2221 results about "Magnetorheological fluid" patented technology

The present invention relates to a variable-torque magnetorheologically actuated prosthetic knee which utilizes a plurality of interspersed and alternating rotors and stators to shear magnetorheological fluid in gaps formed therebetween. Advantageously, by operating in the "shear mode" there is substantially no or negligible fluid pressure buildup or change. Moreover, the multiple MR fluid gaps or flux interfaces desirably allow for the production of a large torque at low speed-eliminating the need for a transmission-and also for a wide dynamic torque range. One embodiment of the invention allows the rotors and / or stators to close the gaps therebetween to create a frictional torque component, thereby forming a "hybrid" braking system which provides a total torque or damping which is a combination of viscous torque and frictional torque.

A variable footwear support system includes at least one rheological body within a sole of an article of footwear, control electronics within the article of footwear, and at least one E / M field generator coupled to the control electronics and arranged operably proximate to at least one rheological body. The sole is formed of a resilient material and the rheological body contains a Theological fluid having a viscosity that is variable in the presence of an energy field. The control electronics is adapted to generate at least one control signal. The at least one E / M field generator is adapted to generate an energy field corresponding to a control signal generated by the control electronics upon the rheological body.

The present invention relates to a variable-torque magnetorheologically actuated prosthetic knee which utilizes a plurality of interspersed and alternating rotors and stators to shear magnetorheological fluid in gaps formed therebetween. Advantageously, by operating in the "shear mode" there is substantially no or negligible fluid pressure buildup or change. Moreover, the multiple MR fluid gaps or flux interfaces desirably allow for the production of a large torque at low speed-eliminating the need for a transmission-and also for a wide dynamic torque range. One embodiment of the invention allows the rotors and / or stators to close the gaps therebetween to create a frictional torque component, thereby forming a "hybrid" braking system which provides a total torque or damping which is a combination of viscous torque and frictional torque.

An improved damping apparatus that utilizes a fluid having a viscosity that may be varied by the application of an electromagnetic field, such as a magnetorheological fluid or an electrorheological fluid, to provide the damping response. The damping apparatus includes a linear to rotary conversion mechanism which comprises a translatable member that is adapted for linear translation in a forward and a reverse direction and a rotatable member comprising a rotatable shaft that is rotatably coupled to the translatable member; wherein translation of the translatable member in one of the forward or the reverse directions produces a forward or a reverse rotation of the rotatable member and shaft, respectively. The damping apparatus also includes a damping mechanism which comprises a hub that is fixed to the shaft, a means for generating a variable electromagnetic field in response to an applied electrical signal that may be continuously varied in response to an input signal that is representative of a desired damping force and a fluid having a viscosity that may be continuously varied by application of the electromagnetic field that is in touching contact with the hub. Application of the variable electromagnetic field to the fluid produces changes in the viscosity of the fluid that in turn provides variable resistance to rotation of the hub and resistance to translation of the translatable member, thereby providing a damping apparatus with a continuously variable damping response.

A haptic feedback device including a fluid viscosity-controlled brake that outputs high forces to the device user at low cost while maintaining inherent safety. An interface device includes a manipulandum physically contacted by the user. A sensor senses a position of the manipulandum and outputs a sensor signal. The interface device also includes a brake including a field-controlled fluid having a viscosity that can be controlled by controlling an electric current in a coil, where a resistive force or drag on the manipulandum is controlled by controlling the fluid's viscosity. The fluid can be an electrorheological fluid controlled by an electric field or a magnetorheological fluid controlled by a magnetic field. In one preferred embodiment, the resistive force is controlled by adjusting a degree of contact of the brake with the manipulandum based on the fluid's viscosity. Disclosed embodiments include fishing devices, bicycle simulators, and control knobs.

The invention in some embodiments relates to systems and methods of loading fluid in a prosthetic knee. A vacuum fill technique is utilized in one embodiment to load magnetorheological fluid within small gaps in a chamber of a prosthetic knee. Advantageously, this allows for an efficient loading scheme thereby desirably allowing for faster manufacturing speed. Another advantage is that the magnetorheological fluid is substantially uniformly distributed within the small gaps thereby desirably providing consistent production.

The present invention discloses a grinding-polishing method based on magnetorheological effect. Said method is characterized by that in the magnetorheological fluid a kind of free abrasive material is added, used as grinding-polishing liquor and injected into the between of magnetic body and workpiece surface, under the action of magnetic field the ferromagnetic particles in the magnetorheological fluid can be arranged by strings to cover the abrasive material pacticles and can be constrained in the end face of magnetic body to form magnetic grinding brush, said magnetic grinding brush can be used for grinding-polishing workpiece surface. Said invention also provides a grinding-polishing device for implementing said grinding-polishing method. Said device includes grinding tool mounted on main shaft connected with motor and working table for mounting workpiece.

A strut (12) is configured for an active suspension system (142) which provides electronic control for both the force applied by the strut (12) and the dampening characteristics of the strut (12). A compressible fluid (18) is used within the strut (12), and preferably includes a compressible base fluid and electromagnetic field responsive particles (132) which are suspended in the compressible base fluid. The electromagnetic field responsive particles (132) are preferably closely matched in density and modulas of elasticity to that of the compressible base fluid to prevent sedimentation of the particles (132) and to maintain the elasticity of the compressible fluid (18). The amount compressible fluid (18) within the strut (12) is electronically controlled to determine the force applied by the strut (12) and a field strength applied to the compressible fluid in a fluid flow passage is electronically controlled to determine the dampening characteristics of the strut (12).

The present invention relates in one embodiment to magnetorheological fluids utilized in prosthetic joints in general and, in particular, to magnetorheological fluids utilized in controllable braking systems for prosthetic knee joints. Preferred magnetorheological fluids of the present invention comprises polarizable iron particles, a carrier fluid, and optionally an additive. Preferred additives include, but are not limited to functionalized carrier fluids as well as derivatized fluoropolymers. Preferred carrier fluids include, but are not limited, to perfluorinated polyethers.

Active pressure relief valves and methods of use for regulating atmospheric conditions within an interior compartment of a vehicle generally include an active material to effect movement of a flap relative to an opening. The active material has the ability to remember its original at least one attribute such as dimension, shape, and / or flexural modulus, which can subsequently be recalled by applying or removing an external stimulus, as will be discussed in detail herein. Suitable active materials include, without limitation, shape memory alloys, ferromagnetic shape memory alloys, shape memory polymers, piezoelectric materials, electroactive polymers, magnetorheological fluids and elastomers, electrorheological fluids, composites of one or more of the foregoing materials with non-active materials, combinations comprising at least one of the foregoing materials, and the like. Depending on the particular active material, the activation signal can take the form of, without limitation, an electric current, a temperature change, a magnetic field, a mechanical loading or stressing, or the like.

An apparatus and method for damping vibration, especially torsional vibration due to stick-slip, in a drill string, Sensors measure the instantaneous angular velocity of the drill string at one or more locations along the length of the drill string. One or more vibration damping modules are also spaced along the length of the drill string. When torsional vibration above a threshold is detected, the damping module imposes a reverse torque on the drill that dampens the torsional vibration. The reverse torque can be created by imparting a frictional resistance to the rotation of the drill string. The frictional resistance can be created externally, by extending friction pads from the damping module so that they contact the bore hole wall and drag along the bore hole as the drill string rotates, or internally by anchoring a housing mounted on the drill string to the wall of the bore hole and then imposing frictional resistance on a fluid, such as a magnetorheological fluid, flowing within the drill string.

The invention relates to a magnetorheological-material-based 3D (Three-Dimensional) printing type rapid prototyping method and device. According to the principle of magnetorheological effect, a magnetorheological material is used as a 3D printing raw material; and a 3D solid model is constructed by spraying the magnetorheological material on a workbench with a magnetic field, rapidly solidifying and prototyping the sprayed magnetorheological material, and then depositing the treated material layer by layer. A computer is provided with three control circuits; one circuit is used for controlling the flow of a driving pump, namely the flow at a spray head; another circuit is used for controlling the 3D motion of the spray head through a servo mechanism; and the rest circuit is used for controlling colour mixing and allocating of a colourized ink box. The magnetorheological material is solidified and prototyped by utilizing the magnetic field generated by an electromagnet. According to the magnetorheological effect of the magnetorheological material, a temperature control module in the traditional melting, spraying and rapid prototyping type 3D printing method is replaced by the magnetic field; in addition, the device disclosed by the invention is also different from a high-pressure electric field required by an electrorheological fluid effect, has the advantages of being simple in structure, low in energy consumption and cost, capable of realizing the microminiaturization and the like, and can be applicable to the fields of process design, art and entertainment, prosthesis model and the like.

The invention involving a magnetorheological fluid damping device for automobile suspension system.The magnetic field generator of this damping device consists of permanent magnet and electromagnetic coil.On the top of the damping device,there are guide apparatus and damping regulator,the function of which is that to ensure the damping channel is uniform annular duct and to meet the high-damp requirement in the restoration process and low-damp requirement in the compression process of damper seperately.The current in the electromagnetic coil designs of bi-directional and this controls the magnetic field intersity of the damping channel,decreases the excitation current of the electromagnetic coil,reduces energy consumption and decreases damper fever.On the non-controlling conditions,this damping device has the equivalent characteristics of the traditional shock absorber and can instead the passive shock absorber,after equiping corresponding current controller,this device can regulate the damping characteristics of suspension system,which improves the automobile driving safety and ride comfort.

Tunable structural member for a vehicle generally comprises an active material adapted to selectively undergo a change in at least one attribute in response to an activation signal. The change in the at least one attribute results in a change in the mechanical properties of the tunable structural member. Active materials generally include shape memory alloys, shape memory polymers, magnetorheological fluids and elastomers, piezoelectrics, electroactive polymers, and the like.

Active pressure relief valves and methods of use for regulating atmospheric conditions within an interior compartment of a vehicle generally include an active material to effect movement of a flap relative to an opening. The active material has the ability to remember its original at least one attribute such as dimension, shape, and / or flexural modulus, which can subsequently be recalled by applying or removing an external stimulus, as will be discussed in detail herein. Suitable active materials include, without limitation, shape memory alloys, ferromagnetic shape memory alloys, shape memory polymers, piezoelectric materials, electroactive polymers, magnetorheological fluids and elastomers, electrorheological fluids, composites of one or more of the foregoing materials with non-active materials, combinations comprising at least one of the foregoing materials, and the like. Depending on the particular active material, the activation signal can take the form of, without limitation, an electric current, a temperature change, a magnetic field, a mechanical loading or stressing, or the like.

An apparatus and a method for generating haptic feedback and a portable device having the apparatus are provided. The haptic feedback generator changes the property of a magneto-rheological fluid or an electro-rheological fluid using a magnetic field or an electric field and transmits haptic feedback using the property variation. The haptic feedback generator includes a controller 620 outputting a control signal for providing a haptic feedback based on application information selected by a user and a haptic feedback generating unit 610 generating the haptic feedback based on the control signal and providing the haptic feedback in response to an external force Fin of the user.

One embodiment of the invention includes an MR fluid of improved durability. The MR fluid is particularly useful in devices that subject the fluid to substantial centrifugal forces, such as large fan clutches. A particular embodiment includes a magnetorheological fluid including 10 to 14 wt % of a hydrocarbon-based liquid, 86 to 90 wt % of bimodal magnetizable particles, and 0.05 to 0.5 wt % fumed silica.

A downhole tool that includes a tractor for assisting movement of the tool through deviated portions of a wellbore. The tractor includes a working fluid that damps vibrations in the tractor by adjusting the viscosity in the fluid. In an example, the working fluid is a magnetorheological fluid that has a viscosity that changes in response to applied electrical energy. The working fluid, which may be used for powering actuators on the tractor, may contain a suspension of magnetic particles.

The invention in some embodiments relates to a dynamic seal for a prosthetic knee. The dynamic seal in one embodiment is utilized to seal a magnetorheological fluid comprising a liquid and solid particles within a chamber of the knee. The dynamic seal embodiments are specially configured with a pre-loaded tensioned garter spring which has a coil spacing that is at least as large as the size of the particles or maximum size of the particles in the magnetorheological fluid. Desirably, this allows the magnetorheological fluid particles to flow in and out of the dynamic seal without clogging the seal and advantageously provides for a reliable dynamic seal.

A system and method for controlling a plurality of accessories associated with a multiple cylinder internal combustion engine having the accessories coupled to an engine crankshaft by an electromagnetic coupling device with a flowable magnetic material disposed between a driving member and a driven member include selectively supplying power to the electromagnetic coupling device in response to at least one operating condition to simultaneously engage or disengage the plurality of engine accessories. Embodiments include a magnetic particle clutch or magnetorheological fluid clutch connected to an engine crankshaft and a plurality of engine accessories that may include an air conditioning compressor, water pump, power steering pump, alternator, and / or supercharger, for example.

A limited slip differential includes a friction clutch mechanism, an electromagnetic coupling, and a camming mechanism disposed between the friction clutch mechanism and the electromagnetic coupling. The camming mechanism converts shearing forces within the electromagnetic coupling to an axial force applied to engage the clutch mechanism. The camming mechanism includes annular discs having axially inclined ramps, and a roller bearing for movement along the ramps to provide for variable spacing between the annular discs, wherein increased spacing is used to apply the axial force.

The invention belongs to the technical field of precise optical polishing processing, and in particular relates to a method and a device for polishing a magnetic field auxiliary flexible rotary brush for an optical element. The method comprises that a ferromagnetic main shaft capable of rotating at a high speed drives a magnetorheological fluid which can be updated circularly to be adsorbed on a finished surface under certain pressure and the action of a magnetic field to form a flexible rotary polishing grinding head which finishes the polishing processing of a whole concave surface in a composite motion mode of self rotation and workpiece rotation. The device is applicable to polishing the concave surface of a conformal optical element; and the method has the characteristic of flexible fine machining and stable polishing removal, can adopt a computer to control the polishing removal distribution, is capable of controlling a polished surface shape, has the advantages of high precision and high surface quality, and is applicable to polishing aspheric surface and free-form surface elements with thin-walls and high gradients.

A magnetorheological fluid-based device and method may include the use of magnetorheological (MR) fluid, a primary magnetic field to control the viscosity of the fluid, and a secondary magnetic field to reduce clumping of ferromagnetic particles.

A haptic interface, including: a button which can be rotated by a user; an interaction element interacting with a magnetorheological fluid, secured to the button; a mechanism measuring a current position of the button; a brake including a magnetorheological fluid and a generation system to generate a magnetic field in the fluid; a controller configured to generate orders for the system to generate a magnetic fluid to modify a value of the magnetic field; and a mechanism to detect torque exerted by a user on the button to know direction of the torque and whether the torque is greater than a given value for a given direction, the controller controlling generation of a magnetic field based on obtained information about the torque at least when the button indicates zero or low speed.

A system and method for self-powered magnetorheological-fluid damping of mechanical vibrations includes a hydraulic cylinder. The hydraulic cylinder is configured for at least partially disposing magnetorheological fluid therein. A piston head is disposed within the hydraulic cylinder. The piston head has first and second sides and is configured to be in sliding engagement with the hydraulic cylinder. A piston rod is at least partially disposed within the hydraulic cylinder and is connected to the piston head on the first side. The system also includes a vibration absorber assembly having housing. The vibration absorber assembly is configured to transduce mechanical vibrations of the piston rod to electric current.

The invention discloses a conical extrusion-shearing type magnetorheological clutch. An iron core input disc is fixed at a front end of an input shaft and an armature output disc sliding axially is arranged at a front end of an output shaft, or the armature output disc sliding axially is arranged at the front end of the input shaft and the iron core output disc is fixed at the front end of the output shaft; a containing cavity is formed between the iron core input disc and the armature output disc; magnetorheological fluid is filled in the containing cavity; a sealing ring for sealing the magnetorheological fluid in the containing cavity is arranged on the periphery of the containing cavity; a coil for driving the armature output disc to move axially to the iron core input disc is further arranged in a working cavity; and an adjusting device for adjusting the volume of the containing cavity is further arranged between the iron core input disc and the armature output disc. The conical extrusion-shearing type magnetorheological clutch has the advantages that: when the clutch is in the working state, through attraction to the armature output disc by a magnetic field generated by the coil, the volume of the containing cavity is reduced, and meanwhile, an extrusion and shearing force is generated against the magnetorheological fluid, so as to transfer a greater torque; in addition, the conical extrusion-shearing type magnetorheological clutch is small in volume, reliable in performance, compact in structure, and good in effect.

A magnetorheological fluid delivery system includes a mixing and tempering vessel. Fluid is admitted to the vessel via a plurality of tangential ports, creating a mixing of the fluid in the vessel and promoting homogeneity. Fluid may be reconstituted in the vessel by metered addition of carrier fluid. A fixed-speed centrifugal pump disposed in the vessel pressurizes the system. Fluid is pumped through a magnetic-induction flowmeter and a magnetic flow control valve having solenoid windings whereby MR fluid is magnetically stiffened to restrict flow. A closed-loop feedback control system connects the output of the flowmeter to performance of the valve. A nozzle having a slot-shaped bore dispenses MR fluid for re-use in the work zone. A planar-diaphragm flush-mounted pressure transducer at the entrance to the nozzle and flowmeter inferentially measure relaxed viscosity and provide signals to a computer for dispensing metered amounts of carrier fluid into the mixing vessel to assure correct composition of the reconstituted fluid as it is dispensed.