困油时外啮合高速润滑泵全齿面油膜厚度计算

Calculation of Oil-film Thickness on Full Tooth Surface in External Gear High-speed Lubrication Pump with Regard to Trapped-oil Pressure

为把握困油压力和油膜两端压差以及与众不同的液压载荷,如何影响外啮合高速润滑泵齿面的最小油膜厚度,先从直齿齿轮传动的几何关系和刚性等黏度润滑理论入手,建立出包含初始压差的最小油膜厚度及油膜破裂点位置的计算式。实例的结果表明:困油压力造成了载荷的较大波动,甚至出现负值载荷;困油压力通过改变载荷和油膜两端压差来影响齿面的最小油膜厚度。总体上,困油压力以及油膜压差有利于改善齿面的润滑状态;困油时全齿面上的弹性参数和最小油膜厚度变化较大,刚度理论无法适用,并依据实际的弹性参数和黏性参数选自合适的公式再计算油膜厚度等;得出外啮合高速润滑泵的齿面润滑确有别于常规的齿面润滑。常规齿面相关润滑理论在后续外啮合高速润滑泵的设计应用上,应予以修正。

In order to understanding trapped-oil pressure and pressure difference of the oil-film both ends as well as especial fluid load how to impact on the minimum oil-film thickness in external gear high-speed lubrication pump is presented.Firstly,from geometrical relationship of straight-tooth gear transmission and stiff-isoviscous lubrication theory,a new corresponding formula of minimum oil-film thickness included inlet pressure and outlet pressure and cracked-point position of oil-film were derived.All simulation results indicated that a large load fluctuations even negative load was caused by trapped-oil pressure;the minimum film thickness on the tooth surface was changed by the affected fluid load and the affected oil-film pressure difference by trapped-oil pressure,in general,the lubrication state of tooth surface would be improved because of the trapped-oil pressure and oil-film pressure difference.The elastic parameters and the minimum oil-film thickness in a full tooth surface cycle had a large change when trapped-oil pressure was presence.The stiffness theory could not be applied for the lubrication analysis of the tooth surface.And a suitable formula was selected to calculate the logical oil-film thickness in accordance with the actual elastic parameters and viscosity parameter,etc.Finally,the conclusion is summarized that the lubrication of the gear tooth surface in external gear high-speed lubrication pump is fully different from conventional gear,and relative lubricating theory derives from conventional gear must be corrected before applied to external gear lubrication pump.