Machine element or mechanism – Rotary member or shaft indexing – e.g. – tool or work turret – Preselected indexed position
Patent
1989-12-26
1991-12-10
Herrmann, Allan D.
Machine element or mechanism
Rotary member or shaft indexing, e.g., tool or work turret
Preselected indexed position
74867, B60K 4106
Patent
active
050707477
ABSTRACT:
In an automatic transmission, clutch-to-clutch powered downshifting is controlled by filling the on-coming clutch at a low pressure while ramping down the off-going clutch pressure until turbine speed is pulled up due to off-going clutch slippage, and then increasing the off-going pressure stepwise to compensate the change from static to dynamic coefficients of friction. Then the on-coming pressure is gradually ramped up and a closed-loop profile control period starts wherein the slip speed of the on-coming clutch is measured and controlled to a slip speed profile by controlling the off-going clutch pressure. When synchronization of the on-coming clutch is first detected, a closed-loop sync control period starts wherein the off-going pressure is controlled to minimize the slip and the on-coming pressure is ramped up at a steeper rate to begin clutch engagement during the sync control period. Adaptive control is accomplished for the initial on-coming pressure by an iterative process which decreases that pressure stepwise until flare occurs and then increases the pressure to stop the flare and repeating the changes in smaller steps to approach the flare condition. Initial off-going pressure is modified when early slip or late slip of the off-going pressure is detected. A modification of off-going pressure step value is effected when the final pressure in the closed-loop period is greater or smaller than the initial pressure. The modifications are targeted to fully correct the respective conditions.
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Lentz Carl A.
Runde Jeffrey K.
General Motors Corporation
Herrmann Allan D.
Levi Benjamin
Navarre Mark A.
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