Electric motor construction
First Claim
1. A subfractional horsepower, permanent magnet motor comprisingan annular stator assembly comprising a pair of axially aligned annular stator coils in stacked relation, complementary housing members enclosing said coils and defining a series of stator poles equally spaced around the outer periphery of said annular stator assembly, each said housing member having a base plate portion with a central aperture therein,an elongated sleeve portion disposed within said annular stator assembly and in engagement with the inner peripheral surface of each said base plate aperture of said metal housing members to provide with said metal housing members magnetic circuits that surround said stator coils,a motor frame comprising a base and a core upstanding from said base, a passage in said core for receiving a motor shaft,the thermal conductivity of said core being significantly greater than the thermal conductivity of said sleeve portion,said sleeve portion being disposed over and interfitted with said core, an axial channel that extends inside at least one of said stator coils along the axial length of said core to said base,the leads of said one coil extending radially inward from said one coil into said channel and along said channel to said base and extending therefrom externally of said motor,a rotor having a cylindrical sleeve portion with a circumferential array of axially extending permanently magnetized rotor poles equally spaced about the periphery of said rotor sleeve,a motor shaft secured to said rotor and disposed within said passage in said core for supporting said rotor for rotation about said stator assembly with a uniform air gap between the outer surface of said stator assembly and the inner surface of said rotor sleeve.
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Accused Products
Abstract
A subfractional horsepower, permanent magnet motor has a stator assembly with a pair of axially aligned stator coils in stacked relation, and complementary metal housing members that enclose the coils and define a series of stator poles. An elongated sleeve disposed within the annular stator assembly provides, with the metal housing members, magnetic circuits that surround the stator coils. The stator sleeve is disposed over and interfitted with a frame core that has significantly greater thermal conductivity than the thermal conductivity of the stator sleeve. A channel extends from at least one of the stator coils along the axial length of the core to the base, and the leads of that coil extend radially inward from the coil and along the channel to the base and therefrom externally of the motor. The motor rotor has a cylindrical sleeve portion with a circumferential array of axially extending permanently magnetized rotor poles equally spaced about the periphery, and the rotor is supported such that a uniform annular air gap is provided between the outer surface of the stator assembly and the inner surface of the rotor sleeve.
43 Citations
19 Claims
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1. A subfractional horsepower, permanent magnet motor comprising
an annular stator assembly comprising a pair of axially aligned annular stator coils in stacked relation, complementary housing members enclosing said coils and defining a series of stator poles equally spaced around the outer periphery of said annular stator assembly, each said housing member having a base plate portion with a central aperture therein, an elongated sleeve portion disposed within said annular stator assembly and in engagement with the inner peripheral surface of each said base plate aperture of said metal housing members to provide with said metal housing members magnetic circuits that surround said stator coils, a motor frame comprising a base and a core upstanding from said base, a passage in said core for receiving a motor shaft, the thermal conductivity of said core being significantly greater than the thermal conductivity of said sleeve portion, said sleeve portion being disposed over and interfitted with said core, an axial channel that extends inside at least one of said stator coils along the axial length of said core to said base, the leads of said one coil extending radially inward from said one coil into said channel and along said channel to said base and extending therefrom externally of said motor, a rotor having a cylindrical sleeve portion with a circumferential array of axially extending permanently magnetized rotor poles equally spaced about the periphery of said rotor sleeve, a motor shaft secured to said rotor and disposed within said passage in said core for supporting said rotor for rotation about said stator assembly with a uniform air gap between the outer surface of said stator assembly and the inner surface of said rotor sleeve.
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2. An electric motor comprising
a permanent magnet rotor having a cylindrical sleeve portion defining a plurality of permanently magnetized rotor poles, a shaft supporting said rotor for rotation about the axis of said rotor, a motor frame including a rotor shaft support core extending into the internal volume defined by said rotor sleeve, an annular stator assembly mounted within said rotor sleeve on said rotor shaft support core with an annular air gap between the outer peripheral surface of said stator assembly and the inner peripheral surface of said rotor sleeve, said stator assembly including annular coil means mounted on a common axis and magnetic circuit structure of magnetically permeable material that defines a circumferential array of spaced stator poles around said coil means extending parallel to said axis, and provides a magnetic circuit about said coil means, said magnetic circuit structure including an inner magnetically permeable sleeve portion at the inner periphery of said coil means, said shaft support core being of material having greater thermal conductivity than said inner sleeve portion, and said inner sleeve portion being disposed over and in heat conductive engagement with said support core such that heat generated in said coil means passes inwardly through said magnetically permeable sleeve portion to said heat conducting core and then flows axially through said core, and out of said motor.
Specification