JP6568003B2 - Automatic transmission - Google Patents

Description

  The present invention relates to an automatic transmission including a fluid transmission device having a lock-up clutch mounted on a vehicle, for example.

  2. Description of the Related Art Conventionally, as a torque converter (fluid transmission) provided between an internal combustion engine mounted on a vehicle and an automatic transmission, one having a lock-up clutch that can lock up the torque converter has been widely used. A lock-up clutch is generally locked up when the vehicle speed exceeds a predetermined speed and reduces fluid transmission loss in the torque converter. However, since the lock-up clutch is released when the vehicle starts, the torque converter As a result, the vehicle starts while the engine speed increases. The increase in engine speed at the time of departure hinders the improvement of fuel efficiency of the vehicle. Therefore, the so-called flex start control for slip-controlling the lock-up clutch at the time of start is performed to prevent the increase in engine speed and to improve the fuel efficiency. Something to improve is proposed.

  In such a lockup clutch, the engaged state and the released state are controlled by the differential pressure between the on pressure supplied to the engaging oil chamber and the off pressure supplied to the releasing oil chamber. In the hydraulic control device that controls the lock-up clutch, for example, an original pressure is supplied to the engagement oil chamber, and in order to gradually switch the lock-up clutch from the release state to the engagement state, A control valve for gradually discharging the off-pressure is provided. In the control valve, the regulated signal pressure is input, and the release pressure of the release oil chamber is discharged as the signal pressure increases, and the on pressure increases and acts on the release oil chamber via the lock-up clutch. When the off-pressure increases, the off-pressure assists the signal pressure as a feedback pressure and promotes the discharge of the off-pressure from the release oil chamber. When the lockup clutch is switched from the released state to the engaged state, the on-pressure of the engaging oil chamber and the off-pressure of the releasing oil chamber are set to the same hydraulic pressure (that is, zero differential pressure state), and then released. The lockup clutch is engaged by gradually discharging the off pressure of the oil chamber and gradually increasing the differential pressure between the on pressure and the off pressure.

  However, in the zero differential pressure state between the on pressure and the off pressure, in a situation where the rotational speed difference between the input and output of the torque converter is relatively large, the centrifugal hydraulic pressure generated in the on pressure of the engagement oil chamber on the input shaft side of the torque converter May increase due to the difference in rotational speed, and the lockup clutch may be pushed into the release oil chamber. In this case, since the off pressure of the release oil chamber becomes high, the feedback pressure that encourages the discharge of the off pressure acts on the control valve greatly, and the discharge of the off pressure is further promoted more than necessary, and the lockup clutch is engaged. As a result, an engagement shock may occur.

  In order to solve this, when feedback pressure is applied to the control valve, until the release oil chamber communicates with the drain oil passage after the communication with the original pressure of the release oil chamber is interrupted in the control valve, A hydraulic control device has been developed in which the stroke amount (so-called lap amount) of the spool while the release oil chamber is closed is set longer than usual (see Patent Document 1). According to this hydraulic control device, the state in which the hydraulic oil is confined in the release oil chamber at the time of slip engagement of the lockup clutch can be maintained for a long stroke amount, so that the centrifugal hydraulic pressure generated in the engagement oil chamber increases. However, it is possible to prevent sudden switching to the engaged state.

JP 2012-72797 A

  However, in the hydraulic control device described in Patent Document 1, since the lap amount, which is the stroke amount of the spool of the control valve, is increased while the release oil chamber is closed, the signal pressure is supplied to the control valve. Therefore, there is a possibility that the response (differential pressure response) when discharging the off-pressure from the release oil chamber is delayed. In addition, depending on the specifications of the torque converter, the centrifugal hydraulic pressure may be further increased, and it may be possible to cope with this by increasing the lap amount, but in order to maintain the differential pressure response within an appropriate range. There was a limit to increasing the amount of lap.

  Therefore, in the standby state before the lock-up clutch of the fluid transmission device is slip-engaged, the differential rotational speed of the input / output is increased, so that centrifugal hydraulic pressure is generated and the on-pressure in the lock-up clutch becomes larger than the off-pressure. Therefore, an object of the present invention is to provide an automatic transmission that can suppress the engagement shock caused by the centrifugal oil pressure without reducing the differential pressure responsiveness even when there is a possibility that the engagement shock of the lockup clutch may occur.

  An automatic transmission according to the present disclosure is interposed between a speed change mechanism and an output shaft of an internal combustion engine and an input shaft of the speed change mechanism, and an engagement state and a release state are controlled by a differential pressure between an on pressure and an off pressure. A fluid transmission device having a lockup clutch capable of locking up the output shaft and the input shaft by engagement, a solenoid valve for controlling the differential pressure by regulating an output pressure, A hydraulic control device for outputting the controlled on-pressure and off-pressure, and the on-pressure and the off-pressure in the lock-up clutch in an equivalent state in order to perform slip control of the lock-up clutch when starting When waiting, the higher the differential rotational speed between the rotational speed of the output shaft of the internal combustion engine and the rotational speed of the input shaft of the transmission mechanism, the greater the output from the hydraulic control device. The output pressure is adjusted so that the ON pressure and the OFF pressure in the lock-up clutch are maintained in an equivalent state by increasing the OFF pressure side in the differential pressure between the ON pressure and the OFF pressure. A control unit for controlling.

  According to this automatic transmission, the control unit makes the lock-up clutch on-off and the off-pressure in the same state (zero differential pressure state) in order to perform slip control, that is, so-called flex start control, of the lock-up clutch when starting. When waiting, the higher the differential speed between the rotational speed of the output shaft of the internal combustion engine and the rotational speed of the input shaft of the speed change mechanism, the greater the OFF in the differential pressure between the off pressure and the on pressure output from the hydraulic control device. By increasing the pressure side, the output pressure from the solenoid valve is controlled so that the ON pressure and the OFF pressure in the lockup clutch are maintained in an equivalent state. That is, in the zero differential pressure state between the on-pressure and off-pressure in the lock-up clutch, when a large centrifugal oil pressure is generated in the on-pressure of the engagement oil chamber due to a large rotational speed difference between input and output, the control unit The output pressure is controlled to increase the off pressure side output from the hydraulic control device. By increasing the off-pressure side output from the hydraulic control device, the on-pressure and the off-pressure in the lock-up clutch become equal, and the lock-up clutch is pushed from the engagement oil chamber side to the release oil chamber side. Therefore, it is possible to suppress the lockup clutch from being engaged by the on pressure increased by the centrifugal hydraulic pressure. Further, since it is not necessary to increase the stroke amount of the spool while the release oil chamber is closed, the differential pressure response is not lowered. Thus, according to the hydraulic control device of the automatic transmission, even when the input / output differential rotation speed increases when the lock-up clutch is slip-engaged, the hydraulic pressure control is performed without reducing the differential pressure response. The resulting engagement shock can be suppressed.

1 is a schematic hydraulic circuit diagram of a control valve, a lock-up clutch and the like in an automatic transmission according to an embodiment. It is a control valve of the hydraulic control device of an automatic transmission concerning an embodiment, (a) is the 1st state, (b) is the 2nd state, and (c) is the 3rd state. It is explanatory drawing which shows an example of the map for controlling the hydraulic control apparatus of the automatic transmission which concerns on embodiment. 4 is a time chart of vehicle speed, rotation speed, current value, and hydraulic pressure in the automatic transmission according to the embodiment.

  Hereinafter, an automatic transmission 1 according to an embodiment will be described with reference to FIGS. 1 to 4.

  As shown in FIG. 1, the automatic transmission 1 includes a transmission mechanism, a torque converter (fluid transmission device) 2 interposed between an output shaft of the internal combustion engine and an input shaft of the transmission mechanism, a hydraulic control device 3, And an ECU (control unit) 4. The speed change mechanism has a friction engagement element that engages and disengages by supplying and discharging the engagement pressure on a power transmission path from the input shaft to the output shaft, and a plurality of shift speeds can be formed by engaging and disengaging them.

  The torque converter 2 rectifies the pump impeller 21 connected to the output shaft of the internal combustion engine, the turbine runner 22 to which the rotation of the pump impeller 21 is transmitted via the working fluid, and the oil returning from the turbine runner 22 to the pump impeller 21. However, it has a stator 23 that produces a torque increasing action. The turbine runner 22 is drivably coupled to an input shaft of a transmission mechanism that is disposed coaxially with the output shaft of the internal combustion engine.

The torque converter 2 includes a lock-up clutch 24 and an engagement oil chamber 25 and a release oil chamber 26 that are disposed with the lock-up clutch 24 in the axial direction. The lockup clutch 24 is controlled to be engaged and disengaged by a differential pressure ΔP between the on pressure P _ON supplied to the engagement oil chamber 25 and the off pressure P _OFF supplied to the release oil chamber 26. When the lockup clutch 24 is engaged, the output shaft and the input shaft can be locked up by the engagement, and the rotation of the output shaft is directly transmitted to the input shaft.

Engaging oil chamber 25 is provided to engage the lock-up clutch 24, it communicates with the outside by turning pressure port 25a, the exhaust pressure P1 or secondary pressure (source pressure) Psec of the secondary pressure as the ON pressure P _ON Supplied. The release oil chamber 26 is provided to release the lock-up clutch 24, communicates with the outside through the off-pressure port 26a, and is supplied with the secondary pressure Psec as the off-pressure P _OFF .

  Next, the hydraulic control device 3 of the automatic transmission 1 according to the present embodiment will be described. In this embodiment, the actual spool is one in each valve. However, in order to explain the switching position or control position of the spool position, the right half state shown in FIGS. "Half position", left half state "left half position".

The hydraulic control device 3 is a valve body, and includes a primary regulator valve (not shown), a secondary regulator valve (not shown), a line pressure modulator valve (not shown), a linear solenoid valve (solenoid valve) SLU, and a control valve 50. have. The primary regulator valve adjusts the hydraulic pressure generated by an oil pump (not shown) to the line pressure PL based on the throttle opening. The oil pump is connected to the output shaft of the internal combustion engine and is driven by starting the internal combustion engine. The secondary regulator valve adjusts the exhaust pressure of the line pressure PL from the primary regulator valve to the secondary pressure Psec based on the throttle opening, and uses the exhaust pressure P1 as, for example, lubricating oil. The line pressure modulator valve adjusts the line pressure PL to generate a modulator pressure P _LPM2 that is a constant pressure lower than the line pressure PL.

The linear solenoid valve SLU is a so-called normally closed type that shuts off the input port and the output port when not energized and communicates when energized. The linear solenoid valve SLU has an input port SLUa to which the modulator pressure P _LPM2 is input, and an output port SLUb communicated with the third hydraulic oil chamber 53 of the control valve 50 via the orifice 31. The linear solenoid valve SLU regulates the modulator pressure P _LPM2 input from the input port SLUa based on a current command value (command value) from the ECU 4 and supplies a lockup control pressure (output) to the control valve 50. Pressure) PSLU is generated and supplied from the output port SLUb. The linear solenoid valve SLU controls the differential pressure ΔP between the on pressure P _ON and the off pressure P _OFF by adjusting the lockup control pressure PSLU. In this embodiment, the linear solenoid valve SLU is applied as the solenoid valve. However, the present invention is not limited to this, and an on / off solenoid valve capable of adjusting pressure by duty control may be applied.

  The control valve 50 includes a spool 60 slidable between a left half position (lock-up off state, first state) and a right half position (lock-up on state, third state). And a spring 50s formed of a compression coil spring that is biased to the first state. The spool 60 has a first land portion 61, a second land portion 62, a third land portion 63, and a fourth land from the end opposite to the spring 50s toward the spring 50s. Part 64. The first land portion 61 to the third land portion 63 have the same diameter, and the fourth land portion 64 has a larger diameter than the first land portion 61 to the third land portion 63.

The control valve 50 includes a first hydraulic fluid chamber 51 disposed at an end opposite to the spring 50s, a second hydraulic fluid chamber 52 disposed to accommodate the spring 50s, and a first hydraulic fluid. And a third hydraulic oil chamber 53 disposed between the chamber 51 and the second hydraulic oil chamber 52. The first hydraulic oil chamber 51 is provided so that the off pressure P _OFF is input via the orifice 32 in the direction D1 in which the spool 60 is pressed into the third state. The second hydraulic oil chamber 52 is provided so that the secondary pressure exhaust pressure P1 or the secondary pressure Psec is input via the orifice 33 in the direction in which the spool 60 is pressed to the first state, similarly to the spring 50s. It has been. The third hydraulic oil chamber 53 is disposed at a step portion between the third land portion 63 and the fourth land portion 64 of the spool 60, and the pressure receiving area between the third land portion 63 and the fourth land portion 64. Due to the difference, the lockup control pressure PSLU is provided via the orifice 31 in the direction D1 in which the spool 60 is pressed to the third state.

The control valve 50 communicates with the main pressure port 54 for inputting the secondary pressure Psec via the orifice 34, the off pressure port 26 a and the first hydraulic oil chamber 51, and applies the off pressure P _OFF via the orifice 35. The off-pressure port 55 for output, the lubrication port 56 communicating with the lubrication circuit, the on-pressure port 57 communicating with the on-pressure port 25 a and the second hydraulic oil chamber 52 via the orifice 36, and the secondary via the orifice 37 A third input port 58 for inputting the pressure Psec and drain ports 50a and 50b communicating with the drain oil passage are provided. The control valve 50 controls the engagement state of the lockup clutch 24 by controlling the differential pressure ΔP between the on pressure P _ON and the off pressure P _OFF based on the supplied lockup control pressure PSLU.

The control valve 50 can be switched between a first state, a second state, and a third state in which the position of the spool 60 is different by a lockup control pressure PSLU from the linear solenoid valve SLU. In the control valve 50, the spool 60 is slidable between one end (first hydraulic oil chamber 51 side) and the other end (second hydraulic oil chamber 52 side) in the sliding range. Thus, the first to third states can be switched. A lockup control pressure PSLU can act on the spool 60 in the direction D1 from the one end side to the other end side in the sliding direction, and the off pressure P _OFF of the release oil chamber 26 serves as a feedback pressure in the same direction D1. It is possible to act.

When the lockup control pressure PSLU is not supplied to the control valve 50, as shown in FIG. 2A, the spool 60 is in the lockup off state, and the main pressure port 54 and the off pressure port 55 are communicated with each other. The off pressure port 55 and the drain port 50a are blocked, the lubrication port 56 and the on pressure port 57 are communicated, and the on pressure port 57 and the third input port 58 are blocked. At this time, the ON pressure _PON is input from the ON pressure port 57 and supplied from the lubrication port 56 to the circulation circuit. The first state is formed when the spool 60 is located in the first range including one end of the sliding range.

Further, when the lockup control pressure PSLU is gradually supplied, the control valve 50 has the spool 60 between the lockup off state and the lockup on state as shown in FIG. The secondary pressure Psec input to 54 is adjusted based on the lock-up control pressure PSLU, and is in a second state in which it is output from the off pressure port 55 as the off pressure P _OFF . At this time, the off pressure P _OFF output from the off pressure port 55 is fed back to the first hydraulic oil chamber 51 and the off pressure P _OFF is regulated. That is, in the second state, the secondary pressure Psec is output as an off pressure _{P OFF,} OFF pressure _{P OFF} is feedback input to the first hydraulic oil chamber 51, the original pressure port 54 when the off pressure _{P OFF} is increased blocking Then, the off-pressure port 55 and the drain port 50a communicate with each other, and the off-pressure P _OFF is drained. When the off pressure P _OFF is drained and becomes smaller, the feedback input to the first hydraulic oil chamber 51 becomes smaller, so that the original pressure port 54 and the off pressure port 55 are communicated again, and the secondary pressure Psec becomes the off pressure P. _It is output as _OFF . Thus, in the second state, the secondary pressure Psec is regulated based on the lockup control pressure PSLU.

The second state is formed when the spool 60 is positioned in the second range on the other end side in the sliding direction with respect to the first range. The length ΔL of the second range is obtained when the inner length between the source pressure port 54 and the drain port 50a is L1, and the distance between the first land portion 61 and the second land portion 62 is L2. Calculated as L1-L2. That is, the spool 60 can slide by the length ΔL in the second range while maintaining the second state. The length ΔL of the second range is the centrifugal hydraulic pressure generated in the torque converter 2 when the feedback pressure from the release oil chamber 26 acts on the spool 60 when the control valve 50 is in the second state. Feedback pressure by more than the on pressure P _oN the engaging oil chamber 25 is set to a length that holds the second state even if it exceeds the modulator pressure P _LPM2 by.

Here, by setting the length ΔL of the second range to be long, the state in which the hydraulic oil is confined in the release oil chamber at the time of slip engagement of the lockup clutch can be maintained for a long stroke amount. Even if the centrifugal oil pressure generated in the combined oil chamber increases, it can be prevented from switching to the engaged state suddenly, but in that case, when the signal pressure is supplied to the control valve and the off pressure is discharged from the release oil chamber There is a possibility that the responsiveness (differential pressure responsiveness) becomes slow. In contrast, in the present embodiment, ECU 4 is, at zero differential pressure condition of the on pressure _{P ON} and OFF pressure _{P OFF} in the lock-up clutch 24, the lock-up clutch 24 by the increased ON pressure _{P ON} by centrifugal hydraulic pressure In order to prevent the release oil chamber 26 from being engaged, there is no need to increase the stroke amount of the spool 60 while the release oil chamber 26 is closed, so the length ΔL of the second range is zero. Also good.

  Further, when a higher lock-up control pressure PSLU is supplied to the control valve 50, as shown in FIG. 2C, the spool 60 is in the lock-up on state, and the main pressure port 54 and the off-pressure port 55, the off pressure port 55 and the drain port 50a are communicated, the lubrication port 56 and the on pressure port 57 are blocked, and the on pressure port 57 and the third input port 58 are communicated with each other. It becomes the state of. The third state is formed when the spool 60 is located on the other end side in the sliding direction with respect to the second range and is located in the third range including the other end of the sliding range.

The ECU 4 includes, for example, a CPU, a ROM that stores a processing program, a RAM that temporarily stores data, an input / output port, and a communication port. Various control signals such as a control signal to the hydraulic control device 3 are provided. The signal is output from the output port. The engine speed Ne is input from the engine ECU to the ECU 4 and the rotation speed Nt of the input shaft of the speed change mechanism is input by a rotation sensor (not shown). The ECU 4 controls the engagement state of the lockup clutch 24 of the torque converter 2 in accordance with the traveling state such as the vehicle speed of the vehicle. In this case, the ECU 4 controls the linear solenoid valve SLU to regulate the lockup control pressure PSLU output from the linear solenoid valve SLU, and controls the engagement state of the lockup clutch 24 using the control valve 50. To do. In this embodiment, as the lock-up control pressure PSLU is large, the lockup clutch 24 becomes large on pressure P _ON side of the differential pressure is engaged strongly.

When the ECU 4 stands by with the on-pressure P _ON and the off-pressure P _OFF in the lock-up clutch 24 being equal to each other in order to perform slip control of the lock-up clutch 24 at the time of starting, the rotational speed of the output shaft of the internal combustion engine And the rotational speed of the input shaft of the speed change mechanism are increased, the off pressure P _OFF side of the differential pressure ΔP between the on pressure P _ON and the off pressure P _OFF output from the hydraulic control device 3 is increased. Thus, the lockup control pressure PSLU is controlled so that the on pressure P _ON and the off pressure P _OFF in the lockup clutch 24 are maintained in an equivalent state. Further, the ECU 4 cancels the centrifugal hydraulic pressure generated according to the differential rotation speed in the lockup clutch 24 by increasing the off pressure P _OFF side in the differential pressure ΔP, and turns on and off the on pressure P _ON in the lockup clutch 24. The lockup control pressure from the linear solenoid valve SLU is set so as to set the differential pressure ΔP between the on pressure P _ON and the off pressure P _OFF output from the hydraulic control device 3 so as to maintain the pressure P _OFF in an equivalent state. The PSLU command value has a preset map M1, and the lockup control pressure PSLU is controlled by referring to the map M1.

  Here, as the map M1, as shown in FIG. 3, for example, a current command value C (mA) to the lockup control pressure PSLU is set for the differential rotational speeds N1, N2, N3,. It is supposed to be. Linear interpolation or the like is appropriately executed between the numerical values of the map M1.

Incidentally, the differential pressure ΔP off pressure _{P OFF} and ON pressure _{P ON (P OFF -P ON)} , the differential rotation speed N1, N2, N3, ... and, in relation, differential rotation speed N1, N2, N3, ... As the pressure increases, the differential pressure ΔP decreases linearly. If the same differential rotational speed is used, the differential pressure ΔP increases as the engine rotational speed Ne increases. Furthermore, the differential pressure ΔP off pressure _{P OFF} and ON pressure _{P ON (P ON -P OFF)} , the relationship in the negative difference pressure region between a current command value, as the current command value increases, the pressure difference ΔP is larger Become.

Therefore, in the map M1 shown in FIG. 3, when the relationship between the differential rotation speeds is N1 <N2 <N3, the relationship between the addition values of the current command value C is, for example, a1>a2> a3. As a result, the ECU 4 decreases the current command value to the linear solenoid valve SLU as the differential rotational speeds N1, N2, N3,... Increase, so that the OFF pressure P _OFF and ON are reduced by decreasing the lockup control pressure PSLU. it is possible to increase the side off pressure _{P oFF} in the differential pressure ΔP between the pressure _{P ON.} Moreover, you may make it have such a map M1 different for every engine speed Ne.

  The ECU 4 switches the control valve 50 to the first state when the lockup clutch 24 is released, and switches the control valve 50 to the third state when the lockup clutch 24 is fully engaged. When the up clutch 24 is in the half-engaged state, the control valve 50 is set in the second state.

Next, the operation of the hydraulic control device 3 of the automatic transmission 1 will be described along the time chart shown in FIG. In FIG. 4, the time change graph of the _ON pressure P _ON and the OFF pressure P _OFF indicates the hydraulic pressure output from the hydraulic control device 3 and may be different from the actual hydraulic pressure in the lockup clutch 24.

When the internal combustion engine is started at time t0, the output shaft of the internal combustion engine rotates. However, when the rotational speed Ne of the internal combustion engine is low, the pump impeller 21 of the torque converter 2 idles and the rotational speed Nt of the input shaft of the transmission mechanism is 0. Remains. The control valve 50 is in the first state because the lockup control pressure PSLU is not supplied. When the internal combustion engine is started, hydraulic pressure is supplied from the oil pump, the primary regulator valve generates line pressure PL, the secondary regulator valve generates secondary pressure Psec, and the line pressure modulator valve generates modulator pressure P _LPM2. The The secondary pressure Psec is supplied to the control valve 50 in the first state and the engagement oil chamber 25 of the torque converter 2, and the off pressure P _OFF increases. The modulator pressure P _LPM2 is supplied to the linear solenoid valve SLU.

Thereafter, at time t1, the input shaft of the speed change mechanism is rotated at the rotational speed Nt by the torque converter 2, and the vehicle travels to generate a vehicle speed. Thereby, the release state (t1 to t5) of the lockup clutch 24 is started. At time t2, the ECU 4 issues a current command value for executing fast fill to the linear solenoid valve SLU. Thus, the control valve 50 switches to the second state by the lock-up control pressure PSLU is supplied, also on pressure _{P ON} and OFF pressure _{P OFF} is increased.

Thereafter, the standby state (t3 to t4) is started at time t3. The standby state is a state in which the on-pressure P _ON and the off-pressure P _OFF in the lock-up clutch 24 are set to the same state (zero differential pressure state) to perform slip control of the lock-up clutch 24 at the start, As shown in FIG. 4, the on-pressure P _ON and the off-pressure P _OFF output from the hydraulic control device 3 in order to realize this are as follows. The off-pressure P _OFF exceeds the on-pressure _PON by a predetermined differential pressure ΔP. Maintained (negative differential pressure). Here, the ECU 4 refers to the map M1 shown in FIG. 3 based on the differential rotational speed between the rotational speed Ne of the output shaft of the internal combustion engine and the rotational speed Nt of the input shaft of the speed change mechanism. On the other hand, the current command value is transmitted, and the lockup control pressure PSLU is controlled so as to maintain the on pressure P _ON and the off pressure P _OFF output from the hydraulic control device 3 at a predetermined differential pressure ΔP.

Further, during the period from the start of the standby state until the lockup clutch 24 is completely engaged (t3 to t5), the on-pressure of the engagement oil chamber 25 depends on the differential rotational speed between the rotational speed Ne and the rotational speed Nt. there is a large centrifugal hydraulic pressure is generated in the P _oN, but the map M1 of the current command value such centrifugal be hydraulic pressure is generated so as not pushed freeing oil chamber 26 on pressure P _oN and oFF pressure P _The lockup control pressure PSLU is set to be supplied so as to maintain _OFF at a predetermined differential pressure ΔP. For this reason, since the ECU 4 can be controlled according to the map M1, the lock-up clutch 24 can be prevented from being pushed from the engagement oil chamber 25 side to the release oil chamber 26 side. _Engagement of the lockup clutch 24 by PON is suppressed.

At time t4, the ECU 4 ends the standby state and starts flex control (t4 to t6). At this time, the ECU 4 issues a current command value to the linear solenoid valve SLU and controls the lockup control pressure PSLU to gradually increase. As a result, the control valve 50 is switched to the third state, and the on pressure P _ON slightly increases and the off pressure P _OFF significantly decreases. For this reason, the lockup clutch 24 is in a semi-engaged state, and further approaches a fully engaged state.

When the on pressure P _ON exceeds the off pressure P _OFF at time t5, the lockup clutch 24 is completely engaged, and the rotational speed Ne of the output shaft of the internal combustion engine and the input shaft of the transmission mechanism are rotated at the rotational speed Nt. Matches and enters the lockup state. Thereafter, at time t6, the ON pressure P _ON becomes maximum, the OFF pressure P _OFF further decreases, and the flex control ends. At time t7, the ECU 4 issues a current command value to the linear solenoid valve SLU, and controls the lockup control pressure PSLU to be maximized so that the off pressure P _OFF is zero.

As described above, according to the automatic transmission 1 of the present embodiment, ECU 4 may slip control of the lockup clutch 24 at the time of starting, that is, the ON pressure P _ON in the lock-up clutch 24 to a so-called flex-start control When the standby state with the _OFF pressure P _OFF being equal (zero differential pressure state), the larger the differential rotational speed between the rotational speed Ne of the output shaft of the internal combustion engine and the rotational speed Nt of the input shaft of the transmission mechanism, the on pressure _{P oN} and oFF pressure _{P oFF} in the lock-up clutch 24 by increasing the side of the oFF pressure _{P oFF} in the differential pressure ΔP between the off pressure _{P oFF} and oN pressure _{P oN} outputted from the hydraulic control device 3 The lockup control pressure PSLU from the linear solenoid valve SLU is controlled so as to maintain the same state. That is, in the zero differential pressure condition of the on pressure P _ON and OFF pressure P _OFF in the lock-up clutch 24, a large centrifugal hydraulic pressure on pressure P _ON the engaging oil chamber 25 due to a large rotational speed difference between the input and output When this occurs, the ECU 4 controls the lockup control pressure PSLU so as to increase the off pressure P _OFF output from the hydraulic control device 3. By increasing the off pressure P _OFF output from the hydraulic control device 3, the on pressure P _ON and the off pressure P _{OFF in} the lock up clutch 24 become equal, and the lock up clutch 24 is engaged with the engagement oil chamber 25 side. can be suppressed to be pushed to the release oil chamber 26 side from it is prevented that the lock-up clutch 24 by the increased oN pressure P _oN by centrifugal hydraulic pressure will engage.

  Further, since it is not necessary to increase the stroke amount of the spool 60 of the control valve 50 while the release oil chamber 26 is closed, the differential pressure response is not reduced, and the control valve 50 is increased in size. Can be suppressed. Thus, according to the hydraulic control device 3 of the automatic transmission 1, even when the input / output differential rotation speed increases when the lock-up clutch 24 is slip-engaged, the differential pressure response is not reduced. Engagement shock caused by centrifugal oil pressure can be suppressed.

  Further, according to the hydraulic control device 3 of the automatic transmission 1 according to the present embodiment, the ECU 4 controls the lockup control pressure PSLU by referring to the map M1, so that, for example, a map created based on experimental data or the like Therefore, it is not necessary to obtain a complicated calculation formula, and the calculation method can be easily obtained.

  Further, according to the hydraulic control device 3 of the automatic transmission 1 of the present embodiment, two elements of the linear solenoid valve SLU and the control valve 50 are used as a hydraulic control circuit for engaging and disengaging the lockup clutch 24. . For this reason, for example, since a switching valve such as a lockup relay valve is not used, the number of parts can be minimized and the hydraulic circuit can be simplified and the hydraulic control device 3 can be downsized.

  In the above-described embodiment, the ECU 4 calculates the current command value from the differential rotation speed by using the map M1, but the present invention is not limited to this. For example, a calculation formula for calculating the current command value from the differential rotation speed may be obtained, and the calculation formula may be used.

  In the above-described embodiment, the case where two elements of the linear solenoid valve SLU and the control valve 50 are used as the hydraulic control circuit for engaging and disengaging the lockup clutch 24 has been described. Not limited. For example, a three-element hydraulic control circuit in which a switching valve such as a lock-up relay valve is added to the above-described two elements may be used. Alternatively, the lockup clutch 24 may be directly engaged / disengaged by a linear solenoid valve.

The present embodiment includes at least the following configuration. The automatic transmission (1) of the present embodiment is interposed between a transmission mechanism, an output shaft of an internal combustion engine and an input shaft of the transmission mechanism, and has an on pressure (P _ON ) and an off pressure (P _OFF ). A fluid transmission device (20) having a lockup clutch (24) capable of locking up the output shaft and the input shaft by engagement, the output state being controlled by the differential pressure (ΔP); A solenoid valve (SLU) that controls the differential pressure (ΔP) by adjusting the pressure (PSLU), and the on-pressure (P _ON ) and the off-pressure (P _OFF ) in which the differential pressure (ΔP) is controlled. ) And the on-pressure (P _ON ) and the off-pressure (P _OFF ) in the lock-up clutch (24) to control the slip-up of the lock-up clutch (24) when starting. ) In the equivalent state, the greater the difference rotational speed between the rotational speed (Ne) of the output shaft of the internal combustion engine and the rotational speed (Nt) of the input shaft of the transmission mechanism, the greater the hydraulic control. By increasing the off pressure (P _OFF ) side of the differential pressure (ΔP) between the on pressure (P _ON ) and the off pressure (P _OFF ) output from the device (3), the lockup clutch A control unit (4) for controlling the output pressure (PSLU) so as to maintain the on pressure (P _ON ) and the off pressure (P _OFF ) in (24) in an equivalent state. According to this configuration, the control unit (4) performs on-pressure (P _ON ) and off-pressure on the lock-up clutch (24) in order to perform slip control, that is, so-called flex start control on the lock-up clutch (24) at the start. (P _OFF ) in the equivalent state (zero differential pressure state), and when waiting, the differential rotational speed between the rotational speed (Ne) of the output shaft of the internal combustion engine and the rotational speed (Nt) of the input shaft of the transmission mechanism The larger the is, the larger the lock-up is achieved by increasing the off pressure (P _OFF ) side in the differential pressure (ΔP) between the off pressure (P _OFF ) and the on pressure (P _ON ) output from the hydraulic control device (3). The output pressure (PSLU) from the solenoid valve (SLU) is controlled so that the _ON pressure (P _ON ) and the OFF pressure (P _OFF ) in the clutch (24) are maintained in an equivalent state. That is, in the zero differential pressure state between the on pressure (P _ON ) and the off pressure (P _OFF ) in the lock-up clutch (24), the engagement oil chamber (25) is turned on due to a large rotational speed difference between input and output. When a large centrifugal oil pressure is generated in the pressure (P _ON ), the control unit (4) controls the output pressure (PSLU) to increase the off pressure (P _OFF ) side output from the hydraulic control device (3). To do. By increasing the off pressure (P _OFF ) output from the hydraulic control device (3), the on pressure (P _ON ) and the off pressure (P _OFF ) in the lock-up clutch (24) become equal and locked. Since it is possible to suppress the up clutch (24) from being pushed from the engagement oil chamber (25) side to the release oil chamber (26) side, the lock-up clutch (24) is turned on by the on pressure (P _ON ) increased by the centrifugal hydraulic pressure. ) Is suppressed from engaging. Further, since it is not necessary to increase the stroke amount of the spool while the release oil chamber (26) is closed, the differential pressure response is not lowered. Thus, according to the hydraulic control device (3) of the automatic transmission (1), even when the input / output differential rotational speed increases when the lockup clutch (24) is slip-engaged, the differential pressure response The engagement shock caused by the centrifugal hydraulic pressure can be suppressed without reducing the performance.

In the hydraulic control device (3) of the automatic transmission (1) of the present embodiment, the control unit (4) generates centrifugal hydraulic pressure generated according to the differential rotational speed in the lockup clutch (24). The ON pressure (P _ON ) and the OFF pressure (P _OFF ) in the lock-up clutch (24) are equalized by canceling out by increasing the _OFF pressure (P _OFF ) side in the differential pressure (ΔP). The solenoid valve (ΔP) is set so as to set the differential pressure (ΔP) between the on pressure (P _ON ) and the off pressure (P _OFF ) output from the hydraulic control device (3) so as to maintain a stable state. A command value of the output pressure (PSLU) from the SLU has a preset map (M1), and the output pressure (PSLU) is controlled by referring to the map (M1). According to this configuration, for example, a map created based on experimental data or the like can be used, and it is not necessary to obtain a complicated calculation formula, and an arithmetic technique can be easily obtained.

Further, in the hydraulic control device (3) of the automatic transmission (1) of the present embodiment, the fluid transmission device (2) is disposed with the lock-up clutch (24) interposed therebetween in the axial direction, and on pressure _{(P oN)} as an original pressure (Psec) is supplied the lock-up clutch (24) engaging oil chamber for engaging with (25), the off-pressure _{(P oFF)} is supplied said lockup A release oil chamber (26) for releasing the clutch (24), and the hydraulic control device (3) includes a main pressure port (54) communicated with the main pressure (Psec) and the release An off pressure port (55) communicated with the oil chamber (26) and a drain port (50a) communicated with the drain oil passage, and the off pressure port (55) and the original pressure port (54) And the off-pressure port ( 55) and the first state in which the drain port (50a) is shut off, and the original pressure (Psec) input to the original pressure port (54) is adjusted based on the output pressure (PSLU) to The second state of output as the off pressure P _OFF from the off pressure port (55), the off pressure port (55) and the original pressure port (54) are shut off, and the off pressure port (55) and the A control valve (50) that can be switched by the output pressure (PSLU) from the solenoid valve (SLU) between the third state communicating with the drain port (50a), and the control unit (4), When the lockup clutch (24) is in the released state, the control valve (50) is switched to the first state, and when the lockup clutch (24) is in the fully engaged state, the control valve (50) is switched. When the lube (50) is switched to the third state and the lock-up clutch (24) is in a semi-engaged state, the control valve (50) is set to the second state. According to this configuration, two elements of the solenoid valve (SLU) and the control valve (50) are used as a hydraulic control circuit for engaging and disengaging the lockup clutch (24). For this reason, for example, since a switching valve such as a lock-up relay valve is not used, the number of parts can be minimized and the hydraulic circuit can be simplified and the hydraulic control device (3) can be downsized.

1 Automatic transmission 2 Torque converter (fluid transmission)
3 Hydraulic control device 4 ECU (control part)
24 Lock-up clutch 25 Engaging oil chamber 26 Release oil chamber 50 Control valve 50a Drain port 54 Original pressure port 55 Off pressure port 60 Spool P _OFF off pressure P _ON on pressure Psec Secondary pressure (original pressure)
PSLU lock-up control pressure (output pressure)
SLU linear solenoid valve (solenoid valve)
Ne Rotational speed of the engine output shaft Nt Rotational speed of the input shaft of the transmission mechanism M1 Map ΔP Differential pressure

Claims (3)

A transmission mechanism;
It is interposed between the output shaft of the internal combustion engine and the input shaft of the speed change mechanism, and the engagement state and the release state are controlled by the differential pressure between the on pressure and the off pressure, and the output shaft and the input shaft are connected by the engagement. A fluid transmission device having a lockup clutch capable of being locked up;
A hydraulic control device that has a solenoid valve that controls the differential pressure by regulating an output pressure, and that outputs the on-pressure and the off-pressure in which the differential pressure is controlled;
When the vehicle is on standby with the on-pressure and the off-pressure in the lock-up clutch being equal to each other in order to perform slip control of the lock-up clutch at the time of starting, the rotational speed of the output shaft and the speed change of the internal combustion engine As the differential rotational speed of the mechanism with respect to the rotational speed of the input shaft increases, the off-pressure side of the differential pressure between the on-pressure and the off-pressure output from the hydraulic control device is increased to increase the lock. An automatic transmission comprising: a control unit that controls the output pressure so as to maintain the on pressure and the off pressure in an up clutch in an equivalent state.   The control unit cancels the centrifugal hydraulic pressure generated according to the differential rotation speed in the lockup clutch by increasing the off pressure side in the differential pressure, so that the on pressure and the off pressure in the lockup clutch are increased. The command value of the output pressure from the solenoid valve is set in advance so as to set the differential pressure between the on pressure and the off pressure output from the hydraulic control device so that the pressure is maintained in an equivalent state. The automatic transmission according to claim 1, wherein the output pressure is controlled by referring to the map. The fluid transmission device is disposed across the lock-up clutch in the axial direction, and an engagement oil chamber for supplying the original pressure as the on-pressure to engage the lock-up clutch, and the off-pressure A release oil chamber for releasing the lock-up clutch that is supplied,
The hydraulic control device includes an original pressure port that communicates with the original pressure, an off pressure port that communicates with the release oil chamber, and a drain port that communicates with a drain oil passage, and the off pressure port and the A first state in which the source pressure port is communicated and the off pressure port and the drain port are shut off, and the source pressure input to the source pressure port is regulated based on the output pressure to adjust the off pressure. A second state in which the off-pressure is output from the port; and a third state in which the off-pressure port and the source pressure port are blocked and the off-pressure port and the drain port are communicated with each other. A control valve that can be switched by the output pressure from
The control unit switches the control valve to the first state when the lockup clutch is in a released state, and moves the control valve to the third state when the lockup clutch is in a fully engaged state. The automatic transmission according to claim 1 or 2, wherein the control valve is set to the second state when the lockup clutch is set to a half-engaged state.

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