JPH0880766A - Lockup control device for automatic transmission - Google Patents

Abstract

PURPOSE: To improve the fuel consumption by expanding the lockup region to the operation region of the coast state in a lockup control device for an automatic transmission having an engine output control actuator capable of optionally controlling the engine output via the control command from the outside. CONSTITUTION: This lockup control device for an automatic transmission is provided with a lockup engine output integration control means (j) outputting the lockup command fastening a lockup clutch (c) to a lockup control actuator (e) when a vehicle is judged to be in the lockup operation region while a foot is removed from an accelerator and outputting the command to keep the detected speed ratio less than 1 at least during the time required for the precharge control of lockup fastening to an engine output control actuator (f).

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 having an engine output control actuator capable of arbitrarily controlling an engine output according to a control command from the outside.

[0002]

2. Description of the Related Art In a lockup mechanism, the engine side of a lockup clutch (hereinafter, L / U clutch) is integrated with a converter cover and is connected to the engine side through a flywheel, and the L / U clutch is also connected. Let us consider an example in which the turbine side is a lock-up piston (hereinafter, L / U piston) slidably connected to the turbine hub, and its back surface receives a pressure from the torque converter oil chamber.

When the L / U piston is rotating, centrifugal hydraulic pressure is applied thereto. In the drive state where the torque is transmitted from the engine side to the turbine side, the rotation of the L / U clutch on the engine side is faster than the rotation on the turbine side,
Therefore, the action of increasing the pressure on the outer circumference of the piston due to centrifugal force is
The engine side works stronger than the turbine side. However, since the outer peripheral side of the L / U clutch serves as a hydraulic fluid flow path, the outer peripheral pressure of the L / U piston is equal on the engine side and the turbine side. Therefore, as shown in FIG. 19, the pressure on the inner peripheral side of the L / U piston is larger on the engine side where the increasing action of the centrifugal force of the piston outer peripheral end is larger, that is, between the L / U clutches, on the turbine side.
That is, it becomes lower than the back pressure of the L / U piston. Therefore, the inner peripheral portion of the L / U piston is pushed from the turbine side to the engine side, and the L / U clutch receives a force to engage it.

On the contrary, in the coast state where torque is transmitted from the turbine side to the engine side, the rotation of the L / U clutch on the turbine side is faster than the rotation of the engine side. Therefore,
As shown in FIG. 20, a phenomenon completely opposite to the drive state occurs, and the L / U piston inner peripheral portion is pushed from the engine side to the turbine side, and the L / U clutch tries to release it. Power will work.

Due to the action of such centrifugal force, the L / U clutch is provided even when the lockup pressure is maximized when the vehicle is coasting and the speed ratio, which is the ratio of the turbine speed to the engine speed, exceeds a certain value. There may be a situation where the is no longer fastened. Alternatively, even if the clutch is engaged, first, an excessive L / U clutch pressure is required as compared with the lock-up engagement capacity required to bring the L / U clutch closer, and the L / U clutch approaches and the above L / U clutch is approached.
Immediately after the hydraulic oil flow passage on the outer periphery of the U-clutch is cut off, the L / U clutch may be rapidly engaged, and the drivability may be impaired. Therefore, it is necessary to limit the range in which the lock-up engagement control is performed during the coast, and it has not been possible to perform the coast lock-up having a large fuel consumption improving effect in a wide range.

For example, as shown in FIG. 21, after the throttle is closed, the fuel injection amount is minimized by fail cut. For this reason, the engine speed decreases sharply compared to the turbine speed, the speed ratio immediately becomes greater than 1, and when the time required up to this point is not long enough for the lockup precharge control, It is difficult to lock up at this point. Therefore, lock-up control must be prohibited. After that, when the engine speed falls below a predetermined value, the fuel injection amount is returned to an appropriate value by fail cut recovery, and the engine speed stabilizes.

In order to prevent this, JP-A-61-118
Japanese Patent No. 4268 describes that "lock-up is performed when the input and output shafts of the torque converter are rotated equally."

[0008]

However, in the lockup control device for the conventional automatic transmission described above, there is actually a control dead time due to the piston volume in the lockup control system, and the lockup command value is Even if the value is set such that the L / U clutch is sufficiently engaged, in the situation where the L / U clutch is completely disengaged, engagement will be delayed by the control dead time described above before being engaged. . If the engine control side is fail-cutting during this period, the speed ratio changes remarkably rapidly, and the L / U control command value is raised by the control dead time, that is, so-called precharge control is not completed and lockup occurs. It enters the speed ratio area where it is impossible to do.

Therefore, as described in the embodiment of Japanese Patent Laid-Open No. 61-102341, a method of delaying the start of the fail cut by the operation delay of the hydraulic system can be considered. However, with a simple fail-cut delay, if the precharge control ends before the speed ratio reaches a predetermined value and lockup becomes impossible, or conversely, before the precharge control ends due to variations or the like. It is possible that the fail cut will start. In the former case, although fuel cut may be originally started, fuel consumption may be impaired because fuel is continuously blown. In the latter case, it is out of the question because lock-up is not possible after all.

Incidentally, Japanese Patent Laid-Open No. 60-35147 discloses that
It has been proposed to increase the engine output by controlling the idle speed control valve in the opening direction when the accelerator pedal is released during lockup, but the purpose is to prevent shock during deceleration from lockup travel. The problem to be solved and the object are completely different from the present invention.

The present invention has been made in view of the above problems. A first object of the present invention is to provide an automatic transmission having an engine output control actuator capable of arbitrarily controlling an engine output by a control command from the outside. In the lockup control device, it is intended to improve fuel efficiency by expanding the lockup region to the operating region in which the coast state is established.

A second object is to further improve fuel efficiency by expanding the lock-up area and the fail-cut area when the accelerator is released.

A third object is to achieve the first object by a smooth lock-up engagement and a high degree of freedom in controlling the speed ratio on the engine side.

[0014]

In order to achieve the first object, in the lock-up control device for an automatic transmission according to the first aspect of the invention, as shown in the claim correspondence diagram of FIG. 1, the input side thereof is the engine a. A fluid transmission joint d having an output side connected to the speed change mechanism b and having a lock-up clutch c capable of directly connecting input and output for transmitting power via fluid, and a control command from the outside provided on the lock-up clutch c. A lock-up control actuator e capable of arbitrarily controlling the clutch engagement / disengagement by means of the engine, an engine output control actuator f provided in the engine a and capable of arbitrarily controlling the engine output by a control command from the outside, and an accelerator for detecting an accelerator operation Operation detection means g and lockup operation area determination for determining whether the vehicle operating state is in the lockup operation area The stage h, a speed ratio detecting means i for detecting a speed ratio or a value corresponding to the speed ratio which is a ratio of the input rotation and the output rotation of the fluid transmission joint d, and a lock-up operation region at the time of accelerator release operation. When it is determined that the lockup clutch c is engaged, a lockup command for engaging the lockup clutch c is output to the lockup control actuator e, and at least the time required for precharge control for lockup engagement is set to 1 for the detected speed ratio. The engine output control actuator f
Lockup engine output integrated control means j for outputting to
And are provided.

In order to achieve the second object, the lockup control device for an automatic transmission according to the second invention is the lockup control device for an automatic transmission according to claim 1, wherein the engine output control actuator f is The lock-up control actuator e is a means for controlling the engine output by fail-cut when the accelerator is released.
As a means to perform precharge control only for the time set in the initial stage of lock-up engagement, assuming that the fail cut has started at a certain time after the accelerator foot release operation, the speed ratio is 1
A first predetermined speed ratio arrival time predicting means for predicting an elapsed time until reaching a predetermined value close to 1 and a first remaining pre-calculation for calculating a remaining time of pre-charge control based on a pre-charge control set time and a certain time. A charge time calculating means is provided, and the lockup / engine output integrated control means j
When the accelerator release operation is performed and it is determined to be in the lock-up operation region, the pre-charge control command is output to the lock-up control actuator e until the set time, and the predetermined speed ratio arrival time remains for the pre-charge. The speed ratio is controlled so that the fail cut is prohibited and the speed ratio is maintained at less than 1 until the time becomes larger than the time.
It is characterized in that it is a means for performing fail-cut control after the arrival of the time.

In order to achieve the third object, the lockup control device for an automatic transmission according to a third aspect of the invention is the lockup control device for an automatic transmission according to claim 1, wherein the engine output control actuator f is As a means for controlling the engine output by increasing / decreasing the intake air amount to the engine a, the lock-up control actuator e as a means for performing pre-charge control only for the time set in the initial stage of lock-up engagement, and at the time of accelerator release operation, The intake air amount is increased according to the accelerator operation to maintain the intake air amount at a predetermined value, and it is assumed that the intake air amount starts decreasing at a certain time, and the speed ratio reaches a predetermined value close to 1 when the speed ratio is less than 1. Predetermined speed ratio arrival time prediction means for predicting the elapsed time up to, and precharge control at a certain time assuming that the reduction of the intake air amount has started A second remaining precharge time calculating means for calculating the remaining time is provided, and when the lockup / engine integrated control means is determined to be in the lockup operation area when the accelerator pedal is released, until the set time. A precharge control command is output to the lock-up control actuator e, and the intake air amount is kept at a predetermined value until the intake air amount decrease start assumption time at which the predetermined speed ratio arrival time becomes longer than the remaining precharge time is reached. It is characterized in that the speed ratio control for maintaining the ratio to less than 1 is performed, and after the time arrives, the intake air amount is reduced.

[0017]

The operation of the first invention will be described.

When the accelerator release detecting operation is detected by the accelerator operation detecting means g and the vehicle operating state is judged by the lockup operating area determining means h to be the lockup operating area, the lockup / engine output integrated control is performed. In the means j, a lockup command for engaging the lockup clutch c is output to the lockup control actuator e.

On the other hand, when the accelerator release detecting operation is detected by the accelerator operation detecting means g and the vehicle operating condition is determined to be in the lockup operating area by the lockup operating area determining means h, the lockup engine output is output. The integrated control means j outputs a command to the engine output control actuator f to maintain the speed ratio detected by the speed ratio detection means i at less than 1 for at least the time required for the precharge control for lock-up engagement.

Therefore, in the lockup independent control, when the accelerator pedal is released, the fluid transmission joint d is in a state of transmitting torque through the fluid, so that the turbine rotational speed is gradually decreased, while the engine rotational speed is decreased. Drops sharply,
Although the drive state may change to the coast state before the lockup clutch c is engaged, the speed ratio is maintained at less than 1 for at least the time required for the precharge control for the lockup engagement by the engine output control, that is, The drive state is maintained for at least the time until the hydraulic oil flow path on the outer peripheral side of the lockup clutch c is cut off, so that there is no problem that the lockup clutch c becomes difficult to engage due to the action of centrifugal hydraulic pressure. The lock-up engagement is achieved reliably with good response, and the engine a and the speed change mechanism b are directly connected via the lock-up clutch c.

The operation of the second invention will be described.

When the accelerator release detecting operation is detected by the accelerator operation detecting means g and the vehicle operating state is determined by the lockup operating area determining means h to be the lockup operating area, the lockup / engine output integrated control is performed. In the means j, the precharge control command is output to the lockup control actuator e until the set time.

On the other hand, when the accelerator operation detecting means g detects an accelerator release operation and the lockup operating area determining means h determines that the vehicle operating state is in the lockup operating area, the lockup engine output In the integrated control means j, until the time at which the predetermined speed ratio arrival time predicted by the first predetermined speed ratio arrival time prediction means becomes larger than the remaining precharge time calculated by the first remaining precharge time calculation means is reached. Speed ratio control is performed to prohibit the fail cut and maintain the speed ratio below 1, and after that time, fail cut control is performed.

Therefore, until the fail cut start assumed time is reached, that is, until the precharge control for lock-up engagement is completed, the fail cut is prohibited and the speed ratio is maintained at a predetermined value range of less than 1 and close to 1. The speed ratio control is performed, and as in the first aspect of the invention, the lock-up engagement is reliably achieved with good response.

After the fail cut start assumed time is reached, the fail cut control is executed, but at this time, the lock-up engaging operation is already in progress, and the complete lock-up state is started immediately after the start of the fail cut control. Therefore, the change in the speed ratio becomes a change with the upper limit being 1, and as a result, the decrease in the engine speed becomes gradual along with the decrease in the turbine speed, and the decrease to a certain engine speed is recovered as a recovery condition. The fail cut control can be maintained for a long time.

The operation of the third invention will be described.

When the accelerator release detecting operation is detected by the accelerator operation detecting means g and the vehicle operating state is determined by the lockup operating area determining means h to be the lockup operating area, the lockup / engine output integrated control is performed. In the means j, the precharge control command is output to the lockup control actuator e until the set time.

On the other hand, when the accelerator release detecting operation g detects the accelerator release operation and the lockup operation area determining means h determines that the vehicle operating state is in the lockup operation area, the lockup engine output In the integrated control means j, at the assumed intake air amount reduction start time at which the predetermined speed ratio arrival time predicted by the second predetermined speed ratio arrival time prediction means becomes larger than the remaining precharge time calculated by the second remaining precharge time calculation means. Until reaching, the speed ratio control is performed to keep the intake air amount at a predetermined value and the speed ratio is kept less than 1, and after that time, the intake air amount is controlled to decrease.

Therefore, the intake air amount is kept at a predetermined value and the speed ratio is less than 1 and close to 1 until the assumed intake air amount reduction start time is reached, that is, until the precharge control for lock-up engagement is completed. The speed ratio control that maintains the value range is performed, and as in the first aspect of the invention, the lockup engagement is reliably achieved with good response.

After reaching the assumed fail-cut start time, the intake air amount reduction control is performed. At this time, the lock-up engagement operation is already in progress,
The speed ratio gradually increases with the upper limit being 1 as the intake air amount decreases. Then, by engaging the clutch at a speed ratio close to 1, smooth lock-up engagement without shock is achieved.

In addition, in the case of the engine output control by the intake air amount, it is not the on / off control like the fail cut but the control that can continuously change the intake air amount. The degree of freedom in controlling the speed ratio is high such that the speed ratio control can be performed so that the speed ratio matches the target speed ratio.

[0032]

According to the first invention of claim 1,
In a lockup control device for an automatic transmission having an engine output control actuator capable of arbitrarily controlling an engine output by a control command from the outside, when the accelerator pedal is released, it is determined that the lockup operation range is set.
The engine output control actuator is instructed to output a lockup command for engaging the lockup clutch to the lockup control actuator and to maintain the detected speed ratio at less than 1 for at least the time required for precharge control of lockup engagement. Since it is a device equipped with a lockup engine output integrated control means for outputting,
The fuel efficiency can be improved by expanding the lockup region to the driving region in the coast state.

According to a second aspect of the present invention, in the lockup control device for an automatic transmission according to the first aspect, the lockup / engine output integrated control means is locked when the accelerator is released. When it is determined to be in the up operation range, the precharge control command is output to the lockup control actuator until the set time, and the fail cut is performed until the time when the predetermined speed ratio arrival time becomes longer than the remaining precharge time is reached. By prohibiting speed ratio control to keep the speed ratio below 1, and performing fail cut control after that time is reached, fuel consumption is further increased by expanding the lock-up area and fail cut area during accelerator release operation. The effect that it can improve is acquired.

According to a third aspect of the present invention, in the lockup control device for the automatic transmission according to the first aspect, the lockup / engine integrated control means is locked up during the accelerator release operation. When it is judged that it is in the operating region, the precharge control command is output to the lockup control actuator until the set time, and the intake air amount decrease start assumed time at which the predetermined speed ratio arrival time is longer than the remaining precharge time is reached. Until the time is reached, the speed ratio control is performed to keep the intake air amount at a predetermined value and the speed ratio is kept below 1, and after that time, the intake air amount is reduced. The effect of the first invention can be achieved by the high degree of freedom in controlling the speed ratio.

[Brief description of drawings]

FIG. 1 is a claim correspondence diagram showing a lock-up control device for an automatic transmission according to the present invention.

FIG. 2 is an overall system diagram showing a lockup control device for an automatic transmission according to a first embodiment.

FIG. 3 is a flowchart showing a flow of a lockup control operation and a fail cut control operation when the accelerator is off, which is performed in the first embodiment device.

FIG. 4 is a time chart showing the lock-up engagement operation when the accelerator is off in the device of the first embodiment.

FIG. 5 is a flowchart showing a flow of a lockup control operation and a fail cut control operation when the accelerator is off, which is performed in the device of the second embodiment.

FIG. 6 is a time chart showing the lock-up engagement operation when the accelerator is off in the device of the second embodiment.

FIG. 7 is a flowchart showing each embodiment of an engine side control routine.

FIG. 8 is a flowchart showing each embodiment of an engine side control routine.

FIG. 9 is a flowchart showing each embodiment of an engine side control routine.

FIG. 10 is a control block and a flow chart showing each embodiment of speed ratio control in the flowchart of the engine side control routine.

FIG. 11 is a flowchart showing each embodiment of speed ratio control in the flowchart of the engine side control routine.

FIG. 12 is a control block and characteristic diagram showing each embodiment of the speed ratio control in the flowchart of the engine side control routine.

FIG. 13 is a flowchart showing each embodiment of a lockup control routine.

FIG. 14 is a flowchart showing an example of a lockup control routine and a diagram showing an example of precharge control.

FIG. 15 is a flowchart showing an example of a precharge control routine of a lockup control routine and an embodiment of a lockup control routine.

FIG. 16 is a flowchart of lockup control and failcut control using a precharge control end signal.

FIG. 17 is a diagram showing an example of a case where lock-up control and fail-cut control are executed by independent control units.

FIG. 18 is a diagram showing an example of a case where lock-up control and fail-cut control are executed by a common control unit.

FIG. 19 is a diagram showing a centrifugal hydraulic pressure characteristic that acts on the lock-up clutch when the lock-up is released during driving.

FIG. 20 is a diagram showing a centrifugal hydraulic pressure characteristic that acts on the lockup clutch when releasing the lockup during coasting.

FIG. 21 is a time chart showing engine / turbine rotation speed characteristics, speed ratio characteristics, throttle opening characteristics, and fuel injection quantity characteristics when the accelerator is off in the lockup control device for a conventional automatic transmission.

[Explanation of symbols]

 a engine b speed change mechanism c lock-up clutch d fluid transmission joint e lock-up control actuator f engine output control actuator g accelerator operation detecting means h lock-up operation region determining means i speed ratio detecting means j lock-up / engine output integrated control means

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Shinsuke Higashikura 2 Takaracho, Kanagawa-ku, Yokohama, Kanagawa Nissan Motor Co., Ltd.

Claims (3)

[Claims] 1. A fluid transmission joint, the input side of which is connected to the engine and the output side of which is connected to a speed change mechanism, and which has a lock-up clutch capable of directly connecting between input and output for transmitting power via fluid, and the lock-up clutch. , A lock-up control actuator that can arbitrarily control clutch engagement / disengagement by an external control command, an engine output control actuator that is provided in the engine and that can arbitrarily control the engine output by an external control command, and an accelerator operation Accelerator operation detecting means for detecting, lockup operating area determining means for determining whether the vehicle operating state is in the lockup operating area, and a speed ratio or a speed ratio which is a ratio of the input rotation and the output rotation of the fluid transmission coupling. A speed ratio detecting means for detecting a corresponding value, and a lock at the time of accelerator release operation. When it is determined that the lockup clutch is in the lockup operation range, a lockup command for engaging the lockup clutch is output to the lockup control actuator, and at least the time required for precharge control for lockup engagement is detected. 1
A lock-up control device for an automatic transmission, comprising: lock-up / engine output integrated control means for outputting a command to keep the output of the engine output control actuator at a lower level. 2. The lockup control device for an automatic transmission according to claim 1, wherein the engine output control actuator is means for controlling an engine output by fail cut during an accelerator release operation, and the lockup control actuator is As a means to perform precharge control only for the time set in the initial stage of lock-up engagement, assuming that fail cut has started at a certain time after releasing the accelerator pedal, the speed ratio reaches a predetermined value close to 1 when it is less than 1. A first predetermined speed ratio arrival time predicting means for predicting an elapsed time up to and a first remaining precharge time calculating means for calculating a remaining time of precharge control according to a precharge control set time and a certain time. The lock-up operation range of the up / engine output integrated control means when the accelerator is released. When it is determined that, until the setting time outputs the precharge control command to said lock-up control actuator,
A means for performing a fail-cut control after performing fail-ratio until the time when the arrival time of the predetermined speed ratio becomes longer than the remaining precharge time is reached, and performing the speed ratio control for maintaining the speed ratio below 1; A lock-up control device for an automatic transmission characterized by the above. 3. The lockup control device for an automatic transmission according to claim 1, wherein the engine output control actuator is means for controlling an engine output by increasing or decreasing an intake air amount to the engine, and the lockup control actuator is , It is a means to perform precharge control only for the time set in the initial stage of lock-up engagement, and when the accelerator pedal is released, the intake air amount is increased according to the accelerator operation to keep the intake air amount at a predetermined value, and the intake is performed at a certain time. Assuming that the air volume has started to decrease, the speed ratio is 1
A predetermined speed ratio arrival time predicting means for predicting an elapsed time until reaching a predetermined value close to 1 and a remaining time of precharge control at a certain time assuming that the reduction of the intake air amount is started. A second remaining precharge time calculation means is provided, and when the lockup / engine integrated control means is determined to be in the lockup operation area at the time of accelerator release operation, a precharge control command is issued until the set time. The speed ratio is kept below 1 by keeping the intake air amount at a predetermined value while outputting to the lock-up control actuator and until reaching the assumed intake air amount decrease start time at which the predetermined speed ratio arrival time becomes longer than the remaining precharge time. Lockup of the automatic transmission, characterized in that the speed ratio control is performed and the intake air amount is reduced after the time is reached. Control device.