Variable-period downshift process control method of multi-gear wire-controlled automatic gearbox

Abstract

The invention discloses a variable-period downshift process control method of a multi-gear wire-controlled automatic gearbox. According to the method, whether the downshift from the second gear to the first gear, the downshift from the third gear to the second gear or the downshift from the fourth gear to the third gear is needed or not is judged by an electric control unit through detecting a D gear switching signal, a vehicle speed signal v of a vehicle speed sensor and an opening degree signal Alpha of an accelerator pedal position sensor, and the electrification current control of an electromagnetic clutch in each downshift process is carried out. By taking the downshift from the third gear to the second gear as an example, the electrification current of a second gear electromagnetic clutch is controlled by the electric control unit according to a variable control period function T(v) and the electrification current function of the second gear electromagnetic clutch: I<2b>(t) ={I2, t is greater than or equal to 0 but is smaller than or equal to T<delta>; kI2+I2(1-k)(t-T<delta>) / (T<32>-T<delta>), t is greater than or equal to T<delta> but is smaller than or equal to T<32>}, meanwhile, the electrification current of a third gear electromagnetic clutch is controlled according to the electrification current function of the third gear electromagnetic clutch: I<3b>(t)={I3, t is greater than or equal to 0 but is smaller than or equal to IT<delta>; 0, t is greater than or equal to IT<delta> but is smaller than or equal to T<32>}, and the downshift process control of the wire-controlled automatic gearbox is realized. The downshift process control method has the advantages that the input power interrupt of an engine in the downshift process can be avoided, in addition, the gear shifting impact can be avoided, and the stable downshift of the wire-controlled automatic gearbox is realized.

Description

technical field [0001] The invention relates to a control method for an automatic transmission, more specifically a control method for a variable-period downshift process of a multi-speed wire-controlled automatic transmission. 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 four types: hydromechanical automatic transmission (AT), metal belt continuously variable automatic transmission (CVT), mechanical automatic transmission (AMT) and dual clutch automatic transmission (DCT). [0003] The above four types of automatic transmissions all use an electronically controlled hydraulic servo device to realize the control of the shifting process, which is complicated in structure, high in cost, and increases the difficulty and complexity of control. In particular, the DCT's executive mechanism includes: an oil supply mecha...

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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