PTC Heating Element Contacts for Thickness Variation Tolerance
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Solution Overview
Problem
Existing electrical heating devices with PTC elements face issues due to thickness variations in PTC heating elements, leading to inadequate contact between strip conductors and PTC elements, causing spark formation and thermal disturbances, which impair service life and electronic controllers.
Innovation Solution
The introduction of contact projections on strip conductors that extend beyond the locating face of the PTC heating elements ensures a defined and reliable electrical contact, preventing conduction problems even with slight thickness deviations, and can be formed by shaping sheet metal strips to protrude and contact the PTC elements under tension.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PTC heating elements are manufactured by sintering with metallisation, then heating function is achieved, but thickness variations occur leading to inadequate contact
Solution Approach 1:
The strip conductor is designed with an elastically deformable contact region that can dynamically adapt to thickness variations in PTC elements. This elastic deformation allows the contact region to maintain reliable electrical contact despite manufacturing tolerances in PTC element thickness, resolving the contradiction between contact reliability and manufacturing precision.
Solution Approach 2:
The invention changes the physical state of the strip conductor from rigid to elastically deformable in the contact region. This parameter change allows the contact region to accommodate thickness variations through elastic deformation, ensuring consistent electrical contact while maintaining manufacturing simplicity.
2Ease of manufacture
If strip conductors are rigidly aligned, then manufacturing is simplified, but contact reliability deteriorates due to thickness variations
Solution Approach 1:
The strip conductor is segmented into a rigid portion for alignment and a deformable contact region for reliable contact. This segmentation allows the majority of the strip conductor to remain rigidly aligned for easy manufacturing, while the specific contact region can deform elastically to accommodate PTC element thickness variations.
Solution Approach 2:
The strip conductor has different local properties: a rigid section for structural stability and alignment, and a locally deformable contact region for adapting to thickness variations. This local quality differentiation resolves the contradiction by maintaining rigid alignment overall while providing localized flexibility where needed for reliable contact.
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 solution enhances the safety and service life of electrical heating devices by ensuring consistent current transfer and accurate contacting of PTC elements, reducing thermal disturbances and extending the operational lifespan.
Implementation Method 1
PTC heating elements, which are ceramic components that are manufactured by sintering... the strip conductors directly contacting the PTC element so that current is reliably introduced into the PTC element and heat can be coupled out of the PTC element
Implementation Method 2
at least one of the strip conductors (3) is provided with at least one contact projection (6) which extends beyond a locating face (7) for the PTC heating element (2) formed by the strip conductor (3)... a contact projection (6) ensures current transfer
Data Source
AI summary
An electrical heating device includes at least one heat generating element and at least one heat emitting element having opposed surfaces that abut the heat generating element. The heat generating element includes at least one PTC heating element having strip conductors on both sides of it for the electrical supply of the PTC heating element At least one of the strip conductor is provided with at least one contact projection which protrudes beyond a PTC heating element locating face formed on the strip conductor. Also disclosed is a heat generating element having at least one strip conductor provided with at least one contact projection.