Integration analysis model of oil-charging system about parallel hydraulic retarder and its response characteristic

Abstract

As a auxiliary braking device in vehicle’s downhill process, parallel hydraulic retarder has strict requirements for its rapidity of response performance and accuracy of braking torque. The parallel hydraulic retarder uses high-pressure gas as the control medium, which pushes the oil into the working chamber through the high-speed on/off valve. Because the oil filling process of the chamber is an indirect process, the complicated gas–liquid movement during the oil filling period affects the accuracy and response of the braking process. In this paper, the mechanical characteristics of high-speed on/off valve had analyzed by computational fluid dynamics. The oil filling system’s characteristics has analyzed, which had verified by experimental data. Compared with the three dimensional method to directly analyze the response process of the oil charging and discharging system, it has the characteristics of simplicity and fast calculation.The modeling method used in this paper is mainly suitable for hydraulic system which uses air pressure and liquid as control medium. This integration model can obtain the characteristics of valve group more accurately and has certain novelty rather than Theoretical formula calculation. Then the influence of different control pressure and input speed on transient braking response has discussed and analyzed. The results has showed that the shortest opening response time is 1.49 s when the control pressure is 3.2 bar. With the decrease of the oil amount and speed, the oil-discharging response time increases gradually. When the speed is 1800 rpm and the liquid filling rate is 25 %, the oil discharge time reaches 5.48 s.

Keywords

• Hydraulic retarder
• High-speed on/off valve
• Transient braking performance
• Computational fluid dynamics
• Torque characteristics