| Summary: | 碩士 === 國立中興大學 === 農業機械工程學系 === 89 === Currently, most of engine technicians utilize the compression pressure meter, vacuum gauge and air flow gauge to diagnose the intake valve leaking problem for four-stroke engines. Using these tools are found either not convenient or less accuracy for minor leakage.
The electronic oscilloscope, which is generically equipped in modern automotive workshop, was used in this research associated with the manifold absolute pressure sensor (MAP) installed on modern vehicles to observe the vacuum pulse variation in an intake manifold when a intake valve leaking problem occurred in an four-cylinder-four-stroke engine. Based on the findings, one could study the relation between intake valve leakage quantities and waveform’s spikes captured by an electronic oscilloscope. The study, thus, expected to find those intake valve leaking problems by studying their waveform.
The results showed that the waveform’s spikes captured by an oscilloscope having linear relation with the quantity of the intake valve leakage. The average value of R2 was calculated to be 0.985. To verify the effect of measuring locations, one way ANOVA analysis was used. Results showed that the F value was less than 3.49 for each location. That is, measuring locations did not affect the leaking measurements significantly. Thus, applying an electronic oscilloscope to detect the leaking problem in intake valves of a four-cylinder-four-stroke engine is possible. In addition, by appropriately arranging electronic oscilloscope’s trigger source, the linking intake valve could be precisely identified.
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