Magnetorheological Bushing Structure for Variable Stiffness Damping
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Solution Overview
Problem
Existing liquid filled bushings have constant vibration absorbing/damping characteristics in both axial and orthogonal directions, which cannot be varied during use, limiting their adaptability and functionality.
Innovation Solution
A variable stiffness bushing design featuring an inner and outer tubular member, elastic member, communication passages, and a magnetic fluid, where the volume difference between liquid chambers is controlled by axial displacement and electric current to the coil, adjusting the magnetic field and flow resistance, thus varying the stiffness and damping characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a liquid filled bushing uses constant viscosity liquid and fixed orifice/gap dimensions, then the manufacturing is simple, but the stiffness cannot be varied during use
Solution Approach 1:
The patent changes the viscosity parameter of the filling liquid dynamically by using magnetorheological fluid whose viscosity can be altered through magnetic field application. The coil generates a magnetic field that modifies the fluid's rheological properties, enabling stiffness variation without changing the physical structure of the bushing.
Solution Approach 2:
The patent replaces the traditional mechanical adjustment mechanism (such as adjustable orifices or movable partitions) with an electromagnetic field-based control system. The coil and magnetorheological fluid create a non-mechanical means to control fluid flow resistance and thus stiffness, eliminating complex mechanical adjustment components.
2Adaptability or versatility
If the bushing uses a simple liquid filled structure, then the device complexity is low, but the vibration damping characteristics cannot be dynamically adjusted
Solution Approach 1:
The patent utilizes the magnetorheological effect to change the viscosity parameter of the filling liquid in response to magnetic field strength. By adjusting the current through the coil, the viscosity of the magnetorheological fluid changes, thereby dynamically adjusting the damping characteristics without requiring complex mechanical reconfiguration.
Solution Approach 2:
The patent substitutes electromagnetic field control for mechanical damping adjustment mechanisms. The coil generates a magnetic field that directly influences the rheological properties of the magnetorheological fluid, providing energy-efficient damping control without moving parts or complex mechanical systems.
3Adaptability or versatility
If the bushing uses fixed orifice and gap dimensions, then the manufacturing precision requirements are low, but the stiffness is constant and cannot be varied
Solution Approach 1:
The patent changes the effective flow resistance parameter by utilizing magnetorheological fluid whose viscosity can be dynamically adjusted through magnetic field application. This allows stiffness control without requiring precise manufacturing of orifice and gap dimensions, as the rheological properties of the fluid provide the primary control mechanism.
Solution Approach 2:
The patent replaces precision mechanical flow control elements (such as precisely dimensioned orifices and gaps) with an electromagnetic field-based viscosity control system. The magnetorheological fluid's field-responsive viscosity provides a more flexible and less manufacturing-sensitive method for controlling stiffness and damping characteristics.
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
Enables the bushing to dynamically adjust its axial and radial stiffness and damping characteristics in response to displacement and current supply, providing a simple configuration for adaptable vibration management.
Implementation Method 1
a magnetic fluid (37) filling the at least one pair of liquid chambers and the at least one communication passage... by supplying electric current to the coil to generate a magnetic field around the coil such that magnetic field lines pass through the circumferential passage of each communication passage, the flow resistance of the magnetic fluid in the communication passage can be varied
Implementation Method 2
an elastic member (8) connecting the inner tubular member and the outer tubular member
Implementation Method 3
by supplying electric current to the coil to generate a magnetic field around the coil such that magnetic field lines pass through the circumferential passage of each communication passage, the flow resistance of the magnetic fluid in the communication passage can be varied
Data Source
AI summary
A variable stiffness bushing includes: inner and outer tubular members; an elastic member connecting these tubular members. At least one pair of circumferentially separated liquid chambers is defined in the elastic member such that first axial ends and second axial ends of the liquid chambers are defined by first and second end walls of the elastic member, respectively. The liquid chambers of each pair communicate with each other by a corresponding communication passage including a circumferential passage provided in one of the tubular members, which includes a coil wound coaxially therewith and a yoke provided with at least one gap constituting the circumferential passage. A magnetic fluid fills the liquid chambers and the communication passage(s). The first and second end walls are configured such that when the tubular members are axially displaced relative to each other, a difference is created between volumes of the liquid chambers of each pair.