Study On The Injection Flow Meter

As one of the most advanced diesel injection systems, high pressure common rail injection system can control the injection volume and times per cycle with a high precision. As a result, the fuel consumption and the emission can be reduced greatly. The injection flow meter can measure the injection volume and the injection rate, especially analyzing the multiple injections per cycle. It is obvious that the injection flow meter is necessary for researching and applying the high pressure common rail injection technique. With the rapid development of native common rail injection system and the popularization of foreign common rail injection system, the demand of the injection flow meter will continue to increase.After investigating the development status of the injection flow meter, the system measurement scheme was confirmed and following researches were done.The system structural design was completed based on the displacement measuring principle and the partition of three function modules (Upper Body, Middle Body and Lower Body). Following the system function requirements and specification requirements of the injection flow meter, IC models were selected and the system circuit was drawn. According to the system sequence, the flow chart of injection measurement was drawn and then the software of host computer and slave computer were also designed.Piston-cylinder is the fuel measurement unit of the injection flow meter and plays a crucial role in the system measurement accuracy. According to the system design requirement, the structure of piston-cylinder was designed. Using Fire CFD software, the structure of piston-cylinder was improved to reduce the influence of the leakage. To avoid the situation that the piston was locked with the cylinder, an anti-heat cover was installed. The effect of improvement was also proved by means of ANASYS analysis. The circuit was modified to eliminate the high-frequency interference of displacement signal. As well as, the Kalman filter was used to remove random noise. As a result, the injection flow meter has high system measurement accuracy now. Finally, many experiments were carried out to analyze the effect of structural improvement and interference filtering as well as the achievement of system function requirements and specification requirements. As a result, the measurement accuracy of the injection flow meter is±0.1% FSO. The ability to measure multiple injections and injection rate are also proved in the experiments.