Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
2001-09-28
2004-07-06
Mullins, Burton S. (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C310S049030
Reexamination Certificate
active
06759786
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a stator of a brushless direct current motor and a method for making it, wherein the stator of the brushless direct current motor may be processed and manufactured conveniently.
2. Description of the Related Art
A conventional stator combination structure of a miniature heat-sink fan in accordance with the prior art shown in
FIG. 1
comprises a stator coil
90
, upper and lower pole plates
91
and
92
, a circuit board
93
, and a housing
94
. A metallic shaft tube
95
having a proper outer diameter passes through central holes of the stator coil
90
, the upper and lower pole plates
91
and
92
, and the circuit board
93
, so that they are combined integrally. Then, the bottom of the metallic shaft tube
95
is pressed in the central column hole
96
of the housing
94
. The outer diameter of the metallic shaft tube
95
is provided with multiple sections, and has a top end formed with an annular lip
951
, a mediate portion formed with an enlarged diameter portion
952
, and a bottom
953
. The stator coil
90
is provided with a central hole having a diameter slightly greater than the outer diameter of the enlarged diameter portion
952
of the metallic shaft tube
95
. The upper pole plate
91
is provided with a central hole having a diameter slightly smaller than the outer diameter of the annular lip
951
of the metallic shaft tube
95
. The lower pole plate
92
is provided with a central hole having a diameter slightly smaller than the outer diameter of the bottom
953
of the metallic shaft tube
95
. The circuit board
93
is provided with a central hole having a diameter slightly smaller than the outer diameter of the bottom
953
of the metallic shaft tube
95
. The upper pole plate
91
is pressed on the annular lip
951
of the metallic shaft tube
95
in a forcibly press manner. Then, the stator coil
90
is mounted on the enlarged diameter portion
952
of the metallic shaft tube
95
through the bottom
953
of the metallic shaft tube
95
. Then, the lower pole plate
92
and the circuit board
93
are pressed on the bottom
953
of the metallic shaft tube
95
, so that the stator coil
90
is clamped by the upper and lower pole plates
91
and
92
to be fixed on the enlarged diameter portion
952
of the metallic shaft tube
95
by the diameter difference of the outer diameter of the metallic shaft tube
95
. The outer diameter of the bottom
953
of the metallic shaft tube
95
is slightly greater than the inner diameter of the central column hole
96
of the housing
94
.
In such a stator of the conventional brushless direct current motor, the metallic shaft tube
95
needs to be formed with three sections of different diameters, and the upper and lower pole plates
91
and
92
and the circuit board
93
need to be respectively formed with an inner hole whose inner diameter forms a proper tolerance with the outer diameter of the metallic shaft tube
95
. Thus, fabrication of the stator is more inconvenience. In addition, the upper and lower pole plates
91
and
92
each only have a smaller thickness. Thus, the sensing area of the upper and lower pole plates
91
and
92
and the rotor is reduced relatively. Thus, the stator cannot enhance the rotational torque of the rotor.
The stator structure of another conventional brushless direct current motor in accordance with the prior art shown in
FIG. 2
comprises a stator
80
wound with a coil
803
. The upper and lower ends of the stator
80
are provided with columns
801
and
802
for combining and positioning the upper and lower pole plates
81
and
82
and the circuit board
83
. A metallic shaft tube
84
whose outer diameter is greater than the diameter of the central holes respectively provided by the stator
80
, the upper and lower pole plates
81
and
82
and the circuit board
83
, may be pressed into the central holes in a forcibly press manner. The metallic shaft tube
84
has a protruding annular lip
841
to prevent detachment, and the rotation shaft
851
of the rotor
85
may be pivoted on the metallic shaft tube
84
to rotate. In such a stator of the conventional brushless direct current motor, the fabrication also uses the difference of the larger and the smaller diameters to combine in a forcibly press manner, and also needs combination of the columns
801
and
802
provided by the upper and lower ends of the stator
80
with the upper and lower pole plates
81
and
82
and the circuit board
83
. Thus, the fabrication of the stator is more inconvenience. In addition, the upper and lower pole plates
81
and
82
each only have a smaller thickness. Thus, the sensing area of the upper and lower pole plates
81
and
82
and the annular permanent magnet
852
of the rotor
85
is small. Thus, the stator cannot enhance the rotational torque of the rotor.
SUMMARY OF THE INVENTION
The primary objective of the present invention is to provide a method for making a stator of a brushless direct current motor, wherein the stator may be processed and manufactured conveniently.
A secondary objective of the present invention is to provide a stator of a brushless direct current motor, wherein the upper and lower pole plates of the stator and the annular permanent magnet of the rotor may have a larger sensing area, and have a larger magnetically conducting passage. Thus, the stator may enhance the rotational torque of the rotor.
In accordance with the present invention, there is provided a method for making a stator of a brushless direct current motor, includes the steps of: winding a coil set to predetermined turns, thereby forming a ring body having a central hole, and performing an insulation process; mounting at least two pole plates on two end faces of the coil set respectively, the pole face and the magnetically conducting plates of each pole plate encompassing the inner and outer periphery of the coil set respectively, and a wiring head of the coil set being drawn outside of the pole plate; and mounting a combination member on the magnetically conducting rings (or plates) of each pole plate, thereby forming a stator. The pole faces of each pole plate may be induced with the permanent magnet of the rotor.
Further benefits and advantages of the present invention will become apparent after a careful reading of the detailed description with appropriate reference to the accompanying drawings.
REFERENCES:
patent: 4244099 (1981-01-01), Haydon
patent: 4381465 (1983-04-01), Renkl et al.
patent: 4891567 (1990-01-01), Fujitani et al.
patent: 4987331 (1991-01-01), Horng
patent: 5847485 (1998-12-01), Suzuki et al.
patent: 5917262 (1999-06-01), Huang et al.
patent: 5945765 (1999-08-01), Chen
patent: 6441531 (2002-08-01), Horng et al.
patent: 6466119 (2002-10-01), Drew
Hong Ching-Shen
Horng Alex
Bacon & Thomas PLLC
Jones Judson H.
Mullins Burton S.
Sunonwealth Electric Machine Industry Co. Ltd.
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