KR100262573B1 - Hydraulic control system for a/t - Google Patents

Abstract

PURPOSE: A hydraulic pressure control system for an automatic transmission is provided to attenuate a static shock by operating a frictional factor during a speed change from a drive range to a reverse range in a neutral range and controlling the frictional factor with drive pressure and torque pressure. CONSTITUTION: A hydraulic pressure control system consists of a line pressure adjusting device(7) adjusting hydraulic pressure from an oil pump(3) with line pressure corresponding to each gear lever and the opening degree of a throttle valve; a converter clutch control device(5) controlling a converted clutch with hydraulic pressure from the line pressure adjusting device; a torque pressure converting device(9) converting hydraulic pressure form the line pressure adjusting device to torque pressure lower than the line pressure; and a speed change control device(11) selectively feeding hydraulic pressure to each frictional factor by controlling hydraulic flow from the line pressure adjusting device and the torque pressure converting device. Furthermore, the control system contains an N-D control valve selectively receiving line pressure from the line pressure adjusting device, drive pressure from a manual valve and torque pressure from the torque pressure converting device, and feeding line pressure and drive pressure to each frictional factor. Thus, the control system attenuates a static shock until a starting.

Description

Hydraulic control system for automatic transmission

FIG. 1 is a hydraulic circuit diagram formed in a neutral N range of a hydraulic control system for an automatic transmission according to the present invention. FIG.

FIG. 2 is a detailed view of an N-D control valve for explaining a hydraulic control system for an automatic transmission according to the present invention; FIG.

3 is a hydraulic circuit diagram for explaining a process in which the hydraulic control system for an automatic transmission according to the present invention is shifted from a neutral N range to a running D range.

FIG. 4 is a hydraulic circuit diagram in which a hydraulic control system for an automatic transmission according to the present invention is formed in a running D range. FIG.

5 is a hydraulic circuit diagram for explaining a process in which the hydraulic control system for an automatic transmission according to the present invention is shifted from a neutral N range to a reverse R range;

6 is a hydraulic circuit diagram in which a hydraulic control system for an automatic transmission according to the present invention is formed in a reverse R range;

The present invention relates to a hydraulic control system for an automatic transmission, and more particularly to a hydraulic control system for an automatic transmission, in which a friction element to be operated upon shifting to a driving D range and a reverse R range is operated first in a neutral N range, And more particularly to a hydraulic control system for an automatic transmission in which a friction element operated when shifting to a reverse R range is controlled by a drive pressure and a torque pressure to reduce a static shock generated from a stop state to a start point.

In general, a vehicular automatic transmission includes a torque converter for converting the torque of an engine, a multi-stage transmission mechanism connected thereto, and a hydraulic operation friction element for selecting and controlling one of the gear stages of the multi-stage transmission mechanism according to the running state of the vehicle Respectively.

The hydraulic operating friction element is provided so as to control each stage of the multi-stage transmission mechanism constituted by the planetary gear set, wherein the friction element is operated or deactivated by a hydraulic control system for controlling the hydraulic pressure pressurized by the oil pump, The automatic transmission is realized by changing the gear ratio of the gear device.

Further, the friction element is operated by selective action of the hydraulic pressure that is switched by the plurality of valves provided in the hydraulic control system, and the manual valve is port-converted by the selection position of the shift lever operated by the driver Hydraulic pressure is supplied from the oil pump and is connected to the oil line so as to supply hydraulic pressure to the torque-pressure converting means and the speed-change control means.

The hydraulic control system for an automatic transmission as described above generally has a line pressure adjusting means for controlling the hydraulic pressure discharged from an oil pump by line pressure and a converter clutch for operating and deactivating the converter clutch by line pressure supplied from the line pressure adjusting means. Torque pressure converting means for controlling and distributing the line pressure supplied from the control means and the line pressure adjusting means by the torque pressure and controlling the flow direction of the hydraulic pressure supplied from the line pressure adjusting means and the torque pressure converting means to operate the respective friction elements Or non-actuated, and is configured to selectively operate one or a plurality of friction elements to achieve a plurality of gear positions.

However, in the neutral N range, only one friction element is directly controlled by the line pressure, only one friction element is controlled in the running D range by the torque pressure at the beginning of the shift, , It is controlled by the drive pressure, and a friction element operated in the reverse R range is directly controlled by the backward drive pressure, so that the shock generated from the stop state to the starting point in the shift from the neutral N range state to the D range of travel and the reverse R range That is, the static shock is increased.

SUMMARY OF THE INVENTION Accordingly, the present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a friction element which is operated in a D range and an R range in a neutral N range, The present invention provides a hydraulic control system for an automatic transmission wherein a frictional element operated upon shifting to a range and a reverse R range state is controlled by a drive pressure and a torque pressure to reduce a static shock generated from a stop state to a start point.

In order to achieve this, the hydraulic control system for an automatic transmission according to the present invention comprises line pressure control means for controlling the hydraulic pressure discharged from the oil pump to a line pressure corresponding to the opening ratio of each of the speed change stages and the throttle valve, A converter clutch control means for controlling the converter clutch in the torque converter by receiving the hydraulic pressure, torque-voltage conversion means for receiving hydraulic pressure from the line-pressure control means and converting the hydraulic pressure to a torque pressure lower than the line pressure, And a shift control means for controlling the flow direction of the hydraulic pressure supplied from the line pressure control means and selectively supplying the hydraulic pressure to each friction element to realize a shift, wherein the line pressure is supplied from the line pressure control means, , And the torque pressure It receives the torque pressure fed from the means, a N-D control valve which is controlled by the torque pressure for supplying the line pressure and the drive pressure supplied to the frictional element as described above, which correspond to the respective speed change stages.

In the neutral N range, the ND control valve supplies the line pressure supplied from the line pressure regulating means to the friction element which is operated in the forward D range and the reverse R range and to the friction element which is operated in the reverse R range, The friction elements work together.

During the N → D shift, the ND control valve releases one friction element that will operate in the reverse R range, and at the same time controls one of the friction elements operating in D range 1 with torque pressure and drive pressure control, A friction element that is commonly operated in the running D range and the reverse R range is converted and controlled to the torque pressure from the line pressure.

In the running D range, the ND control valve interrupts the line pressure supplied from the line pressure adjusting means and supplies the drive pressure supplied from the manual valve to a carriage element operated in the running D range to actuate this friction element, The torque pressure supplied from the pressure converting means is supplied to one friction element operated in the neutral N, reverse R range to actuate this friction element.

In the case of N → R shift, the ND control valve continuously controls the friction factor, which is common to both the driving D range and the reverse R range, to the line pressure, and that one friction element operating in the neutral N range is driven by the drive pressure When controlled, the hydraulic pressure supplied to the friction element is shut off.

In the reverse R range, the N-D control valve actuates a friction element that operates in common in the neutral N range and the reverse R range with the line pressure supplied from the line pressure adjusting means.

The ND control valve includes first and second ports connected to the line pressure adjusting means by a line pressure line to receive line pressure, a third port connected to the torque pressure converting means and the torque pressure line for receiving the torque pressure, A fourth port connected to the manual valve and the drive pressure pipe for receiving the drive pressure when the D range is selected, a line pressure supplied to the first port, and a torque pressure supplied to the third port, D, a fifth port connected to the fourth clutch valve of the transmission control means through a channel so as to supply the frictional element acting in common to the reverse R range, and a fifth port operable to drive the line pressure supplied to the second port from the reverse R range A sixth port connected to the friction element and a channel to supply the friction force to the third port and a torque pressure supplied to the third port by driving pressure in the driving D range A seventh port for first supplying a friction element to the seventh port, an eighth port for selectively applying a torque pressure and a drive pressure to the seventh port, a hydraulic pressure sensor for selectively applying a torque pressure supplied to the eighth port, And a valve spool which is provided on the opposite side of the chamber and the hydraulic chamber with an elastic member to allow the port pressure to be converted by the torque pressure and the drive pressure selectively acting on the hydraulic chamber.

The valve spool includes a first land forming a hydraulic hydraulic pressure receiving surface on which a hydraulic pressure supplied to the hydraulic chamber is applied and interrupting the communication between the fourth port and the eighth port and a second land formed on one side of the first land, Third and fourth lands formed on one side of the second land to intercommunicate the communication between the first port and the fifth port, and third and fourth lands formed on one side of the fourth land, And a fifth land for interrupting the communication between the second port and the sixth port together with the fourth land and controlling the hydraulic pressure discharged from the sixth port.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a hydraulic circuit diagram formed in a neutral N range of an oil pressure control system for an automatic transmission according to the present invention.

The hydraulic control system includes a torque converter 1 disposed between a crankshaft of the engine and a transmission to torque-convert and transmit the power of the engine, a drive gear provided in the pump drive hub of the torque converter 1, A converter clutch control means 5 for activating and deactivating a converter clutch mounted on the torque converter 1 by varying an oil pressure generated by the oil pump 3; ).

The hydraulic pressure control system includes line pressure adjusting means 7 for controlling the hydraulic pressure supplied from the oil pump 3 to line speeds corresponding to respective speed change stages and throttle opening rates, The line pressure, the drive pressure and the torque pressure are selectively supplied from the torque-pressure converting means 9, the torque-pressure converting means 9 and the line-pressure adjusting means 7, And a shift control means (11) for realizing a shift by operating each friction element so as to control each element as an input element, an output element and a reaction force element.

The converter clutch control means 5 receives the hydraulic pressure supplied from the line pressure regulating means 7 to the converter feed valve 13 to return the required hydraulic pressure to the oil pan 15 and the appropriate hydraulic pressure is supplied to the converter clutch regulator valve (17) into the torque converter (1) so as to enable or disable the converter clutch mounted thereon. The converter clutch regulator valve 17 controls the hydraulic pressure supplied from the converter feed valve 13 by the duty ratio of the first solenoid valve S1 whose duty is controlled by a transmission control unit ).

The line pressure regulating means 7 for supplying the hydraulic pressure to the converter clutch control means 5 for controlling the hydraulic pressure so as to activate or deactivate the converter clutch as described above regulates the hydraulic pressure supplied from the oil pump 3 to the regulator valve 19, And when the hydraulic pressure is higher than or equal to a pressure appropriate for the running state of the vehicle, a part of the oil is returned to the oil pan 15 to supply the line pressure to the torque-torque converting means 9 or the transmission control means 11.

The regulator valve 19 regulates the solenoid supply pressure, which is regulated and supplied by the regulator valve 19 and supplied and converted by the torque-pressure converting means 9, and the solenoid supply pressure, which is converted and supplied by the manual valve 21, So that the line pressure can be readjusted by the pressure. The solenoid supply pressure supplied from the torque-torque converting means 9 is supplied to the first solenoid valve S1 and supplied to the second solenoid valve S2 as the converter clutch regulator 17 is controlled, 19). The second solenoid valve S2 is also duty-controlled by the TCU to control the amount of oil returned from the regulator valve 19 to the oil pan 15.

As described above, the torque-pressure converting means 9, which receives the line pressure from the regulator valve 19 of the line pressure adjusting means 7 for adjusting the line pressure, converts the line pressure into the solenoid supply pressure by the solenoid supply valve 23 And supplies the control pressure to each solenoid valve including the first and second solenoid valves S1 and S2. The solenoid supply pressure is controlled by the third solenoid valve S3 so that the manual valve 21 controls the torque The torque pressure supplied from the torque control regulator valve 25 to the control switch valve 27 is controlled by the fourth solenoid valve S4 so that the torque pressure supplied to the regulator valve 25 is converted into the torque pressure, To supply the respective valves and friction elements of the shift control means (11).

The third solenoid valve S3 is duty-controlled by the TCU, and the fourth solenoid valve S4 is on-off controlled by the TCU.

The transmission control means 11 receives the torque pressure from the torque-torque converting means 9 and is supplied with the line pressure and the drive pressure from the line pressure adjusting means 7 is driven by the NR control valve 27 in the neutral N range The hydraulic pressure is controlled by the ND control valve 29 and the hydraulic pressure is controlled by the ND control valve 27 and the ND control valve 29 during the shift from the neutral range to the running D range. (3), (3), (3), (3), (3) and (3) and (3), (4) and (3) and (4), depending on the hydraulic pressure supplied and the line pressure and drive pressure supplied from the line pressure adjusting means Second, third, fourth, fifth, sixth, and seventh friction elements (43, 45, 47, 49, 51, 53, 55) .

The 1-2, 2-3, 3-4 shift valves 31, 33, and 35 are connected to the fifth, sixth, and seventh solenoid valves S5, S6, and S7, The line pressure supplied from the manual valve 19 is controlled so that the torque pressure supplied from the torque-pressure converting means 9 and the drive pressure supplied from the manual valve 21 are supplied to the second-, third-, 39, 41 so as to be selectively supplied to these valves (37, 39, 41).

On the other hand, the N-R control valve 27 is arranged to control and supply the backward drive pressure supplied from the manual valve 21 to the fifth friction element 51 by the duty control of the third solenoid valve S3.

As shown in FIG. 2, the ND control valve 29 includes a plurality of ports for receiving line pressure from the line pressure adjusting means 7, The first and second ports 57 and 59 are connected to the line pressure piping 61 and the third port 63 is connected to the torque control regulator valve 25 of the torque- And the fourth port 67 is connected to the drive pressure conduit 69 so as to receive the drive pressure from the manual valve 21. [

The ND control valve 29, which is connected to each of the conduits 61, 65 and 69 and is supplied with the respective hydraulic pressures as described above, is connected to the first and second ports 57 and 59 by the torque pressure supplied to the third port 63, The first and second friction elements 43 and 45 and the sixth friction element 53 control and supply the line pressure supplied to the fourth port 67 and the drive pressure supplied to the fourth port 67, respectively.

The fifth port 71 of the ND control valve 29 is connected to the fourth speed control valve 41 through the conduit 73 so that the line pressure supplied to the first port 57 and the third port 63, To the sixth friction element 53 which is commonly operated in the neutral N range, the running D range, and the reverse R range.

The sixth port 75 is connected to the second friction element 45 through a channel 77 and is connected to a second friction element 45 for operating the line pressure supplied to the second port from the reverse R range, .

The seventh port 79 is connected to the first frictional element 43 through the conduit 81 and is connected to a first frictional element 43 operating as a drive pressure in the traveling D range, To actuate the first friction element 43 first.

The eighth port 83 is connected to the seventh port 79 by a bypass line 85 and is connected to the seventh port 79 through a seventh port 79, The pressure is supplied later and is supplied from the fourth port 67. The bypass line 85 is supplied with the drive pressure to the fourth port 67 by another bypass line 87 And is connected via the drive pressure line 69 and the check valve 89. The check valve 89 prevents the drive pressure supplied to the drive pressure line 69 from being directly supplied to the eighth port 83 and the line 81.

The drive pressure supplied to the eighth port 85 and the torque pressure supplied to the seventh port 79 are supplied to the hydraulic chamber 88 formed on the eighth port 83 and the fourth port 67, And acts on one side of the valve spool 89 that realizes each port conversion as shown in Fig.

The valve spool 89 is resiliently supported by an elastic member 91 interposed on the opposite side of the hydraulic chamber 88 and maintained in a state of being pushed to the left as shown in FIG. 2 in the neutral N range state .

The valve spool 89 is composed of a plurality of lands for realizing port conversion of the N-D control valve 29.

That is, the first land 95 is provided with the hydraulic pressure receiving surface 93 on which the hydraulic pressure supplied to the hydraulic chamber 88 acts and interrupts the communication between the fourth port 67 and the eighth port 83 .

The second land 97 formed on one side of the first land 95 selectively connects the third port 63 to the fifth port 71 and the seventh port 79.

The third land 99 formed on one side of the second land 97 interrupts the communication between the first port 57 and the fifth port 71 to selectively communicate with each other.

The fourth land 101 formed on one side of the third land 99 selectively communicates the second port 59 and the sixth port 75 together with the fifth land 103 formed on one side of the third land 99 And the sixth port (75) and the discharge port (105).

In the hydraulic control system for an automatic transmission configured as described above, each range is determined by a manual valve 21 interlocked with a shift lever, and the TCU turns on / off each solenoid valve depending on the opening rate of the throttle valve and the vehicle speed. Duty control is performed so that each gear range is determined.

[Neutral N range]

The line pressure supplied from the line pressure adjusting means 7 is supplied to the torque converter 1 through the converter clutch control means 5 because the TCU controls all the solenoid valves to be in the ON state in the neutral N range state The converter clutch is inactivated and the manual valve 21 can not supply the drive pressure to the torque control regulator valve 25 of the torque-pressure converting means 9, so that the torque pressure can not be generated.

Therefore, only the line pressure supplied from the line pressure regulating means 7 is supplied to the ND control valve 29 to the first and second ports 57 and 59. This line pressure is common to both the driving D range and the reverse R range I.e., the sixth friction element 53 and the one friction element, i.e., the second friction element 45, which is to be operated in the reverse R range to control the hydraulic control system to the neutral N range state.

As a result, in the neutral N range, the second and sixth friction elements 45, 53 work together (see FIG. 1).

[N → D shifting process]

When the shift lever is operated from the neutral N range state to the travel D range, the manual valve 21 is interlocked and moves from the N range to the D range as shown in FIG.

At this time, the drive pressure supplied from the manual valve 21 is supplied to the torque control regulator valve 25 connected to the drive pressure line 69 and is converted into the torque pressure by the duty control of the third solenoid valve S3 Is supplied to the third port (63) of the ND control valve (29) through the torque pressure line (65). A part of the drive pressure supplied from the regulator valve 35 is supplied to the fourth port 67 of the N-D control valve 29 and waits.

The torque pressure supplied to the third port 63 is supplied to the seventh port 79 communicating with the third port 63 to connect the seventh port 79 to the first friction element 43 And the first friction element 43 is firstly operated while a part of the torque pressure is supplied to the hydraulic chamber 88 through the bypass line 85 and the eighth port 83 connected thereto And acts on the hydraulic receiving surface 93 of the first land 95 of the valve spool 89 to move the valve spool 89 to the right in the drawing.

The drive pressure pending in the fourth port 67 is supplied to the other bypass pipe 87 through the eighth port 83 and simultaneously supplied to the pipeline 81 so that the first friction element 43 to the drive pressure and operate.

The fourth land 101 cuts off the communication of the second and sixth ports 59 and 75 while the valve spool 89 moves to the right and the sixth port 75 communicates with the discharge port 105, Releasing the second frictional element 45 in operation.

The torque applied to the third port 63 to actuate the first friction element 43 through the seventh port 79 and the channel 81 is blocked by the first land 95, The third port 63 and the fifth port 71 are communicated with each other by the two lands 95 and 97 so that the second port 71 is connected to the fifth port 71 through the line 73 connecting the fifth port 71 and the fourth speed clutch valve 41, The sixth friction element 53 which has been operated by the pressure is switched to the torque pressure and operated.

That is, the ND control valve 29 at the time of the N-to-D shift releases the second friction element 45 which is to be operated in the reverse R range and at the same time the first and sixth friction elements 43, 53, the first friction element 43 is controlled by the drive pressure, and the sixth friction element 53, which is commonly operated in the drive D range and the reverse R range, is converted from the line pressure to the torque pressure ㆍ Control.

As a result, the N-D control valve 29 controls the second friction element 45 and the first and sixth friction elements 43 and 53 during the N to D shift.

[Travel D Range]

As described above, when the N-to-D shift process is performed, the D-range 1-speed state is maintained as shown in FIG.

That is, the line pressure supplied from the line pressure regulating means 7 waits at the first and second ports 57 and 59 of the ND control valve 29, and the torque pressure supplied to the third port 63 is maintained The drive force supplied to the fourth port 67 is transmitted to the first frictional element 53 connected to the channel 81 through the eighth port 83, (43).

In other words, in the running D range, the ND control valve 29 interrupts the line pressure supplied from the line pressure regulating means 7 and outputs the drive pressure supplied from the manual valve 21 to the first friction And supplies the torque to the sixth friction element 53 which operates at the neutral N and the reverse R range and supplies the torque to the sixth friction element 53. [ .

As a result, in the D range, the first and sixth friction elements 43 and 53 are operated together.

[N → R shifting process]

When the shift lever is operated from the neutral N range to the reverse R range as described above, the manual valve 21 is interlocked and moves from the N range to the R range as shown in FIG.

Therefore, the backward drive pressure is supplied from the manual valve 21 to the N-R control valve 27. This reverse drive pressure is supplied to the fifth friction element 51 by the duty control of the third solenoid valve S3 to operate it.

At this time, since the manual valve 21 can not supply the drive pressure to the torque control regulator valve 25, the drive pressure and the torque pressure are not supplied to the N-D control valve 29. The line pressure supplied to the first port 57 of the N-D control valve 29 is thus supplied to the fifth port 71 and continues to operate the sixth friction element 53 via the line 73.

However, the line pressure supplied to the second port 59 is supplied to the sixth port 75 via the line 77, but the line 73 is blocked by the reverse drive pressure supplied from the NR control valve 27 do. Therefore, the second frictional element 45, which is operated from the N-R control valve 27 by the reverse drive pressure, is switched to the reverse drive pressure and operated.

In other words, in the N-to-R shift, the ND control valve 29 continuously controls the sixth friction element 53, which operates painfully in the running D range and the reverse R range, to the line pressure, The second friction element 45 is switched to the backward drive pressure supplied from the manual valve 21 and controlled.

As a result, the N-D control valve 29 controls the fifth friction element 51 and the second and sixth friction elements 45 and 53 during the N → R shift.

[Reverse R range]

As described above, when the N? R shift process has elapsed, the R range state is maintained as shown in FIG.

That is, in the reverse R range, the ND control valve 29 switches the second friction element 45, which operates in common in the neutral N range and the reverse R range, to the line pressure supplied from the line pressure regulating means 7 to the reverse drive pressure .

As a result, the second, fifth and sixth friction elements 45, 51 and 53 are operated in the reverse R range.

As described above, in the hydraulic control system for an automatic transmission according to the present invention, the friction elements to be operated upon shifting to the D range and the R range are operated first in the neutral N range, and in the neutral N range, the running D range and the reverse R range state The static shock generated from the stop state to the start point can be reduced.

Claims (3)

Line pressure adjusting means for adjusting the hydraulic pressure discharged from the oil pump to a line pressure corresponding to an opening ratio of each of the speed change stages and the throttle valve; Converter clutch control means for receiving hydraulic pressure from the line pressure regulating means and controlling the converter clutch in the torque converter; Torque-pressure converting means for receiving the hydraulic pressure from the line-pressure adjusting means and converting it into a torque pressure lower than the line pressure; And a shift control means for controlling the flow direction of the hydraulic pressure supplied from the line pressure regulating means and the torque pressure converting means to selectively supply the hydraulic pressure to the respective friction elements to realize shifting. The hydraulic control system for an automatic transmission, , The line pressure from the line pressure adjusting means is supplied to a friction element which operates in common in the D range and the R range and in a friction element which operates in the R range so that the two friction elements are operated together, One of the frictional elements operating in the range is released and at the same time one of the frictional elements operating in the D range 1 is controlled by the torque pressure and then controlled by the drive pressure and the frictional element which operates commonly in the D range and the R range is controlled by the line In the D range, the line pressure supplied from the line pressure adjusting means is changed to the torque And the drive pressure supplied from the manual valve is supplied to and operated as a friction element which operates in the D range, and the torque pressure supplied from the torque-pressure converting means is supplied to and operated as a friction element operating in the N, R range, When a friction element that operates in the N range is controlled by the drive pressure supplied from the manual valve, the frictional element, which operates in common in the D range and the R range, And an ND control valve controlled to operate a friction element which is commonly operated in the N range and the R range by the line pressure supplied from the line pressure adjusting means in the R range, Hydraulic control system. [2] The apparatus as claimed in claim 1, wherein the ND control valve comprises first and second ports connected to the line pressure regulating means via a line pressure line and supplied with line pressure, third and fourth ports connected to the torque pressure converting means by a torque pressure line, A fourth port connected to the manual valve of the port and the line pressure adjusting means through a drive pressure pipe and supplied with the drive pressure when the drive D range is selected, a line pressure supplied to the first port, and a torque pressure supplied to the third port A fifth port connected to the fourth clutch valve of the shift control means through a channel so as to supply a friction element common to the neutral N, the traveling D and the reverse R range, A sixth port connected to the friction element and a duct for supplying a friction element operated by the drive pressure in the range, and a sixth port connected to the friction port through a duct, A seventh port for first supplying a friction element operated by pressure, a eighth port for selectively applying a torque pressure and a drive pressure to the seventh port, a torque pressure and a drive pressure supplied to the eighth port, And a valve spool which is provided on an opposite side of the hydraulic chamber with an elastic member interposed therebetween to allow the port pressure to be switched by the torque pressure and the drive pressure selectively acting on the hydraulic chamber. 3. The hydraulic control apparatus according to claim 2, wherein the valve spool comprises: a first land forming a hydraulic pressure receiving surface on which hydraulic pressure supplied to the hydraulic chamber acts and interrupting the communication between the fourth port and the eighth port; A third land for selectively connecting the third port to the fifth port and the seventh port, and third and fourth lands formed on one side of the second land for interrupting the communication between the first port and the fifth port, And a fifth land interposed between the second port and the sixth port together with the fourth land and interrupting the hydraulic pressure discharged from the sixth port.