JPH0861495A - Hydraulic control device for automatic transmission - Google Patents

Abstract

PURPOSE: To provide a hydraulic control device for an automatic transmission which reduces the driving force of a spool valve and the number of part items, and can be miniaturized. CONSTITUTION: Spool valves 2, 3, 4, 5, 6, 7, 8 and a cam shaft 1 are stored in a housing 28 of an Integrated valve 60. When the spool valve 5 is illustrated, three small holes 5e are provided at the bottom part of the spool valve 5 on the cam shaft 1 side to reduce the driving force of the spool valve 5. Annular grooves 5h, i are formed on the outer circumferential wall of the spool valve 5 to prevent the hydraulic lock. In addition, the cam ruggedness is formed so that the radius of curvature of the cam ruggedness of the cam shaft 1 with which a tip part 17a of a pin 17 to push up the spool valve 5 is brought into contact may be larger than the radius of curvature of the tip part 17a, to allow the cam surface of the cam shaft 1 is smoothly slid without the pin 17 being hooked. Other spool valves 2, 3, 4, 6, 7, 8 are of the same constitution as that of the spool valve 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic control device for an automatic transmission, which hydraulically controls a speed change mechanism of the automatic transmission.

[0002]

2. Description of the Related Art Conventionally, automatic transmissions often used for vehicles or the like control hydraulic pressure by hydraulic valves to control each friction engagement device in order to smoothly transmit rotational driving force according to load. Shift control is being performed. The shift control is performed manually by a select lever that allows the occupant to select an arbitrary gear position to some extent, and by an engine control computer that automatically determines the friction engagement device based on the engine throttle opening and vehicle speed so that the gear ratio is appropriate. Control. In order to smoothly transmit the rotational drive force according to the load,
The shift control is realized by controlling the hydraulic pressure of each friction engagement device of the automatic transmission with a hydraulic circuit using a plurality of hydraulic valves, accumulators, solenoid valves and the like. In such a configuration, since hydraulic valves are required for the number of friction engagement devices in the automatic transmission, the device becomes large and requires many parts, and the device is complicated and the manufacturing cost is high. is there.

In order to solve such a problem, it is conceivable to reduce the size, weight and simplification of the device by using an integrated valve in which a plurality of hydraulic valves are integrated in one place. In this thing, by the fail system of the engine control computer,
Even if the automatic control function of the electronic control fails, the occupant can operate the select lever to select forward or reverse, and to a certain extent, select a shift speed when moving forward.

[0004]

However, in the hydraulic control device that uses the spool valve as the hydraulic valve for controlling the automatic shift by such a conventional integrated valve, there are the following problems. When the pin that pushes up the spool valve climbs the cam crest formed on the cam shaft as the cam shaft moves in the axial direction or the rotation direction, the pin is likely to be caught in the cam crest, which may hinder the sliding of the pin.

With one communication hole provided at the end of the spool valve for reducing the force for driving the spool valve, the opening area required cannot be obtained even if the hole has a large diameter due to the space at the end of the spool valve. Therefore, the force for driving the spool valve cannot be sufficiently reduced. The annular groove provided on the outer periphery of the spool valve to eliminate the pressure imbalance caused by the oil leaking between the spool valve and the cylindrical hole in which the spool valve slides allows the seal length between the hydraulic communication passages closed by the spool valve to be increased. Since the length becomes shorter, the amount of oil leakage between the hydraulic communication passages increases.

The present invention has been made to solve such a problem, and an object thereof is to provide a hydraulic control device for an automatic transmission which reduces the driving force of a spool valve and has a small number of parts. And

[0007]

A hydraulic control device for an automatic transmission according to claim 1 of the present invention for solving the above-mentioned problems provides a plurality of hydraulic pressures applied to a plurality of friction engagement elements provided in the automatic transmission. A hydraulic control device for an automatic transmission, which performs switching control with a hydraulic valve of 1. and controls switching of a plurality of shift stages by engaging or disengaging the plurality of friction engagement elements, each of the plurality of friction engagement elements being provided. An integrated valve having a plurality of hydraulic valves for switching the hydraulic pressure applied to the friction engagement element, a cam for transmitting a driving force to the plurality of hydraulic valves, an automatic switching means for driving and controlling the cam by automatic control, and a manual operation With a manual switching means for driving and controlling the cam,
A radius of curvature of a contact portion of the plurality of hydraulic valves that contacts the cam is smaller than a radius of curvature of a cam surface that contacts the contact portion of the cam.

According to a second aspect of the present invention, there is provided a hydraulic control device for an automatic transmission, wherein the hydraulic pressure applied to a plurality of friction engagement elements provided in the automatic transmission is switched and controlled by a plurality of hydraulic valves.
An oil pressure control device for an automatic transmission, which controls switching of a plurality of shift stages by engaging or disengaging the plurality of friction engaging elements, and switches an oil pressure applied to each friction engaging element of the plurality of friction engaging elements. An integrated valve having a plurality of hydraulic valves, a power transmission member that transmits a driving force to the plurality of hydraulic valves, an automatic switching unit that drives and controls the power transmission member by automatic control, and a power transmission member that is manually operated. And a manual switching means for controlling the drive, the hydraulic valve,
It is characterized by having a plurality of passages that connect the high-pressure side and the low-pressure side.

Further, according to a third aspect of the present invention, there is provided a hydraulic control device for an automatic transmission, wherein the hydraulic pressure applied to a plurality of friction engagement elements provided in the automatic transmission is switched and controlled by a plurality of hydraulic valves to provide a plurality of frictions. A hydraulic control device for an automatic transmission, which controls a plurality of shift stages by engaging or disengaging a fastening element, wherein a plurality of spool valves for switching a hydraulic pressure applied to each of the plurality of friction fastening elements is provided. An integrated valve, a power transmission member that transmits a driving force to the plurality of spool valves, an automatic switching unit that drives and controls the power transmission member by automatic control, and a manual that controls and drives the power transmission member by manual operation. A switching means, a groove formed in the outer peripheral surface of the spool valve in the circumferential direction, and a plurality of hydraulic ports formed in the valve housing of the integrated valve, A plurality of ports that can selectively communicate with the input port of the spool valve, and when the port of any one of the plurality of ports communicates with the input port of the spool valve, the groove is It is characterized by being placed in the port.

Further, according to a fourth aspect of the present invention, there is provided a hydraulic control device for an automatic transmission, wherein hydraulic pressures applied to a plurality of friction engagement elements provided in the automatic transmission are switched and controlled by a plurality of hydraulic valves, and the plurality of hydraulic valves are controlled. What is claimed is: 1. A hydraulic control device for an automatic transmission, which controls switching between a plurality of shift stages by engaging or disengaging a friction engaging element, wherein a plurality of hydraulic pressures that switch the hydraulic pressure applied to each friction engaging element of the plurality of friction engaging elements. An integrated valve having a valve, a cam for transmitting a driving force to the plurality of hydraulic valves, an automatic switching means for drivingly controlling the cam by automatic control, a manual switching means for drivingly controlling the cam by manual operation, A biasing means for biasing the hydraulic valve in the direction of pressing the hydraulic valve against the cam surface of the cam, and a ball abutting the cam for transmitting the displacement amount of the cam to the hydraulic valve are provided. The features.

[0011]

According to the hydraulic control device for an automatic transmission according to claim 1 of the present invention, the radius of curvature of the contact portion of the hydraulic valve which contacts the cam for switching the plurality of hydraulic valves is in contact with the contact portion. Since it is smaller than the radius of curvature of the cam surface,
The contact portion and the cam surface do not come into contact with each other at two or more points, and it is possible to prevent the contact portion and the cam surface from being caught. This has the effect that the contact portion can smoothly slide on the cam surface.

According to the hydraulic control device for an automatic transmission of the second aspect of the present invention, since the hydraulic valve has a plurality of passages that connect the high pressure side and the low pressure side of the hydraulic valve, the pressure oil filled in the hydraulic valve is high. Can be released from the plurality of communication holes to the low pressure side, and the pressure due to the hydraulic pressure inside the hydraulic valve and the hydraulic pressure acting on the surface of the hydraulic valve bottom can be balanced. This has the effects of improving the responsiveness of the hydraulic valve and reducing the driving force of the hydraulic valve.

According to the hydraulic control device for an automatic transmission according to claim 3 of the present invention, when the input port of the spool valve and any one of the plurality of ports formed in the valve housing communicate with each other, the spool valve Grooves formed in the circumferential direction on the outer peripheral surface are located so as to be located inside other ports of multiple ports, eliminating pressure imbalance without increasing the amount of oil leakage between multiple ports. Has the effect of enabling.

According to the hydraulic control device for an automatic transmission according to claim 4 of the present invention, since the ball is located between the cam and the hydraulic valve for switching the plurality of hydraulic valves, the ball rotates on the cam surface. This has the effect of pushing up the hydraulic valve and reducing the frictional force between the ball and the cam surface. Further, since the frictional force between the ball and the cam surface is reduced, there is an effect of reducing the driving force for driving the cam.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) FIG. 3 shows a system configuration in which the hydraulic control device for an automatic transmission according to the present invention is applied to an automatic transmission for a vehicle (hereinafter referred to as "AT"). In FIG. 3, EV represents a solenoid valve and MV represents an integrated valve.

As is well known, in the operation of the vehicle AT, the gear connection in the transmission 300 is automatically or manually switched, and the rotational force from an engine (not shown) connected to the torque converter 200 is applied to the rear wheels or front wheels of the vehicle. Transmitted. The integrated valve 60 and the entire peripheral device thereof are inside an oil pan (not shown) inside the AT under the transmission 300, and the periphery of the hydraulic control device 400 inside the oil pan serves as a drain of the hydraulic circuit.

A well-known hydraulic pump 56 which is directly connected to the rotary shaft of the engine and is rotationally driven is provided in the transmission 300, and the drive oil discharged from each hydraulic device to an oil pan or the like is supplied from an intake port 57. It sucks and supplies pressure oil to each device through the line pressure control valve 64. The pressure oil from the hydraulic pump 56 is a variable high pump oil pressure and is a line pressure control valve 6 which is an electromagnetic control type pressure control valve.
It is controlled to a constant high line pressure by 4 and supplied to each hydraulic equipment. The hydraulic control device 400 is provided with two engagement hydraulic control valves 61 and 62.
00 to supply pressure oil to the integrated valve 60 by arbitrarily controlling the line pressure of the pressure oil supplied from the line pressure control valve 64 to a predetermined control pressure required when engaging each friction engagement device described later. are doing.

The pressure oil of the line pressure or the control pressure supplied to the integrated valve 60 is used for the spool valves 2, 3, 4, shown in FIG.
Through the communication ports 39, 40, 41,
Transmission 300 from 42, 43, 44, 45
Multi-disc clutches C0, C1, C, which are friction engagement devices
2 and multi-disc brakes B0, B1, B2, B3. Each friction engagement device is a transmission 300
The gears are connected to gears forming respective gear ratios such as a planetary gear (not shown) therein, and by engaging or disengaging these friction engagement devices, the gear ratios are switched to perform gear shift control of the vehicle.

The connecting portion 11 is mechanically connected to a select lever 500 which allows the operator to manually operate the driving state of the vehicle such as forward, backward, neutral and parking. The pressure oil supplied from the line pressure control valve 64 is further supplied to the torque converter 200 via the lockup hydraulic control valve 65 in order to further perform lockup (L / U) slip control of the torque converter 200.

Next, the structure of the integrated valve 60 will be described.
As shown in FIGS. 1 and 2, a cylindrical camshaft 1 made of, for example, aluminum is provided in a recess 58 provided at the substantially center of the housing 28. The camshaft 1 has bearings 9, 29. Is supported so as to be rotatable and axially reciprocable. As the bearings 9 and 29, it is preferable to use, for example, a sliding bearing, a ball bearing, a roller bearing, a rolling bearing, or the like. The bearing 9 is press-fitted and fixed to one end of the housing 28, and the bearing 29 is press-fitted and fixed to the side housing 30 attached to the other end of the housing 28.
Concavities and convexities are formed on the outer peripheral surface of the main part of the cylindrical cam shaft 1 as cams for driving the spool valves 2, 3, 4, 5, 6, 7, 8. As will be described later, the unevenness of the cam shaft 1 is slightly displaced, for example, at a position where the pin 14 that is located between the spool valve 2 and the cam shaft 1 and pushes up the spool valve 2 contacts the outer peripheral surface of the cam shaft 1. Camshaft 1
The outer peripheral surface of the pin 14 is formed in a shape capable of smoothly sliding. In addition, each spool valve 2, 3, 4, 5, 6,
By making the heights of the concavities and convexities of the camshaft 1 corresponding to 7 and 8 respectively equal, it is possible to share the members that form the seven spool valves, and it is possible to reduce the cost.

Gear teeth 53 having a predetermined arc width and a predetermined axial length are formed on the circumferential surface of the cam shaft 1 near the bearing 9 on the side of the spool valves 6, 7 and 8 opposite to the cam surface. There is.
A step motor 12 having a rotary shaft parallel to the axial direction of the cam shaft 1 is fixed at a position opposed to the gear teeth 53. One end of a spiral return spring (not shown) is fixed to the shaft of the step motor 12, and the other end is fixed to the housing of the step motor 12. This return spring is used for the AT ECU 70 shown in FIG. 3 when an abnormality occurs in the drive control of the step motor 12.
Serves to shift the camshaft 1 to the fail-safe position, for example, the fourth speed mode position, by the restoring force of the return spring in order to make the step motor 12 free.

The bearings 9 and 29 support the cam shaft 1 so as to be rotatable and movable in parallel in the axial direction. Camshaft 1
The end portion of the bearing 9 side of the is provided with a connecting portion 11 that is mechanically connected to an externally provided select lever 500 shown in FIG. 3 via a link (not shown). By operating the connecting part 1
Reference numeral 1 drives the camshaft 1 in the axial direction in conjunction with the select lever 500.

A gear 53 meshing with a part of the circumferential surface of the camshaft 1 via a gear 52 in the middle of the gear 13 of the motor.
And has a cam 1 driven by the rotation of the step motor 12.
Rotates. At this time, the load of the step motor 12 can be reduced and the size of the step motor 12 can be reduced by setting the gear ratio so as to reduce the rotation of the step motor 12 and providing the speed reducing mechanism for amplifying the torque.

As shown in FIGS. 1 and 2, the spool valves 2, 3, 4, 5, 6, 7, 8 (collectively referred to as “spool valve SP” hereinafter) for switching the oil passages are the shafts of the camshaft 1. Are arranged side by side on both sides of the camshaft 1 in a direction perpendicular to the. The spool valve SP has cylindrical holes 28a, 28b, 28c, 28d, 28 provided in the housing 28, respectively.
e, 28f and 28g are slidably inserted in the axial direction.

The line pressure ports 35 and 37 provided in the housing 28 have line pressure communication passages 46 and 51, respectively.
Is connected to the line pressure control valve 64 shown in FIG.
The line pressure, which is high-pressure oil, is supplied to the line pressure ports 35 and 37 via the. The line pressure communication passage 46 has a cylindrical hole 2 in the housing 28 into which the spool valves 2, 3, 4, 5 are inserted.
8d, 28c, 28b, 28a are provided so as to supply line pressure, respectively, and the line pressure communication passage 51 is connected to the cylindrical holes 28g, 28f, 28e of the housing 28 into which the spool valves 6, 7, 8 are inserted. It is provided to supply pressure.

Further, in the housing 28, pressure control ports 36, 38 to which a pressure-adjusted engagement hydraulic pressure (or control pressure) is supplied are provided, and the pressure control ports 36, 38 are provided.
Control pressure communication passages 47, 50 are provided in parallel with the line pressure communication passages 46, 51. The control pressure communication passages 47 and 50 are similar to the line pressure communication passages 46 and 51.
It is possible to communicate with each spool valve SP. Pressure control port 3
Since the reference numerals 6 and 38 do not communicate with each other in the side housing 30, the engagement hydraulic pressure supplied to the pressure control port 36 via the engagement hydraulic pressure control valve 61 is able to communicate with the control pressure communication passage 47. The engagement hydraulic pressures supplied to the pressure control ports 38 through the engagement hydraulic pressure control valves 62 are supplied to the spool valves 6, 7, 8 which can communicate with the control pressure communication passages 50. .

Further, in the housing 28, a drain pressure communication passage 4 connected to drain ports 54 and 55 communicating with a drain (not shown) provided outside the housing 28.
Reference numerals 8 and 49 are provided in parallel with the control pressure communication passages 47 and 50. Next, the structure of the spool valve SP will be described by taking the spool valve 5 as an example. The other spool valves have the same structure as the spool valve 5.

As shown in FIG. 4, the spool valve 5 has a cylindrical shape with a bottom, and is formed inside the spool valve 5 and an annular groove 5a formed near the central portion of the outer surface of the spool valve 5. The inner cylindrical portion 5c having a cylindrical shape and the inner cylindrical portion 5
It has a hole portion 5b formed so as to connect the c and the groove 5a. When the spool valve 5 slides in the cylindrical hole 28a, depending on the slide position, the hole 5b
Each of the line pressure communication passages 4 communicating with the cylindrical hole 28a.
6, it communicates with the control pressure communication passage 47 and the drain pressure communication passage 48. Similarly, the other spool valves 2, 3, 4,
Holes (not shown) formed in 6, 7, and 8 are cylindrical holes 28.
b, 28c, 28d, 28e, 28f, 28g, and line pressure communication passages 46 and 51, control pressure communication passages 47 and 50, and drain pressure communication passages 48 and 49. The inner cylindrical portion 5c formed in the spool valve 5 is open at one end and communicates with a communication port 42 provided in the port case 32. Similarly, the inner cylindrical portion 2c formed in the other spool valve 2, 3, 4, 6, 7, 8
3c, 4c, 6c, 7c and 8c are port cases 31 and 3
2 communication ports 39, 40, 41, 43, 4
4 and 45 communicate with each other.

The camshaft 1 and each spool valve SP
End face of the unopened side bottom part (5 in the spool valve 5 shown in FIG. 4)
(represented by d) between the pins 14, 15, 16, 17, 1 slidably in the direction perpendicular to the axis of the camshaft 1.
8, 19, and 20 are fitted into the housing 28 to transmit the movement of the cam of the camshaft 1 to each spool valve SP.
In accordance with the movement of the camshaft 1, the spool valve SP has the cylindrical holes 28a, 28b, 28c, 28d, 29e, 28.
Pin 1 so that it slides smoothly in f and 28g.
Small holes (represented by 5e in the spool valve 5 shown in FIG. 5 and FIG. 6) for pressure relief are provided on each unopened side of the spool valve SP with which 4, 15, 16, 17, 18, 19, and 20 hit.
It is provided in the place.

As shown in FIGS. 5 and 6, the small hole 5e provided in the spool valve 5 has an inner circumference that contacts the outer circumference of the bottom surface 5f, and the bottom wall 5 extends radially outward from the bottom surface 5e.
penetrates g. Similarly, the other spool valves 2, 3,
Small holes 2e, 3e, 4e, 6e, 7 in 4, 6, 7, 8
e and 8e are formed. These small holes 2e, 3e, 4
Since the oil filled in the spool valve SP is released to the low pressure depression 58 by e, 5e, 6e, 7e, and 8e, the pressure due to the hydraulic pressure in the spool valve SP and the hydraulic pressure acting on the surface of the spool valve unopened side bottom part Can be balanced, and the force for driving the spool valve SP is reduced.
The locations where the small holes 2e, 3e, 4e, 5e, 6e, 7e, and 8e are formed are not limited to three locations, and the pressure due to the hydraulic pressure in the spool valve SP and the hydraulic pressure acting on the bottom surface of the spool valve unopened side It may be provided at a plurality of locations depending on the balance with the above.

All the spool valves SP are springs 21,
Pins 1 by 22, 23, 24, 25, 26, 27
4, 15, 16, 17, 18, 19, 20 are pressed against the camshaft 1 side, and port cases 31, 32
The cylindrical holes 28a, 28
b, 28c, 28d, 28e, 28f, 28g.

As shown in FIGS. 6 and 7, on the outer peripheral wall of the spool valve 5, annular grooves 5h and 5i are formed. The annular grooves 5h and 5i are for eliminating hydraulic lock caused by the imbalance of the oil flowing through the gap between the outer peripheral wall of the spool valve 5 and the inner peripheral wall of the cylindrical hole 28a. The position where this annular groove is formed is determined as follows.

For example, as shown in FIG. 7A, the cylindrical hole 28
The line pressure communication passage 46 opening to a and the groove 5 of the spool valve 5
The position of the annular groove 5h is determined so that the annular groove 5h is located in the control pressure communication passage 47 when the spool valve 5 is stopped at a position in which the annular valve 5a is communicated with a, and the annular groove 5i is located in the drain pressure communication passage 48. The position of the annular groove 5i is determined so that

The annular groove 5 thus positioned
In h and 5i, since the distance between the line pressure communication passage 46 and the control pressure communication passage 47 and the distance between the control pressure communication passage 47 and the drain pressure communication passage 48 are substantially equal, the spool valve 5 communicates with the control pressure communication passage 47 and the groove 5a. When moved to the position where the drain pressure is established, the annular groove 5h is located in the drain pressure communication passage 48. Therefore, the spool valve 5 as shown in FIG.
The annular grooves 5h and 5i are provided in the line pressure communication passage 46, the control pressure communication passage 47, and the drain pressure communication passage 4 except during the movement in the inside.
8 will be located in the opening. That is,
When the spool valve 5 is stopped, the line pressure communication passage 4
6, the control groove 47, the control pressure communication passage 47, the drain pressure communication passage 48 any two two, the annular groove 5h, 5 on the outer peripheral wall of the spool valve 5.
Since i is not formed, even though the annular grooves 5h and 5i are formed on the outer peripheral wall of the spool valve 5, there is no problem between adjacent communication passages, for example, the control pressure communication passage 47 and the drain pressure communication passage 4.
There is no effect on the seal length for sealing between the control pressure communication passage 47 and the drain pressure communication passage 8, and the amount of oil leakage between the control pressure communication passage 47 and the drain pressure communication passage 48 does not increase.

Similarly, the other spool valves 2, 3, 4, 6,
An annular groove (not shown) is formed on the outer peripheral wall of each of the spool valves SP and SP without increasing the amount of oil leakage between the line pressure communication passage 46, the control pressure communication passage 47, and the drain pressure communication passage 48.
It is possible to eliminate hydraulic lock when moving.
Next, the flow of each pressure oil with respect to the moving position of each spool valve SP will be described. Each spool valve SP is a camshaft 1
Drive the cylindrical holes 28a, 28b, 28c, 28d,
When moving 28e, 28f, 28g, each cylindrical hole 28
a, 28b, 28c, 28d, 29e, 28f, 28g
Line pressure communication passage 46 or line pressure communication passage 5 opening to the
When the groove and the hole of each spool valve SP are positioned at the position opposite to the position of 1, the pressure oil of the line pressure supplied to the line pressure communication passage 46 or the line pressure communication passage 51 causes the groove and the hole of each spool valve SP to move. Is supplied to the inner cylindrical portion of the spool valve SP via the communication ports 39, 40, 41,
Pressure oil of line pressure is supplied to each friction engagement device via 42, 43, 44, and 45.

Similarly to the line pressure oil, the pressure-adjusted engagement oil pressure (or control pressure) pressure oil is supplied from the pressure control ports 36 and 38 to each spool valve SP, and the spool valve SP is opened. The pressure oil is supplied to each friction engagement device via the friction engagement device. The engagement hydraulic pressure supplied from the engagement hydraulic pressure control valve 61 to the pressure control port 36 is supplied to the spool valves 2, 3, 4, 5 as described above. Similarly, the engagement hydraulic pressure supplied from the engagement hydraulic pressure control valve 62 to the pressure control port 38 is supplied to the spool valves 6, 7, 8. As a result, the engagement hydraulic pressure supplied from the engagement hydraulic control valve 62 is supplied to the multi-disc brakes B1, B0, B2, and the engagement hydraulic pressure supplied from the engagement hydraulic control valve 61 is the multi-disc brake B3 and the multi-disc brake. It will be supplied to the clutches C0, C2, C1.

The groove of the spool valve SP has the drain pressure communication passage 4
When positioned at a position communicating with 8, 49, pressure oil in the friction engagement device communicating with the spool valve SP is discharged from the drain ports 54, 55 to the outside of the housing 28. As shown in FIG. 3, the communication ports 39, 40, 41, 42, 43, which are connected to the transmission 300,
Of the ports 44 and 45, the ports 40 and 44, which communicate with the multi-disc clutch C0 and the multi-disc brake B0 installed in the transmission 300, respectively, from the internal structure when the ports are operated simultaneously, the transmission 3
00 may become inoperable and may be damaged. To prevent simultaneous coupling, the double coupling prevention valve 6
3 intervenes. Other communication ports, such as those found in known transmissions, are engaged or disengaged with other multi-plate clutches and brakes by hydraulic pressure from the communication port to switch the connection states of a plurality of gears for gear shifting in the transmission 300. , AT control is performed. The brakes are substantially the same friction elements as the clutch, and the brake has a structure in which one side of the clutch is fixed to the body of the transmission.

Next, the control of the camshaft 1 and the cam unevenness formed on the outer peripheral surface of the camshaft 1 will be described. The circumferential position of the camshaft 1 shown in FIG.
Is controlled by an instruction from the ECU 70 for AT shown in
The step motor 12 rotates the camshaft 1, and the cam provided on the circumferential surface of the camshaft 1 causes the pin 1 to move.
The position of the spool valve SP is controlled via 4, 15, 16, 17, 18, 19, 20 and thereby the spool valve SP
A groove provided in the communication line communicates with the line pressure communication passages 46, 51, the control pressure communication passages 47, 50, and the drain pressure communication passages 48, 49 so that a predetermined hydraulic pressure is applied to each of the communication ports 39, 40, 41, 42, 43 ,.
It is transmitted to 44 and 45.

The camshaft 1 is provided with the same diameter portion with a predetermined width in the circumferential direction and the axial direction from the contact position with the pins 14, 15, 16, 17, 18, 19, 20 in a certain operation mode. The position of the spool valve SP does not change even if the camshaft 1 is driven in the rotational direction or the axial direction and moves in a small range. For this reason, a slight deviation is allowed in the positioning of the camshaft 1. Accordingly, it is not necessary to control the drive stop position in the rotation direction or the axial direction with high accuracy. Furthermore, when the camshaft 1 makes a full stroke in the rotation direction or the axial direction, the pins 14, 1
A slight margin is provided between the side surfaces of 5, 16, 17, 18, 19, and 20 and the cam irregularities on the surface of the cam shaft 1 corresponding to the adjacent spool valve.
It is considered that a large force is not applied to the tips of 15, 16, 17, 18, 19, and 20. As shown in FIG. 9B, for example, the magnitude relationship between the radius of curvature R1 of the tip portion 14a of the pin 14 and the radius of curvature R2b of the corner 1b of the cam irregularity on the surface of the camshaft 1 (hereinafter referred to as "cam surface") is shown. R1 <R
By setting to 2b, the pin 14 slides smoothly on the cam surface.

As shown in FIG. 9 (a), the corner portion 1 of the cam irregularity is formed.
When the radius of curvature R2a of a is smaller than the radius of curvature R1 of the pin 14, the tip 14a of the pin 14 contacts the cam surface at two points A and B shown in FIG. 9 (a).
The tip portion 14a of the pin 14 is easily caught on the cam surface. On the other hand, as shown in FIG. 9 (b), by making the radius of curvature R2b of the corner 1b of the cam unevenness larger than the radius of curvature R1 of the pin 14, the tip 14a of the pin 14 contacts the cam surface. This is one point C shown in FIG. 9 (b).
Further, as shown by point D in FIG. 9 (b), even when the pin 14 climbs the convex portion of the cam, the pin 14 and the cam surface are in contact with each other at one point, so that the pin 14 does not get caught on the cam surface and is smooth. It is slidable to ensure normal operation.
Like the pin 14, the other pins 15, 16, 17, 18, 19, and 20 can be slid smoothly without being caught by the cam surface.

As shown in FIG. 8, the AT ECU 70
By a kickdown signal for shifting the gear position to the lower gear at the time of acceleration, a select lever signal indicating which position the select lever 500 is in, and a signal from the engine (E / G) ECU 72 controlling the drive of the engine. , A motor position signal for driving the step motor 12 is output while exchanging data with the E / G ECU 72,
At the same time, the respective hydraulic pressure control signals are sent to the engagement hydraulic pressure control valves 61 and 6 described above.
2, line pressure control valve 64, lockup hydraulic control valve 65
Output to. At this time, the E / G ECU 72 and the AT ECU
The data exchanged with 70 includes the water temperature of the radiator, the throttle opening, the crank angle of the crankshaft, the vehicle speed, the turbine speed, and the like. In addition, since the camshaft 1 is connected to the select lever 500 via the connecting portion 11, the select lever signal is also input to the AT ECU 70.

FIG. 10 shows that in each range of the select lever 500 and each shift range, each spool valve SP communicates with a line pressure port P _S , a drain port D _r , and an engagement hydraulic pressure control valve 61 which communicate with the line pressure control valve. control pressure port P _C1 to the control pressure port P _C2 communicating with the engagement hydraulic pressure control valve 62
FIG. 4 is a diagram showing which of the ports are connected to. The camshaft 1 is connected to the select lever 50 by the connecting portion 11.
Since it is connected to 0, when the position of the select lever 500 is manually selected by the driver, the camshaft 1 moves in the axial direction of the shaft and comes into contact with the camshaft 1 by the unevenness in the axial direction of the camshaft 1. Pins 14, 15, 1
6, 17, 18, 19, 20 by moving each spool valve SP
Control. Further, the step motor 12 is rotated according to a command from the AT ECU 70, and the circumferential position of each spool valve SP is controlled by the circumferential cam unevenness of the cam shaft 1.

FIG. 12 shows D for spool valves 5 and 8
FIG. 6 shows an axial cross-sectional view of the camshaft 1 in the range position, showing the gear position in the fourth speed position. The pins 17 and 18, which are in contact with the spool valves 5 and 8, respectively, have the other ends in contact with the position of the maximum diameter of the camshaft 1, and therefore push up the spool valves 5 and 8 to the maximum. Therefore, the spool valves 5 and 8 are positioned so as to communicate with the line pressure ports 35 and 37 (P _S ), and the multi-plate clutch C1 that communicates with the spool valves 5 and 8
And the hydraulic oil of the line pressure is supplied to the multi-plate brake B2.

From this state, a command from the AT ECU 70 is sent.
According to the rotation of the step motor 12 by_rd),
2nd speed (2_nd) 1st speed (1_st) And the camshaft 1 is 45
The pins 17 and 18 are rotated at intervals of °
It moves along the outer peripheral surface of the camshaft 1. Shown in Figure 12
In the case of the drawing shown, the spool valves 5 and 8 have three_rdAnd 4 _th
Same position in, but 2_ndPin 1 at the gear
8 moves to the intermediate diameter position of the camshaft 1, and the spool valve
8 is moved to a position communicating with the control pressure port 38f,
Pressure oil of the control pressure is applied to the multi-plate brake B2 via the communication port 44.
Supplied. 1 _stSimilarly, in the gear stage of
Enter the port status shown.

Since the cam shaft 1 is connected to the select lever 500 through the connecting portion 11, when the position of the select lever 500 is manually selected by the driver, the cam shaft 1 moves in the shaft axial direction, The spools are controlled by moving the pins 14, 15, 16, 17, 18, 19, 20 contacting the cam shaft 1 by the cam irregularity of the cam shaft 1 in the axial direction. Also select lever 500
Select lever signal corresponding to the selected position of the ECU for AT
It is input to 70. Therefore, cam concavities and convexities are formed on the cam surface of the cam shaft 1 in both the axial direction and the circumferential direction, and the shape of the cam concavities and convexities is designed to be the spool valve position determined by the hydraulic communication mode shown in FIG. ing. The operating states of the clutches and brakes of the AT controlled in this manner are as shown in FIG.

The select lever 500 is sequentially set to 2 (forward second speed), D (forward automatic shift stage), N (neutral),
When shifting to R (back) and P (parking), the camshaft 1 moves in the axial direction by a predetermined distance. Then, as in the case of the rotational movement, the spool valve 5
In and 8, the pressure distribution shown in FIG. 10 is performed. Similar operation is shown in other gears, other ranges, and other spool valves.

Next, the shifting operation at the D range position will be described. The basic operation is the same in other ranges. When the camshaft 1 is in the manual D range position, the spool valve SP is inserted through the pin due to the cam unevenness on the cam surface.
To the communication mode determined by the communication port shown in the D range column of FIG. And E for AT to camshaft 1
Indication of CU70 is, if it is the first speed mode of the four stages of the vehicle speed (1 _st in Fig. 10), FIG. 10, as shown in FIG. 11,
The multi-plate clutch C0 receives the line pressure from the line pressure port (P _{S in} FIG. 10) 35 of FIG. 1 via the line pressure communication passage 46, the groove of the spool valve 3, and the communication port 40 to be in an operating state. Similarly, the multi-disc clutch C1 receives control pressure from the pressure control port (P _{C1 in} FIG. 10) 36 via the control pressure communication passage 47, the groove of the spool valve 5, and the communication port 42, and the control pressure is applied depending on the vehicle speed and the like. The engagement state is controlled by adjusting the combined hydraulic pressure control valves 61 and 62. Also, the multi-plate clutch C2
The multi-plate brake B0 is connected to the drain port 48 (D _{r in} FIG. 10) through the drain ports 54 and 55, and the multi-plate brakes B1, B2 and B3 are all drain ports 48.
Connected to.

From the first speed mode, the AT ECU 7
When 0 is to become an instruction state of the second speed mode (2 _nd in FIG. 10), the step motor 12 by an instruction from the AT ECU70 rotates the cam shaft 1 to the second speed mode position, the position of each spool valve SP Change. as a result,
As shown in the column 2 _nd of the D range of FIG. 10, multi-plate clutch C1 is connected to the line pressure port 35 (P _S in FIG. 10), multi-plate brake B2 is P of the control pressure port 38 (FIG. 10
_It is connected to _c2 ) and other clutches and brakes are maintained in the same state as in 1st speed mode. The hydraulic pressure determined by these modes actuates the clutches and brakes in the transmission 300, resulting in a torque state of a second speed mode having a speed ratio different from that of the first speed mode. In this way, the control state is determined and the function as AT is achieved. The same operation is performed at the other range positions and the downshift operation.

When the select lever 500 is manually switched and the shift ratio is changed, the camshaft 1 is slid by the connecting portion 11 interlocked with the select lever 500 to switch the position of each spool valve SP, and designated by each range in FIG. To the hydraulic communication mode. In that state, the camshaft 1 is rotationally driven by the step motor 12 under the control of the AT ECU 70 at the same time to enter the hydraulic communication mode corresponding to the vehicle speed, and the automatic control is continued.

According to the first embodiment, there are three small holes 2e, 3e, 4e, 6e, 7 in the bottom wall of each spool valve SP.
Since e and 8e are formed, the oil filled in the spool valve SP is released to the lower side of the bottom portion of the spool valve unopened side, and the pressure due to the hydraulic pressure inside the spool valve and the hydraulic pressure acting on the surface of the spool valve unopened side bottom portion. It becomes possible to balance and. This has the effects of improving the responsiveness of the spool valve SP and reducing the driving force of the spool valve SP. Further, since the driving force of the spool valve SP is reduced, the driving force of the step motor 12 that is the driving source of the camshaft 1 can be reduced. Therefore, the step motor 12 can be downsized, and the hydraulic control device 400 can be downsized and lightweight.

Further, according to the first embodiment, since the annular groove is formed on the outer periphery of each spool valve SP, the outer peripheral wall of each spool valve SP and the inner peripheral wall of the cylindrical hole corresponding to each spool valve SP are formed. Has the effect of eliminating hydraulic lock caused by the imbalance of oil flowing through the gap. For example, in the case of the spool valve 5, the annular groove is formed so as to be located in the control pressure communication passage 47 when stopped at a position communicating with the line pressure communication passage 46. It does not affect the seal length for sealing with the passage 48. Therefore, the line pressure communication passage 46, the control pressure communication passage 47, the drain pressure communication passage 48.
There is an effect that the hydraulic lock can be eliminated when the spool valve SP moves without increasing the amount of oil leakage between them.

Further, according to the first embodiment, the radius of curvature R2b of the corner of the cam concavo-convex formed on the camshaft 1 is larger than the radius of curvature R1 of the tip of the pin sliding on the cam surface. There is an effect that the tip of the pin slides smoothly without being caught on the cam surface when the cam unevenness is moved up and down. Moreover, since the tip of the pin slides smoothly on the cam surface, there is an effect of improving the reliability of the operation of the spool valve SP with respect to the movement of the camshaft 1 in the rotational direction and the axial direction.

(Second Embodiment) FIG. 1 shows a second embodiment of the present invention.
3 shows. The same reference numerals are given to substantially the same components as those in the first embodiment. In the second embodiment shown in FIG. 13, the balls 84 are used instead of the pins for pushing up the spool valve 5, and the balls 84 push up the spool valve 5 while rotating the cam surface of the camshaft 1. The frictional force between 84 and the cam surface is reduced.

As shown in FIG. 13, a spherical ball 84 having a diameter allowing the full stroke of the spool valve 5 is located between the camshaft 1 and the end surface 5d of the bottom portion of the spool valve 5 on the unopened side. It is inserted into the housing 28 and transmits the movement of the cam of the camshaft 1 to the spool valve 5. When the spool valve 5 slides in the cylindrical hole 28a, the line pressure communication passage 46 and the control pressure communication passage 47, which allow the hole 5b to communicate with the cylindrical hole 28a, depending on the slide position.
It communicates with the drain pressure communication passage 48. Similarly, balls (not shown) are inserted between the other spool valves 2, 3, 4, 6, 7, 8 and the camshaft 1.

According to the second embodiment, each spool valve 2,
Since balls (for example, the ball 84 in the spool valve 5) for transmitting the cam movement of the camshaft 1 to each spool valve are inserted between the camshafts 3, 4, 5, 6, 7, 8 and the camshaft 1, This ball has the effect of pushing up each spool valve while rotating the cam surface of the cam shaft 1 and reducing the frictional force between the ball and the cam surface. Further, since the frictional force between the ball and the cam surface is reduced, it is possible to reduce the driving force of the step motor that is the driving source that drives the cam shaft 1 in the rotational direction and the axial direction. Therefore, the step motor can be downsized, and the hydraulic control device can be downsized and lightened.

(Third Embodiment) A third embodiment of the present invention is shown in FIG.
4 shows. In the third embodiment, the pressure applied to both ends of the spool valve 91 is reduced to a low pressure to smoothen the movement of the spool valve 91 in the cylindrical hole 90a. 14
As shown in (a), the spool valve 91 is formed in a cylindrical shape, and an annular oil passage groove 91a is provided around the center of the outer side surface. A cylindrical hole 91b is formed inside the end opposite to the cam shaft (not shown). A part of the spring 92 is housed in this hole 91b, and the spring 9
2 biases the spool valve 91 toward the camshaft side.
The space 91c on the drain pressure port 90d side formed by the spool valve 91 and the housing 90 including the hole 91b is always in communication with the drain pressure port 90d.
The pressure in c is a low drain pressure. Space portion 91d formed between the spool valve 91 and the housing 90
Is communicated with a recess formed in the housing 90 into which the camshaft is inserted through a pressure relief groove 94 formed in the housing 90, and a drain pressure is always low.

FIG. 14A shows the state where the spool valve 91 is pushed up most by the pin 93, and FIG. 14C shows the state where the spool valve 91 comes closest to the camshaft. In FIG. 14 (b), the spool valve 91 is located at a position approximately midway between FIGS. 14 (a) and 14 (c). The hydraulic pressure of the pressure oil supplied to the communication port 95 is shown in FIG.
FIG. 14 (b) corresponds to the control pressure, and FIG. 14 (c) corresponds to the drain pressure.

Since the pressures in the space portions 91c and 91d, which are pressure chambers provided at both ends of the spool valve 91, are always equal to the drain pressure, the spool valve 91 is provided on the camshaft side.
It is possible to reduce the biasing force of the spring 92 that biases the. Then, the force of the pin 93 pushing up the spool valve 91 against the biasing force of the spring 92 can be reduced,
The operation force of the select lever (not shown) that drives the cam shaft in the axial direction can be reduced. Further, since the driving force of the step motor that drives the cam shaft in the rotation direction is reduced, the step motor can be downsized.

According to the third embodiment, since the pressure at both ends of the spool valve 91 is always equal to the drain pressure, the force by which the pin 93 pushes up the spool valve 91 can be reduced and the force applied to the surface of the camshaft can be reduced. effective. Therefore,
The material of the camshaft can be resin or the like, which has the effect of reducing the weight and cost of the camshaft. In the embodiment of the present invention described above, as shown in FIG. 1, since the spool valves SP are arranged on both sides of the camshaft 1, the integrated valve 60 has a compact and substantially flat plate shape. Since there is no upper or lower restriction on the arrangement, the arrangement in the oil pan is easy. In the present invention, the shape is not limited to the flat plate shape, but may be bent around the cam shaft axis, for example. Further, in the present invention, the spool valve train may be arranged in one line on one side of the camshaft and may be in the shape of an elongated rod.
In these cases, it can be compactly mounted around other devices, especially in the inside of an oil pan with a small installation margin, etc., according to the shape of the transmission of the AT body.

Further, in the embodiment of the present invention, the camshaft 1
The ECU shift and the manual shift are assigned to the ECU in the rotational direction and the manual shift in the axial direction. This is because the frequency of changes in the cam irregularities on the cam surface in the rotational direction decreases, which facilitates the processing such as casting and molding of the cam shaft 1, which is extremely advantageous in manufacturing. In the present invention, it is possible to perform automatic control by linear movement in the axial direction of the cam shaft, which is the driven body, and manual control by rotational movement. In this case, the step motor, which is the driving means, is arranged to interlock with the cam shaft, and the position of the step motor is mechanically connected to the select lever by a gear. Further, in the present invention, the cam shaft is not limited to the illustrated dimensions, and the diameter may be increased to be a substantially cylindrical drum cam shaft. Also, the shape of the spool valve is not limited to a cylinder as long as it is a hydraulic valve having the above-mentioned function,
The valve may have any shape. Note that generally, the number of spool valves and the hydraulic communication mode change depending on the structure of the transmission, and the setting conditions also change depending on the number and quality of the multiple disc brakes and multiple disc clutches.

In the embodiment of the present invention, the camshaft 1
Although each spool valve SP is driven by the above method, in the present invention, the spool valve that is the control valve may be driven by any hydraulic control method having an automatic or manual mechanism, and the same effect can be obtained. it can. Further, in the embodiment of the present invention, the driving in the axial direction is performed by the manual operation by the select lever 500, but of course the automatic side, that is, the step motor 12
The same effect can be obtained with a configuration applied to driving in the rotation direction driven by.

In the embodiment of the present invention, the cam and the cam shaft 1 are integrally formed. However, in the present invention, a cam ring having an outer peripheral surface having a cam shape is fitted on the shaft to form the cam shaft structure shown in FIG. Well, in that case, it becomes easier to respond to changes in the number of ports and port combinations. For example, although not shown, the change can be easily made by forming a structure in which the circumference of the cylindrical hole of the housing having each spool valve is one block and the blocks are stacked in the axial direction of the camshaft. Therefore, such a structure is characterized in that the integrated valve has the hydraulic valve and the housing thereof as one block unit and the one block unit is laminated by the required number of ports.

[Brief description of drawings]

FIG. 1 is a sectional view showing an integrated valve of a hydraulic control device for an automatic transmission according to a first embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II in FIG.

FIG. 3 is a block diagram showing a system configuration of an automatic transmission device.

FIG. 4 is a cross-sectional view showing a structure of a spool valve and its surroundings.

5 is a sectional view taken along line VV of FIG.

FIG. 6 is a plan view of a spool valve.

FIG. 7 is an explanatory diagram showing a positional relationship between the annular groove of the spool valve and each hydraulic communication passage.

FIG. 8 is a block diagram showing an input / output state of a signal line.

FIG. 9 is a radius of curvature of a corner portion of the cam unevenness of the cam shaft,
It is explanatory drawing which showed the relationship with the curvature radius of the front-end | tip part of a pin.

FIG. 10 is an explanatory diagram showing a hydraulic communication mode of the integrated valve.

FIG. 11 is an operation state diagram of a multi-disc clutch and a multi-disc brake of the transmission.

12 is a sectional view taken along line XII-XII in FIG.

FIG. 13 is a sectional view showing the structure of a spool valve and its surroundings according to a second embodiment of the invention.

FIG. 14 is a sectional view showing a schematic configuration of a spool valve and its surroundings according to a third embodiment of the present invention.

[Explanation of symbols]

1 Cam Shaft (Power Transmission Member, Cam) 1b Corner 2, 3, 4, 5, 6, 7, 8 Spool Valve (Hydraulic Valve) 2b, 3b, 4b, 5b, 6b, 7b, 8b Holes
(Input port) 2c, 3c, 4c, 5c, 6c, 7c, 8c Inner cylindrical portion 2e, 3e, 4e, 5e, 6e, 7e, 8e Small hole
(Passage) 5h, i Annular groove (Groove) 12 Step motor (Automatic switching means) 14, 15, 16, 17, 18, 19, 20 pin 14a, 15a, 16a, 17a, 18a, 19a, 2
0a Tip (contact end) 28 Housing (valve housing) 28a, 28b, 28c, 28d, 28e, 28f, 2
8g Cylindrical hole (cylindrical hole) 39, 40, 41, 42, 43, 44, 45 Communication port 46, 51 Line pressure communication passage (hydraulic passage, port) 47, 50 Control pressure communication passage (hydraulic passage, port) 48, 49 Drain Pressure communication passage (hydraulic passage, port) 61, 62 Engagement hydraulic control valve 64 Line pressure control valve 84 Ball 500 Select lever (manual switching means)

Claims (4)

[Claims] 1. A plurality of shift stages are switched by controlling the hydraulic pressure applied to a plurality of friction engagement elements provided in an automatic transmission with a plurality of hydraulic valves and engaging or disengaging the plurality of friction engagement elements. A hydraulic control device for an automatic transmission, comprising: an integrated valve having a plurality of hydraulic valves for switching the hydraulic pressure applied to each of the plurality of friction engaging elements; and transmitting a driving force to the plurality of hydraulic valves. A cam, an automatic switching means for driving and controlling the cam by automatic control, and a manual switching means for driving and controlling the cam by manual operation, wherein a radius of curvature of a contact portion of the plurality of hydraulic valves in contact with the cam is A hydraulic control device for an automatic transmission, characterized in that the radius of curvature of a cam surface that contacts the contact portion of the cam is smaller than that of the cam surface. 2. A plurality of shift stages are switched by controlling the hydraulic pressure applied to a plurality of friction engagement elements provided in an automatic transmission by a plurality of hydraulic valves and engaging or disengaging the plurality of friction engagement elements. A hydraulic control device for an automatic transmission, comprising: an integrated valve having a plurality of hydraulic valves for switching the hydraulic pressure applied to each of the plurality of friction engaging elements; and transmitting a driving force to the plurality of hydraulic valves. A power transmission member, an automatic switching device for driving and controlling the power transmission member by automatic control, and a manual switching device for driving and controlling the power transmission member by a manual operation, wherein the hydraulic valve has a high pressure side and a low pressure side. A hydraulic control device for an automatic transmission having a plurality of passages communicating with each other. 3. A plurality of shift stages are switched by controlling the hydraulic pressure applied to a plurality of friction engagement elements provided in an automatic transmission by a plurality of hydraulic valves and engaging or disengaging the plurality of friction engagement elements. An automatic transmission hydraulic control device for controlling, comprising: an integrated valve having a plurality of spool valves for switching the hydraulic pressure applied to each of the plurality of friction engagement elements; and transmitting a driving force to the plurality of spool valves. A power transmission member, an automatic switching unit that drives and controls the power transmission member by automatic control, a manual switching unit that drives and controls the power transmission member by manual operation, and is formed on the outer peripheral surface of the spool valve in the circumferential direction. A groove and a plurality of hydraulic ports formed in the valve housing of the integrated valve, the ports being capable of selectively communicating with the input port of the spool valve. An automatic transmission characterized in that, when any one of the plurality of ports communicates with the input port of the spool valve, the groove is arranged in another port of the plurality of ports. Hydraulic control device. 4. A plurality of gear stages are switched by controlling the hydraulic pressure applied to a plurality of friction engagement elements provided in an automatic transmission by a plurality of hydraulic valves and engaging or disengaging the plurality of friction engagement elements. A hydraulic control device for an automatic transmission, comprising: an integrated valve having a plurality of hydraulic valves for switching the hydraulic pressure applied to each of the plurality of friction engaging elements; and transmitting a driving force to the plurality of hydraulic valves. A cam, an automatic switching means for drivingly controlling the cam by automatic control, a manual switching means for drivingly controlling the cam by manual operation, and a biasing means for biasing the cam surface of the cam in a direction of pressing the hydraulic valve. A hydraulic control device for an automatic transmission, comprising: means and a ball that is in contact with the cam and that transmits a displacement amount of the cam to the hydraulic valve.