Study on braking stability of commercial vehicles: An optimized air brake system

Abstract

The braking stability has significant importance for commercial vehicles, especially tractor-semitrailer. However, the brake lag of air brake system brings serious safety risk to the vehicle. To improve the braking stability of tractor-semitrailer, an optimized air brake system is proposed. Using characteristic of the fast exhaust response of spring brake cylinder of composite brake chamber, a normally open solenoid valve and a normally closed solenoid valve are connected with the spring brake cylinder of composite brake chamber of semitrailer to control the spring brake force, which responds more quickly than service brake force. A strategy is proposed to control the difference between the actual braking torque of the semitrailer brake and the target braking torque and is simulated based on AMESim and SIMULINK. An experiment is made to verify the effectiveness of the optimized system. The simulation shows that the improved scheme reduces the response time of semitrailer brake system by 0.19 s, and effectively restrains the lateral movement of the vehicle downhill braking and improves the stability of the braking direction of the vehicle. And the experiment indicates that the brake of semitrailer responds earlier than tractor, which means the brake lag is improved significantly.