Patent ID: 7326149

Claim:
A control method for controlling speed ratio shifts in a multiple-ratio converterless transmission for an automotive vehicle powertrain wherein an internal combustion engine is connected directly to torque input elements of the transmission, the transmission having multiple pressure-actuated friction elements, a speed ratio change in the transmission being effected by engaging a pressure actuator for an oncoming friction element and releasing a pressure actuator for an off-going friction element, the method comprising the steps of: increasing actuating pressure for the oncoming friction element during a torque phase of a power-on upshift; detecting slip speed of an actuator for the oncoming friction element at the beginning of an inertia phase of the power-on upshift; controlling slip speed of the oncoming friction element using closed loop control triggered by detection of slip speed of the actuator for the oncoming friction element; and increasing pressure of the actuator for the oncoming friction element at the end of the closed loop control as slip of the oncoming friction element becomes approximately zero.