JPH1096469A - Control device for automatic transmission with lock-up clutch - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To improve fuel efficiency while preventing engine stall by effectively utilizing ABS. SOLUTION: Control of an automatic transmission with a lock-up clutch of a vehicle having a fluid coupling incorporating a lock-up clutch which mechanically connects an input member and an output member and is released at a vehicle speed lower than a predetermined lower limit vehicle speed. A lock for setting the lower vehicle speed to a lower vehicle speed for releasing the lock-up clutch than when there is no anti-lock function for controlling the braking force of the wheels so as to prevent the wheels from locking during braking. Up control means (steps 2 and 3) is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an automatic transmission in which a lock-up clutch is incorporated in a fluid coupling such as a torque converter, and more particularly to an anti-lock control for preventing wheels from being locked during braking. The present invention relates to a device for controlling release of a lock-up clutch.

[0002]

2. Description of the Related Art In an automatic transmission for a vehicle, a torque converter, which is a fluid coupling, is used in order to provide a function of increasing torque when starting and accelerating and to eliminate the need for intermittent operation when stopping. The torque converter has many advantages, such as a torque increasing function and a vibration cutoff function, for transmitting torque through a fluid.However, on the other hand, the torque converter is connected between a pump impeller as an input member and a turbine runner as an output member. Since inevitable slippage occurs between them, power transmission efficiency is poor, which is a factor against improvement in fuel efficiency of the vehicle. Therefore, conventionally, it is widely practiced to provide a lock-up clutch that directly mechanically connects an input-side member and an output-side member of a torque converter.

When the lock-up clutch is engaged,
Deterioration of fuel efficiency due to power transmission loss can be suppressed, but there is a disadvantage that engine vibrations are directly transmitted to the automatic transmission. Further, in the coast state, the engine can be forcibly rotated by the torque input from the automatic transmission by engaging the lock-up clutch, thereby improving fuel efficiency by cutting off fuel (fuel cut). However, on the other hand, it may cause engine stall.

[0004] The above-mentioned inconvenience associated with the engagement of the lock-up clutch mainly occurs when the engine speed becomes low. Therefore, in the related art, the vehicle speed and the gear position at which the lock-up clutch is engaged are limited, and the lock-up clutch is engaged in a region where the vehicle speed is equal to or higher than a predetermined lower limit speed. However, since there is an unavoidable delay in the release control of the lock-up clutch, if the braking force when performing the braking operation is large, the release control is performed when the vehicle speed falls to the lower limit speed of engagement of the lock-up clutch. However, the engine speed is greatly reduced due to a delay in releasing the lock-up clutch, and in extreme cases, the engine may be stalled. Therefore, in the invention described in Japanese Patent Application Laid-Open No. 5-141526, when a brake signal is detected while the lock-up clutch is engaged, the lock-up clutch is immediately released.

[0005]

However, if the lock-up clutch is released simultaneously with the detection of the brake signal as in the invention described in the above-mentioned publication,
Since the engine speed immediately drops to the idling speed, it is necessary to continue the supply of fuel to maintain the engine speed, which makes it impossible to improve fuel efficiency.

Particularly, in a vehicle equipped with an anti-lock brake system (ABS) for controlling a braking force so as to prevent the wheels from locking during braking, the rotation of the wheels even when the brake pedal is depressed greatly. However, if the lock-up clutch is to be released at that time, transmission of torque from the automatic transmission to the engine is interrupted, and the number of revolutions of the engine is reduced. Therefore, it is necessary to continue supplying the fuel in order to maintain the rotation of the engine, and it is impossible to improve the fuel efficiency.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has an apparatus capable of preventing engine stall by organically relating a function of preventing wheel lock to a control of a lock-up clutch. The purpose is to provide.

[0008]

Means for Solving the Problems and Action Therefor To achieve the above object, the invention according to the first aspect is characterized in that the input member and the output member are mechanically connected and the vehicle speed is lower than a predetermined lower limit vehicle speed. In the control device for an automatic transmission with a lock-up clutch of a vehicle having a fluid coupling incorporating a lock-up clutch to be released, there is an anti-lock function that controls the braking force of the wheel so as to prevent the wheel from locking during braking. A lock-up control means for setting the lower limit vehicle speed at which the lock-up clutch is released to a lower vehicle speed than in a case where there is no lock-up clutch is provided.

Therefore, according to the first aspect of the present invention, the lock-up clutch is maintained in the engaged state at a lower vehicle speed in a vehicle having an anti-lock function of wheels than in a vehicle without the function. Therefore, during braking (coasting), the engine speed is maintained at a high speed by the torque transmitted from the automatic transmission, and the engine speed can be maintained even when the supply of fuel is cut off. At the same time, by performing such control at the same time, fuel efficiency can be improved. Without the anti-lock function, the lock-up clutch is released at a relatively high vehicle speed, so that the engine speed cannot be forcibly reduced to a low speed with the locking of the wheels. ,as a result,
It is possible to prevent engine stall due to wheel lock or a state close to this.
In the present invention, the case where there is no anti-lock function means
This includes the case where there is no means or device for controlling the braking force to prevent the wheels from locking during braking, and the case where such a device or device is not functioning due to a failure.

According to a second aspect of the present invention, there is provided a vehicle having a fluid coupling having a lock-up clutch which mechanically connects an input member and an output member and is released at a vehicle speed lower than a predetermined lower limit vehicle speed. If the control device of the automatic transmission with a lock-up clutch has no brake detecting means for detecting that a braking operation has been performed and an anti-lock function for controlling the braking force of the wheels so as to prevent the wheels from locking during braking, When the vehicle speed is lower than the lower limit vehicle speed or when the braking detecting means detects a braking operation, the lock-up clutch is released, and the braking force of the wheels is controlled so as to prevent the wheels from locking during braking. If the vehicle has an anti-lock function and the vehicle speed is lower than the lower limit vehicle speed regardless of the detection of the braking operation by the brake detecting means, And it is characterized in that it comprises a lock-up control means for releasing the click-up clutch.

Therefore, according to the second aspect of the present invention, when there is no antilock function for controlling to prevent the wheels from being locked during braking, the lockup clutch is released based on the detection of the braking operation. Therefore, even if the wheels are locked with the braking operation, the engine speed cannot be forcibly reduced to a low speed, so that engine stall can be prevented. On the other hand, if the vehicle has an anti-lock function, even if a braking operation is detected, the lock-up clutch will not be immediately disengaged and the lock-up clutch will not be released if the vehicle speed falls to the predetermined lower limit vehicle speed. The clutch is released. Therefore, when the anti-lock function is provided, the lock-up clutch is engaged up to a low vehicle speed, and the engine speed is maintained at a high speed by the torque transmitted from the automatic transmission, so that the fuel supply can be shut off during that time. Thus, fuel efficiency can be improved, and, naturally, engine stall can be avoided. In the present invention, when there is no anti-lock function, there are cases where there is no means or device for controlling to prevent locking of the wheel during braking, and cases where this kind of device or device does not function due to failure. including.

The invention according to claim 3 further comprises an antilock control device for controlling a braking force so as to prevent the wheels from being locked during braking, and further comprises a mechanical connection between the input member and the output member, and In a control device for an automatic transmission with a lock-up clutch of a vehicle having a fluid coupling incorporating a lock-up clutch that is released when a condition is satisfied, the anti-lock control device operates to start controlling the braking force. Anti-lock control detecting means for detecting an elapsed time from the time when the anti-lock control device detects that the elapsed time from the start of the braking force control by the anti-lock control device has reached a preset reference time. Lock-up control means for performing release control of the lock-up clutch upon detection. .

According to the third aspect of the present invention, when the anti-lock control device operates to control the braking force so that the wheels do not lock, and when the lock-up clutch is to be released, the braking force is changed. Accordingly, the rotation speed of the wheels and the rotation speed of the engine connected thereto via the lock-up clutch gradually decrease and increase as a whole, but the engine rotation speed decreases immediately after the start of the braking force control. In the case of, the lock-up clutch is engaged, and the lock-up clutch is released in the subsequent upward tendency. That is, the lock-up clutch is not released at the same time as the start of the control of the braking force by the anti-lock control device, but is released when the inertial force is acting in the direction of increasing the engine speed. It can be prevented beforehand. In addition, since the time required to engage the lock-up clutch to maintain the engine speed at or above the predetermined speed becomes longer, it is possible to increase the time for stopping the supply of fuel to be performed in conjunction therewith, thereby improving fuel efficiency. become.

According to a fourth aspect of the present invention, there is provided an anti-lock control device for controlling a braking force so as to prevent the wheels from being locked during braking, and further comprises an input member and an output member mechanically connected to each other and In a control device for an automatic transmission with a lock-up clutch of a vehicle having a fluid coupling including a lock-up clutch which is released when a condition is satisfied, a wheel speed during the operation of the anti-lock control device and the wheel speed Speed difference detecting means for detecting a change state of the difference between the wheel speed and the vehicle speed obtained from the vehicle speed, and lock-up control means for releasing the lock-up clutch in a state where the difference between the wheel speed and the vehicle speed is small. It is characterized by the following.

Therefore, according to the present invention, when the anti-lock control device is operated to control the braking force so that the wheels are not locked and the lock-up clutch is to be released, the braking force is reduced. According to the change, the rotation speed of the wheels and the rotation speed of the engine connected thereto via the lock-up clutch gradually decrease as a whole, but gradually decrease as a whole.However, the lock-up clutch is used when the wheel speed approaches the vehicle speed, that is, It will be released when the engine speed is on the rise. That is, when the lock-up clutch is released while the anti-lock control device is operating, the lock-up clutch is released when the inertial force acts in a direction to increase the engine speed, and the engine stall is released. Can be prevented beforehand. Further, it is possible to increase the time during which the lock-up clutch is engaged to maintain the engine speed at or above the predetermined speed, thereby improving fuel efficiency.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be specifically described with reference to the drawings. First, the overall control system of a vehicle to which the present invention is applied will be briefly described. In the example shown in FIG. 11, an electronically controlled automatic transmission 1 and an antilock brake system (ABS) 2 are mounted. It is a vehicle. The automatic transmission 1 is connected to the output side of the engine 3 and converts the torque input via the torque converter 4 into a plurality of gears by a gear transmission mechanism (not shown) mainly composed of a planetary gear mechanism. It is of a known structure that outputs after shifting. The torque converter 4 has a pump impeller 5 rotated by the engine 3 as an input member, and supplies a spiral flow of fluid generated by the pump impeller 5 to a turbine runner 6 as an output member to transmit torque. It has a known structure with a built-in lock-up clutch 7 for directly transmitting torque between the input member and the output member.

The automatic transmission 1 is configured to control engagement / disengagement of the lock-up clutch 7 and shift control by hydraulic pressure. The hydraulic control device 8 for that purpose includes a plurality of solenoid valves (not shown), and controls the engagement / disengagement of the lock-up clutch 7 and the speed change by changing the supply / discharge path of the hydraulic pressure by the switching operation of the solenoid valves. In addition, it is configured to control a transient hydraulic pressure at the time of gear shifting.

Further, the hydraulic control unit 8 is provided with a lock-up clutch 7 and an electronic control unit (T-ECU) 9 for outputting a signal for controlling a shift. The electronic control unit 9 mainly includes a central processing unit (CPU), storage devices (ROM, RAM), and an input / output interface.
And a throttle opening θ, a shift position, a brake signal, and the like. The electronic control unit 9 determines the gear position and the engagement / disengagement of the lock-up clutch 7 based on the input data and a shift map stored in advance, and based on the determination result, the hydraulic control unit 8. Is configured to output a control signal.

Here, an example of a map for controlling the engagement / disengagement of the lock-up clutch 7 and the shift speed is shown below.
As shown in FIG. This map defines the engagement region and the release region of the lock-up clutch 7 using the vehicle speed V and the throttle opening θ as parameters, and also defines each shift speed region. A thick solid line indicates the third forward speed or the third speed. A so-called engagement line for switching the lock-up clutch 7 from the released state (OFF) to the engaged state (ON) at the fourth speed is shown, and a thick broken line shows the engaged state of the lock-up clutch 7 at the third or fourth forward speed. (ON) to released state (O
FF). Further, a thin solid line indicates an upshift line, and a thin broken line indicates a downshift line.

Therefore, if the vehicle speed V increases so as to cross the engagement line or the throttle opening θ decreases, the lock-up clutch 7 is engaged, and conversely, the vehicle speed V decreases so as to cross the release line. Or the throttle opening θ increases, the lock-up clutch 7 is released. If the vehicle speed V increases so as to cross the upshift line, or if the throttle opening θ decreases, an upshift is executed, and conversely, the vehicle speed V decreases so as to cross the downshift line, or Opening θ
Increases, a downshift is performed.

Next, the anti-lock brake system 2 will be described. This is an apparatus for controlling the braking force so that the wheels do not lock during braking, and detects the rotational speed of each of the front and rear wheels, that is, the wheel speed. for,
Each of the wheels Fr, Fl, Rr, Rl has a rotation speed sensor 10, 11, 12, 13 attached thereto, and these rotation speed sensors 10, 11, 12, 13 are provided with an electronic control unit (ABS-ECU) 14. Is electrically connected to
The electronic control unit 14 includes a central processing unit (CPU)
And a storage device (ROM, RAM) and an input / output interface. The main unit detects wheel speeds based on signals input from the respective rotation speed sensors 10, 11, 12, and 13 and detects the input signals and reduces the wheel speeds. The ground speed of the vehicle, that is, the vehicle body speed is detected based on the speed and the like, and the wheels Fr,
It is configured to determine the lock of Fl, Rr, Rl and output a control signal for temporarily reducing the braking force on the wheel that may be locked. The electronic control units 9 and 14 are electrically connected to each other so as to be able to perform data communication with each other.

A brake master cylinder 16 operated by a brake pedal 15 is connected to a proportional valve 17, and the proportional valve 17 is connected to an electrically controlled actuator 18. The actuator 18 supplies hydraulic pressure to the brake cylinders 19, 20, 21, and 22 of the wheels Fr, Fl, Rr, Rl. The actuator 18 is mainly composed of a solenoid valve such as a three-position solenoid valve, a hydraulic pump, and a reservoir. The actuator 18 switches the solenoid valve in accordance with an output signal from the electronic control unit 14 so that the braking force of each wheel is controlled. Or the braking force is maintained, and the braking force is selectively increased so as to be increased by the hydraulic pressure from the pump. Note that a conventionally known device can be used as the antilock brake system 2.

As described above, the anti-lock brake
The system 2 reduces the braking force on the wheel, that is, the braking torque of the wheel, by detecting the situation in which the wheel speed decreases with respect to the vehicle speed and the wheel locks with the braking. Avoid locking and maintain frictional forces with the road surface. Therefore, in a state where the antilock brake system 2 is functioning normally, the rotation of the wheels can be maintained even when the brake pedal 15 is greatly depressed to perform braking. Therefore, even if the lock-up clutch 7 is engaged up to a low vehicle speed, the engine speed can be kept high by the torque input from the automatic transmission 1 to the engine 3, so that there is no danger of engine stall. On the other hand, when the anti-lock brake system 2 is not functioning normally, or in a vehicle not equipped with this system, the wheels lock when the braking force is large. At this time, if the lock-up clutch 7 is engaged, the engine speed is forcibly reduced. Even if the control for immediately releasing the lock-up clutch 7 is executed to avoid this, the response delay of the control is delayed. As a result, the engine speed further decreases. Therefore, when the lock-up clutch 7 is engaged up to a low vehicle speed, there is a possibility that the engine is stalled due to a delay in the locking of the wheels and the release control of the lock-up clutch 7.

Therefore, in the control device according to the present invention, the minimum speed at which the lock-up clutch 7 is engaged, that is, the minimum engagement speed Vmin, is determined as follows according to the presence or absence of the antilock brake system 2 or the function thereof. Control. FIG. 1 shows an example of the control.
It is determined whether or not there is an antilock function (ABS) for controlling the braking force so as to prevent locking of the wheels (step 1).
This means that the anti-lock brake system 2 is not functioning properly in addition to the above-described determination that the anti-lock brake system 2 is functioning properly and that the anti-lock brake system 2 is not functioning normally due to the failure or the switch being shut off. Including judgment.

If the anti-lock function is functioning normally or the anti-lock function is provided, the routine proceeds to step 2, where the lower limit speed V of the lock-up clutch 7 is applied.
min is set to a predetermined value α which is a relatively small value. On the other hand, if it is determined in step 1 that the anti-lock function is not functioning properly or that there is no anti-lock function, the process proceeds to step 3 where the lower limit engagement speed Vmin of the lock-up clutch 7 is set to Is set to a value β (> α) larger than the value α. Steps 2 and 3 correspond to the lock-up control means in the first aspect of the present invention.

Therefore, when the anti-lock brake system 2 is provided and is functioning properly, the lock-up clutch 7 is maintained in the engaged state up to the low vehicle speed. This can be specifically implemented by changing the map described with reference to FIG. In the braking state or the coast state, the lock-up clutch 7 is engaged and the engine 3 is forcibly rotated by the torque input from the automatic transmission 1 side, even though the engine 3 is in the idling state. Therefore, the engine speed can be maintained at a relatively high speed up to a low vehicle speed. Therefore, at that time, even if the supply of fuel to the engine 3 is stopped, engine stall does not occur,
Fuel efficiency can be improved.

On the other hand, when the anti-lock function is not provided or when the anti-lock function is not operating normally, the lock-up clutch 7 is released at a relatively higher vehicle speed than in the above case. Specifically, this is done by preparing such a map in advance,
When the system 2 is not mounted or when it is detected that the system 2 is not functioning properly, it can be implemented by reading the map and performing control based on the map. Therefore, when the vehicle speed decreases with braking and reaches the engagement lower limit vehicle speed of the lock-up clutch 7, the lock-up clutch 7 is released. At this time, even if the wheels are locked and the engine speed further decreases due to a response delay of the release control of the lock-up clutch 7, the engine stall does not occur because the engine speed is relatively high. .

The vehicle speed V is basically detected based on the rotational speed of the wheels. However, the antilock brake system 2 is used when the wheels are locked or in order to avoid locking.
Does not reflect the actual ground speed of the vehicle. Therefore, in order to accurately detect the vehicle speed, when the antilock brake system 2 is mounted and functions normally, the vehicle speed is adopted as the vehicle speed V at the time of idling or braking and control is performed. FIG. 2 shows a control example of the selection of the vehicle speed. It is determined whether or not the vehicle is idling (step 11). When the determination is affirmative, the vehicle speed VB is adopted as the vehicle speed V (step 12). Conversely, if a negative determination is made, the wheel speed VW is adopted as the vehicle speed V (step 13).

The reason why the vehicle speed VB is adopted as the vehicle speed V is as follows.
This is because the wheel speed may not coincide with the vehicle speed due to braking. Therefore, the detection of the braking state may be performed as a prerequisite. Therefore, the above step 11 is replaced with a step of detecting the presence or absence of a brake signal. You may. Alternatively, the step of determining the idling state based on the output signal of the idle switch and detecting the braking state based on the output signal of the brake switch may be replaced with a step of detecting the braking state.

As described above, conventionally, when a brake operation is performed in a state where the lock-up clutch is engaged, the lock-up clutch is controlled to be immediately released. If the vehicle speed is equal to or higher than the engagement lower limit vehicle speed of the clutch 7, the lock-up clutch 7 is maintained in the engaged state even when the brake operation is detected. FIG. 3 shows an example of the control, in which the vehicle speed V is compared with an engagement lower limit vehicle speed Vmin of the lock-up clutch 7 (step 21).
If so, the process proceeds to step 22, wherein the antilock function (AB) for controlling the braking force so as to prevent the wheels from being locked.
It is determined whether S) is present. This step 22 is a determination step similar to step 1 shown in FIG. 1 described above.

If it is determined in step 22 that the anti-lock function is provided, or if the anti-lock brake system 2 is provided and it is determined that the anti-lock brake system 2 is functioning normally, the process proceeds to step 23 to lock. A control signal (L / CO) for engaging (ON) the up clutch 7
N) is output. On the other hand, if it is determined in step 22 that the antilock function is not provided, or if it is determined that the antilock brake system 2 is not operating normally, the process proceeds to step 24 to determine whether the brake operation has been performed. Determine whether or not. This step 24 corresponds to claim 2
Corresponds to the braking detection means of the invention.

If the brake is not operated, that is, if the brake is off, the routine proceeds to step 23, where the lock-up clutch 7 is maintained in the engaged state. When the brake operation is performed, that is, when the brake ON is detected, the process proceeds to step 25, and a control signal (L / C OFF) for releasing (OFF) the lock-up clutch 7 is output. These steps 23 and 25 correspond to claim 2
Corresponds to the lock-up control means of the invention.

Therefore, if the anti-lock function is working normally, the lock-up clutch 7 must be engaged until the vehicle speed decreases to the engagement lower limit speed, so that the engine 3 rotates at a speed higher than the idling speed. As a result, the fuel can be cut off (fuel cut) for a long time, and the fuel efficiency can be improved.

When the brake pedal 15 is depressed while traveling on a road having a low coefficient of friction, such as a snow-covered road, the wheels lock relatively easily. In such a case,
Since it is normal to stop as quickly as possible while maintaining the posture of the vehicle body, it is also possible to control the lock-up clutch 7 to be released based on the operation of the antilock brake system 2. . An example of control in that case is shown in FIG.

In this control example, it is assumed that a road surface friction coefficient such as a frozen road surface is small, and therefore, the vehicle speed VB is adopted as the vehicle speed V. First, the vehicle speed VB is compared with the engagement lower limit speed Vmin of the lock-up clutch 7 (step 31). If the vehicle speed VB is high, it is determined whether the antilock brake system 2 is operating (step 32). This can be determined based on whether a signal is output to the actuator 18 described above.

If the antilock brake system 2 is operating, the routine proceeds to step 33, where the elapsed time T from the start of the operation is compared with a predetermined reference time TA. As shown in FIG. 5, the reference time TA is a time until a predetermined point in time when the braking force is reduced and the wheel speed VW tends to increase. This is a value determined in advance based on the maximum deviation from the speed. Therefore, step 33 corresponds to the antilock control means in the third aspect of the present invention.

If the elapsed time T from the start of the operation of the antilock brake system 2 does not reach the reference time TA, the control state at that time is continued (step 3).
4). Specifically, the lock-up clutch 7 is engaged,
Further, the control of the braking force by the antilock brake system 2 is continued. On the other hand, if the elapsed time T has reached the reference time TA, a control signal (L / C OFF) for releasing (OFF) the lock-up clutch 7 is output (step 35). The shift control in that case is performed in the same manner as usual. This step 35 corresponds to the lock-up control means in the third aspect of the present invention.

Therefore, according to the control shown in FIG. 4, when the antilock brake system 2 is operating to control the braking force, the time when the wheel speed VW tends to increase, that is, the engine speed increases. At this point, the lock-up clutch 7 is released. Therefore, the transmission of torque from the automatic transmission 1 is interrupted in a state where the inertial force of the rotating element such as the engine 3 acts to increase the rotating speed, so that the rotating speed of the engine 3 decreases at least. As a result, the engine stall can be prevented from occurring. As described above, in the control example shown in FIG. 4, the engine stall becomes difficult, so that the engagement lower limit vehicle speed of the lock-up clutch 7 can be reduced to the low vehicle speed side. It is possible to increase the fuel cut time by enlarging the engagement area and improve fuel efficiency.

In step 31, the vehicle speed VB is compared with the engagement lower limit vehicle speed Vmin.
If it is less than n, the routine immediately proceeds to step 35, where a control signal for releasing the lock-up clutch 7 is output. If a negative determination is made in step 32 because the antilock brake system 2 is not operating, normal control is executed based on the map shown in FIG. 12 (step 36).

Another example of the control for releasing the lock-up clutch 7 when the engine speed is increased will be described below. The example shown in FIGS. 6 and 7 detects the braking state in which the wheels are locked based on the wheel speed VW and the vehicle body speed VB, and detects the increase in the engine speed to release the lock-up clutch 7. This is an example of controlling.

FIG. 6 shows a routine executed by performing braking. First, a judgment is made on the flag F1 (step 41). This flag F1 is a flag which is set to "1" when a braking state enough to lock the wheels is detected, and is reset to zero when an idle / off state is detected. Therefore, the process proceeds to step 42. In this step 42, the deviation VS (= VB -VW) between the vehicle speed VB and the wheel speed VW is compared with a predetermined reference value VS1.

As shown in FIG. 7, when the antilock brake system 2 is operated in accordance with the braking operation, the vehicle speed VB gradually decreases, while the wheel speed VW is lower than the vehicle speed VB. The increase and decrease are repeated. Therefore, the deviation VS between the vehicle speed VB and the wheel speed VW is
As shown in the middle part of FIG. 7, the value is repeatedly increased and decreased, and gradually changes to approach zero. In the meantime, it crosses a predetermined reference value VS1. In FIG. 7, the sign is inverted upside down, and the line above the “0” line is negative and the line below it is positive. That is, when the deviation VS is larger than the reference value VS1, the wheel speed VW is far from the vehicle speed VB, and the wheels are close to the locked state.

If it is determined in step 42 that the deviation VS is larger than the reference value VS1, the process proceeds to step 43, where the rate of change d of the deviation VS per unit time is d.
VS (VS dot) is compared with a reference value dVS1 (VS1 dot). The change in the rate of change dVS of the deviation VS is shown by a curve in FIG. 7, and the reference value dVS1 is set as a positive value. Therefore, if the rate of change dVS of the deviation VS is greater than the reference value dVS1, it means that the wheel speed VW is sharply away from the vehicle speed VW, that is, the wheel speed VW is rapidly decreasing.

Therefore, if it is determined in step 42 that the deviation VS is greater than the reference value VS1, and if it is determined in step 43 that the rate of change dVS of the deviation VS is greater than the reference value dVS1, the wheel speed VW decreases. It will tend. That is, the wheels tend to lock. In this case, the flag F1 is set to "1" (step 44). Then, the wheel speed VW is compared with the engagement lower limit speed Vmin of the lock-up clutch 7 (step 4).
5).

On the other hand, if the deviation VS is equal to or smaller than the reference value VS1, the routine immediately proceeds to step 45. Similarly, when the rate of change dVS of the deviation VS is equal to or less than the reference value dVS1, the routine immediately proceeds to step 45.

On the other hand, if the flag F1 has already been set to "1" after a lapse of time after the braking has been started, that is, if the wheel speed VW is dropping significantly, step 1
If it is determined that the flag F1 is "1", the routine proceeds to step 46 instead of step 42. In this step 46, the rate of change dVS of the deviation VS is compared with a second reference value dVS2 (VS2 dot). The second reference value dVS2 is set as a negative value as shown in FIG. 7. Therefore, if the rate of change dVS of the deviation VS is smaller than the second reference value dVS2, the deviation VS rapidly decreases. That is, the wheel speed VW is approaching the vehicle speed VB.

Therefore, the rate of change dVS is equal to the second reference value dVS2.
If it is smaller, the routine proceeds to step 47, where it is determined whether the deviation VS is smaller than a second reference value VS2 for the deviation. The second reference value VS2 for this deviation is shown in FIG.
As shown in FIG. 7, the value is larger than the above-mentioned first reference value VS1. Therefore, in this step 47, the deviation VS
Is smaller than the second reference value VS2,
In step 46, the rate of change dVS is equal to the second reference value dV.
In combination with the fact that the wheel speed is equal to or less than S2, the wheel speed VW tends to increase past the minimum value. In this case, the flag F2 is set to "1" (step 48), and the routine proceeds to step 45.

On the other hand, when it is determined in step 46 that the rate of change dVS is equal to or greater than the second reference value dVS2, and in step 47, it is determined that the deviation VS is equal to or greater than the second reference value VS2. If so, the process immediately proceeds to step 45.

At step 45, the wheel speed VW is judged. If the wheel speed VW is lower than the engagement lower limit speed Vmin of the lock-up clutch 7, it is judged whether or not the first flag F1 is "1" (step 45). Step 49). As described above, the first flag F1 is set to "1" when the wheels tend to lock, so if the first flag F1 is determined to be "0" in step 49, Means that the vehicle is slowly decelerated, and in this case, the wheel speed VW and the vehicle speed VB are substantially the same, so that the control signal (L / C OFF) for releasing the lock-up clutch 7 ) Is output (step 50).

On the other hand, if it is determined in step 49 that the first flag F1 is set to "1", the brake pedal 15 is greatly depressed and the wheels tend to lock. In other words, if the antilock function is working effectively, the braking force is being controlled.
Therefore, in this case, the routine proceeds to step 51, where the second flag F2 is determined.

As described above, the second flag F2 is
When the braking force is controlled and the wheel speed VW tends to increase so as to approach the vehicle speed VB, it is set to "1".
If it is determined at step 51 that the second flag F2 is "1", the routine proceeds to step 50, where the control signal (L / C OF) for releasing the lock-up clutch 7 is issued.
F) is output. If it is determined in step 51 that the second flag F2 is "0", the routine returns.

If it is determined in step 45 that the wheel speed VW is equal to or higher than the minimum engagement speed Vmin, the process immediately proceeds to step 51, and the lock is performed according to the state of the second flag F2 as described above. The up clutch 7 is controlled. That is, if the second flag F2 is set to "1" and the wheel speed VW tends to increase, the lock-up clutch 7 is released.

That is, in the control example shown in FIG. 6, when the flags F1 and F2 are both set to "1", the release signal of the lock-up clutch 7 is output. It is shown as As can be seen from FIG. 7, the release of the lock-up clutch 7 while the braking force is being controlled is executed when the wheel speed VW is increasing, that is, when the engine speed is increasing. As a result, since the inertial force acts in a direction to increase the rotation speed of the engine 3, engine stall can be prevented. As described above, in the control example shown in FIG. 6, since the engine stall becomes difficult, it is possible to reduce the engagement lower limit vehicle speed of the lock-up clutch 7 to the lower vehicle speed side. It is possible to increase the fuel cut time by enlarging the engagement area and improve fuel efficiency.

Steps 46 and 47 correspond to the speed deviation detecting means in the invention of claim 4, and steps 50 and 51 correspond to the lock-up control means in the invention of claim 4.

In the example shown in FIG. 6, the lock state of the wheels and the state of the anti-lock control are determined based on the vehicle body speed VB and the wheel speed VW, and the release control of the lock-up clutch 7 is performed. Since the operation of the brake system 2 can be determined by the output signal, the control can be performed in the same manner as in FIG. 6 using the signal.

FIG. 8 shows an example of the control. First, it is determined whether or not the antilock brake system 2 is operating (step 61). This can be determined by whether or not a control signal is output to the actuator 18 described above. If the determination is affirmative, the tendency of any of the wheels to lock is detected, and the braking force is controlled. Will be. Therefore, in this case, the routine proceeds to step 62, where the rate of change dVS of the deviation VS is compared with a preset reference value dVS3 (VS3 dot).

A third reference value dVS3 for this change rate
Is set as a negative value as shown in FIG. 9, which is the same as the above-mentioned second reference value dVS2 for the change rate, and the change rate dVS is smaller than the third reference value dVS3. In other words, the wheel speed VW is rapidly increasing so as to approach the vehicle speed VB. Therefore, the rate of change dVS
Is smaller than the third reference value dVS3 in step 62, the difference VS is compared with the third reference value VS3 (step 63).

The third reference value VS3 for this deviation is
Like the second reference value VS2 for the above-described deviation, it is set as a positive value. Therefore, if it is determined in step 63 that the deviation VS is smaller than the third reference value VS3, the wheel speed VW Increases to approach the vehicle speed VB, and the flag F3 is set to "1" (step 64). Next, the vehicle body speed VB is compared with the engagement lower limit speed Vmin of the lock-up clutch 7 (step 65).

If a negative determination is made in step 61 because the antilock brake system 2 is not operating, the flag F3 is reset to zero (step 66), and the routine proceeds to step 65. In addition, even when the antilock brake system 2 is operating, the change rate dV
If S is equal to or greater than the third reference value dVS3 or if the deviation VS is equal to or greater than the third reference value VS3, one of the wheels is in a state close to lock, so that step 65 is immediately executed. Then, the vehicle speed VB is compared with the engagement lower limit speed Vmin.

If it is determined in step 65 that the vehicle body speed VB is higher than the engagement lower limit speed Vmin, the flag F3 is determined (step 67). If the flag F3 is set to "1", the control signal (L / C) for releasing the lock-up clutch 7 indicates that the rotational speed of the wheels, that is, the engine rotational speed is in a state of increasing as described above. OFF) is output (step 68). Therefore, when the lock-up clutch 7 is released in a state where the braking force is controlled so that the wheels are not locked, the lock-up clutch 7 is locked when the rotation speed of the wheels and the engine 3 substantially integrated therewith is increasing. The up clutch 7 is released. This can be seen from the time chart of FIG.
Is released in this manner, the inertia force can be applied in the direction of increasing the engine speed, and as a result, engine stall can be effectively prevented.

If it is determined in step 65 that the vehicle speed VB is equal to or lower than the engagement lower limit speed Vmin, the flow immediately proceeds to step 68 to output a lock-up clutch 7 release signal. This is to prevent engine stall. If it is determined in step 67 that the flag F3 is "0", it means that the antilock brake system 2 is not operating, or that the wheels are locked even if it is operating. So
The routine returns without releasing the lock-up clutch 7. Steps 62 and 63 correspond to the speed deviation detecting means in the invention of claim 4, and steps 67 and 68 correspond to the lock-up control means in the invention of claim 4.

If the lock-up clutch 7 is engaged, the engine 3 and the wheels are substantially integrally connected, so that the engine speed can be kept high even during idling during coasting. When the engine 3
As described above, it is possible to improve the fuel efficiency by cutting off the fuel supply to the fuel cell. Therefore, an example of a control routine of the fuel cut-off (fuel cut) is briefly described as shown in FIG.

In FIG. 10, first, it is determined whether or not the engine 3 is in an idle ring state (step 71). This is the ON / OFF of the idle switch normally provided in the vehicle.
The determination can be made based on the OFF state. If an affirmative determination is made in step 71 due to the idling state, it is determined whether the fuel cut flag F / C is ON (step 72).

When it is determined in step 72 that the fuel cut flag F / C is OFF because the fuel cut has not been executed yet, the engine speed Ne is compared with the fuel cut lower limit speed Nc (step 72). 73). The fuel cut lower limit rotation speed Nc is a lower limit engine speed at which the fuel cut is executed, and is a reference rotation speed at which the fuel cut is performed when a predetermined condition is satisfied in a state of being equal to or higher than the lower limit rotation speed. Therefore, if the engine speed Ne is equal to or higher than the fuel cut lower limit speed Nc, the fuel cut flag F / C is turned on (step 74). as a result,
The engine 3 is controlled by an engine electronic control unit (not shown).
The supply of fuel to or fuel injection is shut off. On the other hand, if the engine speed Ne is lower than the fuel cut lower limit speed Nc, the routine returns without performing any particular control.

On the other hand, the fuel cut has already been performed, and the fuel cut flag F
If it is determined that / C is ON, the engine speed Ne is compared with the fuel cut return speed NRT (step 75). The fuel cut return rotation speed NRT is a reference rotation speed at which supply or injection of fuel in the engine 3 is restarted. When the engine rotation speed Ne falls below the fuel cut return rotation speed NRT, fuel supply or injection is stopped. Will be resumed. Therefore step 7
If it is determined in step 5 that the engine speed Ne is equal to or higher than the fuel cut return rotation speed NRT, the routine returns without performing any special control. Conversely, the engine speed Ne becomes the fuel cut return rotation speed NRT. If the rotational speed is lower, the fuel cut flag F / C is set to 0F.
It is set to F (step 76). At the same time, the supply of fuel to the engine 3 or the fuel injection is restarted by the engine electronic control unit (not shown).

The above-mentioned fuel cut return rotation speed NRT
Is set to the lower limit speed that will cause engine stall if the supply of fuel continues to be stopped, but if the antilock function is effective as described above, the rotation of the wheels even during braking Since the rotation of the engine is maintained by the torque that is maintained and input from the transmission to the engine, the lower limit rotation speed at which engine stall does not occur even when the supply of fuel is stopped is reduced. On the other hand, if there is no anti-lock function or if it does not function effectively, the wheels are likely to lock during braking, and therefore it is not expected that the torque of the transmission will maintain the rotation of the engine. In addition, the lower limit of the number of revolutions at which the engine is stalled due to the stop of the fuel supply is increased. Therefore, in the present invention, the fuel cut return rotation speed at the time of deceleration in a vehicle having an antilock function may be set lower than a vehicle without an antilock function or a vehicle in which the antilock function is not operating normally. . In this way, the antilock function can be effectively functioned in the fuel cut improvement control by fuel cut together with the vehicle behavior stabilization control.

In the first and second aspects of the present invention, the so-called lock-up lower limit vehicle speed of a vehicle having an anti-lock function is set to be lower than the lock-up lower limit vehicle speed of a vehicle without an anti-lock function. The vehicle having the anti-lock function means a vehicle having no anti-lock function as a base vehicle and having the anti-lock function mounted thereon. If the power transmission characteristics or the configuration and characteristics of the so-called power plant or power train system such as the engine, the automatic transmission, and the reduction ratio, or the engine and the automatic transmission almost match, these anti-lock functions are provided. The base vehicle of the vehicle and the vehicle that does not have the same base vehicle.

In the present invention, the lock-up clutch can be half-engaged, that is, can be slip-controlled.
The control device of the present invention can be applied to control when the lock-up clutch is released from slip control. In this case, if the lock-up clutch is slip-controlled, the lock-up lower limit vehicle speed can be set to a lower vehicle speed than the lower limit vehicle speed in the engaged state. Since the vehicle speed can be further reduced, fuel efficiency can be further improved.

Further, the present invention is not limited to the above-described specific example, and an antilock brake system having an appropriate configuration such as 4 channels of 4 sensors or 3 channels of 4 sensors can be used.
The rotation speed and speed used as various references used in the control need not be constant values, but may be variables that can be changed according to the state of the vehicle.

[0070]

As described above, according to the control device of the first aspect of the present invention, the lock-up clutch is engaged at a lower vehicle speed in a vehicle having an anti-lock function of wheels than in a vehicle without the function. Will be maintained. Therefore, during braking (coasting), the engine speed is maintained at a high speed by the torque transmitted from the automatic transmission, and the engine speed can be maintained even when the fuel supply is cut off. Is performed at the time of braking or coasting, thereby improving fuel efficiency. If the anti-lock function is not provided, the lock-up clutch is released at a relatively high vehicle speed. It is not possible to forcibly reduce the rotation speed to a low speed, and as a result, it is possible to prevent engine stall due to locking of the wheels or a state close thereto.

According to the second aspect of the present invention, when there is no anti-lock function for controlling to prevent the wheels from being locked during braking, the lock-up clutch is released based on the detection of the braking operation. Can be Therefore, even if the wheels are locked with the braking operation, the engine speed cannot be forcibly reduced to a low speed, so that engine stall can be prevented. On the other hand, if the vehicle has an anti-lock function, even if a braking operation is detected, the lock-up clutch will not be immediately disengaged and the lock-up clutch will not be released if the vehicle speed falls to the predetermined lower limit vehicle speed. The clutch is released. Therefore, when the anti-lock function is provided, the lock-up clutch is engaged up to a low vehicle speed, and the engine speed is maintained at a high speed by the torque transmitted from the automatic transmission, so that the fuel supply can be shut off during that time. Thus, fuel efficiency can be improved, and, naturally, engine stall can be avoided.

According to the third aspect of the present invention, when the anti-lock control device operates to control the braking force so that the wheels do not lock, and when the lock-up clutch is to be released, the braking force changes. Accordingly, the rotation speed of the wheels and the rotation speed of the engine connected thereto via the lock-up clutch decrease and increase gradually as a whole, but when the rotation speed of the engine decreases immediately after the start of the control of the braking force. The lock-up clutch will be engaged and the lock-up clutch will be released during the subsequent upward trend. That is, the lock-up clutch
It is not released at the same time as the control of the braking force by the antilock control device, but is released when the inertial force acts in the direction to increase the engine speed, so that it is possible to prevent engine stall beforehand. it can. In addition, since the time required to maintain the engine speed at or above the predetermined speed by engaging the lock-up clutch becomes longer, the fuel consumption can be improved by lengthening the time of stopping the supply of fuel to be performed together with the engine speed. become.

According to the fourth aspect of the present invention, when the anti-lock control device operates to control the braking force so that the wheels do not lock, and when the lock-up clutch is to be released, the braking force changes. Accordingly, the rotation speed of the wheels and the rotation speed of the engine connected thereto via the lock-up clutch gradually increase and decrease as a whole, but the lock-up clutch is operated when the wheel speed approaches the vehicle body speed, that is, when the engine speed is increased. They will be released when the numbers are on the rise. That is, when the lock-up clutch is released while the anti-lock control device is operating, the lock-up clutch is released when the inertial force acts in a direction to increase the engine speed, and the engine stall is released. Can be prevented beforehand. In addition, since the time required to maintain the engine speed at or above the predetermined speed by engaging the lock-up clutch can be lengthened, the fuel consumption can be improved by lengthening the time for stopping the supply of fuel to be performed together with the time. become.

[Brief description of the drawings]

FIG. 1 is a flowchart for explaining an example of control for changing an engagement lower limit speed of a lock-up clutch according to the presence or absence of an anti-lock brake system or its function.

FIG. 2 is a flowchart illustrating a control example for changing data adopted as a vehicle speed between an idling state and a non-idling state.

FIG. 3 is a flowchart illustrating an example of control for changing the release timing of a lock-up clutch according to the presence or absence of an antilock brake system or its function.

FIG. 4 is a flowchart for explaining a control example in which control for releasing a lock-up clutch is performed by timer control when a wheel speed is increasing.

5 is a time chart showing a lock-up clutch release timing when the control shown in FIG. 4 is performed.

FIG. 6 is a flowchart for explaining a control example in which control for releasing the lock-up clutch when the wheel speed is increasing is performed based on the wheel speed and the vehicle speed.

7 is a time chart showing a lock-up clutch release timing when the control shown in FIG. 6 is performed.

FIG. 8 is a flowchart for explaining a control example of executing control for releasing the lock-up clutch when the wheel speed is increasing based on the operation signal of the anti-lock brake system, the wheel speed, and the vehicle body speed; is there.

9 is a time chart showing a lock-up clutch release timing when the control shown in FIG. 8 is performed.

FIG. 10 is a flowchart schematically illustrating control of fuel cut.

FIG. 11 is a diagram schematically showing an example of a control system of a vehicle targeted by the present invention.

FIG. 12 is a diagram showing an example of a map for controlling shifting and engagement / disengagement of a lock-up clutch in a vehicle targeted by the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Automatic transmission 2 Anti-lock brake system 3 Engine 4 Torque converter 5 Pump impeller 6 Turbine runner 7 Lock-up clutch 9 Electronic control device for automatic transmission 14 Electronic control device for anti-lock brake system 15 Brake pedal

Claims (4)

[Claims] An automatic transmission with a lock-up clutch for a vehicle including a fluid coupling including a lock-up clutch that mechanically connects an input member and an output member and that is released at a vehicle speed lower than a predetermined lower limit vehicle speed. In the control device, when there is an anti-lock function for controlling the braking force of the wheels so as to prevent the wheels from locking during braking, the lock-up clutch is disengaged as compared to a case where there is no anti-lock function. A control device for an automatic transmission with a lock-up clutch, comprising control means. 2. An automatic transmission with a lock-up clutch for a vehicle having a fluid coupling incorporating a lock-up clutch mechanically connecting an input member and an output member and being released at a vehicle speed lower than a predetermined lower limit vehicle speed. In the case where the control device does not have a brake detecting means for detecting that a braking operation has been performed, and an antilock function for controlling a braking force of the wheels so as to prevent the wheels from locking during braking, the vehicle speed is lower than the lower limit vehicle speed. Or when the braking detection means detects a braking operation, releases the lock-up clutch, and has an anti-lock function that controls the braking force of the wheels so as to prevent the wheels from locking during braking. Releases the lock-up clutch when the vehicle speed becomes lower than the lower limit vehicle speed regardless of the detection of the braking operation by the brake detection means. Control apparatus for an automatic transmission with a lock-up clutch, characterized in that a lock-up control means. 3. An anti-lock control device for controlling a braking force so as to prevent the wheels from being locked during braking, wherein the input member and the output member are mechanically connected and released when a predetermined condition is satisfied. A control device for an automatic transmission with a lock-up clutch for a vehicle equipped with a fluid coupling incorporating a built-in lock-up clutch, which detects an elapsed time from the time when the anti-lock control device operates to start controlling the braking force. Anti-lock control detecting means, and the lock-up clutch when the anti-lock control detecting means detects that an elapsed time from the start of braking force control by the anti-lock control device has reached a preset reference time. Control of an automatic transmission with a lock-up clutch, comprising: lock-up control means for performing release control of the clutch. Location. 4. An anti-lock control device for controlling a braking force so as to prevent the wheels from being locked during braking, wherein the input member and the output member are mechanically connected and released when a predetermined condition is satisfied. A control device for an automatic transmission with a lock-up clutch of a vehicle equipped with a fluid coupling incorporating a lock-up clutch, wherein a difference between a wheel speed during operation of the anti-lock control device and a vehicle speed obtained from the wheel speed is determined. And a lock-up clutch that releases the lock-up clutch when the difference between the wheel speed and the vehicle speed is small. Control device for automatic transmission with