Shock Absorber Resilient Device Rebound Chamber Cavitation
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Solution Overview
Problem
In shock absorbers, the pressure in the return chamber often falls below a minimum level during rapid damping movements, leading to cavitation and a loss of damping forces, as existing solutions struggle to maintain a consistent pressure ratio between the compression and return chambers.
Innovation Solution
A resilient device is placed directly in the return chamber, acting as an accumulator to store energy and maintain a minimum pressure, comprising elastic members or pressurizing media that build up pressure and compensate for pressure drops during compression strokes, ensuring the pressure in the return chamber remains above a predetermined level.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a high pressure is applied to the return chamber to prevent cavitation, then the damping forces are maintained, but the rigidity becomes excessively high and the shock absorber becomes too stiff
Solution Approach 1:
The resilient device dynamically adjusts the return chamber pressure based on the compression stroke phase. During early compression, it provides high pressure to prevent cavitation. As compression progresses and the piston approaches the rebounded state, the resilient device gradually reduces pressure, allowing the return chamber pressure to decrease and reducing overall rigidity. This dynamic pressure adjustment maintains damping forces while avoiding excessive stiffness.
Solution Approach 2:
The resilient device is pre-loaded to provide immediate pressure support in the return chamber at the beginning of the compression stroke. This preliminary pressure buildup prevents cavitation before it can occur, ensuring damping forces are maintained from the start of the compression cycle without requiring continuously high pressure that would make the shock absorber excessively stiff throughout the entire cycle.
2Reliability
If the pressure in the return chamber is kept high to avoid cavitation, then damping forces are preserved, but energy is wasted and the shock absorber efficiency decreases
Solution Approach 1:
The resilient device recovers and stores energy that would otherwise be wasted. As the compression stroke progresses and the piston rod displaces damping medium, the resilient device compresses and stores the energy from the pressure differential. This stored energy is then released during the rebound stroke, reducing the need for continuously high return chamber pressure and improving overall energy efficiency while still preventing cavitation during critical phases.
Solution Approach 2:
The resilient device creates a dynamic pressure system where the return chamber pressure varies throughout the compression stroke rather than remaining constantly high. This dynamic behavior allows the system to maintain minimum pressure for cavitation prevention while reducing average pressure levels, thereby decreasing energy waste and improving shock absorber efficiency.
3Reliability
If a resilient device is added to the return chamber to maintain pressure, then cavitation is prevented, but the device complexity increases
Solution Approach 1:
The resilient device is integrated into the existing shock absorber structure, combining multiple functions into a single component. It serves as both a pressure maintenance device and an energy storage element, while also accommodating the piston rod displacement and temperature-induced volume changes. This merging approach prevents cavitation without adding separate complex subsystems, as the resilient device performs multiple critical functions simultaneously within the return chamber.
Solution Approach 2:
The resilient device is designed as a multi-functional component that simultaneously: (1) maintains minimum return chamber pressure to prevent cavitation, (2) stores energy from compression for use during rebound, (3) accommodates piston rod displacement volume changes, and (4) compensates for thermal expansion/contraction of the damping medium. This universal design achieves pressure consistency without proportionally increasing device complexity, as one component handles multiple critical functions.
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 solution effectively prevents cavitation by maintaining a resilient function in the shock absorber, ensuring the pressure in the return chamber remains above the minimum level, thereby enhancing the damping characteristics and preventing losses in damping forces.
Implementation Method 1
energy is stored in the shock absorber so that a pressure is built up in a resilient device, preferably in the form of an accumulator, that is disposed in the return chamber
Implementation Method 2
comprising elastic members or pressurizing media that build up pressure and compensate for pressure drops during compression strokes
Implementation Method 3
A resilient device is placed directly in the return chamber, acting as an accumulator to store energy and maintain a minimum pressure
Data Source
AI summary
A shock absorber comprises a damping cylinder pressurized by a system pressure and divided by a piston into a compression chamber and a return chamber. A resilient device is disposed in the return chamber. The resilient device comprises a pressurizing member or pressurizing medium disposed in an inner volume that is delimited from the return chamber. The resilient device acts upon the damping medium volume in the return chamber such that the pressure initially during a compression stroke does not fall below a predetermined minimum pressure. As long as the pressure in the return chamber is less than the pressure created by the resilient device, the device is able to absorb energy. When the pressure in the return chamber is greater than the pressure created by the resilient device, the device becomes inflexible. The resilient device compensates for pressure reduction in the return chamber that occurs under rapid damping movements and that can cause cavitation during a compression stroke.