Frederick K Reichert

US Patent:

46711392, Jun 9, 1987

Filed:

Jan 27, 1986

Appl. No.:

6/822397

Inventors:

Robert C. Downs - Ortonville MI
Larry T. Nitz - Troy MI
Frederick K. Reichert - Auburn Hills MI
Joseph L. Wanamaker - Rochester MI

Assignee:

General Motors Corporation - Detroit MI

International Classification:

B60K 4106

US Classification:

74866

Abstract:

Clutch-to-clutch downshifts in the course of a coast mode of operation are effected by releasing the off-going clutching device at a time determined in relation to the vehicle speed and deceleration rate, and applying the on-coming clutching device a predetermined time thereafter such that the apply occurs when the engine speed is substantially equal to the transmission input speed in the downshifted speed ratio. The predetermined time defines an neutral interval during which the on-coming clutching device is filled with hydraulic fluid in preparation for engagement, and the engine speed assumes its neutral idle value. At the end of the predetermined time, the engine speed and the transmission input speed in the downshifted speed ratio are at the neutral idle value, and the on-coming clutching device is applied to complete the shift.