The structure and sealing principle of skeleton oil seal.

The skeleton oil seal is relatively simple, and generally consists of three parts: oil seal body, reinforced skeleton and self-tightening coil spring. The sealing body is divided into bottom, waist, cutting edge and sealing lip according to different parts. Usually, the inner diameter of the skeleton oil seal in the free state is smaller than the shaft diameter, that is, it has a certain "interference". Therefore, when the oil seal is installed on the oil seal seat and the shaft, the pressure of the oil seal cutting edge and the contraction force of the self-tightening coil spring will produce a certain radial tightening force on the shaft: after a period of operation, the pressure will decrease rapidly and even disappear. Loss, due to the surface: adding springs can compensate for Difeng's self-tightening force at any time.

Sealing principle: Since there is an oil film controlled by the edge of the oil seal between the oil seal and the shaft, the oil film has fluid lubrication characteristics. Under the effect of the surface tension of the liquid, the rigidity of the oil film just makes the oil film and the air contact end form a crescent surface, which prevents the leakage of the working medium and realizes the sealing of the rotating shaft. The sealing ability of the oil seal depends on the thickness of the oil film on the sealing surface. If the thickness is too large, the oil seal will leak; if the thickness is too small, dry friction may occur, causing wear of the oil seal and shaft; if there is no oil film between the sealing lip and the shaft, it will easily cause heat and wear . Therefore, when installing, you must apply some oil on the sealing ring, and at the same time ensure that the skeleton oil seal is perpendicular to the axis line. If it is not vertical, the sealing lip of the oil seal will drain the lubricating oil from the shaft, and it will also cause excessive sealing of the sealing lip. wear and tear. During operation, the lubricant in the casing seeps out a little to achieve the ideal state of forming an oil film on the sealing surface.