Heating device for heating a gas flow
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Solution Overview
Problem
Existing heating devices for exhaust gas streams from internal combustion engines are often unreliable and complex, failing to efficiently bring the system to the required temperature for effective catalytic reactions during cold starts, and face issues with electrical insulation and mechanical stress.
Innovation Solution
A heating device with an electrically conductive heating element featuring separate heating segments and a carrier device with spacer sections for insulation, housed within a robust structure that includes bearing mats for thermal and mechanical support, ensuring reliable operation and easy integration into exhaust systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a heating device with continuous heating path is used, then heating efficiency is improved, but electrical insulation reliability deteriorates due to potential short circuits between segments
Solution Approach 1:
The heating element is divided into multiple discrete heating segments separated by gaps. Each segment is electrically isolated from others, preventing short circuits while maintaining heating functionality. The segments are arranged in a meandering pattern to provide multiple heating zones along the exhaust gas flow path.
Solution Approach 2:
Electrically insulating support elements are introduced as intermediary components between adjacent heating segments. These support elements with spacer sections physically separate the conductive segments, ensuring electrical isolation while providing mechanical support and maintaining the structural integrity of the heating device.
2Productivity
If heating segments are placed close together to maximize heating path, then heating efficiency is improved, but risk of short circuits increases due to vibrations and thermal expansion
Solution Approach 1:
Spacer sections protruding from the support elements are designed in advance to compensate for thermal expansion and vibration-induced movements. These spacers create predetermined clearance gaps between heating segments, preventing contact and potential short circuits even when segments expand or vibrate during operation.
Solution Approach 2:
The support elements with spacer sections act as intermediary buffer zones between adjacent heating segments. They absorb dimensional changes due to thermal expansion and mechanical vibrations, maintaining consistent electrical isolation without requiring the segments themselves to be rigid or immovable.
3Reliability
If gaps between heating segments are made larger to ensure insulation, then electrical reliability is improved, but heating efficiency deteriorates due to reduced heat transfer to gas flow
Solution Approach 1:
The heating path is segmented into multiple zones rather than using a single continuous element. This allows strategic placement of gaps at specific locations where electrical isolation is critical, while maintaining continuous heating coverage through the meandering arrangement of segments. The segmentation enables differentiated gap sizing based on local electrical insulation requirements.
Solution Approach 2:
The heating segments are arranged in a meandering, multi-dimensional pattern through the exhaust gas flow path rather than simple linear spacing. This three-dimensional arrangement maximizes the total heating surface area and gas contact time, compensating for the reduced heat transfer efficiency in gap regions by providing alternative heating zones along the flow path.
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 provides reliable and efficient heating of exhaust gas streams, preventing electrical short circuits and withstanding thermal and mechanical stress, while simplifying integration and assembly, thus ensuring effective catalytic reactions even during cold starts.
Implementation Method 1
This creates the longest possible heating path between the disc's electrical contacts, which heats up quickly when energized due to its ohmic resistance.
Implementation Method 2
This results in heat transfer from the heated disk to the gas stream.
Implementation Method 3
This gas stream, in turn, heats the catalyst body to bring it to the aforementioned operating temperature as quickly as possible.
Data Source
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AI summary
The present invention relates to a heating device for heating a gas stream, in particular an exhaust gas stream of an internal combustion engine, comprising an electrically conductive heating element through which the gas stream flows in the axial direction, the heating element having at least two heating segments which are separated from each other section by a gap which is in particular open on one side, a support device with at least one electrically insulating support element which surrounds the heating element at least section by circumferential direction and/or covers an edge region of at least one axial end face of the heating element at least section by section, wherein the support element has at least a spacer section which projects into the gap, and a housing section in which the heating element and the support device are held.