EP3943755A1 - Fluid pressure control device - Google Patents
Fluid pressure control device Download PDFInfo
- Publication number
- EP3943755A1 EP3943755A1 EP20779689.7A EP20779689A EP3943755A1 EP 3943755 A1 EP3943755 A1 EP 3943755A1 EP 20779689 A EP20779689 A EP 20779689A EP 3943755 A1 EP3943755 A1 EP 3943755A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- passage
- spool
- fluid pressure
- tank
- port
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
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- 239000012530 fluid Substances 0.000 title claims abstract description 164
- 230000007935 neutral effect Effects 0.000 claims description 59
- 230000004048 modification Effects 0.000 description 14
- 238000012986 modification Methods 0.000 description 14
- 238000011144 upstream manufacturing Methods 0.000 description 12
- 230000000052 comparative effect Effects 0.000 description 9
- 238000010586 diagram Methods 0.000 description 5
- 230000008602 contraction Effects 0.000 description 4
- 230000008859 change Effects 0.000 description 3
- 230000009471 action Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000007246 mechanism Effects 0.000 description 2
- 238000010276 construction Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000005192 partition Methods 0.000 description 1
- 230000004044 response Effects 0.000 description 1
Images
Classifications
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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
- E02F9/2239—Control of flow rate; Load sensing arrangements using two or more pumps with cross-assistance
-
- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02F—DREDGING; SOIL-SHIFTING
- E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
- E02F9/20—Drives; Control devices
- E02F9/22—Hydraulic or pneumatic drives
- E02F9/2264—Arrangements or adaptations of elements for hydraulic drives
- E02F9/2267—Valves or distributors
-
- 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
- E02F9/2282—Systems using center bypass type changeover 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
- E02F9/2278—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
- F15B20/00—Safety arrangements for fluid actuator systems; Applications of safety devices in fluid actuator systems; Emergency measures for fluid actuator systems
- F15B20/005—Leakage; Spillage; Hose burst
-
- 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
- F15B2013/0412—Valve members; Fluid interconnections therefor with three positions
-
- 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
- F15B2211/30565—Assemblies of multiple valves having multiple valves for a single output member, e.g. for creating higher valve function by use of multiple valves like two 2/2-valves replacing a 5/3-valve
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/30—Directional control
- F15B2211/31—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
- F15B2211/315—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
- F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
- F15B2211/705—Output members, e.g. hydraulic motors or cylinders or control therefor characterised by the type of output members or actuators
- F15B2211/7051—Linear output members
- F15B2211/7053—Double-acting output members
Definitions
- the present invention relates to a fluid pressure control device.
- JP2001-165106A discloses a flow combining mechanism provided with a pair of circuit systems.
- pumps are each separately connected to the respective circuit systems, and a pump discharged fluid from a second circuit system is joined to a first switch valve of a first circuit system via the second switch valve of the second circuit system.
- a pair of actuator ports are formed in a valve main body, and a spool is provided inside thereof so as to be freely slidable.
- the valve main body is formed with a U-shaped parallel feeder, and a discharge flow channel of a first pump is connected to the parallel feeder.
- the valve main body is formed with the U-shaped parallel feeder, and one end portion thereof is connected to an end portion of the parallel feeder of the first switch valve.
- a tandem passage, a neutral passage, and a supply passage are formed in the valve main body of the second switch valve, and the discharge flow channel of a second pump is connected to the tandem passage and the supply passage.
- the discharged fluid from the second pump is supplied to the parallel feeder of the second switch valve.
- the discharged fluid from the second pump is supplied to the parallel feeder of the first switch valve via an end portion of the parallel feeder of the second switch valve and is supplied to the actuator port by being combined with the discharged fluid from the first pump.
- the valve main body of the second switch valve is formed with a communication port that is always in communication with the actuator port formed in the valve main body of the first switch valve.
- the communication port communicates with the tank port that is formed in the valve main body of the second switch valve and that communicates with a tank.
- the actuator port communicates with the tank via the communication port of the second switch valve.
- the first actuator port communicates with the tank in accordance with the movement of the spool of the first switch valve and also communicates with the tank in accordance with the movement of the spool of the second switch valve.
- a small clearance is formed between an outer circumference of the spool and an inner circumference of a valve housing.
- An object of the present invention is to suppress a leakage of working fluid from a spool valve of a fluid pressure control device.
- a fluid pressure control device which is configured to be capable of combining working fluid discharged from a first pump and working fluid discharged from a second pump and of supplying the combined working fluid to a fluid pressure chamber of a fluid pressure actuator, includes: a first pump passage configured to guide the working fluid discharged from the first pump; a second pump passage configured to guide the working fluid discharged from the second pump; a first spool valve configured to control a flow of the working fluid to be supplied from the first pump to the fluid pressure actuator; a second spool valve configured to control the flow of the working fluid to be supplied from the second pump to the fluid pressure actuator; a connecting passage connecting the first spool valve and the second spool valve; a first fluid pressure passage configured to allow the first spool valve communicate with the fluid pressure chamber of the fluid pressure actuator; a second fluid pressure passage configured to allow the second spool valve communicate with the fluid pressure chamber of the fluid pressure actuator; a first tank passage connected to the first spool valve and communicated with a tank
- the first spool valve has: a first supply position at which the first fluid pressure passage is communicated with the first pump passage; and a first discharge position at which the first fluid pressure passage is communicated with the first tank passage and the first fluid pressure passage is communicated with the connecting passage.
- the second spool valve has: a second supply position at which the second fluid pressure passage is communicated with the second pump passage; and a second discharge position at which the connecting passage is communicated with the second tank passage and the second fluid pressure passage is shut off from the second tank passage.
- a fluid pressure control device 100 according to an embodiment of the present invention will be described bellow with reference to the drawings.
- a description will be given of the fluid pressure control device 100 that is provided in a fluid pressure control system 101 used for a construction machinery, in particular a hydraulic excavator, to control flows of working fluid supplied/discharged to/from a fluid pressure actuator.
- the fluid pressure control system 101 controls movement of a hydraulic cylinder 1 serving as the fluid pressure actuator for driving objects to be driven (not shown) such as a boom, an arm, a bucket, or the like.
- a hydraulic cylinder 1 serving as the fluid pressure actuator for driving objects to be driven (not shown)
- objects to be driven such as a boom, an arm, a bucket, or the like.
- the fluid pressure control device 100 that controls the movement of the hydraulic cylinder 1 for driving the boom serving as the object to be driven will be explained as an example.
- the fluid pressure control system 101 is provided with a first pump 7 and a second pump 8 that are each driven by an engine (not shown) or a motor (not shown) and that discharge working oil serving as the working fluid, a tank 9 that stores the working oil, and the fluid pressure control device 100 that moves the hydraulic cylinder 1 by controlling the flow of the working oil that is supplied/discharged to/from the hydraulic cylinder 1.
- the hydraulic cylinder 1 is a double acting type cylinder having a piston 4 that partitions an interior of a cylinder tube 2 into a rod side chamber 5 and a bottom-side chamber 6 that are respectively fluid pressure chambers.
- a piston rod 3 is linked to the piston 4.
- the hydraulic cylinder 1 As the working oil is supplied to the bottom-side chamber 6 and the working oil is discharged from the rod side chamber 5, the hydraulic cylinder 1 is extended to lift the boom. Conversely, as the working oil is supplied to the rod side chamber 5 and the working oil is discharged from the bottom-side chamber 6, the hydraulic cylinder 1 is contracted to lower the boom.
- the fluid pressure control device 100 is provided with a first neutral passage 10 that connects the first pump 7 and the tank 9, a second neutral passage 11 that connects the second pump 8 and the tank 9, a switch valve 30 serving as a first spool valve that is provided on the first neutral passage 10 and that controls the flow of the working oil from the first pump 7 to the hydraulic cylinder 1, and a flow-combining control valve 60 serving as a second spool valve that is provided on the second neutral passage 11 and that controls the flow of the working oil supplied from the second pump 8 to the hydraulic cylinder 1.
- the fluid pressure control device 100 can combine the working oil discharged from the first pump 7 and the working oil discharged from the second pump 8 and supply the combined working oil to the hydraulic cylinder 1.
- the first neutral passage 10 is formed of a first pump passage 10a that is an upstream passage of the switch valve 30 and that guides the working oil discharged from the first pump 7 and a first downstream passage 10b that is a downstream passage of the switch valve 30.
- the second neutral passage 11 is an upstream passage of the flow-combining control valve 60, and is formed of a second pump passage 11a that guides the working oil discharged from the second pump 8 and a second downstream passage 11b that is a downstream passage of the flow-combining control valve 60.
- the first downstream passage 10b and the second downstream passage 11b are joined with each other and communicate with the tank 9.
- the fluid pressure control device 100 is provided with a rod side passage 12 that communicates with the rod side chamber 5 of the hydraulic cylinder 1, a bottom side passage 13 that communicates with the bottom-side chamber 6 of the hydraulic cylinder 1, a first connecting passage 14 and a second connecting passage 15 that respectively connect the switch valve 30 and the flow-combining control valve 60, a first tank passage 16 that is connected to the switch valve 30 and communicates with the tank 9, and a second tank passage 17 that is connected to the flow-combining control valve 60 and communicates with the tank 9.
- the rod side passage 12 has a first rod side passage 12a through which the switch valve 30 is communicated with the rod side chamber 5 and a second rod side passage 12b through which the flow-combining control valve 60 is communicated with the rod side chamber 5.
- the first rod side passage 12a and the second rod side passage 12b are joined with each other and communicate with the rod side chamber 5.
- the bottom side passage 13 has a first bottom side passage 13a through which the switch valve 30 is communicated with the bottom-side chamber 6 and a second bottom side passage 13b through which the flow-combining control valve 60 is communicated with the bottom-side chamber 6.
- the first bottom side passage 13a and the second bottom side passage 13b are joined with each other and communicate with the bottom side chamber 6.
- the switch valve 30 is a spool valve having eight ports and three positions.
- a pilot pressure is guided to a pair of first pilot pressure chambers 50a and 50b, and a position is switched.
- a first spool 40 (see FIG. 2 ), which will be described below, is moved to the position in accordance with the level of the pilot pressure externally supplied to the pair of first pilot pressure chambers 50a and 50b, and the position is switched between a first neutral position 30A, a first extending position 30B, and a first contracting position 30C.
- the switch valve 30 In a state in which the pilot pressure is not supplied to the pair of first pilot pressure chambers 50a and 50b, the switch valve 30 is maintained at the first neutral position 30A by a biasing force exerted by centering springs 58a and 58b.
- the first neutral passage 10 At the first neutral position 30A, the first neutral passage 10 is opened, and the working oil discharged from the first pump 7 is guided to the tank 9 through the first neutral passage 10.
- the respective communications of the rod side chamber 5 and the bottom-side chamber 6 with the first pump passage 10a, the first tank passage 16, the first connecting passage 14, and the second connecting passage 15 are shut off. With such a configuration, the supply/discharge of the working oil to/from the hydraulic cylinder 1 is shut off, and the hydraulic cylinder 1 is in a load-holding state.
- the switch valve 30 is switched to the first extending position 30B in accordance with the level of the pilot pressure.
- the first pump passage 10a of the first neutral passage 10 is shut off from the first downstream passage 10b and is communicated with the first bottom side passage 13a.
- the first rod side passage 12a is communicated with the first tank passage 16 via a first rod side restrictor 30d imparting resistance to the flow of the working oil flowing therethrough and is communicated with the first connecting passage 14.
- the working oil that has been discharged from the first pump 7 is supplied to the bottom-side chamber 6 and the working oil in the rod side chamber 5 is discharged to the tank 9, and thereby, the hydraulic cylinder 1 is extended.
- the flowing amount of the working oil discharged from the rod side chamber 5 through the first tank passage 16 is controlled by the first rod side restrictor 30d, and thereby, the speed of the extension of the hydraulic cylinder 1 is controlled.
- the switch valve 30 is switched to the first contracting position 30C in accordance with the level of the pilot pressure.
- the first pump passage 10a is shut off from the first downstream passage 10b and is communicated with the first rod side passage 12a.
- the first bottom side passage 13a is communicated with the first tank passage 16 via a first bottom side restrictor 30e imparting resistance to the flow of the working oil flowing therethrough and is communicated with the second connecting passage 15.
- the working oil that has been discharged from the first pump 7 is supplied to the rod side chamber 5, and the working oil in the bottom-side chamber 6 is discharged to the tank 9, and thereby, the hydraulic cylinder 1 is contracted.
- the flowing amount of the working oil discharged from the bottom-side chamber 6 through the first tank passage 16 is controlled by the first bottom side restrictor 30e, and thereby, the speed of the extension of the hydraulic cylinder 1 is controlled.
- the flow-combining control valve 60 is the spool valve having eight ports and three positions.
- the pilot pressure is guided to a pair of second pilot pressure chambers 80a and 80b in accordance with the operation direction of the operation lever, and the position is switched.
- a second spool 70 (see FIG. 2 ), which will be described below, is moved to the position in accordance with the level of the pilot pressure externally supplied to the pair of second pilot pressure chambers 80a and 80b, and the position is switched between a second neutral position 60A, a second extending position 60B, and a second contracting position 60C.
- the flow-combining control valve 60 is maintained at the second neutral position 60A by the biasing force exerted by centering springs 88a and 88b.
- the second neutral passage 11 is opened, and the working oil discharged from the second pump 8 is guided to the tank 9 through the second neutral passage 11.
- the respective communications of the second tank passage 17 with the second rod side passage 12b, the second bottom side passage 13b, the first connecting passage 14, and the second connecting passage 15 are shut off.
- the flow-combining control valve 60 is switched to the second extending position 60B in accordance with the level of the pilot pressure.
- the second pump passage 11a of the second neutral passage 11 is shut off from the second downstream passage 11b and is communicated with the second bottom side passage 13b.
- the first connecting passage 14 is communicated with the second tank passage 17 via a second rod side restrictor 60d.
- a part of the working oil discharged from the rod side chamber 5 is discharged to the tank 9 through the switch valve 30, the first connecting passage 14, the flow-combining control valve 60, and the second tank passage 17.
- the flowing amount of the working oil discharged from the rod side chamber 5 through the second tank passage 17 is controlled by the second rod side restrictor 60d, and thereby, the speed of the extension of the hydraulic cylinder 1 is controlled.
- the communication of the second rod side passage 12b with the second tank passage 17 is shut off.
- the flow-combining control valve 60 is switched to the second contracting position 60C in accordance with the level of the pilot pressure.
- the second pump passage 11a is shut off from the second downstream passage 11b and is communicated with the second rod side passage 12b.
- the second connecting passage 15 is communicated with the second tank passage 17 via a second bottom side restrictor 60e.
- a part of the working oil that has been discharged from the bottom-side chamber 6 is discharged to the tank 9 through the switch valve 30, the second connecting passage 15, the flow-combining control valve 60, and the second tank passage 17.
- the flowing amount of the working oil discharged from the bottom-side chamber 6 through the second tank passage 17 is controlled by the second bottom side restrictor 60e, and thereby, the speed of the extension of the hydraulic cylinder 1 is controlled.
- the communication between the second bottom side passage 13b and the second tank passage 17 is shut off.
- the fluid pressure control device 100 is configured such that, in both cases of the extension and contraction of the hydraulic cylinder 1, it is possible to combine the working oil discharged from the second pump 8 with the working oil that has been discharged from the first pump 7 and to supply the combined working oil to the hydraulic cylinder 1.
- the flow-combining control valve 60 shuts off the second tank passage 17 from the second rod side passage 12b and the second bottom side passage 13b at the second neutral position 60A.
- the flow-combining control valve 60 at the second extending position 60B, the communication between the second rod side passage 12b and the second tank passage 17 is shut off, and at the second contracting position 60C, the communication between the second bottom side passage 13b and the second tank passage 17 is shut off.
- the second bottom side passage 13b and the second rod side passage 12b serving as a second fluid pressure passage guide the working oil that has been discharged from the second pump 8 to the hydraulic cylinder 1, but do not guide the working oil that has been discharged from the hydraulic cylinder 1 to the tank 9.
- the working oil that has been discharged from the hydraulic cylinder 1 is discharged to the tank 9 from the first connecting passage 14 or the second connecting passage 15 through the second tank passage 17.
- the first connecting passage 14 corresponds to "a connecting passage”
- the first bottom side passage 13a corresponds to "a first fluid pressure passage”
- the second bottom side passage 13b corresponds to "the second fluid pressure passage” in the claims.
- the first extending position 30B, the first contracting position 30C, and the first rod side restrictor 30d of the switch valve 30 correspond to "a first supply position", “a first discharge position”, and “a first discharge restrictor” in the claims, respectively
- the second extending position 60B and the second contracting position 60C of the flow-combining control valve 60 correspond to "a second supply position” and "a second discharge position” in the claims, respectively.
- the second connecting passage 15, the first rod side passage 12a, and the second rod side passage 12b correspond to "the connecting passage", "the first fluid pressure passage”, and "the second fluid pressure passage” in the claims, respectively.
- the first contracting position 30C, the first extending position 30B, and the first bottom side restrictor 30e of the switch valve 30 correspond to "the first supply position", “the first discharge position”, and “the first discharge restrictor” in the claims, respectively
- the second contracting position 60C and the second extending position 60B of the flow-combining control valve 60 correspond to "the second supply position” and "the second discharge position” in the claims, respectively.
- the switch valve 30 has a first housing 100a in which a first spool hole 31 is formed, the first spool 40 that is received in the first spool hole 31 so as to be freely movable, the pair of first pilot pressure chambers 50a and 50b that respectively face both ends of the first spool 40, and a centering spring 58 that imparts the biasing force to the first spool 40.
- the first spool hole 31 is a through hole whose both ends respectively open at end surfaces of the first housing 100a.
- a first downstream side port 32 that communicates with the first downstream passage 10b of the first neutral passage 10
- a pair of first upstream side ports 33a and 33b that communicate with the first pump passage 10a of the first neutral passage 10 on the upstream side
- a first rod side port 35a that communicates with the first rod side passage 12a
- a first bottom side port 35b that communicates with the first bottom side passage 13a
- a pair of connecting ports 36a and 36b that respectively communicate with the first connecting passage 14 and the second connecting passage 15, and a pair of first tank ports 37a and 37b that communicate with the first tank passage 16
- first tank ports 37a and 37b that communicate with the first tank passage 16
- a first bridge passage 10c whose both ends open to the first spool hole 31 is formed in the first housing 100a. Both ends of the first bridge passage 10c open to the first spool hole 31 via a pair of first bridge ports 34a and 34b that are respectively formed to have annular shapes in the inner circumference of the first spool hole 31.
- a pair of first caps 51a and 51b for closing openings of the first spool hole 31 are respectively attached to both ends of the first housing 100a.
- the pair of first pilot pressure chambers 50a and 50b of the switch valve 30 are respectively formed in the pair of first caps 51a and 51b.
- a recessed portion 52a into which the first spool 40 can enter and a pilot port 54a that communicates with the recessed portion 52a are formed. Because the recessed portion 52a is provided, the one first pilot pressure chamber 50a is formed, and so, the pilot pressure is guided to the recessed portion 52a through the pilot port 54a.
- a first support member 55 is attached to an end portion of the first spool 40 so as to be coaxial with the first spool 40.
- the first support member 55 has a first shaft portion 56 that is fixed to the end portion of the first spool 40 and a first head portion 57 that has a larger outer diameter than the first shaft portion 56. As shown in FIG. 2 , the first head portion 57 of the first support member 55 is inserted into the first small diameter hole 53b at the first neutral position 30A.
- the centering spring 58 is provided in the other first cap 51b. Specifically, the centering spring 58 is provided around an outer circumference of the first shaft portion 56 of the first support member 55 between the end surface of the first spool 40 and the first head portion 57.
- both ends of the centering spring 58 are respectively seated, via spring washers 59a and 59b, on an end surface of the first housing 100a and on a step surface 52c formed between the first large diameter hole 52b and the first small diameter hole 53b of the first cap 51b.
- the single centering spring 58 shown in FIG. 2 functions as the pair of centering springs 58a and 58b in the hydraulic circuit diagram shown in FIG. 1 .
- the switch valve 30 is held at the first neutral position 30A.
- the first spool 40 has a first land part 41, a pair of second land parts 42a and 42b, a pair of third land parts 43a and 43b, a pair of fourth land parts 44a and 44b, and a pair of fifth land parts 45a and 45b, which are each in sliding contact with the inner circumference of the first spool hole 31.
- the one fifth land part 45a, the one fourth land part 44a, the one third land part 43a, the one second land part 42a, the first land part 41, the other second land part 42b, the other third land part 43b, the other fourth land part 44b, and the other fifth land part 45b are provided in this order in the shaft direction from one end towards the other end of the first spool 40 (from the left side to the right side in FIG. 2 ).
- a pair of first pump grooves 46a and 46b are formed as annular grooves between the first land part 41 and the pair of second land parts 42a and 42b.
- First bridge grooves 47a and 47b are respectively formed between the pair of mutually adjacent second land parts 42a and 42b and the pair of third land parts 43a and 43b.
- First connecting grooves 48a and 48b are respectively formed between the pair of mutually adjacent third land parts 43a and 43b and the pair of fourth land parts 44a and 44b.
- First tank grooves 49a and 49b are respectively formed between the pair of mutually adjacent fourth land parts 44a and 44b and the pair of fifth land parts 45a and 45b.
- notches 40a and 40b respectively serving as the first rod side restrictor 30d and the first bottom side restrictor 30e (see FIG. 1 ) are formed so as to respectively extend in the shaft direction of the first spool 40 and so as to respectively communicate with the first tank grooves 49a and 49b.
- the notches 40a and 40b respectively impart the resistance to the flows of the working oil discharged to the tank 9 from the rod side chamber 5 and the bottom-side chamber 6 through the first tank passage 16.
- notches 40a and 40b are respectively formed along the circumferential direction of the first spool 40, the configuration is not limited thereto, and only a single notch may be formed.
- whole of the plurality of the notch 40a form the first rod side restrictor 30d shown in FIG. 1 .
- whole of the plurality of notches 40b form the first bottom side restrictor 30e.
- the flow-combining control valve 60 has a second housing 100b in which a second spool hole 61 is formed, the second spool 70 that is received in the second spool hole 61 so as to be freely movable, the second pilot pressure chambers 80a and 80b that respectively face both ends of the second spool 70, and a centering spring 88 that imparts the biasing force to the second spool 70.
- the second housing 100b is formed integrally with the first housing 100a of the switch valve 30.
- the switch valve 30 and the flow-combining control valve 60 are accommodated in a common housing functioning as both of the first housing 100a and the second housing 100b.
- the configuration is not limited thereto, and the first housing 100a and the second housing 100b may be formed separately from each other.
- the second spool hole 61 is a through hole whose both ends respectively open at end surfaces of the second housing 100b.
- the second spool hole 61 is formed such that its center axis extends in parallel with the center axis of the first spool hole 31.
- a second downstream side port 62 that communicates with the second downstream passage 11b of the second neutral passage 11, a pair of second upstream side ports 63a and 63b that communicate with the second pump passage 11a of the second neutral passage 11 on the upstream passage, a second rod side port 65a that communicates with the second rod side passage 12b, a second bottom side port 65b that communicates with the second bottom side passage 13b, a pair of combining ports 66a and 66b that respectively communicate with the first connecting passage 14 and the second connecting passage 15, and a pair of second tank ports 67a and 67b that communicate with the second tank passage 17 are respectively formed to have annular shapes in an inner circumference of the second spool hole 61 so as to open to the second spool hole 61.
- a second bridge passage 11c whose both ends open to the second spool hole 61 is formed in the second housing 100b. Both ends of the second bridge passage 11c open to the second spool hole 61 via a pair of second bridge ports 64a and 64b that are respectively formed to have annular shapes in the inner circumference of the second spool hole 61.
- a pair of second caps 81a and 81b for closing openings of the second spool hole 61 are respectively attached to both ends of the second housing 100b.
- the pair of second pilot pressure chambers 80a and 80b of the flow-combining control valve 60 are respectively formed in the pair of second caps 81a and 81b.
- the centering spring 88 is provided in the one second cap 81a.
- a second support member 85 is attached to end portion of the second spool 70 so as to be coaxial with the second spool 70.
- the pair of second caps 81a and 81b and the second support member 85 have the similar configurations with those of the pair of first caps 51a and 51b and the first support member 55 in the switch valve 30, a detailed description is omitted.
- a recessed portion 82a and a pilot port 84a are formed in a corresponding manner to the recessed portion 52a and the pilot port 54a in the one first cap 51a.
- a second large diameter hole 82b, a second small diameter hole 83b, a step surface 82c, and a pilot port 84b are formed in a corresponding manner to the first large diameter hole 52b, the first small diameter hole 53b, the step surface 52c, and the pilot port 54b in the other first cap 51b.
- the second support member 85 has a second shaft portion 86 and a second head portion 87 in a corresponding manner to the first shaft portion 56 and the first head portion 57 in the first support member 55.
- centering spring 88 and a pair of spring washers 89a and 89b of the flow-combining control valve 60 also have similar configurations with those of the centering spring 58 and the pair of spring washers 59a and 59b of the switch valve 30, a detailed description is omitted.
- the single centering spring 88 of the flow-combining control valve 60 shown in FIG. 2 exhibits functions of the centering springs 88a and 88b in the hydraulic circuit diagram shown in FIG. 1 .
- the second spool 70 has a first control land part 71, a pair of second control land parts 72a and 72b, a pair of third control land parts 73a and 73b, a pair of fourth control land parts 74a and 74b, and a pair of fifth control land parts 75a and 75b, which are each in sliding contact with the second spool hole 61.
- the one fifth control land part 75a, the one fourth control land part 74a, the one third control land part 73a, the one second control land part 72a, the first control land part 71, the other second control land part 72b, the other third control land part 73b, the other fourth control land part 74b, and the other fifth control land part 75b are provided in this order in the shaft direction from one end towards the other end of the second spool 70 (from the left side to the right side in FIG. 2 ).
- a pair of second pump grooves 76a and 76b are formed as annular grooves between the first control land part 71 and the pair of second control land parts 72a and 72b.
- Second bridge grooves 77a and 77b are respectively formed between the pair of mutually adjacent second control land parts 72a and 72b and the pair of third control land parts 73a and 73b.
- Combining connecting grooves 78a and 78b are respectively formed between the pair of mutually adjacent third control land parts 73a and 73b and the pair of fourth control land parts 74a and 74b.
- second tank grooves 79a and 79b are respectively formed between the pair of mutually adjacent fourth control land parts 74a and 74b and the pair of fifth control land parts 75a and 75b.
- notches 70a and 70b respectively serving as the second rod side restrictor 60d and the second bottom side restrictor 60e are formed so as to respectively extend in the shaft direction of the second spool 70 and so as to respectively communicate with the second tank grooves 79a and 79b.
- the notches 70a and 70b respectively impart the resistance to the flows of the working oil discharged to the tank 9 from the rod side chamber 5 and the bottom-side chamber 6 through the second tank passage 17.
- notches 70a and 70b are respectively formed along the circumferential direction of the second spool 70, the configuration is not limited thereto, and only a single notch may be formed.
- whole of the plurality of the notches 70a form the second rod side restrictor 60d shown in FIG. 1 .
- whole of the plurality of notches 70b form the second bottom side restrictor 60e.
- the land parts 42a, 43a, 44a, 45a and the grooves 46a, 47a, 48a, 49a in the first spool 40 which are provided on the one side in the shaft direction
- the land parts 42b, 43b, 44b, 45b and the grooves 46b, 47b, 48b, 49b in the first spool 40 which are provided on the other side in the shaft direction, are configured such that their respective functions are exchanged with each other between corresponding configurations (configurations forming the pair) in accordance with the moving direction of the hydraulic cylinder 1.
- the ports 33a, 34a, 35a, 36a, 37a, which are provided on the one side in the shaft direction, and the ports 33b, 34b, 35b, 36b, 37b, which are provided on the other side in the shaft direction, are configured such that their respective functions are exchanged with each other between corresponding configurations in accordance with the extension and the contraction of the hydraulic cylinder 1.
- control land parts 72a, 73a, 74a, 75a and the grooves 76a, 77a, 78a, 79a in the second spool 70 which are provided on the one side in the shaft direction
- control land parts 72b, 73b, 74b, 75b and the grooves 76b, 77b, 78b, 79b in the second spool 70 which are provided on the other side in the shaft direction
- the ports 63a, 64a, 65a, 66a, 67a, which are provided on the one side in the shaft direction, and the ports 63b, 64b, 65b, 66b, 67b, which are provided on the other side in the shaft direction, are configured such that their respective functions are exchanged with each other between corresponding configurations in accordance with the extension and the contraction of the hydraulic cylinder 1.
- the hydraulic cylinder 1 is to be extended will be explained as an example, and for a case in which the hydraulic cylinder 1 is to be contracted, an explanation will be omitted appropriately.
- the pilot pressure is not guided to neither of the pair of first pilot pressure chambers 50a and 50b of the switch valve 30.
- the pair of first upstream side ports 33a and 33b and the first downstream side port 32 of the switch valve 30 are communicated via the pair of first pump grooves 46a and 46b.
- the pilot pressure is guided to the one first pilot pressure chamber 50a of the switch valve 30 in accordance with the operational input.
- the first spool 40 is moved in accordance with the level of the pilot pressure, and the switch valve 30 is shifted to the first extending position 30B in accordance with the moved amount of the first spool 40 (see FIG. 1 ).
- the first spool 40 is moved to the right direction in the figure against the biasing force exerted by the centering spring 58.
- the communications of the pair of first upstream side ports 33a and 33b with the first downstream side port 32 are shut off by the first land part 41 and the second land part 42a of the first spool 40.
- the one first upstream side port 33a is communicated with the first bridge port 34a via the first bridge groove 47a
- the first bridge port 34b is communicated with the first bottom side port 35b via the first bridge groove 47b.
- the first rod side port 35a is communicated with the connecting port 36a via the first connecting groove 48a
- the connecting port 36a is communicated with the first tank port 37a via the notch 40a and the first tank groove 49a.
- the working oil that has been discharged from the first pump 7 is guided to the first bridge passage 10c from the first pump passage 10a through the first bridge groove 47a of the first spool 40, and then, the working oil is guided to the bottom-side chamber 6 from the first bridge passage 10c through the first bridge groove 47b and the first bottom side passage 13a.
- the working oil in the rod side chamber 5 is discharged to the tank 9 by being guided to the first tank passage 16 from the first rod side passage 12a through the notch 40a. By doing so, the hydraulic cylinder 1 is extended.
- the part of the working oil in the rod side chamber 5 is guided to the combining port 66a of the flow-combining control valve 60 from the first rod side port 35a through the connecting port 36a and the first connecting passage 14.
- the notch 40a is formed to have the length along the shaft direction of the first spool 40 such that, along with the movement of the first spool 40 to the right direction in FIG. 2 , the communication between the first rod side port 35a and the connecting port 36a is established before the communication between the first tank port 37a and the connecting port 36a is established.
- the pilot pressure is not supplied to the second pilot pressure chambers 80a and 80b of the flow-combining control valve 60, and the flow-combining control valve 60 is held at the second neutral position 60A by the biasing force exerted by the centering spring 88 (see FIG. 1 ).
- the pair of second upstream side ports 63a and 63b and the second downstream side port 62 of the flow-combining control valve 60 are communicated via the pair of second pump grooves 76a and 76b.
- the pilot pressure is also guided to the one second pilot pressure chamber 80a of the flow-combining control valve 60.
- the second spool 70 is moved in accordance with the level of the pilot pressure, and the flow-combining control valve 60 is shifted to the second extending position 60B in accordance with the moved amount of the second spool 70 (see FIG. 1 ).
- the second spool 70 is moved to the right direction in the figure against the biasing force exerted by the centering spring 88.
- the communications of the pair of second upstream side ports 63a and 63b with the second downstream side port 62 are shut off by the first control land part 71 and the second control land part 72a.
- the one second upstream side port 63a is communicated with the second bridge port 64a via the second bridge groove 77a
- the second bridge port 64b is communicated with the second bottom side port 65b via the second bridge groove 77b.
- the working oil discharged from the second pump 8 is guided to the second bridge passage 11c from the second pump passage 11a through the second bridge groove 77a of the second spool 70 and is guided to the second bottom side passage 13b from the second bridge passage 11c through the second bridge groove 77b.
- the working oil discharged from the second pump 8 is guided to the bottom-side chamber 6 by being combined with the working oil that has been discharged from the first pump 7.
- the combining port 66a is communicated with the second tank port 67a via the notch 70a and a second tank groove 79a.
- the part of the working oil in the rod side chamber 5 is guided to the flow-combining control valve 60 from the switch valve 30 through the first connecting passage 14 and is discharged to the tank 9 through the second tank passage 17.
- the working oil that has been discharged from the hydraulic cylinder 1 is discharged to the tank 9 through the switch valve 30, and at the same time, discharged to the tank 9 also through the flow-combining control valve 60.
- the working oil that has been discharged from the hydraulic cylinder 1 is discharged to the tank 9 through the notch 40a (the first bottom side restrictor 30e) of the switch valve 30, and at the same time, discharged to the tank 9 through the notch 70a (the second bottom side restrictor 60e) of the flow-combining control valve 60. Therefore, the hydraulic cylinder 1 is extended at the speed corresponding to the resistance imparted to the working oil that has been discharged from the rod side chamber 5 by the notch 40a of the switch valve 30 and the notch 70a of the flow-combining control valve 60.
- a fluid pressure control device 300 according to a comparative example of the present invention will be described with reference to FIGs. 5 and 6 .
- Configurations that are similar to those in the present embodiment are assigned the same reference signs, and descriptions thereof shall be omitted appropriately.
- a switch valve 230 according to the comparative example differs from the configuration in the above-mentioned embodiment in that, at a first extending position 230B, the first rod side passage 12a is not communicated with the first connecting passage 14, and at a first contracting position 230C, the first bottom side passage 13a is not communicated with the second connecting passage 15.
- a flow-combining control valve 260 in a flow-combining control valve 260 according to the comparative example, at a second extending position 260B, the second rod side passage 12b is communicated with the second tank passage 17. The part of the working oil in the rod side chamber 5 is discharged to the tank 9 from the second rod side passage 12b through the flow-combining control valve 260 and the second tank passage 17.
- the second bottom side passage 13b in the flow-combining control valve 260, at a second contracting position 260C, the second bottom side passage 13b is communicated with the second tank passage 17. The part of the working oil in the bottom-side chamber 6 is discharged to the tank 9 from the second bottom side passage 13b through the flow-combining control valve 260 and the second tank passage 17.
- the switch valve 230 at a first neutral position 230A, the first neutral passage 10 is opened, and the respective communications of the first rod side passage 12a and the first bottom side passage 13a with the first pump passage 10a and the first tank passage 16 are shut off.
- the second neutral passage 11 is opened, and the respective communications of the second rod side passage 12b and the second bottom side passage 13b with the second pump passage 11a and the second tank passage 17 are shut off.
- the hydraulic cylinder 1 is to be extended will be described, as an example, with reference to an enlarged sectional view shown in FIG. 6 .
- the first rod side port 35a and the first tank port 37a of the switch valve 230 are adjacent with each other in the shaft direction, and other ports like the connecting port 36a in the above-mentioned embodiment are not provided between these ports.
- the notch 40a that communicates with the first tank groove 49a is formed in a third land part 243a of a first spool 240 that closes the first rod side port 35a in a state in which the switch valve 230 has been switched to the first neutral position 230A.
- the second rod side port 65a and the second tank port 67a of the flow-combining control valve 260 are adjacent with each other in the shaft direction.
- the notch 70a that communicates with the second tank groove 79a is formed in a third control land part 273a of a second spool 270 that closes the second rod side port 65a in a state in which the flow-combining control valve 260 has been switched to the second neutral position 260A.
- the working oil discharged from the second pump 8 is supplied to the bottom-side chamber 6 or the rod side chamber 5 through the second bottom side passage 13b or the second rod side passage 12b.
- the part of the working oil in the bottom-side chamber 6 or the rod side chamber 5 is discharged to the tank 9 from the second bottom side passage 13b or the second rod side passage 12b through the flow-combining control valve 260.
- the load (the self weight) of the objects to be driven may act only on either of the rod side chamber or the bottom-side chamber.
- the working oil in the rod side chamber or the bottom-side chamber, on which the load pressure acts tends to leak through the clearance formed around the outer circumference of the spool due to the influence of the load pressure.
- the self weight (the load) of the boom acts on the bottom-side chamber.
- the switch valve 230 when the switch valve 230 is switched to the first neutral position 230A to maintain the hydraulic cylinder 1 at the stopped state (the load-holding state), the load pressure acting on the bottom-side chamber 6 respectively acts on the switch valve 230 and the flow-combining control valve 260. Therefore, in the fluid pressure control device 300 according to the comparative example, there is a risk in that the working oil in the bottom-side chamber 6 leaks out through the clearance formed between the spool (the first spool 240, the second spool 270) and the spool hole (the first spool hole 31, the second spool hole 61) in each of the switch valve 230 and the flow-combining control valve 260. If the working oil in the bottom-side chamber 6, on which the load pressure acts, leaks out through the clearance, the hydraulic cylinder 1 is contracted in accordance with the leaked amount, and the load can no longer be held.
- the third control land part 273a closes the second rod side port 65a, and the notch 70a is formed in the third control land part 273a. Therefore, an amount of the third control land part 273a overlapped with the second spool hole 61 on the inner side of the wall portion W is smaller by an amount corresponding to the length of the notch 70a opposing to an wall portion W between the second rod side port 65a and the second tank port 67a.
- the working oil in the rod side chamber 5 tends to leak out even further to the tank 9 through the clearance formed around the outer circumference of the second spool 270.
- the second rod side passage 12b and the second bottom side passage 13b are not communicated with the tank 9 through the flow-combining control valve 60 (the second spool 70), the leakage of the working oil in the rod side chamber 5 and the bottom-side chamber 6 to the tank 9 from the clearance around the outer circumference of the second spool 70 of the flow-combining control valve 60 is suppressed.
- the second rod side port 65a is closed by the third control land part 73a of the second spool 70.
- the second rod side port 65a is completely closed by the third control land part 73a of the second spool 70.
- the state in which the second spool 70 has completed the stroke in the direction in which the flow-combining control valve 60 is switched to the second extending position 60B is the state in which a second head portion 87 of the second support member 85 provided on the end portion of the second spool 70 is in contact with the second cap 81b (the state shown in FIG. 3 ).
- the second rod side port 65a is completely closed by the third control land part 73a from the state in which the flow-combining control valve 60 is in the second neutral position 60A to the state in which the second spool 70 has completed the stroke such that the flow-combining control valve 60 is switched to the second extending position 60B.
- the flow-combining control valve 60 has a configuration in which the communication between the second rod side passage 12b and the second tank passage 17 is shut off at the second extending position 60B, there is no need to provide the notch on the second tank port 67a side of the third control land part 73a.
- the amount of the third control land part 73a overlapped with the second spool hole 61 in the shaft direction of the second spool 70 can be increased. Therefore, the leakage of the working oil from the second rod side port 65a to the second tank port 67a through the clearance between the third control land part 73a and the second spool hole 61 is suppressed.
- the combining ports 66a and 66b are respectively provided between the second rod side port 65a and the second tank port 67a and between the second bottom side port 65b and the second tank port 67b.
- the communication between the second rod side port 65a and the combining port 66a and the communication between the second bottom side port 65b and the combining port 66b are respectively shut off by the third control land parts 73a and 73b.
- the communication between the second rod side passage 12b and the second tank passage 17 is shut off at the second extending position 60B, and the communication between the second bottom side passage 13b and the second tank passage 17 is shut off at the second contracting position 60C.
- the flow-combining control valve 60 is configured such that the second rod side passage 12b and the second bottom side passage 13b are always in communication with the second tank passage 17. More specifically, even in a state in which the second spool 70 has completed the stroke in the direction in which the flow-combining control valve 60 is switched to the second extending position 60B, the second rod side port 65a, which is always in communication with the rod side chamber 5, is closed by the third control land part 73a.
- the second bottom side port 65b which is always in communication with the bottom-side chamber 6, is closed by the third control land part 73b.
- the second rod side passage 12b is shut off from the second tank passage 17 when the flow-combining control valve 60 is in the second extending position 60B, and the second bottom side passage 13b is shut off from the second tank passage 17 when the flow-combining control valve 60 is in the second contracting position 60C.
- each of the rod side chamber 5 and the bottom-side chamber 6 corresponds to "the fluid pressure chamber" in the claims, and the present invention is applied to both of the control of the working oil to be supplied/discharged to/from the rod side chamber 5 and the control of the working oil to be supplied/discharged to/from the bottom-side chamber 6.
- the present invention may only be applied to either one of the control of the working oil to be supplied/discharged to/from the rod side chamber 5 and the control of the working oil to be supplied/discharged to/from the bottom-side chamber 6.
- specific description will be given with reference to FIG. 4 .
- the modification shown in FIG. 4 is an example showing a configuration in which the present invention is only applied to the control of the flow of the working oil supplied/discharged to/from the bottom-side chamber 6.
- the fluid pressure control device 100 according to the modification shown in FIG. 4 is provided with, similarly to the above-mentioned embodiment, the first neutral passage 10, the second neutral passage 11, the first rod side passage 12a, the second rod side passage 12b, the first bottom side passage 13a (the first fluid pressure passage), the second bottom side passage 13b (the second fluid pressure passage), the second connecting passage 15 (the connecting passage), the first tank passage 16, and the second tank passage 17.
- the fluid pressure control device 100 according to the modification is not provided with the first connecting passage 14 in the above-mentioned embodiment.
- a switch valve 130 has: a first neutral position 130A at which the first neutral passage 10 is opened; a first extending position 130B at which the first bottom side passage 13a is communicated with the first pump passage 10a and the first rod side passage 12a is communicated with the first tank passage 16; and a first contracting position 130C at which the first rod side passage 12a is communicated with the first pump passage 10a, the first bottom side passage 13a is communicated with the first tank passage 16, and the first bottom side passage 13a is communicated with the second connecting passage 15.
- the first extending position 130B corresponds to "the first supply position”
- the first contracting position 130C corresponds to "the first discharge position" in the claims.
- a flow-combining control valve 160 has: a second neutral position 160A at which the second neutral passage 11 is opened; a second extending position 160B at which the second bottom side passage 13b is communicated with the second pump passage 11a, and the second rod side passage 12b is communicated with the second tank passage 17; and a second contracting position 160C at which the second rod side passage 12b is communicated with the second pump passage 11a, and the second connecting passage 15 is communicated with the second tank passage 17.
- the respective communications of the second rod side passage 12b, the second bottom side passage 13b, and the second connecting passage 15 with the second pump passage 11a and the second tank passage 17 are shut off.
- the second contracting position 160C the communication between the second bottom side passage 13b and the second tank passage 17 is shut off.
- the second extending position 160B corresponds to "the second supply position”
- the second contracting position 160C corresponds to "the second discharge position” in the claims.
- the second bottom side passage 13b that is always in communication with the bottom-side chamber 6 of the hydraulic cylinder 1 is shut off from the tank 9 at both of the second neutral position 160A and the second contracting position 160C.
- the part of the working oil in the bottom-side chamber 6 is not discharged to the tank 9 through the second bottom side passage 13b, but is discharged to the tank 9 through the switch valve 130, the second connecting passage 15, and the flow-combining control valve 160.
- the leakage of the working oil in the bottom-side chamber 6 to the tank 9 through the clearance around the outer circumference of the second spool 70 of the flow-combining control valve 160 is suppressed.
- the present invention is applied to the control of the working oil to be supplied/discharged to/from the bottom-side chamber 6 serving as a load-side pressure chamber in the hydraulic cylinder 1 for driving the boom.
- the present invention may be applied to the control of the flow of the working oil to be supplied/discharged to/from an anti-load-side pressure chamber (the rod side chamber 5 in the hydraulic cylinder 1 for driving the boom).
- the fluid pressure control device 100 that controls the flow of the working oil to the hydraulic cylinder 1 for driving the boom as the object to be driven.
- the fluid pressure control device 100 may control the flow of the working oil to the hydraulic cylinder 1 for driving other objects to be driven such as the arm, the bucket, and so forth.
- the fluid pressure control device 100 may be provided with an anti-drift valve serving as a poppet valve that prevents the working oil from being discharged to the tank 9 from the load-side pressure chamber on which the load pressure acts by shutting off the tank passage (the first tank passage 16, the second tank passage 17) in the load-holding state.
- an anti-drift valve serving as a poppet valve that prevents the working oil from being discharged to the tank 9 from the load-side pressure chamber on which the load pressure acts by shutting off the tank passage (the first tank passage 16, the second tank passage 17) in the load-holding state.
- the fluid pressure control device 100 configured to be capable of combining the working oil that has been discharged from the first pump 7 and the working oil that has been discharged from the second pump 8 and of supplying the combined working oil to the fluid pressure chamber (the rod side chamber 5, the bottom-side chamber 6) of the hydraulic cylinder 1 includes: the first pump passage 10a configured to guide the working oil discharged from the first pump 7; the second pump passage 11a configured to guide the working oil discharged from the second pump 8; the switch valve 30, 130 configured to control the flow of the working oil from the first pump 7 to the hydraulic cylinder 1; the flow-combining control valve 60, 160 configured to control the flow of the working oil supplied from the second pump 8 to the hydraulic cylinder 1; the connecting passage (the first connecting passage 14, the second connecting passage 15) configured to connect the switch valve 30, 130 and the flow-combining control valve 60, 160; the first fluid pressure passage (the first rod side passage 12a, the first bottom side passage 13a) configured such that the switch valve 30, 130 and the fluid pressure chamber (the rod side chamber 5, the bottom-side chamber 6) of
- the switch valve 30, 130 is switched to the first discharge position (the first contracting position 30C, 130C, the first extending position 30B), the working oil in the fluid pressure chamber (the rod side chamber 5, the bottom-side chamber 6) of the hydraulic cylinder 1 is discharged to the tank 9 through the first tank passage 16.
- the flow-combining control valve 60, 160 is switched to the second discharge position (the second contracting position 60C, 160C, the second extending position 60B) in a state in which the switch valve 30, 130 has been switched to the first discharge position (the first contracting position 30C, 130C, the first extending position 30B), the working oil in the fluid pressure chamber (the rod side chamber 5, the bottom-side chamber 6) is discharged to the tank 9 through the second tank passage 17 by being guided to the flow-combining control valve 60, 160 through the switch valve 30, 130 and the connecting passage (the first connecting passage 14, the second connecting passage 15).
- the second fluid pressure passage (the second rod side passage 12b, the second bottom side passage 13b) is not communicated with the tank 9 and is shut off.
- the working oil in the fluid pressure chamber (the rod side chamber 5, the bottom-side chamber 6) is not discharged to the tank 9 through the second fluid pressure passage (the second rod side passage 12b, the second bottom side passage 13b).
- the second fluid pressure passage (the second rod side passage 12b, the second bottom side passage 13b) that is always in communication with the fluid pressure chamber (the rod side chamber 5, the bottom-side chamber 6) of the hydraulic cylinder 1 is not configured to communicate with the tank 9 by the flow-combining control valve 60, 160, the leakage of the working oil in the fluid pressure chamber (the rod side chamber 5, the bottom-side chamber 6) to the tank 9 from the second fluid pressure passage (the second rod side passage 12b, the second bottom side passage 13b) through the clearance around the outer circumference of the spool (the second spool 70) of the flow-combining control valve 60, 160 is suppressed.
- the switch valve 30, 130 has: the first housing 100a; the first spool 40 received in the first spool hole 31 so as to be freely movable, the first spool hole 31 being formed in the first housing 100a; the first fluid pressure port (the first rod side port 35a, the first bottom side port 35b) configured to communicate with the first fluid pressure passage (the first rod side passage 12a, the first bottom side passage 13a) and to open to the first spool hole 31; the first tank ports 37a and 37b configured to communicate with the first tank passage 16 and to open to the first spool hole 31; the connecting ports 36a and 36b configured to communicate with the connecting passage (the first connecting passage 14, the second connecting passage 15) and to open to the first spool hole 31; the first rod side restrictor 30d and the first bottom side restrictor 30e (the notches 40a and 40b) provided in the first spool 40, the first rod side restrictor 30d and the first bottom side restrictor 30e (the notches 40a and 40b) provided in the first spool 40,
- the communication between the first fluid pressure port (the first rod side port 35a, the first bottom side port 35b) and the connecting ports 36a and 36b is established first, and subsequently, the communication between the first tank ports 37a and 37b and the connecting ports 36a and 36b is established via the first rod side restrictor 30d and the first bottom side restrictor 30e (the notches 40a and 40b).
- the pressure change caused by the establishment of the communication between the fluid pressure chamber (the rod side chamber 5, the bottom-side chamber 6) and the tank 9 is relaxed by the first rod side restrictor 30d and the first bottom side restrictor 30e (the notches 40a and 40b), and therefore, it is possible to stably move the hydraulic cylinder 1 at a desired speed.
- the flow-combining control valve 60, 160 has: the second housing 100b; the second spool 70 received in the second spool hole 61 so as to be freely movable, the second spool hole 61 being formed in the second housing 100b; and the second fluid pressure port (the second rod side port 65a, the second bottom side port 65b) configured to communicate with the second fluid pressure passage (the second rod side passage 12b, the second bottom side passage 13b) and to open to the second spool hole 61, and the flow-combining control valve 60, 160 having the second neutral position 60A, 160A at which the communication between the second tank passage 17 and the connecting passage (the first connecting passage 14, the second connecting passage 15) and the communication between the second tank passage 17 and the second fluid pressure passage (the second rod side passage 12b, the second bottom side passage 13b) are respectively shut off, the second spool 70 has the third control land parts 73a and 73b facing the second fluid pressure port (the second rod side port 65a, the second bottom side port 65
- the second fluid pressure port (the second rod side port 65a, the second bottom side port 65b) is closed by the third control land parts 73a and 73b at the second neutral position 60A, 160A, and the second fluid pressure port (the second rod side port 65a, the second bottom side port 65b) is closed by the third control land parts 73a and 73b even in a state in which the flow-combining control valve 60, 160 has been switched to the second discharge position (the second contracting position 60C, 160C, the second extending position 60B) and in which the second spool 70 has completed the stroke.
- the amount of the second spool 70 overlapped with the second spool hole 61 is ensured.
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Abstract
Description
- The present invention relates to a fluid pressure control device.
-
JP2001-165106A - In the first switch valve, a pair of actuator ports are formed in a valve main body, and a spool is provided inside thereof so as to be freely slidable. In addition, the valve main body is formed with a U-shaped parallel feeder, and a discharge flow channel of a first pump is connected to the parallel feeder. When the spool is switched, a first actuator port is communicated with a tank port by annular grooves formed in the spool, and a second actuator port is communicated with the discharge flow channel of the first pump via the annular grooves and the parallel feeder.
- In the second switch valve, the valve main body is formed with the U-shaped parallel feeder, and one end portion thereof is connected to an end portion of the parallel feeder of the first switch valve. A tandem passage, a neutral passage, and a supply passage are formed in the valve main body of the second switch valve, and the discharge flow channel of a second pump is connected to the tandem passage and the supply passage. As the spool is switched, the discharged fluid from the second pump is supplied to the parallel feeder of the second switch valve. At this time, if the first switch valve has been switched, the discharged fluid from the second pump is supplied to the parallel feeder of the first switch valve via an end portion of the parallel feeder of the second switch valve and is supplied to the actuator port by being combined with the discharged fluid from the first pump.
- With the fluid pressure control device disclosed in
JP2001-165106A JP2001-165106A - In the above, in general, in a spool valve, in order to ensure the slidability of the spool, a small clearance is formed between an outer circumference of the spool and an inner circumference of a valve housing.
- With the fluid pressure control device disclosed in
JP2001-165106A - An object of the present invention is to suppress a leakage of working fluid from a spool valve of a fluid pressure control device.
- According to one aspect of the present invention, a fluid pressure control device, which is configured to be capable of combining working fluid discharged from a first pump and working fluid discharged from a second pump and of supplying the combined working fluid to a fluid pressure chamber of a fluid pressure actuator, includes: a first pump passage configured to guide the working fluid discharged from the first pump; a second pump passage configured to guide the working fluid discharged from the second pump; a first spool valve configured to control a flow of the working fluid to be supplied from the first pump to the fluid pressure actuator; a second spool valve configured to control the flow of the working fluid to be supplied from the second pump to the fluid pressure actuator; a connecting passage connecting the first spool valve and the second spool valve; a first fluid pressure passage configured to allow the first spool valve communicate with the fluid pressure chamber of the fluid pressure actuator; a second fluid pressure passage configured to allow the second spool valve communicate with the fluid pressure chamber of the fluid pressure actuator; a first tank passage connected to the first spool valve and communicated with a tank; and a second tank passage connected to the second spool valve and communicated with the tank. The first spool valve has: a first supply position at which the first fluid pressure passage is communicated with the first pump passage; and a first discharge position at which the first fluid pressure passage is communicated with the first tank passage and the first fluid pressure passage is communicated with the connecting passage. The second spool valve has: a second supply position at which the second fluid pressure passage is communicated with the second pump passage; and a second discharge position at which the connecting passage is communicated with the second tank passage and the second fluid pressure passage is shut off from the second tank passage.
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FIG. 1 is a hydraulic circuit diagram showing a fluid pressure control device according to an embodiment of the present invention. -
FIG. 2 is a sectional view showing the fluid pressure control device according to the embodiment of the present invention and shows a state in which a switch valve is set at a first neutral position and a flow-combining control valve is set at a second neutral position. -
FIG. 3 is a sectional view showing the fluid pressure control device according to the embodiment of the present invention and shows a state in which the switch valve is set at a first extending position and a flow-combining control valve is set at a second extending position. -
FIG. 4 is a hydraulic circuit diagram showing a modification of the fluid pressure control device according to the embodiment of the present invention. -
FIG. 5 is a hydraulic circuit diagram of the fluid pressure control device according to a comparative example of the present invention. -
FIG. 6 is an enlarged sectional view of the fluid pressure control device according to the comparative example of the present invention. - A fluid
pressure control device 100 according to an embodiment of the present invention will be described bellow with reference to the drawings. In the following, as an example, a description will be given of the fluidpressure control device 100 that is provided in a fluidpressure control system 101 used for a construction machinery, in particular a hydraulic excavator, to control flows of working fluid supplied/discharged to/from a fluid pressure actuator. - An overall configuration of the fluid
pressure control system 101 provided with the fluidpressure control device 100 will be first explained with reference toFIG. 1 . - The fluid
pressure control system 101 controls movement of a hydraulic cylinder 1 serving as the fluid pressure actuator for driving objects to be driven (not shown) such as a boom, an arm, a bucket, or the like. In the following, the fluidpressure control device 100 that controls the movement of the hydraulic cylinder 1 for driving the boom serving as the object to be driven will be explained as an example. - As shown in
FIG. 1 , the fluidpressure control system 101 is provided with afirst pump 7 and asecond pump 8 that are each driven by an engine (not shown) or a motor (not shown) and that discharge working oil serving as the working fluid, atank 9 that stores the working oil, and the fluidpressure control device 100 that moves the hydraulic cylinder 1 by controlling the flow of the working oil that is supplied/discharged to/from the hydraulic cylinder 1. - The hydraulic cylinder 1 is a double acting type cylinder having a
piston 4 that partitions an interior of acylinder tube 2 into arod side chamber 5 and a bottom-side chamber 6 that are respectively fluid pressure chambers. Apiston rod 3 is linked to thepiston 4. - As the working oil is supplied to the bottom-
side chamber 6 and the working oil is discharged from therod side chamber 5, the hydraulic cylinder 1 is extended to lift the boom. Conversely, as the working oil is supplied to therod side chamber 5 and the working oil is discharged from the bottom-side chamber 6, the hydraulic cylinder 1 is contracted to lower the boom. - The fluid
pressure control device 100 is provided with a firstneutral passage 10 that connects thefirst pump 7 and thetank 9, a secondneutral passage 11 that connects thesecond pump 8 and thetank 9, aswitch valve 30 serving as a first spool valve that is provided on the firstneutral passage 10 and that controls the flow of the working oil from thefirst pump 7 to the hydraulic cylinder 1, and a flow-combiningcontrol valve 60 serving as a second spool valve that is provided on the secondneutral passage 11 and that controls the flow of the working oil supplied from thesecond pump 8 to the hydraulic cylinder 1. The fluidpressure control device 100 can combine the working oil discharged from thefirst pump 7 and the working oil discharged from thesecond pump 8 and supply the combined working oil to the hydraulic cylinder 1. - The first
neutral passage 10 is formed of afirst pump passage 10a that is an upstream passage of theswitch valve 30 and that guides the working oil discharged from thefirst pump 7 and a firstdownstream passage 10b that is a downstream passage of theswitch valve 30. The secondneutral passage 11 is an upstream passage of the flow-combiningcontrol valve 60, and is formed of asecond pump passage 11a that guides the working oil discharged from thesecond pump 8 and a seconddownstream passage 11b that is a downstream passage of the flow-combiningcontrol valve 60. The firstdownstream passage 10b and the seconddownstream passage 11b are joined with each other and communicate with thetank 9. - In addition, the fluid
pressure control device 100 is provided with arod side passage 12 that communicates with therod side chamber 5 of the hydraulic cylinder 1, abottom side passage 13 that communicates with the bottom-side chamber 6 of the hydraulic cylinder 1, a first connectingpassage 14 and a second connectingpassage 15 that respectively connect theswitch valve 30 and the flow-combiningcontrol valve 60, afirst tank passage 16 that is connected to theswitch valve 30 and communicates with thetank 9, and asecond tank passage 17 that is connected to the flow-combiningcontrol valve 60 and communicates with thetank 9. - The
rod side passage 12 has a firstrod side passage 12a through which theswitch valve 30 is communicated with therod side chamber 5 and a secondrod side passage 12b through which the flow-combiningcontrol valve 60 is communicated with therod side chamber 5. The firstrod side passage 12a and the secondrod side passage 12b are joined with each other and communicate with therod side chamber 5. - The
bottom side passage 13 has a firstbottom side passage 13a through which theswitch valve 30 is communicated with the bottom-side chamber 6 and a secondbottom side passage 13b through which the flow-combiningcontrol valve 60 is communicated with the bottom-side chamber 6. The firstbottom side passage 13a and the secondbottom side passage 13b are joined with each other and communicate with thebottom side chamber 6. - The
switch valve 30 is a spool valve having eight ports and three positions. In theswitch valve 30, in response to an operation direction and an operation amount of an operation lever (not shown) by an operator, a pilot pressure is guided to a pair of firstpilot pressure chambers switch valve 30, a first spool 40 (seeFIG. 2 ), which will be described below, is moved to the position in accordance with the level of the pilot pressure externally supplied to the pair of firstpilot pressure chambers neutral position 30A, a first extendingposition 30B, and afirst contracting position 30C. - In a state in which the pilot pressure is not supplied to the pair of first
pilot pressure chambers switch valve 30 is maintained at the firstneutral position 30A by a biasing force exerted by centeringsprings neutral position 30A, the firstneutral passage 10 is opened, and the working oil discharged from thefirst pump 7 is guided to thetank 9 through the firstneutral passage 10. At the firstneutral position 30A, the respective communications of therod side chamber 5 and the bottom-side chamber 6 with thefirst pump passage 10a, thefirst tank passage 16, the first connectingpassage 14, and the second connectingpassage 15 are shut off. With such a configuration, the supply/discharge of the working oil to/from the hydraulic cylinder 1 is shut off, and the hydraulic cylinder 1 is in a load-holding state. - As the pilot pressure is guided to the one first
pilot pressure chamber 50a, theswitch valve 30 is switched to the first extendingposition 30B in accordance with the level of the pilot pressure. At the first extendingposition 30B, thefirst pump passage 10a of the firstneutral passage 10 is shut off from the firstdownstream passage 10b and is communicated with the firstbottom side passage 13a. In addition, at the first extendingposition 30B, the firstrod side passage 12a is communicated with thefirst tank passage 16 via a firstrod side restrictor 30d imparting resistance to the flow of the working oil flowing therethrough and is communicated with the first connectingpassage 14. With such a configuration, the working oil that has been discharged from thefirst pump 7 is supplied to the bottom-side chamber 6 and the working oil in therod side chamber 5 is discharged to thetank 9, and thereby, the hydraulic cylinder 1 is extended. In addition, the flowing amount of the working oil discharged from therod side chamber 5 through thefirst tank passage 16 is controlled by the firstrod side restrictor 30d, and thereby, the speed of the extension of the hydraulic cylinder 1 is controlled. - As the pilot pressure is guided to the other first
pilot pressure chamber 50b, theswitch valve 30 is switched to thefirst contracting position 30C in accordance with the level of the pilot pressure. At thefirst contracting position 30C, thefirst pump passage 10a is shut off from the firstdownstream passage 10b and is communicated with the firstrod side passage 12a. In addition, at thefirst contracting position 30C, the firstbottom side passage 13a is communicated with thefirst tank passage 16 via a firstbottom side restrictor 30e imparting resistance to the flow of the working oil flowing therethrough and is communicated with the second connectingpassage 15. With such a configuration, the working oil that has been discharged from thefirst pump 7 is supplied to therod side chamber 5, and the working oil in the bottom-side chamber 6 is discharged to thetank 9, and thereby, the hydraulic cylinder 1 is contracted. In addition, the flowing amount of the working oil discharged from the bottom-side chamber 6 through thefirst tank passage 16 is controlled by the firstbottom side restrictor 30e, and thereby, the speed of the extension of the hydraulic cylinder 1 is controlled. - The flow-combining
control valve 60 is the spool valve having eight ports and three positions. In the flow-combiningcontrol valve 60, when the operation amount of the operation lever by the operator is equal to or greater than a predetermined amount, the pilot pressure is guided to a pair of secondpilot pressure chambers control valve 60, a second spool 70 (seeFIG. 2 ), which will be described below, is moved to the position in accordance with the level of the pilot pressure externally supplied to the pair of secondpilot pressure chambers neutral position 60A, a second extendingposition 60B, and asecond contracting position 60C. - In a state in which the pilot pressure is not supplied to the pair of second
pilot pressure chambers control valve 60 is maintained at the secondneutral position 60A by the biasing force exerted by centeringsprings neutral position 60A, the secondneutral passage 11 is opened, and the working oil discharged from thesecond pump 8 is guided to thetank 9 through the secondneutral passage 11. In addition, at the secondneutral position 60A, the respective communications of thesecond tank passage 17 with the secondrod side passage 12b, the secondbottom side passage 13b, the first connectingpassage 14, and the second connectingpassage 15 are shut off. - As the pilot pressure is guided to the one second
pilot pressure chamber 80a, the flow-combiningcontrol valve 60 is switched to the second extendingposition 60B in accordance with the level of the pilot pressure. At the second extendingposition 60B, thesecond pump passage 11a of the secondneutral passage 11 is shut off from the seconddownstream passage 11b and is communicated with the secondbottom side passage 13b. With such a configuration, the working oil that has been discharged from thesecond pump 8 is combined with the working oil that has been discharged from thefirst pump 7, and the combined working oil is supplied to the bottom-side chamber 6. - At the second extending
position 60B, the first connectingpassage 14 is communicated with thesecond tank passage 17 via a secondrod side restrictor 60d. With such a configuration, a part of the working oil discharged from therod side chamber 5 is discharged to thetank 9 through theswitch valve 30, the first connectingpassage 14, the flow-combiningcontrol valve 60, and thesecond tank passage 17. The flowing amount of the working oil discharged from therod side chamber 5 through thesecond tank passage 17 is controlled by the secondrod side restrictor 60d, and thereby, the speed of the extension of the hydraulic cylinder 1 is controlled. In addition, at the second extendingposition 60B, the communication of the secondrod side passage 12b with thesecond tank passage 17 is shut off. - As the pilot pressure is guided to the other second
pilot pressure chamber 80b, the flow-combiningcontrol valve 60 is switched to thesecond contracting position 60C in accordance with the level of the pilot pressure. At thesecond contracting position 60C, thesecond pump passage 11a is shut off from the seconddownstream passage 11b and is communicated with the secondrod side passage 12b. With such a configuration, the working oil that has been discharged from thesecond pump 8 is combined with the working oil that has been discharged from thefirst pump 7 and guided to the firstrod side passage 12a, and the combined working oil is supplied to therod side chamber 5. - In addition, at the
second contracting position 60C, the second connectingpassage 15 is communicated with thesecond tank passage 17 via a secondbottom side restrictor 60e. With such a configuration, a part of the working oil that has been discharged from the bottom-side chamber 6 is discharged to thetank 9 through theswitch valve 30, the second connectingpassage 15, the flow-combiningcontrol valve 60, and thesecond tank passage 17. The flowing amount of the working oil discharged from the bottom-side chamber 6 through thesecond tank passage 17 is controlled by the secondbottom side restrictor 60e, and thereby, the speed of the extension of the hydraulic cylinder 1 is controlled. In addition, at thesecond contracting position 60C, the communication between the secondbottom side passage 13b and thesecond tank passage 17 is shut off. - As described above, the fluid
pressure control device 100 according to this embodiment is configured such that, in both cases of the extension and contraction of the hydraulic cylinder 1, it is possible to combine the working oil discharged from thesecond pump 8 with the working oil that has been discharged from thefirst pump 7 and to supply the combined working oil to the hydraulic cylinder 1. - In addition, in the fluid
pressure control device 100, the flow-combiningcontrol valve 60 shuts off thesecond tank passage 17 from the secondrod side passage 12b and the secondbottom side passage 13b at the secondneutral position 60A. In the flow-combiningcontrol valve 60, at the second extendingposition 60B, the communication between the secondrod side passage 12b and thesecond tank passage 17 is shut off, and at thesecond contracting position 60C, the communication between the secondbottom side passage 13b and thesecond tank passage 17 is shut off. As described above, the secondbottom side passage 13b and the secondrod side passage 12b serving as a second fluid pressure passage guide the working oil that has been discharged from thesecond pump 8 to the hydraulic cylinder 1, but do not guide the working oil that has been discharged from the hydraulic cylinder 1 to thetank 9. The working oil that has been discharged from the hydraulic cylinder 1 is discharged to thetank 9 from the first connectingpassage 14 or the second connectingpassage 15 through thesecond tank passage 17. - In a case in which the working oil discharged from the
first pump 7 and the working oil discharged from thesecond pump 8 are combined, and in which the combined working oil is supplied to the bottom-side chamber 6 serving as a fluid pressure chamber, the first connectingpassage 14 corresponds to "a connecting passage", the firstbottom side passage 13a corresponds to "a first fluid pressure passage", and the secondbottom side passage 13b corresponds to "the second fluid pressure passage" in the claims. In addition, in this case, the first extendingposition 30B, thefirst contracting position 30C, and the first rod side restrictor 30d of theswitch valve 30 correspond to "a first supply position", "a first discharge position", and "a first discharge restrictor" in the claims, respectively, and the second extendingposition 60B and thesecond contracting position 60C of the flow-combiningcontrol valve 60 correspond to "a second supply position" and "a second discharge position" in the claims, respectively. - Conversely, in a case in which the working oil discharged from the
first pump 7 and the working oil discharged from thesecond pump 8 are combined, and in which the combined working oil is supplied to therod side chamber 5 serving as the fluid pressure chamber, the second connectingpassage 15, the firstrod side passage 12a, and the secondrod side passage 12b correspond to "the connecting passage", "the first fluid pressure passage", and "the second fluid pressure passage" in the claims, respectively. In addition, in this case, thefirst contracting position 30C, the first extendingposition 30B, and the first bottom side restrictor 30e of theswitch valve 30 correspond to "the first supply position", "the first discharge position", and "the first discharge restrictor" in the claims, respectively, and thesecond contracting position 60C and the second extendingposition 60B of the flow-combiningcontrol valve 60 correspond to "the second supply position" and "the second discharge position" in the claims, respectively. - Next, a specific configuration of the fluid
pressure control device 100 according to this embodiment will be described with reference toFIG. 2 . - As shown in
FIG. 2 , theswitch valve 30 has afirst housing 100a in which afirst spool hole 31 is formed, thefirst spool 40 that is received in thefirst spool hole 31 so as to be freely movable, the pair of firstpilot pressure chambers first spool 40, and a centeringspring 58 that imparts the biasing force to thefirst spool 40. - The
first spool hole 31 is a through hole whose both ends respectively open at end surfaces of thefirst housing 100a. In thefirst housing 100a, a firstdownstream side port 32 that communicates with the firstdownstream passage 10b of the firstneutral passage 10, a pair of firstupstream side ports first pump passage 10a of the firstneutral passage 10 on the upstream side, a firstrod side port 35a that communicates with the firstrod side passage 12a, a firstbottom side port 35b that communicates with the firstbottom side passage 13a, a pair of connectingports passage 14 and the second connectingpassage 15, and a pair offirst tank ports first tank passage 16 are respectively formed to have annular shapes in an inner circumference of thefirst spool hole 31 so as to open to thefirst spool hole 31. - In addition, although a detailed illustration is omitted, a
first bridge passage 10c whose both ends open to thefirst spool hole 31 is formed in thefirst housing 100a. Both ends of thefirst bridge passage 10c open to thefirst spool hole 31 via a pair offirst bridge ports first spool hole 31. - A pair of
first caps first spool hole 31 are respectively attached to both ends of thefirst housing 100a. The pair of firstpilot pressure chambers switch valve 30 are respectively formed in the pair offirst caps - In the one
first cap 51a, a recessedportion 52a into which thefirst spool 40 can enter and apilot port 54a that communicates with the recessedportion 52a are formed. Because the recessedportion 52a is provided, the one firstpilot pressure chamber 50a is formed, and so, the pilot pressure is guided to the recessedportion 52a through thepilot port 54a. - In the other
first cap 51b, a firstlarge diameter hole 52b into which thefirst spool 40 can enter, a firstsmall diameter hole 53b that has a smaller inner diameter than the firstlarge diameter hole 52b and that communicates with the firstlarge diameter hole 52b, and apilot port 54b that communicates with the firstsmall diameter hole 53b are formed. Because the firstsmall diameter hole 53b and the firstlarge diameter hole 52b are provided, the other firstpilot pressure chamber 50b is formed, and so, the pilot pressure is guided to the firstpilot pressure chamber 50b through thepilot port 54b. - A first support member 55 is attached to an end portion of the
first spool 40 so as to be coaxial with thefirst spool 40. The first support member 55 has afirst shaft portion 56 that is fixed to the end portion of thefirst spool 40 and afirst head portion 57 that has a larger outer diameter than thefirst shaft portion 56. As shown inFIG. 2 , thefirst head portion 57 of the first support member 55 is inserted into the firstsmall diameter hole 53b at the firstneutral position 30A. - The centering
spring 58 is provided in the otherfirst cap 51b. Specifically, the centeringspring 58 is provided around an outer circumference of thefirst shaft portion 56 of the first support member 55 between the end surface of thefirst spool 40 and thefirst head portion 57. When theswitch valve 30 is positioned at the firstneutral position 30A, both ends of the centeringspring 58 are respectively seated, viaspring washers first housing 100a and on astep surface 52c formed between the firstlarge diameter hole 52b and the firstsmall diameter hole 53b of thefirst cap 51b. The single centeringspring 58 shown inFIG. 2 functions as the pair of centeringsprings FIG. 1 . - As the
first spool 40 is moved to the right direction in the figure by the pilot pressure guided to the one firstpilot pressure chamber 50a, the onespring washer 59a being seated on thefirst housing 100a is pushed by thefirst spool 40 and is moved to the right direction in the figure together with thefirst spool 40. At this time, the movement of theother spring washer 59b to the right direction in the figure is restricted by thestep surface 52c of thefirst cap 51b, and so, the centeringspring 58 is compressed. As the supply of the pilot pressure to the firstpilot pressure chamber 50a is shut off, thefirst spool 40 is moved to the left direction in the figure by a restoring force of the centeringspring 58, and thereby, theswitch valve 30 is held at the firstneutral position 30A. - Conversely, as the
first spool 40 is moved to the left direction in the figure by the pilot pressure guided to the other firstpilot pressure chamber 50b, theother spring washer 59b being seated on thestep surface 52c of thefirst cap 51b is pushed by thefirst head portion 57 and is moved to the left direction in the figure together with thefirst spool 40. At this time, between the movement of the onespring washer 59a to the left direction in the figure is restricted by thefirst housing 100a, the centeringspring 58 is caused to be compressed. When the supply of the pilot pressure to the firstpilot pressure chamber 50b is shut off, thefirst spool 40 is moved to the right direction in the figure by the restoring force of the centeringspring 58, and thereby, theswitch valve 30 is held at the firstneutral position 30A. - The
first spool 40 has afirst land part 41, a pair ofsecond land parts third land parts fourth land parts fifth land parts first spool hole 31. In thefirst spool 40, the onefifth land part 45a, the onefourth land part 44a, the onethird land part 43a, the onesecond land part 42a, thefirst land part 41, the othersecond land part 42b, the otherthird land part 43b, the otherfourth land part 44b, and the otherfifth land part 45b are provided in this order in the shaft direction from one end towards the other end of the first spool 40 (from the left side to the right side inFIG. 2 ). - A pair of
first pump grooves first land part 41 and the pair ofsecond land parts First bridge grooves second land parts third land parts grooves third land parts fourth land parts First tank grooves fourth land parts fifth land parts - In outer circumferences of the pair of
fourth land parts first spool 40,notches rod side restrictor 30d and the firstbottom side restrictor 30e (seeFIG. 1 ) are formed so as to respectively extend in the shaft direction of thefirst spool 40 and so as to respectively communicate with thefirst tank grooves notches tank 9 from therod side chamber 5 and the bottom-side chamber 6 through thefirst tank passage 16. In this embodiment, although a plurality of (two for each inFIG. 2 )notches first spool 40, the configuration is not limited thereto, and only a single notch may be formed. In a case in which the plurality ofnotches first spool 40, whole of the plurality of thenotch 40a form the first rod side restrictor 30d shown inFIG. 1 . Similarly, in a case in which the plurality ofnotches 40b are formed in thefirst spool 40, whole of the plurality ofnotches 40b form the firstbottom side restrictor 30e. - The flow-combining
control valve 60 has asecond housing 100b in which asecond spool hole 61 is formed, thesecond spool 70 that is received in thesecond spool hole 61 so as to be freely movable, the secondpilot pressure chambers second spool 70, and a centeringspring 88 that imparts the biasing force to thesecond spool 70. - In this embodiment, the
second housing 100b is formed integrally with thefirst housing 100a of theswitch valve 30. In other words, theswitch valve 30 and the flow-combiningcontrol valve 60 are accommodated in a common housing functioning as both of thefirst housing 100a and thesecond housing 100b. The configuration is not limited thereto, and thefirst housing 100a and thesecond housing 100b may be formed separately from each other. - The
second spool hole 61 is a through hole whose both ends respectively open at end surfaces of thesecond housing 100b. Thesecond spool hole 61 is formed such that its center axis extends in parallel with the center axis of thefirst spool hole 31. In thesecond housing 100b, a seconddownstream side port 62 that communicates with the seconddownstream passage 11b of the secondneutral passage 11, a pair of secondupstream side ports second pump passage 11a of the secondneutral passage 11 on the upstream passage, a secondrod side port 65a that communicates with the secondrod side passage 12b, a secondbottom side port 65b that communicates with the secondbottom side passage 13b, a pair of combiningports 66a and 66b that respectively communicate with the first connectingpassage 14 and the second connectingpassage 15, and a pair ofsecond tank ports 67a and 67b that communicate with thesecond tank passage 17 are respectively formed to have annular shapes in an inner circumference of thesecond spool hole 61 so as to open to thesecond spool hole 61. - In addition, a
second bridge passage 11c whose both ends open to thesecond spool hole 61 is formed in thesecond housing 100b. Both ends of thesecond bridge passage 11c open to thesecond spool hole 61 via a pair ofsecond bridge ports second spool hole 61. - A pair of
second caps second spool hole 61 are respectively attached to both ends of thesecond housing 100b. The pair of secondpilot pressure chambers control valve 60 are respectively formed in the pair ofsecond caps spring 88 is provided in the onesecond cap 81a. In addition, asecond support member 85 is attached to end portion of thesecond spool 70 so as to be coaxial with thesecond spool 70. - Because the pair of
second caps second support member 85 have the similar configurations with those of the pair offirst caps switch valve 30, a detailed description is omitted. In the onesecond cap 81a, a recessedportion 82a and apilot port 84a are formed in a corresponding manner to the recessedportion 52a and thepilot port 54a in the onefirst cap 51a. In the othersecond cap 81b, a second large diameter hole 82b, a secondsmall diameter hole 83b, a step surface 82c, and apilot port 84b are formed in a corresponding manner to the firstlarge diameter hole 52b, the firstsmall diameter hole 53b, thestep surface 52c, and thepilot port 54b in the otherfirst cap 51b. In addition, thesecond support member 85 has asecond shaft portion 86 and asecond head portion 87 in a corresponding manner to thefirst shaft portion 56 and thefirst head portion 57 in the first support member 55. - In addition, because the centering
spring 88 and a pair ofspring washers control valve 60 also have similar configurations with those of the centeringspring 58 and the pair ofspring washers switch valve 30, a detailed description is omitted. The single centeringspring 88 of the flow-combiningcontrol valve 60 shown inFIG. 2 exhibits functions of the centeringsprings FIG. 1 . - The
second spool 70 has a firstcontrol land part 71, a pair of secondcontrol land parts control land parts control land parts control land parts second spool hole 61. In thesecond spool 70, the one fifthcontrol land part 75a, the one fourthcontrol land part 74a, the one thirdcontrol land part 73a, the one secondcontrol land part 72a, the firstcontrol land part 71, the other secondcontrol land part 72b, the other thirdcontrol land part 73b, the other fourthcontrol land part 74b, and the other fifthcontrol land part 75b are provided in this order in the shaft direction from one end towards the other end of the second spool 70 (from the left side to the right side inFIG. 2 ). - A pair of
second pump grooves control land part 71 and the pair of secondcontrol land parts Second bridge grooves control land parts control land parts grooves control land parts control land parts second tank grooves control land parts control land parts - In outer circumference of the pair of fourth
control land parts second spool 70,notches rod side restrictor 60d and the secondbottom side restrictor 60e are formed so as to respectively extend in the shaft direction of thesecond spool 70 and so as to respectively communicate with thesecond tank grooves notches tank 9 from therod side chamber 5 and the bottom-side chamber 6 through thesecond tank passage 17. In this embodiment, although a plurality of (two for each inFIG. 2 )notches second spool 70, the configuration is not limited thereto, and only a single notch may be formed. In a case in which the plurality ofnotches second spool 70, whole of the plurality of thenotches 70a form the second rod side restrictor 60d shown inFIG. 1 . Similarly, in a case in which the plurality ofnotches 70b are formed in thesecond spool 70, whole of the plurality ofnotches 70b form the secondbottom side restrictor 60e. - Next, action of this embodiment will be described.
- In the
switch valve 30, with reference to thefirst land part 41, theland parts grooves first spool 40, which are provided on the one side in the shaft direction, and theland parts grooves first spool 40, which are provided on the other side in the shaft direction, are configured such that their respective functions are exchanged with each other between corresponding configurations (configurations forming the pair) in accordance with the moving direction of the hydraulic cylinder 1. In addition, with reference to the firstdownstream side port 32, theports ports control valve 60, with reference to the firstcontrol land part 71, thecontrol land parts grooves second spool 70, which are provided on the one side in the shaft direction, and thecontrol land parts grooves second spool 70, which are provided on the other side in the shaft direction, are configured such that their respective functions are exchanged with each other between corresponding configurations in accordance with the extension and the contraction of the hydraulic cylinder 1. In addition, in the flow-combiningcontrol valve 60, with reference to the seconddownstream side port 62, theports ports - The movement of the
switch valve 30 will be described first. - When there is no operational input from the operator, the pilot pressure is not guided to neither of the pair of first
pilot pressure chambers switch valve 30. In this case, as shown inFIG. 2 , the pair of firstupstream side ports downstream side port 32 of theswitch valve 30 are communicated via the pair offirst pump grooves neutral passage 10 is opened, and the working oil that has been discharged from thefirst pump 7 is guided to thetank 9. - When there is the operational input by the operator for the operation lever such that the hydraulic cylinder 1 is to be extended, the pilot pressure is guided to the one first
pilot pressure chamber 50a of theswitch valve 30 in accordance with the operational input. Thefirst spool 40 is moved in accordance with the level of the pilot pressure, and theswitch valve 30 is shifted to the first extendingposition 30B in accordance with the moved amount of the first spool 40 (seeFIG. 1 ). - Specifically, as shown in
FIG. 3 , as the pilot pressure is guided to the firstpilot pressure chamber 50a, thefirst spool 40 is moved to the right direction in the figure against the biasing force exerted by the centeringspring 58. With such a configuration, the communications of the pair of firstupstream side ports downstream side port 32 are shut off by thefirst land part 41 and thesecond land part 42a of thefirst spool 40. In addition, the one firstupstream side port 33a is communicated with thefirst bridge port 34a via thefirst bridge groove 47a, and thefirst bridge port 34b is communicated with the firstbottom side port 35b via thefirst bridge groove 47b. Furthermore, the firstrod side port 35a is communicated with the connectingport 36a via the first connectinggroove 48a, and the connectingport 36a is communicated with thefirst tank port 37a via thenotch 40a and thefirst tank groove 49a. - Therefore, the working oil that has been discharged from the
first pump 7 is guided to thefirst bridge passage 10c from thefirst pump passage 10a through thefirst bridge groove 47a of thefirst spool 40, and then, the working oil is guided to the bottom-side chamber 6 from thefirst bridge passage 10c through thefirst bridge groove 47b and the firstbottom side passage 13a. The working oil in therod side chamber 5 is discharged to thetank 9 by being guided to thefirst tank passage 16 from the firstrod side passage 12a through thenotch 40a. By doing so, the hydraulic cylinder 1 is extended. In addition, the part of the working oil in therod side chamber 5 is guided to the combining port 66a of the flow-combiningcontrol valve 60 from the firstrod side port 35a through the connectingport 36a and the first connectingpassage 14. - As the moved amount of the
first spool 40 to the right direction inFIG. 2 is increased, an opening area of thenotch 40a to the connectingport 36a is increased, and the resistance imparted to the flow of the working oil is decreased. Thenotch 40a is formed to have the length along the shaft direction of thefirst spool 40 such that, along with the movement of thefirst spool 40 to the right direction inFIG. 2 , the communication between the firstrod side port 35a and the connectingport 36a is established before the communication between thefirst tank port 37a and the connectingport 36a is established. - In a case in which the communication between the
first tank port 37a and the connectingport 36a is established first by thenotch 40a, and subsequently, the communication between the firstrod side port 35a and the connectingport 36a is established, as thefirst spool 40 is moved during this period, the opening area of thenotch 40a to the connectingport 36a is increased. Thus, the resistance imparted by thenotch 40a to the flow of the working oil is reduced, and it becomes more difficult to effectively suppress a pressure change caused by the establishment of the communication between therod side chamber 5 and thetank 9 by the establishment of the communication between the firstrod side port 35a and the connectingport 36a. In contrast, as described in this embodiment, by employing the configuration in which the communication between the firstrod side port 35a and the connectingport 36a is established first, as thenotch 40a then comes to communicate with the connectingport 36a, it is possible to readily discharge the working oil in therod side chamber 5 to thetank 9 through thenotch 40a, which is in a state where the opening area to the connectingport 36a is relatively small. With such a configuration, the pressure change caused by the establishment of the communication between therod side chamber 5 and thetank 9 is effectively relaxed by thenotch 40a, and therefore, it is possible to allow the hydraulic cylinder 1 to extend stably. - Next, the movement of the flow-combining
control valve 60 will be described. - In a case in which there is no operational input by the operator and in a case in which the operation amount of the operation lever for extending the hydraulic cylinder 1 is smaller than the predetermined amount, the pilot pressure is not supplied to the second
pilot pressure chambers control valve 60, and the flow-combiningcontrol valve 60 is held at the secondneutral position 60A by the biasing force exerted by the centering spring 88 (seeFIG. 1 ). In this state, as shown inFIG. 2 , the pair of secondupstream side ports downstream side port 62 of the flow-combiningcontrol valve 60 are communicated via the pair ofsecond pump grooves neutral passage 11 is opened, and the working oil discharged from thesecond pump 8 is guided to thetank 9. - Therefore, in a case in which the operation amount of the operation lever for extending the hydraulic cylinder 1 is smaller than the predetermined amount, only the
switch valve 30 is switched to the first extendingposition 30B (seeFIG. 1 ), and the hydraulic cylinder 1 is extended only by the working oil supplied from thefirst pump 7. - When the operation amount of the operation lever for extending the hydraulic cylinder 1 becomes equal to or greater than the predetermined amount, the pilot pressure is also guided to the one second
pilot pressure chamber 80a of the flow-combiningcontrol valve 60. With such a configuration, thesecond spool 70 is moved in accordance with the level of the pilot pressure, and the flow-combiningcontrol valve 60 is shifted to the second extendingposition 60B in accordance with the moved amount of the second spool 70 (seeFIG. 1 ). - Specifically, as the pilot pressure is guided to the second
pilot pressure chamber 80a of the flow-combiningcontrol valve 60, thesecond spool 70 is moved to the right direction in the figure against the biasing force exerted by the centeringspring 88. With such a configuration, the communications of the pair of secondupstream side ports downstream side port 62 are shut off by the firstcontrol land part 71 and the secondcontrol land part 72a. In addition, the one secondupstream side port 63a is communicated with thesecond bridge port 64a via thesecond bridge groove 77a, and thesecond bridge port 64b is communicated with the secondbottom side port 65b via thesecond bridge groove 77b. Thus, the working oil discharged from thesecond pump 8 is guided to thesecond bridge passage 11c from thesecond pump passage 11a through thesecond bridge groove 77a of thesecond spool 70 and is guided to the secondbottom side passage 13b from thesecond bridge passage 11c through thesecond bridge groove 77b. With such a configuration, the working oil discharged from thesecond pump 8 is guided to the bottom-side chamber 6 by being combined with the working oil that has been discharged from thefirst pump 7. - In addition, the combining port 66a is communicated with the
second tank port 67a via thenotch 70a and asecond tank groove 79a. Thus, the part of the working oil in therod side chamber 5 is guided to the flow-combiningcontrol valve 60 from theswitch valve 30 through the first connectingpassage 14 and is discharged to thetank 9 through thesecond tank passage 17. - As described above, when the working oil discharged from the
first pump 7 and the working oil discharged from thesecond pump 8 are combined, the working oil that has been discharged from the hydraulic cylinder 1 is discharged to thetank 9 through theswitch valve 30, and at the same time, discharged to thetank 9 also through the flow-combiningcontrol valve 60. Thus, the working oil that has been discharged from the hydraulic cylinder 1 is discharged to thetank 9 through thenotch 40a (the first bottom side restrictor 30e) of theswitch valve 30, and at the same time, discharged to thetank 9 through thenotch 70a (the second bottom side restrictor 60e) of the flow-combiningcontrol valve 60. Therefore, the hydraulic cylinder 1 is extended at the speed corresponding to the resistance imparted to the working oil that has been discharged from therod side chamber 5 by thenotch 40a of theswitch valve 30 and thenotch 70a of the flow-combiningcontrol valve 60. - Here, for ease of understanding the present invention, a fluid
pressure control device 300 according to a comparative example of the present invention will be described with reference toFIGs. 5 and6 . Configurations that are similar to those in the present embodiment are assigned the same reference signs, and descriptions thereof shall be omitted appropriately. - As shown in
FIGs. 5 and6 , in the fluidpressure control device 300 according to the comparative example, the first connectingpassage 14 and the second connectingpassage 15 as described in this embodiment are not provided. As shown inFIG. 5 , aswitch valve 230 according to the comparative example differs from the configuration in the above-mentioned embodiment in that, at a first extendingposition 230B, the firstrod side passage 12a is not communicated with the first connectingpassage 14, and at afirst contracting position 230C, the firstbottom side passage 13a is not communicated with the second connectingpassage 15. - In addition, in a flow-combining
control valve 260 according to the comparative example, at a second extendingposition 260B, the secondrod side passage 12b is communicated with thesecond tank passage 17. The part of the working oil in therod side chamber 5 is discharged to thetank 9 from the secondrod side passage 12b through the flow-combiningcontrol valve 260 and thesecond tank passage 17. In addition, in the flow-combiningcontrol valve 260, at asecond contracting position 260C, the secondbottom side passage 13b is communicated with thesecond tank passage 17. The part of the working oil in the bottom-side chamber 6 is discharged to thetank 9 from the secondbottom side passage 13b through the flow-combiningcontrol valve 260 and thesecond tank passage 17. - Similarly to the above-mentioned embodiment, in the
switch valve 230, at a firstneutral position 230A, the firstneutral passage 10 is opened, and the respective communications of the firstrod side passage 12a and the firstbottom side passage 13a with thefirst pump passage 10a and thefirst tank passage 16 are shut off. In addition, in the flow-combiningcontrol valve 260, at a secondneutral position 260A, the secondneutral passage 11 is opened, and the respective communications of the secondrod side passage 12b and the secondbottom side passage 13b with thesecond pump passage 11a and thesecond tank passage 17 are shut off. - A case in which the hydraulic cylinder 1 is to be extended will be described, as an example, with reference to an enlarged sectional view shown in
FIG. 6 . In the fluidpressure control device 300, the firstrod side port 35a and thefirst tank port 37a of theswitch valve 230 are adjacent with each other in the shaft direction, and other ports like the connectingport 36a in the above-mentioned embodiment are not provided between these ports. Thenotch 40a that communicates with thefirst tank groove 49a is formed in athird land part 243a of afirst spool 240 that closes the firstrod side port 35a in a state in which theswitch valve 230 has been switched to the firstneutral position 230A. Similarly, the secondrod side port 65a and thesecond tank port 67a of the flow-combiningcontrol valve 260 are adjacent with each other in the shaft direction. Thenotch 70a that communicates with thesecond tank groove 79a is formed in a thirdcontrol land part 273a of asecond spool 270 that closes the secondrod side port 65a in a state in which the flow-combiningcontrol valve 260 has been switched to the secondneutral position 260A. - As described above, in the fluid
pressure control device 300 according to the comparative example, the working oil discharged from thesecond pump 8 is supplied to the bottom-side chamber 6 or therod side chamber 5 through the secondbottom side passage 13b or the secondrod side passage 12b. The part of the working oil in the bottom-side chamber 6 or therod side chamber 5 is discharged to thetank 9 from the secondbottom side passage 13b or the secondrod side passage 12b through the flow-combiningcontrol valve 260. - Here, in general, in the spool valve, in order to ensure the slidability of the spool, a small clearance is formed between the outer circumference of the spool and the inner circumference of the valve housing. Therefore, in a case in which the communication of the tank with the rod side chamber and the bottom-side chamber is controlled by the spool valve, even in a state in which the communication with the tank is shut off, there is a risk in that the working oil leaks out to the tank through the clearance formed around the outer circumference of the spool.
- Furthermore, in the hydraulic cylinder, the load (the self weight) of the objects to be driven may act only on either of the rod side chamber or the bottom-side chamber. In such a case, in the load-holding state in which the supply/discharge of the working oil is stopped and the hydraulic cylinder is maintained at a stopped state, the working oil in the rod side chamber or the bottom-side chamber, on which the load pressure acts, tends to leak through the clearance formed around the outer circumference of the spool due to the influence of the load pressure. For example, in a case in which the hydraulic cylinder is provided to drive the boom, at the load-holding state, the self weight (the load) of the boom acts on the bottom-side chamber.
- Thus, in the fluid
pressure control device 300 according to the comparative example, when theswitch valve 230 is switched to the firstneutral position 230A to maintain the hydraulic cylinder 1 at the stopped state (the load-holding state), the load pressure acting on the bottom-side chamber 6 respectively acts on theswitch valve 230 and the flow-combiningcontrol valve 260. Therefore, in the fluidpressure control device 300 according to the comparative example, there is a risk in that the working oil in the bottom-side chamber 6 leaks out through the clearance formed between the spool (thefirst spool 240, the second spool 270) and the spool hole (thefirst spool hole 31, the second spool hole 61) in each of theswitch valve 230 and the flow-combiningcontrol valve 260. If the working oil in the bottom-side chamber 6, on which the load pressure acts, leaks out through the clearance, the hydraulic cylinder 1 is contracted in accordance with the leaked amount, and the load can no longer be held. - In addition, in the fluid
pressure control device 300, in a state in which the flow-combiningcontrol valve 260 has been switched to the secondneutral position 260A, the thirdcontrol land part 273a closes the secondrod side port 65a, and thenotch 70a is formed in the thirdcontrol land part 273a. Therefore, an amount of the thirdcontrol land part 273a overlapped with thesecond spool hole 61 on the inner side of the wall portion W is smaller by an amount corresponding to the length of thenotch 70a opposing to an wall portion W between the secondrod side port 65a and thesecond tank port 67a. Thus, the working oil in therod side chamber 5 tends to leak out even further to thetank 9 through the clearance formed around the outer circumference of thesecond spool 270. - In contrast, in this embodiment, as described above, even if the flow-combining
control valve 60 is switched to the second extendingposition 60B, the secondrod side passage 12b is not communicated with thetank 9 and is shut off. In addition, even if the flow-combiningcontrol valve 60 is switched to thesecond contracting position 60C, the secondbottom side passage 13b is not communicated with thetank 9 and is shut off. In other words, the working oil in therod side chamber 5 and the bottom-side chamber 6 is not discharged to thetank 9 through the secondrod side passage 12b and the secondbottom side passage 13b, respectively. As described above, because the secondrod side passage 12b and the secondbottom side passage 13b are not communicated with thetank 9 through the flow-combining control valve 60 (the second spool 70), the leakage of the working oil in therod side chamber 5 and the bottom-side chamber 6 to thetank 9 from the clearance around the outer circumference of thesecond spool 70 of the flow-combiningcontrol valve 60 is suppressed. - In addition, As shown in
FIG. 2 , in a state in which the flow-combiningcontrol valve 60 has been switched to the secondneutral position 60A, the secondrod side port 65a is closed by the thirdcontrol land part 73a of thesecond spool 70. As shown inFIG. 3 , even in a state in which the flow-combiningcontrol valve 60 has been switched to the second extendingposition 60B, more specifically, even in a state in which thesecond spool 70 has completed a full stroke in the direction in which the flow-combiningcontrol valve 60 is switched to the second extendingposition 60B, the secondrod side port 65a is completely closed by the thirdcontrol land part 73a of thesecond spool 70. In this embodiment, the state in which thesecond spool 70 has completed the stroke in the direction in which the flow-combiningcontrol valve 60 is switched to the second extendingposition 60B is the state in which asecond head portion 87 of thesecond support member 85 provided on the end portion of thesecond spool 70 is in contact with thesecond cap 81b (the state shown inFIG. 3 ). - As described above, in the flow-combining
control valve 60, the secondrod side port 65a is completely closed by the thirdcontrol land part 73a from the state in which the flow-combiningcontrol valve 60 is in the secondneutral position 60A to the state in which thesecond spool 70 has completed the stroke such that the flow-combiningcontrol valve 60 is switched to the second extendingposition 60B. In other words, because the flow-combiningcontrol valve 60 has a configuration in which the communication between the secondrod side passage 12b and thesecond tank passage 17 is shut off at the second extendingposition 60B, there is no need to provide the notch on thesecond tank port 67a side of the thirdcontrol land part 73a. With such a configuration, the amount of the thirdcontrol land part 73a overlapped with thesecond spool hole 61 in the shaft direction of thesecond spool 70 can be increased. Therefore, the leakage of the working oil from the secondrod side port 65a to thesecond tank port 67a through the clearance between the thirdcontrol land part 73a and thesecond spool hole 61 is suppressed. - In addition, in the flow-combining
control valve 60, the combiningports 66a and 66b are respectively provided between the secondrod side port 65a and thesecond tank port 67a and between the secondbottom side port 65b and the second tank port 67b. In the flow-combiningcontrol valve 60, at the secondneutral position 60A, the communication between the secondrod side port 65a and the combining port 66a and the communication between the secondbottom side port 65b and the combiningport 66b are respectively shut off by the thirdcontrol land parts rod side port 65a and the secondbottom side port 65b, the load pressure is shut off by the thirdcontrol land parts second tank port 67a due to the action of the load pressure is suppressed. Therefore, the leakage of the working oil in the secondrod side port 65a to thesecond tank port 67a is further suppressed. - According to the embodiment mentioned above, the advantages described below are afforded.
- In the fluid
pressure control device 100, in the flow-combiningcontrol valve 60, the communication between the secondrod side passage 12b and thesecond tank passage 17 is shut off at the second extendingposition 60B, and the communication between the secondbottom side passage 13b and thesecond tank passage 17 is shut off at thesecond contracting position 60C. The flow-combiningcontrol valve 60 is configured such that the secondrod side passage 12b and the secondbottom side passage 13b are always in communication with thesecond tank passage 17. More specifically, even in a state in which thesecond spool 70 has completed the stroke in the direction in which the flow-combiningcontrol valve 60 is switched to the second extendingposition 60B, the secondrod side port 65a, which is always in communication with therod side chamber 5, is closed by the thirdcontrol land part 73a. In addition, even in a state in which thesecond spool 70 has completed the stroke in the direction in which the flow-combiningcontrol valve 60 is switched to thesecond contracting position 60C, the secondbottom side port 65b, which is always in communication with the bottom-side chamber 6, is closed by the thirdcontrol land part 73b. Thus, the leakage of the working oil in therod side chamber 5 and the bottom-side chamber 6 to thetank 9 through the clearance around the outer circumference of thesecond spool 70 is suppressed. - Next, a modification of the present invention will be described.
- The modification shown in
FIG. 4 will be described first. - In the above-mentioned embodiment, the second
rod side passage 12b is shut off from thesecond tank passage 17 when the flow-combiningcontrol valve 60 is in the second extendingposition 60B, and the secondbottom side passage 13b is shut off from thesecond tank passage 17 when the flow-combiningcontrol valve 60 is in thesecond contracting position 60C. In other words, in the above-mentioned embodiment, each of therod side chamber 5 and the bottom-side chamber 6 corresponds to "the fluid pressure chamber" in the claims, and the present invention is applied to both of the control of the working oil to be supplied/discharged to/from therod side chamber 5 and the control of the working oil to be supplied/discharged to/from the bottom-side chamber 6. In contrast, the present invention may only be applied to either one of the control of the working oil to be supplied/discharged to/from therod side chamber 5 and the control of the working oil to be supplied/discharged to/from the bottom-side chamber 6. In the following, specific description will be given with reference toFIG. 4 . - The modification shown in
FIG. 4 is an example showing a configuration in which the present invention is only applied to the control of the flow of the working oil supplied/discharged to/from the bottom-side chamber 6. The fluidpressure control device 100 according to the modification shown inFIG. 4 is provided with, similarly to the above-mentioned embodiment, the firstneutral passage 10, the secondneutral passage 11, the firstrod side passage 12a, the secondrod side passage 12b, the firstbottom side passage 13a (the first fluid pressure passage), the secondbottom side passage 13b (the second fluid pressure passage), the second connecting passage 15 (the connecting passage), thefirst tank passage 16, and thesecond tank passage 17. On the other hand, the fluidpressure control device 100 according to the modification is not provided with the first connectingpassage 14 in the above-mentioned embodiment. - A
switch valve 130 according to the modification has: a firstneutral position 130A at which the firstneutral passage 10 is opened; a first extendingposition 130B at which the firstbottom side passage 13a is communicated with thefirst pump passage 10a and the firstrod side passage 12a is communicated with thefirst tank passage 16; and afirst contracting position 130C at which the firstrod side passage 12a is communicated with thefirst pump passage 10a, the firstbottom side passage 13a is communicated with thefirst tank passage 16, and the firstbottom side passage 13a is communicated with the second connectingpassage 15. In the modification, the first extendingposition 130B corresponds to "the first supply position", and thefirst contracting position 130C corresponds to "the first discharge position" in the claims. - A flow-combining
control valve 160 according to the modification has: a secondneutral position 160A at which the secondneutral passage 11 is opened; a second extendingposition 160B at which the secondbottom side passage 13b is communicated with thesecond pump passage 11a, and the secondrod side passage 12b is communicated with thesecond tank passage 17; and asecond contracting position 160C at which the secondrod side passage 12b is communicated with thesecond pump passage 11a, and the second connectingpassage 15 is communicated with thesecond tank passage 17. At the secondneutral position 160A, similarly to the above-mentioned embodiment, the respective communications of the secondrod side passage 12b, the secondbottom side passage 13b, and the second connectingpassage 15 with thesecond pump passage 11a and thesecond tank passage 17 are shut off. In addition, at thesecond contracting position 160C, the communication between the secondbottom side passage 13b and thesecond tank passage 17 is shut off. In this modification, the second extendingposition 160B corresponds to "the second supply position", and thesecond contracting position 160C corresponds to "the second discharge position" in the claims. - In a case in which the hydraulic cylinder 1 is to be extended, when the flow-combining
control valve 160 is switched to the second extendingposition 160B, similarly to the above-mentioned embodiment, the working oil discharged from thesecond pump 8 is guided to the bottom-side chamber 6 through the secondbottom side passage 13b. On the other hand, in a case in which the hydraulic cylinder 1 is to be extended in the modification shown inFIG. 4 , the part of the working oil in therod side chamber 5 is guided to thesecond tank passage 17 from the secondrod side passage 12b through the flow-combiningcontrol valve 160. - In a case in which the hydraulic cylinder 1 is to be contracted, when the flow-combining
control valve 160 is switched to thesecond contracting position 160C, similarly to the above-mentioned embodiment, the working oil discharged from thesecond pump 8 is guided to therod side chamber 5 through the secondrod side passage 12b. In addition, similarly to the above-mentioned embodiment, the part of the working oil that has been discharged from the bottom-side chamber 6 is discharged to thetank 9 by being guided to thesecond tank passage 17 from theswitch valve 130 through the second connectingpassage 15 and the flow-combiningcontrol valve 160. - As described above, in the fluid
pressure control device 100 according to the modification, the secondbottom side passage 13b that is always in communication with the bottom-side chamber 6 of the hydraulic cylinder 1 is shut off from thetank 9 at both of the secondneutral position 160A and thesecond contracting position 160C. In a case in which the hydraulic cylinder 1 is to be contracted, even if the flow-combiningcontrol valve 160 is switched to thesecond contracting position 160C, the part of the working oil in the bottom-side chamber 6 is not discharged to thetank 9 through the secondbottom side passage 13b, but is discharged to thetank 9 through theswitch valve 130, the second connectingpassage 15, and the flow-combiningcontrol valve 160. Thus, similarly to the above-mentioned embodiment, the leakage of the working oil in the bottom-side chamber 6 to thetank 9 through the clearance around the outer circumference of thesecond spool 70 of the flow-combiningcontrol valve 160 is suppressed. - In the modification shown in
FIG. 4 , the present invention is applied to the control of the working oil to be supplied/discharged to/from the bottom-side chamber 6 serving as a load-side pressure chamber in the hydraulic cylinder 1 for driving the boom. In contrast, the present invention may be applied to the control of the flow of the working oil to be supplied/discharged to/from an anti-load-side pressure chamber (therod side chamber 5 in the hydraulic cylinder 1 for driving the boom). - Next, another modification will be described.
- In the above-mentioned embodiment, description has been given of the fluid
pressure control device 100 that controls the flow of the working oil to the hydraulic cylinder 1 for driving the boom as the object to be driven. In contrast, the fluidpressure control device 100 may control the flow of the working oil to the hydraulic cylinder 1 for driving other objects to be driven such as the arm, the bucket, and so forth. - In addition, the fluid
pressure control device 100 may be provided with an anti-drift valve serving as a poppet valve that prevents the working oil from being discharged to thetank 9 from the load-side pressure chamber on which the load pressure acts by shutting off the tank passage (thefirst tank passage 16, the second tank passage 17) in the load-holding state. With such a configuration, it is possible to reliably prevent the leakage of the working oil from the load-side pressure chamber by the anti-drift valve and to suppress the leakage of the working oil from the anti-load-side pressure chamber by the effect of the fluidpressure control device 100 according to the present invention. - The configurations, operations, and effects of the embodiments of the present invention will be collectively described below.
- The fluid pressure control device 100 configured to be capable of combining the working oil that has been discharged from the first pump 7 and the working oil that has been discharged from the second pump 8 and of supplying the combined working oil to the fluid pressure chamber (the rod side chamber 5, the bottom-side chamber 6) of the hydraulic cylinder 1 includes: the first pump passage 10a configured to guide the working oil discharged from the first pump 7; the second pump passage 11a configured to guide the working oil discharged from the second pump 8; the switch valve 30, 130 configured to control the flow of the working oil from the first pump 7 to the hydraulic cylinder 1; the flow-combining control valve 60, 160 configured to control the flow of the working oil supplied from the second pump 8 to the hydraulic cylinder 1; the connecting passage (the first connecting passage 14, the second connecting passage 15) configured to connect the switch valve 30, 130 and the flow-combining control valve 60, 160; the first fluid pressure passage (the first rod side passage 12a, the first bottom side passage 13a) configured such that the switch valve 30, 130 and the fluid pressure chamber (the rod side chamber 5, the bottom-side chamber 6) of the hydraulic cylinder 1 are communicated; the second fluid pressure passage (the second rod side passage 12b, the second bottom side passage 13b) configured such that the flow-combining control valve 60, 160 and the fluid pressure chamber (the rod side chamber 5, the bottom-side chamber 6) of the hydraulic cylinder 1 are communicated; the first tank passage 16 connected to the switch valve 30, 130 and communicated with the tank 9; and the second tank passage 17 connected to the flow-combining control valve 60, 160 and communicated with the tank 9, wherein the switch valve 30, 130 has: the first supply position (the first extending position 30B, 130B, the first contracting position 30C) at which the first fluid pressure passage (the first rod side passage 12a, the first bottom side passage 13a) is communicated with the first pump passage 10a; and the first discharge position (the first contracting position 30C, 130C, the first extending position 30B) at which the first fluid pressure passage (the first rod side passage 12a, the first bottom side passage 13a) is communicated with the first tank passage 16 and the first fluid pressure passage (the first rod side passage 12a, the first bottom side passage 13a) is communicated with the connecting passage (the first connecting passage 14, the second connecting passage 15), and the flow-combining control valve 60, 160 has: the second supply position (the second extending position 60B, 160B, the second contracting position 60C) at which the second fluid pressure passage (the second rod side passage 12b, the second bottom side passage 13b) is communicated with the second pump passage 11a; and the second discharge position (the second contracting position 60C, 160C, the second extending position 60B) at which the connecting passage (the first connecting passage 14, the second connecting passage 15) is communicated with the second tank passage 17, and the second fluid pressure passage (the second rod side passage 12b, the second bottom side passage 13b) is shut off from the second tank passage 17.
- In this configuration, when the
switch valve position first contracting position 30C) and the flow-combiningcontrol valve position second contracting position 60C), the working oil that has been discharged from thefirst pump 7 is guided to the first fluid pressure passage (the firstrod side passage 12a, the firstbottom side passage 13a), and the working oil discharged from thesecond pump 8 is guided to the second fluid pressure passage (the secondrod side passage 12b, the secondbottom side passage 13b). By doing so, the working oil discharged from thefirst pump 7 and the working oil discharged from thesecond pump 8 are combined, and the combined working oil is supplied to the hydraulic cylinder 1. In addition, when theswitch valve first contracting position position 30B), the working oil in the fluid pressure chamber (therod side chamber 5, the bottom-side chamber 6) of the hydraulic cylinder 1 is discharged to thetank 9 through thefirst tank passage 16. Furthermore, when the flow-combiningcontrol valve second contracting position position 60B) in a state in which theswitch valve first contracting position position 30B), the working oil in the fluid pressure chamber (therod side chamber 5, the bottom-side chamber 6) is discharged to thetank 9 through thesecond tank passage 17 by being guided to the flow-combiningcontrol valve switch valve passage 14, the second connecting passage 15). On the other hand, even when the flow-combiningcontrol valve second contracting position position 60B), the second fluid pressure passage (the secondrod side passage 12b, the secondbottom side passage 13b) is not communicated with thetank 9 and is shut off. In other words, the working oil in the fluid pressure chamber (therod side chamber 5, the bottom-side chamber 6) is not discharged to thetank 9 through the second fluid pressure passage (the secondrod side passage 12b, the secondbottom side passage 13b). As described above, because the second fluid pressure passage (the secondrod side passage 12b, the secondbottom side passage 13b) that is always in communication with the fluid pressure chamber (therod side chamber 5, the bottom-side chamber 6) of the hydraulic cylinder 1 is not configured to communicate with thetank 9 by the flow-combiningcontrol valve rod side chamber 5, the bottom-side chamber 6) to thetank 9 from the second fluid pressure passage (the secondrod side passage 12b, the secondbottom side passage 13b) through the clearance around the outer circumference of the spool (the second spool 70) of the flow-combiningcontrol valve - In addition, in the fluid pressure control device 100, the switch valve 30, 130 has: the first housing 100a; the first spool 40 received in the first spool hole 31 so as to be freely movable, the first spool hole 31 being formed in the first housing 100a; the first fluid pressure port (the first rod side port 35a, the first bottom side port 35b) configured to communicate with the first fluid pressure passage (the first rod side passage 12a, the first bottom side passage 13a) and to open to the first spool hole 31; the first tank ports 37a and 37b configured to communicate with the first tank passage 16 and to open to the first spool hole 31; the connecting ports 36a and 36b configured to communicate with the connecting passage (the first connecting passage 14, the second connecting passage 15) and to open to the first spool hole 31; the first rod side restrictor 30d and the first bottom side restrictor 30e (the notches 40a and 40b) provided in the first spool 40, the first rod side restrictor 30d and the first bottom side restrictor 30e (the notches 40a and 40b) being configured to impart the resistance to the flow of the working oil to be discharged to the tank 9 from the fluid pressure chamber (the rod side chamber 5, the bottom-side chamber 6) through the first fluid pressure passage (the first rod side passage 12a, the first bottom side passage 13a) in a state in which the switch valve 30, 130 has been switched to the first discharge position (the first contracting position 30C, 130C, the first extending position 30B), and the flow-combining control valve 60, 160 has: the second rod side restrictor 60d and the second bottom side restrictor 60e (the notch 70a, the notch 70b) provided in the second spool 70, the second rod side restrictor 60d and the second bottom side restrictor 60e (the notch 70a, the notch 70b) being configured to impart the resistance to the flow of the working oil to be discharged to the tank 9 from the fluid pressure chamber (the rod side chamber 5, the bottom-side chamber 6) through the first fluid pressure passage (the first rod side passage 12a, the first bottom side passage 13a) and connecting passage (the first connecting passage 14, the second connecting passage 15) in a state in which the flow-combining control valve 60, 160 has been switched to the second discharge position (the second contracting position 60C, 160C, the second extending position 60B), wherein, as the first spool 40 is moved in the direction in which the switch valve 30, 130 is switched to the first discharge position (the first contracting position 30C, 130C, the first extending position 30B), the communication between the first fluid pressure port (the first rod side port 35a, the first bottom side port 35b) and the connecting ports 36a and 36b is established before the establishment of the communication between the first tank ports 37a and 37b and the connecting ports 36a and 36b.
- In this configuration, along with the movement of the
first spool 40, the communication between the first fluid pressure port (the firstrod side port 35a, the firstbottom side port 35b) and the connectingports first tank ports ports rod side restrictor 30d and the firstbottom side restrictor 30e (thenotches rod side chamber 5, the bottom-side chamber 6) and thetank 9 is relaxed by the firstrod side restrictor 30d and the firstbottom side restrictor 30e (thenotches - In addition, in the fluid pressure control device 100, the flow-combining control valve 60, 160 has: the second housing 100b; the second spool 70 received in the second spool hole 61 so as to be freely movable, the second spool hole 61 being formed in the second housing 100b; and the second fluid pressure port (the second rod side port 65a, the second bottom side port 65b) configured to communicate with the second fluid pressure passage (the second rod side passage 12b, the second bottom side passage 13b) and to open to the second spool hole 61, and the flow-combining control valve 60, 160 having the second neutral position 60A, 160A at which the communication between the second tank passage 17 and the connecting passage (the first connecting passage 14, the second connecting passage 15) and the communication between the second tank passage 17 and the second fluid pressure passage (the second rod side passage 12b, the second bottom side passage 13b) are respectively shut off, the second spool 70 has the third control land parts 73a and 73b facing the second fluid pressure port (the second rod side port 65a, the second bottom side port 65b), the third control land parts 73a and 73b being configured so as to be slidably movable in the second spool hole 61, and the second fluid pressure port (the second rod side port 65a, the second bottom side port 65b) is closed by the third control land parts 73a and 73b of the second spool 70 from a state in which the flow-combining control valve 60, 160 is at the second neutral position 60A, 160A to a state in which the second spool 70 has completed the stroke in the direction in which the flow-combining control valve 60, 160 is switched to the second discharge position (the second contracting position 60C, 160C, the second extending position 60B).
- In this configuration, in the flow-combining
control valve rod side port 65a, the secondbottom side port 65b) is closed by the thirdcontrol land parts neutral position rod side port 65a, the secondbottom side port 65b) is closed by the thirdcontrol land parts control valve second contracting position position 60B) and in which thesecond spool 70 has completed the stroke. With such a configuration, the amount of thesecond spool 70 overlapped with thesecond spool hole 61 is ensured. Thus, it is possible to further suppress the leakage of the working oil in the second fluid pressure port (the secondrod side port 65a, the secondbottom side port 65b) to thetank 9 through the clearance around the outer circumference of thesecond spool 70. - Embodiments of this invention were described above, but the above embodiments are merely examples of applications of this invention, and the technical scope of this invention is not limited to the specific constitutions of the above embodiments.
- This application claims priority based on
Japanese Patent Application No.2019-55069 filed with the Japan Patent Office on March 22, 2019
Claims (3)
- A fluid pressure control device configured to combine working fluid discharged from a first pump and working fluid discharged from a second pump to supply the combined working fluid to a fluid pressure chamber of a fluid pressure actuator, the fluid pressure control device comprising:a first pump passage configured to guide the working fluid discharged from the first pump;a second pump passage configured to guide the working fluid discharged from the second pump;a first spool valve configured to control a flow of the working fluid to be supplied from the first pump to the fluid pressure actuator;a second spool valve configured to control the flow of the working fluid to be supplied from the second pump to the fluid pressure actuator;a connecting passage connecting the first spool valve and the second spool valve;a first fluid pressure passage configured to allow the first spool valve communicate with the fluid pressure chamber of the fluid pressure actuator;a second fluid pressure passage configured to allow the second spool valve communicate with the fluid pressure chamber of the fluid pressure actuator;a first tank passage connected to the first spool valve and communicated with a tank; anda second tank passage connected to the second spool valve and communicated with the tank, whereinthe first spool valve has:a first supply position at which the first fluid pressure passage is communicated with the first pump passage; anda first discharge position at which the first fluid pressure passage is communicated with the first tank passage and the first fluid pressure passage is communicated with the connecting passage, andthe second spool valve has:a second supply position at which the second fluid pressure passage is communicated with the second pump passage; anda second discharge position at which the connecting passage is communicated with the second tank passage and the second fluid pressure passage is shut off from the second tank passage.
- The fluid pressure control device according to claim 1, wherein
the first spool valve has:a first housing;a first spool received in a first spool hole so as to be freely movable, the first spool hole being formed in the first housing;a first fluid pressure port communicating with the first fluid pressure passage and opening to the first spool hole;a tank port communicating with the first tank passage and opening to the first spool hole;a connecting port communicating with the connecting passage and opening to the first spool hole;a connecting groove formed in the first spool, the connecting groove being configured such that the first fluid pressure port and the connecting port are communicated via the connecting groove along with movement of the first spool;a tank groove formed in the first spool, the tank groove being configured such that the connecting port and the tank port are communicated via the tank groove along with movement of the first spool;a land part provided between the connecting groove and the tank groove of the first spool, the land part being in sliding contact with the first spool hole; anda first discharge restrictor formed in the land part so as to communicate with the tank groove, the first discharge restrictor being configured to impart resistance to the flow of the working fluid passing through the first discharge restrictor, whereinas the first spool is moved in the direction in which the first spool valve is switched to the first discharge position, a communication between the first fluid pressure port and the connecting port is established before an establishment of a communication between the tank port and the connecting port. - The fluid pressure control device according to claim 1, wherein
the second spool valve has:a second housing;a second spool received in a second spool hole so as to be freely movable, the second spool hole being formed in the second housing; anda second fluid pressure port communicating with the second fluid pressure passage and opening to the second spool hole, the second spool valve having a neutral position at which a communication between the second tank passage and the connecting passage and a communication between the second tank passage and the second fluid pressure passage are respectively shut off,the second spool has a control land part facing the second fluid pressure port, the control land part being in sliding contact with the second spool hole, andthe second fluid pressure port is closed by the control land part of the second spool from a state in which the second spool valve is at the neutral position to a state in which the second spool has completed a stroke in a direction in which the second spool valve is switched to the second discharge position.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2019055069A JP6768106B2 (en) | 2019-03-22 | 2019-03-22 | Fluid pressure controller |
PCT/JP2020/008522 WO2020195555A1 (en) | 2019-03-22 | 2020-02-28 | Fluid pressure control device |
Publications (2)
Publication Number | Publication Date |
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EP3943755A1 true EP3943755A1 (en) | 2022-01-26 |
EP3943755A4 EP3943755A4 (en) | 2022-11-30 |
Family
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Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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EP20779689.7A Pending EP3943755A4 (en) | 2019-03-22 | 2020-02-28 | Fluid pressure control device |
Country Status (4)
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EP (1) | EP3943755A4 (en) |
JP (1) | JP6768106B2 (en) |
CN (1) | CN113614387B (en) |
WO (1) | WO2020195555A1 (en) |
Family Cites Families (13)
Publication number | Priority date | Publication date | Assignee | Title |
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JPS51130775A (en) * | 1975-05-10 | 1976-11-13 | Nippon Air Brake Co Ltd | Pressure fluid controlling system |
JP4027000B2 (en) | 1999-12-06 | 2007-12-26 | カヤバ工業株式会社 | Merge mechanism |
JP2001295803A (en) * | 2000-04-10 | 2001-10-26 | Hitachi Constr Mach Co Ltd | Hydraulic driving device for work machine |
JP4568406B2 (en) * | 2000-06-13 | 2010-10-27 | 東芝機械株式会社 | Hydraulic control device and construction machine |
JP4548959B2 (en) * | 2001-03-19 | 2010-09-22 | カヤバ工業株式会社 | Hydraulic control device |
JP5357864B2 (en) * | 2008-03-31 | 2013-12-04 | 株式会社不二越 | Hydraulic circuit for construction machinery |
JP6022461B2 (en) * | 2011-09-09 | 2016-11-09 | 住友重機械工業株式会社 | Excavator and control method of excavator |
JP6091154B2 (en) * | 2012-10-19 | 2017-03-08 | 株式会社小松製作所 | Hydraulic drive system |
CN107532407B (en) * | 2015-04-29 | 2021-03-05 | 沃尔沃建筑设备公司 | Flow rate control device for construction equipment and control method thereof |
JP2016217378A (en) * | 2015-05-15 | 2016-12-22 | 川崎重工業株式会社 | Hydraulic drive system of construction equipment |
JP6453711B2 (en) * | 2015-06-02 | 2019-01-16 | 日立建機株式会社 | Pressure oil recovery system for work machines |
WO2016195134A1 (en) * | 2015-06-03 | 2016-12-08 | 볼보 컨스트럭션 이큅먼트 에이비 | Hydraulic circuit for construction machine |
JP6836488B2 (en) | 2017-09-21 | 2021-03-03 | 京セラ株式会社 | Barometric pressure regulator, barometric pressure regulation method and barometric pressure regulation program |
-
2019
- 2019-03-22 JP JP2019055069A patent/JP6768106B2/en active Active
-
2020
- 2020-02-28 EP EP20779689.7A patent/EP3943755A4/en active Pending
- 2020-02-28 CN CN202080022823.8A patent/CN113614387B/en active Active
- 2020-02-28 WO PCT/JP2020/008522 patent/WO2020195555A1/en active Application Filing
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JP6768106B2 (en) | 2020-10-14 |
CN113614387A (en) | 2021-11-05 |
JP2020153504A (en) | 2020-09-24 |
EP3943755A4 (en) | 2022-11-30 |
CN113614387B (en) | 2023-07-25 |
WO2020195555A1 (en) | 2020-10-01 |
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