Method of clutch-to-clutch closed throttle downshift in an autom

Details Method of clutch-to-clutch closed throttle downshift in an autom Method of clutch-to-clutch closed throttle downshift in an autom

1990-01-11

1991-09-03

Cangialosi, Salvatore

Boots, shoes, and leggings

74866, B60K 4102

Patent

active

050461745

ABSTRACT:
In an automatic transmission, clutch-to-clutch closed throttle downshifting is controlled by filling the on-coming clutch at a maximum pressure command for a set period while commanding the off-going clutch pressure to a low value and exhausting the off-going clutch before the end of the fill period. At the end of the fill period the on-coming pressure is set to an initial value and then ramped up until turbine speed is pulled up due to off-going clutch slippage. Then a closed-loop profile control period starts wherein the slip of the on-coming clutch is measured and controlled to a slip profile. When synchronization of the on-coming clutch is detected, maximum pressure is commanded. If the throttle is opened during the downshift, the algorithm reverts to a powered downshift algorithm if the off-going clutch still has pressure or to an open-loop ramp control of the on-coming clutch if the off-going clutch has been exhausted.

REFERENCES:
patent: 4653351 (1987-03-01), Downs et al.
patent: 4671139 (1987-06-01), Downs et al.
patent: 4757886 (1988-07-01), Brown et al.
patent: 4765450 (1988-08-01), Kurihara et al.
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patent: 4875391 (1989-10-01), Leising et al.
patent: 4893527 (1990-01-01), Furusawa et al.
patent: 4913004 (1990-04-01), Panoushek et al.
patent: 4955259 (1990-09-01), Narita

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