Rotary Damper Assembly With Permanent Magnet Backup Damping
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Solution Overview
Problem
Rotary dampers using magnetorheological fluid face issues with increased temperature causing fluid expansion, leading to cavitation and reduced operational life, and lack a reliable backup mode during power outages or system failures.
Innovation Solution
Incorporating a permanent magnetic insert and a gas cup within the rotary damper assembly to accommodate fluid expansion and provide continuous magnetic flux, enabling increased damping levels and a backup mode of operation in case of power loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If magnetorheological fluid is used in the rotary damper, then damping performance is improved, but fluid expansion due to temperature increase causes cavitation and reduces operational life
Solution Approach 1:
The patent introduces a gas bubble into the magnetorheological fluid before operation to serve as a cushioning element. This pre-introduced gas bubble accommodates the thermal expansion of the magnetorheological fluid during operation, preventing cavitation that would otherwise occur due to volume expansion. The gas bubble acts as a buffer that absorbs the expansion stress, thereby protecting the damper system and extending its operational life.
2Reliability
If electrorheological or magnetorheological fluid is subjected to an electric or magnetic field, then viscosity increases and damping performance improves, but the fluid requires continuous power supply which is vulnerable to power outages
Solution Approach 1:
The patent changes the operational parameter of the damper by introducing a passive mechanical element (gas bubble) that does not require external power supply. The gas bubble's physical presence and compressibility provide a backup damping mechanism that operates independently of electrical or magnetic fields, ensuring continuous operation during power outages or system failures.
3Ease of operation
If coils are used to generate magnetic field for controlling magnetorheological fluid viscosity, then damping control is achieved, but device complexity increases
Solution Approach 1:
The patent extracts the essential damping function from the complex electromagnetic control system and implements it through a simple passive gas bubble mechanism. By removing the requirement for coils and magnetic field generators, the patent achieves damping control through the physical properties of the gas bubble and magnetorheological fluid interaction, significantly reducing device complexity while maintaining operational effectiveness.
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 effectively reduces cavitation by accommodating fluid expansion and ensures continuous operation during power outages, enhancing the rotary damper's performance and lifespan.
Implementation Method 1
the magnetorheological fluid whose properties are changed by changing intensity of an electric or magnetic field. When the electrorheological or magnetorheological fluid is subject to an electric or magnetic field, particles contained in the fluid are connected to form chains resulting in that the fluid is changed from a liquid phase to a gel phase, i.e. an increase in the viscosity of the fluid
Implementation Method 2
As the magnetorheological fluid moves in the rotary damper assembly, the temperature of the magnetorheological fluid increases which can cause the volume of magnetorheological fluid to expand. Accordingly, due to the expansion of the magnetorheolgocial fluid, cavitation occurs
Implementation Method 3
By combining the flux density generated by the at least one coil and the flux density of the insert during operation, the rotary damper assembly is able to increase the damping level of the rotary damper assembly. Additionally, by including the insert, the rotary damper assembly is able to provide a continuous magnetic flux
Data Source
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AI summary
A rotary damper assembly (20) comprises a housing (22) extending along a center axis. The housing includes an upper portion (24) and a lower portion (26). The lower portion defines a fluid chamber (32,34). The upper portion defines a compartment in communication with the fluid chamber. The magnetic field generator (56) includes a magnetic core located between the upper portion and the lower portion. The magnetic core extends along the center axis between the upper portion and the lower portion. At least one coil (66) extends about the magnetic core. A shaft (96) extends along the center axis through the upper portion and the magnetic core and into the fluid chamber to facilitate magnetorheological fluid flow from the compartment to the fluid chamber. The magnetic field generator includes an insert (72), containing a permanent magnetic material, for generating a permanent magnetic field to change viscosity of the magnetorheological fluid.