Control method of electronically controlled hydraulic power steering system with variable transmission ratio function

Abstract

The invention discloses an electronically controlled hydraulic power steering system having a transmission ratio changing function and a control method thereof. The electronically controlled hydraulic power steering system having the transmission ratio changing function comprises a steering mechanical unit, a valve-controlled electro-hydraulic position servo unit, a rotary valve opening degree regulating unit and an electronic control unit (ECU) which are connected in sequence, wherein the valve-controlled electro-hydraulic position servo unit provides an additional turning angle during automobile turning to change the transmission ratio of the turning angle of a steering wheel to the turning angle of front wheels and enhance the running stability of an automobile, a steering counter torque brought by the additional turning angle is factored into calculation of steering assist power, and the rotary valve opening degree regulating unit regulates the rotating speed of an oil pumping motor and the opening degree of a rotary valve according to a sensor signal and the steering counter torque. The valve-controlled electro-hydraulic position servo unit and the rotary valve opening degree regulating unit jointly complete control of the steering assist power and enable the electronically controlled hydraulic power steering system having the transmission ratio changing function to provide better steering road feeling and higher steering economical efficiency while improving the handling stability of the automobile and reducing the burden of a driver.

Description

technical field [0001] The invention relates to a power steering system and a control method thereof, in particular to an electronically controlled hydraulic power steering system with a variable transmission ratio function and a control method thereof. Background technique [0002] At present, electronically controlled hydraulic power steering system has been widely used in automobile power steering. According to the driver's steering operation, the system can apply variable steering assistance by means of the hydraulic power assist system to reduce the driver's steering burden. However, the transmission ratio of the existing electronically controlled hydraulic power steering system is fixed, that is, the ratio of the driver's steering wheel input angle to the front wheel angle is always constant, which cannot be used for various problems encountered by the car during driving. Therefore, the steering sensitivity when the car is running at low speed and the stability of the...

AI Technical Summary

Problems solved by technology

In actual use, the energy loss at the rotary valve accounts for a large proportion of the energy loss of the steering system. During optimization, it was found that the energy consumption of the steering system varies greatly under different rotary valve angles. In the power steering system, the rotary valve angle is linearly controlled by the steering column, and it is difficult to obtain the optimal economical rotary valve angle, which greatly limits the improvement of automobile steering economy

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