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AssigneeGeneral Motors Corporation
InventorsTodd M Steinmetz, Jeffrey Kurt Runde, Gregory A Hubbard, Phillip F McCauley, Charles Francis Long, Martin Robert Dadel
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An improved shift control for a hydraulic automatic transmission in which the apply chamber of an on-coming clutch is filled in the preparation phase of the shift using a hydraulic flow rate model to estimate the volume of hydraulic fluid supplied to the apply chamber. In an initial portion of the fill interval, fluid is supplied to the apply chamber at a first elevated pressure, while continuously updating the fluid volume estimate. When the remaining un-filled volume of the apply chamber reaches a reference volume, the supply pressure is reduced to a second pressure at which the next phase of the shift is to be carried out. When the chamber volume is filled, the torque capacity of the clutch rises to a level corresponding to the second pressure, and the next phase of the shift automatically ensues.
A control method for an automatic transmission including an on-coming clutch having an apply chamber that is filled with hydraulic fluid in a preparation phase of shifting, a pump for providing hydraulic fluid at a regulated pressure, and a controller for supplying hydraulic fluid at a commanded pressure to the on-coming clutch during the preparation phase, the method comprising the steps of:
Dependencies are inferred from the claim text.