Interlocking yoke and endplates for permanent magnet rotor

Details Interlocking yoke and endplates for permanent magnet rotor Interlocking yoke and endplates for permanent magnet rotor

1984-12-20

1987-01-27

Budd, Mark O.

Electrical generator or motor structure

Dynamoelectric

Rotary

310261, H02K 2112

Patent

active

046396276

DESCRIPTION:

BRIEF SUMMARY
DESCRIPTION

1. Technical Field
The present invention relates to a permanent-magnet field rotor for use in a synchronous motor such as AC servo motor, etc.
2. Background Art
Generally, the permanent-magnet field rotor used in synchronous motor, e.g., AC servo motor, comprises a shaft, a plurality of yokes to form magnetic paths, these being radially disposed on the outer circumference of the shaft, a plurality of permanent magnets each held between two successive yokes, and a pair of end plates fixed to the shaft to support each yoke at the opposite ends thereof.
In the conventional rotors of this kind, the pair of end plates and each yoke engage each other on a plane perpendicular to the shaft axis; therefore, a bonding agent, welding or similar technique must be used to fix the yokes and end plates, and tie bolts and nuts are used to rigidly couple each yoke with the end plates. However, the adhesion of the bonding agent used for the above purpose becomes degraded due to the heat and centrifugal force of the rotor. Welding causes deformation of the yokes and end plates and also complicates the manufacturing process. Also the use of the tie bolts and nuts adds to the number of parts of the rotor.


DISCLOSURE OF THE INVENTION

An object of the present invention is to overcome the above-mentioned drawbacks of the prior art by providing a permanent-magnet field rotor in which yokes and end plates can be rigidly coupled together without adding to the number of parts and which can be simply assembled.
The above object is accomplished by a permanent-magnet field rotor, according to the present invention, comprising a shaft, a pair of end plates fixed to the shaft, which are axially spaced from each other, a plurality of permanent magnets each extending outwardly in the radial direction of the shaft and also axially between the end plates, and a plurality of yokes disposed between successive permanent magnets to hold the permanent magnets, each of which extends axially between the end plates, each of the yokes being provided with a protrusion at either end thereof and each of the end plates being provided with an engagement hole therein which serves, when engaged on the protrusion, to prevent the yoke from moving circumferentially and radially.
According to the another aspect of the present invention, the shaft should preferably be provided with an axially extending keyway in the outer cylindrical surface thereof, and each of the pair of end plates has an inner cylindrical face fittable to the shaft and a protrusion projecting inwardly from the inner cylindrical face in the radial direction which engages in the keyway in the shaft, thereby securely preventing the pair of end plates from rotating about the shaft.
According to a yet another aspect of the present invention, the yoke should preferably be provided at either circumferential corner thereof with a protruding edge for preventing the permanent magnet from moving in the radial direction of the shaft.
The foregoing and other objects and advantages of the present invention will be better understood from the ensuing description made by way of example with reference to the accompanying drawings.


BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a half longitudinal sectional side elevation of an AC servo motor in which the permanent-magnet field rotor according to the present invention is adopted;
FIG. 2 is a longitudinal sectional view of the rotor shown in FIG. 1;
FIG. 3 is a partially sectional end view of the rotor shown in FIG. 1;
FIG. 4 is a plan view of the rotor shaft shown in FIG. 1;
FIG. 5 is an end view of the rotor end plate shown in FIG. 1;
FIG. 6 is a side elevation of the rotor end plate shown in FIG. 5;
FIG. 7 is a side elevation of the rotor yoke shown in FIG. 1;
FIG. 8 is an end view of the yoke shown in FIG. 7; and
FIG. 9 is an end view showing a variation of the end plate.


BEST MODE FOR CARRYING OUT THE INVENTION

FIG. 1 shows an AC servo motor employing one embodiment of the permanent-magnet field rotor according to the present invention, a

REFERENCES:
patent: 826650 (1906-07-01), Christensen
patent: 2655611 (1953-10-01), Sherman
patent: 2719931 (1955-10-01), Kober
patent: 3422294 (1969-01-01), Parker
patent: 3427486 (1969-02-01), Whitney
patent: 4337405 (1982-06-01), Hishida
patent: 4513216 (1985-04-01), Muller
patent: 4543506 (1985-09-01), Kawada et al.

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