Force actuator with dual magnetic operation

An electromagnetic force actuator, for active vibration control, motivated in a dual magnetic manner by a combination of voice-coil-effect and solenoid-effect flux paths, comprising;

• an electromagnetic coil structure of magnetically permeable material constructed and arranged to have a typical cross-sectional shape defining at least one prominent pole facing a common reference line at a predetermined spacing distance and separating two of a plurality of adjacent channels formed in the magnetically permeable material each filled with an oppositely polarized coil winding oriented such that wire ends appear in the cross-sectional shape;
• a magnet structure having at least one permanent magnet with a pair of magnetically opposed prominent poles of magnetically permeable material having a cross sectional shape such as to face the common reference line from a direction opposite the coil structure, disposed along the common reference line such that the prominent pole(s) of the coil structure and those of the magnet structure are located in a staggered symmetric disposition about the common reference line so as to be mutually centered axially;
• suspension means constructed and arranged to retain the coil structure and the magnet structure facing the common reference line at a constant distance therefrom while providing freedom for the electromagnetic coil structure and the magnet structure to vibrate relative to each other in an axial direction along the common reference line:
• magnetic flux path conducting means, including magnetically permeable material, for conducting magnetic flux, configured and arranged to conduct portions of magnetic flux paths extending from a first prominent pole of each magnet through a path to a second and opposite prominent pole thereof, the flux paths including (1) a voice-coil-effect flux path that traverses first and second air gaps serially, each gap being made to have substantially constant separation distance under vibration and each containing respectively a central portion of a first and second one of two adjacent ones of said oppositely polarized coil windings, and (2) a solenoid-effect flux path that traverses serially (a) a first air gap containing an end portion of the first coil winding, (b) a prominent pole of the coil structure that is axially movable with respect to the magnet poles, and (c) a second air gap containing an end portion of the second coil winding;
• the first and second air gaps being constructed and arranged to have respective separation spacings and permeabilities that vary with vibration in a complementary manner;
• said actuator being made to have an odd total number of prominent poles and thus to have at least three prominent poles;
• adjacent magnets being oppositely polarized and adjacent coils being oppositely polarized;
• and
• spring means constructed and arranged to provide a spring force tending to establish and maintain the mutually centered relationship between each prominent pole of the coil structure and corresponding prominent poles of the magnet structure;
• whereby, in response to alternating current applied to the coil windings, at least one of said structures is caused to vibrate relative to the other, operating in first part according to principles of a voice coil type actuator due to e.m.f. of the voice-coil-effect flux path having substantially constant permeability and acting directly on the said oppositely polarized coil windings as a force in an axial direction, and operating in second part according to principles of a dual-gap solenoid type actuator in the solenoid-effect flux path due to magnetic attraction forces typically between a stator prominent pole and an adjacent movable armature prominent pole, with recurrent complementary flux redistribution in the two air gaps from the complementary variation of respective gap separation distances and permeabilities under vibration.