Spherical Annular Seal Protrusions for Exhaust Pipe Assembly
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Solution Overview
Problem
The assembly workability of spherical annular seal members in exhaust pipe joints is compromised due to the risk of the seal member falling off during assembly, especially when there is a large clearance between the cylindrical inner surface and the outer peripheral surface of the exhaust pipe, and making the clearance too small leads to difficulty in installation due to manufacturing errors.
Innovation Solution
The spherical annular seal member features at least three protrusions made of expanded graphite that extend between the large- and small-diameter side annular end faces, which are designed to protrude from the cylindrical inner surface and scrape off during insertion, ensuring a secure fit and reducing the risk of leakage, while an outer layer with a mixed surface of reinforcing member and solid lubricant improves sliding and prevents abnormal frictional noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the clearance between the cylindrical inner surface and the outer peripheral surface of the exhaust pipe is made large, then it is easy to install the spherical annular seal member, but the seal member may come off and fall down during assembly work
Solution Approach 1:
The protrusions are pre-formed on the cylindrical inner surface before assembly. During installation, these protrusions automatically engage with the exhaust pipe's outer surface, creating a preliminary mechanical interlock that prevents the seal member from falling down while still allowing for installation with reasonable clearance
2Reliability
If the clearance between the cylindrical inner surface and the outer peripheral surface of the exhaust pipe is made small, then the risk of seal member falling down is reduced, but it becomes difficult to dispose the seal member due to manufacturing errors
Solution Approach 1:
Instead of uniformly reducing the clearance around the entire cylindrical inner surface, the invention locally adds protrusions at specific positions. This allows the clearance to remain relatively large for easy installation while creating localized contact points that prevent the seal member from falling down
3Reliability
If the protrusions are made to scrape off during insertion, then close contact with the exhaust pipe is achieved and leakage is prevented, but the protrusions are consumed
Solution Approach 1:
The protrusions are designed as sacrificial elements made of expanded graphite that are intended to be consumed during the initial insertion process. This consumption achieves the primary goal of creating close contact and preventing leakage, while the loss of material is acceptable given the improved sealing performance and assembly 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 design enhances assembly workability by preventing the seal member from falling off and reduces the risk of exhaust gas leakage, while maintaining smooth sliding and minimizing abnormal frictional noise over extended periods.
Implementation Method 1
at least three protrusions, which are formed of expanded graphite capable of being scraped off by an exhaust pipe when inserted into a through hole defined by the cylindrical inner surface
Implementation Method 2
an outer layer formed integrally on the partially convex spherical surface of the spherical annular base member... an outer surface of the outer layer being formed into a smooth surface in which surfaces constituted by the reinforcing member and surfaces constituted by the solid lubricant are present in mixed form
Data Source
Figure 1(a)~2
Figure 3~4(b)
Figure 5~6
AI summary
A spherical annular seal member 35 for use in an exhaust pipe joint includes: a spherical annular base member 33 defined by a cylindrical inner surface 29, a partially convex spherical surface 30, and large- and small-diameter side annular end faces 31 and 32 of the partially convex spherical surface 30; and an outer layer 34 formed integrally on the partially convex spherical surface 30 of the spherical annular base member 33.