CN101946096B - Hydraulic circuit for construction machine - Google Patents

Hydraulic circuit for construction machine Download PDF

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Publication number
CN101946096B
CN101946096B CN200980105395.9A CN200980105395A CN101946096B CN 101946096 B CN101946096 B CN 101946096B CN 200980105395 A CN200980105395 A CN 200980105395A CN 101946096 B CN101946096 B CN 101946096B
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China
Prior art keywords
pressure
relief valve
valve
negative control
control pressure
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CN200980105395.9A
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Chinese (zh)
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CN101946096A (en
Inventor
池生慎一
濑川均
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Nabtesco Corp
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Nabtesco Corp
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    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/20—Drives; Control devices
    • E02F9/22—Hydraulic or pneumatic drives
    • E02F9/2221—Control of flow rate; Load sensing arrangements
    • E02F9/2232—Control of flow rate; Load sensing arrangements using one or more variable displacement pumps
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/20—Drives; Control devices
    • E02F9/22—Hydraulic or pneumatic drives
    • E02F9/2221—Control of flow rate; Load sensing arrangements
    • E02F9/2225—Control of flow rate; Load sensing arrangements using pressure-compensating valves
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/20—Drives; Control devices
    • E02F9/22—Hydraulic or pneumatic drives
    • E02F9/2221—Control of flow rate; Load sensing arrangements
    • E02F9/2239—Control of flow rate; Load sensing arrangements using two or more pumps with cross-assistance
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/20—Drives; Control devices
    • E02F9/22—Hydraulic or pneumatic drives
    • E02F9/2278—Hydraulic circuits
    • E02F9/2285—Pilot-operated systems
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/20—Drives; Control devices
    • E02F9/22—Hydraulic or pneumatic drives
    • E02F9/2278—Hydraulic circuits
    • E02F9/2292—Systems with two or more pumps
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/20—Drives; Control devices
    • E02F9/22—Hydraulic or pneumatic drives
    • E02F9/2278—Hydraulic circuits
    • E02F9/2296—Systems with a variable displacement pump
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
    • F15B11/02—Systems essentially incorporating special features for controlling the speed or actuating force of an output member
    • F15B11/04—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the speed
    • F15B11/042—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the speed by means in the feed line, i.e. "meter in"
    • F15B11/0423—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the speed by means in the feed line, i.e. "meter in" by controlling pump output or bypass, other than to maintain constant speed
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/20—Fluid pressure source, e.g. accumulator or variable axial piston pump
    • F15B2211/205—Systems with pumps
    • F15B2211/2053—Type of pump
    • F15B2211/20546—Type of pump variable capacity
    • F15B2211/20553—Type of pump variable capacity with pilot circuit, e.g. for controlling a swash plate
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/20—Fluid pressure source, e.g. accumulator or variable axial piston pump
    • F15B2211/205—Systems with pumps
    • F15B2211/20576—Systems with pumps with multiple pumps
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/30—Directional control
    • F15B2211/305—Directional control characterised by the type of valves
    • F15B2211/30505—Non-return valves, i.e. check valves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/30—Directional control
    • F15B2211/305—Directional control characterised by the type of valves
    • F15B2211/30505—Non-return valves, i.e. check valves
    • F15B2211/30515—Load holding valves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/30—Directional control
    • F15B2211/305—Directional control characterised by the type of valves
    • F15B2211/30525—Directional control valves, e.g. 4/3-directional control valve
    • F15B2211/3053—In combination with a pressure compensating valve
    • F15B2211/30535—In combination with a pressure compensating valve the pressure compensating valve is arranged between pressure source and directional control valve
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/30—Directional control
    • F15B2211/305—Directional control characterised by the type of valves
    • F15B2211/3056—Assemblies of multiple valves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/30—Directional control
    • F15B2211/31—Directional control characterised by the positions of the valve element
    • F15B2211/3105—Neutral or centre positions
    • F15B2211/3111—Neutral or centre positions the pump port being closed in the centre position, e.g. so-called closed centre
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/30—Directional control
    • F15B2211/31—Directional control characterised by the positions of the valve element
    • F15B2211/3105—Neutral or centre positions
    • F15B2211/3116—Neutral or centre positions the pump port being open in the centre position, e.g. so-called open centre
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/30—Directional control
    • F15B2211/31—Directional control characterised by the positions of the valve element
    • F15B2211/3122—Special positions other than the pump port being connected to working ports or the working ports being connected to the return line
    • F15B2211/3127—Floating position connecting the working ports and the return line
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/30—Directional control
    • F15B2211/32—Directional control characterised by the type of actuation
    • F15B2211/329—Directional control characterised by the type of actuation actuated by fluid pressure
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/40—Flow control
    • F15B2211/405—Flow control characterised by the type of flow control means or valve
    • F15B2211/40507—Flow control characterised by the type of flow control means or valve with constant throttles or orifices
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/40—Flow control
    • F15B2211/46—Control of flow in the return line, i.e. meter-out control
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/50—Pressure control
    • F15B2211/505—Pressure control characterised by the type of pressure control means
    • F15B2211/50509—Pressure control characterised by the type of pressure control means the pressure control means controlling a pressure upstream of the pressure control means
    • F15B2211/50518—Pressure control characterised by the type of pressure control means the pressure control means controlling a pressure upstream of the pressure control means using pressure relief valves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/50—Pressure control
    • F15B2211/515—Pressure control characterised by the connections of the pressure control means in the circuit
    • F15B2211/5151—Pressure control characterised by the connections of the pressure control means in the circuit being connected to a pressure source and a directional control valve
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/50—Pressure control
    • F15B2211/515—Pressure control characterised by the connections of the pressure control means in the circuit
    • F15B2211/5156—Pressure control characterised by the connections of the pressure control means in the circuit being connected to a return line and a directional control valve
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/50—Pressure control
    • F15B2211/55—Pressure control for limiting a pressure up to a maximum pressure, e.g. by using a pressure relief valve
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/60—Circuit components or control therefor
    • F15B2211/605—Load sensing circuits
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/60—Circuit components or control therefor
    • F15B2211/605—Load sensing circuits
    • F15B2211/6051—Load sensing circuits having valve means between output member and the load sensing circuit
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/60—Circuit components or control therefor
    • F15B2211/635—Circuits providing pilot pressure to pilot pressure-controlled fluid circuit elements
    • F15B2211/6355—Circuits providing pilot pressure to pilot pressure-controlled fluid circuit elements having valve means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/705—Output members, e.g. hydraulic motors or cylinders or control therefor characterised by the type of output members or actuators
    • F15B2211/7051—Linear output members
    • F15B2211/7053—Double-acting output members
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/705—Output members, e.g. hydraulic motors or cylinders or control therefor characterised by the type of output members or actuators
    • F15B2211/7058—Rotary output members
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/71—Multiple output members, e.g. multiple hydraulic motors or cylinders
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/71—Multiple output members, e.g. multiple hydraulic motors or cylinders
    • F15B2211/7114—Multiple output members, e.g. multiple hydraulic motors or cylinders with direct connection between the chambers of different actuators
    • F15B2211/7128—Multiple output members, e.g. multiple hydraulic motors or cylinders with direct connection between the chambers of different actuators the chambers being connected in parallel
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/75—Control of speed of the output member
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/77—Control of direction of movement of the output member
    • F15B2211/7741—Control of direction of movement of the output member with floating mode, e.g. using a direct connection between both lines of a double-acting cylinder

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mining & Mineral Resources (AREA)
  • Civil Engineering (AREA)
  • Structural Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Mechanical Engineering (AREA)
  • Fluid-Pressure Circuits (AREA)
  • Operation Control Of Excavators (AREA)

Abstract

Negative control of a split pump having a single swash plate consumes less energy than conventional negative control. A hydraulic circuit (1) for a construction machine is adapted for control of a split pump (111) the discharge volume of which can be reduced according to the magnitude of an external signal pressure. The hydraulic circuit (1) is provided with switching valves (118, 124) for controlling actuators (119, 120, 125, 126, 127), and also with control valves (115, 116) which can feedback, as external signal pressures, back pressures caused by the center bypass flow rates of two systems to the split pump (111). Further, the hydraulic circuit (1) is constructed such that, of the external signal pressures, a minimum pressure (external signal pressure (114)) selected by a low-pressure selecting valve (131) is fed back to the split pump (111).

Description

The oil hydraulic circuit of building machinery
Technical field
The present invention relates to adopt two mouthfuls of oil hydraulic circuits of discharging the building machinery of formula diverter pump of a cylinder of variable capacity type.Particularly relate to the oil hydraulic circuit that is applicable to small building machineries such as mini-excavator.
Background technique
In the past, the back pressure that extensive utilization is produced by the size of the middle roadside through-current capacity of control valve, a plurality of variable capacity type reciprocating pumps are carried out negative control (negative control), because described a plurality of pumps have swash plate separately, and can distinguish the control pump capacity, so consumption state according to the action oil of discharging from each pump, and carry out only control by the swash plate to each pump, can only discharge the flow (for example with reference to patent documentation 1: Japan Patent open communique spy open flat 5-132977 number) that needs.
But, in the oil hydraulic circuit of the building machinery that uses the bypass type variable displacement piston pump (cylinder is discharged the formula diverter pump for two mouthfuls) that only has a swash plate, because pump only has a swash plate, so can not carry out this negative control best.Therefore, in the excavator that adopts open-center hydraulic system, realize that energy-conservation is a problem.
Summary of the invention
In order to solve described problem, even the object of the present invention is to provide a kind of oil hydraulic circuit that under aforesaid way (negative control that only has the diverter pump of a swash plate), also can realize the building machinery more energy-conservation than prior art.
In order to solve described problem, the invention provides a kind of oil hydraulic circuit of building machinery, the oil hydraulic circuit of described building machinery is used for the control diverter pump, described diverter pump is from a swash plate and two kinds of flows that oil hydraulic cylinder seat discharge capacity equates, and described diverter pump can make the discharge capacity reduce according to the size of external signal pressure, it is characterized in that comprising: control valve, described control valve has a plurality of switching valves of a plurality of hydraulic drive mechanisms of control, and described control valve can feed back as external signal pressure the main back pressure that is produced by the middle roadside through-current capacity of two systems to described diverter pump, and the oil hydraulic circuit of described building machinery can be to described diverter pump feedback by the pressure minimum in described a plurality of external signal pressure of low pressure selector valve selection.
In addition, the invention described above also is the oil hydraulic circuit of building machinery as described below, and it comprises: the first release path is connected with an exhaust port of the diverter pump with discharge flow rate (discharge capacity) control gear (for example having regulator); The first direction switching valve of first system is connected with the described first release path; The second release path is connected with another exhaust port of described diverter pump; The second direction switching valve of second system is connected with the described second release path; And low pressure selector valve, oil pressure low in the first negative control pressure and the second negative control pressure is exported as the 3rd negative control pressure, the described first negative control pressure is the oil pressure (back pressure) of the described first release path in described first direction switching valve downstream, the described second negative control pressure is the oil pressure (back pressure) of the described second release path in described second direction switching valve downstream, and by described discharge flow rate control gear (for example regulator), feed back described the 3rd negative control pressure from described low pressure selector valve to described diverter pump.
Structure according to the invention described above, for example when the discharge flow rate of carrying out any one pump discharge is trickle when operation that gets final product on a small quantity or does not make the release of hydraulic drive mechanism action, can reduce the discharge flow rate of pump, and reduce roadside through-current capacity in the happy formula, and then can reduce the residual flow that pump is discharged, thereby realize energy-conservationization, fuel savingization.In addition, rise owing to can reduce the temperature of hydraulic system, the degradation speed of action oil is postponed, and can reduce fuel tank fuel quantity, so can effectively utilize resource.And, owing to discharge the necessary flow of minimum, so reduced the running noise of pump, make noise lower.
In addition, in the present invention preferably, described diverter pump has the regulator of control discharge capacity, one during the middle roadside of described two systems is logical is the first release path that is connected with an exhaust port of described diverter pump, logical another in the middle roadside of described two systems is the second release path that is connected with another exhaust port of described diverter pump, described a plurality of switching valve is the first direction switching valve of first system that is connected with the described first release path and the second direction switching valve of second system that is connected with the described second release path, the oil hydraulic circuit of described building machinery also comprises: fuel tank is communicated with the described first release path and the described second release path; First throttle portion is arranged on the described first release path between described first direction switching valve and the described fuel tank; And second restriction, be arranged on the described second release path between described second direction switching valve and the described fuel tank, described low pressure selector valve is exported low in the first negative control pressure and second a negative control pressure oil pressure as the 3rd negative control pressure, the described first negative control pressure is the oil pressure as the described first throttle portion upstream of described external signal pressure, the described second negative control pressure is the oil pressure as the described second restriction upstream of described external signal pressure, described pressure minimum is described the 3rd negative control pressure, the oil hydraulic circuit of described building machinery also comprises first pressure-relief valve, when the described second negative control pressure of the described first negative control pressure ratio is high, described first pressure-relief valve from the described first release path of described first direction switching valve upstream to the oil of described fuel tank discharging with the pressure difference corresponding amount of the described first negative control pressure and the described second negative control pressure.
According to this configuration, when not using first system or when necessary flow-rate ratio second system of first system after a little while, can discharge the residual oil of the first release path of first system that will flow through from first pressure-relief valve to fuel tank.
In addition, in the present invention preferably, also comprise second pressure-relief valve, when the described first negative control pressure of the described second negative control pressure ratio is high, described second pressure-relief valve from the described second release path of described second direction switching valve upstream to the oil of described fuel tank discharging with the pressure difference corresponding amount of the described first negative control pressure and the described second negative control pressure.
According to this configuration, second system is also identical with first system, when not using second system or when necessary flow-rate ratio first system of second system after a little while, can discharge the residual oil of the second release path of second system that will flow through from second pressure-relief valve to fuel tank.
In addition, in the present invention preferably, described second pressure-relief valve has lap position and is communicated with the position, import the described second negative control pressure to first Room of described second pressure-relief valve, import described the 3rd negative control pressure to another chamber of described second pressure-relief valve, and described second pressure-relief valve disposes the second pressure-relief valve spring, when described the 3rd negative control pressure of the described second negative control pressure ratio and described second pressure-relief valve were high with the pressing force sum of spring, described second pressure-relief valve was in and is communicated with the position.
Wherein, if operated the first direction switching valve, make the first negative control pressure ratio, the second negative control pressure low, then the discharge flow rate of diverter pump increases, and the residual flow of the oil of the second release path of flowing through increases.At this moment, if follow the reduction of the first negative control pressure, reduce from the pressing force of another chamber of second pressure-relief valve, make from the pressing force of a chamber and win, then this second pressure-relief valve moves to and is communicated with the position.Thus, the residual oil of the second release path of will flowing through can be discharged from second pressure-relief valve to fuel tank, thereby the energy loss in second restriction can be reduced in.
In addition, in the present invention preferably, described first pressure-relief valve has lap position and is communicated with the position, import the described first negative control pressure to first Room of described first pressure-relief valve, import described the 3rd negative control pressure to another chamber of described first pressure-relief valve, and described first pressure-relief valve disposes the first pressure-relief valve spring, when described the 3rd negative control pressure of the described first negative control pressure ratio and described first pressure-relief valve were high with the pressing force sum of spring, described first pressure-relief valve was in and is communicated with the position.
Wherein, if operated the second direction switching valve, make the second negative control pressure ratio, the first negative control pressure low, then the discharge flow rate of diverter pump increases, and the residual flow of the oil of the first release path of flowing through increases.At this moment, if follow the reduction of the second negative control pressure, reduce from the pressing force of another chamber of first pressure-relief valve, make from the pressing force of a chamber and win, then this first pressure-relief valve moves to and is communicated with the position.Thus, the residual oil of the first release path of will flowing through can be discharged from first pressure-relief valve to fuel tank, thereby the energy loss in the first throttle portion can be reduced in.
In addition, in the present invention preferably, when whole direction switching valve of described first system and described second system was all operated, described second pressure-relief valve was oily to described fuel tank discharging from the described second release path of described second direction switching valve upstream.
According to this configuration, when not having the direction of operating switching valve, also can discharge the residual oil of the second release path of will flowing through from second pressure-relief valve to fuel tank, thereby further be reduced in the energy loss in second restriction.
In addition, in the present invention preferably, when whole direction switching valve of described first system and described second system was all operated, described first pressure-relief valve was oily to described fuel tank discharging from the described first release path of described first direction switching valve upstream.
According to this configuration, when not having the direction of operating switching valve, also can discharge the residual oil of the first release path of will flowing through from first pressure-relief valve to fuel tank, thereby can be reduced in the energy loss in the first throttle portion.
In addition, in the present invention preferably, also comprise: first guide (pilot) path, the one end is connected with guide (pilot) pump, and the other end is connected with described fuel tank; A plurality of Auxiliary valvess are wholely set respectively on whole direction switching valve of described first system and described second system, and are arranged in series on the described first first guiding path; And the not operation signal generates valve, an one chamber is connected with the described first first guiding path that described Auxiliary valves than upstream more relies on the upstream, dispose press device in another chamber, when the described direction switching valve of correspondence is in the neutral position, described Auxiliary valves is in and is communicated with the position, when the described direction switching valve of correspondence is in switching position, described Auxiliary valves is in lap position, when at least one described Auxiliary valves is in lap position, described not operation signal generates valve all is connected second Room of described first pressure-relief valve and described second pressure-relief valve with described fuel tank, when whole described Auxiliary valvess all was in the connection position, described not operation signal generates valve all was connected described second Room with described pioneer pump.
According to this configuration, when whole Auxiliary valvess all was in the connection position, the not operation signal generates valve all was connected second Room of first pressure-relief valve and second pressure-relief valve with pioneer pump.Thus, first pressure-relief valve and second pressure-relief valve are switched to the connection position from lap position.Therefore, generate valve by increasing a not operation signal, just can switch to the operation of the connection position of first pressure-relief valve and second pressure-relief valve.
In addition, in the present invention preferably, when whole direction switching valve of described first system and described second system was all operated, described not operation signal generated the hydraulic pressure signal that valve output makes discharge flow rate (discharge capacity) minimizing of described diverter pump.
According to this configuration, when not having the direction of operating switching valve, reduce by the discharge flow rate that makes diverter pump, can reduce the energy loss when not having the direction of operating switching valve.
In addition, in the present invention preferably, also comprise: the second first guiding path, one end generate valve with described not operation signal and are connected, and the other end is connected with described low pressure selector valve; And shuttle valve, be arranged on the described second first guiding path, select described not operation signal to generate the output of valve and the high oil pressure in described the 3rd negative control pressure, and export described oil pressure to described regulator.
According to this configuration, by being also used as regulator with signal and pressure-relief valve signal from the signal of not operation signal generation valve, can simplify oil hydraulic circuit.
In addition, in the present invention preferably, the hydraulic pressure signal that is input to a chamber of described not operation signal generation valve is used as the auto idle speed signal of Eng ine Idling Control.
According to this configuration, by generating signal and the auto idle speed signal dual-purpose of valve for the not operation signal, can simplify oil hydraulic circuit.
In addition, in the present invention preferably, also comprise pressure-relief valve lap position retaining mechanism, when the described first negative control pressure makes the discharge flow rate (discharge capacity) of described diverter pump be maximum, described pressure-relief valve lap position retaining mechanism remains on described first pressure-relief valve on the lap position, and when the described second negative control pressure made the discharge flow rate (discharge capacity) of described diverter pump be maximum, described pressure-relief valve lap position retaining mechanism remained on described second pressure-relief valve on the lap position.
According to this configuration, when the first negative control pressure makes the discharge flow rate of diverter pump be maximum, described pressure-relief valve lap position retaining mechanism remains on first pressure-relief valve on the lap position, and when the second negative control pressure makes the discharge flow rate of diverter pump be maximum, described pressure-relief valve lap position retaining mechanism remains on second pressure-relief valve on the lap position, thus, in any one system of first system and second system, in this system, need under the situation of the oil mass more than the discharge flow rate of diverter pump, the pressure-relief valve of this system is remained on the lap position.Therefore, the flow of the system that needs the above oil mass of diverter pump discharge flow rate is reduced.That is to say the operating characteristics of the hydraulic drive mechanism the when discharge flow rate that can improve diverter pump is maximum.
In addition, in the present invention preferably, described first pressure-relief valve has lap position and is communicated with the position, import the described first negative control pressure to first Room of described first pressure-relief valve, import described the 3rd negative control pressure to another chamber of described first pressure-relief valve, and described first pressure-relief valve disposes the first pressure-relief valve spring, when described the 3rd negative control pressure of the described first negative control pressure ratio and described first pressure-relief valve are high with the pressing force sum of spring, described first pressure-relief valve is in and is communicated with the position, described second pressure-relief valve has lap position and is communicated with the position, import the described second negative control pressure to first Room of described second pressure-relief valve, import described the 3rd negative control pressure to another chamber of described second pressure-relief valve, and described second pressure-relief valve disposes the second pressure-relief valve spring, when described the 3rd negative control pressure of the described second negative control pressure ratio and described second pressure-relief valve are high with the pressing force sum of spring, described second pressure-relief valve is in and is communicated with the position, described pressure-relief valve lap position retaining mechanism is arranged between another chamber and described low pressure selector valve of described first pressure-relief valve and described second pressure-relief valve, and described pressure-relief valve lap position retaining mechanism comprises: first check valve, from described low pressure selector valve towards the direction of described two pressure-relief valves as forward; And second check valve, from described two pressure-relief valves towards the direction of described low pressure selector valve as forward, when described the 3rd negative control pressure was higher than the discharge flow rate (discharge capacity) that makes described diverter pump for maximum pressure, described second check valve was opened.
According to this configuration, by having two simple structures that check valve is such, can form pressure-relief valve lap position retaining mechanism.
In addition, in the present invention preferably, described diverter pump has the regulator of control discharge capacity, one during the middle roadside of described two systems is logical is the first release path that is connected with an exhaust port of described diverter pump, logical another in the middle roadside of described two systems is the second release path that is connected with another exhaust port of described diverter pump, described a plurality of switching valve is the first direction switching valve of first system that is connected with the described first release path and the second direction switching valve of second system that is connected with the described second release path, the oil hydraulic circuit of described building machinery also comprises: fuel tank is communicated with the described first release path and the described second release path; First throttle portion is arranged on the described first release path between described first direction switching valve and the described fuel tank; And second restriction, be arranged on the described second release path between described second direction switching valve and the described fuel tank, described low pressure selector valve is exported low in the first negative control pressure and second a negative control pressure oil pressure as the 3rd negative control pressure, the described first negative control pressure is the oil pressure as the described first throttle portion upstream of described external signal pressure, the described second negative control pressure is the oil pressure as the described second restriction upstream of described external signal pressure, described pressure minimum is described the 3rd negative control pressure, the oil hydraulic circuit of described building machinery also comprises pressure-relief valve, when the described second negative control pressure of the described first negative control pressure ratio is high, described pressure-relief valve from the described first release path of described first direction switching valve upstream to the oil of described fuel tank discharging with the pressure difference corresponding amount of the described first negative control pressure and the described second negative control pressure, when the described first negative control pressure of the described second negative control pressure ratio is high, described pressure-relief valve from the described second release path of described second direction switching valve upstream to the oil of described fuel tank discharging with the pressure difference corresponding amount of the described first negative control pressure and the described second negative control pressure.
According to this configuration, when not using first system or when necessary flow-rate ratio second system of first system after a little while, can discharge the residual oil of the first release path of first system that will flow through from pressure-relief valve to fuel tank.In addition, second system is also identical with first system, when not using second system or when necessary flow-rate ratio first system of second system after a little while, the discharging residual oil of the second release path of second system of will flowing through from pressure-relief valve to fuel tank.
In addition, owing to be not in first system and second system, pressure-relief valve to be set respectively, get final product but in these two systems, a pressure-relief valve only is set, thus the quantity of valve can be reduced, thus can simplify oil hydraulic circuit.
In addition, in the present invention preferably, described pressure-relief valve has: the neutral position, interdict being communicated with between the described first release path and the described second release path and the described fuel tank; First switching position makes the described first release path be communicated with described fuel tank, and interdicts the connection between the described second release path and the described fuel tank; And second switching position, interdict the connection between the described first release path and the described fuel tank, and the described second release path is communicated with described fuel tank, import the described first negative control pressure to a chamber of described pressure-relief valve, import the described second negative control pressure to another chamber of described pressure-relief valve, when the described second negative control pressure of the described first negative control pressure ratio is high, described pressure-relief valve is in described first switching position, when the described first negative control pressure of the described second negative control pressure ratio was high, described pressure-relief valve was in described second switching position.
At this, if for example operated the second direction switching valve, make the second negative control pressure ratio, the first negative control pressure low, then the discharge flow rate of diverter pump increases, and the residual flow of the oil of the first release path of flowing through increases.At this moment, pressure-relief valve moves to first switching position.Thus, the residual oil of the first release path of will flowing through can be discharged from pressure-relief valve to fuel tank, thereby the energy loss in the first throttle portion can be reduced in.
Equally, if operated the first direction switching valve, make the first negative control pressure ratio, the second negative control pressure low, then the discharge flow rate of diverter pump increases, and the residual flow of the oil of the second release path of flowing through increases.At this moment, pressure-relief valve moves to second switching position.Thus, the residual oil of the second release path of will flowing through can be discharged from pressure-relief valve to fuel tank, thereby the energy loss in second restriction can be reduced in.
In addition, as long as owing to have two first guiding paths that are connected with above-mentioned pressure-relief valve, so can simplify oil hydraulic circuit.
In addition, in the present invention preferably, also comprise: neutral pressure-relief valve, be connected with the second shunting release path with the first shunting release path, the described first shunting release path is from the described first release path shunting between described diverter pump and the described first direction switching valve, the described second shunting release path is from the described second release path shunting between described diverter pump and the described second direction switching valve, when whole direction switching valve of described first system and described second system was all operated, described neutral pressure-relief valve discharged oil from the described first release path of described first direction switching valve upstream and the described second release path of described second direction switching valve upstream to described fuel tank.
According to this configuration, when not having the direction of operating switching valve, the residual oil of will the flow through first release path and the second release path can be discharged from above-mentioned neutral pressure-relief valve to fuel tank, thereby the energy loss in first throttle portion and second restriction can be further be reduced in.
In addition, in the present invention preferably, also comprise: the first first guiding path, the one end is connected with pioneer pump, and the other end is connected with described fuel tank; A plurality of Auxiliary valvess are wholely set respectively on whole direction switching valve of described first system and described second system, and are arranged in series on the described first first guiding path; And the not operation signal generates valve, an one chamber is connected with the described first first guiding path that described Auxiliary valves than upstream more relies on the upstream, dispose press device in another chamber, when the described direction switching valve of correspondence is in the neutral position, described Auxiliary valves is in and is communicated with the position, when the described direction switching valve of correspondence is in switching position, described Auxiliary valves is in lap position, when at least one described Auxiliary valves is in lap position, described not operation signal generates valve makes the pilot chamber of described neutral pressure-relief valve be connected with described fuel tank, and make described neutral pressure-relief valve be in lap position, when whole described Auxiliary valvess all is in the connection position, described not operation signal generates valve makes described pilot chamber be connected with described pioneer pump, and makes described neutral pressure-relief valve be in the connection position.
According to this configuration, when whole Auxiliary valvess all was in the connection position, the not operation signal generates valve made the pilot chamber of neutral pressure-relief valve be connected with pioneer pump.Thus, neutral pressure-relief valve switches to from lap position and is communicated with the position.Therefore, by increasing a neutral pressure-relief valve and a not operation signal generation valve, just can when not having the direction of operating switching valve, discharge the oil of the first release path and the second release path.
In addition, in the present invention preferably, when whole direction switching valve of described first system and described second system was all operated, described not operation signal generated the hydraulic pressure signal that valve output makes discharge flow rate (discharge capacity) minimizing of described diverter pump.
According to this configuration, when not having the direction of operating switching valve, reduce by the discharge flow rate that makes diverter pump, can reduce the energy loss when not having the direction of operating switching valve.
In addition, in the present invention preferably, also comprise: the second first guiding path, one end generate valve with described not operation signal and are connected, and the other end is connected with described low pressure selector valve; And shuttle valve, be arranged on the described second first guiding path, select described not operation signal to generate high oil pressure in the output of valve and described the 3rd negative control pressure, and export described oil pressure to described regulator.
According to this configuration, be also used as regulator with signal and pressure-relief valve signal by making the signal from not operation signal generation valve, can simplify oil hydraulic circuit.
In addition, in the present invention preferably, the hydraulic pressure signal that is input to a chamber of described not operation signal generation valve is used as the auto idle speed signal of Eng ine Idling Control.
According to this configuration, by generating signal and the auto idle speed signal dual-purpose of valve for the not operation signal, can simplify oil hydraulic circuit.
In addition, in the present invention preferably, also comprise pressure-relief valve lap position retaining mechanism, when the described first negative control pressure makes the discharge flow rate (discharge capacity) of described diverter pump be maximum, described pressure-relief valve lap position retaining mechanism remains on described pressure-relief valve on the position that is communicated with between the described first release path of blocking and the described fuel tank, and when the described second negative control pressure made the discharge flow rate (discharge capacity) of described diverter pump be maximum, described pressure-relief valve lap position retaining mechanism remained on described pressure-relief valve on the position that is communicated with between the described second release path of blocking and the described fuel tank.
According to this configuration, when the first negative control pressure makes the discharge flow rate of diverter pump be maximum, pressure-relief valve is remained on the position that is communicated with between the blocking first release path and the fuel tank, and when the second negative control pressure makes the discharge flow rate of diverter pump be maximum, pressure-relief valve is remained on the position that is communicated with between the blocking second release path and the fuel tank, thus, in any one system of first system and second system, in this system, need under the situation of the oil mass more than the discharge flow rate of diverter pump, in this system from pressure-relief valve discharging oil.Therefore, the flow of the system that needs the above oil mass of diverter pump discharge flow rate is unexpectedly reduced.That is to say the operating characteristics of the hydraulic drive mechanism the when discharge flow rate that can improve diverter pump is maximum.
In addition, in the present invention preferably, described pressure-relief valve has: the neutral position, interdict being communicated with between the described first release path and the described second release path and the described fuel tank; First switching position makes the described first release path be communicated with described fuel tank, and interdicts the connection between the described second release path and the described fuel tank; And second switching position, interdict the connection between the described first release path and the described fuel tank, and the described second release path is communicated with described fuel tank, import the described first negative control pressure to a chamber of described pressure-relief valve, import the described second negative control pressure to another chamber of described pressure-relief valve, when the described second negative control pressure of the described first negative control pressure ratio is high, described pressure-relief valve is in described first switching position, when the described first negative control pressure of the described second negative control pressure ratio is high, described pressure-relief valve is in described second switching position, described pressure-relief valve lap position retaining mechanism comprises: first check valve, be arranged between the chamber of first split point of described first throttle portion upstream and described pressure-relief valve, from described first split point towards the direction of described pressure-relief valve as forward; Second check valve is arranged in parallel with described first check valve, from described pressure-relief valve towards the direction of described first split point as forward; The 3rd check valve is arranged between another chamber of second split point of the described second restriction upstream and described pressure-relief valve, from described second split point towards the direction of described pressure-relief valve as forward; And the 4th check valve, be arranged in parallel with described the 3rd check valve, from described pressure-relief valve towards the direction of described second split point as forward, when the described first negative control pressure is higher than the discharge flow rate (discharge capacity) that makes described diverter pump for maximum pressure, described second check valve is opened, when the described second negative control pressure was higher than the discharge flow rate (discharge capacity) that makes described diverter pump for maximum pressure, described the 4th check valve was opened.
According to this configuration, by having four simple structures that check valve is such, just can form pressure-relief valve lap position retaining mechanism.
According to the present invention, the residual flow that diverter pump is discharged reduces, thereby can realize energy-conservationization, fuel savingization.In addition, rise owing to can reduce the temperature of hydraulic system, the degradation speed of action oil is postponed, and fuel tank fuel quantity is reduced, so can effectively utilize resource.In addition, owing to discharge the necessary flow of minimum, so reduced the running noise of pump, make noise lower.
Description of drawings
Fig. 1 is the circuit diagram of oil hydraulic circuit of the building machinery of expression first embodiment of the invention.
Fig. 2 is the plotted curve that makes the pilot pressure-Flow characteristics under power pump discharge head one stable condition in when control.
Fig. 3 is the plotted curve of middle roadside through-current capacity-pilot pressure characteristic.
Fig. 4 is the plotted curve that changes the pump discharge head-Flow characteristics under the power characteristic situation according to pilot pressure.
Fig. 5 is the plotted curve that changes the pump discharge head-Flow characteristics under the pump capacity situation according to pilot pressure.
Fig. 6 is the circuit diagram of oil hydraulic circuit of the building machinery of expression second embodiment of the invention.
Fig. 7 is the circuit diagram of oil hydraulic circuit of the building machinery of expression third embodiment of the invention.
Fig. 8 is the circuit diagram of oil hydraulic circuit of the building machinery of expression four embodiment of the invention.
Fig. 9 is the circuit diagram of oil hydraulic circuit of the building machinery of expression fifth embodiment of the invention.
Figure 10 is the plotted curve of the open nature of the expression discharge flow rate characteristic of diverter pump and pressure-relief valve.
Figure 11 is the circuit diagram of oil hydraulic circuit of the building machinery of expression sixth embodiment of the invention.
Figure 12 is the circuit diagram of oil hydraulic circuit of the building machinery of expression seventh embodiment of the invention.
The plotted curve that concerns between the first negative control pressure when Figure 13 is expression direction of operating switching valve and the second negative control pressure.
Figure 14 is the circuit diagram of oil hydraulic circuit of the building machinery of expression eighth embodiment of the invention.
Figure 15 is the circuit diagram of oil hydraulic circuit of the building machinery of expression ninth embodiment of the invention.
Figure 16 is the circuit diagram of oil hydraulic circuit of the building machinery of expression tenth embodiment of the invention.
Figure 17 is the circuit diagram of oil hydraulic circuit of the building machinery of expression eleventh embodiment of the invention.
Figure 18 is the circuit diagram of oil hydraulic circuit of the building machinery of expression twelveth embodiment of the invention.
Figure 19 is the circuit diagram of oil hydraulic circuit of the building machinery of expression thirteenth embodiment of the invention.
Description of reference numerals
1, the oil hydraulic circuit of 201 building machineries
2 first pressure-relief valves
3 second pressure-relief valves
4 first release flow control valves
5 second release flow control valves
6x, 6y, 6z first direction switching valve
7x, 7y, 7z second direction switching valve
8 low pressure selector valves
9 first throttle portions
10 second restriction
13 first release paths (middle roadside is logical)
14 second release paths (middle roadside is logical)
51,111 diverter pumps
52 regulators
54 fuel tanks
112 swash plates
115,116 control valves
118,124 switching valves
119,120,125,126,127 hydraulic drive mechanisms
Embodiment
With reference to the accompanying drawings embodiment of the present invention is described.And being example with the oil hydraulic circuit of hydraulic shovel describes the oil hydraulic circuit of building machinery, and mode of execution is as follows.
First mode of execution
Fig. 1 is the circuit diagram of oil hydraulic circuit of the building machinery of expression first embodiment of the invention.At this, pump 111 is bypass type variable displacement piston pump (diverter pumps), this bypass type variable displacement piston pump is chimeric on an oil hydraulic cylinder seat by input shaft and spline be combined into an even number piston, discharge the liquid of equal capacity, and have a swash plate 112, and pump 111 has also be used to the constant-torque control mechanism 142 that effectively utilizes engine power.This constant-torque control mechanism 142 is widely used in building machinery, particularly mini-excavator etc., this constant-torque control mechanism 142 is according to the summation of a plurality of head pressures and further according to the head pressure of attached constant discharge capacity type pump 113, change the angle of swash plate 112, thereby the axle input torque to pump is controlled, so that it is no more than certain moment of torsion.
Characteristic shown in Figure 2 is based on external signal pressure 114, by increase constant-torque control mechanism 142 (for example regulators) in this pump 111, under the certain situation of the head pressure that makes pump 111, with respect to the capacity characteristic of the pump 111 of external signal pressure 114.For example, as Fig. 4 or shown in Figure 5, the characteristic 151,161 the when Flow characteristics with respect to head pressure of the pump 111 that is produced by this mechanism can be zero from external signal pressure 114 becomes the characteristic 152,162 that the discharge flow rate that makes pump 111 reduces.This characteristic 152 of known realization, 162 method are to utilize the control mechanism of variable capacity type reciprocating pump, so omitted detailed description.And Fig. 3 is the figure that concerns between roadside through-current capacity and the pilot pressure (negative control pressure) in the expression.As shown in Figure 3, middle roadside through-current capacity is more many, and pilot pressure (negative control pressure) becomes more big.
And, reference character 123,130 expression control valves 115,116 negative control pressure line, in addition, reference character 132 is that for example rotating motor and bulldozer oil hydraulic cylinder (Dozer cylinder) are used control valve, reference character 133,134 is represented rotating motor, bulldozer oil cylinder respectively, and reference character 135 is safety valves.In addition, reference character 136 expression main safety valves.
In addition, in Fig. 2, Fig. 4 and Fig. 5, pump discharge flow rate Q1, Q2 represent the discharge flow rate of pump 111,111a, and pumping pressure P1, P2 represent the pumping pressure of pump 111,111a.And, though be recited as pump 111,111a, be not to have diverse two pumps.Constituted the pump 111 (cylinder is discharged the formula diverter pump for two mouthfuls) with a swash plate 112 by pump 111 and pump 111a.
In order to drive a plurality of hydraulic drive mechanisms 119,120,125,126,127, control valve 115,116 each discharge flow rate with pump 111 are divided into two-way, and has the control valve of being configured in 115, a plurality of switching valves 118 on 116,124 (in other words, the first direction switching valve that a plurality of switching valves 118 are first systems, the second direction switching valve that a plurality of switching valves 124 are second systems), according to described switching valve 118,124 operation amount, middle roadside is road 13 all, 14 opening (not shown) diminishes, thereby to hydraulic drive mechanism 119,120,125,126,127 direct traffic.In other words, middle roadside road 13 all is the first release paths that are connected with an exhaust port of diverter pump, and middle roadside road 14 all is the second release paths that are connected with another exhaust port of diverter pump.
Therefore, for example make discharge flow rate flow, consume under the situation of flow to the hydraulic drive mechanism 119 of correspondence by operation switching valve 118, having only remaining oil to flow to reservoir port 121.Therefore, in whole hydraulic drive mechanism 119,120,125,126,127, under the situation of the discharge flow rate that does not have all to consume pump 111, whole residual oils flow back in the fuel tank 54 by control valve 115,116 reservoir port 121,128.At this moment, the energy loss that generation is corresponding with the head pressure of Fuel Oil Remaining and pump 111, the problem when realization is energy-conservation in the oil hydraulic circuit of building machinery is exactly how to reduce this Fuel Oil Remaining.
In the past, using for the control valve 115 of the happy formula of this pump 111 of control (bypass type variable displacement piston pump), 116 oil hydraulic circuit, because the swash plate 112 of pump 111 only has one and pump 111 to discharge the oil of equal capacity substantially from two exhaust ports of pump 111 all the time, so can not the discharge capacity of each pump, for example pump 111,111a the most compatibly be reduced according to two control valves 115 of flowing through, 116 reservoir port 121,128 flow.
But, in the oil hydraulic circuit 1 of the building machinery of as shown in Figure 1 first embodiment of the invention (following " oil hydraulic circuit of building machinery " abbreviated as " oil hydraulic circuit "), be provided with fixed restriction portion 9,10 in these two control valves 115,116 reservoir port 121,128 downstream, and be provided with the safety valve 140,141 that this fixed restriction portion 9,10 is shunted.Thus, produce with flow through in roadside road 13, back pressure that 14 Fuel Oil Remaining is corresponding all.And, the little back pressure (pressure minimum) of utilizing low pressure selector valve 131 to select in these back pressures, by the external signal pressure 114 of this pressure minimum as pump 111 is read in the constant-torque control mechanism 142, for example when the standby time that does not have the operating operation bar or micromanipulation etc. also control valve 115,116 any one in produce under the residue oil condition, by reducing the discharge flow rate of pump 111, can realize energy-conservation.And in low pressure selector valve 131, even under the situation that control valve 115,116 back pressure equate, also the external pilot mouth to pump 111 guides any one pressure.
And, fixed restriction portion 9 is equivalent to be arranged on the first throttle portion on the first release path (middle roadside is road 13 all) between first direction switching valve (switching valve 118) and the fuel tank 54, and fixed restriction portion 10 is equivalent to be arranged on second restriction on the second release path (middle roadside is road 14 all) between second direction switching valve (switching valve 124) and the fuel tank 54.In addition, be configured in the switching valve 118 in downstream in a plurality of switching valves 118 (in flowing through roadside the downstream of the flow direction of the oil on road 13) all and the middle roadside between the fixed restriction portion 9 all the oil pressure on road 13 be the first negative control pressure, be configured in the switching valve 124 in downstream in a plurality of switching valves 124 (in flowing through roadside the downstream of the flow direction of the oil on road 14) all and the middle roadside between the fixed restriction portion 10 all the oil pressure on road 14 be the second negative control pressure.This first negative control pressure is directed to low pressure selector valve 131, the second negative control pressure via negative control pressure line 130 via negative control pressure line 123, is directed to low pressure selector valve 131.In addition, the pressure minimum of being selected by low pressure selector valve 131 (lower pressure in the first negative control pressure and the second negative control pressure) to 142 outputs of constant-torque control mechanism is the 3rd negative control pressure.
Second mode of execution
Fig. 6 is the circuit diagram of the oil hydraulic circuit 201 of expression second embodiment of the invention.As shown in Figure 6, adopted the hydraulic shovel of this oil hydraulic circuit 201 to comprise: diverter pump 51, the regulator 52 with discharge flow rate (the discharge capacity of diverter pump) of pilot pressure oil; Pioneer pump 53; Mobile with left side oil hydraulic motor 55 (moving left motor 55); Elevator boom rack oil hydraulic cylinder 56; Scraper bowl oil hydraulic cylinder 57; Arm oil hydraulic cylinder 58; Rotate with oil hydraulic motor 59; Mobile with right side oil hydraulic motor 60 (motor 60 moves right); And fuel tank 54.And these fluid pressure motors (55,59,60) and oil hydraulic cylinder hydraulic drive mechanism, pump (51,53) and regulators 52 such as (56～58) are combined into oil hydraulic circuit 201.
Diverter pump 51 is two mouthfuls of pumps of discharging formula of a cylinder of variable capacity type, discharges the pressure oil of same traffic from two exhaust port 51a, 51b.And diverter pump 51 is driven by motor (not shown).
The structure of oil hydraulic circuit
The release path
As shown in Figure 6, oil hydraulic circuit 201 comprises: the first release path 13 is connected with an exhaust port 51a of diverter pump 51; And the second release path 14, be connected with another exhaust port 51b of diverter pump 51.The first release path 13 and the second release path 14 collaborate in the downstream, and are connected with drain passageway 71, thereby are communicated with fuel tank 54.The first release path 13 is release paths of first system, and the second release path 14 is release paths of second system.
The direction switching valve
Oil hydraulic circuit 201 comprises: three first direction switching valve 6x～6z of first system are connected with the first release path 13; And three second direction switching valve 7x～7z of second system, be connected with the second release path 14.First direction switching valve 6x～6z and second direction switching valve 7x～7z all are the direction switching valves of the logical type in middle roadside and are the direction switching valves of hydraulic pilot type.In addition, first direction switching valve 6x～6z is arranged in series on the first release path 13, and second direction switching valve 7x～7z is arranged in series on the second release path 14.
Wherein, first direction switching valve 6x is to offering the valve that the pressure oil that moves left motor 55 is controlled, first direction switching valve 6y is to offering the valve that the elevator boom rack that makes elevator boom rack action is controlled with the pressure oil of oil hydraulic cylinder 56, and first direction switching valve 6z is to offering the valve that scraper bowl that scraper bowl is moved is controlled with the pressure oil of oil hydraulic cylinder 57.
In addition, second direction switching valve 7x is the valve that the pressure oil that offers the motor 60 that moves right is controlled, second direction switching valve 7y rotates the valve of controlling with the pressure oil of oil hydraulic motor 59 to offering, and second direction switching valve 7z is to offering the valve that the arm that makes arm movement is controlled with the pressure oil of oil hydraulic cylinder 58.
Wherein, in first direction switching valve 6x～6z, on the first direction switching valve 6z and the first release path 13 between the drain passageway 71 in downstream, be provided with first throttle portion 9.Equally, in second direction switching valve 7x～7z, on the second direction switching valve 7z and the second release path 14 between the drain passageway 71 in downstream, be provided with second restriction 10.
In addition, on whole direction switching valve 6x～7z of first system and second system, be formed with Auxiliary valves 11x～12z respectively.Auxiliary valves 11x～12z is the valve of the logical type in middle roadside.And an end of the first first guiding path 18 is connected with pioneer pump 53, the other end is connected with fuel tank 54 by drain passageway 71, and this first first guiding path 18 is arranged on the oil hydraulic circuit 201.Auxiliary valves 11x～12z is arranged in series on this first first guiding path 18.And when the direction switching valve 6x～7z of correspondence is in the neutral position (when not operating), Auxiliary valves 11x～12z is positioned at and is communicated with the position, and when direction switching valve 6x～7z is in switching position (during operation), Auxiliary valves 11x～12z is positioned at lap position.
The low pressure selector valve
In addition, oil hydraulic circuit 201 has low pressure selector valve 8, and this low pressure selector valve 8 is exporting as the 3rd negative control pressure as lower oil pressure in the first negative control pressure of first throttle portion 9 upstream oil pressure and the second negative control pressure as second restriction, 10 upstream oil pressure.At this, to a chamber 81 input first direction switching valve 6z of low pressure selector valve 8 and the above-mentioned first negative control pressure of the conduct first release path 13 oil pressure between the first throttle portion 9, to another chamber 82 input second direction switching valve 7z of low pressure selector valve 8 and the above-mentioned second negative control pressure of the conduct second release path 14 oil pressure between second restriction 10.
In addition, oil hydraulic circuit 201 is provided with the regulator that connects low pressure selector valve 8 and regulator 52 with first guiding path 16.Utilize this regulator with first guiding path 16, import from the 3rd negative control pressure of low pressure selector valve 8 outputs to regulator 52.
Pressure-relief valve
In addition, oil hydraulic circuit 201 has first pressure-relief valve 2, when the first negative control pressure ratio, the second negative control pressure is high, this first pressure-relief valve 2 will with the oil of the pressure difference corresponding amount of this first negative control pressure and this second negative control pressure, more rely on the first release path 13 of upstream to fuel tank 54 dischargings from the first direction switching valve 6x than upstream.The upstream passages 74 of first pressure-relief valve 2 is connected with the first release path 13 of first direction switching valve 6x upstream, and the downstream passages 72 of first pressure-relief valve 2 is connected with drain passageway 71.
Wherein, first pressure-relief valve 2 has lap position 2b and is communicated with position 2a, to first Room, 21 inputs, first a negative control pressure of this first pressure-relief valve 2, to another chamber 23 inputs the 3rd negative control pressure of this first pressure-relief valve 2, and first pressure-relief valve 2 disposes first pressure-relief valve spring 24.When this first negative control pressure ratio the 3rd negative control pressure and first pressure-relief valve used the pressing force sum of spring 24 high, first pressure-relief valve 2 was in and is communicated with position 2a.At this, be in the non-vanishing state of opening area that the state that is communicated with position 2a refers to first pressure-relief valve 2, that is to say, be not that the opening area that only refers to valve is maximum state (the second following pressure-relief valve 3 is also identical).In addition, another chamber 23 of first pressure-relief valve 2 is communicated with low pressure selector valve 8 with path 76 by the 3rd negative control pressure.
Equally, oil hydraulic circuit 201 has second pressure-relief valve 3, when the second negative control pressure ratio, the first negative control pressure is high, this second pressure-relief valve 3 will with the oil of the pressure difference corresponding amount of this first negative control pressure and this second negative control pressure, more rely on the second release path 14 of upstream to fuel tank 54 dischargings from the second direction switching valve 7x than upstream.The upstream passages 75 of second pressure-relief valve 3 is connected with the second release path 14 of second direction switching valve 7x upstream, and the downstream passages 73 of second pressure-relief valve 3 is connected with drain passageway 71.
In addition, second pressure-relief valve 3 has lap position 3b and is communicated with position 3a, to first Room, 31 inputs, second a negative control pressure of this second pressure-relief valve 3, to another chamber 33 inputs the 3rd negative control pressure of this second pressure-relief valve 3, and second pressure-relief valve 3 disposes second pressure-relief valve spring 34.When this second negative control pressure ratio the 3rd negative control pressure and second pressure-relief valve used the pressing force sum of spring 34 high, second pressure-relief valve 3 was in and is communicated with position 3a.At this, another chamber 33 of second pressure-relief valve 3 is communicated with low pressure selector valve 8 with path 76 by the 3rd negative control pressure.
The action of hydraulic shovel
At this, at first diverter pump 51 and pressure- relief valve 2,3 characteristic are described.Figure 10 is the plotted curve of the expression discharge flow rate characteristic of diverter pump 51 and pressure- relief valve 2,3 open nature.
The discharge flow rate characteristic of (a) expression diverter pump 51 of Figure 10, utilize regulator 52 to adjust the discharge flow rate of diverter pump 51, when negative control pressure (the 3rd negative control pressure) when being 0～Pf, the discharge flow rate of diverter pump 51 becomes peak rate of flow Qmax, when negative control pressure is Pf～Ps, the proportional decline with the increase of negative control pressure of the discharge flow rate of diverter pump 51, when negative control pressure is Ps when above, the discharge flow rate of diverter pump 51 is minimum discharge Qmin.And, Pf＜Ps.In addition, Pf is the discharge flow rate of the diverter pump 51 maximum negative control pressure during for maximum (Qmax), and Ps is the discharge flow rate of the diverter pump 51 minimal negative pilot pressure during for minimum (Qmin).The discharge flow rate of diverter pump 51 refers to the discharge flow rate of a discharge from two exhaust port 51a, 51b.
Figure 10 (b) represents pressure-relief valve 2 by solid line, 3 open nature, when negative control pressure difference (absolute value of the difference of the first negative control pressure and the second negative control pressure) when being 0, pressure- relief valve 2,3 opening area is 0 ( lap position 2b, 3b), when the negative control pressure difference is 0～(Ps-Pf), pressure-relief valve 2, the proportional increase (pressure-relief valve stroke neutral position (connection position)) with the increase of negative control pressure difference of 3 opening area, when the negative control pressure difference is Ps-Pf when above, pressure- relief valve 2,3 opening area is maximum open area (pressure-relief valve stroke maximum position (connection position)).And pressure- relief valve 2,3 opening area are more big, and the pressure-relief valve 2 of flowing through, 3 oil mass are more many.
And, in the example shown in Figure 10 (b), be linear though make pressure- relief valve 2,3 open nature, according to pressure- relief valve 2,3 create conditions or operator's hobby, it is non-linear also can making pressure- relief valve 2,3 open nature.For example, shown in the dot and dash line in Figure 10 (b), be spill by making open nature, supply flow in the time of can making composition operation increases, and pressure is raise, and its result has increased the size of steering force.In addition, shown in the double dot dash line in Figure 10 (b), be convex by making open nature, increased the soft sense of operation.
Then, the action (action of oil hydraulic circuit 201) with reference to the hydraulic shovel of Fig. 6 describes.At first, the whole direction switching valve 6x～7z that supposes first system and second system is in and does not have operated state.At this moment, because the first negative control pressure and the second negative control pressure all are higher pressure, so by low pressure selector valve 8 selections and also higher to the 3rd negative control pressure of regulator 52 inputs.Therefore, the discharge flow rate of diverter pump 51 becomes less state (with reference to (a) of Figure 10).For example, all be Qmin from the exhaust port 51a of diverter pump 51 and the discharge flow rate of exhaust port 51b.
From this state, for example operate second direction switching valve 7y, make and rotate with fluid pressure motor 59 actions.At this moment, owing to provide pressure oil to rotating with fluid pressure motor 59 from the second release path 14, institute is so that the second negative control pressure ratio, the first negative control pressure is low.If the second negative control pressure reduces, then select this second negative control pressure as the 3rd negative control pressure and output by low pressure selector valve 8, import three negative control pressure with first guiding path 16 to regulator 52 by regulator.Thus, all be increased to the necessary flow of second system from the discharge flow rate of the exhaust port 51a of diverter pump 51 and exhaust port 51b.
At this moment, first pressure-relief valve 2 is only with the path increment corresponding with the negative control pressure difference, switch (movement) to being communicated with position 2a from lap position 2b, become the pressure-relief valve opening area corresponding with the negative control pressure difference, thereby make residual oil (with the oil of the negative control pressure difference corresponding amount) downstream passages of flowing through 72 of first system and discharge (with reference to (b) of Figure 10) to fuel tank 54.
Thus, by diverter pump 51 is carried out negative control, can make the discharge flow rate of diverter pump 51 consistent with a necessary flow side how in first system and second system.And, though in oil hydraulic circuit 201, adopt the direction switching valve of hydraulic pilot type, also can use the direction switching valve of type hand.
In addition, when not using first system or necessary flow-rate ratio second system of first system after a little while, can be from first pressure-relief valve 2 to fuel tank will the flow through residual oil of first system of 54 dischargings.At this, by the 54 discharging residual oils from first pressure-relief valve 2 to fuel tank, the pressure in the first release path 13 is descended, thereby be reduced in the energy loss in the first throttle portion 9.In addition, pressure in the first release path 13 is elevated under the state more than necessary (under the state that raises because of residual oil), if operation first direction switching valve, then hydraulic drive mechanism can be out of control sometimes, can not carry out trickle control, but the residual oil by to the fuel tank 54 dischargings first release path 13 can reduce the influence to second direction switching valve 7y operation amount, thereby improves control performance.
Equally, according to oil hydraulic circuit 201, when not using second system or necessary flow-rate ratio first system of second system after a little while, can be from second pressure-relief valve 3 to fuel tank the 54 dischargings residual oil of second system of will flowing through, thereby be reduced in energy loss in second restriction 10.
The 3rd mode of execution
Fig. 7 is the circuit diagram of the oil hydraulic circuit 202 of expression third embodiment of the invention.Difference around present embodiment and described second mode of execution describes present embodiment.In addition, identical with described second mode of execution constituent element adopts identical reference character (other mode of execution also adopts the same manner).
The release flow control valve
The main oil hydraulic circuit that is not both the 3rd mode of execution 202 of the 3rd mode of execution and second mode of execution has release flow control valve 4,5.As shown in Figure 7, oil hydraulic circuit 202 has the first release flow control valve 4, and this first release flow control valve 4 is arranged on the downstream passages 72 of this first pressure-relief valve 2 between first pressure-relief valve 2 and the fuel tank 54.The first release flow control valve 4 has lap position 4b and is communicated with position 4a, import the pressure in first pressure-relief valve, 2 downstreams to a chamber 41 of the first release flow control valve 4, import the pressure (pressure of first pressure-relief valve, 2 upstreams) that more relies on the first release path 13 of upstream than first direction switching valve 6x to its another chamber 42, and the first release flow control valve 4 disposes first flow control valve spring 43.
Equally, oil hydraulic circuit 202 has the second release flow control valve 5, and this second release flow control valve 5 is configured on the downstream passages 73 of this second pressure-relief valve 3 between second pressure-relief valve 3 and the fuel tank 54.Wherein, the second release flow control valve 5 has lap position 5b and is communicated with position 5a, import the pressure in second pressure-relief valve, 3 downstreams to a chamber 51 of the second release flow control valve 5, import the pressure (pressure of second pressure-relief valve, 3 upstreams) that more relies on the second release path 14 of upstream than second direction switching valve 7x to its another chamber 52, and the second release flow control valve 5 disposes second flow control valve spring 53.
Thus, by on the downstream passages 73 of the downstream passages 72 of first pressure-relief valve 2 and second pressure-relief valve 3, increasing by the first release flow control valve 4 and the second release flow control valve 5 respectively, can be irrelevant with the load pressure of hydraulic drive mechanism, all the time to the oil of fuel tank 54 discharging and pressure-relief valve 2, residual flow that 3 opening (operation amount of direction switching valve) is corresponding, thereby can suppress the operating characteristics variation.
The 4th mode of execution
Fig. 8 is the circuit diagram of the oil hydraulic circuit 203 of expression four embodiment of the invention.Difference around present embodiment and described second mode of execution describes present embodiment.
The not operation signal generates valve
The main difference of the 4th mode of execution and second mode of execution is that the oil hydraulic circuit 203 of the 4th mode of execution has not operation signal generation valve 15.As shown in Figure 8, the not operation signal generates a chamber 61 of valve 15 by path 77, and the first first guiding path 18 that more relies on the upstream with Auxiliary valves 11x than upstream is connected.In addition, dispose spring 62 in this chamber 61.In addition, the not operation signal generates another chamber 63 of valve 15 by path 78, and the first first guiding path 18 that more relies on the upstream with Auxiliary valves 11x than upstream is connected.And the first first guiding path 18 between path 78 and the Auxiliary valves 11x is provided with restriction 19.At this, path 78 is equivalent to the press device that is configured in another chamber 63 of the present invention, by the pressure of this path 78 63 input pioneer pumps 53 to the chamber.And, also can be in the chamber 63 dispose spring, this spring as press device.In addition, also can use this spring and path 78 together.
In addition, the not operation signal generates valve 15 and forms: when at least one Auxiliary valves is in lap position, second Room 22 of first pressure-relief valve 2 and second Room 32 of second pressure-relief valve 3 all are connected with fuel tank 54, and when whole Auxiliary valves 11x～12z is in the connection position, described second Room 22,32 all is connected with pioneer pump 53.
Wherein, when whole direction switching valve 6x～7z of first system and second system was not operated, whole Auxiliary valves 11x～12z was in and is communicated with the position.Thus, the pressing force of another chamber 63 1 sides of not operation signal generation valve 15 is bigger than the pressing force of chamber 61 1 sides, and the not operation signal generates the state that valve 15 is in position 15b.Thus, second Room 22 of first pressure-relief valve 2 and second Room 23 of second pressure-relief valve 3 all are connected with pioneer pump 53, and first pressure-relief valve 2 and second pressure-relief valve 3 all switch to from lap position and be communicated with the position.Thus, first pressure-relief valve 2 and second pressure-relief valve 3 discharge oil from the release path 13,14 of first direction switching valve 6x and second direction switching valve 7x upstream to fuel tank 54 respectively.According to present embodiment, even when whole direction switching valve 6x～7z is not operated, also can be from pressure- relief valve 2,3 to fuel tank 54 discharging will flow through release path 13,14 residual oil, thus can further be reduced in energy loss in first throttle portion 9 and second restriction 10.
And if operated wherein any one direction switching valve, then corresponding with it Auxiliary valves is switched to lap position.At this, if at least one Auxiliary valves is in lap position, then (upstream and downstream) pressure of restriction 19 front and back equates substantially, and the not operation signal generates valve 15 and switches to position 15a.Thus, second Room 32 of first pressure-relief valve 2 second Room 22 and second pressure-relief valve 3 all is connected with fuel tank 54.
Shuttle valve
Oil hydraulic circuit 203 is provided with the second first guiding path 20, and an end NOT-AND operation signal of this second first guiding path 20 generates valve 15 and connects, and the other end is connected with low pressure selector valve 8 with path 76 by the 3rd negative control pressure.Oil hydraulic circuit 203 has the shuttle valve 17 that is arranged on the second first guiding path 20.Shuttle valve 17 selects the not operation signals to generate higher oil pressure in the output of valves 15 and described the 3rd negative control pressure, and exports this oil pressure with first guiding path 16 to regulator 52 by regulator.
Wherein, as mentioned above, when whole direction switching valve 6x～7z of first system and second system was not operated, the not operation signal generated the state that valve 15 is in position 15b.At this moment, the pressure from the pioneer pump 53 higher than the head pressure of diverter pump 51 acts on the second first guiding path 20.Thus, the high pressure that shuttle valve 17 is selected from pioneer pump 53, and to regulator 52 these high pressure of output.Its result, the discharge flow rate of diverter pump 51 reduces to Qmin.That is to say that when whole direction switching valve 6x～7z was not operated, the not operation signal generated the hydraulic pressure signal that valve 15 outputs reduce the discharge flow rate of diverter pump 51.According to present embodiment, can further reduce the energy loss when not having the direction of operating switching valve.In addition, by being also used as regulator with signal and pressure-relief valve signal from the signal of not operation signal generation valve 15, can simplify oil hydraulic circuit.And in general, negative control pressure is set to the pressure lower than 3Mpa, and the pressure of pioneer pump 53 is set to more than the 3MPa.
The idle speed control of motor
Send to the control device of motor (not shown) by port 79 and to be imported into the hydraulic pressure signal from the first first guiding path 18 (pilot pressure signal) that the not operation signal generates a chamber 61 of valve 15, the auto idle speed signal that motor is carried out idle speed control with work.According to present embodiment, by being also used as signal and the auto idle speed signal that the not operation signal generates valve 15, can simplify oil hydraulic circuit.
The 5th mode of execution
Fig. 9 is the circuit diagram of the oil hydraulic circuit 204 of expression fifth embodiment of the invention.The oil hydraulic circuit 204 of present embodiment is oil hydraulic circuit 203 merging with oil hydraulic circuit 202 with described the 4th mode of execution of described the 3rd mode of execution.
The 6th mode of execution
Figure 11 is the circuit diagram of the oil hydraulic circuit 205 of expression sixth embodiment of the invention.Difference around present embodiment and described the 3rd mode of execution describes present embodiment.In addition, identical with described the 3rd mode of execution constituent element adopts identical reference character.
In the oil hydraulic circuit of described first～the 5th mode of execution record, for example, if the first negative control pressure of first system is below the Pf, then the discharge capacity of diverter pump 51 is maximum.Be lower than under the state of Pf at this first negative control pressure, when oil hydraulic circuit moves, if the second negative control pressure of second system becomes than the lower state of the first negative control pressure that is lower than Pf, then first pressure-relief valve 2 is in and is communicated with the position, the flow of first system is descended, its result exists the output of the hydraulic drive mechanism of first system to descend unexpectedly, causes the problem of operating characteristics variation.But, according to the oil hydraulic circuit 205 of the present embodiment of following explanation, the operating characteristics of the hydraulic drive mechanism of the discharge flow rate that can improve diverter pump 51 when maximum.
Pressure-relief valve lap position retaining mechanism
The main oil hydraulic circuit that is not both the 6th mode of execution 205 of the 6th mode of execution and the 3rd mode of execution has pressure-relief valve lap position retaining mechanism 94.Oil hydraulic circuit 205 has pressure-relief valve lap position retaining mechanism 94, when the first negative control pressure makes the discharge flow rate of diverter pump 51 be maximum, this pressure-relief valve lap position retaining mechanism 94 remains on the lap position 2b first pressure-relief valve 2, and when the second negative control pressure made the discharge flow rate of diverter pump 51 be maximum, this pressure-relief valve lap position retaining mechanism 94 remained on the lap position 3b second pressure-relief valve 3.At this, when the discharge flow rate that the first negative control pressure makes diverter pump 51 refers to that the first negative control pressure among (a) of Figure 10 is 0～Pf when maximum.When equally, the second negative control pressure discharge flow rate that makes diverter pump 51 refers to that the second negative control pressure in (a) of Figure 10 is 0～Pf when maximum.
In other words, (0～Pf) time, make the negative control pressure in the system is that the following pressure-relief valve of Pf remains on the lap position to the discharge flow rate that pressure-relief valve lap position retaining mechanism 94 makes diverter pump 51 when the 3rd negative control pressure becomes for maximum pressure.
In the present embodiment, pressure-relief valve lap position retaining mechanism 94 comprises: first check valve 92, be arranged on the 3rd negative control pressure with on the path 76, from low pressure selector valve 8 towards the direction of first pressure-relief valve 2 and second pressure-relief valve 3 as forward; And second check valve 91, with these first check valve, 92 the 3rd negative control pressure that are configured in parallel with on the path 76, from two pressure- relief valves 2,3 towards the direction of low pressure selector valve 8 as forward.And second check valve 91 has spring 93.This spring 93 is designed to when the 3rd negative control pressure is higher than the discharge flow rate that makes diverter pump 51 for maximum pressure second check valve 91 be opened.Wherein, the discharge flow rate that makes diverter pump 51 refers to the pressure P f among (a) of Figure 10 for maximum pressure.
According to this configuration, the pressure-relief valve lap position retaining mechanism 94 that is made of two check valves 91,92 makes another chamber 23 of first pressure-relief valve 2 and second pressure- relief valve 3,33 pressure can not become the pressure lower than Pf.
Liquid Press the action of excavator
Then, with reference to Figure 11, Figure 13, the action (action of oil hydraulic circuit 205) of hydraulic shovel is described.Figure 13 be expression when having operated the direction switching valve the first negative control pressure and the second negative control pressure between the plotted curve that concerns.
At first, the whole direction switching valve 6x～7z that supposes first system and second system is in and does not have operated state.At this moment, because the first negative control pressure and the second negative control pressure all are high pressure, so the 3rd negative control pressure of being selected and being imported to regulator 52 by low pressure selector valve 8 also raises.Therefore, the discharge flow rate of diverter pump 51 becomes less state (with reference to (a) of Figure 10).For example, all be Qmin from the exhaust port 51a of diverter pump 51 and the discharge flow rate of exhaust port 51b.
From this state, for example operate the second direction switching valve 7x of first direction switching valve 6x, first direction switching valve 6y, first direction switching valve 6z and second system of first system, make their actions, thereby provide pressure oil to each hydraulic drive mechanism 55～57,60, its result, shown in Figure 13 (a), the first negative control pressure becomes the Pa1 lower than Pf, and the second negative control pressure becomes Pb1 (Pf＜Pb1＜Ps).
At this moment, the first negative control pressure of being selected by low pressure selector valve 8 (Pa1) is exported as the 3rd negative control pressure, and it is imported to regulator 52.Thus, all become Qmax (peak rate of flow) from the exhaust port 51a of diverter pump 51 and the discharge flow rate of exhaust port 51b.
And utilize pressure-relief valve lap position retaining mechanism 94 this moment, and another chamber 23 of first pressure-relief valve 2 and second pressure- relief valve 3,33 pressure are maintained Pf.And, second pressure-relief valve 3 is only with the path increment corresponding with negative control pressure difference (Pb1-Pf), switch (movement) to being communicated with position 3a from lap position 3b, become the pressure-relief valve opening area corresponding with negative control pressure difference (Pb1-Pf), thereby make residual oil (with the oil of the pressure corresponding amount of the Pb1-Pf) downstream passages of flowing through 73 of second system and to fuel tank 54 dischargings (with reference to (b) of Figure 10).And first pressure-relief valve 2 becomes lap position 2b.
Then, operate second direction switching valve 7y and the second direction switching valve 7z of second system again, its result, shown in Figure 13 (b), the second negative control pressure P b1 becomes the Pb2 lower than Pa1.
At this moment, if hypothesis does not have pressure-relief valve lap position retaining mechanism 94, then first pressure-relief valve 2 switches to from lap position 2b and is communicated with position 2a, to fuel tank 54 discharging oil, thereby causes the oil mass of first system that flows through to be lower than Qmax.Thus, the output meeting of the hydraulic drive mechanism of first system descends unexpectedly, causes the operating characteristics variation.
But, according to the oil hydraulic circuit 205 of present embodiment, utilize pressure-relief valve lap position retaining mechanism 94, the pressure of another chamber 23 of first pressure-relief valve 2 is maintained the Pf higher than Pa1.Therefore, first pressure-relief valve 2 remains on the lap position 2b, thereby the oil mass of first system that will flow through is maintained Qmax.That is to say the operating characteristics of the hydraulic drive mechanism of the discharge flow rate that can improve diverter pump 51 during for maximum (Qmax).
The 7th mode of execution
Figure 12 is the circuit diagram of the oil hydraulic circuit 206 of expression seventh embodiment of the invention.The oil hydraulic circuit 206 of present embodiment is oil hydraulic circuit 203 merging with the oil hydraulic circuit 205 of described the 6th mode of execution and described the 4th mode of execution.
The 8th mode of execution
Figure 14 is the circuit diagram of the oil hydraulic circuit 301 of expression eighth embodiment of the invention.Difference around present embodiment and described second mode of execution describes present embodiment.In addition, identical with described second mode of execution constituent element adopts identical reference character.
The structure of oil hydraulic circuit
The 8th mode of execution and second mode of execution are main is not both in first system of the oil hydraulic circuit 201 of second mode of execution and second system and is respectively arranged with first pressure-relief valve 2 and second pressure-relief valve 3, and in the oil hydraulic circuit 301 of the 8th mode of execution, the pressure-relief valve 25 (the 9th～the 13 mode of execution of narrating later is also identical) that first system that is provided with is shared with second system.
Pressure-relief valve
Oil hydraulic circuit 301 comprises pressure-relief valve 2, when the first negative control pressure ratio, the second negative control pressure was high, this pressure-relief valve 2 more relied on the first release path 13 of upstream to the oil of fuel tank 54 dischargings with the pressure difference corresponding amount of this first negative control pressure and this second negative control pressure from the first direction switching valve 6x than upstream.Described pressure-relief valve 25 also is when the second negative control pressure ratio, the first negative control pressure is high, more relies on the second release path 14 of upstream from the second direction switching valve 7x than upstream to the oil of fuel tank 54 dischargings with the pressure difference corresponding amount of this first negative control pressure and this second negative control pressure.
In addition, pressure-relief valve 25 is connected with the first shunting release path 13a that begins to shunt from the first release path 13 between diverter pump 51 and the first direction switching valve 6x.In addition, pressure-relief valve 25 also is connected with the second shunting release path 14a that begins to shunt from the second release path 14 between diverter pump 51 and the second direction switching valve 7x.And the downstream passages 72 of pressure- relief valve 25,73 is connected with drain passageway 71.
Wherein, pressure-relief valve 25 has neutral position 25b, the first switching position 25a and the second switching position 25c.Neutral position 25b is the valve position that is communicated with and interdicts connection between the second release path 14 and the fuel tank 54 between the blocking first release path 13 and the fuel tank 54.The first switching position 25a makes the first release path 13 be communicated with fuel tank 54 and interdicts the valve position of connection between the second release path 14 and the fuel tank 54 by the first shunting release path 13a.In addition, the second switching position 25c is the valve position that is communicated with between the blocking first release path 13 and the fuel tank 54 and the second release path 14 is communicated with by the second shunting release path 14a with fuel tank 54.
In addition, to a chamber 26 inputs first negative control pressure of pressure-relief valve 25, to another chamber 27 inputs second negative control pressure of this pressure-relief valve 25.And when the first negative control pressure ratio, the second negative control pressure was high, pressure-relief valve 25 was in the first switching position 25a, and when the second negative control pressure ratio, the first negative control pressure was high, pressure-relief valve 25 was in the second switching position 25c.
At this, the state that pressure-relief valve 25 is in the first switching position 25a, make the first release path 13 be communicated with fuel tank 54 refers to the non-vanishing state of opening area of the pressure-relief valve 25 of this connection, that is to say, be not that the opening area that only refers to valve is maximum state (the second switching position 25c is also identical).
In addition, the first release path 13 between first direction switching valve 6z and first throttle portion 9 is formed with first split point 89, and this first split point 89 is communicated with a chamber 26 of pressure-relief valve 25 with path 99 by the first negative control pressure.Equally, the second release path 14 between second direction switching valve 7z and second restriction 10 is formed with second split point 88, and this second split point 88 is communicated with another chamber 27 of pressure-relief valve 25 with path 90 by the second negative control pressure.
The action of hydraulic shovel
At this, at first the characteristic to pressure-relief valve 25 describes.(b) of Figure 10 also is the plotted curve of the open nature of expression pressure-relief valve 25.
The open nature of in (b) of Figure 10, being represented pressure-relief valve 25 by solid line, when negative control pressure difference (absolute value of the difference of the first negative control pressure and the second negative control pressure) when being 0, the opening area of pressure-relief valve 25 is 0 (neutral position 25b), when the negative control pressure difference is 0～(Ps-Pf), the opening area of pressure-relief valve 25 is with the proportional increase of the increase of negative control pressure difference (pressure-relief valve stroke neutral position (the first switching position 25a or the second switching position 25c)), when the negative control pressure difference is Ps-Pf when above, the opening area of pressure-relief valve 25 is maximum open area (pressure-relief valve stroke maximum position (the first switching position 25a or the second switching position 25c)).And the opening area of pressure-relief valve 25 is more big, and the oil mass of the pressure-relief valve 25 of flowing through is more many.
In addition, in the example shown in Figure 10 (b), be linear though make the open nature of pressure-relief valve 25, according to creating conditions or operator's hobby of pressure-relief valve 25, the open nature that also can make pressure-relief valve 25 is non-linear.For example, shown in the dot and dash line in Figure 10 (b), be spill by making open nature, supply flow in the time of can making composition operation increases, and pressure is raise, and its result has increased the size of steering force.In addition, shown in the double dot dash line in Figure 10 (b), be convex by making open nature, increased the soft sense of operation.
Then, the action (action of oil hydraulic circuit 301) with reference to the hydraulic shovel of Figure 14 describes.At first, the whole direction switching valve 6x～7z that supposes first system and second system is in and does not have operated state.At this moment, because the first negative control pressure and the second negative control pressure all are high pressure, so the 3rd negative control pressure of being selected and being imported to regulator 52 by low pressure selector valve 8 also raises.Therefore, the discharge flow rate of diverter pump 51 becomes less state (with reference to 10 (a) of figure).For example, all be Qmin from the exhaust port 51a of diverter pump 51 and the discharge flow rate of exhaust port 51b.
From this state, for example operate second direction switching valve 7y, make and rotate with fluid pressure motor 59 actions.At this moment, owing to provide pressure oil to rotating with oil hydraulic motor 59 from the second release path 14, institute is so that the second negative control pressure ratio, the first negative control pressure is low.If the second negative control pressure reduces, then select this second negative control pressure as the 3rd negative control pressure and output by low pressure selector valve 8, import three negative control pressure with first guiding path 16 to regulator 52 by regulator.Thus, all be increased to the necessary flow of second system from the discharge flow rate of the exhaust port 51a of diverter pump 51 and exhaust port 51b.
At this moment, pressure-relief valve 25 is only with the path increment corresponding with the negative control pressure difference, switch (movement) to the first switching position 25a from neutral position 25b, become the pressure-relief valve opening area corresponding with the negative control pressure difference, thereby make residual oil (with the oil of the negative control pressure difference corresponding amount) downstream passages 72 of flowing through of first system, and to fuel tank 54 dischargings (with reference to (b) of Figure 10).
Thus, by diverter pump 51 is carried out negative control, can make the discharge flow rate of diverter pump 51 consistent with a necessary flow side how in first system and second system.
In addition, when not using first system or necessary flow-rate ratio second system of first system after a little while, can be from pressure-relief valve 25 to fuel tank will the flow through residual oil of first system of 54 dischargings.By the 54 discharging residual oils from pressure-relief valve 25 to fuel tank, the pressure in the first release path 13 is reduced, thereby be reduced in the energy loss in the first throttle portion 9.In addition, pressure in the first release path 13 is elevated under the state more than necessary (under the state that raises because of residual oil), if operation first direction switching valve, then hydraulic drive mechanism can be out of control sometimes, can not carry out trickle control, but the residual oil by to the fuel tank 54 dischargings first release path 13 can reduce the influence to second direction switching valve 7y operation amount, thereby improves control performance.
Equally, according to oil hydraulic circuit 301, when not using second system or necessary flow-rate ratio first system of second system after a little while, can be from pressure-relief valve 25 to fuel tank the 54 dischargings residual oil of second system of will flowing through, thereby be reduced in energy loss in second restriction 10.
In addition, owing to can in first system and second system, pressure-relief valve be set respectively yet, and in these two systems a pressure-relief valve 25 is set, thus can reduce the quantity of valve, thus oil hydraulic circuit can be simplified.
The 9th mode of execution
Figure 15 is the circuit diagram of the oil hydraulic circuit 302 of expression ninth embodiment of the invention.Difference around present embodiment and described the 8th mode of execution describes present embodiment.In addition, identical with described the 8th mode of execution constituent element adopts identical reference character.
The release flow control valve
The main oil hydraulic circuit that is not both the 9th mode of execution 302 of the 9th mode of execution and the 8th mode of execution has release flow control valve 4,5.As shown in figure 15, oil hydraulic circuit 302 has the first release flow control valve 4 on the downstream passages 72 that is arranged on pressure-relief valve 25.The first release flow control valve 4 has lap position 4b and is communicated with position 4a, import the pressure of first system in pressure-relief valves 25 downstreams to a chamber 41 of the first release flow control valve 4, import the pressure (pressure of pressure-relief valve 25 upstreams) that more relies on the first release path 13 of upstream than first direction switching valve 6x to its another chamber 42, and the first release flow control valve 4 disposes first flow control valve spring 44.
In addition, oil hydraulic circuit 302 has the second release flow control valve 5 on the downstream passages 73 that is arranged on pressure-relief valve 25.At this, the second release flow control valve 5 has lap position 5b and is communicated with position 5a, import the pressure of second system in pressure-relief valves 25 downstreams to a chamber 51 of the second release flow control valve 5, import the pressure (pressure of pressure-relief valve 25 upstreams) that more relies on the second release path 14 of upstream than second direction switching valve 7x to its another chamber 52, and the second release flow control valve 5 disposes second flow control valve spring 54.
Like this, by on the downstream passages 72,73 of pressure-relief valve 25, increasing by the first release flow control valve 4 and the second release flow control valve 5 respectively, can be irrelevant with the load pressure of hydraulic drive mechanism, all the time discharge the oil of the residual flow corresponding with the opening (operation amount of direction switching valve) of pressure-relief valve 25 to fuel tank 54, thereby can suppress the operating characteristics variation.
The tenth mode of execution
Figure 16 is the circuit diagram of the oil hydraulic circuit 303 of expression tenth embodiment of the invention.Difference around present embodiment and described the 8th mode of execution describes present embodiment.The main difference of the tenth mode of execution and the 8th mode of execution is that the oil hydraulic circuit 303 of the tenth mode of execution has neutral pressure-relief valve 35 and the not operation signal generates valve 15.
Neutral pressure-relief valve
When whole direction switching valve 6x～7z was operated, neutral pressure-relief valve 35 discharged oil from the first release path 13 of first direction switching valve 6x upstream and the second release path 14 of second direction switching valve 7x upstream to fuel tank 54.As shown in figure 16, neutral pressure-relief valve 35 is connected with the second shunting release path 14a with the first shunting release path 13a, and its downstream is connected with drain passageway 71 by path 83.In addition, neutral pressure-relief valve 35 has lap position 35b and is communicated with position 35a.
The not operation signal generates valve
When at least one Auxiliary valves is in lap position, the not operation signal generates valve 15 makes the pilot chamber 36 of neutral pressure-relief valve 35 be connected with fuel tank 54, make this neutrality pressure-relief valve 35 be in lap position 35b, when whole Auxiliary valves 11x～12z is in the connection position, the not operation signal generates valve 15 makes the pilot chamber 36 of neutral pressure-relief valve 35 be connected with pioneer pump 53, this neutrality pressure-relief valve 35 is in is communicated with position 35a.
At this, when whole direction switching valve 6x～7z of first system and second system was not operated, whole Auxiliary valves 11x～12z was in and is communicated with the position.Thus, the pressing force of another chamber 63 1 sides of not operation signal generation valve 15 is bigger than the pressing force of chamber 61 1 sides, and the not operation signal generates the state that valve 15 is in position 15b.And the pilot chamber 36 of neutral pressure-relief valve 35 is connected with pioneer pump 53, and neutral pressure-relief valve 35 switches to from lap position 35b and is communicated with position 35a.Thus, neutral pressure-relief valve 35 discharges oil from the release path 13,14 of first direction switching valve 6x and second direction switching valve 7x upstream to fuel tank 54.According to present embodiment, even when whole direction switching valve 6x～7z is not operated, also can be from neutral pressure-relief valve 35 to fuel tank 54 dischargings will flow through release path 13,14 residual oil, thereby can further be reduced in energy loss in first throttle portion 9 and second restriction 10.
And if operated wherein any one direction switching valve, then corresponding with it Auxiliary valves switches to lap position.At this, if at least one Auxiliary valves is in lap position, then (upstream and downstream) pressure of restriction 19 front and back equates substantially, and the not operation signal generates valve 15 and switches to position 15a.Thus, the pilot chamber 36 of neutral pressure-relief valve 35 all is connected with fuel tank 54, and neutral pressure-relief valve 35 is in lap position 35b.
Shuttle valve
Oil hydraulic circuit 303 is provided with the second first guiding path 20, and an end NOT-AND operation signal of this second first guiding path 20 generates valve 15 and connects, and the other end is connected with low pressure selector valve 8.And oil hydraulic circuit 303 has the shuttle valve 17 that is arranged on the second first guiding path 20.
Utilize the not operation signal to generate valve 15 and shuttle valve 17, (explanation of carrying out in the 4th mode of execution) as mentioned above can further reduce the energy loss when not having the direction of operating switching valve.In addition, be also used as regulator with signal and pressure-relief valve signal by making the signal from not operation signal generation valve 15, can simplify oil hydraulic circuit.
The idle speed control of motor
In addition, send to the control device of motor (not shown) by port 79 and to be imported into the hydraulic pressure signal from the first first guiding path 18 (pilot pressure signal) that the not operation signal generates 15 1 chambers 61 of valve, as the auto idle speed signal of Eng ine Idling Control.According to present embodiment, by being also used as signal and the auto idle speed signal that the not operation signal generates valve 15, can simplify oil hydraulic circuit.
The 11 mode of execution
Figure 17 is the circuit diagram of the oil hydraulic circuit 304 of expression eleventh embodiment of the invention.The oil hydraulic circuit 304 of present embodiment is oil hydraulic circuit 303 merging with the oil hydraulic circuit 302 of described the 9th mode of execution and described the tenth mode of execution.
With reference to the accompanying drawings preferred forms of the present invention is described.And following mode of execution is represented the oil hydraulic circuit of hydraulic shovel.
The 12 mode of execution
Figure 18 is the circuit diagram of the oil hydraulic circuit 305 of expression twelveth embodiment of the invention.Difference around present embodiment and described the 9th mode of execution describes present embodiment.In addition, identical with described the 9th mode of execution constituent element adopts identical reference character.
In the oil hydraulic circuit of described the 8th～the 11 mode of execution record, for example, if the first negative control pressure of first system is below the Pf, then the discharge capacity of diverter pump 51 is maximum.And, be lower than under the state of Pf at this first negative control pressure, when oil hydraulic circuit moves, if the second negative control pressure of second system becomes than the lower state of the first negative control pressure that is lower than Pf, then pressure-relief valve 25 is in the first switching position 25a, the flow of first system is descended, and its result exists the output of the hydraulic drive mechanism of first system to descend unexpectedly, causes the problem of operating characteristics variation.But, adopt the oil hydraulic circuit 305 of the present embodiment of following explanation, the operating characteristics of the hydraulic drive mechanism of the discharge flow rate that can improve diverter pump 51 when maximum.
Pressure-relief valve lap position retaining mechanism
The main oil hydraulic circuit 305 that is not both the 12 mode of execution of the 12 mode of execution and the 9th mode of execution has pressure-relief valve lap position retaining mechanism 87.Oil hydraulic circuit 305 has pressure-relief valve lap position retaining mechanism 87, when the first negative control pressure makes the discharge flow rate of diverter pump 51 be maximum, this pressure-relief valve lap position retaining mechanism 87 remains on pressure-relief valve 25 on the position (neutral position 25b or the second switching position 25c) that is communicated with between the blocking first release path 13 and the fuel tank 54, and when the second negative control pressure made the discharge flow rate of diverter pump 51 be maximum, this pressure-relief valve lap position retaining mechanism 87 remained on pressure-relief valve 25 on the position (neutral position 25b or the first switching position 25a) of interdicting between the second release path 14 and the fuel tank 54.At this, when the first negative control pressure refers to that the first negative control pressure is 0～Pf in (a) of Figure 10 when making the discharge flow rate of diverter pump 51 be maximum.When referring to that the second negative control pressure is 0～Pf in (a) of Figure 10 when equally, the second negative control pressure makes the discharge flow rate of diverter pump 51 be maximum.
In the present embodiment, pressure-relief valve lap position retaining mechanism 87 comprises: first check valve 96, be arranged on the first negative control pressure with on the path 99, from first split point 89 towards the direction of pressure-relief valve 25 as forward; And second check valve 95, be arranged in parallel at the first negative control pressure with on the path 99 with this first check valve 96, from pressure-relief valve 25 towards the direction of first split point 89 as forward; The 3rd check valve 85 is arranged on the second negative control pressure with on the path 90, from second split point 88 towards the direction of pressure-relief valve 25 as forward; And the 4th check valve 84, be arranged in parallel at the second negative control pressure with on the path 90 with the 3rd check valve 85, from pressure-relief valve 25 towards the direction of second split point 88 as forward.
And second check valve 95 and the 4th check valve 84 have spring 97 and spring 86 respectively.Spring 97 is designed to when the first negative control pressure is higher than the discharge flow rate that makes diverter pump 51 for maximum pressure second check valve 95 be opened.In addition, spring 86 is designed to when the second negative control pressure is higher than the discharge flow rate that makes diverter pump 51 for maximum pressure the 4th check valve 84 be opened.At this, the discharge flow rate that makes diverter pump 51 refers to the pressure of the Pf among (a) of Figure 10 for maximum pressure.
Utilize this structure, the pressure-relief valve lap position retaining mechanism 87 that is made of four check valves 84,85,95,96 makes the chamber 26 of pressure- relief valve 25,27 pressure can not become the pressure lower than Pf.
The action of hydraulic shovel
Then, with reference to Figure 18, Figure 13, the action (action of oil hydraulic circuit 305) of hydraulic shovel is described.Figure 13 be expression when having operated the direction switching valve the first negative control pressure and the second negative control pressure between the plotted curve that concerns.
At first, the whole direction switching valve 6x～7z that supposes first system and second system is in and does not have operated state.At this moment, because the first negative control pressure and the second negative control pressure all are high pressure, so the 3rd negative control pressure of being selected and being imported to regulator 52 by low pressure selector valve 8 raises.Therefore, the discharge flow rate of diverter pump 51 becomes less state (with reference to (a) of Figure 10).For example, all be Qmin from the exhaust port 51a of diverter pump 51 and the discharge flow rate of exhaust port 51b.
From this state, for example operate the second direction switching valve 7x of first direction switching valve 6x, first direction switching valve 6y, first direction switching valve 6z and second system of first system, make their actions, thereby provide pressure oil to each hydraulic drive mechanism 55～57,60, its result, shown in Figure 13 (a), the first negative control pressure becomes the Pa1 lower than Pf, and the second negative control pressure becomes Pb1 (Pf＜Pb1＜Ps).
At this moment, the first negative control pressure of being selected by low pressure selector valve 8 (Pa1) is exported as the 3rd negative control pressure, and it is imported to regulator 52.Thus, all become Qmax (peak rate of flow) from the exhaust port 51a of diverter pump 51 and the discharge flow rate of exhaust port 51b.
And utilize pressure-relief valve lap position retaining mechanism 87 this moment, and the pressure of a chamber 26 of pressure-relief valve 25 is remained Pf.And, pressure-relief valve 25 is only with the path increment corresponding with negative control pressure difference (Pb1-Pf), switch (movement) to the second switching position 25c from neutral position 25b, become the pressure-relief valve opening area corresponding with negative control pressure difference (Pb1-Pf), thereby make residual oil (with the oil of the pressure corresponding amount of the Pb1-Pf) downstream passages 73 of flowing through of second system, and to fuel tank 54 dischargings (with reference to (b) of Figure 10).
Then, operate second direction switching valve 7y and the second direction switching valve 7z of second system again, its result, shown in Figure 13 (b), the second negative control pressure P b1 becomes the Pb2 lower than Pa1.
At this moment, if hypothesis does not have pressure-relief valve lap position retaining mechanism 87, then pressure-relief valve 25 switches to the first switching position 25a from the second switching position 25c, to fuel tank 54 discharging oil, thereby causes the oil mass of first system that flows through to be lower than Qmax.Thus, the output meeting of the hydraulic drive mechanism of first system unexpectedly reduces, thereby causes the operating characteristics variation.
But, adopt the oil hydraulic circuit 305 of present embodiment, utilize pressure-relief valve lap position retaining mechanism 87, the pressure of another chamber 27 of pressure-relief valve 25 is remained the Pf higher than Pa1.Therefore, the chamber 26 of pressure-relief valve 25 both sides, 27 pressure become uniform pressure, and pressure-relief valve 25 turns back to neutral position 25b from the second switching position 25c, and keep this state.Its result is maintained Qmax with the oil mass of first system that flows through.That is to say the operating characteristics of the hydraulic drive mechanism of (Qmax) when the discharge flow rate that can improve diverter pump 51 is maximum.
The 13 mode of execution
Figure 19 is the circuit diagram of the oil hydraulic circuit 306 of expression thirteenth embodiment of the invention.The oil hydraulic circuit 306 of present embodiment is oil hydraulic circuit 303 merging with the oil hydraulic circuit 305 of described the 12 mode of execution and described the tenth mode of execution.
More than, though embodiments of the present invention are illustrated,, the present invention is not limited to above-mentioned mode of execution, can carry out various changes and enforcement in the scope of claim record.
For example, though in the above-described embodiment Biao Shi example be the back pressure of the oil of the middle roadside of two systems that flow through logical (the first release path and the second release path) as external signal pressure (the first negative control pressure and the second negative control pressure), a lower pressure (the 3rd negative control pressure) feed back to pump in this external signal pressure that will be selected by the low pressure selector valve.But, also can will be fed back to pump by the pressure minimum in this external signal pressure of low pressure selector valve selection the back pressure of the oil in three the middle roadsides more than the system logical (the release paths more than three) of flowing through as external signal pressure.In this case, if arranged in series two low pressure selector valves 8 for example, then can be from three systems that flow through in the back pressure of the logical oil in roadside, select the pressure minimum among them.Thus, as long as increase the quantity of low pressure selector valve, also can apply the present invention to have in the logical oil hydraulic circuit in the above middle roadside of three systems.
In addition, though Biao Shi example is to dispose three or four first direction switching valves and second direction switching valve on oil hydraulic circuit respectively in the above-described embodiment, but, also can distinguish and only dispose a first direction switching valve and second direction switching valve, can also dispose two respectively, can also dispose respectively more than five.
In addition, though Biao Shi example is the direction switching valve that adopts the hydraulic pilot type in the above-described embodiment,, also can adopt the direction switching valve of type hand.In addition, also can mix the direction switching valve that uses type hand and the direction switching valve of hydraulic pilot type.
Claims (according to the modification of the 19th of treaty)
1. the oil hydraulic circuit of a building machinery, be used for the control diverter pump, described diverter pump is from a swash plate and two kinds of flows that oil hydraulic cylinder seat discharge capacity equates, and described diverter pump can make the discharge capacity reduce according to the size of external signal pressure, it is characterized in that
Described diverter pump has the regulator of control discharge capacity,
The oil hydraulic circuit of described building machinery comprises:
The first release path is connected with an exhaust port of described diverter pump;
The second release path is connected with another exhaust port of described diverter pump;
The first direction switching valve of first system is connected with the described first release path;
The second direction switching valve of second system is connected with the described second release path;
Fuel tank is communicated with the described first release path and the described second release path;
First throttle portion is arranged on the described first release path between described first direction switching valve and the described fuel tank;
Second restriction is arranged on the described second release path between described second direction switching valve and the described fuel tank;
The low pressure selector valve, low in the first negative control pressure and second a negative control pressure oil pressure is exported as the 3rd negative control pressure, the described first negative control pressure is that the described second negative control pressure is the oil pressure as the described second restriction upstream of described external signal pressure as the oil pressure of the described first throttle portion upstream of described external signal pressure; And
First pressure-relief valve, when the described second negative control pressure of the described first negative control pressure ratio is high, described first pressure-relief valve from the described first release path of described first direction switching valve upstream to the oil of described fuel tank discharging with the pressure difference corresponding amount of the described first negative control pressure and the described second negative control pressure.
2. the oil hydraulic circuit of building machinery according to claim 1, it is characterized in that also comprising second pressure-relief valve, when the described first negative control pressure of the described second negative control pressure ratio is high, described second pressure-relief valve from the described second release path of described second direction switching valve upstream to the oil of described fuel tank discharging with the pressure difference corresponding amount of the described first negative control pressure and the described second negative control pressure.
3. the oil hydraulic circuit of building machinery according to claim 2, it is characterized in that, described second pressure-relief valve has lap position and is communicated with the position, import the described second negative control pressure to first Room of described second pressure-relief valve, import described the 3rd negative control pressure to another chamber of described second pressure-relief valve, and described second pressure-relief valve disposes the second pressure-relief valve spring, when described the 3rd negative control pressure of the described second negative control pressure ratio and described second pressure-relief valve were high with the pressing force sum of spring, described second pressure-relief valve was in and is communicated with the position.
4. the oil hydraulic circuit of building machinery according to claim 1, it is characterized in that, described first pressure-relief valve has lap position and is communicated with the position, import the described first negative control pressure to first Room of described first pressure-relief valve, import described the 3rd negative control pressure to another chamber of described first pressure-relief valve, and described first pressure-relief valve disposes the first pressure-relief valve spring, when described the 3rd negative control pressure of the described first negative control pressure ratio and described first pressure-relief valve were high with the pressing force sum of spring, described first pressure-relief valve was in and is communicated with the position.
5. the oil hydraulic circuit of building machinery according to claim 2, it is characterized in that, when whole direction switching valve of described first system and described second system was all operated, described second pressure-relief valve was oily to described fuel tank discharging from the described second release path of described second direction switching valve upstream.
6. the oil hydraulic circuit of building machinery according to claim 1, it is characterized in that, when whole direction switching valve of described first system and described second system was all operated, described first pressure-relief valve was oily to described fuel tank discharging from the described first release path of described first direction switching valve upstream.
7. the oil hydraulic circuit of building machinery according to claim 5 is characterized in that also comprising:
The first first guiding path, the one end is connected with pioneer pump, and the other end is connected with described fuel tank;
A plurality of Auxiliary valvess are wholely set respectively on whole direction switching valve of described first system and described second system, and are arranged in series on the described first first guiding path; And
The not operation signal generates valve, and an one chamber is connected with the described first first guiding path that described Auxiliary valves than upstream more relies on the upstream, disposes press device in another chamber,
When the described direction switching valve of correspondence was in the neutral position, described Auxiliary valves was in and is communicated with the position, and when the described direction switching valve of correspondence was in switching position, described Auxiliary valves was in lap position,
When at least one described Auxiliary valves is in lap position, described not operation signal generates valve all is connected second Room of described first pressure-relief valve and described second pressure-relief valve with described fuel tank, when whole described Auxiliary valvess all was in the connection position, described not operation signal generates valve all was connected described second Room with described pioneer pump.
8. the oil hydraulic circuit of building machinery according to claim 7, it is characterized in that, when whole direction switching valve of described first system and described second system was all operated, described not operation signal generated the hydraulic pressure signal that valve output makes the discharge flow rate minimizing of described diverter pump.
9. the oil hydraulic circuit of building machinery according to claim 8 is characterized in that also comprising:
The second first guiding path, one end generate valve with described not operation signal and are connected, and the other end is connected with described low pressure selector valve; And
Shuttle valve is arranged on the described second first guiding path, selects described not operation signal to generate the output of valve and the high oil pressure in described the 3rd negative control pressure, and exports described oil pressure to described regulator.
10. the oil hydraulic circuit of building machinery according to claim 7 is characterized in that, the hydraulic pressure signal that is input to a chamber of described not operation signal generation valve is used as the auto idle speed signal of Eng ine Idling Control.
11. the oil hydraulic circuit of building machinery according to claim 2, it is characterized in that also comprising pressure-relief valve lap position retaining mechanism, when the described first negative control pressure makes the discharge flow rate of described diverter pump be maximum, described pressure-relief valve lap position retaining mechanism remains on described first pressure-relief valve on the lap position, and when the described second negative control pressure made the discharge flow rate of described diverter pump be maximum, described pressure-relief valve lap position retaining mechanism remained on described second pressure-relief valve on the lap position.
12. the oil hydraulic circuit of building machinery according to claim 11 is characterized in that,
Described first pressure-relief valve has lap position and is communicated with the position, import the described first negative control pressure to first Room of described first pressure-relief valve, import described the 3rd negative control pressure to another chamber of described first pressure-relief valve, and described first pressure-relief valve disposes the first pressure-relief valve spring, when described the 3rd negative control pressure of the described first negative control pressure ratio and described first pressure-relief valve are high with the pressing force sum of spring, described first pressure-relief valve is in and is communicated with the position
Described second pressure-relief valve has lap position and is communicated with the position, import the described second negative control pressure to first Room of described second pressure-relief valve, import described the 3rd negative control pressure to another chamber of described second pressure-relief valve, and described second pressure-relief valve disposes the second pressure-relief valve spring, when described the 3rd negative control pressure of the described second negative control pressure ratio and described second pressure-relief valve are high with the pressing force sum of spring, described second pressure-relief valve is in and is communicated with the position
Described pressure-relief valve lap position retaining mechanism is arranged between another chamber and described low pressure selector valve of described first pressure-relief valve and described second pressure-relief valve, and described pressure-relief valve lap position retaining mechanism comprises: first check valve, from described low pressure selector valve towards the direction of described two pressure-relief valves as forward; And second check valve, from described two pressure-relief valves towards the direction of described low pressure selector valve as forward, when described the 3rd negative control pressure was higher than the discharge flow rate that makes described diverter pump for maximum pressure, described second check valve was opened.
13. the oil hydraulic circuit of building machinery according to claim 1 is characterized in that,
Described first pressure-relief valve is the pressure-relief valve of the described first release path and the described second release path sharing, when the described second negative control pressure of the described first negative control pressure ratio is high, described first pressure-relief valve from the described first release path of described first direction switching valve upstream to the oil of described fuel tank discharging with the pressure difference corresponding amount of the described first negative control pressure and the described second negative control pressure, when the described first negative control pressure of the described second negative control pressure ratio is high, described first pressure-relief valve from the described second release path of described second direction switching valve upstream to the oil of described fuel tank discharging with the pressure difference corresponding amount of the described first negative control pressure and the described second negative control pressure.
14. the oil hydraulic circuit of building machinery according to claim 13 is characterized in that,
Described pressure-relief valve has:
Being communicated with between the described first release path and the described second release path and the described fuel tank interdicted in the neutral position;
First switching position makes the described first release path be communicated with described fuel tank, and interdicts the connection between the described second release path and the described fuel tank; And
Second switching position is interdicted the connection between the described first release path and the described fuel tank, and the described second release path is communicated with described fuel tank,
Import the described first negative control pressure to a chamber of described pressure-relief valve, import the described second negative control pressure to another chamber of described pressure-relief valve, when the described second negative control pressure of the described first negative control pressure ratio is high, described pressure-relief valve is in described first switching position, when the described first negative control pressure of the described second negative control pressure ratio was high, described pressure-relief valve was in described second switching position.
15. the oil hydraulic circuit of building machinery according to claim 13 is characterized in that also comprising:
Neutral pressure-relief valve, be connected with the second shunting release path with the first shunting release path, the described first shunting release path is from the described first release path shunting between described diverter pump and the described first direction switching valve, the described second shunting release path is from the described second release path shunting between described diverter pump and the described second direction switching valve
When whole direction switching valve of described first system and described second system was all operated, described neutral pressure-relief valve discharged oil from the described first release path of described first direction switching valve upstream and the described second release path of described second direction switching valve upstream to described fuel tank.
16. the oil hydraulic circuit of building machinery according to claim 15 is characterized in that also comprising:
The first first guiding path, the one end is connected with pioneer pump, and the other end is connected with described fuel tank;
A plurality of Auxiliary valvess are wholely set respectively on whole direction switching valve of described first system and described second system, and are arranged in series on the described first first guiding path; And
The not operation signal generates valve, and an one chamber is connected with the described first first guiding path that described Auxiliary valves than upstream more relies on the upstream, disposes press device in another chamber,
When the described direction switching valve of correspondence was in the neutral position, described Auxiliary valves was in and is communicated with the position, and when the described direction switching valve of correspondence was in switching position, described Auxiliary valves was in lap position,
When at least one described Auxiliary valves is in lap position, described not operation signal generates valve makes the pilot chamber of described neutral pressure-relief valve be connected with described fuel tank, and make described neutral pressure-relief valve be in lap position, when whole described Auxiliary valvess all is in the connection position, described not operation signal generates valve makes described pilot chamber be connected with described pioneer pump, and makes described neutral pressure-relief valve be in the connection position.
17. the oil hydraulic circuit of building machinery according to claim 16, it is characterized in that, when whole direction switching valve of described first system and described second system was all operated, described not operation signal generated the hydraulic pressure signal that valve output makes the discharge flow rate minimizing of described diverter pump.
18. the oil hydraulic circuit of building machinery according to claim 17 is characterized in that also comprising:
The second first guiding path, one end generate valve with described not operation signal and are connected, and the other end is connected with described low pressure selector valve; And
Shuttle valve is arranged on the described second first guiding path, selects described not operation signal to generate high oil pressure in the output of valve and described the 3rd negative control pressure, and exports described oil pressure to described regulator.
19. the oil hydraulic circuit of building machinery according to claim 16 is characterized in that, the hydraulic pressure signal that is input to a chamber of described not operation signal generation valve is used as the auto idle speed signal of Eng ine Idling Control.
20. the oil hydraulic circuit of building machinery according to claim 13, it is characterized in that also comprising pressure-relief valve lap position retaining mechanism, when the described first negative control pressure makes the discharge flow rate of described diverter pump be maximum, described pressure-relief valve lap position retaining mechanism remains on described pressure-relief valve on the position that is communicated with between the described first release path of blocking and the described fuel tank, and when the described second negative control pressure made the discharge flow rate of described diverter pump be maximum, described pressure-relief valve lap position retaining mechanism remained on described pressure-relief valve on the position that is communicated with between the described second release path of blocking and the described fuel tank.
21. the oil hydraulic circuit of building machinery according to claim 20 is characterized in that,
Described pressure-relief valve has:
Being communicated with between the described first release path and the described second release path and the described fuel tank interdicted in the neutral position;
First switching position makes the described first release path be communicated with described fuel tank, and interdicts the connection between the described second release path and the described fuel tank; And
Second switching position is interdicted the connection between the described first release path and the described fuel tank, and the described second release path is communicated with described fuel tank,
Import the described first negative control pressure to a chamber of described pressure-relief valve, import the described second negative control pressure to another chamber of described pressure-relief valve, when the described second negative control pressure of the described first negative control pressure ratio is high, described pressure-relief valve is in described first switching position, when the described first negative control pressure of the described second negative control pressure ratio is high, described pressure-relief valve is in described second switching position
Described pressure-relief valve lap position retaining mechanism comprises:
First check valve is arranged between the chamber of first split point of described first throttle portion upstream and described pressure-relief valve, from described first split point towards the direction of described pressure-relief valve as forward;
Second check valve is arranged in parallel with described first check valve, from described pressure-relief valve towards the direction of described first split point as forward;
The 3rd check valve is arranged between another chamber of second split point of the described second restriction upstream and described pressure-relief valve, from described second split point towards the direction of described pressure-relief valve as forward; And
The 4th check valve is arranged in parallel with described the 3rd check valve, from described pressure-relief valve towards the direction of described second split point as forward,
When the described first negative control pressure is higher than the discharge flow rate that makes described diverter pump for maximum pressure, described second check valve is opened, when the described second negative control pressure was higher than the discharge flow rate that makes described diverter pump for maximum pressure, described the 4th check valve was opened.

Claims (21)

  1. A kind of oil hydraulic circuit of building machinery is used for the control diverter pump, and described diverter pump is from a swash plate and two kinds of flows that oil hydraulic cylinder seat discharge capacity equates, and described diverter pump can make the discharge capacity reduce according to the size of external signal pressure, it is characterized in that,
    Described diverter pump has the regulator of control discharge capacity,
    The oil hydraulic circuit of described building machinery comprises:
    The first release path is connected with an exhaust port of described diverter pump;
    The second release path is connected with another exhaust port of described diverter pump;
    The first direction switching valve of first system is connected with the described first release path;
    The second direction switching valve of second system is connected with the described second release path;
    Fuel tank is communicated with the described first release path and the described second release path;
    First throttle portion is arranged on the described first release path between described first direction switching valve and the described fuel tank;
    Second restriction is arranged on the described second release path between described second direction switching valve and the described fuel tank;
    The low pressure selector valve, low in the first negative control pressure and second a negative control pressure oil pressure is exported as the 3rd negative control pressure, the described first negative control pressure is that the described second negative control pressure is the oil pressure as the described second restriction upstream of described external signal pressure as the oil pressure of the described first throttle portion upstream of described external signal pressure; And
    First pressure-relief valve, when the described second negative control pressure of the described first negative control pressure ratio is high, described first pressure-relief valve from the described first release path of described first direction switching valve upstream to the oil of described fuel tank discharging with the pressure difference corresponding amount of the described first negative control pressure and the described second negative control pressure.
  2. The oil hydraulic circuit of building machinery according to claim 1, it is characterized in that also comprising second pressure-relief valve, when the described first negative control pressure of the described second negative control pressure ratio is high, described second pressure-relief valve from the described second release path of described second direction switching valve upstream to the oil of described fuel tank discharging with the pressure difference corresponding amount of the described first negative control pressure and the described second negative control pressure.
  3. The oil hydraulic circuit of building machinery according to claim 2, it is characterized in that, described second pressure-relief valve has lap position and is communicated with the position, import the described second negative control pressure to first Room of described second pressure-relief valve, import described the 3rd negative control pressure to another chamber of described second pressure-relief valve, and described second pressure-relief valve disposes the second pressure-relief valve spring, when described the 3rd negative control pressure of the described second negative control pressure ratio and described second pressure-relief valve were high with the pressing force sum of spring, described second pressure-relief valve was in and is communicated with the position.
  4. The oil hydraulic circuit of building machinery according to claim 1, it is characterized in that, described first pressure-relief valve has lap position and is communicated with the position, import the described first negative control pressure to first Room of described first pressure-relief valve, import described the 3rd negative control pressure to another chamber of described first pressure-relief valve, and described first pressure-relief valve disposes the first pressure-relief valve spring, when described the 3rd negative control pressure of the described first negative control pressure ratio and described first pressure-relief valve were high with the pressing force sum of spring, described first pressure-relief valve was in and is communicated with the position.
  5. The oil hydraulic circuit of building machinery according to claim 2, it is characterized in that, when whole direction switching valve of described first system and described second system was all operated, described second pressure-relief valve was oily to described fuel tank discharging from the described second release path of described second direction switching valve upstream.
  6. The oil hydraulic circuit of building machinery according to claim 1, it is characterized in that, when whole direction switching valve of described first system and described second system was all operated, described first pressure-relief valve was oily to described fuel tank discharging from the described first release path of described first direction switching valve upstream.
  7. The oil hydraulic circuit of building machinery according to claim 5 is characterized in that also comprising:
    The first first guiding path, the one end is connected with pioneer pump, and the other end is connected with described fuel tank;
    A plurality of Auxiliary valvess are wholely set respectively on whole direction switching valve of described first system and described second system, and are arranged in series on the described first first guiding path; And
    The not operation signal generates valve, and an one chamber is connected with the described first first guiding path that described Auxiliary valves than upstream more relies on the upstream, disposes press device in another chamber,
    When the described direction switching valve of correspondence was in the neutral position, described Auxiliary valves was in and is communicated with the position, and when the described direction switching valve of correspondence was in switching position, described Auxiliary valves was in lap position,
    When at least one described Auxiliary valves is in lap position, described not operation signal generates valve all is connected second Room of described first pressure-relief valve and described second pressure-relief valve with described fuel tank, when whole described Auxiliary valvess all was in the connection position, described not operation signal generates valve all was connected described second Room with described pioneer pump.
  8. The oil hydraulic circuit of building machinery according to claim 7, it is characterized in that, when whole direction switching valve of described first system and described second system was all operated, described not operation signal generated the hydraulic pressure signal that valve output makes the discharge flow rate minimizing of described diverter pump.
  9. The oil hydraulic circuit of building machinery according to claim 8 is characterized in that also comprising:
    The second first guiding path, one end generate valve with described not operation signal and are connected, and the other end is connected with described low pressure selector valve; And
    Shuttle valve is arranged on the described second first guiding path, selects described not operation signal to generate the output of valve and the high oil pressure in described the 3rd negative control pressure, and exports described oil pressure to described regulator.
  10. The oil hydraulic circuit of building machinery according to claim 7 is characterized in that, the hydraulic pressure signal that is input to a chamber of described not operation signal generation valve is used as the auto idle speed signal of Eng ine Idling Control.
  11. The oil hydraulic circuit of building machinery according to claim 2, it is characterized in that also comprising pressure-relief valve lap position retaining mechanism, when the described first negative control pressure makes the discharge flow rate of described diverter pump be maximum, described pressure-relief valve lap position retaining mechanism remains on described first pressure-relief valve on the lap position, and when the described second negative control pressure made the discharge flow rate of described diverter pump be maximum, described pressure-relief valve lap position retaining mechanism remained on described second pressure-relief valve on the lap position.
  12. The oil hydraulic circuit of building machinery according to claim 11 is characterized in that,
    Described first pressure-relief valve has lap position and is communicated with the position, import the described first negative control pressure to first Room of described first pressure-relief valve, import described the 3rd negative control pressure to another chamber of described first pressure-relief valve, and described first pressure-relief valve disposes the first pressure-relief valve spring, when described the 3rd negative control pressure of the described first negative control pressure ratio and described first pressure-relief valve are high with the pressing force sum of spring, described first pressure-relief valve is in and is communicated with the position
    Described second pressure-relief valve has lap position and is communicated with the position, import the described second negative control pressure to first Room of described second pressure-relief valve, import described the 3rd negative control pressure to another chamber of described second pressure-relief valve, and described second pressure-relief valve disposes the second pressure-relief valve spring, when described the 3rd negative control pressure of the described second negative control pressure ratio and described second pressure-relief valve are high with the pressing force sum of spring, described second pressure-relief valve is in and is communicated with the position
    Described pressure-relief valve lap position retaining mechanism is arranged between another chamber and described low pressure selector valve of described first pressure-relief valve and described second pressure-relief valve, and described pressure-relief valve lap position retaining mechanism comprises: first check valve, from described low pressure selector valve towards the direction of described two pressure-relief valves as forward; And second check valve, from described two pressure-relief valves towards the direction of described low pressure selector valve as forward, when described the 3rd negative control pressure was higher than the discharge flow rate that makes described diverter pump for maximum pressure, described second check valve was opened.
  13. The oil hydraulic circuit of building machinery according to claim 1 is characterized in that,
    Described first pressure-relief valve is the pressure-relief valve of the described first release path and the described second release path sharing, when the described second negative control pressure of the described first negative control pressure ratio is high, described first pressure-relief valve from the described first release path of described first direction switching valve upstream to the oil of described fuel tank discharging with the pressure difference corresponding amount of the described first negative control pressure and the described second negative control pressure, when the described first negative control pressure of the described second negative control pressure ratio is high, described first pressure-relief valve from the described second release path of described second direction switching valve upstream to the oil of described fuel tank discharging with the pressure difference corresponding amount of the described first negative control pressure and the described second negative control pressure.
  14. The oil hydraulic circuit of building machinery according to claim 13 is characterized in that,
    Described pressure-relief valve has:
    Being communicated with between the described first release path and the described second release path and the described fuel tank interdicted in the neutral position;
    First switching position makes the described first release path be communicated with described fuel tank, and interdicts the connection between the described second release path and the described fuel tank; And
    Second switching position is interdicted the connection between the described first release path and the described fuel tank, and the described second release path is communicated with described fuel tank,
    Import the described first negative control pressure to a chamber of described pressure-relief valve, import the described second negative control pressure to another chamber of described pressure-relief valve, when the described second negative control pressure of the described first negative control pressure ratio is high, described pressure-relief valve is in described first switching position, when the described first negative control pressure of the described second negative control pressure ratio was high, described pressure-relief valve was in described second switching position.
  15. The oil hydraulic circuit of building machinery according to claim 13 is characterized in that also comprising:
    Neutral pressure-relief valve, be connected with the second shunting release path with the first shunting release path, the described first shunting release path is from the described first release path shunting between described diverter pump and the described first direction switching valve, the described second shunting release path is from the described second release path shunting between described diverter pump and the described second direction switching valve
    When whole direction switching valve of described first system and described second system was all operated, described neutral pressure-relief valve discharged oil from the described first release path of described first direction switching valve upstream and the described second release path of described second direction switching valve upstream to described fuel tank.
  16. The oil hydraulic circuit of building machinery according to claim 15 is characterized in that also comprising:
    The first first guiding path, the one end is connected with pioneer pump, and the other end is connected with described fuel tank;
    A plurality of Auxiliary valvess are wholely set respectively on whole direction switching valve of described first system and described second system, and are arranged in series on the described first first guiding path; And
    The not operation signal generates valve, and an one chamber is connected with the described first first guiding path that described Auxiliary valves than upstream more relies on the upstream, disposes press device in another chamber,
    When the described direction switching valve of correspondence was in the neutral position, described Auxiliary valves was in and is communicated with the position, and when the described direction switching valve of correspondence was in switching position, described Auxiliary valves was in lap position,
    When at least one described Auxiliary valves is in lap position, described not operation signal generates valve makes the pilot chamber of described neutral pressure-relief valve be connected with described fuel tank, and make described neutral pressure-relief valve be in lap position, when whole described Auxiliary valvess all is in the connection position, described not operation signal generates valve makes described pilot chamber be connected with described pioneer pump, and makes described neutral pressure-relief valve be in the connection position.
  17. The oil hydraulic circuit of building machinery according to claim 16, it is characterized in that, when whole direction switching valve of described first system and described second system was all operated, described not operation signal generated the hydraulic pressure signal that valve output makes the discharge flow rate minimizing of described diverter pump.
  18. The oil hydraulic circuit of building machinery according to claim 17 is characterized in that also comprising:
    The second first guiding path, one end generate valve with described not operation signal and are connected, and the other end is connected with described low pressure selector valve; And
    Shuttle valve is arranged on the described second first guiding path, selects described not operation signal to generate high oil pressure in the output of valve and described the 3rd negative control pressure, and exports described oil pressure to described regulator.
  19. The oil hydraulic circuit of building machinery according to claim 16 is characterized in that, the hydraulic pressure signal that is input to a chamber of described not operation signal generation valve is used as the auto idle speed signal of Eng ine Idling Control.
  20. The oil hydraulic circuit of building machinery according to claim 13, it is characterized in that also comprising pressure-relief valve lap position retaining mechanism, when the described first negative control pressure makes the discharge flow rate of described diverter pump be maximum, described pressure-relief valve lap position retaining mechanism remains on described pressure-relief valve on the position that is communicated with between the described first release path of blocking and the described fuel tank, and when the described second negative control pressure made the discharge flow rate of described diverter pump be maximum, described pressure-relief valve lap position retaining mechanism remained on described pressure-relief valve on the position that is communicated with between the described second release path of blocking and the described fuel tank.
  21. The oil hydraulic circuit of building machinery according to claim 20 is characterized in that,
    Described pressure-relief valve has:
    Being communicated with between the described first release path and the described second release path and the described fuel tank interdicted in the neutral position;
    First switching position makes the described first release path be communicated with described fuel tank, and interdicts the connection between the described second release path and the described fuel tank; And
    Second switching position is interdicted the connection between the described first release path and the described fuel tank, and the described second release path is communicated with described fuel tank,
    Import the described first negative control pressure to a chamber of described pressure-relief valve, import the described second negative control pressure to another chamber of described pressure-relief valve, when the described second negative control pressure of the described first negative control pressure ratio is high, described pressure-relief valve is in described first switching position, when the described first negative control pressure of the described second negative control pressure ratio is high, described pressure-relief valve is in described second switching position
    Described pressure-relief valve lap position retaining mechanism comprises:
    First check valve is arranged between the chamber of first split point of described first throttle portion upstream and described pressure-relief valve, from described first split point towards the direction of described pressure-relief valve as forward;
    Second check valve is arranged in parallel with described first check valve, from described pressure-relief valve towards the direction of described first split point as forward;
    The 3rd check valve is arranged between another chamber of second split point of the described second restriction upstream and described pressure-relief valve, from described second split point towards the direction of described pressure-relief valve as forward; And
    The 4th check valve is arranged in parallel with described the 3rd check valve, from described pressure-relief valve towards the direction of described second split point as forward,
    When the described first negative control pressure is higher than the discharge flow rate that makes described diverter pump for maximum pressure, described second check valve is opened, when the described second negative control pressure was higher than the discharge flow rate that makes described diverter pump for maximum pressure, described the 4th check valve was opened.
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