| 摘要 |
A rotary actuator has a ferromagnetic armature with at least one arcuate-shaped wall extending circumferentially at the perimeter of the armature. The stator has a pair of axially and circumferentially aligned axial walls, separated by an axial air gap, disposed radially outward of, and in relatively circumferentially advanced relationship to, each such arcuate-shaped wall. Current flow in an electromagnetic coil associated with the stator causes magnetic flux to pass from one axial wall of each pair, across an air gap, to the respective arcuate-shaped armature wall, through that wall, and across a radial air gap to the other axial wall of each pair. Each arcuate-shaped wall has a ferromagnetic characteristic that causes it to be positioned to increasingly circumferentially overlap the respective pair of axial walls as the magnetic flux increases. The actuator may include a rotary flow control valve, such as an EGR valve for an automotive engine.
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