Hydraulic clutch pressure regulator

Abstract

To provide a hydraulic clutch pressure regulating valve that improves the accuracy of adjusting the charge amount in the hydraulic clutch pressure regulating valve and enables versatility. [Solution] The system comprises a main circuit (12), a pressure reducing valve (14), a pilot circuit (18) that branches off from the main circuit (12) downstream of the pressure reducing valve (14) and supplies pilot pressure that reduces the opening of the pressure reducing valve (14), a first charge valve (20) that delays the supply of pilot pressure, a back pressure circuit (22) that branches off from the pilot circuit (18) and supplies back pressure that increases the opening of the pressure reducing valve (14), and a second charge valve (24) that adjusts the oil pressure in the back pressure circuit (22) to maintain a predetermined pressure, and is characterized by comprising a bypass circuit (26) that connects the pilot circuit (18) and the first charge valve (20) and increases the amount of oil supplied to the pilot chamber (14e) when the pilot pressure rises to a predetermined value.

Description

[Technical Field]

[0001] The present invention relates to a hydraulic clutch pressure regulating valve that is suitable for preventing a sudden increase in pressure that occurs when hydraulic oil is sent to a clutch in a hydraulic device. [Background technology]

[0002] A known hydraulic clutch pressure regulating valve that can improve responsiveness during clutch engagement and reduce engagement shock is disclosed in Patent Document 1. The hydraulic clutch pressure regulating valve disclosed in Patent Document 1 is basically composed of a pressure reducing valve that adjusts the amount of hydraulic oil supplied to the clutch, a first charge valve, and a second charge valve. The pressure reducing valve is provided with a valve element for adjusting the amount of hydraulic oil passing through the pressure reducing valve, and the first charge valve is an element that moves the valve element in the direction that reduces the amount of hydraulic oil, while the second charge valve is an element that moves the valve element in the direction that increases the amount of hydraulic oil.

[0003] In a hydraulic clutch pressure regulating valve configured as described above, the hydraulic circuit to the first charge valve branches off from the circuit downstream of the pressure reducing valve, i.e., the circuit that supplies hydraulic oil to the hydraulic clutch, and downstream of that, the hydraulic circuit to the second charge valve branches off. As a result, the hydraulic pressure of the hydraulic oil supplied to the hydraulic clutch is adjusted so that it is reduced by the first charge valve and increased by the second charge valve.

[0004] This prevents a sudden increase in pressure of the hydraulic oil supplied to the hydraulic clutch and reduces connection shock, and since the amount of hydraulic oil passing through the pressure reducing valve is not reduced until the supply path is filled with hydraulic oil, the clutch piston chamber is filled quickly and good clutch connection responsiveness can be maintained. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-161050 Summary of the Invention [Problem to be solved by the invention]

[0006] In a hydraulic clutch pressure regulating valve having the configuration disclosed in Patent Document 1, when the clutch size is constant, the amount of hydraulic oil charged (the amount of hydraulic oil that fills the clutch pressure chamber) changes little, so the adjustment range can be small.

[0007] On the other hand, in small clutches used on vessels other than ships, the charge amount varies greatly depending on the size and specifications of the clutch, and it is difficult for the hydraulic clutch pressure regulating valve disclosed in Patent Document 1 to cope with this.

[0008] SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems and to provide a hydraulic clutch pressure regulating valve that can improve the accuracy of adjusting the charge amount in the hydraulic clutch pressure regulating valve and can be made versatile. [Means for solving the problem]

[0009] To achieve the above object, a hydraulic clutch pressure regulating valve according to the present invention comprises: a main circuit that supplies hydraulic pressure from a hydraulic supply source to a clutch; a pressure reducing valve that is provided in the main circuit and has an aperture that changes in response to movement of a pressure reducing valve element; a pilot circuit that branches off from the main circuit downstream of the pressure reducing valve and supplies a pilot pressure to the pressure reducing valve that moves the pressure reducing valve element in a direction that reduces the aperture of the pressure reducing valve; a first charge valve that is provided in the pilot circuit and stops the supply of the pilot pressure to the pressure reducing valve until the hydraulic pressure in the pilot circuit reaches a predetermined pressure; a back pressure circuit that branches off from the pilot circuit and supplies a back pressure to the pressure reducing valve that moves the pressure reducing valve element in a direction that increases the aperture of the pressure reducing valve; and a second charge valve that is provided in the back pressure circuit and adjusts the hydraulic pressure in the back pressure circuit to maintain the predetermined pressure, and the pilot circuit comprises a bypass circuit that connects the pilot circuit and the first charge valve and increases the amount of hydraulic pressure supplied to the pressure reducing valve when the pilot pressure rises to a predetermined value.

[0010] In addition, in a hydraulic clutch pressure regulating valve having the above-described characteristics, it is preferable that the hydraulic pressure supply path to the first charge valve in the pilot circuit is provided with an orifice used to adjust the time when the pilot pressure starts to be supplied. This characteristic makes it possible to throttle the amount of hydraulic oil supplied to the first charge valve, thereby adjusting the time difference (delay time) between the supply of hydraulic pressure to the clutch and the supply of pilot pressure via the first charge valve. [Effects of the Invention]

[0011] According to a hydraulic clutch pressure regulating valve having the above-described characteristics, it is possible to improve the accuracy of adjusting the charge amount in the hydraulic clutch pressure regulating valve and to provide versatility. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a circuit diagram showing a configuration of a hydraulic clutch pressure regulating valve according to an embodiment of the present invention. [Figure 2] 4 is a circuit diagram showing a state in which the hydraulic clutch pressure regulating valve starts to supply hydraulic oil to the hydraulic clutch. FIG. [Figure 3] This is a circuit diagram showing a state in which hydraulic oil is supplied to the pilot chamber of the pressure reducing valve via the first charge valve in the hydraulic clutch pressure regulating valve to reduce the engagement shock of the hydraulic clutch, and the opening of the pressure reducing valve moves toward closure. [Figure 4] FIG. 4 is a circuit diagram showing a state in which hydraulic oil flows into a back pressure circuit via a pilot circuit in a hydraulic clutch pressure regulating valve. [Figure 5] 1 is a circuit diagram illustrating a hydraulic clutch pressure regulating valve in a state in which hydraulic oil is supplied to a back pressure chamber of a pressure reducing valve and the opening degree of the pressure reducing valve shifts in an opening direction. [Figure 6] 1 is a graph showing a state of change in hydraulic pressure from the supply of hydraulic oil to a hydraulic clutch to the engagement of the clutch, and a schematic diagram showing that state. [Figure 7] 1 is a graph showing the state of hydraulic pressure rise due to the action of back pressure after the clutch is engaged in a hydraulic clutch, and a schematic diagram showing that state. [Figure 8] 1 is a graph showing the rise in hydraulic pressure from when the hydraulic clutch is engaged until the clutch plates are completely in contact (power is completely transmitted), and a schematic diagram showing that state. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments of the hydraulic clutch pressure regulating valve of the present invention will be described in detail with reference to the drawings. Note that the embodiments described below are some of the preferred forms for carrying out the present invention, and even if some of the configuration is changed, they can be considered as part of the present invention as long as the effects of the invention are achieved.

[0014] [composition] First, the configuration of a hydraulic clutch pressure regulating valve (hereinafter simply referred to as pressure regulating valve 10) according to this embodiment will be described with reference to Figure 1. The pressure regulating valve 10 according to this embodiment is basically composed of a main circuit 12, a pressure reducing valve 14, a sub-circuit 16, a pilot circuit 18, a first charge valve 20, a back pressure circuit 22, a second charge valve 24, and a bypass circuit 26.

[0015] The main circuit 12 is a circuit that connects a hydraulic supply source such as a pump 40 to a clutch 50, and is provided with a filter 28, a pressure reducing valve 14, and a switching valve 30, in this order from the upstream side. Here, the clutch 50 is configured such that hydraulic oil is supplied to a piston chamber 50a, which operates a piston 50b and presses a clutch plate 50c, thereby transmitting the power of a main engine (not shown).

[0016] Therefore, the main circuit 12 is connected to supply hydraulic oil to the piston chamber 50a of the clutch 50. The supply of hydraulic oil to the clutch 50 is controlled by the ON / OFF control of the switching valve 30, but when the switching valve 30 is in the OFF state, the hydraulic oil supplied to the clutch is discharged to the hydraulic oil tank 60, and the piston chamber 50a becomes empty.

[0017] When the clutch 50 is connected (engaged), the pressure reducing valve 14 shortens the time it takes for the piston chamber 50a to be filled with hydraulic oil (the reaction time of the clutch 50), and after the piston chamber 50a has been filled with hydraulic oil, it temporarily increases the amount of pressure reduction (reduces the hydraulic oil pressure) thereby suppressing engagement shock and gently increasing the hydraulic pressure.

[0018] The pressure reducing valve 14 includes a cylinder 14a into which hydraulic oil flows, a pressure reducing valve element 14b that reciprocates within the cylinder 14, a back pressure piston 14c, and a pressure reducing spring 14d. The cylinder 14a also includes a hydraulic oil inlet port 14a1 and a hydraulic oil outlet port 14a2. The space within the cylinder 14a separated by the pressure reducing valve element 14b defines a pilot chamber 14e and a back pressure chamber 14f. When hydraulic oil is supplied to the pilot chamber 14e, the pressure reducing valve element 14b moves in a direction that closes the hydraulic oil inlet port 14a1, i.e., in a direction that reduces the opening of the pressure reducing valve 14 (to the right in FIG. 1). When hydraulic oil is supplied to the back pressure chamber 14f, the back pressure piston 14c moves toward the pressure reducing valve element 14b (to the left in FIG. 1). This action applies a pressing force to the pressure reducing spring 14d, causing the pressure reducing valve element 14b to move in a direction that opens the hydraulic oil inlet port 14a1, i.e., in a direction that increases the opening of the pressure reducing valve 14 (to the left in FIG. 1). Note that the hydraulic oil that passes through the pressure reducing valve 14 and is discharged from the hydraulic oil outlet port 14a1 is supplied to the clutch 50 when the switching valve 30 is in the ON state.

[0019] In the pressure reducing valve 14 configured as described above, the opening degree of the pressure reducing valve 14 is changed by the difference between the pressing force due to the oil pressure (oil volume) of the hydraulic oil supplied to the pilot chamber 14e and the pressing force due to the oil pressure (oil volume) of the hydraulic oil supplied to the back pressure chamber 14f. Here, when no hydraulic oil is supplied to either the pilot chamber 14e or the back pressure chamber 14f, the pressure reducing spring 14d arranged between the pressure reducing valve element 14b and the back pressure piston 14c acts to press the pressure reducing valve element 14b and the back pressure piston 14c against the longitudinal ends of the cylinder 14a so that the volumes of the pilot chamber 14e and the back pressure chamber 14f are minimized (the pressure reducing valve 14 is fully open).

[0020] The auxiliary circuit 16 is a branch circuit located downstream of the filter 28 and upstream of the pressure-reducing valve 14 in the main circuit 12. The auxiliary circuit 16 according to this embodiment not only supplies hydraulic pressure to other devices (not shown) but also contributes to adjusting the hydraulic pressure of the main circuit 12. Therefore, the auxiliary circuit 16 is provided with a hydraulic pressure adjustment valve 32. The hydraulic pressure adjustment valve 32 includes a hydraulic pressure adjustment cylinder 32a, an adjustment chamber 32b, a hydraulic pressure adjustment valve element 32c, a back pressure piston 32d, and a hydraulic pressure adjustment spring 32e. The hydraulic pressure adjustment cylinder 32a is a cylindrical body that reciprocates the hydraulic pressure adjustment valve element 32c and the back pressure piston 32d in response to the inflow of hydraulic oil. The adjustment chamber 32b acts as a buffer element for hydraulic oil flowing in from the main circuit 12 and being discharged to the outside. The hydraulic pressure adjustment valve element 32c enters the adjustment chamber 32b, changing the amount of hydraulic oil discharged and the hydraulic pressure. The hydraulic pressure adjustment spring 32e is disposed between the hydraulic pressure adjustment valve element 32c and the back pressure piston 32d. Adjusting the hydraulic pressure adjustment spring 32e allows adjustment of the biasing force of the hydraulic pressure adjustment valve element 32c, thereby enabling adjustment of the hydraulic pressure in the main circuit 12. An adjustment back pressure chamber 32f is formed at the end of the hydraulic pressure adjustment cylinder 32a near the back pressure piston 32d, and is connected to the back pressure circuit 22, which will be described in detail later. When hydraulic oil is supplied to the adjustment back pressure chamber 32f from the back pressure circuit 22, the back pressure piston 32d is pressed down, expanding the volume of the adjustment back pressure chamber 32f. This compresses the hydraulic pressure adjustment spring 32e, increasing the biasing force on the hydraulic pressure adjustment valve element 32c. This increases the discharge pressure of the hydraulic oil in the main circuit 12, thereby increasing the hydraulic pressure in the main circuit 12.

[0021] The pilot circuit 18 is a branch circuit provided in the main circuit 12 between the switching valve 30 and the clutch 50, i.e., downstream of the switching valve 30. The pilot circuit 18 is a circuit provided to supply hydraulic oil to the pilot chamber 14e of the pressure reducing valve 14. Therefore, when hydraulic oil flows into the pilot circuit 18, the opening of the pressure reducing valve 14 is reduced. In the pressure regulating valve 10 according to this embodiment, a first charge valve 20 is provided in the pilot circuit 18, thereby creating a delay between the flow of hydraulic oil into the pilot circuit 18 and the flow of hydraulic oil into the pilot chamber 14e.

[0022] First charge valve 20 has first charge cylinder 20a, first charge valve element 20b, and first charge adjustment spring 20c. First charge cylinder 20a is a cylindrical body to which hydraulic oil is supplied from pilot circuit 18, and first charge valve element 20b reciprocates to form first charge chamber 20d between inlet port 20d1 (outlet port 20d2) and first charge valve element 20b. In addition, a hydraulic oil discharge port 20a1 and a bypass port 20a2 are provided in the side wall of first charge cylinder 20a that forms first charge chamber 20d.

[0023] In first charge valve 20, when hydraulic oil is supplied to first charge chamber 20d, first charge valve element 20b moves against the biasing force of first charge adjustment spring 20c in accordance with the oil pressure of the supplied hydraulic oil, increasing the volume of first charge chamber 20d. When first charge valve element 20b moves a predetermined distance, hydraulic oil discharge port 20a1 and bypass port 20a2 are opened. When hydraulic oil discharge port 20a1 is opened, hydraulic oil that was supplied to first charge chamber 20d is supplied to pilot chamber 14e via pilot circuit 18. When bypass port 20a2 is opened, hydraulic oil flowing into pilot circuit 18 is supplied to first charge chamber 20d via bypass circuit 26.

[0024] Here, an orifice 18a is provided in the circuit (part of pilot circuit 18) connected to inlet port 20d1 to first charge valve 20, and the amount of hydraulic oil supplied to first charge chamber 20d is adjusted. Also, a check valve 18b is provided in the circuit connected to outlet port 20d from first charge valve 20, and a configuration is made such that hydraulic oil stored in first charge chamber 20d can be discharged to hydraulic oil tank 60 when the hydraulic pressure in pilot circuit 18 drops.

[0025] Furthermore, pilot circuit 18 connecting hydraulic oil discharge port 20a1 and pilot chamber 14e is provided with orifice 18c, allowing adjustment of the amount of hydraulic oil supplied to pilot chamber 14e. Furthermore, pilot circuit 18 connecting hydraulic oil discharge port 20a1 and pilot chamber 14e is provided with a branch circuit, which is connected to first charge cylinder 20a and forms discharge port 20a3. Discharge port 20a3 is located in an open state when first charge valve body 20b is positioned at the position where first charge chamber 20d is narrowest, and is an element for discharging hydraulic oil stored in pilot chamber 14e to hydraulic oil tank 60 when pilot circuit 18 is in an unloaded state.

[0026] By providing the first charge valve 20 configured as described above, it becomes possible to adjust the timing and amount of hydraulic oil supplied to the pilot chamber 20d by the orifices 18a, 18c and the first charge adjusting spring 20c.

[0027] The bypass circuit 26 is a branch circuit from the pilot circuit 18, and is an element for increasing the amount of hydraulic oil supplied to the pilot chamber 14e after the delay time has elapsed, i.e., after the hydraulic oil discharge port 20a1 in the first charge chamber 20d has been opened.

[0028] By providing the first charge valve 20, even when the hydraulic pressure in the main circuit 12, i.e., the pilot circuit 18, is increased, the desired delay time for hydraulic oil supply to the pilot chamber 14e can be ensured by adjusting the orifice 18a and the first charge adjustment spring 20c. Furthermore, by providing the first charge valve 20 with a bypass circuit 26, the amount of hydraulic oil supplied to the pilot chamber 14e (the amount supplied per predetermined time) can be increased after the delay time has elapsed. This shortens the time it takes for the piston chamber 50a of the clutch 50 to fill with hydraulic oil, i.e., the clutch 50 activation time, while also shortening the time from the clutch 50 activation to the reduction in the opening of the pressure-reducing valve 14, thereby reducing the impact when the clutch is engaged. Therefore, the orifice 18a and the first adjustment spring 20c have a small flow rate, allowing them to respond even to low hydraulic pressure, enabling more precise adjustment of the delay time.

[0029] The back pressure circuit 22 is a branch circuit from the pilot circuit 18, and is an element that supplies hydraulic oil to the back pressure chamber 14f in the pressure reducing valve 14 and operates the back pressure piston 14c. The back pressure circuit 22 is connected to the back pressure chamber 14f via a parallel circuit of an orifice 22a and a check valve 22b, and an adjustment back pressure chamber 32f of the hydraulic pressure adjustment valve 32.

[0030] The second charge valve 24 is an element for gently increasing the hydraulic pressure in the back pressure chamber 14f and is provided in a branch circuit from the back pressure circuit 22. The second charge valve 24 includes a second charge cylinder 24a, a second charge valve body 24b, and a second charge adjustment spring 24c, and a second charge chamber 24d is defined between the second charge cylinder 24a and the second charge valve body 24b. The second charge valve 24 acts as a buffer element, allowing for a gentle increase in the amount of hydraulic oil supplied to the back pressure chamber 14f. This allows for gentle adjustment of the opening of the pressure reducing valve 14, reducing the impact when the clutch 50 engages.

[0031] A drain circuit 34 is connected to the back pressure circuit 22, and the drain circuit 34 is connected to the pilot circuit 18 via a check valve 34a. When the pilot circuit 18a is in a no-load state, the check valve 34a opens, allowing the hydraulic oil in the back pressure circuit 22 to be discharged to the hydraulic oil tank 60.

[0032] [Actions and Effects] Next, hydraulic control of the clutch 50 via the pressure regulating valve 10 configured as described above will be described with reference to FIGS. 2 to 8. In the pressure regulating valve 10 according to the above embodiment, when hydraulic oil is supplied to the clutch 50, the switching valve 30 is turned ON while the pump 40 is running, as shown in FIG. 2. As a result, hydraulic oil supplied to the main circuit 12 is supplied to the piston chamber 50a of the clutch 50 via the pressure reducing valve 14 and also flows into the pilot circuit 18. At this time, hydraulic oil is not supplied to the pilot chamber 14e, so the pressure reducing valve 14 is fully open. Therefore, hydraulic oil at high pressure flows rapidly into the piston chamber 50a of the clutch 50. This shortens the time it takes for the piston chamber 50a of the clutch 50 to fill with hydraulic oil (0 to 0.5 seconds), as shown in the graph in FIG. 6. While the piston chamber 50a is filling with hydraulic oil, hydraulic oil flowing into the pilot circuit 18 is supplied to the first charge valve 20 and presses down the first charge valve element 20b.

[0033] When the first charge valve element 20b is depressed after a predetermined delay time adjusted by the orifice 18a and the first charge adjustment spring 20c, as shown in FIG. 3, the hydraulic oil discharge port 20a1 is opened and hydraulic oil is supplied to the pilot chamber 14e. At this time, the bypass port 20a2 is also opened, so that hydraulic oil is also supplied to the first charge chamber 20d from the bypass circuit 26, increasing the amount of hydraulic oil supplied to the pilot chamber 14e. This increases the pressure in the pilot chamber 14e, pushing the pressure-reducing valve element 14b downward toward the backpressure piston 14c, and operating the pressure-reducing valve 14 in the closing direction. As a result, the hydraulic oil pressure in the main circuit 12 downstream of the pressure-reducing valve 14 decreases, making it possible to suppress the engagement shock of the clutch 50 (0.5 seconds to 2.8 seconds in FIG. 6).

[0034] Next, the hydraulic oil that flows into pilot circuit 18 from first charge valve 20 to pilot chamber 14e flows into backpressure circuit 22. The hydraulic oil that flows into backpressure circuit 22 is supplied to backpressure chamber 14f of pressure-reducing valve 14 and second charge chamber 24d of second charge valve 24 via pressure regulating valve 32 (FIG. 4). At this time, second charge valve element 24b of second charge valve 24 is pushed down, thereby suppressing a sudden increase in hydraulic pressure in backpressure circuit 22. Therefore, as shown in FIG. 5, the hydraulic oil supplied to backpressure chamber 14f gradually pushes backpressure piston 14c toward pressure-reducing valve element 14b. When backpressure piston 14c moves toward pressure-reducing valve element 14b, pressure-reducing spring 14d acts to push pressure-reducing valve element 14b back toward the side narrowing pilot chamber 14e. Therefore, the opening of the pressure reducing valve 14 is gradually increased, and as shown in the graph of FIG. 7, the oil pressure of the hydraulic oil supplied to the clutch 50 rises gently (2.8 seconds - 12 seconds). After the clutch 50 is fully engaged, the pressure in the main circuit 12 rises as shown in the graph of FIG.

[0035] As described above, the pressure regulating valve 10 according to this embodiment shortens the operating time until the piston chamber 50a of the clutch 50 is filled with hydraulic oil, i.e., until the clutch plates 50c are tightly fitted, while lengthening the time until the neutral hydraulic pressure, i.e., until the clutch 50 reaches the engaged state, thereby making the hydraulic pressure rise gentle. This makes it possible to suppress the initial torque acting on the main engine when the clutch is engaged. Therefore, even when the power of the main engine is small, it is possible to avoid a decrease in rotation and suppress the impact that occurs when the clutch is engaged.

[0036] The pressure regulating valve 10 configured as described above allows for precise adjustment of the delay time (the time from when hydraulic oil is supplied to the piston chamber 50a until the aperture of the pressure reducing valve 14 is reduced) by the first charge valve 20, and also makes it possible to shorten the time required to reduce the aperture of the pressure reducing valve 14. This makes it possible to accommodate clutches of various sizes. [Explanation of symbols]

[0037] 10....Pressure regulating valve, 12....Main circuit, 14....Pressure reducing valve, 14a....Cylinder, 14a1....Hydraulic oil inlet port, 14a2....Hydraulic oil outlet port, 14b....Pressure reducing valve body, 14c....Back pressure piston, 14d....Pressure reducing spring, 14e....Pilot chamber, 14f....Back pressure chamber, 16....Sub-circuit, 18....Pilot circuit, 18a....Orifice, 18b....Check valve, 18c....Orifice, 20....First charge valve, 20a....First charge cylinder, 20a1....Hydraulic oil discharge port, 20a2....Bypass port, 20a3....Discharge port, 20b....First charge valve body, 20c....First charge adjusting spring, 20d....First charge chamber, 20d1....Inlet port, 20d2 ………Outlet port, 22………Back pressure circuit, 22a………Orifice, 22b………Check valve, 24………Second charge valve, 24a………Second charge cylinder, 24b………Second charge valve body, 24c………Second charge adjustment spring, 24d………Second charge chamber, 26………Bypass circuit, 28………Filter, 30………Switching valve, 32………Hydraulic pressure adjustment valve, 32a………Hydraulic pressure adjustment cylinder, 32b………Adjustment chamber, 32c………Hydraulic pressure adjustment valve body, 32d………Back pressure piston, 32e………Hydraulic pressure adjustment spring, 32f………Adjustment back pressure chamber, 34………Drain circuit, 34a………Check valve, 40………Pump, 50………Clutch, 50a………Piston chamber, 50b………Piston, 50c………Clutch plate, 60………Hydraulic oil tank.

Claims

1. a main circuit that supplies hydraulic pressure from a hydraulic pressure supply source to the clutch; a pressure reducing valve provided in the main circuit and having an opening degree that changes depending on the movement of a pressure reducing valve element; a pilot circuit branching from the main circuit downstream of the pressure reducing valve and supplying a pilot pressure to the pressure reducing valve for moving the pressure reducing valve element in a direction to reduce the opening of the pressure reducing valve; a first charge valve provided in the pilot circuit and configured to stop supplying the pilot pressure to the pressure reducing valve until the hydraulic pressure in the pilot circuit reaches a predetermined pressure; a back pressure circuit branching from the pilot circuit and supplying a back pressure to the pressure reducing valve that moves the pressure reducing valve element in a direction that increases the opening of the pressure reducing valve; a second charge valve provided in the back pressure circuit and regulating the hydraulic pressure in the back pressure circuit to maintain a predetermined pressure, a bypass circuit that connects the pilot circuit with the first charge valve and increases the amount of oil supplied to the pressure reducing valve when the pilot pressure rises to a predetermined value.

2. 2. The hydraulic clutch pressure regulating valve according to claim 1, wherein an orifice used for adjusting a time when the supply of pilot pressure to the first charge valve is provided in the hydraulic supply path to the pilot circuit.

Images