Method of making a multi-coil/multi-magnet actuator Patent #: 4692999
AbstractA reciprocating electromagnetic actuator (20) includes a movable reciprocator (36) within a stationary stator (22). A permanent magnet (46) forms part of the reciprocator. A compensation coil (64, 66) forms part of and is embedded within the stator. A drive coil (72, 74) forms part of and is embedded within the reciprocator. The drive coil is selectively energized with an drive current (ID) from a current source (100). The compensation coil is selectively energized with an compensation current (IC) from another energy source (102). The current applied to the compensation coil is of opposite polarity from the current applied to the drive coil, and the ampere-turns resulting from the current ID applied to the drive coil must be equal to the ampere-turns resulting from the current IC applied to the compensation coil. The drive current ID interacts with the magnetic flux from the permanent magnet in order to move the reciprocator with a force that is proportional to the drive current at all locations along the stroke path of the reciprocator. In one embodiment (FIGS. 1-4), the reciprocator is mounted for linear reciprocating motion within the stator. In another embodiment (FIG. 19), the reciprocator is mounted for rotational reciprocating motion. Other embodiments (FIGS. 6, 9-12, 14) place the permanent magnet at different locations and/or orientations within the reciprocator or the stator.