Braking kick-down control method of double clutch automatic transmission

Abstract

The invention discloses a braking kick-down control method of a double clutch automatic transmission. The braking kick-down control method includes the steps that the pressure on a braking pedal, the opening degree of an accelerator pedal, the vehicle speed, the acceleration of the whole vehicle and the current gear position are acquired; the braking percentage is obtained according to the pressure on the braking pedal, and the gain coefficient is obtained by looking up a table of the braking percentage; according to the vehicle speed and the gain coefficient, the actual gear engaging vehicle speed is obtained; according to the actual gear engaging vehicle speed and the opening degree of the accelerator pedal, a first target gear position is obtained by looking up a table; whether the first target gear position is smaller than the current gear position or not is judged, and whether the opening degree of the accelerator pedal is equal to zero or not is judged; if yes, according to the braking percentage and the acceleration of the whole vehicle, it is determined that a common braking kick-down control mode is executed or a re-treading braking kick-down control mode is executed; if the common braking kick-down control mode is executed, common braking kick-down control is executed; if the re-treading braking kick-down control mode is executed, the re-treading braking kick-down control is executed. By the adoption of the method, it is guaranteed that the gear position can be fast decreased, and the driving comfort and the driving safety are improved.

Description

technical field [0001] The invention relates to the technical field of automobile transmissions, in particular to a braking downshift control method for a dual-clutch automatic transmission. Background technique [0002] A typical wet dual clutch automatic transmission has two clutches, inner and outer. The outer clutch is connected to the outer input shaft and controls the odd gears. The outer clutch is also called the first clutch; the inner clutch is connected to the inner input shaft and controls the even gears and reverse gears (that is, the R gear). The clutch is also called the second clutch. Electro-hydraulic control is used to drive the solenoid valve to realize the gear change and the alternate work of the clutch, and finally realize the automatic shifting. [0003] At present, the wet dual-clutch automatic transmission does not have a special system control function for the downshifting process under the brake intervention. Since the impact of the brakes is not ...

AI Technical Summary

Problems solved by technology

[0003] At present, the wet dual-clutch automatic transmission does not have a special system control function for the downshifting process under the brake intervention. Since the impact of the brakes is not considered, the gear cannot be quickly downshifted, and it is likely to cause the downshifting process under the brakes. In the process, the vehicle is not running smoothly, and the clutch wear time is too long, resulting in overheating of the clutch, which reduces the safety of the vehicle, the comfort of driving and the working life of the clutch, especially in the process of heavy braking. It may cause a sudden increase in the load of the vehicle, a sharp drop in engine speed, and even a situation of flameout, which further reduces the safety of the vehicle and the comfort of driving.

Images