An electromagnetic actuating apparatus, in particular a proportional magnet or switching magnet, includes a magnet armature (4) guided for axial movement in a pole tube (2). The pole tube is at least partially surrounded by a coil winding and is adjoined by a pole core (10) via a separating region (20) forming a magnetic decoupling. On energization of the coil winding (52), a magnetic force acts on the armature (4) to move the armature (4) in the direction of the pole core (10) within a travel area. At least one insert (28) of ferromagnetic material with a preset axial thickness is between the armature (4) and the pole core (10) to shorten, as desired, the axial length of the travel area.

Apparatus, systems, and methods used to produce linear and rotational motion, acceleration, and actuation by the use of mobile ferromagnetic or permanent magnets subjected to asymmetric electromagnetic field distributions are disclosed herein. A variety of exemplary embodiments and applications are described, involving different coil and actuator geometries to include and allow for both stationary and moving magnets, electric fields, and magnetic fields.

An apparatus for negative stiffness including one or more solenoids for generating a magnetic field. A moveable magnet is moveable relative to the one or more solenoids through the one or more solenoids. The one or more solenoids are configurable to generate an at least substantially quadratic magnetic field about an equilibrium position at which the resultant force on the moveable magnet is zero. Depending on the respective pole orientation, generating a quadratic magnetic field about an equilibrium position provides a substantially linear negative stiffness characteristic with displacement.

In a main magnetic circuit, first pulling force generated based on a first component of the magnetic flux flowing through the main magnetic path pulls a movable core in a reciprocation direction of the movable core. The first pulling force increases with a reduction of a dimension of the gap. In an auxiliary magnetic circuit, second pulling force generated based on the second component of the magnetic flux flowing through the auxiliary magnetic path pulls the movable core in the reciprocation direction of the movable core. In the auxiliary magnetic circuit, the second pulling force with the dimension of the gap being within a first range is changed to be higher than the second pulling force with the dimension of the gap being within a second range, the second range being smaller than the first range.

A device and a method are provided for determining a stroke of an armature of a magnetic valve which has a coil and the armature is displaceable by magnetic force, including: providing at least one reference data set which includes a magnitude of a current through the coil and a magnitude of the magnetic flux in the case of a known magnitude of the stroke; generating a current flow through the coil of the magnetic valve in order to generate a magnetic field for generating a magnetic force on the armature, which magnetic force displaces the armature in the direction for the opening of a closure element coupled to the armature; determining a magnitude of the magnetic flux when the armature abuts against a driver of the closure element; and determining the magnitude of the stroke based upon the determined magnitude of the magnetic flux and the reference data set.

A downhole magnetic clamping system for a tool is provided. The clamping system may include a first permanent magnet, and a yoke, movably positioned next to the first permanent magnet and movable to at least two positions, a first position in which a magnetic attraction force produced by the first permanent magnet on structures exterior to the tool is reduced relative to a second position. In addition, the clamping system may further include a non-linear resilient member applying a resilient force to the yoke in the direction of the second position. Further, the clamping system may include an electro-magnetic coil, operable in a first and second direction to initiate movement of the yoke between the first position and the second position.

A solenoid device includes two electromagnetic coils, two stationary cores, two plungers and a yoke that surrounds the two electromagnetic coils. When a first electromagnetic coil is energized, magnetic flux flows through a first magnetic circuit that includes the first stationary core. When the two electromagnetic coils are energized, magnetic flux of the first electromagnetic coil flows through the first magnetic circuit, and magnetic flux of the second electromagnetic coil flows through a second magnetic circuit that includes a second stationary core. When energization of the first electromagnetic coil is stopped while maintaining energization of the second electromagnetic coil, the magnetic flux of the second electromagnetic coil continues to flow through the second magnetic circuit and a third magnetic circuit that includes the two stationary cores. A magnetism limiting portion is disposed in a portion of the second magnetic circuit that does not overlap the third magnetic circuit.

A solenoid device includes two electromagnetic coils, two stationary cores, two plungers and a yoke that surrounds the two electromagnetic coils. When a first electromagnetic coil is energized, magnetic flux flows through a first magnetic circuit that includes the first stationary core. When the two electromagnetic coils are energized, magnetic flux of the first electromagnetic coil flows through the first magnetic circuit, and magnetic flux of the second electromagnetic coil flows through a second magnetic circuit that includes a second stationary core. When energization of the first electromagnetic coil is stopped while maintaining energization of the second electromagnetic coil, the magnetic flux of the second electromagnetic coil continues to flow through the second magnetic circuit and a third magnetic circuit that includes the two stationary cores. A magnetism limiting portion is disposed in a portion of the second magnetic circuit that does not overlap the third magnetic circuit.

A solenoid includes: a coil wound around a bobbin; a case section accommodating the coil; a tubular yoke arranged on an inner circumferential portion of the coil; and a plunger arranged on an inner circumferential portion of the yoke, and moving from a start position along an axial direction of the yoke by magnetic attraction force generated in the yoke, wherein a diameter increasing portion whose diameter is increased from the start position toward a lower part in the axial direction is formed on an outer circumferential surface of the yoke, and the diameter increasing portion overlaps at least a part of a moving region of a lower-part side end portion of the plunger, and wherein an inner circumferential surface of the yoke guides the movement of the plunger and the yoke includes a contact member that regulates the movement of the plunger on the inner circumferential surface.

A solenoid includes: a coil wound around a bobbin; a case section accommodating the coil; a tubular yoke arranged on an inner circumferential portion of the coil; and a plunger arranged on an inner circumferential portion of the yoke, and moving from a start position along an axial direction of the yoke by magnetic attraction force generated in the yoke, wherein a diameter increasing portion whose diameter is increased from the start position toward a lower part in the axial direction is formed on an outer circumferential surface of the yoke, and the diameter increasing portion overlaps at least a part of a moving region of a lower-part side end portion of the plunger, and wherein an inner circumferential surface of the yoke guides the movement of the plunger and the yoke includes a contact member that regulates the movement of the plunger on the inner circumferential surface.