Abstract:
A magnetorheological (MR) device (20) including settling stability. The MR fluid device (20) includes a housing (22) including a hollow (30), a moving element (26) contained within the hollow (30), the housing (26) and moving element (26) cooperating to form a working section (36) and a chamber (32) within the hollow (30), a MR fluid (38) contained within the working section (36) and the chamber (32), a coil (40) or the like for generating a magnetic field to act upon the MR fluid (38) contained within the working section (36) to cause a rheology change therein, and a magnet (25) or electromagnet (31) generating a low-level magnetic field to act upon a substantial portion of the MR fluid (38) contained in the chamber (32) to minimize settling of the particles in the MR fluid. Linear and rotary acting embodiments are included.
Abstract:
A controllable platform suspension system (20) for treadmills (18) and other platforms and devices therefor which exhibit controllability of the impact condition of the platform, such as a treadmill deck (36). In the treadmill application, user-selectable damping/stiffness is provided to simulate variable track conditions, such as pavement, rubber, grass, gravel, sand, and the like. The controllable suspension system (20) comprises spring mounts (40) or the like or a flexible deck (36) for allowing movement of the deck (36) relative to the frame (22) at a contact location (29) due to impact and a controllable device such as an Electrorheological (ER) device, Electrophoretic (EP) device, Electromechanical Hydraulic (Semi-Active) device, controllable mounting, or a Magnetorheological (MR) device, such as an MR brake (42a, 42a, 42b), MR damper (42d), or MR mount (42c, 42e, 42f) interconnecting between the frame (22) and platform (36) to provide the user-variable impact restraint. Various MR devices are described which exhibit controllability in a first direction (ex. bound) and substantially unrestricted motion in a second direction (ex. rebound).
Abstract:
The invention relates to magnetorheological (MR) fluid devices and the process of controlling the force in exercise equipment by utilizing the MR fluid devices. The MR fluid devices include rotary and linear acting varieties and are useful for controlled forces in exercise bicycles, recumbent exercisers, ski machines, rowing machines, and stair stepper machines. The rotary MR fluid device is comprised of a rotor supported by bearings and received within a housing. An MR fluid is received adjacent the rotor and within a cavity in the housing and the MR fluid is controlled by an applied magnetic field to vary the operating torque resistance. Spring biasing the rotor allows for relaxed tolerances. Optimization of the Ri/Ro ratio is described which reduces the size and weight of the device. The linear acting version utilizes simple extensible pumps and an external MR fluid valve to provide a modularized system.
Abstract:
A portable controllable fluid device (20a) for rehabilitation of injured limbs, appendages and joints (33a). The rehabilitation device (20a) includes a first bracket (22a) for fixedly securing to a first body part, such as a lower leg (25), a second bracket (24a) for fixedly securing to a second body part, such as a foot (26), and a controllable fluid brake (27a) such as a magnetorheological fluid brake including a magnetorheological fluid contained therein having a carrier fluid and disbursed magnetic particles, attached between the first bracket (22a) and second bracket (24a). The controllable fluid brake (27a), preferably acts in a rotary fashion and provides resistive forces about an axis adjacent said body joint (33a) to exercise the muscles upon movement of said first bracket (22a) relative to said second bracket (24a) resulting from movement of the user's first body part relative to the second body part. The device (20a) is portable and can be used to rehabilitate, for example, a wrist, elbow, knee or ankle joint in the user's home. The device (20a) allows variable adjustment of the level of resistance felt by the rehabilitating user by adjusting a controller (28a). In another embodiment, feedback information is used to control the level of resistance according to a predetermined force/torque profile(s). A potentiometer (53d) provides the feedback information regarding position to the controller (28a).
Abstract:
A controllable fluid device (20) for rehabilitation of injured or weakened complex appendages such as the hands and feet. The controllable fluid device (20)includes a reservoir (34)which contains a sufficient amount of controllable fluid (52)such as a Magnetorheological (MR) fluid. A magnetic field generator (36)provides the magnetic field (H) which is applied to the controllable fluid (52) by a magnetic circuit (60). In one aspect, an electromagnet including a coil (58) and core (54) provides the magnetic field (H). The intensity of the magnetic field is controlled via a controller (38). In another aspect, the magnetic field (H) is provided by a permanent magnet (44) and a mechanical shunt mechanism (42) is used to vary the magnetic field intensity. Other embodiments include a heater unit (66) with optional thermostat (74).
Abstract:
A magnetorheological material containing a carrier fluid and a magnetically active particle. The particle has been modified so that the surface of the particle is substantially free of contamination products. The contamination products are removed from the surface of the particle by abrader processing, chemical treatment or a combination thereof. Magnetorheological materials prepared using the particles from which contamination products have been removed exhibit significantly enhanced magnetorheological effects.
Abstract:
A magnetorheological material containing a carrier fluid and an iron alloy particle component. The particle component can be either an iron-cobalt alloy or an iron-nickel alloy. The iron-cobalt alloy has an iron:cobalt ratio ranging from about 30:70 to 95:5 while the iron-nickel alloy has an iron:nickel ratio ranging from about 90:10 to 99:1. The iron alloy particle components are capable of imparting high yield stress capability to magnetorheological materials.
Abstract:
This invention relates to sealless designs of magnetorheological fluid dampers. With these sealless designs a piston rod extends above and below a piston head within a cylindrical housing and has frustoconical elastomer elements attached to and between the rod and housing to allow translation of the piston head and rod. The piston head has a coil contained radially therein that produces magnetic flux in and around the piston. The advantages of utilizing an MR fluid according to the invention include magnetic fields which are easily produced by low voltage electromagnetic coils, damping effects which are velocity independent, and higher yield strength obtained by the MR fluid capable of generating greater damping forces.
Abstract:
Magnetorheological (MR) fluid dampers are optimized. Dimensional relationships involved in the flow of magnetic flux are related to an operational parametric ratio of magnetic flux density in the fluid to the flux density in the steel. A magnetic valve is utilized to change the flow parameters of the MR fluid and, hence, the operational characteristics of the damper. Several embodiments depicting improved piston designs, including spool as well as toroidal configurations, are disclosed. In addition, both single and twin-tube housing designs are presented.
Abstract:
An electrorheological material containing a carrier fluid, an anionic surfactant particle component, and an activator. The non-abrasive anionic surfactant acts as both a particle component and a surfactant and the electrorheological material is miscible with water and will not mar the surface of objects utilized in an electrorheological device.