Electrical generator or motor structure – Dynamoelectric – Rotary
Patent
1990-03-30
1993-04-06
Skudy, R.
Electrical generator or motor structure
Dynamoelectric
Rotary
310 42, 310 43, 310114, 310156, H02K 122
Patent
active
052006620
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a joint structure of an output shaft and a radial type rotor comprising an alternate circumferential arrangement of rotor cores and magnets.
BACKGROUND ART
Usually, a radial type rotor is mounted fixedly on an output shaft by attaching end plates to the opposite ends of the rotor, and fixing the end plates to the output shaft. A shrinkage fit is another method of fixedly mounting a rotor on an output shaft. Another method is the use of pins for fastening a rotor to an output shaft. Most rotors are impregnated with an impregnant to prevent the play of the component rotor cores and magnets thereof relative to each other.
When the rotor is assembled by either the method employing a shrinkage fit or the method using pins, a gap is formed between the rotor and the output shaft, except for end portions of the rotor, and therefore, the output shaft within the rotor is bent when an external force acts on the rotor assembly. The method employing a shrinkage fit is unable to fasten a long, high-torque rotor to an output shaft with a high reliability, because torque is transmitted from the rotor to the output shaft through only the two front and rear portions where the rotor and the output shaft are joined together by a shrinkage fit, regardless of the length of the rotor, while the output torque of a longer rotor is greater than that of a shorter rotor.
DISCLOSURE OF THE INVENTION
Accordingly, to solve the above problem, an object of the present invention is to provide a joint structure of a rotor and an output shaft, capable of preventing the bending of the output shaft and fastening the rotor to the output shaft with a high reliability.
In view of the above object, the present invention provides a joint structure of a radial type rotor and an output shaft in a synchronous motor, the rotor comprising an alternate circumferential arrangement of rotor cores and magnets, characterized in that a resin for molding is filled and hardened in a gap between the inner circumference of the rotor and the circumference of the output shaft.
Since the molding resin is filled and hardened in the gap between the inner circumference of the rotor and the circumference of the output shaft, a bending action on the output shaft is unable in practice to bend the output shaft. Since the torque generated by the rotor is transmitted through the molding resin filling the gap over the entire length of the rotor to the output shaft, the local concentration of torque, namely, the concentration of torque on portions corresponding to the opposite ends of a rotor, is obviated. Thus the joint structure of a rotor and the output shaft has a high reliability structure and a high torque transmitting reliability.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a front view of a rotor assembly constructed by joining a rotor and an output shaft according to the present invention;
FIG. 2 is an enlarged fragmentary cross-sectional view taken along the line II--II in FIG. 1;
FIG. 3 is a fragmentary cross-sectional view showing a joint structure according to the present invention in one stage of fabrication; and
FIG. 4 is a fragmentary cross-sectional view of a rotor assembly constructed by another method of fabrication different from the method shown in FIG. 3.
BEST MODE OF CARRYING OUT THE INVENTION
The present invention will be described in detail hereinafter with reference to the accompanying drawings. A method of fixedly joining a radial type rotor 12 comprising an alternate circumferential arrangement of magnets 14 and rotor cores 16 to an output shaft 10, and a joint structure constructed by the above method will be explained. In this embodiment, the elongated rotor 12 comprises four unit rotors 12a, 12b, 12c and 12d having a predetermined axial length and arranged in an axially contiguous arrangement, and rods 18 for positioning rotor cores 16 at a predetermined radial position in cooperation with end plates 26 are inserted through the cores 16 to hold magnets 14. When the relatively long roto
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patent: 3221194 (1965-11-01), Blackburn
patent: 3917967 (1975-11-01), Robinson
patent: 4263711 (1981-04-01), Sakano
patent: 4543506 (1985-09-01), Kawada
patent: 4570097 (1987-10-01), Kawada
patent: 4678954 (1987-07-01), Takeda
patent: 4954736 (1990-09-01), Kawamoto
Tagami Kiyoshi
Uchida Hiroyuki
Fanuc Ltd.
Skudy R.
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