Behavior of Deceleration Conscious Pressure Reducing Valve in Automobile Brake System 2005-01-3140
Hydraulic brakes are widely used in passenger cars and light commercial vehicles. Rear wheel locking ahead of front wheels creates vehicle instability and is considered most dangerous and illegal. This is prevented by using valves in the brake system and by proper brake component selection. A deceleration proportioning (GP) valve senses the deceleration of the vehicle and modulates the rear brake pressure. The valve under investigation has failed to meet the regulatory requirements of Bureau of Indian Standards (BIS) 11852; hence, the performance of a GP valve was studied experimentally in static and dynamic conditions of the vehicle. It was found that the valve is sensitive to the rate of pedal application. An analytical model was developed to predict the displacement of the ball under different rates of pedal application and at different decelerations. As the displacement of the ball in the valve cannot be measured, performance of the valve was compared based on the pressure with reference to the time. It was found that there is a good agreement between the analytical and experimental values. From the parametric study, it was found that the gap between the ball and valve seal influences the valve performance. By increasing the gap by dishing out the flow plate, the performance of the valve was found to be satisfactory and the brakes meet the BIS specifications.