Shell-like Shielding Plates for Vehicle Heating Element EMI Reduction
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Solution Overview
Problem
Existing heat generating elements for motor vehicle electric heating devices face issues with electromagnetic interference (EMI) and unreliable sealing due to thermal expansion, leading to permanent cracking and loss of sealing effect.
Innovation Solution
A heat generating element with shell-like shielding plates connected thermally and sealed with adhesive, encasing the PTC element and contact plates, providing electromagnetic shielding while allowing for thermal conductivity and expansion compensation without direct electrical contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If curing insulating adhesive is used to seal the positioning frame and bond corrugated fin elements, then hermetic sealing is achieved, but permanent cracking occurs due to different thermal expansions
Solution Approach 1:
The adhesive is applied in a controlled manner with specific geometry (bead cross-section, annular shape) at specific locations (between positioning frame and shielding plate) to provide sealing where needed while avoiding areas subject to high thermal stress
Solution Approach 2:
The adhesive is applied in advance before final assembly, allowing it to be positioned correctly in the annular space between the positioning frame and shielding plate, ensuring proper sealing configuration before thermal cycling begins
2Object-affected harmful factors
If shielding plates are added to reduce electromagnetic interference, then EMI shielding is improved, but device complexity increases
Solution Approach 1:
The shielding plate serves multiple functions simultaneously: it provides electromagnetic shielding, acts as a mounting surface for the adhesive seal, and serves as a structural component of the heating element assembly, thereby reducing the need for separate sealing and shielding components
Solution Approach 2:
The sealing function and shielding function are merged into a single integrated solution where the adhesive bonds the shielding plate directly to the positioning frame, combining what would traditionally be separate sealing and shielding components into one unified assembly
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 effectively shields against electromagnetic radiation, maintains a reliable seal, and compensates for thermal expansions, ensuring efficient operation and reduced EMI in motor vehicle electric heating devices.
Implementation Method 1
The two shielding plates are sealed by way of an adhesive which is received in one of said two shielding plates and into which the end of a rim of said other shielding plate dips
Implementation Method 2
The two shell-like shielding plates are connected to the insulating layer in a thermally conductive manner
Implementation Method 3
two contact plates which are in contact with opposite sides of the PTC element and are provided on their outer side facing away from the PTC element with an insulating layer
Data Source
AI summary
A heat generating element for an electrical heating device of a motor vehicle, including at least one PTC element and two contact plates which are in contact with opposite sides of the PTC element and are provided on their outer side facing away from the PTC element with an insulating layer. Shielding is provided, comprising a first shell-like shielding plate and a second shell-like shielding plate which are each provided on the outer side of the insulating layer and are connected thereto in a thermally conductive manner. The longitudinal wall sections, directed towards one another, of the first and second shielding plate form an overlapping region. In order to reduce EMC problems, two shielding plates are sealed by way of an adhesive which is received in one of the two shielding plates and into which the end of a rim of the other shielding plate dips.