Downshift process control method of three-gear wire control automatic transmission of electric vehicle

Abstract

The invention discloses a downshift process control method of a three-gear wire control automatic transmission of an electric vehicle. The method uses an electric control unit for judging if a second gear is required to be reduced to a first gear and a third gear is required to be reduced to the second gear through detecting a signal of a D-gear switch, a vehicle speed signal (v) of a vehicle speed sensor and an openness signal (a) of a motor acceleration pedal position sensor, and controls the electrification current of electromagnetic clutches in each downshift process. Taking the reduction from the third gear to the second gear as an example, the electric control unit controls the electrification current of a second-gear electromagnetic clutch according to an electrification current function I2b(t)={I2, t is not smaller than 0 and not greater than T delta; kI2+I2(1-k)(t-T delta) / (T32-T delta), t is greater than T delta and not greater than T32} of the second-gear electromagnetic clutch in a fixed control period T32, and controls the electrification current of a third-gear electromagnetic clutch according to an electrification current function I3b(t)={I3, t is not smaller than 0 and not greater than b T delta; 0, t is greater than b T delta and not greater than T32} of the third-gear electromagnetic clutch, so as to realize the downshift process control of the wire control automatic transmission. The downshift process control method not only can prevent the interruption of input power of the motor in the downshift process, but also can prevent the gear shift impact to realize smooth downshift of the wire control automatic transmission.

Description

technical field [0001] The invention relates to a control method of an automatic transmission, more precisely, a control method for a downshift process of a three-speed wire-controlled automatic transmission of an electric vehicle. Background technique [0002] Automatic transmissions are widely used in various vehicles such as automobiles, electric vehicles, and construction machinery. The existing automatic transmissions mainly include hydromechanical automatic transmission (AT), metal belt continuously variable automatic transmission (CVT), mechanical automatic transmission (AMT) and dual clutch automatic transmission (DCT). [0003] The above-mentioned four types of automatic transmissions all adopt electronically controlled hydraulic servo devices to realize the control of the shifting process, which has complex structure, high cost and increased control difficulty and complexity. In particular, the executive mechanism of DCT includes: oil supply mechanism composed of ...

AI Technical Summary

Problems solved by technology

These hydraulic control mechanisms make the overall structure of the transmission complex, high cost and increase the difficulty and complexity of control

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