Magneto rheological damper
Encyclopedia
A magnetorheological damper or magnetorheological shock absorber is a damper
filled with magnetorheological fluid
, which is controlled by a magnetic field
, usually using an electromagnet
. This allows the damping characteristics of the shock absorber to be continuously controlled by varying the power of the electromagnet
. This type of shock absorber has several applications, most notably in semi-active
vehicle suspensions which may adapt to road conditions, as they are monitored through sensors in the vehicle, and in prosthetic limbs.
, Audi TT
and R8, Buick Lucerne
, Cadillac CTS-V, DTS
, XLR
, SRX
, STS
, Chevrolet Corvette
, Ferrari 599GTB, 458 Italia and Holden HSV Commodore. These systems were produced by the Delphi Corporation and now by BWI Group
under the proprietary name MagneRide.
MillenWorks
has also included them in several military vehicles including the MillenWorks Light Utility Vehicle
, and in retrofits to the US Army Stryker
and HMMWV for testing by TARDEC.
of the magnetorheological fluid with electric current
. When the fluid is brought into a magnetic field
, the metal particles of the fluid are aligned according to the field lines
. This makes the fluid stiff. When this occurs at the right instant, the properties of the damper change, which helps in attenuating an undesired shock or vibration.
Shock absorber
A shock absorber is a mechanical device designed to smooth out or damp shock impulse, and dissipate kinetic energy. It is a type of dashpot.-Nomenclature:...
filled with magnetorheological fluid
Magnetorheological fluid
A magnetorheological fluid is a type of smart fluid in a carrier fluid, usually a type of oil. When subjected to a magnetic field, the fluid greatly increases its apparent viscosity, to the point of becoming a viscoelastic solid. Importantly, the yield stress of the fluid when in its active state...
, which is controlled by a magnetic field
Magnetic field
A magnetic field is a mathematical description of the magnetic influence of electric currents and magnetic materials. The magnetic field at any given point is specified by both a direction and a magnitude ; as such it is a vector field.Technically, a magnetic field is a pseudo vector;...
, usually using an electromagnet
Electromagnet
An electromagnet is a type of magnet in which the magnetic field is produced by the flow of electric current. The magnetic field disappears when the current is turned off...
. This allows the damping characteristics of the shock absorber to be continuously controlled by varying the power of the electromagnet
Electromagnet
An electromagnet is a type of magnet in which the magnetic field is produced by the flow of electric current. The magnetic field disappears when the current is turned off...
. This type of shock absorber has several applications, most notably in semi-active
Active suspension
Active or adaptive suspension is an automotive technology that controls the vertical movement of the wheels with an onboard system rather than the movement being determined entirely by the road surface...
vehicle suspensions which may adapt to road conditions, as they are monitored through sensors in the vehicle, and in prosthetic limbs.
Ground-based
These types of systems are available from OEMs for several vehicles, including the Acura MDXAcura MDX
The Acura MDX, or Honda MDX as known in Japan and Australia , is a mid-size luxury crossover SUV produced by the Japanese automaker Acura since the 2001 model year. The MDX was the first crossover SUV to have third-row seating. It is related to the Honda Pilot. The alphanumeric moniker stands for...
, Audi TT
Audi TT
The Audi TT is a two-door sports car manufactured by the German automaker and Volkswagen Group subsidiary Audi since 1998.The Audi TT has been produced in two generations. Both generations have been available in two car body styles; as a 2+2 Coupé, or two-seater Roadster...
and R8, Buick Lucerne
Buick Lucerne
The Buick Lucerne is a full-size car sold by the Buick division of General Motors. Introduced at the 2005 Chicago Auto Show, the Lucerne replaced both the Park Avenue and the LeSabre for the 2006 model year, and was sold through the 2011 model year...
, Cadillac CTS-V, DTS
Cadillac DTS
The Cadillac DTS is a full-size luxury sedan produced by General Motors, an American automobile company. The DTS replaced the Cadillac DeVille as General Motors' largest luxury car for the 2006 model year...
, XLR
Cadillac XLR
The XLR was a retractable hardtop convertible marketed by the Cadillac division of General Motors, assembled in Bowling Green, Kentucky. Intended to be Cadillac's flagship sports car, the XLR was based on the Chevrolet Corvette's Y platform...
, SRX
Cadillac SRX
Engine options include the High-Feature V6 and the 4.6 L Northstar V8. It is based on the GM Sigma platform and comes with a five or six-speed automatic transmission; rear-wheel drive and four-wheel drive are available....
, STS
Cadillac STS
The STS is a mid-size luxury sports sedan / executive car manufactured and sold by Cadillac. It is equipped with a six-speed automatic transmission with performance algorithm shifting and driver shift control.- Origins :...
, Chevrolet Corvette
Chevrolet Corvette
The Chevrolet Corvette is a sports car by the Chevrolet division of General Motors that has been produced in six generations. The first model, a convertible, was designed by Harley Earl and introduced at the GM Motorama in 1953 as a concept show car. Myron Scott is credited for naming the car after...
, Ferrari 599GTB, 458 Italia and Holden HSV Commodore. These systems were produced by the Delphi Corporation and now by BWI Group
Beijing West Industries
BWI Group, also known as BeijingWest Industries, is a supplier for brake and suspension systems. The company acquired the Chassis Division of Delphi on November 1, 2009. The brake and suspension business lines were purchased for approximately $100 million. The company supplies to automotive,...
under the proprietary name MagneRide.
MillenWorks
MillenWorks
MillenWorks, known as Rod Millen Motorsports until 2005, is an automotive technology company started by Rod Millen in 1980. The company began by preparing Millen's rally cars, and evolved into designing and building them...
has also included them in several military vehicles including the MillenWorks Light Utility Vehicle
MillenWorks Light Utility Vehicle
The MillenWorks Light Utility Vehicle is a prototype testbed for automotive technologies. It was designed and built by MillenWorks under contract to the Tank Automotive Research, Development and Engineering Center. Textron Marine and Land Systems will use the platform for further development of...
, and in retrofits to the US Army Stryker
Stryker
The IAV Stryker is a family of eight-wheeled, 4-wheel-drive , armored fighting vehicles derived from the Canadian LAV III and produced by General Dynamics Land Systems, in use by the United States Army. The vehicle is named for two American servicemen who posthumously received the Medal of Honor:...
and HMMWV for testing by TARDEC.
Aviation
MRF squeeze film dampers are being designed for use in the rotary wing industry to isolate vibrations from the aircraft structure and crew.Control
A magnetorheological damper is controlled by algorithms specifically designed for the purpose. There are plenty of alternatives, such as skyhook or groundhook algorithms. The idea of the algorithms is to control the viscosityViscosity
Viscosity is a measure of the resistance of a fluid which is being deformed by either shear or tensile stress. In everyday terms , viscosity is "thickness" or "internal friction". Thus, water is "thin", having a lower viscosity, while honey is "thick", having a higher viscosity...
of the magnetorheological fluid with electric current
Electric current
Electric current is a flow of electric charge through a medium.This charge is typically carried by moving electrons in a conductor such as wire...
. When the fluid is brought into a magnetic field
Magnetic field
A magnetic field is a mathematical description of the magnetic influence of electric currents and magnetic materials. The magnetic field at any given point is specified by both a direction and a magnitude ; as such it is a vector field.Technically, a magnetic field is a pseudo vector;...
, the metal particles of the fluid are aligned according to the field lines
Field line
A field line is a locus that is defined by a vector field and a starting location within the field. Field lines are useful for visualizing vector fields, which are otherwise hard to depict...
. This makes the fluid stiff. When this occurs at the right instant, the properties of the damper change, which helps in attenuating an undesired shock or vibration.
See also
- Smart fluidSmart fluidA smart fluid is a fluid whose properties can be changed by applying an electric field or a magnetic field.The most developed smart fluids today are fluids whose viscosity increases when a magnetic field is applied...
- Magnetorheological fluidMagnetorheological fluidA magnetorheological fluid is a type of smart fluid in a carrier fluid, usually a type of oil. When subjected to a magnetic field, the fluid greatly increases its apparent viscosity, to the point of becoming a viscoelastic solid. Importantly, the yield stress of the fluid when in its active state...
- FerrofluidFerrofluidA ferrofluid is a liquid which becomes strongly magnetized in the presence of a magnetic field.Ferrofluids are colloidal liquids made of nanoscale ferromagnetic, or ferrimagnetic, particles suspended in a carrier fluid . Each tiny particle is thoroughly coated with a surfactant to inhibit clumping...
- Electrorheological fluidElectrorheological fluidElectrorheological fluids are suspensions of extremely fine non-conducting particles in an electrically insulating fluid. The apparent viscosity of these fluids changes reversibly by an order of up to 100,000 in response to an electric field...
- RheologyRheologyRheology is the study of the flow of matter, primarily in the liquid state, but also as 'soft solids' or solids under conditions in which they respond with plastic flow rather than deforming elastically in response to an applied force....
- RheometryRheometryRheometry generically refers to the experimental techniques used to determine the rheological properties of materials, that is the quantitative and qualitative relationships between deformations and stresses and their derivatives.The choice of the adequate experimental technique depends on the...