Control of the supply pressure of a hydraulic actuator

Claim 1

A control device for controlling the hydraulic pressure of a hydraulic actuator of a transmission, said actuator including a cylinder and mating linings, comprising: a controller for producing a control signal having a first input for receiving an engine speed signal ω m , a second input for receiving a turbine speed signal ω t , a third input for receiving an engine load signal α C , a fourth input for receiving a vehicle speed signal V v , a fifth input for receiving an enabling input E, and an output for transmitting said control signal; a pressure modulator connected to said output of said controller, said modulator being controlled by said control signal and closed by a lack of current on said output of said controller; said control signal being a function of the measurement of the slippage Δω=ω m -ω t when α C and V v are less than preset threshold values, said control signal causing said pressure modulator to position said cylinder so that said linings mate; said controller including a first comparator and a second comparator, said first comparator comparing Δω to a first threshold δω and said second comparator comparing Δω to a second threshold ε, whereby a large gain correction signal δ=δ(Δω 1 ) is generated to modify said control signal if Δω 1 =δω-Δω is negative, a small gain correction signal δ=δ(Δω 2 ) is generated if Δω 1 is positive and Δω 2 =ε-Δω is negative, and a zero gain correction signal is generated if Δω 1 and Δω 2 are positive.