Electric motor with external rotor
AssigneeMol Belting Company
InventorLaurens Wolters
Life of this patent
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Abstract
An electric motor comprises a shaft to which a stator is fixedly mounted and a rotor is rotatably mounted. The shaft is stiffened by a plurality of plates mounted to the shaft and held in compression thereon. The position of the rotor relative to the shaft and the speed of rotation of the rotor relative to the shaft are determined by a highly accurate opto-reflective sensor assembly. The shaft is mounted to a structural support by way of a mounting block that dampens virtually all vibrations generated by the motor for quiet operation. A rotor extension provides adaptability for operation with wider belts e.g. a treadmill.
Claims16
In an electric motor of the type comprising an internal stator, including a shaft fixedly mounted to a structural support and having multiple windings capable of reversible current flow to alter the winding polarity, and an external rotor rotatably mounted to the shaft and having multiple magnets radially spaced about the periphery of the stator, with each of the magnets having at least one predetermined pole;
- the improvement wherein:
- the stator comprises a plurality of plates on the shaft under sufficient compression to inhibit bending of the shaft due to external forces that would otherwise tend to cause the windings to contact the magnets.
A method of forming a winding core for an electric motor of the type comprising an internal stator, including a shaft fixedly mounted to a structural support and having multiple windings capable of reversible current flow to alter the winding polarity, and an external rotor rotatably mounted to the shaft and having multiple magnets radially spaced about the periphery of the stator, with each of the magnets having at least one predetermined pole, comprising the steps of:
- providing a shaft with a keyway oriented at an acute angle relative to the longitudinal axis of the shaft;
- providing plates, each having radial poles with caps at the end of each pole and a key corresponding in shape to the keyway;
- placing a stop on the shaft;
- sliding each plate on the shaft following the keyway with the first plate bearing against the stop until a plurality of plates are mounted to the shaft;
- compressing the plates to form a lamination;
- and
- securing a lock nut on the shaft adjacent to the last plate to hold the lamination in compression.
A method of forming a winding core for an electric motor of the type comprising an internal stator, including a shaft fixedly mounted to a structural support and having multiple windings capable of reversible current flow to alter the winding polarity, and an external rotor rotatably mounted to the shaft and having multiple magnets radially spaced about the periphery of the stator, with each of the magnets having at least one predetermined pole, comprising the steps of:
- providing a hollow cylindrical jig having at least one keyway;
- providing plates, each having a central opening, radial poles with caps at the end of each pole, and having a key corresponding in shape to the keyway;
- placing a stop in the jig;
- sliding each plate in the jig following the keyway with the first plate bearing against the stop until a plurality of plates are disposed in the jig;
- pressing a shaft into the central openings compressing the plates to form a lamination;
- and
- securing a lock nut on the shaft adjacent to the last plate to hold the lamination in compression.
In an electric motor of the type comprising an internal stator, including a shaft fixedly mounted to a structural support and having multiple windings capable of reversible current flow to alter the winding polarity, and an external rotor rotatably mounted to the shaft and having multiple magnets radially spaced about the periphery of the stator, with each of the magnets having at least one predetermined pole;
- the improvement wherein:
- the shaft is mounted to the structural support through at least one mounting block having a yoke with two opposing bushed pins and a clamp carrying the shaft, mounted to the bushings whereby the mounting block damps vibrations of the motor in all directions while maintaining torsion stability.
In an electric motor of the type comprising an internal stator, including a shaft fixedly mounted to a structural support and having multiple windings capable of reversible current flow to alter the winding polarity, and an external rotor rotatably mounted to the shaft and having multiple magnets radially spaced about the periphery of the stator, with each of the magnets having at least one predetermined pole;
- the improvement comprising:
- a sensor assembly capable of generating over 1000 pulse signals for each revolution of the rotor.
In an electric motor of the type comprising an internal stator, including a shaft fixedly mounted to a structural support and having multiple windings capable of reversible current flow to alter the winding polarity, and an external rotor rotatably mounted to the shaft and having multiple magnets radially spaced about the periphery of the stator, with each of the magnets having at least one predetermined pole;
- the improvement wherein:
- a first end of the shaft is mounted to the structural support and the second end of the shaft is not;
- the rotor has an extension mounted at the end thereof nearer the second shaft end;
- and
- a second shaft has one end secured to the structural support and a second end mounted rotatably to the extension, collinear with the shaft.
Dependencies are inferred from the claim text.