JPH05332444A - Lock-up clutch control device for automatic transmission - Google Patents

Abstract

PURPOSE:To prevent the generation of racing of engine and the connection shock of a lock up clutch due to the operation of a lock-up clutch at the time of changing the speed. CONSTITUTION:A duty ratio of a solenoid 58 for controlling a lockup clutch 18 during the speed change is set at a value for connecting the lock up clutch 18. The duty ratio is changed continuously so that the predetermined slip condition of the lock-up clutch 18 before and after the speed change and the connecting condition of the lock-up clutch 18 during the speed change are changed smoothly.

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 lock-up clutch control device for an automatic transmission, there is a lock-up clutch control device disclosed in JP-A-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 the oil passage for controlling the lockup clutch, and the lockup clutch is released during the shift to reduce the 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 gear shifting and then completely engaged again. Therefore, depending on the timing of 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 the engaged state during shifting. That is, the lock-up clutch control device for an automatic transmission according to the present invention comprises an N-th speed 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-th speed. The N + 1th 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 + 1th speed, and the lockup clutch at the start of the shift between the Nth speed and the N + 1th speed. Duty ratio control means at the start of shift for gradually changing the duty ratio from the slip state to the engaged state, and a duty ratio control means during shifting for keeping the lock-up clutch in the engaged state as a predetermined duty ratio state during shifting. And at the end of the gear shift, the duty ratio during engagement is adjusted so that a predetermined slip state is reached. Has a shift end time duty ratio control means for gradually changing the Ti ratio, the.

[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 + 1) th speed is commanded, the duty ratio is controlled so that the lockup clutch is engaged. This change in duty ratio is performed smoothly. Further, the duty ratio in the engaged state is set to a constant value, and as this value, a predetermined value is selected according to the shift condition, from a value at which the lockup clutch is firmly engaged to a value at which the lockup clutch is engaged immediately before slipping. At the end of the shift, the constant duty ratio smoothly changes to the duty ratio corresponding to the predetermined slip state at the (N + 1) th speed. As a result, a predetermined slip state at the (N + 1) th speed is realized. As mentioned above, during shifting,
The lockup clutch is engaged, 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 includes 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, and the like 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 has a spool 34 and a sleeve 3.
6, it 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 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. A constant pressure regulated by a pressure regulating valve (not shown) is supplied to the oil passage 50. The oil passage 46 branched from the oil passage 50 via the orifice 56 is connected to the lockup solenoid 58. The lock-up solenoid 58 is not energized and the opening 60 of the oil passage 46 is opened.
The lockup solenoid 58 is energized under duty ratio control by a signal from the control unit 64. That is, the lock-up solenoid 58 is repeatedly turned on and off at a predetermined cycle, opens the opening 60 according to the ratio of the on-time, and thereby adjusts the hydraulic pressure of the oil passage 46 so as to be inversely proportional to the on-time. Signals from an engine rotation speed sensor 66, an output shaft rotation speed sensor (vehicle speed sensor) 68, and a throttle opening sensor 70 are input to the control unit 64, and the control unit 64 will be described later based on these signals. Thus, the operation of the lockup solenoid 58 is controlled.

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 slip 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 6
0 is completely closed by the plunger 62. Therefore, the same hydraulic pressure as that of the oil passage 50 is generated in the oil passage 46, which causes the spool 34 of the lockup control valve 32 to move.
Will act on the left end of. Therefore, the spool 3
4, the hydraulic pressure of the oil passage 42 is supplied to the release chamber 22 via the oil passage 26, and the release chamber 2
The hydraulic pressure 2 flows through the clearance between the friction surface of the cover 28 and the facing 30 to the apply chamber 20 side, then passes through the oil passage 24, returns to the lockup control valve 32, and is 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 a torque converter state in which the rotational force is transmitted only through the fluid.

When controlling the lockup clutch 18 from the above state to the slip state, the following operation is performed. That is, when the duty ratio applied from the control unit 64 to the lockup solenoid 58 is gradually increased, oil is discharged from the opening 60 and the oil pressure in the oil passage 46 is decreased in accordance with this duty ratio. For this reason,
The hydraulic pressure acting on the left end portion of the spool 34 of the lockup control valve 32 decreases, and the spool 34 and the plug 38 move leftward in the drawing. When the spool 34 and the plug 38 are moved leftward by a predetermined amount, the oil passage 26 is slightly in communication with the drain port 72, and at the same time, the oil passage 42 is in communication with the oil passage 24. Oil passage 26
Since the oil pressure of the oil 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 of the oil passage 26 is the oil passage 46.
Therefore, the pressure is adjusted according to the hydraulic pressure acting on the left end portion of the spool 34. 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 in the apply chamber 20 passes through the clearance between the lockup clutch 18 and the cover 28.
It enters 2 and is 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. Since the oil pressure on the release chamber 22 side becomes lower than the oil pressure on the apply chamber 20 side,
The facing 30 of the lockup clutch 18 is pressed against the friction surface of the cover 28. The force for pressing the lockup clutch 18 is controlled by the lockup solenoid 58 as described above. By controlling this pressing force to be slightly smaller than the force required to completely engage the lockup clutch 18,
A slip state in which the lockup clutch 18 slips slightly is realized.

Next, when the duty ratio of the lockup solenoid 58 is set to 100%, the opening 60 is completely released. Therefore, the oil pressure of 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 then it is determined whether or not the operating conditions for gear shifting are in effect (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 (slip state) in which a slight slip is applied (step 106). When the slip state is not present, normal shift control is performed (108). When in the slip state, the duty ratio that gradually changes from the duty ratio of the current slip state to the constant duty ratio corresponding to the fastening state is output (at step 110). It should be noted that the time for gradually changing the duty ratio is set in advance according to the operating conditions (this time can be controlled based on changes in the engine rotation speed, etc.). Then, the constant duty ratio is held for a predetermined time (step 112). During this time, the shift progresses. The above-mentioned predetermined time may be set in advance according to operating conditions, or may be determined from changes in the engine rotation speed and the like. Next, when the above-mentioned certain time has elapsed, the certain duty ratio is gradually changed to the duty ratio corresponding to the gear after the gear shift (at 114). The same applies to the time for changing the duty ratio.

After all, when the shift control to the fifth speed is instructed by the above control, for example, in the state where the lockup clutch 18 is controlled to be in the predetermined slip state at the fourth speed, the lockup clutch 18 is activated. First, the slip state of the fourth speed is changed to the engagement state, during which gear shifting is performed,
Then, the predetermined slip state at the fifth speed is again established.
During this period, the duty ratio changes gradually. In this way, the lock-up clutch is engaged during the shift, so that the engine will not be idle and the shift shock will not occur. It should be noted that the constant duty ratio during engagement can be appropriately set according to the shift condition so that a smooth shift can be obtained.

[0012]

As described above, according to the present invention, the lock-up clutch, which is in the slip state before and after the gear shift, is engaged during the gear shift, so that the engine does not blow dry. The engagement shock of the lock-up clutch will not occur.

[Brief description of drawings]

FIG. 1 is a diagram showing a relationship 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 in which an operating state of a lockup clutch is controlled by hydraulic pressure controlled according to a duty ratio of a solenoid, and the lockup clutch is in a predetermined slip state at the Nth speed. No. N for controlling the duty ratio of the solenoid so that
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 lock-up clutch is in a predetermined slip state at the (N + 1) th speed; and the (N) th speed and the (N + 1) th speed. When the shift is started during the shift, the duty ratio control means for gradually changing the duty ratio so that the lockup clutch changes from the slip state to the engaged state, and the lockup clutch is engaged in a predetermined duty ratio state during the shift. And a duty ratio control means at the end of shifting for gradually changing the duty ratio from the duty ratio being engaged at the end of the gear shifting to a predetermined slip state at the end of the gear shifting. Lockup clutch control device for automatic transmission.