高压高转速服役特征下唇形油封失效机制

坦克车综合传动系统中油封经常处于高压、高转速的工况,出现短时失效泄漏且在工况条件降低后密封性能恢复。针对这一问题,以唇形油封的泵汲理论作为其失效评判标准,首先,通过分析不同介质压力下油封的变形特征和接触特性,发现油封受压后腰部向轴侧塌陷、唇部翘曲,导致其接触宽度增加、最大接触应力减小,不利于产生或失去泵汲效应;其次,基于高速下油封摩擦升温现象,指出转速增加使油封橡胶材料的弹性模量下降,导致油封的抵抗变形能力减弱,其受压时腰部变形量增大;最后,对高压高转速服役特征下的油封进行分析,发现转速作用下油封升温导致其腰部抵抗变形能力下降,同时施加介质压力后加剧其腰部的塌陷程度,降低其工作可靠性,进一步得出了油封的可靠介质压力与转速之间的匹配关系。研究成果可为设计优化耐高压高速油封及油封选型提供参考和理论支持。

Failure Mechanism of Lip Seal Under High Pressure and High Speed Service Characteristics

The oil seal in the integrated transmission system of tank vehicles is often in high pressure and high speed conditions. Short-term failure leakage occurs and the sealing performance is restored after the working condition is reduced. In order to solve this problem, taking the pumping theory of oil seal as its failure criterion. Firstly, by analyzing the deformation characteristics and contact characteristics of oil seal under different pressures, it is found that the axial side of the waist collapses and the lip ‘warping’ after the oil seal is compressed, resulting in the increase of contact width and the decrease of maximum contact stress, which is not conducive to the generation or loss of pumping effect. Secondly, based on the phenomenon of temperature rise of oil seal friction at high speed, it is pointed out that the increase of rotational speed decreases the elastic modulus of oil seal rubber material, resulting in the weakening of the resistance to deformation of oil seal, and the increase of waist deformation under compression. Finally, the oil seal under the service characteristics of high pressure and high speed is analyzed. It is found that the temperature rise of the oil seal under the action of the rotational speed leads to the decrease of its waist resistance to deformation. At the same time, the application of pressure intensifies the collapse of its waist and reduces its working reliability. The matching relationship between the reliable pressure and the rotational speed of the oil seal is further obtained. The results can provide reference and theoretical support for the design and optimization of high pressure and high speed oil seal and the selection of oil seal.