Claims
- 1. A control apparatus for controlling an automatic transmission for a vehicle comprising:
an automatic transmission capable of switching plural shift stages; a torque converter for controlling transmitting rotation of an engine to the automatic transmission via a fluid; a first friction engagement element for connecting a turbine wheel housed in the torque converter and a forward movement member housed in the automatic transmission when the first friction engagement element is engaged; a one-way clutch housed in the automatic transmission so as to establish a predetermined shift stage in the automatic transmission cooperating with the first friction engagement element; and a second friction engagement element housed in the automatic transmission so as to prevent an output shaft of the automatic transmission from being rotated in a reverse direction cooperating with the one-way clutch when the second friction engagement element is engaged; wherein an engagement force for engaging the first friction engagement element is set to be lower than an engagement force for establishing the predetermined shift stage with the second friction engagement element being engaged when a vehicle is under a stationary condition with an acceleration operating member not being operated and a brake operating member being operated under a forward driving range being established in the automatic transmission, the engagement force for engaging the first friction engagement element is increased when the vehicle starts from the stationary condition with the brake operating member released from the operated condition, and the engagement force for engaging the second friction engagement element is decreased when a relative rotational speed between the turbine wheel and the forward movement member becomes equal to or smaller than a predetermined rotational speed, thereby the predetermined shift stage is established in the automatic transmission.
- 2. A control apparatus for controlling an automatic transmission for a vehicle according to claim 1, wherein the engagement force for engaging the second friction engagement element is decreased at a predetermined rate when the relative rotational speed becomes equal to or smaller than an intermediate rotational speed which is greater than the predetermined rotational speed in response to the vehicle start from the stationary condition with the brake operating member released from the operated condition, and the engaging force for engaging the second friction engagement element is further decreased faster than the predetermined rate when the relative rotational speed becomes equal to or smaller than the predetermined rotational speed.
- 3. A control apparatus for an automatic transmission according to claim 2, wherein the predetermined rate is varied so as to decrease the engagement force for engaging the second friction engagement element corresponding to a variation of the relative rotational speed when the relative rotational speed is within a range between the intermediate rotational speed and the predetermined rotational speed.
- 4. A control apparatus for an automatic transmission according to claim 1, wherein the torque converter is disconnected from the automatic transmission in response to the decrease of the engagement force for engaging the first friction engagement element and the second friction engagement element is engaged.
- 5. A control apparatus for an automatic transmission according to claim 2, wherein the engagement force for engaging the first friction engagement element is increased at a constant rate so as to control the relative rotational speed to become equal to or smaller than the intermediate rotational speed or the predetermined rotational speed and the second friction engagement element is decreased.
- 6. A control apparatus for an automatic transmission according to claim 3, wherein the engagement force for engaging the first friction engagement element is increased at a constant rate so as to control the relative rotational speed to become equal to or smaller than the intermediate rotational speed or the predetermined rotational speed and the second friction engagement element is decreased.
- 7. A control apparatus for an automatic transmission according to claim 2, wherein the intermediate rotational speed is smaller than a relative rotational speed under a neutral condition in the automatic transmission.
- 8. A control apparatus for an automatic transmission according to claim 3, wherein the intermediate rotational speed is smaller than a relative rotational speed under a neutral condition in the automatic transmission.
- 9. A method for controlling an automatic transmission for a vehicle comprising:
an engagement force increasing means for increasing an engagement force for engaging a first friction engagement element when a vehicle starts from a stationary condition with a brake operating member released from being operated under a forward driving range in an automatic transmission; a relative rotational speed calculating means for calculating a relative rotational speed between a turbine wheel and a forward movement member; a first comparing means for comparing the relative rotational speed with a predetermined rotational speed; and a first engagement force decreasing means for decreasing an engagement force for engaging a second friction engagement element when the relative rotational speed is equal to or smaller than the predetermined rotational speed, wherein a neutral control is substantially terminated in the automatic transmission prior to performing a hill hold control.
- 10. A method for controlling an automatic transmission according to claim 9, further comprising:
a second comparing means for comparing the relative rotational speed with an intermediate rotational speed being greater than the predetermined rotational speed; a second engagement force decreasing means for decreasing the engagement force for engaging the second friction engagement element at a predetermined rate when the relative rotational speed is equal to or smaller than the intermediate rotational speed, wherein the engagement force for engaging the second friction engagement element is decreased faster than at the predetermined ratio by the first engagement force decreasing means when the relative rotational speed is equal to or smaller than the predetermined rotational speed.
- 11. A method for controlling an automatic transmission according to claim 10, further comprising
a judging means for judging how many times the relative rotational speed was counted after the vehicle started from the stationary condition with the brake operating member released from the operated condition under the forward driving range in the automatic transmission; a relative rotational speed variation calculating means for calculating how much the relative rotational speed was decreased when the relative rotational speed is judged to have been counted before; a first rate determining means for determining a first rate for decreasing the engagement force for engaging the second friction engagement element corresponding to the variation of the relative rotational speed; and a third engagement force decreasing means for decreasing the engagement force for the second friction engagement element at the first rate when the relative rotational speed is within a range between the intermediate rotational speed and the predetermined rotational speed.
- 12. A method for controlling an automatic transmission according to claim 11, wherein the engagement force for engaging the second friction engagement element is decreased at the predetermined rate when the relative rotational speed is judged to be first counted.
- 13. A method for controlling an automatic transmission according to claim 10, wherein the engagement force for engaging the first friction engagement element is increased at a constant rate by the engagement force increasing means so as to control the relative rotational speed to become equal to or smaller than the intermediate rotational speed or the predetermined rotational speed and the second friction engagement element is decreased.
- 14. A method for controlling an automatic transmission according to claim 11, wherein the engagement force for engaging the first friction engagement element is increased at a constant rate by the engagement force increasing means so as to control the relative rotational speed to become equal to or smaller than the intermediate rotational speed or the predetermined rotational speed and the second friction engagement element is decreased.
- 15. A method for controlling an automatic transmission according to claim 12, wherein the engagement force for engaging the first friction engagement element is increased at a constant rate be the engagement force increasing means so as to control the relative rotational speed to become equal to or smaller than the intermediate rotational speed or the predetermined rotational speed and the second friction engagement element is decreased.
- 16. A method for controlling an automatic transmission according to claim 10, wherein the intermediate rotational speed is smaller than a relative rotational speed under a neutral condition in the automatic transmission.
- 17. A method for controlling an automatic according to claim 11, wherein the intermediate rotational speed is smaller than a relative rotational speed under a neutral condition in the automatic transmission.
Priority Claims (1)
Number |
Date |
Country |
Kind |
2002-045200 |
Feb 2002 |
JP |
|
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is based on and claims priority under 35 U.S.C. § 119 with respect to a Japanese Patent Application 2002-040200, filed on Feb. 21, 2002, the entire content of which is incorporated herein by reference.