Roller Bearing Unit Weight Reduction via Ferrous Alloy Intermediary Cores
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing wheel-support hub units face issues with weight reduction and durability, particularly due to material differences leading to changes in preloading and potential galvanic corrosion, as well as foreign matter ingress through gaps caused by differing linear expansion coefficients between various components.
Innovation Solution
The rolling bearing unit design incorporates a stationary bearing ring and a rotating bearing ring with raceway surfaces made from synthetic resin or aluminum alloy for weight reduction, and ferrous alloy for high strength, with the raceway members directly fitted to cores made of the same ferrous alloy to match linear expansion coefficients, and seal members to block external matter entry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If aluminum alloy or synthetic resin is used for the outer ring and hub to reduce weight, then the unsprung weight is reduced, but gaps occur due to linear expansion coefficient differences causing foreign matter ingress and galvanic corrosion
Solution Approach 1:
A ferrous alloy core is introduced as an intermediary component between the aluminum alloy outer ring and the rolling bearing components. This core has a linear expansion coefficient matching the rolling bearing components, preventing gaps and foreign matter ingress, while the aluminum alloy outer ring maintains weight reduction benefits
Solution Approach 2:
The outer ring is constructed as a composite structure with a ferrous alloy core and aluminum alloy outer layer. This composite design combines the high strength and matched thermal expansion of ferrous alloy with the lightweight properties of aluminum alloy, resolving the contradiction between weight reduction and durability
2Weight of moving object
If different materials are used for the outer ring and hub to reduce weight, then the weight is reduced, but preloading changes occur due to material differences
Solution Approach 1:
The ferrous alloy core acts as a thermal expansion intermediary that matches the linear expansion coefficient of the rolling bearing components, ensuring stable preloading conditions while allowing the use of lightweight aluminum alloy for the outer ring
3Strength
If ferrous alloy raceway members are fastened to aluminum alloy hubs, then the raceway strength is maintained, but galvanic corrosion occurs at the interface
Solution Approach 1:
The ferrous alloy core serves as an intermediary between the ferrous alloy raceway members and the aluminum alloy hub, eliminating dissimilar metal contact and preventing galvanic corrosion while maintaining raceway strength through the ferrous alloy components
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
This design achieves a balance of reduced weight and improved durability by preventing preloading changes and galvanic corrosion, while maintaining the strength of raceway members and cores, and effectively sealing the unit from external contaminants.
Implementation Method 1
The seal ring 19 and the cover 21 prevent foreign matter such as dust or rainwater from entering into the rolling-element installation space 18, and prevent grease that is filled in the rolling-element installation space 18 from leakage to the outside.
Implementation Method 2
a plurality of rolling elements 4 for supporting the hub 3 so as to be able to freely rotate around the outer ring 2
Implementation Method 3
the raceway members directly fitted to cores made of the same ferrous alloy to match linear expansion coefficients
Implementation Method 4
with the raceway members directly fitted to cores made of the same ferrous alloy to match linear expansion coefficients, and seal members to block external matter entry
Data Source
AI summary
A rolling bearing unit with decreased weight and improved durability is provided. An outer-ring core, manufactured using a ferrous alloy, forms an outer ring and is molded to an outer-ring main body that is manufactured using a synthetic resin containing reinforced fibers or using an aluminum alloy. Outer-ring raceway members are fitted into and fastened to mating concave surfaces of the inner circumferential surface of the outer-ring core that are exposed from the outer-ring main body. A hub core, manufactured using a ferrous alloy, forms a hub and is molded to a hub main body made using a synthetic resin containing reinforced fibers or using an aluminum alloy. Around the outer circumferential surface of the hub core, inner-ring raceway members are fitted onto and fastened to a fitting surface of the outer circumferential surface of the hub core that is exposed from the hub main body.