Load Wheel Hub Venting for Bearing and Bond Heat Dissipation
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Solution Overview
Problem
Small diameter load wheels in material handling vehicles experience high loads and rotational speeds, leading to heat generation that causes premature failure of the tire-bond-hub assembly due to bond failure and bearing overheating, exacerbated by debris entanglement.
Innovation Solution
A cylindrical hub design with a central core and a plurality of axial passageways to facilitate air flow and dissipate heat efficiently, constructed from materials with high thermal conductivity and low density, such as aluminum, to reduce the temperature experienced by the bond and bearings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a solid metal hub is used, then structural strength is improved, but heat dissipation capability deteriorates leading to bearing overheating and bond failure
Solution Approach 1:
The solid hub is segmented into a hollow structure with multiple axial passageways running through it. This segmentation creates channels for air flow while maintaining the outer cylindrical structure for strength. The hub wall thickness is optimized to balance structural integrity with heat dissipation surface area.
Solution Approach 2:
The hub is designed with a porous-like structure through the axial passageways, allowing air to penetrate and flow through the hub material. This creates internal convection channels that enhance heat transfer from the bearings and bond line to the external environment.
2Temperature
If axial passageways are added to the hub, then heat dissipation is improved, but structural strength deteriorates
Solution Approach 1:
The hub wall thickness is varied locally to optimize both strength and heat dissipation. The walls are thick enough to maintain structural integrity and support the tire bonding, but thin enough to provide adequate surface area for heat transfer. The passageway placement is strategically positioned to maximize heat transfer paths while minimizing structural compromise.
3Temperature
If aluminum material is used instead of steel, then heat conductivity is improved, but weight increases
Solution Approach 1:
The hub material parameters are optimized by selecting aluminum alloys with specific thermal conductivity and density characteristics. The hollow structure with passageways is designed to achieve the desired thermal performance while keeping the overall weight lower than solid steel hubs, as the aluminum material compensates for the removed core material.
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 design effectively reduces heat experienced by the bond and bearings, prolonging their useful life and increasing the performance and efficiency of material handling vehicles by preventing premature failures and maintaining operational efficiency.
Implementation Method 1
A plurality of passageways extend axially between the outer surface and the inner surface of the hub to facilitate air flow and dissipate heat efficiently
Implementation Method 2
constructed from materials with high thermal conductivity and low density, such as aluminum, to reduce the temperature experienced by the bond and bearings
Data Source
AI summary
A load wheel for a vehicle is provided having a cylindrical hub with an axis, a first sidewall, a second sidewall, an outer surface, a central core extending coaxially within the hub, and a plurality of passageways extending in an axial direction between the first and second sidewall. A solid, non-pneumatic tire is bonded to the outer surface of the hub, and a set of bearing is mounted in the central core of the hub. The hub is characterized by a “heat factor” equal to the (hub mass×hub specific heat)/surface area exposed. The heat factor for a hub comprising passageways is compared to the heat factor for a solid hub to derive a heat factor ratio, which is used to select the exposed surface area of the hub and maintain the operating temperature of the wheel below the failure temperature.