Abstract: Electromagnetic actuators are provided, which generate bidirectional linear force output without magnetic bias from current or permanent magnets. Systems and methods based on the electromagnetic actuators are also provided.

Abstract: Electromagnetic inertial force generators are provided, which include radially polarized permanent magnets providing bias flux across axial gaps to combine with axial coil flux to linearize the actuator output. Coil cooling in the electromagnetic inertial force generators is improved by embedding the coils in the stationary portion of the actuator, allowing for direct transfer of coil heat, and reducing oscillating stresses on coil leads.

Abstract: An electromagnetic inertial force generator is provided, which includes radially polarized permanent magnets providing bias flux across axial gaps to combine with axial coil flux to linearize flux output. An array of components is integrated into a single structure that is more compact and lighter than a monolithic force generator, providing the same level of performance while using less permanent magnet material.

Abstract: Electromagnetic actuators are provided, which generate bidirectional linear force output without magnetic bias from current or permanent magnets. Systems and methods based on the electromagnetic actuators are also provided. In particular, an electromagnetic actuator having a shaft, an axial bearing, coil assembly, top and bottom stationary flux returns, and top and bottom magnetic flux sensors to measure flux crossing the respective top and bottom axial air gaps.

Abstract: Inertial actuators are provided, which use a one-dimensional or a two-dimensional voice coil array to achieve the same force output performance as a monolithic actuator. The voice coil arrays use less permanent magnet and flux conducting material, and have a lower inductance, while achieving increased frequency bandwidth.

Abstract: Exemplary practice of the present invention provides a magnetostrictive actuator characterized by linear force output and uniform magnetic biasing. A center bias magnet drives flux through series magnetostrictive bars in opposite directions while surrounding drive coils apply flux in the same direction through the bars. The net response is substantially linear with respect to the drive coil current. A second parallel set of magnetostrictive bars completes the flux path and adds to the actuator output force. Flux leakage between the parallel bars is compensated by a ferromagnetic shunt or by a tapered magnet providing uniform flux density down the length of the magnetostrictive bars. The closed flux path allows magnetic shielding of the entire actuator, if desired.

Abstract: Exemplary practice of the present invention provides a magnetostrictive actuator characterized by linear force output and uniform magnetic biasing. A center bias magnet combined with a flux transfer tube produces a uniform magnetic bias down the length of a magnetostrictive component. Depending on the inventive embodiment, the magnetostrictive component may include one magnetostrictive element or a pair of collinear magnetostrictive elements. A center bias magnet, in combination with a flux transfer tube, drives magnetic flux through the magnetostrictive component (e.g., a series of magnetostrictive rods) in opposite directions, while surrounding drive coils apply flux in the same direction through the magnetostrictive component. The net response is substantially linear with respect to the drive coil current. The flux transfer tube applies distributed magnetic flux to the magnetostrictive component at a rate that ensures uniform magnetic flux density down the length of the magnetostrictive component.

Abstract: An electromagnetic inertial force generator provides a linear output with improved compactness and reliability because it has no radial gaps and only one pair of axial gaps. Radial permanent magnet rings are directly in contact with inner and outer flux cylinders to provide magnetic bias. The magnetic bias flux flows across two axial air gaps to a supporting flux return structure. A current conducting coil drives magnetic flux across the same axial air gaps. The magnetic bias flux is in opposite directions across the two air gaps, while the coil flux across the two gaps is in the same direction. The combination of bias flux and coil flux cancels in one gap and adds in the other gap, producing a net force on an inertial mass and an equal and opposite force on the supporting structure. The resulting force is linear with current through the drive coil.

Abstract: Exemplary practice of the present invention provides a magnetostrictive actuator characterized by linear force output and uniform magnetic biasing. A center bias magnet drives flux through series magnetostrictive bars in opposite directions while surrounding drive coils apply flux in the same direction through the bars. The net response is substantially linear with respect to the drive coil current. A second parallel set of magnetostrictive bars completes the flux path and adds to the actuator output force. Flux leakage between the parallel bars is compensated by a ferromagnetic shunt or by a tapered magnet providing uniform flux density down the length of the magnetostrictive bars. The closed flux path allows magnetic shielding of the entire actuator, if desired.

Abstract: Exemplary practice of the present invention provides a magnetostrictive actuator characterized by linear force output and uniform magnetic biasing. A center bias magnet combined with a flux transfer tube produces a uniform magnetic bias down the length of a magnetostrictive component. Depending on the inventive embodiment, the magnetostrictive component may include one magnetostrictive element or a pair of collinear magnetostrictive elements. A center bias magnet, in combination with a flux transfer tube, drives magnetic flux through the magnetostrictive component (e.g., a series of magnetostrictive rods) in opposite directions, while surrounding drive coils apply flux in the same direction through the magnetostrictive component. The net response is substantially linear with respect to the drive coil current. The flux transfer tube applies distributed magnetic flux to the magnetostrictive component at a rate that ensures uniform magnetic flux density down the length of the magnetostrictive component.

Abstract: The invention is an electromagnetic inertial force generator that provides a linear output with improved compactness and reliability because it has no radial gaps and only on pair of axial gaps. Radial permanent magnet rings are directly in contact with inner and outer flux cylinders to provide magnetic bias. The magnetic bias flux flows across two axial air gaps to a supporting flux return structure. A current conducting coil drives magnetic flux across the same axial air gaps. The magnetic bias flux is in opposite directions across the two air gaps while the coil flux across the two gaps is in the same direction. The combination of bias flux and coil flux cancels in one gap and add in the other gap producing a net force on an inertial mass and an equal and opposite force on the supporting structure. The resulting force is linear with current through the drive coil.

Abstract: An exemplary magnetic flux sensor in accordance with the present invention is characterized by an electrical output that is proportional to the total static and dynamic flux passing normally through a large area. An oscillating electrical current passing down a conducting area produces Lorentz forces, which are transferred to piezoelectric areas. The piezoelectric areas produce electrical voltage at the oscillation frequency whereby amplitude is proportional to the total magnetic flux passing normally through the conducting area. Demodulating the voltage provides an electrical signal with high sensitivity, dynamic range, and noise immunity.

Abstract: Disclosed is an electrodynamic actuator that simultaneously produces a controlled linear combination of interstructural and inertial forces. Two coil pairs interact with radial or axial permanent magnets. The forces produced in the coil pairs acts between an end of the actuator and a common moveable mass. If the coil pair forces are equal and in the same direction they make the mass move and produce an inertial output force. If the coil pair forces are equal and in opposite directions the mass does not move and interstructural forces are produced between the two ends of the actuator. Combinations of inertial and interstructural forces are produced in a controlled manner by coordinating the electrical current through each coil pair. The actuator efficiency and the low frequency inertial force outputs are greatly improved compared to separate dedicated inertial and interstructural actuators.

Abstract: A shock and acoustic mount for reducing transmission of forces between two relatively moveable members such as a mounted component and a supporting structure, providing a compressible fluid spring with large allowable relative movement of the mounted component and support structure. The mount comprises a casing, a piston shell with one end disposed in the casing and another end extending outside of the casing, and a piston housed in the piston shell, all relatively moveable in response to external axial forces. In one embodiment, the mount is filled with a compressible fluid, such as air, providing an air spring. The piston is sealingly bonded to the inner surface of the piston shell, the bond accommodating acoustic and vibration forces by deformation of the bond material. An annular seal between the piston shell and the casing accommodates large and shock forces.

Abstract: According to one aspect of the invention, a magnetorheological fluid (MRF) damping device includes two concentric coils or groups of coils arranged to produce respective magnetic fields that mutually cancel substantially everywhere but within the gap between them. The rheological properties of the MRF are magnetically controlled within this gap. According to a second aspect of the invention, the piston rod of a MRF damper or other viscous fluid damper communicates its motion to a hollow, capped cylinder. Damping fluid within this cylinder communicates via a narrow channel with damping fluid outside of this cylinder. When the piston rod undergoes motions directed so as to expel fluid from the interior of the cylinder, resistance within the narrow channel causes pressure to build up within the cylinder, but prevents any substantial amount of pressure from building up without the cylinder, thus isolating sealing devices from the highest resistive forces generated within the damping fluid.