Directional Control Valve

Abstract

To provide a directional control valve capable of restricting the supply amount of working liquid to a specified liquid hydraulic actuator without using a priority valve.SOLUTION: A directional control valve 1 includes a housing 2 including a spool hole, a pump flow path 3, a tank flow path 4, and a pair of supply and discharge flow paths 5A, 5B, and a spool 6 inserted into the spool hole. The spool 6 shuts off the supply and discharge flow paths 5A, 5B from the pump flow path 3 and the tank flow path 4 at a neutral position, respectively, and communicates one of the supply and discharge flow paths 5A, 5B with the pump flow path 3 and communicates the other with the tank flow path 4 when moved from the neutral position. An opening area between one of the supply and discharge flow paths 5A, 5B and the pump flow path 3 is increased up to the maximum value during a time when the stroke of the spool 6 is increased up to a predetermined value, and becomes smaller than the maximum value when the stroke of the spool 6 exceeds the predetermined value.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a directional control valve provided in a hydraulic circuit. [Background technology]

[0002] A directional control valve for switching the operating direction of a hydraulic actuator (e.g., a double-acting cylinder, a hydraulic motor, etc.) that operates in both directions has been known. This directional control valve includes a housing that includes a spool hole and a spool inserted into the spool hole.

[0003] In a hydraulic circuit including multiple hydraulic actuators, multiple directional control valves may be connected in parallel to a pump. In such a hydraulic circuit, when a combined operation is performed to simultaneously operate multiple hydraulic actuators, a priority valve, which is a variable throttle, may be provided upstream of the directional control valve corresponding to that hydraulic actuator in order to limit the amount of hydraulic fluid supplied to that specific hydraulic actuator (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 8-302751 Summary of the Invention [Problem to be solved by the invention]

[0005] For the above-mentioned combined operation, there is a demand for limiting the amount of hydraulic fluid supplied to a specific hydraulic actuator without using a priority valve.

[0006] Therefore, an object of the present disclosure is to provide a directional control valve that can limit the amount of hydraulic fluid supplied to a specific hydraulic actuator without using a priority valve. [Means for solving the problem]

[0007] The present disclosure provides a directional control valve comprising: a housing including a spool hole, a pump flow path, a tank flow path, and a pair of supply and discharge flow paths; and a spool inserted into the spool hole, which, in a neutral position, blocks the pair of supply and discharge flow paths from the pump flow path and the tank flow path, and which, when moved from the neutral position, connects one of the pair of supply and discharge flow paths to the pump flow path and the other to the tank flow path, wherein an opening area between one of the pair of supply and discharge flow paths and the pump flow path increases to a maximum value while the stroke of the spool increases to a predetermined value, and becomes smaller than the maximum value when the stroke of the spool exceeds the predetermined value. [Effects of the Invention]

[0008] According to the present disclosure, a directional control valve is provided that can limit the amount of hydraulic fluid supplied to a specific hydraulic actuator without using a priority valve. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 2 is a diagram illustrating a hydraulic circuit including a directional control valve according to an embodiment. [Figure 2] 4 is a graph showing the relationship between a spool stroke and an opening area in the directional control valve. [Figure 3] 4 is a cross-sectional view of a portion of the directional control valve, showing a state in which the spool is in a neutral position. FIG. [Figure 4] 4 is a cross-sectional view of a portion of the directional control valve, showing a state in which a spool stroke is at a predetermined value. FIG. [Figure 5] 4 is a cross-sectional view of a portion of the directional control valve, showing a state in which the spool stroke is at its maximum. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0010] 1 shows a hydraulic circuit including a directional control valve 1 according to one embodiment. The hydraulic circuit also includes another directional control valve 93.

[0011] The directional control valve 1 is used to switch the operating direction of a bidirectional hydraulic actuator 92, and the directional control valve 93 is used to switch the operating direction of a bidirectional hydraulic actuator 96. For example, the hydraulic actuators 92 and 96 are double-acting cylinders, hydraulic motors, etc.

[0012] The directional control valve 1 includes a housing 2 that includes a spool hole 20 (see FIG. 3) and a spool 6 that is inserted into the spool hole 20. Similarly, the directional control valve 93 includes a housing 94 that also includes a spool hole and a spool 95 that is inserted into the spool hole. The housings 2 and 94 of both directional control valves 1 and 93 may be integrated.

[0013] The directional control valve 1 is connected to a pump 91 in parallel with the directional control valve 93 by a supply line 15, and is also connected to a tank in parallel with the directional control valve 93 by a tank line 16. The directional control valve 1 is also connected to a hydraulic actuator 92 by a pair of supply and discharge lines 17.

[0014] In addition to a spool hole 20, the housing 2 includes a pump flow path 3, a tank flow path 4, and a pair of supply and discharge flow paths 5A and 5B. The pump flow path 3 forms a pump port 11 on the surface of the housing 2, and a supply line 15 is connected to this pump port 11. The tank flow path 4 forms a tank port 12 on the surface of the housing 2, and a tank line 16 is connected to this tank port 12. The supply and discharge flow paths 5A and 5B form supply and discharge ports 13 on the surface of the housing 2, and supply and discharge lines 17 are respectively connected to these supply and discharge ports 13.

[0015] In addition, when the housings 2, 94 of both directional control valves 1, 93 are integrated, instead of the supply line 15 and the tank line 16 branching off, the pump flow path 3 and the tank flow path 4 may branch off within the housings 2, 94, so that the directional control valves 1, 93 are connected to the pump 91 in parallel.

[0016] In the neutral position, the spool 6 blocks the supply and discharge flow paths 5A, 5B from the pump flow path 3 and the tank flow path 4, and when moved from the neutral position to one side and the other, it connects one of the supply and discharge flow paths 5A, 5B to the pump flow path 3 and the other to the tank flow path 4.

[0017] 2, the opening area of ​​the meter-in between one of the supply / discharge flow paths 5A, 5B and the pump flow path 3 increases to a maximum value β while the stroke of the spool 6 increases to a predetermined value α, and becomes smaller than the maximum value β when the stroke of the spool 6 exceeds the predetermined value α. Note that the percentage of the opening area of ​​the meter-in at the full stroke of the spool 6 relative to the maximum value β can be determined appropriately depending on the priority of hydraulic actuator 96 relative to hydraulic actuator 92 when hydraulic actuators 92, 96 are operated simultaneously.

[0018] Furthermore, in this embodiment, the opening area of ​​the meter-out between the other of the supply and discharge flow paths 5A, 5B and the tank flow path 4 increases to a maximum value γ while the stroke of the spool 6 increases to a predetermined value α, and is maintained at the maximum value γ when the stroke of the spool 6 exceeds the predetermined value α.

[0019] 3, a central annular groove 21 recessed radially outward from the spool hole 20 is formed in the housing 2 at the center of the spool hole 20, and a pair of inlet annular grooves 22, 23 recessed radially outward from the spool hole 20 are formed on both sides of the central annular groove 21. The pump flow path 3 includes a main flow path that forms the pump port 11 and a plurality of branch paths 31 branching from the main flow path, and the branch paths 31 are connected to the inlet annular grooves 22, 23, respectively.

[0020] In addition, a pair of intermediate annular grooves 24, 25 are formed on the housing 2 outside the inlet annular groove 22, recessed radially outward from the spool hole 20, and a pair of outlet annular grooves 26, 27 are formed on the housing 2 outside the intermediate annular grooves 24, 25, recessed radially outward from the spool hole 20.

[0021] The supply and discharge flow paths 5A and 5B are connected to the intermediate annular grooves 24 and 25, respectively. The tank flow path 4 includes a main flow path that forms the tank port 12 and a plurality of branch paths 41 that branch off from the main flow path, and the branch paths 41 are connected to the outflow annular grooves 26 and 27, respectively.

[0022] Meanwhile, the spool 6 includes a central land portion 61 located between the inlet annular grooves 22 and 23 when the spool 6 is in the neutral position, a pair of supply / discharge lands 64 and 65 located on both sides of the central land portion 61, and a pair of end lands 68 and 69 located outside the supply / discharge lands 64 and 65. The spool 6 also includes a pair of inner small diameter portions 62 and 63 connecting the central land portion 61 and the supply / discharge lands 64 and 65, respectively, and a pair of outer small diameter portions 66 and 67 connecting the supply / discharge lands 64 and 65 and the end lands 68 and 69, respectively.

[0023] In this embodiment, an annular groove 61C is formed in the center of the central land portion 61, dividing the central land portion 61 into a first central land portion 61A and a second central land portion 61B. However, the central land portion 61 may be continuous from one end to the other without forming the annular groove 61C. The supply / discharge lands 64 and 65 close the intermediate annular grooves 24 and 25, respectively, when the spool 6 is in the neutral position.

[0024] Annular flow paths 81, 82 are formed between the inner small diameter portions 62, 63 and the inner surface of the spool hole 20, respectively, and annular flow paths 83, 84 are formed between the outer small diameter portions 66, 67 and the inner surface of the spool hole 20, respectively.

[0025] A plurality of notches 71 opening toward the annular flow passage 81 are formed on the circumferential surface of the first central land portion 61A, and a plurality of notches 72 opening toward the annular flow passage 82 are formed on the circumferential surface of the second central land portion 61B. When the spool 6 is in the neutral position, the annular flow passage 81 overlaps with the inlet annular groove 22, and the annular flow passage 82 overlaps with the inlet annular groove 23.

[0026] The inner end of the circumferential surface of the supply / discharge land portion 64 is formed with a plurality of notches 73 that open toward the annular flow passage 81, and the outer end is formed with a plurality of notches 75 that open toward the annular flow passage 83. The annular flow passage 83 always overlaps with the annular outlet groove 26 regardless of the position of the spool 6.

[0027] Similarly, the inner end of the circumferential surface of the supply / discharge land portion 65 is formed with a plurality of notches 74 that open toward the annular flow passage 82, and the outer end is formed with a plurality of notches 76 that open toward the annular flow passage 84. The annular flow passage 84 always overlaps with the outflow annular groove 27 regardless of the position of the spool 6.

[0028] When the spool 6 moves to one side (leftward in FIG. 3 ) from the neutral position, the annular flow passage 81 communicates with the intermediate annular groove 24 via the notch 73, and the annular flow passage 84 communicates with the intermediate annular groove 25 via the notch 76, as shown in FIG. 4 . As a result, the working fluid flows from the branch passage 31 of the pump flow passage 3 to the supply / discharge flow passage 5A through the inlet annular groove 22, the annular flow passage 81, the notch 73, and the intermediate annular groove 24, and also flows from the supply / discharge flow passage 5B to the branch passage 41 of the tank flow passage 4 through the intermediate annular groove 25, the notch 76, the annular flow passage 84, and the outlet annular groove 27.

[0029] On the meter-in side, from the time when communication between the notch 73 and the intermediate annular groove 24 begins until the stroke of the spool 6 reaches a predetermined value α, the intermediate annular groove 24 and the annular flow passage 81 always communicate with each other via the notch 73. Therefore, the maximum value β of the opening area of ​​the meter-in is the total cross-sectional area of ​​the notch 73 on a plane perpendicular to the axial direction of the spool 6.

[0030] 5, when the stroke of the spool 6 exceeds the predetermined value α, the first central land portion 61A is positioned to cover the annular inlet groove 22. Before the first central land portion 61A covers the annular inlet groove 22, the annular inlet groove 22 is in direct communication with the annular flow passage 81. However, once the first central land portion 61A is positioned to cover the annular inlet groove 22, the annular inlet groove 22 is in communication with the annular flow passage 81 through the notch 71. As a result, the opening area of ​​the meter-in decreases from the maximum value β to the total cross-sectional area of ​​the notch 71 on a plane perpendicular to the axial direction of the spool 6.

[0031] On the meter-out side, from the time when communication between the notch 76 and the intermediate annular groove 25 begins until the stroke of the spool 6 reaches its maximum, the intermediate annular groove 25 and the annular flow passage 84 always communicate with each other via the notch 76. Therefore, the maximum value γ of the meter-out opening area is the total cross-sectional area of ​​the notch 76 on a plane perpendicular to the axial direction of the spool 6, and is maintained at the maximum value γ until the stroke of the spool 6 reaches its maximum from a predetermined value α or a value smaller than this.

[0032] The operation when the spool 6 moves from the neutral position to the other side (to the right in FIG. 3) is the same as the operation described above except for the direction, so a description thereof will be omitted.

[0033] As described above, in the directional control valve 1 of this embodiment, when a combined operation is performed to simultaneously operate the hydraulic actuators 92, 96, the amount of hydraulic fluid supplied to the hydraulic actuator 92 can be limited by making the stroke of the spool 6 of the directional control valve 1 greater than the predetermined value α. Moreover, in this embodiment, when limiting the amount of hydraulic fluid supplied to the hydraulic actuator 92, the opening area of ​​the meter-out can be maintained at the maximum value γ. In other words, the amount of hydraulic fluid supplied to the hydraulic actuator 92 can be limited without reducing the opening area of ​​the meter-out.

[0034] For example, if the hydraulic circuit is a hydraulic circuit for construction machinery such as a hydraulic excavator, the directional control valve 1 may be a swing direction control valve for a swing motor, and the directional control valve 93 may be a boom direction control valve for a boom cylinder. In this case, when a combined operation of swinging and boom raising is performed, if the spool stroke of the directional control valve 1 is made larger than the predetermined value α, priority is given to the supply of hydraulic fluid to the boom cylinder over the supply of hydraulic fluid to the swing motor, and the boom raising speed can be ensured.

[0035] (Variation) The present disclosure is not limited to the above-described embodiments, and various modifications are possible without departing from the gist of the present disclosure.

[0036] For example, the opening area of ​​the meter-out of the directional control valve 1 may become smaller than the maximum value γ when the stroke of the spool 6 exceeds a predetermined value α.

[0037] (summary) The present disclosure provides a directional control valve comprising: a housing including a spool hole, a pump flow path, a tank flow path, and a pair of supply and discharge flow paths; and a spool inserted into the spool hole, which, in a neutral position, blocks the pair of supply and discharge flow paths from the pump flow path and the tank flow path, and which, when moved from the neutral position, connects one of the pair of supply and discharge flow paths to the pump flow path and the other to the tank flow path, wherein an opening area between one of the pair of supply and discharge flow paths and the pump flow path increases to a maximum value while the stroke of the spool increases to a predetermined value, and becomes smaller than the maximum value when the stroke of the spool exceeds the predetermined value.

[0038] When the above-mentioned directional control valve is connected to a pump in parallel with another directional control valve and a combined operation is performed, the amount of hydraulic fluid supplied to the specific hydraulic actuator corresponding to the above-mentioned directional control valve can be limited by making the stroke of the spool of the above-mentioned directional control valve larger than the predetermined value.

[0039] The opening area between the other of the pair of supply / discharge passages and the tank passage may increase to a maximum value while the stroke of the spool increases to the predetermined value, and may be maintained at the maximum value when the stroke of the spool exceeds the predetermined value. With this configuration, the opening area of ​​the meter-out can be maintained at the maximum value when limiting the amount of hydraulic fluid supplied to a specific hydraulic actuator.

[0040] For example, the housing includes a pair of inlet annular grooves recessed radially outward from the spool hole, a pair of intermediate annular grooves recessed radially outward from the spool hole outside the pair of inlet annular grooves, and a pair of outlet annular grooves recessed radially outward from the spool hole outside the pair of intermediate annular grooves, the pump flow path is connected to the pair of inlet annular grooves, the pair of supply and discharge flow paths are connected to the pair of intermediate annular grooves, respectively, and the tank flow path is connected to the pair of outlet annular grooves, the spool has a central land portion located between the pair of inlet annular grooves when the spool is located at the neutral position, and the spool has a central land portion located between the pair of inlet annular grooves when the spool is located at the neutral position. The spool may include a pair of supply / discharge land portions that respectively block the pair of intermediate annular grooves when the spool is positioned at the neutral position, and a pair of small diameter portions that respectively connect the central land portion and the pair of supply / discharge land portions, and an annular flow path that communicates with the corresponding intermediate annular groove when the spool moves from the neutral position is formed between each of the pair of small diameter portions and the inner surface of the spool hole, and when the stroke of the spool exceeds the predetermined value, the central land portion is positioned to cover one of the pair of inlet annular grooves, and the inlet annular groove communicates with the annular flow path through a notch formed on the peripheral surface of the central land portion. [Explanation of symbols]

[0041] 1. Directional control valve 2. Housing 20 spool holes 22,23 Inlet annular groove 24,25 Intermediate annular groove 26,27 Outlet annular groove 3 Pump flow path 4 Tank flow path 5A,5B Supply / discharge channel 6 spools 61 Central Land Section 62,63 Inner small diameter section 64,65 Supply and discharge land section 66,67 Outer small diameter section 68,69 End land 71-76 notches 81~84 Annular flow path

Claims

1. a housing including a spool bore, a pump passage, a tank passage, and a pair of supply and discharge passages; a spool that is inserted into the spool hole and that, at a neutral position, blocks the pair of supply and discharge passages from the pump passage and the tank passage, and that, when moved from the neutral position, connects one of the pair of supply and discharge passages to the pump passage and connects the other of the pair of supply and discharge passages to the tank passage, the housing includes a pair of annular inlet grooves recessed radially outward from the spool hole and connected to the pump flow paths, and a pair of intermediate annular grooves recessed radially outward from the spool hole outside the pair of annular inlet grooves and connected to the pair of supply and discharge flow paths, a directional control valve, the spool including a central land portion located between the pair of inlet annular grooves when the spool is located at the neutral position, and a pair of supply / discharge land portions that respectively close the pair of intermediate annular grooves when the spool is located at the neutral position, wherein an opening area between one of the pair of supply / discharge flow paths and the pump flow path increases to a maximum value via notches formed on the circumferential surfaces of the pair of supply / discharge land portions while the stroke of the spool increases to a predetermined value, and becomes smaller than the maximum value via notches formed on the circumferential surface of the central land portion when the stroke of the spool exceeds the predetermined value.

2. 2. The directional control valve according to claim 1, wherein an opening area between the other of the pair of supply / discharge passages and the tank passage increases to a maximum value while the stroke of the spool increases to the predetermined value, and is maintained at the maximum value when the stroke of the spool exceeds the predetermined value.

3. A housing including a spool hole, a pump flow path, a tank flow path, and a pair of supply and discharge flow paths; a spool that is inserted into the spool hole and that, at a neutral position, blocks the pair of supply and discharge passages from the pump passage and the tank passage, and that, when moved from the neutral position, connects one of the pair of supply and discharge passages to the pump passage and connects the other of the pair of supply and discharge passages to the tank passage, the housing includes a pair of annular inlet grooves recessed radially outward from the spool hole, a pair of intermediate annular grooves recessed radially outward from the spool hole outside the pair of annular inlet grooves, and a pair of annular outlet grooves recessed radially outward from the spool hole outside the pair of intermediate annular grooves, the pump flow path is connected to the pair of inflow annular grooves, the pair of supply and discharge flow paths are connected to the pair of intermediate annular grooves, respectively, and the tank flow path is connected to the pair of outflow annular grooves; the spool includes a central land portion located between the pair of inlet annular grooves when the spool is located at the neutral position, a pair of supply / discharge land portions that close the pair of intermediate annular grooves when the spool is located at the neutral position, and a pair of small diameter portions that connect the central land portion to the pair of supply / discharge land portions, an annular flow passage is formed between each of the pair of small diameter portions and an inner circumferential surface of the spool hole, the annular flow passage communicating with the corresponding intermediate annular groove when the spool moves from the neutral position; an opening area between one of the pair of supply and discharge flow paths and the pump flow path increases to a maximum value while the stroke of the spool increases to a predetermined value, and becomes smaller than the maximum value when the stroke of the spool exceeds the predetermined value; a directional control valve in which, when the stroke of the spool exceeds the predetermined value, the central land portion is positioned to cover one of the pair of annular inlet grooves, and the annular inlet groove communicates with the annular flow path through a notch formed in the circumferential surface of the central land portion.

4. A directional control valve as described in claim 3, wherein the opening area between the other of the pair of supply and discharge flow paths and the tank flow path increases to a maximum value while the stroke of the spool increases to the predetermined value, and is maintained at the maximum value when the stroke of the spool exceeds the predetermined value.

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