Power-on downshift control of a dual-clutch transmission

摘要

A vehicle includes an engine, dual-clutch transmission (DCT), and controller. The controller executes a method to detect a requested power-on downshift of the DCT from an attained gear to a desired gear. Offgoing and oncoming clutches are identified for the power-on downshift from the input clutches, and the controller determines whether engine speed has reached a target synchronous speed. The controller increases oncoming clutch torque at a calibrated ramp rate when a fork for the desired gear has engaged and releases the offgoing clutch at another calibrated ramp rate. If engine flare is present, the controller adjusts the oncoming clutch ramp rate, uses engine torque management to control the flare, and allows the offgoing clutch to continue disengaging. The power-on downshift is completed when the oncoming clutch reaches full torque capacity of the engine and the offgoing clutch is completely exhausted.

主权项

1. A vehicle comprising:
an engine having an engine speed; a dual-clutch transmission (DCT) having an input member, a pair of input clutches, and separate oddly-numbered and evenly-numbered gear sets, wherein an application of a designated one of the pair of input clutches connects the engine to a corresponding one of the oddly-numbered or evenly-numbered gear sets; and a controller in communication with the pair of input clutches, wherein the controller includes a processor and tangible, non-transitory memory, and wherein the controller is configured to:
detect a requested power-on downshift of the DCT from an attained gear to a desired gear;identify an offgoing clutch and an oncoming clutch for the requested power downshift from among the pair of input clutches;determine whether the engine speed has reached a target synchronous speed;increase clutch torque of the oncoming clutch at a calibrated ramp rate when a fork for the desired gear has engaged;release the offgoing clutch at the calibrated ramp rate while increasing the clutch torque of the oncoming clutch at the calibrated ramp rate;adjust the calibrated ramp rate when engine flare is present to thereby reduce the engine flare to a calibrated level; andcomplete the requested power-on downshift when the oncoming clutch reaches full torque capacity of the engine and the offgoing clutch is completely exhausted.