Dynamic Characteristics Analysis Of Axial Piston Pump Slipper Pair With Wear Fault

As one of the typical displacement fluid machinery,axial piston pump is through relative motion of internal components to achieve oil suction and extrusion,which makes that there are many friction pairs in its interior.Slipper pair is the joint between swash-plate and piston.For a long period under the friction condition of high relative speed and high contact pressure,slipper is one of the parts that are prone to failure.And it is also the key factor that affects the service life,restricts the development towards high pressure and high speed of axial piston pump.For a long time,domestic and foreign scholars have focused on the dynamic characteristics of axial piston pump in the normal service stage.But the dynamic characteristics,with the wear fault,are different from the normal state.So in the paper,the dynamic characteristics of the slipper pair with different wear failure degrees and the effect of wear on the dynamic parameters of the pump were analyzed.Considering development mechanism of slipper pair wear fault,the description equation of slipper wear profiles was presented,and was used to be wear correction quantity to establish oil film thickness model.Based on the kinematic analysis,force Analysis and the working principle analysis of the slipper pair,the force/torque balance equation and the flow balance equation are obtained.And combined with the pressure control equation,the dynamic model of the slipper pair wear fault was established.The optimized result of model was got through MATLAB software and the effects of wear loss on the pressure distribution lift force,anti-overturning torque and the minimum film thickness were obtained.In view of the structure of the axial piston pump is so complex and the unknown parameters are so multiple that it is difficult to get the exact solution of the dynamic mode.So,the influence of the key parameters change on the overall dynamic characteristics of the pump was studied by using the operational modal analysis method.Considering the excitation characteristics of axial piston pump,the Op.PolyMAX method is used to iden-tify the multi modal parameters including harmonic modals and the time domain signals corresponding to the modal frequencies were separated by using the Morlet wavelet band-pass filter.Then based on the statistical characteristic differences of random response and harmonic response,the harmonic modes caused by the rotational frequency conversion were eliminated successfully,and the effective identification for the multi-operational modal parameters was achieved.Finally,by comparing and analyzing the modal parameters of normal and fault states,the feature extraction of the slipper pair wear fault was realized.