JPH08285074A - Lock-up control device for automatic transmission - Google Patents

Abstract

PURPOSE: To make sudden deceleration judgment appropriate by starting lock-up clutch release control in the case of detecting sudden deceleration in the coasting state of a vehicle, and completely opening without release in the case of detecting sudden deceleration again after waiting for the specified time set according to the delay time. CONSTITUTION: In the case of a vehicle being in a coasting state, coasting lock-up capacity control is performed to control a lock-up state appropriately at the coasting time in order to improve fuel consumption and to avoid an engine stalling at the time of sudden deceleration. When sudden deceleration is detected after detecting the moving state of the vehicle to have become a coasting state, the locking capacity of a lock-up clutch is released. In the case of not sensing sudden deceleration again after the lapse of time corresponding to the response delay of lock-up clutch operating oil pressure after the start of lock-up clutch release control, a controller 9 suspends lock-up clutch release control and executes also control for relocking.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lockup control device for an automatic transmission in a vehicle.

[0002]

2. Description of the Related Art In order to improve fuel efficiency by improving transmission efficiency, an automatic transmission is equipped with a torque converter which is capable of operating under a vehicle operating condition in a lockup region where a torque increasing function and a torque fluctuation absorbing function are not required. Then, there is a tendency to switch to a lock-up type in which the input / output elements are directly connected to each other so that a lock-up state can be achieved. In the lock-up control of this type of torque converter, conventionally, for example, “NISSAN R” issued by the applicant of the present application.
As shown in the automatic transmission described in "E4R01A Full-range Electronic Control Automatic Transmission Maintenance Manual" (Reference 1), and in Fig. 8, the lock-up ON line is illustrated by a two-dot chain line, and the lock-up OFF line is a one-dot chain line. As illustrated in FIG. 5, it is determined which of the lockup (L / U) region and the converter (C / V) region the vehicle is operating in, which is defined by the throttle opening TH (engine operating load) and the vehicle speed V. According to the determination result, the torque converter is locked in the lockup region by engaging the lockup clutch to directly connect the input and output elements to each other, and in the converter region, the lockup clutch is released to release the direct connection. It is customary to enter the converter state. Then, in order to enhance the fuel consumption improving effect by lockup of the torque converter, it is necessary to expand the lockup region (low speed L / U) so as to lockup the torque converter to the lowest possible load operation and low vehicle speed. This lockup area is defined as shown in FIG. 8, for example.

On the other hand, as a device for improving the fuel consumption of a vehicle, power from an engine during so-called coasting (coast running) including deceleration by releasing the accelerator pedal is unnecessary depending on whether the vehicle is in a coasting state or not. Therefore, there is a fuel cut device that stops the fuel supply to the engine during this period. This device, when the engine speed drops to the set speed (fuel recovery speed),
In order to prevent engine stall (stalling), fuel cut is stopped and fuel supply is restarted (fuel recovery). In such a device, it is better to delay the decrease in engine speed during coasting.
The fuel cut time becomes longer and the fuel consumption improvement effect is great. For this reason, generally, in a vehicle equipped with an engine with a fuel cut device, it is common practice to set the torque converter during coasting with the throttle opening TH set to 0/8 to the lockup state as shown in FIG.

[0004]

For these reasons, in a vehicle equipped with an automatic transmission having a torque converter in a transmission system, which can be brought into a lockup state in which input / output elements are directly connected by a lockup clutch, the inertia of the vehicle is increased. It is becoming increasingly common to put the torque converter into a locked-up state in which the input and output elements are directly connected during running, but when braking by depressing the brake pedal during running in such a state, especially on a low friction road (low μ road). In (), since the wheels suddenly stop rotating, there is a concern that the lockup release, which cannot avoid the relatively large response delay of the torque converter, cannot catch up with this, and the engine drive-coupled to the wheels stops. There is a problem that JP-A-4-37
As described in Japanese Patent No. 0465 (Reference 2), when the brake pedal is depressed during coasting, the torque converter in the lockup state is switched to a slip control state in which slip occurs to allow relative rotation between the input / output elements, Furthermore, a technique has been proposed to release the lockup of the torque converter during sudden deceleration with a larger brake pedal depression force.In this case, however, the torque converter immediately slips when coasting even though the braking is not sudden braking. For this reason, the slip of the torque converter reduces the engine speed by the slip amount, and the fuel cut must be stopped earlier to recover the fuel, which reduces the fuel consumption improvement effect of the fuel cut. , Not perfect.

Therefore, the present applicant has previously filed Japanese Patent Application No. 6-1.
According to No. 57325, during coasting including deceleration of the vehicle, it is detected whether or not there is a sudden deceleration, and during the coasting without rapid deceleration, the engagement capacity of the lockup clutch is the smallest engagement within the range in which the torque converter does not slip. Keep the capacity (lock-up intermediate capacity control for coasting), and thereby prevent engine stall due to response delay of L / U release without sacrificing fuel economy improvement effect by fuel cut. We are proposing the technology that According to this, the lock-up control which can improve the fuel consumption and prevent the engine stall at the time of sudden deceleration is realized while solving the above problems.

For example, in the case of realizing two purposes of improving the fuel efficiency and avoiding the engine stall during sudden deceleration,
In order to achieve that, the accuracy of detection of sudden deceleration is important, and if high accuracy can be obtained for detection of sudden deceleration, better control can be expected. If sudden deceleration is not properly detected, the L / U will be too sensitive to deceleration.
If the above is canceled, the former purpose (improvement of fuel consumption) cannot be achieved, and conversely, the latter purpose (avoiding engine stall during sudden deceleration) cannot be achieved with insensitivity. In particular, when the L / U is released unnecessarily, not only the fuel consumption is deteriorated, but also a feeling of discomfort is generated. Above all, the above-mentioned intermediate capacity control lock-up control during coasting is performed. In the state of being released, if it is released although it should not have been released,
The impact will be significant. Also, these problems are
For example, it depends on how to deal with deceleration that occurs when a wheel gets over a step, such as when traveling on a rough road or traveling on a highway.

When high accuracy is required for detection of sudden deceleration, there is a need to avoid the problem that engine stall is likely to occur during sudden braking on a low μ road when the L / U is slowed during deceleration. As a deceleration detection method, a method of obtaining a change in wheel speed is one of effective means. However, the rapid deceleration detection logic for avoiding engine stall on a low μ road requires very high accuracy because the phenomenon to be targeted occurs in an extremely short time. For this reason, for example, the fluctuation of the wheel speed that occurs when passing through a joint or the like that normally exists on the roadway is also detected as a sudden deceleration, and as a result, L / U cancellation (malfunction) is performed due to such erroneous detection. Then, not only the fuel consumption is deteriorated during the actual steady deceleration operation, but the L / U is suddenly released even though the user (driver) does not expect a change before and after the joint, It may cause an uncomfortable feeling such as a sudden change in engine rotation or a drastic change in drivability. In order to avoid this, for example, a rapid deceleration detection method based on a change in wheel speed,
Although it is conceivable to use the method of detecting the operation of the brake together with the method of making a judgment based on the logical product of each of them, this is also the case at the time of gentle braking (even if an ON signal for pedal depression is obtained, it is sudden This is not a braking but a gentle braking based on the driver's intention). Therefore, it is not a complete solution for avoiding the above false detection. In either case, it cannot be said that the means have been exhausted. However, gradual release of L / U contradicts the original aim and purpose of avoiding engine stall, and makes it difficult to achieve both improved fuel economy and avoidance of engine stall during sudden deceleration.

In view of the above points, the present invention improves the above-mentioned disadvantages and inconveniences, makes proper judgment of sudden deceleration based on sudden braking, and even if sudden braking is performed on a low μ road, engine stall at that time is performed. While ensuring the prevention of the above, it is possible to avoid the lockup release due to a malfunction by the re-engagement control at an appropriate timing, thereby improving the fuel efficiency and avoiding the engine stall during sudden deceleration. It is an object of the present invention to provide a lockup control device for an automatic transmission that can be compatible with each other. Another object is to easily apply the method of detecting the sudden deceleration by detecting the change speed of the wheel speed.Even if such sudden deceleration is detected, the fluctuation of the wheel speed due to the joint and the actual sudden braking can be applied. The rapid deceleration based on is to provide a lock-up control device for an automatic transmission that can achieve the above, while being able to reliably identify it and improve accuracy.

[0009]

According to the present invention, the following lockup control device for an automatic transmission is provided. That is, in an automatic transmission having a torque converter in a transmission system, which can be brought into a lockup state in which input / output elements are directly connected by a lockup clutch, a means for determining whether or not a motion state of the vehicle is a coasting state, and a means for determining whether the vehicle is in a sudden state If a rapid deceleration is detected after detecting that the vehicle's motion state is coasting by these means for detecting deceleration and these means,
A means for controlling to release the lock-up clutch, and after the release control of the lock-up clutch is started, when a predetermined time set according to the delay time of the lock-up system has elapsed, the rapid deceleration test is performed again. However, in that case, if sudden deceleration is not detected, lockup control means including means for performing control for canceling the release control of the lockup clutch and engaging again. It is a lock-up control device for an automatic transmission characterized by the following. Further, in the above, the means for detecting a sudden deceleration of the vehicle includes a means for detecting a sudden deceleration by a change speed of the wheel speed or a change in a physical quantity similar thereto, and the predetermined time is a response delay of the lockup clutch operating hydraulic pressure. If the lockup control means detects a sudden deceleration of the wheel speed or a sudden deceleration due to a change in a physical quantity similar to the above, the lockup control means locks up the lockup. While controlling to start the clutch release control, when a time corresponding to the response delay of the lockup clutch operating hydraulic pressure has elapsed, a change in the wheel speed or a change in a physical quantity similar thereto is verified again. A lockup control device for an automatic transmission characterized by the above.

Also, during the waiting time from the first sudden deceleration detection to the reverification, the presence or absence of the sudden deceleration is successively verified, and the rapid deceleration detection at the time of reverification is performed depending on the magnitude of the sudden deceleration occurring during that time. A lock-up control device for an automatic transmission characterized by being configured, and when re-fastening occurs a predetermined number of times or more within a preset time, a lock-up control for a predetermined time after that, or at the time of the next deceleration. A lockup control device for an automatic transmission, characterized in that lockup during deceleration is prohibited until an opportunity. Further, in any one of the above lockup control devices for an automatic transmission, a lockup control device is further provided with a device for detecting the start of braking from the actuation of a brake, and the rapid deceleration detection is performed in combination with the device and is based on each detection. The lockup control device for an automatic transmission is characterized in that rapid deceleration is detected by logical product. Further, the lockup control means,
At the time of re-fastening, the re-fastening control is performed so that the lock-up control command value rises up to a control command value at which valve switching operation occurs, and then gradually returns to the control command value originally set during deceleration. It is a lock-up control device for an automatic transmission, characterized in that it further comprises means for performing.

[0011]

With the above-described structure, in the lock-up control device of the present invention, when sudden deceleration is detected when the vehicle is in the coasting state, the lock-up clutch release control is immediately started. In consideration of the characteristics, wait for a predetermined time set according to the delay time, perform a rapid deceleration test again, and if a sudden deceleration is detected there, the lockup clutch release control is not stopped and the On the other hand, it is possible to complete the release by the control. On the other hand, if the rapid deceleration is not detected during the re-verification, the lock-up clutch release control can be stopped and the re-engagement control can be performed. Therefore, it is possible to prevent the malfunction such as the lockup being released due to the false detection that is not based on the sudden braking on the low μ road, and the rapid deceleration determination can be appropriately performed. The waiting time until re-verification of sudden deceleration made after the predetermined time for that,
Therefore, at the time of sudden deceleration due to actual sudden braking, the release control of the lockup clutch should be advanced and completed to avoid engine stall, or the release control is canceled because of false detection and the original coasting The time to select whether to switch to the re-engagement control side to return to the lockup control in the state can also be set in consideration of the release response delay time of the lockup system. You can do it, and before the lockup is actually released,
It is possible to make an accurate decision as to which one of them is selected, and even in lockup control in coasting state, it is possible to perform necessary re-engagement in the case of re-engagement control and prevent malfunction. At the same time, it is possible to achieve a high degree of both improvement of fuel efficiency and avoidance of engine stall during sudden deceleration. In this case, preferably, the mode of the lockup control in the case where the speed is not rapidly decelerated during the coasting state,
With the lock-up capacity control that controls the engagement capacity of the lock-up clutch to the smallest engagement capacity within the range that does not cause relative rotation between the input and output elements of the torque converter, it can be smoothly returned to this at the time of re-engagement. It is possible to achieve compatibility with the lock-up control by the applicant of the present application, and the present invention can be implemented in such a manner.

As described above, based on the re-verification of the sudden deceleration after the predetermined time, if the control is applied to avoid the engine stall or re-engage, the change in the wheel speed is used to detect the sudden deceleration. The means for detecting a sudden deceleration of the vehicle may include a means for detecting a sudden deceleration based on a change speed of the wheel speed or a change in a physical quantity similar to the wheel speed, and the predetermined time is It is a time corresponding to the response delay of the lockup clutch operating hydraulic pressure, and the lockup control means detects a rapid deceleration of the wheel speed or a rapid deceleration due to a change in a physical quantity similar thereto after detecting that the vehicle is coasting. If the lockup clutch release control is started so that the time corresponding to the response delay of the lockup clutch operating oil pressure elapses, Configured to test a change in physical quantity similar change or even again the wheel speed, the present invention is suitably be performed, likewise makes it possible to realize the above.

Further, as described in claim 3, during the waiting time from the detection of the first sudden deceleration to the reverification, the presence or absence of the sudden deceleration is successively verified, and depending on the magnitude of the frequency of sudden deceleration during that time, the reverification is performed. The invention can be implemented in a configuration adapted for rapid deceleration detection, as well as enabling the above to be realized. Further, preferably, when re-fastening occurs a predetermined number of times or more within a preset time, the lockup during deceleration is performed for a predetermined time or until the next lockup occasion during deceleration. Configured for prohibition, the present invention may be practiced, as well as being able to accomplish the above. Further, as described in claim 5, a device for detecting the start of braking from the actuation of the brake is provided, and the rapid deceleration detection is used together with the device to detect the rapid deceleration by a logical product based on the respective detections. When configured to do so, the present invention may be practiced, as well as capable of accomplishing the above.

Further, as in claim 6, the lock-up control means, when re-fastening, raises the lock-up control command value up to a control command value at which the valve switching operation occurs, and then sets the lock-up control command value during deceleration. The present invention can be implemented as a configuration further including means for performing re-engagement control so as to gradually return to the control command value that has been set, and similarly, it is possible to realize the above.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a lockup control device for an automatic transmission according to an embodiment of the present invention. In the figure, 1 is an engine as a prime mover, and 2 is an automatic transmission (A / T). The automatic transmission 2 receives the power of the engine 1 via the torque converter 3, shifts the input rotation at a gear ratio according to the selected shift speed, and transmits it to the output shaft 4.

Here, in the automatic transmission 2, the shift solenoids 6 and 7 in the control valve 5 are turned on and off.
The selected shift speed is determined by the combination of F, and the torque converter 3 is in the converter (C / V) state in which the input / output elements are not directly connected by the duty control of the lockup solenoid 8 in the control valve 5, or the input / output element. A lockup (L / U) state in which the space is directly connected by a lockup clutch (not shown) can be set. When the drive duty D is 0%, the lockup solenoid 8 puts the torque converter 3 into a converter state by releasing the lockup clutch, and when the drive duty D is 100%, the torque converter 3 is closed by engaging the lockup clutch. Lock up (L / U)
Shall be in a state. The lock-up control valve (hydraulic control valve) in the control valve 5 used for lock-up duty control is a valve that switches to the open side when the drive duty is 0% and to the engagement side when the drive duty is 100%, and the range between them. In the intermediate capacity control based on the duty D, the engagement capacity of the lockup clutch can be arbitrarily set according to the duty D. During such an intermediate capacity control, the valve is in a duty driving state in which the lockup engagement pressure is released and the lockup release pressure is supplied at a duty ratio ratio.

ON / OFF of the shift solenoids 6 and 7,
The drive duty D (lockup control command value) of the lockup solenoid 8 is controlled by the A / T controller 9, and the controller 9 includes a throttle opening sensor 10 for detecting the throttle opening TH of the engine 1. Input the signal from the transmission output shaft 4
The signal from the transmission output rotation sensor 13 for detecting the rotation speed No. is input. In addition, here, the controller 9 receives a signal from the oil temperature sensor 14 that detects the transmission operating oil temperature C, a signal B from the brake switch 15 that is turned on when the brake pedal is depressed, and the wheel speed of the wheel. The signal Vw or the like from the wheel speed sensor 21 to be detected is input. Here, the input information from the throttle opening sensor 10 is applied to the shift control and can also be used to determine whether or not the motion state of the vehicle is the coasting state (coasting state).

The controller 9 executes shift control and lockup control based on these input information. Regarding the shift control, although not shown here, the following shift control can be performed by well-known calculation based on the input information of the throttle opening TH and the transmission output shaft rotation speed No. That is, in the shift control, the controller 9 obtains the optimum shift stage for the current driving state from the throttle opening TH and the vehicle speed V obtained from the transmission output speed No by a lookup method from table data, for example. The shift solenoids 6 and 7 are turned on and off so that the optimum shift speed is selected, and a predetermined shift is performed.

In the lockup control, in this example,
When the vehicle is coasting, the lockup capacity control for coasting is performed to control the lockup state appropriately during coasting, aiming to improve fuel efficiency and avoid engine stall during sudden deceleration. If a sudden deceleration is detected after detecting that the motion state of is in the coasting state, control is performed to release the engagement capacity of the lockup clutch. In this case, as will be described later, the controller 9 again verifies the sudden deceleration when the time corresponding to the response delay of the lockup clutch operating hydraulic pressure has elapsed after the lockup clutch release control has started. ,
At this time, if the sudden deceleration is not detected, the lockup clutch release control is stopped and the control for reengagement is also executed. Preferably, in such lock-up control, the presence / absence of sudden deceleration is sequentially verified during the waiting time from the first sudden deceleration detection to the reverification, and the rapid deceleration at the time of reverification is determined by the frequency of sudden deceleration during that period. Detect.

Here, for the detection of sudden deceleration, the controller 9 obtains the changing speed of the wheel speed Vw based on the input wheel speed information as will be touched on FIGS. Can be detected. Further, preferably, in addition to the above, the lockup control device of the present embodiment is used in combination with a device that detects the start of braking from the actuation of the brake, and rapid deceleration is detected by the logical product of each detection method. In this case, the rapid deceleration detection method also uses the input information from the brake switch 15.

Preferably, in the lock-up control capable of switching to re-engagement as described above, when re-engaging, the controller 9 raises the control command value up to a control command value at which valve switching operation occurs. After that, a process for setting the lockup control command value is executed so as to gradually return to the control command value originally set during deceleration.

FIG. 2 shows the controller 9 in this embodiment.
5 is a program flowchart showing lockup control executed by the computer. 3 and 4 show examples of logics applicable to the control program, such as rapid deceleration detection, re-rapid deceleration determination after a predetermined time, setting of lock-up control command value including lock-up re-engagement control processing, and the like. In the following, in the present example, the controller 9 repeatedly executes the main routine of FIG. 2 by the timed interrupt every Δt = 10 msec in the lockup control.
First, in step S121, the throttle opening T
H, transmission output speed No., and transmission operating oil temperature C are read.

Next, in step S123, for example, as shown in FIG.
Based on the table data corresponding to the lockup vehicle speed diagram (L / U is the lockup area, C / V is the converter area) shown in Fig. 2, the throttle opening TH
And the vehicle speed V calculated from the transmission output speed No., the lockup region L / U and the converter region C / V.
It is determined which of the running states is Here, in the converter region C / V, the drive duty D of the lockup solenoid 8 is set to 0% in step S124 as the L / U control command value (lockup release (L
/ U capacity minimum)), by outputting this to the lockup solenoid 8 in step S131, the torque converter 3 is released by releasing the lockup clutch, as required.
Then, the converter state is set as usual.

In step S123, the lockup area L /
When it is determined to be U, in step S125 corresponding to the inertia traveling detection means, it is determined whether the vehicle is coasting including deceleration, depending on whether the throttle opening TH is less than the minute set value THs. If you determine that you are not coasting,
In step S126, the drive duty D of the lockup solenoid 8 is set to 100% (lockup hold (maximum L / U capacity)), the output process is executed every time step S131 is executed, and the main routine is ended. In this case, the duty D = 10 in step S131.
By outputting the control command corresponding to 0% to the lockup solenoid 8, the torque converter 3 is brought into the lockup state as requested by the engagement of the lockup clutch and as usual. Incidentally, in step S125 as the inertial running detection means, although not shown, instead of the above, it is also possible to determine whether or not the vehicle is coasting based on a signal from an idle switch that is turned on when the accelerator pedal is released. Needless to say.

As a result of the determination according to the above method in step S125, coasting (coasting) is performed in this step.
If it is determined that the vehicle is in the middle, in step S127, the coasting L for coasting when the vehicle is not in the rapid deceleration is further taken into consideration by further considering whether or not the vehicle is in the rapid deceleration.
/ U capacity control should be performed (step S128 side selection), or it should be taken as L / U control in the case of coasting and reflecting the actual vehicle state and hitting a sudden deceleration state. Whether or not the L / U release control should be performed (selection on the step S129 side), or the L / U release control is once started considering it as a sudden deceleration, but if the rapid deceleration state is reached by the determination again during the progress. Since there is no L / U release, stop L / U and re-engage L / U
Whether or not the U re-engagement control should be performed (step S130 side selection) is determined, and L / L is determined.
Determine the aspect of U control.

Then, a necessary L / U control command value is calculated according to the control contents of the steps S128, S129 and S130 selected in step S127, and the corresponding drive duty D of the lockup solenoid 8 is set. Then, step S131 of the output process is executed to control the lockup clutch.

The coasting L / U control for coasting will now be described. In this example, step S1
The L / U capacity control for coasting performed at 28 is performed when the vehicle is coasting but no rapid deceleration is detected and no rapid deceleration is performed. When this is selected, the following is performed. It can be of any content. That is, although it is determined in step S125 that the vehicle is coasting, if not suddenly decelerating, in step S128 corresponding to the lock-up capacity control means for coasting, the lock-up clutch engagement capacity for coasting is calculated. Drive duty of lock-up solenoid 8 corresponding to
(= Dc%) is calculated and set to the lockup solenoid drive duty D (L / U intermediate capacity).

More specifically, in such processing,
For example, until the duration of inertial running exceeds the set time, that is, until the inertial running stabilizes, L /
The drive duty D is set to 1 in conformity with the U area.
When the coasting is set to 00% and the coasting continues for a set time or longer and the coasting is stabilized, the lockup clutch for coasting is based on the map for each gear position from the vehicle speed V and the transmission operating oil temperature C. The engagement capacity is searched, the drive duty Dc% for achieving this capacity is calculated, and this is set as the lockup solenoid drive duty D. Here, for example, the lockup clutch engagement capacity for coasting is the torque converter 3 (lockup clutch).
Is set to the smallest lock-up clutch engagement capacity within the range where slip does not occur, and two-dimensional table data of the vehicle speed V and the transmission operating oil temperature C is obtained in advance by experiments or the like for each gear position.

The drive duty D for coasting thus obtained is output to the lockup solenoid 8 in step S131, and the lockup clutch of the torque converter 3 is engaged with the smallest engagement capacity within the range that does not slip. You can

Further, in such L / U capacity control for coasting, when coasting causes a rapid deceleration after sudden coasting, sudden deceleration and finally deceleration as described later. When the determination is reached, the drive duty D of the lockup solenoid 8 is set in step S129 corresponding to the lockup release means for rapid deceleration, and this is output to the lockup solenoid 8 in step S130, whereby the torque converter 3 is generated. It is possible to prevent the engine 1 from being stopped by the braked drive wheels at the time of the sudden deceleration of the vehicle when the lockup is released to the converter state.

Further, in the case of this intermediate capacity control, since the engagement capacity of the lockup clutch is controlled to be the smallest engagement capacity in the range where the torque converter 3 does not slip as described above, that is, For example, as shown in the time chart of FIG. 7, from the instant t ₁ of transition to coasting to the instant t ₂ of rapid deceleration accompanying the braking operation at instant t _2.
Up to ₃ , the lockup release pressure P _R has been lowered to P _RC corresponding to D = Dc% in advance by the above capacity control, so this ends at the instant t _{4 at} which the lockup engagement pressure P _A intersects. The above L / U release is completed promptly, and the time from the time point t ₃ to the time point t ₄ at which a large deceleration that the vehicle deceleration becomes equal to or more than the predetermined value ΔVs is observed. It is possible to shorten ΔT _C (response delay of lock-up release) and eliminate the concern that engine stall will occur.

According to this control, the above-described effects can be achieved without causing slippage in the torque converter 3, so the fuel cut time is shortened due to the reduction in engine speed due to the slippage, and the fuel cut time is reduced. There is no problem that the fuel efficiency improvement effect due to is sacrificed.

Basically, the L / U capacity control for coasting can be performed as described above, and in FIGS.
Such coasting L / U capacity control is performed in step S20.
This subroutine is executed when the subroutine is executed in a loop that goes through the processes of 1, step S203, and step S204.
The lock-up control of the automatic transmission including the re-engagement control according to the present invention is independent of the details of the rapid deceleration detection method, but is necessary for the description of the embodiment, and will be described below. In some cases, it may be specifically referred to as an example, or simply referred to as sudden deceleration detection (abrupt deceleration detection method).
However, if there is a method of detecting sudden deceleration by a change in wheel speed or a physical quantity similar to that, the method by this control is effective regardless of the details of the method.

The programs of FIGS. 3 and 4 can be read and executed at the timing of execution of step S127 of FIG. 2. In FIG. 3, first, step S2 is executed.
At 01, check if sudden deceleration is detected. The sudden deceleration can be detected by detecting the changing speed of the wheel speed Vw and detecting the sudden deceleration of the wheel speed. Further, in more detail, a rapid deceleration detection method (see FIGS. 5 and 6) may be used in which the rapid deceleration threshold value is compared with a preset rapid deceleration threshold value and rapid deceleration is performed when the wheel speed change speed exceeds this.

As a result of the determination in step S201, when the occurrence of sudden deceleration is not detected, it is checked in step S203 whether the malfunction prevention flag is ON or OFF. If the malfunction prevention flag is OFF, the subsequent process is skipped, and at the same time, in step S204, the processing for turning OFF the rapid deceleration detection flag is performed each time this step is executed, and this subroutine is ended. In this case, it is detected that the inertia running state is detected, and after the above-mentioned inertia running L / U capacity control rush, the step S is performed even once.
If the result of Yes is not obtained in 201, the L / U capacity control for coasting is continued as it is.

Here, the malfunction prevention flag is set to ON in step S208, which will be described later, and also to step S21.
5 or a flag that is set to OFF in step S222. The timing when the flag is set to ON is
It is the time to start the timer for comparison with the waiting time described below, which is introduced to distinguish it from the actual sudden deceleration, in order to avoid erroneously detecting it as the sudden deceleration even though it is not in the sudden deceleration state ( In step S209), therefore, the malfunction prevention flag being ON means that the timer is once activated. The initial value of the flag is set to OFF when the power is turned on. Further, the initial values of the rapid deceleration detection flag and the re-engagement flag (steps S219 and S222) of the other control flags are also set to OFF.

Incidentally, from step S201 to step S2
In the case of proceeding to 03, if the malfunction prevention flag is ON in step S203, as will be described later, step S2
At 05, it is checked whether the re-fastening flag is ON or OFF. Then, if the re-fastening flag is OFF, the control proceeds to the timer count (step S212) processing, and the processing thereafter is executed, while if the re-fastening flag is ON, L / U
The re-fastening control is performed.

On the other hand, if the occurrence of sudden deceleration is detected in step S201, the L / U control command value is set to the minimum engagement capacity in step S202 to avoid the occurrence of engine stall. In this case, the drive duty D corresponding to this is set and is output to the lockup solenoid 8 in step S131 of FIG. Command value setting for executing engine stall avoidance control (step S202)
After that, first, in step S206, it is checked whether the rapid deceleration detection flag is ON or OFF. In this program example, the sudden deceleration detection flag is set in step S described later.
212 (timer increment) → step S213
(Determination of timer <malfunction prevention standby time) → step S
214 (determination of whether rapid deceleration occurrence frequency> sudden deceleration determination occurrence frequency threshold value) → step S215 → when the process is executed in the loop of step S216, it is set to ON in the sudden deceleration detection flag ON setting process in step S216, On the other hand, the flag is set to OFF in step S204.

Therefore, if the sudden deceleration detection flag is ON here, it is not a malfunction (in this program example, as will be described later, the malfunction prevention standby time has elapsed and the Since it has been confirmed that the condition of deceleration occurrence frequency> rapid deceleration determination frequency threshold value is established), the subsequent processes (steps S207 to S219) are skipped and the engine stall avoidance control is continued. That is, this subroutine is finished as it is from step S206.

On the other hand, if the sudden deceleration detection of the current loop (Yes in step S201) is the first one after the previous sudden deceleration L / U release or re-engagement control execution, for example, step S125 in FIG. If the first rapid deceleration detection after the vehicle is determined to be in the inertia running state in the determination step of No., the rapid deceleration detection flag is OFF at that time.
If the sudden deceleration detection flag is in the OFF state as described above (step S204), the following processing for performing control including initialization of the timer proceeds. That is, if the rapid deceleration detection flag is OFF, it is checked in step S207 whether the malfunction prevention flag is ON or OFF.

The malfunction prevention flag indicates that only the L / U capacity control for coasting is executed and the sudden deceleration L / U is not released after the start of vehicle operation and before the L / U opportunity at the time of the previous deceleration. Even if it does, the initial value remains OFF, and the L / U release based on the sudden deceleration detection has progressed and executed in the past, and the L / U is actually released, or it is canceled midway. In any of the cases where the re-fastening is performed, the state in which it is once turned on in the course of the process (step S208) is reset again to the off state (steps S115 and S223). S201 → S202 → S206 → S2
When the loop to 07 is first established based on the first rapid deceleration detection of this time, the malfunction prevention flag is in the OFF state.

Then, as described above, the malfunction prevention flag is set to O.
If it is FF, the step S207 is a step S208-
The process of step S210 is selected here only once, and the process proceeds to step S211. In this process, the flag is switched from OFF to ON in step S208, and the timer is initialized to 0 in step S209. This timer is used for the determination in step S213 described below. Further, in this program example, step S2
At 10, the frequency of sudden deceleration is initialized. The sudden deceleration occurrence frequency is applied to the comparison determination with the sudden deceleration occurrence determination frequency threshold value in step S214 described below. Thus, after the malfunction prevention flag is switched and set, the malfunction prevention flag is ON in the determination of step S207 after the next loop, and as a result, the processes of steps S208 to S210 are not performed and they are skipped.

Thus, in this program example, in step S211, the frequency of sudden deceleration occurrence is incremented each time this step is executed. As a result, the time of executing step S211 in the loop in the case of the above initialization is the first time, and thereafter steps S201 → S202 → S206 → S.
When the loop of 207 → S211 is established, the occurrence of sudden deceleration is counted. In this way, the magnitude of the frequency of sudden deceleration can be used for the rapid deceleration determination.

In the following step S212, the timer is incremented each time this step is executed. Also in this process, in accordance with the count process of the sudden deceleration occurrence, the first time is the execution of this step S212 in the loop in the case of the above initialization, and thereafter, steps S201 → S202 → S
When the loop of 206 → S207 → S211 → S212 is established, the increment is sequentially executed in the corresponding loop. Further, in the above-mentioned processing after the timer is started, which involves switching the malfunction prevention flag to ON, since the time counting processing is started after the timer is started until the predetermined time is reached, even at a timing at which the occurrence of sudden deceleration is not detected in step S201. , Execute timer count. Therefore, as mentioned earlier, the answer is No in step S201, the malfunction prevention flag is ON, and the re-engagement flag is still OFF and has not been switched ON. In the state (accordingly, before shifting to L / U re-engagement control), that is, step S201 → step S20.
Even when the loop from 3 to S205 to S212 is established, the timer is incremented each time the step S212 is executed, and the timer count is continued in this manner.

Then, step S212 as described above is performed.
The timer is incremented, and if applicable, the rapid deceleration occurrence frequency is incremented in step S211, and in step S213, the timer value is compared with a predetermined malfunction prevention standby time for each execution of this step. Then, the termination judgment of the malfunction prevention standby control is performed. If the result of determination in step S212 is that the timer value has not reached the malfunction prevention standby time, the subsequent processes (steps S214 to S219) are skipped, and this subroutine is ended from step S212.
If the timer value has reached the preset malfunction prevention standby time while continuing the malfunction prevention standby control, at the time when such a judgment is obtained, the L / U release control is advanced and locked up. To determine whether to release the clutch completely, or to switch to control to stop it and re-engage it, determine again whether it is a sudden deceleration or not. If it is detected, the former mode is selected, and if the sudden deceleration is not detected, it is considered that the actual mode is not the rapid deceleration state but an erroneous detection, and the latter mode is adopted.

Here, the waiting time (waiting time from the first sudden deceleration detection to the reverification) provided for this purpose, that is, the waiting time for preventing malfunctions used for comparison in step S213 is the lock to be applied. The delay time can be set according to the delay time of the lockup system (release response delay time), and the time is set in advance to a wait time corresponding to such a delay time of the lockup system. Specifically, it is the time corresponding to the response delay of the lockup clutch operating hydraulic pressure in the automatic transmission that is going to adopt this control,
In step S201, the first sudden deceleration detection (whether it is due to an erroneous detection or an actual sudden deceleration state at this point) is made, and in step S202, a command is issued in the direction of L / U cancellation. After the release control is started, a waiting time is set so that necessary re-engagement can be performed at least before the lockup clutch is completely released.

In this way, when a sudden deceleration is detected, a command to immediately release the L / U is output (steps S201, S202), but the responsiveness of the L / U is taken into consideration, and after the command is output, Before the L / U is actually released,
The determination is performed again, and if the speed is not rapidly reduced, the re-engagement command can be output at an appropriate timing. If normal L
Even if it is canceled due to an erroneous judgment at the time of / U engagement, if the drive system is in the drive state, it is possible to easily re-engage. On the other hand, in particular, when it is premised on the intermediate capacity control (L / U capacity control for coasting) as described above, it is originally a control at the coast, so once it is released, once again, Since it is difficult to conclude,
The necessity of re-judging at the above timing is significant, and according to this example, even in this respect, it is possible to appropriately output the necessary re-engagement command, and as a countermeasure in case of false detection. It is possible to smoothly shift to the L / U re-engagement control.

In the present program example, the re-judgment when the malfunction prevention waiting time set as described above is reached is
In step S214, the rapid deceleration occurrence frequency obtained in the increment processing of step S211 is compared with a preset predetermined rapid deceleration determination frequency threshold value. In this case, the presence / absence of sudden deceleration can be sequentially verified during the waiting time from the first sudden deceleration detection to the reverification, and the rapid deceleration detection during reverification can be performed depending on the frequency of sudden deceleration occurring during that period. it can. When the sudden deceleration occurrence frequency exceeds the sudden deceleration determination frequency threshold value, it is considered that the sudden deceleration requiring the engine stall is actually occurring, and thus when it is determined that the sudden deceleration is in progress. , The malfunction prevention flag is turned off in step S215.
Then, in step S216, the rapid deceleration flag is turned on.

In step S214, when the sudden deceleration occurrence frequency> the sudden deceleration determination frequency threshold is satisfied immediately after the waiting time has elapsed, the steps S215 and S2 are performed at the above timing.
16 processes are selected once, and the malfunction prevention flag that was once set to ON is switched back to the original OFF, while the sudden deceleration flag used to indicate that the actual deceleration state is actually switched from OFF to ON. , This subroutine ends. In this case, after the next loop, after confirming that this is not a malfunction,
In order to avoid the engine stall, the L / U release control can be directly advanced and the lockup clutch can be completely released.

On the other hand, even if the timer value reaches the malfunction prevention standby time, if the frequency of sudden deceleration is low, it is considered that the deceleration is not rapid (for example, although the rapid deceleration was detected in step S201, The sudden deceleration occurrence detection is, for example, only one such transient, and after that, the steps S201 → S203 → S205 → S212 → are continuously performed.
If it is a case corresponding to the processing by the loop of S212, it is assumed that it is an erroneous detection that is not the actual sudden deceleration), and step S214 selects the step S217 side, cancels the release control, and engages the lockup clutch. Switch to L / U re-engagement control to increase capacity and re-engage.

In the present program example, the contents of the re-fastening control when it is detected that the deceleration is not sudden deceleration are step S2.
In step 17, the L / U control command value is set to a value corresponding to the vicinity of the valve switching point, and in step S218, the control command value increase rate is determined. Further, in step S219, the re-engagement flag is changed from OFF to ON. After switching, the present subroutine in the loop is completed.

In this case, the value given in step S217 is used as the initial value for re-fastening control, and the corresponding drive duty D is set, and step S13 in FIG.
When it is 1, it is output to the lockup solenoid 8. The control command value increase rate set in step S218 is applied to the process (command value update) in the gradual increase process of the control command value in step S220 described below after the start of the L / U re-engagement control.

In this way, the process proceeds to the re-engagement control, and after the next loop, the process is step S201 → S203 → S205.
In the step S205 of the re-engagement flag check process, the re-engagement flag is set to ON in step S219 in the previous loop, and as a result, the step S220 is selected and L
/ U Re-engagement control is executed.

Here, in step S220, after giving a relatively large command value as an initial value at the start of the L / U re-engagement control, the L / U control command value is gradually advanced in the course of the main re-engagement control. In order to return to the command value of (for example, the original value just before the first sudden deceleration detection that would have been applied if there was no false detection as in the previous example), this step Each time it is executed, the control command value increase rate preset in step S218 is used to reconnect the L / U control command value as the previous value (for example, the current loop If it is the first process after re-engagement control shift, the above-mentioned re-engagement initial value) is added with the control command value increase rate, and thus updated,
Let it be the current value of the L / U control command value for re-fastening. In this case, the drive duty D corresponding to the L / U control command current value obtained as described above is set in step S220, and is output to the lockup solenoid 8 in step S131 of FIG. The U re-engagement control will be executed (see the latter half of FIG. 5A)).

In the next step S221, however, during the L / U re-engagement control, the above step S220 is executed.
The L / U control command value that is sequentially updated in is monitored, and the L / U control command value for re-fastening is compared with the coast L / U control command value as the target command value to be restored. When the re-fastening L / U control command value is still smaller than the original value, control is executed in a loop of steps S205 → S220 → S221, and the present subroutine is ended as it is from step S221. As a result, the re-engagement control involving the above-mentioned command value gradual increase process is advanced and continued.

As a result of the comparison in step S221, if the L / U control command value is equal to or larger than the coast L / U control command value, the L / U re-engagement control is terminated at that time. In step S221, the previously touched side of steps S222 and S223 is once selected, and the present subroutine is terminated after step S204. That is, in step S222, the re-fastening flag is set to the original OFF state,
In step S223, the malfunction-prevention flag is turned off.
Then, in step S204, the sudden deceleration detection flag is turned off, and each control flag is returned. In the case where the re-engagement control is executed, the re-engagement control is thus completed, and the L / U capacity control for inertial running previously executed from the L / U re-engagement control is continued. It can be smoothly returned to.

According to the control of this embodiment, L / during coasting
While U control can be appropriately executed to improve fuel efficiency and avoid engine stall during sudden deceleration, and even if accuracy is improved for detection of sudden deceleration, erroneous detection due to disturbance, such as driving on a bad road or a highway, can be performed. It is also possible to improve the problem of deceleration that occurs when the wheels pass over steps such as when traveling. Even if the rapid deceleration detection applied to step S127 of FIG. 2 or step S201 of FIG. 3 is a means for detecting a rapid deceleration by obtaining a change in wheel speed, it can be used up sufficiently. It is possible to bring out the effect of the rapid deceleration detection effectively while achieving high accuracy and bring out the effect.

In FIGS. 5 and 6, the case where the wheel passes through the joint is taken as an example, and the L / U control including the re-engagement control according to the present embodiment and the L / U control when this control is not adopted are shown. U
It is a time waveform chart of various amounts at the time of overcoming a joint road showing respective states of control, and will be described below with reference to this also. The L / U system originally has an open response delay time, and even if the control command value is set to the maximum open side, as already seen, it does not immediately respond (see FIG. 7). In comparison, the fluctuation of the wheel speed that occurs when passing through a joint, for example, is expected to be a very short time phenomenon. Therefore, even when the method of performing the rapid deceleration detection by using the wheel speed change speed as shown in FIG. 5B is adopted, after the rapid deceleration is detected once as in the present embodiment (for example, the step (S201), after examining the presence / absence of sudden deceleration, after a waiting time corresponding to the delay time of the L / U system has passed (for example, step S21).
3) Perform the rapid deceleration test again (for example, step S2
14) If the frequency in the section is more than a predetermined number of times set in advance, L / U is canceled as it is, and if it is less than the predetermined number of times, the L / U capacity is increased again and re-engagement is attempted. Such problems can be solved well.

In the case of the comparative example of FIG. 6, the lock-up solenoid drive duty before and after passing over the joint road,
Changes in lockup differential pressure (lockup clutch engagement capacity) (Fig. (A)), changes in wheel speed change speed and vertical G (vertical acceleration), and sudden deceleration detection threshold value are shown (Fig. (B)). . In this example, when the vehicle crosses the joint road, an up and down G occurs, and then the wheel speed change speed largely changes and exceeds the threshold value. As a result, the shock over the joint road is detected as a sudden deceleration, the drive duty is commanded to the re-opening side, and the L / U release progresses.
L / U differential pressure is reversed and L / U is released.

As a result, in the case of L / U control during deceleration, when a sudden deceleration due to sudden braking is attempted to release L / U, a method of simply determining a change in wheel speed is introduced as a method for detecting the sudden deceleration. However, in this case, the L / U release was performed even though it should not have been released in the above case, and as a result, as described above, during actual steady deceleration operation. It can be seen that the fuel economy deteriorates and a feeling of strangeness occurs. Even if it is used together with the method of detecting the brake operation, it will still work during gentle braking, and it will not be possible to make a reliable distinction from sudden braking due to the true depression of the brake pedal. If there is an erroneous detection in the case of overcoming a joint road as described above, the situation such as the deterioration of fuel consumption as described above will still occur.

On the other hand, in the case of FIG.
As shown in contrast in the scene of overcoming the same joint road,
Even if the method of obtaining the change in wheel speed is used as the rapid deceleration detection method in order to avoid the occurrence of engine stall during sudden braking on a low μ road when the L / U during deceleration is reduced, It is also possible to avoid erroneous detection even if the wheel speed suddenly changes within a minute time due to such a disturbance, which is an effective means for avoiding this. That is, according to the present embodiment, basically, the deceleration is again compared, and the re-fastening command can be output if the deceleration is not the rapid deceleration. In the example of FIG. 5, the joint overpass shock is detected as the rapid deceleration. , After a command to release L / U is issued at that timing, after a preset time (waiting time) equivalent to the release response delay time of the L / U system has elapsed,
As a result of comparing the wheel speed change speed with the threshold value, it is determined that the speed is not suddenly decelerated, and thus the drive duty is commanded to the re-engagement side, and the L / U differential pressure increases in the middle without completely opening. And then re-fastened. Therefore, according to this, it can be seen that even in the same case, the erroneous detection which is not the sudden braking as in the case of FIG. 5 is surely avoided, and the problem caused by the erroneous detection can be prevented.

At this time, if the waiting time until the re-verification of the sudden deceleration is too short, the speed of the wheel speed change transiently decreases due to the rattling of the gear due to the deceleration of the sudden deceleration detection threshold. If there is a sudden deceleration, the engine will be re-engaged despite the sudden deceleration, and as a result, there is a high possibility that the engine stall cannot be avoided. On the other hand, the waiting time until re-verification of sudden deceleration is too long, and after the lock-up clutch is completely released, a force that prevents the lock-up clutch from engaging during deceleration acts, making re-engagement impossible. Fuel consumption and drivability are impaired. Therefore, when introducing and applying this control to the lock-up control device of the automatic transmission,
How to set the waiting time is an important matter, but it is possible to reliably identify the fluctuation of the wheel speed due to joints and the actual sudden deceleration due to the sudden braking, and also the lockup clutch is completely released. It has already been stated that it is optimal to set this waiting time so that re-engagement can be performed before it is done, and therefore it is optimal to set the timing of re-judging. This embodiment is characterized by the control.

Further, if it is not a sudden deceleration in practice, for example, such a fluctuation of the wheel speed is made to such an extent that the frequency of the sudden deceleration detection exceeds a preset determination frequency within such a set time. If it continues for a short time, it will be released as a result, but in rough terrain where such a situation is caused, even if L / U
Even if the engine is released, there are less problems than the case where the L / U is suddenly released and the engine speed suddenly changes despite the driver not expecting a change before and after the joint. I can say.

Further, as a countermeasure against such a case, for example, when re-fastening occurs a predetermined number of times or more within a predetermined time, the L / U during deceleration is prohibited for a predetermined time or until the next deceleration L / U opportunity. It is also effective to add such processing to the control program (FIGS. 2 to 4) of this embodiment. That is, if the frequency increases abnormally,
This can be solved by prohibiting the L / U during deceleration until the next L / U opportunity during deceleration, and it is more effective if such a means is added.

Further, in addition to the main control in the case of using the rapid deceleration detection based on the change in the wheel speed, the brake switch signal B (for example,
(See FIG. 7), the method of detecting the start of braking and the method of detecting the start of braking may be used in combination, and the rapid deceleration may be detected by each logical sum. In this case, the distinction between erroneous detection and sudden deceleration due to sudden braking accompanying the actual depression of the brake pedal becomes more reliable. Therefore, as described above, it was also used in combination with the method for temporarily detecting the brake operation. Even if it is the case, it cannot be a complete solution, and the
A situation such as a malfunction that should not be released from U can be reliably prevented, and unnecessary release of L / U can be avoided.

Furthermore, in this embodiment, as described above,
Also, as shown in FIG. 5A together with the waveform change during the re-fastening process, in the re-fastening control, a relatively large initial value is first set as the re-fastening command value, and then gradually increased. Method (steps S217, S218, S)
220, S221) is also adopted, and in this case, it is also effective against a shock or the like at the time of re-fastening. In other words, regarding the shock at the time of re-engagement, a re-engagement method that first gradually raises up to a control command value that returns the valve that was once switched to the open side to the engaged side, and then gradually engages If you take it, you can also reduce shock,
At the same time, it is possible to reduce the time required for re-fastening and reduce the shock of re-fastening. In addition, the shock for re-fastening can be expected to have a large allowable range for the driver only immediately after the joint overstep shock. Therefore, it can be said that it is not a problem unless it is extremely large.

When setting the waiting time until the re-verification of sudden deceleration, that is, the timing for re-judgment, in consideration of the responsiveness of L / U, when the L / U response is performed, the coasting L When the / U capacity control is the intermediate capacity control as described above, it may be variably set in accordance with the lockup lockup clutch engagement capacity immediately before the L / U release command instant. FIG. 9 shows an example in which the response delay of the L / U release changes according to the engagement capacity of the lockup clutch. In the example of FIG. 10, L /
As the lock-up clutch engagement capacity immediately before the U release command instant t ₁ decreases from the solid line to the dotted line and from the dotted line to the alternate long and short dash line, the lock-up release pressure P _R and the lock-up that show a change with time on the same corresponding line. Response delay ΔT ₁ , ΔT until L / U release, which is completed instantly when the engagement pressure P _A intersects
₂ and ΔT ₃ become smaller.

Therefore, in consideration of such dependency of the change tendency of the response delay, for example, in step S213 of FIG. 3, the malfunction prevention standby time which is the comparison value with the timer value is changed, and L / L is actually changed. Before U is released, it is possible to make a re-judgment and, if applicable, shift to re-engagement control.
Set the waiting time so that it is neither too short nor too long, and depending on the lockup lockup clutch engagement capacity that was taken in the previous intermediate capacity control, if the engagement capacity is small, the timing for rapid deceleration reverification is set. It is more effective to change the timing earlier, such as delaying the timing if the engagement capacity is large. When considering the responsiveness of the L / U system, the present invention may be implemented with such change control taken into consideration. In particular, it is effective when the present invention is carried out in combination with the lockup control of the application by the present applicant.

[0069]

According to the present invention, in a vehicle equipped with an automatic transmission having a torque converter in its transmission system that can be locked up by a lockup clutch, the vehicle is suddenly decelerated when the vehicle is in a coasting state. When the lockup clutch is released, the lockup clutch release control is immediately started, but in consideration of the responsiveness of the lockup system, a predetermined time set according to the delay time is waited for, and the rapid deceleration test is performed again. If a sudden deceleration is detected, the lockup clutch release control is not stopped, and it is possible to completely release the lockup clutch by the control as it is, while a sudden deceleration is not detected during the reverification. The lock-up clutch release control can be stopped and the re-engagement control can be performed.

Therefore, it is possible to prevent an erroneous operation such as the lockup being released due to an erroneous detection that is not based on sudden braking on a low μ road, and to make an appropriate sudden deceleration determination. Also, the waiting time until the re-verification of the sudden deceleration after the lapse of a predetermined time for that is the state in which the lockup clutch release control should be advanced and completed to avoid the engine stall during the sudden deceleration due to the actual sudden braking. Or the timing of selecting whether to switch to the re-engagement control side to return to the original lockup control in the original coasting state because of false detection, the lockup system The release response delay time can be set in consideration, so that re-judgment can be performed at such timing, and either of them can be selected before the lockup is actually released. Even in the lock-up control in the coasting state, it is possible to perform the necessary re-engagement even in the lock-up control in the coasting state, preventing malfunction and improving fuel economy and suddenly. Both the avoidance of engine stall during deceleration can be highly achieved.

In this case, preferably, the mode of the lockup control in the case where the speed is not rapidly decelerated during the coasting state is such that the engagement capacity of the lockup clutch is the most within the range where relative rotation does not occur between the input and output elements of the torque converter. With the lock-up capacity control that controls to a small engagement capacity, it can be smoothly returned to this at the time of re-engagement, and it is possible to achieve compatibility with the lock-up control by the previous applicant, and the present invention is implemented in that way. You can also do it.

As described above, based on the re-verification of the sudden deceleration after the predetermined time, if any of them corresponds, the control of the engine stall avoidance or the re-engagement is performed, and the change of the wheel speed is used for the sudden deceleration detection. The present invention can be suitably implemented by constructing as claimed in claim 2. In this case, in addition to the above, even if the method of detecting the rapid deceleration by detecting the change speed of the wheel speed is applied as the rapid deceleration detection, the wheels can get over the step when driving on a bad road or running on a highway. It is an effective solution to the deceleration that sometimes occurs, and it is also possible to avoid malfunctions when the wheel speed suddenly changes within a minute time due to external disturbances and causes false detection. The sudden deceleration based on the sudden braking of the vehicle can be identified with certainty to improve the accuracy, and the necessary re-engagement can be performed before the lock-up clutch is completely released. It is possible to achieve a high level of balance with engine stall avoidance.

In the case of claim 3, in addition to the above,
Perform more rapid deceleration detection, detect sudden deceleration once, and then sequentially examine whether or not there is a sudden deceleration.After a predetermined waiting time, perform a rapid deceleration test again and check the frequency during that period. If it is more than the frequency of sudden deceleration occurrence, the lockup is released as it is, and if it is less than that, the engagement capacity of the lockup clutch is increased again and reengagement can be achieved. It is possible to further improve the discriminating ability from non-defective ones and to respond to the case where extremely high precision is required, and to realize more detailed and effective control. Further, preferably, the present invention can be implemented by being configured as described in claim 4. In this case, in addition to the above, for example, it becomes effective as a control on an uneven terrain where wheel speed fluctuations continue for a short time. In the case where false detections increase due to abnormalities that will be released,
It is possible to cope with this by adding such prohibition control, and it is more effective. Further, the present invention can be implemented with the structure as set forth in claim 5, and in this case, by such combined use, erroneous detection, for example, in passage of joints or the like in a state where the brake pedal is not depressed, or in a bad road traveling situation. Can be reliably eliminated, and even when braking by pedaling the brake pedal, it is possible to eliminate malfunctions during slow braking that is not sudden deceleration. The combined use is even more effective.

Further, the present invention can be implemented with the constitution as claimed in claim 6, and in this case, in addition to the above, it becomes effective as a control against a shock or the like at the time of re-fastening, and is once switched to the open side. If a re-engagement mode is adopted in which the control command value to the extent that the valve that has been closed is returned to the engagement side is first raised at a stroke, and then gradually re-engaged, it is possible to shorten the time until re-engagement and reduce the re-engagement shock. Will also be possible.

[Brief description of drawings]

FIG. 1 is a system diagram showing an embodiment of a lockup control device for an automatic transmission according to the present invention.

FIG. 2 is a flowchart of an example of a main routine showing lockup control performed by the transmission controller in the same example.

FIG. 3 is an example of a control program that can be applied in combination with the processing of the main routine to execute sudden deceleration detection, determination of rapid re-deceleration after a predetermined time, setting of lock-up control command values including lock-up re-engagement, and the like. It is a figure which shows the flowchart of, and shows a part thereof.

FIG. 4 is a diagram showing another part of the same.

FIG. 5 is a diagram for explaining an example of the content of lock-up control including re-engagement, which is shown as an example when a vehicle crosses a joint road.

FIG. 6 is an explanatory diagram of various amounts when a vehicle crosses over a similar joint in a comparative example shown in comparison with FIG.

FIG. 7 is a time chart for explaining an example of basic control contents during coasting.

FIG. 8 is a region diagram illustrating a lockup region of the automatic transmission.

FIG. 9 is a diagram showing an example of a relationship between a lockup clutch engagement capacity and a response delay of lockup release.

FIG. 10 is an operation time chart showing an example of the relationship between the lockup clutch engagement capacity and the lockup release response delay.

[Explanation of symbols]

 1 Engine 2 Automatic Transmission (A / T) 3 Torque Converter 5 Control Valve 6 Shift Solenoid 7 Shift Solenoid 8 Lockup (L / U) Solenoid 9 Controller 10 Throttle Opening Sensor 11 Engine Rotation Sensor 12 Turbine Rotation Sensor 13 Transmission Output rotation sensor 14 Oil temperature sensor 15 Brake switch 21 Wheel speed sensor

Claims (6)

[Claims] 1. An automatic transmission having a transmission system that includes a torque converter that can be brought into a lockup state in which input / output elements are directly connected by a lockup clutch, and means for determining whether or not a motion state of a vehicle is a coasting state. Means for detecting sudden deceleration of the vehicle, and means for controlling to release the lock-up clutch when sudden deceleration is detected after detecting that the motion state of the vehicle is coasting by these means. So, after the lockup clutch release control is started,
When the predetermined time set according to the delay time of the lockup system has elapsed, the rapid deceleration is verified again. In that case, if the rapid deceleration is not detected, the lockup clutch release control is stopped. A lockup control device for an automatic transmission, comprising: lockup control means including means for performing control for re-engagement. 2. The means for detecting a sudden deceleration of the vehicle includes a means for detecting a sudden deceleration by a change speed of a wheel speed or a change of a physical quantity similar thereto, and the predetermined time is a response delay of a lockup clutch operating hydraulic pressure. If the lockup control means detects a sudden deceleration of the wheel speed or a rapid deceleration due to a change in a physical quantity similar to the above, the lockup control unit locks up the lockup. While controlling to start the clutch release control, when a time corresponding to the response delay of the lockup clutch operating hydraulic pressure has elapsed, a change in the wheel speed or a change in a physical quantity similar thereto is verified again. The lockup control device for an automatic transmission according to claim 1, wherein. 3. The presence / absence of sudden deceleration is sequentially verified during the waiting time from the first sudden deceleration detection to the reverification, and the rapid deceleration detection at the reverification is performed according to the magnitude of the sudden deceleration occurrence during that time. The lockup control device for an automatic transmission according to claim 1 or 2, wherein the lockup control device is configured. 4. When the re-fastening occurs a predetermined number of times or more within a preset time, the lockup during deceleration is prohibited for a predetermined time after that or until the next lockup opportunity during deceleration. Claim 1, Claim 2, or Claim 3 characterized by
A lock-up control device for the automatic transmission described. 5. The lockup control device for an automatic transmission according to claim 1, 2, 3, or 4, further comprising a device for detecting the start of braking from the actuation of the brake. The rapid deceleration detection is used together with the device, and the rapid deceleration detection is performed by a logical product based on the respective detections. 6. The lock-up control means raises the lock-up control command value up to a control command value at which valve switching operation occurs at the time of re-fastening, and then the control command originally set during deceleration. The automatic transmission according to claim 1, claim 2, claim 3, claim 4, or claim 5, further comprising means for performing re-engagement control so as to gradually return to a value. Lockup controller.