US 6,981,931 B2
Method and apparatus for providing momentary torque reversal for a transmission having an automated shift system
Wade A. Smith, Imlay City, Mich. (US); and Thomas A. Genise, Dearborn, Mich. (US)
Assigned to Eaton Corporation, Cleveland, Ohio (US)
Filed on Mar. 12, 2004, as Appl. No. 10/799,983.
Prior Publication US 2005/0202928 A1, Sep. 15, 2005
Int. Cl. B60K 41/02 (2006.01)
U.S. Cl. 477—70 15 Claims
OG exemplary drawing
 
1. A vehicle transmission for providing a plurality of selectable speed ratios, comprising:
an input shaft that receives torque in a first direction of rotation,
a plurality of gear sets that each selectively provide one of the plurality of gear ratios, wherein each gear set has a plurality of gears arranged in a gear train;
a wet master clutch may be disengaged to facilitate sufficient disengagement of the engine from the transmission, allowing the transmission to change from one of the gear sets to another gear set, wherein a residual torque in the wet clutch caused by viscous drag resists disengagement of the transmission;
at least one shifter motor shifts the transmission from one gear set, to a neutral position between gear sets, and to another gear set;
a control system determines if shifting of the transmission into the neutral position is delayed for more than a predetermined period; and
an auxiliary motor is operatively connected to the transmission to selectively apply torque in a second direction of rotation that is opposite to the first direction of rotation when the control system determines that shifting into the neutral position is delayed for more than the predetermined period to overcome the residual torque and thereby facilitate shifting the transmission to the neutral position.