Urgent speed reducing and gear shifting control method and system of automatic transmission

Abstract

The invention discloses an urgent speed reducing and gear shifting control method and system of an automatic transmission, which are used for controlling gear-shift jumping of a vehicle in case of slamming on the brake for speed reduction. The urgent speed reducing and gear shifting control method comprises the following steps of: acquiring multiple operating parameters of the vehicle in real time, wherein the multiple operating parameters at least include a current gear position, a brake signal and a current acceleration value a of the vehicle; calculating to obtain critical acceleration value a 0 based on the current gear position and preset gear shift time t; acquiring a target gear position according to a preset jump shift-down mode if the brake signal is available and the current acceleration value a is less than the critical acceleration value a 0, if not, acquiring the target gear position according to a normal shift-down mode; and carrying out gear shift from the current gear position to the target gear position on the vehicle.

Description

technical field [0001] The invention relates to the field of automobiles, in particular to a control method and system for rapid deceleration and shifting of an automatic transmission. Background technique [0002] When the vehicle is running, emergency braking may be required in some emergency situations. Under such rapid deceleration conditions, if the automatic transmission vehicle still shifts gears according to the normal shifting schedule, the vehicle will quickly and gradually downshift. Due to the time required for the vehicle to shift gears, it is possible that the vehicle has decelerated to the next shift gear before the clutch starts to engage, which will cause the shifting process to always lag behind the deceleration of the vehicle, and eventually lead to two results: If the clutch is forced to be engaged in the middle, the engine will be turned off; or if the clutch is not engaged, it is equivalent to the engine being in neutral during the rapid deceleration pr...

AI Technical Summary

Problems solved by technology

Due to the time required for the vehicle to shift gears, it is possible that the vehicle has decelerated to the next shift gear before the clutch starts to engage, which will cause the shifting process to always lag behind the deceleration of the vehicle, and eventually lead to two results: If the clutch is forced to be engaged in the middle, the engine will be turned off; or if the clutch is not engaged, it is equivalent to the engine being in neutral during the rapid deceleration process, and engine braking cannot be achieved.

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