Heatable Honeycomb Body with Merged Sheet Metal Layers
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Solution Overview
Problem
Existing electrically heated honeycomb bodies for exhaust gas treatment systems face challenges in achieving uniform current distribution and stable electrical connections, often requiring complex current distribution structures and supporting pins to prevent overheating and ensure insulation.
Innovation Solution
A honeycomb body with multiple sheet metal layers connected to a single connecting pin, using resistance welding for electrical conductivity, which eliminates the need for current distribution structures and stabilizing half shells, ensuring a stable and cost-effective construction with controlled electrical resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If complex current distribution structures and supporting pins are used to ensure uniform current distribution and stable connections, then electrical connection reliability is improved, but device complexity increases
Solution Approach 1:
The patent combines multiple sheet metal layers (at least five layers) into a single stack structure that collectively forms one central current path. This merging approach eliminates the need for separate current distribution structures and multiple supporting pins, as the stacked configuration inherently provides both current distribution and mechanical stability. The insulating layers between sheets further simplify the structure by preventing short circuits without requiring additional complex insulation mechanisms.
Solution Approach 2:
The stack of sheet metal layers serves multiple functions simultaneously: it provides electrical conduction (forming the central current path), mechanical support (stabilizing the honeycomb body structure), and thermal management (distributing heat uniformly). The insulating layers between sheets add electrical insulation while maintaining the compact stacked structure. This multi-functionality eliminates the need for separate dedicated components for each function, reducing overall device complexity.
2Manufacturing precision
If multiple sheet metal layers are stacked to form a central current path, then uniform current distribution is improved, but manufacturing complexity increases
Solution Approach 1:
The patent segments the current path into multiple parallel sheet metal layers (at least five layers) stacked together. Each sheet carries a portion of the current, and the collective stack forms the complete central current path. This segmentation naturally distributes current uniformly across all layers, ensuring consistent heating along the entire length of the honeycomb body without requiring complex current distribution structures.
Solution Approach 2:
The patent uses a composite structure combining multiple sheet metal layers with insulating layers (such as ceramic or plastic coatings) between them. This composite approach provides both electrical conduction (through the metal sheets) and electrical insulation (through the insulating layers), enabling uniform current distribution while simplifying manufacturing by integrating multiple functions into a single stacked assembly that can be produced using standard metallurgical and coating processes.
3Device complexity
If the connecting pin connects to multiple sheet metal layers directly, then electrical connection simplicity is improved, but connection region overheating risk increases
Solution Approach 1:
The patent connects the connecting pin to multiple sheet metal layers (at least two layers) simultaneously at the connection point. By merging multiple conductive paths in parallel at the connection region, the overall electrical resistance is reduced, allowing the simple direct connection structure to dissipate heat effectively without overheating. This maintains both structural simplicity and thermal safety.
Solution Approach 2:
The patent changes the electrical resistance parameter in the connection region by connecting the pin to multiple sheet metal layers in parallel. This reduces the effective resistance at the connection point, thereby reducing ohmic heating (Q=I²R) and preventing overheating. The insulating layers between sheets also help manage thermal characteristics by providing thermal barriers while maintaining electrical connectivity through the metal layers.
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 configuration allows for uniform current distribution and stable electrical connections, preventing overheating and maintaining efficient gas flow while simplifying manufacturing and reducing costs by eliminating the need for complex structures.
Implementation Method 1
The connecting pin is metallically connected by an electrically conductive connection, in particular by using resistance welding, to at least two of the sheet metal layers
Implementation Method 2
The multiple sheet metal layers are electrically connected to one another in an axial direction and together form at least one central electrically conductive current path
Data Source
AI summary
A honeycomb body includes sheet metal layers forming a central current path to a radial connecting pin. A metal casing has an inner periphery and a feedthrough guiding and insulating the pin. The layers are alternate coarsely structured and finely structured or smooth sheets forming a stack with uppermost and lowermost layers forming axial gas channels. The pin is metallically connected to two or all of the layers directly or through an intermediate piece by an electrically conductive or welded connection. The current path has an electrical resistance per unit length in the connection region being greater than an average electrical resistance per unit length in the stack. The uppermost layer runs approximately parallel to the casing over 35% or 40% of the inner periphery and is separated from the casing by an air gap. Simple manufacture of a highly uniform, reliably operating, electrically heatable honeycomb body is thus possible.