Mono-Tube Shock Absorber Sealing Unit for High-Pressure Cold Operation
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Solution Overview
Problem
Existing mono-tube shock absorber sealing units are complex, bulky, and inefficient at low temperatures, with limited axial dimensions and inability to handle high pressure peaks, and lack versatility in pressurization processes.
Innovation Solution
A sealing unit with a stem-guiding annular bushing, a first seal with an elastomeric sealing ring and metal reinforced zone, a reinforcing ring for thrust absorption, and a second seal for external environment protection, allowing separate assembly and pressurization during the assembly process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sealing unit with multiple separate parts is used (as in DE8201327U), then the sealing function is provided, but the device complexity and assembly difficulty increase
Solution Approach 1:
The patent combines multiple sealing functions into a single integrated sealing unit that includes both the oil seal and dust cover seal as one component. This merging eliminates the need for separate sealing parts, reducing assembly complexity while maintaining reliable sealing performance for both pressurized oil and external environment protection
2Reliability
If a fluorinated synthetic elastomeric material is used for the rubber ring, then the sealing performance is improved, but the minimum working temperature is limited to −15° C.
Solution Approach 1:
The patent changes the material parameter by using a different elastomeric material formulation that maintains sealing performance while extending the operational temperature range down to −40° C. This parameter change in material properties allows the sealing unit to function reliably in colder conditions without sacrificing sealing effectiveness
3Length of moving object
If the axial dimensions of the sealing unit are reduced, then the overall size and weight of the shock absorber are reduced, but the assembly complexity increases
Solution Approach 1:
The patent segments the sealing unit into modular components that can be assembled in a simplified sequence. The sealing unit includes distinct but integrated elements such as the elastomeric part with sealing lips, metal reinforcement zones, and pre-assembled components that fit together in a straightforward manner, reducing overall axial dimensions while maintaining ease of assembly
4Ease of manufacture
If the oil seal and dust cover seal are pre-assembled together, then the assembly is simplified, but the versatility for intermediate pressurization is lost
Solution Approach 1:
The patent applies preliminary action by pre-assembling certain components of the sealing unit (such as the elastomeric part with its reinforcement) while leaving the overall assembly open for intermediate pressurization operations. This partial pre-assembly simplifies the final assembly process while maintaining the flexibility to perform pressurization at an intermediate stage during production
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 compact, cost-effective, and versatile sealing unit that operates effectively across a wide temperature range, withstands high pressures, and simplifies the assembly and pressurization of mono-tube shock absorbers.
Implementation Method 1
a sealing ring (12) made of an elastomeric material and having an annular sealing lip (13) which projects, protruding radially and axially, inside the cup-shaped seat (9) so as to cooperate, during use, in a sliding manner, with the stem (2)
Implementation Method 2
a reinforced zone (14), for example made of metal, made using an elastically deformable material that is much more rigid than the elastomeric material of the sealing ring (12)
Implementation Method 3
the mono-tube shock absorber has a chamber into which gas under pressure is blown and the gas in turn pressurizes the hydraulic working fluid, normally oil, contained inside a second chamber
Implementation Method 4
As already mentioned, the oil reaches pressure peaks in the region of 100 bar
Data Source
AI summary
A sealing unit for a stem of a mono-tube shock absorber includes a first seal having a sealing ring providing an annular sealing lip that projects in a radially and axially inner direction to slidingly cooperate with the stem and ensure a sealing action with respect to pressurized working fluid inside the mono-tube shock absorber; a second seal with a sealing ring having an annular sealing lip, which projects protruding in a radially and axially external direction to slidingly cooperate, with the stem and ensure a sealing action with respect to the outside of the mono-tube shock absorber; a reinforcing ring snapped into an annular seat of the sealing ring. The reinforcing ring is arranged axially locked between the lip and a bottom wall of the second sealing lip; the first and second seals are two physically distinct and separate elements assembled separately inside a body of the shock absorber.