Shock Absorber Sealing with Passive Pressure Valve
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing shock absorbers in the aeronautical field require frequent maintenance due to high pressure exposure affecting dynamic seals, leading to increased operational costs and limitations in automatic sealing transitions.
Innovation Solution
A shock absorber design featuring two dynamic seals with passive valve means that automatically switch operation when pressure thresholds are exceeded, ensuring the second seal is preserved and activated without manual intervention, thereby extending its service life and reducing maintenance needs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If manual valve means are provided to switch between first and second dynamic seals, then the second dynamic seal can be activated when the first seal wears out, but the system requires regular manual checking and the valve means add dead mass and complexity
Solution Approach 1:
The valve means are designed to operate automatically based on pressure differential without requiring manual intervention. The system self-regulates by using the pressure difference between the annular chamber and inter-seal space to open or close the valve, thereby activating the appropriate dynamic seal based on operational conditions.
Solution Approach 2:
The manual mechanical valve operation is replaced with a passive pressure-responsive mechanism. Instead of requiring manual actuation, the valve automatically responds to pressure conditions, eliminating the need for regular manual checking and reducing operational complexity.
2Reliability
If the second dynamic seal is kept ready in the inter-seal space, then it can take over when the first seal fails, but the second seal is exposed to high pressures which accelerates its wear and reduces its service life
Solution Approach 1:
The second dynamic seal is pre-positioned and lubricated in the inter-seal space during normal operation, preparing it for future use without exposing it to high pressures. This preliminary preparation allows the seal to be ready when needed while preserving its service life.
Solution Approach 2:
The valve means act as an intermediary that controls pressure exposure to the second dynamic seal. By opening or closing the duct between the annular chamber and inter-seal space, the valve mediates pressure transmission, protecting the second seal from high pressures during normal operation while allowing it to function when the first seal fails.
3Duration of action of stationary object
If the valve means are made passive and automatically close when pressure exceeds a threshold, then the second dynamic seal is protected from high pressures, but the valve must be precisely calibrated to distinguish between normal and abnormal pressure conditions
Solution Approach 1:
The valve means automatically regulate pressure exposure based on inherent pressure differential without requiring external control or complex calibration. The system uses its own operating parameters (pressure differences) to control the valve state, making it self-regulating and reducing manufacturing precision requirements.
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 enables automatic and maintenance-reduced operation of the second dynamic seal, enhancing operational reliability and reducing monitoring requirements by ensuring the second seal remains functional and protected from high pressures, thus extending its service life and reducing maintenance needs.
Implementation Method 1
the valve means are arranged to normally place the annular chamber in communication with the inter-seal space and automatically isolate the inter-seal space from the annular chamber when the pressure in the annular chamber is greater than a determined threshold pressure
Implementation Method 2
the second dynamic seal is wetted by the stagnant fluid in the inter-seal space and coming from the annular chamber
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The present invention relates to a shock absorber comprising a cylinder (2) in which a rod (4) is mounted such as to slide inside the cylinder by means of two bearings (5, 6) arranged between the cylinder (2) and the rod (4) such that said bearings (5, 6), the cylinder (2) and the rod (4) define therebetween an annular chamber (7), at least one of the bearings (5, 6) supporting a sealing means (8) with at least two dynamic seals (9, 10) in contact with that of the rod (4) or of the cylinder (2) sliding relative to said bearing, the two dynamic seals defining an inter-seal space (11) therebetween, a valve means (12) installed in a duct of the bearing in order to selectively connect the annular chamber (7) and the inter-seal space (11). The valve means (12) is passive and arranged such as to establish a normal connection between the annular chamber (7) and the dynamic inter-seal space (11) and automatically to isolate the inter-seal space from the annular chamber if the pressure in the annular chamber (7) is higher than a predetermined threshold pressure.