US 7,608,013 B2 · Transmission downshift control method

Abstract

A method of controlling a downshift in a transmission having a main box and a compounder that has at least one gearset and at least one friction element separate from the main box includes initiating an upshift in the compounder including application of at least one friction element (e.g. a clutch) in the compounder, and releasing a friction element (e.g. a clutch) in the main box providing a swap shift. The speed phase in the compounder may trigger the speed phase in the main box, and vice versa. Target fluid volumes in one or both of a clutch being released in the main box and a clutch being applied in the compounder may be controlled and adjusted, if necessary, as a function of specific event timing in prior shifts.

Claims18

Dependent claims

A method of controlling a downshift in a transmission having a main box and a compounder coupled to the main box and having at least one gearset and at least one clutch separate from the main box, the method comprising:

initiating an upshift in the compounder including application of at least one clutch in the compounder;
initiating venting of a clutch being released in the main box;
determining occurrence of slip in the compounder and the main box;
controlling, after slip has occurred in the main box, a duty cycle of a solenoid associated with the clutch being released in the main box as a function of a desired acceleration of the main box;
determining a target input speed for the gear into which the transmission is being shifted;
initiating filling of a clutch to be applied in the main box;
and
controlling a duty cycle of a solenoid of the clutch being applied in the main box when the input speed exceeds the target input speed to control the apply rate of the clutch being applied to bring the input speed to the target input speed.

5 more elements

A method of controlling a double swap downshift in a transmission having a main box and a compounder coupled to the main box, the method comprising:

initiating application of a clutch in the compounder for an upshift in the compounder;
initiating release of a clutch in the main box for a downshift in the main box;
determining a compounder target speed and a target input speed for the selected gear into which the transmission is being shifted;
controlling a solenoid duty cycle associated with the clutch being applied in the compounder after slip has occurred in the compounder to control the deceleration of the compounder until the compounder speed is within a threshold value of the compounder target speed and thereafter completing the upshift in the compounder;
controlling a solenoid duty cycle associated with the clutch being released in the main box after slip has occurred in the main box to control the acceleration of the main box until the input speed is within a threshold value of the target input speed and thereafter completing the downshift in the main box.

2 more elements

Dependencies are inferred from the claim text.

Transmission downshift control method

Life of this patent

Transmission downshift control method

Life of this patent

Abstract

Claims18