Full Power Hydraulic Brake System Based on Double Pipelines for Heavy Vehicles

The hydraulic caliper disc brake system with air-over-oil is widely adopted at present for heavy vehicles,which makes use of air pressure system propelling the hydraulic pressure system acting on friction plates divided and combined for braking.There are some disadvantages such as pneumatic components failure,dust polluted and produce lots of heat in hydraulic caliper disc brake system.Moreover,considering the demands of the high speed,heavy weight,heavy load and fast brake of heavy vehicles,the full power hydraulic brake system based on double pipelines for heavy vehicles is designed and analyzed in this paper.The scheme of the full power hydraulic brake system,in which the triloculare cylinder is controlled by dual brake valve,is adopted in the brake system.The full power hydraulic brake system can accomplish steering brake,parking brake and emergent brake for heavy vehicles.Furthermore,electronic control system that is responsible for coordinating the work of hydraulic decelerator and hydraulic brake system is developed for different speed brakes.Based on the analysis of the influence of composed unit and connecting pipeline on braking performance,the nonlinear mathematic model is established for the full power hydraulic brake system.The braking completion time and braking pressure in braking performance of the double-pipeline steering brake and parking brake are discussed by means of simulation experiments based on Matlab/Simulink,and the simulation results prove that the braking performance of steering brake and parking brake meets the designing requirement of the full power hydraulic brake system.Moreover,the test-bed experiments of the brake system for heavy vehicles are carried out.The experimental data prove that the braking performance achieves the goal of the design,and that the full power hydraulic brake system based on double pipelines can effectively enhance braking performance,ensure braking reliability and security for heavy vehicles.

Implementable Strategy Research of Brake Energy Recovery Based on Dynamic Programming Algorithm for a Parallel Hydraulic Hybrid Bus

The purpose of this paper is to develop an implementable strategy of brake energy recovery for a parallel hydraulic hybrid bus. Based on brake process analysis, a dynamic programming algorithm of brake energy recovery is established. And then an implementable strategy of brake energy recovery is proposed by the constraint variable trajectories analysis of the dynamic programming algorithm in the typical urban bus cycle. The simulation results indicate the brake energy recovery efficiency of the accumulator can reach 60% in the dynamic programming algorithm. And the hydraulic hybrid system can output braking torque as much as possible.Moreover, the accumulator has almost equal efficiency of brake energy recovery between the implementable strategy and the dynamic programming algorithm. Therefore, the implementable strategy is very effective in improving the efficiency of brake energy recovery.The road tests show the fuel economy of the hydraulic hybrid bus improves by 22.6% compared with the conventional bus.