Research Of An Intellectual Oil Measuring Instrument Of Fuel Injection Pump Test-bed

This paper introduce the design of a high precision fuel injection measuring system based on the research to a oil pump test-bed intelligent quantity system.This system has the function to measurement injection quantity intelligently. A indispensable equipment to adjustment or inspection a diesel injection pump. This system provide important theoretical basis and test base to perfect the fuel injection system and optimize the control of fuel injection law.This paper present the situation of the development of injection pumps both in China and abroad, and introduce the principles of several kinds of measuring systems(such as cylinder method, image processing method, Zeuch method and the lift of injector needle-valve method), and analyze some problems.The paper introduce the design principle and related software and hardware of a high precision measurement oil system was designed taking a LVDT displacement sensor and an ATmega128 single chip. A contrast test is conducted on the 12PSDB75 pump test-bed at different speed.The system consists of oil measuring instrument and signal acquisition and processing system. The oil measuring instrument designed according to the principle of displacement method. For the high precision requirements, before design the cylinder, the accuracy of cylinder is analyzed, then chooses the proper radius and length. Signal acquisition and processing system consists of speed acquisition circuit, temperature testing modules, displacement signal A/D circuit, serial communication circuit, electromagnetic valve drive circuit and digital pipe display circuit. The measurement data through a serial port send to PC. A serial communication procedures and measurement system control and display interface programmed by c++in PC.The fuel injection quantity calculate by the displacement value multiply the sectional area of plunger, then make temperature correction. The precision of displacement sensor make a prominent influence in fuel injection quantity. The limiting resolution of LVDT displacement sensor are 0.01μm. In order to eliminate the signal disturbance, the integrated circuit hardware of gathering displacement signal employ RCπstyle wave filtering circuit, the program of software employ the middle value method of wave filtering.Finally, through the experimental detection and data analysis, proved the measurement svstem accurate and reliable.