Lip Seal Pumping Areas Prevent Leakage and Reduce Wear
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Solution Overview
Problem
Existing shaft seal devices with lip-type seals face issues of leakage when at rest and wear over time, due to the design of the sealing edge and groove structures, which fail to maintain low friction and seal integrity during rotation.
Innovation Solution
A shaft seal device featuring a lip-type seal with discontinuously formed pumping areas on the rotating member's outer surface, including suction and discharge portions with periodic linear indentation structures, where the lip seal extends towards the atmosphere side, covering part of the pumping areas to prevent leakage and facilitate fluid lubrication, and the indentations are formed using a femtosecond laser for precise control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a coating is applied to the lip sealing face or the counterpart shaft surface or the roughness of the counterpart shaft surface is optimized, then friction is reduced initially, but low friction cannot be maintained due to wear over time
Solution Approach 1:
The invention changes the physical-chemical parameters of the sealing interface by applying a fluororesin coating to the lip sealing face, transforming it from a bare rubber surface to a low-friction coated surface. This coating maintains its properties over time, providing sustained low friction without the degradation experienced by uncoated surfaces or alternative coatings.
Solution Approach 2:
The invention uses a composite structure combining rubber material for the lip body with a fluororesin coating on the sealing face. This composite approach leverages the elasticity and sealing capability of rubber while adding the low-friction, wear-resistant properties of fluororesin, achieving both good seal properties and reduced friction over extended service life.
2Reliability
If an arrow-shaped groove is formed on the rotating shaft surface, then pumping action is achieved, but the sealing edge wears down quickly due to contact with high hardness material
Solution Approach 1:
The invention changes the surface parameters of the rotating shaft by forming micro-concave portions with specific dimensional parameters (depth of 0.1-10 μm, width of 1-100 μm). These precisely controlled micro-structures provide pumping action while having sufficiently small dimensions to minimize contact stress and wear on the sealing edge, extending service life.
Solution Approach 2:
The invention applies local micro-structures only in the pumping area rather than modifying the entire shaft surface. The micro-concave portions are localized to specific regions where pumping action is needed, concentrating the functional benefit while minimizing the total contact area and associated wear on the sealing lip.
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 prevents leakage when the device is at rest, forms a lubricant fluid film upon activation, reduces sliding torque, and maintains seal integrity by effectively drawing and returning sealed fluid through the pumping areas, thereby reducing wear and ensuring reliable sealing.
Implementation Method 1
a plurality of pumping areas for generating pumping action via relative rotational sliding of the lip seal and the rotating member
Implementation Method 2
a lip seal for creating a seal between a rotating member and a stationary member concentrically disposed inside and outside each other with respect to the radial direction
Data Source
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AI summary
{Problem} To provide a lip seal-type shaft seal device that exhibits no leakage when at rest; operates under fluid lubrication and prevents leakage when rotating, including during initial rotation; and enables a balance between seal integrity and lubrication. {Solution} A plurality of discontinuous pumping areas for generating pumping action via the relative rotational sliding of a lip seal and a rotating member is formed in the circumferential direction on the outer circumferential surface of the rotating member, the plurality of pumping areas being provided with suction portion of pumping areas operating in a direction in which a sealed fluid is drawn in and discharge portion of pumping areas operating in a direction in which the sealed fluid is expelled, a lip of the lip of the lip seal extending in an axial direction towards an atmosphere side, leaving part of the pumping areas uncovered on a sealed fluid side.