Mat Joint Positioning for Electric Heating Catalyst Insulation
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Solution Overview
Problem
In exhaust gas control apparatuses for internal combustion engines, electric leakage paths form due to carbon deposition and moisture accumulation, leading to potential electric leakage during energization of the electric heating catalyst, as the joint of the mat holding the downstream side catalyst often accumulates water, creating a conductive path.
Innovation Solution
The joint of the mat is positioned above the vertically lowermost portion in the outer tube to avoid water accumulation, and the electric heating catalyst is held via a second mat with its joint also positioned away from the lowermost area, preventing the formation of electric leakage paths and reducing the risk of leakage during energization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the joint of the mat is positioned in the vertically lower portion for easy manufacturing and installation, then the manufacturing and assembly process is simplified, but water accumulates at the joint creating an electric leakage path
Solution Approach 1:
The mat joint is positioned at a specific location (vertically upper portion or side portion) rather than uniformly distributed, creating local quality differentiation. This positioning avoids water accumulation zones while maintaining manufacturing feasibility, resolving the contradiction between ease of assembly and electrical insulation reliability.
2Object-affected harmful factors
If the mat is made conductive to prevent static electricity, then static electricity control is improved, but electric leakage occurs when moisture and carbon deposit on the mat
Solution Approach 1:
The electrical conductivity parameter of the mat is changed from conductive to insulating. This parameter change prevents electric leakage paths when moisture and carbon deposits occur, while still controlling static electricity through alternative means such as proper grounding of the exhaust pipe system.
3Productivity
If the electric heating catalyst is energized to heat the exhaust gas quickly, then the catalyst activation time is reduced, but electric leakage may occur during energization due to moisture accumulation
Solution Approach 1:
The insulating mat serves as an intermediary barrier between the electric heating catalyst and the exhaust pipe. This intermediary prevents electric leakage paths even when moisture accumulates, allowing the catalyst to be energized for quick activation without compromising electrical insulation reliability.
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 suppresses electric leakage path formation and occurrence, ensuring reliable operation of the electric heating catalyst by positioning the joints away from areas prone to water accumulation, thereby preventing electric leakage.
Implementation Method 1
an electric heating catalyst configured to be held in the exhaust passage via a second mat
Implementation Method 2
an outer tube having an electrical insulation property connected to an exhaust pipe having an electrical conductive property
Implementation Method 3
water is likely to accumulate in the vertically lower portion of the downstream side catalyst
Data Source
AI summary
An exhaust gas control apparatus for an internal combustion engine includes an outer tube, a downstream side catalyst held in the outer tube via a first mat, and an electric heating catalyst held in the outer tube via a second mat upstream of the downstream side catalyst. A joint of the first mat is disposed in a place other than a vertically lowermost portion.