Automobile Electric Power Steering System with Intelligent Overload Protection Function

Abstract

The invention relates to an automobile electric power steering system with an intelligent overload protection function. According to the system, the steering operation hand feeling of a driver is not affected during the switching process of starting or stopping of the overload protection function, and the intelligent overload protection function is applicable to all brush electric power steering systems (hereinafter referred to as EPS). Three input parameters of steering hand power signals (Ts), speed signals (V) and theoretical target current (I) are correlatively designed by the designed and developed EPS system, so that an electronic control unit (ECU) of the EPS system can automatically judges whether the system is overloaded, and automatically decides an ignition at a proper time according to the existing overload situation, the electric current output by the ECU is reduced gradually by bounded control, power torque is reduced and the intelligent overload protection ability of the EPS is realized; and the overload protection for a recycling ball-type or gear and rack type mechanical steering device is implemented and the safety of the steering system is enhanced.

Description

technical field [0001] The invention belongs to the technical field of automobiles, and relates to a brushed electric power steering system (abbreviated as EPS), in particular to an electric power steering system with an intelligent overload protection function. Background technique [0002] Automotive electric power steering system is mainly composed of mechanical steering gear, torque sensor, vehicle speed sensor, electronic control unit (ECU for short), power steering motor (EPS motor for short), mechanical deceleration mechanism and so on. Among them, the torque sensor is installed on the steering shaft to detect the driver's steering hand force and output the torque signal Ts; the vehicle speed sensor is used to detect the vehicle speed and output the vehicle speed signal V; the electronic control unit is the EPS system to realize various control functions. The core, according to Ts, V and other signals, conducts comprehensive calculation and processing, and sends a dri...

AI Technical Summary

Problems solved by technology

While the EPS system provides power assist torque to reduce the steering hand force, it will cause the driver to continue to increase the steering hand force in order to achieve the steering target under special working conditions, so that the EPS output torque will be greatly improved after being superimposed. At this time, without the driver's knowledge, the mechanical steering gear will be overloaded and damaged, causing the car to fail to turn.

For this reason, the countermeasure of the traditional EPS system is to control the overload by keeping the power assist torque no longer increasing after the steering hand force Ts exceeds a certain value in the design of the basic power assist current characteristics. However, this measure only limits the increase in the power assist torque. When the steering hand force is too large, the EPS output torque will be superimposed, which will still cause the mechanical steering gear to be overloaded and damaged.

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