Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
2002-04-17
2004-04-27
Mullins, Burton (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C310S06700R, C310S051000
Reexamination Certificate
active
06727626
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a balancing plate for a motor. In particular, the present invention relates to a balancing plate having at least two induction edges, each induction edge having an arc length that mates with a length of one of plural poles of the annular permanent magnet on a rotor, thereby allowing stable rotation of the motor and allowing easy restarting of the motor by means of preventing the rotor from being locked by excessive magnetic attractive force between the respective induction edge and the permanent magnet.
2. Description of the Related Art
FIG. 1
of the drawings illustrates a motor and a conventional balancing plate therefore.
FIG. 2
is a plan view of the motor and the balancing plate after assembly. As illustrated in
FIGS. 1 and 2
, the conventional motor
1
comprises a rotor
10
, a stator
2
, a balancing plate
30
, and a circuit board
40
that are assembled along an axial direction to thereby form the motor. The balancing plate
30
includes an axial hole
31
and a plurality of induction edges
32
each having a predetermined arc length a. The induction edges
32
are preferably sector-like and diametrically, symmetrically arranged. The rotor
10
has a permanent magnet
11
that is radially spaced from the silicon steel plates
21
of the stator
20
. The rotor
10
is driven by alternating magnetic fields generated by the silicon steel plates
21
. The balancing plate
30
is located on the permanent magnet side of the rotor
10
such that the balancing plate
30
and the permanent magnet
11
of the rotor
10
always have an induction force therebetween regardless of the fact that the motor
1
is turning or stopped, thereby providing an appropriate inductive magnetic force to the rotor
10
. In fact, the inductive magnetic force provided by the induction edges
32
of the balancing plate
30
is a downward, attractive balancing force, which is also a damping force in a way. Namely, the damping force will reduce the rotational efficiency. When the arc length a of the respective induction edge
32
of the balancing plate
30
is too long; namely, the arc length a of the respective induction edge
32
of the balancing plate
30
is greater than the length of the respective pole of the annular permanent magnet
11
of the rotor
10
, an excessive inductive magnetic force is generated between the balancing plate
30
and the rotor
10
, resulting a decrease in the rotational efficiency of the motor. Further, when the motor
1
is stopped, restarting of the motor
1
would not be easy in view of the excessive inductive magnetic force generated between the balancing plate
30
and the rotor
10
. If the arc length a of the respective induction edge
32
of the balancing plate
30
is too short, the balancing force is insufficient for the rotor
10
such that the rotor
10
would “wobble” and “float” during rotation. Therefore, the arc length a of the respective induction edge
32
of the balancing plate
30
needs to be redesigned so as to provide the rotor
10
with sufficient balancing force and to allow easy restarting of the motor
1
.
SUMMARY OF THE INVENTION
It is the primary object of the present invention to provide a balancing plate having at least two induction edges, each induction edge having an arc length that is equal to or less than a length of one of plural poles of the annular permanent magnet on a rotor. Thus, the arc length of the respective induction edge mates with the length of the respective pole of the annular permanent magnet, thereby avoiding generation of excessive inductive magnetic force and allowing easy restarting of the motor.
It is the secondary object of the present invention to provide a balancing plate having at least two induction edges, each induction edge having an arc length that is equal to or less than a length of one of plural poles of the annular permanent magnet on a rotor. Thus, the arc length of the respective induction edge mates with the length of the respective pole of the annular permanent magnet, thereby providing sufficient inductive magnetic force and allowing stable rotation of the motor.
A balancing plate in accordance with the present invention is to be assembled with a rotor, a stator, and a circuit board to form a motor. The balancing plate comprises an axial hole for engagement with a stator and at least two induction edges symmetrically arranged with respect to the axial hole. Each induction edge includes an arc length that is not greater than a length of one of plural poles of an annular permanent magnet of a rotor. When the motor rests, the induction edges of the balancing plate face at least two of the poles of the annular permanent magnet having the same polarity, forming a mating therebetween to thereby allow easy restarting of the motor.
Other objects, specific advantages, and novel features of the invention will become more apparent from the following detailed description and preferable embodiments when taken in conjunction with the accompanying drawings.
REFERENCES:
patent: 4728833 (1988-03-01), Shiraki et al.
patent: 5355373 (1994-10-01), Salmon et al.
patent: 5679997 (1997-10-01), Matsuzawa et al.
patent: 5808390 (1998-09-01), Miyazawa et al.
patent: 6291916 (2001-09-01), Huang et al.
patent: 6400053 (2002-06-01), Horng
patent: 2-214455 (1990-08-01), None
patent: 2001-86720 (2001-03-01), None
patent: 2001-258185 (2001-09-01), None
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