HYDRAULIC VALVE AND HYDRAULIC CIRCUIT

Abstract

A flow rate control valve 40 is provided that changes the opening area of ​​a meter passage portion 63f with respect to a meter port 41 in conjunction with the movement of a spool 62, and performs flow rate control of oil from the meter port 41 to a drain port 42 through a main passage portion 63 to perform precise flow rate control while maintaining the rigidity of the spool. The main passage portion 63 of the spool 62 includes a meter portion 63b in which the meter passage portion 63f is provided, a drain portion 63d in which a drain passage portion 63g is provided, and a tapered portion 63c connecting the meter portion 63b and the drain portion 63d.An inner diameter of the measuring device portion 63b is formed larger than that of the drain portion 63d, and the tapered portion 63c is formed in a tapered shape in which an inner diameter gradually decreases toward the drain portion 63d.

Description

Area

[0001] The present invention relates to a hydraulic valve including a control piston in a valve main body and a hydraulic circuit. background

[0002] Many hydraulic valves of this type are provided with a groove portion in an outer periphery of a spool (see, for example, Patent Literature 1). Since the spool in this hydraulic valve moves in an axial direction with respect to a valve main body, there is a problem that the hydraulic valve is easily affected by flow force. That is, when a port of the valve main body starts to open due to the movement of the spool, oil flows in an oblique direction. Therefore, there is a possibility that flow force is generated in a direction in which the spool closes the port, and a problem such as difficulty in precise flow rate control may arise.

[0003] To reduce such an influence of the flow force, an oil passage is provided inside the spool. That is, in this hydraulic valve, a main passage is provided in the axial direction inside the spool, and a sub-passage is provided in a radial direction so as to open from the main passage to an outer peripheral surface of the spool, thereby reducing the flow force (see, for example, Patent Literature 2). Citation listPatent literature Patent Literature 1: Japanese Patent Application Laid-Open No. 2020-20446 Patent Literature 2: Japanese Patent Application Laid-Open No. 2007-107677 SummaryTechnical problem

[0004] Incidentally, for precise flow rate control, it is advantageous to open a large number of independent sub-passages in an outer peripheral surface of a spool. To provide the large number of sub-passages in the spool, it is necessary to enlarge the inner diameter of the main passage due to a processing problem. However, in the spool with the inner diameter of the main passage enlarged, it is difficult to ensure sufficient rigidity, and there is a concern that deformation such as bending will be caused in a case where a large hydraulic pressure is applied.

[0005] In view of the above circumstances, it is an object of the present invention to provide a hydraulic valve and a hydraulic circuit capable of precisely performing flow rate control while ensuring the rigidity of a control piston. Solution to the problem

[0006] To achieve the object, a hydraulic valve according to the present invention includes: a valve main body having a first port and a second port that are independent of each other; and a spool disposed so as to be movable along an axial center with respect to the valve main body. Further, the spool is provided with a main passage portion provided at an axial center portion, a first passage portion provided between the main passage portion and an outer peripheral surface and connectable to the first port, and a second passage portion provided between the main passage portion and the outer peripheral surface and connectable to the second port.wherein an opening area of ​​the first passage portion with respect to the first port is changed along with the movement of the spool, and flow rate control of oil from the first port to the second port is performed through the main passage portion, and the main passage portion of the spool has a first region in which the first passage portion is provided, a second region in which the second passage portion is provided, and a third region connecting the first region and the second region, wherein an inner diameter of the first region is formed larger than that of the second region, and the third region is formed in a tapered shape in which an inner diameter gradually decreases toward the second region. Advantageous effects of the invention

[0007] According to the present invention, since only a first region constituting a first passage portion in a spool has a large diameter, it is possible to reduce the influence of the flow force without causing a problem with the rigidity of the spool. Furthermore, since a third region in which the inner diameter gradually decreases is provided between the first region and a second region, even if air bubbles are generated in the oil flowing from a first port into a main passage portion, the oil smoothly flows through the third region, reaches the second region without being deflected to one side of the first region, and is discharged toward a second port.Thus, there is no possibility of air bubbles accumulating in the first region or reaching a land portion of a valve main body through the first passage portion, and there is no possibility of erosion occurring in the land portion of the valve main body. Consequently, a position of the spool can be accurately controlled, and precise flow rate control becomes possible. Brief description of the drawings Fig. 1 is a circuit diagram illustrating a hydraulic circuit in which a hydraulic valve according to an embodiment of the present invention is applied. Fig. 2 is a view illustrating a state in which a hydraulic cylinder performs an extension operation in the Fig. 1 illustrated circuit diagram. Fig. 3 is a view illustrating a state in which the hydraulic cylinder performs a retraction operation in the Fig. 1 illustrated circuit diagram. Fig. 4 is a cross-sectional view illustrating the structure of the hydraulic valve used in the Fig. 1 illustrated circuit diagram. Fig. 5 is an enlarged cross-sectional view of a main portion of the Fig. 4 illustrated hydraulic valve. Description of the embodiments

[0008] In the following, a preferred embodiment of a hydraulic valve and a hydraulic circuit according to the present invention will be described in detail with reference to the accompanying drawings.

[0009] Fig. 1 to Fig. 3 are views illustrating a hydraulic circuit according to an embodiment of the present invention. The hydraulic circuit described here as an example is to operate a hydraulic cylinder 1 by supplying oil from a hydraulic pump. The hydraulic cylinder 1 is of a single-rod double-action type having a single piston 2. In the present embodiment, the hydraulic cylinder 1 for operating a boom 3 in a work machine is described as an example. In the work machine, an upper swing body 5 is arranged in an upper portion of a lower traveling body 4 so as to be rotatable about a swing axis in an up-down direction, and the boom 3 is provided in the upper swing body 5. The boom 3 is rotatably supported in the upper swing body 5 via a base end portion by a boom support shaft in the horizontal direction.In the drawing, reference numeral 6 denotes an arm provided at a front end portion of the boom 3, and reference numeral 7 denotes a bucket provided at a leading end portion of the arm.

[0010] The hydraulic cylinder 1 is connected to the upper swing body 5 via a cylinder body 8 and coupled to the boom 3 via a rod 9. The front end portion of the boom 3 moves upward with respect to the upper swing body 5 when the hydraulic cylinder 1 performs the extension operation, and the front end portion of the boom 3 moves downward with respect to the upper swing body 5 in a case where the hydraulic cylinder 1 performs the retraction operation. In the hydraulic cylinder 1, a bottom oil passage 11 is connected to a bottom chamber 1a, and a rod oil passage 12 is connected to a rod chamber 1b. The bottom oil passage 11 is branched along its course into a first bottom oil passage 11A and a second bottom oil passage (metering device oil passage) 11B. Similarly, the rod oil passage 12 branches along its course into a first rod oil passage 12A and a second rod oil passage 12B.

[0011] The hydraulic circuit includes a hydraulic pump 20, a directional control valve 30 for operating the hydraulic cylinder 1, and a flow rate control valve (hydraulic valve) 40.

[0012] The hydraulic pump 20 is a variable displacement pump driven by a motor (not shown). A pump oil passage 22 with a check valve 21 is connected to a discharge port of the hydraulic pump 20.

[0013] The directional switching valve 30 is operated by pilot pressure from an operating valve (not illustrated) and is configured to switch the connection states of a pump port 33 and a tank port 34 with respect to a first input / output port 31 and a second input / output port 32. More specifically, in a case where the directional switching valve 30 is in a Fig. 1, each of the two input / output ports 31 and 32, the pump port 33, and the tank port 34 is in a closed state. When the directional switching valve 30 is moved to the left from this state and in an extended position, as shown in Fig. 2, the first input / output port 31 is connected to the pump port 33 and the second input / output port 32 is connected to the tank port 34. On the other hand, when the directional switching valve 30 is moved from the neutral position to the right and is arranged in a retracted position, as shown in Fig. 3, the first input / output port 31 is connected to the tank port 34, and the second input / output port 32 is connected to the pump port 33. In the directional switching valve 30, the first bottom oil passage 11A is connected to the first input / output port 31, and the first rod oil passage 12A is connected to the second input / output port 32. The pump oil passage 22 is connected to the pump port 33, and a tank oil passage 51 leading to an oil tank 50 is connected to the tank port 34.

[0014] The flow rate control valve 40 is operated by pilot pressure from an operating valve (not illustrated) and is configured to switch the connection states of a drain port (second port) 42 and a regeneration port 43 with respect to a meter-out port (first port) 41. Specifically, when the flow rate control valve 40 is disposed in a closed position illustrated in the drawing, all of the meter-out port 41, the drain port 42, and the regeneration port 43 are in the shut-off state. When the flow rate control valve 40 is moved to the left from this state and is in the control position illustrated in the drawing, the meter-out port 41 is connected to the drain port 42 and the regeneration port 43.A meter-out throttle 44 is disposed between the meter port 41 and the drain port 42 and the regeneration port 43 so that an opening area increases as the pilot pressure applied by the operating valve (not illustrated) increases. A drain-side fixed throttle 45 is provided downstream of the meter throttle 44 between the meter port 41 and the drain port 42. A check valve 46 and a regeneration-side fixed throttle 47 are provided downstream of the meter throttle 44 between the meter port 41 and the regeneration port 43. In the flow rate control valve 40, the second bottom oil passage 11B is connected to the meter port 41, and the tank oil passage 51 is connected to the drain port 42. The second rod oil passage 12B is connected to the regeneration port 43.

[0015] Fig. 4 and Fig. 5 are views illustrating a specific configuration of the flow rate control valve 40. The configuration of the flow rate control valve 40 will be described below with reference to Fig. 4 and Fig. 5 in detail, and characteristic portions of the present invention will be described together. As can be seen from the drawings, the flow rate control valve 40 includes a valve main body 60 configured in a block shape. The valve main body 60 is provided with a spool hole 61 and is provided with the above-described metering device port 41, the drain port 42, and the regeneration port 43 so as to communicate with the spool hole 61. The spool hole 61 is a through hole having a circular cross section and a linear axial center, and includes a spool 62 therein. The spool 62 is a columnar member having an outer diameter fitted to the spool hole 61 and is arranged in the valve main body 60 in a state of being movable along the axial center of the spool hole 61.Although not clearly illustrated in the drawing, a return spring 48 (see ) is provided between an end portion of the control piston 62 and the valve main body 60. Fig. 1) which moves the control piston 62 to the right in relation to the valve main body 60 in Fig. 4 and holds the control piston 62 in a normal position, and there is a pressure chamber 49 (see Fig. 1) is provided, to which the pilot pressure is supplied from the actuating valve (not shown). The pressure chamber 49 serves to move the control piston 62 against the spring force of the return spring 48 to the left side in Fig. 4 in a case where the pilot pressure is supplied from the operating valve (not illustrated) to place the directional switching valve 30 in the retracted position. The metering device port 41, the drain port 42, and the regeneration port 43 are configured to have portions surrounding a periphery of the spool hole 61 and are provided at positions separated from each other in the axial center direction of the spool 62. In the illustrated example, the drain port 42 and the regeneration port 43 are each provided in portions on both sides of the metering device port 41.

[0016] The spool 62 is provided with a main passage portion 63. The main passage portion 63 is a through hole formed in an axial center portion of the spool 62 and includes a reference portion 63a, a metering device portion (first portion) 63b, a tapered portion (third portion) 63c, a drain portion (second portion) 63d, and a valve portion 63e. The reference portion 63a is a void with a circular cross section and is configured to have a constant inner diameter.

[0017] The measuring device area 63b is a void with a constant inner diameter and a circular cross-section, which is Fig. 4 is provided adjacent to the right side of the reference portion 63a. The inner diameter of the meter portion 63b is larger than that of the reference portion 63a. A meter passage portion (first passage portion) 63f, which constitutes the above-described meter throttle 44, is formed in the meter portion 63b. The meter passage portion 63f is a through hole with a circular cross section formed in the radial direction of the spool 62, and a plurality of meter passage portions 63f with different cross-sectional areas are formed so as to be juxtaposed in the circumferential direction and the axial center direction.In a case where the spool 62 is disposed in the normal position, the meter passage portions 63f are completely covered by a land portion 60a located between the meter port 41 and the drain port 42 in the valve main body 60. On the other hand, when the spool 62 moves to the left side with respect to the valve main body 60, the meter passage portions 63f open toward the meter port 41 and function to gradually increase the opening area between the main passage portion 63 and the meter port 41.

[0018] The tapered portion 63c is a space provided adjacent to the right side of the gauge portion 63b and formed in a tapered shape in which the inner diameter gradually decreases toward the right side. The inner diameter of the tapered portion 63c decreases at a constant rate, and an inner peripheral surface extends linearly in a cross section including the axial center. In the shown example, the tapered portion 63c is formed such that the inclination angle θ with respect to the gauge portion 63b is 21°. The inclination angle θ of the tapered portion 63c is preferably in a range of 15 to 30°. In other words, the rate at which the inner diameter decreases toward the right side toward the axial center is preferably in a range of tan 15° to tan 30°.The inner diameter of a portion located on the rightmost side of the tapered portion 63c is set to be larger than that of the reference portion 63a and smaller than that of the measuring device portion 63b.

[0019] The bleed portion 63d is a circular cross-sectional space with a constant inner diameter provided on the right side of the tapered portion 63c. The inner diameter of the bleed portion 63d is the same as that of the smallest diameter portion of the tapered portion 63c. The bleed portion 63d is provided with a bleed passage portion (second passage portion) 63g to form the above-described bleed-side fixed throttle 45. The bleed passage portion 63g is a through hole with a circular cross-section formed in the radial direction of the spool 62, with a plurality of bleed passage portions 63g formed at equal intervals in the circumferential direction.These drain passage portions 63g are provided to constantly communicate with the drain port 42 from a state where the spool 62 is located in the normal position to a state where the spool 62 moves to the left side and the meter passage portions 63f are all open to the meter port 41. A plug 64 is attached to a portion of the main passage portion 63 located on the right side of the drain area 63d.

[0020] The valve portion 63e is a circular-sectioned void provided adjacent to a portion on the left side of the reference portion 63a. The valve portion 63e houses a valve body 65 and a return spring 66 that constitute the above-described check valve 46, and a regeneration passage portion 63h that constitutes the above-described regeneration-side fixed throttle 47. The valve body 65 prevents the oil from flowing between the reference portion 63a and the valve portion 63e in a case where it abuts against a valve seat portion 63i provided therebetween, and allows the oil to flow therebetween in a case where it moves to the left side and is separated from the valve seat portion 63i.The return spring 66 is disposed between a plug 67 attached to a portion of the main passage portion 63 located on the left side of the valve area 63e and the valve body 65, and biases the valve body 65 to constantly abut against the valve seat portion 63i. The regeneration passage portion 63h is a through hole with a circular cross section formed in the radial direction of the spool 62, with a plurality of regeneration passage portions 63h formed at equal intervals in the circumferential direction.

[0021] In the hydraulic circuit arranged in the above manner, when the operating valve (not illustrated) is operated so that the front end portion of the boom 3 is raised, as shown in Fig. 2, the directional switching valve 30 is arranged in the extended position in a state where the flow rate control valve 40 is arranged in the normal position. As a result, the oil discharged from the hydraulic pump 20 is supplied to the lower chamber 1a of the hydraulic cylinder 1 through the pump oil passage 22 and the bottom oil passage 11. As a result, the hydraulic cylinder 1 performs the extension operation, and the front end portion of the boom 3 moves upward.

[0022] On the other hand, when the operating valve (not illustrated) is operated so that the front end portion of the boom 3 is lowered as shown in Fig.3, the directional switching valve 30 is arranged in the retracted position, the spool 62 of the flow rate control valve 40 moves to the left side with respect to the valve main body 60, and the opening area of ​​the meter passage portions 63f (meter throttle 44) changes according to the pilot pressure applied from the operating valve (not illustrated). As a result, a part of the oil discharged from the bottom oil passage 11 flows through the second bottom oil passage 11B through the flow rate control valve 40, a flow rate of the oil to the oil tank 50 is restricted by the meter throttle 44, and a part of the oil flowing through the flow rate control valve 40 is regenerated into the rod chamber 1b of the hydraulic cylinder 1 through the check valve 46, the regeneration passage portion 63h (regeneration-side fixed throttle 47), and the second rod oil passage 12B.By adjusting the opening area of ​​the meter passage portions 63f in the flow rate control valve 40, a speed at which the hydraulic cylinder 1 contracts against the weight of the boom 3, the arm 6, and the bucket 7 can be controlled.

[0023] During this time, according to the above-described flow rate control valve 40, the oil flows in the radial direction through the meter passage portions 63f provided in the spool 62. In this way, the influence of the flow force generated when the oil in the second bottom oil passage 11B flows into the main passage portion 63 of the spool 62 can be reduced, and the opening area of ​​the meter passage portions 63f can be accurately adjusted. In addition, since the meter portion 63b in which the meter passage portions 63f are formed is formed with a large inner diameter, a large number of meter passage portions 63f can be formed without interfering with each other.Furthermore, since only the metering device portion 63b in the spool 62 is a large inner diameter portion, even when a large hydraulic pressure is applied, there is no possibility of causing problems such as bending. As a result, the flow rate control of the oil flowing through the flow rate control valve 40 can be accurately and precisely controlled, and the operability of the boom 3 in the working machine can be improved.

[0024] Incidentally, when the oil flows from the second bottom oil passage 11B into the main passage portion 63 of the spool 62, the pressure is reduced, and air bubbles are generated in the oil. When the air bubbles collapse into the meter passage portions 63f closed by the land portion 60a of the valve main body 60, they cause erosion in the land portion 60a, and there is a concern that the tightness between the spool 62 and the valve main body 60 will be affected. However, in the flow rate control valve 40 described above, since the tapered portion 63c is provided between the meter portion 63b and the drain portion 63d so that the inner diameter is gradually decreased, the oil flows smoothly downstream without being deflected in the main passage portion 63.Thus, the air bubbles generated in the oil in the metering device portion 63b move to the tapered portion 63c and the drain portion 63d, are discharged to the outside from the drain passage portions 63g, and there is no possibility of the air bubbles accumulating in the metering device portion 63b or the metering device passage portions 63f. As a result, erosion can be prevented from occurring in the land portion 60a of the valve main body 60, and there is no possibility of the sealing between the spool 62 and the valve main body 60 being impaired.

[0025] Although the hydraulic cylinder for operating the boom of the work machine was described as an example in the above-described embodiment, the present invention is not limited thereto. In this case, the first port need not be a meter port, and the second port need not be a drain port. Moreover, although a tapered portion whose inner diameter decreases at a constant rate is described as an example of the third region, a tapered portion may be curved in a protruding shape at a rate of inner diameter decrease from the first region to the second region, or may be configured to be curved in a recessed shape. List of reference symbols 1 hydraulic cylinder 1a Floor Chamber 11B SECOND SOIL OIL PASSAGE 40 FLOW RATE CONTROL VALVE 41 MEASURING DEVICE CONNECTION 42 DRAIN CONNECTION 50 OIL TANK 51 TANK OIL PASSAGE 60 VALVE MAIN BODY 62 CONTROL PISTON 63 MAIN THROUGH SECTION 63b MEASURING DEVICE AREA 63c Tapered area 63d DRAINAGE AREA 63f MEASURING DEVICE PASSAGE SECTION 63g drain passage section QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] JP 2020-20446

[0003] JP 2007-107677

[0003]

Claims

[1] Hydraulic valve, comprising: a valve main body having a first port and a second port which are independent of each other; and a control piston arranged to be movable along an axial center with respect to the valve main body, wherein the control piston is provided with a main passage portion provided in an axial central portion, a first passage portion provided between the main passage portion and an outer peripheral surface and connectable to the first port, and a second passage portion provided between the main passage portion and the outer peripheral surface and connectable to the second port an opening area of the first passage portion with respect to the first port is changed along with the movement of the control piston, and a flow rate control of oil from the first port to the second port through the main passage portion is performed, and the main passage portion of the control piston has a first region in which the first passage portion is provided, a second region in which the second passage portion is provided, and a third region connecting the first region and the second region, wherein an inner diameter of the first region is formed larger than that of the second region and the third region is formed in a tapered shape in which an inner diameter gradually decreases toward the second region. [2] A hydraulic valve according to claim 1, wherein the inner diameter of the third region decreases at a constant rate from the first region to the second region. [3] A hydraulic valve according to claim 2, wherein in the third region, the rate at which the inner diameter decreases with respect to a length in an axial center direction of the main passage portion is in a range of tan 15° to tan 30°. [4] A hydraulic circuit, wherein a metering device oil passage communicating with a bottom chamber of a hydraulic cylinder is connected to the first port of the hydraulic valve according to any one of claims 1 to 3, and a tank oil passage communicating with an oil tank is connected to the second port.

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