Electrical generator or motor structure – Dynamoelectric – Rotary
Patent
1991-02-11
1992-10-20
Stephan, Steven L.
Electrical generator or motor structure
Dynamoelectric
Rotary
310 45, 310261, H02K 2112, H02K 1512, H02K 122
Patent
active
051572974
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
1. Technical Field
The present invention relates to a structure of the radial type rotor in a synchronous type motor, which has a shaft comprised of a magnetic material and which holds the rotor core by magnets.
2. Background Art
In general, rotor shafts are high in strength and are made using inexpensive ferrous bar materials. In a rotor of a radial type where the rotor core is held by magnets, however, the existence of a ferrous shaft, which is a ferromagnetic body, results in a smaller density of magnetic flux passing through the magnet portions close to the shaft upon magnetization and thus causes incomplete magnetization. Further, after magnetization, when turning the rotor so as to obtain the torque output for the motor, the magnetic flux leaks to the shaft and therefore it sometimes is not possible to obtain a desired torque output.
To reduce the leakage of magnetic flux at the magnetization and the output rotation, the shaft material has been made of stainless steel or other nonmagnetic materials and the region of the shaft opposing the magnets has been made smaller.
Stainless steel, however, is expensive and by making the shaft smaller in diameter, the strength of the shaft is remarkably reduced.
DISCLOSURE OF THE INVENTION
Accordingly, to resolve the above problems, an object of the present invention is to provide a rotor structure which raises the magnetization of the magnets and raises the torque output without reducing the strength of the shaft, at low cost.
In consideration of the above object, there is provided a structure of the radial type rotor which has a shaft comprised of a magnetic material and has a rotor core held by magnets, said structure of the radial type rotor characterized in that the portion of the shaft opposing the rotor body is formed to be narrower than other portions and the gap between the narrow portion of the shaft and the said rotor body is filled with a resin material which is then cured.
Further, it provides a structure of the radial type rotor characterized in that a thin annular node is formed at the above-mentioned narrow portion regardless of the presence or absence of the above-mentioned resin material.
Although the shaft is comprised of iron or another high strength magnetic material, the portion opposing the rotor body is made narrow so that it is possible to reduce the leakage of magnetic flux from the magnet portion to the shaft both upon magnetization and upon rotation of the rotor. In this case, the shaft is reinforced in strength by filling and curing a resin material in the gap between the said shaft and the rotor body.
Further, instead of filling a resin material, it is possible to provide a node at the narrow portion of the shaft and have the node abut against the inner circumference of the rotor when a bending force acts on the shaft so as to enable the bending force to be withstood.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a lateral sectional view of a rotor according to the present invention;
FIG. 2 is a longitudinal sectional view along the arrow line II--II of FIG. 1;
FIG. 3 is a lateral sectional view showing another embodiment of the rotor according to the present invention; and
FIG. 4 is a longitudinal sectional view along the arrow line IV--IV of FIG. 3.
BEST MODE FOR CARRYING OUT THE INVENTION
Below, a more detailed explanation will be made of the present invention based on the embodiments shown in the attached drawings. First, referring to FIG. 1 and FIG. 2, a rotor core sector 20 comprised of laminated plates and held by a plurality of magnets 18 is held by end plates 14 at its two ends in the longitudinal direction along with the magnets, 18 extending longitudinally and radially with respect to the core, and, further, is penetrated and held by rods 16 to thus form a rotor body 10. Through this rotor body 10 is inserted a shaft 12, which is tightened to form the rotor. The portion opposing the rotor body 10 is a narrow shaft portion 12a formed to be small in diameter. The radial type of rotor shown in this figure
REFERENCES:
patent: 2213724 (1940-09-01), Vogel
patent: 4674178 (1987-06-01), Patel
patent: 4746827 (1988-05-01), Ochiai et al.
Copy of Search Report, 3 pages.
Fanuc Ltd.
Stephan Steven L.
To E.
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