Asymmetrical Tooth Profile in Planetary Roller Bearing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Planetary roller bearings experience stress peaks and potential failure due to uneven load distribution across teeth, particularly the first row, caused by spring deflection and tolerance issues.
Innovation Solution
The introduction of an asymmetrical tooth profile on the planetary rolling elements or rings, where the height or spacing of teeth is varied to reduce the load on the outermost teeth, allowing for a more even distribution of load across subsequent teeth, thereby minimizing stress peaks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If symmetrical tooth profiles are used on planetary rolling elements, then manufacturing is simplified, but stress peaks occur on the first row of teeth leading to overloading and potential failure
Solution Approach 1:
The patent applies asymmetry by designing tooth profiles with different heights on opposite sides of the planetary rolling element. Specifically, the tooth height on the first side (h1) is made different from the tooth height on the second side (h2), creating an asymmetric profile that prevents all teeth from contacting simultaneously and distributes load more evenly across multiple tooth rows, thereby eliminating stress peaks on the first row of teeth while maintaining manufacturing feasibility through standardized asymmetric profile designs.
2Force
If the first row of teeth is designed to bear the primary load, then load capacity is maximized, but stress peaks cause overloading and failure of these teeth
Solution Approach 1:
The patent applies local quality by varying the tooth height locally at different positions around the planetary rolling element. The first tooth row has a different tooth height (h1) compared to the second tooth row (h2), creating localized differences in load bearing capacity. This ensures that no single tooth row is overloaded, as the asymmetric profile causes the load to be distributed across multiple tooth rows simultaneously, with each row bearing a portion of the total load appropriate to its local geometry.
3Manufacturing precision
If uniform tooth spacing is used, then manufacturing precision is improved, but load distribution becomes uneven causing stress peaks on the first tooth row
Solution Approach 1:
The patent resolves this contradiction by introducing asymmetry in tooth height while maintaining uniform tooth spacing. The uniform spacing (equal pitch between adjacent teeth) ensures manufacturing precision and ease of gear generation, while the asymmetric tooth heights (h1 ≠ h2) create different engagement conditions for each tooth row. This asymmetric configuration causes the load to be shared across multiple tooth rows rather than concentrated on the first row, achieving both precise manufacturing and reliable load distribution.
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
Planetary roller bearing comprising an outer ring with a tooth profile formed on the inner circumference by grooves, an inner ring with a tooth profile formed on the outer circumference by grooves, and a plurality of planetary rolling elements which are accommodated on the end side in cage disks and have a tooth profile formed by grooves, wherein the tooth profiles of the planetary rolling elements engage in the tooth profiles of the rings, wherein the height, viewed axially, of at least one first tooth (15a, 9a, 12a) of the planetary rolling elements (4) or of the outer or inner ring (2, 3) is less than that of the following second tooth (15b, 9b, 12b), or that the axial distance (d1), viewed axially, of at least one first tooth (15a, 9a, 12a) to the following second tooth (15b, 9b, 12b) is less than the distance of the second tooth (15b, 9b, 12b) to the third tooth (15c, 9c, 12c).