JPH06101755A - Lockup clutch controller of automatic transmission - Google Patents

Abstract

PURPOSE:To prevent generation of racing of an engine and clamping shock of a lockup clutch in accordance with temporarily releasing the lockup clutch at the time of speed change. CONSTITUTION:The duty ratio of a solenoid (58) for lockup clutch control before and after speed change is set so that a lockup clutch (18) may come in a specified slipping condition. A continuous change is allowed from the duty ratio before the speed change to the duty fue after speed change, during process of speed change.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art As a conventional lockup clutch control device for an automatic transmission, there is one disclosed in Japanese Patent Laid-Open No. 62-7885. In this, the lock-up clutch is temporarily released during shifting. That is, a switching valve that switches only during a shift is provided in the middle of an oil passage for controlling the lockup clutch, and the lockup clutch is released during the shift to reduce shift shock.

[0003]

However, in the conventional lock-up clutch control device for an automatic transmission as described above, the lock-up clutch is temporarily completely disengaged during a gear shift and then completely engaged again. So, depending on the timing with the gear change, the engine may blow dry,
There is a problem that a fastening shock may occur. The present invention aims to solve such problems.

[0004]

The present invention solves the above problems by holding the lock-up clutch in a slip state even during shifting. That is, the lockup clutch control device for an automatic transmission according to the present invention comprises an Nth speed duty ratio control means for controlling the duty ratio of the solenoid so that the lockup clutch is in a predetermined slip state at the Nth speed, and Duty ratio control means for controlling the duty ratio of the solenoid so that the lock-up clutch is in a predetermined slip state at the N + 1th speed, and a duty ratio for the Nth speed when shifting between the Nth speed and the N + 1th speed. A shift duty ratio control means for continuously changing the duty ratio of the (N + 1) th speed.

[0005]

The duty ratio of the solenoid is controlled so that the lockup clutch is in a predetermined slip state at the Nth speed. The slippage of the lock-up clutch prevents the rotational vibration of the engine from being transmitted to the drive wheels. When a shift command from the Nth speed to the N + 1th speed is commanded, the duty ratio continuously changes from the value at the Nth speed to the value at the N + 1th speed. It should be noted that the control is performed so that a predetermined slip state is obtained even at the (N + 1) th speed.
Since the engine speed is different from the Nth speed and the appropriate slip amount is also different, the duty ratio is also different from the Nth speed. During shifting, the duty ratio changes from the Nth speed state to the Nth speed state.
Since the lockup clutch continuously changes to the + 1st speed state, the slip state of the lockup clutch gradually changes, and gear shifting is performed during this period. Therefore, the engine is not blown idle and the engagement shock does not occur. The same applies to the case of shifting from the (N + 1) th speed to the Nth speed.

[0006]

EXAMPLE FIG. 2 shows an example of the present invention. The torque converter 10 has a lockup clutch 18 in addition to the pump impeller 12, the turbine runner 14, and the stator 16. An apply chamber 20 in which the pump impeller 12, the turbine runner 14, etc. are arranged is formed on the right side of the lockup clutch 18 in the drawing, and a release chamber 22 is formed on the left side of the lockup clutch 18 in the drawing. An oil passage 24 is connected to the apply chamber 20, and an oil passage 26 is connected to the release chamber 22. The lockup clutch 18 has a facing 30 that comes into contact with the friction surface of the cover 28 of the torque converter 10. Oil passage 2
The lockup control valve 32 controls the supply state of the hydraulic pressure to the hydraulic pressure 4 and the oil passage 26. The lockup control valve 32 includes a spool 34 and a sleeve 3.
6, has a plug 38 and a spring 40. Further, the oil passage 42, the oil passage 44, the oil passage 46, the oil passage 48, and the oil passage 50 other than the oil passage 24 and the oil passage 26 described above are also connected as illustrated. A constant pressure is supplied to the oil passage 42 from a torque converter relief valve 52. The torque converter relief valve 52 has an oil passage 54 to which hydraulic pressure is supplied from a pressure regulator valve (not shown).
The pressure is adjusted by using the hydraulic pressure. The oil passage 44 is connected to an oil cooler 56, and the oil exiting the oil cooler 56 is used for lubrication. The oil passage 50 is supplied with a constant pressure regulated by a pressure regulating valve (not shown). The oil passage 46 branched from the oil passage 50 via the orifice 56 is connected to a lockup solenoid 58. The lock-up solenoid 58 is in the non-energized state and the opening 60 of the oil passage 46.
Is provided in a closed state, and the duty ratio of the energized state of the lockup solenoid 58 is controlled by a signal from the control unit 64. That is, the lockup solenoid 58 is turned on at a predetermined cycle.
The off state is repeated, and the opening 60 is opened in accordance with the on time ratio, whereby the hydraulic pressure of the oil passage 46 is adjusted so as to be inversely proportional to the on time. The control unit 64 includes an engine rotation speed sensor 66, an output shaft rotation speed sensor (vehicle speed sensor) 68, and a throttle opening sensor 7
Signals from 0 are input, and the control unit 64 controls the operation of the lockup solenoid 58 based on these signals as described later.

Next, the operation of this embodiment will be described.
First, the general operation of the lockup clutch 18, that is, the control of the disengaged state, the half-clutched state, and the completely engaged state will be described. The released state of the lockup clutch 18 is realized as follows. That is, the duty ratio of the lockup solenoid 58 is set to 0, and the opening 60 is completely closed by the plunger 62. Therefore, the same hydraulic pressure as the oil passage 50 is generated in the oil passage 46,
This acts on the left end of the spool 34 of the lockup control valve 32. Therefore, the spool 34 is in the state shown in the figure, and the oil pressure of the oil passage 42 is changed to the oil passage 26.
Is supplied to the release chamber 22 via the hydraulic pressure of the release chamber 22 and the frictional surface of the cover 28 and the facing 30.
Through the clearance between the lockup control valve 32 and the apply chamber 20.
And then discharged to the oil passage 44. That is, the hydraulic pressure is supplied from the oil passage 26 to the release chamber 22, and then discharged from the apply chamber 20 to the oil passage 24. Therefore, the hydraulic pressure in the release chamber 22 and the hydraulic pressure in the apply chamber 20 become the same (strictly speaking, since the apply chamber 20 side is on the downstream side, the apply chamber 20 side is slightly lower due to the flow path loss). As a result, the lockup clutch 18 is released. That is, the torque converter 10 is in the torque converter state in which the rotational force is transmitted only through the fluid.

When the lockup clutch 18 is controlled from the above state to the half-clutch state, the following operation is performed. That is, when the duty ratio given from the control unit 64 to the lockup solenoid 58 is gradually increased, oil is discharged from the opening 60 according to this duty ratio, and the oil pressure in the oil passage 46 is reduced. Therefore, the spool 3 of the lockup control valve 32
The hydraulic pressure acting on the left end portion of No. 4 decreases, and the spool 34 and the plug 38 move leftward in the drawing. Spool 34
When the plug and the plug 38 move leftward by a predetermined amount, the oil passage 26
Is in a state of slightly communicating with the drain port 72,
At the same time, the oil passage 42 is in communication with the oil passage 24. Since the oil pressure in the oil passage 26 is fed back to the right end portion of the plug 38 via the oil passage 48, the lockup control valve 32 is in a pressure regulating state, and the oil pressure in the oil passage 26 is changed from the oil passage 46 to the left end portion of the spool 34. The pressure is adjusted according to the hydraulic pressure that acts on. That is, in this state, the hydraulic pressure is supplied to the apply chamber 20 from the oil passage 24 in the torque converter 10, and the hydraulic pressure of the apply chamber 20 enters the release chamber 22 through the clearance between the lockup clutch 18 and the cover 28. It will be discharged from the oil passage 26. The oil pressure in the oil passage 26 is controlled by the oil pressure in the oil passage 46, that is, the oil pressure adjusted in inverse proportion to the duty ratio of the lockup solenoid 58. Apply room 2
Since the oil pressure on the release chamber 22 side is lower than the oil pressure on the 0 side, the facing 30 of the lockup clutch 18 is pressed against the friction surface of the cover 28. The force pressing the lockup clutch 18 is controlled by the lockup solenoid 58 as described above.

Next, when the duty ratio of the lockup solenoid 58 is set to 100%, the opening 60 is completely released. Therefore, the oil pressure in the oil passage 46 becomes 0, and the spool 34 is completely switched to the left side in the drawing. In this state, oil pressure is supplied from the oil passage 24 to the apply chamber 20 and the lockup clutch 18 is completely engaged, so that almost no oil flows into the oil passage 26.

The general control of the lockup clutch 18 has been described above. Next, the control of the lockup clutch 18 before and after the shift according to the present embodiment will be described. First,
As shown in the control flow of FIG. 3, various signals indicating operating conditions are read (step 102), and it is then determined whether or not the operating conditions for gear shifting are in effect (step 104). When the necessity of gear shifting is judged and the gear shifting command is output,
It is determined whether or not the lockup clutch 18 is in a control state in which a slight slip is given (at 106).
In this embodiment, the slip control is performed by the duty ratio corresponding to the predetermined value so that the pressure difference between the pressure inside the apply chamber 20 and the pressure inside the release chamber 22 becomes a predetermined value. This duty ratio is obtained from a map determined by the shift speed and the throttle opening. When not in this control state, normal shift control is carried out (see 10 above).
8). When the control state is such that a slight slip is given, the duty ratio of the current gear is determined (see 11
0). As this duty ratio, an average value for a predetermined period of time is obtained, and it is a value obtained by learning the change of the duty ratio due to the change of the oil temperature and the friction coefficient of the facing. Next, the duty ratio at the shift stage after the shift is completed is calculated (step 112). An average value is also adopted for this duty ratio, and it is corrected by learning. Next, the duty ratio during shifting is determined (at step 114). The duty ratio during shifting is based on the shifting time predicted from the driving conditions,
It is a value that linearly changes from the duty ratio in the shift stage before the shift to the duty ratio in the shift stage after the shift. Next, the duty ratio is output to the lockup solenoid 58 to control the slip state during the shift (step 116). After the gear shift, the duty ratio at the gear stage after the gear shift is output (see 11
8).

After all, when a shift command to the fifth speed is commanded by the above control, for example, when the lockup clutch 18 is controlled to be in a predetermined slip state at the fourth speed, the lockup clutch 18 is activated. The duty ratio gradually changes so that a predetermined slip state is obtained at the fifth speed. Gear shifting is performed during the change in the slip state. Therefore, the engine is not blown idle or a shift shock is not generated.

[0012]

As described above, according to the present invention, the duty ratio of the solenoid for controlling the lockup clutch is continuously changed from the state of the shift stage before the shift to the state of the shift stage after the shift during the shift. Since the lockup clutch is held in the slip state even during the shift, the slip state also changes smoothly. Therefore,
The engine does not blow dry, and the lock-up clutch engagement shock does not occur.

[Brief description of drawings]

FIG. 1 is a diagram showing relationships between components of the present invention.

FIG. 2 is a diagram showing an example of the present invention.

FIG. 3 is a diagram showing a control flow.

[Explanation of symbols]

 18 Lockup clutch 58 Lockup solenoid 64 Control unit

Claims (1)

[Claims] 1. A lockup clutch control device for an automatic transmission, wherein a hydraulic pressure is controlled according to a duty ratio of a solenoid, and an operating state of the lockup clutch is controlled by the hydraulic pressure. No. N for controlling the duty ratio of the solenoid so that the slip state becomes
A high speed duty ratio control means, and a (N + 1) th speed duty ratio control means for controlling the duty ratio of the solenoid so that the lockup clutch is in a predetermined slip state at the (N + 1) th speed, and the Nth speed and the (N + 1) th speed. Nth when shifting
A shift-up duty ratio control means for continuously changing between a duty ratio of a high speed and a duty ratio of a (N + 1) th speed, and a lockup clutch control device for an automatic transmission.