Auxiliary electricity and liquid composite braking control method applied for hybrid vehicle to go downhill

Abstract

The invention discloses an auxiliary electricity and liquid composite braking control method applied for a hybrid vehicle to go downhill. The method comprises the following strategies: a brake torque is preferentially distributed to an electric motor, then an engine, and finally a hydraulic brake system; the value of the torque of the engine is a constant when the speed is stable; the value of the hydraulic brake torque is that T,hyd=max((Thyd_min),(T,sum-T,PM1)), and the value of brake torque of the electric motor is that T,PM1=min(((TPM_max*f(delta V,)),(T,sum-Thyd_min)), wherein T,sum is a total brake torque distributed to the electric motor and hydraulic pressure, Thyd_min is the minimum response torque that the hydraulic brake system can start, TPM_max is the maximum brake torque that the electric motor can bear, f(delta V,) is a function inversely proportional to d delta V/dt and is calibrated and obtained by the system; and when T,sum is smaller than TPM_max with a certain proportion specified by the system, the auxiliary braking of hydraulic pressure can stop. In order to achieve safe, economical and comfortable driving when going downhill, a parallel connection type electricity and liquid auxiliary braking control method is provided, and a coordinated braking method of the electric motor and the hydraulic pressure is particularly provided, so that the defect that the hydraulic brake system starts in a time delay manner is remedied, and the brake energy feedback of the electric motor after the hydraulic system starts can be maximized.

Description

technical field [0001] The invention relates to vehicle auxiliary braking control technology, in particular to a method for coordinating braking of a motor and a hydraulic braking system during a downhill auxiliary braking process of a hybrid electric vehicle. Background technique [0002] Under the premise of increasing car ownership and people's higher requirements for car driving safety and comfort, the active safety technology (assistant driving technology) of cars has become one of the focuses of research in the automotive industry. Hybrid electric vehicle (HEV) downhill assist Braking is an active safety control technology for automobiles. The use of auxiliary braking greatly reduces the driving burden of the driver on the downhill section and improves the driving safety of the vehicle on the downhill section. [0003] In a hybrid vehicle, the engines, motors and hydraulic brake systems are involved in the downhill auxiliary braking. The downhill auxiliary braking pro...

AI Technical Summary

Problems solved by technology

But this method exists: First, although the hydraulic brake is turned on in advance through the strategy, the predictive control has certain limitations, which will affect the control accuracy; second, although the fast response characteristics of the motor can make up for the slow hydraulic response and the lack of control accuracy , to improve the accuracy of hydraulic control, but did not consider the problem of improving the response speed of the hydraulic system through the distribution and coordination of the motor and hydraulic braking torque

For the problem of maximizing the braking energy feedback in the electric-hydraulic coordinated braking process, it is only proposed that when the motor torque exceeds a certain threshold, a certain proportion of the motor torque is allocated to the hydraulic brake, but this method can only ensure that the motor The torque is in a high range, but it cannot guarantee that the motor braking torque feedback is always maximum

Images