Steering Wheel Heater Unit Flat Surface Design
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Solution Overview
Problem
Conventional heater units installed in steering wheels create uneven thickness, leading to discomfort when gripping the wheel due to the thicker areas where the cord-shaped heater is arranged, causing users to feel uncomfortable during operation.
Innovation Solution
A heater unit comprising a substrate made of polymeric foam with a cord-shaped heater arranged in a predetermined pattern, where the thickness is thinner at the heater's location, forming a flat shape with a heat-fusing portion that is melted and permeated into the foam, creating a fixed portion with a width exceeding three times the core material's width, ensuring a uniform surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a cord-shaped heater is simply arranged on a substrate, then the heater unit provides heating function, but the thickness becomes uneven and causes discomfort to users
Solution Approach 1:
The substrate is designed with locally varying thickness: thinner at the heater arrangement position and thicker at other areas. This local quality differentiation allows the substrate to conform to the heater's shape while maintaining an overall flat surface, resolving the contradiction between providing heating function and maintaining surface flatness.
2Shape
If the substrate thickness is reduced at the heater position to maintain flatness, then surface flatness is improved, but the mechanical strength at that location may be compromised
Solution Approach 1:
The heater unit is constructed as a composite structure combining the substrate and cord-shaped heater. The heater itself provides structural support at the thinned region, compensating for the reduced substrate thickness and maintaining mechanical strength while enabling surface flatness.
3Temperature
If the cord-shaped heater is arranged on the substrate, then heating function is provided, but the fixed portion width is insufficient for reliable attachment
Solution Approach 1:
The substrate thickness at the heater arrangement position is optimized to a specific range (0.5-2.0 mm) that balances multiple requirements: it is thin enough to maintain overall surface flatness but thick enough to provide sufficient material for reliable attachment of the cord-shaped heater, ensuring the fixed portion width exceeds three times the heater core width.
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 results in a surface that is approximately flat without unevenness, eliminating discomfort when operating the steering wheel by maintaining a consistent thickness and improving mechanical strength.
Implementation Method 1
a heat-fusing portion is formed on an outermost layer of the cord-shaped heater, and the heat-fusing portion of the cord-shaped heater is melted and permeated in the polymeric foam to form a fixed portion
Implementation Method 2
a cord-shaped heater arranged on the substrate... the heater unit is arranged between the wheel core material and the covering material
Data Source
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AI summary
The present invention provides a steering wheel and a heater unit used for the steering wheel that does not give discomfort to a user when operating the steering wheel. A heater unit 31 is comprised of a substrate 10 made of a polymeric foam; and a cord-shaped heater 1 arranged on the substrate 10, wherein a thickness of the substrate 10 is thinner at a portion on which the cord-shaped heater 1 is arranged than other area so that the portion is formed along a shape of the cord-shaped heater 1 and the heater unit 31 is approximately flat. A steering wheel, comprised of the above described heater unit; a wheel core material; and a covering material, wherein the heater unit is arranged between the wheel core material and the covering material.