Vehicle powertrain and method for controlling a vehicle

Abstract

The present disclosure relates to a vehicle powertrain and method for controlling a vehicle, or a system and method for controlling a vehicle powertrain with a transmission to improve shift quality based on Detection of an initial rise time of torque capacity indicating the start of a torque phase. The initial rise time is detected using a transmission input shaft torque calculation. The system may include a vehicle powertrain having an engine, a transmission coupled to the engine through a torque converter, and a controller configured to operate during a period characterized by a preparation phase, a torque phase, and an inertia phase Torque phase control is initiated when a difference between the first transmission input shaft torque and the second transmission input shaft torque exceeds a first predetermined threshold parameter during a shift event.

Description

technical field

[0001] The present disclosure relates to a multi-speed automatic transmission for an automatic vehicle and a control strategy for effecting engagement and disengagement of a transmission friction torque building element during a gear ratio change. Background technique

[0002] Multi-speed automatic transmissions in motor vehicle powertrains utilize multiple friction elements to automatically shift gear ratios. Typically, these friction elements can be described as torque building elements, but are more commonly referred to as clutches or brakes. Friction elements establish a power flow path from the internal combustion engine to the vehicle traction wheels. During vehicle acceleration, for a given accelerator pedal demand, the overall speed ratio (i.e., the ratio of transmission input shaft speed to transmission output shaft speed) decreases as the speed of the vehicle increases as the transmission upshifts through different ratios. Small.

[0003] In the ...

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