Analysis Of Support Character On Journal Bearing Of Full Water Lubricating Axial Piston Pump

There are many researches on water lubricating piston pump at home and abroad,however most of them are concentrated on the analysis of lubrication characteristics of these three key friction pairs as well as their material selection of friction pairs.There are few studies on the journal bearing of water pump.In fact,the journal bearing is the main bearing part of the water pump.It has high pv value,poor lubrication condition and large local heating.Its supporting characteristics directly affect the performance and life of the pump.In the past,experimental studies on water-lubricated bearings mostly have been carried out mostly by building a load system to simulate the load conditions of bearings.Thus experimental results are difficult to accurately describe the friction,lubrication,and support characteristics exhibited by the bearings under actual operating conditions.In this paper,the water pump is directly used as a test subject to test the pressure distribution and the thickness of water film of journal bearing under real conditions.The specific work of this paper is as follows:According to the structural characteristics of the water pump,the pressure flow model of the pump is established to get the loads of the journal bearing under different working conditions.The full fluid dynamic pressure lubrication of journal bearing is modeled and solved by MATLAB programming,and the pressure distribution of the water film in journal bearings under different working conditions and the vortex trajectory of the center of the cylinder are obtained.The calculation results show that the area of dynamic pressure in the journal bearing water film is very small,and the pressure peak is generally large.With the increase of loading pressure,the dynamic pressure generated by the journal bearing water film increases rapidly,also with the speed of the water pump,there is also a slight increase of the dynamic pressure.The experimental measurement system is built by installing pressure sensors and displacement sensors on the pump,and by observing sensors to measure the dynamic film pressure distribution of the large pump bearing under different working conditions and the center vortex of the cylinder.Compared with experiment and simulation results,it is found that the journal bearing of the HPP80 pump is in a mixed lubrication state,that is,hydrodynamic lubrication and micro convex body contact exist simultaneously,and the supporting force generated by the dynamic pressure of the water film is much smaller than the contact pressure.Under the same loading pressure,with the decrease of the pump speed,the dynamic pressure in the journal bearing reduces,and the vortex trajectory gradually shifts outwards.Meanwhile,the contact force between the cylinder block and the journal bearing increases.Under the same speed,with the increase of the loading pressure,the center of the vortex moves slowly to outward,and the dynamic pressure value in the water film increases first and then decreases.When the pump pressure exceeds 8MPa,the dynamic pressure lubrication effect becomes worse.The research results in this paper reveal the lubrication state of the journal bearing in which fluid lubrication and boundary lubrication coexist under real operating conditions.The relationship between its support characteristics and working condition parameters is obtained,which lays a theoretical and experimental basis for the design of the journal bearing in water pump.