Research Of The Wavelet Analysis In The Noise Signal Of Hydraulic Power Steering Pump

Hydraulic power steering pump is an important device of the modern car, it play a crucial role in ensuring the safety and stability of the car. The steering pump is the "heart" of the hydraulic system., it works rotationally, emits vibration and noise. The noise is not only a sort of pollution, but also some kind of the information carrier, it contains the useful information of the equipment operating status. Measuring and analysis the noise signal effectively can find out the equipment operating status, and the noise generation mechanism.In this dissertation, We overview the basic theories and concepts of the acoustic, Introduce some basic physical quantities, the basic law of wave propagation, the basic model of the sound field, synthesis and decomposition of the noise. Summarize the knowledge of Vane-type hydraulic power steering pump noise. Analyze the structure and the principles of the pump. Elaborate the generation mechanism and the transmission of noise, Introduce some noise measurement methods, including the fundamental, the instruments, the error analysis method, and some traditional signal analysis methods such as spectrum analysis, power spectrum analysis, cepstrum analysis etc. Focus on Wavelet transform in singularity detection, signal noise separation and fault feature extraction. Made a theoretical preparation for the experience.In the experience stage, We according to GB/T1748, tested a Vane-type hydraulic power steering pump in Semi-anechoic environment. Using the Sound intensity measuring instrument measured the noise signal and the sound power. Analyzed and reconstructed the signal, Denoising and Extracted Singular Signal using the wavelet. Experimental results show that the wavelet is useful in extract the signal characteristic frequency. This dissertation has great significance in rotating machinery noise signal analysis.