困油压力对滑动轴承润滑状态的影响

为研究困油压力对轴承润滑状态的影响,在一个困油周期内,基于纯流体润滑状态设计要求,提出轴承-轴颈间所必需的承载量系数计算公式;依据泵样机参数,提出轴承-轴颈间所能提供的承载量系数的多项式拟合式;由所必需的承载量系数公式等于所能提供的承载量系数的定值优化方法,建立出困油压力与最小油膜厚度间的对应关系。通过一案例,对是否考虑困油压力的润滑状态计算结果进行比较和分析。案例分析结果表明:困油压力导致径向力增加45%～59%;导致最小油膜厚度降低19.6%～24.3%;困油压力造成轴承-轴颈间处于混合润滑状态,达不到原始的纯流体润滑状态设计要求。因此,困油压力对润滑状态影响较大,在泵轴设计中应充分考虑困油压力的影响,从而在结构上尽量缓解困油压力。

Influence of Trapped-oil Pressure on Lubrication State of Journal Bearing in External Gear Pumps

In order to study the effect of trapped oil pressure on lubrication state of journal bearing in external gear pumps,a formula for calculating the needed load carrying factors between bearing and journal based on the design requirements of all fluid lubrication state was established.A polynomial formula of provided load carrying factors by a prototype of a gear pump was fitted based the parameters of the prototype by Excel software.Through the zero value solution of the needed load carrying factors minus the provided load carrying factors tby the programming solver of Excel software,the corresponding relationship between the trapped oil pressure and the minimum oil film thickness on journal bearing was derived.The lubrication state of the journal bearing of a prototype of a gear pump was studied when considering and not considering the trapped oil pressure.The results of the prototype show that the trapped oil pressure causes the increasing of the radial force from 45% to 59%,and the decreasing of the minimum oil film thickness from 19.6% to 24.3%.The journal bearing is in mixed lubrication state because of the effect of trapped oil pressure,which can not meet the original design requirements of all fluid lubrication state.It is concluded that the oil trapping pressure has a great influence on the lubrication condition,the influence of oil trapping pressure should be fully considered in the design of pump shaft,so as to alleviate the oil trapping pressure as far as possible in structure.