Research On The Online Measurement Of Automobile Engine Speed Based On Vibration Analysis

Today, with the development of the automobile industry, cars are constantly updating and upgrading. The car engine's instantaneous rotational speed is a very important criterion to determine vehicle performance is good or bad. Vehicle detection and fault diagnosis technology,at the very beginning, was based on personal experience to judge,nowadays,a variety of testing instruments has been used.In addition,the state environmental protection departments require vehicle idling at a specified value in the exhaust gas detection. Based on this stable value, compare with the exhaust emission standards, judge whether the target vehicle exhaust, the instantaneous engine speed is the foundationWe carefully analyzed the traditional method of measuring vehicle engine speed, check out some domestic and foreign research results and methodologies of this field. This topics chosen for analysis the vibration signals of automobile engine to measure the engine speed, and compare with the traditional methods.This method needn't install any sensors inside the engine of the car, needn't split the machinery, no need to consider specific factors of various types of vehicles.After referring to a large number of books and materials about signal processing, this paper raised the method of correlation analysis in the time domain to filter and denoising, CZT transform in frequency domain to obtain accurate fundamental. Correlation analysis can test signal cyclecomposition, having a good noise suppression ability, improving the signal to noise ratio, highlighting the signal characteristics, and filtering Gaussian noise more batter; CZT transform can only analyze the section of the signal band, no need to consider the total signal band, which canmore clearly get the desired local frequency, bringing great convenience to the analysis for the local spectrum of vibration signals; At the same time, avoiding unnecessarily large computation, making the results more accurate frequency domain.In order to verify the correctness of the mathod, using MATLAB 7.0 software to simulate, the experimental results meet the requirements well.The next field test, use the vibration sensors for data acquisition, signal analysis and processing, to achieve real-time vehicle engine speed measurement. Finally, sum up the advantages and disadvantages of topics and proposed for future research directions.