Spherical Seal Member with Solid Lubricant Layer
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Solution Overview
Problem
Existing spherical annular seal members for exhaust pipe joints generate abnormal frictional noise due to differences in static and dynamic friction coefficients of heat-resistant materials and can wear down under continuous oscillating motions or axial loads, leading to damage and reduced sealability.
Innovation Solution
A spherical annular seal member with laminated partially convex spherical intermediate layers and an outer layer featuring a knitted metal wire net and expanded graphite, where the reinforcing member and solid lubricant are exposed in a mixed form, reducing frictional loads and preventing wear, and the seal member is manufactured using specific knitted metal wire nets and expanded graphite sheets to ensure effective lubrication and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If heat-resistant material (expanded graphite) is used for the spherical seal member, then heat resistance and affinity with mating member are improved, but abnormal frictional noise is generated under dry frictional conditions
Solution Approach 1:
A solid lubricant layer is introduced as an intermediary between the heat-resistant expanded graphite seal member and the mating member. This lubricant layer mediates the frictional contact, preventing direct dry friction between the graphite surfaces and eliminating abnormal noise while preserving the heat resistance properties of the expanded graphite base material.
Solution Approach 2:
The seal member is constructed as a composite structure combining expanded graphite (heat-resistant base material) with a solid lubricant coating (surface layer). This composite approach allows the inner expanded graphite layer to provide heat resistance and structural integrity, while the outer solid lubricant layer provides low-friction, noise-free operation under sliding conditions.
2Temperature
If heat-resistant material is used for the spherical seal member, then heat resistance is improved, but frictional resistance exhibits negative resistance with respect to sliding velocity
Solution Approach 1:
The solid lubricant acts as a mediator that replaces the problematic direct contact friction mechanism of expanded graphite with a more favorable lubrication mechanism. The lubricant layer provides consistent frictional resistance characteristics that do not exhibit negative velocity dependence, while allowing the expanded graphite to maintain its heat-resistant function.
Solution Approach 2:
The surface friction characteristics are changed by applying a solid lubricant coating, which fundamentally alters the friction mechanism from dry graphite-on-graphite contact to lubricated contact. This parameter change in the friction interface eliminates the negative resistance effect with respect to sliding velocity while preserving the thermal properties of the base material.
3Ease of operation
If the spherical seal member undergoes continuous oscillating motions or axial loads, then the seal member experiences wear, but durability is reduced
Solution Approach 1:
The solid lubricant layer is applied in advance as a protective cushioning layer on the surface of the expanded graphite seal member. This pre-applied lubricant layer cushions and protects the underlying heat-resistant material from wear during continuous oscillating motions and axial loading, preventing direct abrasive contact and extending the service life of the seal member.
Solution Approach 2:
The composite structure of expanded graphite base material plus solid lubricant coating provides both the operational flexibility needed for oscillating motions and the wear resistance required for long-term durability. The expanded graphite provides structural integrity and heat resistance, while the solid lubricant layer provides wear protection during continuous operation.
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
The solution effectively prevents abnormal frictional noise and surface damage, maintaining sealability even under prolonged exposure to oscillating motions and axial loads, by distributing the load across the reinforcing and heat-resistant material surfaces, thus enhancing the durability and performance of the seal member.
Implementation Method 1
a solid lubricant layer formed of a lubricating composition... effectively prevents abnormal frictional noise and surface damage... by distributing the load across the reinforcing and heat-resistant material surfaces
Data Source
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AI summary
A spherical annular seal member 46 includes a spherical annular base member 42 defined by a cylindrical inner surface 38, a partially convex spherical surface 39, and large- and small-diameter side annular end faces 40 and 41 of the partially convex spherical surface 39; a plurality of partially convex.spherical intermediate layers 43 formed integrally on the partially convex spherical surface 39 of the spherical annular base member 42 and laminated in a radial direction; and an outer layer 45 formed integrally on a partially convex spherical surface 44 of the outermost partially convex spherical intermediate layer 43 of these partially convex spherical intermediate layers 43.