Double transition closed throttle downshift control in an automa

Details Double transition closed throttle downshift control in an automa Double transition closed throttle downshift control in an automa

1990-01-11

1991-02-05

Diehl, Dwight

Machine element or mechanism

Rotary member or shaft indexing, e.g., tool or work turret

Preselected indexed position

74867, 74336R, B60K 4106

Patent

active

049894773

ABSTRACT:
In an automatic transmission, a double transition closed throttle downshift to a target range requires the release of two off-going clutches and the engagement of two on-coming clutches. The shift is made in two stages. The first stage involves a first off-going clutch and a first on-coming clutch and effects an upshift to a third range having a speed ratio lower than both the initial range and the target range, so that a momentary input speed decrease occurs. The speed decrease is managed by a closed-loop control of the first on-coming clutch until the clutch reaches a synthronous speed for the third range. The second stage is a downshift from the third ratio to the second ratio by a second off-going clutch and a second on-coming clutch and results in a speed increase. The second on-coming clutch is also managed by a closed-loop control. In each case, the closed-loop control parameter is on-coming clutch slip speed which is controlled to a calculated slip speed profile.

REFERENCES:
patent: 4023443 (1977-05-01), Usui et al.
patent: 4073204 (1978-02-01), Dick
patent: 4653351 (1987-03-01), Downs et al.
patent: 4709596 (1987-12-01), Boda et al.
patent: 4722247 (1988-02-01), Shindo et al.
patent: 4742732 (1988-05-01), Hiramatsu
patent: 4790418 (1988-12-01), Brown et al.
patent: 4793216 (1988-12-01), Hiramatsu et al.
patent: 4796490 (1989-01-01), Butts et al.
patent: 4855914 (1989-08-01), Davis et al.

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