Tapered Roller Bearing Retainer with Convex Guide Surfaces
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Solution Overview
Problem
Tapered roller bearings experience increased rotation torque due to shear resistance of oil between the rollers and the retainer's guide surfaces, which is not effectively reduced by existing retainer designs, especially when combined with tapered rollers having straight generating lines on their rolling surfaces.
Innovation Solution
A retainer design featuring crossbars with smoothly convex guide surfaces that are tapered and have recessed surfaces, allowing for reduced contact lengths and oil flow passages, thereby minimizing shear resistance and rotation torque. The guide surfaces are designed to have a maximum protruding amount shorter than the rolling surface central portion, and the recessed surfaces facilitate quick oil flow between the inner and outer races, reducing stirring resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the guide surfaces are made straight in the longitudinal direction of the crossbars, then the manufacturing is simpler, but the contact length with the tapered rollers becomes large, increasing shear resistance of oil and rotation torque
Solution Approach 1:
The guide surfaces are formed with a convex curvature in the longitudinal direction of the crossbars, specifically with a radius of curvature R where 0.05D ≤ R ≤ 0.2D (D being the average diameter of the tapered roller). This curvature reduces the contact length between the guide surfaces and the tapered rollers, thereby reducing the shear resistance of oil and the rotation torque of the bearing, while still being manufacturable through standard forming processes
2Loss of energy
If the guide surfaces are made convex to reduce contact length, then the shear resistance of oil is reduced, but the manufacturing precision becomes more difficult to control
Solution Approach 1:
The patent specifies precise parameter ranges for the convex guide surfaces, including the radius of curvature R (0.05D ≤ R ≤ 0.2D) and the position of the apex portion. These controlled parameters allow the guide surfaces to reduce oil shear resistance while maintaining manufacturability and quality control through standard production tolerances
3Loss of energy
If recesses are added to the crossbars to allow oil flow, then the stirring resistance of oil is reduced, but the device complexity increases
Solution Approach 1:
The crossbars are segmented with recesses (cutouts) formed in the annular portion, which divide the oil flow path and allow oil to quickly flow from the inner race side to the outer race side. This segmentation reduces the stirring resistance of oil while the recesses are integrated into the existing crossbar structure, minimizing additional complexity
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The retainer effectively reduces the shear resistance of oil and rotation torque by minimizing contact lengths between the guide surfaces and tapered rollers, and by optimizing oil flow, resulting in improved bearing performance.
Implementation Method 1
the crossbars of the retainer have guide surfaces that are circumferentially brought into contact with the tapered rollers in the pockets. This increases the shear torque (or shear resistance) of oil between the tapered rollers and the guide surfaces
Implementation Method 2
Some other conventional retainers have recesses in the shape of cutouts formed in the annular portion of the retainer on its small-diameter side to allow oil that has flowed through a gap between the retainer and the inner race into the space between the retainer and the inner race to quickly flow into the space between the retainer and the outer race, thereby reducing the stirring resistance of oil
Implementation Method 3
The guide surfaces are smoothly convex in the longitudinal direction of the tapered rollers... Each guide surface has a protruding portion having a maximum protruding amount toward the rolling surface central portion of the corresponding tapered roller, the protruding portion being shorter, in the longitudinal direction of the tapered roller, than the rolling surface central portion of the tapered roller
Data Source
AI summary
A retainer of a tapered roller bearing includes crossbars having guide surfaces which circumferentially contact the tapered rollers. The crossbars are also formed with first recessed surfaces and second recessed surfaces which are both in the form of cutouts circumferentially recessed from the respective guide surfaces to reduce stirring resistance and shear resistance of oil. To reduce the contact lengths between the rolling surface central portions of the tapered rollers and the guide surfaces, the guide surfaces are smoothly convex in the longitudinal direction of the tapered rollers.