Joseph A Kelemen

US Patent:

45969701, Jun 24, 1986

Filed:

Dec 21, 1984

Appl. No.:

6/685034

Inventors:

Robert D. Vanderlaan - Kalamazoo MI
Joseph A. Kelemen - Kalamazoo MI

Assignee:

Pneumo Corporation - Boston MA

International Classification:

H01F 708

US Classification:

335229

Abstract:

Limited angle torque motor includes a motor power section comprising a rotor assembly having one or more permanent rotor magnets which are magnetized in a diametrical direction and a stator assembly surrounding the rotor assembly. The magnetic flux in the motor power section produces an inherent magnetic centering spring rate tending to keep the rotor assembly at the midpoint of its rotational angle range. However, when a direct or pulse width modulated current is applied to the stator windings, a cross flux is produced through the stator and rotor assemblies of the motor power section which produces the desired limited rotational angle range for the rotor assembly. The motor also includes a separate magnetic centering spring section which provides another centering spring function in addition to the basic centering spring function inherent in the motor power section. The magnetic centering spring section is located immediately adjacent to the motor power section, and the permanent rotor magnet of the rotor assembly extends into the centering spring section, such centering spring section additionally including two or more permanent magnets with polarities in alignment with respect to the rotor magnet.