PTC Heating Element Contact Projections for Heat Extraction
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Solution Overview
Problem
Existing heat-generating elements for motor vehicles face challenges in achieving a good mechanical connection between conductor tracks and PTC elements while ensuring effective heat extraction, particularly in compact designs where clearance and creepage distances are critical, especially in high-voltage applications.
Innovation Solution
The heat-generating element features conductor tracks with contact projections that protrude from the abutment surface, forming contact surfaces to abut the PTC element, allowing for a defined space filled with adhesive for enhanced heat conduction and electrical conductivity, with adjustable adhesive thickness and flexible protrusion segments for adaptability to the PTC element's rough surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conductor tracks are pressed against the PTC element with external clamping force, then electrical contact resistance is reduced, but mechanical connection reliability deteriorates in compact designs
Solution Approach 1:
The conductor track incorporates elastic protrusion segments that can dynamically adapt to the PTC element's rough surface. These segments are designed with elastic properties allowing them to deform and make reliable electrical contact without requiring complex external clamping mechanisms, thus improving mechanical connection reliability while maintaining compact design simplicity.
Solution Approach 2:
The conductor track uses protrusion segments with specific elastic parameters and geometric dimensions that enable self-adjustment to surface irregularities. By changing the physical parameters of the contact structure (elasticity, protrusion height, segment geometry), the system achieves reliable mechanical and electrical connection without additional clamping complexity.
2Temperature
If adhesive layer thickness is increased to fill gaps between conductor tracks and PTC element, then heat extraction efficiency is improved, but electrical insulation increases contact resistance
Solution Approach 1:
The contact interface is segmented into multiple protrusion segments rather than a continuous adhesive layer. This segmentation allows the adhesive to be applied in controlled amounts between segments, ensuring thermal contact while maintaining electrical conductivity through the protrusion tips that directly contact the PTC element surface.
Solution Approach 2:
Different regions of the conductor track have different properties: the protrusion segments have elastic and conductive properties for electrical contact, while the adhesive regions provide thermal conduction and mechanical bonding. This local differentiation of material properties and functions resolves the contradiction between heat extraction and electrical contact reliability.
3Volume of moving object
If clearance and creepage distances are reduced for compact design, then device size is minimized, but electrical insulation between opposite polarity tracks deteriorates
Solution Approach 1:
An adhesive layer with insulating properties serves as an intermediary substance between conductor tracks of opposite polarity. This adhesive mediator provides the necessary creepage distance for electrical insulation while allowing the overall device dimensions to remain compact, as the adhesive layer is thin yet functionally sufficient for high-voltage isolation.
4Temperature
If conductor track abuts the main side surface of the PTC element for heat extraction, then heat transfer area is maximized, but adhesive layer uniformity becomes difficult to maintain
Solution Approach 1:
The elastic protrusion segments can dynamically adapt to surface irregularities of the PTC element's main side surface. This dynamic adaptation capability compensates for manufacturing tolerances and surface roughness, allowing uniform adhesive distribution and reliable contact even when abutting the large main side surface area for optimized heat transfer.
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
This configuration ensures reliable electrical contact and efficient heat extraction by filling the gap between the conductor tracks and PTC elements with adhesive, minimizing thermal resistance and maintaining a precise heat transfer path, suitable for high-voltage applications and compact designs.
Implementation Method 1
filling the gap between the conductor tracks and PTC elements with adhesive, minimizing thermal resistance and maintaining a precise heat transfer path
Implementation Method 2
the contact projections each form contact surfaces which abut the surface of the PTC element in an electrically conductive manner
Data Source
AI summary
A heat-generating element of an electric heating device includes a PTC element, conductor tracks abutting surfaces of the PTC element, and an adhesive which connects the conductor tracks to the PTC element. The conductor track has several contact projections which protrude from an abutment surface of the conductor tracks. The contact projections form a contact surface which abuts the surface in an electrically conductive manner with a free space between the surface and the abutment surface, in which the adhesive is accommodated. Also disclosed is a method in which the contact projections are formed from initially planar conductor track, an adhesive is applied to the abutment surface between the contact projections, a masking covering the contact surfaces is removed, and the conductor track is glued to a PTC element with the adhesive accommodated between the surface and the abutment surface.