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US 2009/0152971 A1Published application
Small DC motor
AssigneeMinebea Motor Manufacturing Corporation
InventorMinoru Kuroda
Life of this patent
Estimating the term…
Abstract
A small DC motor includes a motor frame having a cylindrical portion, the cylindrical portion having a constant thickness and having a cross section in a shape that comprises four sides and connecting portions, each of the connecting portions connecting adjacent two of the four sides and being located inward from a corresponding corner in a quadrangle comprising the four sides; and a magnet having a circumferential surface on an inside thereof and having conformable contact with the motor frame on an outside thereof.
Claims12
A small DC motor, comprising:
- a motor frame having two ends and a side wall;
- wherein the side wall surrounds a magnet and a rotor and includes four straight portions and at least four connecting portions;
- wherein each of the connecting portions is located between a pair of the side portions;
- wherein the magnet includes at least four poles and has an outer surface conforming to the motor frame and an inner surface forming a circular opening and wherein the width of the magnet between the inner and outer surface varies;
- wherein the rotor is located in the circular opening;
- wherein the side wall includes the same number of connecting portions as the number of poles contained in the magnet and wherein each of the connecting portions is a segment of a circle having a center located away from the center of the circular opening and having a radius less than the radius of the circular opening so that the ratio of the radius of the connecting portion to the radius of the circular opening is between about 65 percent to about 85 percent.
3 more elements
A small DC motor, comprising:
- a motor frame having two ends and a side wall;
- wherein the side wall surrounds a magnet and a rotor and includes four straight portions and at least four connecting portions;
- wherein each of the connecting portions is located between a pair of the side portions;
- wherein the magnet includes at least four adjacent magnet sections, each magnet section having a different polarity to the adjacent magnet section, and wherein each magnet section has an outer surface conforming to the motor frame and an inner surface combining with the other magnet sections to form a circular opening and wherein the width of the magnet between the inner and outer surface varies;
- wherein the rotor is located in the circular opening;
- wherein the side wall includes at least four connecting portions wherein each of the connecting portions is located adjacent to only one magnet section and wherein each connecting portion forms a segment of a circle having a center located away from the center of the circular opening and having a radius less than the radius of the circular opening and wherein the radius of the circle related to the connecting portion is less than the radius of the circular opening so that each magnet section is tapered from a center portion of the magnet section to each end portion of the magnet section and wherein each magnet section has a radial minimum thickness located at each end and a radial maximum thickness located at the center portion of the magnet section.
3 more elements
Dependencies are inferred from the claim text.