U.S. patent application number 10/836362 was filed with the patent office on 2004-11-25 for electric blower and electric apparatus equipped therewith.
This patent application is currently assigned to Toshiba Tec Kabushiki Kaisha. Invention is credited to Kushida, Hiroyuki, Sakurai, Osamu.
Application Number | 20040231090 10/836362 |
Document ID | / |
Family ID | 33100433 |
Filed Date | 2004-11-25 |
United States Patent
Application |
20040231090 |
Kind Code |
A1 |
Kushida, Hiroyuki ; et
al. |
November 25, 2004 |
Electric blower and electric apparatus equipped therewith
Abstract
By arranging a power device or devices on the outer face of a
partition wall such as a linking portion (flange portion)
constituting a flow passage between the exhaust port of a
centrifugal fan and a motor, the power device or devices can be
efficiently cooled without disturbing the air flow in an air
channel within a case and without increasing in pressure loss of
the air channel. Moreover, the power device or devices are not
affected by heat from the motor since they are positioned farther
upstream than the motor, in the air flow from the centrifugal
fan.
Inventors: |
Kushida, Hiroyuki;
(Odawara-shi, JP) ; Sakurai, Osamu; (Isehara-shi,
JP) |
Correspondence
Address: |
FRISHAUF, HOLTZ, GOODMAN & CHICK, PC
767 THIRD AVENUE
25TH FLOOR
NEW YORK
NY
10017-2023
US
|
Assignee: |
Toshiba Tec Kabushiki
Kaisha
Tokyo
JP
|
Family ID: |
33100433 |
Appl. No.: |
10/836362 |
Filed: |
April 29, 2004 |
Current U.S.
Class: |
15/326 |
Current CPC
Class: |
F04D 25/06 20130101;
F04D 29/5813 20130101; A47L 9/22 20130101; F04D 29/5853 20130101;
A47L 5/22 20130101 |
Class at
Publication: |
015/326 |
International
Class: |
A47L 005/00 |
Foreign Application Data
Date |
Code |
Application Number |
May 20, 2003 |
JP |
2003-141344 |
Jul 25, 2003 |
JP |
2003-201695 |
Claims
What is claimed is:
1. An electric blower, comprising: a motor having a rotation shaft;
a centrifugal fan fitted to the rotation shaft of the motor, the
fan having an exhaust port; a case for housing the motor and the
centrifugal fan, the case including a partition wall constituting
an air channel between the exhaust port of the centrifugal fan and
the motor; and a drive circuit including a power device for driving
the motor, wherein the power device is fixed on the outer surface
of the partition wall.
2. An electric blower according to claim 1, wherein the case
comprises a motor case for housing the motor, and a fan cover
covering the centrifugal fan, the fan cover having an outer
circumferential wall greater in width than that of the motor case,
the partition wall including a linking portion interposing between
the outer circumferential wall of the motor case and the outer
circumferential wall of the fan cover, wherein the power device is
fixed on the linking portion of the partition wall.
3. An electric blower according to claim 2, wherein the motor case
includes a cylindrical wall and a flange formed at the edge of the
cylindrical wall, the flange acting as the linking portion.
4. An electric blower according to claim 2, wherein the linking
portion includes an outer ring shaped plate portion on which the
power device is fixed and an inner disk shaped plate portion
integrally extending from the inner edge of the outer ring shaped
plate portion, the inner disk shaped plate portion having an
opening through which air from the exhaust port of the centrifugal
fan flows to the motor case.
5. An electric blower according to claim 1 further comprising a
diffuser located between the centrifugal fan and the motor for
rectifying an air flow from the exhaust port of the centrifugal fan
toward the motor, the diffuser being opposite to the partition
wall, wherein the power device is fixed on a portion of the
partition wall opposite to the diffuser.
6. An electric blower according to claim 1, wherein a cooling
opening is formed on the case in the vicinity of the power
device.
7. An electric blower according to claim 1, wherein the motor is a
brushless motor and the drive circuit includes a plurality of the
power devices on the partition wall arranged radially on
substantially the same circle around the rotation shaft.
8. An electric apparatus for causing air flow, comprising: an
electric blower including; a motor having a rotation shaft; a
centrifugal fan fitted to the rotation shaft of the motor, the fan
having an exhaust port; a case for housing the motor and the
centrifugal fan, the case including a partition wall constituting
an air channel between the exhaust port of the centrifugal fan and
the motor; and a drive circuit including a power device for driving
the motor, wherein the power device is fixed on the outer surface
of the partition wall.
9. An electric apparatus comprising: an electric blower including;
a motor having a rotation shaft; a centrifugal fan fitted to the
rotation shaft of the motor, a case for housing the motor and the
centrifugal fan, the case having a fan cover for covering the fan,
a motor case for housing the motor, and a partition wall being
located between the fan cover and the motor case for constituting
an air channel from the fan to the motor, the fan cover having an
outer circumferential wall greater in width than that of the motor
case; a drive circuit including a power device for driving the
motor; a blower chamber having a wall for housing the electric
blower; and a supporter located between the wall of the blower
chamber and the outer circumferential wall of the fan cover for
supporting the electric blower, wherein the power device is fixed
on the outer surface of the partition wall.
10. An electric apparatus according to claim 9, wherein the
supporter is made of a vibration absorbing material.
11. An electric apparatus according to claim 9, wherein the
supporter is made of thermally insulating material.
12. An electric apparatus according to claim 9, wherein the
supporter is made of a heat resisting material.
Description
BACKGROUND OF THE INVENTION
[0001] This application is based upon and claims the benefit of
priority from the prior Japanese Applications No. 2003-1413441
filed on May 20, 2003, and No. 2003-201695, filed on Jul. 25, 2003,
the entire contents of which are incorporated herein by
reference.
FIELD OF THE INVENTION
[0002] The present invention relates, in general, to an electric
blower and an electric apparatus equipped with this electric
blower, such as a vacuum cleaner. In particular, the invention
relates to an electric blower which is equipped with a switching
element for controlling the operation of the blower.
DISCUSSION OF THE BACKGROUND
[0003] FIG. 1 of the Japanese Patent Laid-Open No. Hei 6 (1994)
26494 shows an example in which a switching element is mounted in a
close contact on the outer circumferential wall of a motor case
facing a space formed by a step portion between the outer
circumferential wall of the motor case and the outer
circumferential wall of a fan case.
[0004] In the above-described construction, as the switching
element is fitted to the outer circumferential wall of the motor
case close to the stator, the switching element is significantly
affected by heat emitted from the stator, and the cooling effect is
therefore poor. This problem is especially serious in motors such
as brushless motors equipped with a plurality of power devices that
require cooling.
[0005] FIG. 3 of the Japanese Patent Laid-Open No. Hei 6 (1994)
261847 shows an example in which a package including a
control/drive integrated circuit board is fixed on a case in the
area closer to the fan than the partition plate where air from a
diffuser directly hits in a position.
[0006] In the electric blower shown in FIG. 3, the package
including a control/drive integrated circuit board is arranged in
an air channel between the fan and the motor. However, the
arrangement of the package located in the air channel increases
pressure loss of the channel and, therefore lowers the efficiency
of the electric blower. In motors such as brushless motor equipped
with a plurality of power devices that require cooling, the
internal channel is more complex, causing even greater pressure
loss of the channel.
SUMMARY OF THE INVENTION
[0007] Therefore, an object of the present invention is to enable
power devices such as switching elements to be efficiently cooled
without causing increase in pressure loss of the air channel.
[0008] This object can be achieved by a novel electric blower of
the invention.
[0009] Therefore, in the novel electric blower, a case for housing
the motor and a centrifugal fan fitted to a rotation shaft of the
motor is provided, and a power device or devices provided in a
drive circuit to drive the motor are arranged on an outer surface
of a partition wall constituting an air channel between the exhaust
port of the centrifugal fan and the motor.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] A more complete appreciation of the present invention and
many of the attendant advantages thereof will be readily obtained
as the same becomes better understood by reference to the following
detailed description when considered in connection with the
accompanying drawings, wherein:
[0011] FIG. 1 is a partial cut-out profile of the configuration of
an electric blower as a first preferred embodiment of the
invention;
[0012] FIG. 2 is a plan of an example of the internal configuration
thereof;
[0013] FIG. 3A is a schematic diagram showing for a form of a
centrifugal fan;
[0014] FIG. 3B is a schematic diagram showing for a partial form of
a centrifugal fan;
[0015] FIG. 4A is a plan of an example of a configuration of a
diffuser;
[0016] FIG. 4B shows a bottom view of the example of a
configuration of the diffuser;
[0017] FIG. 5 is a schematic circuit diagram of the drive circuit
of the electric blower;
[0018] FIG. 6 is a partial cut-out profile of the configuration of
an electric blower as a variation of the first embodiment;
[0019] FIG. 7 is a plan of a variation of the electric blower;
[0020] FIG. 8 is a partial cut-out profile of the configuration of
an electric blower as a second preferred embodiment of the
invention;
[0021] FIG. 9 is a plan of an example of an internal configuration
thereof;
[0022] FIG. 10 is a partial cut-out profile of the configuration of
an electric blower as a third preferred embodiment of the
invention;
[0023] FIG. 11 is a plan of an example of an internal configuration
thereof;
[0024] FIG. 12 is a schematic circuit diagram of the drive circuit
of the electric blower;
[0025] FIG. 13 shows a perspective view of an external
configuration of a vacuum cleaner as a fourth preferred embodiment
of the invention;
[0026] FIG. 14 is a vertical cut profile of an example of the
internal configuration thereof;
[0027] FIG. 15 is a partial cut-out profile of the configuration of
the electric blower included in the vacuum cleaner;
[0028] FIG. 16 is a partial cut-out profile of the configuration of
an electric blower as a fifth preferred embodiment of the
invention; and
[0029] FIG. 17 is a partial plan of an example of the internal
configuration of an electric blower as a sixth preferred embodiment
of the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0030] A first preferred embodiment of the present invention will
be described below with reference to FIG. 1 through FIG. 5.
[0031] An electric blower 1 is basically comprised of a motor 2, a
centrifugal fan 4 fitted to a rotor shaft 3 of this motor 2, and a
case 5 for housing the motor 2 and centrifugal fan 4.
[0032] The motor 2 in this embodiment is a motor with brush, housed
in a cylindrical shaped motor case 6. The front end of this motor
case 6 constitutes an opening 7, and a long planar bracket 8
bridges over this motor case 6 in the diametric direction of the
motor case 6, fitted with screws 9 so as to cover part of the
opening 7. The opening 7 not covered by the bracket 8 therefore
forms an air flow opening 10. Approximately at the center of the
bracket 8 a bearing housing 13a is arranged to protrude forward
(towards the centrifugal fan 4) in a substantially cylindrical
shape. A bearing 11a is housed on the inner circumferential side of
this bearing housing 13a. A through hole 12 for the rotor shaft 3
is formed at the center of the bearing housing 13a.
[0033] The centrifugal fan 4 comprises a main disk plate 322, a
side disk plate 323 and a plurality of vanes 324. Each vane 324 has
a plurality of ear portions 325, which are respectively fit and
fastened up in their corresponding holes 326 formed in the main
disk plate 322 and the side disk plate 323. Thus, vanes 324 are
respectively fixed in a sandwiched manner between the main disk
plate 322 and the side disk plate 323. An inlet 17 is formed at a
center of the side disk plate 323 and exhaust ports 22
communicating to the inlet 17 along vanes 324 respectively are
formed between a circumferential edge of the main disk plate 322
and that of the side disk plate 323.
[0034] A diffuser 14 is fixed to a forward side of the bracket 8.
Farther ahead of this diffuser 4, the centrifugal fan 4 is
arranged. Onto the outer circumferential portion of the motor case
6 is snapped (connected) a fan cover 15. This fan cover 15 covers
the centrifugal fan 4 and the diffuser 14. This fan cover 15 has an
intake opening 16, which is located opposite to the inlet 17 of the
centrifugal fan 4, at the center of its front side and a rear
opening (not shown) at the entire rear side. And the fan cover 15
is formed substantially as a cylindrical shape. These motor case 6
and fan cover 15 comprise the case 5. The fan cover 15 here is
formed to have a larger outer circumferential wall than that of the
motor case 6 in the centrifugal direction. The upper end of an
outer circumferential wall of the motor case 6 (the upward
direction being toward the fan cover 15 as viewed from the motor
case 6) and the lower end of that of the fan cover 15 are connected
through a linking portion 18.
[0035] On the circumferential wall near the rear side of the motor
case 6, an air outlet (not shown) is opened, positioned in the
radial direction. The rear side of the motor case 6 in the axial
direction is sealed by a rear plate 21. The central part of this
rear plate 21 protrudes backward in a substantially cylindrical
shape to constitute a bearing housing 13b. A bearing 11b is housed
in this bearing housing 13b.
[0036] On the other hand, the motor 2 is configured of a stator 19
fixed to the motor case 6 and a rotor 20 arranged inside this
stator 19. Both ends of the rotor shaft 3 at the center of the
rotor 20 are rotatably supported by the bearings 11a and 11b.
[0037] An example of configuration of the diffuser 14 will now be
described with reference to FIG. 4. As shown in FIGS. 4A and 4B,
the diffuser 14 comprises: a substantially circular disk plate 81;
a through hole 82, through which the rotor shaft 3 rotatably
penetrates, formed substantially at the center of this disk plate
81; screw holes 83a and 83b for fixing the disk plate 81 to the
bracket 8; a plurality of arcuate blades 84 erected on the
circumferential area of the front surface of the disk plate 81 so
as to be positioned outside of the circumferential edge of the
centrifugal fan 4; and a plurality of arcuate blades 85 erected in
a volute shape on the rear surface of the disk plate 81. The
diffuser 14 having the above-described construction is located
opposite to the linking portion 18 of the case 5, and secured to
the bracket 8 with screws. The rotor shaft 3 penetrates the through
hole 82 of the disk plate 81 and is supported by the bracket 8.
[0038] In this configuration, when the rotor shaft 3 rotates, the
centrifugal fan 4 rotates integrally with that rotation. This
rotation causes flow of air to pass the centrifugal fan 4 from the
intake opening 16 opened at the front face of the fan cover 15 to
exhaust port 22. Air from the exhaust port 22 flows between the
arcuate blades 84 along the inner circumferential face of the fan
cover 15 toward the rear side of the disk plate 81. The air further
flows between the arcuate blades 85 in a volute manner along the
rear surface of the disk plate 81 toward the center of the diffuser
14. The diffuser 14 in this way uniformly rectifies the air
discharged from the exhaust port 22 of the centrifugal fan 4 and
guides the air to the motor 2.
[0039] On the other hand, the electric blower 1 is connected to a
commercial A.C. power source via a switching element 23 for
controlling electric power to the motor 2 as shown in FIG. 5. A
control terminal of this switching element 23 is connected with an
electric blower control unit 26 consisting of a microcomputer 25
and the like. The electric blower control unit 26 is mounted on a
circuit board 27 and terminals of the switching element 23 are
connected with wired patterns on it. This electric blower control
unit 26 is further connected with an operating unit 28 for starting
and stopping power, or selecting from a plurality of different
electric powers (Strong, Regular and Weak) a desirable power
supplied to the electric blower 1. The switching element 23 and the
electric blower control unit 26 in this way constitute a drive
circuit 27a.
[0040] In the configuration of this embodiment of the invention, a
body of the switching element 23 contained in the drive circuit 27a
as a power device is arranged on the outside of a partition wall
29a forming an air channel 29 between the exhaust port 22 of the
centrifugal fan 4 and the motor 2, and secured by a screw 30.
[0041] The partition wall 29a is a wall forming the channel 19
between the exhaust port 22 of the centrifugal fan 4 and the upper
end of the motor 2 in the electric blower 1 and separating air
flowing through the air channel 29 from an outside air. In this
electric blower 1, part of an outer circumferential wall 15a of fan
cover 15 and part of an outer circumferential wall 6a of motor case
6 constitute the partition wall 29a.
[0042] Accordingly, air flowing through the air channel 29 is in no
way disturbed by the switching element 23 controlling electric
power to the motor 2.
[0043] It is therefore possible to release heat caused by the
switching element 23 to the case 5 without increase in pressure
loss of the air channel 29 of the electric blower 1. Also, as the
partition wall 29a where the switching element 23 is fixed is
located in a farther upstream position than the motor 2 in the air
flow direction from the centrifugal fan 4, it is little affected by
heat caused by the motor 2. Moreover, during the operation of the
electric blower 1, temperature of the air flowing through the
channel 29 in the partition wall 29a on which the switching element
23 is arranged is lower than that of the downstream side of the
motor 2 because the partition wall 88 is located at the upstream
side from the motor 2.
[0044] In this embodiment, the case 5 comprises the motor case 6
and the fan cover 15, and this fan cover 15 has an outer
circumferential wall 15a greater in diameter than an outer
circumferential wall 6a of the motor case 6. The partition wall 29a
includes the linking portion 18 which is interposed between the
outer circumferential wall 15a of the fan cover 15 and the outer
circumferential wall 6a of the motor case 6. And the switching
element 23 is fixed on the outside surface of the linking portion
18. Also, this type of linking portion 18 is a step portion created
by the difference in outer circumferential size between the fan
cover 15 and the motor case 6 in the centrifugal direction. It is
therefore structurally easy to form the linking portion 18 as a
planar portion. Since the switching element 23 can be mounted to
this type of plane in this structure, there is greater degree of
freedom in mounting of the switching element 23 compared with a
case where the switching element is mounted on the outer
circumferential surface of the motor case 6.
[0045] Further, this linking portion 18 also constitutes a region
opposite the diffuser 14 for rectifying the channel flow of the air
from the exhaust port 22 of the centrifugal fan 4 to the motor 2.
Experimental findings by the present inventor have also confirmed
the high cooling effect on the switching element 23 arranged in the
region opposite the diffuser 14.
[0046] Incidentally, in a specific example of a configuration of
this embodiment, the linking portion 18 in the case 5 is integrated
with the motor case 6, and is configured of a flange 31 formed by
bending the circumferential end portion of this cylindrical shaped
motor case 6 to protrude in the outer direction to have a
substantially L-shaped section. As the flange 31 can be easily
shaped flatly in this configuration, the switching element 23 can
be easily secured to the flange 31.
[0047] Now is shown a modification of this embodiment in FIG. 6 and
FIG. 7. In the first embodiment, the switching element 23 is
arranged on the outer surface of the flange 31 formed by a step
portion designed to make fixing easier and cooling more efficient.
However, if the emphasis is to be on efficient cooling without
being affected by heat generated by the stator 19, then the
switching element 23 can also be fixed on the outer surface of the
electric blower 1 in a position closer to the intake opening 16
than the motor 2 and opposite the diffuser 14, for instance on the
outer surface of the outer circumferential wall 15a of the fan
cover 15 as shown in FIG. 6 and FIG. 7.
[0048] A second preferred embodiment of the present invention will
now be described with reference to FIG. 8 and FIG. 9. The same or
similar constituent elements as those shown in the first embodiment
will be denoted respectively by the same reference numerals, and
their description is omitted (this also applies to subsequent
embodiments).
[0049] While this embodiment is basically similar to the first
embodiment, this embodiment uses a motor case 32 in place of the
motor case 6. The motor case 32 in this embodiment is a bottomed
structure using a rear plate portion 33, whose fan cover 15 side
opens as an opening 34 to house the motor 2. A disk-shaped frame 35
larger than the motor case 32 in outer circumference is fitted to
the motor case 32 with screws 36 so as to cover the opening 34 of
the motor case 32. Further, the outer circumferential wall 15a of
the fan cover 15 is secured tightly by a pressure fitting or the
like to an outer circumferential edge 87 of the disk-shaped frame
35. The motor case 32 and the fan cover 15 are integrally affixed
to each other. The disk-shaped frame 35 is therefore interposed
between the motor case 32 and the fan cover 15. This disk-shaped
frame 35 has an outer ring shaped plate portion 35a acting as the
linking portion 18 and an inner disk shaped plate portion 35b
integrally extending from the inner edge of the outer ring shaped
plate portion 35a, as shown in FIG. 8.
[0050] Further a plurality of openings 37, which are shaped like a
fan as shown in FIG. 9 for instance, are formed in the inner disk
shaped plate portion 39 to flow the air from the exhaust port 22 of
the centrifugal fan 4 to the motor 2. These openings 37 are
designed to secure a required rate of air for cooling the motor 2
according to the performance of the centrifugal fan 4. The bearing
housing 13a is formed at substantially the center of the
disk-shaped frame 35, protruding forward in a substantially
cylindrical shape. The bearing 11a is housed in the bearing housing
13a, and the through hole 12 for the rotor shaft 3 is formed at its
center.
[0051] In this configuration, the outer ring shaped plate portion
35a positioned outside the outer circumferential wall 6a of the
motor case 32 constitutes part of the partition wall 29a forming
the air channel 29 between the exhaust port 22 of the centrifugal
fan 4 and the motor 2, and which acts as the linking portion 18.
The switching element 23 is fixed on the outer surface of this
outer ring shaped plate portion 35a, and secured with the screw
30.
[0052] Therefore, also in this embodiment by utilizing the outer
ring shaped plate portion 35a of the disk-shaped frame 35, the same
functions and effects as in the first embodiment using the flange
31 can be achieved. Incidentally in this embodiment, the motor case
6, the fan cover 15 and the outer ring shaped plate portion 35a of
the disk-shaped frame 35 constitute the case 5.
[0053] In this configuration, the disk-shaped frame 35 of this
embodiment is comprised of part of the partition wall 88 that forms
the air channel 29 between the exhaust port 22 of the centrifugal
fan 4 and the upper end of the motor 2. Furthermore, the inner disk
shaped plate portion 35b is arranged in a position farther upstream
in the air flow direction than the motor 2 from which heat emits.
This arrangement results in increase in a surface area of the
disk-shaped frame 35 in contact with the air at the farther
upstream than the motor 2 and accordingly a cooling effect of the
disk-shaped frame 35 is enhanced. The switching element 23
therefore affixed integrally to this disk-shaped frame 35 is also
cooled more efficiently.
[0054] A third preferred embodiment of the invention will now be
described with reference to FIG. 10 through FIG. 12. While this
embodiment is basically similar to the first embodiment, this
embodiment applies the present invention to an electric blower 42
using a brushless motor 41 in place of the motor 2 with
brushes.
[0055] First will be described with reference to FIG. 12 an example
of configuration of a drive control system including a drive
circuit 27b for the brushless motor 41. The centrifugal fan 4 is
rotated by the brushless motor 41 which is driven by an inverter
circuit 44. The DC voltage is supplied to the inverter circuit 44
from a D.C. power supply unit 43. An electric blower control unit
45 for controlling the electric blower 42 is connected to drivers
46a through 46f, and controls the switching timing of switching
elements 47a through 47f, which are power devices such as power
MOSFET devices that constitute the inverter circuit 44. The
individual sections will be described in detail below.
[0056] The D.C. power supply unit 43 consists of a battery
combining a plurality of secondary cells, such as nickel cadmium
(NiCd) cells, nickel hydrogen cells or lithium ion cells, or is a
circuit which converts an A.C. voltage of a commercial A.C. power
supply into a D.C. voltage under rectifying and smoothing. This
D.C. voltage is supplied to the inverter circuit 44.
[0057] The inverter drive circuit 44 has a configuration in which
six switching elements 47a through 47f are connected in a
three-phase bridge structure. These switching elements 47a through
47f are driven by the high voltage side drivers 46a through 46c and
the low voltage side drivers 46d through 46f on the basis of pulse
signals supplied from the electric blower control unit 45 mainly
consisting of a microcomputer 48. They supply A.C. to the windings
49a through 49c of the electric blower 42.
[0058] The electric blower control unit 45 are connected with an
operating unit 50 for starting, stopping or selecting power to
supply to the electric blower 42, a current detecting means 51 for
detecting a current flowing to the inverter circuit 44, and an
input voltage detecting means 52 for detecting an input
voltage.
[0059] The electric blower control unit 45 is further connected
with a position detecting means 55 for detecting magnetic poles of
a rotor 54 surrounded by a stator 53. Three magnetic sensors
arranged at electrical angle intervals of 120.degree. are used as
this position detecting means 55. Hole sensors and hole ICs may
also be utilized as these magnetic sensors. Other methods for
detecting the magnetic poles include, though not shown, a method
using an optical pulse encoder and another method for detecting by
a voltage phase detecting means the voltages induced by the
windings 49a through 49c.
[0060] In this configuration, terminals of the plurality of
switching elements 47a through 47f, which are power devices, are
connected with wired patterns on a circuit board 56. And bodies of
the switching elements 47a through 47f are arranged on the outer
surface of the linking portion 18 of the partition wall 88 and
secured with the screws 30 or similar manners. Here, unlike the
case where there is only one switching element 23, the plurality of
switching elements 47a through 47f must be considered. These
switching elements 47a through 47f, as shown in FIG. 11 are
arranged on substantially the same circle around the rotor shaft 3
of the brushless motor 41 and radially arranged at nearly equal
intervals.
[0061] By using this structure for arranging the switching elements
47a through 47f, as in the case of the first embodiment described
above, the switching elements 47a through 47f can be effectively
cooled without increasing pressure loss of the channel 29 of the
electric blower 42. Since the drive circuit 27b of the brushless
motor 41 in this embodiment is in particular configured of a
plurality of switching elements 47a through 47f, this plurality of
switching elements 47a through 47f are effectively cooled without
increasing pressure loss of the channel 29 of the electric blower
42. This embodiment is therefore particularly effective.
Furthermore, since this plurality of switching elements 47a through
47f are radially arranged on substantially the same circumferential
region around the rotor shaft 3, the unevenly distributed cooling
of these switching elements 47a through 47f is reduced, and they
are uniformly cooled, resulting in an increased cooling effect. It
is therefore possible to stabilize the operation of the switching
elements 47a through 47 and accordingly the operation of all the
circuitry.
[0062] This embodiment has been described as an application of the
first embodiment and the second embodiment can also be applied
using the disk-shaped frame 35.
[0063] Further, the motor cases 6 and 32 in these embodiments are
supposed to have bottomed structures for blocking, their rear plate
21 and 33 may also be blocked using separate members.
[0064] These embodiments were described using examples in which the
switching element 23 or elements 47a through 47f, such as Triac
switches or power MOSFETs were used as a power device or devices.
And, the present invention is not limited to these elements and is
applicable to devices that emit heat during drive operation such as
switching elements using insulated gate bipolar transistors
(IGBTs). These elements can be used not only discretely but also in
a packaged form or integrated into a device.
[0065] A fourth preferred embodiment of the invention will now be
described with reference to FIG. 13 through FIG. 15. This
embodiment is an application of the electric blower 1 or 42 of any
of the configurations described above for a vacuum cleaner, which
is particularly suitable. The other applications are kitchen
equipments or electric tools, for example food processors or power
drills.
[0066] A vacuum cleaner 61 as the present embodiment, is mounted
with the electric blower 1.
[0067] The vacuum cleaner 61 is mainly configured of a cleaner body
62 which constitutes the basic constituent of the vacuum cleaner
61, a hose 63 one of whose ends is detachably connected to the
cleaner body 62, a manual operating unit 64 arranged at the other
end of the hose 63, an extension pipe 65 of a bisected structure
one of whose ends is connected to the manual operating unit 64, a
suction inlet unit 66 detachably connected to the other end of the
extension pipe 65, the electric blower 1 housed and held within the
cleaner body 62, and a dust chamber 67 formed within the cleaner
body 62.
[0068] The hose 63 is connected to the cleaner body 62 in such a
manner that its base end is made to communicate with the suction
side of the electric blower 1 via the dust chamber 67. The manual
operating unit 64 provided at the other end of the hose 63 is
equipped with a grip 68 extending backwards and an operating means
69 positioned within manipulation range of the fingers of the
operator holding this grip 68. The operating means 69 is equivalent
to the operating unit 28 in FIG. 5.
[0069] The operating means 69 also serves as the power switch for
the electric blower 1, and is configured to allow selecting one of
a plurality of operating modes in which this electric blower 1 is
driven to different states of power. More specifically, there are
successively arranged in a row, in the direction from the grip 68
to the extension pipe 65, a stop button 69a for setting the
operating mode to a stopped state, a low power operation button 69b
for setting low power operation, and a high power operation button
69c for setting high power operation. In high power operation mode
for instance, the electric blower 1 turns at a high speed of 30,000
rpm and sucks up the dust.
[0070] The cleaner body 62 has a body case 70. This body case 70 is
configured by joining a lower case 70a which is open on the top
face and formed for example of acrylonitrile butadiene styrene
(ABS) or similar material, and an upper case 70b of the same
material to block the rear top face of this lower case 70a with a
bumper (not shown) being held by the circumferential edges
including the front face, and is thereby formed into a case whose
front upper face is open. A lid 71 is fitted to this body case 70,
pivoting on it to make the opening in the front upper face
closable.
[0071] The body case 70 is fitted with turning wheels 72 on the
front under face of the cleaner body 62 in the running direction,
and following wheels 73 of a larger diameter are fitted to the rear
side faces of the cleaner body 62. The turning wheels 72 and the
following wheels 73 allow the vacuum cleaner 61 to move along the
floor (not shown). A handle 74 which is vertically slidable is
provided at the top of the cleaner body 62.
[0072] On the other hand, A dust chamber 77 is partitioned and
formed in the running direction of the cleaner body 62 within the
cleaner body 62. A inside wall 76 having ventilated grids 75 is
formed behind the dust chamber 77. And the dust chamber 77 is
opened upward. An electric blower chamber 78 for housing the
electric blower 1 is partitioned and formed behind the dust chamber
77. A dust bag 90 is detachably fitted by a holder 79 formed within
the dust chamber 77.
[0073] An auxiliary dust filter 91 covering those ventilated grids
75 is detachably fitted to the front side of the inside wall 76.
This auxiliary dust filter 91 has a frame 92 and an auxiliary
filter 93 to be snapped onto this frame 92.
[0074] The dust bag 90 and the auxiliary dust filter 91 are
attached or detached through the top opening of the dust chamber
77. The lid 71, whose rear end pivots on the upper case 70b, is
formed so as to cover the dust chamber 77 from above.
[0075] On the other hand, the electric blower 1 is provided within
the electric blower chamber 78. This electric blower 1 is
structured in the same way as the electric blower 1 as the first
preferred embodiment of the invention. On the circumferential
surface near the rear part of the motor case 6 is opened an
electric blower outlet 94 as the exhaust port. Though not shown,
the electric blower outlet 94 may also be formed in the rear
surface of the motor case 6.
[0076] In this configuration, when the motor 2 rotates, the
centrifugal fan 4 rotates integrally with that rotation, and this
rotation guides air from the intake opening 16 of the fan cover 15
through the centrifugal fan 4, its exhaust port 22, the diffuser 14
and the motor 2 to the electric blower outlet 94.
[0077] An airtight supporter 95, which is an annular and made of
natural rubber or synthetic rubber for instance, is fitted into the
front end of the outer circumferential edge of the electric blower
1. On the other hand, an upper rib front 78a and a lower rib front
78b constituting part of a chamber wall of the electric blower
chamber 78 are protrusively formed at the lower face of the upper
case 70b and the upper face of the lower case 70a. The airtight
supporter 95 is brought into contact with the upper rib front 78a
and lower rib front 78b to set the electric blower 1 in the
electric blower chamber 78.
[0078] A negative pressure generated by the drive of the electric
blower 1 deforms the airtight supporter 95. On the front end of the
electric blower 1, this airtight supporter 95 makes an airtight
communication between the intake opening 16 of the electric blower
1 and the dust chamber 77 via the ventilated grids 75.
[0079] The airtight supporter 95 has a substantial L-shaped section
and is arranged between the outer surface of the fan cover 15 and
the chamber wall of the electric blower chamber 78. The airtight
supporter 95 is made of absorbing vibration material which is
natural rubber or synthetic rubber, for instance, as mentioned
above. In this embodiment, since the switching element 23 as the
power device to drive the electric blower 1 is directly fixed to
the outer surface of the case 5, the vibration of the body case 70
caused by steps and/or unevenness of floors is directly transmitted
to the switching element 23 when the vacuum cleaner 61 is moved on
the floors. However, by making the airtight supporter 95 of the
absorbing vibration material, it is possible to suppress the
transmission of vibrations from the body case 70 and thereby
increase the mechanical reliability of the switching element
23.
[0080] On the other hand in this embodiment, since the switching
element 23 and the airtight supporter 95 are close to each other,
the airtight supporter 95 is affected by heat from the switching
element 23 when the electric blower 1 is being driven. Therefore,
by using highly heat resisting material, such as silicone rubber or
ethylene propylene rubber for the airtight supporter 95, the
thermal reliability of the vacuum cleaner 61 can be enhanced.
[0081] On the other hand, so that heat caused by the switching
element 23 when the electric blower 1 is being driven will not
affect the chamber wall of the electric blower chamber 78, namely,
the body case 70, it is necessary to make the airtight supporter 95
of thermally insulated material, which is natural foam rubber or
synthetic foam rubber having a lot of air bubbles inside. Since
foam material even of the same component parts may differ in
thermal insulation performance if density of the air bubbles
varies, the density should be adjusted according to the level of
heat caused by the switching element 23.
[0082] According to a characteristic of the vacuum cleaner 61, the
material of the airtight supporter 95 is chosen from among the
absorbing-vibration material, heat resisting material or thermally
insulated material and/or the component parts are adjusted.
[0083] An electric blower mounted in the vacuum cleaner 61 may be
not only the electric blower of the first embodiment but that of
other embodiments.
[0084] There are a number of factors that can influence the dust
sucking power of the vacuum cleaner 61. These factors include the
input power and pressure loss of a channel. While a greater input
power would increase the dust sucking power, the heat caused by the
switching element 23 or elements 47a through 47f which control that
input power would also increase. If temperature of the switching
element 23 or elements 47a through 47f is too high, the input power
might be limited. In addition, the larger pressure loss of the
channel, the weaker the dust sucking power. Therefore, it is
particularly effective in enhancing the dust sucking performance of
the vacuum cleaner 61 to be equipped with the aforementioned
electric blower 1 or 42, which can effectively cool the switching
element 23 or elements 47a through 47f, which are the power
devices, without increasing pressure loss of the channel.
[0085] A fifth preferred embodiment of the present invention will
now be described with reference to FIG. 16. While this embodiment
is basically similar to the first embodiment, a cooling opening 100
is formed on the partition wall 88 near the switching element 23.
Thus the cooling opening 100 is formed at a position where a blown
air directly hits the switching element 23 or a position where the
blown air directly gives rise to forced convection around the
switching element 23. FIG. 16 specifically shows a case in which
the cooling opening 100 is formed on the partition wall 88 parallel
to the rotor axis 3 in the vicinity of the fixed switching element
23. The number of cooling openings 100 may be one or more.
[0086] In this configuration an air with only a slight rise in
temperature before passing the motor 2 flows on the surface of the
switching element 23 or to the vicinity of it. It is therefore
possible to cool the switching element 23 using the blown air
forcibly and release the heat to the partition wall 88 which is
part of the case 5 at the same time. And the cooling effect to the
switching element 23 is significantly enhanced.
[0087] A sixth preferred embodiment of the invention will now be
described with reference to FIG. 17. While this embodiment is
basically similar to the third embodiment, cooling openings 101 are
formed on the flange 31 near the switching elements 47a through
47f. Thus the cooling openings 101 are formed in a position where
the blown air directly gives rise to forced convection around the
switching elements 47a through 47f. FIG. 17 specifically shows a
case in which a plurality of cooling openings 101 are formed on the
flange 31 orthogonal to the rotor shaft 3 in the vicinity of the
switching elements 47a through 47f.
[0088] In this configuration an air with only a slight rise in
temperature before passing the brushless motor 41 flows to the
vicinity of the switching elements 47a through 47f. It is therefore
possible to cool the switching element 23 using the blown air
forcibly and release the heat to the flange 31 which is part of the
motor case 6 at the same time. And the cooling effect to the
switching elements 47a through 47f is significantly enhanced.
[0089] Obviously, numerous modifications and variations of the
present invention are possible in light of the above teachings. It
is therefore to be understood that within the scope of the appended
claims, the invention may be practiced otherwise than as
specifically described herein.
* * * * *