JP6721309B2 - Automatic transmission - Google Patents

Description

TECHNICAL FIELD The present invention relates to an automatic transmission in which engagement and release of a friction engagement element is controlled by hydraulic pressure.

In an automatic transmission that hydraulically controls engagement and release of a friction engagement element, it is desirable to reduce the clearance of the friction engagement element before starting engagement in order to prevent shock and vibration during engagement of the friction control device. Further, when the frictional fastening element is released, it is desirable to increase the clearance of the frictional fastening element at the time of release in order to prevent friction loss due to dragging of the frictional fastening element.

As a clearance adjusting device for such a friction engagement element, there is known a device provided with two clutch engagement pistons and clearance adjustment pistons (see Patent Document 1).

JP, 09-112690, A

In the conventional technique described in Patent Document 1, the two pistons are respectively provided with hydraulic chambers, and hydraulic pressure is supplied to the respective hydraulic chambers.

However, when the two pistons are respectively provided with the hydraulic chambers as described above, the number of parts increases, and the weight and size increase. Further, it is necessary to provide two pistons, two hydraulic chambers, and a hydraulic circuit for supplying hydraulic pressure to these, which requires a large design change from the structure of the conventional clutch, which causes a problem of increased cost.

The present invention has been made in view of such problems, and is characterized by providing an automatic transmission that can appropriately adjust the clearance of the frictional engagement element of the clutch without significantly increasing the cost.

According to one embodiment of the present invention, there is provided an automatic transmission having a friction element for connecting and disconnecting a driving force from a driving force source, the piston including a hydraulic chamber and a piston for receiving and connecting the friction element by receiving hydraulic pressure supplied to the hydraulic chamber. When a first oil passage Ru connecting to the hydraulic chamber, a second oil passage that connects the hydraulic chamber, a first hydraulic control unit capable of supplying first hydraulic pressure to the hydraulic chamber via the first oil passage A second hydraulic pressure control unit capable of supplying a second hydraulic pressure lower than the first hydraulic pressure to the hydraulic chamber via the second oil passage and discharging the hydraulic pressure of the hydraulic chamber via the second oil passage. Of the first and second hydraulic pressures, when the first hydraulic pressure is not supplied, the friction element is maintained in the released state, and the first hydraulic pressure control unit controls the second hydraulic pressure control unit to supply the second hydraulic pressure to the second hydraulic pressure control unit. the Rukoto comprising a relief valve for discharging the hydraulic pressure of the second hydraulic control unit, characterized when the hydraulic pressure exceeds a predetermined pressure.

According to the above aspect, in the friction element, the second oil pressure lower than the first oil pressure is supplied from the second oil passage different from the first oil passage before the first oil pressure is supplied from the first oil passage. It is possible to shorten the time required for the friction element to be engaged and the vehicle to travel, and it is possible to suppress the shock at the time of engagement. This makes it possible to increase the piston clearance when releasing the friction element, reduce friction in the released state, and improve fuel efficiency.

It is an explanatory view showing the composition of the vehicle carrying the automatic transmission of the embodiment of the present invention. It is explanatory drawing of the principal part of the hydraulic control circuit of embodiment of this invention. It is explanatory drawing which shows the state of REV/B of embodiment of this invention. It is a flow chart of control which a controller of an embodiment of the present invention performs with respect to a hydraulic control circuit. It is explanatory drawing of the principal part of the hydraulic control circuit of another embodiment of this invention.

<First Embodiment>
The first embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is an explanatory diagram showing the configuration of a vehicle equipped with the automatic transmission 4 of this embodiment.

The vehicle includes an engine 1 as a power source. The output rotation of the engine 1 is transmitted to the drive wheels via a torque converter 2 having a lockup clutch, a forward/reverse switching mechanism 3, an automatic transmission 4, and a final reduction gear 6.

In the vehicle, an oil pump 10 that is driven by utilizing a part of the power of the engine 1 and a pressure of hydraulic oil supplied from the oil pump 10 are regulated to supply hydraulic pressure to each part of the automatic transmission 4. A hydraulic control circuit 11 and a controller 12 that controls the hydraulic control circuit 11 are provided.

The forward/reverse switching mechanism 3 includes a forward clutch (FWD/C) 32 that is engaged when the vehicle travels forward, and a reverse brake (REV/B) 34 that is engaged when the vehicle travels backward. When both FWD/C32 and REV/B34 are released, a neutral state in which power is not transmitted is obtained.

The automatic transmission 4 includes a continuously variable transmission mechanism (hereinafter referred to as "variator 20").

The variator 20 is a belt-type continuously variable transmission mechanism including a primary pulley 21, a secondary pulley 22, and a V-belt 23 wound around the pulleys 21 and 22. The pulleys 21 and 22 are each a fixed conical plate, a movable conical plate that is arranged with a sheave surface facing the fixed conical plate, and forms a V groove between the fixed conical plate, and the back surface of the movable conical plate. And hydraulic cylinders 23a and 23b that are provided in the cylinder to displace the movable conical plate in the axial direction. When the hydraulic pressure supplied to the hydraulic cylinders 23a and 23b is adjusted, the width of the V groove changes, the contact radius between the V belt 23 and each pulley 21 and 22 changes, and the speed ratio vRatio of the variator 20 changes steplessly. To do.

The controller 12 outputs an output signal of an accelerator opening sensor 41 that detects an opening of an accelerator pedal, an output signal of a rotation speed sensor 42 that detects an input rotation speed of the automatic transmission 4, and an output of a vehicle speed sensor 43 that detects a vehicle speed. A signal, an output signal of the inhibitor switch 46 that detects the range position of the select lever 45, an output signal of the brake switch 47 that detects that the brake pedal is depressed, and the like are input. The select lever 45 includes, for example, a forward drive range (D range), a neutral range (N range), and a reverse drive range (R range). The inhibitor switch 46 outputs signals corresponding to these range positions.

The controller 12 determines a target gear ratio based on the input signal, and a gear map previously recorded so that the entire gear ratio (through gear ratio) of the automatic transmission 4 follows the target gear ratio. With reference to the above, a shift control signal for controlling the shift ratio of the variator 20 is generated, and the generated shift control signal is output to the hydraulic control circuit 11.

The hydraulic control circuit 11 adjusts the required hydraulic pressure from the hydraulic pressure generated by the oil pump 10 based on the shift control signal from the controller 12, and supplies the adjusted hydraulic pressure to the lockup clutch of the automatic transmission 4 and the torque converter 2. As a result, the gear ratio of the variator 20 is changed and the automatic transmission 4 is shifted. Further, the torque converter 2 is controlled to the lockup state (including slip lockup) or the converter state depending on the engaged state of the lockup clutch.

FIG. 2 is an explanatory diagram of a main part of the hydraulic control circuit 11 of this embodiment.

In FIG. 2, only the hydraulic circuits related to the FWD/C 32, REV/B 34 of the forward/reverse switching mechanism 3 and the lockup clutch of the torque converter 2 are shown.

In the hydraulic control circuit 11, the pressure of the hydraulic oil supplied from the oil pump 10 is regulated as a line pressure and supplied to the line pressure oil passage PL.

The line pressure oil passage PL is provided with a first pilot valve 101. The first pilot valve 101 supplies the source pressure of the select pressure, which is the hydraulic pressure required to bring the FWD/C 32 or REV/B 34 into the engaged state.

The output of the first pilot valve 101 is supplied to the select pressure solenoid valve 131 and the second pilot valve 102 via the oil passage 121.

The select pressure solenoid valve 131 includes an electromagnetic valve 131A, regulates the hydraulic pressure supplied from the first pilot valve 101, and outputs it as the select pressure to the FWD/C32 or REV/B34 side.

The output of the select pressure solenoid valve 131 communicates with a manual valve 90 that strokes by mechanically or electrically linking the operation of the select lever 45 by the driver.

When the forward travel range (D range) is selected by the operation of the select lever 45 by the driver, the manual valve 90 strokes to one side and supplies the select pressure to the FWD/C32.

When the reverse travel range (R range) is selected by the operation of the select lever 45 by the driver, the manual valve 90 strokes to the other side and supplies the select pressure to the REV/B34 side via the switch valve 141.

When the non-travel range (neutral range (N range) or parking range (P range)) is selected by the operation of the select lever 45 by the driver, the manual valve 90 strokes to an intermediate position between the forward travel range and the reverse travel range. Then, the hydraulic pressure supplied to the FWD/C 32 and the REV/B 34 is drained. As a result, the forward/reverse switching mechanism 30 enters a neutral state in which torque is not transmitted.

The switch valve 141 supplies the select pressure supplied from the manual valve 90 to the REV/B 34 via the first oil passage 151, or makes the oil pressure in the first oil passage 151 less than a predetermined pressure by the relief valve 143. Control or switch.

When the R range is selected by the select lever 45, the select pressure is supplied from the manual valve 90 to the switch valve 141. By supplying the select pressure to the switching port 141A of the switch valve, the switch valve 141 moves to the right in FIG. 2, and the output of the manual valve 90 communicates with the first oil passage 151. As a result, the select pressure is supplied from the first oil passage 151 to the REV/B34, and the REV/B34 is brought into the engaged state.

When the D range or the non-traveling range is selected by the select lever 45, the manual valve 90 is switched and the select pressure is not supplied to the switch valve 141. In this case, the switch valve 141 moves to the left in FIG. 2 due to the action of the spring, and the first oil passage 151 and the relief valve 143 are in communication with each other. In this state, the hydraulic pressure (standby pressure) set by the relief valve 143 is supplied to the REV/B34 or the hydraulic pressure of the REV/B34 is drained, as described later.

The output of the first pilot valve 101 is also supplied to the second pilot valve 102 via the oil passage 121. The second pilot valve 102 supplies the original pressure of the hydraulic pressure required to operate the lockup clutch of the torque converter 2.

The output of the second pilot valve 102 is supplied to the standby pressure solenoid valve 132 and the L/U solenoid valve 201 via the oil passage 122.

The L/U solenoid valve 201 includes an electromagnetic valve 201A, controls the hydraulic pressure supplied from the second pilot valve 102, and outputs it to a switching port of a T/C regulator valve 202 that engages a lockup clutch of the torque converter 2. .. The T/C regulator valve 202 switches the engagement state of the lockup clutch of the torque converter 2 based on the hydraulic pressure supplied from the L/U solenoid valve 201.

The output of the second pilot valve 102 is also supplied to the standby pressure solenoid valve 132 via the oil passage 122. The standby pressure solenoid valve 132 includes an electromagnetic valve 132A, regulates the hydraulic pressure supplied from the second pilot valve 102, and outputs it to the discharge switching valve 142.

The discharge switching valve 142 moves to the lower side in FIG. 2 when the hydraulic pressure is supplied from the standby pressure solenoid valve 132 to the switching port 142A and communicates with the output port of the standby pressure solenoid valve 132. The hydraulic pressure supplied from 153 is supplied to REV/B34 via a 2nd oil path. The standby pressure oil passage 153 is provided with a check valve 144, and regulates the flow of oil from the discharge switching valve 142 to the standby pressure solenoid valve 132 side.

The operations of the select pressure solenoid valve 131, the standby pressure solenoid valve 132, and the L/U solenoid valve 201 are performed by a command signal transmitted from the controller 12.

Next, the operation of the automatic transmission 4 of the present embodiment configured as above will be described.

In the case of the D range, the automatic transmission 4 engages the FWD/C32 and releases the REV/B34 and travels forward, corresponding to the range position of the select lever 45 by the driver. When it is in the R range, the FWD/C32 is released and the REV/B34 is engaged, and the vehicle runs backward. In the case of the non-driving range (N range, P range), both FWD/C32 and REV/B34 are released so that torque is not transmitted to the wheels.

In such a configuration, it is desirable that the REV/B 34, which is used only for backward traveling, has a large clearance between the piston and the clutch plate at the time of disengagement to reduce friction in order to improve fuel efficiency during forward traveling.

On the other hand, when the clearance between the piston and the clutch plate is large, the stroke of the piston until the engaged state becomes large, so the time from the selection of the R range to the backward travel becomes large, The shock at the time of fastening becomes large. This may give the driver a feeling of strangeness.

In the present embodiment, in order to prevent the driver from feeling uncomfortable, the standby pressure is supplied as described above before the REV/B34 is brought into the engaged state, and the piston and the clutch of the REV/B34 are connected to each other. It is configured to reduce the clearance between them.

FIG. 3 is an explanatory diagram showing a state of the REV/B 34 of this embodiment.

The REV/B 34 includes a hydraulic chamber 341, a piston 342, a return spring 343, a clutch plate 344, a disc spring 345, and a retainer 346.

The hydraulic chamber 341 communicates with the first oil passage 151 and the second oil passage 152. When the hydraulic pressure is not supplied to the hydraulic chamber 341, the piston 342 is biased to the release side (left side in FIG. 3) by the return spring 343 (FIG. 3A). In this state, the clearance between the piston 342 and the clutch plate 344 is a predetermined distance A+α [mm] (large clearance).

The predetermined interval A is a state in which the piston 342 and the clutch plate 344 do not come into contact with each other and have no transmission capacity (released state), and a state in which a torque capacity is quickly provided when the hydraulic pressure is further increased, as described later. It is an interval (small clearance) that can be set. Then, when the clearance of REV/B34 is increased, the interval (A+α) is made larger than the predetermined interval A. This distance (A+α) is sufficient to keep the distance between the piston 342 and the clutch plate 344 and prevent the piston 342 from dragging the clutch plate 344.

When the hydraulic pressure is supplied to the hydraulic chamber 341, the piston 342 moves to the engagement side (rightward in FIG. 3). When the hydraulic pressure at this time is the standby pressure, the clearance between the piston 342 and the clutch plate 344 becomes a predetermined distance A (small clearance) in a state of being balanced with the urging force of the return spring 343 (FIG. 3(B)). ).

When the hydraulic pressure supplied to the hydraulic chamber 341 rises above the standby pressure, the piston 342 further moves to the engagement side, and the piston 342 presses the clutch plate 344 via the disc spring 345. When the hydraulic pressure supplied to the hydraulic chamber 341 exceeds the standby pressure and becomes the select pressure, and the piston 342 completely presses the clutch plate 344 against the biasing force of the disc spring 345, the REV/B 34 enters the engaged state (Fig. 3(C)).

FIG. 4 is a flowchart of control executed by the controller 12 of the present embodiment with respect to the hydraulic control circuit 11.

The controller 12 executes the flowchart shown in FIG. 4 in a predetermined cycle (for example, 10 ms).

In step S10, the controller 12 determines whether the range position of the select lever 45 is the R range.

When it is determined that the range position is the R range, the process proceeds to step S20, and the controller 12 controls the hydraulic control circuit 11 to supply the select pressure to the REV/B34, and fastens the REV/B34.

More specifically, while the manual valve 90 is selected to the REV/B34 side by the select lever 45, the controller 12 controls the solenoid valve of the select pressure solenoid valve 131 to supply the select pressure.

When the select pressure is supplied to the switching port 141A of the switch valve 141, the switch valve 141 connects the output of the manual valve 90 and the first oil passage 151, and the select pressure is supplied to the REV/B34. The first oil passage 151 communicates with the second oil passage 152, and the second oil passage 152 communicates the select pressure with the standby pressure oil passage 153 via the discharge switching valve 142. Is regulated. In this way, the select pressure is supplied to the REV/B34, and the REV/B34 is fastened (see FIG. 3C).

When the range position is not the R range, the process proceeds to step S30, and the controller 12 determines whether it is the non-running range (P range or N range).

When it is determined that the vehicle is in the non-running range, the process proceeds to step S40, and the controller 12 controls the hydraulic control circuit 11 to supply the standby pressure to the REV/B34.

More specifically, when the non-traveling range is selected by the select lever 45, the manual valve 90 becomes a drain for both the FWD/C32 and REV/B34. In this state, in the switch valve 141, the relief valve 143 and the first oil passage 151 communicate with each other by the biasing force of the spring. The controller 12 controls the solenoid valve of the standby pressure solenoid valve 132 to supply hydraulic pressure to the switching port 142A of the discharge switching valve 142.

As a result, the second oil passage 152 and the standby pressure oil passage 153 communicate with each other, but the flow to the standby pressure oil passage 153 is restricted by the check valve 144. At this time, the hydraulic pressure in the second oil passage 152 is kept below a predetermined pressure by the relief valve 143 communicating with the first oil passage 151.

With such a mechanism, in the non-driving range, the REV/B 34 is supplied with the standby pressure defined by the standby pressure solenoid valve 132 and the relief valve 143. The standby pressure is a load at which the piston 342 of the REV/B 34 balances the reaction force of the return spring of the clutch disc. As a result, the REV/B 34 enters the standby state (see FIG. 3B).

In the standby state, when the select pressure is supplied thereafter, the time until the REV/B 34 is brought into the engagement state is shortened.

If the range position is neither the R range nor the non-driving range, that is, if it is the forward traveling range (for example, the D range), the process proceeds to step S50, and the controller 12 is based on the output signal of the vehicle speed sensor 43. Then, it is determined whether or not the current vehicle speed is lower than the predetermined vehicle speed.

When the vehicle speed is lower than the predetermined vehicle speed, the controller 12 supplies the standby pressure to the REV/B 34 in step S40.

More specifically, when the D range is selected by the select lever 45, the REV/B34 of the manual valve 90 becomes the drain. At this time, similarly to step S40 described above, in the switch valve 141, the relief valve 143 and the first oil passage communicate with each other by the biasing force of the spring. The controller 12 controls the solenoid valve of the standby pressure solenoid valve 132 to supply hydraulic pressure to the switching port of the discharge switching valve 142.

As a result, the REV/B 34 is supplied with the standby pressure defined by the standby pressure solenoid valve 132 and the relief valve 143. The predetermined vehicle speed in step S50 is set to a speed at which REV/B34 can be engaged when the R range is selected while the vehicle is moving forward at a low speed, and is set to, for example, 10 km/h.

When it is determined that the current vehicle speed is equal to or higher than the predetermined vehicle speed, the process proceeds to step S60, and the controller 12 controls the REV/B34 to the release state.

More specifically, when the D range is selected by the select lever 45, the REV/B34 of the manual valve 90 becomes a drain, and the switch valve 141 is a relief valve due to the biasing force of the spring as in step S40 described above. 143 and the first oil passage communicate with each other. At this time, the controller 12 controls the solenoid valve of the standby pressure solenoid valve 132 so as not to supply the hydraulic pressure to the discharge switching valve 142. As a result, the discharge switching valve 142 is switched to the drain side by the biasing force of the spring, and the hydraulic pressure of the REV/B34 is drained. As a result, the piston 342 of the REV/B34 is retracted by the return spring, and the clutch plate of the REV/B34 is completely released (see FIG. 3(A)).

In this state, the clutch clearance of the REV/B 34 is sufficiently secured, so friction due to dragging is prevented and fuel efficiency is improved.

As described above, in the present embodiment, the controller 12 executes the control shown in FIG. 3 to drain the hydraulic pressure of the REV/B 34 to drain the REV/B 34 when the vehicle is traveling at a predetermined vehicle speed or higher in the D range. B34 is released and dragging of REV/B34 is prevented to improve fuel economy.

On the other hand, when driving at a low vehicle speed in the non-driving range (P range, N range) or D range, the R range may be selected by the driver, so the standby pressure is supplied to the REV/B34. By setting the REV/B 34 in the standby state, it is possible to shorten the time from the selection of the R range to the reverse traveling, and it is possible to suppress the shock at the time of engagement. When the R range is subsequently selected, the REV/B34 can be quickly brought into the engaged state by supplying the select pressure to the REV/B34.

Next, a second embodiment of the present invention will be described.

FIG. 5 is an explanatory diagram of a main part of the hydraulic control circuit 11 of the present embodiment.

FIG. 5 shows a hydraulic circuit related to the FWD/C32, REV/B34 of the forward/reverse switching mechanism 3 and the lockup clutch of the torque converter 2 in the second embodiment. The same components as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted.

In the second embodiment, the lockup pressure output from the L/U solenoid valve 201 is supplied to the switching port 142A of the discharge switching valve 142.

The torque converter 2 engages a lockup clutch when traveling at a predetermined vehicle speed or higher in order to efficiently transmit the driving force of the engine 1 and improve fuel efficiency. When the vehicle starts or stops, the lockup is released for the purpose of torque amplification and vibration suppression. The L/U solenoid valve 201 outputs a lockup pressure when engaging the lockup clutch. The engagement of the lockup clutch is determined by the vehicle speed, and the predetermined vehicle speed is, for example, 10 km/h.

Therefore, in the second embodiment, it is configured to switch between the standby state and the released state of the REB/V 34 by utilizing the engagement/release timing of the lockup clutch.

When the vehicle speed is equal to or higher than the predetermined vehicle speed in the D range, the L/U solenoid valve 201 outputs the lockup switching pressure. The output of the L/U solenoid valve 201 is input to the switching port 142A of the discharge switching valve 142. When the lockup switching pressure is supplied to the switching port 142A, the discharge switching valve 142 is switched to the drain side against the biasing force of the spring, and the hydraulic pressure of the REV/B 34 is drained. As a result, the piston 342 of the REV/B34 is retracted by the return spring, and the clutch plate of the REV/B34 is completely released.

When the vehicle speed is lower than the predetermined vehicle speed in the D range or in the non-running range (P range, N range), the L/U solenoid valve 201 does not output the lockup pressure. In this case, the discharge switching valve 142 switches to a state in which the standby pressure oil passage 153 and the second oil passage 152 communicate with each other by the biasing force of the spring.

In this state, the output from the second pilot valve 102 is supplied to the second oil passage via the oil passage 122 and the standby pressure oil passage 153. At this time, since it is in the D range, the switch valve 141 is switched to the relief valve 143 side and regulates the hydraulic pressure supplied to the second oil passage to a predetermined pressure or less. In this way, the REV/B 34 is supplied with the standby pressure defined by the second pilot valve 102 and the relief valve 143.

When the R range is selected, the controller 12 controls the solenoid valve of the select pressure solenoid valve 131 to supply the select pressure while the manual valve 90 is selected to the REV/B34 side by the select lever 45.

When the select pressure is supplied to the switching port 141A of the switch valve 141, the switch valve 141 connects the output of the manual valve 90 and the first oil passage 151, and the select pressure is supplied to the REV/B34. The first oil passage 151 communicates with the second oil passage 152, and the second oil passage 152 communicates the select pressure with the standby pressure oil passage 153 via the discharge switching valve 142. Is regulated.

Thus, also in the second embodiment, when the vehicle travels at a predetermined vehicle speed or higher in the D range and the lockup clutch is in the engaged state, the hydraulic pressure of REV/B34 is drained to release REV/B34, Prevents dragging of REV/B34 and improves fuel economy.

On the other hand, when traveling at a low vehicle speed in the non-driving range (P range, N range) or the D range, the R range may be selected by the driver, so the standby pressure is supplied to the REV/B34. Then, the REV/B 34 is set in the standby state. As a result, the time from when the R range is selected until the vehicle travels backward can be shortened and the shock at the time of engagement can be suppressed.

As described above, the embodiment of the present invention is the automatic transmission 4 having the friction element (REV/B34) that connects and disconnects the driving force from the driving force source including the engine 1, and is an oil pump as a hydraulic source. The hydraulic pressure chamber 341 to which the hydraulic pressure from 10 is supplied, the piston 342 that connects and disconnects the REV/B34 by receiving the hydraulic pressure supplied to the hydraulic pressure chamber 341, and is connected to the hydraulic pressure chamber 341 to supply the first hydraulic pressure (selection pressure) It is possible to supply the first oil pressure to the hydraulic chamber 341 via the first oil passage 151 and the second oil passage 152 that is connected to the hydraulic chamber 341 and supplies the second hydraulic pressure (standby pressure). A second hydraulic pressure lower than the first hydraulic pressure can be supplied to the hydraulic chamber 341 via the first hydraulic pressure control section (select pressure solenoid valve 131, manual valve 90, switch valve 141) and the second hydraulic passage 152. , A second hydraulic pressure control unit (a discharge switching valve 142, a standby pressure solenoid valve 132) capable of discharging the hydraulic pressure of the hydraulic chamber 341 via the second oil passage 152.

With this configuration, according to the present embodiment, the standby pressure lower than the select pressure from the second oil passage 152 is supplied to the REV/B 34 before the select pressure is supplied from the first oil passage 151. By supplying the pressure, it is possible to shorten the time from when the R range is selected until the vehicle travels backward, and it is possible to suppress the shock at the time of engagement. As a result, the clearance between the piston and the clutch plate can be increased when the REV/B 34 is released, and the friction when the vehicle travels forward can be reduced to improve the fuel efficiency.

Furthermore, by providing two oil passages, a first oil passage 151 and a second oil passage 152, with respect to the hydraulic chamber 341 of the REV/B 34, one piston 342 of one hydraulic chamber 341 can provide standby pressure and select pressure. Since these two states can be controlled, the number of parts does not increase and the size does not increase. This effect corresponds to claim 1.

Further, in the embodiment of the present invention, the first hydraulic control unit discharges the hydraulic pressure of the second hydraulic control unit when the hydraulic pressure supplied from the second hydraulic control unit exceeds the second hydraulic pressure (standby pressure). The relief valve 143 is provided.

With such a configuration, the hydraulic pressure supplied from the second oil passage 152 can be regulated to the standby pressure with a simple configuration including only the relief valve 143. This effect corresponds to claim 2.

Further, in the embodiment of the present invention, the torque converter 2 having the lockup clutch is connected, and the lockup clutch pressure control unit (L/U solenoid valve) that outputs the lockup pressure supplied when the lockup clutch is engaged. 201, T/C regulator valve 202), the second hydraulic pressure control unit discharges the hydraulic pressure of the hydraulic pressure chamber 341 through the second oil passage 152 when the lockup pressure is supplied.

With such a configuration, the REV/B34 can be released when the lockup clutch is engaged (the vehicle speed is equal to or higher than the predetermined vehicle speed), so that the standby pressure and the select pressure of the REV/B34 are controlled without increasing the number of parts. be able to. This effect corresponds to claim 3.

Further, in the embodiment of the present invention, the second hydraulic control unit has the check valve 144 that restricts the flow of hydraulic pressure from the hydraulic chamber 341 through the second oil passage 152, so that by providing two oil passages, Two states of standby pressure and select pressure can be controlled by one piston 342 of one hydraulic chamber 341, and when the hydraulic pressure is supplied from the first oil passage 151, the hydraulic pressure flows out from the second oil passage 152 in many cases. This can be prevented, and the two states of standby pressure and select pressure can be controlled with a simple configuration. This effect corresponds to claim 4.

Although the embodiments of the present invention have been described above, the above embodiments merely show one application example of the present invention, and the technical scope of the present invention is limited to the specific configuration of the above embodiments. is not.

Further, in the above embodiment, a belt type continuously variable transmission mechanism is provided as the variator 20, but the variator 20 is a continuously variable transmission mechanism in which a chain is wound between the pulleys 21 and 22 instead of the V belt 23. It may be. Alternatively, the variator 20 may be a toroidal type continuously variable transmission mechanism in which a tiltable power roller is arranged between an input disc and an output disc.

In the above embodiment, the forward/reverse switching mechanism 3 is provided between the torque converter 2 and the variator 20, but the forward/reverse switching mechanism 3 is provided between the output side of the variator 20 and the final reduction gear 6. May be. Further, the forward/reverse switching mechanism 3 may be a stepped transmission having two speed stages, that is, a first speed and a second speed, as forward speeds.

Furthermore, in the above-described embodiment, the continuously variable transmission including the variator 20 and the auxiliary transmission mechanism has been described as an example, but the present invention is not limited to this, and can be similarly applied to a stepped transmission.

1 Engine 2 Torque Converter 3 Forward/Reverse Switching Mechanism 4 Automatic Transmission 6 Final Reduction Gear 10 Oil Pump 11 Hydraulic Control Circuit 12 Controller 20 Variator 30 Forward/Reverse Switching Mechanism 32 Forward Clutch (FWD/C)
34 Reverse Brake (REV/B)
46 Inhibitor switch 90 Manual valve 101 First pilot valve 102 Second pilot valve 121 Oil passage 122 Oil passage 131 Select pressure solenoid valve 131A Solenoid valve 132 Standby pressure solenoid valve 132A Solenoid valve 141 Switch valve 141A Switching port 142 Discharge switching valve 142A Switching Port 143 Relief valve 144 Check valve 151 First oil passage 152 Second oil passage 153 Standby pressure oil passage 201 L/U solenoid valve 201A Solenoid valve 202 T/C regulator valve 341 Hydraulic chamber 342 Piston

Claims (3)

An automatic transmission having a friction element for connecting and disconnecting a driving force from a driving force source,
Hydraulic chamber,
A piston that connects and disconnects the friction element by receiving the hydraulic pressure supplied to the hydraulic chamber,
A first oil passage connected to the hydraulic chamber;
A second oil passage connected to the hydraulic chamber;
A first hydraulic pressure control unit capable of supplying a first hydraulic pressure to the hydraulic chamber via the first oil passage;
A second hydraulic pressure control capable of supplying a second hydraulic pressure lower than the first hydraulic pressure to the hydraulic chamber via the second oil passage and discharging the hydraulic pressure of the hydraulic chamber via the second oil passage. Department,
Equipped with
Of the first and second hydraulic pressures, when the first hydraulic pressure is not supplied, the friction element is kept in a released state,
The first hydraulic control unit includes a relief valve that discharges the hydraulic pressure of the second hydraulic control unit when the second hydraulic pressure supplied from the second hydraulic control unit exceeds a predetermined pressure. Automatic transmission. The automatic transmission according to claim 1 , wherein
A torque converter with a lockup clutch is connected,
A lock-up clutch pressure control unit that outputs a lock-up pressure supplied when engaging the lock-up clutch,
The automatic transmission, wherein the second hydraulic pressure control unit discharges the hydraulic pressure of the hydraulic chamber via the second oil passage when the lockup pressure is supplied. In the automatic transmission according to claim 1 or 2 ,
The automatic transmission, wherein the second hydraulic pressure control unit includes a check valve that restricts a hydraulic pressure flow from the hydraulic pressure chamber through the second oil passage.

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