U-Shaped Brake Rotor Lug Geometry for Aluminum Hub Durability
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Solution Overview
Problem
Aluminum wheel hubs experience premature failure due to stress risers and increased stress from misalignment and thermal expansion, complicating the use of U-shaped brake rotors.
Innovation Solution
A U-shaped brake rotor with a unitary, one-piece construction featuring an inclined lug design and sacrificial pilots to minimize stress risers and align concentrically with the wheel hub, while incorporating a flared flange to resist bending forces and provide clearance for brake calipers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If a U-shaped brake rotor is used with an aluminum wheel hub, then the wheel hub assembly can be lighter, but the rotor flange and pilot configurations may cause excess stress in the aluminum material leading to premature failure
Solution Approach 1:
The patent applies local quality by modifying specific regions of the rotor flange and pilot configurations to have different geometries and material properties. The rotor flange includes recesses and the pilots have specific dimensional relationships with the aluminum hub to distribute stress locally and prevent premature failure while maintaining overall lightweight design
Solution Approach 2:
The patent changes critical parameters including the dimensional relationships between pilot diameter, pilot length, and flange thickness. These parameter adjustments are specifically tailored for aluminum wheel hubs to reduce stress concentrations and prevent premature failure while maintaining the lightweight advantage
2Ease of manufacture
If the rotor is not concentrically aligned with the wheel hub, then assembly is simpler, but radial run out and vibration occur during operation
Solution Approach 1:
The patent uses the wheel hub as an intermediary component with precisely engineered pilot features that guide and center the rotor during assembly. The pilot diameter and length are specifically designed to ensure concentric alignment, allowing simple assembly procedures while preventing radial runout and vibration through the hub's geometric constraints
3Strength
If the rotor flange is made thick to resist bending forces, then structural strength improves, but the flange may interfere with the brake caliper in the narrow wheel end area
Solution Approach 1:
The patent segments the rotor flange structure by introducing recesses and varying thickness strategically. This segmentation allows the flange to be thick where structural strength is needed to resist bending forces while being thinner in areas where brake caliper clearance is required, optimizing both strength and space utilization in the narrow wheel end area
4Temperature
If aluminum wheel hub material is used, then thermal expansion is higher, but this causes the hub to expand radially outward against the rotor pilot and increase stress in the rotor barrel
Solution Approach 1:
The patent changes the dimensional parameters of the pilot configuration, specifically the pilot diameter and length relationships. These parameter adjustments account for the higher thermal expansion coefficient of aluminum, creating clearance and geometric relationships that prevent excessive radial expansion from causing stress in the rotor barrel during thermal cycling
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 solution enhances durability and reduces stress concentrations, preventing premature failure by aligning the rotor correctly and distributing forces effectively, thus improving the lifespan of the wheel hub assembly.
Implementation Method 1
The inboard inclined surface provides clearance for a brake caliper, or other brake system component of the vehicle, and reduces the weight of the brake rotor
Implementation Method 2
the lug having the inboard inclined surface enables the lug to be thick and angled proximate the wheel mounting flange of the wheel hub to resist bending forces from the wheel mounting flange
Implementation Method 3
The sacrificial pilot is configured to wear out of contact with the wheel hub during operation of the wheel hub assembly
Implementation Method 4
The sacrificial pilot is configured to wear out of contact with the wheel hub during operation of the wheel hub assembly
Implementation Method 5
the material of an aluminum wheel hub may have a higher coefficient of thermal expansion than the material of a similar iron wheel hub. Due to the higher coefficient of thermal expansion, the aluminum wheel hub may expand radially outward against a pilot of the associated U-shaped brake rotor
Data Source
AI summary
A U-shaped brake rotor including a body that is rotatable around a central axis. The body has an interior to receive a wheel hub, an inboard brake disc, an outboard mounting flange, and an annular wall portion. The outboard mounting flange includes a lug having a through opening to receive a fastener to secure the lug to a wheel mounting flange of the wheel hub. The lug further includes an inboard inclined surface extending radially outward as the inboard inclined surface extends away from the annular wall portion of the body. The inboard inclined surface of the lug extends around the through opening and includes a radially outer portion radially outward of the through opening, a radially inner portion radially inward of the through opening, and an intermediate portion on either side of the through opening and connecting the radially outer and inner portions of the inboard inclined surface.