Wheel-Cylinder Hydraulic Pressure Control of Integrated-Electro-Hydraulic Brake System Without Pressure Sensors

Abstract:

The electro-hydraulic brake-by-wire system is the mainstream solution for next-generation automotive brake systems, whose wheel-cylinder hydraulic pressure control is the basis to achieve active safety functions such as vehicle stability control. In view of the cost and redundancy of the integrated-electronic-hydraulic brake system with a four-valve structure, a wheel-cylinder hydraulic pressure control strategy without pressure sensors is proposed. Through the bench test, the working characteristics of the hydraulic control unit were analyzed. A method for estimating the hydraulic pressure of the wheel cylinder is developed based on the combination of Bernoulli equation and PV characteristics. The solenoid-valve control logic and balance control strategy are designed for wheel-cylinder pressure regulation based on depressurization priority. The experimental results show that the root-mean-square error of the pressure control in this method is within 0.21MPa, which is equivalent to the control accuracy of the scheme with a hydraulic pressure sensor.

Key words:electro-hydraulic brake system;wheel-cylinder hydraulic pressure control;wheel-cylinder hydraulic pressure estimation;four-valve hydraulic control unit