Exhaust Pipe Subassembly Tolerance Compensation
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Solution Overview
Problem
The assembly of curved pipes in exhaust treatment devices faces challenges due to large manufacturing tolerances, leading to difficulties in fitting and sealing, which can result in poor weld quality and potential fluid leaks, as the existing aperture sizes often do not accommodate the varying dimensions of the pipes effectively.
Innovation Solution
The method involves defining aperture sizes based on manufacturing tolerances to ensure a tight fit for the first linear portion of the pipe, while allowing the second linear portion to be expanded for a secure seal, thereby accommodating pipes with varying tolerances and ensuring consistent weld locations for improved assembly and reduced costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If curved pipes are manufactured using traditional bending operations, then the pipes can be formed with curved geometry, but the true position tolerance between inlet and outlet centerlines becomes large
Solution Approach 1:
The patent applies preliminary action by pre-defining the aperture sizes in the metal sheet based on the expected pipe dimension variations. The first aperture is sized to accommodate pipes with larger deviations from nominal dimensions, while the second aperture is sized for pipes closer to nominal dimensions. This preliminary sizing strategy ensures that pipes with large manufacturing tolerances can still be properly fitted and sealed, resolving the contradiction between achieving curved geometry and maintaining manufacturing precision.
2Adaptability or versatility
If aperture sizes are defined to accommodate large pipe tolerances, then pipe fitment is improved, but weld quality and sealing reliability deteriorate
Solution Approach 1:
The patent applies local quality by creating different aperture sizes at different locations in the metal sheet. The first aperture (for the first linear portion) is defined with a size that accommodates pipes with large tolerances, ensuring fitment. The second aperture (for the second linear portion) is defined with a size optimized for weld quality and sealing reliability. This localized differentiation allows the system to simultaneously achieve both adaptability to tolerance variations and high reliability in critical sealing areas.
3Ease of manufacture
If a single aperture size is used for both linear portions, then manufacturing is simplified, but pipes with varying tolerances cannot be properly accommodated
Solution Approach 1:
The patent applies segmentation by dividing the aperture definition into two distinct apertures with different size criteria. The first aperture size is determined based on the need to accommodate pipes with large dimension variations, while the second aperture size is determined based on different tolerance considerations. This segmentation allows each aperture to be optimized for its specific function, enabling the system to accommodate pipes with varying tolerances while maintaining a relatively simple manufacturing process.
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 approach enables the use of a variety of pipes with large manufacturing tolerances, ensuring proper fitment and sealing, reducing the risk of leaks and improving the quality of weld joints, while maintaining cost-effectiveness and ease of assembly.
Implementation Method 1
expanding the second linear portion to increase the fourth size to an enlarged size until a second difference between the second size and the enlarged size is less than or equal to the predetermined value
Implementation Method 2
sealingly fixing the first linear portion of the one-piece pipe to the metal sheet
Implementation Method 3
A curved pipe may include a 180° bend (e.g., J pipe or U pipe), a 90° bend, or multiple bends (e.g., S pipe). Curved pipes may be manufactured in a bending operation
Data Source
AI summary
A method of manufacturing a subassembly for an exhaust treatment device includes providing a metal sheet including first and second apertures having respective first and second sizes, and a one-piece pipe including first and second linear portions having respective third and fourth sizes. The method further includes defining the first size based on a first difference between the first size and the third size being less than or equal to a predetermined value, and defining the second size based on manufacturing tolerances of the pipe to assure that the second linear portion will pass through the second aperture while the first linear portion passes through the first aperture. The method further includes fixing the first linear portion to the sheet, expanding the second linear portion from the fourth size to an enlarged size less than or equal to the predetermined value, and fixing the second linear portion to the sheet.