Pressure Accumulator Bellows Liquid Support Pulsation Damping
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Solution Overview
Problem
Existing pressure accumulators face challenges in maintaining effective damping of hydraulic fluid pulsations within a small installation space while protecting the bellows from overloading and ensuring reliable operation over long cycle times, especially under varying load conditions and potential overpressure or lack of prefill pressure.
Innovation Solution
The pressure accumulator incorporates a gas working chamber filled with a liquid, allowing the fluid to support the bellows during expansion and contraction, reducing the gas space volume and providing damping support, with a combination of nitrogen gas and ethylene alcohol as the working fluid, which increases the service life and operating reliability by distributing pressure evenly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the stroke length of the end plate is increased to provide sufficient gas space volume, then the gas space volume is improved, but the bellows becomes more heavily loaded and requires thicker or multilayer construction
Solution Approach 1:
A liquid intermediary substance is introduced into the gas space to support the bellows from the inside during expansion and contraction. This liquid mediator distributes the mechanical loads evenly across the bellows surface, reducing peak stresses and preventing overloading while maintaining sufficient gas space volume for effective pulsation damping.
Solution Approach 2:
The patent changes the physical state parameters within the bellows by introducing a liquid phase alongside the gas phase. This creates a two-phase environment where the liquid provides hydraulic support to the bellows folds, altering the mechanical stress distribution and enabling the bellows to operate within safe stress limits while maintaining adequate volume.
2Strength
If thicker or multilayer metal bellows are used to protect against overloading, then the bellows strength is improved, but the spring stiffness is greatly increased leading to poor response behavior
Solution Approach 1:
The liquid intermediary substance provides internal hydraulic support to the bellows structure, distributing loads evenly across all folds during operation. This prevents localized overloading and stress concentrations, allowing the use of thinner, more compliant bellows construction that maintains high response speed while still protecting against overloading through the liquid's pressure-distributing effect.
3Volume of stationary object
If the gas space volume is reduced to improve damping in small installation space, then the installation space requirement is improved, but the damping capability for rapid pulsations may be compromised
Solution Approach 1:
The patent changes the physical composition of the gas space by introducing a liquid phase, creating a two-phase fluid system. This parameter change enables the system to maintain effective pulsation damping capability in a reduced volume, as the liquid-gas interaction provides enhanced damping effects compared to gas alone, allowing compact installation while preserving reliability for rapid pulsations.
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 configuration enhances damping capabilities and operating reliability for rapid pulsations and high-speed pressure surges, reduces the risk of bellows failure, and eliminates the need for additional seals, ensuring continuous operation without wear.
Implementation Method 1
The gas working chamber (26) is filled with a liquid (47) in which the bellows-shaped separating element (30) is buoyed up in a buoyant state, such that the bellows-shaped separating element (30) can be supported with its individual folds (38) on the liquid (47) during expansion and contraction
Implementation Method 2
A bellows-shaped separating element (30) separates two working chambers from each other, especially a gas space from a fluid space within the pressure accumulator housing (10), in a fluid-tight, especially gastight, manner
Implementation Method 3
Up to a definable degree the working gas allows compression. In this way, damping and smoothing of the pulsations of the pertinent fluid medium occur on the fluid side of the pressure accumulator
Implementation Method 4
A piston part (28) is configured to be able to move axially along the longitudinal axis (22) of the pressure accumulator
Data Source
AI summary
A pressure accumulator, especially a pulsation damper, includes an accumulator housing (10) and a piston element (28) disposed in it. A bellows-type separative element (30) is supported on the piston part (28) with its one end (32) and with its other end (34) on the accumulator housing (10). The separative element (30) separates two working chambers (26, 40) within the accumulator housing (10) from each other, especially a gas chamber (26) from a fluid chamber (40), in a fluid-tight, especially gas-tight manner. To one working chamber (26), in addition to a defined volumetric proportion of a working gas, is filled with a fluid. In this manner, the working gas allows for a compression to a certain degree and for a dampening and smoothening of the pulsations of the fluid medium migrating to and occurring on the fluid side of the accumulator.