Steering Wheel Heater Unit Flatness via Foam Substrate Thinning
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Solution Overview
Problem
Conventional heater units in steering wheels cause discomfort due to uneven thickness where the cord-shaped heater is disposed, leading to an uncomfortable steering experience.
Innovation Solution
A method of manufacturing a steering wheel with a heater unit that includes a pair of substrates formed from polymeric foam and a cord-shaped heater, where the heater is sandwiched between the substrates and thinned to form a flat shape, using a pressure-sensitive adhesive and thermal fusible regions for bonding, ensuring evenness and enhanced mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a cord-shaped heater is disposed between substrates in a conventional heater unit, then the heater can provide heating function, but the thickness at the heater region becomes larger causing unevenness and user discomfort
Solution Approach 1:
The substrate thickness is locally reduced at the heater-disposed region to match the heater thickness, creating a uniform overall thickness. This local modification allows the heater to provide heating function while maintaining shape uniformity and eliminating user discomfort.
Solution Approach 2:
The substrate thickness parameter is changed in the heater region by reducing it to be substantially equal to the heater thickness. This parameter change resolves the thickness unevenness problem while preserving the heating function.
2Shape
If substrate thickness is reduced at heater regions to eliminate unevenness, then shape uniformity is improved, but substrate strength may be compromised
Solution Approach 1:
A laminated structure is used where multiple substrate layers are combined with the heater between them. This composite structure allows local thickness reduction while maintaining overall strength through the layered configuration and bonding between layers.
Solution Approach 2:
The substrate exhibits elastic curvature or bending in the heater region rather than being completely flat. This curvature allows the substrate to accommodate the heater thickness while maintaining structural integrity and strength.
3Ease of manufacture
If conventional substrates are used without thickness modification, then manufacturing is simpler, but user comfort is reduced due to unevenness
Solution Approach 1:
The substrate thickness is preliminarily reduced at the heater regions during the manufacturing process, specifically when the heater is disposed between the substrates. This preliminary action ensures uniform thickness is achieved before final assembly, maintaining both manufacturing efficiency and user comfort.
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 flat heater unit that eliminates discomfort during steering by eliminating unevenness, providing a comfortable grip and enhanced mechanical strength.
Implementation Method 1
applying heat and pressure to the substrates by a flat plate such that the thickness of a region of each of the substrates at which the cord-shaped heater is disposed is thinned
Implementation Method 2
the cord-shaped heater includes on an outmost layer thereof a thermal fusible region. This configuration will help fix the cord-shaped heater on the substrates easily only with the aid of heat
Data Source
Figure 1~2
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AI summary
Provided is a heater unit (31), including a pair of substrates (10, 10') formed from a polymeric foam and a cord-shaped heater (1) sandwiched between the pair of substrates (10, 10'). The thickness of a region of each of the substrates (10, 10') at which the cord-shaped heater (1) is disposed is thinned relative to other regions of the substrates (10, 10') in such a manner as to be shaped to the cord-shaped heater (1) and thus the heater unit forms a flat shape. In the heater unit (31), the substrates (10, 10') are bonded together by an adhesive layer that is composed only from a pressure-sensitive adhesive.