Researches Of Measuring System For Diesel Engine Injection Rate

The fuel injection system of diesel engine was considered as its "heart", the whole machine’s reliability and life was directly determined by the performance of the fuel injection system. With the increasingly shortage of energy resource and the stringent exhaust emission standards, the topics of reducing oil dependence, climate change and increasing energy sustainability have been the prime drivers in the automotive industry. The rate at which the fuel is introduced into the combustion chamber determines the quality of combustion. Hence, the rate of injection is an important parameter to obtain, also knowing the characteristics of the fuel injection rate is extremely important in designing the engine.This paper firstly investigate the development status of the rate of injection system both in China and abroad, and secondly introduced several kinds of principles of measuring system, including cylinder method, Zeuch measuring method, Bosch measuring method, the lift of injector needle-valve method and so on. After studying several typical injection flow meter aboard, the system measurement scheme was confirmed. According to the principle of Zeuch method, a high precision injection rate measurement system was designed, taking a piezoelectric pressure sensor and an ATmegal28single chip. A contrast experimental was conducted on the pump test-bed.The system structural consist of two parts, mechanical part and signal acquisition and processing part. Electromagnetic valve, piezoelectric pressure sensor, temperature sensor were selected according to the requirement and they were located on the mechanical body. Also a constant volume chamber was designed. Signal acquisition and processing system consists of temperature testing circuit, high speed electromagnetic valve drive circuit, pressure signal A/D circuit and serial communication circuit and cam position acquisition circuit. Following the system function requirements, several important microchips were selected. In order to eliminate the signal disturbance, the integrated circuit hardware of gathering pressure signal was designed. According to the flow chart of injection measurement, the software of host computer and slave computer were designed.Finally, through the experimental on the12PSDB75pump test bench and data analysis, the results show that the system designed in this paper can measure the fuel injection rate and achieved the initial goal.