Downshift process control method of multi-block automatic transmission by wire

Abstract

The invention discloses a down-shift process control method of an automatic multi-gear linear control speed changer. The method comprises the steps of judging whether the speed changer needs to be changed from the second level to the first level, from the third level to the second level and from the fourth level to the third level by detecting a D-gear switch signal, a car speed signal (v) of a car speed sensor and an openness signal (a) of an acceleration pedal position sensor by virtue of an electric control unit, and carrying out the electrification current control of an electromagnetic clutch in each down-shift process. Taking the down shift from third level to the second level as an example, the electrification current of a second-level electromagnetic clutch is controlled by virtue of the electric control unit by taking a fixed control period T<32> according to an electrification current function that I<2b>(t) is equal to {I<1> t is less than or equal to T<theta> and more than or equal to zero; kI<1>+I<1>(1-k)(t-T<theta>) / (T<21>-T<theta>), t is more than T<theta and less than or equal to T<21>}, simultaneously the electrification current of a third-level electromagnetic clutch is controlled according to the third-level electromagnetic clutch electrification current function that I<3b>(t) is equal to {I<3>0 t is more than or equal to 0 and less than or equal to beta T<theta>; 0, t is more than beta T<theta> and less than or equal to T<32>}, so that the down-shift process control of the automatic linear control speed changer is realized; by adopting the down-shift process control method, not only can the interruption of the input power of an engine in the down-shift process be avoided, but also the gear shift impact can be avoided, and the stable down-shift of the automatic linear control speed changer can be realized.

Description

technical field

[0001] The invention relates to a control method of an automatic transmission, more precisely a method for controlling the 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 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 hydraulic pump, hy...

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