PTC heating element and electric heating device comprising such a PTC heating element and method for producing a PTC heating element
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Solution Overview
Problem
Existing PTC heating elements face challenges in cost-effective production and ensuring complete sealing, leading to potential leaks and increased production complexity, which affects electrical safety and heat dissipation.
Innovation Solution
A deep-drawn housing made from sheet metal, preferably copper or aluminum, with a pot-shaped configuration closed on the underside and open on one side, accommodates the PTC element and insulating layers, ensuring good thermal conductivity and elastic prestress for improved sealing and heat dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional sealing methods (laser welding, electron welding, or beading) are used to close the housing, then the housing can be sealed, but the production cost increases and the process becomes more complex
Solution Approach 1:
The housing is designed with an interference fit connection where the outer diameter of the housing slightly exceeds the inner diameter of the receptacle (interference fit). This parameter change eliminates the need for additional sealing processes like laser welding or beading, as the interference fit itself provides both mechanical connection and sealing. The patent specifies that the housing has an outer diameter that is 0.05-0.5mm larger than the receptacle's inner diameter, creating a press-fit connection that seals the heating element in place.
2Reliability
If the housing is designed as a tube closed at both ends, then complete sealing is achieved, but the length of the heating element becomes greater than necessary
Solution Approach 1:
The invention extracts the sealing function from a traditional closed-tube design by using an interference fit connection between the housing and receptacle. Instead of closing both ends of a tube, the housing is designed as an open-ended structure that inserts into the receptacle, where the interference fit provides the sealing action. This eliminates the need for end-closing operations and reduces the overall length of the heating element while maintaining complete sealing of the heating element within the receptacle.
3Temperature
If the housing material has good thermal conductivity, then heat dissipation is improved, but the sealing capability may be reduced
Solution Approach 1:
The invention employs a composite material structure where the housing is made of metal (aluminum or steel) providing good thermal conductivity for heat dissipation, while the interference fit connection with the receptacle provides the sealing capability. The metal housing material conducts heat away from the PTC element efficiently, while the mechanical interference fit between the metal housing and receptacle ensures complete sealing. This composite approach combines the beneficial properties of metal (thermal conductivity) with the sealing mechanism (interference fit) without compromise.
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 enables cost-effective production of PTC heating elements with enhanced sealing and heat dissipation, reducing the risk of leaks and improving electrical safety while maintaining efficient heat extraction.
Implementation Method 1
A deep-drawn housing made from sheet metal, preferably copper or aluminum, with a pot-shaped configuration closed on the underside and open on one side, accommodates the PTC element and insulating layers, ensuring good thermal conductivity and elastic prestress for improved sealing and heat dissipation
Implementation Method 2
A deep-drawn housing made from sheet metal, preferably copper or aluminum, with a pot-shaped configuration closed on the underside and open on one side, accommodates the PTC element and insulating layers, ensuring good thermal conductivity and elastic prestress for improved sealing and heat dissipation
Data Source
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AI summary
The present invention relates to a PTC heating element (22) for an electric heating device, an electric heating device with such a PTC heating element (22), and a method for manufacturing the PTC heating element (22). The PTC heating element (22) has a housing (72) that integrates at least one PTC element (30), conductive traces (38) electrically connected to the PTC element (30), and insulating layers (34) thermally conductive against the PTC element (30) as a unit and is projected by contact tongues (42) which are electrically conductively connected to the conductive traces (38) for supplying current to the PTC element (30) with opposite polarity.To improve heat extraction from the PTC element, the present invention proposes to delimit the receiving space (78) in a cross-sectional view by two opposing inner surfaces (88) covering the PTC element (30) and concave cavities adjoining the inner surfaces (88) and forming the longitudinal edges (88) of the housing (72), the diameter of which is larger than the distance between the inner surfaces (88). The electric heating device has at least one PTC heating element (22) according to the invention arranged in a circulation chamber (14). In the method according to the invention, the housing (72) is first formed.Then the PTC element (30), the conductor tracks (38) and the insulating layers (34) are inserted into the receiving space (78) through an opening (74) of the deep-drawn part (72) and finally the housing (72) is formed by forming forces acting on the edge areas of the housing (72) so that opposing inner surfaces of the housing (72) are pressed against the insulating layers (34).