Patent ID: 6370463
Filing Date: 2002-04-09
Classification: F16H

Abstract:
A transmission ratio shift control method for a swap-shift transmission in a powertrain for an automotive vehicle including an engine and two multiple-ratio gear units, a torque input element of a first of the gear units being connected drivably to the engine, a torque output element of the first gear unit being connected to a torque input element of the second gear unit, an overrunning coupling connecting the torque input element to the torque output element of the first gear unit, a torque output element of the second gear unit being connected to a driven torque output shaft, each gear unit having a reaction member including a pressure-actuated reaction brake means for effecting ratio changes, one reaction brake being applied and the other reaction brake being released, whereby one gear unit is upshifted and the other gear unit is downshifted;the method comprising the steps of: measuring input speed of a torque transfer element of the first gear unit, the output speed of one element of the second gear unit and the speed of a second element of the second gear unit; controlling overrunning speed of the overrunning coupling at the first gear unit during a ratio change interval as reaction brake capacity for the first gear unit is changed whereby a reaction member of the first gear unit becomes released in a first time increment during the ratio change interval; controlling a speed ratio change rate at the second gear unit during the ratio change interval as the reaction brake for the second gear unit is applied whereby the reaction member for the second gear unit becomes braked in a second time increment during the ratio change interval; the reaction brake for the second gear unit becoming fully applied before the reaction brake for the first gear unit is fully released whereby inertia torque disturbances at the output shaft are reduced.