Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
2001-02-12
2003-09-09
Le, Dang (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C310S06700R, C310S089000, C310S06800R, C310S071000
Reexamination Certificate
active
06617719
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates in general to brushless motors and more particularly to brushless motors of a type which exhibits a satisfied heat proof performance and is easy to be assembled.
2. Description of the Prior Art
In order to clarify the task of the present invention, two conventional brushless motors will be briefly described with reference to
FIGS. 16 and 17
of the accompanying drawings.
In
FIG. 16
, there is shown one conventional brushless motor
100
. The motor
100
comprises a drive circuit
102
for driving a motor shaft
104
. The drive circuit
102
generally comprises a filter section which filters out surges from a supplied electric power, a switching section which switches the path of the current from the filter section toward a stator
106
thereby to vary the magnetic fields generated by the stator
106
and a control section which controls rotation of the motor shaft
104
by controlling the switching timing of the switching section. These sections of the drive circuit
102
are all arranged on a circuit substrate
108
. The circuit substrate
108
is accommodated in a circuit protection case
110
.
The switching section comprises a plurality of switching elements
112
which switch the path of current directed to coils
114
of the stator
106
, and the control section comprises electronic parts
107
which control the switching timing of the switching elements
112
. Since the switching elements
112
produce a considerable amount of heat under operation, these elements
112
are attached to a heat sink
115
which is formed with a plurality of heat radiation fins
116
. That is, under operation of the motor
100
, the heat generated by the switching elements
112
is transmitted to the heat sink
115
and released to the open air by the heat radiation fins
116
.
However, hitherto, it has been difficult to effectively release the heat of the switching elements
112
to the open air. In fact, if the motor
100
is designed to generate a higher output, the switching elements
112
are forced to generate a marked heat inevitably and thus it becomes necessary to use high heat-proof and thus expensive ones as the electronic parts
107
of the control section of the drive circuit
102
.
In
FIG. 17
, there is shown the other conventional brushless motor
200
which is shown in Laid-open Japanese Patent Publication 9-191625. The motor
200
comprises a drive circuit
202
for driving a motor shaft
204
. The drive circuit
202
is accommodated in a circuit protection case
210
. The drive circuit
202
is printed on a circuit substrate
212
, and generally comprises a filter section
202
a
which filters our surges from a supplied power, and a control section
202
b
which controls magnetic fields of a stator
214
by switching the path of the current from the filter section
202
a
at given intervals. The control section
202
b
comprises a plurality of switching elements
216
which switch the path of current directed to coils
214
a
of the stator
214
. The switching elements
216
are attached to a heat sink
218
formed with a plurality of heat radiation fins
218
a.
Thus, under operation of the motor
200
, the heat generated by the switching elements
216
is transmitted to the heat sink
218
and released to the open air from the heat radiation fins
218
a.
The coils
214
a
of the stator
214
and the control section
202
b
of the drive circuit
202
are connected through terminal pins
220
which extend from the coils
214
a
to bus bars
224
which, in turn are connected to joint bars
222
held by the circuit substrate
212
.
However, employment of the terminal pins
220
, joint bars
222
and bus bars
224
for connecting the control section
202
b
to the coils
214
a
has caused a troublesome and time-consuming work for assembling the motor
200
. For example, for welding given portions of the bus bars
224
to the joint bars
222
and the terminal pins
220
, it is necessary to precisely hold the bus bars
224
at given positions before carrying out the welding work.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a brushless motor which is free of the above-mentioned drawbacks.
According to the present invention, there is provided a brushless motor which is constructed to suppress or at least minimize undesired heat transmission from a heat generating switching section of a drive circuit to a control section of the same.
According to the present invention, there is further provided a brushless motor which is easily assembled.
According to the present invention, there is provided a brushless motor which comprises a circuit protecting case; a holder disposed on the case; a motor shaft rotatably held by the holder; a stator disposed about the holder, the stator including a plurality of coils which surround the motor shaft; a yoke fixed to the motor shaft to rotate therewith, the yoke covering the stator with a given space therebetween; permanent magnets held by the yoke; a circuit substrate tightly held in the circuit protecting case; a drive circuit arranged on the circuit substrate, the drive circuit including a switching section which switches the path of current directed to the coils of the stator and a control section which controls a switching timing of the switching section, the switching section including a plurality of switching elements which generate a certain heat when operated; and a partition wall provided in the circuit protection case to partition the interior of the case into a first chamber to which the switching elements of the switching section are exposed and a second chamber to which the control section is exposed.
REFERENCES:
patent: 5691584 (1997-11-01), Toida et al.
patent: 5969445 (1999-10-01), Horiuchi et al.
patent: 6107708 (2000-08-01), Yamaguchi et al.
patent: 6107716 (2000-08-01), Penketh
patent: 6229226 (2001-05-01), Kramer et al.
patent: 6236126 (2001-05-01), Yagi et al.
patent: 6278207 (2001-08-01), Matsumoto
patent: 6297572 (2001-10-01), Sunaga et al.
patent: 9-191625 (1997-07-01), None
Asayama Yoshinori
Kawarai Hiromi
Machida Katsuhiro
Ohba Takeshi
Sunaga Hideki
Calsonic Kansei Corporation
Foley & Lardner
Le Dang
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