Patent ID: 7850572

Claim:
An apparatus for controlling hydraulic fluid to a clutch in a vehicle automatic speed change transmission where the clutch is configured to couple a pair of members at least one of which is rotatable, comprising: an electro-hydraulic pressure control module having an outlet configured to provide fluid at an outlet pressure that is variable in accordance with a control current signal, said outlet being in fluid communication with said clutch; an estimator configured to generate a pressure estimation signal indicative of an actual clutch pressure; a pressure to current controller configured to generate said control current signal in response to a control pressure signal; and a control arrangement configured to generate said control pressure signal in response to (i) a clutch pressure command signal indicative of a desired, commanded clutch pressure and (ii) said pressure estimation signal, said control arrangement being further configured to generate said control pressure signal so as to reduce deviations in said actual clutch pressure relative to said commanded clutch pressure.