1.潍柴动力股份有限公司，山东 潍坊 261061；2.一汽解放青岛汽车有限公司，山东 青岛 266000；
3.潍柴动力空气净化科技有限公司，山东 潍坊 261061
Abstract：In order to improve the braking performance of a natural gas engine and ensure driving safety, based on the analysis and study of different engine auxiliary braking methods, the compression release braking in cylinder is determined.The parameters such as valve lift, contact stress of camshaft tappet and engine braking power are tested on a natural gas engine equipped with in cylinder compression release brake, and the braking power of diesel engine and natural gas engine with the same displacement are compared. The vehicle road test is also carried out to test the braking performance of in-cylinder compression release braking system. The results show that the natural gas engine equipped with cylinder compression-release braking system can effectively increase the braking power, reduce the vehicle speed and controllable in the process of downhill. The braking efficiency of natural gas engine is 9.3% less than that of diesel engine with the same displacement. Using pedal brake-cylinder compression release brake, the use frequency of the pedal brake is 68.1% less than that of the pedal brake only, 57.8% less than that of the pedal brake-exhaust butterfly valve brake. The compression release braking system effectively prolongs the downhill driving time of the vehicle and makes braking safer.
Keywords:natural gas engine;cylinder compression release brake; valve lift;contact stress;brake power