Toroidal Roller Bearings with Concave Profiles
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Solution Overview
Problem
Conventional roller bearings face issues with fretting damage and metal fatigue due to high radial loads and vibrations, which can lead to catastrophic failure, especially in high-fatigue and high-speed applications.
Innovation Solution
A roller bearing design featuring a toroidal inner and outer raceway with concave cylindrical rollers and a cage ring that provides increased radial thickness and cage thickness, allowing for better load distribution and retention, and accommodating axial displacement and misalignment, while reducing friction and wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional spherical roller bearings are used, then the bearing can accommodate axial displacement and misalignment, but the inner ring has insufficient radial thickness to provide heavy interference fit with the shaft, leading to fretting damage and metal fatigue under high radial loads
Solution Approach 1:
The invention employs a toroidal inner raceway with a convex surface profile instead of a conventional spherical or cylindrical raceway. This curved geometry allows the raceway to engage the concave rolling elements over an extended axial length, effectively increasing the radial thickness of the inner ring and enabling heavy interference fits with the shaft to prevent fretting and metal fatigue under high radial loads.
Solution Approach 2:
The invention transitions from conventional spherical rollers to concave cylindrical rollers with a different geometric configuration. The concave profile of the rollers, combined with the toroidal raceways, creates a new dimensional relationship where the rolling elements engage the raceways along their entire length, maximizing load distribution and eliminating the radial thickness limitation of conventional designs.
2Strength
If conventional spherical rollers with convex profiles are used, then the bearing design is simpler, but the load-carrying capacity is reduced and the cage thickness is insufficient for high-fatigue applications
Solution Approach 1:
The invention applies concave profiling specifically to the rolling elements while maintaining the overall bearing structure. The concave geometry is localized to the roller profile and toroidal raceway surfaces, creating optimal stress distribution and load-carrying capacity in the critical contact zones without unnecessarily complicating the entire bearing assembly.
Solution Approach 2:
The invention combines the toroidal inner raceway with concave cylindrical rollers and a reinforced cage structure to create a composite bearing system. This composite design integrates multiple geometric features and structural elements that work together to enhance load-carrying capacity and durability in high-fatigue applications.
3Reliability
If the inner ring radial thickness is increased to provide heavy interference fit, then fretting damage is reduced, but the bearing width and overall size increase
Solution Approach 1:
The toroidal raceway geometry with its convex surface profile enables the inner ring to engage the concave rollers over an extended axial length. This curved contact geometry increases the effective load-bearing area and allows for heavy interference fits that protect against fretting damage without requiring a proportional increase in bearing width, as the load is distributed along the toroidal surface.
Data Source
AI summary
A roller bearing comprises inner and outer rings defining a toroidal inner raceway rotatable about a bearing axis (A). A plurality of concave rolling elements is arranged in a single row between the outer and inner rings. Each of the plurality of concave rolling elements is a symmetrical cylindrical roller having circular ends, a roller axis passing through the center of the circular ends, and a concave side profile that extends continuously between the circular ends. The toroidal inner and outer raceways each have a convex race surface that continuously engages the concave side profile between the circular ends of each concave rolling element with a first radius and extends axially beyond the circular ends of each concave rolling element with a second radius that is less than the first radius.