Hydraulic control device

Abstract

This suppresses the complexity of the structure required to move the valve body of the control valve. [Solution] The hydraulic control device 40 includes a first supply / discharge passage 46 and a second supply / discharge passage 48, a first oil passage 58A connecting the first supply / discharge passage 46 and a hydraulic actuator, a fourth oil passage 58D connecting the second supply / discharge passage 48 and a hydraulic actuator, a second oil passage 58B and a third oil passage 58C connected to the hydraulic actuator, and a control valve 56 having a valve body. The valve body is displaceable between a first position in which the first supply / discharge passage 46 and the second oil passage 58B are in communication and the second supply / discharge passage 48 and the third oil passage 58C are in communication, and a second position in which communication between the first supply / discharge passage 46 and the second oil passage 58B, and communication between the second supply / discharge passage 48 and the third oil passage 58C are blocked, and the second oil passage 58B and the third oil passage 58C are in communication.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a hydraulic control device. BACKGROUND ART

[0002] The hydraulic control device described in Patent Document 1 includes a control valve. The control valve switches the supply state of hydraulic oil to a hydraulic actuator by moving a valve element between a first position and a second position. PRIOR ART DOCUMENT PATENT DOCUMENT

[0003] Patent Document 1 Japanese Unexamined Patent Publication No. 2022-30106 SUMMARY OF THE INVENTION PROBLEM TO BE SOLVED BY THE INVENTION

[0004] In the hydraulic control device as described above, the structure for moving the valve element between the first position and the second position may be complicated. MEANS FOR SOLVING THE PROBLEM

[0005] A hydraulic control device according to one aspect of the present disclosure includes a first supply / discharge passage and a second supply / discharge passage, a first oil passage connecting the first supply / discharge passage and a hydraulic actuator, a fourth oil passage connecting the second supply / discharge passage and the hydraulic actuator, a second oil passage and a third oil passage connected to the hydraulic actuator, and a control valve having a valve element. The valve element is displaceable between: a first position where the first supply / discharge passage communicates with the second oil passage and the second supply / discharge passage communicates with the third oil passage; and a second position where communication between the first supply / discharge passage and the second oil passage and communication between the second supply / discharge passage and the third oil passage are each blocked, and the second oil passage and the third oil passage communicate with each other.

[0006] According to the above configuration, when the valve body of the control valve is in the first position, hydraulic fluid is supplied to and discharged from the hydraulic actuator through the first and fourth oil passages and the second and third oil passages. When the valve body is in the second position, the second oil passage, the hydraulic actuator, and the third oil passage form a closed hydraulic circuit, so no hydraulic fluid is supplied to or discharged from the hydraulic actuator through the second and third oil passages. When the valve body is in the second position, the same amount of hydraulic fluid that is discharged from the hydraulic actuator to the second and third oil passages is returned to the hydraulic actuator through the second and third oil passages. Therefore, when the valve body is in the second position, the operating speed of the output member of the hydraulic actuator is faster and the output taken from the output member is smaller compared to when the valve body is in the first position. Thus, by making the second oil passage, the hydraulic actuator, and the third oil passage form a closed hydraulic circuit, the supply state of hydraulic fluid to the hydraulic actuator, and consequently the operating state of the hydraulic actuator, can be switched in two stages.

[0007] In the hydraulic control device, the first oil passage, the second oil passage, the third oil passage, and the fourth oil passage may be connected to a hydraulic motor which serves as the hydraulic actuator. The hydraulic control device further includes an oil supply passage for replenishing hydraulic fluid to the second oil passage and the third oil passage, wherein the oil supply passage is connected to the control valve, and the first position is a position in which the valve body blocks communication between the oil supply passage and the second oil passage and the third oil passage, and the second position may be a position in which the oil supply passage communicates with the second oil passage and the third oil passage.

[0008] The hydraulic control device may further include a high-pressure selector valve that connects the passage with high hydraulic fluid pressure among the first supply / discharge passage and the second supply / discharge passage to the oil replenishment passage, and blocks communication between the passage with low hydraulic fluid pressure among the first supply / discharge passage and the oil replenishment passage.

[0009] In a hydraulic control device, the control valve has an operating pressure chamber into which hydraulic fluid is introduced from the oil supply passage, and the valve body may be displaceable from the second position to the first position by the pressure in the operating pressure chamber.

[0010] In a hydraulic control device, the control valve may include a cylinder having a first end and a second end, with a spool as the valve body positioned between the first and second ends; a pilot chamber located at the first end that pushes the spool toward the second position by pilot pressure; and a spring located at the second end that pushes the spool toward the first position.

[0011] The hydraulic control device further comprises a high-pressure passage and a high-pressure selector valve that connects the high-pressure passage to the passage with high hydraulic fluid pressure among the first supply / discharge passage and the second supply / discharge passage, and blocks communication between the high-pressure passage and the passage with low hydraulic fluid pressure among the first supply / discharge passage and the second supply / discharge passage, wherein the control valve has an operating pressure chamber that communicates with the high-pressure passage, and the spool has a pressure-receiving surface that defines the operating pressure chamber and faces the second end side, and may be displaceable from the second position to the first position by the pressure of the hydraulic fluid acting on the pressure-receiving surface.

[0012] In a hydraulic control device, the operating pressure chamber extends through the interior of the spool in the axial direction of the spool and has an open end that opens to the second end and a closed end that serves as the pressure receiving surface, and the support member may further include a support member that is inserted into the open end and supports the spool so that it can move in the axial direction.

[0013] In a hydraulic control device, the spool has a large-diameter portion and a small-diameter portion having a smaller diameter than the large-diameter portion, the pressure-receiving surface extends radially outward from the outer circumferential surface of the small-diameter portion and connects the outer circumferential surface of the large-diameter portion and the outer circumferential surface of the small-diameter portion, the cylinder has a first contact surface and a second contact surface that contact the outer circumferential surface of the large-diameter portion and the outer circumferential surface of the small-diameter portion, respectively, and a connecting surface that connects the first contact surface and the second contact surface, and the operating pressure chamber may be defined by the pressure-receiving surface, the outer circumferential surface of the small-diameter portion, and the connecting surface.

[0014] In a hydraulic control device, the large-diameter portion may be the end of the spool having a pilot surface on which the pilot pressure of the pilot chamber acts. In a hydraulic control device, the spool has a large-diameter portion and a small-diameter portion having a smaller diameter than the large-diameter portion, the pressure-receiving surface extends radially outward from the outer circumferential surface of the small-diameter portion and connects the outer circumferential surface of the small-diameter portion and the outer circumferential surface of the large-diameter portion, the cylinder has a guide member located at the second end and having an insertion hole into which the small-diameter portion is inserted, and the operating pressure chamber may be defined by the pressure-receiving surface, the outer circumferential surface of the small-diameter portion, and the end face of the guide member on the first end side.

[0015] In a hydraulic control device, the spool has a first land, a second land, a third land, a first groove located between the first and second lands, and a second groove located between the second and third lands, and the cylinder has a first annular groove communicating with the first supply and discharge passage, a second annular groove communicating with the second oil passage, a third annular groove communicating with the third oil passage, and a fourth annular groove communicating with the second supply and discharge passage, and the first position is where the first groove The first annular groove and the second annular groove are positioned such that the second groove connects the third annular groove and the fourth annular groove, respectively, and the second land blocks the connection between the second annular groove and the third annular groove. The second position may be a position where the first land and the second land block the connection between the first annular groove and the second annular groove and the connection between the third annular groove and the fourth annular groove, respectively, and the first groove connects the second annular groove and the third annular groove. [Effects of the Invention]

[0016] This can suppress the structural complexity of hydraulic control devices. [Brief explanation of the drawing]

[0017] [Figure 1] Figure 1 shows the configuration of one embodiment of the hydraulic circuit structure of a hydraulic control device. [Figure 2] Figure 2 is a schematic end view of a hydraulic motor. [Figure 3] Figure 3 is an end view schematically representing the flow channel. [Figure 4] Figure 4 is a schematic end view of the inlet and outlet plates. [Figure 5] Figure 5 is a schematic end view of the hydraulic control device. [Figure 6] Figure 6 is an enlarged view of the control valve when the valve body is in the first position. [Figure 7] Figure 7 is an enlarged view of the control valve when the valve body is in the second position. [Figure 8] Figure 8 is an enlarged view of the control valve in the second embodiment. [Figure 9] FIG. 9 is an enlarged view of the control valve according to the third embodiment. [Figure 10] FIG. 10 is an enlarged view of a control valve according to a modified example. [Figure 11] FIG. 11 is a diagram showing a modified example of the hydraulic circuit structure of the hydraulic control apparatus. MODE FOR CARRYING OUT THE INVENTION

[0018] Hereinafter, embodiments of the hydraulic control apparatus of the present disclosure will be described with reference to the accompanying drawings. To simplify and clarify the description, components illustrated in the drawings are not necessarily drawn to a uniform scale. The accompanying drawings merely illustrate embodiments of the present disclosure, and should not be construed as limiting the present disclosure.

[0019] The following detailed description includes apparatuses, systems, and methods embodying exemplary embodiments of the present disclosure. This detailed description is intended for illustrative purposes only, and is not intended to limit the embodiments of the present disclosure or the application and use of such embodiments.

[0020] <First Embodiment> (Hydraulic Circuit Structure) Referring to FIG. 1, the hydraulic circuit structure 200 of the hydraulic control apparatus 40 according to the present embodiment will be described.

[0021] As shown in FIG. 1, the hydraulic circuit structure 200 includes a hydraulic actuator and a hydraulic control apparatus 40. An example of the hydraulic actuator is a hydraulic motor 10. The hydraulic motor 10 will be described later.

[0022] The hydraulic control device 40 includes a first supply / discharge port 42, a second supply / discharge port 44, a first supply / discharge passage 46, and a second supply / discharge passage 48. The first supply / discharge port 42 can be connected to either a pump that supplies hydraulic fluid to the hydraulic circuit structure 200 or a tank from which hydraulic fluid is discharged from the hydraulic circuit structure 200. The second supply / discharge port 44 can be connected to either the pump that supplies hydraulic fluid to the hydraulic circuit structure 200 or the tank from which hydraulic fluid is discharged from the hydraulic circuit structure 200, the one to which the first supply / discharge passage 46 is not connected. In detail, the first supply / discharge port 42 and the second supply / discharge port 44 are connected to the pump and the tank via a flow path switching valve (not shown). When the flow path switching valve is in the first position, the first supply / discharge port 42 and the second supply / discharge port 44 are connected to the pump and the tank, respectively. When the flow path switching valve is in the second position, the first supply / discharge port 42 and the second supply / discharge port 44 are connected to the tank and the pump, respectively. The first supply / exhaust passage 46 is connected to the first supply / exhaust port 42. The second supply / exhaust passage 48 is connected to the second supply / exhaust port 44.

[0023] The hydraulic control device 40 includes a directional valve 50 and a high-pressure selector valve 52. The hydraulic control device 40 also includes a high-pressure passage 54. The directional valve 50 is located in the first supply / discharge passage 46 and the second supply / discharge passage 48. The high-pressure selector valve 52 is connected to the first supply / discharge passage 46 and the second supply / discharge passage 48. The high-pressure passage 54 is connected to the high-pressure selector valve 52.

[0024] The directional valve 50 can be switched to a first position, a second position, and a third position. When the directional valve 50 is in the first position, the movement of hydraulic fluid in the first supply / discharge passage 46 in the direction from the hydraulic motor 10 toward the first supply / discharge port 42 is restricted. Also, when the directional valve 50 is in the first position, the movement of hydraulic fluid in the first supply / discharge passage 46 in the direction from the first supply / discharge port 42 toward the hydraulic motor 10 is permitted. That is, when the directional valve 50 is in the first position, the first supply / discharge passage 46 is through which hydraulic fluid supplied to the hydraulic motor 10 flows. When the directional valve 50 is in the first position, the second supply / discharge passage 48 is through which hydraulic fluid discharged from the hydraulic motor 10 flows.

[0025] When the directional valve 50 is in the second position, the movement of hydraulic fluid in the first supply / discharge passage 46 in the direction from the hydraulic motor 10 toward the first supply / discharge port 42 is restricted. Also, when the directional valve 50 is in the second position, the first supply / discharge passage 46 allows the movement of hydraulic fluid in the direction from the first supply / discharge port 42 toward the hydraulic motor 10. When the directional valve 50 is in the second position, the movement of hydraulic fluid in the second supply / discharge passage 48 in the direction from the hydraulic motor 10 toward the second supply / discharge port 44 is restricted. Also, when the directional valve 50 is in the second position, the second supply / discharge passage 48 allows the movement of hydraulic fluid in the direction from the second supply / discharge port 44 toward the hydraulic motor 10.

[0026] When the directional valve 50 is in the third position, the movement of hydraulic fluid in the second supply / discharge passage 48 in the direction from the hydraulic motor 10 toward the second supply / discharge port 44 is restricted. Also, when the directional valve 50 is in the third position, the movement of hydraulic fluid in the second supply / discharge passage 48 in the direction from the second supply / discharge port 44 toward the hydraulic motor 10 is permitted. In other words, when the directional valve 50 is in the third position, the second supply / discharge passage 48 is through which the hydraulic fluid supplied to the hydraulic motor 10 flows. When the directional valve 50 is in the third position, the first supply / discharge passage 46 is through which the hydraulic fluid discharged from the hydraulic motor 10 flows.

[0027] The directional valve 50 moves to the first position when the first supply / exhaust passage 46 is under high pressure. The directional valve 50 also moves to the third position when the second supply / exhaust passage 48 is under high pressure. When the directional valve 50 moves from the first position to the third position, it first moves from the first position to the second position, and then from the second position to the third position. Similarly, when the directional valve 50 moves from the third position to the first position, it first moves from the third position to the second position, and then from the second position to the first position.

[0028] The high-pressure selector valve 52 connects the high-pressure passage 54 with the passage with higher hydraulic fluid pressure among the first supply / discharge passage 46 and the second supply / discharge passage 48. Conversely, the high-pressure selector valve 52 blocks the connection between the high-pressure passage 54 and the passage with lower hydraulic fluid pressure among the first supply / discharge passage 46 and the second supply / discharge passage 48. In other words, hydraulic fluid is supplied to the high-pressure passage 54 from the passage with higher pressure among the first supply / discharge passage 46 and the second supply / discharge passage 48.

[0029] The hydraulic circuit structure 200 includes a control valve 56. The hydraulic circuit structure 200 also includes a first oil passage 58A, a second oil passage 58B, a third oil passage 58C, and a fourth oil passage 58D. One end of the first oil passage 58A, the second oil passage 58B, the third oil passage 58C, and the fourth oil passage 58D is connected to the control valve 56. The other ends of the first oil passage 58A, the second oil passage 58B, the third oil passage 58C, and the fourth oil passage 58D are connected to the hydraulic motor 10.

[0030] The control valve 56 is a flow path switching valve. The control valve 56 has a valve body. The control valve 56 can change the connection relationship between the first supply / discharge passage 46 and the second supply / discharge passage 48 and the first oil passage 58A, the second oil passage 58B, the third oil passage 58C, and the fourth oil passage 58D. Specifically, the connection relationship between the first supply / discharge passage 46 and the second supply / discharge passage 48 and the first oil passage 58A, the second oil passage 58B, the third oil passage 58C, and the fourth oil passage 58D can be changed by displacing the valve body of the control valve 56 to a first position and a second position.

[0031] When the valve body is in the first position, the first supply / discharge passage 46 and the first oil passage 58A are in communication. Also, when the valve body is in the first position, the second supply / discharge passage 48 and the fourth oil passage 58D are in communication. Also, when the valve body is in the first position, the first supply / discharge passage 46 and the second oil passage 58B are in communication. Also, when the valve body is in the first position, the second supply / discharge passage 48 and the third oil passage 58C are in communication.

[0032] When the valve body is in the second position, the first supply / discharge passage 46 and the first oil passage 58A are in communication. Also, when the valve body is in the second position, the second supply / discharge passage 48 and the fourth oil passage 58D are in communication. Also, when the valve body is in the second position, communication between the first supply / discharge passage 46 and the second oil passage 58B is blocked. Also, when the valve body is in the second position, communication between the second supply / discharge passage 48 and the third oil passage 58C is blocked. Also, when the valve body is in the second position, the second oil passage 58B and the third oil passage 58C are in communication.

[0033] Therefore, when the valve body is in the second position, the second oil passage 58B, the hydraulic motor 10, and the third oil passage 58C constitute a closed hydraulic circuit. Furthermore, the first supply / discharge passage 46 and the first oil passage 58A are in communication regardless of whether the valve body of the control valve 56 is in the first or second position. That is, the first oil passage 58A is the passage connecting the first supply / discharge passage 46 and the hydraulic motor 10. Furthermore, the second supply / discharge passage 48 and the fourth oil passage 58D are in communication regardless of whether the valve body of the control valve 56 is in the first or second position. That is, the fourth oil passage 58D is the passage connecting the second supply / discharge passage 48 and the hydraulic motor 10.

[0034] In the following explanation, the state in which the valve body of the control valve 56 is in the first position may be described as "the control valve 56 is in the first position." Similarly, the state in which the valve body of the control valve 56 is in the second position may be described as "the control valve 56 is in the second position."

[0035] The hydraulic control device 40 is equipped with an oil replenishment passage 60. The oil replenishment passage 60 communicates with the second oil passage 58B and the third oil passage 58C when the control valve 56 is in the second position. The oil replenishment passage 60 is a passage for replenishing hydraulic fluid to the second oil passage 58B and the third oil passage 58C. Specifically, the oil replenishment passage 60 replenishes the hydraulic fluid that has leaked from the closed circuit formed by the second oil passage 58B, the hydraulic motor 10, and the third oil passage 58C when the valve body is in the second position. Also, when the valve body of the control valve 56 is in the first position, the oil replenishment passage 60 is closed.

[0036] In this embodiment, the high-pressure passage 54 constitutes the oil replenishment passage 60. That is, the oil replenishment passage 60 is connected to the high-pressure selector valve 52. The high-pressure selector valve 52 connects the oil replenishment passage 60 with the passage with high hydraulic fluid pressure among the first supply / discharge passage 46 and the second supply / discharge passage 48. The high-pressure selector valve 52 also blocks the connection between the oil replenishment passage 60 and the passage with low hydraulic fluid pressure among the first supply / discharge passage 46 and the second supply / discharge passage 48.

[0037] (Structure of a hydraulic motor) The hydraulic motor 10 of this embodiment will be described with reference to Figures 2 to 4. In one example, the hydraulic motor 10 is a drive source for travel in construction machinery.

[0038] As shown in Figure 2, the hydraulic motor 10 comprises a rocking housing 12, a rocking gear 14, a plurality of pins 16, and a plurality of crankshafts 18. The oscillating housing 12 is substantially cylindrical. In the following description, the direction parallel to the central axis C of the oscillating housing 12 is referred to as the reference direction. In Figure 2, the reference direction coincides with the plane of the paper. Furthermore, in this disclosure, a plan view refers to viewing the components from the reference direction.

[0039] Multiple semicircular recesses 20 are recessed into the inner circumferential surface of the oscillating housing 12. The multiple semicircular recesses 20 are arranged at equal intervals in the circumferential direction. The outer shape of the semicircular recesses 20 is semicircular when viewed from above. The number of semicircular recesses 20 is, for example, 13.

[0040] The pins 16 are located within the semicircular recesses 20. The number of pins 16 is equal to the number of semicircular recesses 20. The pins 16 are cylindrical. The diameter of the pins 16 is approximately the same as the diameter of the semicircular recesses 20. The pins 16 are rotatably supported by the semicircular recesses 20. Approximately half of the outer surface of the pins 16, in the circumferential direction around the central axis of the pins 16, is located within the semicircular recesses 20. The remaining circumferential portion of the pins 16 is exposed from the semicircular recesses 20.

[0041] The oscillating gear 14 is located inside the oscillating housing 12. The oscillating gear 14 is generally disc-shaped. The outer surface of the oscillating gear 14 is curved in a wave-like manner. That is, the outer surface of the oscillating gear 14 has repeating smooth irregularities. When the tips of these irregularities are called tooth tips 14X and the central parts of the irregularities are called tooth roots 14Y, the number of tooth roots 14Y is one less than the number of pins 16. As a result, in a portion of the circumferential range of the oscillating gear 14, the pins 16 are located at the tooth roots 14Y. On the other hand, in the remaining circumferential range of the oscillating gear 14, the pins 16 are located either between the tooth roots 14Y and tooth tips 14X or at tooth tips 14X. In other words, in a plan view, the center of the oscillating gear 14 does not coincide with the center of the oscillating housing 12. In other words, the oscillating gear 14 is eccentric with respect to the oscillating housing 12. Note that in Figure 2, only one representative tooth tip 14X is labeled. The same applies to the tooth root 14Y.

[0042] The region between the outer circumferential surface of the oscillating gear 14 and the inner circumferential surface of the oscillating housing 12 is an operating chamber 22 to which hydraulic fluid is supplied and discharged. The operating chamber 22 is located between two adjacent pins 16 in the circumferential direction. There are 13 operating chambers 22 in total. In response to the supply and discharge of hydraulic fluid to each operating chamber 22, the oscillating gear 14 oscillates so that the center of the oscillating gear 14 revolves around the center of the oscillating housing 12. Along with this, the circumferential range in which the pins 16 are located at the tooth roots 14Y of the oscillating gear 14 changes. The oscillating gear 14 can also rotate on its own axis.

[0043] The oscillating gear 14 is equipped with three shaft holes 24. The three shaft holes 24 penetrate the oscillating gear 14 in the reference direction. The shaft holes 24 are arranged at approximately equal intervals in the circumferential direction around the central axis of the oscillating gear 14.

[0044] Three crankshafts 18 are provided, corresponding to the shaft holes 24. Each crankshaft 18 passes through the shaft hole 24 individually. The crankshaft 18 comprises a pair of shaft portions (not shown) and an eccentric portion 26 connecting the pair of shaft portions. The eccentric portion 26 is cylindrical. The eccentric portion 26 is located in the shaft hole 24. The diameter of the eccentric portion 26 is approximately the same as the diameter of the shaft hole 24. The central axis of the eccentric portion 26 is approximately the same as the central axis of the shaft hole 24. The pair of shaft portions are located on both sides of the eccentric portion 26 in the reference direction. Both shaft portions are cylindrical. The pair of shaft portions have the same diameter and are coaxially arranged on both sides of the eccentric portion 26. The central axes of the pair of shaft portions are parallel to the central axis of the eccentric portion 26 and offset from that central axis. The pair of shaft portions are capable of rotating about their respective central axes. As the pair of shafts rotate, the eccentric part 26 revolves around the central axis of the shafts. The revolution of the eccentric part 26 supports the oscillation of the oscillating gear 14.

[0045] As shown in Figure 2, the oscillating gear 14 is provided with three column holes 28. The three column holes 28 penetrate the oscillating gear 14 in the reference direction. The column holes 28 are located between adjacent shaft holes 24 in the circumferential direction of the oscillating gear 14. Each column hole 28 is individually penetrated by a support column 30. The support columns 30 rotate around their axes as the oscillating gear 14 rotates. In plan view, each column hole 28 is slightly larger than each support column 30.

[0046] As shown in Figure 3, the hydraulic motor 10 has a flow path section 32. The inlet / outlet plate 36, which will be described later, is in contact with the end face of the oscillating gear 14 in the reference direction. The flow path section 32 is in contact with the surface of the inlet / outlet plate 36 that is in contact with the oscillating gear 14 and the surface that is opposite to it in the reference direction. The flow path section 32 rotates integrally with the rotation of the oscillating gear 14.

[0047] The flow path section 32 is equipped with a first oil passage 58A, a second oil passage 58B, a third oil passage 58C, and a fourth oil passage 58D. In detail, each of the oil passages 58A, 58B, 58C, and 58D branches into six passages, which are then arranged in the flow path section 32. In other words, the flow path section 32 is equipped with a total of 24 oil passages.

[0048] The oil passages 58A, 58B, 58C, and 58D are arranged at equal intervals in the circumferential direction. More specifically, the first oil passage 58A, the second oil passage 58B, the third oil passage 58C, and the fourth oil passage 58D are arranged at equal intervals in a counterclockwise direction in the order of first oil passage 58A, second oil passage 58B, third oil passage 58C, fourth oil passage 58D, first oil passage 58A, ... In Figure 4, the first oil passage 58A, the second oil passage 58B, the third oil passage 58C, and the fourth oil passage 58D are denoted by the symbols P1, P2, P3, and P4, respectively.

[0049] As shown in Figure 4, the hydraulic motor 10 has an inlet / outlet plate 36. The inlet / outlet plate 36 is positioned between the flow path section 32 and the working chamber 22 in the reference direction. The inlet / outlet plate 36 is fixed to the rocking housing 12 in a non-rotatable manner. The inlet / outlet plate 36 has a plurality of through holes 38. Each through hole 38 penetrates the inlet / outlet plate 36 in the reference direction. The plurality of through holes 38 are arranged at equal intervals in the circumferential direction. Each through hole 38 is positioned between the pins 16 in the circumferential direction. The number of through holes 38 is equal to the number of working chambers 22. In this embodiment, the number of through holes 38 is 13.

[0050] The number of through-holes 38 differs from the number of oil passages 58A, 58B, 58C, and 58D in the flow path section 32. More specifically, the number of through-holes 38 is one more than half the number of oil passages 58A, 58B, 58C, and 58D in the flow path section 32. Due to this difference in number, when the hydraulic motor 10 is in operation, only some of the multiple oil passages 58A, 58B, 58C, and 58D communicate with the working chamber 22.

[0051] For example, in Figure 4, the oscillating gear 14 is located in the center of the left and right sides of the oscillating housing 12. In this case, the hydraulic motor 10 has, as the working chamber 22, a first working chamber 22A communicating with the first oil passage 58A, a second working chamber 22B communicating with the second oil passage 58B, a third working chamber 22C communicating with the third oil passage 58C, and a fourth working chamber 22D communicating with the fourth oil passage 58D. The hydraulic motor 10 also has a fifth working chamber 22E that is not communicating with any of the first oil passage 58A, the second oil passage 58B, the third oil passage 58C, and the fourth oil passage 58D.

[0052] The fifth working chamber 22E is located in the center of the left-right axis in Figure 4. Starting from the fifth working chamber 22E, the third working chamber 22C, the first working chamber 22A, the third working chamber 22C, and so on are arranged alternately in a clockwise direction. Also, starting from the fifth working chamber 22E, the second working chamber 22B, the fourth working chamber 22D, the second working chamber 22B, and so on are arranged alternately in a counterclockwise direction. In other words, in Figure 4, the working chamber 22 on the left side communicates with either the first oil passage 58A or the third oil passage 58C. The working chamber 22 on the right side communicates with either the second oil passage 58B or the fourth oil passage 58D. There are three of each of the first working chamber 22A, the second working chamber 22B, the third working chamber 22C, and the fourth working chamber 22D. There is one fifth working chamber 22E.

[0053] (Operation of the hydraulic motor) The rotational operation of the hydraulic motor 10 will be described below. Note that the following description assumes the directional valve 50 is in the first position.

[0054] First, let's explain the case where the control valve 56 is in the first position. As described above, in Figure 4, of the working chambers 22 of the hydraulic motor 10, the left working chamber 22 is in communication with the first oil passage 58A or the third oil passage 58C, and the right working chamber 22 is in communication with the second oil passage 58B or the fourth oil passage 58D. Therefore, when the control valve 56 is in the first position, hydraulic fluid is supplied to the left working chamber 22. Also, hydraulic fluid is discharged from the right working chamber 22. Therefore, the oscillating gear 14 receives a force W directed to the right, as indicated by the arrow in Figure 4, due to the pressure difference between the left and right working chambers 22. The oscillating gear 14, having received force W, tries to move to the right. Therefore, the center of the oscillating gear 14 revolves around the center of the oscillating housing 12.

[0055] Here, the number of tooth roots 14Y of the oscillating gear 14 is different from the number of teeth in the working chamber 22. Therefore, the oscillating gear 14 revolves to move to the right and also rotates slightly on its own axis. In other words, the oscillating gear 14 rotates slightly relative to the oscillating housing 12.

[0056] As the oscillating gear 14 rotates slightly relative to the oscillating housing 12, the flow path section 32 rotates by the same angle relative to the inlet / outlet plate 36. Due to the relative rotation of the flow path section 32 and the inlet / outlet plate 36, each working chamber 22 communicates with different oil passages 58A, 58B, 58C, and 58D than those shown in Figure 4. Consequently, the direction of the force W acting on the oscillating gear 14 due to the pressure difference in the working chambers 22 changes. The hydraulic motor 10 rotates as a result of the continuous rotation of the oscillating gear 14 and its relative rotation, and the change in the direction of the force W acting on the oscillating gear 14.

[0057] When the control valve 56 is in the second position, the second oil passage 58B and the third oil passage 58C are in communication. When the pressure in one of the second working chambers 22B and the third working chamber 22C becomes higher than the other, the hydraulic fluid moves from the high-pressure working chamber 22 to the low-pressure working chamber 22 so that both working chambers 22 are at equal pressure. In other words, the hydraulic fluid circulates between the second oil passage 58B, the third oil passage 58C, and the hydraulic motor 10. More specifically, the hydraulic fluid circulates between the second working chamber 22B and the third working chamber 22C of the hydraulic motor 10 via the second oil passage 58B and the third oil passage 58C.

[0058] In this disclosure, "circulation" refers to the supply and discharge of approximately equal amounts of hydraulic fluid. For example, it is not a term that limits the supply of hydraulic fluid from the second working chamber 22B to the supply of the third working chamber 22C, but rather means that approximately equal amounts of hydraulic fluid to the amount discharged from the second working chamber 22B are supplied to the third working chamber 22C.

[0059] When the control valve 56 is in the second position, the amount of hydraulic fluid displaced by the hydraulic motor 10 decreases by the amount of hydraulic fluid circulating, compared to when the control valve 56 is in the first position. As a result, when the control valve 56 is in the second position, the torque decreases and the rotational speed increases compared to when the control valve 56 is in the first position. In other words, the hydraulic motor 10 can shift between a first gear, which is the gear shift when the control valve 56 is in the first position, with high torque and low rotational speed, and a second gear, which is the gear shift when the control valve 56 is in the second position, with low torque and high rotational speed.

[0060] The amount of hydraulic fluid displaced by the hydraulic motor 10 is the amount of hydraulic fluid discharged by the hydraulic motor 10 from the hydraulic circuit structure 200 during one cycle. For example, the amount of hydraulic fluid displaced is the amount of hydraulic fluid supplied from the pump to the hydraulic circuit structure 200 via the first supply / discharge passage 46 and the second supply / discharge passage 48 as the oscillating gear 14 increases or decreases the volume of each working chamber 22, and the amount of hydraulic fluid discharged from the hydraulic circuit structure 200 to the tank.

[0061] (Hydraulic control device) The hydraulic control device 40 will be described with reference to Figures 5 to 7. As shown in Figure 5, the hydraulic control device 40 includes a housing 70. The first supply and discharge port 42, the second supply and discharge port 44, the first supply and discharge passage 46, the second supply and discharge passage 48, the oil supply passage 60, and the first oil passages 58A to the fourth oil passages 58D are located within the internal space of the housing 70. The directional valve 50, the control valve 56, and the high-pressure selector valve 52 are located within the housing 70.

[0062] (Control valve) As shown in Figure 5, the control valve 56 includes a cylinder 72. The cylinder 72 is composed of, for example, an inner circumferential wall surrounding a cylindrical hole extending within the housing 70, and one end wall 731A, 732A of cylindrical plugs 731, 732, respectively, which close both ends of the hole. The cylinder 72 has a first end 72X and a second end 72Y. The first end 72X includes the end wall 731A of the plug 731 and the inner circumferential wall of the cylinder 72. The second end 72Y includes the end wall 731A of the plug 731 and the inner circumferential wall of the cylinder 72.

[0063] As shown in Figure 6, the cylinder 72 has a first annular groove 74A, a second annular groove 74B, a third annular groove 74C, and a fourth annular groove 74D. The first annular groove 74A, the second annular groove 74B, the third annular groove 74C, and the fourth annular groove 74D are portions in which the inner circumferential wall of the cylinder 72 is recessed away from the central axis of the cylinder 72. The first annular groove 74A, the second annular groove 74B, the third annular groove 74C, and the fourth annular groove 74D are all annular and extend in a circular motion in the circumferential direction. The first annular groove 74A, the second annular groove 74B, the third annular groove 74C, and the fourth annular groove 74D are arranged in this order from the first end 72X toward the second end 72Y.

[0064] The first annular groove 74A communicates with the first supply and discharge passage 46. The first annular groove 74A communicates with the first oil passage 58A. Therefore, the first oil passage 58A connects the first supply and discharge passage 46 and the hydraulic motor 10. The second annular groove 74B communicates with the second oil passage 58B. The third annular groove 74C communicates with the third oil passage 58C. The fourth annular groove 74D communicates with the second supply and discharge passage 48. The fourth annular groove 74D communicates with the fourth oil passage 58D. Therefore, the fourth oil passage 58D connects the second supply and discharge passage 48 and the hydraulic motor 10. In addition, the replenishment passage 60 opens into the inner circumferential wall of the cylinder 72 between the second annular groove 74B and the third annular groove 74C in the axial direction of the cylinder 72.

[0065] The cylinder 72 has an annular groove 76 for operating pressure. The annular groove 76 for operating pressure is a portion of the inner circumferential wall of the cylinder 72 that is recessed in a direction away from the central axis of the cylinder 72. The annular groove 76 for operating pressure is annular and extends in a circular direction.

[0066] The control valve 56 has a valve body. The valve body is located between the first end 72X and the second end 72Y of the cylinder 72. An example of a valve body is a spool 78. In the following description, the valve body may be referred to as a spool 78.

[0067] The spool 78 has a pilot land 80, a first land 82, a second land 84, and a third land 86. The outer diameters of the pilot land 80, the first land 82, the second land 84, and the third land 86 are equal to the inner diameter of the cylinder 72.

[0068] Furthermore, the spool 78 has an operating pressure groove 88, a first groove 90, and a second groove 92. The operating pressure groove 88 is located between the pilot land 80 and the first land 82 in the axial direction of the spool 78. The first groove 90 is located between the first land 82 and the second land 84 in the axial direction of the spool 78. The second groove 92 is located between the second land 84 and the third land 86 in the axial direction of the spool 78. The outer diameter of the portion of the spool 78 where the operating pressure groove 88, the first groove 90, and the second groove 92 are located is smaller than the inner diameter of the cylinder 72.

[0069] The spool 78 has a small diameter portion 94 and an annular stepped surface 95. The small diameter portion 94 is adjacent to the third land 86 from the second end 72Y side of the cylinder 72. The small diameter portion 94 constitutes the end of the spool 78. The outer diameter of the small diameter portion 94 is smaller than the outer diameter of the third land 86. The stepped surface 95 extends radially outward from the spool 78 and connects the outer circumferential surface of the small diameter portion 94 to the outer circumferential surface of the third land 86. The pilot land 80, operating pressure groove 88, first land 82, first groove 90, second land 84, second groove 92, third land 86 and small diameter portion 94 are arranged in this order from the first end 72X to the second end 72Y.

[0070] As shown in Figure 6, when the first groove 90 faces both the first annular groove 74A and the second annular groove 74B, the first annular groove 74A and the second annular groove 74B communicate through the first groove 90. When the second groove 92 faces both the third annular groove 74C and the fourth annular groove 74D, the third annular groove 74C and the fourth annular groove 74D communicate through the second groove 92. Also, as shown in Figure 7, when the first groove 90 faces both the second annular groove 74B and the third annular groove 74C, the second annular groove 74B and the third annular groove 74C communicate through the first groove 90.

[0071] The axial dimension of the spool 78 is smaller than the dimension between the end walls 731A and 732A of the plugs 731 and 732. Therefore, the spool 78 can move axially within the internal space of the cylinder 72. More specifically, the spool 78 is displaceable between a first position and a second position. The spool 78 can move from the first position to the second position by moving toward the second end 72Y.

[0072] As shown in Figure 6, when the spool 78 is in the first position, the first supply / discharge passage 46 and the second oil passage 58B are in communication, and the second supply / discharge passage 48 and the third oil passage 58C are in communication. Specifically, when the spool 78 is in the first position, the first groove 90 connects the first annular groove 74A and the second annular groove 74B, thereby connecting the first supply / discharge passage 46 and the second oil passage 58B. Also, when the spool 78 is in the first position, the second groove 92 connects the third annular groove 74C and the fourth annular groove 74D, thereby connecting the second supply / discharge passage 48 and the third oil passage 58C. Furthermore, when the spool 78 is in the first position, the second land 84 blocks the communication between the second annular groove 74B and the third annular groove 74C.

[0073] Furthermore, when the spool 78 is in the first position, communication between the oil supply passage 60 and the second oil passage 58B and the third oil passage 58C is blocked. Specifically, when the spool 78 is in the first position, the second land 84 blocks the oil supply passage 60, thereby blocking communication between the oil supply passage 60 and the second oil passage 58B and the third oil passage 58C.

[0074] As shown in Figure 7, when the spool 78 is in the second position, communication between the first supply / discharge passage 46 and the second oil passage 58B is blocked. Specifically, when the spool 78 is in the second position, the first land 82 blocks communication between the first annular groove 74A and the second annular groove 74B, thereby blocking communication between the first supply / discharge passage 46 and the second oil passage 58B. Also, when the spool 78 is in the second position, communication between the second supply / discharge passage 48 and the third oil passage 58C is blocked. Specifically, the second land 84 blocks communication between the third annular groove 74C and the fourth annular groove 74D, thereby blocking communication between the second supply / discharge passage 48 and the third oil passage 58C.

[0075] Furthermore, when the spool 78 is in the second position, the second oil passage 58B and the third oil passage 58C are in communication. Specifically, when the spool 78 is in the second position, the first groove 90 connects the second annular groove 74B and the third annular groove 74C, thereby connecting the second oil passage 58B and the third oil passage 58C. Also, when the spool 78 is in the second position, the oil supply passage 60 is in communication with the second oil passage 58B and the third oil passage 58C.

[0076] Furthermore, as shown in Figures 6 and 7, the operating pressure annular groove 76 and the operating pressure groove 88 are in communication regardless of whether the spool 78 is in the first position or the second position. The control valve 56 has a pilot chamber 96 and a spring chamber 98. The pilot chamber 96 and the spring chamber 98 are part of the internal space of the cylinder 72. The pilot chamber 96 is located at the first end 72X of the cylinder 72. The spring chamber 98 is located at the second end 72Y of the cylinder 72.

[0077] The pilot chamber 96 is a space defined by the bottom wall and inner circumferential wall of the cylinder 72 and the pilot land 80. Hydraulic fluid is supplied to the pilot chamber 96. The pilot chamber 96 can push the spool 78 toward the second position by the pilot pressure, which is the pressure of the hydraulic fluid supplied to the chamber 96.

[0078] The spring chamber 98 is a space defined by the bottom wall and inner circumferential wall of the cylinder 72 and the third land 86. Although not shown in the illustration, the spring chamber 98 has a port connected to a tank. Any hydraulic fluid that leaks into the spring chamber 98 is discharged to the tank through the port.

[0079] The control valve 56 has a spring 100 and a support member 102. The spring 100 is located in a spring chamber 98. The spring 100 is a coil spring. The spring 100 is located at the second end 72Y of the cylinder 72. More specifically, the spring 100 is located between the plug 732 and the spool 78. The spring 100 surrounds the small diameter portion 94 of the spool 78 from the radially outer side. The spring 100 pushes the spool 78 toward a first position. More specifically, the spring 100 pushes the stepped surface 95 of the spool 78 toward a first position. The support member 102 is located in a spring chamber 98. The support member 102 is cylindrical.

[0080] The control valve 56 includes an operating pressure chamber 104. In this embodiment, the operating pressure chamber 104 is the internal space of the spool 78. More specifically, the operating pressure chamber 104 extends axially within the interior of the spool 78. The operating pressure chamber 104 has an open end 110 that opens to the second end 72Y and a closed end 112 located closer to the first end 72X.

[0081] The support member 102 is inserted into the open end 110 of the working pressure chamber 104 of the spool 78. The support member 102 supports the spool 78 so that it can move in the axial direction. The outer diameter of the support member 102 is equal to the inner diameter of the working pressure chamber 104. That is, the open end 110 of the working pressure chamber 104 is closed by the support member 102. Therefore, the spool 78 is pushed toward the first position by the pressure exerted by the hydraulic fluid in the working pressure chamber 104 on the closed end 112 of the working pressure chamber 104. The closed end 112 of the working pressure chamber 104 constitutes a pressure-receiving surface facing the second end 72Y side of the cylinder 72. The spool 78 is displaceable from the second position toward the first position by being pushed by the pressure acting on the pressure-receiving surface.

[0082] The connecting passage 106 extends radially within the spool 78. The connecting passage 106 connects the working pressure chamber 104 and the working pressure groove 88 of the spool 78. The connecting passages 106 are arranged at 180-degree intervals in the circumferential direction.

[0083] The hydraulic control device 40 includes a connecting passage 106 and an operating pressure passage 108. The operating pressure passage 108 communicates with the oil supply passage 60. The operating pressure passage 108 also communicates with the operating pressure annular groove 76. In other words, the operating pressure passage 108 connects the oil supply passage 60 and the operating pressure chamber 104. Hydraulic fluid is introduced from the oil supply passage 60 to the operating pressure chamber 104 via the operating pressure passage 108. More specifically, the hydraulic fluid from the oil supply passage 60 is supplied to the operating pressure chamber 104 via the operating pressure passage 108, the operating pressure annular groove 76, the operating pressure groove 88, and the connecting passage 106.

[0084] (Operation of the first embodiment) The operation of the hydraulic control device 40 of this embodiment will be described below. The following description will focus on the case where the directional valve 50 is in the first position. When the directional valve 50 is in the second position, the roles of the first supply / discharge passage 46 and the second supply / discharge passage 48, the roles of the first oil passage 58A and the fourth oil passage 58D, and the roles of the second oil passage 58B and the third oil passage 58C are swapped compared to when the directional valve 50 is in the first position.

[0085] The hydraulic control device 40 can change the supply state of hydraulic fluid to the hydraulic motor 10 by moving the control valve 56 to a first position and a second position. When the valve body is in the first position, hydraulic fluid is supplied to the hydraulic motor 10 from the first supply / discharge passage 46 via the first oil passage 58A and the second oil passage 58B. Also, when the valve body is in the first position, hydraulic fluid is discharged from the hydraulic motor 10 to the second supply / discharge passage 48 via the third oil passage 58C and the fourth oil passage 58D.

[0086] When the valve body is in the second position, hydraulic fluid is supplied to the hydraulic motor 10 from the first supply / discharge passage 46 via the first oil passage 58A. When the valve body is in the second position, hydraulic fluid is discharged from the hydraulic motor 10 to the second supply / discharge passage 48 via the fourth oil passage 58D. The second oil passage 58B and the third oil passage 58C are connected. In other words, the second oil passage 58B, the third oil passage 58C, and the hydraulic motor 10 constitute a closed hydraulic circuit.

[0087] When the valve body is in the second position, as described above, the amount of hydraulic fluid displaced by the hydraulic motor 10 decreases by the amount of hydraulic fluid circulating. Therefore, when the valve body is in the second position, the torque decreases and the rotational speed increases compared to when the valve body is in the first position. Accordingly, the hydraulic control device 40 can switch the hydraulic motor 10 between a first speed with high torque and low rotational speed, and a second speed with low torque and high rotational speed.

[0088] The valve body is pushed toward the second position by the pressure in the pilot chamber 96. The valve body is also pushed toward the first position by the force of the spring 100 pushing the spool 78 and the pressure in the working chamber 22.

[0089] The working chamber 22 is connected by a high-pressure selector valve 52 to the passage with the higher pressure among the first supply / discharge passage 46 and the second supply / discharge passage 48. When the directional valve 50 is in the first position, the working chamber 22 is connected to the first supply / discharge passage 46. Therefore, when the pressure in the first supply / discharge passage 46 increases, the pressure in the working chamber 22 also increases. Consequently, when the pressure in the first supply / discharge passage 46 increases, the force pushing the valve body toward the first position increases.

[0090] When the control valve 56 is in the second position, as described above, the hydraulic motor 10 is operating at low torque and high rotational speed. When the load on the hydraulic motor 10 increases and its operation is hindered, the pressure in the first supply and discharge passage 46 increases. Therefore, when the load on the hydraulic motor 10 increases, the force pushing the valve body toward the first position increases. That is, when the hydraulic motor 10 is in the second position, when the load on the hydraulic motor 10 increases, the valve body autonomously moves to the first position. Therefore, when the load on the hydraulic motor 10 increases, the control valve 56 autonomously switches from the second position of low torque and high rotation to the first position of high torque and low rotational speed.

[0091] (Effects of the first embodiment) The hydraulic control device 40 of the first embodiment has the following effects. (1-1) When the valve body of the control valve 56 is in the first position, hydraulic fluid is supplied to and discharged from the hydraulic motor 10 through the first oil passage 58A and the fourth oil passage 58D, and the second oil passage 58B and the third oil passage 58C. When the valve body is in the second position, the second oil passage 58B, the hydraulic motor 10, and the third oil passage 58C form a closed hydraulic circuit, so no hydraulic fluid is supplied to or discharged from the hydraulic motor 10 through the second oil passage 58B and the third oil passage 58C. When the valve body is in the second position, the same amount of hydraulic fluid that was discharged from the hydraulic motor 10 to the second oil passage 58B and the third oil passage 58C is returned to the hydraulic motor 10 through the second oil passage 58B and the third oil passage 58C. For this reason, when the valve body is in the second position, the rotational speed of the hydraulic motor 10 is faster and the torque is lower compared to when it is in the first position. Therefore, by creating a closed hydraulic circuit with the second oil passage, the hydraulic motor 10, and the third oil passage, the supply state of hydraulic fluid to the hydraulic motor 10, and consequently the operating state of the hydraulic motor 10, can be switched in two stages.

[0092] (1-2) When the hydraulic control device 40 is connected to the hydraulic motor 10, as described above, when the valve body is in the second position, the hydraulic motor 10 operates with lower torque and higher rotational speed compared to when the valve body is in the first position. Therefore, by switching the valve position of the control valve 56, the operation of the hydraulic motor 10 can be switched between high torque and low rotational speed and low torque and high rotational speed.

[0093] Furthermore, both the first and second positions of the control valve 56 correspond to both forward and reverse rotation of the hydraulic motor 10. Therefore, the control valve 56 does not require a third or subsequent position specifically for when the hydraulic motor 10 is rotating in the reverse direction. Consequently, the complexity of the control valve 56's structure can be suppressed.

[0094] (1-3) If hydraulic fluid leaks from the hydraulic circuit, which is composed of the second oil passage 58B, the hydraulic motor 10, and the third oil passage 58C, causing the hydraulic fluid pressure in the hydraulic passage to drop, hydraulic fluid is replenished to the hydraulic circuit through the replenishment passage 60 until the pressure of the hydraulic fluid rises to the pressure it was at before the drop. As a result, instability in the operation of the hydraulic motor 10 caused by hydraulic fluid leakage from the hydraulic circuit is less likely to occur.

[0095] (1-4) Through the high-pressure selector valve 52, the oil supply passage 60 communicates with the passage with the higher pressure among the first supply and discharge passage 46 and the second supply and discharge passage 48. Therefore, the hydraulic circuit consisting of the second oil passage 58B, the hydraulic motor 10, and the third oil passage 58C can be communicated with the passage among the first supply and discharge passage 46 and the second supply and discharge passage 48 that supplies hydraulic fluid to the hydraulic motor 10. Thus, a part of the configuration for replenishing hydraulic fluid in the oil supply passage 60 can be shared as part of the configuration for supplying hydraulic fluid to the hydraulic motor 10.

[0096] (1-5) When the discharge rate of the pump is constant, if the load on the hydraulic motor 10 increases, the pressure of the hydraulic fluid in the passage that supplies hydraulic fluid to the hydraulic motor 10, among the first supply and discharge passage 46 and the second supply and discharge passage 48, increases. When the hydraulic fluid with increased pressure is introduced into the working pressure chamber 104, the pressure of the working pressure chamber 104 acting on the pressure-receiving surface pushes the valve body from the second position to the first position. As a result, the valve body moves from the second position to the first position. Therefore, in response to the increase in the load acting on the hydraulic motor 10, autonomous switching of the control valve 56 from the second position to the first position can be achieved.

[0097] (1-6) The hydraulic control device 40 can achieve autonomous speed change in response to the load acting on the hydraulic motor 10 through the high-pressure passage 54 and the working pressure chamber 104. Therefore, while suppressing an increase in the number of parts of the hydraulic control device 40, it is possible to achieve autonomous switching of the control valve 56 from the second position to the first position in response to an increase in the load acting on the hydraulic motor 10.

[0098] (1-7) The hydraulic control device 40 can change the connection state between the first supply and discharge passage 46 and the second supply and discharge passage 48 and the first oil passage 58A, the second oil passage 58B, the third oil passage 58C, and the fourth oil passage 58D by the lands 80, 82, 84, 86 and grooves 90, 92 of the spool 78 and the annular grooves 74A, 74B, 74C, 74D of the cylinder 72.

[0099] (1-8) The operating pressure chamber 104 of the hydraulic control device 40 is an internal space extending within the spool 78. Therefore, without complicating the structure of the cylinder 72, i.e., the housing 70, autonomous switching of the control valve 56 from the second position to the first position can be achieved in response to an increase in the load acting on the hydraulic motor 10.

[0100] <Second Embodiment> Referring to Figure 8, the hydraulic control device 40 of the second embodiment will be described. The hydraulic control device 40 of the second embodiment differs from the first embodiment in the configuration of the control valve 56. Specifically, the configuration of the operating pressure chamber 104, the pilot land 80 of the spool 78, and the first land 82 are mainly different. In Figure 8, parts that function the same or substantially the same as those in Figure 6 are denoted by the same reference numerals as in Figure 6. In addition, in the following description, parts that overlap in content with the first embodiment may be omitted or simplified as appropriate.

[0101] As shown in Figure 8, the cylinder 72 has a large inner diameter section 72A and a small inner diameter section 72B. The inner diameter of the large inner diameter section 72A is larger than the inner diameter of the small inner diameter section 72B. The large inner diameter section 72A is located at the first end 72X of the cylinder 72. The small inner diameter section 72B is adjacent to the large inner diameter section 72A from the second end 72Y side. The first annular groove 74A, the second annular groove 74B, the third annular groove 74C, and the fourth annular groove 74D are located at the small inner diameter section 72B of the cylinder 72.

[0102] In the spool 78 of this embodiment, the outer diameter of the pilot land 80 is larger than the outer diameter of the first land 82. The pilot land 80 is adjacent to the first land 82 from the first end 72X side of the cylinder 72. The spool 78 has an annular stepped surface 114 that connects the pilot land 80 and the first land 82. The stepped surface 114 extends radially outward from the outer circumferential surface of the first land 82 to the spool 78. The stepped surface 114 connects the outer circumferential surface of the pilot land 80 to the outer circumferential surface of the first land 82. The stepped surface 114 faces the second end 72Y side of the cylinder 72. In the following description, the pilot land 80 of the second embodiment may be referred to as the large diameter portion 80. Also, the first land 82 of the second embodiment may be referred to as the small diameter portion 82.

[0103] The pilot land 80 is the end of the spool 78 on the first end 72X side of the cylinder 72. Therefore, the end face of the pilot land 80 on the first end 72X side has a pilot surface 781 on which the pressure of the pilot chamber 96 acts. The outer diameter of the pilot land 80 is equal to the inner diameter of the large inner diameter portion 72A of the cylinder 72. Therefore, the large inner diameter portion 72A of the cylinder 72 has a first contact surface that contacts the outer circumferential surface of the pilot land 80. The first contact surface is the inner circumferential wall of the large inner diameter portion 72A of the cylinder 72.

[0104] The outer diameter of the first land 82 is equal to the inner diameter of the small inner diameter portion 72B of the cylinder 72. Therefore, the small inner diameter portion 72B of the cylinder 72 has a second contact surface that contacts the outer circumferential surface of the first land 82. The second contact surface is the inner circumferential wall of the small inner diameter portion 72B of the cylinder 72. The cylinder 72 also has a connecting surface 116 that connects the first contact surface and the second contact surface. The connecting surface 116 extends radially outward from the second contact surface toward the first contact surface.

[0105] In this embodiment, the operating pressure chamber 104 is the space between the outer circumferential surface of the spool 78 and the inner circumferential wall of the cylinder 72. Specifically, the operating pressure chamber 104 is the space defined by the stepped surface 114 of the spool 78, the outer circumferential surface of the first land 82, and the connecting surface 116 of the cylinder 72.

[0106] The spool 78 is pushed toward the first position by the pressure of the hydraulic fluid in the operating pressure chamber 104 acting on the stepped surface 114. The stepped surface 114 of the spool 78 constitutes a pressure-receiving surface facing the second end 72Y side of the cylinder 72. That is, the spool 78 is displaceable from the second position toward the first position by being pushed by the pressure acting on the stepped surface 114, which is the pressure-receiving surface.

[0107] (Effects of the second embodiment) The hydraulic control device 40 of the second embodiment has the following effects in addition to (1-1) to (1-7) of the first embodiment.

[0108] (2-1) In the second embodiment, the working pressure chamber 104 is defined by the stepped surface 114 of the spool 78, the outer circumferential surface of the first land 82, and the connecting surface 116 of the cylinder 72. Therefore, it is not necessary to provide a hole for the working pressure chamber 104 in the spool 78.

[0109] (2-2) The area of ​​the stepped surface 114, which is the pressure-receiving surface for the operating pressure chamber 104, is expressed as the difference between the cross-sectional area of ​​the large-diameter portion 80 and the cross-sectional area of ​​the small-diameter portion 82. The cross-sectional area is the cross-sectional area obtained by cutting in a direction perpendicular to the axial direction of the spool 78. The area of ​​the pilot surface 781, which is the pressure-receiving surface for the pilot chamber 96 of the spool 78, is expressed as the cross-sectional area of ​​the large-diameter portion 80. Therefore, the area of ​​the pilot surface 781 is larger than the area of ​​the stepped surface 114 by the amount of the cross-sectional area of ​​the small-diameter portion 82. Consequently, the pilot pressure required to move the spool 78 from the first position to the second position can be reduced.

[0110] <Third Embodiment> Referring to Figure 9, the hydraulic control device 40 of the third embodiment will be described. The hydraulic control device 40 of the third embodiment differs from the first embodiment in the configuration of the control valve 56. Specifically, the configuration of the operating pressure chamber 104, the spring chamber 98, and the spool 78 are mainly different. In Figure 9, parts that function the same or substantially the same as those in Figure 6 are denoted by the same reference numerals as in Figure 6. In addition, in the following description, parts that overlap in content with the first embodiment may be omitted or simplified as appropriate.

[0111] As shown in Figure 9, the cylinder 72 of the third embodiment is equipped with a guide member 118. The guide member 118 is located at the second end 72Y of the cylinder 72. The end face of the guide member 118 on the second end 72Y side is in contact with the bottom wall of the cylinder 72 on the second end 72Y side. The guide member 118 is cylindrical and surrounds a cylindrical insertion hole. The outer diameter of the guide member 118 is equal to the inner diameter of the cylinder 72.

[0112] In the spool 78 of this embodiment, the outer diameter of the small-diameter portion 94 is smaller than the inner diameter of the cylinder 72. That is, a cylindrical space exists between the outer circumferential surface of the small-diameter portion 94 and the inner circumferential wall of the cylinder 72. The spool 78 also has a stepped surface 119 that connects the third land 86 and the small-diameter portion 94. The stepped surface 119 extends radially outward from the outer circumferential surface of the small-diameter portion 94. The stepped surface 119 faces the second end 72Y side of the cylinder 72.

[0113] The outer diameter of the small-diameter portion 94 is equal to the inner diameter of the guide member 118. The small-diameter portion 94 is inserted into the guide member 118. Therefore, the end face of the guide member 118 on the first end 72X side is exposed in the space between the outer circumferential surface of the small-diameter portion 94 and the inner circumferential wall of the cylinder 72.

[0114] The small-diameter portion 94 has an internal space. That is, the small-diameter portion 94 is cylindrical with a bottom wall and side walls. Note that the third land 86 in the third embodiment may be described as the large-diameter portion 86.

[0115] In this embodiment, the spring chamber 98 is a space defined by the bottom wall and side wall of the small-diameter portion 94, the side wall of the guide member 118, and the bottom wall of the cylinder 72. The spring 100 is located inside the spring chamber 98. The spring 100 pushes the bottom wall of the small-diameter portion 94 toward the first end 72X. The outer diameter of the spring 100 is equal to the inner diameter of the small-diameter portion 94.

[0116] In this embodiment, the operating pressure chamber 104 is defined by the stepped surface 119, the outer circumferential surface of the small-diameter portion 94, the inner circumferential wall of the cylinder 72, and the end face of the guide member 118 on the first end 72X side. That is, the stepped surface 119 is the pressure-receiving surface on which the pressure of the hydraulic fluid in the operating pressure chamber 104 acts. The guide member 118 separates the operating pressure chamber 104 from the spring chamber 98.

[0117] Furthermore, the spool 78 of the third embodiment has one fewer land than the spool 78 of the first embodiment. Specifically, in the spool 78 of the third embodiment, the first groove 90 shown in Figure 6 is not present, and as a result, the first land 82 is integrated with the pilot land 80. In other words, in the spool 78 of the third embodiment, the pilot land 80 performs the roles of both the pilot land 80 and the first land 82 in the first embodiment.

[0118] (Effects of the third embodiment) The hydraulic control device 40 of the third embodiment has the following effects in addition to (1-1) to (1-7) of the first embodiment.

[0119] (3-1) In the third embodiment, the operating pressure chamber 104 is defined by the stepped surface 119 of the spool 78, the outer circumferential surface of the small diameter portion 94, and the end face of the guide member 118 on the first end 72X side. Therefore, there is no need to provide a hole in the spool or a stepped surface on the inner circumferential wall of the cylinder.

[0120] [Example of changes] This embodiment can be implemented with the following modifications. This embodiment and the following modifications can be implemented one or more of them in combination with each other to the extent that they do not contradict each other technically.

[0121] The configuration of the control valve 56 is not limited to the above. For example, the valve body of the control valve 56 may be composed of multiple spools. The control valve 56 shown in Figure 10 has a first spool 120X and a second spool 120Y. Note that Figure 10 shows the case where the control valve 56 is in the second position.

[0122] The cylinder 72 of the control valve 56 has two large inner diameter sections 122X and 122Y and one small inner diameter section 124. The large inner diameter sections 122X and 122Y are located at the first end 72X and the second end 72Y of the cylinder 72, respectively. The small inner diameter section 124 is located between the two large inner diameter sections 122X and 122Y in the axial direction of the cylinder 72. The small inner diameter section 124 connects the two large inner diameter sections 122X and 122Y. The first annular groove 74A, the second annular groove 74B, the third annular groove 74C, and the fourth annular groove 74D are located in the small inner diameter section 124.

[0123] The first spool 120X has a first pilot land 126X, a first small diameter portion 128X, and a first center land 130X. The outer diameter of the first pilot land 126X is equal to the inner diameter of the large inner diameter portion 122X. The outer diameters of the first small diameter portion 128X and the first center land 130X are equal to the inner diameter of the small inner diameter portion 124. The first pilot land 126X, the first small diameter portion 128X, and the first center land 130X are arranged in this order from the first end 72X side to the second end 72Y side. A first groove 132X is also located in the first small diameter portion 128X. The outer diameter of the portion of the first small diameter portion 128X where the first groove 132X is located is smaller than the inner diameter of the small inner diameter portion 124 of the cylinder 72.

[0124] The second spool 120Y has a second pilot land 126Y, a second small diameter portion 128Y, and a second center land 130Y. The outer diameter of the second pilot land 126Y is equal to the inner diameter of the large inner diameter portion 122Y. The outer diameters of the second small diameter portion 128Y and the second center land 130Y are equal to the inner diameter of the small inner diameter portion 124. The second pilot land 126Y, the second small diameter portion 128Y, and the second center land 130Y are arranged in this order from the second end 72Y side toward the first end 72X side. A second groove 132Y is also located in the second small diameter portion 128Y. The outer diameter of the portion of the second small diameter portion 128Y where the second groove 132Y is located is smaller than the inner diameter of the small inner diameter portion 124 of the cylinder 72.

[0125] The first spool 120X has an internal space with an open end face of the first center land 130X. The internal space of the first spool 120X is cylindrical. The bottom wall of the internal space of the first spool 120X is located within the small inner diameter portion 124.

[0126] The second spool 120Y has an internal space with an open end face of the second center land 130Y. The internal space of the second spool 120Y is cylindrical. The bottom wall of the internal space of the second spool 120Y is located within the small inner diameter portion 124.

[0127] The control valve 56 has a columnar portion 134. The columnar portion 134 is cylindrical. One end of the columnar portion 134 is inserted into the internal space of the first spool 120X. The other end of the columnar portion 134 is inserted into the internal space of the second spool 120Y. A spring 136X for the first column is positioned between the columnar portion 134 and the bottom wall of the internal space of the first spool 120X. A spring 136Y for the second column is positioned between the columnar portion 134 and the bottom wall of the internal space of the second spool 120Y.

[0128] A first spring 138X is positioned between the end wall 731A of plug 731 and the first pilot land 126X, pushing the first pilot land 126X toward the second end 72Y. Similarly, a second spring 138Y is positioned between the end wall 732A of plug 732 and the second pilot land 126Y, pushing the second pilot land 126Y toward the first end 72X.

[0129] The control valve 56 has a first pilot chamber 140X and a second pilot chamber 140Y. The first pilot chamber 140X is defined by the outer circumferential surface of the first small diameter portion 128X, a first stepped surface 142X connecting the outer circumferential surface of the first pilot land 126X and the outer circumferential surface of the first small diameter portion 128X, and a first connecting surface 144X connecting the inner circumferential wall of the large inner diameter portion 122X and the inner circumferential wall of the small inner diameter portion 124. The second pilot chamber 140Y is defined by the outer circumferential surface of the second small diameter portion 128Y, a second stepped surface 142Y connecting the outer circumferential surface of the second pilot land 126Y and the outer circumferential surface of the second small diameter portion 128Y, and a second connecting surface 144Y connecting the inner circumferential wall of the large inner diameter portion 122Y and the inner circumferential wall of the small inner diameter portion 124.

[0130] The first spool 120X and the second spool 120Y are pushed toward the axial center of the cylinder 72 by the first spring 138X and the second spring 138Y. In addition, the first spool 120X and the second spool 120Y are pushed toward the axial side of the cylinder 72 by the pressure of the first pilot chamber 140X and the second pilot chamber 140Y.

[0131] Figure 10 shows the state in which the first spool 120X and the second spool 120Y have moved outward in the axial direction of the cylinder 72 due to the pressure in the first pilot chamber 140X and the second pilot chamber 140Y. At this time, the first center land 130X blocks communication between the first supply / discharge passage 46 and the second oil passage 58B. Also, the second center land 130Y blocks communication between the second supply / discharge passage 48 and the third oil passage 58C. The second oil passage 58B and the third oil passage 58C are in communication between the first center land 130X and the second center land 130Y.

[0132] When the pressure in the first pilot chamber 140X and the second pilot chamber 140Y decreases, the first spool 120X and the second spool 120Y move to the axial center of the cylinder 72 by the pressure of the first spring 138X and the second spring 138Y. The first center land 130X and the second center land 130Y come into contact at the axial center of the cylinder 72. At this time, the first supply / discharge passage 46 and the second oil passage 58B communicate via the first groove 132X. Also, the second supply / discharge passage 48 and the third oil passage 58C communicate via the second groove 132Y. Furthermore, the communication between the second oil passage 58B and the third oil passage 58C is blocked by the first center land 130X and the second center land 130Y.

[0133] In other words, the control valve 56 can be displaced between a first position in which the first spool 120X and the second spool 120Y are in contact at the center in the axial direction of the cylinder 72, and a second position in which the first spool 120X and the second spool 120Y are separated outward in the axial direction of the cylinder 72. Even if the configuration is different from the above, the control valve 56 only needs to be displaced between a first position in which the first supply / discharge passage 46 and the second oil passage 58B are in communication, and the second supply / discharge passage 48 and the third oil passage 58C are in communication, and a second position in which the communication between the first supply / discharge passage 46 and the second oil passage 58B, and the communication between the second supply / discharge passage 48 and the third oil passage 58C are blocked, and the second oil passage 58B and the third oil passage 58C are in communication.

[0134] The hydraulic circuit structure 200 of the hydraulic control device 40 is not limited to the above configuration. As shown in Figure 11, the first oil passage 58A and the fourth oil passage 58D may be connected to the hydraulic motor 10 without going through the control valve 56. In the hydraulic circuit structure 200 of Figure 11, the first oil passage 58A connects the portion of the first supply / discharge passage 46 that is on the hydraulic motor 10 side of the directional valve 50 to the hydraulic motor 10. The second oil passage 58B connects the portion of the second supply / discharge passage 48 that is on the hydraulic motor 10 side of the directional valve 50 to the hydraulic motor 10. At this time, in the second position of the control valve 56, the first supply / discharge passage 46 and the second supply / discharge passage 48 may be closed within the control valve 56.

[0135] Furthermore, the first oil passage 58A and the second oil passage 58B may be connected to the first supply / discharge passage 46 and the second supply / discharge passage 48 on the side of the first supply / discharge port 42 and the second supply / discharge port 44 of the directional valve 50. Alternatively, the first oil passage 58A and the second oil passage 58B may be connected to the first supply / discharge passage 46 and the second supply / discharge passage 48 within the directional valve 50.

[0136] The hydraulic actuator is not limited to the hydraulic motor 10. The hydraulic actuator can be any hydraulic device in which hydraulic fluid is supplied through the first oil passage 58A to the fourth oil passage 58D, and whose operation is changed by switching between the first and second positions of the control valve 56. For example, if the hydraulic actuator is a hydraulic cylinder, hydraulic fluid is supplied and discharged to the first and second chambers located on both sides of the piston through the first oil passage 58A to the fourth oil passage 58D. As a result, the piston's movement speed and the force generated by the piston can be switched in two stages.

[0137] The configuration of the oil supply passage 60 and the high-pressure selector valve 52 in the hydraulic control device 40 is not limited to the above. For example, the oil supply passage 60 may be connected to a different pressure system from the hydraulic fluid flowing through the first supply / discharge passage 46 and the second supply / discharge passage 48. Also, the oil supply passage 60 and the high-pressure selector valve 52 may be omitted in the hydraulic control device 40.

[0138] The configuration of the operating pressure chamber 104 in the hydraulic control device 40 is not limited to the above. The operating pressure chamber 104 is configured such that the valve body of the control valve 56 can be displaced from the second position to the first position by the pressure in the operating pressure chamber 104. In addition, the operating pressure chamber 104, the operating pressure passage 108, and the operating pressure annular groove 76 may be omitted in the hydraulic control device 40.

[0139] In the above embodiment, a structure composed of multiple objects may be integrated, or conversely, a structure composed of a single object may be divided into multiple objects. Whether or not the objects are integrated, the structure should be configured in a way that achieves the objective of the invention.

[0140] The above description is illustrative only. Those skilled in the art will recognize that many more possible combinations and substitutions are possible beyond the components and methods (manufacturing processes) enumerated for the purpose of illustrating the technology of this disclosure. This disclosure is intended to encompass all alternatives, variations, and modifications that fall within the scope of this disclosure, including the claims. [Explanation of symbols]

[0141] 10… Hydraulic motor 12... Oscillating housing 14…Oscillating gear 14X…tooth tip 14Y…Tooth bottom 16... pins 18…Crankshaft 20... Semicircular recess 22…Operating chamber 22A...First working chamber 22B...Second working chamber 22C...Third working chamber 22D…Fourth working chamber 22E…Fifth working chamber 24…Hole for shaft 26...Eccentric part 28...Pillar hole 30…post 32...Flow channel section 36…Inlet / Outlet Plates 38…Through hole 40… Hydraulic control device 42...First supply and discharge port 44...Second supply and exhaust port 46…1st supply / discharge passage 48…Second supply / drainage passage 50... Directional valve 52... High-pressure selector valve 54…High-voltage passage 56…Control valve 58A…1st oil passage 58B…Second oil passage 58C…3rd oil passage 58D…4th oil passage 60…Bunker oil passage 70… Housing 72...Cylinder 72X...1st end 72Y…Second end 74A...First annular groove 74B...Second annular groove 74C...Third annular groove 74D...Fourth annular groove 76... Annular groove for operating pressure 78... Spool 80... Pilotland 82...Round 1 84... Second Round 86... Third Round 88…Operating pressure groove 90…1st groove 92…Second groove 94…Small diameter part 96... Pilot's Room 98... Spring Room 100... Spring 102...Support member 104…Working pressure chamber 106…Connecting passage 108...Operating pressure passage 110...Open end 112...Closed end 114...Step surface 116…Connection surface 118... Guide component 119...Step surface 120X...First spool 120Y...2nd spool 122X, 122Y…Large inner diameter part 124... Small inner diameter section 126X... First Pilot Land 126Y…2nd Pilotland 128X…1st small diameter section 128Y…Second small diameter section 130X...Central Land No. 1 130Y…Second Centerland 132X…1st groove 132Y…Second groove 134...Columnar part 136X…Spring for the first column 136Y…Spring for the second column 138X...1st Spring 138Y…2nd Spring 140X…Pilot Room 1 140Y…Pilot's Room 2 142X…1st step surface 142Y…2nd step surface 144X…First connection surface 144Y…Second connection surface 200... Hydraulic circuit structure 731, 732… plugs

Claims

1. The first supply and discharge passage and the second supply and discharge passage, The first oil passage connecting the first supply and discharge passage and the hydraulic actuator, A fourth oil passage connecting the second supply and discharge passage and the hydraulic actuator, A second oil passage and a third oil passage connected to the hydraulic actuator, A control valve having a valve body, The valve body is, A first position in which the first supply / discharge passage and the second oil passage are in communication, and the second supply / discharge passage and the third oil passage are in communication, The communication between the first supply / discharge passage and the second oil passage, and the communication between the second supply / discharge passage and the third oil passage are blocked, respectively, and there is a second position in which the second oil passage and the third oil passage communicate, It is displaceable, Hydraulic control device.

2. The first oil passage, the second oil passage, the third oil passage, and the fourth oil passage are connected to the hydraulic motor which serves as the hydraulic actuator. The hydraulic control device according to claim 1.

3. The second oil passage and the third oil passage are further provided with an oil supply passage for replenishing hydraulic fluid. The oil supply passage is connected to the control valve, The first position is the position in which the valve body blocks communication between the oil supply passage and the second and third oil passages. The second position is the position where the oil supply passage, the second oil passage, and the third oil passage are in communication. The hydraulic control device according to claim 2.

4. The system further includes a high-pressure selector valve that connects the passage with high hydraulic fluid pressure among the first supply / discharge passage and the second supply / discharge passage to the oil replenishment passage, and blocks communication between the passage with low hydraulic fluid pressure among the first supply / discharge passage and the oil replenishment passage. The hydraulic control device according to claim 3.

5. The control valve has an operating pressure chamber into which hydraulic fluid is introduced from the oil supply passage, The valve body is displaceable from the second position to the first position by the pressure in the operating pressure chamber. The hydraulic control device according to claim 4.

6. The control valve is A cylinder having a first end and a second end, with the spool serving as the valve body positioned between the first end and the second end, A pilot chamber located at the first end, which pushes the spool toward the second position by pilot pressure, A spring located at the second end that pushes the spool toward the first position, Equipped with, The hydraulic control device according to claim 2.

7. High-voltage passage and The system further includes a high-pressure selector valve that connects the passage with high hydraulic fluid pressure among the first and second supply / discharge passages to the high-pressure passage, and blocks communication between the passage with low hydraulic fluid pressure among the first and second supply / discharge passages to the high-pressure passage, The control valve has an operating pressure chamber that communicates with the high-pressure passage, The spool has a pressure-receiving surface facing the second end, which defines the operating pressure chamber, and is displaceable from the second position to the first position by the pressure of the hydraulic fluid acting on the pressure-receiving surface. The hydraulic control device according to claim 6.

8. The operating pressure chamber extends through the interior of the spool in the axial direction of the spool and has an open end that opens to the second end and a closed end that serves as the pressure receiving surface. The system further includes a support member inserted into the open end to support the spool so that it can move in the axial direction. The hydraulic control device according to claim 7.

9. The spool has a large diameter portion and a small diameter portion which has a smaller diameter than the large diameter portion. The pressure-receiving surface extends radially outward from the outer surface of the small-diameter portion to the outer surface of the spool, connecting the outer surface of the large-diameter portion and the outer surface of the small-diameter portion. The cylinder has a first contact surface and a second contact surface that contact the outer circumferential surface of the large diameter portion and the outer circumferential surface of the small diameter portion, respectively, and a connecting surface that connects the first contact surface and the second contact surface. The operating pressure chamber is defined by the pressure-receiving surface, the outer circumferential surface of the small-diameter portion, and the connecting surface. The hydraulic control device according to claim 7.

10. The large-diameter portion is the end of the spool, having a pilot surface on which the pilot pressure of the pilot chamber acts. The hydraulic control device according to claim 9.

11. The spool has a large diameter portion and a small diameter portion which has a smaller diameter than the large diameter portion. The pressure-receiving surface extends radially outward from the outer surface of the small-diameter portion to the outer surface of the spool, connecting the outer surface of the small-diameter portion and the outer surface of the large-diameter portion. The cylinder has a guide member located at the second end, which has an insertion hole into which the small diameter portion is inserted. The operating pressure chamber is defined by the pressure-receiving surface, the outer circumferential surface of the small-diameter portion, and the end face of the guide member on the first end side. The hydraulic control device according to claim 7.

12. The spool has a first land, a second land, a third land, a first groove located between the first land and the second land, and a second groove located between the second land and the third land. The cylinder has a first annular groove communicating with the first supply and discharge passage, a second annular groove communicating with the second oil passage, a third annular groove communicating with the third oil passage, and a fourth annular groove communicating with the second supply and discharge passage. The first position is a position in which the first groove connects the first annular groove and the second annular groove, the second groove connects the third annular groove and the fourth annular groove, and the second land blocks the connection between the second annular groove and the third annular groove. The second position is a position in which the first land and the second land block communication between the first annular groove and the second annular groove and communication between the third annular groove and the fourth annular groove, respectively, and the first groove connects the second annular groove and the third annular groove. The hydraulic control device according to claim 6.

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