Capacitive Coupling Sensor Laminate for Faster Steering Wheel Heating
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Solution Overview
Problem
Conventional capacitive-coupling sensors in steering wheels have low thermal conductivity and require adhesive layers, leading to slow heat transmission and increased production costs.
Innovation Solution
A capacitive-coupling sensor with a thermoplastic elastomer insulating layer providing thermal conductivity of 0.3 W/m·K or more and volume resistivity of 1×10^12 Ω·cm or more, eliminating the need for adhesive layers by using conductive cloths embedded in the insulating layer through thermal compression bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If foamed resin is used for the insulating layer, then electrical insulation is provided, but thermal conductivity is low (0.04 W/m·K) causing slow heat transmission
Solution Approach 1:
The insulating layer uses a composite structure combining a resin base material with thermally conductive particles (such as aluminum oxide, aluminum nitride, or boron nitride) dispersed within it. This composite approach maintains the electrical insulation properties of the resin while the thermally conductive particles create heat transmission pathways, achieving both electrical isolation and improved thermal conductivity simultaneously.
Solution Approach 2:
The patent changes the thermal conductivity parameter of the insulating layer from 0.04 W/m·K (foamed resin) to 0.3 W/m·K or higher by incorporating thermally conductive particles. This parameter modification is achieved while maintaining the volume resistivity at 1×10^12 Ω·cm or more, thus improving heat transmission without compromising electrical insulation.
2Stability of the object's composition
If adhesive layers are used to bond layers, then layer bonding is achieved, but production process complexity and cost increase
Solution Approach 1:
The patent merges the insulating layer and adhesive layer into a single integrated insulating layer. The insulating layer is designed with both insulation and bonding functions, eliminating the need for separate adhesive layers. This is achieved by incorporating bonding agents or surface treatments directly into the insulating layer material, reducing the total number of layers and production steps.
Solution Approach 2:
The insulating layer is designed to perform multiple functions simultaneously: electrical insulation, thermal conduction, and layer bonding. By giving the insulating layer universal functionality, the patent eliminates the need for separate specialized adhesive layers, simplifying both the structure and manufacturing process while maintaining all necessary functions.
3Stability of the object's composition
If multiple adhesive layers are used for bonding, then layer attachment is secured, but production time and cost increase
Solution Approach 1:
The patent combines multiple adhesive layers into a single integrated insulating layer with bonding capability. This reduces the number of bonding operations from multiple separate adhesive applications to a single integrated bonding process, directly improving production efficiency while maintaining secure layer attachment.
Solution Approach 2:
The patent extracts and eliminates the separate adhesive layers from the structure, retaining only the essential bonding function within the insulating layer itself. This extraction of unnecessary intermediate layers simplifies the production process and increases productivity while maintaining the required layer attachment stability.
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 tactile sensation, reduces the risk of sensor function inhibition, and significantly shortens the time to warm up the steering wheel, while simplifying the production process and reducing costs by eliminating the need for adhesives.
Implementation Method 1
the insulating layer includes a thermoplastic elastomer, and the insulating layer has a thermal conductivity of 0.3 W/m·K or more
Implementation Method 2
the insulating layer includes a thermoplastic elastomer, and the insulating layer has a thermal conductivity of 0.3 W/m·K or more, and a volume resistivity of 1×10^12 Ω·cm or more
Implementation Method 3
eliminating the need for adhesive layers by using conductive cloths embedded in the insulating layer through thermal compression bonding
Data Source
AI summary
A capacitive-coupling sensor includes: a detection electrode layer that generates capacitance between the detection electrode layer and an object to be detected; a shield electrode layer; and an insulating layer disposed between the detection electrode layer and the shield electrode layer. The insulating layer includes a thermoplastic elastomer, and the insulating layer has a thermal conductivity of 0.3 W/m·K or more and a volume resistivity of 1×1012 Ω·cm or more. When the detection electrode layer and the shield electrode layer are made of conductive cloths, the conductive cloth for the detection electrode layer is placed on a front surface of the insulating layer and the conductive cloth for the shield electrode layer is placed on a back surface of the insulating layer forming a laminate. The laminate is pressed in a front-back direction under heating to fuse the insulating layer to the conductive cloths, producing the capacitive-coupling sensor.