Tapered Roller Bearing Profile to Reduce Edge Pressure and Skew
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Solution Overview
Problem
Tapered roller bearings used in automobile transmission pilot and idler portions experience excessive edge surface pressure and skew due to misalignment, leading to fretting wear and reduced lifespan, which existing designs fail to adequately address at low manufacturing costs.
Innovation Solution
A tapered roller bearing design featuring elongated rollers with a significant straight portion in the axial center and logarithmic crowning at both ends, optimizing the ratio of roller length to diameter and crowning drop amount to reduce edge surface pressure and prevent skew, while maintaining low manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If large crowning is formed on the tapered roller to counteract edge surface pressure, then edge surface pressure is reduced, but the contact width between the rolling surface and raceway surfaces becomes smaller, making the tapered roller more liable to skew
Solution Approach 1:
The patent applies different surface treatments to different regions of the tapered roller: logarithmic crowning is applied only to the end portions (local regions) while the central portion maintains a straight profile. This local quality approach allows the end portions to counteract edge surface pressure through crowning, while the straight central portion maintains adequate contact width to prevent skew, thus resolving the contradiction between reducing edge pressure and maintaining skew resistance.
2Stress or pressure
If the ratio of roller length to diameter is increased to reduce edge surface pressure, then edge surface pressure is suppressed, but manufacturing complexity and cost increase
Solution Approach 1:
The patent optimizes the L/Dw ratio to 1.7 or more, which is a specific parameter change that balances edge surface pressure reduction with manufacturing feasibility. Additionally, the logarithmic crowning is applied only to the end portions rather than the entire surface, which reduces manufacturing complexity and cost while still achieving the pressure distribution improvement. This combination of parameter optimization and localized treatment resolves the contradiction between pressure suppression and ease of manufacture.
Data Source
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AI summary
Provided is a tapered roller bearing (1, 1', 21) which is to be used for a pilot portion and an idler portion of a synchronous mesh-type transmission in which a component corresponding to a bearing outer ring (3, 23) is formed of a gear (34, 43), wherein a ratio L/Dw of a roller length (L) of a tapered roller (4) serving as a rolling element to a roller diameter (Dw) is set to 1.7 or more, wherein a rolling surface (6) of the tapered roller (4) includes a straight portion (6a) in a center portion of the rolling surface (6) in an axial direction and crowning portions (6b, 6c) extending from the straight portion (6a) to both end portions, and wherein the crowning portions (6b, 6c) are each formed of logarithmic crowning.