Ceramic Insulating Bushes for Fiber Composite Wheel Fastening
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Solution Overview
Problem
The use of metal wheel disks in vehicles generates thermal stresses and potential corrosion due to poor heat conduction and thermal expansion differences between plastics and metals, particularly in fiber-reinforced polymers, which can compromise the strength and stability of the wheel disk during braking, and existing solutions do not adequately address these issues.
Innovation Solution
A wheel fastening arrangement using ceramic insulating bodies and washers that surround the screw openings in the wheel disk, providing thermal insulation and preventing electrical contact, thereby protecting the plastic wheel disk from high temperatures and avoiding galvanic corrosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If a fiber-reinforced plastic wheel disk is used to reduce weight, then the weight of the wheel is reduced, but the thermal insulation property causes heat accumulation and thermal stress during braking
Solution Approach 1:
A metallic insert is introduced as an intermediary component between the plastic wheel disk and the fastening screws. This insert serves as a thermal bridge to conduct heat away from the wheel disk, while also providing a suitable bonding surface for adhesive attachment and preventing direct contact between dissimilar materials that would cause galvanic corrosion.
2Strength
If metallic inserts are used in the screwing arrangement, then fastening strength is improved, but galvanic corrosion occurs between the metal insert and carbon-fiber-reinforced plastic
Solution Approach 1:
An electrically insulating adhesive layer is introduced as a mediator between the metallic insert and the carbon-fiber-reinforced plastic wheel disk. This adhesive layer prevents direct electrical contact between the two dissimilar materials, thereby eliminating the galvanic corrosion pathway while maintaining the mechanical fastening function.
3Ease of operation
If the wheel disk is poorly cooled by dynamic wind, then cooling efficiency is reduced, but heat accumulation increases leading to thermal stress
Solution Approach 1:
The metallic insert acts as a passive thermal management component that continuously conducts heat from the wheel disk to the fastening points during rotation, providing active cooling through centrifugal force and air flow, thereby reducing thermal stress without requiring additional active cooling systems.
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 ceramic insulating bodies effectively reduce heat transfer and prevent corrosion, enhancing the structural integrity and longevity of the wheel disk by maintaining the plastic's mechanical properties and preventing thermal damage during braking.
Implementation Method 1
The insulating body effectively reduce heat transfer and prevent corrosion, enhancing the structural integrity and longevity of the wheel disk by maintaining the plastic's mechanical properties and preventing thermal damage during braking
Implementation Method 2
customary metallic inserts in the region of the screwing arrangement must be electrically isolated from a carbon-fiber-reinforced plastic in order to avoid contact corrosion
Data Source
AI summary
A wheel for a motor vehicle, has a rim intended to receive a tire and a wheel disc made of fiber composite material joined to the rim, as well as an arrangement including screws or nuts for fastening the wheel disc to a wheel hub, for which purpose the wheel disc has axially directed openings for the passage of the screws or threaded bolts for screwing onto the nuts. The arrangement includes, for each opening of the wheel disc, an insulating body, a bush and a washer, each having a central opening, which surround the opening of the wheel disc in a U-shape, wherein the bush rests as a frame at an inner circumference of the opening, and the insulating body and the washer, resting against the frame and against the wheel disc in each case on one side of the wheel, at least partially cover the wheel disc in the radial direction. The insulating body is directed towards the wheel inside and the washer is directed towards the wheel outside. The insulating body can consist at least partially of ceramic material.