Spring-Loaded PTFE Seal Structure for Settling-Resistant Lips
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Solution Overview
Problem
The existing sealing devices using PTFE for annular gaps between shafts and housings face deterioration of sealing properties due to plastic deformation (settling) at high temperatures, as PTFE has a higher linear expansion coefficient than metal materials, leading to inadequate sealing performance.
Innovation Solution
A sealing device with a resin packing and a metal spring member, where the protrusion to prevent the spring member from coming off is only on the inner circumferential lip, reducing the rigidity of the outer circumferential lip and increasing the influence of the spring member's pressing portion, maintaining sealing properties over time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a protrusion is provided on both outer circumferential lip and inner circumferential lip to prevent spring member from coming off, then the spring member is securely retained, but the rigidity of the outer circumferential lip increases, reducing the effectiveness of the pressing portion in suppressing settling
Solution Approach 1:
The protrusion is provided only on the inner circumferential lip rather than on both lips, creating local differentiation. This allows the outer circumferential lip to maintain lower rigidity so that the pressing portion can effectively suppress settling, while the inner circumferential lip with the protrusion prevents the spring member from coming off.
2Strength
If the outer circumferential lip is made with high rigidity to maintain structural integrity, then the spring member is retained securely, but the pressing portion cannot effectively suppress settling of the lip
Solution Approach 1:
The protrusion is localized only on the inner circumferential lip, allowing the outer circumferential lip to have lower rigidity and be more responsive to the pressing force from the spring member, thereby suppressing settling effectively while maintaining overall structural integrity through the inner lip's protrusion.
3Stability of the object's composition
If the protrusion is provided on the outer circumferential lip to prevent spring member from coming off, then the spring member is retained, but the rigidity of the outer circumferential lip increases, reducing the influence of the pressing portion
Solution Approach 1:
The protrusion is positioned only on the inner circumferential lip, creating local structural differentiation. This ensures that the outer circumferential lip remains sufficiently flexible to respond to the pressing force from the spring member, maximizing the effectiveness of the pressing action in suppressing settling.
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 suppresses the deterioration of sealing properties by lowering the rigidity of the outer circumferential lip, ensuring long-term sealing performance and wear allowance for the inner circumferential lip, while preventing the spring member from sticking out.
Implementation Method 1
a metal spring member mounted in the mounting groove and having an outer circumferential pressing portion extending radially outward and toward the sealed fluid side from a groove bottom of the mounting groove and pressing the outer circumferential lip radially outward, and an inner circumferential pressing portion extending radially inward and toward the sealed fluid side from the groove bottom of the mounting groove and pressing the inner circumferential lip radially inward
Implementation Method 2
PTFE has a higher linear expansion coefficient than that of metal materials commonly used as the housing material. In high temperature environments, therefore, the sealing lip on an outer circumferential side of the packing (outer circumferential lip) tends to deform so as to expand radially outward
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
Provided is a sealing device that can suppress deterioration of sealing properties due to plastic deformation (settling) of an outer circumferential lip. The sealing device is characterized by including a packing (10) made of resin having an outer circumferential lip (12) on an outer circumferential side with respect to an annular mounting groove (11) provided on a sealed fluid side and an inner circumferential lip (13) on an inner circumferential side with respect to the annular mounting groove (11), and a metal spring member (20) mounted in the mounting groove (11) and having an outer circumferential pressing portion (21) that extends radially outward and toward the sealed fluid side from a groove bottom of the mounting groove (11) and presses the outer circumferential lip (12) radially outward, and an inner circumferential pressing portion (22) that extends radially inward and toward the sealed fluid side from the groove bottom of the mounting groove (11) and presses the inner circumferential lip (13) radially inward. Among the outer circumferential lip (12) and the inner circumferential lip (13), a protrusion (13a) for preventing the spring member (20) from coming off is provided only on the inner circumferential lip (13).