JP2006342907A - Lock-up control device for automatic transmission - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the fuel consumption of an internal combustion engine by effectively control the slipping condition of a lock-up clutch during reducing the speed of a vehicle even under such circumstances that a following vehicle exists. <P>SOLUTION: The slipping control of the lock-up clutch 6 is executed during reducing the speed of an automobile 1 for fuel cut. In this case, when the following vehicle exists, a slipping rotating speed in slipping control is higher than when it does not. As a result, engine brake less works in the automobile 1 and a driver less feels that the speed of the automobile 1 is reduced too much during slipping control because the following vehicle exists. During slipping control for keeping fuel cut long, there is no need for the driver to foot an accelerating pedal 8 so that he less feels that the speed of the automobile 1 is reduced, avoiding trouble in improving fuel consumption of the engine 2 with the stop of the resulting fuel cut. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a lockup control device for an automatic transmission.

  An automatic transmission mounted on a vehicle such as an automobile includes a fluid transmission device that transmits power through a fluid between the internal combustion engine side and the wheel side, and an input side (internal combustion engine side) of the device And a lock-up clutch that can directly connect the output side (wheel side).

  In such an automatic transmission, when the vehicle is decelerated, the lockup clutch is operated so that the fuel cut of the internal combustion engine can be continued for as long as possible. Here, the fuel cut of the internal combustion engine is executed on condition that the engine speed is equal to or higher than a predetermined value when the vehicle is decelerated when the accelerator pedal is released. When the accelerator pedal is depressed or the engine speed becomes less than the above value during the fuel cut, the fuel cut is stopped. Therefore, when the engine rotation speed gradually decreases during the fuel cut, the fuel cut can be continued for a long time by setting the lock-up clutch to the slip state so that the decrease in the engine rotation speed is suppressed. (See Patent Document 1). Further, by setting the lock-up clutch to the slip state as described above, it is possible to ensure engine braking by the internal combustion engine.

In the control of the slip state of the lock-up clutch in Patent Document 1 (hereinafter referred to as slip control), the slip rotation speed that is the difference between the input-side rotation speed and the output-side rotation speed of the fluid transmission device becomes the target value. Thus, it is realized by controlling the fastening force of the lock-up clutch. If the target value of the slip rotation speed is made small, a decrease in the engine rotation speed is more preferably suppressed, and the fuel economy improvement effect by the fuel cut is enhanced, and a feeling of deceleration by the engine brake is also more suitably obtained. Become.
JP 2004-340289 A

  By the way, under certain circumstances of the following vehicle, when the vehicle is decelerating when the fuel cut of the internal combustion engine is performed and the slip control of the lockup clutch is performed to suppress the decrease in the engine rotation speed, There is a case where the vehicle decelerates too much and the accelerator pedal is depressed to suppress the decelerating feeling. In this case, since the fuel cut of the internal combustion engine is stopped by the depression of the accelerator pedal, the slip control of the lockup clutch, which is performed in order to continue the fuel cut for a long time, becomes meaningless, and the fuel consumption of the internal combustion engine is reduced. Improvement is hindered.

  As described above, even when the slip control of the lock-up clutch is performed as described above when the vehicle is decelerated under a certain situation of the following vehicle, the slip control cannot be effectively used for improving the fuel consumption of the internal combustion engine. was there.

  The present invention has been made in view of such circumstances, and its object is to control the slip state of the lock-up clutch during deceleration of the vehicle even when there is a following vehicle, and to improve the fuel efficiency of the internal combustion engine. An object of the present invention is to provide a lockup control device for an automatic transmission that can be effectively used for improvement.

In the following, means for achieving the above object and its effects are described.
In order to achieve the above object, according to the first aspect of the present invention, when the vehicle is decelerated, the lockup clutch capable of directly connecting the input side and the output side of the fluid transmission device is brought into a slip state, and the input side of the fluid transmission device is Detection means for detecting the presence or absence of a succeeding vehicle in a lockup control device for an automatic transmission that controls the engagement force of the lockup clutch so that the slip rotation speed, which is the difference between the rotation speed and the output side rotation speed, becomes a target value. And setting means for setting the target value to a larger value when the detection means detects that there is a succeeding vehicle than when it is not.

  In a fluid transmission device for an automatic transmission mounted on a vehicle, the input side is connected to the internal combustion engine side of the vehicle, and the output side is connected to the wheel side of the vehicle. Further, in an internal combustion engine of a vehicle, fuel cut for improving fuel efficiency is executed on condition that the engine rotational speed is equal to or higher than a predetermined value when the vehicle is decelerated when the accelerator pedal is released.

  When the vehicle decelerates, the lock-up clutch is brought into a slip state so that the fuel cut is continued for a long time so that the decrease in the engine speed is suppressed. As control of the slip state of the lockup clutch at this time (slip control), specifically, the engagement force of the lockup clutch is controlled so that the slip rotation speed becomes a target value. When the slip control of the lockup clutch is performed as described above, the engine brake by the internal combustion engine works and the driver feels that the vehicle is decelerating. At this time, if there is a following vehicle, the driver may feel that the deceleration is too large, and the accelerator pedal may be depressed to suppress the deceleration. When the accelerator pedal is depressed in this way, the fuel cut of the internal combustion engine is stopped, and the improvement of the fuel consumption of the internal combustion engine by continuing the fuel cut for a long time is hindered. In other words, this means that the slip control of the lockup clutch, which is performed in order to continue the fuel cut for a long time, is not effectively utilized for improving the fuel consumption of the internal combustion engine.

  However, according to the above configuration, when there is a succeeding vehicle, the slip rotation speed is increased and the engine braking function by the internal combustion engine is reduced compared to the case where the following vehicle is not, so the driver has a greater feeling of deceleration. Feeling too much is suppressed. As a result, when executing the slip control of the lockup clutch for continuing the fuel cut for a long time, the accelerator pedal is not stepped on as described above, and the fuel cut of the internal combustion engine is prevented from being improved by the stop of the fuel cut. It is suppressed. Therefore, even when there is a succeeding vehicle, the slip control of the lockup clutch at the time of deceleration of the vehicle is effectively utilized for improving the fuel consumption of the internal combustion engine.

  According to a second aspect of the invention, in the first aspect of the invention, the detecting means detects a distance from the following vehicle, and the setting means sets the target value as the distance from the following vehicle is shorter. The value was set to a large value.

  When slip control of the lockup clutch is executed so as to suppress a decrease in engine rotation speed when the vehicle is decelerated, the magnitude of the feeling of deceleration felt by the driver varies depending on the distance from the following vehicle. Further, as the slip rotational speed is increased in order to suppress this feeling of deceleration, it becomes difficult to realize the suppression of the decrease in engine rotational speed by the slip control of the lockup clutch.

  According to the above configuration, the shorter the distance from the succeeding vehicle, the greater the slip rotation speed and the lower the vehicle deceleration. Therefore, the shorter the distance to the following vehicle and the more likely the driver feels that the driver feels too much deceleration, the smaller the vehicle deceleration can be reduced. It can be more adapted to the intention. Further, in a situation where the distance to the following vehicle is long and the driver does not feel that the feeling of deceleration is too great, the slip rotation speed is made small. For this reason, the slip rotation speed is increased more than necessary, and it becomes difficult to realize reduction suppression of the engine rotation speed by the slip control, and the fuel efficiency improvement of the internal combustion engine is not adversely affected. As described above, it is possible to suitably achieve both reduction in the feeling of deceleration and improvement in fuel consumption.

  According to a third aspect of the present invention, in the first or second aspect of the invention, the detecting means detects an approaching speed of the succeeding vehicle, and the setting means increases the target speed as the approaching speed of the succeeding vehicle increases. The value was set to a large value.

  When slip control of the lockup clutch is executed so as to suppress a decrease in engine rotational speed when the vehicle is decelerated, the magnitude of the feeling of deceleration felt by the driver varies depending on the approach speed of the following vehicle. Further, as the slip rotational speed is increased in order to suppress this feeling of deceleration, it becomes difficult to realize the suppression of the decrease in engine rotational speed by the slip control of the lockup clutch.

  According to the above configuration, as the approaching speed of the following vehicle increases, the slip rotation speed increases and the deceleration of the vehicle decreases. Therefore, as the approaching speed of the following vehicle is fast and the situation where the driver feels that the feeling of deceleration is too large, the vehicle deceleration can be reduced, and the deceleration is reduced according to the situation of the following vehicle. It can be more adapted to the intention. Further, in a situation where the approach speed is slow and the driver does not feel that the feeling of deceleration is too great, the slip rotation speed is made small. For this reason, the slip rotation speed is increased more than necessary, and it becomes difficult to realize reduction suppression of the engine rotation speed by the slip control, and the fuel efficiency improvement of the internal combustion engine is not adversely affected. As described above, it is possible to suitably achieve both reduction in the feeling of deceleration and improvement in fuel consumption.

Hereinafter, an embodiment in which the present invention is embodied in a lockup control device for an automatic transmission mounted on an automobile will be described with reference to FIGS.
As shown in FIG. 1, in an automobile 1, an automatic transmission 4 is provided on a power transmission path between an engine 2 and wheels 3, and the engine 2, wheels 3, and the like are connected via the automatic transmission 4 and the like. Rotational transmission between the two is performed. In addition, the automatic transmission 4 is provided with a torque converter 5 that transmits power through the oil between the engine 2 side and the wheel 3 side, and an input side (engine 2 side) of the torque converter 5. And a lockup clutch 6 that can be directly connected to the output side (wheel 3 side).

  The lock-up clutch 6 is hydraulically driven and includes a “direct connection state” in which the input side and the output side of the torque converter 5 are directly engaged, and a “release state” in which such a direct connection state is released. The operating state changes between. Further, the lockup clutch 6 allows a relative rotation between the “directly connected state” and the “released state”, that is, relative rotation between the input side and the output side of the torque converter 5 to some extent, and partially engages them. It is also possible to take a “slip state”. The slip state of the lock-up clutch 6, in other words, the rotational speed difference between the input side and the output side of the torque converter 5 is adjusted through control of the engaging force of the lock-up clutch 6 by the hydraulic drive.

  Various controls relating to the engine 2 and the automatic transmission 4 are performed by an electronic control unit 7 mounted on the automobile. Detection signals from various sensors shown below are input to the electronic control unit 7.

An accelerator position sensor 9 that detects the amount of depression of the accelerator pedal 8 (accelerator depression amount).
An engine rotation speed sensor 10 that detects an engine rotation speed that is the rotation speed on the input side of the torque converter 5.

A turbine rotation speed sensor 11 that detects a turbine rotation speed that is a rotation speed on the output side of the torque converter 5.
A subsequent vehicle distance sensor 12 that detects the distance between the automobile 1 and the following vehicle.

  The electronic control unit 7 performs fuel injection amount control by driving a fuel injection valve 13 provided in the engine 2 as operation control of the engine 2. The output adjustment of the engine 2 is performed by such fuel injection amount control. It should be noted that at the time of deceleration of the vehicle 1 in which the accelerator depression amount is set to “0 (accelerator release)”, and the engine rotation speed is equal to or higher than a predetermined determination value (for example, a value somewhat higher than the idle rotation speed). In this case, the fuel injection amount from the fuel injection valve 13 is set to “0”, and the fuel cut for improving the fuel consumption of the engine 2 is performed. Further, such fuel cut is stopped when the accelerator pedal 8 is depressed and an output request for the engine 2 is made, or when the engine rotation speed becomes less than the above-described determination value.

  Further, the electronic control unit 7 changes the gear position of the automatic transmission 4 to the driver's acceleration request (accelerator depression amount) and the traveling state (vehicle speed) of the vehicle 1 based on the accelerator depression amount and the vehicle speed of the vehicle 1. Switch to a suitable gear position. The vehicle speed is determined based on the turbine rotation speed and the current gear position of the automatic transmission 4. For example, the following modes can be cited as the shift modes of the automatic transmission 4. That is, when the driver's acceleration request is large (accelerator depression amount is large), the automatic transmission 4 is switched to the low-speed gear stage. Then, when the accelerator depression amount is set to “0” and the acceleration request is eliminated and the engine rotation speed decreases, the automatic transmission 4 is switched to the high speed side gear stage.

  Further, the electronic control unit 7 hydraulically drives the lockup clutch 6 based on the accelerator depression amount and the vehicle speed, and the operation state of the clutch 6 is between “directly connected state”, “released state”, and “slip state”. Switch with. Here, at the time of deceleration of the automobile 1 where the fuel cut of the engine 2 is performed, the lock-up clutch 6 slips in order to keep the engine rotation speed gradually decreasing as high as possible above the above-described determination value and continue the fuel cut for a long time. State. When the lockup clutch 6 is in the slip state in this way, rotation transmission from the wheel 3 side to the engine 2 side is performed, and a decrease in engine rotation speed is suppressed. As a result, when the automobile 1 is decelerated, the engine rotation speed is easily maintained at a value equal to or higher than the determination value, and the fuel cut can be continued for a long time.

Next, the fuel cut execution mode during deceleration of the automobile 1 will be described in detail with reference to the time chart of FIG.
As shown in FIGS. 2A, 2C, and 2D, when the accelerator depression amount becomes “0” and deceleration of the automobile 1 is started (timing T1), the engine rotation speed is equal to or higher than the determination value. If so, the fuel cut is started as shown in FIG.

  If the lock-up clutch 6 is in the released state during the fuel cut, the engine speed decreases rapidly as indicated by a two-dot chain line in FIG. 2C, for example. When the engine rotation speed becomes less than the determination value (timing T2), the fuel cut is stopped as indicated by a two-dot chain line in FIG. On the other hand, when the lockup clutch 6 is brought into the slip state during the fuel cut, the decrease in the engine rotation speed is suppressed as shown by the solid line in FIG. Then, the engine rotation speed becomes less than the determination value, and the fuel cut is stopped at the timing T3 in the drawing.

  Therefore, by setting the lock-up clutch 6 to the slip state when the vehicle 1 in which the fuel cut is performed is decelerated, the fuel cut execution time is increased from the time t1 to the time t2, and the fuel consumption of the engine 2 is increased accordingly. It becomes possible to improve. Further, if the lock-up clutch 6 is in the slip state, engine braking by the engine 2 is ensured. For this reason, when the lockup clutch 6 is in the disengaged state, if the vehicle speed of the automobile 1 decreases as shown by a two-dot chain line in FIG. 2D, for example, the lockup clutch 6 is in the slip state. As indicated by the solid line, the vehicle speed decreases more quickly than when the lockup clutch 6 is in the released state (two-dot chain line). Therefore, by setting the lock-up clutch 6 to the slip state, the vehicle 1 can be decelerated so that the driver feels a certain degree of deceleration.

  As described above, when the lock-up clutch 6 is brought into the slip state so as to suppress a decrease in the engine speed during deceleration of the automobile 1, the slip state control (hereinafter referred to as slip control) is as follows. To be done. That is, a slip rotation speed that is the difference between the engine rotation speed that is the rotation speed on the input side of the torque converter 5 and the turbine rotation speed on the output side of the torque converter 5 is calculated. Then, the fastening force of the lockup clutch 6 is controlled so that the slip rotation speed becomes a target value.

  Here, as the target value of the slip rotation speed is decreased, the decreasing tendency of the engine rotation speed becomes gentle as indicated by an arrow in FIG. This is because, as the target value is smaller, the rotation transmission efficiency from the wheel 3 side to the engine 2 side during deceleration of the automobile 1 is higher, and a decrease in engine rotation speed is suitably suppressed. Therefore, in order to continue the fuel cut for a long time, it is preferable to set the target value as small as possible. Further, as the target value is decreased, the vehicle speed decreases more rapidly as indicated by the arrow in FIG. This is because the smaller the target value is, the greater the rotational resistance of the engine 2 in rotating the wheel 3 and the greater the function of engine braking in the automobile 1.

  From the above, it is conceivable that the target value of the slip rotation speed is set to a value that suppresses a decrease in the engine rotation speed as much as possible, for example, 50 rpm while the driver feels a certain deceleration. However, even if the target value is set in this way, the slip control of the lock-up clutch 6 for continuing the fuel cut for a long time when the automobile 1 is decelerated is executed in the situation where the following vehicle exists behind the automobile 1. When the driver feels that the deceleration is too large, the accelerator pedal 8 may be depressed in order to suppress the feeling of deceleration (timing T4). In this case, the accelerator depression amount becomes large as shown in FIG. 2B, and accordingly, the fuel cut is stopped in a short time after the start (timing T1) as shown in FIG. 2F. Therefore, the slip control of the lock-up clutch 6 performed to keep the fuel cut for a long time becomes meaningless, and the fuel efficiency improvement of the engine 2 is hindered.

  Next, a slip rotation speed control procedure for avoiding such a problem will be described with reference to a flowchart of FIG. 3 showing a slip rotation speed control routine. The routine is executed by interruption at predetermined intervals through the electronic control unit 7 when the automobile 1 to be fuel cut is decelerated.

  In the slip rotation speed control routine, first, the presence or absence of the following vehicle is detected based on the detection signal from the following vehicle distance sensor 12 (S101). If it is detected in step S101 that there is no following vehicle and a negative determination is made, the target value of the slip rotation speed is set to a predetermined fixed value (S102). As the fixed value, as described above, a value (for example, 50 rpm) that suppresses a decrease in the engine rotation speed as much as possible while the driver feels a certain degree of deceleration is used. Then, after the target value is calculated as described above, the fastening force of the lockup clutch 6 is controlled so that the slip rotation speed becomes the target value (S104).

  Here, assuming that the target value of the slip rotation speed is set as described above in a situation where there is a following vehicle, the driver decelerates during the slip control of the lockup clutch 6 for continuing the fuel cut for a long time. As described above, the accelerator pedal 8 is depressed in order to suppress the feeling and the fuel cut may be stopped. In other words, this means that the slip control, which is performed in order to continue the fuel cut for a long time, is not effectively utilized for improving the fuel efficiency of the engine 2.

  For this reason, when it is detected in step S101 that there is a following vehicle and an affirmative determination is made, the target value of the slip rotation speed is set to a value larger than the fixed value (50 rpm) (S103). ). Then, in the subsequent step S104, the fastening force of the lockup clutch 6 is controlled so that the slip rotation speed becomes the target value as described above.

  Therefore, when there is a following vehicle, the slip rotational speed is higher and the engine brake function in the automobile 1 is smaller than when it is not, so that the driver is prevented from feeling that the feeling of deceleration is too large. Is done. As a result, at the time of executing the slip control of the lockup clutch 6 for continuing the fuel cut for a long time, the accelerator pedal 8 is not depressed as described above, and the fuel cut of the engine 2 is prevented from being improved by the stop of the fuel cut. That is suppressed. Therefore, the slip control of the lock-up clutch 6 at the time of deceleration of the automobile 1 in which fuel cut is performed in a situation where there is a following vehicle is effectively utilized for improving the fuel efficiency of the engine 2.

Next, the setting of the target value in step S103 will be described in more detail.
When the lock control of the lockup clutch 6 is executed so that the decrease in the engine speed is suppressed so as to keep the fuel cut longer when the automobile 1 decelerates, the magnitude of the deceleration feeling felt by the driver is the following vehicle. Depending on the distance between the vehicle and the approach speed of the following vehicle. That is, the driver tends to feel that the feeling of deceleration is too great as the distance to the following vehicle is short and the approaching speed of the following vehicle is high. Further, as the slip rotation speed at the time of the slip control is increased so as to suppress this feeling of deceleration, it becomes more difficult to suppress the decrease in the engine rotation speed by the slip rotation speed.

  In step S103, when setting the target value of the slip rotation speed, first, based on the detection signal from the following vehicle distance sensor 12, the distance to the following vehicle and the approaching speed of the following vehicle are detected. Then, the target value of the slip rotation speed is variably set to a value larger than the fixed value based on the distance to the following vehicle and the approach speed of the following vehicle. As shown in FIG. 4, the target value is set to a larger value as the distance to the succeeding vehicle becomes shorter, and is set to a larger value as the approaching speed of the succeeding vehicle becomes faster.

  By setting the slip rotation speed target in this manner, the shorter the distance from the succeeding vehicle and the faster the approaching distance of the succeeding vehicle, the greater the slip rotation speed and the smaller the deceleration of the automobile 1. Accordingly, the deceleration of the automobile 1 can be reduced as the driver feels that the feeling of deceleration is too large, such as the distance to the following vehicle is short or the approaching speed of the following vehicle is high. The deceleration can be adapted to the driver's intention according to the situation of the vehicle.

  Further, in a situation where the driver does not feel that the feeling of deceleration is too great, such as when the distance to the following vehicle is long or the approaching speed of the following vehicle is slow, the slip rotation speed is made small. For this reason, the slip rotation speed is increased more than necessary, and it becomes difficult to suppress the decrease in the engine rotation speed by the slip control of the lock-up clutch 6, and the fuel efficiency improvement of the engine 2 is not adversely affected.

According to the embodiment described in detail above, the following effects can be obtained.
(1) When the slip control of the lockup clutch 6 is executed during deceleration of the automobile 1 where fuel cut is performed, the slip rotation speed in the slip control is greater when there is a following vehicle than when it is not. Is done. As a result, the function of the engine brake in the automobile 1 becomes small, and it is suppressed that the driver feels that the deceleration feeling of the automobile 1 during the slip control is too large due to the presence of the following vehicle. Therefore, at the time of the slip control for keeping the fuel cut for a long time, the driver does not step on the accelerator pedal 8 to suppress the feeling of deceleration of the automobile 1, and the fuel cut of the engine 2 is hindered by the stop of the fuel cut. Can be suppressed. Therefore, the slip control when the automobile 1 is decelerated can be effectively used to improve the fuel consumption of the engine 2 even under certain conditions of the following vehicle.

  (2) As the distance from the following vehicle becomes shorter, the slip rotation speed in the slip control increases and the deceleration of the automobile 1 decreases. Accordingly, the deceleration of the automobile 1 can be made smaller as the distance to the succeeding vehicle becomes shorter and the driver is more likely to feel that the deceleration feeling of the automobile 1 during the slip control is too great. Accordingly, the deceleration can be adapted to the driver's intention. Further, in a situation where the distance to the following vehicle is long and the driver does not feel that the vehicle 1 feels too slow during the slip control, the slip rotation speed in the slip control is made small. For this reason, the slip rotation speed is increased more than necessary, and it is difficult to suppress the decrease in the engine rotation speed by the slip control, and the fuel efficiency improvement of the engine 2 is not adversely affected. As described above, it is possible to suitably achieve both reduction of the feeling of deceleration and improvement of fuel consumption.

  (3) As the approach speed of the succeeding vehicle increases, the slip rotation speed in the slip control increases, and the deceleration of the automobile 1 decreases. Therefore, the deceleration of the vehicle 1 can be made smaller as the approaching speed of the following vehicle is faster and the driver is more likely to feel that the vehicle 1 is feeling too slow during the slip control. Accordingly, the deceleration can be adapted to the driver's intention. Further, in a situation where the approaching speed of the following vehicle is slow and the driver does not feel that the feeling of deceleration of the automobile 1 during the slip control is too great, the slip rotation speed in the slip control is made small. For this reason, the slip rotation speed is increased more than necessary, and it is difficult to suppress the decrease in the engine rotation speed by the slip control, and the fuel efficiency improvement of the engine 2 is not adversely affected. As described above, it is possible to suitably achieve both reduction of the feeling of deceleration and improvement of fuel consumption.

In addition, the said embodiment can also be changed as follows, for example.
The target value of the slip rotation speed when there is a following vehicle may be variably set only according to the distance from the following vehicle, or may be variably set only according to the approach speed with the following vehicle.

Although the target value of the slip rotation speed when there is no following vehicle is a fixed value and 50 rpm is exemplified as a specific value of the fixed value, this value may be changed as appropriate.
The target value of the slip rotation speed when there is no following vehicle may be a variable value according to the driving state or the like instead of a fixed value.

BRIEF DESCRIPTION OF THE DRAWINGS Schematic which shows the whole motor vehicle to which the lockup control apparatus of the automatic transmission of this embodiment is applied. (A)-(f) is a time chart which shows the transition of the accelerator depression amount at the time of the deceleration of the motor vehicle in which fuel cut is performed, engine speed, and vehicle speed, and the execution mode of fuel cut. The flowchart which shows the control procedure of the slip rotational speed in the slip control of a lockup clutch. The graph which shows how the target value of slip rotational speed in the slip control of a lockup clutch changes according to the difference of the distance with a succeeding vehicle, and the difference of the approach speed of a succeeding vehicle.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Automobile, 2 ... Engine, 3 ... Wheel, 4 ... Automatic transmission, 5 ... Torque converter, 6 ... Lock-up clutch, 7 ... Electronic control unit, 8 ... Accelerator pedal, 9 ... Accelerator position sensor, 10 ... Engine rotation Speed sensor, 11... Turbine rotation speed sensor, 12... Subsequent vehicle distance sensor, 13.

Claims (3)

When the vehicle decelerates, the lockup clutch capable of directly connecting the input side and the output side of the fluid transmission device is brought into a slip state, and the slip rotation speed which is the difference between the input side rotational speed and the output side rotational speed of the fluid transmission device In the lockup control device for an automatic transmission that controls the fastening force of the lockup clutch so that the target value becomes,
Detection means for detecting the presence or absence of a following vehicle;
A setting means for setting the target value to a larger value than when it is not detected when the detection means detects that there is a succeeding vehicle;
A lockup control device for an automatic transmission, comprising: The automatic transmission lockup according to claim 1, wherein the detecting means detects a distance to the following vehicle, and the setting means sets the target value to a larger value as the distance to the following vehicle is shorter. Control device. 3. The automatic transmission according to claim 1, wherein the detecting unit detects an approaching speed of the succeeding vehicle, and the setting unit sets the target value to a larger value as the approaching speed of the succeeding vehicle increases. Lock-up control device.

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