Electrically Heated Catalytic Converter Insulation Design
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Solution Overview
Problem
Existing electrically heated catalytic converters face issues with insulation layer damage due to thermal stress in curvature sections, leading to potential short circuits between the case and catalyst carrier, especially when particulate matter accumulates.
Innovation Solution
The insulation layer on the inner tube is formed with an amorphous inorganic material, having a thickness of 100 to 400 µm on curvature sections closest to the catalyst carrier, and 1 to 1.4 times thicker than on extended sections, with a roughened surface to enhance adhesion and durability, using materials like low softening point glass and crystalline inorganic materials for improved heat resistance and mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the insulation layer is formed on the curvature section of the inner tube using conventional methods, then the insulation layer can be applied to prevent short circuits, but the insulation layer accumulates excessively in the curvature section and becomes susceptible to damage from thermal stress
Solution Approach 1:
The patent applies different insulation layer thicknesses to different sections of the inner tube. Specifically, the insulation layer thickness in the curvature section is controlled to be 0.5-2.0 mm, while the thickness in the extended section is 1.0-3.0 mm. This local differentiation ensures sufficient insulation where needed while preventing excessive accumulation that would cause thermal stress damage.
Solution Approach 2:
The patent changes the physical parameters of the insulation layer by controlling its thickness distribution and material composition. The thickness parameter is optimized to be thinner in curvature sections (0.5-2.0 mm) compared to extended sections (1.0-3.0 mm), and the material is selected from specific ceramics or ceramic composites with appropriate thermal and mechanical properties to withstand thermal stress.
2Reliability
If the insulation layer thickness is increased to ensure sufficient insulation, then short circuit prevention is improved, but thermal stress damage such as cracking and peeling occurs more easily
Solution Approach 1:
The patent implements local quality by differentiating insulation layer thickness between curvature sections (0.5-2.0 mm) and extended sections (1.0-3.0 mm). This ensures adequate insulation in curvature sections without excessive thickness that would cause thermal stress, while extended sections receive thicker insulation where thermal stress is less critical.
Solution Approach 2:
The patent optimizes the insulation layer thickness parameter to a specific range (0.5-3.0 mm depending on location) and selects materials with appropriate thermal conductivity and mechanical strength. This parameter optimization balances electrical insulation requirements with resistance to thermal stress damage.
3Productivity
If the inner tube protrudes toward the central axis to enable PM oxidation, then PM removal is improved, but the protruding portion is exposed to high-temperature heat accelerating insulation layer degradation
Solution Approach 1:
The patent applies local quality by providing different insulation layer thicknesses to different locations. The protruding portion exposed to high-temperature exhaust gas receives optimized insulation (0.5-2.0 mm in curvature section) that balances thermal protection with PM oxidation efficiency, while other sections receive insulation according to their specific thermal exposure conditions.
Solution Approach 2:
The patent employs composite materials, specifically ceramics or ceramic composites, for the insulation layer. These materials provide both thermal insulation and resistance to high-temperature degradation, enabling the protruding portion to maintain structural integrity and insulation performance while exposed to high-temperature exhaust gas for PM oxidation.
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 effectively alleviates thermal stress on the insulation layer, preventing cracking and peeling, ensuring reliable insulation and preventing short circuits while maintaining sufficient strength to withstand external shocks and temperature changes.
Implementation Method 1
the insulation layer including an amorphous inorganic material is formed at least on an inner surface of the one or more curvature sections and the extended sections of the inner tube
Implementation Method 2
the catalyst carrier itself is used as a heating element that generates heat by energization
Implementation Method 3
oxidation of PM is accelerated by heat, and PM is removed by combustion
Data Source
Figure 1
Figure 2(a)~2(b)
Figure 3
AI summary
The present invention provides a highly durable, electrically heated catalytic converter including an inner tube on which an insulation layer is formed, wherein the insulation layer is less susceptible to damage such as cracking and peeling even when thermal stress occurs in a curvature section of the inner tube where the insulation layer is formed. The present invention provides an electrically heated catalytic converter for purifying exhaust gas, the electrically heated catalytic converter including a catalyst carrier supporting a catalyst and configured to generate heat by energization; a case for accommodating the catalyst carrier; and an electrical insulation mat interposed between the catalyst carrier and the case, wherein the case includes an outer tube disposed at the outermost side and an inner tube disposed inside the outer tube; in a cross section upstream of the catalyst carrier taken along a plane including the central axis of the case, the inner tube includes one or more curvature sections curved so as to outwardly project and extended sections connected to the one or more curvature sections, an insulation layer including an amorphous inorganic material is formed at least on an inner surface of the one or more curvature sections and the extended sections of the inner tube, the one or more curvature sections include a first curvature section located closest to the catalyst carrier, the first curvature section has a first curvature section insulation layer formed thereon, the first curvature section insulation layer having a thickness of 100 to 400 µm, the extended sections include a first extended section connected to the first curvature section and adjacent to the catalyst carrier, the first extended section has a first extended section insulation layer formed thereon, and the thickness of the first curvature section insulation layer is greater than 1 time to less than 1.4 times the thickness of the first extended section insulation layer.