Hub-Rotor Adapter Thermal Expansion Management
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Solution Overview
Problem
Existing disc brake systems face issues due to differential thermal expansion between the rotor and axle hub, leading to stress on the connection, heat conduction affecting bearing and seal longevity, and high costs associated with machining and material selection, especially when using hardened materials.
Innovation Solution
A hub-rotor adapter with a frustoconical and cylindrical design that accommodates relative expansion and contraction, allowing for various material choices and reducing stress on the interface, while being simpler and less expensive to fabricate, and isolating the rotor-hub joint from the bearing/seal area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a direct interface between the rotor and axle hub is used, then the structure is simple, but differential thermal expansion causes stress on the connection and heat conducts directly to the bearing/seal area
Solution Approach 1:
An intermediate adapter assembly is introduced between the rotor and axle hub. This adapter includes an adapter body with tapered outer surface matching the hub, a retaining ring, and a rotor mounting flange. The intermediary structure isolates the rotor from direct thermal and mechanical contact with the hub, preventing heat conduction to the bearing area and accommodating differential thermal expansion through its geometric design.
2Strength
If hardened material is selected for the axle hub, then strength is improved, but machining costs and manufacturing complexity increase significantly
Solution Approach 1:
The system is segmented into distinct components: the axle hub, the adapter assembly (including adapter body and retaining ring), and the rotor. This segmentation allows the hub to be manufactured from softer, more easily machined materials, while the adapter components can be made from hardened materials to provide the necessary strength and wear resistance at the interface points.
Solution Approach 2:
The adapter assembly combines different materials strategically - the adapter body uses a material compatible with the hub's tapered surface (such as ductile iron or steel), while the retaining ring can be made from hardened material to provide locking force. This composite approach optimizes both manufacturability and performance.
3Reliability
If splined connections are used to accommodate thermal expansion, then thermal expansion is accommodated, but manufacturing cost and complexity increase due to costly machining
Solution Approach 1:
The adapter body features a tapered outer surface with a conical geometry that matches the tapered bore of the axle hub. This curved, tapered interface allows the adapter to expand and contract thermally while maintaining axial alignment and secure attachment, eliminating the need for complex splined connections. The taper angle is selected to accommodate thermal expansion while providing sufficient frictional engagement.
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
The hub-rotor adapter effectively manages thermal expansion, reduces heat transfer, and allows for cost-effective and lightweight designs by enabling the use of different materials, extending system longevity and reducing replacement costs.
Implementation Method 1
the rotor and axle hub may be made of materials having different coefficients of thermal expansion, and/or may be heated to different temperatures during braking, so that the connecting portions of the axle hub and rotor will expand and contract at different rates or by different amounts
Implementation Method 2
heat from the rotor can be conducted directly into the bearing/grease or adjacent oil seal area. This prolonged heat can have a detrimental effect on both bearing and seal life
Data Source
AI summary
A hub-rotor adapter for use with a disc brake assembly having an axle hub and rotor. The hub-rotor adapter may include an adapter body having a wall forming an annular opening at an inboard end thereof; the adapter body having an inboard flange shaped to be attached to the rotor, and an outboard flange shaped to be attached to the axle hub.