Reluctance-type motor having widened bottom

Details Reluctance-type motor having widened bottom Reluctance-type motor having widened bottom

2000-10-06

2002-08-27

Nguyen, Tran (Department: 2834)

Electrical generator or motor structure

Dynamoelectric

Rotary

C310S254100, C310S168000

Reexamination Certificate

active

06441529

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a reluctance-type motor which is multiple-phase half-wave energized.
2. Related Art
A reluctance-type motor produces high output torque and has simple construction. However, it is used in only limited fields, because it also produces high ripple in the output torque. When a protruded salient pole of a rotor and a protruded salient pole of a stator completely face each other, that is, align in phase, during the rotation of the rotor rotation, magnetic resistance between poles decreases thereby causing magnetic saturation and hence the ripple in the output torque.
The reluctance-type motor is typically constructed as shown in
FIG. 8. A
rotor has protruded poles
100
on a rotor ring
102
, and a stator has protruded poles
101
on a stator ring
103
. Poles
100
and
101
protrude from the rings
102
and
103
, respectively. It is assumed that each protruded pole
100
of the rotor has the same widths rD
1
and rD
2
(rD
1
=rD
2
) at its bottom (root) and top (free end) in a rotation direction, and that each protruded pole
101
of the stator has the same widths sD
1
and sD
2
(sD
1
=sD
2
) at its bottom and top in a rotation direction. In this instance, the magnetic flux concentrates in the angled corner part between pole and the ring. As a result, the magnetic saturation occurs when poles
100
and
101
completely face each other in a radial direction, thus greatly decreasing the output torque as shown in FIG.
3
A.
It is also assumed that the ring
102
has a width rW in the radial direction, which is less than a half of the width rD
2
of pole
100
(rW<0.5×rD
2
), and that the ring
103
has a width sW in the radial direction, which is less than a half of the width sD
2
of pole
101
(sW<0.5×sD
2
). In this instance, the magnetic flux generated in the pole cannot flow sufficiently into the ring thereby causing the magnetic maturation when poles
100
and
101
completely face each other. As a result, the output torque sharply decreases as shown in
FIG. 4A
resulting in the ripple in the output torque.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a reluctance-type motor that has less drop in output torque and hence less ripple in the output torque even salient poles of a rotor and a stator completely face each other.
According to the present invention, a reluctance-type motor comprises a core for a rotor or a stator. The core has a cylindrical ring and a plurality of salient poles protruding from the ring in a radial direction of the ring. Each pole has a bottom width and a top width in a circumferential direction of the core at its bottom which is connected to the ring and at its top which is away from the ring, respectively. The bottom width (D
1
) is sized to be larger than the top width (D
2
), and the ring has a width in a radial direction of the core to allow at least a half of magnetic flux in the pole to pass through the ring.
Preferably, the width of the ring is sized to be larger than a half of the top width of the pole. The pole is shaped to have a round corner at the bottom or in a trapezoid in which the bottom width is larger than the top width. The core has a plurality of thin magnetic plates stacked in an axial direction of the core, each plate has a plurality slits in each protrusion which forms the pole, and each plate has a thickness which is less than 5 times of a maximum width of each slit.


REFERENCES:
patent: 713604 (1902-11-01), Churchward
patent: 737576 (1903-09-01), Burrow
patent: 919458 (1909-04-01), Poth
patent: 3564312 (1971-02-01), Bunea
patent: 4186316 (1980-01-01), Singh
patent: 4647802 (1987-03-01), Konecny
patent: 5804896 (1998-09-01), Takehara et al.
patent: 5844346 (1998-12-01), Kolomeitsev et al.
patent: 6025668 (2000-02-01), Kolomeitsev
patent: 8-126273 (1996-05-01), None

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