Method for determining the fill time of a transmission clutch

• US 5,580,332 A
• Filed: 04/13/1995
• Issued: 12/03/1996
• Est. Priority Date: 04/13/1995
• Status: Expired due to Term

• Current Assignee: Caterpillar Incorporated
• Original Assignee: Caterpillar Incorporated
• Inventors: League, Richard B., Creger, Todd D., Mitchell, Randall M., Williamson, Gregory L., Talbott, James R.
• Primary Examiner(s): Marmor, Charles A.
• Assistant Examiner(s): Kwon, Peter
• Application Number:
  US08/421,724
• Time in Patent Office: 600 Days
• Field of Search: 475/123, 475/120, 475/127, 475/128, 475/62, 475/63, 477/70, 477/143, 477/154, 477/156, 477/169
• US Class Current: 477/143
• CPC Class Codes: F16H 2059/467 of torque converter
• CPC Class Codes: F16H 2059/6807 Status of gear-change operation, e.g. clutch fully engaged
• CPC Class Codes: F16H 2061/062 for controlling filling of clutches or brake servos, e.g. fill time, fill level or pressure during filling
• CPC Class Codes: F16H 59/38 of gearing elements
• CPC Class Codes: F16H 59/42 Input shaft speed
• CPC Class Codes: F16H 59/46 dependent on a comparison between speeds
• CPC Class Codes: F16H 61/061 using electric control means

Abstract

The present invention is directed toward determining when a clutch of an automatic transmission substantially fills with fluid. Once it is accurately determined when a clutch fills with fluid, then control over the transmission shifting may reliably be performed. The present invention determines when an on-coming speed clutch substantially fills with fluid in response to determining when an off-going speed clutch releases. Further, the present invention determines when an on-coming direction clutch substantially fills with fluid in response to determining when the torque converter output torque suddenly changes.

Claims

1. A method for determining when a clutch substantially fills with fluid, the clutch being one of a plurality of speed and direction clutches associated with an automatic transmission, the transmission being adapted to receive torque from an engine through a torque convertor, the transmission producing a shift from a first transmission ratio to a second transmission ratio through disengagement of an off-going clutch associated with the first transmission ratio and engagement of an on-coming clutch associated the second transmission ratio, the method comprising the steps of:

monitoring an output speed of the transmission;

monitoring an intermediate speed of the transmission;

determining when an off-going clutch substantially releases based on the transmission intermediate and output speeds; and

determining when an on-coming clutch substantially fills based on when the off-going clutch substantially releases.

2. A method, as set forth in claim 1, wherein the step of determining when an on-coming speed clutch substantially fills, includes the following steps:

determining the actual speed of a predetermined transmission carrier gear based on the transmission intermediate and output speeds;

determining a reference speed;

determining the difference between the actual speed and the reference speed;

comparing the speed difference to a target value; and

determining when an off-going speed clutch substantially releases in response to the speed difference being less than the target value.

3. A method, as set forth in claim 2, wherein the step of determining when an on-coming direction clutch substantially fills, includes the following steps:

determining the slip of an on-coming direction clutch;

comparing the on-coming direction clutch slip to a reference value; and

determining when the on-coming direction clutch substantially fills in response to the on-coming direction clutch slip decreasing relative to the reference value.

4. A method for determining when a clutch substantially fills with fluid, the clutch being one of a plurality of speed and direction clutches associated with an automatic transmission, the transmission being adapted to receive torque from an engine through a torque convector, the transmission producing a shift from a first transmission ratio to a second transmission ratio through disengagement of an off-going clutch associated with the first transmission ratio and engagement of an on-coming clutch associated the second transmission ratio, the method comprising the steps of:

monitoring the torque converter input speed and output speed;

determining a torque converter speed ratio in response to the torque converter input speed and output speed;

comparing the torque converter speed ratio to a reference value; and

determining when an on-coming clutch substantially fills in response to the torque converter speed ratio increasing relative to the reference value.

5. A method, as set forth in claim 4, including the steps of:

determining the difference between the torque converter speed ratio and the reference value;

comparing the difference to a predetermined value; and

determining when an on-coming direction clutch substantially fills in response to the difference being greater than the predetermined value.

6. A method, as set forth in claim 5, including the steps of:

monitoring the slip of an on-coming speed clutch;

comparing the on-coming speed clutch slip to a reference slip value; and

determining when the on-coming speed clutch substantially fills in response to the on-coming speed clutch slip being less than the reference slip value.

7. A method, as set forth in claim 5, including the steps of:

determining when an off-going speed clutch releases; and

determining when an on-coming speed clutch substantially fills based on when the off-going speed clutch releases.