Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
1999-01-22
2001-07-24
Ramirez, Nestor (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C310S256000, C310S216006, C310S183000, C310S156030, C310S054000, C310S057000, C310S06000A, C310S06800R, C310S201000, C310S051000, C310S198000
Reexamination Certificate
active
06265801
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to permanent magnet type electrical rotating machines, and more particularly to permanent magnetic type electrical rotating machines in which the construction of the stators is improved in order to prevent reduction of the properties of the permanent magnets that are the rotors.
2. Description of the Related Art
FIG. 1
is a partial cross-section view, in a direction orthogonal to the axis, showing an example of a prior art permanent magnet type electrical rotating machine.
FIG. 2
is an enlarged development view of part C of FIG.
1
.
In FIG.
1
and
FIG. 2
, slots
3
F are formed at equal intervals on the inner periphery of stator core
2
H that is formed in a cylindrical shape by laying silicon steel punched plates one on another. Stator winding
4
B is inserted into these slots
3
F in two layers. Trapezoidal wedges
11
, fabricated of magnetic material described later, are press-fitted into the inner periphery sides of slots
3
F. Tooth-like parts
10
B of the stator core are formed between slots
3
F.
Wedges
11
are made of hardened material by mixing malleable iron powder with resin and a reinforcing agent to become high-resistance magnetic material with a relative magnetic permeability (&mgr;) of about 10~100.
At the same time, permanent magnets
6
of arc-shaped cross-section are mounted in close contact with the outer periphery of rotor core
7
in the peripheral direction and bonded with an adhesive agent to form rotor
5
. Magnets magnetized with S poles on the inner periphery side and N poles on the outer periphery side are mounted alternately with magnets magnetized with the reverse polarity, according to the number of poles.
Prevention of the peeling-off of permanent magnets
6
due to the centrifugal force generated by high-speed rotation is designed by press-fitting cylindrical retaining ring
8
on the outer peripheries of these permanent magnets
6
. Specified gap
9
is formed between the outer periphery of retaining ring
8
and inner periphery of stator core
2
H.
In a permanent magnet type electrical rotating machine constructed in this way, magnetic flux
13
emanating from the outer periphery side of permanent magnets
6
reaches the outer periphery side of stator core
2
H from wedges
11
and tooth-like parts
10
B between these wedges
11
after passing through retaining ring
8
and gap
9
, as shown in FIG.
2
. From this outer periphery side, the flux once more passes through a magnetic path via the neighbouring permanent magnet poles.
This permanent magnetic type electrical rotating machine is driven in rotation at high speed by increasing the frequency of the inverter power source that excites stator winding
4
B.
FIG. 3
is a drawing corresponding to
FIG. 2
, and is an enlarged partial development illustration showing the magnetic flux distribution emanating from a permanent magnet for the case when non-magnetic wedges
12
are used in place of magnetic material wedges
11
.
In
FIG. 3
, the point of difference from above-mentioned
FIG. 2
is that the greater part of magnetic flux
13
emanating from permanent magnets
6
passes through tooth-like parts
10
B of stator core
2
H while hardly any passes through non-magnetic wedges
12
.
That is to say, hardly any flux passes through the inner periphery side of stator winding
4
B, but is concentrated in the trapezoidal parts of the inner periphery sides of tooth-like parts
10
.
Consequently, the peaks of the sine wave of the magnetic flux passing between permanent magnets
6
and the stator oscillate as shown in FIG.
4
(
a
), and therefore the rotor torque oscillates.
On the other hand, with a permanent magnet type electrical rotating machine that incorporates magnetic material wedges
11
shown in
FIG. 2
, eddy currents flow in wedges
11
due to the magnetic flux passing through wedges
11
. Thus, not only does the temperature of wedges
11
rise, but since, as mentioned above wedges
11
are made of hardened material , wedges
11
are very brittle, extreme care is required in their manufacture and assembly processes.
Moreover, eddy currents also flow in retaining ring
8
due to the magnetic flux passing through retaining ring
8
. Since permanent magnets
6
are heated when the temperature of retaining ring
8
rises, the magnetic properties (coercive force) of permanent magnets
6
reduce.
SUMMARY OF THE INVENTION
Accordingly, one object of the present invention is to provide a novel permanent magnet type electrical rotating machine that may prevent the reduction in the permanent magnet properties consequent upon the temperature rise of the retaining ring, and may also solve the problem of wedge damage.
In order to achieve the above object, in a permanent magnet type electrical rotating machine of the present invention, in opposition to the inner part of a cylindrical stator, in which multiple enclosed slots that form projecting gaps on the shaft center side of their stator winding insertion parts are formed radially at equal intervals, a rotor, on the outer periphery of which multiple permanent magnets with their polarities reversed in the radial direction are closely mounted, is inserted on the same shaft, and a cylindrical retaining ring is closely inserted on the outer periphery of this rotor.
Also, in order to achieve the above object, in a permanent magnet type electrical rotating machine of the present invention, the stator winding is composed of U-shaped wire bundles of rectangular cross-section, and the open ends of the U-shapes are connected.
Moreover, in order to achieve the above object, in a permanent magnet type electrical rotating machine of the present invention, the stator is divided into two at the shaft center side, or the outer periphery side, of the stator winding.
Furthermore, in order to achieve the above object, in a permanent magnet type electrical rotating machine of the present invention, the shapes of the inner periphery of the outer stator and the outer periphery of the inner stator of a stator that is divided into two at the outer periphery side of the stator winding are formed as ellipses.
Still further, in order to achieve the above object, in a permanent magnet type electrical rotating machine of the present invention, the shapes of the inner periphery of the outer stator and the outer periphery of the inner stator of a stator that is divided into two at the outer periphery side of the stator winding are formed as circles having straight line parts in at least one place.
Again, in order to achieve the above object, in a permanent magnet type electrical rotating machine of the present invention, the shapes of the inner periphery of the outer stator and the outer periphery of the inner stator of a stator that is divided into two at the outer periphery side of the stator winding are formed in shapes from pentagons to polygons with the same number of angles as the number of stator coils.
Yet again, in order to achieve the above object, in a permanent magnet type electrical rotating machine of the present invention, the heat intake sides of heat pipes are installed in the projecting parts formed in the above-mentioned enclosed slots of the stator.
Also, in order to achieve the above object, in a permanent magnet type electrical rotating machine of the present invention, detector coils that detect the angle of rotation of the rotor are installed in the projecting gaps formed in the enclosed slots of the stator.
Moreover, in order to achieve the above object, in a permanent magnet type electrical rotating machine of the present invention, vibration suppression coils, through which a current corresponding to the rotor vibration is passed and that suppress the vibration of the rotor, are installed in the projecting gaps formed in the enclosed slots of the stator.
Furthermore, in order to achieve the above object, in a permanent magnet type electrical rotating machine of the present invention, projecting parts, against which the outer peripheries of the stator coils butt, are
Hashiba Yutaka
Sakai Kazuto
Takahashi Norio
Tokumasu Tadashi
Dinh Le Dang
Kabushiki Kaisha Toshiba
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Ramirez Nestor
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