Reciprocating Shaft Seal Stabilizing Friction via Lip Segmentation
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Solution Overview
Problem
Conventional sealing devices for reciprocating shafts, such as those in hydraulic shock absorbers, face instability in frictional force due to varying oil pressure, leading to early seal projection abrasion and inconsistent lubrication.
Innovation Solution
A sealing device with a main lip that contacts the shaft's entire periphery to prevent fluid leakage and a frictional lip that compensates for frictional force variations, allowing fluid circulation and maintaining lubrication, thereby stabilizing frictional force over time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the main lip is used for both sealing and providing frictional force, then the sealing function is achieved, but the frictional force becomes unstable due to oil pressure fluctuations
Solution Approach 1:
The sealing device is divided into two separate functional lips: the main lip dedicated to sealing the operating oil, and the frictional lip dedicated to providing stable frictional force. This segmentation allows each component to optimize its specific function without interference from the other, resolving the contradiction between sealing ability and frictional force stability.
Solution Approach 2:
Different parts of the sealing device are given different functional properties: the main lip has high sealing capability with proper interference fit, while the frictional lip has optimized surface characteristics for stable friction. This local differentiation of quality allows each region to perform its designated function effectively.
2Force
If the main lip provides frictional force, then the shaft can be controlled, but the oil film becomes thin and lubrication is insufficient due to pressure variations
Solution Approach 1:
The frictional lip is separated from the sealing function, allowing it to be specifically designed for maintaining stable frictional force and proper lubrication. The frictional lip's structure and material properties are optimized to maintain consistent oil film thickness regardless of operating conditions.
Solution Approach 2:
The frictional lip acts as an intermediary element between the main sealing lip and the reciprocating shaft, specifically tasked with maintaining stable frictional force and ensuring adequate lubrication through its interaction with the oil film.
3Reliability
If the seal projection contacts the shaft with proper interference, then sealing is effective, but the frictional coefficient varies and stable frictional force cannot be maintained
Solution Approach 1:
The sealing function and frictional force provision are separated into different lips. The main lip's seal projection maintains effective sealing with proper interference, while the frictional lip independently provides stable frictional coefficient through its specific surface characteristics and geometry.
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 ensures consistent frictional force over a long period without affecting the sealing ability, as the frictional lip balances pressure-induced frictional force fluctuations and maintains lubrication, preventing abrasion and ensuring reliable sealing.
Implementation Method 1
the whole periphery of the main lip is slidably and tightly contacted with an outer peripheral face of the shaft reciprocating in the axial direction
Implementation Method 2
a rubber-like elastic material
Implementation Method 3
the frictional lip compensates frictional force with respect to the shaft
Implementation Method 4
the sliding face is lubricated with the fluid to be sealed
Data Source
AI summary
To stabilize frictional force to the reciprocating shaft without affecting sealing ability, a sealing device for a reciprocating shaft comprises a main lip 11, a whole periphery of which slidably and tightly contacts with an outer peripheral surface of a shaft 2 reciprocating in the axial direction; and a frictional lip 13, which extends to the sealed space A side from the main lip 11 and slidably and tightly contacts with the outer peripheral surface of the shaft 2 in the state of permitting circulation of sealed fluid, whereby the frictional force of the frictional lip 13 is not varied by pressure of the sealed fluid, while frictional force of the main lip 11 to the shaft 2 is varied by the pressure, the sliding surface is lubricated with the sealed fluid, and reduction of the frictional force by abrasion can be controlled.