Ping, X., Wu, M., Tan, G., Pang, Y. et al., "On-Vehicle Engine Brake Performance Measurement System," SAE Technical Paper 2017-01-2499, 2017.
The engine brake is widely used as auxiliary braking device for its continuous braking torque. The engine brake performance is usually measured in the laboratory or proving ground as per relevant standards. The main purpose of this paper is to introduce an on-vehicle measurement system to measure the performance of the engine brake in the driving process, which can reduce the test times in the laboratory or proving ground and the test cost. Based on the vehicle longitudinal dynamics, the measurement system can match various vehicles without basic parameter calibration at installation. The measurement system can also estimate gross vehicle mass. First, the vehicle state information from CAN (Controller Area Network) bus and the road gradient from the gradient sensor are used to compute gross vehicle mass and relevant vehicle driving resistance coefficients by the vehicle longitudinal dynamics in the driving process. Then, the data fusion algorithm with simple structure and fast computation speed processes above computation results for more accurate results. Finally, these accurate results are used to deduce the relationship between the engine braking torque and the engine speed by the vehicle longitudinal dynamics during gear taxiing. Some vehicle tests are carried out to validate the effectiveness of on-vehicle engine brake performance measurement system. The measurement error of the engine braking torque is ranged from 3.6% to 6.7% within normal working speed range of the engine brake 1600 r/min to 2200 r/min. The measurement error of gross vehicle mass is 7.92%. The errors of the engine brake measurement system can satisfy the general requirements of the researches relevant to the engine brake performance. With the popularization of the on-vehicle measurement system, the engine brake performance test will not be confined to experimental places and at the same time, the test cost will be reduced.