JP7099402B2 - Car control device - Google Patents

Description

The techniques disclosed herein relate to automotive controls comprising a torque converter with a lockup clutch.

Vehicles equipped with automatic transmissions and torque converters with lockup clutches are widespread. The torque converter connects the pump impeller connected to the output shaft of the engine and the turbine liner connected to the input shaft of the automatic transmission via a large number of fixed blades called stators and a viscous fluid. Through the stator and viscous fluid, the torque amplification effect can be obtained, and the torque change at the time of starting becomes smooth, and the drivability is improved. On the other hand, there is a loss in power transmission through the viscous fluid.

On the other hand, the lockup clutch mechanically connects the pump impeller and the turbine liner. By engaging the lockup clutch, the output shaft of the engine and the input shaft of the automatic transmission are mechanically connected, and the loss in power transmission is reduced.

In the present specification, for convenience of explanation, engaging the lockup clutch is simply referred to as locking up (or locking up), and releasing the lockup clutch is non-locking up (or unlocking). It is called. By appropriately switching between the locked-up state and the non-locked-up state according to the accelerator opening and the vehicle speed, both drivability and loss reduction can be achieved.

Slip control (or flex lockup control) that keeps the rotation speed difference (actual rotation speed difference) between the pump impeller and the turbine liner at a predetermined target rotation speed difference by putting the lockup clutch in a semi-engaged state is also widely used. (For example, Patent Documents 1 and 2). By adopting slip control, the balance between drivability and loss reduction is further improved. The control device stores a two-dimensional map of the accelerator opening and the vehicle speed, and the lock-up area, the slip area, and the non-lock-up area are defined in the two-dimensional map. The control device refers to the two-dimensional map and switches between lockup, non-lockup, and slip control based on the state of the vehicle.

The control device disclosed in Patent Documents 1 and 2 separates slip control during starting of a vehicle and slip control during normal traveling. The former is called start slip control or flex start control, and the latter is called steady slip control.

The actuator of the lockup clutch is hydraulic, and in slip control at the start, feed forward control is adopted so that the valve is quickly filled with hydraulic oil at the beginning and then the lockup clutch starts to be half-engaged smoothly. Will be done. On the other hand, in steady-state slip control, feedback control is adopted so that the difference in actual rotation speed follows the difference in target rotation speed. In the steady state slip control, feedforward control and feedback control may be used together.

Further, in the control device of Patent Document 1, when the engine blow-up is large in the start slip control, the learning control is incorporated so that the feed forward command value is made larger than the previous time in the next start slip control. In the control device of Patent Document 2, learning control is incorporated even in the steady state slip control.

Further, in the control device of Patent Document 1, the lockup clutch hydraulic pressure command value and the actual rotation speed difference in the start slip control are set so that the vehicle behavior is not disturbed when shifting from the start slip control to the steady state slip control. Based on this, the method of setting the lockup clutch hydraulic pressure command value at the time of transition is changed.

Japanese Unexamined Patent Publication No. 2011-241963 Japanese Unexamined Patent Publication No. 2012-047301

In order to realize a smoother start, it is conceivable to use feedforward control and feedback control together in the slip control at the time of starting. Patent Document 1 does not mention the process at the time of control transition when the feedforward control and the feedback control are used together in both the start slip control and the steady state slip control. The present specification provides a technique for suppressing disturbance of vehicle behavior at the time of control transition when feedforward control and feedback control are used in combination in both start slip control and steady state slip control.

The control device disclosed in the present specification includes a start-time slip control that controls a hydraulic actuator that adjusts the engagement of the lockup clutch when the vehicle starts, and a steady-time slip control that controls the hydraulic actuator after the start-time slip control. Is feasible. In the start slip control, the control device adds the first feedback value based on the difference between the actual rotation speed difference between the pump impeller and the turbine liner of the torque converter and the first target rotation speed difference to the first feed forward value. Give the value to the hydraulic actuator. In the constant slip control, the control device gives the hydraulic actuator a hydraulic command value obtained by adding the second feedback value based on the difference between the actual rotation speed difference and the second target rotation speed difference (steady difference) to the second feed forward value. give. Further, in the steady state slip control, the second feed forward value at the time of the next control is learned and updated based on the steady difference. When shifting from the start slip control to the steady slip control, the control device executes one of the following processes (1) and (2). (1) When the last first feedback value exceeds a predetermined threshold value, the last first feedback value is used as the initial value of the second feedback value, and the second feedback value is reset until the second feedback value is reset. Stop learning and updating the feedback value. (2) If the last first feedback value is below the threshold value, zero is used as the initial value of the second feedback value.

At the time of control transition, if the initial value of the second feedback value is set to zero even though the final first feedback value is large, the last hydraulic pressure command value in the start slip control and the first in the steady state slip control The difference in hydraulic pressure command value may become large. If the hydraulic pressure command value changes significantly in steps during control transition, the vehicle behavior may be disturbed. Therefore, in such a case, by taking over the last first feedback value to the initial value of the second feedback value, it is possible to suppress a sudden change in hydraulic pressure at the time of control transition. On the other hand, when the final first feedback value is small, it is expected that a large hydraulic pressure change does not occur in the feedforward value at the initial stage of steady-state slip control. Therefore, when the final first feedback value is small (when the first feedback value is below the threshold value), zero is used as the initial value of the second feedback value.

Further, when the first feedback value is inherited to the initial value of the second feedback value, the steady-state slip control is started from the value where the second feedback value is large, and the learning of the second feedforward value is affected. It ends up. Therefore, when the first feedback value is inherited to the initial value of the second feedback value, the learning of the second feedforward value is stopped and the above-mentioned influence is removed. Details and further improvements to the techniques disclosed herein will be described in the "Modes for Carrying Out the Invention" section below.

FIG. 3 is a block diagram of an automobile including a control device of an embodiment. It is a control block diagram of a control device and a control target (torque converter). It is a flowchart at the time of control transition executed by a control device. This is an example of a time chart of various parameters.

The control device 30 of the embodiment will be described with reference to the drawings. FIG. 1 shows a block diagram of an automobile 2 including a control device 30. The dashed arrow line in FIG. 1 indicates the signal flow. The automobile 2 includes an engine 40, a torque converter 10, an automatic transmission 50, and a control device 30.

The output shaft 41 of the engine 40 is connected to the input shaft 51 of the automatic transmission 50 via the torque converter 10. The output shaft 52 of the automatic transmission 50 is connected to the drive wheels 7 via the differential gear 6.

The torque converter 10 will be described. The output shaft 41 of the engine 40 is connected to the shaft 11 of the pump impeller 12 of the torque converter 10, and the input shaft 51 of the automatic transmission 50 is connected to the shaft 13 of the turbine liner 14 of the torque converter 10. As is well known, the pump impeller 12 and the turbine liner 14 are housed in a casing filled with a viscous fluid (oil). Further, the pump impeller 12 and the turbine liner 14 face each other with the stator 15 interposed therebetween. When the pump impeller 12 rotates, power is transmitted to the turbine liner 14 via the viscous fluid, and the turbine liner 14 rotates. The torque is amplified by the mechanism by which the viscous fluid passes between the numerous blades of the stator 15 and hits the turbine liner 14. The larger the difference in rotation speed between the pump impeller 12 and the turbine liner 14, the larger the torque amplification factor. The torque is amplified through the stator 15, but there is a loss in the transmitted energy.

The stator 15 is supported by the casing via a one-way clutch 16. When the pump impeller 12 rotates in the normal direction (direction in which the vehicle is advanced), the one-way clutch 16 is engaged and the stator 15 is fixed. When the pump impeller 12 reverses (the direction in which the vehicle moves backward), the one-way clutch 16 is disengaged, and the stator 15 rotates together with the pump impeller 12.

The torque converter 10 includes a lockup clutch 17, and the lockup clutch 17 is engaged / disengaged by a command from the control device 30. When the lockup clutch 17 is engaged, the pump impeller 12 (that is, the output shaft 41 of the engine 40) and the turbine liner 14 (that is, the input shaft 51 of the automatic transmission 50) are mechanically directly connected to each other, and the torque amplification function is performed. Is lost, but the energy loss is small. The torque converter 10 includes a rotation speed sensor 18 that measures the rotation speed (rotational speed) of the pump impeller 12 and a rotation speed sensor 19 that measures the rotation speed (rotational speed) of the turbine liner 14. The measurement data of the rotation speed sensors 18 and 19 is sent to the control device 30. For convenience of explanation, the rotation speed of the pump impeller 12 is hereinafter referred to as an impeller rotation speed. Further, the rotation speed of the turbine liner 14 is hereinafter referred to as a turbine rotation speed. As is well known, the larger the difference between the impeller rotation speed and the turbine rotation speed (rotation speed difference), the higher the torque amplification factor can be obtained.

The control device 30 can also hold the lockup clutch 17 in a semi-engaged state. The control device 30 adjusts the engaging force of the lockup clutch 17 so that the difference between the impeller rotation speed and the turbine rotation speed (rotational speed difference) matches a predetermined target rotation speed difference. Specifically, the lockup clutch 17 is pressed against the engagement plate of the pump impeller 12 and the engagement plate of the turbine liner 14 by the hydraulic actuator 20. The control device 30 can adjust the engagement condition of the lockup clutch 17 by controlling the hydraulic actuator 20.

When the lockup clutch 17 is completely engaged with the engaging plate of the pump impeller 12 and the engaging plate of the turbine liner 14, the pump impeller 12 and the turbine liner 14 are mechanically connected. By adjusting the hydraulic pressure, the lockup clutch 17 is in a semi-engaged state, and the engagement plate of the pump impeller 12 and the engagement plate of the turbine liner 14 slide between the friction plate of the lockup clutch 17. If the oil pressure is increased, the rotation speed difference becomes smaller, and if the oil pressure is weakened, the rotation speed difference becomes larger. The control that keeps the rotation speed difference at the target rotation speed difference is called slip control (or flex lockup control).

By executing slip control, smooth torque transmission is realized while suppressing loss. That is, both loss suppression and drivability improvement can be achieved.

The control device 30 receives measurement data from sensors such as the vehicle speed sensor 8, the accelerator opening sensor 33, and the brake depression amount sensor 34, outputs the engine 40 (fuel injection amount), and locks up the torque converter 10 (hydraulic actuator 17). 20) Controls the shift stage (gear ratio) of the automatic transmission 50. As described above, in the case of slip control, the lockup clutch 17 (hydraulic actuator 20) is controlled by using the measurement data of the rotation speed sensors 18 and 19 for measuring the impeller rotation speed and the turbine rotation speed.

The control device 30 includes a central processing unit (CPU) 31, a memory 32, and various interfaces. When the central processing unit 31 executes the program stored in the memory 32, the control processing of the engine 40, the torque converter 10 (hydraulic actuator 20 of the lockup clutch 17), and the automatic transmission 50 is realized.

Slip control will be described. The control device 30 switches between a plurality of types of slip control according to conditions. At the time of starting, a slip control called a start slip control is executed, and the start slip control is followed by a slip control called a steady state slip control. The steady-state slip control region and the start-time slip region are defined on the two-dimensional map of the accelerator opening and the vehicle speed, and when the vehicle state belongs to any of the slip control regions, the control device 30 controls the slip. To execute. In the steady state slip region, the control rule differs between the acceleration state (impeller rotation speed> pump rotation speed) and the deceleration state (impeller rotation speed <turbine rotation speed), but here the acceleration state is fixed. Only constant slip control is the subject of the description.

The start slip control is started as soon as the vehicle starts to move. In the start slip control, the control device 30 controls the hydraulic actuator 20 so that the engine speed at the time of starting is suppressed and the turbine speed (that is, the axle) gradually increases. More specifically, in the first period of slip control at the start, the hydraulic pressure command is set by a predetermined feed forward value, and the difference between the impeller rotation speed (engine rotation speed) and the turbine rotation speed is determined from the middle. The hydraulic pressure command is determined by adding the feedback value to the feed forward value so as to follow the first rotation speed difference. In the constant slip control, the control device 30 controls the hydraulic actuator 20 so that the rotation speed difference follows a predetermined second rotation speed difference. In both the starting slip control and the steady slip control, the hydraulic pressure command value for the hydraulic actuator 20 is given as the sum of the feedforward value and the feedback value.

FIG. 2 shows a control block diagram. In the following, for convenience of explanation, "feedforward" may be abbreviated as "FF" and "feedback" may be abbreviated as "FB".

The control device 30 includes a first feedforward value output unit 301a (first FF value output unit 301a), a second feedforward value output unit 301b (second feedback value output unit 301b), a first target output unit 302a, and a second. Target output unit 302b, first switcher 303, second switcher 304, differencer 305, gain multiplier 306, adder 307, PID calculation unit 308, learning unit 309, switching determination unit 310, feedback adjustment unit 311 (FB) It is equipped with an adjusting unit 311). As described above, these modules are realized by the central processing unit 31 executing the program stored in the memory 32.

When executing the slip control at the time of starting, the switching determination unit 310 controls the first switching unit 303 so as to connect the first FF value output unit 301a to the adder 307, and the first target output unit 302a is differentiated. The second switch 304 is controlled so as to be connected to the device 305.

In the starting slip control, the first FF value output unit 301a and the first target output unit 302a are used for control. The first FF value output unit 301a outputs the first FF value (first feed forward value) in the slip control at the time of starting. The symbol FFt1 shown in FIG. 2 means the first feed forward value (first FF value). The first target output unit 302a outputs the difference in the first target rotation speed in the slip control at the time of starting. The symbol dRt1 shown in FIG. 2 means the first target rotation speed difference. The first target output unit 302a is connected to the difference device 305 through the second switch 304, and the difference device 305 has an impeller rotation speed Rp and a turbine rotation speed measured by the rotation speed sensors 18 and 19 of the torque converter 10. The difference in Rt (difference in actual rotation speed dR) is also input. The difference device 305 calculates the difference between the first target rotation speed difference dRt1 and the actual rotation speed difference dR. The difference between the first target rotation speed difference dRt1 and the actual rotation speed difference dR may be referred to as a first feedback value (first FB value).

The first FB value is input to the gain multiplier 306, and a predetermined gain is multiplied by the first FB value. The output of the gain multiplier 306 is added to the first FF value by the adder 307. The total value of the first FF value and the first FB value is output as a command value (hydraulic pressure command value) to the hydraulic actuator 20. However, the total value of the first FF value and the first FB value is output to the hydraulic actuator 20 via the PID calculation unit 308. The PID calculation unit 308 adjusts the total value of the first FF value and the first FB value so that the change with time of the hydraulic pressure command value is smoothed and the integration error with time is reduced.

As described above, in the start slip control, the control device 30 sets the hydraulic command value by adding the first FB value based on the difference between the actual rotation speed difference dR and the first target rotation speed difference dRt1 to the first FF value. Give to.

The switching determination unit 310 controls the first switcher 303 so as to connect the second FF value output unit 301b to the adder 307 when shifting from the start slip control to the steady state slip control, and also controls the second target output unit. The second switch 304 is controlled so that the 302b is connected to the difference device 305.

In the constant slip control, the second FF value output unit 301b and the second target output unit 302b are used for control. The second FF value output unit 301b outputs the second feed forward value (second FF value) in the steady state slip control. The symbol FFt2 shown in FIG. 2 means the second FF value. The second target output unit 302b outputs the difference in the second target rotation speed in the steady-state slip control. The symbol dRt2 shown in FIG. 2 means the second target rotation speed difference.

The second target output unit 302b is connected to the difference device 305 via the second switch 304, and the difference between the impeller rotation speed Rp and the turbine rotation speed Rt (actual rotation speed difference dR) is also input to the difference device 305. Will be done. The difference device 305 calculates the difference between the second target rotation speed difference dRt2 and the actual rotation speed difference dR. The difference between the second target rotation speed difference dRt2 and the actual rotation speed difference dR is referred to as a second feedback value (second FB value).

The second FB value is input to the gain multiplier 306, and a predetermined gain is multiplied by the second FB value. The output of the gain multiplier 306 is added to the second FF value by the adder 307. The total value of the second FF value and the second FB value is output as a command value (hydraulic pressure command value) to the hydraulic actuator 20. Similar to the start slip control, the total value (hydraulic pressure command value) of the second FF value and the second FB value is output to the hydraulic actuator 20 via the PID calculation unit 308. The PID calculation unit 308 adjusts the total value of the second FF value and the second FB value so that the change with time of the hydraulic pressure command value is smoothed and the integration error with time is reduced.

As described above, in the steady-state slip control, the control device 30 sets the hydraulic command value by adding the second FB value based on the difference between the actual rotation speed difference dR and the second target rotation speed difference dRt2 to the second FF value. Give to.

In the constant slip control, the difference (second FB value) between the actual rotation speed difference dR and the second target rotation speed difference dRt2 is also input to the learning unit 309. The learning unit 309 sends a value obtained by multiplying the second FB value by a predetermined multiplier to the second FF value output unit 301b as a learning correction value of the second FF value in the next steady slip control. The second FF value output unit 301b outputs a value obtained by adding the learning correction value to the original second FF value as a new second FF value in the next steady-state slip control. That is, the second FF value is learned.

When the second FB value, that is, the difference between the actual rotation speed difference dR and the second target rotation speed difference dRt2 is large, the learning control raises the next second FF value by the learning correction value. As a result, in the next control, the rotation speed difference becomes smaller by the feed forward amount included in the hydraulic pressure command value, and the actual rotation speed difference dR quickly follows the second target rotation speed difference dRt2. The learning correction value is updated every cycle of the control routine.

Although the description is omitted in this embodiment, the learning of the first FF value is carried out based on the first FB value also in the slip control at the time of starting.

When shifting from the start slip control to the steady slip control, the control device 30 selects the initial value of the second FB value in the steady slip control according to the magnitude of the final first FB value of the start slip control. .. The FB adjustment unit 311 in FIG. 2 selects the initial value of the second FB value. Specifically, the FB adjusting unit 311 of the control device 30 performs the following processing at the time of control transition. (1) When the first FB value (last first FB value) immediately before the control transition exceeds a predetermined threshold value, the control device 30 uses the last first FB value as the initial value of the second FB value. In that case, the control device 30 stops the learning update of the second FF value until the second FB value is reset next. (2) When the first FB value is below the threshold value, zero is used as the initial value of the second FB value. In this case, learning of the second FF value is performed at the same time as the start of steady-state slip control. In the process of comparing the last first FB value and the threshold value in the above (1) and (2), the absolute value of the last first FB value is compared with the threshold value.

The effect of selecting the initial value of the second FB value will be described. The sum of the first FF value and the first FB value corresponds to the hydraulic pressure command value to the hydraulic actuator 20 in the start slip control. The sum of the second FF value and the second FB value corresponds to the hydraulic pressure command value to the hydraulic actuator 20 in the steady state slip control. The first FF value and the second FF value are different, and the first target rotation speed difference dR1 and the second target rotation speed difference dR2 are also different.

At the time of control transition, if the initial value of the second FB value is set to zero even though the final first FB value (absolute value) is large, the final hydraulic pressure command value in the start slip control and the steady state slip control The difference between the initial oil pressure command values may be large. If the hydraulic pressure command value changes significantly in a step-like manner, the PID calculation unit 308 cannot suppress the sudden change, the engaging force of the lockup clutch 17 (hydraulic actuator 20) changes suddenly, and the vehicle behavior is disturbed at the time of control transition. There is a risk. Therefore, in such a case, by taking over the last first FB value to the initial value of the second FB value, it is possible to suppress a sudden change in hydraulic pressure at the time of control transition. On the other hand, when the final first FB value is small, it is expected that a large hydraulic pressure change does not occur at the second FF value at the initial stage of steady-state slip control. Therefore, when the last first FB value is small (when the absolute value of the last first FB value is below the threshold value), zero is used as the initial value of the second FB value.

Further, when the last first FB value is inherited to the initial value of the second FB value, the second FB value starts from a large value, and the learning of the second FF value is affected. Therefore, when the first FB value is inherited to the initial value of the second FB value, the learning update of the second FF value is stopped, and the above-mentioned influence is removed.

FIG. 3 shows a flowchart for setting the initial value of the second FB value when shifting from the start slip control to the steady slip control. The process of FIG. 3 is executed when the state of the vehicle shifts from the start slip control region to the steady slip control region on the two-dimensional map of the accelerator opening degree and the vehicle speed.

First, the control device 30 stops the slip control at the time of starting (step S2). Subsequently, the absolute value of the final first FB value is compared with the threshold value (step S3). When the absolute value of the last first FB value exceeds the threshold value (step S3: YES), the control device 30 sets the last first FB value to the initial value of the second FB value (step S4), and the learning stop flag. Is set to "ON" (step S5). The learning stop flag is a variable used in the program of the control device 30, and is referred to in the steady-time slip control program. In the constant slip control, the learning of the second FF value by the learning unit 309 (see FIG. 2) is stopped while the learning stop flag is set to “ON”. While the learning stop flag is set to "OFF", the learning unit 309 (see FIG. 2) learns and updates the second FF value.

On the other hand, when the absolute value of the last first FB value is below the threshold value (step S3: NO), the control device 30 sets the initial value of the second FB value to zero (step S6), and sets the learning stop flag to ". "OFF" is set (step S7). After the execution of steps S4 and S5, or after the execution of steps S6 and S7, steady-state slip control is started (step S8).

When the absolute value of the last first FB value is equal to the threshold value, which of steps S4 and S6 may be selected may be appropriately selected. In the case of the flowchart of FIG. 3, if the absolute value of the last first FB value is equal to the threshold value, the process proceeds to step S6. In other words, in the flowchart of FIG. 3, when the absolute value of the last first FB value is equal to or less than the threshold value, the process proceeds to step S6.

When step S7 is executed, the learning unit 309 operates in the steady state slip control, and the learning correction value of the second FF value is updated every control cycle.

After the learning stop flag is set to "ON" in step S5, when the second FB value is reset to zero again, the learning stop flag is reset to "OFF". The case where the second FB value is reset is typically not the transition from the starting slip control but the transition from another control to the steady slip control. Specifically, it is a case of shifting from the lock-up state to the steady-state slip control, or a case of shifting from the non-lock-up state to the steady-state slip control. Further, the second FB value is also reset when shifting from the steady state slip control on the deceleration side to the steady state slip control on the acceleration side.

FIG. 4 shows an example of a time chart of the impeller rotation speed, the turbine rotation speed, and the hydraulic pressure command value. The graph (1) shows the rotation speed, and the graph (2) shows the hydraulic pressure command value. The horizontal axis is time.

The slip control at the time of starting is started at time T1. From time T1 to time T2, the hydraulic pressure command value is only the first FF value. After time T2, the first FB value is added to the first FF value. The alternate long and short dash line in graph (2) indicates the first FF value (FFt1), and the width from the alternate long and short dash line corresponds to the first FB value (FBt1). By adding the second FB value, the difference in rotation speed between the impeller rotation speed and the turbine rotation speed becomes smaller (see graph (1)).

At time T3, the vehicle state enters the steady state slip control region. The first FF value (FFt1) and the second FF value (FFt2) are different. That is, the feed forward value (first FF value) in the start slip control and the feed forward value (second FF value) in the steady slip control are different. In FIG. 4 (2), the alternate long and short dash line indicates the second FF value (FFt2). In the example of FIG. 4, the final first FB value (FBt1) of the starting slip control is larger than the threshold value. Therefore, the initial value of the second FB value (FBt2) is equal to the last first FB value (FBt1).

The graph of FIG. 4 (2) shows the hydraulic pressure command value (symbol Cmd of FIG. 3) before being input to the PID calculation unit 308 (see FIG. 2). In the hydraulic pressure command value that has passed through the PID calculation unit 308, the change on the step before and after the time T3 is converted into a gradual change.

Although specific examples of the present invention have been described in detail above, these are merely examples and do not limit the scope of claims. The techniques described in the claims include various modifications and modifications of the specific examples exemplified above. The technical elements described herein or in the drawings exhibit their technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the techniques exemplified in the present specification or the drawings can achieve a plurality of purposes at the same time, and achieving one of the purposes itself has technical usefulness.

2: Automobile 10: Torque converter 12: Pump impeller 14: Turbine liner 17: Lock-up clutch 18, 19: Rotation sensor 20: Hydraulic actuator 30: Control device 40: Engine 50: Automatic transmission 301a: First feed forward ( FF) Value output unit 301b: 2nd FF value output unit 302a: 1st target output unit 302b: 2nd target output unit 303, 304: Switcher 305: Difference device 306: Gain multiplier 307: Adder 308: PID calculation unit 309: Learning unit 310: Switching judgment unit 311: FB adjustment unit

Claims (1)

It is a control device for automobiles equipped with a torque converter with a lockup clutch.
The control device is
It is possible to execute start-time slip control that controls a hydraulic actuator that adjusts the engagement of the lockup clutch when the vehicle starts, and steady-time slip control that controls the hydraulic actuator after the start-time slip control.
In the start slip control, the control device adds a first feedback value based on the difference between the actual rotation speed difference between the pump impeller and the turbine liner of the torque converter and the first target rotation speed difference to the first feed forward value. The hydraulic pressure command value is given to the hydraulic actuator.
In the steady state slip control, the control device sets a hydraulic pressure command value obtained by adding a second feedback value based on the difference between the actual rotation speed difference and the second target rotation speed difference (steady state difference) to the second feed forward value. While giving to the hydraulic actuator, the second feedforward value at the time of the next control is learned and updated based on the steady-state difference.
When shifting from the starting slip control to the steady-time slip control, the control device is subjected to the control device.
(1) When the last first feedback value exceeds a predetermined threshold value, the first feedback value is used as the initial value of the second feedback value, and until the second feedback value is reset next time. Stop the learning update and
(2) When the last first feedback value is below the threshold value, zero is used as the initial value of the second feedback value.
Control device.

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