EP0684389B1 - Control device for multiple hydraulic apparatus - Google Patents
Control device for multiple hydraulic apparatus Download PDFInfo
- Publication number
- EP0684389B1 EP0684389B1 EP95202287A EP95202287A EP0684389B1 EP 0684389 B1 EP0684389 B1 EP 0684389B1 EP 95202287 A EP95202287 A EP 95202287A EP 95202287 A EP95202287 A EP 95202287A EP 0684389 B1 EP0684389 B1 EP 0684389B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- pressure
- actuators
- valve
- control device
- operating
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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Classifications
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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
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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
- E02F9/2225—Control of flow rate; Load sensing arrangements using pressure-compensating valves
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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
- E02F9/2278—Hydraulic circuits
- E02F9/2296—Systems with a variable displacement pump
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- 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
- F15B11/16—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors
- F15B11/161—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors with sensing of servomotor demand or load
- F15B11/162—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors with sensing of servomotor demand or load for giving priority to particular servomotors or users
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- 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
- F15B11/16—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors
- F15B11/161—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors with sensing of servomotor demand or load
- F15B11/163—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors with sensing of servomotor demand or load for sharing the pump output equally amongst users or groups of users, e.g. using anti-saturation, pressure compensation
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- 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
- F15B11/16—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors
- F15B11/161—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors with sensing of servomotor demand or load
- F15B11/166—Controlling a pilot pressure in response to the load, i.e. supply to at least one user is regulated by adjusting either the system pilot pressure or one or more of the individual pilot command pressures
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- 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
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- 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
- F15B2211/25—Pressure control functions
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- 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
- F15B2211/30555—Inlet and outlet of the pressure compensating valve being connected to the directional control valve
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- 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
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- 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
- F15B2211/40576—Assemblies of multiple valves
- F15B2211/40584—Assemblies of multiple valves the flow control means arranged in parallel with a check valve
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- 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
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- 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
- F15B2211/47—Flow control in one direction only
- F15B2211/473—Flow control in one direction only without restriction in the reverse direction
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- 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
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- 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
- F15B2211/5153—Pressure control characterised by the connections of the pressure control means in the circuit being connected to an output member and a directional control valve
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- 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
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- 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
- F15B2211/575—Pilot pressure control
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- 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
- F15B2211/6054—Load sensing circuits having valve means between output member and the load sensing circuit using shuttle valves
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- 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
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- 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
- F15B2211/65—Methods of control of the load sensing pressure
- F15B2211/654—Methods of control of the load sensing pressure the load sensing pressure being lower than the load pressure
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- 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
Definitions
- This invention relates to a control device for multiple hydraulic actuators, and more particularly to a control device which is adapted to control multiple hydraulic actuators by means of one variable pump, thereby to be suitably used for an industrial vehicle.
- a control device for multiple hydraulic actuators which comprises a plurality of actuators provided with operating valves, respectively, a single variable pump for feeding hydraulic fluid to the actuators, a variable orifice which is connected to a feed passage and each of the actuators communicating with the feed passage and of which a degree of opening is controlled depending on the amount of changing-over of each of the operating valves, a pressure compensating valve arranged on a downstream side of each of the variable orifices to keep a pressure difference between a load pressure and a pressure on the downstream side of the variable orifice constant, and a control mechanism for causing the load pressure and a discharge pressure of the variable pump to act as a pilot pressure and the discharge pressure of the variable pump to be kept increased by a predetermined level as compared with the load pressure.
- the control device of the present invention generally constructed as described above is characterised in that the operating valve of one of the actuators is connected on a downstream side thereof to a feed side of at least one of the other actuators through a converging passage and the converging passage is provided with a change-over valve which is changed over to an open position when the operating valve of at least one of the other actuators is changed over.
- the pilot change-over valve is changed over to permit a part of hydraulic fluid fed to an operation system of the specific actuator to be fed to the other actuators, resulting in an excessive increase in circuit pressure of the operation system being effectively prevented.
- FIG. 3 is a circuit diagram showing a power shovel which has been conventionally known in the art.
- a variable pump 1 is connected on a discharge side thereof to a high pressure flow passage 2.
- the high pressure passage 2 is connected to an input port 5 of a first operating valve 40 connected to a boom cylinder 37, an input port 5 of a second operating valve 41 connected to a bucket cylinder 38, and an input port 5 of a third operating valve 42 connected to a spin motor 39.
- variable orifices 6 are rendered open. The degree of opening of the variable orifices 6 is determined depending on the amount of changing-over of the operating valves 40, 41 and 42, respectively.
- relay ports 61 are provided respectively.
- the relay ports 61 are arranged so as to communicate with pressure compensating valves 8, respectively.
- the pressure compensating valves 8 are arranged so as to communicate on a downstream side thereof with feed ports 9 of the first, second and third operating valves 40, 41 and 42, respectively.
- the feed ports 9 are adapted to be kept closed when the operating valves 40, 41 and 42 are each at the neutral position and communicate with either actuator port 10 or 11, when the operating valves 40, 41 and 42 are changed over the their respective lateral positions. At this time, the remaining actuator ports which do not communicate with the feed ports are kept communicating with tank passages 62, respectively.
- the first to third operating valves 40, 41 and 42 are formed with load detecting ports 13, respectively.
- the load detecting ports 13 are adapted to communicate with the tank passages 62, respectively, when the first to third operating valves 40, 41 and 42 are each at the neutral position.
- the load detecting ports 13 are caused to communicate with the actuator ports positioned on a high pressure side.
- the above-described pressure compensating valves 8 are adapted to introduce a pressure on an upstream side of the pressure compensating valves 8 to one of the pilot chambers 8a of the respective valve 8 and a pressure on a side of the load detecting ports 13 to the other pilot chamber 8b of the respective valve 8.
- Such introduction of the pressure is selected by a plurality of shuttle valves 14 so that a maximum load pressure in each of circuit systems is introduced into each of the other pilot chambers 8b.
- the pressure compensating valves 8 carry out controlling in a manner to permit a pressure on the downstream side of the variable orifices 6 to be kept increased by a predetermined level as compared with the maximum load pressure.
- the maximum load pressure selected by the shuttle valves 14 is introduced to one pilot chamber 63a of a control valve 63 for controlling the variable pump 1.
- the other pilot chamber 63b of the control valve 63 is fed with a pressure in the high pressure flow passage 2 or a discharge pressure of the variable pump 1.
- the control valve 63 is caused to operate depending on a relative difference between the discharge pressure of the variable pump 1 and the maximum load pressure.
- Such operation of the control valve 63 causes a control cylinder 64 to operate so that the discharge pressure of the variable pump 1 may be kept constantly increased by a predetermined level as compared with the maximum load pressure.
- reference numeral 65 designates a main relief valve, which functions to set a maximum pressure of the circuit system of each of the boom cylinder 37, bucket cylinder 38 and spin motor 39.
- Co-operation between the amount of discharge of the variable pump 1 and the amount of control of the pressure compensating valves 8 permits fluid to be fed to the actuators in an amount proportional to the amount of changing-over of the first to third operating valves 40, 41 and 42.
- the conventional control system constructed as described above is of the load-sensing type, wherein the variable pump 1 discharges a pressure slightly higher than the maximum load pressure and the pressure compensating valves 8 of the circuit system control the variable orifices 6 of the first to third operating valves 40, 41 and 42 depending on the maximum load pressure. This causes a pressure difference between both sides of each of the variable orifices 6 to be kept constant, thereby to permit fluid to be fed to the actuators in an amount proportional to the amount of changing-over of the operating valves.
- the maximum load pressure established in any of the multiple hydraulic actuators causes the discharge pressure of the variable pump 1 to be controlled, thereby to increase energy loss in the following cases.
- a load pressure is rapidly increased for accelerating the inertia body at a moment of changing-over of the operating valves, resulting in a pressure in the circuit being increased to a set pressure of the main relief valve 65.
- the circuit pressure thus increased constitutes a control signal for each of the first to third operating valves 40, 41 and 42 and variable pump 1. Therefore, if a large amount of hydraulic fluid is flowed under a low pressure in a circuit system other than a spin circuit system, the variable pump 1 is obliged to discharge hydraulic fluid at an increased flow rate under a high pressure. Thus, it is required to feed hydraulic fluid at a large flow rate under a high pressure to the circuit system which requires that hydraulic fluid is fed thereto at a large flow rate under a high pressure for the sake of the spin circuit system which requires to feed hydraulic fluid at a micro flow rate and under a high pressure, so that energy loss is extensively increased.
- the present invention has been made in view of the foregoing disadvantage of the prior art.
- FIG. 1 a first embodiment of a control device for multiple hydraulic actuators according to the present invention is illustrated.
- the relay port 61 of the third operating valve 42 and the pressure compensating valve 8 communicating with the relay port 61 are connected through a converging passage 44 to a side of an inlet port 68 of a change-over valve 67.
- An outlet port 69 of the change-over valve 67 is connected through a load check valve 72 to a side of a bottom of the boom cylinder 37.
- the change-over valve 67 When the change-over valve 67 thus arranged is at a normal position shown in Figure 1, it interrupts communication between the inlet port 68 and the outlet port 69. Also, the change-over valve 67 is changed over to its upper open position (as shown in Figure 1) when a pilot pressure acts on a pilot chamber 70 of the change-over valve 67, thereby to cause both ports 68 and 69 to communicate with an orifice 71. Thus, when the boom cylinder 37 is extended, the change-over valve 67 is changed over to the open position.
- FIG. 2 a second embodiment of a control device for multiple hydraulic actuators according to the present invention is illustrated, which is so constructed that a downstream side of a pressure compensating valve 8 and a feed port 9 of a third operating valve 42 are connected to an inlet port 68 of a change-over valve 67 through a converging passage 44.
- the remaining part of the second embodiment is constructed in substantially the same manner as the first embodiment described above.
- the control device for the multiple hydraulic actuators permits, when a load pressure of one of the actuators is increased, a part of hydraulic fluid fed to the one actuator to be fed to the other actuators. This effectively prevents the one actuator which is required to be fed with hydraulic fluid in a micro-amount under a high pressure from decreasing a discharge quantity of the variable pump, thereby to minimize energy loss.
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- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Fluid Mechanics (AREA)
- Mechanical Engineering (AREA)
- Mining & Mineral Resources (AREA)
- Civil Engineering (AREA)
- Structural Engineering (AREA)
- Fluid-Pressure Circuits (AREA)
- Operation Control Of Excavators (AREA)
Description
- This invention relates to a control device for multiple hydraulic actuators, and more particularly to a control device which is adapted to control multiple hydraulic actuators by means of one variable pump, thereby to be suitably used for an industrial vehicle.
- It is an object of the present invention to provide a control device for multiple hydraulic actuators which is capable of permitting a discharge pressure of a variable pump to be rapidly increased effectively to prevent the amount of fluid discharged from the variable pump from being decreased even when a specific one of the actuators requires that fluid is fed thereto at a micro flow rate under a low pressure.
- In accordance with the present invention, there is provided a control device for multiple hydraulic actuators which comprises a plurality of actuators provided with operating valves, respectively, a single variable pump for feeding hydraulic fluid to the actuators, a variable orifice which is connected to a feed passage and each of the actuators communicating with the feed passage and of which a degree of opening is controlled depending on the amount of changing-over of each of the operating valves, a pressure compensating valve arranged on a downstream side of each of the variable orifices to keep a pressure difference between a load pressure and a pressure on the downstream side of the variable orifice constant, and a control mechanism for causing the load pressure and a discharge pressure of the variable pump to act as a pilot pressure and the discharge pressure of the variable pump to be kept increased by a predetermined level as compared with the load pressure.
- The control device of the present invention generally constructed as described above is characterised in that the operating valve of one of the actuators is connected on a downstream side thereof to a feed side of at least one of the other actuators through a converging passage and the converging passage is provided with a change-over valve which is changed over to an open position when the operating valve of at least one of the other actuators is changed over.
- In the control device of the present invention constructed as described above, when a load pressure of the specific actuator is increased, the pilot change-over valve is changed over to permit a part of hydraulic fluid fed to an operation system of the specific actuator to be fed to the other actuators, resulting in an excessive increase in circuit pressure of the operation system being effectively prevented.
- The present invention is now described by way of example with reference to the accompanying drawings, in which like reference characters designate like or corresponding parts throughout, wherein:-
- FIGURE 1 is a circuit diagram showing a first embodiment of a control device for multiple hydraulic actuators according to the present invention;
- FIGURE 2 is a circuit diagram showing a second embodiment of a control device for multiple hydraulic actuators according to the present invention; and
- FIGURE 3 is a circuit diagram showing a conventional or prior art control device for multiple hydraulic actuators.
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- A conventional control device will first be described with reference to Figure 3, which is a circuit diagram showing a power shovel which has been conventionally known in the art. A variable pump 1 is connected on a discharge side thereof to a high
pressure flow passage 2. Thehigh pressure passage 2 is connected to aninput port 5 of afirst operating valve 40 connected to aboom cylinder 37, aninput port 5 of asecond operating valve 41 connected to abucket cylinder 38, and aninput port 5 of athird operating valve 42 connected to aspin motor 39. - When the first, second and
third operating valves input ports 5 are kept closed. When theoperating valves variable orifices 6 are rendered open. The degree of opening of thevariable orifices 6 is determined depending on the amount of changing-over of theoperating valves - On a downstream side of the
variable orifices 6relay ports 61 are provided respectively. Therelay ports 61 are arranged so as to communicate withpressure compensating valves 8, respectively. Thepressure compensating valves 8 are arranged so as to communicate on a downstream side thereof withfeed ports 9 of the first, second andthird operating valves feed ports 9 are adapted to be kept closed when theoperating valves actuator port 10 or 11, when theoperating valves tank passages 62, respectively. - Also, the first to
third operating valves load detecting ports 13, respectively. theload detecting ports 13 are adapted to communicate with thetank passages 62, respectively, when the first tothird operating valves third operating valves load detecting ports 13 are caused to communicate with the actuator ports positioned on a high pressure side. - The above-described
pressure compensating valves 8 are adapted to introduce a pressure on an upstream side of thepressure compensating valves 8 to one of thepilot chambers 8a of therespective valve 8 and a pressure on a side of theload detecting ports 13 to theother pilot chamber 8b of therespective valve 8. Such introduction of the pressure is selected by a plurality ofshuttle valves 14 so that a maximum load pressure in each of circuit systems is introduced into each of theother pilot chambers 8b. - Thus, the
pressure compensating valves 8 carry out controlling in a manner to permit a pressure on the downstream side of thevariable orifices 6 to be kept increased by a predetermined level as compared with the maximum load pressure. - The maximum load pressure selected by the
shuttle valves 14 is introduced to onepilot chamber 63a of acontrol valve 63 for controlling the variable pump 1. The other pilot chamber 63b of thecontrol valve 63 is fed with a pressure in the highpressure flow passage 2 or a discharge pressure of the variable pump 1. Thus, thecontrol valve 63 is caused to operate depending on a relative difference between the discharge pressure of the variable pump 1 and the maximum load pressure. Such operation of thecontrol valve 63 causes acontrol cylinder 64 to operate so that the discharge pressure of the variable pump 1 may be kept constantly increased by a predetermined level as compared with the maximum load pressure. - In Figure 3, reference numeral 65 designates a main relief valve, which functions to set a maximum pressure of the circuit system of each of the
boom cylinder 37,bucket cylinder 38 andspin motor 39. - Co-operation between the amount of discharge of the variable pump 1 and the amount of control of the
pressure compensating valves 8 permits fluid to be fed to the actuators in an amount proportional to the amount of changing-over of the first tothird operating valves - The conventional control system constructed as described above is of the load-sensing type, wherein the variable pump 1 discharges a pressure slightly higher than the maximum load pressure and the
pressure compensating valves 8 of the circuit system control thevariable orifices 6 of the first tothird operating valves variable orifices 6 to be kept constant, thereby to permit fluid to be fed to the actuators in an amount proportional to the amount of changing-over of the operating valves. - Such circuit construction results in the maximum discharge pressure of the variable pump 1 being controlled to a set pressure of the main relief valve 65.
- Thus, in the conventional control device constructed as described above, the maximum load pressure established in any of the multiple hydraulic actuators causes the discharge pressure of the variable pump 1 to be controlled, thereby to increase energy loss in the following cases.
- For example, when the conventional control circuit is used for a power shovel and an inertia body is used as a load as in spin motion, a load pressure is rapidly increased for accelerating the inertia body at a moment of changing-over of the operating valves, resulting in a pressure in the circuit being increased to a set pressure of the main relief valve 65.
- The circuit pressure thus increased, as described above, constitutes a control signal for each of the first to
third operating valves - In particular, when the discharge pressure of the variable pump 1 is increased during controlling which is carried out so as to keep an output of the variable pump 1 constant, a discharge capability of the variable pump is decreased along a pump output control curve. This causes restriction of a flow rate of hydraulic fluid fed to the circuit system which requires that hydraulic fluid is fed at a large flow rate under a low pressure. For example, when a power shovel is pivotally moved for the purpose of charging a truck with a material in the power shovel, a swinging-up speed of a boom is caused to be decreased during pivotal movement of the power shovel. Unfortunately, this leads to striking of a bucket of the shovel against the truck before the bucket is lifted to a desired height.
- The present invention has been made in view of the foregoing disadvantage of the prior art.
- Referring now to Figure 1, a first embodiment of a control device for multiple hydraulic actuators according to the present invention is illustrated. In the illustrated embodiment, the
relay port 61 of thethird operating valve 42 and thepressure compensating valve 8 communicating with therelay port 61 are connected through aconverging passage 44 to a side of aninlet port 68 of a change-overvalve 67. Anoutlet port 69 of the change-overvalve 67 is connected through aload check valve 72 to a side of a bottom of theboom cylinder 37. - When the change-over
valve 67 thus arranged is at a normal position shown in Figure 1, it interrupts communication between theinlet port 68 and theoutlet port 69. Also, the change-overvalve 67 is changed over to its upper open position (as shown in Figure 1) when a pilot pressure acts on apilot chamber 70 of the change-overvalve 67, thereby to cause bothports orifice 71. Thus, when theboom cylinder 37 is extended, the change-overvalve 67 is changed over to the open position. - The remaining part of the illustrated embodiment is constructed in substantially the same manner as the prior art described above.
- When the
first operating valve 40 is changed over to its left-side position as viewed in Figure 1 in order to extend theboom cylinder 37, a pilot pressure acting on thefirst operating valve 40 then acts on thepilot chamber 70 of the change-overvalve 67, leading to changing-over of the change-overvalve 67 to the open position. This results in a part of hydraulic fluid fed to a circuit system of aspin motor 39 being fed to the bottom side of theboom cylinder 37 through the change-overvalve 67. - Thus, a part of hydraulic fluid fed to the circuit system of the spin motor is fed to the
boom cylinder 37. This effectively prevents a rapid increase in load pressure of the circuit system of thespin motor 39, even when thespin motor 39 is rapidly accelerated or a load pressure on the side of thespin motor 39 is increased. Thus, the illustrated embodiment effectively eliminates a problem that an excessive increase in pressure of thespin motor 39 causes the amount of hydraulic fluid to theboom cylinder 37 to be insufficient. - Referring now to Figure 2, a second embodiment of a control device for multiple hydraulic actuators according to the present invention is illustrated, which is so constructed that a downstream side of a
pressure compensating valve 8 and afeed port 9 of athird operating valve 42 are connected to aninlet port 68 of a change-overvalve 67 through aconverging passage 44. The remaining part of the second embodiment is constructed in substantially the same manner as the first embodiment described above. - The control device for the multiple hydraulic actuators according to the present invention permits, when a load pressure of one of the actuators is increased, a part of hydraulic fluid fed to the one actuator to be fed to the other actuators. This effectively prevents the one actuator which is required to be fed with hydraulic fluid in a micro-amount under a high pressure from decreasing a discharge quantity of the variable pump, thereby to minimize energy loss.
- While preferred embodiments of the invention have been described with a certain degree of particularity with reference to the drawings, obvious modifications and variations are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practised otherwise than as specifically described.
Claims (3)
- A control device for multiple hydraulic actuators comprising a plurality of actuators provided with operating valves (40,41,42) respectively, a single variable pump (1) for feeding hydraulic fluid to the actuators, each of which has a variable orifice (6) which is connected to a feed passage (9) and each of the actuators communicating with the feed passage (9) and the degree of opening of the variable orifice (6) being controlled dependent on the amount of changing-over of each of the operating valves (40,41,42), a pressure compensating valve (8) arranged on a downstream side of each of the variable orifices (6) to keep a pressure difference between a load pressure and a pressure on the downstream side of the variable orifice (6) constant, and a control mechanism for causing the load pressure and a discharge pressure of the variable pump (1) to act as a pilot pressure and the discharge pressure of the variable pump (1) to be kept increased by a predetermined level as compared with the load pressure, characterised in that the operating valve (42) of one of the actuators is connected on a downstream side thereof to a feed side of at least one of the other actuators through a converging passage (44), and the converging passage (44) is provided with a change-over valve (67) which is changed over to an open position when the operating valve (40,41) of at least one of the other actuators is changed over.
- A control device for multiple hydraulic actuators as defined in claim 1, characterised in that the converging passage (44) is connected at one end thereof between the operating valve (42) for controlling the one actuator and the pressure compensating valve (8) connected thereto.
- A control device for multiple hydraulic actuators as defined in claim 1, characterised in that the converging passage (44) is connected at one end thereof to a downstream side of the pressure compensating valve (8) connected to the operating valve (42) for controlling the one actuator.
Applications Claiming Priority (10)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP35712891 | 1991-12-25 | ||
JP03357128A JP3124094B2 (en) | 1991-12-25 | 1991-12-25 | Control device for multiple actuators |
JP357128/91 | 1991-12-25 | ||
JP21224492 | 1992-07-16 | ||
JP212244/92 | 1992-07-16 | ||
JP21224492A JPH0633904A (en) | 1992-07-16 | 1992-07-16 | Load sensitive control device |
JP25051792 | 1992-08-26 | ||
JP250517/92 | 1992-08-26 | ||
JP04250517A JP3128775B2 (en) | 1992-08-26 | 1992-08-26 | Load-sensitive control device |
EP19920311770 EP0550257B1 (en) | 1991-12-25 | 1992-12-23 | Device for controlling multiple hydraulic actuators |
Related Parent Applications (2)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP19920311770 Division EP0550257B1 (en) | 1991-12-25 | 1992-12-23 | Device for controlling multiple hydraulic actuators |
EP92311770.9 Division | 1992-12-23 |
Publications (3)
Publication Number | Publication Date |
---|---|
EP0684389A2 EP0684389A2 (en) | 1995-11-29 |
EP0684389A3 EP0684389A3 (en) | 1996-10-30 |
EP0684389B1 true EP0684389B1 (en) | 1999-09-08 |
Family
ID=27329339
Family Applications (4)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP95202287A Expired - Lifetime EP0684389B1 (en) | 1991-12-25 | 1992-12-23 | Control device for multiple hydraulic apparatus |
EP95202286A Expired - Lifetime EP0684387B1 (en) | 1991-12-25 | 1992-12-23 | Load-sensing active hydraulic control device |
EP95202288A Expired - Lifetime EP0684388B1 (en) | 1991-12-25 | 1992-12-23 | Load-sensing active hydraulic control device |
EP19920311770 Expired - Lifetime EP0550257B1 (en) | 1991-12-25 | 1992-12-23 | Device for controlling multiple hydraulic actuators |
Family Applications After (3)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP95202286A Expired - Lifetime EP0684387B1 (en) | 1991-12-25 | 1992-12-23 | Load-sensing active hydraulic control device |
EP95202288A Expired - Lifetime EP0684388B1 (en) | 1991-12-25 | 1992-12-23 | Load-sensing active hydraulic control device |
EP19920311770 Expired - Lifetime EP0550257B1 (en) | 1991-12-25 | 1992-12-23 | Device for controlling multiple hydraulic actuators |
Country Status (2)
Country | Link |
---|---|
EP (4) | EP0684389B1 (en) |
DE (4) | DE69228489T2 (en) |
Families Citing this family (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE19719228A1 (en) * | 1997-05-07 | 1998-11-12 | Bosch Gmbh Robert | Hydraulic control device for load-independent control of a double-acting engine |
DE19831595B4 (en) * | 1998-07-14 | 2007-02-01 | Bosch Rexroth Aktiengesellschaft | Hydraulic circuit |
FR2807118B1 (en) * | 2000-03-28 | 2002-07-05 | Mannesmann Rexroth Sa | HYDRAULIC CIRCUIT FOR OPERATING MULTIPLE HYDRAULIC RECEIVERS |
BR112013010815A2 (en) * | 2010-11-01 | 2016-08-16 | Volvo Constr Equip Ab | a method for controlling a hydraulic system of a working machine |
CN104627880B (en) * | 2014-12-31 | 2017-02-22 | 中联重科股份有限公司 | Closed-type system, control method, winch system and track vehicle walking system |
CN110671376B (en) * | 2019-09-29 | 2021-03-12 | 中国矿业大学 | Engineering machinery load sensitive-inlet-outlet independent hydraulic system and control method thereof |
Family Cites Families (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE3710699C1 (en) * | 1987-03-31 | 1988-08-18 | Heilmeier & Weinlein | Hydraulic control device for a consumer group |
SE8803181D0 (en) * | 1988-09-09 | 1988-09-09 | Atlas Copco Ab | HYDRAULIC DRIVING SYSTEM WITH A PRIORITY FUNCTION FOR HYDRAULIC MOTORS |
DE69025462T2 (en) * | 1989-05-24 | 1996-09-26 | Kabushiki Kaisha Komatsu Seisakusho, Tokio/Tokyo | HYDRAULIC SWITCHING DEVICE |
-
1992
- 1992-12-23 DE DE1992628489 patent/DE69228489T2/en not_active Expired - Fee Related
- 1992-12-23 EP EP95202287A patent/EP0684389B1/en not_active Expired - Lifetime
- 1992-12-23 DE DE1992629968 patent/DE69229968T2/en not_active Expired - Fee Related
- 1992-12-23 EP EP95202286A patent/EP0684387B1/en not_active Expired - Lifetime
- 1992-12-23 DE DE1992625392 patent/DE69225392T2/en not_active Expired - Fee Related
- 1992-12-23 DE DE1992629966 patent/DE69229966T2/en not_active Expired - Fee Related
- 1992-12-23 EP EP95202288A patent/EP0684388B1/en not_active Expired - Lifetime
- 1992-12-23 EP EP19920311770 patent/EP0550257B1/en not_active Expired - Lifetime
Also Published As
Publication number | Publication date |
---|---|
EP0684388B1 (en) | 1999-02-24 |
DE69225392D1 (en) | 1998-06-10 |
DE69228489T2 (en) | 1999-09-30 |
EP0684387B1 (en) | 1999-09-08 |
EP0550257B1 (en) | 1998-05-06 |
DE69229966T2 (en) | 2000-03-09 |
DE69225392T2 (en) | 1998-09-03 |
EP0550257A1 (en) | 1993-07-07 |
EP0684387A2 (en) | 1995-11-29 |
DE69229966D1 (en) | 1999-10-14 |
EP0684387A3 (en) | 1996-10-30 |
DE69229968T2 (en) | 2000-03-09 |
EP0684388A2 (en) | 1995-11-29 |
DE69229968D1 (en) | 1999-10-14 |
EP0684389A3 (en) | 1996-10-30 |
EP0684389A2 (en) | 1995-11-29 |
DE69228489D1 (en) | 1999-04-01 |
EP0684388A3 (en) | 1996-11-06 |
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