U.S. patent application number 14/461413 was filed with the patent office on 2015-03-19 for air compressor.
The applicant listed for this patent is HITACHI KOKI CO., LTD.. Invention is credited to Naoto Ichihashi.
Application Number | 20150078938 14/461413 |
Document ID | / |
Family ID | 51357818 |
Filed Date | 2015-03-19 |
United States Patent
Application |
20150078938 |
Kind Code |
A1 |
Ichihashi; Naoto |
March 19, 2015 |
AIR COMPRESSOR
Abstract
An air compressor includes a cooling fan having a back plate
serving as a plate shape part formed on a flat plate, a normal line
thereof being set to a direction along a rotational shaft of a
motor, blades extending parallel with the rotational shaft from an
inner side of the back plate towards an outer periphery thereof and
being centrifugally formed on the back plate, and a ring part
having a cylindrical shape substantially parallel with the
rotational shaft and extending from the back plate towards a heat
generation surface. When the motor is operated, exterior air sucked
by the cooling fan is guided to a central part thereof, flows
towards an outer periphery thereof along the back plate, deflected
by the ring part, flows towards and collides with the heat
generation surface and further flows radially.
Inventors: |
Ichihashi; Naoto; (Ibaraki,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
HITACHI KOKI CO., LTD. |
Tokyo |
|
JP |
|
|
Family ID: |
51357818 |
Appl. No.: |
14/461413 |
Filed: |
August 17, 2014 |
Current U.S.
Class: |
417/423.8 |
Current CPC
Class: |
F04D 25/082 20130101;
F04B 41/02 20130101; F04D 29/584 20130101; F04B 35/06 20130101;
F04D 29/5806 20130101; F04D 13/06 20130101; F04D 29/281 20130101;
F04B 39/066 20130101 |
Class at
Publication: |
417/423.8 |
International
Class: |
F04D 25/08 20060101
F04D025/08; F04D 29/58 20060101 F04D029/58; F04D 13/06 20060101
F04D013/06 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 18, 2013 |
JP |
2013-193538 |
Claims
1. An air compressor comprising: an air tank configured to store
therein compressed air; a compression part configured to compress
air sucked from an outside and to supply the air to the air tank; a
motor configured to drive the compression part; a cooling fan
provided at one end-side of a rotational shaft of the motor, and a
cover configured to cover at least the compression part, the motor
and the cooling fan, wherein the cooling fan comprises a ring part
provided at an outer peripheral part thereof and having a
substantially cylindrical shape, and wherein the cooling fan is
configured to change a direction of an air stream by the ring
part.
2. The air compressor according to claim 1, wherein the ring part
is configured to guide the air stream to a first heat generation
part.
3. The air compressor according to claim 1, wherein the cooling fan
comprises a plate-shaped part partially bridging between an
attaching part to the rotational shaft and the ring part.
4. The air compressor according to claim 3, wherein the attaching
part and the ring part are connected and integrated over an entire
circumference by the plate-shaped part.
5. The air compressor according to claim 3, wherein the cooling fan
comprises a blade for generating an air stream, and wherein the
blade is integrated with the plate-shaped part.
6. The air compressor according to claim 1, wherein the cooling fan
is configured to generate an air stream flowing from a center-side
towards an outer peripheral direction by a rotation of the blade
and to change a direction of the air stream such that the air
stream has a component in a direction along the rotational
shaft.
7. The air compressor according to claim 6, wherein a first heat
generation part is arranged at a position which faces the cooling
fan and with which the air stream which direction has been changed
by the ring part collides.
8. The air compressor according to claim 7, wherein a baffle wall
part is provided at a position facing a part except for a central
part of the cooling fan at the same side as the first heat
generation part, wherein the cooling fan is configured to suck the
air stream through between the first heat generation part and the
baffle wall part, and wherein the ring part enables an outflow
direction of the air stream of the cooling fan to be close to
parallel with the suction direction of the air stream.
9. The air compressor according to claim 7, wherein the first heat
generation part is a control circuit board or a holding member of
the control circuit board.
10. The air compressor according to claim 1, wherein the cover
comprises a ventilating window at a position facing a suction-side
of the cooling fan.
11. The air compressor according to claim 1, further comprising a
baffle wall part configured to change a direction of the air stream
outflowing from the cooling fan and to guide the air stream towards
a second heat generation part.
12. The air compressor according to claim 11, wherein the second
heat generation part is a cylinder of the compression part.
13. The air compressor according to claim 12, further comprising
another cooling fan provided at the other end-side of the
rotational shaft of the motor, wherein the baffle wall part is
configured to guide the air stream outflowing from the cooling fan
to a side of the cylinder with which an air stream from said
another cooling fan does not collide.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority from Japanese Patent
Application No. 2013-193538 filed on Sep. 18, 2013, the entire
subject-matter of which is incorporated herein by reference.
TECHNICAL FIELD
[0002] The present invention relates to an air compressor suitable
for generation of compressed air required to drive a pneumatic tool
such as a nailing machine.
BACKGROUND
[0003] In a building site and the like, a portable pneumatic tool
to drive a nail and a screw into a wooden material by a pressure of
compressed air has been widely used. In general, an air compressor
for driving the pneumatic tool and the like is configured to
convert a rotational motion of a rotational shaft of a driving part
such as a motor into a reciprocal motion of a piston in a cylinder
through a crankshaft of a compression part and to compress air
sucked from a suction valve of the cylinder by the reciprocal
motion of the piston. The compressed air compressed in the cylinder
is discharged from an exhaust valve of the cylinder to an air tank
through a pipe and is stored in the air tank. When compressing the
gas to a high pressure, a multistage reciprocating compressor of
increasing a pressure in a stepwise manner has been generally used.
The high-pressure compressed air stored in the air tank is adjusted
to an appropriate pressure by a decompression valve attached to the
air tank and is then supplied to the pneumatic tool and the like
through an air hose. The air compressor is disclosed in
JP-A-2013-40586.
SUMMARY
[0004] The air compressor has a plurality of heat generation parts
in which the temperature thereof is high in accordance with using
the motor, the compression part (particularly, the cylinder), the
control circuit and the like. Thus, in many cases, the heat
generation parts should be thus arranged at spaced positions.
Therefore, it is necessary to securely guide the cooling air
generated by the cooling fan attached to the rotational shaft of
the motor to the respective heat generation parts. However, the
heat generation part may be positioned at a place that is difficult
to be cooled by the general cooling fan, due to a layout, which is
a problem to be solved with respect to the cooling efficiency.
[0005] It is therefore an object of the present invention to
provide an air compressor capable of improving cooling efficiency
by a cooling fan.
[0006] According to one illustrative aspect of the present
invention, there is provided an air compressor comprising: an air
tank configured to store therein compressed air; a compression part
configured to compress air sucked from an outside and to supply the
air to the air tank; a motor configured to drive the compression
part; a cooling fan provided at one end-side of a rotational shaft
of the motor, and a cover configured to cover at least the
compression part, the motor and the cooling fan, wherein the
cooling fan comprises a ring part provided at an outer peripheral
part thereof and having a substantially cylindrical shape, and
wherein the cooling fan is configured to change a direction of an
air stream by the ring part.
[0007] Incidentally, any combination of the above-described
elements, and a method, a system and the like converted from the
expressions of the present invention are also effective as the
aspects of the present invention.
[0008] According to the illustrative aspects of the present
invention, it is possible to provide an air compressor capable of
improving cooling efficiency by a cooling fan.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a perspective view of an air compressor 1
according to a first illustrative embodiment of the present
invention;
[0010] FIG. 2 is a plan view of the air compressor 1 in which a
cover 26 is a cross-sectional surface;
[0011] FIG. 3 is a plan sectional view of the air compressor 1;
[0012] FIG. 4 is a IV-IV sectional view of FIG. 2;
[0013] FIG. 5 is a front sectional view of the air compressor
1;
[0014] FIG. 6 is a first perspective view from below of the cover
26 of the air compressor 1;
[0015] FIG. 7 is a second perspective view from below of the cover
26 of the air compressor 1;
[0016] FIG. 8 is an VIII-VIII sectional view of FIG. 4 relating to
the cover 26 of the air compressor 1;
[0017] FIG. 9 is a IX-IX sectional view of FIG. 4 relating to the
cover 26 of the air compressor 1;
[0018] FIG. 10 is a perspective view of a cooling fan 8b of the air
compressor 1;
[0019] FIG. 11 is a perspective view of a cooling fan 8a of the air
compressor 1;
[0020] FIG. 12 is a perspective view of a seventh baffle plate 306
of the air compressor 1;
[0021] FIG. 13 is a plan view of an air compressor according to a
second illustrative embodiment of the present invention, in which
the cover 26 is a cross-sectional surface;
[0022] FIG. 14 is a plan view of an air compressor according to a
third illustrative embodiment of the present invention, in which
the cover 26 is a cross-sectional surface; and
[0023] FIG. 15 is a plan view of an air compressor according to a
fourth illustrative embodiment of the present invention, in which
the cover 26 is a cross-sectional surface.
DETAILED DESCRIPTION
[0024] Hereinafter, preferred illustrative embodiments of the
present invention will be described with reference to the drawings.
Incidentally, the same or equivalent elements, members and the like
shown in the respective drawings are denoted with the same
reference numerals and the overlapping descriptions are
appropriately omitted. Also, the illustrative embodiments are just
exemplary, not to limit the present invention, and all features and
combinations thereof described in the illustrative embodiments
cannot be considered as the essentials of the present
invention.
First Illustrative Embodiment
[0025] FIG. 1 is a perspective view of an air compressor 1
according to a first illustrative embodiment of the present
invention. FIG. 2 is a plan view of the air compressor 1 in which a
cover 26 is a cross-sectional surface. Incidentally, in FIG. 2,
gripping parts 31a, 31b are not shown. FIG. 3 is a plan sectional
view of the air compressor 1. FIG. 4 is a IV-IV sectional view of
FIG. 2. FIG. 5 is a front sectional view of the air compressor 1.
FIG. 6 is a first perspective view from below of the cover 26 of
the air compressor 1. FIG. 7 is a second perspective view from
below of the cover 26 of the air compressor 1. FIG. 8 is an
VIII-VIII sectional view of FIG. 4 relating to the cover 26 of the
air compressor 1. FIG. 9 is a IX-IX sectional view of FIG. 4. FIG.
10 is a perspective view of a cooling fan 8b of the air compressor
1. FIG. 11 is a perspective view of a cooling fan 8a of the air
compressor 1. FIG. 12 is a perspective view of a seventh baffle
plate 306 of the air compressor 1.
[0026] The air compressor 1 includes: a pair of air tanks 2a, 2b
arranged to be parallel at a predetermined interval therebetween
and storing therein compressed air; a compression part 3 for
compressing air sucked from an outside and supplying the compressed
air to the air tanks 2a, 2b; and a motor 4, which is connected to
the compression part 3, for driving the compression part 3. The
motor 4 and the compression part 3 are arranged above the pair of
air tanks 2a, 2b such that an axis direction of the motor 4 is
substantially perpendicular to a longitudinal direction of the air
tanks 2a, 2b.
[0027] As shown in FIG. 3, a rotational shaft 5 of the motor 4
penetrates the compression part 3, and a cooling fan 8a (a first
cooling fan) is provided at a motor-side end portion of the
rotational shaft 5 of the motor 4 and a cooling fan 8b (a second
cooling fan) is provided at a non-motor-side end portion of the
rotational shaft 5 of the motor 4. The cooling fans 8a, 8b are
rotated integrally with the motor 4.
[0028] As shown in FIG. 2, decompression valves 9a, 9b, pressure
meters 10a, 10b for displaying a pressure of the decompressed
compressed air and couplers 11a, 11b functioning as outlets of the
compressed air are provided in the vicinity of the compression part
3 in the longitudinal direction of the pair of air tanks 2a, 2b. An
operator connects the couplers 11a, 11b and a pneumatic tool (not
shown) such as a nailing machine by an air hose for high pressure
(not shown) and operates the pneumatic tool by using the compressed
air to appropriately perform an operation.
[0029] As shown in FIG. 2, the air tanks 2a, 2b are provided with a
safety valve 12 and a drain discharge device 13. The safety valve
12 is configured to discharge a part of the compressed air to the
outside when a pressure is abnormally increased. The drain
discharge device 13 has an operation part 14. When the operation
part 14 is operated, the compressed air and moisture in the air
tanks 2a, 2b can be appropriately discharged to the outside.
[0030] As shown in FIG. 3, the compression part 3 is provided
therein with a crank mechanism. A rotational motion of the
rotational shaft 5 of the motor 4 is converted into reciprocal
motions of a first piston 34a and a second piston 34b through a
first connecting rod 33a and a second connecting rod 33b,
respectively. The first piston 34a is accommodated in a first
cylinder 15a and a first cylinder head 16a. The second piston 34b
is accommodated in a second cylinder 15b and a second cylinder head
16b. The first cylinder 15a and the second cylinder 15b are
horizontally opposed to each other with the rotational shaft 5 of
the motor 4 being interposed therebetween. The first cylinder 15a
and the second cylinder 15b are arranged to be substantially
parallel with the air tanks 2a, 2b, respectively. When the exterior
air is sucked in the compression part 3, the air is first
compressed by the second cylinder 15b (a low pressure-side
cylinder) and the air compressed by the second cylinder 15b is
supplied to the first cylinder 15a (a high pressure-side cylinder)
through a piping 19a (refer to FIG. 2). The air further compressed
by the first cylinder 15a is supplied to the air tank 2a through a
piping 19b. The air tanks 2a, 2b are connected to each other by a
connection pipe 20, so that the pressures of the air tanks 2a, 2b
are uniform.
[0031] As shown in FIG. 3, a control circuit 21 (a control circuit
board) for driving the motor 4 is accommodated in a case 22. The
control circuit 21 is arranged to face the cooling fan 8b at the
non-motor-side of the compression part 3. The control circuit 21 is
fixed to the air tank 2a. The motor 4, which is a DC brushless
motor, has a stator coil 23, a rotor 24 arranged in the stator coil
23 and a Hall element board 25 (refer to FIG. 2) for detecting a
rotating position of the rotor 24. The motor 4 is
inverter-controlled by the control circuit 21. The control circuit
21 includes a heat generation component 204 (refer to FIG. 3) such
as a semiconductor switching element for inverter control. A
surface of the case 22 on which the heat generation component 204
is attached is configured as a heat generation surface 203, from
which a heat is to be radiated or which is to be cooled.
[0032] As shown in FIG. 1, a cover 26 for covering the components
of the air compressor such as the compression part 3, the motor 4,
the control circuit 21 and the like is arranged above the air tanks
2a, 2b and is fixed to the air tanks 2a, 2b. Both end portions of
the air tanks 2a, 2b in the longitudinal direction are provided
with gripping parts 31a, 31b for carrying the air compressor 1. The
cover 26 is provided with an operation panel 26 having a power
supply switch (not shown) for operating the air compressor 1 and
the like. The cover 26 is provided with ventilating windows 29a,
29b (refer to FIGS. 6 and 7) on wall surfaces facing the cooling
fans 8a, 8b. A cover 30 (refer to FIG. 4) for preventing foreign
materials from being introduced is additionally attached between
the air tanks 2a, 2b. The air tanks 2a, 2b are provided with leg
parts 32 for preventing the air tanks 2a, 2b from directly
contacting a ground to protect the air tanks 2a, 2b.
[0033] During an operation of the air compressor 1, the motor 4 is
alternately applied with a compression load upon compression of the
air by the reciprocal motions of the first piston 34a and the
second piston 34b. For this reason, load currents are generated in
the stator coil 23 and the control circuit 21, so that temperatures
of the stator coil 23 and the control circuit 21 are increased by
Joule heats accompanied by the load currents. Also, temperatures of
the first cylinder 15a, the first cylinder head 16a, the second
cylinder 15b and the second cylinder head 16b are increased by
compression heat of the compressed air. Temperatures of the pipings
19a, 19b and the air tanks 2a, 2b are also increased because the
compressed air whose temperature is increased by the compression
heat flows therein. For this reason, it is necessary to suppress
the increase in the temperature of the respective parts by the
cooling, with a focus on the heat generation parts such as the
first cylinder 15a, the first cylinder head 16a, the second
cylinder 15b, the second cylinder head 16b, the stator coil 23, the
control circuit 21, the case 22 and the like. Hereinafter,
configurations relating to the cooling will be described.
[0034] (Cooling by Cooling Fan 8a)
[0035] In a typical axial flow fan, a generated air stream has a
tendency to flow in an outer peripheral direction due to a high
centrifugal force thereof. Therefore, it is difficult to promote
the air stream in the adjacent motor, and thus the heat is likely
to be accumulated in the motor. Here, a configuration for improving
cooling performance of the motor 4 will be described.
[0036] As shown in FIG. 11, the cooling fan 8a has outer blades 104
and inner blades 105. The outer blades 104 and the inner blades 105
are connected to each other by a cylindrical partition part
(cylindrical part) 102. The partition part 102 extends in a
direction along the rotational shaft of the motor 4. An attaching
part 103 is formed at a further inner side of the inner blades 105.
The cooling fan 8a can be attached to the rotational shaft 5 of the
motor 4 by the attaching part 103. The inner blades 105 are formed
integrally with the partition part 102 and the attaching part 103.
The inner blades 105 are formed into a curved plate shape extending
substantially parallel with the rotational shaft 5 of the motor 4,
a so-called centrifugal type. The cooling fan 8a has a
through-hole, which is formed by the adjacent inner blades 105,
partition part 102 and attaching part 103. The through-hole is
formed such that an opening area of a non-motor-side opening 107 is
smaller than an opening area of a motor-side opening 106 at an
opposite side (refer to FIG. 3). The outer blades 104 are formed
into a curved shape extending obliquely relative to the direction
along the rotational shaft 5 of the motor 4, a so-called axial flow
type. As shown in FIG. 3, an outer diameter D2 of the outer blades
104 is set to be larger than an outer diameter D1 of the motor 4.
The cover 26 is formed with the ventilating window 29a facing the
cooling fan 8a. A central portion of the ventilating window 29a is
formed with a shield plate 101 (refer to FIGS. 7 and 8) facing the
inner blades 105 and serving as a shield part.
[0037] When the motor 4 is operated, the cooling fan 8a is rotated
to generate an air stream. That is, the exterior air is sucked from
an outside through the ventilating window 29a by the outer blades
104, and an air stream CA1 flowing towards the first cylinder 15a,
the first cylinder head 16a, the second cylinder 15b and the second
cylinder head 16b, as shown in FIG. 3, is generated. Also, a part
of the air stream generated by the outer blades 104 flows towards
the stator coil 23, like an air stream CA2. At this time, by a
negative pressure P1 additionally generated by the inner blades
105, the air in the vicinity of the stator coil 23 is sucked to the
inner blades 105, like an air stream CA3. The air sucked to the
inner blades 105 is enabled to flow out from the motor-side opening
106 towards the non-motor-side opening 107 by a negative pressure
P2 generated by the outer blades 104, and is then sucked to the
outer blades 104, like an air stream CA4. Thereafter, the air
sucked to the outer blades 104 like the air stream CA4 is enabled
to flow out together with the air stream CA1. As shown in FIG. 4,
the cooling wind having completed the cooling is discharged to the
outside of the cover 30 through between the air tanks 2a, 2b.
[0038] According thereto, it is possible to generate the air
streams CA3, CA4 by the inner blades 105 (the air stream generated
by the inner blades 105 is restrained by a cylindrical inner
surface of the partition part 102 and is securely enabled to flow
in a direction along a rotational shaft of the cooling fan 8a).
Therefore, a synergetic effect with the air streams CA1, CA2 of the
outer blades 104 can be exhibited, and it is possible to generate a
high flow rate in the vicinity of the stator coil 23, in which the
air stream is stagnant in the related art. According thereto, it is
possible to effectively suppress the temperature increase of the
stator coil 23. That is, it is possible to realize the auxiliary
effect or synergetic effect for the air stream of the outer blades
104, which is likely to flow in the outer peripheral direction due
to the high centrifugal force, by the inner blades 105, so that it
is possible to improve the cooling performance of the motor 4 by
the cooling fan 8a.
[0039] Further, the rotational shaft 5 of the motor 4 is
alternately applied with the compression load upon the compression
of the air in the first cylinder 15a and the second cylinder 15b,
so that a rotational variation is generated. Thus, a distortion
vibration due to the rotational variation is generated for the
cooling fan 8a. However, the attaching part 103 and the partition
part 102 are strongly connected using the plurality of inner blades
105. According thereto, it is possible to disperse and reduce the
stress resulting from the distortion vibration, thereby increasing
the strength and reliability of the cooling fan 8a. Further, since
the inner blades 105 also serve as a connection part (a frame)
connecting the partition part 102 and the attaching part 103 each
other, it is not necessary to separately form a connection part,
which does not contribute to the air stream, so that the structure
is efficient. Incidentally, by increasing the number of the inner
blades 105, it is possible to improve the performance of the inner
blades 105 as a fan and to improve the connection strength of the
partition part 102 and the attaching part 103.
[0040] Further, the cooling fan 8a has a difference in the opening
area between the non-motor-side opening 107 and the motor-side
opening 106. According thereto, it is easy to control the flowing
direction of the air stream generated by the inner blades 105. That
is, it is possible to appropriately control the flowing direction
of the air stream generated by the inner blades 105 by
appropriately adjusting an opening area ratio between the
non-motor-side opening 107 and the motor-side opening 106.
[0041] Further, the outer blades 104 suck the air from the
non-motor-side (the outside of the cover 26) and enable the air
stream to flow out towards the motor 4 and the compression part 3.
Therefore, it is possible to suck a large amount of the exterior
air having a temperature lower than the temperature in the cover 26
into the cover 26 and to extensively cool the motor 4, the
compression part 3 and the like.
[0042] Further, since the shield plate 101 is provided, the
negative pressure P2 between the cooling fan 8a and the shield
plate 101 by the action of the outer blades 104 is enhanced.
According thereto, it is possible to further promote the air
streams CA3, CA4, thereby considerably improving the cooling
efficiency. That is, it is possible to enable the air in the
vicinity of the motor 4, which is sucked to the central part of the
cooling fan 8a by the negative pressure (suction) by the inner
blades 105, to smoothly flow towards the non-motor-side of the
inner blades 105 and to further improve the cooling effect in the
vicinity of the motor by the synergetic effect of the negative
pressures of the outer blades 104 and the inner blades 105.
[0043] Further, the outer diameter D2 of the outer blades 104 is
set to be larger than the outer diameter D1 of the motor 4.
According thereto, a part of the air stream generated by the outer
blades 104 is directly supplied to the compression part 3 without
via the motor 4. As a result, it is possible to improve the cooling
efficiency of the compression part 3.
[0044] Further, the air volume by the outer blades 104 is set to be
larger than the air volume enabled to flow through the inner side
of the partition part 102 by the inner blades 105. According
thereto, it is easy to enable a part of the air stream, which is
generated by the inner blades 105 mainly generating the air stream
in the vicinity of the motor 4, to flow together with the air
stream generated by the outer blades 104. Therefore, it is possible
to securely supply the air stream after the cooling of the motor to
the compression part 3 and to finally discharge the air stream to
the outside of the cover. Thus, it is possible to exclude the bad
influence on the cooling performance, which is caused as the heat
is accumulated in the vicinity of the motor 4, thereby improving
the cooling performance.
[0045] Incidentally, it may be possible to appropriately change the
area ratio between the motor-side opening 106 and the
non-motor-side opening 107 of the cooling fan 8a and to
appropriately change the shapes of the inner blade 105 and the
outer blade 104.
[0046] (Cooling by Cooling Fan 8b)
[0047] In general, the air compressor has a plurality of heat
generation parts in which the temperature thereof is high in
accordance with using the motor, the compression part
(particularly, the cylinder), the control circuit and the like.
Thus, in many cases, the heat generation parts should be arranged
at spaced positions. Therefore, it is necessary to securely guide
the cooling air generated by the cooling fan attached to the
rotational shaft of the motor to the respective heat generation
parts. However, the heat generation part may be positioned at a
place that is difficult to be cooled by the general cooling fan,
due to a layout, which is a problem to be solved with respect to
the cooling efficiency. Regarding this problem, a configuration for
improving the cooling efficiency will be described.
[0048] As shown in FIGS. 3 and 4, the case 22 and the control
circuit 21 are arranged to face the cooling fan 8b that is attached
to the end portion of the non-motor-side of the rotational shaft 5
of the motor 4. In the case 22, the heat generation surface 203 of
the accommodated control circuit 21, on which the heat generation
component 204 is mounted, faces the cooling fan 8b. The heat
generation component 204 faces an outer peripheral part (a ring
part 201 that will be described later) of the cooling fan 8b with
the heat generation surface 203 being interposed therebetween. The
heat generation component 204 is an IGBT (insulated gate bipolar
transistor), a diode bridge, an IPM (intelligent power module) and
the like.
[0049] As shown in FIG. 10, the cooling fan 8b has a back plate 202
serving as a plate shape part formed on a flat plate, a normal line
of which is set to a direction along the rotational shaft 5 of the
motor 4. Blades 200 extending substantially parallel with the
rotational shaft 5 of the motor 4 from an inner side of the back
plate 202 towards an outer periphery thereof are centrifugally
formed on the back plate 202. An attaching part 205 is formed at an
inner side of the blades 200. The cooling fan 8b can be attached to
the rotational shaft 5 of the motor 4 by the attaching part 205.
The outer peripheral end of the cooling fan 8b is formed with the
ring part 201. The ring part 201 has a cylindrical shape
substantially parallel with the rotational shaft 5 of the motor 4.
The ring part 201 extends from the back plate 202 towards the heat
generation surface 203. The ring part 201 and the attaching part
205 are connected and integrated over an entire circumference by
the back plate 202. The back plate 202 entirely closes the
motor-side between the ring part 201 and the attaching part
205.
[0050] Further, as shown in FIG. 2, a fifth baffle plate 304 (a
baffle wall part), a sixth baffle plate 305 (a baffle wall part)
and a seventh baffle plate 306 (a baffle wall part) are provided in
the vicinity of the cooling fan 8b. The fifth baffle plate 304 and
the sixth baffle plate 305 are formed as ribs hanging from the
cover 26. The seventh baffle plate 306 shown as a unitary member in
FIG. 12 is attached to the case 22 by a screw material. The seventh
baffle plate 306 is formed from the case 22 towards the
non-motor-side of the second cylinder 15b, as shown in FIG. 2. The
fifth baffle plate 304 hangs from the cover 26 towards the case 22.
The fifth baffle plate 304 is formed with an opening 207 (a notched
portion) having a diameter that is smaller than a diameter D3
(refer to FIG. 4) of the cooling fan 8b (refer to FIGS. 4 and 6 and
the like). The sixth baffle plate 305 is formed integrally with the
fifth baffle plate 304 and is smoothly formed from the fifth baffle
plate 304 towards the non-motor-side of the first cylinder 15a. A
wall surface of the cover 26 facing the cooling fan 8b is formed
with the ventilating window 29b.
[0051] As shown in FIG. 3, when the motor 4 is operated, the
exterior air is sucked from the outside through the ventilating
window 29b by the cooling fan 8b, like an air stream CA10, and is
guided to the central part of the cooling fan 8b by the opening
207. The air stream CA10 flows towards the outer periphery of the
cooling fan 8b along the back plate 202, like an air stream CA11.
Then, as shown in FIG. 3, the air stream CA11 is deflected (a
flowing direction thereof is changed) by the ring part 201 such
that the flowing direction of the air stream CA11 closes to
parallel with the suction direction of the air stream CA10 by the
cooling fan 8b, flows towards and collides with the heat generation
surface 203 (a first heat generation part) and further flows
radially from the cooling fan 8b along the heat generation surface
203. A part of the air stream CA11 is guided towards the
non-motor-sides (a second heat generation part) of the first
cylinder 15a and the second cylinder 15b by the fifth baffle plate
304, the sixth baffle plate 305 and the seventh baffle plate 306,
like air streams CA12, CA13. The cooling air having completed the
cooling is discharged to the outside of the cover 30 through
between the air tanks 2a, 2b, as shown in FIG. 4.
[0052] In this way, the cooling air is deflected by the ring part
201 and is thus enabled to securely collide with the heat
generation surface 203. According thereto, it is possible to
remarkably improve the cooling efficiency of the heat generation
surface 203. Further, by providing the back plate 202, it is
possible to enable the more cooling air to securely flow towards
the non-motor-side (the heat generation surface 203-side), so that
it is possible to further improve the cooling efficiency of the
heat generation surface 203. Further, since the air flow can be
enabled to flow out so as to be ejected towards the heat generation
surface 203 that is arranged in front of the cooling fan 8b, it is
possible to further improve the cooling efficiency. That is, since
the cooling fan 8b sucks centrally the air and enables the air to
flow out in the outer peripheral direction by using the blades 200
and the back plate 202 and applies an axial component (a component
facing the non-motor-side) in the outflow direction of the air
stream by the ring part 201, it is also possible to securely supply
the cooling air to the heat generation surface 203, which exists on
a plane different from the cooling fan 8b. The cooling air supplied
to the heat generation surface 203 is mainly the exterior air
introduced through the ventilating window 29b and not used yet for
another cooling. Therefore, the cooling efficiency of the heat
generation surface 203 is favorable.
[0053] Further, it is possible to utilize the cooling air having
cooled the heat generation surface 203 and the cooling air having
not reached the heat generation surface 203 for cooling the first
cylinder 15a and the second cylinder 15b by the fifth baffle plate
304, the sixth baffle plate 305 and the seventh baffle plate 306.
The effect of this configuration is very advantageous, because the
non-motor-sides of the first cylinder 15a and the second cylinder
15b are difficult to be cooled by the air stream CA1 generated by
the cooling fan 8a and the temperatures thereof are likely to
increase.
[0054] Further, the rotational shaft 5 of the motor 4 is
alternately applied with the compression load upon the compression
of the air in the first cylinder 15a and the second cylinder 15b,
so that a rotational variation is generated. Thus, a distortion
vibration due to the rotational variation is generated for the
cooling fan 8b. However, since the ring part 201 is connected by
the back plate 202, a section modulus of a cross-section, a normal
line of which extends in the direction along the rotational shaft 5
of the motor 4, is remarkably increased, so that it is possible to
obtain the sufficient strength against the centrifugal load and the
distortion vibration load. Further, since the back plate 202 is
provided with the blades 200, it is also possible to increase the
strength of the blades 200. Incidentally, it is preferable to
connect the ring part 201 and the attaching part 205 such that the
back plate 202 entirely closes the motor-side between the ring part
201 and the attaching part 205, from a standpoint of increasing the
cooling efficiency of the first heat generation part.
Alternatively, a structure where the ring part 201 and the
attaching part 205 are connected such that the back plate 202
partially closes the motor-side may also be possible.
[0055] Further, the ring part 201 has not only the function of
changing the direction of the cooling air but a flywheel ring
function of increasing the inertia force of the cooling fan 8b to
thus relieve the rotational variation, thereby reducing the load to
the motor 4 due to the rotational variation, which is structurally
efficient. From another standpoint, the ring part 201 functioning
as the flywheel ring is provided with the function of changing the
direction of the cooling air, so that the ring part 201 can be used
to improve the cooling efficiency, which is also structurally
efficient.
[0056] Incidentally, the blades 200 are not limited to the
centrifugal type and may be appropriately changed. The ring part
201 is not necessarily a complete cylindrical shape and may be
formed to deflect the cooling air towards a heat generation part in
addition to the control circuit 21, the case 22 and the heat
generation surface 203. The ring part 201 is not necessarily
parallel with the rotational shaft 5 of the motor 4 and may be
inclined relative to the back plate 202 to guide the cooling air
towards the first heat generation part. The cooling fan 8b may be
attached such that the back plate 202 faces towards the ventilating
window 29b of the cover 26.
[0057] (Cooling of Cylinder Head)
[0058] During the compression process by the piston in the
compression part 3, the compressed air, which has been heated by
the compression, is supplied into the cylinder head at a high flow
rate and is then stored in the air tank through the piping.
Therefore, since the high-temperature air flows at the high flow
rate in the cylinder head, the heat transfer from the
high-temperature air to the cylinder head is made to a remarkable
extent, and the cylinder head of the compression part 3 becomes
high temperatures. Thus, for the efficient cooling, it is required
to intensively cool the cylinder head becoming the highest
temperature. Hereinafter, a configuration for efficiently cooling
the cylinder head will be described.
[0059] As shown in FIG. 2, a first baffle plate 300 (a baffle wall
part) is arranged in a substantially linear shape in the cover 26
such that a virtual extension line inclined relative to the
rotational shaft 5 of the motor 4 passes above the first cylinder
head 16a, when seen from above, towards the first cylinder 15a that
is positioned at a downstream side in the rotating direction from
the cooling fan 8a. Here, the virtual extension line of the first
baffle plate 300 coincides with a linear approximation straight
line of the first baffle plate 300. An air path or virtual
extension line of the air path following a wall surface of the
first baffle plate 300 facing towards the cooling fan 8a intersects
with the first cylinder head 16a, when seen from above.
[0060] A second baffle plate 301 (a baffle wall part) is arranged
above the first cylinder head 16a such that the second baffle plate
301 hangs from the cover 26 towards the first cylinder head 16a
(refer to FIG. 5). The second baffle plate 301 is provided to
intersect with the air path or virtual extension line of the air
path following the first baffle plate 300 or the linear
approximation straight line of the first baffle plate 300, and to
enable the air stream guided to the first baffle plate 300 to flow
towards the first cylinder head 16a or a vicinity thereof.
[0061] A third baffle plate 302 (a baffle wall part) is arranged in
a substantially linear shape at the second cylinder head 16b-side
such that a virtual extension line inclined relative to the
rotational shaft 5 of the motor 4 passes above the second cylinder
head 16b, when seen from above. Here, the virtual extension line of
the third baffle plate 302 coincides with a linear approximation
straight line of the third baffle plate 302. An air path or virtual
extension line of the air path following a wall surface of the
third baffle plate 302, which faces towards the cooling fan 8a,
intersects with the second cylinder head 16b, when seen from
above.
[0062] A fourth baffle plate 303 (a baffle wall part) is arranged
to face the second cylinder head 16b (refer to FIG. 5). The fourth
baffle plate 303 is provided to intersect with the air path or
virtual extension line of the air path following the third baffle
plate 302 or the linear approximation straight line of the third
baffle plate 302, such that the fourth baffle plate 303 enables the
air stream guided to the third baffle plate 302 to flow towards the
second cylinder head 16b or a vicinity thereof.
[0063] The first baffle plate 300 and the third baffle plate 302
are connected above the rotational shaft 5 of the motor 4 to thus
form a substantial V shape. Further, as shown in FIGS. 6 and 7, the
first baffle plate 300, the second baffle plate 301 and the third
baffle plate 302 are formed as ribs extending (protruding
downwardly) integrally from the cover 26, and the fourth baffle
plate 303 is formed on a part of the wall surface of the cover 26.
As shown in FIG. 2, the first baffle plate 300 and the third baffle
plate 302 are provided to form different angles relative to the
rotational shaft 5 of the motor 4 so as to favorably cool the first
cylinder head 16a and the second cylinder head 16b.
[0064] An eighth baffle plate 307 and a ninth baffle plate 308
(refer to FIG. 7) are provided so as to prevent the air from going
round from the motor-side of the cooling fan 8a towards the
non-motor-side and to prevent the air from flowing out more
outwards than the first cylinder head 16a and the second cylinder
head 16b in the cover 26. The eighth baffle plate 307 and the ninth
baffle plate 308 are formed as ribs extending (hanging) integrally
from the cover 26.
[0065] During the operation of the air compressor 1, the rotational
shaft 5 of the motor 4 is rotated to generate the compressed air,
and the cooling fan 8a is rotated to suck the air from the
ventilating window 29a into the cover 26, as shown in FIG. 2. The
cooling air turns along the rotating direction of the cooling fan
8a, like an air stream CA20 (refer to FIG. 2) and flows along the
rotational shaft 5 of the motor 4 towards the compression part 3.
Then, the cooling air is guided to the first cylinder head 16a by
the first baffle plate 300 (and the upper surface of the cover 26),
like an air stream CA21, and is enabled to further flow to be
ejected to the first cylinder head 16a by the second baffle plate
301, like an air stream CA22, as shown in FIG. 5. Therefore, since
it is possible to form the flowing so that the cooling air securely
reaches the first cylinder head 16a by the first baffle plate 300
and the second baffle plate 301, it is possible to cool the first
cylinder head 16a very effectively. Here, since the air stream
flows along the wall surface at the high flow rate, by making the
linear approximation straight line or virtual extension line of the
first baffle plate 300 to face towards the first cylinder head 16a
when seen from above, it is possible to securely guide the air
stream of high flow rate to the first cylinder head 16a whose
temperature is likely to increase. As a result, it is possible to
realize the high cooling effect.
[0066] Further, a part of the air stream CA20 is guided to the
second cylinder head 16b by the third baffle plate 302 (and the
upper surface of the cover 26), like an air stream CA23, and is
then enabled to flow to be ejected to a vicinity of the second
cylinder head 16b by the fourth baffle plate 303, like an air
stream CA24, as shown in FIG. 5. Therefore, since it is possible to
form the flowing such that the cooling air securely reaches the
second cylinder head 16b by the third baffle plate 302 and the
fourth baffle plate 303, it is possible to cool the second cylinder
head 16b very effectively. Here, since the air stream flows along
the wall surface at the high flow rate, by making the linear
approximation straight line or virtual extension line of the third
baffle plate 302 to face towards the second cylinder head 16b, when
seen from above, it is possible to securely guide the air stream of
high flow rate to the second cylinder head 16b whose temperature is
likely to increase. As a result, it is possible to realize the high
cooling effect.
[0067] Further, the first baffle plate 300 and the third baffle
plate 302 are connected above the rotational shaft 5 of the motor 4
to thus distribute an amount of the cooling air to the first
cylinder head 16a and the second cylinder head 16b, so that an air
volume of the first baffle plate 300 along the rotating direction
of the cooling fan 8a is set to be large. Therefore, it is possible
to prevent an air path resistance due to the third baffle plate
302, which is arranged against the rotating direction of the
cooling fan 8a, from being excessively high, so that it is possible
to favorably cool the first cylinder head 16a and the second
cylinder head 16b. That is, since the air volume guided by the
first baffle plate 300 following the turning direction of the air
stream is set to be larger than the air volume guided by the third
baffle plate 302 arranged against the turning direction of the air
stream, it is possible to cool both the first cylinder head 16a and
the second cylinder head 16b while suppressing the increase in the
air path resistance due to the third baffle plate 302. The cooling
air having completed the cooling is discharged to the outside of
the cover 30 mainly through between the air tanks 2a, 2b.
[0068] Incidentally, the first baffle plate 300 and the third
baffle plate 302 are ideally formed to have a linear shape so as to
minimize the air path resistance (the wall surfaces facing towards
the cooling fan 8a-side are formed to be planar). However, even
though the first baffle plate 300 and/or the third baffle plate 302
are partially curved/bent so as to avoid other components, for
example, it is possible to guide the cooling air to the first
cylinder head 16a or second cylinder head 16b inasmuch as the
linear approximation straight line is formed to pass above the
first cylinder head 16a or second cylinder head 16b.
Second Illustrative Embodiment
[0069] FIG. 13 is a plan view of an air compressor according to a
second illustrative embodiment of the present invention, in which
the cover 26 is a cross-sectional surface. The air compressor of
this illustrative embodiment is the same as the first illustrative
embodiment, except that the first baffle plate 300 and the third
baffle plate 302 are curved to be convex towards the cooling fan
8a-side. The linear approximation straight lines and virtual
extension lines of the first baffle plate 300 and the third baffle
plate 302 intersect with the first cylinder head 16a and the second
cylinder head 16b, when seen from above. Also in this illustrative
embodiment, it is possible to obtain the same effects as the first
illustrative embodiment.
Third Illustrative Embodiment
[0070] FIG. 14 is a plan view of an air compressor according to a
third illustrative embodiment of the present invention, in which
the cover 26 is a cross-sectional surface. The air compressor of
this illustrative embodiment is the same as the first illustrative
embodiment, except that the connection part between the first
baffle plate 300 and the third baffle plate 302 is shifted from the
upper of the rotational shaft 5 of the motor 4 towards the second
cylinder head 16b. In this illustrative embodiment, the air volume
to the first cylinder head 16a is increased and the air volume to
the second cylinder head 16b is decreased, as compared to the first
illustrative embodiment. However, it is possible to reduce the air
path resistance due to the third baffle plate 302 arranged against
the turning direction of the air stream.
Fourth Illustrative Embodiment
[0071] FIG. 15 is a plan view of an air compressor according to a
fourth illustrative embodiment of the present invention, in which
the cover 26 is a cross-sectional surface. The air compressor of
this illustrative embodiment is the same as the first illustrative
embodiment, except that the third baffle plate 302 is omitted and
the first baffle plate 300 extends up to the second cylinder head
16b-side. In this illustrative embodiment, the air volume to the
first cylinder head 16a is increased and the air volume to the
second cylinder head 16b is decreased, as compared to the first
illustrative embodiment. However, since the third baffle plate 302
arranged against the turning direction of the air stream is
omitted, the air path resistance is reduced.
[0072] Although the present invention has been described with
reference to the illustrative embodiments, it can be understood by
one skilled in the art that the respective elements and respective
processes of the illustrative embodiments can be variously modified
within the scope defined in the claims.
[0073] The following matters may also be disclosed in this
specification.
[0074] (1) An air compressor comprising: an air tank configured to
store therein compressed air; a compression part configured to
compress air sucked from an outside and to supply the air to the
air tank; a motor configured to drive the compression part; a
cooling fan provided at one end-side of a rotational shaft of the
motor, and a cover configured to cover at least the compression
part, the motor and the cooling fan, wherein the cooling fan
comprises a ring part provided at an outer peripheral part thereof
and having a substantially cylindrical shape, and wherein the
cooling fan is configured to change a direction of an air stream by
the ring part.
[0075] (2) The air compressor according to (1), wherein the ring
part is configured to guide the air stream to a first heat
generation part.
[0076] (3) The air compressor according to (1) or (2), wherein the
cooling fan comprises a plate-shaped part partially bridging
between an attaching part to the rotational shaft and the ring
part.
[0077] (4) The air compressor according to (3), wherein the
attaching part and the ring part are connected and integrated over
an entire circumference by the plate-shaped part.
[0078] (5) The air compressor according to (3) or (4), wherein the
cooling fan comprises a blade for generating an air stream, and
wherein the blade is integrated with the plate-shaped part.
[0079] (6) The air compressor according to any one of (1) to (5),
wherein the cooling fan is configured to generate an air stream
flowing from a center-side towards an outer peripheral direction by
a rotation of the blade and to change a direction of the air stream
such that the air stream has a component in a direction along the
rotational shaft.
[0080] (7) The air compressor according to (6), wherein a first
heat generation part is arranged at a position which faces the
cooling fan and with which the air stream which direction has been
changed by the ring part collides.
[0081] (8) The air compressor according to (7), wherein a baffle
wall part is provided at a position facing a part except for a
central part of the cooling fan at the same side as the first heat
generation part, wherein the cooling fan is configured to suck the
air stream through between the first heat generation part and the
baffle wall part, and wherein the ring part enables an outflow
direction of the air stream of the cooling fan to be close to
parallel with the suction direction of the air stream.
[0082] (9) The air compressor according to (7) or (8), wherein the
first heat generation part is a control circuit board or a holding
member of the control circuit board.
[0083] (10) The air compressor according to any one of (1) to (9),
wherein the cover comprises a ventilating window at a position
facing a suction-side of the cooling fan.
[0084] (11) The air compressor according to any one of (1) to (10),
further comprising a baffle wall part configured to change a
direction of the air stream outflowing from the cooling fan and to
guide the air stream towards a second heat generation part.
[0085] (12) The air compressor according to (11), wherein the
second heat generation part is a cylinder of the compression
part.
[0086] (13) The air compressor according to (12), further
comprising another cooling fan provided at the other end-side of
the rotational shaft of the motor, wherein the baffle wall part is
configured to guide the air stream outflowing from the cooling fan
to a side of the cylinder with which an air stream from said
another cooling fan does not collide.
* * * * *