Effects of Rolling Bearing Type and Size on the Maximum Eccentricity Ratio of Hydrodynamic Rolling Hybrid Bearings

Abstract

A hydrodynamic rolling hybrid bearing (HRHB) composed of a rolling bearing with a fixed clearance and a hydrodynamic bearing is developed to solve the wear problem in hydrodynamic bearings. In this study, the maximum eccentricity ratio is developed to assess the protection of the rolling bearing offers to the hydrodynamic bearing. An analytic model for the maximum eccentricity ratio is presented. The effects of the size of the ball bearing and cylindrical roller bearing on the maximum eccentricity ratio are investigated. The results show that the maximum eccentricity ratio is affected by the clearance constraint and contact deformation of the rolling bearing. The maximum eccentricity ratio presents itself at zero speed, at which the rolling bearing reaction is equal to the external load. The results also show that the type of rolling bearing has significant effects on the maximum eccentricity ratio. The increment of the maximum eccentricity ratio due to elastic deformation of ball bearings is about 8.6 times the increment due to elastic deformation of cylindrical roller bearings. In comparison, the size of the rolling bearing of the same type has a slight influence on the maximum eccentricity ratio. The maximum eccentricity ratio is a key parameter related to antiwear. When the maximum eccentricity ratio is smaller than the allowable value of the hydrodynamic bearing, direct contact between the hydrodynamic bearing and rotor can be avoided and the wear in the hydrodynamic bearing can thus be prevented by the rolling bearing.

KEY WORDS:

• Hybrid Bearings
• Combination Bearings
• Composite Bearings
• Antifriction Bearings
• Auxiliary Bearings
• Hydrodynamic Bearings
• Rolling Bearings