JP3149559B2 - Lock-up clutch slip control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a slip control device for controlling a slip ratio of a lock-up clutch provided in an automatic transmission.

[0002]

2. Description of the Related Art As is well known, lock-up clutches are widely used in recent automatic transmissions. When a vehicle is traveling at a constant speed or the like, the lock-up clutch is held in an engaged state, so that an internal combustion engine can be used. The rotation is transmitted to the transmission mechanism side without passing through the torque converter, thereby preventing power loss due to slippage of the torque converter. Such a lock-up clutch is released when the vehicle is stopped to prevent the internal combustion engine from being stopped (so-called stall) by the driven wheel whose rotation has been prevented. This is performed when the accelerator operation is stopped to decelerate the vehicle. That is, since it takes a little time to release the lock-up clutch, if the lock-up clutch is released immediately before the stop of the vehicle, the internal combustion engine is stalled because the lock-up clutch cannot be released in time for rapid deceleration of the vehicle. There is a danger that this will occur, and in order to avoid this, the vehicle is opened in advance with a margin.

[0003] By the way, during deceleration of the vehicle, there is no danger of engine stall even if the internal combustion engine is driven in reverse by the torque from the driving wheel side and fuel injection is stopped. The engine speed is within a predetermined rotation range (for example, from 1600 rpm to 1000 rpm).
Is reduced, the fuel injection is temporarily interrupted, so-called fuel cut is performed. Therefore, in order to extend the fuel cut period (that is, the fuel injection interruption time) to achieve a sufficient improvement in fuel efficiency and a reduction in emission, the engine speed is gradually reduced when the vehicle is decelerated, and the above-described predetermined speed is reduced. It is necessary to stop for a long time in the rotation area.

However, when the lock-up clutch is released in conjunction with the stoppage of the accelerator operation as described above, the rotation of the internal combustion engine rapidly decreases without being reversely driven by the torque from the driving wheel side. The fuel cut period became extremely short, and little improvement in fuel efficiency or emission reduction was expected.

[0005] In order to prolong the fuel cut period by reducing the engine speed more slowly when the vehicle decelerates, see, for example, Japanese Patent Laid-Open Publication No. 1-2061.
No. 59 and Japanese Patent Application Laid-Open No. 225875/1990 propose a slip control device for a lock-up clutch.

These slip control devices switch the lock-up clutch from an engaged state to a slip control state of a predetermined slip ratio with a decrease in vehicle speed when the vehicle decelerates due to the stop of the accelerator operation, and lock-up occurs when the vehicle speed further decreases. Control is performed to release the clutch. Then, by the slip control performed at the time of deceleration, the internal combustion engine is reversely driven by the torque from the driving wheel side, and the rotation speed is gently reduced, so that the fuel cut period is extended.

In the slip control device described in Japanese Patent Application Laid-Open No. Hei 1-206159, two types of slip ratios are set in advance, and during slip control, a small slip ratio (close to the engagement side) in a high vehicle speed region. ) Is applied, and when the vehicle speed falls to a low region, the slip ratio is switched to a large value (close to the open side). Also, JP-A-2-22587
In the slip control device described in Japanese Patent Application Laid-Open No. 5 (1999) -1995, for example, different slip rates are applied in slip control when the vehicle is decelerated and at other times.

[0008]

Problems to be Solved by the Invention
As described above, the slip control device of the lock-up clutch realizes the extension of the fuel cut period by slip-controlling the lock-up clutch at the time of deceleration of the vehicle as described above. No precautions have been taken to prevent stalling. That is, the lock-up clutch during the slip control is released when the vehicle speed decreases to a preset release determination value, but when the vehicle rapidly decelerates, the vehicle speed decreases from the release determination value to 0 in a short time. However, there is a possibility that the internal combustion engine may be stopped in time for release of the lock-up clutch. In the slip control device disclosed in JP-A-1-206159, the lock-up clutch is controlled at a slip rate closer to the release side when the vehicle speed decreases to the release determination value.
As a result, engine stall during sudden deceleration cannot be avoided.

As a countermeasure, the release judgment value is increased,
Although it is conceivable to release the lock-up clutch early when the vehicle decelerates, another problem occurs in that a sufficient fuel cut period cannot be obtained.

Therefore, the present invention provides a sufficiently long fuel cut period at the time of deceleration of the vehicle to improve fuel economy and reduce emissions.
It is an object of the present invention to provide a lock-up clutch slip control device that can immediately control the lock-up clutch to the release side and reliably prevent the engine from stalling.

[0011]

As shown in FIG. 1, a lock control clutch slip control apparatus according to the present invention includes a throttle full-position detecting device for detecting a fully closed state of a throttle valve M2 of an internal combustion engine M1 mounted on a vehicle. Close detection means M3
The deceleration matching determination means M4 for determining the degree of deceleration based on the engine speed when the vehicle is braked, and the fully closed state of the throttle valve M2 is detected by the throttle fully closed detection means M3 during running of the vehicle. The target slip ratio of the lock-up clutch in the automatic transmission M5 mounted on the vehicle is set based on the deceleration degree determined by the deceleration degree determination means M4.
6. The slip ratio of the lock-up clutch is controlled based on the target slip ratio set by the target slip ratio setting device M6 and the deceleration matching determination device.
Based on the degree of deceleration determined by M4,
And a slip ratio control means M7 for ending the slip ratio control of the clutch.

[0012]

According to the present invention, when the accelerator operation of the running vehicle is stopped and the throttle fully closed state is detected by the throttle fully closed detecting means, the deceleration degree determined by the deceleration degree determining means is determined. based on the target slip rate is set by the target slip ratio setting unit, on the basis of the target slip ratio, the actual slip ratio of the lock-up clutch is controlled by the slip ratio control means co
Based on the deceleration rate determined by the deceleration rate determination means.
And the lockup clutch slip ratio control is terminated.
You .

For example, when the accelerator operation of the running vehicle is stopped and the throttle fully closing means detects the fully closed state of the throttle valve, the deceleration matching judging means determines that the vehicle is suddenly decelerated. Then, the target slip ratio of the lock-up clutch is set to be increased by the target slip ratio setting means, and based on the target slip rate, the slip rate is controlled by the slip rate control means in a direction to increase the actual slip rate.

Also, for example, the accelerator operation of a running vehicle
Operation is stopped, and the throttle
When the fully closed state of the lube is detected,
If it is determined that the vehicle is decelerating more rapidly, lock-up
Since there is no need to control the clutch slip rate,
The slip ratio control by the slip ratio control means ends.

Therefore, during normal deceleration without judging sudden deceleration, the lock-up clutch is maintained in the engaged state or at a predetermined slip ratio, so that the internal combustion engine is reversely driven by the torque from the drive wheel side to gradually reduce the rotational speed. Lowering it, and it is possible to obtain a sufficiently long fuel cut period,
In addition, when the sudden deceleration is determined, the lock-up clutch is immediately controlled to the disengagement side, so that the engine stall is reliably prevented.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A description will now be given of a slip control device for a lock-up clutch according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing an internal combustion engine and an automatic transmission to which a slip control device for a lock-up clutch according to one embodiment of the present invention is applied.

As shown in the figure, a throttle valve 3 is provided in an intake pipe 2 of an internal combustion engine 1, and the throttle valve 3 controls the amount of intake air supplied to the internal combustion engine 1 to adjust the engine output. You. A transmission mechanism 7 is connected to the crankshaft 4 of the internal combustion engine 1 via a torque converter 6 of the automatic transmission 5 (separated from the internal combustion engine 1 for convenience), and the transmission mechanism 7 is a vehicle not shown. Are connected to the drive wheels via the drive system. A lock-up clutch 8 is provided in the torque converter 6, and the lock-up clutch 8 is switched between an open state and an engaged state by a hydraulic circuit (not shown) controlled by a clutch control solenoid 9. In the meantime, an arbitrary slip ratio is adjusted. Then, as is well known, when the lock-up clutch 8 is released, the rotation of the internal combustion engine 1 is transmitted to the transmission mechanism 7 via the torque converter 6, and when the lock-up clutch 8 is engaged,
The torque is transmitted to the transmission mechanism 7 via the lock-up clutch 8 without passing through the torque converter 6. On the other hand, during the intermediate slip control, the rotation of the internal combustion engine 1 is controlled by the torque converter 6 or the lock-up clutch 8 at a rate corresponding to the slip ratio. Is transmitted to the speed change mechanism 7 via the

An electronic control unit 11 (hereinafter, simply referred to as "ECU") for controlling the lock-up clutch 8 constitutes a logical operation circuit centered on a CPU, a ROM, and a RAM (not shown). Solenoid 9
Are connected, an idle switch 12 for detecting the fully closed state of the throttle valve 3, a rotational speed sensor 13 for detecting the rotational speed Ne of the internal combustion engine 1, and a vehicle speed V provided on the output side of the speed change mechanism 7 for detecting the vehicle speed V. Vehicle speed sensor 14 is connected.

Then, as will be described later, when the vehicle is decelerating, the ECU 11 calculates the engine speed Ne based on the decrease rate ΔNe per unit time of the engine speed Ne detected by the speed sensor 13.
The actual slip ratio SLIP of the lock-up clutch 8 is controlled to gradually reduce the rotation speed Ne of the internal combustion engine 1 to extend the fuel cut period, and to immediately control the lock-up clutch 8 to the release side during rapid deceleration. Thus, engine stall of the internal combustion engine 1 is prevented. Note that the ECU 11 of the present embodiment not only controls the lock-up clutch 8 but also performs shift control of the automatic transmission 5 and operation control including fuel cut of the internal combustion engine 1.

Next, an outline of the slip control executed by the lock-up clutch slip control device configured as described above will be described.

FIG. 3 is a time chart for explaining slip control during deceleration of the vehicle by the lock-up clutch slip control device according to one embodiment of the present invention, and FIG. 4 is a slip diagram of the lock-up clutch according to one embodiment of the present invention. RO for determining target slip ratio from rotation reduction ratio of control device
FIG. 4 is an explanatory diagram showing a map stored in M.

As shown in FIG. 3, when the vehicle is running at a constant speed, the throttle valve 3 of the internal combustion engine 1 is maintained at a predetermined opening by operating the accelerator, and the engine speed Ne is maintained at a predetermined value. The up clutch 8 is controlled to the engaged state, that is, the slip ratio is 0%, and transmits the rotation of the internal combustion engine 1 to the transmission mechanism 7 without passing through the torque converter 6. Here, in order to decelerate the vehicle, first, when the accelerator operation is stopped prior to the brake operation, the throttle valve 3 is held in the fully closed state and the idle switch 12 is stopped.
Turn on.

At this time, the target slip ratio SLIPTG of the lock-up clutch 8 is set based on the rotation decrease rate ΔNe per unit time of the internal combustion engine 1 according to the map of FIG. That is, the target slip ratio SLIPTG is set to a small value in a region where the rotation decrease rate ΔNe is lower, and is set to increase rapidly in a region where the rotation decrease ratio ΔNe is higher, with the preset sudden deceleration determination value BΔNe as a boundary. Then, the duty ratio of the clutch control solenoid 9 is controlled based on the set target slip ratio SLIPTG, and the actual slip ratio SLIP is adjusted to the target slip ratio SLIPTG.

Here, the rapid deceleration determination value BΔNe is a rotation decrease rate that can occur when the vehicle is decelerating by engine braking or general gentle braking operation (hereinafter simply referred to as “normal deceleration”). It is defined as a boundary between a region of ΔNe and a region of a rotation decrease rate ΔNe that can occur when the vehicle is rapidly decelerating due to a sudden braking operation (hereinafter, simply referred to as “at the time of rapid deceleration”). Therefore,
During normal deceleration (ΔNe <BΔNe), as shown in FIG. 3, the actual slip ratio S along with the target slip ratio SLIPTG
The LIP is suppressed to a small value, and the internal combustion engine 1 is reversely driven by the torque from the driving wheel side, and the rotation speed Ne is gradually reduced. Then, the rotation decrease rate ΔNe becomes the sudden deceleration determination value BΔN
As long as the value does not exceed e, the target slip ratio SLIPTG continues to be suppressed to a small value. Therefore, the engine speed Ne stays for a long time in the rotation region where the fuel cut is performed, and a sufficiently long fuel cut period is obtained.

Further, a sharp braking operation is performed during the normal deceleration, and the vehicle is rapidly decelerated (ΔNe> BΔN).
When the process shifts to e), the target slip ratio SLIPTG rapidly increases and is set to a maximum value or a value close to the maximum value. That is, unlike the slip control device described in the related art, the lockup clutch 8 is not released at the time when the vehicle speed V decreases to the release determination value, but the earlier vehicle starts to rapidly decelerate (rotation decrease). When the rate ΔNe exceeds the sudden deceleration determination value BΔNe), the lockup clutch 8 is immediately controlled to the release side. Therefore, the engine stall due to the driven wheels whose rotation has been prevented is reliably prevented.

That is, as compared with the case where the lock-up clutch 8 is disengaged when the vehicle speed V decreases to the disengagement determination value as in the slip control device described in the related art.
Rather than do it earlier, the vehicle begins to decelerate sharply,
When the rotation decrease rate ΔNe exceeds the sudden deceleration determination value BΔNe,
Immediately, the lockup clutch 8 is controlled to be released.
Therefore, the engine stall due to the driven wheels whose rotation has been prevented is reliably prevented.

On the other hand, FIG. 3 shows a case where the vehicle traveling at a constant speed is shifted to a rapid deceleration state after passing through a normal deceleration state.
By controlling the lock-up clutch 8 to the release side,
Stall of the internal combustion engine 1 is prevented.

As is well known, the actual slip ratio SLIP does not match the target slip ratio SLIPTG due to the power transmission action of the torque converter, and the target slip ratio SLIPTG
The actual slip ratio SLIP when TG is set to the maximum value is
For example, it is about 60%. Therefore, the target slip ratio SLIPTG in FIG. 4 is set in a range of about 0 to 60%. However, since the driving wheels are locked during the brake operation in FIG. 3, the actual slip ratio SLIP has reached 100%.

Next, a description will be given of a slip control process executed by the ECU 11 of the vehicle running control device configured as described above.

FIG. 5 is a flowchart showing a slip control routine executed by the ECU of the lock-up clutch slip control device according to one embodiment of the present invention.

The routine shown in FIG. 5 is executed every 4 msec. The ECU 11 determines in step S1 that the idle switch 12
It is determined whether or not the vehicle is on. If the vehicle is on, it is determined that the throttle valve 3 is fully closed and the vehicle is decelerating, and the process proceeds to step S2. Next, step S2
The engine speed Ne detected by the speed sensor 13 is 2
It is determined whether the rotation speed is less than 000 rpm. If the rotation speed is less than 2000 rpm, it is determined that the rotation range of the lockup clutch 8 is to be slip-controlled, and the process proceeds to step S3. Further, in step S3, it is determined whether or not the vehicle speed V detected by the vehicle speed sensor 14 is less than 40 km / h.
If it is less than / h, it is determined that the speed is in the speed range where the slip control is to be performed, and the process proceeds to step S4. Step S
If a negative determination is made in any of the processes from 1 to S3, that is, when the vehicle is not decelerating, or when the engine speed Ne and the vehicle speed V are not in the region where the slip control is to be performed, it is determined that the slip control does not need to be performed. This routine is terminated.

When the processing at steps S1 to S3 is affirmatively determined and the routine proceeds to step S4, it is determined whether or not the lock-up clutch 8 is currently released. When the lock-up clutch 8 is released, it is considered that the lock-up clutch 8 under the slip control is released with the decrease of the vehicle speed V in step S9 described later, and it is necessary to execute the slip control again. This routine ends because there is no such information.

If the lock-up clutch 8 has not been released in step S4, that is, if the vehicle is in the engaged state or the slip control is in progress, it is determined in step S5 whether the vehicle speed V is less than 5 km / h. When the vehicle speed V is 5 km / h or more, as shown in FIG. 3, it is considered that the engine speed Ne is decreasing together with the vehicle speed V due to the stoppage of the accelerator operation, and the slip control after step S6 is performed. Execute the processing of

First, the ECU 11 calculates a rotation decrease rate ΔNe per unit time of the internal combustion engine 1 based on the engine speed Ne detected by the speed sensor 13 in step S6, and according to the map of FIG. Rotation decrease rate Δ
The target slip ratio SLIPTG is calculated from Ne. Furthermore,
In step S8, the duty ratio of the clutch control solenoid 9 is controlled based on the calculated target slip ratio SLIPTG to adjust the actual slip ratio SLIP to the target slip ratio SLIPTG, and then the process returns to step S1.

Therefore, after the accelerator operation shown in FIG. 3 is stopped, normal deceleration by the engine brake is performed. Therefore, the target slip ratio SLI is calculated according to the map shown in FIG.
PTG is suppressed to a small value, and the internal combustion engine 1 is reversely driven by the torque from the driving wheel side, and the rotation speed Ne is gradually reduced. Then, when the vehicle shifts to a sudden deceleration state due to a sudden braking operation, the target slip ratio SLIPTG is rapidly increased and set.
Is controlled to the open side to prevent engine stall.

In step S5, the vehicle speed V is 5 km / h.
If less than the target slip rate SLIP in step S9.
TG is set to the maximum value, and the duty ratio of the clutch control solenoid 9 is controlled in step S8 to set the actual slip ratio SLIP to the maximum value, that is, the open state. That is, without a sudden braking operation as shown in FIG.
When the vehicle maintains the normal deceleration state until the vehicle stops, the rotation reduction rate ΔNe is kept at a value lower than the sudden deceleration determination value BΔNe. As a result, the target slip ratio SLIPTG is also suppressed to a small value, and the lock-up clutch 8 is not finally released, which causes the internal combustion engine 1 to stall. Therefore, in the region where the vehicle speed V is less than 5 km / h (the region where the fuel cut has already been completed), the lock-up clutch 8 is released regardless of the rotation reduction rate ΔNe to prevent engine stall.

When the rotation decrease rate ΔNe slightly exceeds the sudden deceleration determination value BΔNe in step S7, the maximum value is not set as the target slip rate SLIPTG.
The lock-up clutch 8 is not completely released. However, since the target slip ratio SLIPTG at this time is close to the maximum value, the amount of operation required to release the lock-up clutch 8 from that state is very small. Therefore, when the vehicle speed V decreases to less than 5 km / h, the lock-up clutch 8 is promptly released in steps S9 and S8, and the engine stall is reliably prevented.

As described above, in this embodiment, the internal combustion engine M
1, the internal combustion engine 1 functions as the throttle valve M2, the throttle valve 3 functions as the throttle valve M2, and the idle switch 12 functions as the throttle full-close detecting means M3.
ECU 11 when executing the process of step S6
However, the ECU 11 when executing the processing of step S7 as the automatic transmission M5, the processing of step S7 as the target slip rate setting means M6, and the ECU 11 when executing the processing of step S8 as the slip rate control means M7, respectively. Function.

As described above, the slip control device for a lock-up clutch according to the present embodiment includes the internal combustion engine 1 mounted on a vehicle.
An idle switch 12 for detecting a fully closed state of the throttle valve 3 of the vehicle;
2, when the fully closed state of the throttle valve 3 is detected, the rate of decrease ΔNe of the engine speed Ne per unit time is calculated, and the calculated rate of decrease of speed ΔNe is used to determine a sudden deceleration of a map set in advance. In a region lower than the value BΔNe, the target slip ratio SLIPTG of the lock-up clutch 8 in the automatic transmission 5 mounted on the vehicle is suppressed to a small value, and in a region higher than the rapid deceleration determination value BΔNe, it is regarded as rapid deceleration. The ECU 11 controls the actual slip ratio SLIP of the lock-up clutch 8 based on the target slip ratio SLIPTG.

Therefore, at the time of normal deceleration of the vehicle, the target slip ratio SLIPTG is suppressed to a small value, and the internal combustion engine 1 is reversely driven by the torque from the driving wheel side to gradually lower the rotation speed Ne. As a result, a longer fuel cut period can be achieved, and fuel efficiency can be improved and emissions can be reduced. Further, when the vehicle suddenly decelerates due to a sudden braking operation, the target slip ratio SLIPTG is rapidly increased and set, so that the lock-up clutch 8 is immediately controlled to the release side to reliably prevent the engine 1 from stalling. can do.

In the above embodiment, the engine speed N
e, the rotation reduction rate ΔNe is calculated, and the rotation reduction rate ΔN
Although the target slip ratio SLIPTG corresponding to the deceleration state of the vehicle was calculated from the map based on e, the present invention is not limited to this, and the target slip ratio SLIPTG is not limited to this. May be calculated. Therefore, for example, when the vehicle decelerates, the vehicle speed sensor 1
4, the vehicle speed V is detected, and when the decrease rate of the vehicle speed V is low, it is considered that the vehicle is in a normal deceleration state, and the target slip ratio SLI is determined.
The PTG may be suppressed to a small value, and when the rate of decrease of the vehicle speed V is high, it may be considered that the vehicle is in a rapid deceleration state, and the target slip rate SLIPTG may be increased. The turbine speed TNe detected by the turbine speed sensor 21 shown in FIG.
Also increases or decreases in proportion to the vehicle speed V. Therefore, the target slip ratio SLIP is determined based on the turbine speed TNe instead of the vehicle speed V.
TG may be set. Further, when the vehicle decelerates, the pressure sensor detects the oil pressure of the brake system of the vehicle, and when the oil pressure is low (brake depression force is small), it is regarded as a normal deceleration state, and the target slip ratio SLIPTG is suppressed to a small value. However, when the hydraulic pressure is high (braking depression force is large), it may be regarded as a rapid deceleration state, and the target slip ratio SLIPTG may be increased.

Further, in the above-described embodiment, according to the characteristics of the map shown in FIG.
In a lower region, the target slip ratio SLIPTG is suppressed to a small value, and in a region higher than the sudden deceleration determination value BΔNe,
Although the target slip rate SLIPTG was sharply increased, the present invention is not limited to this,
The characteristics of the map can be changed as appropriate. Therefore, for example, the target slip ratio SLIPTG may be set to 0 in an area lower than the sudden deceleration determination value BΔNe, and the target slip rate SLIPTG may be set to the maximum value in an area higher than the sudden deceleration determination value BΔNe. Even in this case, when the vehicle suddenly decelerates, the lock-up clutch 8 can be immediately released to prevent the engine 1 from stalling. Further, the target slip rate SLIPTG may be set in direct proportion to the rotation decrease rate ΔNe. That is, the brake operation performed by the driver can be roughly classified into a gentle operation at the time of normal deceleration and a rapid operation at the time of rapid deceleration, and a brake operation corresponding to an intermediate therebetween is generally not performed. Therefore, even when the target slip rate SLIPTG is directly proportional to the rotation reduction rate ΔNe as described above, the rotation reduction rate ΔNe actually used is in either a low range or a high range. Target slip ratio SL based on the rotation decrease rate ΔNe
The IPTG is set, so that the engine stall can be prevented.

[0044]

As described above, according to the lock-up clutch slip control device of the present invention, the degree of deceleration is determined on the basis of the engine speed, and at the time of normal deceleration in which no rapid deceleration determination is made, the lock-up clutch is operated. The internal combustion engine is reversely driven by the torque from the driving wheel side, and the rotation speed is gently reduced because the engagement state and the predetermined slip ratio are maintained, so that a sufficiently long fuel cut period is obtained to improve fuel economy and emission. The reduction can be realized, and when a sudden deceleration determination is made, the lock-up clutch is immediately controlled to the release side, so that the engine stall can be reliably prevented.

[Brief description of the drawings]

FIG. 1 is a claim correspondence diagram conceptually showing the contents of one embodiment of the present invention.

FIG. 2 is a schematic configuration diagram showing an internal combustion engine and an automatic transmission to which a slip control device for a lock-up clutch according to an embodiment of the present invention is applied.

FIG. 3 is a time chart for explaining slip control during deceleration of the vehicle by the lock-up clutch slip control device according to one embodiment of the present invention.

FIG. 4 is an explanatory diagram showing a map stored in a ROM for determining a target slip ratio from a rotation reduction ratio of a lock-up clutch slip control device according to an embodiment of the present invention.

FIG. 5 is a flowchart showing a slip control routine executed by the ECU of the lock-up clutch slip control device according to the embodiment of the present invention.

[Explanation of symbols]

 M1 Internal combustion engine M2 Throttle valve M3 Throttle fully closed detection means M4 Deceleration matching determination means M5 Automatic transmission M6 Target slip rate setting means M7 Slip rate control means 1 Internal combustion engine 3 Throttle valve 5 Automatic transmission 8 Lockup clutch 11 ECU 12 Idle switch

Claims (1)

(57) [Claims] 1. Throttle fully closed detection means for detecting a fully closed state of a throttle valve of an internal combustion engine mounted on a vehicle, and deceleration degree determination means for determining a degree of deceleration based on an engine speed during a brake operation of the vehicle. When the throttle fully-closed state is detected by the throttle fully-closed state detecting means during running of the vehicle, the target slip ratio of a lock-up clutch in an automatic transmission mounted on the vehicle is determined by the deceleration matching determining means. controls and the target slip ratio setting means for setting, based on the deceleration degree is determined, the slip ratio of the lock-up clutch on the basis of the target slip rate set by the target slip ratio setting unit makes the deceleration degree determined Judgment by means
Of the lock-up clutch based on the
And a slip rate control means for terminating the slip rate control.