Pollock, VandeSande & Priddy
Linear actuator
 In a linear actuator including a casing, an output shaft passing through the casing and being mounted slidably in a direction along the axis thereof, a solenoid coil disposed within the casing in coaxial relation to the output shaft, a magnet disposed in such a manner that the magnetic flux thereof is linked with windings of the coil, the output shaft mechanically connected to one of the magnet and the coil to form a movable part, and a spring adapted to urge the output shaft in one direction along the axis thereof, and a spacer made of high permeability material and interposed between the casing and either the coil or the magnet, whichever is fixed on the casing to form a stationary part. 
Honda Giken Kogyo Kabushiki Kaisha
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additional inventional inventional
Hidemi Mikio Hiroyuki
Suzuki Nakagawa Yamada