Application Of Engine Brake Technology On CA6DL Diesel Engine

Modern heavy duty trucks become more and more powerful and run faster and faster, while their interior friction decrease dramatically. Thus braking capacity leads to lower significantly. At the meantime, vehicles total weight increasing, braking requirement cannot be met only by its own active braking system during high speed under heavy load circumstances. In order to ensure its safety performance, auxiliary braking instrument (ABI in abbreviation) must be installed on them. Many countries such as Germany, France and Swiss, etc, have already adopted ABI as compulsory device in their commercial vehicles.Engine braking is the most important and widely used because of its high braking efficiency, low cost and reliability.This article will introduce engine braking technology and its working principle, especially nowadays application on FAW's CA6DL engine.In 2004, FAW research and develop its own heavy duty diesel engine, CA6DL, mainly assemble on J5P truck. According to customers and market requirement, FAW decide to cooperate with Jacbos for engine braking system development. In the course of co-development with Jacbos, we conclude FAW own development process for engine braking system.According to our calculation, J5P truck needs about braking power 211kw. CA6DL engine choose leakage style braking system to meet actual situation. Through GT-power program analysis, braking power of 200kw can be achieved at 2500rpm, which is close to 211kw. Its specific braking power is close to bench-marking engine of compression style.According to the development process, we carry out the following works, matching design to CA6DL, finite element analysis (FEA) to new components and changed parts. As result, braking body, exhaust valve arm and cylinder head frame are correct not only in structure, but also safety requirement. In the meantime, DFMEA to these components and parts shows max number is below 80, which means no potential risks.According to the development process, complete verification test of performance and reliability to the CA6DL engine braking instrument have been conducted. Firstly, at 2100rpm of CA6DL2-35 engine, total braking power is 144.1kW, at 2500r/min, it is 201kW, when exhaust braking, exhaust back pressure lower than 400kPa. These results close to the target(max braking power 211kW). Engine durability test aims at verifying its reliability. This test is conducted through 2 connected engines: one for working while another for braking. In the test, temperature, parameters such as oil pressure, exhaust back pressure, intake pressure are monitored. The test process as follows: 30minutes for working, 30minutes for braking at max power point or at max torque point. The test cycles last for 1000 hours. 5 months test shows the engine can work 1000 hours without any failure.The CA6DL engine is assembled on the J5P JIEFANG truck, its type is CA4252P21K2T1B with 6X4 for braking bench test. Compared with relative curve provided by Jacbos, our ca6dl specific braking power has already reached an ideal level. Road test is mainly for slide test comparison under all working conditions: measure its slide distance, speed and braking speed, calculate its driving resistance when sliding. The test curve shows that when engine speed at 2300r/min, braking power reaches 206kW. The truck speed lowers quickly after engine braking added. For our engine braking system mainly used in mountain area slope road, in order to verify its performance, the truck test is designed to do on long slope road in Yunnan province. This test results 4.8% decrease in braking time, reduce 9 times in braking operation, down about 16.7%. The conclusion is that Engine braking system functions apparently during long slope-down road.To verify its actual efficiency of the system, the project team launched 8 trial trucks last year Sanming in mountain area, Fujian province. The truck drivers feedback after one year operation, using the system brings them saving greatly braking shoes, while increase truck's safety. They already benefit by saving cost nearly 15000RMB per year.The successful co-development of CA6DL engine braking technology between FAW and Jacbos will be applied to FAW trucks not only for the present , but also in future.