JPH05196125A - Pressure reducing valve - Google Patents

Abstract

PURPOSE:To provide a precise pressure reducing function by providing a port fed with the output pressure between an input port fed with main pressure and a feedback port. CONSTITUTION:An input port 42a fed with the high line pressure of a line 101, an output port 42b feeding the reduced output pressure to a line 104, a feedback port 42c feeding the output pressure to a pilot pressure chamber 68 via an orifice 69, and a drain port 42d are provided, and an output feed port 42e directly fed with the output pressure not via the orifice 69 is provided between the input port 42a and the feedback port 42c. The constant reduced output pressure (reducing pressure) corresponding to the energizing force of a spring 67 is obtained, the operating oil is prevented from leaking into the pilot pressure chamber 68 through a gap between the inner periphery of a valve cylinder 66 and the outer periphery of a spool 65 from the input port 42a, thereby a precise pressure reducing function by a pressure reducing valve 42 is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure reducing valve used in a hydraulic control circuit, and more particularly to a pressure reducing valve suitable for use in a hydraulic control circuit of a hydraulically operated belt type continuously variable transmission.

[0002]

2. Description of the Related Art Conventionally, in a hydraulic control circuit of a hydraulically actuated transmission which is configured to transmit an engine output obtained through a fluid coupling to wheels at a predetermined gear ratio,
The line pressure generated by adjusting the pump pressure with a pressure adjusting valve (pressure regulator valve) is reduced to a predetermined pressure with a pressure reducing valve, and is used as the original pressure of the pilot pressure for controlling the other pressure adjusting valves.

The pressure reducing valve is disclosed in, for example, Japanese Patent Laid-Open No. 62-4958.
As disclosed in the publication, a spool slidably provided in a valve cylinder and a spool that is compressed between one end of the spool and one end of the valve cylinder to urge the spool in one direction. A spring, an input port to which a high line pressure is supplied, an output port that generates an output pressure reduced from the line pressure to a predetermined pressure, and the output pressure from the side opposite to the spring side with respect to the spool. In order to make the above action, it has a configuration including a pilot pressure chamber provided with a feedback port for feeding back the output pressure via an orifice, and a drain port.

In such a pressure reducing valve, when the output pressure set based on the urging force of the spring falls below a predetermined value, the urging force of the spring becomes higher than the hydraulic pressure in the pilot pressure chamber, so that the spool has a pilot pressure. It moves to the room side and the output port communicates with the input port. Therefore, the line pressure is introduced into the output port and the output pressure rises. Then, the hydraulic pressure in the pilot pressure chamber becomes higher than the biasing force of the spring, the spool is returned, the output port communicates with the drain port, and the output pressure is reduced. By repeating such operations, a constant output pressure (reducing pressure) according to the biasing force of the spring can be obtained.

Further, Japanese Laid-Open Patent Publication No. 62-4958 discloses a hydraulically actuated belt type continuously variable transmission. This continuously variable transmission has a primary pool and a secondary pulley each having a belt receiving groove having a substantially V-shaped cross-sectional shape with a variable groove width, and a belt suspended between these pulleys. The primary pulley functions as a gear ratio control pulley, and the secondary pulley functions as a belt tension adjusting pulley. The belt widths of the belt receiving grooves of both pulleys are relatively changed by the hydraulic pressure so that continuous gear shifting is performed.

[0006]

By the way, in the spool valve used in the hydraulic control circuit, in order to allow the smooth sliding of the spool in the valve cylinder, the spool valve is provided between the inner peripheral surface of the valve cylinder and the outer peripheral surface of the spool. Ten~
A gap of about 20 μm is provided.

However, in the above-mentioned pressure reducing valve, an input port to which a high line pressure is supplied and a feedback port which supplies an output pressure reduced from the line pressure to the pilot chamber through an orifice are provided adjacent to each other. Therefore, the hydraulic fluid leaks from the input port through the gap into the pilot pressure chamber, thereby increasing the hydraulic pressure in the pilot pressure chamber. That is,
When the hydraulic pressure in the pilot pressure chamber rises above the output pressure, the spool moves in the direction that communicates the output port with the drain port against the biasing force of the spring, which causes the output pressure to drop below the set pressure. It was

In particular, the maximum value of the line pressure in the hydraulic control circuit of an ordinary automatic transmission is about 10 kg / cm ² , whereas in the belt type continuously variable transmission, the hydraulic chamber of the secondary pulley is a single chamber type. In this case, since a high line pressure of up to 35 kg / cm ² is required, the amount of hydraulic oil leak inside the pressure reducing valve increases, which significantly reduces the control accuracy of the pressure reducing valve.

For this reason, it has been conventionally proposed that a drain port is interposed between the input port and the feedback port of the pressure reducing valve to prevent the hydraulic oil from leaking from the input port to the pilot pressure chamber. , In this case, the hydraulic oil in the pilot pressure chamber leaks to the drain port side, lowers the hydraulic pressure in the pilot pressure chamber, and as a result, a new problem occurs that the output pressure rises above the set pressure, It was not a fundamental solution.

In view of the above problems, the present invention suppresses fluctuations in hydraulic pressure in the pilot pressure chamber due to leakage of hydraulic oil,
It is an object of the present invention to provide a pressure reducing valve that can obtain a pressure reducing function with good system.

[0011]

According to the pressure reducing valve of the present invention, an output to which the output pressure is supplied is provided between an input port to which the original pressure is supplied and a feedback port to which the reduced output pressure is supplied. It is characterized in that a pressure supply port is provided.

[0012]

According to the present invention, the port to which the output pressure is supplied is provided between the input port to which the high-pressure source pressure is supplied and the feedback port to which the reduced output pressure is supplied. By doing so, the leakage of hydraulic oil from the input port to the pilot pressure chamber becomes almost zero. Further, since there is no leak of hydraulic oil from the pilot pressure chamber to the drain port, which would occur when a drain port is provided between the input port and the feedback port, there is an effect that an accurate pressure reducing function can be obtained.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which a pressure reducing valve according to the present invention is applied to a hydraulic control circuit of a hydraulically operated continuously variable transmission will be described below with reference to the drawings.

FIG. 2 is a skeleton diagram showing the overall structure of the continuously variable transmission Z. The continuously variable transmission Z is a continuously variable transmission for driving front wheels, and includes a torque converter B connected to an output shaft 1 of an engine A, a forward / reverse switching gear groove C, a belt transmission mechanism D, and a reduction mechanism. E and a differential mechanism F are provided.

The torque converter B is fixed to one side of a pump cover 7 connected to the engine output shaft 1 and is fixed to the engine output shaft 1 as shown in FIG.
Between the pump impeller 3 that rotates integrally with the turbine impeller 3, and a turbine runner 4 that is rotatably provided in the space inside the pump cover 7 so as to face the pump impeller 3 and between the pump impeller 3 and the turbine runner 4. And a stator 5 that is interposed between the stator 5 and the stator 5 to increase the torque. Also,
The turbine runner 4 is connected via a turbine shaft 2 to a carrier 15 which is an input member of a forward / reverse switching mechanism C described later, and the stator 5 is connected to a mission case 19 via a one-way clutch 8 and a stator shaft 9. There is.

Further, a lockup clutch is arranged between the turbine runner 4 and the pump cover 7. The lock-up clutch includes a piston 6 that is spline-coupled to the turbine shaft 2 so as to be movable in the axial direction. The piston 6 creates a space in the converter cover 7 and a converter rear chamber 7a on the turbine 5 side and a converter It is divided into a converter front room 10 on the cover 7 side. When the hydraulic pressure is introduced into or discharged from the converter front chamber 10, the pump cover 7 comes into contact with and is integrated with the pump cover 7 in accordance with the differential pressure between the hydraulic pressure inside the converter front chamber 10 and the hydraulic pressure inside the converter rear chamber 7a. The lockup state and the converter state in which the pump cover 7 is separated from the pump cover 7 are selectively realized. Then, in the lockup state, the engine output shaft 1 and the turbine shaft 2 are directly coupled without fluid, and in the converter state, the engine torque is transmitted from the engine output shaft 1 to the turbine shaft 2 side via the fluid. ..

The forward / reverse switching mechanism C includes a torque converter B.
In this embodiment, the forward drive state in which the rotation of the turbine shaft 2 is directly transmitted to the belt transmission mechanism D side and the reverse drive state in which the rotation is transmitted to the belt transmission mechanism D in the reverse rotation state are selectively set. The forward / reverse switching mechanism C is composed of a double pinion type planetary gear unit. That is, the carrier splined to the turbine shaft 2
15, a first pinion gear 13 meshing with the sun gear 12,
A second pinion gear 14 that meshes with the ring gear 11 is attached. The sun gear 12 is splined to the primary shaft 22 of the belt transmission mechanism D.

Further, a forward clutch 16 for connecting and disconnecting the ring gear 11 and the carrier 15 is provided between the ring gear 11 and the carrier 15, and the ring gear 11 is connected to the mission case 19 between the ring gear 11 and the mission case 19. Reverse clutch (or brake) 17 for selective fixing
Is installed.

Therefore, when the forward clutch 16 is engaged and the reverse clutch 17 is disengaged, the ring gear 11 and the carrier 15 are integrated, and the ring gear 11 is rotatable relative to the transmission case 19. Therefore, the rotation of the turbine shaft 2 is output as it is in the same direction as the rotation in the same direction, and is output from the sun gear 12 to the primary shaft 22 side (forward state).

On the other hand, when the forward clutch 16 is released and the reverse clutch 17 is engaged,
Since the ring gear 11 is fixed to the mission case 19 side and the ring gear 11 and the carrier 15 can rotate relative to each other, the rotation of the turbine shaft 2 is reversed via the first pinion gear 13 and the second pinion gear 14. In this state, the sun gear 12 outputs to the primary shaft 22 side (reverse drive state).

That is, in the forward / reverse switching mechanism C, the forward / reverse switching is performed by the selective operation of the forward clutch 16 and the reverse clutch 17.

The belt transmission mechanism D is a primary pulley coaxially arranged on the rear side of the forward / reverse switching mechanism C described above.
The belt 20 is suspended between the secondary pulley 31 and the secondary pulley 31 that are spaced apart from the primary pulley 21.

As shown in FIG. 3, the primary pulley 21 has a sun gear 12 of the forward / reverse switching mechanism C on which a primary shaft 22 is spline-coupled.
A fixed conical plate 23 having a predetermined diameter is integrally provided with the primary shaft 22, and a movable conical plate 24 is provided so as to be movable in the axial direction of the primary shaft 22. Then, by the conical friction surface of the fixed conical plate 23 and the conical friction surface of the movable conical plate 24, approximately V
A belt receiving groove 21a having a V-shaped cross section is formed.

Further, on the outer surface 24a side of the movable conical plate 24,
A cylindrical piston 25 is fixed, and this piston 25
Is oil-tightly fitted and inserted into the inner peripheral surface of a cylinder 26 fixed to the primary shaft 22 side. The piston 25, the cylinder 26, and the movable conical plate 24 form a single-chamber type primary hydraulic chamber 27. This primary hydraulic chamber 27
The hydraulic pressure is introduced into the hydraulic circuit from a later-described hydraulic circuit.

The primary pulley 21 is a primary hydraulic chamber.
The hydraulic pressure introduced into 27 moves the movable conical plate 24 in the axial direction to increase or decrease the distance between the movable conical plate 24 and the fixed conical plate 23 and change the groove width of the belt receiving groove 21a.
The winding radius of the belt 20 with respect to 21, that is, the effective radius of the pulley 21 is adjusted.

The secondary pulley 31 basically has the same structure as that of the above-mentioned primary pulley 21, and as shown in FIG. A fixed conical plate 33 is provided integrally with the secondary shaft 32 on the formed secondary shaft 32, and a movable conical plate 34 is provided so as to be movable in the axial direction of the secondary shaft 32. Then, the conical friction surface of the fixed conical plate 33 and the movable conical plate 34
And the conical friction surface form a belt receiving groove 31a having a substantially V-shaped cross section.

Further, a cylindrical cylinder 35 is fixed on the outer surface 34a side of the movable conical plate 34, and a piston 36 fixed on the secondary shaft 32 is oil-tight on the inner side surface of the cylinder 35. Has been inserted. And this piston
The single-chamber type secondary hydraulic chamber 37 is configured by the 36, the cylinder 35, and the movable conical plate 34. As with the primary hydraulic chamber 27, hydraulic pressure is introduced into the secondary hydraulic chamber 37 from the hydraulic circuit.

Like the primary pulley 21, this secondary pulley 31 also moves its movable conical plate 34 in the axial direction by the hydraulic pressure introduced into the secondary hydraulic chamber 37 to increase or decrease the distance between it and the fixed conical plate 33. The winding radius of the belt 20, that is, the effective radius of the pulley 31 is adjusted by changing the groove width of the belt receiving groove 31a. In addition,
The pressure receiving area of the movable conical plate 34 is set to be smaller than that of the movable conical plate 24 of the primary pulley 21.

Regarding the speed reduction mechanism E and the differential mechanism F,
Since the structure is conventionally known, its description is omitted.

Next, the operation of the continuously variable transmission Z will be described. The torque transmitted from the engine A through the torque converter B is transmitted to the belt transmission mechanism D in the forward / reverse switching mechanism C with its rotation direction set to the forward direction or the reverse direction.

In the belt transmission mechanism D, when the effective radius of the primary pulley 21 is adjusted by introducing or discharging hydraulic oil into the primary hydraulic chamber 27 of the primary pulley 21, the belt 20 is passed through the primary pulley 21 via the belt 20. In the secondary pulley 31 that is interlocked and linked with each other, the effective radius of the secondary pulley 31 is adjusted in a state where the secondary pulley 31 is tracked. The ratio between the effective radius of the primary pulley 21 and the effective radius of the secondary pulley 31 determines the gear ratio between the primary shaft 22 and the secondary shaft 32.

The rotation of the secondary shaft 32 is further reduced by the reduction mechanism E and then transmitted to the differential mechanism F.
It is transmitted from the differential mechanism F to the front axle.

Next, the hydraulic control circuit will be described with reference to FIGS. 4 to 6. This hydraulic control circuit includes the torque converter B in the continuously variable transmission Z and the forward clutch 16 of the forward / reverse switching mechanism C. And reverse clutch
This is for supplying controlled hydraulic pressure to 17, the primary hydraulic chamber 27 that operates the primary pulley 21 of the belt transmission mechanism D, and the secondary hydraulic chamber 37 that operates the secondary pulley 31. The source of the original pressure of the entire hydraulic circuit is the oil pump 40 driven by the engine A.
Is.

The hydraulic control circuit includes a pressure regulating valve 41 for regulating the line pressure, a pressure reducing valve 42, a gear ratio control valve 43, a fail-safe gear ratio holding valve 44, a variable valve 45,
A clutch valve 46, a manual valve 47, a converter relief valve 48, an accumulator control valve 49, a lockup shift valve 50, a lockup control valve 51 and the like are provided.

The gear ratio control valve 43 is directly controlled by the primary duty solenoid valve 52, and the gear ratio hold valve 44 is directly controlled by the on / off type solenoid valve 53. The variable pressure valve 45 is directly controlled by the duty solenoid 54 and controls the pressure regulating valve 41. The lockup shift valve 50 and the lockup control valve 51 are controlled by an on / off type solenoid valve 55 and a duty solenoid valve 56.

The hydraulic oil discharged from the oil pump 40 is
First, the pressure is adjusted to a predetermined line pressure by the pressure adjusting valve 41 and then supplied to the secondary hydraulic chamber 37 via the line 101 to form a belt pressing pressure of the secondary pulley 31. Further, the line pressure is supplied to the clutch valve 46 through the line 102, where the line pressure is adjusted (reduced) to a predetermined pressure and then sent to the manual valve 47 through the line 103.

The decompression valve 42 decompresses the line pressure to generate the original pressure of the pilot pressure of the variable pressure valve 45, the gear ratio control valve 43, and the gear ratio hold valve 44 on the line 104.
From this source pressure, the pilot pressure of the variable pressure valve 45 is generated by the duty solenoid valve 54 that is opened and closed with the duty ratio according to the engine output torque and the gear ratio, and the hydraulic pressure (modifier pressure) regulated by the variable pressure valve 45 is generated. The pilot pressure is supplied to the pressure regulating valve 41 through the line 112, and the line pressure corresponding to the output torque and the transformation ratio of the engine is obtained.

The gear ratio control valve 43 is controlled by the brimary / duty solenoid valve 52 to derive the hydraulic pressure for operating the primary pulley 21 from the line pressure supplied through the orifice 61 onto the line 105. The hydraulic pressure on the line 105 is supplied to the primary hydraulic chamber 27 through the gear ratio hold valve 44 and the line 106.

The gear ratio hold valve 44 is controlled by an off-drain type on / off type solenoid valve 53 which is in a drain state when not excited. When the solenoid valve 53 is in the on (excited) state, the line 106 communicating with the primary hydraulic chamber 27 communicates with the line 105, and in the off (non-excited) state, the communication between the lines 105 and 106 is blocked. That is, in the non-excited state of the solenoid valve 53,
The pressure in the primary hydraulic chamber 27 is maintained and the gear ratio is fixed.

If the primary duty solenoid valve 52 is in the ON state when the solenoid valve 53 is energized and the transformation ratio hold valve 44 connects the lines 105 and 106, The hydraulic oil of the relief balls 6 from the lines 106, 105 and 107.
The oil is drained through 0 and no oil pressure is generated in the primary oil pressure chamber 27. On the other hand, in the OFF state of the primary duty solenoid valve 52, the line 107 that is the drain passage is closed, and the line pressure enters the speed change ratio control valve 43 through the orifice 61 and passes through the lines 105 and 106 to the primary hydraulic chamber 27. Will be introduced in. Therefore, the gear ratio control valve 43 opens at an opening ratio according to the duty ratio of the primary duty solenoid valve 52. In this case, the hydraulic oil is supplied into the primary hydraulic chamber 27 via the orifice 61, so that a rapid pressure increase in the primary hydraulic chamber 2 is prevented.

In the forward drive state, the hydraulic pressure (clutch pressure) reduced by the clutch valve 46 is supplied to the forward clutch 16 through the line 103, the manual valve 47 and the line 108, the forward clutch 16 is engaged, and the hydraulic pressure of the reverse clutch 107 is changed. It is opened through line 109.
On the other hand, in reverse, the lockup control valve
As long as 51 is in the non-locked-up state, clutch pressure is supplied to the reverse clutch 17 through the line 103, the manual valve 47, the lines 110 and 109 to engage the reverse clutch 17, and the hydraulic pressure of the forward clutch 16 is released through the line 108. To be done. Accumulators 62 and 63 whose back pressure is controlled by an accumulator control valve 49 are connected to the lines 108 and 109, respectively.

That is, the back pressure chambers of the accumulators 62 and 63
The output pressure of the accumulator control valve 49 is supplied to 62a and 63a. As the pilot pressure of the accumulator control valve 49, the control pressure on the line 112 downstream of the variable valve 45, that is, the pressure regulating valve 41 is controlled. Pilot pressure is introduced. As described above, the variable valve 45 is controlled by the duty solenoid valve 54 which is opened and closed with a duty ratio according to the engine output torque and the variable ratio. Therefore, the accumulator control valve 49 is provided on the lines 108 and 109. By controlling the back pressure of the accumulators 62 and 63, the rack pressure for engaging the clutches 16 and 17 is generated with a level corresponding to the output torque and the gear ratio of the engine, thereby reducing the engagement shock in the clutches 16 and 17. ing.

On the other hand, excess oil generated by the line pressure adjusting operation of the pressure adjusting valve 41 is discharged from the discharge port to the line.
The hydraulic oil discharged onto 114, supplied to the converter relief valve 48, and led out from the valve 48 to the line 115 together with the hydraulic oil supplied from the clutch valve 46 to the line 115 via the line 116 and the orifice 82. It is supplied to the torque converter B. When the oil pressure in the torque converter B is going to rise above a predetermined value, the converter relief valve 48 relieves the working oil to prevent the oil pressure from rising.

The lockup control mechanism of the torque converter B is a normal lockup mechanism including a lockup shift valve 50 and a lockup control valve 51, an on / off type solenoid valve 55 and a duty solenoid valve 56. The hydraulic oil is supplied to the converter rear chamber 7a of the torque converter B through the line 120, and the hydraulic oil in the converter rear chamber 7a is guided to the oil cooler 64 through the line 121. Also, line 122
Through the line 122, hydraulic pressure is supplied to the converter front chamber 10 through the pipe, and the hydraulic oil in the converter front chamber 10 is discharged through the line 122, whereby the lock-up piston 6 comes into contact with the pump cover 7 and is integrated therewith. It is supposed to be done.

The overall structure of the hydraulic control circuit of the continuously variable transmission including the pressure reducing valve according to the present invention has been described above. Next, the structure of the pressure reducing valve 42 will be described in more detail with reference to FIG.

In FIG. 1, the pressure reducing valve 42 is a land 65.
a spool 65 provided with a and 65b slidably provided in the valve cylinder 66, and the spool 65 is compressed between the right end of the land 65b of the spool 65 and the right end of the valve cylinder 66 to move the spool 65 to the left. Energizing spring 67 and valve cylinder
A pilot pressure chamber 68 provided at the left end of 66. Further, the input port 42a to which the high line pressure of the line 101 is supplied, the output port 42b to supply the reduced output pressure to the line 104, and the output pressure to the pilot pressure chamber 68 are fed back through the orifice 69. The feedback port 42c and the drain port 42d are provided. Furthermore, between the input port 42a and the feedback port 42c,
It has an output supply port 42e to which the output pressure is directly supplied without passing through an orifice.

In the above construction, the output pressure is the spring
When the set pressure based on the urging force of 67 is maintained, the urging force of the spring 67 and the hydraulic pressure in the pilot pressure chamber 68 are balanced, and the spool 65 has the output port 42b at the input port 42
The state in which neither the a nor the drain port 42d is in communication (the upper half state in FIG. 1) is maintained, but when the output pressure falls below a predetermined value, the hydraulic pressure in the pilot pressure chamber 68 becomes a spring.
Since the force becomes lower than the biasing force of 67, the spool 65 moves to the left in the figure, so that the output port 42b communicates with the input port 42a. Therefore, the line pressure is introduced into the output port 42b and the output pressure rises. As a result, the hydraulic pressure in the pilot pressure chamber 68 becomes higher than the urging force of the spring 67, the spool 65 moves to the right in the figure, the input port 42a is closed, and the output port 42b is connected to the drain port 42d. From (state of the lower half of FIG. 1), the output pressure decreases. Then, by repeating such an operation, the spring 67
A constant reduced output pressure (reducing pressure) is obtained according to the urging force of.

In this case, as is apparent from FIG. 1, between the input port 42a to which the line pressure is supplied and the feedback port 42c to which the output pressure is fed back to the pilot pressure chamber 68 via the orifice 69, Since the output pressure supply port 42e is provided, the input port
From 42a, the hydraulic oil flows through the gap between the inner peripheral surface of the valve cylinder 66 and the outer peripheral surface of the spool 65 into the pilot pressure chamber.
Leakage into the inside of 68 is prevented, and thus a highly accurate pressure reducing function by the pressure reducing valve 42 is obtained.

Although the pressure reducing valve 42 is applied to the hydraulic control circuit of the belt type continuously variable transmission in this embodiment,
It will be easily understood that the present invention is not limited to this, and can be applied to pressure reducing valves of various other hydraulic control circuits.

[Brief description of drawings]

FIG. 1 is a diagram showing a structure of a pressure reducing valve according to the present invention.

FIG. 2 is a skeleton diagram showing a mechanical configuration of a belt type continuously variable transmission controlled by a hydraulic control circuit having a pressure reducing valve according to the present invention.

FIG. 3 is a diagram showing a specific configuration of a torque converter, a forward / reverse switching mechanism, and a primary pulley of the continuously variable transmission.

FIG. 4 is a diagram showing a specific configuration of a secondary pulley of the continuously variable transmission and a left side portion of a hydraulic control circuit.

FIG. 5 is a diagram showing a central portion of the hydraulic control circuit.

FIG. 6 is a diagram showing a right side portion of the hydraulic control circuit.

[Explanation of symbols]

 6 Lockup piston 7 Pump cover 7a Converter rear chamber 10 Converter front chamber 16 Forward clutch 17 Reverse clutch 20 Belt 21 Primary pulley 22 Primary shaft 27 Primary hydraulic chamber 31 Secondary pulley 32 Secondary shaft 37 Secondary hydraulic chamber 41 Pressure regulating valve 42 Pressure reducing valve 43 Gear ratio control valve 44 Gear ratio hold valve 45 Transformer valve 46 Clutch valve 47 Manual valve 48 Converter relief valve 49 Accumulator control valve 50 Lockup shift valve 51 Lockup control valve 52, 54, 56 Duty solenoid valve 53, 55 On / Off type solenoid valve

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location F16H 59:36 8207-3J 63:04 9138-3J

Claims (4)

[Claims] 1. An input port to which a source pressure is supplied, an output port for generating an output pressure reduced from the source pressure to a predetermined pressure, and a feedback port to which the output pressure is supplied to one end of a spool. In the pressure reducing valve, between the input port and the feedback port,
A pressure reducing valve comprising an output pressure supply port to which the output pressure is supplied. 2. The source pressure supplied to the input port is a line pressure generated by regulating the pump hydraulic pressure by a pressure regulating valve, and the output pressure generated from the output port is included in a hydraulic pressure control circuit. The pressure reducing valve according to claim 1, wherein the pressure reducing valve is used as a source pressure of a pilot pressure of another pressure regulating valve. 3. A hydraulic pressure for a belt type continuously variable transmission, wherein the hydraulic pressure control circuit includes two pulleys whose effective diameter is controlled to be changed by hydraulic pressure, and a belt suspended between the two pulleys. The pressure reducing valve according to claim 2, comprising a control circuit. 4. The pressure reducing valve according to claim 3, wherein the hydraulic chamber that generates a pressing pressure that presses the pulley against the belt is a single-chamber hydraulic chamber.