Gm Global Technolgoy Operations, Inc.

Kenneth B Harmon

Carl A Lentz

Joseph H Hunter

Ted M McQuinn

Richard J Koenig

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.

Double transition closed throttle downshift control in an automatic

A transmission having a torque converter, lockup clutch, and a 5-speed planetary transmission having four planetary gearsets and six frictiondrive-establishing devices combined to provide five forward speed range drives having a large total gear ratio step, and a reverse drive having a moderate and a high gear ratio. The 1st or primary gearset, with the primary input to the sun gear, the ring gear braked, and carrier output, provides 1st range drive having the largest torque multiplication gear ratio. The 2nd, 3rd and 4th gearsets, the secondary gearsets, are used to provide a secondary input having decreasing torque multiplication gear ratios, to the ring gear of the 1st gearset which, with the primary input to the sun gear, provides 2nd through 5th range drives having decreasing gear ratios. The gear ratio steps between 1st, 2nd, and 3rd ranges are wide, and between 3rd, 4th, and 5th ranges are very close. The automatic controls provide torque converter drive in a portion or all of 1st and 2nd range drives and in a portion of 3rd range drive up to a transition output speed, and lockup drive above the transition output speed in 3rd range drive and all of 4th and 5th range drives, to maintain engine speed within a small engine working speed range between the peak torque speed and maximum governed speed.

Multirange transmissions

A multiratio powershift transmission with a shift control system having a manually selected roading phase and a working phase. The roading phase for vehicle drive permits manual selection of a normal automatic shift control mode providing automatic shifting between ratio drives in response to output speed and throttle for maintaining the engine driven input in a normal speed range for optimum economy at part throttle and optimum performance at full throttle, and a hold automatic shift control mode providing a manually selected ratio drive with hold automatic upshifts and normal automatic downshifts and inhibiting manual hold downshifts between ratio drives in response to output speed to limit engine driven input speed to a maximum speed range during overrun drive. The working phase for driving a works, such as a derrick, permits manual selection of the ratio drives to provide progressive output speed control in response to throttle, and provides hold upshifts and inhibited manual downshifts to limit engine speed to a maximum speed range.

Transmission with automatic and manual control modes

An automatic multiratio drive transmission having an automatic shift control system with a speed and throttle position pressure controlled shift valve controlling shifts between the highest drive ratio and the next lower drive ratio. When the shift valve is in the lower drive ratio position, a normal speed pressure signal increasing with increasing speed acting on the shift valve overcomes an opposing bias force controlled by throttle pressure to upshift the shift valve to the higher drive ratio position at increasing upshift speeds for increased throttle positions and provides an upshift hysteresis force decreasing with increasing throttle positions to prevent shift cycling as the highest ratio is established in a short time period and after a longer time delay period reduces the normal speed related governor pressure in an amount equal to the upshift hysteresis force at full throttle so that the downshift speed is the same as the upshift speed at the full throttle position.

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Carmel, IN, United States of America

Kenneth B Harmon