JP2719652B2 - Lock-up control for automatic transmission - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[Industrial applications]

The present invention relates to a lock-up control device for an automatic transmission configured to release a lock-up clutch in a torque converter during a gear shift.

[Prior art]

An automatic transmission including a gear transmission mechanism and configured to selectively switch an engagement state of a friction engagement device by operating a hydraulic control device to achieve one of a plurality of shift speeds is provided. It is already widely known. Such an automatic transmission is provided with a torque converter and uses its damper function and torque increasing function in order to reduce a shock at the time of shifting. In recent years, in order to reduce the power loss in the torque converter, an automatic transmission having a mechanically directly connected lock-up clutch on the input / output side of the torque converter has become widespread. In an automatic transmission equipped with such a lockup clutch, the lockup at each shift speed (second speed to fourth speed in the illustrated example) is performed based on a lockup diagram as shown in FIG. The engagement and disengagement of the clutch is performed. By the way, when the gearshift is performed from the state where the lockup clutch is engaged, the damper function as the torque converter cannot be used as it is, so that the lockup clutch is temporarily released in association with the gearshift. Preferably, such control is performed. From this point of view, Japanese Patent Application Laid-Open No. 58-30558 discloses a timer counting from the output time point of the shift signal in order to relate the timing of release and re-engagement of the lock-up clutch to the shift processing. The technology employed is disclosed.

[Problems to be solved by the invention]

For example, in an automatic transmission employing a shift diagram as shown in FIG. 5, when traveling at a vehicle speed V ₁ and a throttle opening (corresponding to an access opening) θ ₁ , _one wants acceleration. If the Surotsutoru opening was transferred to theta _2, for crossing the downshift line from the fourth speed stage of the diagram the shift line to the third speed stage, the automatic transmission is the fourth speed (over driver stage) The downshift to the third gear will be performed. However, at this time, if the lock-up clutch is re-engaged in connection with the end of the speed change process according to the lock-up diagram as shown in FIG. And the feeling of acceleration is lost. In order to prevent this, the engagement area (vehicle speed) of the lockup clutch shown in FIG. 3 is moved to a higher speed side, but the engagement area of the lockup clutch is moved to the higher speed side. The only thing to do is to increase the area where the lock-up clutch does not engage, and there arises a problem that the fuel efficiency cannot be improved particularly when the driver does not want the acceleration performance. Although the technique disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 58-30558 surely reengages the lock-up clutch after the shift is completed, this is merely for the purpose of reducing the shift shock. The timing under which the lock-up clutch is released or re-engaged "in connection with the shift" is merely controlled by a timer. It used to focus on performance. Therefore, the lock-up clutch is re-engaged with the end of the shift in a broad sense, and there is a problem that the acceleration performance is impaired. SUMMARY OF THE INVENTION The present invention has been made in view of such a problem, and it is intended to ensure sufficient acceleration performance especially in running after shifting, and not to reduce the improvement in fuel efficiency, which is one of the major objects of the lock-up clutch. It is an object of the present invention to provide a lock-up control device for an automatic transmission which has been improved in the above.

[Means for Solving the Problems]

As shown in FIG. 1, the present invention provides a lock-up clutch control device for an automatic transmission which includes a torque converter with a lock-up clutch and releases the lock-up clutch during shifting. Means for detecting the occurrence of a shift, means for determining whether or not the shift is performed in a state where the engine torque is positive, means for detecting the accelerator opening degree, and shifting in a state where the engine torque is positive. Means for canceling the re-engagement of the lock-up clutch after the gear shift until it is detected that the accelerator opening has decreased, thereby achieving the above object. In the present invention, "the state where the engine torque is positive"
Means a state in which power is transmitted from the engine side to the wheel side (hereinafter referred to as power-on).

[Action]

Generally, shifting of an automatic transmission is performed by an upshift (power-on upshift) that occurs when the vehicle speed is increased by depressing an accelerator, such as during starting acceleration, and an upshift (power) that occurs when the accelerator is rapidly loosened during traveling. Off-upshift), Downshift (power-on downshift) caused by suddenly depressing the accelerator due to overtaking, etc., Occurs when the vehicle coasts down with the accelerator warmed and the vehicle speed decreases. There are four types of downshift (power-off downshift). Of these, the driver demanding acceleration performance is a power-on upshift and a power-on downshift (particularly, a power-on downshift). When the acceleration performance is important, it is desirable that the lock-up clutch of the torque converter is not engaged. This is because the engine can be used in a rotation speed region higher than the synchronous rotation speed at that time (the rotation speed when the lock-up clutch is turned on), and the torque increasing effect of the torque converter can be obtained. In the present invention, the state in which the shift has occurred, that is, the history of the occurrence of the shift, is determined, and if the shift occurs while the accelerator pedal is depressed, even if the current running state is on the lock-up diagram, Even if the lock clutch is in the area to be engaged, the lock clutch is not engaged. As a result, sufficient acceleration performance can be secured. In the present invention, the state of the engagement center of the lockup clutch is continued until the accelerator opening is reduced by the driver. This is because, when the accelerator is moved in the decreasing direction, it can be estimated that the driver does not request any further acceleration. As a result, thereafter, if the running state is in the area where the lock clutch is to be engaged on the lock-up diagram, the engagement of the lock clutch is appropriately performed.

【Example】

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 2 is a schematic diagram showing the vicinity of a lock-up clutch of the automatic transmission to which the embodiment of the present invention is applied. The automatic transmission 10 includes a torque converter 12 connected to the engine 8 and a coaxial connection with the torque converter 12.
And a well-known gear transmission 14 for forming a plurality of shift speeds. The torque converter 12 is a crankshaft of the engine 8.
Pump impeller 18, connected to 16, one-way clutch
It has a stator 22 connected to the housing via 20, a turbine runner 26 connected to an input shaft 24 of the gear transmission 14, and a lock-up clutch 28. The lock-up clutch 28 transmits the driving force of the crankshaft 16 to the input shaft 24 directly without passing the fluid in the torque converter 12 when engaged, and
The power of the crankshaft 16 is transmitted to the input shaft 24 via the internal fluid. The microcomputer 30 for controlling the automatic transmission receives input signals such as throttle opening (accelerator opening), vehicle speed (rotation speed of the output shaft 29 of the automatic transmission 10), and a shift pattern selected by the driver. And controls the solenoids 34A to 34D of the hydraulic control circuit 32. Of these, solenoid 34
A is provided for controlling the lock clutch 28. When the solenoid 34A is turned on and off, the lock clutch 28 is hydraulically controlled in a well-known configuration to release and engage. The solenoids 34B to 34D are for selectively releasing and engaging a plurality of frictional engagement devices in the gear transmission 14 with a known configuration, thereby achieving a predetermined gear position. Can be. FIG. 4 shows a control flow executed in the microcomputer. First, at steps 100 and 110, the vehicle speed V and the throttle opening θ are read. Next, the routine proceeds to step 120, where it is determined whether or not a shift is necessary from the shift map as shown in FIG. 5 based on the read vehicle speed V and throttle opening θ. If it is determined that shifting is necessary, go to step 130
The lockup clutch 28 is released, and the
At 140, the speed change process is executed. Thereafter, in step 150, it is determined whether or not the shift is a shift performed in a power-on state. This determination is specifically made by determining whether or not the throttle opening θ read in step 110 is equal to or greater than a predetermined value θs. The predetermined value θs is determined by the vehicle speed V read in step 100 or the current gear (gear ratio).
Is appropriately changed in consideration of the above, it is possible to more accurately determine whether or not the shift is performed in a power-on state. If the shift is not a shift performed in the power-on state, the routine proceeds to step 160, where it is determined from the lock-up diagram whether the lock-up clutch 28 should be engaged as shown in FIG. When it is in a state to be engaged, a process for engagement is executed. Therefore,
If the shift is not a shift performed in a power-on state, that is, if it is determined that the shift is not a shift performed in a state where the driver is requesting acceleration performance, the lock-up clutch 28 is not operated. The engagement or disengagement is performed according to the lock-up diagram in FIG. On the other hand, when it is determined in step 150 that the shift is performed while the power is on, the shift is reset without performing the determination and processing of the lock-up clutch 28 in step 160. Immediately after the reset, it is generally determined that there is no need for shifting at step 120, so the process proceeds to step 170, where it is determined whether or not the current running state is after running the power-on state shift. If it is determined that the vehicle is not running after the power-on shift has been performed,
Proceeding to 160, the judgment and processing of the lockup clutch 28 are executed. However, if it is determined that the current running state is after the power-on shift has been performed, then step 18 is executed.
The process proceeds to 0, and it is determined whether or not the throttle opening θ has decreased. This determination is made by determining whether or not the throttle opening θi read in step 110 in this routine is smaller than the throttle opening θi _-1 read in step 110 in the previous routine. . While it is determined that the throttle opening θ has not decreased, the reset is repeated, and steps 100, 110, and 12 are repeated.
The processing of 0, 170, 180 is repeated. Therefore, step 160
The engagement determination of the lock-up clutch 28 is not performed. Therefore, the lockup clutch 28 has a step 130
Is released at the time of shifting, the released state is maintained after all. Eventually, when it is determined in step 180 that the throttle opening has decreased, the process proceeds to step 160, where the engagement of the lock-up clutch is determined and processing is performed. Therefore, thereafter, the lock clutch 28 will be engaged or disengaged in accordance with the lock diagram. According to this control flow, when a gear shift is executed with the driver depressing the accelerator, the lock-up clutch 28 will not be engaged until the driver loosens the accelerator to some extent. It is possible to perform traveling with sufficient performance. Further, since the lock-up clutch 28 does not engage when the engine torque is transmitted to the wheel strongly, the shock at the time of engagement of the lock-up clutch 28 is drastically reduced.

【The invention's effect】

As described above, when a shift is performed, it is determined whether or not the shift is performed when power performance is desired, and the shift is performed when power performance is required. In the case of gear shifting, the lock-up clutch can be maintained in the disengaged state even after the gear shifting process, so that an excellent effect that the demand for the power performance of the driver can be sufficiently satisfied can be obtained. Can be

[Brief description of the drawings]

FIG. 1 is a block diagram showing the gist of the present invention, and FIG.
FIG. 3 is a skeleton diagram showing the vicinity of a lockup clutch of the automatic transmission to which the embodiment of the present invention is applied; FIG. 3 is a diagram showing an example of a map for determining engagement and release of the lockup clutch; FIG. 4 is a flowchart showing a control flow executed in the automatic transmission, and FIG. 5 is a diagram showing an example of a map for determining a gear position. 8 ... engine, 10 ... automatic transmission, 12 ... torque converter, 14 ... gear transmission, 24 ... input shaft, 28 ... rock-up clutch, 29 ... output shaft.

Claims (1)

(57) [Claims] 1. A lock-up clutch control device for an automatic transmission, comprising a torque converter with a lock-up clutch and configured to release the lock-up clutch during shifting, wherein: a means for detecting occurrence of a shift; Means for judging whether the engine torque is in a positive state, means for detecting the accelerator opening, and a lock-up clutch after the gear shift when the gear is shifted in a positive engine torque state. Means for canceling the re-engagement until it is detected that the accelerator opening has decreased, and a lock-up clutch control device for an automatic transmission.