Control apparatus for automatic transmission

Patent metadata

Field	Value
Publication number	US-9810319-B2
Application number	US-201514797440-A
Country	US
Kind code	B2
Filing date	Jul 13, 2015
Priority date	Jul 16, 2014
Publication date	Nov 7, 2017
Grant date	Nov 7, 2017

Abstract

In an apparatus for controlling an automatic transmission connected to a prime mover mounted on a vehicle, having a torque converter equipped with a lock-up clutch, when predetermined operating conditions of the vehicle are satisfied at drive-off, a lock-up clutch engaging circuit is formed through a hydraulic supply circuit. Next it is determined whether engage-position sticking malfunction of the lock-up clutch has occurred based on a ratio of an input rotational speed of the automatic transmission relative to an output rotational speed of the prime mover and a change rate of the output rotational speed of the prime mover when the lock-up clutch engaging circuit has been formed, and fail-safe control is then implement when the sticking is determined.

First claim

What is claimed is:

1. An apparatus for controlling an automatic transmission that is connected to a prime mover mounted on a vehicle and changes speed of rotation of the prime mover to transmit the speed of rotation to driven wheels, having a torque converter interposed between the prime mover and the automatic transmission and equipped with a lock-up clutch, a hydraulic supply circuit that supplies hydraulic pressure to the lock-up clutch and the automatic transmission, and a controller that controls operation of the lock-up clutch and the automatic transmission through the hydraulic supply circuit, comprising:
a rotational speed ratio calculator that calculates a ratio of an input rotational speed of the automatic transmission relative to an output rotational speed of the prime mover; and
a lock-up clutch engage-position sticking determiner that causes the controller to form a lock-up clutch engaging circuit through the hydraulic supply circuit when it is determined that predetermined operating conditions of the vehicle are satisfied at vehicle drive-off, determines whether engage-position sticking malfunction of the lock-up clutch has occurred based on the calculated ratio and a change rate of the output rotational speed of the prime mover when the lock-up clutch engaging circuit has been formed, and causing the controller to implement fail-safe control when the sticking is determined.

2. The apparatus according to claim 1 , wherein the lock-up clutch engage-position sticking determiner determines that the engage-position sticking malfunction of the lock-up clutch has occurred, when it is determined that the calculated ratio is kept to be equal to or greater than a predetermined ratio for a prescribed time period and when the change rate of the output rotational speed of the prime mover was negative at a time at which the calculated ratio was first determined to be equal to or greater than the predetermined ratio.

3. The apparatus according to claim 1 , wherein the lock-up clutch engage-position sticking determiner causes the controller to implement the fail-safe control by disengaging clutches that transmit the output of the prime mover to driven wheels when it is determined that the engage-position sticking malfunction of the lock-up clutch has occurred.

4. The apparatus according to claim 1 , wherein the predetermined operating conditions include at least that the output rotational speed of the prime mover is equal to or greater than a predetermined rotational speed, that the input rotational speed of the automatic transmission is equal to or greater than a prescribed rotational speed, that the calculated ratio is equal to or less than a second predetermined ratio, and that a lock-up clutch control pressure command value that defines engaging pressure of the lock-up clutch is less than a predetermined value.

5. The apparatus according to claim 1 , wherein the predetermined conditions further include that the prime mover is under a stable rotating condition.

6. The apparatus according to claim 1 , wherein the predetermined conditions further include that a gear of the automatic transmission is set to a gear to be used at the vehicle drive-off.

7. The apparatus according to claim 1 , wherein the lock-up clutch engage-position sticking determiner determines the engage-position sticking malfunction of the lock-up clutch only once at the vehicle drive-off.

8. A vehicle comprising the apparatus of claim 1 .

9. A method for controlling an automatic transmission connected to a prime mover mounted on a vehicle through a torque converter, comprising:
calculating a ratio of an input rotational speed of the automatic transmission relative to an output rotational speed of the prime mover, and
forming a lock-up clutch engaging circuit through a hydraulic supply circuit when predetermined operating conditions of the vehicle are satisfied at vehicle drive-off,
determining whether an engage-position sticking malfunction of a lock-up clutch of the torque converter has occurred based on the calculated ratio and a change rate of the output rotational speed of the prime mover when the lock-up clutch engaging circuit has been formed, and
implementing fail-safe control when the engage-position sticking malfunction is determined.

10. The method according to claim 9 , wherein determining that the engage-position sticking malfunction of the lock-up clutch has occurred comprises determining that the calculated ratio is equal to or greater than a predetermined ratio for a prescribed time period and when the change rate of the output rotational speed of the prime mover is negative at a time at which the calculated ratio is first determined to be equal to or greater than the predetermined ratio.

11. The method according to claim 9 , wherein implementing the fail-safe control comprises disengaging clutches that transmit the output of the prime mover to driven wheels when the engage-position sticking malfunction of the lock-up clutch occurs.

12. The method according to claim 9 , wherein the predetermined operating conditions include at least that the output rotational speed of the prime mover is equal to or greater than a predetermined rotational speed, that the input rotational speed of the automatic transmission is equal to or greater than a prescribed rotational speed, that the calculated ratio is equal to or less than a second predetermined ratio, and that a lock-up clutch control pressure command value that defines engaging pressure of the lock-up clutch is less than a predetermined value.

13. The method according to claim 9 , wherein the predetermined conditions further include that the prime mover is under a stable rotating condition.

14. The method according to claim 9 , wherein the predetermined conditions further include that a gear of the automatic transmission is set to a gear to be used at the vehicle drive-off.

15. The method according to claim 9 , wherein determining the engage-position sticking malfunction of the lock-up clutch is performed only once at the vehicle drive-off.

Assignees

• Honda Motor Co Ltd

Inventors

• SHIGENAGA Masato
• Yoshimura Yusuke

Classifications

• F16H2061/1224

  Adapting to failures or work around with other constraints, e.g. circumvention by avoiding use of failed parts · CPC title

• F16H61/143

  using electric control means · CPC title

• F16H2061/1232

  Bringing the control into a predefined state, e.g. giving priority to particular actuators or gear ratios · CPC title

• F16H61/12 Primary

  Detecting malfunction or potential malfunction, e.g. fail safe (in control of hydrostatic gearing F16H61/4192) {; Circumventing or fixing failures} · CPC title

• F16H2061/128

  the main clutch · CPC title