Abstract: Controlled oscillating damper, comprising: a housing (12) provided with a cavity (14), an oscillating element (18) moving sealingly within the cavity (14), in which the housing (12) and the oscillating element (18) have respective walls defining at least one chamber (44) filled with magneto-rheological or electro-rheological damping fluid, and at least one electrically controlled excitation device (46) equipped with at least one fluid passage (52) which a fluid flow gets through during the motion of the oscillating element (18). The excitation device (46) is stationary with respect to the housing (12) and is arranged so as to divide the damping chamber (44) into two sections of variable volume (44a, 44b) communicating one with the other through the passage (52).

Abstract: A drag damper for use on a rotary-wing aircraft rotor comprises a body defining two variable volume chambers linked by a piston. The chambers filled with fluid in the damper are connected by a restrictor port in the piston or between the latter and the body, and via a channel of great length and small cross-section compared with the cross-section of the body, in which elastic means bear against and load the piston-rod assembly towards a neutral position, the anti-resonance frequency of the damper being matched substantially to the nominal rotation frequency of the rotor, and the restrictor port providing effective damping at the natural frequency (??) of the blades in drag, differing by construction from the rotor frequency (?).

Abstract: A shock and vibration isolation system for mounting equipment to a base wall uses a semi-active damper in parallel with a spring arrangement to provide optimum isolation with respect to both shock and vibration. The system comprises a load plate configured for attachment of the equipment thereto and a base plate configured for attachment to the base wall. The base plate is substantially parallel to the load plate with a spring arrangement disposed intermediate the load plate and the base plate. The spring arrangement engages the load plate and the base plate to bias the load plate and the base plate in a separated relationship. The system also comprises a damping arrangement disposed intermediate the load plate and the base plate. The damping arrangement is adapted for providing a selectively variable reaction force to the load plate and the base plate responsive to a relative displacement of the load plate with respect to the base plate.

Abstract: A variable spring member includes a containment housing defining an inner chamber with alternating layers of compressible medium and electro-reactive medium. Adjacent each layer of electro-reactive medium is a coil assembly controlled by a controller. A sealed plate disposed between alternating layers of compressible medium and electro-reactive medium disperses a load exerted on the variable spring member assembly and prevents intermixing of compressible medium with the electro-reactive medium. Actuation of the coil assembly changes physical characteristics and compressibility of the layer of electro-reactive medium to vary spring rate and stiffness.

Abstract: A magnetorheological fluid brake utilizing a positive displacement fluid pump adapted to pump a magnetorheological fluid through a viscosity regulator. The viscosity regulator is adapted to controllably vary the viscosity of the magnetorheological fluid, altering the pumping restriction against the fluid pump, resulting in variable resistance to pump shaft rotation relative to the pump housing. An electronic steering system for a work vehicle utilizing the illustrated magnetorheological brake as a resistance device to provide tactile feedback as a function of steering shaft rotational position.

Abstract: The invention disclosed is a magnetorheological fluid device offering vibration isolation and broad modulation range damping in a high load carrying and compact form. A cylindrically shaped flexure structure has a bottom cap attached to one end and a top cap attached to the other end. A piston comprising a toroidal displacement body, a central shaft, and intermediate connecting plate, attaches to the top cap. A fluid chamber surrounding and generally conforming to the shape of the toroidal displacement body, is attached to the bottom cap. Two bellows attaching between the piston connecting plate and top and bottom portions of the fluid chamber complete an enclosed volume around the toroidal displacement body and allow frictionless motion of the toroidal displacement body relative to the fluid chamber.

Abstract: A method and device for suspending a wheel axle from a vehicle includes a unitary flexible member coupled between the vehicle and the wheel axle and to an electronic control unit. The flexible member is formed of a material that changes shape in the presence of electrical signals having a varying signal strength. The electronic control unit, upon receiving various suspension related inputs, transmits the electrical signals having the varying signal strength to the unitary flexible member to change the shape thereof in order to vary the stiffness of the flexible member and thus control the suspension of the vehicle.

Abstract: A watercraft seat suspension includes a damper mounted between a watercraft seat and the watercraft hull. The damper includes an electrically actuated mechanism controlling fluid flow from a first chamber to a second chamber within the damper. A sensor senses motion of the seat relative to the hull. A control unit interpolates the sensor signal and develops an actuating signal controlling the electrically actuated mechanism. In one arrangement, the electrically actuated mechanism is a solenoid actuated by the actuating signal to effect one of two different damping modes. In another arrangement, the electrically actuated mechanism includes a conductor coil and flux ring generating a magnetic field proportional to the actuating signal to vary the viscosity of magneto-rheological fluid in the damper.

Abstract: A variable resistance cell and method provides a variable resistance response to a load factor, such as a load, a load rate, a strain, a strain rate, a pressure, or a deflection. A variable viscosity fluid is displacable between first and second chambers of an enclosure though an orifice in response to the load factor. The variable viscosity fluid has a viscosity that is variable corresponding to the load factor to vary an ability of the variable viscosity fluid to flow through the orifice. The variable viscosity fluid can be a shear stiffening material that increases in viscosity with an increase in a load factor applied to the shear stiffening material, a magneto rheologic fluid responsive to a magnetic field, or an electro rheologic fluid responsive to an electric field. The enclosure can be compressible between first and second positions.

Abstract: A method controls the damper current of a damper of a motor vehicle. The damper is adjustable by an electrical current and the permissible change of the current per time interval is delimited by a limit.

Abstract: An apparatus (10) for helping to protect an occupant (28) of a vehicle (12) includes a knee bolster (20). An energy absorbing device (80) is interposed between the knee bolster (20) and the vehicle (12). The device (80) includes a field responsive fluid (84) having a viscosity that varies in response to an energy field acting on the fluid. The device (80) also includes at least one passage (134) through which the fluid (84) flows upon movement of the knee bolster (20) relative to the vehicle (12). The device (80) further includes means (150) for varying the viscosity of the fluid (84) to vary the flow rate through the at least one passage (134) and thereby vary the resistance to movement of the knee bolster (20) relative to the vehicle (12).

Abstract: Under electric control of a motor by a CPU, before the rotation angle of a rotary knob reaches a predetermined angle (20°, 40°, 60°, . . . 360°), a torque in the same direction as a rotational direction is provided from the motor to the rotary knob, and the torque is decreased from a maximum value to zero. When the rotation angle of the rotary knob reaches a predetermined angle, a torque product is provided to the rotary knob depending upon an angular velocity of the rotary knob. After the rotation angle of the rotary knob exceeds a predetermined rotation angle, a torque in the reverse direction to a rotational direction is provided to the rotary knob, and the torque is increased from zero to a maximum value.

Abstract: According to the present invention, electrorheological fluid is deaerated after it is sealed in a closed device which is operated by the electrorheological fluid. Thus, it is possible to control the operation of the closed device in accordance with an electric field. Additionally, the control of viscosity is not affected by repetitive operations of the closed device, thereby obtaining a closed device having a smooth operation and good repeatability. The deaeration is achieved under a predetermined reduced pressure, for example, of not more than 100 torr. In addition thereto, a suitable heating process is carried out as required.

Abstract: A shock and vibration isolation system for mounting equipment to a base wall uses a semi-active damper in parallel with a spring arrangement to provide optimum isolation with respect to both shock and vibration. The system comprises a load plate configured for attachment of the equipment thereto and a base plate configured for attachment to the base wall. The base plate is substantially parallel to the load plate. The system further comprises a spring arrangement disposed intermediate the load plate and the base plate. The spring arrangement engages the load plate and the base plate to bias the load plate and the base plate in a separated relationship. A semi-active damper is also disposed intermediate the load plate and the base plate. The a semi-active damper is adapted for providing a selectively variable reaction force to the load plate and the base plate responsive to a relative displacement of the load plate with respect to the base plate.

Abstract: A hydraulic fluid flow passage has a controlled restriction disposed within the passage. The restriction includes a first filter, a second filter and a plurality of particles disposed between the two filters. The particles are either dielectric particles or they are magnetizable particles. The dielectric particles create an electro-rheological fluid between the filters and the magnetizable particles create a magneto-rheological fluid between the filters. The arrangement for the dielectric particles is controlled by an electric field and the arrangement for the magnetizable particles is controlled by a magnetic field.

Abstract: This invention is intended to provide a damping device capable of conducting highly precise damping control. To attain this object, this invention is a damping device used in a machine which includes a rotating object and a motor rotating the rotating object, wherein the damping device includes: a vibration damper filled with an electroviscous fluid having a viscosity changing according to a value of a voltage applied to the electroviscous fluid, and rotatably supporting at least a part of the rotating object in the electroviscous fluid; a voltage applicator applying the voltage to the electroviscous fluid in the vibration damper; and a controller controlling an operation of the voltage applicator so that an optimum voltage, at which the viscosity of the electroviscous fluid absorbing a vibration of the rotating object most effectively is obtained, can be applied to the electroviscous fluid in the vibration damper in accordance with a rotating speed of the rotating object.

Abstract: One aspect of the present invention regards an automotive steering wheel control system having a steering wheel, a magnetorheological damper in communication with the steering wheel and a road wheel control system operably connected to the magnetorheological damper where the magnetorheological damper controls the steering wheel in response to a torque signal from the road wheel control system.

Abstract: A hydraulic vehicle damper is provided for limiting the extent and/or speed of extension of the damper on the rebound stroke with a variety of working fluids including magneto-rheological (MR) fluids, through the use of buoyant sleeve in the working chamber of the damper, rather than having rebound limiting elements attached to the damper piston or damper cylinder tube as in prior vehicle dampers.

Abstract: A shock and vibration isolation system for mounting equipment to a base wall uses a semi-active damper in parallel with a spring arrangement to provide optimum isolation with respect to both shock and vibration. The system comprises a load plate configured for attachment of the equipment thereto and a base plate configured for attachment to the base wall. The base plate is substantially parallel to the load plate with a spring arrangement disposed intermediate the load plate and the base plate. The spring arrangement engages the load plate and the base plate to bias the load plate and the base plate in a separated relationship. The system also comprises a damping arrangement disposed intermediate the load plate and the base plate. The damping arrangement is adapted for providing a selectively variable reaction force to the load plate and the base plate responsive to a relative displacement of the load plate with respect to the base plate.

Abstract: A passive force element on the basis of electrorheological liquids includes a piston with a piston rod guided in a cylindrical housing, and a force introduction element connected with the piston rod. The piston forms, in the cylindrical housing, two variable-volume working chambers, which are filled with electrorheological liquids, and which are connected by a fluid connection including a valve arrangement with an electrorheological liquid valve for controlling the throughflow characteristic. A regulated damping characteristic can be adjustedly set and force peaks are avoided, because the force introduction is achieved via the force introduction element, and the piston is coupled onto the force introduction element via an elastic element.

Abstract: The invention relates to a knee-joint prosthesis with a hydraulic damping cylinder (1) for regulating the swing phase control and stance phase stabilization, and with an electronic control for a force field acting on the hydraulic fluid of the damping cylinder (1), the viscosity of the hydraulic fluid being able to be changed by the force field. The object of the present invention is to make available a knee-joint prosthesis whose electronic control has a high degree of safety and a minimal power consumption. According to the invention, the object is achieved by the fact that an actuating member (6, 7, 9, 12) is provided which generates a permanent force field and acts on the hydraulic fluid with an existing force field which is weakened or strengthened by the electronically controlled force field.

Abstract: Pile weatherstripping has a pile of yarn segments (20) which are attached to a flexible plastic backing strip (1) by ultrasonic welding (21) of the pile thereto. Loops of the yarn (20) are captured in a channel (16) on one side of the backing strip. This channel is formed by extracting flanges (15) from the backing strip by a cutting tool (FIG. 8) having a pair of chiseled cutting surfaces (2a, 2b) tapering inwardly and spaced from each other. The backing strip is preferably wound on a capstan (9) in a plurality of turns so as to feed the strip past the cutting tool. The cutting tool leaves notches along the channel on the outside of the flanges. The base of the channel is unaffected by the cutting tool and presents a stress-free surface at which the yarn is welded. The notches improve thc bending strip flexibility of the backing so as to facilitate insertion of the weatherstrip into a T-slot (22).

Abstract: Fluid current induced vibrations, as well as vortex shedding vibrations induced in a cable stay or a similar elongated, cylindrical element are dampened and substantially eliminated by applying a plurality of flexible active or passive damper bands to the cable at spaced intervals. In underwater currents, the damper bands force or channel the fluid flow over a circular cross-sectional shape, which inhibits lift, and therefore damps the cable stay oscillations. These damper bands can be retrofit to existing cables or can be installed on new cables. Each damper band may include a shiftable mass and an energizing device for facilitating assisted shifting of the mass. A control assembly can actuate all or selected ones of the energizing devices in response to sensed magnitudes of cable stay vibration.

Abstract: A suspension damper including a tube and a damping piston assembly disposed within the tube and slidably mounted therein for reciprocal movement in the tube. The suspension damper also includes a piston rod extending through the tube and connected to the damping piston assembly, a rod guide assembly closing a top end of the tube, and a rebound cut-off disk and spring suspended in the tube between the rod guide assembly and the damping piston assembly and cooperating with the damping piston assembly to provide a rebound cut-off effect between the rebound cut-off disk and the damping piston assembly. The rebound cut-off disk and spring have specific gravities that are less than the specific gravity of the fluid in the tube, such that the disk and the spring are floatable in the fluid.

Abstract: A reduced drag wet disc brake assembly is disclosed in which the viscosity of the fluid in the assembly is capable of changing. At higher traveling speeds, the viscosity of the fluid is low. However, when the viscosity of the fluid increases the speed of the vehicle decreases. The wet disc brake assembly comprises a brake cavity, a rotating plate disposed within the cavity that is rotatingly connected to the hub, two non-rotating plates disposed within the cavity on either side of the rotating plate, a current source connected to the rotating and non-rotating plates, and an electrorheological fluid filling the brake cavity. The viscosity of the electrorheological fluid changes depending on the electric current experienced by the fluid. In an alternative embodiment, the brake assembly also includes a coiled conductive wire connected to a current source to produce a magnetic field and the cavity is filled with magnetic Theological fluid instead of electrorheological fluid.

Abstract: A vibration damper assembly to dampen the vibration generated in a motor vehicle and transmitted through, for example, a steering assembly. The vibration damper assembly includes a rotor disposed within a housing. The rotor is operatively connected to a velocity generating member such as a pinion that is integrated with the steering assembly. A conductive sleeve is disposed between the housing and the rotor. A coil engages the sleeve and is capable of generating a magnetic field that is transmitted through the sleeve. A plate separates the rotor from the sleeve thereby defining a viscous fluid chamber and a Magneto-Rheological (MR) fluid chamber between the rotor and the sleeve. The viscous fluid chamber includes a Newtonian fluid and the MR fluid chamber includes a MR fluid having sheer properties reactive to the magnetic field.

Abstract: A damper for dampening vibrations of a rotatable steering shaft of a motor vehicle comprises a rotor and means for rotating the rotor at a rate proportional to and greater than rotation of the steering shaft. Magnetorheological fluid is disposed at least partially around the rotor, and has a viscosity variable to vary a load on the rotor.

Abstract: A vibration isolation system, with an actuator having two nested, relatively movable members defining an interior portion, and a magnetostrictive member coupled to both nested members and within the interior portion. A variable-strength magnetic field is applied to the magnetostrictive member, for controlling the elongation of the magnetostrictive member, to thereby control the relative positions of the two nested members.

Abstract: A permanent magnet brake system consists of a first body with an active area and a second body with an active area. Between the first and the second active area is a fluid. The fluid activates with a magnetic field when the brake is activated.

Abstract: A passive force element on the basis of electrorheological liquids, in which there is arranged a piston with piston rod, which is guided in a cylindrical housing, whereby the piston rod is connected with a force introduction element, and whereby the piston forms, in the cylindrical housing, two variable-volume working chambers, which are filled with electrorheological liquids, and which are connected by a fluid connection, and whereby the fluid connection comprises a valve arrangement for controlling the throughflow characteristic, which comprises an electrorheological liquid valve, is to be further embodied in such a manner, that a regulated damping characteristic can be adjustedly set and force peaks are avoided. This is achieved in that the force introduction is achieved via a force introduction element and the piston (11, 12, 13, 14) is coupled onto the force introduction element via an elastic element.

Abstract: A variable resistance cell and method provides a variable resistance response to a load factor, such as a load, a load rate, a strain, a strain rate, a pressure, or a deflection. A variable viscosity fluid is displacable between first and second chambers of an enclosure though an orifice in response to the load factor. The variable viscosity fluid has a viscosity that is variable corresponding to the load factor to vary an ability of the variable viscosity fluid to flow through the orifice. The variable viscosity fluid can be a shear stiffening material that increases in viscosity with an increase in a load factor applied to the shear stiffening material, a magneto rheologic fluid responsive to a magnetic field, or an electro rheologic fluid responsive to an electric field. The enclosure can be compressible between first and second positions.

Abstract: The invention provides a vehicle damper assembly including a housing including a fluid carried therein, a piston slidably carried in the housing, and a rod operably attached to the piston. The piston includes a curved portion positioned adjacent a housing inner surface. The invention further provides a vehicle damper assembly including housing means for carrying a fluid, piston means from reducing binding contact with the housing means, and rod means for moving the piston means. The invention further provides a method of reducing binding contact in a vehicle damper assembly. A longitudinal radius is determined for a piston based on a housing inner surface. The piston is formed with a curved portion based on the longitudinal radius. The curved portion is positioned adjacent the housing inner surface.

Abstract: A damper for dampening vibrations of a rotatable steering shaft of a motor vehicle comprises a rotor and means for rotating the rotor at a rate proportional to and greater than rotation of the steering shaft. Magnetorheological fluid is disposed at least partially around the rotor, and has a viscosity variable to vary a load on the rotor.

Abstract: The subject inventive steering damper assembly includes a rotor sleeve having open first and second ends and a drive plate disposed in the open second end. A core is co-axially disposed in the rotor sleeve closing the open first end of the rotor sleeve and defining a magnetic fluid chamber with the sleeve. A Magneto-Rheological fluid is disposed in the magnetic fluid chamber. The drive plate is flexible to provide manufacturing and operational tolerance, and is securely attached to the open second end of the rotor sleeve. Flexibility is derived from at least one aperture disposed in the drive plate. The aperture may be formed in a variety of shapes including elongated, round and oval shaped apertures.

Abstract: A piston rod for use in a magnetorheological dampening device having a surface finish that renders the device resistant to wear at the elastomeric seal/piston rod interface. The piston rod has a surface finish of Ra<0.065 &mgr;m and &Dgr;a≦1.4°, as measured using a Gaussian filter with a 0.08 mm cut-off length. There is further provided a method of achieving the surface finish, including rotating the piston rod while moving an abrasive tape against the outer surface of the rod.

Abstract: According to the present invention, electrorheological fluid is deaerated after it is sealed in a closed device which is operated by the electrorheological fluid. Thus, it is possible to control the operation of the closed device in accordance with an electric field. Additionally, the control of viscosity is not affected by repetitive operations of the closed device, thereby obtaining a closed device having a smooth operation and good repeatability. The deaeration is achieved under a predetermined reduced pressure, for example, of not more than 100 torr. In addition thereto, a suitable heating process is carried out as required.

Abstract: A variable length shaft is provided including a housing defining an internal space. A shaft is connected to a plunger device disposed in said internal space. The internal space is filled with magneto-rheological fluid which is selectively provided with a magnetic field for solidifying the fluid to prevent movement of the plunger within the internal space. When the magnetic field is removed, the plunger device moves freely for allowing variation in the length of the variable length shaft system.

Abstract: This invention is intended to provide a damping device capable of conducting highly precise damping control.

Abstract: The invention relates to an electrically variable spring/mass vibrating force coupler with variable damping, electrically adjustable spring characteristic curves and electrically adjustable, variable natural frequencies using electro-rheological or magneto-rheological fluids in its coupling elements to couple masses and springs

Abstract: A magneto-rheological damping device comprises a core element capable of acting as a magnetic circuit which carries a magnetic flux, and a case element surrounding a portion of the core element. A passage exists between the case element and core element, and an amount of magneto-rheological fluid is positioned between the core element and case element to flow within the passage. A magnetic flux generator is positioned adjacent a portion of the core element and is operable to generate a magnetic flux which acts upon the magneto-rheological fluid in the passage to affect the flow of fluid in the passage. The core element comprises a plurality of stacked laminations, which form a series of individual magnetic poles with gaps therebetween. The magnetic flux generator is operable to generate a magnetic flux in the poles and case element and across the gaps to affect the fluid flow in the passage.

Abstract: An aircraft landing gear includes a sealed cylinder divided by a cylinder head to define an upper chamber and a lower chamber. The lower chamber is further divided by a piston having a piston rod passing in a sealed manner through the lower cylinder end. The cylinder head includes one or more orifices, the opening of each containing an electromagnetic coil configured to control the viscosity of the magneto-rheological oil passing therethrough. The electrical current through the electromagnetic coil is continually controlled by a microcomputer with attached sensors for piston position and pressure between the desired piston and the cylinder head, such that the pressure between the piston and the cylinder head decelerates the aircraft evenly throughout the desired piston stroke. The pressure also is limited to a desired maximum level so that, in a severe crash, the shock absorber will absorb significant energy before it fails structurally.

Abstract: A magneto-rheological fluid device including a housing defining a cavity, a piston slidably disposed in the cavity to divide the cavity into first and second portions, a passage defined on an exterior surface of the piston fluidly coupling the first and second portions of the cavity, a magneto-rheological fluid disposed in the cavity such that motion of the piston is damped by flow of the magneto-rheological fluid through the passage and a magnet disposed to produce a magnetic field within the cavity substantially parallel to the motion of the piston at the exterior surface of the piston.

Abstract: A vibration damper assembly to dampen the vibration generated in a motor vehicle and transmitted through, for example, a steering assembly. The vibration damper assembly includes a rotor disposed within a housing. The rotor is operatively connected to a velocity generating member such as a pinion that is integrated with the steering assembly. A conductive sleeve is disposed between the housing and the rotor. A coil engages the sleeve and is capable of generating a magnetic field that is transmitted through the sleeve. A plate separates the rotor from the sleeve thereby defining a viscous fluid chamber and a Magneto-Rheological (MR) fluid chamber between the rotor and the sleeve. The viscous fluid chamber includes a Newtonian fluid and the MR fluid chamber includes a MR fluid having sheer properties reactive to the magnetic field.

Abstract: A magnetorheological fluid stopper comprises a rotor and a stator, which is in operable communication with the rotor, and wherein one of the rotor and the stator is disposed around the other of the rotor and the stator. A magnetorheological fluid is disposed at the rotor and the stator.

Abstract: A vibration damping device is mounted between two spaced portions of a vehicle for absorbing road forces exerted on the vehicle. A cylindrical housing forms an internal piston chamber and is connected at one end to one portion of the vehicle, with an outer end of the rod of a piston which is slidably mounted within the piston chamber, being connected to another portion of the vehicle. A fluid transfer duct is formed between the housing and piston and provides communication between fluid subchambers formed on opposite sides of the piston within the piston chamber. An electrode is attached to either the housing or piston for applying a voltage across the duct to affect the rheological response of an electrorheological (ER) fluid flowing therethrough to provide a controllable mechanism to modify the damping force characteristics of the device. Each end of the piston rod is slidably supported by a slide bushing assembly which is mounted within an end of the housing.

Abstract: A vehicle suspension damper assembly is provided which includes a cup member with a threaded opening formed therein. A piston rod includes a threaded portion, which is engaged in the threaded opening. An electrical connector including a terminal portion is received in an opening formed in the piston rod. The threaded engagement between the piston rod and the cup member is a predetermined length that reduces deflection of the cup member to reduce transfer of load to the terminal portion of the electrical connector.

Abstract: A damper body for a magnetorheological (MR) damper and associated methods of forming the damper body. The damper body is formed of a base material, such as a steel, and is coated with an abrasion-resistant layer comprising chromium. The layer of chromium provides a sliding wear surface for sliding contact with a reciprocating piston. To avoid high-stress abrasive wear over the expected service life of the magnetorheological damper, the layer of chromium has a minimum thickness greater than or equal to a minimum thickness of about 8 &mgr;m. In other embodiments, be fore applying the abrasion-resistant layer of chromium, the damper body is coated with a layer of a hard coating material having a hardness greater than the hardness of the base material. The effective hardness of the damper body is a composite of the respective hardnesses of the base material comprising the damper body and the layer of hard coating material.

Abstract: A piston assembly for use with an MR fluid damper. The piston assembly has a piston core and a flux ring positioned in a desired alignment with the piston core so that the flux ring forms an annular flow gap the piston core. The flux ring is secured to the piston core in the desired alignment by a plurality of projections extending across the flow gap between an inner surface of the flux ring and an outer surface of the piston core. The projections are molded through flux ring holes intersecting the inner and outer surfaces of the flux ring. A method for making the piston assembly is also described and claimed.

Abstract: A magneto-rheological (“MR”) damper having a damper body tube containing an MR fluid. A piston assembly is disposed in the damper body tube and forms an annular flow gap between the piston assembly and the damper body tube. The piston assembly has a piston core containing ferrous material and an electromagnetic coil mounted on the piston core for generating a magnetic field. The damper further includes a ferromagnetic member positioned outside of the damper body tube substantially adjacent the piston assembly for providing at least a part of a magnetic flux return path for the magnetic field.

Abstract: The invention relates to a device for damping vibrations in a steering wheel. The device comprises a damping means and an attenuation mass connected with the damping means. An electrical control unit is provided which is coupled with the damping means. The control unit is able to alter mechanical vibration characteristics of the device such that different vibration frequencies can be damped.