KR0142455B1 - Hydraulic control system - Google Patents

Abstract

In order to simplify the configuration and to control the operating side in conjunction with the release side hydraulic pressure, the friction enzyme is released during 3-4 up shift, 4-2 kick down skip shift and 3-2 down shift. In order to provide a hydraulic control system of a four-speed automatic transmission for a vehicle that can increase the shifting feeling by allowing the shifting control section to be widely used even when the friction elements are worn, and controlling the release side; D range 3-4 Duty-controlled in the upshift process to back up the hydraulic pressure supplied from the preceding shifting stage to the first friction element to the operating side of the second friction element, and controlled in the kick-down 4-2 skip shift process to shift ahead The hydraulic pressure supplied from the third friction element at the stage is controlled and back-pressured by interlocking with the hydraulic pressure at the release side of the second friction element, and the duty is controlled in the 3-2 downshift shifting step so that the third friction element at the preceding shift stage is controlled. It provides a hydraulic control system of a four-speed automatic transmission for an automobile to control the operating side back pressure while interlocking with the release side hydraulic pressure to the operating side of the second friction element to the operating side of the second friction element.

Description

Hydraulic control system of 4-speed automatic transmission for automobile

1 is an overall hydraulic circuit diagram in a neutral state of the hydraulic control system according to the present invention,

2 is an enlarged view of the line pressure control and damper clutch control unit according to the present invention.

3 is an enlarged view of a first shift control unit according to the present invention.

4 is an enlarged view of a second shift control unit according to the present invention.

5 is a hydraulic circuit diagram of a D range 1 speed state by the hydraulic control system according to the present invention.

6 is a hydraulic circuit diagram of a D range 2 speed state by the hydraulic control system according to the present invention.

7 is a hydraulic circuit diagram of a D range three speed state by the hydraulic control system according to the present invention.

8 is a hydraulic circuit diagram showing an upshift process from D range 3 to 4 speed by the hydraulic control system according to the present invention.

9 is a hydraulic circuit diagram of a D range four speed state by the hydraulic control system according to the present invention.

10 is a hydraulic circuit diagram in which a 4-3 skip shift is performed in the D range by the hydraulic control system according to the present invention.

11 is a hydraulic circuit diagram in which a 4-2 skip shift is performed in the D range by the hydraulic control system according to the present invention.

12 is a hydraulic circuit diagram in which a 3-2 skip shift is performed in the D range by the hydraulic control system according to the present invention.

13 is a hydraulic circuit diagram of the first speed state in the L range by the hydraulic control system according to the present invention.

14 is a hydraulic circuit diagram in the reverse (R) shift state by the hydraulic control system according to the present invention.

15 is a hydraulic operation graph showing an upshift process from the D range 2 to the 3rd speed.

16 is a hydraulic operation graph showing an upshift process from the D range 3 to the 4th speed.

17 is a hydraulic actuation graph showing a skip shifting process from 4 to 3 speeds in the D range.

FIG. 18 is a hydraulic actuation graph showing a shift shift from 4 to 2 speeds in the D range. FIG.

19 is a hydraulic operation graph showing a skip shifting process from 3 to 2 speeds in the D range.

20 is a table showing whether the operation of each mode of the solenoid valves related to the present invention.

The present invention relates to a hydraulic control system of a four-speed automatic transmission for a vehicle, and more particularly, to simplify the configuration and to free operation during 3-4 upshift, 4-2 kickdown skipshift, and 3-2 downshift. In order to control the operating side by controlling the operating side in conjunction with the release side hydraulic pressure on the friction element to be used, the friction control element can use the shift control section widely even when worn, and increase the sense of shifting by controlling the release side. Hydraulic control system.

The automatic transmission for a vehicle can transmit the driving force of an engine to a geartrain through the torque converter which is a fluid clutch.

The gear train combines one or more planetary gear sets, one element as an input element, the other as a reaction element, and the other as an output element. Proper transmission ratio can be output.

The elements of the planetary gear set are using a plurality of friction elements and one-way clutch to selectively input, reaction and output.

The friction elements are selected and controlled at a suitable time by a hydraulic control system including a solenoid valve controlled by a transformer control unit (TCU).

In the case of the conventional four-speed automatic transmission to which such a hydraulic control system is applied, the skip shift is performed by the subordinate control of a certain friction element without the control of the friction element released during shifting, thereby making the hydraulic system as well as the hydraulic control. There was a problem that complicates.

In addition, the operation of the control section is changed when the friction element is worn by the above operation, and there is a closing effect that has a great influence on the quality of the automatic transmission.

Therefore, the present invention has been invented to solve the problems of the prior art as described above, the object of the present invention is to simplify the configuration and at the same time 3-4 upshift, 4-2 kickdown skipshift and 3-2 In order to control the operating side of the friction element that is released during downshifting, it is possible to control the operating side in conjunction with the hydraulic pressure of the release side so that the friction element can use the shift control section even when worn and control the release side. It is to provide a hydraulic control system of a four-speed automatic transmission for automobiles that can increase the feeling of shifting.

In order to realize this, the present invention provides an oil pump for generating oil pressure by driving together with the engine;

A torque converter for transmitting the driving force of the engine to the input shaft of the transmission;

A regulator valve for varying the line pressure generated by the oil pump together with the damper clutch due to the duty of the damper clutch control solenoid valve during driving mode switching and high speed driving; A reducing valve configured to supply pressure lower than the line pressure;

A manual valve for supplying hydraulic pressure to the drive pressure pipe in the D range by interlocking with the selection lever and directly supplying hydraulic pressure to the fifth friction element through the reverse pressure pipe in the R range;

Connected to the above-mentioned drive pressure line, on / off and duty control by the transmission control unit according to the opening speed of the vehicle speed and the throttle valve are supplied to a plurality of valves related to the shift by the action of two shift control solenoid valves. A shift control valve;

A rear clutch release valve for converting a port for supplying the drive pressure to the first friction element in the D ranges 1,2 and 3;

During the automatic shift except N → D and 2-1, the port change is made by the first pressure control solenoid valve to supply the drive pressure to the actuation and deactivation side of the second friction element and the third and fourth friction elements. A first pressure control valve;

A second pressure regulating valve in which port switching is effected by a second pressure control solenoid valve which is duty controlled to supply hydraulic pressure to the first friction element during N → D and 4 → 3, 4 → 2 automatic shifting;

A 1-2 shift valve in which port conversion is performed to supply hydraulic pressure to the actuating side or non-actuating side of the second friction element and the third friction element by the second speed line pressure of the shift control valve;

An end clutch valve in which port conversion is performed by four-speed line pressure to supply hydraulic pressure to the third friction element;

Port change is made by the 3rd speed line pressure and the 4th speed line pressure of the shift control valve, and when the gears of 3-4, 4-2, and 4-3 are shifted, the working release side of the second friction element and the The hydraulic control system of the four-speed automatic transmission for automobiles, which includes a 2-3 / 4-3 shift valve for discharging hydraulic pressure, is processed.

In the above, the first pressure control solenoid valve is duty-controlled during the D range 3-4 upshift process to back up the hydraulic pressure supplied to the first friction element at the preceding shift stage to the operating side of the second friction element, and 4-2 kick It is duty controlled in the down-skip shifting process to back up the hydraulic pressure supplied from the preceding shifting stage to the third friction element to the operating side of the second friction element, and it is duty controlled in the 3-2 upshift shifting process and the third friction in the preceding shifting stage. It provides a hydraulic control system of a four-speed automatic transmission for a vehicle configured to back pressure the hydraulic pressure supplied to the element to the operating side of the second friction element.

The rear clutch release valve includes a first port communicating with a second pressure control valve, a second port communicating with a fourth speed line of the shift control valve, and a third port communicating with a 2-3 / 4-3 shift valve. A valve body having a fourth port communicating with the first friction element;

And a first land for selectively communicating the first port and the fourth port, and a second land for selectively communicating the third port and the fourth port, and including a valve spool supported on one side by a spring. Done;

The 2-3 / 4-3 shift valve receives hydraulic pressure from the first port communicating with the third speed line of the shift control valve, the second port connected with the third port of the rear clutch release valve, and the 1-2 shift valve. A valve body having a third port and a fourth port in communication with the second friction element and the third friction element;

A first land to which the hydraulic pressure of the third speed line acts, and a second land to open and close the third port, one side of which includes a valve spool supported by a spring;

The end clutch valve includes a first port and a second port receiving hydraulic pressure from the third and fourth speed lines of the shift control valve and a third port connected to the fourth port of the 2-3 / 4-3 shift valve. A valve body having a fourth port connected to the friction element;

The four-speed automatic transmission comprising a first land in which the hydraulic pressure flowing into the second port acts, and a second land selectively blocking the first port, one end of which includes a valve spool supported by a spring. Provide hydraulic control system.

In addition, the first friction element and the second at the time of shifts of 3-4, 4-2 and 3-2 on the pipeline connecting the third port of the rear clutch release valve and the second port of the 2-3 / 4-3 shift valve. A discharge port for discharging the hydraulic pressure of the non-operating side of the friction element and the third friction element;

The third friction element allows hydraulic pressure to be supplied through the first pressure control valve and the 1-2 shift valve, and the 2-3 / 4-3 shift valve and the end clutch valve at the third speed;

In the fourth speed, the hydraulic pressure of the third speed line can be supplied by the port conversion of the end clutch controlled by the hydraulic speed of the fourth speed line;

The fifth friction element is supplied with hydraulic pressure directly from the reverse pressure pipe of the manual valve in the R range, and the fourth friction element is a four-speed automatic vehicle for supplying hydraulic pressure from the ND control valve through a 1-2 shift valve. It is characterized by providing a hydraulic control system of a transmission.

Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present invention that can specifically realize the above object will be described in detail.

1 is a schematic diagram of a hydraulic control system according to the present invention, showing a state in which a select lever is selected in the N range.

Its oil pressure control system includes an oil pump (2) which always generates oil pressure during engine operation, a torque converter (4) which transmits engine power to the input shaft of the transmission, and a constant oil pressure, that is, line pressure, generated by the oil pump. Regulator valve (6) for adjusting the pressure, torque converter control valve (8) for constantly adjusting the hydraulic pressure for the torque converter and lubrication, and damper clutch control valve (10) for controlling the hydraulic pressure acting on the damper clutch installed in the torque converter. It is made, including.

And a reducing valve 12 for producing a constant hydraulic pressure lower than the line pressure, a manual valve 14 for switching the flow path in conjunction with the shift lever position and sending or discharging the line pressure to each valve, and two shift controls. The shift control valve 16 which switches a flow path by the ON / OFF action of solenoid valve S1, S2 is included.

In addition, the pressure control solenoid valves S3 and S4 have pressure control valves 18 and 20, which prevent shocks during shifting, and prevent shocks when shifting from the neutral range to the reverse range. It has the NR control valve 22 which prevents it.

And a 1-2 shift valve 24 for controlling the flow of line pressure when shifting from 1 speed to 2 speeds, and for controlling a hydraulic passage connected to a friction element acting upon reversal, and operated by line pressure and having a second friction It has a 2-3 / 4-3 shift valve 26 which supplies the releasing pressure to the element C2 and the operating pressure to the third friction element C3.

In addition, it has an end clutch valve 28 for supplying a working pressure to the fourth friction element C4 and a fifth friction element C5 which is operated by directly receiving hydraulic pressure from the manual valve 14 in the reverse range.

And discharges the hydraulic pressure of the first friction element C1 when shifting from three speeds to four speeds, and generates a shock to control the time of hydraulic pressure supplied to the first friction element C1 when shifting from four speeds to three speeds. It has a rear clutch release valve 30 which prevents.

2 is an enlarged view of the line pressure control and the damper clutch control unit. Since the oil pump 20 and the torque converter 4 are the same as the existing configuration, detailed description thereof will be omitted.

The regulator valve 6 having a function of regulating the line pressure generated by the oil pump 2 has a valve body and a valve spool 32 moving therein.

The valve body is a first line 36 communicating with the line pressure line 34, and a line pressure line passing through the manual valve 14 and acting as a reaction pressure against the regulator valve spring 38 ( 40 and the line pressure supplied to the second port 44 and the third port 46 and the first port 36 in communication with the reverse pressure pipeline 42 to communicate with the torque converter control valve (8) The fourth port 48 and the fifth port 50 are provided.

The valve spool 32 is supported by a spring 38, and the first land 52 for selectively blocking the fourth port 48, and the release of the line pressure in accordance with the left movement of the valve spool 32, Including the second land 54 to allow, and the third land 56 and the fourth land 58 acting as a working surface of the hydraulic pressure flowing into the third port 46 and the second port 44, It is done.

In addition, fifth and sixth lands 60 and 62 are provided between the second land 54 and the third land 56 in preparation for adding a separate control means.

The torque converter control valve 8 provided in the pipeline connecting the regulator valve 6 and the damper clutch control valve 10 includes a first port 64, a second port 66, and a third formed in the valve body. Valve spool 74 having ports 68 and lands 72 which are supported by springs 70 to partially return the hydraulic pressure flowing into the first port 64 to the third port 68. Is being done.

In addition, the damper clutch control valve 10 is connected to the torque converter 4 through the clutch operating conduit 76 and the clutch non-operating conduit 78 to operate the damper clutch in the torque converter.

The damper clutch control valve 10 is the first, second, third, fourth, fifth, sixth lands (80, 82, 84, 86, 88, 9)

And a valve spool 92 having 0), and first, second, third, fourth, fifth, sixth, seventh, eighth, and ninth ports 94,96,98,100,102,104,106,108,110 formed in the valve body. The spring 114 is supported by the front pressure receiving chamber 112 of the land 80 so as to keep the valve spool 92 moved to the right at all times.

In the above, the first port 94 is supplied with a regulated line pressure through a conduit connected from the regulator valve 6 and the third port 98 can receive a line pressure supplied to the reducing valve 12. The second port 96 is supplied with the reduced pressure from the reducing valve 12.

In addition, the seventh port 106 and the eighth port 108 communicate with each other as the conduit 116, and the fifth port 102 and the sixth port 104 communicate with the clutch operating conduit 76 and the clutch non-operating conduit. Communication with the torque converter 4 is made through the 78.

In addition, the reducing valve 12 is connected to the branch line 118 of the line pressure line 34 to supply the reduced pressure to the damper clutch control valve 10 and the damper clutch control solenoid valve S5. The damper clutch control valve 10 and the pressure control valve 18 formed in the first port 120 and part of the hydraulic pressure flowing into the first port 120 communicate with the line pressure branch pipe 118. Valve spool 130 having a second port 122 and a third port 124 for supplying to (20), and a first land 126 and a second land 128 for varying the opening area of these ports. Is being done.

The manual valve 14 includes a first port 132 formed in the valve body, a second port 134 for supplying hydraulic pressure flowing into the port to the shift control valve 16 in the D, 2, and L ranges, and N. The third port 136 for supplying hydraulic pressure to the regulator valve 6 through the D, 2, and L range pipe lines 40, and the fifth and fifth friction valves through the R range pipe line 42. A fourth port 138 for supplying hydraulic pressure to the element C5, and a fifth for supplying hydraulic pressure to any port of the NR control valve 22 when the conversion from the N range to the R range is performed through the conduit 140. Has a port 142.

3 is an enlarged view of the first shift control unit according to the present invention. Referring to FIG. 1, the drive pressure pipe path 144 connecting the manual valve 14 and the shift control valve 16 is connected to the transmission control unit. The hydraulic pressure is selectively supplied to the friction element by the shift control solenoid valves S1 and S2 actuated on and off.

In order to selectively operate these friction elements, in this embodiment, the drive pressure pipe 144 is directly connected to the 1st speed line 146, and the shift control valve 16 is connected to the 2nd speed line 148 and the 3rd speed line. 150 and 4 speed lines 152, respectively.

The shift control valve 16 may include a first port 153 communicating with the drive pressure line 144, a second port 154 connected with a second speed line, and a third port 156 connected with a third speed line. And a fourth port 158 connected to the fourth speed line, and the hydraulic pressure flowing into the first port 153 to move the valve spool 160 by the shift control solenoid valves S1 and S2 is provided. The fifth port 162 and the sixth port 164 are supplied to the left and right sides of the valve spool 160.

The fifth and sixth ports 162 and 164 form a connection in which the hydraulic pressure can be supplied from the seventh port 166, and the seventh port 166 supplies the hydraulic pressure to the eighth port 168. To move the valve spool 160.

Plugs 170 and 172 are respectively installed in the fifth port 162 and the sixth port 164 to move left and right by on / off action of the shift control solenoid valves S1 and S2. .

The plugs 170 and 172 are installed to limit the distance that can be moved by the stoppers 174 and 176 installed at the eighth port 168 and the discharge port Ex, respectively.

The stopper 174, 176 is made of a thin plate, a hole is formed in the center so that the left and right ends of the valve spool 160 can be inserted.

The valve spool 160 has a first land 178 and a smaller second land 180, the second land 180 having second, third and fourth ports 154, 156, 158. Will be selectively blocked.

On the other hand, the NR control valve 22 connected to the pressure reducing line 182 to supply hydraulic pressure is to reduce the shift shock by gradually increasing the hydraulic pressure supplied to the friction element operating in the reverse direction, and the first pressure control solenoid valve S3. Valve spool 184 is moved to the left and right by the on / off duty action.

The valve spool 184 is left by the spring (186) is supported by the spring 186 is always kept moving to the right, this NR control valve 22 is formed in the valve body is in communication with the decompression line 182, The second port 190 is supplied with the line pressure in communication with the fifth port 142 of the manual valve 14 with the first port 188 receives the hydraulic pressure controlled by the first pressure control solenoid valve (S3). ) And a third port 192 for supplying the hydraulic pressure introduced into the second port 190 to the 1-2 shift valve 24.

The valve spool 184 has a first land 194 in which the hydraulic pressure introduced into the first port 188 acts, and a second land 196 selectively blocking the second port 190. .

In addition, the pressure reducing line 182 is branched and connected to the first port 198 and the second port 200 of the first pressure control valve 18, respectively. It is connected to the control solenoid valve S3 so that the hydraulic pressure can be controlled.

In addition, the first pressure control valve 18 is a third port 202 connected to the first speed line 146, and the first to supply the hydraulic pressure introduced into the third port 202 to the 1-2 shift valve 24 It has four ports 204.

The valve spool 206 of the first pressure control valve 18 is supported by the spring 208 and the first land 210 to which the hydraulic pressure flowing into the first port 198 acts, and the second port 200. The second land 212 on which the hydraulic pressure flows is retained.

The second pressure control solenoid valve S4 is installed in the line connected to the second port 200, and the valve S4 controls the valve spool 214 of the second pressure control valve 20. .

The hydraulic pressure controlled by the second pressure control solenoid valve S4 is allowed to flow into the first port 216 formed in the valve body, and the uncontrolled hydraulic pressure can flow into the second port 218. It is.

In addition, the second pressure control valve 20 is connected to the first speed line 146 of the shift control valve 16 and has a third port 220 for receiving hydraulic pressure, which flows into the third port 220. A fourth port 222 for supplying hydraulic pressure to the rear clutch release valve 30 is provided.

In addition, the valve spool 214 of the second pressure control valve 20 is supported by the spring 224 and the first land 226 and the second port 218 where hydraulic pressure flowing into the first port 216 acts. The second land 228 to which the hydraulic pressure flowed in is retained.

4 is an enlarged view of the second shift control unit according to the present invention. Referring to FIG. 1, the rear clutch release valve 30 receives hydraulic pressure from the first and second pressure control valves 18 and 20, and FIG. -3 / 4-3 shift control valve 26, 1-2 shift control valve 24, and end clutch valve 28 kickback the first friction element C1, which is a rear clutch, through the ports they hold The hydraulic pressure is supplied to or released from the second friction element C2 which is shown, the third friction element C3 as the end clutch, and the fourth friction element C4 as the low / reverse brake.

The rear clutch release valve 30 has a first port 230 communicating with the second pressure control valve 20 and a second port 232 communicating with the fourth speed line 152 of the shift control valve 16. ), A third port 234 in communication with the 2-3 / 4-3 shift valve 26, and a fourth port 236 in communication with the first friction element C1.

The valve spool 238 of the valve 30 includes a first land 240 for selectively communicating the first port 230 and the fourth port 236, the first port 230, and the third port 234. ) Has a second land (242) for selectively communicating, and is supported by a spring (244).

The 2-3 / 4-3 shift valve 26 is formed in the valve body and communicates with the third speed line 150 of the shift control valve 16 and the first port 246, and the outlet port EX in the middle portion. 2 port 250 connected to the third port 234 of the rear clutch release valve 30 and the third port 252 supplied with hydraulic pressure from the 1-2 shift valve 24 as ) And a fourth port 254 for releasing the operation of the second friction element C2 at the third speed D range.

In addition, the valve spool 256 has a first land 258 to which the hydraulic pressure of the third speed line 150 acts, and a second land 258 to open and close the third port 252, and has a spring 260. It is burnt.

On the other hand, the 1-2 shift valve 24 forms a first port 262 in the valve body for supplying hydraulic pressure to the action side of the second friction element C2 at speed D, ranges 2, 3, and 4, and L range. And a second port 264 for supplying hydraulic pressure to the fourth friction element C4 in the R range.

These ports 262 and 264 communicate with a fourth port 204 of the first pressure control valve 18 by shifting the position of the valve spool 266 acting by the hydraulic pressure of the second speed line 148. A fourth port 270 is connected to the third port 192 of the port 268 and the NR control valve 22, and a fifth port 272 connected to the second speed line 148.

The valve spool 266 has a first land 274 to which the hydraulic pressure flowing into the fifth port 272 acts, and a second land to selectively open and close the second port 264 and the fourth port 270. 276 and a third land 278 for selectively opening and closing the first port 262 and the third port 268, the valve spool 266 of which has a right end supported by a spring 280. .

The end clutch valve 28 includes first and second ports 282 and 284 which receive hydraulic pressure from the third speed line 150 and the fourth speed line 152 of the shift control valve 16, and 2-3 /. A third port 286 connected to the fourth port 254 of the 4-3 shift valve 26 and a fourth port 288 connected to the third friction element C3 are provided.

In addition, the valve spool 290 is composed of a first land 292 to which the hydraulic pressure flowing into the second port 284 acts, and a second land 294 for selectively blocking the first port 282. The right end is supported by the spring 296.

The automatic transmission hydraulic control system of the present invention made in this way is controlled by the transmission control unit (TCU) according to the opening and the vehicle speed of the throttle valve is made of the following shifting action by the solenoid valves on / off or duty action .

That is, when the engine starts to drive, the torque converter 4 drives together and rotates the input shaft of the transmission. At this time, the oil pump 2 starts to generate oil pressure.

Part of the generated oil pressure flows along the line pressure line 34 to the regulator valve 6, the torque converter control valve 8, and the damper clutch control valve 10, and part of the reducing valve 12 and the manual. It flows into the valve 14.

The hydraulic pressure flowing to the regulator valve 6 flows into the first port 36 and is supplied to the torque converter control valve 8 through the fourth port 50 and simultaneously pushes the valve spool 32 to the left. (Ex) Pressure control is performed while part of the discharge pressure is returned to the oil pan.

In addition, the hydraulic pressure flowing into the first port 120 of the reducing valve 12 changes the opening area of the port by the movement of the valve spool 126 so that the hydraulic pressure lower than the line pressure is reduced to the second port 122, The third port 124 is released, and this pressure is supplied to the damper clutch control valve 10, the first and second pressure control valves 18 and 20, and the NR control valve 22.

In this state, when the shift lever is switched to the D range, the manual valve 14 is in a state of FIG. 5 from FIG. 1 in conjunction with this, while the hydraulic pressure flowing into the first port 132 of the manual valve 14 is second. The first port 152 of the shift control valve 16 and the second port 200 of the first and second pressure control valves 18 and 20 through the drive pressure pipe 144 while exiting through the port 134. 218 is supplied respectively.

A part of the hydraulic pressure from the second port 136 of the manual valve 14 flows into the second port 44 of the regulator valve 6 and acts on the right side surface of the fourth land 58.

At this time, the first and second shift control solenoid valves S1 and S2 are controlled to be turned off and on by the transmission control unit TCU, and the first pressure control solenoid valve S3 and the second pressure control solenoid valve S4 are controlled. ) Is controlled duty, and damper clutch control solenoid valve (S5) is controlled to the off state.

The control of these solenoid valves is for realizing the D range 1 speed by operating the first friction element C1 among a plurality of friction elements, and the process of supplying hydraulic pressure to the first friction element C1 will be described below.

5 is a hydraulic circuit diagram of the D range 1 speed control. The hydraulic pressure having a suitable pressure for shifting by the regulator valve 6 is supplied to the drive pressure pipe 144 through the manual valve 14. Since the two shift control solenoid valves S1 and S2 are all controlled in the on state, the hydraulic pressure flowing into the first port 152 of the shift control valve 16 is the fifth, sixth, and eighth ports 162 and 164. 168 is released without forming hydraulic pressure.

Accordingly, the valve spool 160 moves to the left side and moves to the stopper 170 by the hydraulic pressure acting on the right side of the first land 178 so that the second land 180 moves to the second port 154 and the fourth port ( 166).

Therefore, the drive pressure does not flow to the 2, 3, and 4 speed lines 148, 150, and 152, and the rear clutch is released through the second pressure control valve 20 along the pipeline 146 branched from the pipeline 144. Only the first port 230 of the valve 30 flows.

At this time, since the rear clutch release valve 30 is in a state where no coalescence is applied to the other port, the valve spool 238 is moved to the left side in the drawing by the elastic force of the spring 244.

As a result, the first land 240 is located on the left side of the first port 230, and the second land 242 is located on the right side of the fourth port 236. 236 is in communication with the hydraulic pressure supplied to the first port 230 is supplied to the first friction element (C1) to operate the clutch is to make a first speed shift.

At this time, the first pressure control valve 18 is a state in which the pressure flowing into the first port 198 is controlled by the first pressure control solenoid valve S3 turned on to release the pressure, and the second port 200 Since the pressure introduced into) acts on the right side of the second land 210, the valve spool 206 moves to the left to block the third port 202 so as to stay there.

In addition, the hydraulic pressure flowing into the first port 216 of the second pressure control valve 20 is controlled by the elastic force and the hydraulic pressure of the spring 224 because the second pressure control solenoid valve S4 is controlled to be in an off state. As a result, the valve spool 214 is pushed to the right to supply the hydraulic pressure flowing from the conduit 146 to the rear clutch release valve 30.

FIG. 6 is a hydraulic circuit diagram of the D range 2 speed. When the vehicle speed increases or the opening degree of the throttle valve increases in the state of 1 speed, the transmission control unit (TCU) is the first shift control solenoid as shown in the table of FIG. 20. The duty control of the first pressure control solenoid valve S3 is started while the valve S1 is controlled to be in an OFF state.

This control is for realizing the D range 2 speed, and the hydraulic pressure is formed in the fifth port 162 and the sixth port 164 of the shift control valve 16 by turning off the first shift control solenoid valve S1. Then, the plugs 174 and 176 located at the left and right sides are moved to the place where the stoppers 170 and 172 are positioned.

Accordingly, the valve spool 160 in the first speed state is pushed slightly to the right by the plug 174 so that the second land 180 is located between the second port 154 and the third port 156 so that the second speed line 148 is in communication with the first port 152.

As a result, a part of the hydraulic pressure flowing to the drive pressure pipe 144 flows into the fifth port 272 of the 1-2 shift valve 24 through the second speed line 148 and acts on the valve spool 266, respectively.

That is, the hydraulic pressure introduced into the fifth port 272 of the 1-2 shift valve 24 acts on the left side of the first land 274 to push the valve spool 266 to the right.

However, since the first pressure control solenoid valve S3 is duty controlled, the hydraulic pressure flowing into the first port 198 of the first pressure control valve 18 gradually increases to move the valve spool 206 to the right.

Accordingly, the valve spool 206 of the first pressure control valve 18 moves from the left side to the right side and communicates with the third port 202 and the fourth port 204 to reduce the hydraulic pressure of the drive pressure line 146 by 1-2. The third port 268 of the shift valve 24 is supplied.

At this time, since the valve spool 266 of the 1-2 shift valve 24 is pushed to the right, the third port 268 and the first port 262 communicate with each other, so that the drive pressure is moved to the second friction element C2 operating side. As it enters, it activates this friction element.

At the same time, since the first friction element C1 acting at the first speed continues to operate, the second speed is realized. As the operation is completed, the first pressure control solenoid valve S3, which is duty controlled, is turned off to perform the second speed control. You are done.

FIG. 7 is a hydraulic circuit diagram of the D range third speed. When the vehicle speed increases or the opening degree of the throttle valve increases in the second speed state, the transmission control unit TCU turns on the second shift control solenoid valve S2. In the state, the first pressure control solenoid valve S3 is started to be duty controlled while gradually being turned off.

Then, since the second shift control solenoid valve S2 is controlled to be in the off state in the second speed state, hydraulic pressure is applied to the fifth port 162, the sixth port 164, and the eighth port 168 of the control valve 16. The valve spool 160 is moved to a state in which the valve spool 160 is in contact with the plug 176 by hydraulic pressure acting on the left side surface of the first land 178.

As a result, the second land 180 of the valve spool 160 is positioned between the third port 156 and the fourth port 158 to connect the second speed line 148 and the third speed line 150 to the first port ( 152).

By this action, the drive pressure flowing into the first port 152 is supplied to the 1-2 shift valve 24, the 2-3 / 3-4 shift valve 26 and the end clutch valve 28 as in the case of the second speed. As the hydraulic pressure of the third speed line 150 is supplied to the first port 246 of the 2-3 / 4-3 shift valve 26, the valve spool 256 moves to the right to the third port 252. And the fourth port 254 communicate with each other, so that the pressure is passed to the third port 252 of the 2-3 / 4-3 shift valve 26 so that the drive pressure passes through the non-operating shaft of the second friction element C2. And some hydraulic pressure of the third speed line 150 flows into the third port 286 of the end clutch valve 28.

Therefore, since the valve spool 290 of the end clutch valve 28 is moved to the left by the spring 296 to the right, the third port 286 and the fourth port 288 communicate with each other, thereby preventing hydraulic pressure. By operating the two friction elements C3, the third speed shift is completed.

That is, in the third speed, the shift is performed by the operation of the first friction element C1 and the third friction element C3.

In the third speed state, since the first and second shift control solenoid valves S1 and S2 are both in an off state, the first and second shift control solenoid valves S1 and S2 are used as an emergency mode that occurs when there is a failure of a transmission control unit or an abnormality in an electric device.

Looking at the change in the hydraulic pressure of the shifting process, as shown in Figure 15, the first friction element (C1) is supplied with a constant hydraulic pressure to continue to operate, the hydraulic pressure of the operating side (SA) of the second friction element (C2) When the hydraulic pressure is gradually supplied to the third friction element C3 at the time when it starts to decrease, the operating pressures of the operating side SA and the non-operating side SR of the second friction element C2 increase at the end of the shifting speed. The shift in the stomach is complete.

FIG. 8 is a hydraulic circuit diagram of a speed change process of the D range 3 speed to 4 speed. When the vehicle speed increases or the opening degree of the throttle valve increases at the 3 speed, the transmission control unit (TCU) is connected to the first shift control solenoid valve ( The first pressure control solenoid valve S3 is duty controlled while controlling S2) from off to on.

Then, the hydraulic pressure acting on the fifth port 162 and the sixth port 164 of the shift control valve 16 is released through the discharge passage by the first pressure control solenoid valve S3 (see FIG. 8 XXXXX). Since the hydraulic pressure is released and the hydraulic pressure is formed only in the eighth port 168, the valve spool 160 moves completely to the right side while pushing the plug 176.

Accordingly, the drive pressure flows simultaneously to the 2, 3, and 4 speed lines 148, 150, and 152, wherein the hydraulic pressure supplied to the 4 speed line 152 is the second port 232 of the rear clutch release valve 30. And the second port 284 of the end clutch valve 28 move the valve spools 238 and 290 of these valves 30 and 28 from left to right.

Then, the hydraulic pressure flowing into the non-operating side of the second friction element C2 is blocked by the end clutch valve 28 and the third and fourth ports 234 and 236 of the rear clutch release valve 30 communicate with each other. By communicating with the second and fourth ports 250 and 254 of the 2-3 / 4-3 shift valve 26, the hydraulic pressure supplied to the non-operating side of the first friction element C1 and the second friction element C2 is prevented. When the discharge passage of the pipeline 248 is released (see FIG. 8 ///////), the automatic frictional pressure of the second friction element C2 is controlled to release and control the first friction element C1. In the same state as the ninth, the fourth speed shift is completed.

Looking at the change in the hydraulic pressure of each friction element in the shifting process, as shown in Figure 16, the third friction element (C3) is the operating side of the second friction element (C2) in a state in which the constant hydraulic pressure is continuously operated The hydraulic pressure of the SA starts to lower, and then the non-operating side hydraulic pressure of the first friction element C1 and the second friction element C2 is rapidly lowered to a predetermined pressure, and the pressure of the second friction element C2 The hydraulic pressure of the operating side SA increases while maintaining the pressure for a predetermined time, and the pressure of the non-operating side SR of the first friction element C1 and the second friction element C2 is the second friction element C2. The pressure drops slowly until the pressure starts to rise and then drops sharply to release the hydraulic pressure.

And the hydraulic pressure supplied to the first friction enzyme (C1) is blocked by the rear clutch release valve 30, its hydraulic pressure is supplied to the operating side of the second friction element (C2) to double the hydraulic pressure.

Due to this action, the fourth speed is completed, and the vehicle is driven at the highest speed. During this shifting process, the damper clutch control solenoid valve S5 is turned on / off according to the operation of the torque converter control valve 8 and the torque converter 4 ) Directly or non-directly with the engine.

FIG. 10 is a kickdown shift hydraulic circuit diagram from the fourth speed to the third speed of the D range. In this case, the first friction element C1 is operated in the state of the fourth speed, and the hydraulic pressure is applied to the non-operating side of the second friction element C2. Shall be supplied.

Accordingly, the first shift control solenoid valve S1 is controlled from on to off, the second shift control solenoid valve S2 is controlled on, and the first and second pressure control valves S3 and S4 are It will take control.

Then, hydraulic pressure is formed in the fifth and sixth ports 162 and 164 of the shift control valve 16, and the hydraulic pressure of the eighth port 168 is released, so that the valve spool 160 moves to the left at five speeds. By shutting off the hydraulic pressure to the line 152, the force pushing the valve spools 238 and 290 of the rear clutch release valve 30 and the end clutch valve 28 to the right is released, and these valve spools 238 290 is moved to the left in the drawing by springs 244 and 296 supporting them on the right.

As described above, when the valve spools 238 and 290 are moved to the left from the right side, the first friction element C1 communicates with the third port 234 and the fourth port 236 of the rear clutch release valve 30. The hydraulic pressure is supplied, and the fourth port 288 and the third port 236 of the end clutch valve 28 communicate with each other to supply hydraulic pressure to the non-operating side of the second friction element C2.

Then, since the first friction element C1 is operated while the third friction element C3 is in operation, the skip shift to the second speed is performed.

At this time, the hydraulic pressure of the 5-speed line 152 is released through the fourth port 158 and the discharge passage of the shift control valve 16 (see FIG. 10 /////////).

In addition, the hydraulic change in the shifting process is as shown in FIG. 17. As shown in FIG. 17, the operating side SA of the third friction element C3 and the second friction element C2 is controlled by the duty control of the first pressure control solenoid valve S3. Is lowered and then raised, and the operating side SR of the second friction element C2 and the first friction element C1 are the operating side SA of the third friction element C3 and the second friction element C2. At this time, the pressure is maintained for a predetermined time after the slight increase in the control by the second pressure control solenoid valve S4, and the sudden increase in operation stops the operation of the second friction element C2. The element C1 and the third friction element C3 are operated.

FIG. 11 shows a kickdown skip shift hydraulic circuit diagram from the 4th speed to the 2nd speed of the D range, in which case the operating pressure of the third friction element C3 is released and the second friction element C2 is operated in the state of the fourth speed. Therefore, the transmission control unit TCU controls the first shift control solenoid valve S1 from on to off and the second shift control solenoid valve S2 from off to on.

The damper clutch solenoid valve S5 is controlled to be in an off state while the first and second pressure control solenoid valves S3 and S4 are duty controlled to increase the line pressure.

Then, the hydraulic pressure applied to the eighth port 168 of the shift control valve 16 is released through the discharge passage of the second shift control solenoid valve S2 (refer to //////// in FIG. 11). The valve spool 160 moves to the left to block the hydraulic pressure supplied to the third and fourth speed lines 150 and 152 and releases the hydraulic pressure to the third speed line 150 and the fourth speed line 152 through the discharge passage. (See XXXXX in Figure 11).

When the hydraulic pressure of the 3rd and 4th speed lines 150 and 152 is released in this manner, the hydraulic pressure acting on the rear clutch release valve 30 and the end clutch 28 is released, so the valve spools 238 and 290 of these valves are released. In this drawing, the left clutch release valve 30 communicates with the first port 230 and the fourth port 236 so that the hydraulic pressure waiting at the first port 230 is the first friction element C1. Is supplied and operated.

In the end clutch valve 28, the third and fourth ports 286 and 288 communicate with each other so that the hydraulic pressure supplied to the non-operating side of the second friction element C2 and the third friction element C3 is connected to the pipeline ( By releasing through the release passage 248 (see FIG. 11, XXXX), the second friction element C2 is activated, and the operation of the third friction element C3 is stopped to perform a kick-down skip to second speed. To lose.

At this time, as shown in the hydraulic pressure change of each friction element, as shown in FIG. 18, the hydraulic pressure of the non-operating side SR of the third friction element C3 and the second friction element C2 is lowered, and then the first pressure is immediately released. By the control of the control solenoid valve S3, the hydraulic pressure SA of the second friction element S2 is lowered and then rises to the operating pressure again after a certain period of time.

And the first friction element (C1) when the oil pressure of the non-operating side (SR) of the third friction element (C3) and the second friction element (C2) is lowered by the control of the second pressure control solenoid valve (S4). After temporarily rising to maintain a constant pressure, when the operating side (SA) of the first friction element (C2) is raised to rise to operate the first friction element (C1).

And the hydraulic pressure supplied to the third friction element (C3) is supplied to the operating side of the second friction element (C2) to double the hydraulic pressure.

FIG. 12 is a hydraulic circuit diagram for explaining a downshift process from the 3rd speed to the 2nd speed of the D range 3, in which case the operating pressure of the third friction element C3 is released in the state of the third speed and the second friction element C2 is released. The transmission control unit TCU controls the first shift control solenoid valve S1 in the off state and the second shift control solenoid valve S2 in the off state.

The first pressure control solenoid valve S3 is duty controlled, the second pressure control solenoid valve S4 is controlled off, and the damper clutch control solenoid valve S5 is controlled in an off state to increase the line pressure.

Then, the hydraulic pressure applied to the eighth port 168 of the shift control valve 16 is released through the discharge passage of the second shift control solenoid valve S2 (refer to ////// in FIG. 12) and the valve thereof. The spool 160 moves to the left to block the hydraulic pressure supplied to the third speed line 150 and release the hydraulic pressure of the third speed line 150 through the discharge passage (see XXXXX in FIG. 12).

When the hydraulic pressure of the three-speed line 150 is released in this manner, the hydraulic pressure that is acting on the 2-3 / 4-3 shift valve 26 is released, so that the valve spool 256 of the valve moves to the left in the drawing, and thus the fourth By communicating the port 254 with the second port 250, the hydraulic pressure supplied to the non-operating side of the second friction element C2 and the third friction element C3 is released through the discharge passage of the conduit 248. (See FIG. 12 // // //), the second friction element C2 is operated, and the operation of the third friction element C3 is stopped to allow the shift to the second speed.

Looking at the change in the hydraulic pressure of each friction element in the shifting process, as shown in Figure 19, the first friction element (C1) is the operation of the second friction element (C2) in the state that the constant hydraulic pressure is supplied to continue operation The hydraulic pressure of the side SA starts to lower, and the non-operating side hydraulic pressure of the third friction element C3 and the second friction element C2 is predetermined before the operating side SA of the frictional element C1 lowers. The pressure is rapidly lowered, the hydraulic pressure of the operating side (SA) of the second friction element (C2) is raised while maintaining the pressure for a predetermined time, the third friction element (C3) and the second friction element (C2). The pressure of the non-operating side SR of the is complete just before the pressure of the second friction element C2 rises.

And the hydraulic pressure supplied to the third friction element (C3) is supplied to the operating side of the second friction element (C2) to release the hydraulic pressure.

FIG. 13 is a hydraulic circuit diagram showing a shift state of the L range 1 speed, wherein the first and second shift control solenoid valves S1 and S2 are controlled to be turned on, and the first pressure control solenoid valve S3 is controlled to duty. The second pressure control solenoid valve S4 is controlled off.

As a result, the oil passing through the manual valve 14 is supplied to the shift control valve 16 through the drive pressure pipe 144, but the other valve depends on the on control of the first and second shift control solenoid valves S1 and S2. The hydraulic pressure of the furnace is not transmitted, and the third ports 202 and 220 of the first and second pressure control valves 18 and 20 are supplied through the branch pipe 146.

Then, in the first and second pressure control valves 18, the valve spools 206 and 214 are turned to the right by the duty control of the first and pressure control solenoid valves S3 and the off control of the second pressure control solenoid valves S4. The hydraulic pressure is transmitted to the 1-2 shift valve 24 and the rear clutch release valve 30 by communicating with the third port 202, 220 and the fourth port 204, 222, respectively.

In addition, the 1-2 shift valve 24 and the rear clutch release valve 30 move the valve spools 266 and 238 to the left side by the springs 280 and 244. By operating the friction element C1 and the fourth friction element C4, the shift in the L range 1 speed is achieved.

In addition, although not shown in the drawing, when shifting down from the second speed to the first speed in the D range 2, the operating pressure of the second friction element C2 is released and the speed is shifted by the one-way clutch.

FIG. 14 is a hydraulic circuit diagram of the R range. When the selection lever is switched to the R range, the hydraulic pressure generated by the oil pump 2 is converted into the manual valve 14 while the port of the manual valve 14 is interlocked. 14 flows into the first port 132 and flows along the reverse pressure pipeline 42 through the fourth port 138 to operate the fifth friction element C5 and is supplied to the regulator valve 6 at the same time. The pressure will be adjusted.

Part of the hydraulic pressure is supplied to the second port 190 of the N-R control valve 22.

At this time, the NR control valve 22 moves the valve spool 184 to the left by the hydraulic pressure reduced in the reducing valve 12 by the duty control of the first pressure control solenoid valve S3. By communicating with the third port 192, the hydraulic pressure of the second port 190 is supplied to the fourth port 270 of the 1-2 shift valve 24, pushing the valve spool 266 to the right, and the fourth friction It is fed to element C4 to achieve reverse shift.

As such, in the reverse mode, hydraulic pressure is supplied to the fourth friction element C4 and the fifth friction element C5 to reverse the vehicle.

Thus, in the hydraulic control system of the present invention in which the shift is made, the configuration of the rear clutch release valve and the end clutch valve is simplified, and the hydraulic pressure of the fifth friction element, which is the reverse friction element, is directly supplied from the manual valve without passing through a separate valve. By doing so, the overall configuration of the hydraulic control system can be simplified.

Then, back pressure control of the hydraulic pressure supplied to the 3-4 upshift and 4-2 kickdown skipshift and 3-2 downshift operation to release the friction element is performed to back pressure control the friction element. It can be changed and controlled.

In addition, since the fifth friction element can be used only in reverse, the flow path is simplified, and shift control of 2-3, 3-4, 4-3, and 3-2 is independently performed.

Claims (11)

An oil pump driving together with the engine to generate oil pressure; A torque converter for transmitting the driving force of the engine to the input shaft of the transmission; A regulator valve for varying the line pressure generated by the oil pump together with the damper clutch due to the duty of the damper clutch control solenoid valve during the driving mode switching and the high speed driving; A reducing valve configured to supply pressure lower than the line pressure; A manual valve for supplying hydraulic pressure to the drive pressure pipe line in the D range through linkage with the selection lever, and directly supplying hydraulic pressure to the fifth friction element through the reverse pressure pipe in the R range; Connected to the above-mentioned drive pressure line, on / off and duty control by the transmission control unit according to the opening speed of the vehicle speed and the throttle valve are supplied to a plurality of valves related to the shift by the action of two shift control solenoid valves. A shift control valve; A rear clutch release valve for converting a port for supplying drive pressure to the first friction element at D ranges 1, 2, and 3 speed; Port shift is made by the first pressure control solenoid valve to supply the drive pressure to the actuation and deactivation side of the second friction element and the third and fourth friction elements during the automatic shift except N → D and 2-1. A first pressure control valve; A second pressure regulating valve in which port switching is effected by a second pressure control solenoid valve which is duty controlled to supply hydraulic pressure to the first friction element during N → D and 4 → 3, 4 → 2 automatic shifting; A 1-2 shift valve in which port conversion is made to supply hydraulic pressure to the actuating side or non-actuating side of the second friction element and the third friction element by the second speed line pressure of the shift control valve; An end clutch valve in which port switching is performed by four-speed line pressure to supply hydraulic pressure to the third friction element; Port change is made by the 3rd speed line pressure and the 4th speed line pressure of the shift control valve, and when the gears of 3-4, 4-2, 4-3 are shifted, the working release side of the second friction element and the third friction element Hydraulic control system for a four-speed automatic transmission for automobiles including a 2-3 / 4-3 shift valve to release the hydraulic pressure. The first pressure control solenoid valve of claim 1, wherein the first pressure control solenoid valve is duty-controlled during the D range 3-4 upshift to operate the hydraulic pressure supplied to the first friction element at the preceding shift stage in conjunction with the release side hydraulic pressure of the second friction element. A hydraulic control system of a four-speed automatic transmission for a vehicle, characterized in that the release side control to control the side hydraulic pressure to release as back pressure control. The first pressure control solenoid valve of claim 1, wherein the first pressure control solenoid valve is duty-controlled during the D range 4-2 skip shift operation to operate the hydraulic pressure supplied to the third friction element at the preceding shift stage in conjunction with the release side hydraulic pressure of the second friction element. A hydraulic control system for a four-speed automatic transmission for automobiles, characterized in that the release side is controlled to release the back pressure control by controlling the side hydraulic pressure. According to claim 1, wherein the first pressure control solenoid valve is duty-controlled in the D range 3-2 downshift shifting process to link the hydraulic pressure supplied to the third friction element at the preceding shift stage with the release side hydraulic pressure of the second friction element. A hydraulic control system of a four-speed automatic transmission for a vehicle, characterized in that the control of the operating side hydraulic pressure to control the release side friction element to be released as back pressure control. The rear clutch release valve according to claim 1, wherein the rear clutch release valve communicates with a first port communicating with the second pressure control valve, a second port communicating with the fourth speed line of the shift control valve, and a 2-3 / 4-3 shift valve. A valve body having a third port and a fourth port communicating with the first friction element; A first land positioned between the first port and the fourth port so as to selectively communicate with the first port, and a second formed at one side of the first land to selectively communicate with the third port and the fourth port A hydraulic control system for a four-speed automatic transmission for a vehicle including a valve spool having a land and one side of which is supported by a spring. The 2-3 / 4-3 shift valve according to claim 1, wherein the 2-3 / 4-3 shift valve includes a first port communicating with a third speed line of the shift control valve, and a second port and a 1-2 shift valve connected to a third port of the rear clutch release valve. A valve body having a third port connected with the fourth port and a fourth port connected with the second friction element and the third friction element; A first land having three lines of hydraulic pressure and a second land formed at one side of the first land to open and close the third port, and one side includes a valve spool supported by a spring; Hydraulic control system of 4-speed automatic transmission for automobiles. The end clutch valve of claim 1, wherein the end clutch valve includes a first and second port connected to these lines to receive hydraulic pressure from the third and fourth speed lines of the shift control valve, and the 2-3 / 4-3 shift valve. A valve body having a third port connected with the fourth port and a fourth port connected with the third friction element; A first land in which the hydraulic pressure flowing into the second port acts, and a second land formed on one side of the first land so as to selectively block the first port, the valve spool one end is supported by a spring Hydraulic control system of a four-speed automatic transmission for cars. The method of claim 1, wherein the shift of 3-4, 4-2, 3-2 is carried out on the pipeline connecting the third port of the rear clutch release valve and the second port of the 2-3 / 4-3 shift valve. A hydraulic control system of a four-speed automatic transmission for a vehicle, characterized in that a discharge port for releasing the hydraulic pressure of the non-operating side and the third friction element of the first friction element and the second friction element. The valve of claim 1, wherein the third friction element is configured to receive hydraulic pressure through the first pressure control valve and the 1-2 shift valve, and the 2-3 / 4-3 shift valve and the end clutch valve at three speeds. Hydraulic control system of a four-speed automatic transmission for cars, characterized in that connected with. The motor vehicle according to claim 1, wherein the third friction element is connected to the end clutch valve so that the hydraulic pressure of the third speed line can be supplied by the port change of the end clutch valve controlled from the fourth speed to the fourth speed line. Hydraulic control system of 4 speed automatic transmission. The fifth friction element is connected to the reverse pressure pipe so that the hydraulic pressure can be directly supplied from the reverse pressure pipe of the manual valve in the R range, and the fourth friction element is connected to the hydraulic pressure from the ND control valve 1-2. Hydraulic control system of a four-speed automatic transmission for automobiles, characterized in that connected to the 1-2 shift valve to receive the hydraulic pressure through the shift valve.