Research On Measuring The Thickness Of Plunger Oil Film Of Diesel Fuel Injection Pump Based On Ultrasonic

Lubrication is one of the important conditions to ensure the normal operation of machines,and accurate measurement of lubricating oil film thickness has an important reference role in assessing the lubrication effect and has important application value in industrial production.In this paper,the plunger coupling of a single-cylinder diesel engine injection pump is used as the research object in the ultrasonic measurement oil film thickness test,and the plunger oil film thickness is measured using ultrasonic technology.The study firstly establishes the ultrasonic measurement theoretical models,namely the resonance model theory and the spring model theory.The device is designed in the ultrasonic calibration test,and the construction of the plunger thickness measurement device and wedge thickness measurement device is completed,and the given oil film thickness is measured in the test to complete the calibration test of ultrasonic measurement of oil film thickness.Secondly,in view of the problem of superimposed noise in the ultrasonic probe acquisition signal in the calibration test,the method of wavelet noise reduction processing of the acquisition signal is proposed.The test shows that compared with the traditional noise reduction,wavelet noise reduction can better extract the main part of the signal and is less affected by noise.Therefore,in the experiment,wavelet noise reduction is applied to the oil film signal,and then the signal is processed by fast Fourier transform to obtain the time domain and spectral maps of the oil film reflection signal,and the oil film thickness measurement value is obtained by calculation.Again,the ultrasonic measurement of the injection pump plunger device structure design,in the actual situation of the injection pump in reciprocating motion,measurement of the dynamic plunger oil film thickness is closer to the real value,so the plunger measurement device design has the function of driving the plunger reciprocating motion,combined with the functional requirements of the plunger measurement device and the structural dimensions of the injection pump,the measurement device for two-dimensional drawing design and three-dimensional simulation structure design The design and construction of the measuring device is completed.Finally,ultrasonic measurement of plunger oil film thickness under static and dynamic conditions is carried out,and wavelet noise reduction processing is performed on the collected signals.According to the spring model theory and using MATLAB software to process the data to obtain the relationship between the incident frequency and the oil film reflection coefficient,and calculate the plunger oil film thickness results.Comparing the experimental results,it can be seen that the ultrasonic measurement combined with wavelet noise reduction makes the measurement results optimized.