Bearing Assembly Runout Region for Precise Inner Ring Centering
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Solution Overview
Problem
Conventional bearing assemblies in planetary gears face issues with axial and radial play, leading to suboptimal concentricity and reduced service life due to inadequate pre-tensioning and centering mechanisms.
Innovation Solution
A bearing assembly featuring a shaft with a finely machined bearing seat and a nut with internal threads that provide axial fixing and radial centering through a runout region, ensuring precise alignment and pre-tensioning of the inner ring, thereby eliminating play and enhancing concentricity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional bearing assemblies are used without a runout region, then the structure is simpler, but axial and radial play occurs leading to suboptimal concentricity
Solution Approach 1:
The threaded region incorporates a runout region with distinct local geometry that differs from the main threaded portion. This runout region features a smaller major diameter that creates an interference fit with the bearing inner ring, providing localized radial centering functionality while the rest of the threaded region maintains standard threading for axial positioning.
Solution Approach 2:
The invention merges multiple functions into the threaded region: axial positioning through standard threading, radial centering through the runout region's interference fit, and bearing pre-tensioning through nut application. This consolidation eliminates the need for separate centering features or additional components.
2Manufacturing precision
If the bearing seat is extended axially beyond the inner ring contact region, then high-precision machining region is larger providing better centering, but the manufacturing complexity increases
Solution Approach 1:
The bearing seat is segmented into two distinct axial regions: a first region that contacts the inner ring of the bearing requiring high-precision machining, and a second extended region that contacts the runout region of the threaded shaft. This segmentation allows each region to be optimized for its specific function while maintaining manufacturability.
Solution Approach 2:
The runout region of the threaded shaft is machined to a precise geometry before the bearing is installed. This preliminary precision machining of the runout region enables the bearing inner ring to be centered radially through interference fit, establishing accurate concentricity before final bearing mounting and pre-tensioning.
3Manufacturing precision
If the nut is pushed onto the runout region during assembly, then radial centering is achieved, but the threading process becomes more difficult
Solution Approach 1:
The runout region extends slightly beyond what is strictly necessary for minimum centering, creating an interference fit that provides robust radial centering. This excessive action ensures reliable centering even with manufacturing tolerances, while the gradual transition geometry minimizes threading difficulty.
Solution Approach 2:
The runout region features a gradual change in major diameter from the main threaded region, creating a tapered transition. This parameter change allows the nut to be gradually pushed onto the runout region during assembly, with the interference fit increasing progressively to achieve radial centering without requiring excessive force or causing threading difficulties.
Data Source
AI summary
A bearing assembly includes a shaft, a first bearing, and a nut. The nut has a thread, which is screwed onto a threaded region formed on the shaft, and a bearing seat formed on the shaft adjoins the threaded region. The inner ring of the first bearing contacts the bearing seat, and the nut contacts the inner ring of the first bearing. The inner ring of the first bearing is arranged spaced apart from the threaded region of the shaft. A runout region of a thread cut into the threaded region of the shaft is arranged in a subsection of the bearing seat adjoining the threaded region.