Electric heating device, in particular for a motor vehicle
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Solution Overview
Problem
Existing electric heating devices for motor vehicles face challenges in effectively cooling power switches while protecting internal components from environmental influences such as moisture and dirt, particularly due to the large passage openings for heat sinks which are susceptible to ingress.
Innovation Solution
The heat sink is inserted into the connection housing in a sealing manner with a sealing element that bridges the gap between the heat sink and the connection housing, providing mobility to accommodate pressure and maintain a preloaded, thermally conductive contact with the circuit breaker, while being held by a locking web and pressure element for secure attachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the heat sink is provided with a large-area passage opening for cooling, then the cooling effectiveness of the power switch is improved, but the susceptibility to moisture and dirt ingress increases
Solution Approach 1:
The heat sink is nested within the connection housing, with the heat sink insertion opening providing a controlled passage that allows the heat sink to be positioned inside the housing while maintaining sealing through the sealing element at the interface between the heat sink and housing
Solution Approach 2:
A sealing element is introduced as an intermediary component at the interface between the heat sink and connection housing. This sealing element bridges the gap between the heat sink contour and the heat sink insertion opening, preventing moisture and dirt ingress while allowing thermal conduction and cooling airflow
2Reliability
If the heat sink is rigidly fixed in the connection housing, then the sealing effectiveness is improved, but the ability to accommodate thickness tolerances and pressure variations is reduced
Solution Approach 1:
The heat sink is designed with mobility in the insertion direction, allowing it to move dynamically within the connection housing. This dynamic positioning enables the heat sink to accommodate thickness tolerances of circuit breakers and adjust to pressure variations while maintaining sealing through the compliant sealing element
Solution Approach 2:
The system allows for parameter changes in the position of the heat sink along the insertion direction. By permitting movement within defined limits, the system can adjust to variations in circuit breaker thickness and pressure conditions while maintaining both sealing effectiveness and thermal contact
3Adaptability or versatility
If the heat sink is made movable in the insertion direction, then the ability to accommodate pressure and tolerances is improved, but the risk of the heat sink being pushed out increases
Solution Approach 1:
A locking web is provided on the heat sink that engages with a corresponding locking structure in the connection housing. This preliminary anti-action mechanism prevents the heat sink from being pushed out beyond the heat sink insertion opening while still allowing controlled movement within the housing for accommodating tolerances and pressure
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 ensures effective cooling of power switches while preventing moisture and dirt ingress, maintaining a hermetic seal and ensuring reliable operation even with varying circuit breaker thickness tolerances, thus enhancing the electrical heating device's performance and longevity.
Implementation Method 1
the circuit breaker rests under preload on this contact surface. The preload is preferably effected by compression of an element which brings about the sealing
Implementation Method 2
the air to be heated with the heating block also radiates onto the heat sinks and convectively dissipates heat that is dissipated there
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The present invention relates to an electric heating device, particularly for a motor vehicle, comprising a frame (44) which forms openings (56) on opposite sides for the passage of a medium to be heated, a layered structure (46) arranged in the frame (44) which includes layers of corrugated fins and heat-generating elements (64; 66), wherein the heat-generating element (66) has at least one PTC element (80) arranged between parallel contact plates (82), and a terminal housing (6) in which at least one power-loss-generating circuit breaker (178) is provided, to which a heat sink (32) exposed on the outside of the terminal housing (6) is associated. An improved electric heating device that provides sufficient cooling of the circuit breaker (178) is achieved by the heat sink (32) being inserted into the terminal housing (6) in a sealing manner.