This paper investigates the relationship of voltage and current waveform between normal piezo injector and deterioration abnormal piezo injector. The experimental methods using Pico oscilloscope and GDS scan tool are employed to measure current and voltage waveform and fuel pressure of piezo injector. The experiment is carried out during no-load condition. A summary of the important results are as follows. 1) In case of normal injector, the fluctuation of duration time of piezo injector was linearly and regularly decreased with increasing engine speed, but the that of deterioration piezo injector was irregularly decreased with increasing engine speed. 2) In main injection, the peak value of the current waveform of abnormal injector was larger than that of normal injector, the duration time of deteriorated abnormal injector was less than that of normal injector at 800rpm and 1500rpm, but the duration time of deteriorated abnormal injector was larger than that of normal injector at 2000rpm and 3000rpm. This irregularity appears to be caused by the deterioration of the injector.

ABSTRACT
 1. 서 론
 2. 이론적 연구
  2.1 개요 및 작동원리
  2.2 피에조 인젝터의 전압과 전류 파형
 3. 실험장치의 구성과 방법
  3.1 실험장비
  3.2 실험 방법
 4. 실험결과 및 고찰
 5. 결 론
 References

• 유종식(Dept. of Automobile & Machinery, Daewon University College) | Jong-Sik Yoo
• 김철수(School of Mechanical and Automotive Engineering of Gangneung-Wonju National) | Chul-Soo Kim Corresponding Author