Valve Stem Seal with Metallic Ring and Stop Ring
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Solution Overview
Problem
Conventional valve stem seal devices suffer from insufficient mechanical strength and reduced fitting force due to thermal influences and aging, leading to compromised seal function and potential detachment from the valve stem guide under vibration or pressure loads.
Innovation Solution
A valve stem seal device featuring a cylindrical metallic ring with a seal lip made of rubbery elastic material, a stop ring with a cut part for enhanced engagement, and a movement limiting mechanism, such as a flange portion or retaining ring, to maintain mechanical strength and prevent detachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a projection made of rubbery elastic material is used to engage with the valve stem guide, then the valve stem seal can be fixed to the valve stem guide, but the mechanical strength is insufficient and the fitting force is lowered by thermal influence and aging
Solution Approach 1:
The invention combines a metallic ring (high strength) with a rubbery elastic material layer (sealing function) to create a composite structure. The metallic ring provides the necessary mechanical strength for engagement with the valve stem guide, while the rubbery elastic material layer maintains the sealing function. This composite approach resolves the contradiction by assigning different functions to different materials based on their inherent properties.
Solution Approach 2:
The valve stem seal is divided into distinct functional segments: a metallic ring for structural strength and engagement, and a rubbery elastic material layer for sealing. The projection is also segmented with the metallic ring providing the engagement structure and the rubbery elastic material providing flexibility and sealing at the engagement interface. This segmentation allows each part to optimize its specific function without compromising the other.
2Reliability
If the valve stem seal is fixed using only rubbery elastic material, then the seal function can be maintained, but the valve stem seal may fall away under vibration or pressure loads
Solution Approach 1:
The metallic ring provides the necessary holding force to resist vibration and pressure loads, while the rubbery elastic material layer maintains the seal function. The combination of these two materials with different properties allows the structure to simultaneously achieve high holding force and reliable sealing, resolving the contradiction between these two requirements.
Solution Approach 2:
Different regions of the valve stem seal have different material properties optimized for their specific functions: the metallic ring region provides high strength and rigidity for load-bearing and engagement, while the rubbery elastic material region provides flexibility and sealing capability. This local differentiation of material quality allows each region to perform its specific function effectively.
3Stability of the object's composition
If a projection is used to engage with the valve stem guide, then the valve stem seal can be retained, but the fitting force is reduced by thermal influence and change with time
Solution Approach 1:
The metallic ring provides stable dimensional properties that are not significantly affected by thermal influence or aging, maintaining the engagement geometry over time. The rubbery elastic material layer compensates for thermal expansion and contraction through its elasticity, maintaining the seal function. This composite structure resolves the contradiction by having the metallic component provide long-term dimensional stability and the rubbery component provide thermal compensation.
Solution Approach 2:
The rubbery elastic material's physical properties change with temperature and age, but these changes are beneficial rather than harmful. The material becomes slightly stiffer with age, which can improve engagement stability, and thermal expansion/contraction is accommodated by the elastic nature of the material, maintaining the seal. This parameter change approach resolves the contradiction by utilizing rather than resisting the effects of time and temperature.
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 provides a robust seal function that withstands vibration and pressure loads, ensuring the valve stem seal remains securely fixed to the valve stem guide, with easy detachment and enhanced fitting force.
Implementation Method 1
a seal lip which is integrally formed in an end side of the metallic ring, hermetically slides in relation to the valve stem, and is made of a rubbery elastic material
Data Source
AI summary
A valve stem seal device has a valve stem guide, a cylindrical metallic ring retained to an outer periphery of the valve stem guide, a rubbery elastic seal lip integrally formed in one end side of the metallic ring, and hermetically sliding to the valve stem, and a valve stem seal having the cylindrical metallic ring and the seal lip and fixed to the valve stem guide side. The valve stem seal device has a stop ring retained between a circular-truncated-cone-shaped surface which is expanded toward a side of the seal lip formed in an outer peripheral surface of the valve stem guide, and a cylindrical inner peripheral surface of the metallic ring. The stop ring has a cut part, and a movement limiting means for limiting a movement in an axial direction of the stop ring is provided in the other end side of the metallic ring.