Ratio change control system for multiple ratio transmission

摘要

An automatic control system for a multiple ratio transmission includes an electronically controlled variable orifice configuration within a discharge circuit for a downshift control system from a high speed ratio to an intermediate speed ratio. The variable orifice configuration divides the discharge circuit into an upstream part communicating with an accumulator chamber (66e) and an intermediate brake release pressure chamber (3 S/R) defined by a double acting piston (8) of an intermediate ratio brake servo, and a downstream part communicating with a high speed ratio clutch. A calibrated flow control orifice (120) is disposed in the discharge circuit to control discharge flow of oil from the said downstream part. A transmission controller reduces the variable orifice configuration to provide a reduced orifice size during inertia phase of the downshift.