Patent ID: 7212898
Filing Date: 2007-05-01
Classification: B60W,F16H,Y10T

Abstract:
1. A method for improving a downshift of a powertrain having an automatic transmission and a power source, said downshift including an inertia phase and a torque phase, said automatic transmission having a first off-going clutch; a second off-going clutch; a primary on-coming clutch; and a secondary on-coming clutch, said method comprising: establishing at least one adaptive parameter; disengaging both said first and second off-going clutches; engaging the secondary on-coming clutch; engaging the primary on-coming clutch; calculating an optimal inertia phase transmission input torque value; causing the power source to produce torque such that the optimal inertia phase transmission input torque value is substantially achieved during the inertia phase of the downshift; calculating an optimal torque phase transmission input torque value; causing the power source to produce torque such that the optimal torque phase transmission input torque value is substantially achieved during the torque phase of the downshift; monitoring transmission operating characteristics during the downshift to identify a predefined aberration from a predefined optimal downshift; and adjusting said at least one adaptive parameter in response to said at least one aberration to improve subsequent downshifts.