Single-phase motor

Details Single-phase motor Single-phase motor

2002-11-20

2004-10-19

Martin, David (Department: 2837)

Electricity: motive power systems

Braking

C318S701000, C318S720000, C318S721000, C310S066000, C310S06800R

Reexamination Certificate

active

06806666

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a single-phase motor, and more particularly to a single-phase motor in which a ring-shaped magnet is mounted to a rotor in such a fashion that a parking magnet and a Hall sensor face the ring-shaped magnet.
2. Description of the Prior Art
Generally, single-phase motors include universal motors, BLDCS, or switched reluctance motors.
FIG. 1
is a circuit diagram illustrating the circuit configuration of a conventional single-phase switched reluctance motor.
As shown in
FIG. 1
, the conventional single-phase switched reluctance motor (SRM) includes a driving circuit
10
, a stator
20
receiving electric power from the driving circuit
10
, and a rotor
30
adapted to rotate by a reluctance torque generated between the stator
20
and the rotor
30
when electric power is applied to the stator
20
.
In detail, the stator
20
, which is arranged outside the rotor
30
, includes a yoke
22
having a cylindrical structure opened at upper and lower end thereof, six poles
24
protruded from the inner surface of the yoke
22
toward the rotor
30
while being uniformly spaced apart from one another in a circumferential direction, and field coils
26
respectively wound on the protruded poles
24
, and adapted to receive current from the driving circuit
10
.
The rotor
30
includes a laminated core
34
having six poles
32
protruded from the outer inner surface of the core
34
while being uniformly spaced apart from one another in a circumferential direction. A rotating shaft
12
is axially mounted to the central portion of the rotor
30
so that it rotates along with the rotor
30
, thereby externally transmitting the driving force of the motor.
The driving circuit
10
receives information about the position and speed of the rotor
30
, and controls the intensity of current flowing through the field coils
26
based on the received information.
In the conventional single-phase switched reluctance motor having the above mentioned configuration, when current is supplied from the driving circuit
10
to the field coils
26
, a reluctance torque is generated between the stator
20
and the rotor
30
, thereby causing the rotor
30
to rotate in a direction exhibiting a minimum magnetic resistance.
Meanwhile, in the conventional single-phase switched reluctance motor, auxiliary coils (not shown) are wound on respective protruded poles
24
of the stator
20
in order to allow the rotating shaft
12
to always rotate in an effective rotating direction. When the current supplied from the driving circuit
10
is cut off, each protruded pole
32
of the rotor
30
is positioned within an effective torque generating region formed by an associated one of the protruded poles
24
of the stator
20
, thereby allowing the rotor
30
to be initially driven in the effective rotating direction.
Accordingly, the conventional single-phase motor should use the additional device having a complex structure for its initial driving operation and subsequent operations. For this reason, the conventional single-phase motor has a low utility.
Furthermore, the conventional single-phase motor should use an optical sensor or Hall sensor (not shown) in order to acquire the information about the position and speed of the rotor required during the operation of the motor.
SUMMARY OF THE INVENTION
The present invention has been made in view of the problems involved with the Prior art, and an object of the invention is to provide a single-phase motor which can simply achieve the setting of the initial driving position of its rotor while simply implementing means for acquiring information about the position and speed of the rotor required for the operation of the motor, so that it has a high utility.
In accordance with the present invention, this object is accomplished by providing a single-phase motor comprising: a stator; a rotor adapted to rotate when electric power is applied to the stator; a ring-shaped magnet installed to rotate along with the rotor; a parking magnet for stopping the rotor within an effective torque generating region by a magnetic force effected between the ring-shaped magnet and the parking magnet upon braking the rotor, and a sensor unit for sensing a variation in the intensity of a magnetic field generated around the ring-shaped magnet during the rotation of the rotor, thereby sensing a position and speed of the rotor.


REFERENCES:
patent: 6091170 (2000-07-01), Mayes et al.
patent: 6424114 (2002-07-01), Komatsu
patent: BG2169755 (1986-07-01), None

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