CN111527313A - Fluid pressure control device - Google Patents

Fluid pressure control device Download PDF

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Publication number
CN111527313A
CN111527313A CN201980006723.3A CN201980006723A CN111527313A CN 111527313 A CN111527313 A CN 111527313A CN 201980006723 A CN201980006723 A CN 201980006723A CN 111527313 A CN111527313 A CN 111527313A
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CN
China
Prior art keywords
passage
pump
spool
valve
switching
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Granted
Application number
CN201980006723.3A
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Chinese (zh)
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CN111527313B (en
Inventor
锯屋宜和
吉田说与
田中勇多
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KYB Corp
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KYB Corp
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Publication of CN111527313B publication Critical patent/CN111527313B/en
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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
    • F15B13/00—Details of servomotor systems ; Valves for servomotor systems
    • F15B13/02—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors
    • F15B13/04—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors for use with a single servomotor
    • F15B13/0401—Valve members; Fluid interconnections therefor
    • F15B13/0402—Valve members; Fluid interconnections therefor for linearly sliding valves, e.g. spool 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
    • E02F9/2225—Control of flow rate; Load sensing arrangements using pressure-compensating 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
    • 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
    • F15B11/17—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors using two or more pumps
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F3/00—Dredgers; Soil-shifting machines
    • E02F3/04—Dredgers; Soil-shifting machines mechanically-driven
    • E02F3/28—Dredgers; Soil-shifting machines mechanically-driven with digging tools mounted on a dipper- or bucket-arm, i.e. there is either one arm or a pair of arms, e.g. dippers, buckets
    • E02F3/36—Component parts
    • E02F3/42—Drives for dippers, buckets, dipper-arms or bucket-arms
    • E02F3/43—Control of dipper or bucket position; Control of sequence of drive operations
    • E02F3/435—Control of dipper or bucket position; Control of sequence of drive operations for dipper-arms, backhoes or the like
    • 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
    • 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
    • F15B13/00—Details of servomotor systems ; Valves for servomotor systems
    • F15B13/02—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors
    • F15B13/04—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors for use with a single servomotor
    • F15B13/042—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors for use with a single servomotor operated 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
    • F15B2211/20—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
    • F15B2211/3056—Assemblies of multiple valves
    • F15B2211/3059—Assemblies of multiple valves having multiple valves for multiple output members
    • F15B2211/30595—Assemblies of multiple valves having multiple valves for multiple output members with additional valves between the groups of valves for multiple 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
    • F15B2211/30—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
    • F15B2211/3133—Regenerative position connecting the working ports or connecting the working ports to the pump, e.g. for high-speed approach stroke
    • 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
    • F15B2211/315—Directional control characterised by the connections of the valve or valves in the circuit
    • F15B2211/3157—Directional control characterised by the connections of the valve or valves in the circuit being connected to a pressure source, an output member and a return line
    • F15B2211/31582—Directional control characterised by the connections of the valve or valves in the circuit being connected to a pressure source, an output member and a return line having multiple pressure sources and a single 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
    • F15B2211/30—Directional control
    • F15B2211/315—Directional control characterised by the connections of the valve or valves in the circuit
    • F15B2211/3157—Directional control characterised by the connections of the valve or valves in the circuit being connected to a pressure source, an output member and a return line
    • F15B2211/31588—Directional control characterised by the connections of the valve or valves in the circuit being connected to a pressure source, an output member and a return line having a single pressure source and multiple 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
    • F15B2211/30—Directional control
    • F15B2211/32—Directional control characterised by the type of actuation
    • F15B2211/321—Directional control characterised by the type of actuation mechanically
    • F15B2211/324—Directional control characterised by the type of actuation mechanically manually, e.g. by using a lever or pedal
    • 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
    • F15B2211/42—Flow control characterised by the type of actuation
    • F15B2211/421—Flow control characterised by the type of actuation mechanically
    • F15B2211/423—Flow control characterised by the type of actuation mechanically manually, e.g. by using a lever or pedal
    • 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
    • F15B2211/42—Flow control characterised by the type of actuation
    • F15B2211/428—Flow 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
    • F15B2211/45—Control of bleed-off flow, e.g. control of bypass flow to 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
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/71—Multiple output members, e.g. multiple hydraulic motors or cylinders
    • F15B2211/7142—Multiple output members, e.g. multiple hydraulic motors or cylinders the output members being arranged in multiple groups

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

Abstract

A fluid pressure control device (100) is provided with: a 1 st pump passage (10) for guiding the working oil discharged from the 1 st pump (P1); a 2 nd pump passage (11) for guiding the working oil discharged from the 2 nd pump (P2); a main passage (12) that selectively guides the working oil discharged from the 1 st pump (P1) or the 2 nd pump (P2) and communicates with the working fluid tank (T); a 1 st control valve (20) provided in the 1 st pump passage (10) and controlling the flow of hydraulic fluid supplied to the 1 st hydraulic cylinder (1) and discharged from the 1 st hydraulic cylinder (1); a 2 nd control valve (30) provided in the main passage (12) and controlling the flow of the hydraulic fluid supplied to the 2 nd hydraulic cylinder (2) and discharged from the 2 nd hydraulic cylinder (2); and a switching valve (40) provided in the main passage (12) and configured to selectively switch a passage, which communicates with the main passage (12), of the 1 st pump passage (10) and the 2 nd pump passage (11).

Description

Fluid pressure control device
Technical Field
The present invention relates to a fluid pressure control device.
Background
In JP 2012-241803 a, as a hydraulic drive device of a construction machine, there is disclosed a hydraulic drive device of a working machine, including: a 1 st hydraulic pump and a 2 nd hydraulic pump for supplying pressure oil for operating the boom cylinder and the arm cylinder, respectively; a 1 st boom directional control valve and a 2 nd arm directional control valve connected in parallel to the 1 st hydraulic pump, the 1 st boom directional control valve controlling a flow of pressure oil supplied to a boom cylinder, the 2 nd arm directional control valve controlling a flow of pressure oil supplied to an arm cylinder; and a 2 nd boom directional control valve and a 1 st arm directional control valve connected in parallel to the 2 nd hydraulic pump, the 2 nd boom directional control valve controlling a flow of pressure oil supplied to the boom cylinder, and the 1 st arm directional control valve controlling a flow of pressure oil supplied to the arm cylinder.
The hydraulic drive apparatus further includes: a 3 rd hydraulic pump for supplying pressure oil for operating the boom cylinder and the arm cylinder, respectively; a 3 rd boom directional control valve connected to the 3 rd hydraulic pump for controlling the flow of the pressure oil supplied to the boom cylinder; a 3 rd arm directional control valve connected in series to the 3 rd boom directional control valve and controlling a flow of pressure oil supplied to the arm cylinder; and a 2 nd backup directional control valve connected to the 3 rd hydraulic pump in parallel with the 3 rd boom directional control valve.
In this hydraulic drive device, a 2 nd actuator for driving a 2 nd special attachment connected to the arm is provided, and the 2 nd special attachment can be driven by supplying pressure oil of a 3 rd hydraulic pump to the 2 nd actuator via a 2 nd preliminary directional control valve.
Disclosure of Invention
In the hydraulic drive apparatus of JP 2012-241803 a, the 3 rd boom directional control valve and the 2 nd preliminary directional control valve are connected in parallel to each other to the 3 rd pump. Therefore, when the 3 rd boom directional control valve and the 2 nd backup directional control valve are simultaneously operated, the flow rate of the working fluid supplied to the actuator controlled by one of the valves fluctuates due to the operation of the actuator controlled by the other valve. Therefore, when the 3 rd boom directional control valve and the 2 nd backup directional control valve are simultaneously operated, the operation of the actuator controlled by the control valve may become unstable.
In order to prevent such unstable actuator operation, JP 2012-241803 a describes the following: the 3 rd hydraulic pump and the 2 nd pre-standby direction control valve may be connected to the additional pump port of the 2 nd pre-standby direction control valve through a pipe by blocking a pipe portion connecting them. Accordingly, the pressure oil of the additional hydraulic pump is supplied to the actuator via the 2 nd preliminary directional control valve, and the driving of the special components can be performed independently of the boom operation and the like.
However, depending on the working machine to be mounted, the demand, and the like, it is different whether one control valve (preliminary directional control valve) is connected to the same pump in parallel with another control valve (boom directional control valve) or it is connected to a different pump so as to be independent of the other control valve.
Further, the pump for supplying the working fluid differs in piping structure depending on whether one control valve is connected to the same pump in parallel with another control valve or independent of another control valve.
Therefore, in the hydraulic drive device described in JP 2012-241803 a, it is necessary to manufacture the hydraulic drive device having a plurality of pipe structures in accordance with the mounted working machine, the demand, and the like, and the manufacturing cost increases.
The invention aims to reduce the manufacturing cost of a fluid pressure control device.
According to one aspect of the present invention, there is provided: a 1 st pump passage for guiding the working fluid discharged from the 1 st pump; a 2 nd pump passage for guiding the working fluid discharged from the 2 nd pump; a main passage that selectively guides the working fluid discharged from the 1 st pump or the 2 nd pump, and communicates with the working fluid tank; a 1 st control valve provided in the 1 st pump passage and configured to control a flow of the working fluid supplied to and discharged from the 1 st actuator; a 2 nd control valve provided in the main passage and controlling a flow of the working fluid supplied to and discharged from the 2 nd actuator; a supply passage branched from the main passage for guiding the working fluid to the 2 nd control valve; a parallel passage that branches from the 1 st pump passage and is connected to the supply passage; a check valve provided in the parallel passage and allowing the working fluid to flow only from the 1 st pump toward the supply passage; and a switching valve provided in the main passage and configured to selectively switch a passage communicating with the main passage, from among the 1 st pump passage and the 2 nd pump passage, the switching valve having a 1 st switching position at which the 1 st pump passage communicates with the main passage and a 2 nd switching position at which the 2 nd pump passage communicates with the main passage.
Drawings
Fig. 1 is a configuration diagram showing a part of a hydraulic excavator.
Fig. 2 is a hydraulic circuit diagram showing a fluid pressure control device according to an embodiment of the present invention.
Fig. 3 is an enlarged partial view of a hydraulic circuit diagram of a fluid pressure control device according to an embodiment of the present invention.
Fig. 4 is a cross-sectional view showing a switching valve and a bypass cut-off valve of a fluid pressure control device according to an embodiment of the present invention, showing a state where the switching valve is at a 1 st switching position and the bypass cut-off valve is at an open position.
Fig. 5 is an enlarged cross-sectional view showing a switching valve of the fluid pressure control device according to the embodiment of the present invention.
Fig. 6 is a cross-sectional view showing a switching valve and a bypass cut-off valve of the fluid pressure control device according to the embodiment of the present invention, showing a state where the switching valve is at the 2 nd switching position and the bypass cut-off valve is at the blocking position.
Fig. 7 is a cross-sectional view showing a switching valve and a bypass cut-off valve of the fluid pressure control device according to the embodiment of the present invention, and shows a state in which the switching valve is switched to the 2 nd switching position by the pilot pressure.
Detailed Description
The fluid pressure control device 100 according to the embodiment of the present invention will be described below with reference to the drawings. Hereinafter, a fluid pressure control device 100 will be described as an example, the fluid pressure control device 100 being provided in a fluid pressure control system 101, the fluid pressure control system 101 being applied to a construction machine, particularly a hydraulic excavator (see fig. 1), for controlling the flow of a working fluid supplied to and discharged from a fluid pressure actuator.
First, the overall configuration of a fluid pressure control system 101 including a fluid pressure control device 100 will be described with reference to fig. 2.
The fluid pressure control system 101 includes a 1 st pump P1 and a 2 nd pump P2 for discharging hydraulic fluid as a working fluid, a working fluid tank T for storing the working fluid, a 1 st hydraulic cylinder (hydraulic cylinder) 1 as a 1 st actuator for driving a driving target (see fig. 1) such as a boom 102, an arm 103, a bucket 104, or the like, a 2 nd hydraulic cylinder (hydraulic cylinder) 2 as a 2 nd actuator for driving a preliminary backup (not shown), and a fluid pressure control device 100 for controlling operations of the 1 st hydraulic cylinder 1 and the 2 nd hydraulic cylinder 2. Hereinafter, a case where the 1 st hydraulic cylinder 1 drives the boom 102 will be described as an example, and a detailed description of a hydraulic cylinder for driving a driving target other than the boom 102 will be omitted.
The 1 st pump P1 and the 2 nd pump P2 are driven by an engine (not shown) or a motor (not shown), respectively, and discharge hydraulic oil.
The 1 st cylinder 1 and the 2 nd cylinder 2 have the same structure as each other. Therefore, the structure of the 1 st hydraulic cylinder 1 will be described below in detail, and the structure of the 2 nd hydraulic cylinder 2 is denoted by the same reference numerals as those of the corresponding 1 st hydraulic cylinder 1 and described in the drawings, and detailed description thereof will be omitted.
The 1 st hydraulic cylinder 1 is a double-acting type cylinder having a piston 4 that divides the interior of a cylinder tube 3 into a rod side chamber 6 and a bottom side chamber 7. A piston rod 5 is connected to the piston 4. The hydraulic oil is supplied to the rod side chamber 6 of the 1 st hydraulic cylinder 1 and discharged from the rod side chamber 6 of the 1 st hydraulic cylinder 1 via the 1 st rod side passage 8 a. The hydraulic fluid is supplied to the bottom side chamber 7 of the 1 st hydraulic cylinder 1 and discharged from the bottom side chamber 7 of the 1 st hydraulic cylinder 1 via the 1 st bottom side passage 9 a. The hydraulic oil is supplied to the rod side chamber 6 of the 2 nd hydraulic cylinder 2 and discharged from the rod side chamber 6 of the 2 nd hydraulic cylinder 2 through the 2 nd rod side passage 8 b. The hydraulic fluid is supplied to the bottom side chamber 7 of the 2 nd cylinder 2 and discharged from the bottom side chamber 7 of the 2 nd cylinder 2 via the 2 nd bottom side passage 9 b.
By supplying the hydraulic oil to the bottom chamber 7 and discharging the hydraulic oil from the rod side chamber 6, the 1 st hydraulic cylinder 1 is extended and the boom 102 is raised. Conversely, the 1 st hydraulic cylinder 1 is contracted and the boom 102 is lowered by supplying the hydraulic oil to the rod side chamber 6 and discharging the hydraulic oil from the bottom side chamber 7. In the 1 st hydraulic cylinder 1 that drives the boom 102, the bottom side chamber 7 is a load side pressure chamber to which the weight of the boom 102 acts, and the rod side chamber 6 is an opposite-load side pressure chamber. Therefore, the 1 st hydraulic cylinder 1 may communicate the bottom side chamber 7, which is a load side pressure chamber, with the tank T, and perform the contraction operation by the own weight of the boom 102. The operation of the 1 st and 2 nd hydraulic cylinders 1 and 2 will be described in detail later.
Next, the fluid pressure control device 100 will be described.
The hydraulic pressure control device 100 controls the flow of the hydraulic fluid discharged from the 1 st pump P1 and the 2 nd pump P2, thereby controlling the expansion and contraction operations of the 1 st hydraulic cylinder 1 and the 2 nd hydraulic cylinder 2. The 1 st hydraulic cylinder 1 is expanded and contracted by being supplied with hydraulic fluid discharged from the 1 st pump P1. The 2 nd hydraulic cylinder 2 is selectively supplied with hydraulic fluid discharged from the 1 st pump P1 or the 2 nd pump P2 to perform an expansion and contraction operation. The overall configuration of the fluid pressure control device 100 will be described below with reference to the hydraulic circuit of fig. 2.
As shown in fig. 2, the fluid pressure control device 100 includes a 1 st pump passage 10 for guiding the hydraulic fluid discharged from the 1 st pump P1, a 2 nd pump passage 11 for guiding the hydraulic fluid discharged from the 2 nd pump P2, a main passage 12 for selectively guiding the hydraulic fluid discharged from the 1 st pump P1 or the 2 nd pump P2, a 1 st control valve 20 provided in the 1 st pump passage 10 and controlling the flow of the hydraulic fluid supplied to the 1 st hydraulic cylinder 1 and discharged from the 1 st hydraulic cylinder 1, a 2 nd control valve 30 provided in the main passage 12 and controlling the flow of the hydraulic fluid supplied to the 2 nd hydraulic cylinder 2 and discharged from the 2 nd hydraulic cylinder 2, and a switching valve 40 provided in the main passage 12 and selectively switching a passage, which communicates with the main passage 12, of the 1 st pump passage 10 and the 2 nd pump passage 11.
The 1 st control valve 20 and the 2 nd control valve 30 each have a spool (not shown) and are spool valves whose positions are switched by movement of the spool.
The 1 st control valve 20 has a pair of pilot chambers 21a, 21b and springs 22a, 22b as biasing members, and the 1 st control valve 20 operates in accordance with a pressure difference between the pair of pilot chambers 21a, 21 b.
The 1 st control valve 20 is connected with a 1 st pump passage 10, a 1 st branch passage 13 that branches from the 1 st pump passage 10 upstream of the 1 st control valve 20 (on the 1 st pump P1 side), a 1 st tank passage 16a that communicates with the tank T, and a 1 st rod side passage 8a and a 1 st bottom side passage 9a that are connected to the 1 st cylinder 1, respectively. The 1 st branch passage 13 is provided with a 1 st check valve 81, and the 1 st check valve 81 allows the flow of the hydraulic oil from the 1 st pump P1 to the 1 st control valve 20 and restricts the flow of the hydraulic oil in the opposite direction.
The 1 st control valve 20 has a 1 st neutral position 20A at which the 1 st pump passage 10 is opened, a 1 st extension position 20B at which the hydraulic oil introduced from the 1 st pump passage 10 through the 1 st branch passage 13 is introduced to the 1 st hydraulic cylinder 1, and a 1 st contraction position 20C.
The 1 st control valve 20 is held at the 1 st neutral position 20A by a pair of springs 22a, 22b in a state where the pilot pressure is not led to the pair of pilot chambers 21a, 21b of the 1 st control valve 20. In the 1 st neutral position 20A, the 1 st rod side passage 8a, the 1 st bottom side passage 9a, the 1 st branch passage 13, and the 1 st tank passage 16a are all blocked. Therefore, the 1 st hydraulic cylinder 1 is not operated to expand and contract, and is maintained in the load holding state.
When the pilot pressure is introduced into the one pilot chamber 21a of the 1 st control valve 20, the 1 st control valve 20 is switched to the 1 st extension position 20B. At the 1 st extension position 20B, the 1 st branch passage 13 and the 1 st bottom-side passage 9a communicate, and the 1 st working-fluid tank passage 16a and the 1 st rod-side passage 8a communicate. Further, at the 1 st extended position 20B, the 1 st pump passage 10 is blocked. Therefore, when the 1 st control valve 20 is switched to the 1 st extension position 20B, the hydraulic oil discharged from the 1 st pump P1 is supplied to the bottom chamber 7, and the hydraulic oil in the rod side chamber 6 is discharged to the hydraulic tank T. Thereby, the 1 st hydraulic cylinder 1 performs the extension operation.
When the pilot pressure is introduced into the other pilot chamber 21b of the 1 st control valve 20, the 1 st control valve 20 is switched to the 1 st contraction position 20C. At the 1 st contraction position 20C, the 1 st branch passage 13 and the 1 st rod side passage 8a communicate, and the 1 st working fluid tank passage 16a and the 1 st bottom side passage 9a communicate. Further, at the 1 st contraction position 20C, the 1 st pump passage 10 is opened by the pump orifice 23 for applying resistance to the flow of the passing working oil. When the 1 st control valve 20 is switched to the 1 st contraction position 20C, the bottom side chamber 7 communicates with the tank T, and therefore the 1 st hydraulic cylinder 1 is caused to perform a contraction operation by the discharge pressure supplied from the 1 st pump P1 to the rod side chamber 6 or the load of the boom 102. The 1 st retracted position 20C corresponds to the drive position.
Here, the 1 st contraction position 20C of the 1 st control valve 20 will be described in more detail with reference to fig. 3. Hereinafter, in the 1 st contraction position 20C, the flow path that connects the 1 st branch passage 13 and the 1 st rod side passage 8a is referred to as a "1 st communication passage 27", and the flow path that connects the 1 st tank passage 16a and the 1 st bottom side passage 9a is referred to as a "2 nd communication passage 28". The 1 st control valve 20 is provided with a rod-side orifice 24 and a bottom-side orifice 25, which are orifices for applying resistance to the flow of the passing hydraulic oil. The rod-side orifice 24 is provided in the 1 st communication passage 27. The bottom-side orifice 25 has a 1 st orifice 25a and a 2 nd orifice 25b provided in series with each other in the 2 nd communication passage 28, and a 3 rd orifice 25c provided in parallel with the 1 st orifice 25a and the 2 nd orifice 25 b.
The 1 st communication passage 27 and the 2 nd communication passage 28 communicate with each other through the 3 rd communication passage 29. The 3 rd communication passage 29 communicates with the 2 nd communication passage 28 at a flow path between the 1 st throttle 25a and the 2 nd throttle 25 b. An internal check valve 85 is provided in the 3 rd communication passage 29, and the internal check valve 85 allows only the working oil to flow from the 2 nd communication passage 28 toward the 1 st communication passage 27. The specific contents of switching the 1 st control valve 20 to the 1 st contraction position 20C and causing the 1 st hydraulic cylinder 1 to perform the contraction operation will be described in detail later.
The 2 nd control valve 30 has a pair of pilot chambers 31a and 31b and springs 32a and 32b as biasing members, and the 2 nd control valve 30 operates in accordance with a pressure difference between the pair of pilot chambers 31a and 31 b. As shown in fig. 2, the 2 nd control valve 30 is provided in the main passage 12, and the main passage 12 leads the hydraulic oil discharged from the 1 st pump P1 or the 2 nd pump P2 to communicate with the hydraulic tank T. Further, the 2 nd control valve 30 is connected with a main passage 12, a 2 nd branch passage 14 as a supply passage branched from the main passage 12 upstream of the 2 nd control valve 30, a 2 nd tank passage 16b communicating with the tank T, and a 2 nd rod side passage 8b and a 2 nd bottom side passage 9b connected to the 2 nd hydraulic cylinder 2, respectively.
The parallel passage 15 branched from the 1 st pump passage 10 upstream of the 1 st control valve 20 merges into the 2 nd branch passage 14. The hydraulic oil discharged from the 1 st pump P1 is guided to the 2 nd control valve 30 through the parallel passage 15. The 2 nd branch passage 14 is provided with a 2 nd check valve 82, and the 2 nd check valve 82 allows the working oil to flow from the main passage 12 toward the 2 nd control valve 30 and restricts the flow opposite to the flow. The condition in which the hydraulic oil guided by the parallel passage 15 is guided to the main passage 12 is restricted by the 2 nd check valve 82. Further, the parallel passage 15 is provided with a 3 rd check valve 83, and the 3 rd check valve 83 allows the working oil to flow from the 1 st pump passage 10 toward the 2 nd branch passage 14, and restricts the flow opposite to the flow. A throttle 84 for applying resistance to the flow of the passing hydraulic oil is provided on the upstream side (the 1 st pump P1 side) of the 2 nd check valve 82 in the parallel passage 15.
The 2 nd control valve 30 has a 2 nd neutral position 30A for opening the main passage 12, a 2 nd extension position 30B and a 2 nd contraction position 30C which are supply positions for supplying the hydraulic fluid discharged from the 1 st pump P1 or the 2 nd pump P2 to the 2 nd hydraulic cylinder 2.
The 2 nd control valve 30 is held at the 2 nd neutral position 30A by a pair of springs 32a, 32b in a state where the pilot pressure is not led to the pair of pilot chambers 31a, 31b of the 2 nd control valve 30. At the 2 nd neutral position 30A, the 2 nd branch passage 14, the 2 nd rod side passage 8b, the 2 nd bottom side passage 9b, and the 2 nd tank passage 16b are all blocked. Therefore, the 2 nd hydraulic cylinder 2 is not operated to expand and contract, and is maintained in the load holding state.
When the pilot pressure is introduced into the one pilot chamber 31a of the 2 nd control valve 30, the 2 nd control valve 30 is switched to the 2 nd extension position 30B. At the 2 nd extension position 30B, the 2 nd branch passage 14 and the 2 nd bottom passage 9B communicate, and the 2 nd working fluid tank passage 16B and the 2 nd rod side passage 8B communicate. Further, at the 1 st elongation position 20B, the main passage 12 is blocked. Therefore, when the 2 nd control valve 30 is switched to the 2 nd extension position 30B, the hydraulic oil discharged from the 1 st pump P1 or the 2 nd pump P2 is supplied to the bottom side chamber 7 via the 2 nd branch passage 14, and the hydraulic oil in the rod side chamber 6 is discharged to the hydraulic tank T. Thereby, the 2 nd hydraulic cylinder 2 performs the extension operation.
When the pilot pressure is introduced into the other pilot chamber 31b of the 2 nd control valve 30, the 2 nd control valve 30 is switched to the 2 nd contraction position 30C. At the 2 nd contracted position 30C, the 2 nd branch passage 14 and the 2 nd rod side passage 8b communicate, and the 2 nd working fluid tank passage 16b and the 2 nd bottom side passage 9b communicate. Further, at the 2 nd elongation position 30B, the main passage 12 is blocked. Therefore, when the 2 nd control valve 30 is switched to the 2 nd contraction position 30C, the hydraulic oil discharged from the 1 st pump P1 or the 2 nd pump P2 is supplied to the rod side chamber 6 via the 2 nd branch passage 14, and the hydraulic oil in the bottom side chamber 7 is discharged to the hydraulic tank T. Thereby, the 2 nd hydraulic cylinder 2 performs the contraction operation.
The switching valve 40 has a spool (see fig. 4), and is a two-position spool valve whose position is switched by moving the spool. Hereinafter, the spool of the switching valve 40 is referred to as "1 st spool 41".
The switching valve 40 is connected to a 1 st pump passage 10 for guiding the hydraulic oil discharged from the 1 st pump P1, a 2 nd pump passage 11 for guiding the hydraulic oil discharged from the 2 nd pump P2, a main passage 12 for guiding the hydraulic oil to the 2 nd control valve 30 (the 2 nd hydraulic cylinder 2), and a 3 rd tank passage 16c and a 4 th tank passage 16d which communicate with the tank T, respectively.
The switching valve 40 has a 1 st switching position 40A at which the 1 st pump passage 10 and the main passage 12 communicate with each other and the 2 nd pump passage 11 and the 3 rd tank passage 16c communicate with each other, and a 2 nd switching position 40B at which the 2 nd pump passage 11 and the main passage 12 communicate with each other and the 1 st pump passage 10 and the 4 th tank passage 16d communicate with each other. When the switching valve 40 is switched to the 1 st switching position 40A, the hydraulic oil discharged from the 1 st pump P1 is guided to the 2 nd control valve 30 via the main passage 12. When the switching valve 40 is switched to the 2 nd switching position 40B, the hydraulic oil discharged from the 2 nd pump P2 is guided to the 2 nd control valve 30 via the main passage 12. Therefore, by switching the position of the switching valve 40, it is possible to select whether the hydraulic oil is introduced from the 1 st pump P1 to the 2 nd control valve 30 or the hydraulic oil is introduced from the 2 nd pump P2 to the 2 nd control valve 30.
The switching valve 40 includes a 1 st spring 51 serving as a 1 st biasing member for biasing the 1 st spool 41 so that the 1 st spool 41 is in the 1 st switching position 40A, and a switching portion 55 for moving the 1 st spool 41 against the biasing force of the 1 st spring 51 in response to a manual operation by an operator to switch to the 2 nd switching position 40B. The specific structure and operation of the switching valve 40 will be described in detail later.
The fluid pressure control device 100 further includes a bypass cut-off valve 60, and the bypass cut-off valve 60 is provided in the 1 st pump passage 10 downstream of the 1 st control valve 20 and upstream of the switching valve 40 (between the 1 st control valve 20 and the switching valve 40).
The bypass shutoff valve 60 has a spool (see fig. 4), and is a two-position spool valve that is switched in position by moving the spool. Hereinafter, the spool of the bypass cut valve 60 is referred to as the "2 nd spool 61".
The bypass cut-off valve 60 has an open position 60A at which the 1 st pump passage 10 is opened and a blocking position 60B at which the 1 st pump passage 10 is blocked. The bypass cut valve 60 includes a 2 nd spring 71 as a 2 nd biasing member for biasing the 2 nd spool 61 so that the 2 nd spool 61 is in the open position 60A, and a pilot chamber 78 into which a pilot pressure for biasing the 2 nd spool 61 against the biasing force of the 2 nd spring 71 is introduced. The specific structure and operation of the bypass cut-off valve 60 will be described in detail later.
Next, the operation of the fluid pressure control device 100 will be described.
In the fluid pressure control device 100, the position of the switching valve 40 is switched to switch whether the 1 st pump P1 that supplies the hydraulic fluid to the 1 st hydraulic cylinder 1 also drives the 2 nd hydraulic cylinder 2, or the 1 st pump P1 drives the 1 st hydraulic cylinder 1 and the 2 nd pump P2 drives the 2 nd hydraulic cylinder 2. Hereinafter, the case where the switching valve 40 is in the 1 st switching position 40A and the case where the switching valve 40 is in the 2 nd switching position 40B will be described.
[ 1 st switching position 40A ]
First, a case where the switching valve 40 is switched to the 1 st switching position 40A will be described. When the switching valve 40 is in the 1 st switching position 40A, the 1 st pump passage 10 and the main passage 12 communicate with each other, and the hydraulic oil discharged from the 1 st pump P1 is guided to the 2 nd control valve 30.
[ Individual actuation of the 1 st Hydraulic Cylinder 1 ]
When the 1 st cylinder 1 is driven alone without driving the 2 nd cylinder 2, the 2 nd control valve 30 is switched to the 2 nd neutral position 30A by the pair of springs 32a, 32 b. Further, the bypass cut-off valve 60 is switched to the open position 60A.
When the 1 st hydraulic cylinder 1 is caused to perform the extension operation, the pilot pressure is introduced into the one pilot chamber 21a of the 1 st control valve 20 in accordance with an operation of an operation lever (not shown) by an operator. Thereby, the 1 st control valve 20 is switched to the 1 st extension position 20B.
When the 1 st control valve 20 is switched to the 1 st extension position 20B, the hydraulic oil discharged from the 1 st pump P1 is guided to the bottom side chamber 7 of the 1 st cylinder 1 via the 1 st pump passage 10, the 1 st branch passage 13, and the 1 st bottom side passage 9 a. The hydraulic oil in the rod side chamber 6 of the 1 st hydraulic cylinder 1 is discharged from the 1 st rod side passage 8a to the hydraulic tank T through the 1 st hydraulic tank passage 16 a. Thereby, the 1 st hydraulic cylinder 1 performs the extension operation.
When the 1 st hydraulic cylinder 1 is caused to perform the retracting operation, the pilot pressure is introduced into the other pilot chamber 21b of the 1 st control valve 20 in accordance with the operation of the operation lever by the operator. Thereby, the 1 st control valve 20 is switched to the 1 st contracted position 20C.
When the 1 st control valve 20 is switched to the 1 st contraction position 20C, the 1 st branch passage 13 and the 1 st rod side passage 8a communicate, and the 1 st pump passage 10 is opened by the pump throttle 23. When the 1 st hydraulic cylinder 1 is caused to perform the contraction operation alone, the 2 nd control valve 30 opens the main passage 12 to communicate the main passage 12 with the tank T. Therefore, the 1 st pump passage 10 communicates with the tank T via the main passage 12, and the discharge pressure of the 1 st pump P1 is not led to the rod side chamber 6. On the other hand, in the 1 st hydraulic cylinder 1 that drives the boom 102, the own weight of the boom 102 acts on the bottom side chamber 7. Therefore, in this case, the bottom side chamber 7 is contracted by the load of the boom 102 without using the discharge pressure of the 1 st pump P1, and the hydraulic oil in the bottom side chamber 7 is discharged to the hydraulic tank T through the 1 st bottom side passage 9a and the 1 st hydraulic tank passage 16 a. Further, as the volume of the rod side chamber 6 increases, the working oil is supplied to the rod side chamber 6 through the 1 st branch passage 13. In this way, the 1 st hydraulic cylinder 1 is caused to perform a retracting operation by the load of the boom 102.
When the 1 st hydraulic cylinder 1 contracts, the hydraulic fluid discharged from the bottom chamber 7 is guided to the hydraulic tank T (see fig. 3) via the 1 st orifice 25a, the 2 nd orifice 25b, and the 3 rd orifice 25c provided in the 2 nd communication passage 28 of the 1 st control valve 20. Therefore, the 1 st hydraulic cylinder 1 performs the contraction operation at a speed corresponding to the resistance applied by the 1 st orifice 25a, the 2 nd orifice 25b, and the 3 rd orifice 25 c. Therefore, the speed of the contraction operation of the 1 st hydraulic cylinder 1 can be adjusted by adjusting the resistance applied by the 1 st orifice 25a, the 2 nd orifice 25b, and the 3 rd orifice 25 c.
Further, the working oil discharged from the bottom chamber 7 may be collected into the 1 st communication passage 27 via the 2 nd communication passage 28 and the 3 rd communication passage 29 by adjusting the resistance applied by the 1 st orifice 25a, the 2 nd orifice 25b, and the 3 rd orifice 25 c. Specifically, the ratio of the flow rate (discharge flow rate) of the hydraulic oil discharged to the hydraulic fluid tank T and the flow rate (recovery flow rate) of the hydraulic oil recovered to the 1 st communication passage 27 among the hydraulic oil discharged from the bottom chamber 7 of the 1 st hydraulic cylinder 1 can be adjusted by adjusting the flow path resistances (opening degrees) of the 1 st orifice 25a and the 3 rd orifice 25 c. When the opening degree of the 1 st orifice 25a is larger than the opening degree of the 3 rd orifice 25c, the ratio of the recovery flow rate and the difference between the opening degrees increase. In contrast, in the case where the opening degree of the 1 st throttle 25a is smaller than the opening degree of the 3 rd throttle 25c, the proportion of the discharge flow rate and the difference in the opening degree become large accordingly. It is possible to adjust the recovery flow rate and the discharge flow rate by mainly adjusting the opening degrees of the 1 st orifice 25a and the 3 rd orifice 25c in this way.
[ Individual drive of the 2 nd hydraulic cylinder 2 ]
When the switching valve 40 is in the 1 st switching position 40A and the 1 st hydraulic cylinder 1 is not driven but the 2 nd hydraulic cylinder 2 is driven alone, the 1 st control valve 20 is switched to the 1 st neutral position 20A by the pair of springs 22a and 22 b. Further, the bypass cut-off valve 60 is switched to the open position 60A. The hydraulic oil discharged from the 1 st pump P1 is guided to the main passage 12 via the 1 st pump passage 10 and the parallel passage 15.
When the 2 nd hydraulic cylinder 2 is caused to perform the extension operation, the pilot pressure is introduced into the one pilot chamber 31a of the 2 nd control valve 30 in accordance with the operation of the operation lever by the operator. Thereby, the 2 nd control valve 30 is switched to the 2 nd elongation position 30B.
When the 2 nd control valve 30 is switched to the 2 nd extension position 30B, the hydraulic oil discharged from the 1 st pump P1 to the main passage 12 is guided to the bottom side chamber 7 of the 2 nd hydraulic cylinder 2 via the 2 nd bottom side passage 9B. The hydraulic oil in the rod side chamber 6 of the 2 nd hydraulic cylinder 2 is discharged from the 2 nd rod side passage 8b to the hydraulic tank T through the 2 nd hydraulic tank passage 16 b. Thereby, the 2 nd hydraulic cylinder 2 performs the extension operation.
When the 2 nd hydraulic cylinder 2 is caused to perform the contraction operation, the pilot pressure is introduced into the other pilot chamber 31b of the 2 nd control valve 30 in accordance with the operation of the operation lever by the operator. Thus, the 2 nd control valve 30 switches to the 2 nd contracted position 30C.
When the 2 nd control valve 30 is switched to the 2 nd contraction position 30C, the hydraulic oil discharged from the 1 st pump P1 and guided through the main passage 12 is guided to the rod side chamber 6 of the 2 nd hydraulic cylinder 2 through the 2 nd rod side passage 8 b. The hydraulic fluid in the bottom chamber 7 of the 2 nd hydraulic cylinder 2 is discharged from the 2 nd bottom passage 9b to the hydraulic tank T through the 2 nd hydraulic tank passage 16 b. Thereby, the 2 nd hydraulic cylinder 2 performs the contraction operation.
[ Compound action ]
Next, a compound operation of causing the 1 st hydraulic cylinder 1 to perform the telescopic operation and causing the 2 nd hydraulic cylinder 2 to perform the telescopic operation will be described. Hereinafter, a case will be described in which the 1 st control valve 20 is switched to the 1 st extension position 20B to cause the 1 st hydraulic cylinder 1 to perform the extension operation, and the 2 nd control valve 30 is switched to the 2 nd extension position 30B to cause the 2 nd hydraulic cylinder 2 to perform the extension operation, as a combined operation.
Since the case of performing the extension operation of the 1 st hydraulic cylinder 1 in the combined operation is basically the same as the case of performing the extension operation of the 1 st hydraulic cylinder 1 alone, detailed description thereof is omitted.
When the 1 st control valve 20 is switched to the 1 st extension position 20B, the 1 st pump passage 10 is blocked. Therefore, the hydraulic oil discharged from the 1 st pump P1 is not guided to the 2 nd branch passage 14 via the 1 st pump passage 10 and the main passage 12. On the other hand, the hydraulic oil discharged from the 1 st pump P1 is guided to the 2 nd branch passage 14 through the parallel passage 15. Therefore, the hydraulic oil guided from the parallel passage 15 to the 2 nd bottom passage 9b via the 2 nd branch passage 14 is supplied to the bottom chamber 7 of the 2 nd hydraulic cylinder 2, and the 2 nd hydraulic cylinder 2 performs the extension operation.
In this way, in the combined operation when the switching valve 40 is at the 1 st switching position 40A, a part of the hydraulic oil discharged from the 1 st pump P1 is guided to the 1 st hydraulic cylinder 1 through the 1 st pump passage 10, and the remaining hydraulic oil discharged from the 1 st pump P1 is guided to the 2 nd hydraulic cylinder 2 through the parallel passage 15.
In the compound operation, the 2 nd control valve 30 is switched to the 2 nd extension position 30B or the 2 nd contraction position 30C. Therefore, when the 1 st hydraulic cylinder 1 is caused to perform the contraction operation in the combined operation, the communication between the main passage 12 and the tank T is blocked by the 2 nd control valve 30 when the 1 st control valve 20 is switched to the 1 st contraction position 20C. Therefore, when the 1 st hydraulic cylinder 1 is caused to perform the contraction operation in the combined operation, the discharge pressure of the 1 st pump P1 is introduced into the rod side chamber 6, and the 1 st hydraulic cylinder 1 is caused to perform the contraction operation by the discharge pressure of the 1 st pump P1.
[ Jack-up ]
As described above, when the bypass cut valve 60 is in the open position 60A, the 2 nd control valve 30 is in the 2 nd neutral position 30A, and the 1 st control valve 20 is in the 1 st contraction position 20C, the 1 st pump passage 10 communicates with the tank T, and the 1 st hydraulic cylinder 1 is caused to perform the contraction operation by the load (self weight) of the boom 102. Such a retraction operation of the 1 st hydraulic cylinder 1 by the load of the boom 102 is performed in a state where the bucket 104 is not grounded.
In contrast, in the hydraulic excavator, the 1 st hydraulic cylinder 1 is contracted (the boom 102 is lowered) in a state where the bucket 104 is grounded, and thereby the jack-up operation for raising the body of the hydraulic excavator is performed. In the jack-up operation, the discharge pressure of the 1 st pump P1 is introduced into the rod side chamber 6 of the 1 st hydraulic cylinder 1, and the 1 st hydraulic cylinder 1 is caused to perform the contraction operation.
During the jack-up operation, the pilot pressure is introduced into the pilot chamber 78 of the bypass cut-off valve 60 in response to the operation of the operating lever by the operator. Thereby, the bypass cut-off valve 60 is switched to the blocking position 60B, and the 1 st pump passage 10 is blocked. Therefore, in the state where the bypass cut-off valve 60 is at the blocking position 60B, the 1 st pump passage 10 does not communicate with the tank T even if the 1 st control valve 20 is switched to the 1 st contraction position 20C. Therefore, the discharge pressure of the 1 st pump P1 is led to the rod side chamber 6 of the 1 st hydraulic cylinder 1 via the 1 st branch passage 13 and the 1 st rod side passage 8 a. Accordingly, the 1 st hydraulic cylinder 1 is caused to perform the contraction operation by the discharge pressure of the 1 st pump P1, and therefore the thrust for raising the vehicle body of the hydraulic excavator can be exerted. Thereby performing the jack-up operation.
[ 2 nd switching position 40B ]
Next, a case will be described in which the switching valve 40 is switched to the 2 nd switching position 40B and the hydraulic oil discharged from the 2 nd pump P2 is guided to the 2 nd control valve 30. When the switching valve 40 is switched to the 2 nd switching position 40B, the 2 nd pump passage 11 and the main passage 12 communicate with each other, and the 1 st pump passage 10 communicates with the tank T via the 4 th tank passage 16 d. In addition, even when the switching valve 40 is in the 1 st switching position 40A and the 2 nd control valve 30 is in the 2 nd neutral position 30A, the 1 st pump passage 10 communicates with the tank T. Therefore, the individual driving of the 1 st hydraulic cylinder 1 when the switching valve 40 is in the 2 nd switching position 40B is the same as the case where the switching valve 40 is in the 1 st switching position 40A. The jack-up operation is the same regardless of the position of the switching valve 40. Therefore, the individual driving and the compound operation of the 2 nd hydraulic cylinder 2 will be described below.
[ Individual drive of the 2 nd hydraulic cylinder 2 ]
When the switching valve 40 is in the 2 nd switching position 40B, the hydraulic oil discharged from the 2 nd pump P2 is guided to the 2 nd branch passage 14 via the main passage 12. Further, when the switching valve 40 is in the 2 nd switching position 40B, the 1 st pump passage 10 communicates with the tank T, and therefore the parallel passage 15 also communicates with the tank T. Therefore, the hydraulic oil discharged from the 1 st pump P1 is not guided to the 2 nd branch passage 14, and only the hydraulic oil discharged from the 2 nd pump P2 is guided.
Therefore, by switching the 2 nd control valve 30, the hydraulic oil discharged from the 2 nd pump P2 is guided to the 2 nd hydraulic cylinder 2 through the 2 nd branch passage 14. In this way, when the switching valve 40 is at the 2 nd switching position 40B, the 2 nd hydraulic cylinder 2 is driven by the hydraulic fluid discharged from the 2 nd pump P2.
[ Compound action ]
When the switching valve 40 is in the 2 nd switching position 40B and the 1 st control valve 20 is switched to the 1 st contraction position 20C, the 1 st pump passage 10 communicates with the working fluid tank T via the pump restrictor 23. Therefore, the hydraulic oil discharged from the 1 st pump P1 is not guided to the parallel passage 15, but only the hydraulic oil discharged from the 2 nd pump P2 is guided to the 2 nd branch passage 14.
Further, when the switching valve 40 is in the 2 nd switching position 40B, the 1 st pump passage 10 is blocked when the 1 st control valve 20 is switched to the 1 st extension position 20B. Therefore, the hydraulic oil discharged from the 1 st pump P1 is guided to the parallel passage 15. Here, since the orifice 84 and the 3 rd check valve 83 are provided in the parallel passage 15, the flow of the hydraulic oil guided to the parallel passage 15 causes a pressure loss by the orifice 84. Further, since a part of the hydraulic oil discharged from the 1 st pump P1 is guided to the 1 st hydraulic cylinder 1, the flow rate of the hydraulic oil guided to the parallel passage 15 decreases accordingly, and the pressure also decreases. Therefore, the discharge pressure of the 2 nd pump P2 led to the 2 nd branch passage 14 is higher than the discharge pressure of the 1 st pump P1 led to the parallel passage 15. Therefore, the 3 rd check valve 83 is not opened, and the working oil passing through the parallel passage 15 is restricted from being guided to the 2 nd branch passage 14. That is, since the 3 rd check valve 83 is not opened, only the hydraulic oil discharged from the 2 nd pump P2 is guided to the 2 nd branch passage 14.
In this way, even in the combined operation in which the switching valve 40 is in the 2 nd switching position 40B, the 2 nd hydraulic cylinder 2 is driven by the hydraulic fluid discharged from the 2 nd pump P2, as in the case of driving the 2 nd hydraulic cylinder 2 alone.
As described above, when the switching valve 40 is at the 1 st switching position 40A, the 2 nd hydraulic cylinder 2 is driven by the hydraulic fluid discharged from the 1 st pump P1 both in the case of the 2 nd hydraulic cylinder 2 being driven alone and in the case of the compound operation. When the switching valve 40 is in the 2 nd switching position 40B, the 2 nd hydraulic cylinder 2 is driven by the hydraulic fluid discharged from the 2 nd pump P2 both in the case of the 2 nd hydraulic cylinder 2 being driven alone and in the case of the compound operation.
Here, the preliminary auxiliary tool driven by the 2 nd hydraulic cylinder 2 differs depending on the type of the hydraulic excavator on which the fluid pressure control device 100 is mounted. When a large thrust force is required for driving the preliminary auxiliary equipment, the 2 nd hydraulic cylinder 2 needs to be large. Further, when the hydraulic fluid of the 1 st pump P1 is introduced to both the 1 st hydraulic cylinder 1 and the 2 nd hydraulic cylinder 2, the flow rate of the hydraulic fluid supplied to one of the 1 st hydraulic cylinder 1 and the 2 nd hydraulic cylinder 2 varies due to the operation of the other. Therefore, when the 2 nd hydraulic cylinder 2 is relatively large, the flow rate of the hydraulic fluid supplied to the 2 nd hydraulic cylinder 2 increases accordingly, and the operations of the 1 st hydraulic cylinder 1 and the 2 nd hydraulic cylinder 2 may become unstable during the combined operation.
On the contrary, the 2 nd hydraulic cylinder 2 may be small, and the flow rate of the hydraulic fluid supplied to the 1 st hydraulic cylinder 1 and the 2 nd hydraulic cylinder 2 may be allowed to vary during the combined operation. In this case, by driving both the 1 st hydraulic cylinder 1 and the 2 nd hydraulic cylinder 2 with the hydraulic fluid of the 1 st pump P1, the 2 nd pump P2 can be eliminated and the 2 nd pump P2 can be applied to the driving of the other hydraulic cylinders, which is advantageous in terms of cost and efficiency.
In the fluid pressure control device 100, the position of the switching valve 40 is switched by manual operation, so that it is possible to select whether the hydraulic fluid is introduced from the 1 st pump P1 to the 2 nd hydraulic cylinder 2 or the hydraulic fluid is introduced from the 2 nd pump P2 to the 2 nd hydraulic cylinder 2, according to the type of the hydraulic excavator or the user's demand. Since the pump that supplies the hydraulic oil to the 2 nd hydraulic cylinder 2 can be selected by switching the switching valve 40, the piping structure of the fluid pressure control device 100 can be shared regardless of which pump the user drives the 2 nd hydraulic cylinder 2. Therefore, the manufacturing cost of the fluid pressure control device 100 can be reduced.
In other words, by manually switching the position of the switching valve 40, the same fluid pressure control device 100 can be used for different hydraulic excavators and for different needs of users, and the manufacturing cost is reduced.
In the fluid pressure control device 100, the bypass passage 15 branched from the 1 st main passage 10 is connected to the 2 nd branch passage 14. No matter which position the 2 nd control valve 30 is, the 2 nd branch passage 14 is not communicated with the working fluid tank T. When the switching valve 40 is switched to the 2 nd switching position 40B, the 3 rd check valve 83 is closed by the discharge pressure of the 2 nd pump P2, and therefore the discharge pressure of the 1 st pump P1 is not guided to the 2 nd control valve. Therefore, when the switching valve 40 is in the 2 nd switching position 40B, the hydraulic oil discharged from the 1 st pump P1 is not guided to the hydraulic tank T or other devices via the bypass passage 15 regardless of the position of the 2 nd control valve 30 when the 1 st hydraulic cylinder 1 is caused to perform the extension operation. In this way, in the fluid pressure control device 100, when the switching valve 40 is set to the 2 nd switching position 40B and the 1 st hydraulic cylinder 1 and the 2 nd hydraulic cylinder 2 are independent of each other, all of the hydraulic fluid discharged from the 1 st pump P1 can be guided to the 1 st hydraulic cylinder 1 to cause the 1 st hydraulic cylinder 1 to perform the extension operation. That is, in the fluid pressure control device 100, the hydraulic oil discharged from the 1 st pump P1 can be effectively used even when the switching valve 40 is switched to the 2 nd switching position 40B. In the present embodiment, even if the switching valve 40 is in the 1 st switching position 40A, the communication between the bypass passage 15 and the tank T is blocked and the hydraulic fluid is guided to the 2 nd hydraulic cylinder 2 through the bypass passage 15. Therefore, even when the switching valve 40 is at the 1 st switching position 40A, the hydraulic oil discharged from the 1 st pump P1 can be effectively used.
Next, specific configurations of the switching valve 40 and the bypass cut-off valve 60 will be described with reference to fig. 4 and 5.
As shown in fig. 4, the fluid pressure control device 100 includes a housing 90 for housing the switching valve 40 and the bypass cut-off valve 60. The housing 90 is formed with a receiving hole 91 which is a through hole having both ends opened to the end surfaces 90a and 90b of the housing 90. The receiving hole 91 is a through hole having a uniform inner diameter.
The housing 90 is formed with a 1 st pump passage 10, a 2 nd pump passage 11, a main passage 12, a 3 rd tank passage 16c, and a 4 th tank passage 16d, which are each opened to the inner peripheral surface of the housing hole 91 through an annular port (reference numeral omitted). An annular drain port 18a communicating with the working fluid tank T is formed in the housing 90 so as to open to the inner circumferential surface of the housing hole 91. Hereinafter, the portion of the 1 st pump passage 10 on the upstream side of the bypass cut-off valve 60 is also referred to as an "upstream passage 10 a", and the portion of the 1 st pump passage 10 on the downstream side of the bypass cut-off valve 60 is also referred to as a "downstream passage 10 b".
The switching valve 40 has a 1 st spool 41 slidably inserted into the receiving hole 91. The bypass cut-off valve 60 has a 2 nd spool 61 slidably inserted into the housing hole 91. The 1 st spool 41 of the switching valve 40 and the 2 nd spool 61 of the bypass cut-off valve 60 are housed in the housing hole 91 so as to be opposed to each other and coaxially.
The switching valve 40 includes a 1 st cover 50 attached to an end surface 90a of the housing 90 and sealing one opening of the receiving hole 91, a 1 st spring 51 provided in the 1 st cover 50 and biasing the 1 st spool 41 in a direction (left direction in the drawing) away from the 2 nd spool 61, a pair of 1 st spring seats 52, 53 as a pair of 1 st lowering members in which both ends of the 1 st spring 51 are lowered and which move relative to each other in accordance with expansion and contraction of the 1 st spring 51, a switching portion 55 attached to the 1 st cover 50 and moving the 1 st spool 41 against the biasing force of the 1 st spring 51 in accordance with a manual operation, an internal pressure chamber 58 formed inside the 1 st cover 50, and an introduction port 50c formed in the 1 st cover 50 and guiding the pilot pressure to the internal pressure chamber 58.
The 1 st spool 41 has a 1 st body portion 42 in sliding contact with the inner peripheral surface of the receiving hole 91, and a 1 st support portion 46 attached to one end (left end in the drawing) of the 1 st body portion 42.
The 1 st body portion 42 has a 1 st shoulder portion 42a, a 2 nd shoulder portion 42b, and a 3 rd shoulder portion 42c that are in sliding contact with the inner peripheral surface of the receiving hole 91 and are arranged in the axial direction. A 1 st annular groove 43a is formed in the outer peripheral surface between the 1 st shoulder portion 42a and the 2 nd shoulder portion 42b, and a 2 nd annular groove 43b is formed in the outer peripheral surface between the 2 nd shoulder portion 42b and the 3 rd shoulder portion 42 c.
A 1 st small diameter portion 44 having an outer diameter smaller than the inner diameter of the housing hole 91 and a 2 nd small diameter portion 45 provided on one end side (the 1 st support portion 46 side, the left side in the drawing) of the 1 st small diameter portion 44 and having an outer diameter smaller than the 1 st small diameter portion 44 are formed at one end of the 1 st body portion 42. An annular space 43c is formed between the 1 st small diameter portion 44 and the receiving hole 91. The 2 nd small diameter portion 45 corresponds to the 1 st projecting portion, and the 1 st projecting portion projects in the axial direction from the 1 st small diameter portion 44 toward the 1 st supporting portion 46, and the 1 st supporting portion 46 abuts against.
As shown in fig. 5, the 1 st supporting portion 46 is housed inside the 1 st cover 50. The 1 st support portion 46 has a 1 st shaft portion 47 and a 1 st head portion 48 having an outer diameter larger than that of the 1 st shaft portion 47, and the 1 st shaft portion 47 has a screw portion 47a screwed to the 2 nd small diameter portion 45 at one end of the 1 st body portion 42. The 1 st support portion 46 is detachably attached to the 1 st body portion 42 by screwing the screw portion 47a of the 1 st shaft portion 47 to the 1 st body portion 42.
The 1 st shaft portion 47 has substantially the same outer diameter as the 2 nd small diameter portion 45 of the 1 st body portion 42, and is attached to the 2 nd small diameter portion 45 coaxially with the 2 nd small diameter portion 45. A slit 48a extending in the radial direction is formed in the end surface of the 1 st head 48.
The 1 st cap 50 is formed with a 1 st large-diameter hole 50a communicating with the housing hole 91 and allowing the 1 st spool 41 to enter, a 1 st small-diameter hole 50b communicating with the 1 st large-diameter hole 50a and having a smaller inner diameter than the 1 st large-diameter hole 50a, and an introduction port 50c communicating with the 1 st large-diameter hole 50 a. The 1 st small-diameter hole 50b and the 1 st large-diameter hole 50a form an internal pressure chamber 58. The 1 st head 48 of the 1 st bearing portion 46 enters the 1 st small-diameter hole 50 b.
The 1 st spring 51 is provided on the outer periphery of the 1 st shaft portion 47 of the 1 st support portion 46, and both ends of the 1 st spring 51 are supported by a pair of 1 st spring seats 52, 53. One 1 st spring seat 52 is seated on the step surface 50d between the 1 st large-diameter hole 50a and the 1 st small-diameter hole 50b, and the other 1 st spring seat 53 is seated on the end surface 90a of the housing 90 on which the 1 st cover 50 is mounted. With expansion and contraction of the 1 st spring 51 (movement of the 1 st spool 41), one 1 st spring seat 52 relatively moves with respect to the other 1 st spring seat 53 in the axial direction of the 1 st spool 41. The 1 st spring 51 is interposed in a compressed state between a pair of 1 st spring seats 52, 53. The 1 st spring 51 applies a biasing force that moves the 1 st spool 41 to bring the switching valve 40 into the 1 st switching position 40A (in other words, to separate the 1 st spool 41 from the 2 nd spool 61 of the bypass cut valve 60).
The pair of 1 st spring seats 52, 53 are formed in the same shape as each other. As shown in fig. 5, the first 1 st spring seat 52 includes a disc-shaped flange portion 52a that contacts the stepped surface 50d between the 1 st large-diameter hole 50a and the 1 st small-diameter hole 50b of the 1 st cover 50, and a cylindrical boss portion 52b that extends in the axial direction from the flange portion 52a toward the other 1 st spring seat 53. One end of the 1 st spring 51 is seated on the flange portion 52 a. The boss portion 52b is inserted into the 1 st spring 51 and supports the inner periphery of the 1 st spring 51. The flange portion 52a is formed to have an inner diameter smaller than an outer diameter of the 1 st head portion 48. A slit 52c extending in the radial direction is formed in an end surface of the flange portion 52a that contacts the step surface 50d between the 1 st large-diameter hole 50a and the 1 st small-diameter hole 50 b.
The other 1 st spring seat 53 has a disk-shaped flange portion 53a that contacts the end surface 90a of the housing 90, and a cylindrical boss portion 53b that extends in the axial direction from the flange portion 53a toward the one 1 st spring seat 52. The other end of the 1 st spring 51 is seated on the flange portion 53 a. The boss portion 53b is inserted into the 1 st spring 51 and supports the inner periphery of the 1 st spring 51. A slit 53c extending in the radial direction is formed in an end surface of the flange portion 53a that contacts the end surface 90a of the housing 90.
The switching portion 55 includes a switching bolt 56 that is screwed into a screw hole 50e formed in the 1 st cover 50 and is manually moved forward and backward with respect to the 1 st spool 41, and a regulating nut 57 for regulating a change in a screw-coupling position at which the switching bolt 56 is screwed into the screw hole 50 e. The screw hole 50e is formed in the 1 st cover 50 so as to communicate with the internal pressure chamber 58 (the 1 st small-diameter hole 50 b).
The switching bolt 56 is provided coaxially with the 1 st support portion 46 of the 1 st spool 41. The switching bolt 56 includes a threaded portion 56a formed with a male screw that is threaded into the threaded hole 50e, a contact portion 56b that axially contacts the 1 st head portion 48 of the 1 st spool 41, and an operating portion 56c that is operated by the operator. The contact portion 56b is received in the 1 st small-diameter hole 50 b. A part of the screw coupling portion 56a protrudes outward from the 1 st cover 50, and an operation portion 56c is provided at the protruding end of the screw coupling portion 56 a. The operator grips the operating portion 56c and rotates it to adjust the screw-coupling position at which the screw-coupling portion 56a is screw-coupled to the screw hole 50 e.
The restricting nut 57 is screwed to a portion of the screw joint portion 56a exposed to the outside of the 1 st cover 50. By screwing the regulating nut 57 screwed to the switching bolt 56 to the 1 st cover 50, the change in the screwing position at which the switching bolt 56 is screwed to the screw hole 50e of the 1 st cover 50 is regulated. Conversely, by loosening the regulating nut 57 to generate a gap between the regulating nut 57 and the 1 st cover 50, the screw engagement position at which the switching bolt 56 is screwed into the screw hole 50e of the 1 st cover 50 can be adjusted, and the switching bolt 56 can be advanced and retracted relative to the 1 st spool 41.
As shown in fig. 4, the bypass cut valve 60 includes a 2 nd cover 70 attached to the end surface 90b of the housing 90 and sealing the other opening of the receiving hole 91, a 2 nd spring 71 provided in the 2 nd cover 70 and biasing the 2 nd spool 61 in a direction (right direction in the drawing) away from the 1 st spool 41, a pair of 2 nd spring seats 72, 73 as a pair of 2 nd falling members in which both ends of the 2 nd spring 71 fall and which move relative to each other in accordance with the expansion and contraction of the 2 nd spring 71, and a pilot chamber 78 formed inside the 2 nd cover 70.
The 2 nd spool 61 has a 2 nd main body portion 62 in sliding contact with the inner peripheral surface of the receiving hole 91, and a 2 nd support portion 66 attached to one end (right end in the drawing) of the 2 nd main body portion 62.
The 2 nd body portion 62 has a 4 th shoulder portion 62a, a 5 th shoulder portion 62b, a 6 th shoulder portion 62c, and a 7 th shoulder portion 62d which are respectively in sliding contact with the inner peripheral surface of the receiving hole 91 and are arranged in the axial direction. A 3 rd annular groove 63a is formed in the outer peripheral surface between the 4 th shoulder portion 62a and the 5 th shoulder portion 62 b. A 4 th annular groove 63b is formed in the outer peripheral surface between the 5 th shoulder portion 62b and the 6 th shoulder portion 62 c. A 5 th annular groove 63c is formed in the outer peripheral surface between the 6 th shoulder portion 62c and the 7 th shoulder portion 62 d. The 5 th annular groove 63c always communicates with the drain port 18a regardless of the position of the 2 nd spool 61.
A 3 rd small diameter portion 64 having an outer diameter smaller than the inner diameter of the receiving hole 91 and protruding from the 2 nd main body portion 62 in the axial direction is formed at one end portion of the 2 nd main body portion 62. The 3 rd small diameter portion 64 corresponds to a 2 nd projecting portion, and the 2 nd projecting portion projects in the axial direction from the 2 nd main body portion 62 toward the 2 nd support portion 66, and the 2 nd support portion 66 abuts against.
The 2 nd support portion 66 is housed inside the 2 nd cover 70. The 2 nd support portion 66 has a 2 nd shaft portion 67 and a 2 nd head portion 68 having an outer diameter larger than that of the 2 nd shaft portion 67, and the 2 nd shaft portion 67 has a screw portion 67a screwed to one end portion of the 2 nd body portion 62 of the 2 nd spool 61. The 2 nd support part 66 is detachably attached to the 2 nd body part 62 with respect to the 2 nd body part 62 by screwing the screw part 67a of the 2 nd shaft part 67.
The 2 nd shaft portion 67 has substantially the same outer diameter as the 3 rd small diameter portion 64 of the 2 nd body portion 62, and is attached to the 3 rd small diameter portion 64 coaxially with the 3 rd small diameter portion 64.
The 2 nd head 70 is formed with a 2 nd large diameter hole 70a communicating with the housing hole 91 and into which the 2 nd spool 61 can enter, a 2 nd small diameter hole 70b communicating with the 2 nd large diameter hole 70a and having a smaller inner diameter than the 2 nd large diameter hole 70a, and a pilot port 70c communicating with the 2 nd small diameter hole 70 b. The pilot chamber 78 is formed by the 2 nd small-diameter hole 70b and the 2 nd large-diameter hole 70 a. The 2 nd head 68 of the 2 nd support part 66 enters the 2 nd small-diameter hole 70 b.
The 2 nd spring 71 is provided on the outer periphery of the 2 nd shaft portion 67 of the 2 nd support portion 66, and both ends of the 2 nd spring 71 are supported by a pair of 2 nd spring seats 72 and 73. One 2 nd spring seat 72 is seated on the step surface 70d between the 2 nd large-diameter hole 70a and the 2 nd small-diameter hole 70b of the 2 nd cover 70, and the other 2 nd spring seat 73 is seated on the other end surface 90b of the housing 90. The 2 nd spring 71 is interposed in a compressed state between the pair of 2 nd spring seats 72, 73. The 2 nd spring 71 applies a biasing force that moves the 2 nd spool 61 so that the bypass cut valve 60 is in the open position 60A (in other words, the 2 nd spool 61 is away from the 1 st spool 41 of the switching valve 40).
The pair of 2 nd spring seats 72, 73 are formed in the same shape as each other. The one 2 nd spring seat 72 includes a disc-shaped flange portion 72a that contacts the stepped surface 70d between the 2 nd large-diameter hole 70a and the 2 nd small-diameter hole 70b of the 2 nd cap 70, and a cylindrical boss portion 72b that extends in the axial direction from the flange portion 72a toward the other 2 nd spring seat 73. The flange portion 72a is formed to have an inner diameter smaller than an outer diameter of the 2 nd head portion 68.
The other 2 nd spring bearing 73 has a disk-shaped flange portion 73a that contacts the end surface 90b of the housing 90, and a cylindrical boss portion 73b that extends in the axial direction from the flange portion 73a toward the one 2 nd spring bearing 72. Both ends of the 2 nd spring 71 are seated on flange portions 72a, 73a of the 2 nd spring seats 72, 73, respectively, and boss portions 72b, 73b are inserted into the 2 nd spring 71, respectively, and support the inner periphery of the 2 nd spring 71.
Regardless of the positions of the switching valve 40 and the bypass cut valve 60, the 1 st spool 41 and the 2 nd spool 61 are axially separated without contacting each other. An inner space 92 is formed by an end of the 1 st spool 41 and an end of the 2 nd spool 61 in the receiving hole 91.
The internal pressure chamber 58 inside the 1 st cover 50 is always in communication with the working fluid tank T through the drain passage 18. The drain passage 18 includes a slit 53c (see fig. 5) of the 1 st spring seat 53, an annular space 43c of the outer periphery of the 1 st small diameter portion 44 of the 1 st spool 41, a 1 st internal passage 49 formed in the 1 st body portion 42 of the 1 st spool 41, an internal space 92 between the 1 st spool 41 and the 2 nd spool 61, a 2 nd internal passage 69 formed in the 2 nd body portion 62 of the 2 nd spool 61, and a drain port 18a formed in the housing 90.
The 1 st internal passage 49 has formed therein: a 1 st axial passage 49a that passes through the axial center of the 1 st body portion 42, opens to an end surface of the 1 st spool 41 that faces the 2 nd spool 61, and communicates with the internal space 92; and a throttle passage 49b communicating with the 1 st axial passage 49a and opening into the annular space 43c on the outer periphery of the 1 st small diameter portion 44.
The 2 nd internal passage 69 has: a 2 nd axial passage 69a that passes through the axial center of the 2 nd body portion 62, opens to an end surface of the 2 nd spool 61 that faces the 1 st spool 41, and communicates with the internal space 92; and a radial passage 69b communicating with the 2 nd axial passage 69a and opening to the 5 th annular groove 63 c. Since the 5 th annular groove 63c always communicates with the drain port 18a regardless of the position of the 2 nd spool 61, the internal pressure chamber 58 in the 1 st cap 50 always communicates with the working fluid tank T through the drain passage 18. By always communicating the internal pressure chamber 58 in the 1 st cap 50 with the tank T, an erroneous operation in which the 1 st spool 41 moves due to the accumulation of pressure in the 1 st cap 50 is prevented.
The orifice passage 49b formed in the 1 st body portion 42 is an orifice portion for applying resistance to the flow of the hydraulic oil passing therethrough. The orifice passage 49b is a passage having the largest resistance to the flow of the hydraulic oil in the flow passage through which the hydraulic oil flows from the internal pressure chamber 58 to the drain port 18 a. The throttle portion may be formed of a throttle plug or the like detachably attached to the drain passage 18.
Next, the operation of the switching valve 40 and the bypass cut-off valve 60 will be described with reference to fig. 4, 6, and 7.
When the switching valve 40 is manually switched from the 1 st switching position 40A (the state shown in fig. 4) to the 2 nd switching position 40B (the state shown in fig. 6), the control nut 57 is loosened, and the switching bolt 56 is rotated to move toward the 1 st spool 41. Thereby, the 1 st spool 41 is pressed by the switching bolt 56 and moved against the biasing force of the 1 st spring 51. Further, as the 1 st spool 41 moves against the biasing force of the 1 st spring 51, the 1 st head 48 presses the one 1 st spring seat 52 and moves toward the other 1 st spring seat 53.
The 1 st spool 41 moves against the biasing force of the 1 st spring 51 until the boss portions 52b, 53b of the pair of 1 st spring seats 52, 53 abut against each other. In other words, the pair of 1 st spring seats 52, 53 abut against each other, whereby the 1 st spool 41 is restricted from moving against the biasing force of the 1 st spring 51. When the 1 st spool 41 moves until the pair of 1 st spring seats 52, 53 abut against each other, as shown in fig. 6, the 2 nd pump passage 11 communicates with the main passage 12 via the 2 nd annular groove 43 b. Further, the communication between the downstream passage 10b of the 1 st pump passage 10 and the main passage 12 is blocked by the 2 nd land portion 42b, while the downstream passage 10b of the 1 st pump passage 10 communicates with the 4 th tank passage 16d via the 1 st annular groove 43 a. In this state, the change in the screw engagement position of the switching bolt 56 (the position of the 1 st spool 41) is restricted by tightening the restricting nut 57 to the housing 90. Thus, the switching valve 40 is switched to the 2 nd switching position 40B.
When the switching valve 40 is switched from the 2 nd switching position 40B (the state shown in fig. 6) to the 1 st switching position 40A (the state shown in fig. 4), the limiting nut 57 is loosened, and the switching bolt 56 is rotated so as to be away from the 1 st spool 41. Thus, the 1 st spool 41 receives the biasing force of the 1 st spring 51, and moves together with the one 1 st spring seat 52 following the switching bolt 56 that is apart from the 1 st spool 41. The 1 st spool 41 receives the biasing force of the 1 st spring 51 and moves until one 1 st spring seat 52 abuts against the step surface 50d between the 1 st large-diameter hole 50a and the 1 st small-diameter hole 50 b. When the 1 st spool 41 moves until the 1 st spring seat 52 abuts against the step surface 50d between the 1 st large-diameter hole 50a and the 1 st small-diameter hole 50b, as shown in fig. 4, the downstream passage 10b of the 1 st pump passage 10 and the main passage 12 communicate with each other through the 1 st annular groove 43 a. The 2 nd pump passage 11 communicates with the 3 rd tank passage 16c through the 2 nd annular groove 43 b. In this state, the change in the screw engagement position of the switching bolt 56 is restricted by tightening the restricting nut 57 to the housing 90. Thus, the switching valve 40 switches from the 2 nd switching position 40B to the 1 st position 40A.
As described above, the switching valve 40 can be switched in position by manually operating the switching unit 55.
In general, in a fluid pressure control device incorporating a switching valve that is switched by manual operation, inspection at shipment may be performed by an automatic inspection line in an inspection process at the time of manufacture. However, when a manually operated switching valve is incorporated into a fluid pressure control device, it is necessary for an operator to manually check the operation of the switching valve independently of the inspection of an automatic inspection line. In addition, when the space around the switching portion of the switching valve is small, it is difficult to operate the switching portion, and a large number of steps are required to check the operation of the switching valve. In this way, even a manually operated switching valve is intended to be operated in response to an external signal, such as when the operation of the switching valve is checked by an automatic check line together with the fluid pressure control device. However, in the manual switching valve, in order to prevent an erroneous operation due to the pressure accumulation in the 1 st cap, it is desirable to communicate the inside of the 1 st cap with the working fluid tank. Therefore, generally, even if the pilot pressure is supplied to the inside of the 1 st head, the pilot pressure does not act on the 1 st spool, and it is difficult to move the 1 st spool.
In contrast, in the switching valve 40 of the present embodiment, the orifice passage 49b is provided in the drain passage 18 for guiding the working oil in the internal pressure chamber 58 of the 1 st cap 50 to the working fluid tank T. Thus, although the inner pressure chamber 58 is always in communication with the tank T, resistance is applied to the hydraulic oil passing through the orifice passage 49 b. Therefore, the throttle passage 49b can maintain a predetermined pressure without reducing the pressure of the internal pressure chamber 58 to which the pilot pressure is led to the tank pressure. Thus, when the pilot pressure is supplied to the internal pressure chamber 58 in the state where the switching valve 40 is at the 1 st switching position 40A, a pressure equal to or higher than the tank pressure acts on the slit 48a of the 1 st head 48 through the slit 52c of the flange portion 52a of the one 1 st spring seat 52 (see fig. 4). The 1 st spool 41 is biased against the biasing force of the 1 st spring 51 by the pressure acting on the 1 st head 48. Therefore, as shown in fig. 7, even if the switching unit 55 is not operated, the switching valve 40 is switched to the 2 nd switching position 40B by the pressure generated in the internal pressure chamber 58 while the pilot pressure is supplied to the internal pressure chamber 58. When the supply of the pilot pressure to the internal pressure chamber 58 is stopped, the pressure of the internal pressure chamber 58 is discharged to the working fluid tank T via the drain passage 18. Therefore, the 1 st spool 41 moves by receiving the biasing force of the 1 st spring 51, and is switched to the 1 st switching position 40A.
As described above, the switching valve 40 may be switched by a pilot pressure in addition to a manual operation. Even in the case of the manually operated switching valve 40, since the switching valve 40 can be operated in response to an external signal, the operation of the switching valve 40 can be checked by an automatic inspection line, and the number of man-hours required for the inspection process can be reduced. The operation of the switching valve 40 by the pilot pressure is not limited to the case of performing the inspection in the automatic inspection line, and may be performed in other situations.
In a state where the pilot pressure is not led into the pilot chamber 78, the bypass cut valve 60 is held at the open position 60A by the biasing force of the 2 nd spring 71. At the open position 60A, as shown in fig. 4, the upstream passage 10A and the downstream passage 10b communicate with each other via the 3 rd annular groove 63a and the 4 th annular groove 63b of the 2 nd spool 61, and the 1 st pump passage 10 is open.
When the bypass cut-off valve 60 is switched from the open position 60A (the state shown in fig. 4) to the blocking position 60B (the state shown in fig. 6), the pilot pressure is introduced into the pilot chamber 78 of the bypass cut-off valve 60. Thereby, the 2 nd spool 61 receives the pilot pressure and moves against the biasing force of the 2 nd spring 71. The 2 nd spool 61 moves against the biasing force of the 2 nd spring 71 until the boss portions 72b, 73b of the pair of 2 nd spring seats 72, 73 abut against each other. Thereby, as shown in fig. 6, the communication between the upstream passage 10a and the downstream passage 10b is blocked by the 5 th shoulder portion 62b and the 6 th shoulder portion 62c of the 2 nd spool 61, and the 1 st pump passage 10 is blocked. Thus, the bypass cut-off valve 60 is at the blocking position 60B.
As described above, even in the state where the switching valve 40 is switched to the 2 nd switching position 40B and the bypass cut valve 60 is switched to the blocking position 60B, the 1 st spool 41 and the 2 nd spool 61 do not contact each other but are separated (see fig. 6). Therefore, the switching valve 40 and the bypass cut valve 60 are prevented from affecting each other in operation.
Further, since the switching valve 40 and the bypass cut-off valve 60 are both two-position spool valves, the 1 st spool 41 and the 2 nd spool 61 can be inserted into one receiving hole 91 coaxially with each other. In this case as well, the operations of the switching valve 40 and the bypass cut-off valve 60 do not affect each other. Therefore, as compared with the case where the 1 st spool 41 and the 2 nd spool 61 are inserted into different receiving holes, the housing 90 can be made smaller, and the cost for processing the receiving hole 91 can be reduced.
Next, a modification of the present embodiment will be described. The following modifications are also within the scope of the present invention, and the following modifications may be combined with the respective configurations of the above-described embodiments, or the following modifications may be combined with each other.
In the above embodiment, the 1 st spool 41 of the switching valve 40 and the 2 nd spool 61 of the bypass cut-off valve 60 are inserted into the receiving hole 91 which is a through hole having a uniform inner diameter. Further, an inner space 92 is formed between the 1 st spool 41 and the 2 nd spool 61. In contrast, for example, a partition wall may be provided between the 1 st spool 41 and the 2 nd spool 61, and the storage hole 91 in which the 1 st spool 41 is stored and the storage hole 91 in which the 2 nd spool 61 is stored may be partitioned by the partition wall. In this case, in order to discharge the pressure of the internal pressure chamber 58 in the 1 st cap 50 to the working fluid tank T, it is desirable to form a hole in the partition wall portion to communicate with the receiving holes 91 that receive the 1 st spool 41 and the 2 nd spool 61. In this case, the partition wall may be provided with a throttle portion.
According to the above embodiment, the following effects are obtained.
In the fluid pressure control device 100, the position of the switching valve 40 is switched by manual operation, so that it is possible to select whether the hydraulic fluid is introduced from the 1 st pump P1 to the 2 nd hydraulic cylinder 2 or the hydraulic fluid is introduced from the 2 nd pump P2 to the 2 nd hydraulic cylinder 2, according to the type of the hydraulic excavator or the user's demand. Since the pump that supplies the hydraulic oil to the 2 nd hydraulic cylinder 2 can be selected by switching the switching valve 40, the piping structure of the fluid pressure control device 100 can be shared regardless of which pump the user drives the 2 nd hydraulic cylinder 2. Therefore, the manufacturing cost of the fluid pressure control device 100 can be reduced.
In the fluid pressure control device 100, the 1 st spool 41 of the switching valve 40 and the 2 nd spool 61 of the bypass cut-off valve 60 are inserted into one housing hole 91 in an opposed manner. This prevents the size of the housing 90 from increasing, and reduces the manufacturing cost.
In the fluid pressure control device 100, since the orifice passage 49b as the orifice portion is formed in the drain passage 18, the switching valve 40 can be switched in position by a manual operation and also can be switched in position by the pilot pressure supplied to the internal pressure chamber 58. This makes it possible to check the operation of the manually operated switching valve 40, for example, by an automatic check line, and to easily manufacture the fluid pressure control device 100.
Hereinafter, the structure, operation and effects of the embodiments of the present invention will be described in summary.
The fluid pressure control device 100 includes: a 1 st pump passage 10 for introducing the hydraulic oil discharged from the 1 st pump P1; a 2 nd pump passage 11 for introducing the hydraulic oil discharged from the 2 nd pump P2; a main passage 12 that selectively guides the working oil discharged from the 1 st pump P1 or the 2 nd pump P2 and communicates with the working fluid tank T; a 1 st control valve 20 provided in the 1 st pump passage 10 and controlling the flow of the hydraulic fluid supplied to the 1 st hydraulic cylinder 1 and discharged from the 1 st hydraulic cylinder 1; a 2 nd control valve 30 provided in the main passage 12 and controlling the flow of the hydraulic fluid supplied to the 2 nd hydraulic cylinder 2 and discharged from the 2 nd hydraulic cylinder 2; a 2 nd branch passage 14 that branches from the main passage 12 and guides the working oil to the 2 nd control valve 30; a parallel passage 15 that branches from the 1 st pump passage 10 and is connected to the 2 nd branch passage 14; a 3 rd check valve 83 provided in the parallel passage 15 and allowing the hydraulic oil to flow only from the 1 st pump P1 to the 2 nd branch passage 14; and a switching valve 40 provided in the main passage 12 for selectively switching a passage communicating with the main passage 12, out of the 1 st pump passage 10 and the 2 nd pump passage 11, wherein the switching valve 40 has a 1 st switching position 40A for communicating the 1 st pump passage 10 with the main passage 12 and a 2 nd switching position 40B for communicating the 2 nd pump passage 11 with the main passage 12.
In this configuration, when the switching valve 40 is set to the 1 st switching position 40A, the main passage 12 for introducing the hydraulic oil to the 2 nd control valve 30 communicates with the 1 st pump passage 10, and the hydraulic oil discharged from the 1 st pump P1 is introduced to the 2 nd control valve 30. Therefore, the 1 st hydraulic cylinder 1 and the 2 nd hydraulic cylinder 2 are both operated by the hydraulic fluid discharged from the 1 st pump P1. When the switching valve 40 is set to the 2 nd switching position 40B, the main passage 12 communicates with the 2 nd pump passage 11, and the hydraulic oil discharged from the 2 nd pump P2 is introduced to the 2 nd control valve 30. Therefore, the 1 st hydraulic cylinder 1 and the 2 nd hydraulic cylinder 2 are operated independently of each other by the hydraulic fluid discharged from the 1 st pump P1 and the hydraulic fluid discharged from the 2 nd pump P2, respectively. By switching the position of the switching valve 40 in this way, it is possible to select whether the hydraulic oil from the 1 st pump P1 or the hydraulic oil from the 2 nd pump P2 is introduced to the 2 nd control valve 30. Therefore, the piping structure can be shared regardless of which of the 1 st pump P1 and the 2 nd pump P2 leads the hydraulic oil to the 2 nd control valve 30. Thus, the manufacturing cost of the fluid pressure control device 100 is reduced.
Further, in the fluid pressure control device 100, the 1 st actuator is a hydraulic cylinder that performs an expansion and contraction operation in accordance with a pressure difference between the bottom side chamber 7 and the rod side chamber 6 on which a load of the boom 102 acts, the 1 st control valve 20 has a 1 st neutral position 20A at which the 1 st pump passage 10 is opened and a 1 st contraction position 20C at which the 1 st pump passage 10 is opened and the 1 st pump passage 10 and the rod side chamber 6 are communicated, the 2 nd control valve 30 has a 2 nd neutral position 30A at which the main passage 12 and the tank T are communicated and supply positions (a 2 nd extension position 30B and a 2 nd contraction position 30C) at which the hydraulic oil introduced from the 2 nd branch passage 14 is supplied to the 2 nd hydraulic cylinder 2, the switching valve 40 communicates the 2 nd pump passage 11 and the tank T at the 1 st switching position 40A and communicates the 1 st pump passage 10 and the tank T at the 2 nd switching position 40B, a bypass cut-off valve 60 for switching between opening and closing of the 1 st pump passage 10 is provided downstream of the 1 st control valve 20 in the 1 st pump passage 10.
In this configuration, the bypass cut valve 60 opens the 1 st pump passage 10 in a state where the switching valve 40 is at the 1 st switching position 40A, the 2 nd control valve 30 is at the 2 nd neutral position 30A, and the switching valve 40 is at the 2 nd switching position 40B, and the 1 st pump passage 10 communicates with the tank T when the 1 st control valve 20 is at the 1 st contraction position 20C. In this case, the hydraulic oil discharged from the 1 st pump P1 is not supplied to the 1 st hydraulic cylinder 1, and the 1 st hydraulic cylinder 1 operates under the weight of the load. On the other hand, when the 1 st control valve 20 is switched to the 1 st contraction position 20C with the 1 st pump passage 10 blocked by the bypass cut-off valve 60, the communication between the 1 st pump passage 10 and the tank T is blocked, and therefore the hydraulic fluid discharged from the 1 st pump P1 is supplied to the 1 st hydraulic cylinder 1. Therefore, the 1 st hydraulic cylinder 1 performs the contraction operation by the pressure of the hydraulic fluid discharged from the 1 st pump P1. By switching between opening and closing of the 1 st pump passage 10 by the bypass cut-off valve 60 in this way, the 1 st hydraulic cylinder 1 can be driven by both driving by the load and driving by the hydraulic pressure.
The fluid pressure control device 100 further includes a housing 90 for housing the switching valve 40 and the bypass cut-off valve 60, the switching valve 40 has a 1 st spool 41 for switching the position, the bypass cut-off valve 60 has a 2 nd spool 61 for switching the position, the 1 st spool 41 of the switching valve 40 and the 2 nd spool 61 of the bypass cut-off valve 60 are housed in a housing hole 91 so as to be opposed to each other and coaxially, and the housing hole 91 is formed in the housing 90.
In this configuration, the housing 90 can be made compact.
In the fluid pressure control device 100, the housing hole 91 is formed as a through hole having both ends opened to the end surfaces 90a and 90b of the housing 90, and the switching valve 40 further includes: a 1 st cover 50 mounted to the housing 90 for sealing one opening of the receiving hole 91; an inner pressure chamber 58 formed in the 1 st cover 50; a 1 st spring 51 provided in the 1 st cap 50 and biasing the 1 st spool 41 in a direction away from the 2 nd spool 61; and a switching unit 55 provided in the 1 st cover 50 and manually operated to move the 1 st spool 41 against the biasing force of the 1 st spring 51, the bypass cut valve 60 further including: a 2 nd cover 70 mounted to the housing 90 for sealing the other opening of the receiving hole 91; a pilot chamber 78 formed in the 2 nd cap 70 and into which a pilot pressure for biasing the 2 nd spool 61 toward the 1 st spool 41 is guided via a pilot port 70 c; and a 2 nd spring 71 provided in the 2 nd cap 70 for biasing the 2 nd spool 61 in a direction away from the 1 st spool 41.
In the fluid pressure control device 100, the 1 st cap 50 is provided with an introduction port 50c for introducing a pilot pressure for moving the 1 st spool 41 against the biasing force of the 1 st spring 51 into the internal pressure chamber 58, the internal pressure chamber 58 in the 1 st cap 50 is always communicated with the working fluid tank T through the drain passage 18, and the drain passage 18 is provided with a throttle passage 49b for applying resistance to the flow of the passing working fluid.
Further, in the fluid pressure control device 100, the drain passage 18 includes: an internal space 92 that is defined by the end portion of the 1 st spool 41 and the end portion of the 2 nd spool 61 facing each other in the receiving hole 91, the internal space 92 being defined; a 1 st internal passage 49 formed in the 1 st spool 41 and communicating the internal pressure chamber 58 with the internal space 92; and a 2 nd internal passage 69 formed in the 2 nd spool 61 and communicating the internal space 92 with the working fluid tank T.
In the above configuration, when the pilot pressure is introduced into the internal pressure chamber 58, a part of the hydraulic oil in the internal pressure chamber 58 is discharged through the drain passage 18, but a predetermined pressure is generated in the internal pressure chamber 58 because resistance is applied by the orifice passage 49 b. Therefore, by supplying the pilot pressure to the internal pressure chamber 58, the 1 st spool 41 can be moved while generating a thrust force in the internal pressure chamber 58 that moves the 1 st spool 41.
In the fluid pressure control device 100, the switching valve 40 further includes a pair of 1 st spring seats 52, 53, the pair of 1 st spring seats 52, 53 being configured such that both ends of the 1 st spring 51 are seated and moved relative to each other in accordance with expansion and contraction of the 1 st spring 51, and the bypass cut valve 60 further includes a pair of 2 nd spring seats 72, 73, the pair of 2 nd spring seats 72, 73 being configured such that both ends of the 2 nd spring 71 are seated and moved relative to each other in accordance with expansion and contraction of the 2 nd spring 71, the pair of 1 st spring seats 52, 53 are brought into contact with each other to restrict movement of the 1 st spool 41 against the biasing force of the 1 st spring 51, and the pair of 2 nd spring seats 72, 73 are brought into contact with each other to restrict movement of the 2 nd spool 61 against the biasing force of the 2 nd spring 71.
In this configuration, the movement amounts of the 1 st spool 41 and the 2 nd spool 61 can be easily set.
Further, in the fluid pressure control device 100, the 1 st spool 41 has: a 1 st body portion 42 in sliding contact with the inner peripheral surface of the receiving hole 91; and a 1 st support portion 46 attached to an end portion of the 1 st body portion 42, wherein a 1 st spring 51 is provided on an outer periphery of the 1 st support portion 46, and the 2 nd spool 61 includes: a 2 nd body portion 62 in sliding contact with the inner peripheral surface of the receiving hole 91; and a 2 nd support part 66 attached to an end of the 2 nd body part 62, wherein a 2 nd spring 71 is provided on an outer periphery of the 2 nd support part 66, the 1 st body part 42 has a 2 nd small diameter part 45, the 2 nd small diameter part 45 protrudes in the axial direction toward the 1 st support part 46, and the 1 st support part 46 abuts against the 1 st body part, and the 2 nd body part 62 has a 3 rd small diameter part 64, the 3 rd small diameter part 64 protrudes in the axial direction toward the 2 nd support part 66, and the 2 nd support part 66 abuts against the 2 rd support part 66.
In this configuration, by changing the projection amounts of the 2 nd and 3 rd small diameter portions 45 and 64, the 1 st support portion 46, the 2 nd support portion 66, the 1 st spring seats 52 and 53, and the 2 nd spring seats 72 and 73 can be used in common, and the movement amounts of the 1 st and 2 nd spools 41 and 61 can be changed.
In the fluid pressure control device 100, the housing hole 91 is a through hole having a uniform inner diameter.
In this configuration, since the inner peripheral surface of the housing hole 91 can be polished, the machining accuracy of the housing hole 91 is improved.
While the embodiments of the present invention have been described above, the above embodiments are merely examples of applications of the present invention, and the scope of the present invention is not intended to be limited to the specific configurations of the above embodiments.

Claims (9)

1. A fluid pressure control device, wherein,
the fluid pressure control device includes:
a 1 st pump passage for guiding the working fluid discharged from the 1 st pump;
a 2 nd pump passage for guiding the working fluid discharged from the 2 nd pump;
a main passage that selectively guides the working fluid discharged from the 1 st pump or the 2 nd pump;
a 1 st control valve provided in the 1 st pump passage and configured to control a flow of the working fluid supplied to and discharged from the 1 st actuator;
a 2 nd control valve provided in the main passage and controlling a flow of the working fluid supplied to and discharged from the 2 nd actuator;
a supply passage branched from the main passage for introducing the working fluid to the 2 nd control valve;
a parallel passage that branches from the 1 st pump passage and is connected to the supply passage;
a check valve provided in the parallel passage and allowing only the working fluid to flow from the 1 st pump toward the supply passage; and
a switching valve provided in the main passage for selectively switching a passage communicating with the main passage, from among the 1 st pump passage and the 2 nd pump passage,
the switching valve has a 1 st switching position at which the 1 st pump passage communicates with the main passage, and a 2 nd switching position at which the 2 nd pump passage communicates with the main passage.
2. The fluid pressure control device according to claim 1,
the 1 st actuator is a fluid pressure cylinder which performs expansion and contraction operations according to a pressure difference between a load side pressure chamber and an opposite load side pressure chamber on which a load to be driven acts,
the 1 st control valve has a 1 st neutral position at which the 1 st pump passage is opened and a drive position at which the 1 st pump passage is opened and the 1 st pump passage and the load-opposing-side pressure chamber are communicated with each other,
the 2 nd control valve has a 2 nd neutral position for communicating the main passage with a working fluid tank and a supply position for supplying the working fluid introduced from the supply passage to the 2 nd actuator,
the switching valve communicates the 2 nd pump passage and the working fluid tank at the 1 st switching position and communicates the 1 st pump passage and the working fluid tank at the 2 nd switching position,
a bypass cut-off valve for switching opening and closing of the 1 st pump passage is provided downstream of the 1 st control valve in the 1 st pump passage.
3. The fluid pressure control device according to claim 2,
the fluid pressure control device further includes a housing for housing the switching valve and the bypass cut-off valve,
the switching valve has a 1 st spool that switches positions,
the bypass cut-off valve has a 2 nd spool that switches position,
the 1 st spool of the switching valve and the 2 nd spool of the bypass cut-off valve are housed in a housing hole formed in the housing so as to be opposed to each other and coaxially.
4. The fluid pressure control device according to claim 3,
the housing hole is formed as a through hole having both ends opened to the end surface of the housing,
the switching valve further has:
a 1 st cover mounted to the housing for sealing one opening of the receiving hole;
an inner pressure chamber formed in the 1 st cover;
a 1 st urging member provided in the 1 st cap and urging the 1 st spool in a direction away from the 2 nd spool; and
a switching unit provided in the 1 st cap for manually moving the 1 st spool against the biasing force of the 1 st biasing member,
the bypass cut-off valve further has:
a 2 nd cover mounted to the housing for sealing the other opening of the receiving hole;
a pilot chamber formed in the 2 nd cap, the pilot chamber guiding a pilot pressure that urges the 2 nd spool toward the 1 st spool via a pilot port; and
and a 2 nd biasing member provided in the 2 nd cap, for biasing the 2 nd spool in a direction away from the 1 st spool.
5. The fluid pressure control device according to claim 4,
an inlet port for guiding a pilot pressure for moving the 1 st spool against the biasing force of the 1 st biasing member to the internal pressure chamber is formed in the 1 st cap,
the internal pressure chamber in the 1 st cover is always in communication with the working fluid tank via a drain passage,
the drain passage is provided with a throttle portion for applying resistance to the flow of the working fluid passing therethrough.
6. The fluid pressure control device of claim 5,
the drain passage has:
an internal space defined in the receiving hole by an end of the 1 st spool and an end of the 2 nd spool facing each other;
a 1 st internal passage formed in the 1 st spool and communicating the internal pressure chamber with the internal space; and
a 2 nd internal passage formed in the 2 nd spool to communicate the internal space with the working fluid tank.
7. A fluid pressure control device according to any of claims 4 to 6,
the switching valve further comprises a pair of 1 st falling members, wherein the 1 st falling members are used for falling the two ends of the 1 st force application member and moving relative to each other along with the expansion and contraction of the 1 st force application member,
the bypass cut-off valve further comprises a pair of 2 nd falling members, wherein the pair of 2 nd falling members are used for falling two ends of the 2 nd forcing member and moving relative to each other along with the expansion and contraction of the 2 nd forcing member,
the pair of 1 st seating members are brought into contact with each other to restrict the 1 st spool from moving against the biasing force of the 1 st biasing member,
the pair of 2 nd seating members are brought into contact with each other to restrict the movement of the 2 nd spool against the biasing force of the 2 nd biasing member.
8. The fluid pressure control device of claim 7,
the 1 st spool has:
a 1 st body portion which is in sliding contact with an inner peripheral surface of the housing hole; and
a 1 st support part attached to an end of the 1 st main body part, the 1 st biasing member being provided on an outer periphery of the 1 st support part,
the 2 nd spool has:
a 2 nd body portion which is in sliding contact with an inner peripheral surface of the housing hole; and
a 2 nd support part attached to an end of the 2 nd main body part, the 2 nd biasing member being provided on an outer periphery of the 2 nd support part,
the 1 st body part has a 1 st projecting part projecting in the axial direction toward the 1 st supporting part and abutting against the 1 st supporting part,
the 2 nd main body portion has a 2 nd projecting portion projecting in the axial direction toward the 2 nd support portion, and the 2 nd support portion is abutted against the 2 nd projecting portion.
9. A fluid pressure control device according to any of claims 3 to 6,
the receiving hole is formed as a through hole having a uniform inner diameter.
CN201980006723.3A 2018-11-01 2019-10-23 fluid pressure control device Active CN111527313B (en)

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JP2018206882A JP6703585B2 (en) 2018-11-01 2018-11-01 Fluid pressure controller
PCT/JP2019/041543 WO2020090586A1 (en) 2018-11-01 2019-10-23 Fluid pressure control device

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JP2023101191A (en) * 2022-01-07 2023-07-20 川崎重工業株式会社 Fluid control device
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JP6703585B2 (en) 2020-06-03
EP3730804A4 (en) 2021-08-25
EP3730804A1 (en) 2020-10-28

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