Floating Piston Membrane Structure for Shock Absorber Sealing
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Solution Overview
Problem
Existing floating pistons for single-tube gas shock absorbers face a challenge in balancing the rigidity required for sealing with the flexibility needed for effective deformation, leading to compromised performance in both sealing and flexibility functions.
Innovation Solution
A floating piston design featuring an L-shaped metallic support frame with a dynamic-lip seal and a central flexible membrane, where the dynamic-lip seal and flexible membrane are made of different elastomeric materials, providing enhanced flexibility and sealing capabilities. The flexible membrane is made of a more flexible and elastic material, optimized with specific physical characteristics such as Shore A hardness, modulus of elasticity, and elongation at break, allowing for greater deformation and pressure responsiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the radially outer seal is made rigid to ensure controlled axial sliding and sealing, then sealing performance is improved, but the flexibility and rapid deformation capability deteriorate
Solution Approach 1:
The patent applies different elastomeric materials with different properties to different parts of the floating piston: a more rigid material for the radially outer seal to ensure sealing and controlled sliding, and a more flexible material for the flexible membrane to enable rapid deformation. This local differentiation of material properties resolves the contradiction between sealing rigidity and flexibility.
Solution Approach 2:
The floating piston is constructed as a composite structure using two different elastomeric materials with distinct properties. The radially outer seal uses an elastomeric material optimized for sealing and friction control, while the flexible membrane uses a different elastomeric material optimized for flexibility and rapid deformation. This composite material approach allows both sealing performance and flexibility to be optimized simultaneously.
2Speed
If the flexible membrane is made highly flexible to enable rapid deformation and anticipate piston movement, then responsiveness is improved, but the static friction and sealing control deteriorate
Solution Approach 1:
The patent differentiates material properties locally within the floating piston structure. The flexible membrane is made of a highly flexible elastomeric material to enable rapid deformation and anticipate piston movement, while the radially outer seal is made of a different elastomeric material that provides appropriate static friction and sealing control. This local quality differentiation resolves the contradiction between responsiveness and sealing stability.
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
This design enhances the shock absorber's reactivity and comfort by maintaining pressure equilibrium and improving damping effects, ensuring effective absorption of road surface roughness without transmitting impulses to the vehicle and driver, while maintaining static friction and sealing integrity.
Implementation Method 1
The flexible membrane of the floating piston must be able to flex either toward the sliding chamber or, alternatively, toward the blind chamber depending on the variations in pressure between the chambers of the shock absorber, and must be likewise sufficiently flexible so as to be able to be deformed before the start of displacement of the floating piston.
Implementation Method 2
a dynamic-lip seal disposed radially external to the frame and arranged in sliding contact with the sleeve of the shock absorber so as to define a radial seal external to the frame
Data Source
AI summary
A floating piston for a single-tube shock absorber is arranged slidably inside a tubular sleeve of the shock absorber so as to separate a sliding chamber and a blind chamber. The piston includes an annular support frame formed of a metallic material and having a central hole, a dynamic-lip seal which is radially external to the frame and arranged in sliding contact with the sleeve of the shock absorber so as to define a radial seal external to the frame, and a central flexible membrane arranged to hermetically close the central hole and deformable so as to anticipate the complete movement of the floating piston. The dynamic-lip seal and the flexible membrane are made of two elastomeric materials which are different from each other, the elastomeric material of the membrane being more flexible and elastic than the elastomeric material of the dynamic-lip seal.