Exhaust Purifying Device Buffer Member Press-Fit Coupling
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Solution Overview
Problem
Conventional exhaust purifying devices for internal combustion engines face challenges in durability and production efficiency due to the use of welding at heat-expansion areas and the need for miniaturization, which complicates the design and increases costs.
Innovation Solution
The design incorporates a buffer member with recesses and a setting member that securely fits into these recesses, eliminating the need for welding at heat-expansion areas, enhancing durability and production efficiency by using a holding mechanism that regulates the buffer member's position without welding, allowing for better stress distribution and reduced deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If welding is performed at the edge section of the case member to strengthen coupling, then coupling strength is improved, but durability deteriorates due to repeated thermal expansion and contraction
Solution Approach 1:
The patent removes the welding process from the heat-expansion area (edge section of case member) and extracts only the necessary coupling function. The stopper member is press-fitted into the case member at a position away from the edge section, eliminating welding from the thermal stress zone while maintaining coupling strength.
Solution Approach 2:
The patent introduces a mat as an intermediary component between the stopper member and the case member. This mat enables coupling without direct welding at the edge section, mediating the connection and avoiding thermal damage to the case member's edge area.
2Strength
If welding is used to secure the stopper member, then coupling strength is improved, but production efficiency deteriorates due to the complexity of the welding process
Solution Approach 1:
The patent replaces the welding process (thermal/chemical joining) with a press-fitting mechanical joining method. The stopper member is secured to the case member through press-fitting combined with friction engagement, eliminating the need for welding equipment and processes while maintaining coupling strength.
3Strength
If the contact area between stopper member and case member is increased to strengthen coupling, then coupling strength is improved, but device length increases inhibiting miniaturization
Solution Approach 1:
The patent transitions from increasing contact area in the axial direction (which would lengthen the device) to increasing contact area in the radial direction. The stopper member engages the case member through radial press-fitting and circumferential friction, achieving strong coupling without extending the axial length of the device.
Data Source
AI summary
An exhaust purifying device provided in an exhaust passage of an internal combustion engine comprises: a column-shaped honeycomb carrier; a cylindrical case member adapted to house the honeycomb carrier; a holding member provided between the honeycomb carrier and the case member to surround the outer circumference of the honeycomb carrier; buffer members provided on a peripheral edge of the edge surface of at least one side of an inflow side edge surface and an outflow side edge surface of the honeycomb carrier so as to regulate the movement of the honeycomb carrier in the central axis X direction; and setting members secured to the case member to regulate the movement of the buffer members by allowing their position regulation parts to contact the buffer members; wherein the buffer members are provided, on the outer circumferential sides, with recesses into which the position regulation parts of the setting members are fitted.