Exhaust Gas Purifying Device Slidable Attachment for Thermal Stress
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Solution Overview
Problem
The existing exhaust gas purifying devices for internal combustion engines, particularly in large vehicles like construction machines, face issues with insufficient attachment strength and thermal stress due to dimensional changes caused by high temperatures, leading to durability concerns.
Innovation Solution
The exhaust gas purifying device is designed with a cylindrical case attached at two points: one point is firmly fixed upstream of the soot filter using a flange and attachment plates, while the other point is slidably attached downstream using U-bolts, allowing for thermal expansion and reducing stress concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the case is firmly fixed via a bracket welded to the case, then attachment strength is improved, but a dimensional change due to thermal expansion cannot be accepted and thermal stress is generated which decreases durability
Solution Approach 1:
The attachment system is divided into two separate attachment points: a first attachment point for firm fixation and a second attachment point for slidable attachment. This segmentation allows different attachment characteristics at different locations, resolving the contradiction between needing strong attachment and accommodating thermal expansion.
Solution Approach 2:
Different attachment methods are applied at different locations: the first attachment point uses firm fixation (via flange and attachment plate) while the second attachment point uses slidable fixation (via U-bolts). This local differentiation allows the system to achieve both strong overall attachment and local flexibility for thermal expansion.
2Reliability
If the case is attached slidably at both attachment points, then thermal expansion is accommodated, but attachment strength is insufficient and the position shifts during operation
Solution Approach 1:
The attachment system is divided into two separate attachment points with different characteristics: one for firm fixation and one for slidable attachment. This segmentation ensures that not all attachment points are made slidable, maintaining sufficient overall attachment strength while providing flexibility where needed.
Solution Approach 2:
Different attachment methods are applied at different locations: the first attachment point uses firm fixation to maintain position, while the second attachment point uses slidable fixation to accommodate thermal expansion. This local differentiation resolves the contradiction between needing strong attachment and allowing thermal movement.
3Ease of manufacture
If U-bolts only are used for attachment, then ease of installation is improved, but attachment strength is not sufficient and position shifts during operation
Solution Approach 1:
Two different attachment methods are merged into a single attachment system: flange and attachment plate connection combined with U-bolt connection. This combination merges the advantages of both methods: the flange provides strong structural attachment while the U-bolts provide easy installation and adjustment capability.
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 ensures reliable attachment and improved durability by preventing thermal stress and maintaining the position of the exhaust gas purifying device during operation, even under high temperatures.
Implementation Method 1
captured particulate matter should be combusted to regenerate the soot filter, so that the exhaust aftertreatment device is heated to a high temperature due to the combustion temperature
Implementation Method 2
the case in which the exhaust aftertreatment device is housed is thermally expanded
Data Source
AI summary
An exhaust gas purifying device for an internal combustion engine includes an inflow case provided with an inlet pipe, a catalyst case in which an oxidizing catalyst for dosing is housed, a filter case in which a soot filter is housed, and an outflow case provided with an outlet pipe, and is attached to an attached target at two attachment points mutually spaced in the axial direction of the cases. At one of the two attachment points, which is defined on the catalyst case, the catalyst case is firmly fixed. At the other attachment point, which is defined on the filter case, the filter case is attached slidably in the axial direction.