WO2023176686A1 - Dispositif de commande de pression de fluide - Google Patents

Dispositif de commande de pression de fluide Download PDF

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Publication number
WO2023176686A1
WO2023176686A1 PCT/JP2023/009047 JP2023009047W WO2023176686A1 WO 2023176686 A1 WO2023176686 A1 WO 2023176686A1 JP 2023009047 W JP2023009047 W JP 2023009047W WO 2023176686 A1 WO2023176686 A1 WO 2023176686A1
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WIPO (PCT)
Prior art keywords
pilot
pressure
chamber
valve
passage
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PCT/JP2023/009047
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English (en)
Japanese (ja)
Inventor
俊輔 久保
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Ｋｙｂ株式会社
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Application filed by Ｋｙｂ株式会社 filed Critical Ｋｙｂ株式会社
Publication of WO2023176686A1 publication Critical patent/WO2023176686A1/fr

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
    • F15B11/08—Servomotor systems without provision for follow-up action; Circuits therefor with only one servomotor

Definitions

  • the present invention relates to a fluid pressure control device.
  • Japanese Patent Application Publication No. 2010-101400 discloses a control valve that switches the supply and discharge of hydraulic oil to and from a cylinder and controls the expansion and contraction operation of the cylinder, and a load side pressure chamber of the cylinder.
  • a device is disclosed that includes a load holding mechanism interposed in a main passage connecting the control valve.
  • the load holding mechanism includes an operated check valve and a meter-out control valve that is operated by pilot pressure to switch the operation of the operated check valve.
  • the meter-out control valve includes a spool, a pilot chamber to which pilot pressure is introduced, and a piston that is slidably accommodated in the pilot chamber and receives the pilot pressure to move the spool.
  • a drain chamber that communicates with the tank is divided between the spool and the piston so that when pilot pressure is introduced into the pilot chamber, the thrust of the piston is efficiently transmitted to the spool.
  • An annular gap is provided between the piston and the housing for discharging air from the pilot chamber to the drain chamber.
  • air in the drain chamber moves to the pilot chamber through the annular gap between the piston and the housing.
  • the increase in pilot pressure in the pilot room is delayed in response to the operator's input operation due to the influence of the air that has moved to the pilot room side, and the air from the pilot room side drains through the annular gap between the piston and the housing. The increase in pilot pressure in the pilot room is completed after it is discharged into the pilot room.
  • the gas on the pilot room side causes a delay in response to operator input operations when starting the work equipment.
  • An object of the present invention is to prevent the movement of gas from the drain side to the pilot chamber side, and to suppress response delays due to the influence of the gas.
  • a fluid pressure control device for controlling the expansion and contraction operation of a cylinder that drives a load, comprising: a control valve that controls supply of working fluid to the cylinder; and a control valve that controls the supply of working fluid to the cylinder; a pilot control valve that controls pilot pressure guided to the valve; a main passage connecting the control valve and a load-side pressure chamber of the cylinder on which load pressure due to a load acts when the control valve is in a neutral position; a load holding mechanism provided in the main passage, the load holding mechanism allowing the flow of working fluid from the control valve to the load side pressure chamber, while allowing the flow of working fluid from the load side pressure chamber in accordance with back pressure.
  • the switching valve has a pilot chamber to which pilot pressure is guided through the pilot control valve, a spool that moves according to the pilot pressure of the pilot chamber, a drain passage connected to the pilot chamber, and the a gas vent valve provided in the drain passage for discharging gas from the pilot chamber to the drain side;
  • the gas vent valve includes a passage provided across the pilot chamber side and the drain side; It has a valve body that opens and closes, and a biasing member that biases the valve body, and when the pilot pressure supply source is stopped, the valve body is pushed against the first seat portion by the biasing force of the biasing member.
  • the biasing member moves against the urging force of and separates from the first sheet, allowing fluid to flow from the pilot chamber to the drain side.
  • FIG. 1 is a fluid pressure circuit diagram of a fluid pressure control device according to an embodiment of the present invention.
  • FIG. 3 is a sectional view of a load holding mechanism of a fluid pressure control device according to an embodiment of the present invention.
  • FIG. 3 is a sectional view of the area around the gas vent valve. It is a graph diagram showing the relationship between the pilot pressure in the pilot chamber and the flow rate of air flowing from the pilot chamber to the drain side.
  • FIG. 7 is a cross-sectional view of the vicinity of the gas vent valve in the load holding mechanism of the fluid pressure control device according to a modification of the embodiment of the present invention.
  • a fluid pressure control device controls the operation of hydraulic work equipment such as a hydraulic excavator.
  • a hydraulic control device 100 that controls the expansion and contraction operation of a cylinder 2 that drives an arm (load) 1 of a hydraulic excavator shown in FIGS. 1 and 2 will be described.
  • the fluid pressure control device may control the expansion and contraction operation of a lift cylinder mounted on a forklift or the like.
  • hydraulic oil is used as the working fluid of the cylinder 2
  • a water-soluble substitute liquid or the like may be used.
  • the cylinder 2 includes a cylindrical cylinder tube 2c, a piston 2d that is slidably inserted into the cylinder tube 2c and partitions the inside of the cylinder tube 2c into a rod side chamber 2a and an anti-rod side chamber 2b, and one end is connected to the piston 2d.
  • a rod 2e whose other end extends outside the cylinder tube 2c and is connected to the arm 1 is provided.
  • the hydraulic excavator is equipped with a power source such as an engine or an electric motor, and the power drives a pump 4 as a fluid pressure supply source and a pilot pump 5 as a pilot pressure supply source.
  • a power source such as an engine or an electric motor
  • the power drives a pump 4 as a fluid pressure supply source and a pilot pump 5 as a pilot pressure supply source.
  • the pilot pump 5 may be eliminated and the pump 4 may also be used as a pilot pressure supply source. That is, the pump 4 may be used as a fluid pressure supply source and a pilot pressure supply source.
  • the hydraulic control device 100 includes a control valve 6 that controls the supply of hydraulic oil from the pump 4 to the cylinder 2, and a pilot control valve 9 that controls pilot pressure guided from the pilot pump 5 to the control valve 6.
  • control valve 6 and the rod side chamber 2a of the cylinder 2 are connected by a first main passage 7, and the control valve 6 and the opposite rod side chamber 2b of the cylinder 2 are connected by a second main passage 8.
  • the control valve 6 is operated by pilot pressure guided from the pilot pump 5 to the pilot chambers 6a, 6b through the pilot control valve 9 when the operator of the hydraulic excavator manually operates the control lever 10.
  • control valve 6 has three positions: a retracted position 6A where the cylinder 2 is contracted, an extended position 6B where the cylinder 2 is extended, and a neutral position 6C where the load on the cylinder 2 is maintained. It switches the supply and discharge of hydraulic oil and controls the expansion and contraction operation of the cylinder 2.
  • a load holding mechanism 20 is provided in the first main passage 7 connected to the rod side chamber 2a, which is a load side pressure chamber.
  • the load holding mechanism 20 holds the load pressure in the rod side chamber 2a when the control valve 6 is in the neutral position 6C, and is fixed to the surface of the cylinder 2, as shown in FIG.
  • the anti-rod side chamber 15b becomes the load side pressure chamber, so when the boom 14 is provided with the load holding mechanism 20, it is connected to the anti-rod side chamber 15b.
  • a load holding mechanism 20 is provided in the main passage.
  • the load holding mechanism 20 operates in conjunction with the control valve 6 by the pilot pressure guided through the operating check valve 21 provided in the first main passage 7 and the pilot control valve 9, and switches the operation of the operating check valve 21. It has a switching valve 22.
  • the operated check valve 21 includes a valve body 24 that opens and closes the first main passage 7, a seat portion 28 on which the valve body 24 is seated, a back pressure chamber 25 facing the back side of the valve body 24, and a rod formed in the valve body 24. It has a passage 26 that always guides the hydraulic oil in the side chamber 2a to the back pressure chamber 25. The passage 26 is provided with a restriction 26a that provides resistance to the hydraulic oil passing therethrough.
  • the first main passage 7 has a cylinder side first main passage 7a that connects the rod side chamber 2a and the operated check valve 21, and a control valve side first main passage 7b that connects the operated check valve 21 and the control valve 6. .
  • the valve body 24 has a first pressure receiving surface 24a on which the pressure of the control valve side first main passage 7b acts, and a second pressure receiving surface 24b on which the pressure of the rod side chamber 2a acts through the cylinder side first main passage 7a. It is formed.
  • a spring 27 as a biasing member that biases the valve body 24 in the closing direction is housed in the back pressure chamber 25 .
  • the pressure in the back pressure chamber 25 and the biasing force of the spring 27 act in a direction to seat the valve body 24 on the seat portion 28 .
  • the operated check valve 21 functions as a check valve that blocks the flow of hydraulic oil from the rod side chamber 2a to the control valve 6. That is, the operating check valve 21 prevents leakage of the hydraulic oil in the rod side chamber 2a, maintains the load pressure, and maintains the stopped state of the arm 1.
  • the switching valve 22 includes a pilot chamber 23 to which pilot pressure is introduced through the pilot control valve 9, a spool 56 (see FIG. 3) that moves according to the pilot pressure in the pilot chamber 23, and an energizer that biases the spool 56 in the closing direction. It has a spring 36 as a biasing member, a spring chamber 54 (see FIG. 3) in which the spring 36 is housed, and a drain passage 76 connected to the pilot chamber 23 and the spring chamber 54.
  • a bypass passage 30 and a back pressure passage 31 are connected to the upstream side of the switching valve 22, and a downstream passage 38 is connected to the downstream side of the switching valve 22.
  • the bypass passage 30 is a passage for guiding the hydraulic oil in the rod side chamber 2a to the control valve side first main passage 7b, bypassing the operating check valve 21.
  • the back pressure passage 31 is a passage for guiding the hydraulic oil in the back pressure chamber 25 to the control valve side first main passage 7b.
  • the downstream passage 38 is a passage for guiding the hydraulic oil from the bypass passage 30 and the back pressure passage 31 to the control valve side first main passage 7b.
  • the switching valve 22 switches communication between the bypass passage 30 and the back pressure passage 31 with respect to the downstream passage 38, and controls the flow of hydraulic oil in the first main passage 7 which is on the meter-out side when the cylinder 2 is extended.
  • the switching valve 22 has three ports: a first supply port 32 communicating with the bypass passage 30, a second supply port 33 communicating with the back pressure passage 31, and a discharge port 34 communicating with the downstream passage 38. Moreover, the switching valve 22 has three positions: a cutoff position 22A, a first communication position 22B, and a second communication position 22C.
  • pilot pressure is introduced into the pilot chamber 6b of the control valve 6
  • pilot pressure is also introduced into the pilot chamber 23 at the same time. That is, when the control valve 6 is switched to the extended position 6B, the switching valve 22 is also switched to the first communication position 22B or the second communication position 22C.
  • the switching valve 22 When a pilot pressure equal to or higher than the first predetermined pressure and lower than the second predetermined pressure is introduced into the pilot chamber 23, the switching valve 22 is switched to the first communication position 22B.
  • the first supply port 32 communicates with the discharge port 34.
  • the hydraulic oil in the rod side chamber 2a is guided from the bypass passage 30 to the downstream passage 38 through the switching valve 22. That is, the hydraulic oil in the rod side chamber 2a bypasses the operated check valve 21 and is guided to the control valve side first main passage 7b.
  • the throttle 37 provides resistance to the flow of the hydraulic oil.
  • the second supply port 33 remains blocked.
  • the switching valve 22 When a pilot pressure equal to or higher than the second predetermined pressure is introduced into the pilot chamber 23, the switching valve 22 is switched to the second communication position 22C.
  • the first supply port 32 communicates with the discharge port 34
  • the second supply port 33 also communicates with the discharge port 34.
  • the hydraulic oil in the back pressure chamber 25 is guided from the back pressure passage 31 to the downstream passage 38 through the switching valve 22.
  • the hydraulic oil in the back pressure chamber 25 bypasses the throttle 37, is guided to the control valve side first main passage 7b, and is discharged from the control valve 6 to the tank T.
  • the load holding mechanism 20 has a relief valve 41 that opens when the pressure in the rod side chamber 2a reaches a predetermined pressure and discharges the hydraulic oil in the rod side chamber 2a to the tank T.
  • the relief valve 41 is provided in a relief passage 40 that branches from the upstream side of the switching valve 22 in the bypass passage 30 .
  • the relief passage 40 may be provided branching off from the cylinder side first main passage 7a, or may be directly connected to the rod side chamber 2a.
  • the drain passage 76 is formed by a first drain passage 76a connected to the pilot chamber 23, a second drain passage 76b connected to the spring chamber 54, and a confluence of the first drain passage 76a and the second drain passage 76b. It has a confluence drain passage 76c.
  • the combined drain passage 76c communicates with a drain port 77 that opens on the outer surface of the body 60 (see FIG. 3) of the load holding mechanism 20.
  • the drain port 77 is connected to the tank T through a drain hose 78.
  • a relief valve 43 that opens when the pressure in the control valve side first main passage 7b reaches a predetermined pressure is connected to the control valve side first main passage 7b.
  • a relief valve 44 that opens when the pressure in the second main passage 8 reaches a predetermined pressure is connected to the second main passage 8 .
  • the relief valve 43 and the relief valve 44 are for releasing the high pressure generated in the rod side chamber 2a and the anti-rod side chamber 2b of the cylinder 2, respectively, when a large external force is applied to the arm 1.
  • FIG. 3 is a sectional view of the load holding mechanism 20, showing a state in which pilot pressure is not introduced to the pilot chamber 23 and the switching valve 22 is in the cutoff position 22A.
  • components denoted by the same reference numerals as those shown in FIG. 2 have the same configurations as those shown in FIG.
  • the switching valve 22 is incorporated into the body 60 of the load holding mechanism 20.
  • a spool hole 60a is formed in the body 60, and a substantially cylindrical sleeve 61 is inserted into the spool hole 60a.
  • a spool 56 is slidably incorporated into the sleeve 61.
  • a spring chamber 54 is defined by a cap 57 on the side of one end surface 56a of the spool 56.
  • the spring chamber 54 is connected to the second drain passage 76b through a notch 61a formed in the end surface of the sleeve 61.
  • the hydraulic oil that has leaked into the spring chamber 54 is discharged to the tank T from the second drain passage 76b.
  • the spring chamber 54 includes a first annular spring receiving member 45 whose end surface abuts the one end surface 56a of the spool 56 and into which a pin portion 56c formed to protrude from the one end surface 56a of the spool 56 is inserted into the hollow portion; A second spring receiving member 46 disposed near the bottom of the cap 57 is housed.
  • the spring 36 is interposed in a compressed state between the first spring receiving member 45 and the second spring receiving member 46, and urges the spool 56 in the closing direction via the first spring receiving member 45.
  • a pilot chamber 23 is defined on the side of the other end surface 56b of the spool 56.
  • the pilot chamber 23 is defined by a pilot hole 60b formed in communication with the spool hole 60a of the body 60, a cap 58 that closes the pilot hole 60b, and the other end surface 56b of the spool 56.
  • a pilot passage 52 formed in the body 60 is connected to the pilot chamber 23, and pilot pressure oil (pilot fluid) is guided through the pilot passage 52.
  • the pilot pressure in the pilot chamber 23 acts on the other end surface 56b of the spool 56, and the spool 56 moves against the urging force of the spring 36.
  • the spool 56 stops at a position where the urging force of the spring 36 acting on one end surface 56a and the load due to the pilot pressure acting on the other end surface 56b are balanced, and the switching position of the switching valve 22 is set at the stopping position of the spool 56. Set.
  • a first drain passage 76a formed in the body 60 is also connected to the pilot chamber 23.
  • the first drain passage 76a is provided with a gas vent valve 80 for discharging air from the pilot chamber 23 to the drain side (tank T side).
  • the gas vent valve 80 blocks the flow of pilot pressure oil from the pilot chamber 23 to the drain side when the pilot pressure in the pilot chamber 23 exceeds a predetermined pressure, so that the operation of the spool 56 is not adversely affected.
  • the gas vent valve 80 will be explained in detail later. Note that in FIG. 2, illustration of the gas vent valve 80 is omitted.
  • the sleeve 61 has a first supply port 32 communicating with the bypass passage 30 (see FIG. 2), a second supply port 33 communicating with the back pressure passage 31 (see FIG. 2), and a downstream passage 38 (see FIG. 2). Three communicating discharge ports 34 are formed.
  • the outer circumferential surface of the spool 56 is partially annularly cut out, and the cutout portion and the inner circumferential surface of the sleeve 61 form a first pressure chamber 64, a second pressure chamber 65, a third pressure chamber 66, and A fourth pressure chamber 67 is formed.
  • the first pressure chamber 64 is always in communication with the discharge port 34.
  • the third pressure chamber 66 is always in communication with the first supply port 32.
  • a plurality of throttles 37 are formed on the outer peripheral surface of the land portion 72 of the spool 56 as the spool 56 moves against the biasing force of the spring 36 to communicate the third pressure chamber 66 and the second pressure chamber 65. Ru.
  • the fourth pressure chamber 67 is constantly in communication with the second pressure chamber 65 through a pressure guiding passage 68 formed in the spool 56 in the axial direction.
  • the poppet valve 70 separates from the valve seat 71 and the third pressure chamber 66 and the second pressure chamber 65 communicate with each other through the plurality of throttles 37. It communicates with the discharge port 34 through the chamber 65 and the first pressure chamber 64 . Due to the communication between the first supply port 32 and the discharge port 34, the hydraulic oil in the rod side chamber 2a is guided to the downstream passage 38 (see FIG. 2) through the throttle 37. This state corresponds to the first communication position 22B of the switching valve 22.
  • the spool 56 moves further against the urging force of the spring 36, and the fourth pressure chamber 67 communicates with the second supply port 33.
  • the second supply port 33 communicates with the discharge port 34 through the fourth pressure chamber 67, the pressure guiding passage 68, the second pressure chamber 65, and the first pressure chamber 64. Due to the communication between the second supply port 33 and the discharge port 34, the hydraulic oil in the back pressure chamber 25 is guided to the downstream passage 38 (see FIG. 2), bypassing the throttle 37. This state corresponds to the second communication position 22C of the switching valve 22.
  • the back pressure chamber 25 of the operated check valve 21 is maintained at the pressure of the rod side chamber 2a.
  • the pressure receiving area of the valve body 24 in the closing direction (the area of the back surface of the valve body 24) is larger than the area of the second pressure receiving surface 24b, which is the pressure receiving area in the opening direction. Due to the load acting on the back surface of the body 24 and the biasing force of the spring 27, the valve body 24 is placed in a seated state on the seat portion 28. In this way, the operating check valve 21 prevents the hydraulic oil from leaking in the rod side chamber 2a, and the arm 1 is maintained in a stopped state.
  • the control valve 6 When the operating lever 10 is operated and pilot pressure is guided from the pilot control valve 9 to the pilot chamber 6a of the control valve 6, the control valve 6 is switched to the retracted position 6A by an amount corresponding to the pilot pressure.
  • the discharge pressure of the pump 4 acts on the first pressure receiving surface 24a of the operating check valve 21.
  • the switching valve 22 is in the cutoff position 22A with no pilot pressure introduced into the pilot chamber 23, so the back pressure chamber 25 of the operating check valve 21 is maintained at the pressure of the rod side chamber 2a.
  • the control valve 6 When the operating lever 10 is operated and pilot pressure is guided from the pilot control valve 9 to the pilot chamber 6b of the control valve 6, the control valve 6 is switched to the extended position 6B by an amount corresponding to the pilot pressure. At the same time, pilot pressure is also guided to the pilot chamber 23, so the switching valve 22 is switched to the first communication position 22B or the second communication position 22C depending on the supplied pilot pressure.
  • the switching valve 22 When the pilot pressure guided to the pilot chamber 23 is greater than or equal to the first predetermined pressure and less than the second predetermined pressure, the switching valve 22 is switched to the first communication position 22B. In this case, since the communication between the second supply port 33 and the discharge port 34 is cut off, the back pressure chamber 25 of the operated check valve 21 is maintained at the pressure of the rod side chamber 2a, and the operated check valve 21 is closed. maintain the condition.
  • the switching valve 22 is switched to the first communication position 22B mainly when a crane operation is performed to lower the transported object attached to the bucket 13 to a target position.
  • the pilot pressure introduced into the pilot chamber 6b of the control valve 6 is small, and the control valve 6 is It is only slightly switched to the extended position 6B.
  • the pilot pressure guided to the pilot chamber 23 of the switching valve 22 is also small, being greater than or equal to the first predetermined pressure and less than the second predetermined pressure, and the switching valve 22 is only switched to the first communication position 22B. Therefore, the hydraulic oil in the rod side chamber 2a passes through the throttle 37 and is discharged, and the arm 1 descends at a low speed suitable for crane work.
  • the switching valve 22 when the switching valve 22 is in the first communication position 22B, even if the control valve side first main passage 7b ruptures and the hydraulic oil leaks to the outside, the hydraulic oil will not be discharged from the rod side chamber 2a. Since the flow rate of the hydraulic oil is restricted by the throttle 37, the falling speed of the bucket 13 is suppressed. Therefore, the switching valve 22 can be switched to the cutoff position 22A before the bucket 13 falls to the ground, and the bucket 13 can be prevented from falling suddenly.
  • the throttle 37 is intended to suppress the descending speed of the cylinder 2 when the operating check valve 21 is closed, and also to suppress the falling speed of the bucket 13 when the control valve side first main passage 7b bursts. .
  • the switching valve 22 is switched to the second communication position 22C.
  • the hydraulic oil in the back pressure chamber 25 of the operated check valve 21 is guided from the back pressure passage 31 to the downstream passage 38, bypassing the throttle 37, and is controlled. It is discharged from the valve-side first main passage 7b to the tank T through the control valve 6.
  • a pressure difference is generated before and after the throttle 26a, and the pressure in the back pressure chamber 25 is reduced, so that the force in the closing direction acting on the valve body 24 is reduced, and the valve body 24 is separated from the seat portion 28.
  • the function of the operating check valve 21 as a check valve is canceled.
  • the operating check valve 21 allows the flow of hydraulic oil from the control valve 6 to the rod side chamber 2a, while allowing the flow of hydraulic oil from the rod side chamber 2a to the control valve 6 according to the back pressure, which is the pressure in the back pressure chamber 25. Operates to allow flow of hydraulic oil.
  • the switching valve 22 is switched to the second communication position 22C when performing excavation work, etc., and the pilot pressure guided to the pilot chamber 6b of the control valve 6 is large, and the control valve 6 is switched to the extended position 6B. For this reason, the pilot pressure guided to the pilot chamber 23 of the switching valve 22 is also large and becomes equal to or higher than the second predetermined pressure, so the switching valve 22 is switched to the second communication position 22C.
  • FIG. 4 is a sectional view of the vicinity of the gas vent valve 80.
  • the gas vent valve 80 discharges air from the pilot chamber 23 to the drain chamber 51
  • what the gas vent valve 80 discharges is not limited to air, and may discharge other gases.
  • the conventional hydraulic control device had a problem in that air from the drain side moved to the pilot chamber 23 side when the hydraulic excavator stopped. Specifically, when the hydraulic excavator stops, the hydraulic oil in the pilot chamber 23 and the pilot passage 52 flows down to the tank T by gravity, so that the pilot chamber 23 and the pilot passage 52 become negative pressure, and as a result, the hydraulic oil in the pilot chamber 23 and the pilot passage 52 flows down from the tank T. The air sucked into the combined drain passage 76c and the first drain passage 76a moves to the pilot chamber 23 and the pilot passage 52. Further, the load holding mechanism 20 provided in the cylinder 2 that drives the arm 1 is provided at the highest position in the hydraulic excavator, as shown in FIG.
  • the gas vent valve 80 provided in the first drain passage 76a discharges air from the pilot chamber 23 to the drain side and blocks the flow of air from the drain side to the pilot chamber 23. . This will be explained in detail below.
  • the gas vent valve 80 includes a housing 90, a passage 81 formed in the housing 90 and provided across the pilot chamber 23 side and the drain side, a valve body 82 that opens and closes the passage 81, and a biasing member that biases the valve body 82. It has a spring 83.
  • the passage 81 is formed to extend through the housing 90 along the longitudinal direction of the first drain passage 76a.
  • the valve body 82 is a spherical body, and is provided in the middle of the passage 81.
  • the spring 83 is compressed and provided between the valve body 82 and the housing 90.
  • the passage 81 has a valve body accommodating portion 81a that accommodates the valve body 82.
  • the inner diameter of the valve body accommodating portion 81a is larger than the outer diameter of the valve body 82.
  • the inner diameter of the portion other than the valve body accommodating portion 81a is smaller than the outer diameter of the valve body 82.
  • the spring 83 has one end housed in the valve body accommodating portion 81 a and in contact with the valve body 82 , and the other end side provided outside the valve body accommodating portion 81 a and in contact with a stepped portion 90 a formed in the housing 90 .
  • the valve body housing portion 81a has an annular first seat portion 81b with which the valve body 82 contacts due to the biasing force of the spring 83, and a second seat portion 81c with which the valve body 82 contacts due to the pressure of the pilot chamber 23. , is formed.
  • the valve body 82 moves between the first seat portion 81b and the second seat portion 81c within the valve body housing portion 81a.
  • the housing 90 includes a first housing 91 that is installed in the first drain passage 76a, and a second housing 92 that is attached to the first housing 91.
  • a hole 91a is formed in the end surface of the first housing 91 facing the pilot chamber 23, and the second housing 92 is installed in the hole 91a.
  • An O-ring 99 serving as a sealing member is provided between the inner surface of the first drain passage 76a and the outer peripheral surface of the first housing 91 in order to prevent leakage of pilot pressure oil between the two.
  • the first housing 91 may be press-fitted into the first drain passage 76a.
  • an O-ring 98 as a sealing member is provided between the outer circumferential surface of the second housing 92 and the inner circumferential surface of the hole 91a in order to prevent leakage of pilot pressure oil between the two.
  • the second housing 92 may be press-fitted into the hole 91a.
  • the first housing 91 may be formed integrally with the body 60.
  • the second housing 92 is formed with a small diameter hole 92a communicating with the pilot chamber 23 side, and a large diameter hole 92b communicating with the small diameter hole 92a and having a larger inner diameter than the small diameter hole 92a.
  • the small diameter hole 92a and the large diameter hole 92b constitute a part of the passage 81.
  • the large diameter hole 92b defines the valve body housing portion 81a.
  • the step portion formed between the small diameter hole 92a and the large diameter hole 92b constitutes the first seat portion 81b.
  • the opening edge of the passage 81 formed on the bottom surface of the hole 91a constitutes a second seat portion 81c.
  • FIG. 5 is a graph diagram showing the relationship between the pilot pressure in the pilot chamber 23 and the flow rate of air flowing from the pilot chamber 23 to the drain side.
  • the pilot pressure oil discharged from the pilot pump 5 is discharged into the tank T through the pilot control valve 9 and into the pilot chamber 23. There is almost no guidance. However, even in such a state, when the pilot pump 5 is driven, the pilot passage 52 and the pilot chamber 23 have a minimum pilot pressure, specifically, a pilot pressure of about 0.05 to 0.2 MPa. acts. In this state, the valve body 82 moves against the biasing force of the spring 83 and separates from the first seat portion 81b, but does not contact the second seat portion 81c.
  • valve body 82 is located between the first seat portion 81b and the second seat portion 81c due to the balance between the pilot pressure in the pilot chamber 23 and the biasing force of the spring 83.
  • This state is when the pilot pressure in the pilot chamber 23 is less than a predetermined pressure. In this state, as shown in FIG. 5, air is allowed to flow from the pilot chamber 23 to the drain side through the passage 81, and air from the pilot chamber 23 side is discharged to the drain side. Therefore, when the hydraulic excavator is started from a stopped state, the air in the pilot chamber 23 side is naturally discharged to the drain side before the operator operates the operating lever 10. When starting, the response delay of the cylinder 2 to the operation is suppressed.
  • a pilot pressure of 0.3 MPa or more acts on the pilot chamber 23.
  • the valve body 82 moves against the biasing force of the spring 83 and comes into contact with the second seat portion 81c.
  • This state is when the pilot pressure in the pilot chamber 23 is equal to or higher than a predetermined pressure.
  • the flow of air from the pilot chamber 23 to the drain side through the passage 81 is blocked, and the flow of pilot pressure oil is also blocked. Therefore, a desired pilot pressure acts on the pilot chamber 23, and the movement of the piston 50 allows the spool 56 to move, so the passage 81 does not adversely affect the operation of the cylinder 2.
  • the predetermined pressure which is the pilot pressure at which the valve body 82 contacts the second seat portion 81c, is set to a pressure lower than the pilot pressure at which the spool 56 moves, and is approximately 0.3 PMa in this embodiment.
  • This predetermined pressure is set according to the capacity of the pilot pump 5, the inner diameter and length of the pilot passage 52, and the like.
  • the initial load of the spring 83 is set so that the valve body 82 contacts the second seat portion 81c at a pressure equal to or higher than the set predetermined pressure.
  • the gas vent valve 80 prevents air from moving from the drain side to the pilot chamber 23 side when the pilot pump 5 is stopped, and before the operator operates the control lever 10 when the pilot pump 5 is activated. In addition, since the air in the pilot chamber 23 side is naturally discharged to the drain side, a delay in response of the cylinder 2 to an input operation by the operator is suppressed. Furthermore, when the operator operates the operating lever 10, the flow of pilot pressure oil from the pilot chamber 23 to the drain side is blocked, so the gas vent valve 80 may adversely affect the operation of the switching valve 22 and the cylinder 2. There isn't.
  • the operator may operate the control lever 10 to bleed air from the pilot chamber 23 to the drain side through the passage 81.
  • the pilot pressure in the pilot chamber 23 does not exceed 0.3 MPa.
  • the valve body 82 of the gas vent valve 80 comes into contact with the first seat portion 81b and blocks the passage 81 due to the biasing force of the spring 83, so that air does not move from the drain side to the pilot chamber 23 side. is prevented. Furthermore, when the pilot pump 5 is driven and the pilot pressure in the pilot chamber 23 is less than a predetermined pressure, the valve body 82 moves against the biasing force of the spring 83 and separates from the first seat portion 81b. Since air is allowed to flow from the pilot chamber 23 to the drain side, the air from the pilot chamber 23 side is discharged to the drain side, and response delay of the cylinder 2 due to the influence of air is suppressed.
  • FIG. 6 is a diagram corresponding to FIG. 4, and is a sectional view of the vicinity of the gas vent valve 80.
  • components having the same functions as those in the above embodiment are denoted by the same reference numerals.
  • the configuration of the gas vent valve 80 is different from the above embodiment.
  • the valve body 82 moves against the biasing force of the spring 83, but the second seat portion 81c (see FIG. 4), and does not block the flow of pilot pressure oil from the pilot chamber 23 to the drain side through the passage 81.
  • the entire spring 83 is accommodated in the valve body accommodating portion 81a. Specifically, the spring 83 is compressed and provided between the valve body 82 and the bottom surface of the hole 91a formed in the first housing 91.
  • the valve body 82 does not come into contact with the second seat portion 81c (see FIG. 4). Allow pilot pressure oil to flow to the drain side.
  • the gas vent valve 80 has an orifice 85 that is provided in the passage 81 and serves as a throttle that provides resistance to the flow of pilot pressure oil from the pilot chamber 23 to the drain side. Therefore, when the operator operates the control lever 10, the orifice 85 provides resistance to the flow of pilot pressure oil from the pilot chamber 23 to the drain side, and the desired pilot pressure acts on the pilot chamber 23, so that the gas The vent valve 80 does not adversely affect the operation of the cylinder 2.
  • the orifice 85 is formed in the second housing 92.
  • the orifice 85 only needs to be provided in the passage 81, and the position where it is formed is not limited.
  • an orifice 85 may be provided in the passage 81 of the first housing 91.
  • the pilot chamber 23 is not provided with a piston.
  • a piston (not shown) may be slidably accommodated in the pilot chamber 23.
  • the pilot chamber 23 is defined between the cap 58 and the piston, and the drain chamber is defined between the piston and the spool 56.
  • the piston receives pilot pressure in the pilot chamber 23 and applies thrust to the spool 56 against the biasing force of the spring 36 .
  • the air in the pilot chamber 23 is distributed between the outer circumferential surface of the piston and the inner circumferential surface of the pilot hole 60b. After flowing through the gap, it is discharged from the gas vent valve 80 to the drain side.
  • a hydraulic control device 100 that controls the expansion and contraction operation of the cylinder 2 that drives the load 1 includes a control valve 6 that controls the supply of working fluid from the pump 4 (fluid pressure supply source) to the cylinder 2; A pilot control valve 9 that controls the pilot pressure guided from the pilot pump 5 (pilot pressure supply source) to the control valve 6, and the load side of the cylinder 2 on which the load pressure from the load 1 acts when the control valve 6 is in the neutral position 6C.
  • the load holding mechanism 20 includes a main passage 7 that connects the pressure chamber 2a and the control valve 6, and a load holding mechanism 20 provided in the main passage 7.
  • an operating check valve 21 that allows the flow of working fluid from the load-side pressure chamber 2a to the control valve 6 according to the back pressure, and a pilot pressure led through the pilot control valve 9 to control the control valve 6 and the control valve 6. It has a switching valve 22 that operates in conjunction with the operating check valve 21 to switch the operation of the operating check valve 21.
  • a spool 56 that moves according to pressure, a first drain passage 76a (drain passage) connected to the pilot chamber 23, and a drain passage provided in the first drain passage 76a to discharge air (gas) from the pilot chamber 23 to the drain side.
  • the gas vent valve 80 includes a passage 81 provided across the pilot chamber 23 side and the drain side, a valve body 82 that opens and closes the passage 81, and a valve body 82 that energizes the valve body 82.
  • the valve body 82 comes into contact with the first seat portion 81b by the urging force of the spring 83 to block the passage 81, and when the pilot pump 5 stops, the valve body 82
  • the pilot chamber 23 is driven and the pilot pressure in the pilot chamber 23 is less than a predetermined pressure lower than the pilot pressure at which the spool 56 moves, the spool 56 moves against the biasing force of the spring 83 and moves away from the first seat portion 81b. This allows fluid to flow from the pilot chamber 23 to the drain side.
  • a gas vent valve 80 for discharging air from the pilot chamber 23 to the drain side is provided in the first drain passage 76a, and the valve body 82 of the gas vent valve 80 is pressed against the spring 83 when the pilot pump 5 is stopped. Since the biasing force contacts the first seat portion 81b and blocks the passage 81, movement of air from the drain side to the pilot chamber 23 side is prevented. Furthermore, when the pilot pump 5 is driven and the pilot pressure in the pilot chamber 23 is less than a predetermined pressure, the valve body 82 moves against the biasing force of the spring 83 and separates from the first seat portion 81b.
  • valve body 82 moves against the biasing force of the spring 83 and comes into contact with the second seat portion 81c. This blocks the passage 81 and blocks the flow of pilot pressure oil from the pilot chamber 23 to the drain side.
  • valve body 82 controls the flow of pilot pressure oil from the pilot chamber 23 to the drain side through the passage 81 when the pilot pressure in the pilot chamber 23 is higher than a predetermined pressure when the pilot pump 5 is driven. Therefore, the gas vent valve 80 does not adversely affect the operation of the cylinder 2.
  • valve body 82 allows pilot pressure oil to flow from the pilot chamber 23 to the drain side even if the pilot pressure in the pilot chamber 23 is higher than the predetermined pressure, and the gas vent valve 80 allows the pilot pressure oil to flow from the pilot chamber 23 to the drain side. It further includes an orifice 85 (restriction) that is provided in the pilot chamber 23 and provides resistance to the flow of pilot pressure oil from the pilot chamber 23 to the drain side.
  • the orifice 85 provides resistance to the flow of pilot pressure oil from the pilot chamber 23 to the drain side. Therefore, the gas vent valve 80 does not adversely affect the operation of the cylinder 2.

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Fluid-Pressure Circuits (AREA)

Abstract

L'invention concerne un mécanisme de maintien de charge (20) comportant une vanne de commutation (22) qui commute le fonctionnement d'un clapet anti-retour de fonctionnement (21). La vanne de commutation (22) est disposée dans un premier passage de drain (76a) relié à une chambre pilote (23) et a une soupape de libération de gaz (80) pour évacuer le gaz de la chambre pilote (23) vers le côté drain. La soupape de libération de gaz (80) comporte un corps de soupape (82) qui ouvre et ferme un passage (81). Lorsqu'une source d'alimentation en pression pilote (5) est arrêtée, le corps de soupape (82) est mis en contact avec une première partie siège (81b) par une force de sollicitation d'un élément de sollicitation (83) et bloque le passage (81). Lorsque la source d'alimentation en pression pilote (5) est activée et qu'une pression pilote de la chambre pilote (23) est inférieure à une pression prédéterminée inférieure à une pression pilote à laquelle se déplace une bobine (56), le corps de soupape (82) se déplace à l'encontre de la force de sollicitation de l'élément de sollicitation (83) et se sépare de la première partie siège (81b) pour permettre l'écoulement d'un fluide de la chambre pilote (23) vers le côté drain.
PCT/JP2023/009047 2022-03-16 2023-03-09 Dispositif de commande de pression de fluide WO2023176686A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2022-041677 2022-03-16
JP2022041677 2022-03-16

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH05187416A (ja) * 1991-06-20 1993-07-27 Linde Ag 液圧的な装置のためのエア抜き装置
JP2002317802A (ja) * 2001-04-20 2002-10-31 Shin Caterpillar Mitsubishi Ltd パイロット操作制御弁のエア抜き構造
JP2019027504A (ja) * 2017-07-28 2019-02-21 Ｋｙｂ株式会社 流体圧制御装置

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH05187416A (ja) * 1991-06-20 1993-07-27 Linde Ag 液圧的な装置のためのエア抜き装置
JP2002317802A (ja) * 2001-04-20 2002-10-31 Shin Caterpillar Mitsubishi Ltd パイロット操作制御弁のエア抜き構造
JP2019027504A (ja) * 2017-07-28 2019-02-21 Ｋｙｂ株式会社 流体圧制御装置

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