U.S. patent application number 09/771932 was filed with the patent office on 2002-02-07 for noise reduction mechanism of fan device and molding method of porous damping material therefor.
Invention is credited to Koshimizu, Kengo, Nishiyama, Toshihiko, Yabe, Mitsuo.
Application Number | 20020015640 09/771932 |
Document ID | / |
Family ID | 18724021 |
Filed Date | 2002-02-07 |
United States Patent
Application |
20020015640 |
Kind Code |
A1 |
Nishiyama, Toshihiko ; et
al. |
February 7, 2002 |
Noise reduction mechanism of fan device and molding method of
porous damping material therefor
Abstract
Porous damping material (40) is attached to an entire inner
circumference of the fan shroud (20) opposing to an end of a fan
(4) and is exposed to opposing space without using conventional
perforated metal. Accordingly, jet noise caused by strong swirl
between the fan (4) and the fan shroud (20) can be damped by the
damping material (40) and impulsive sound scarcely occurs. Thus,
both of the impulsive sound and the jet noise can be effectively
damped, thereby securely reducing noise. The pours member (401)
constituting the porous damping material (40) is a die-molding
product made by a die (150) having a cavity (153).
Inventors: |
Nishiyama, Toshihiko;
(Oyama-shi, JP) ; Koshimizu, Kengo; (Oyama-shi,
JP) ; Yabe, Mitsuo; (Osaka, JP) |
Correspondence
Address: |
ARMSTRONG,WESTERMAN, HATTORI,
MCLELAND & NAUGHTON, LLP
1725 K STREET, NW, SUITE 1000
WASHINGTON
DC
20006
US
|
Family ID: |
18724021 |
Appl. No.: |
09/771932 |
Filed: |
January 30, 2001 |
Current U.S.
Class: |
415/119 |
Current CPC
Class: |
F04D 29/545 20130101;
F04D 29/526 20130101; F04D 29/664 20130101; F01P 5/06 20130101;
F02B 77/13 20130101; F01P 11/12 20130101; B60K 11/08 20130101; B60K
11/06 20130101; F01P 11/10 20130101 |
Class at
Publication: |
415/119 |
International
Class: |
F04D 029/66 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 31, 2000 |
JP |
2000-231152 |
Claims
What is claimed is:
1. A noise reduction mechanism of fan device comprising: a fan
shroud spaced apart from a rotation locus of an end of a rotary fan
by a predetermined gap; a shroud support for supporting the fan
shroud; and a porous damping material opposing to the end of the
fan, the porous damping material being attached to at least a part
of the fan shroud or forming a part of the fan shroud.
2. The noise reduction mechanism of fan device according to claim
1, further comprising a radiator provided to upstream or downstream
of the fan, a radiator hood and an end plate, the radiator hood and
the end plate air-tightly connecting the radiator and the fan
shroud.
3. The noise reduction mechanism of fan device according to claim
2, wherein another porous damping material is attached to inner
circumference of the radiator hood and/or inner circumference of
the end plate.
4. The noise reduction mechanism of fan device according to claim
1, wherein a number of holes is formed to the fan shroud with the
porous damping material being attached.
5. The noise reduction mechanism of fan device according to claim
1, wherein the fan shroud and/or the porous damping material has
bell-mouth shape.
6. The noise reduction mechanism of fan device according to claim
1, wherein the porous damping material has a cover portion for
covering a surface thereof opposing to the end of the fan.
7. The noise reduction mechanism of fan device according to claim
1, wherein the fan shroud has a protector for protecting at least
one of upstream end and downstream end of the porous damping
material in an air flow direction.
8. The noise reduction mechanism of fan device according to claim
1, wherein the fan shroud has an engage member for partially
engaging the porous damping material.
9. The noise reduction mechanism of fan device according to claim
1, wherein the fan shroud has openings respectively provided on
upstream and downstream side in the air flow direction and curved
in bell-mouth shape, and a parallel portion provided between the
openings, the parallel portion being parallel to the axis line
direction of rotation axis of the fan, and wherein the porous
damping material is attached to the parallel portion of the fan
shroud.
10. The noise reduction mechanism of fan device according to claim
9, wherein the porous damping material is formed in a smooth shroud
extending over a part of the bell-mouth opening provided to
upstream and downstream side in the air flow direction.
11. A noise reduction mechanism of fan device comprising: a fan
shroud spaced apart from a rotation locus of an end of a rotary fan
by a predetermined gap; a radiator provided on upstream or
downstream of the fan; a radiator hood and an end plate for
air-tightly connecting the radiator and the fan shroud; and a
damping chamber constituted of semi-closed space surrounded by the
radiator hood, the end plate and the fan shroud, wherein the
damping chamber is in communication with an inside of the radiator
hood through a plurality of resonance pipe provided along
circumferential direction of the damping chamber.
12. A noise reduction mechanism of fan device according to claim 1,
wherein the fan shroud has a cylindrical shape and the porous
damping material is attached to the fan shroud, the porous damping
material being formed in a bell-mouth shape in both of upstream
side and downstream side in air flow direction.
13. The noise reduction mechanism of fan device according to claim
1, wherein the porous damping material is a die-molding
product.
14. The noise reduction mechanism of fan device according to claim
13, wherein the porous damping material is formed linearly in a
longitudinal direction thereof and is curved along the
circumference of the fan shroud.
15. The noise reduction mechanism of fan device according to claim
13, wherein the porous damping material is curved in a longitudinal
direction thereof and is provided along the circumference of the
fan shroud.
16. The noise reduction mechanism of fan device according to claim
13, wherein the porous damping material is constituted of a
plurality of porous member provided along the circumference of the
fan shroud.
17. The noise reduction mechanism of fan device according to claim
13, wherein a configuration of the porous damping material
confronting the end of the fan is a bell-mouth shape on both
upstream side and downstream side of the fan shroud.
18. The noise reduction mechanism of fan device according to claim
13, wherein the porous damping material is held on the fan shroud
and/or the support by a belt-shaped dropout prevention means.
19. The noise reduction mechanism of fan device according to claim
13, wherein the porous damping material is held on the fan shroud
and/or the support by a net-shaped dropout prevention means.
20. A molding method of a porous damping material used for a noise
damping mechanism of fan device having: a rotary fan; a fan shroud
spaced apart from a rotation locus of an end of the rotary fan by a
predetermined gap; a shroud support for supporting the fan shroud;
and a porous damping material opposing to the end of the fan, the
porous damping material being attached to at least a part of the
fan shroud or forming a part of the fan shroud, the method
comprising the steps of: disposing a foam material having larger
volume than a cavity of a die while being elastically deformed; and
heating the die to mold the foam material into the porous damping
material.
21. The molding method of a porous damping material used for a
noise damping mechanism of fan device according to claim 20,
wherein the porous damping material is constituted of a plurality
of porous member provided along the circumference of the fan
shroud, the porous damping material being molded by the foam
material using the die.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a noise reduction mechanism
of a fan device and a molding method of porous damping material
used therefor. More specifically, it relates to a noise reduction
mechanism of a fan device used for engine cooling system of
special-purpose vehicle including construction equipment such as
excavator and other vehicles, and industrial cooling system.
[0003] 2. Description of Related Art
[0004] Conventionally, in an engine cooling system of vehicles,
coolant is circulated between the engine and radiator. In such
cooling system, a fan is attached proximal to the radiator, so that
heat is exchanged between cooling air sucked in by the fan and the
coolant in the radiator to cool the engine by the coolant after
heat exchange.
[0005] In the above, a fan shroud is provided around the fan to
straighten flow of the cooling air passing through the radiator,
thus enhancing heat exchange by the radiator to improve cooling
efficiency of the engine.
[0006] A strong swirl is generated at a slight gap between an end
of the fan and the fan shroud in accordance with rotation of the
fan, which causes jet noise. For reducing the jet noise, it is
disclosed in Japanese Utility Model Laid-Open Publication No. Sho
56-41119, Japanese Utility Model Laid-Open Publication No. Sho
57-126524, Japanese Utility Model Laid-Open Publication No. Sho
64-13229 and Japanese Utility Model Laid-Open Publication No. Hei
2-39956 (including microfilm of respective application in the
publication) to provide a noise damper to the fan shroud.
[0007] All of the noise dampers disclosed in the publications have
opposing surface of the fan shroud opposing the end of the fan
formed of hard perforated metal with a lot of through-holes being
drilled, so that the jet noise can be reduced by the damping
material and energy damping space provided further outer side of
the perforated metal.
[0008] However, according to the noise damper disclosed in the
publications, since the perforated metal is used at the portion
where the strong swirl is generated, high-frequency impulsive sound
can be generated by an impact caused when the cooling air bumps
into step portion of the through-holes of the perforated metal.
Accordingly, though the noise damper can reduce the jet noise, the
impulsive sound can be newly generated, thus being unable to
effectively reduce the overall noise.
SUMMARY OF THE INVENTION
[0009] An object of the present invention is to provide a noise
reduction mechanism of a fan device capable of effectively damp
both the impulsive sound and the jet noise caused by the swirl,
thus effectively reduce the noise.
[0010] The noise reduction mechanism of fan device according to the
present invention attains the above object by changing material of
the member proximal and opposing to the end of the fan and/or
structure around the fan (fan shroud).
[0011] Specifically, A noise reduction mechanism of fan device
according to the present invention includes: a fan shroud spaced
apart from a rotation locus of an end of a rotary fan by a
predetermined gap; a shroud support for supporting the fan shroud;
and a porous damping material opposing to the end of the fan, the
porous damping material being attached to at least a part of the
fan shroud or forming a part of the fan shroud.
[0012] In the present description, the word "porous" refers to a
material having porosity, i.e. sponge-like material, which is
different from the perforated metal having a number of holes
drilled by press working.
[0013] In the present invention, since the porous damping material
is attached to the surface (inner circumference) of the fan shroud
opposing to the end of the fan to which the strong swirl is
generated by pasting, or the surface of the fan shroud opposing to
the end of the fan itself is made of the porous damping material,
the jet noise caused by the swirl can be damped by sound absorbing
properties of the porous damping material.
[0014] Further, since the conventional perforated metal is not
used, the cooling air does not bump into the hard step portion,
thus being unlikely to generate impulsive sound.
[0015] Accordingly, both of the impulsive sound and the jet noise
can be effectively damped and the noise between the end of the fan
and the fan shroud can be securely decreased.
[0016] The noise reduction mechanism of fan device according to the
present invention may preferably have a radiator provided to
upstream or downstream of the fan, a radiator hood and an end
plate, the radiator hood and the end plate air-tightly connecting
the radiator and the fan shroud.
[0017] According to the above arrangement, since the airtight space
surrounded by the radiator hood and the end plate works as a
damping space of the energy (pressure wave) of the noise, damping
properties can be improved. Further, since the radiator hood is
provided, the cooling air can flow more smoothly, so that the
radiator can exchange the heat more efficiently.
[0018] In the above noise reduction mechanism of fan device,
another porous damping material may preferably be attached to inner
circumference of the radiator hood and/or inner circumference of
the end plate.
[0019] Accordingly, since the porous damping material is attached
to the inner circumference of the radiator hood and the end plate,
the noise can be further decreased.
[0020] In the noise reduction mechanism of fan device according to
the present invention, a number of holes may preferably be formed
to the fan shroud with the porous damping material being
attached.
[0021] Accordingly, low-frequency noise can be effectively
decreased by forming the number of holes to the fan shroud.
[0022] In the noise reduction mechanism of fan device according to
the present invention, the fan shroud and/or the porous damping
material may preferably have bell-mouth shape.
[0023] According to the above arrangement, since the fan shroud
and/or the porous damping material have bell-mouth shape, the
cooling air can flow smoothly between the end of the fan and the
fan shroud or the porous damping material, so that the generated
jet noise can be reduced to further decrease the noise.
[0024] In the above, the porous damping material may have a cover
portion for covering a surface thereof opposing to the end of the
fan.
[0025] Accordingly, since the surface of the porous damping
material is covered with the cover portion, absorption of water can
be more securely prevented as compared to chemical water-repellant
treatment on the surface of the porous damping material. Further,
since the dust snapped by the fan does not bump into the porous
portion of the porous damping material, the porous damping material
can be prevented from being degraded and damaged, so that weather
resistance and durability can be improved.
[0026] Furthermore, since firmness of the porous damping material
can be improved by the cover portion and the porous damping
material is less likely to be flexed, the porous damping material
is more easily attached to the fan shroud by, for instance,
pasting, thus facilitating manufacture of the fan shroud.
[0027] In the noise reduction mechanism of fan device according to
the present invention, the fan shroud may preferably have a
protector for protecting at least one of upstream end and
downstream end of the porous damping material in an air flow
direction.
[0028] When the porous damping material is attached to the fan
shroud, the upstream and downstream end of the porous damping
material can be easily peeled off from the fan shroud by collision
with the dust snapped by the fan. However, since the protector can
prevent the collision of the dust, the porous damping material can
be effectively prevented from being peeled off.
[0029] In the above, the fan shroud may preferably have an engage
member for partially engaging the porous damping material.
[0030] Accordingly, since the engage member can maintain the
attachment of the porous damping material, the porous damping
material can be prevented from being peeled off from the fan
shroud, thus improving reliability.
[0031] The fan shroud may have openings respectively provided on
upstream and downstream side in the air flow direction and curved
in bell-mouth shape, and a parallel portion provided between the
openings, the parallel portion being parallel to the axis line
direction of rotation axis of the fan, and the porous damping
material may be attached to the parallel portion of the fan
shroud.
[0032] Accordingly, since the parallel portion of the fan shroud
forms the cylindrical portion having the same inner diameter, the
porous damping material can be attached to the cylindrical portion.
Therefore, it is not necessary that the porous damping material is
pressed to the curved portion for attachment, thus facilitating
attachment work.
[0033] In the above, the porous damping material may preferably
formed in a smooth shroud extending over a part of the bell-mouth
curved portion provided to upstream and downstream side in the air
flow direction.
[0034] According to the above arrangement, since a part of the
opening having the bell-mouth shape (i.e. a part of the bell-mouth
configuration) is formed by the porous damping material, even when
the portion made of the fan shroud itself is shortened by the
length of the portion made of the porous damping material, the
entire bell-mouth configuration can be maintained while keeping
width dimension (width in a direction parallel to the axis line) of
the porous damping material. Accordingly, the size of the fan
shroud can be reduced by the length of the shortened opening by the
fan shroud while securely maintaining the noise absorbing
properties.
[0035] A noise reduction mechanism of fan device according to
another aspect of the present invention includes: a fan shroud
spaced apart from a rotation locus of an end of a rotary fan by a
predetermined gap; a radiator provided on upstream or downstream of
the fan; a radiator hood and an end plate for air-tightly
connecting the radiator and the fan shroud; and a damping chamber
constituted of semi-closed space surrounded by the radiator hood,
the end plate and the fan shroud, the damping chamber being in
communication with an inside of the radiator hood through a
plurality of resonance pipe provided along circumferential
direction of the damping chamber.
[0036] According to the above arrangement, the porous damping
material attached to the fan shroud can decrease the noise composed
of jet noise and impulsive sound and the noise can be further
reduced by forming the semi-closed damping chamber.
[0037] In addition, since the damping chamber and the inside of the
radiator hood are intercommunicated by the resonance pipe, a
resonance frequency at the resonance pipe can be defined by
appropriately setting diameter and length of the resonance pipe,
volume of the damping chamber etc., so that noise having the same
specific frequency as the resonance frequency is resonated in the
resonance pipe, thus efficiently damping the noise energy.
[0038] Incidentally, in the above-described present invention, the
porous damping material is attached to an inner circumference of
the fan shroud (i.e. a portion confronting the rotation locus of
the end of the fan) for effectively damp the jet noise caused
between the fan shroud and the fan, thus securely reducing
noise.
[0039] The porous damping material is, for instance, formed in a
desired shape such as square cross section and size by cutting a
large foamed urethane resin by a hot wire or a cutting machine
having thin blade. The porous damping material having material
flexibility is attached to the fan shroud of various shapes
considering fan performance such as bell-mouth shape.
[0040] However, a lot of trouble is required for cutting the porous
damping material into a desired shape by the above-described
cutting machine.
[0041] Further, it is not economical to form the fan shroud into a
shape considering the fan performance such as the bell-mouth shape.
This is because, for instance, when the fan shroud is made of
metal, great die cost is necessary on account of large size press
die and, when the fan shroud is made of resin, the size of the
molding die is enlarged and cost thereof is significant.
[0042] Another object of the present invention is to provide a
noise reduction mechanism of fan device capable of being easily and
economically manufactured.
[0043] In order to attain the above object, the noise reduction
mechanism of fan device of the present invention employs the porous
damping material made of die molding.
[0044] Specifically, a noise reduction mechanism of fan device
according to the present invention has: a rotary fan; a fan shroud
spaced apart from a rotation locus of an end of the rotary fan by a
predetermined gap; a shroud support for supporting the fan shroud;
and a porous damping material opposing to the end of the fan, the
porous damping material being attached to at least a part of the
fan shroud or forming a part of the fan shroud, the porous damping
material being a die-molding product.
[0045] According to the above arrangement, since the porous damping
material is a die-molding product, desired final shape of porous
damping material can be easily obtained. Further, since the porous
damping material can be easily molded in any shape considering fan
performance such as bell-mouth shape, the fan shroud may be
configured in a simple shape considering convenience in
manufacture, so that conventionally required large press die or
molding die is no longer necessary.
[0046] In the noise reduction mechanism of fan device according to
the present invention, the porous damping material may preferably
be formed linearly in a longitudinal direction thereof and may
preferably be curved along the circumference of the fan shroud.
[0047] According to the above arrangement, the porous damping
material may be molded in a linear elongated shape and cut into any
desired length, so that the porous damping material can be easily
applied to fan shrouds having different diameter.
[0048] In the noise reduction mechanism of fan device according to
the present invention, the porous damping material may preferably
be curved in a longitudinal direction thereof and be provided along
the circumference of the fan shroud.
[0049] According to the above arrangement, the porous damping
material may be molded in a curved shape in accordance with the
diameter of the fan shroud, so that the porous damping material can
be easily attached.
[0050] In the noise reduction mechanism of fan device according to
the present invention, the porous damping material may preferably
be constituted of a plurality of porous member provided along the
circumference of the fan shroud.
[0051] According to the above arrangement, since the porous damping
material is composed of the plurality of short porous member, the
size of the die required for molding can be reduced, thus
decreasing die cost. Further, since the porous member is short,
transportation and storage thereof can be facilitated.
[0052] In the noise reduction mechanism of fan device according to
the present invention, a configuration of the porous damping
material confronting the end of the fan may preferably be a
bell-mouth shape on both upstream side and downstream side of the
fan shroud.
[0053] According to the above arrangement, the frequency of the fan
can be lowered corresponding to increase in wind flow, thus further
reducing noise.
[0054] In the noise reduction mechanism of fan device according to
the present invention, the porous damping material may preferably
be held on the fan shroud and/or the support by a belt-shaped
dropout prevention means.
[0055] According to the above arrangement, the porous damping
material is securely held by the dropout prevention means and,
since the dropout prevention means is belt-shaped, the dropout
prevention means may be wound around the porous damping material or
the fan shroud, thus facilitating attachment work.
[0056] In the noise reduction mechanism of fan device according to
the present invention, the porous damping material may preferably
be held on the fan shroud and/or the support by a net-shaped
dropout prevention means.
[0057] According to the above arrangement, the porous damping
material can be also securely held by the dropout prevention means.
Further, since the dropout prevention means is net-shaped, the
entire porous damping material can be securely held, thus greatly
improving dropout prevention effect.
[0058] On the other hand, since the porous damping material
directly confronts the fan, the porous damping material can be
deteriorated or damaged by colliding with dust or rainwater snapped
by the fan, thus deteriorating weather-resistance and durability of
the porous damping material.
[0059] Accordingly, the resin sheet or the cloth sheet made of
various material is attached on the surface of the porous damping
material by adhesion or thermal bonding to prevent the surface of
the porous damping material from foreign body, thus improving
weather-resistance and durability.
[0060] However, attachment work of the resin sheet or the cloth
sheet onto the surface of the porous damping material by adhesion
or thermal bonding is not easy and requires a lot of work, thus
deteriorating productivity.
[0061] Further object of the present invention is to improve
weather-resistance and durability of porous damping material used
for the noise reduction mechanism of fan device.
[0062] In order to attain the above object, the present invention
employs molding method of the porous damping material by
die-molding.
[0063] Specifically, according to the present invention, a molding
method of a porous damping material used for a noise damping
mechanism of a fan device having: a rotary fan; a fan shroud spaced
apart from a rotation locus of an end of the rotary fan by a
predetermined gap; a shroud support for supporting the fan shroud;
and a porous damping material opposing to the end of the fan, the
porous damping material being attached to at least a part of the
fan shroud or forming a part of the fan shroud, the method is
characterized in having the steps of: disposing a foam material
having larger volume than a cavity of a die while being elastically
deformed; and heating the die to mold the foam material into the
porous damping material.
[0064] The "cavity" referred herein is a portion having a volume of
a final configuration of the porous damping material.
[0065] According to the above arrangement, since the foam material
is disposed in the cavity while being compressed, the contact area
against the cavity surface is enlarged on the surface of the foam
material on account of dense foam. When the die is heated under the
above condition, the heat is efficiently transmitted to the dense
portion, so that the surface of the foam material is securely
melted to securely mold the final configuration of the porous
damping material. At this time, thin rigid layer is easily formed
on the surface of the foamed material, which efficiently functions
as a protection layer. Accordingly, the porous damping material can
be effectively protected from the dust and rainwater snapped by the
fan, thus improving weather-resistance and durability.
[0066] In the molding method of the porous damping material
according to the present invention, the porous damping material may
preferably be constituted of a plurality of porous member provided
along the circumference of the fan shroud, the porous damping
material being molded by the foam material using the die.
[0067] As mentioned above, according to the above arrangement,
since the size of the die required for molding can be reduced, thus
reducing die cost and facilitating transportation and storage of
the porous member.
BRIEF DESCRIPTION OF THE DRAWINGS
[0068] FIG. 1 is an entire view schematically showing the noise
reduction mechanism of fan device according to first
embodiment;
[0069] FIG. 2 is an enlarged cross section showing a primary
portion of second embodiment according to the present
invention;
[0070] FIG. 3 is an enlarged cross section showing a primary
portion of second embodiment according to the present
invention;
[0071] FIG. 4 is an enlarged cross section showing a primary
portion of third embodiment according to the present invention;
[0072] FIG. 5 is an enlarged cross section showing a primary
portion of fourth embodiment according to the present
invention;
[0073] FIG. 6 is an enlarged cross section showing a primary
portion of fifth embodiment according to the present invention;
[0074] FIG. 7 is an enlarged cross section showing a primary
portion of sixth embodiment according to the present invention;
[0075] FIG. 8 is an enlarged cross section showing a primary
portion of seventh embodiment according to the present
invention;
[0076] FIG. 9 is an enlarged cross section showing a primary
portion of eighth embodiment according to the present
invention;
[0077] FIG. 10 is an enlarged cross section showing a primary
portion of ninth embodiment according to the present invention;
[0078] FIG. 11 is an enlarged cross section showing a primary
portion of tenth embodiment according to the present invention;
[0079] FIG. 12 is an enlarged cross section showing a primary
portion of eleventh embodiment according to the present
invention;
[0080] FIG. 13 is an enlarged cross section showing a primary
portion of twelfth embodiment according to the present
invention;
[0081] FIG. 14 is a cross section showing first modification of the
present invention;
[0082] FIG. 15 is a cross section showing second modification of
the present invention;
[0083] FIG. 16 is a cross section showing third modification of the
present invention;
[0084] FIG. 17 is a cross section showing fourth modification of
the present invention;
[0085] FIG. 18 is a cross section showing fifth modification of the
present invention;
[0086] FIG. 19 is a cross section showing sixth modification of the
present invention;
[0087] FIG. 20 is a cross section showing seventh modification of
the present invention;
[0088] FIG. 21 is a cross section showing eighth modification of
the present invention;
[0089] FIG. 22 is a cross section showing ninth modification of the
present invention;
[0090] FIG. 23 is a cross section showing tenth modification of the
present invention;
[0091] FIG. 24 is a cross section showing eleventh modification of
the present invention; and
[0092] FIG. 25 is a cross section showing twelfth modification of
the present invention.
[0093] FIG. 26 is an enlarged cross section showing a primary
portion of a noise reduction mechanism of a fan device according to
thirteenth embodiment of the present invention;
[0094] FIG. 27 is an entire perspective of a component of the
thirteenth embodiment;
[0095] FIG. 28 is a further enlarged perspective of the primary
portion of the thirteenth embodiment;
[0096] FIG. 29(A), FIG. 29(B) and FIG. 29(C) are cross sections for
illustrating a molding method of the thirteenth embodiment;
[0097] FIG. 30 is a cross section showing the thirteenth
modification of the present invention;
[0098] FIG. 31 is a cross section showing the fourteenth
modification of the present invention;
[0099] FIG. 32 is a cross section showing the fifteenth
modification of the present invention;
[0100] FIG. 33 is a cross section showing the sixteenth
modification of the present invention;
[0101] FIG. 34 is an entire cross section showing the eighteenth
modification of the present invention;
[0102] FIG. 35 is a perspective showing the nineteenth modification
of the present invention; and
[0103] FIG. 36 is a perspective showing the twentieth modification
of the present invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENT(S)
[0104] [First Embodiment]
[0105] First embodiment of the present invention will be described
below with reference to attached drawings.
[0106] FIG. 1 is an entire view schematically showing the noise
reduction system of fan device according to the first embodiment
applied to an engine cooling system 1 of construction equipment
such as excavator, and FIG. 2 is an enlarged view showing primary
portion of the noise reduction mechanism.
[0107] The engine cooling system 1 circulates coolant between an
engine 2 and a radiator 3 and cools the engine 2 by the coolant
whose heat is exchanged by the radiator 3. A fan 4 for sucking in
cooling air for heat exchange from the outside is disposed between
the engine 2 and the radiator 3, the fan 4 being rotated by power
transmitted from a crank shaft of the engine 2 through a pulley and
a fan belt.
[0108] An oil cooler 6 is disposed on further upstream side
(upstream side of the cooling air flow direction) of the radiator 3
(see FIG. 1) and engine oil is circulated between a hydraulic
circuit of a hydraulic machinery (not shown) and the oil cooler 6,
so that the engine oil whose heat is exchanged by the oil cooler 6
cools and lubricates the engine 2. However, the oil cooler 6 may be
provided as necessary.
[0109] A radiator hood 10, a fan shroud 20 and a cover hood 30
respectively made of sheet metal are disposed on the downstream
side of the radiator 3. The cover hood 30 is composed of an engine
cover 31 covering the above-described pulley and fan belt and
semicircle-base shaped outer cover 32 provided above the engine
cover 31, these members forming flow channel of the cooling
air.
[0110] The radiator hood 10 is configured in a square pipe and
partial cylinder having an outer fringe 12 provided to a downstream
end thereof, and is fixed to the radiator 3 by bolts and nuts at
upstream side thereof. A flat perpendicular end plate 13 is fixed
to the outer fringe 12 by bolts and nuts, and the cylindrical fan
shroud 20 is fixed to a large opening provided at the center of the
end plate 13 by welding etc. In short, the end plate 13 shuts the
gap between the radiator hood 10 and the fan shroud 20 and also
works as a shroud support for supporting the fan shroud 20.
[0111] The fan shroud 20 is spaced apart from a rotation locus of
the end of the fan 4 by a predetermined gap, and is composed of an
upstream opening 21 being open in a bell-mouth shape toward
upstream side and a downstream opening 22 being open in a
bell-mouth shape toward downstream side with the end plate 13
approximate border thereof. The bell-mouth configuration of the
respective openings 21 and 22 allows smooth flow of the cooling air
between the end of the fan 4 and the fan shroud 20.
[0112] As shown in enlarged illustration of FIG. 2, a porous
damping material 40 made of synthetic resin such as foamed urethane
resin and polyethylene terephtalate (PET) is attached to inner
circumference of the fan shroud 20 without using perforated metal
and is exposed on substantially the whole surface while keeping the
bell-mouth configuration of the fan shroud 20, thus reducing jet
noise and impulsive sound caused between the end of the fan 4 and
the fan shroud 20. In the present embodiment, the damping material
40 is one of the significant features as the noise reduction
mechanism of the present invention.
[0113] Surface of the damping material 40 is water-repellant by
chemical treatment etc., thus protecting the surface from rainwater
sucked in with the cooling air to improve weather resistance of the
damping material 40.
[0114] In the fan shroud 20, the upstream opening 21 extends wider
than the downstream opening 22 to be open to inside of the radiator
hood 10. Upstream peripheral end of the upstream opening 21 is
proximal to inner circumference of the radiator hood 10 having the
square pipe and partial cylindrical configuration at four sections
(four sections of up, down, right and left viewing from the front)
in circumferential direction.
[0115] As a result, the space surrounded by the radiator hood 10,
the end plate 13, the upstream opening 21 of the fan shroud 20
intercommunicates with the inside of the radiator hood 10 through
the gap 51 (see FIG. 2), thus forming substantially closed damping
chamber 50. The damping chamber 50 is also one of significant
features as the noise reduction mechanism of the present
invention.
[0116] On the other hand, damping materials 41 and 42 are attached
to the outside of the engine cover 31 and inside of the outer cover
32 constituting the cover hood 30 (see FIG. 1), thus reducing jet
noise of the cooling air passing through the fan shroud 20.
Incidentally, the cover hood 30 is not requisite for the present
invention, which may be provided as necessary.
[0117] In the present embodiment, the fan 4 is driven by the engine
2 to suck in the cooling air from the outside of the engine room 5
as shown in arrow in FIG. 1.
[0118] The sucked cooling air passes through the oil cooler 6 to
exchange heat with the hydraulic oil of the hydraulic machinery
and, subsequently, passes through the radiator 3 to exchange heat
with the coolant. Thereafter, the sucked cooling air is sent to the
engine 2 sequentially through the radiator hood 10, the fan shroud
20 and the cover hood 30 and is finally discharged to the outside
of the engine room 5.
[0119] At this time, the noise in accordance with the rotation of
the fan 4 is reduced by the damping chamber 50 in the radiator hood
10 and by damping materials 40 to 42 in the fan shroud 20 and the
cover hood 30.
[0120] According to the above-described embodiment, following
effects can be obtained.
[0121] 1) Since the porous damping material 40 is attached to the
whole inner circumference of the fan shroud 20 opposing to the end
of the fan 4 while being exposed to the opposed space, the jet
noise caused by the strong swirl between the fan 4 and the fan
shroud 20 can be damped by the damping material 40.
[0122] 2) Since the conventional perforated metal is not used, the
cooling air does not bump into the hard step portion, thus unlikely
to cause impulsive sound.
[0123] 3) Both of the impulsive sound and the jet noise in
accordance with the rotation of the fan 4 can be effectively damped
by the above 1) and 2), thus securely reducing the noise between
the end of the fan 4 and the fan shroud 20.
[0124] 4) The upstream opening 21 of the fan shroud 20 extends
proximal to the inside of the radiator hood 10 and the space
surrounded by the upstream opening 21, the radiator hood 10 and the
end plate 13 forms the substantially closed damping chamber 50 in
communication with the inside of the radiator hood 10 through the
small gap 51. Accordingly, the damping effect of the damping
chamber 50 can be enhanced and the noise can be more securely
reduced since the noise energy (pressure wave) transmitted from the
fan 4 to the upstream can be largely damped in the damping chamber
50, thus more securely reducing the noise.
[0125] 5) Since the fan shroud 20 is open to both of the upstream
side and the downstream side in bell-mouth shape, the cooling air
can flow smoothly between the end of the fan 4 and the fan shroud
20, thus enhancing damping effect of the noise.
[0126] 6) Since the damping materials 41 and 42 are attached to the
cover hood 30 disposed to the downstream side of the fan 4 to be
exposed to the flow channel of the cooling air, the noise energy
transmitted from the fan 4 to the downstream can be damped by the
damping materials 41 and 42, thus further reducing the noise.
[0127] 7) Since the surface of the damping materials 40, 41 and 42
is water-repellant on account of chemical treatment or the like,
the damping materials 40, 41 and 42 are less likely to be
significantly degraded by water such as rain sucked with the
cooling air, thus improving weather resistance of the damping
materials 40, 41 and 42.
[0128] 8) Since the cooling air can be smoothly sucked in because
the radiator hood 10 is disposed between the radiator 3 and the fan
shroud 20, the heat exchange by the oil cooler 6 and the radiator 3
can be enhanced and the cooling efficiency of the engine 2 can be
improved.
[0129] Further, since the cooling water can smoothly flow to the
engine 2 by providing the cover hood 30, the cooling air can be
further efficiently sucked in.
[0130] Other preferred embodiments of the present invention will be
described below with reference to attached drawings. Incidentally,
the same reference numeral is attached to the same or corresponding
components as the above-described first embodiment to omit or
simplify the description thereof. Further, the portions not
illustrated in the drawings have the same configuration as the
first embodiment and the description thereof is omitted.
[0131] [Second Embodiment]
[0132] FIG. 3 schematically shows a primary portion of the noise
reduction mechanism of fan device according to second embodiment of
the present invention.
[0133] The present embodiment differs from the first embodiment in
that a number of holes 23 is drilled to the fan shroud 20 and that
the upstream opening 21 of the fan shroud 20 is brought further
proximal to the inside of the radiator hood 10 to improve degree of
enclosure of the damping chamber 50.
[0134] According to the present embodiment, following effects can
be obtained as well as the effects 1) to 8) of the first
embodiment.
[0135] 9) Since the number of holes 23 is drilled to the fan shroud
20, low-frequency noise of the noise generated during rotation of
the fan 4 that easily transmits through the damping material 40 can
be reduced by the upstream opening 21. This is because the
low-frequency noise can be effectively damped by the holes 23 and
the damping chamber 50 in communication with the holes 23 when the
low-frequency noise reaches the fan shroud 20.
[0136] [Third Embodiment]
[0137] FIG. 4 shows the third embodiment of the present invention,
where damping material 43 is attached to the whole inner
circumference of the radiator hood 10 in addition to the
arrangement of the second embodiment.
[0138] According to the present embodiment, following effect as
well as the above effects 1) to 9) can be obtained.
[0139] 10) The noise can be damped at a larger area on the upstream
side of the fan 4 by the damping material 43 attached to the inside
of the radiator hood 10, thus enhancing damping effect.
[0140] [Fourth Embodiment]
[0141] FIG. 5 shows fourth embodiment of the present invention,
where damping material 44 is attached to the whole inner
circumference of the radiator hood 10 and inside of the end plate
13 in addition to the arrangement of the first embodiment.
Incidentally, the damping material 43 attached to the radiator hood
10 and the damping material 44 attached to the end plate 13 may be
independently provided or integrally formed.
[0142] When the respective damping materials 43 and 44 are
independently provided, the members 10 and 13 can be connected
after the damping materials 43 and 44 are attached to the radiator
hood 10 and the end plate 13 respectively. When the damping
materials are integrated, the damping materials 43 and 44 can be
attached after the respective members 10 and 13 are assembled.
[0143] According to the present embodiment, following effect as
well as the effects 1) to 8) and 10) can be obtained.
[0144] 11) Since the damping material 44 is attached to the inner
circumference of the end plate 13, the noise can be damped by
approximate entire area of the inside of the radiator hood 10, thus
further enhancing the damping effect. Further, since an inner
circumference of the damping chamber 50 is formed by a large
surface from which the damping material 44 is exposed, the noise
can be effectively damped in the damping chamber 50.
[0145] [Fifth Embodiment]
[0146] FIG. 6 shows the fifth embodiment of the present invention,
where hole 14 is drilled to circumference of the radiator hood 10
in addition to the arrangement of the fourth embodiment.
[0147] According to the present embodiment, following effect as
well as the effects 1) to 8), 10) and 11) can be obtained.
[0148] 12) The low-frequency noise can be further damped at a
larger upstream side of the fan 4 by the hole 14 drilled on the
radiator hood 10.
[0149] [Sixth Embodiment]
[0150] FIG. 7 shows the sixth embodiment of the present invention,
where hole 15 is drilled to the end plate 13 in addition to the
arrangement of the fifth embodiment.
[0151] According to the present embodiment, following effects as
well as the effects 1) to 8), and 10) to 12) can be obtained.
[0152] 13) The low-frequency noise can be further damped at
substantially the whole upstream side of the fan 4 by the hole 15
drilled to the end plate 13, especially in the damping chamber
50.
[0153] [Seventh Embodiment]
[0154] FIG. 8 shows the seventh embodiment of the present
invention.
[0155] The present embodiment differs from the first embodiment in
that the fan shroud 20 is composed only of the downstream opening
22. Accordingly, the fan shroud 20 does not extend to the inside of
the radiator hood 10 and the damping chamber 50 (see FIGS. 2 to 7)
is not provided.
[0156] According to the present embodiment, since the fan shroud 20
is composed only of the downstream opening 22 and the damping
chamber 50 is not provided, the effects 4) and 5) among the effects
of 1) to 8) of the first embodiment can not be sufficiently
achieved.
[0157] However, the noise can be damped to some degree by a space
52 surrounded by the radiator hood 10 and the end plate 13.
Incidentally, the end plate 13 may be omitted and the radiator hood
10 may be formed in bell-mouth shape to be consecutive with the fan
shroud 20 as shown in single dotted line in FIG. 8, for the fan
shroud 20 not extend to the inside of the radiator hood 10.
[0158] Since the downstream opening 22 has bell-mouth shape, the
cooling air can flow more smoothly as compared to an arrangement
where the fan shroud 20 extends horizontally toward the downstream
as shown in double-dotted line in FIG. 8 or an arrangement where
the opening linearly widens toward downstream, thus damping the
noise.
[0159] [Eighth Embodiment]
[0160] FIG. 9 shows the eighth embodiment of the present
invention.
[0161] The present embodiment differs from the first embodiment in
that upstream peripheral end of the upstream opening 21 of the fan
shroud 20 is connected on the whole circumference of the inside of
the radiator hood 10 and a plurality of resonance pipe 24 is
provided along the circumferential direction of the upstream
opening 21. Accordingly, the damping chamber 50 is semi-closed and
is in communication with the inside of the radiator hood 10 only by
the plurality of the resonance pipe 24.
[0162] According to the present embodiment, following effect as
well as the effects 1) to 8) of the first embodiment can be
obtained.
[0163] 14) Since the inside of the radiator hood 10 is in
communication with the inside of the damping chamber 50 by the
plurality of the resonance pipe 24, diameter, length, volume etc.
of the resonance pipe 24 can be appropriately determined to define
the resonance frequency of the resonance pipe 24, so that the noise
having the same specific frequency as the resonance frequency can
be resonated by the resonance pipe, thus efficiently damping the
noise energy and improving the damping effect.
[0164] Further, since the damping chamber 50 is semi-closed, the
damping effect in the damping chamber can be further improved.
[0165] [Ninth Embodiment]
[0166] FIG. 10 shows the ninth embodiment of the present
invention.
[0167] In the present embodiment, fan shroud 60 itself is formed of
a porous damping material and the surface opposing the end of the
fan 4 is formed in a bell-mouth shape. A slit 61 being cut to the
inside is provided to the outer circumference of the fan shroud 60
and an inner periphery of the end plate 13 having reverse T-shape
cross section (T-shape cross section in the down side) is inserted
to the slit 61 and the fan shroud 60 is fixed to the end plate 13
by adhesion or the like. The other arrangement is the same as the
first embodiment.
[0168] In the present embodiment, since the fan shroud 60 itself is
made of porous damping material, the effects 1) to 3) described in
the first embodiment can be similarly obtained and the object of
the present invention can be attained. Further, when the fan shroud
60 is configured into, for instance, crescent shape to get the
upstream periphery closer to the inner circumference of the
radiator hood 10, the degree of enclosure of the damping chamber 50
is increased and the aforesaid effect 4) can be obtained. Further,
effects 5) to 8) can be obtained by the similar arrangement.
[0169] [Tenth Embodiment]
[0170] The tenth embodiment will be described below with reference
to FIG. 11.
[0171] Fan shroud 70 according to the present embodiment has the
end plate 13 consecutively formed at an end thereof and the entire
shroud is contained in the radiator hood 10.
[0172] The upstream side and the downstream side of the fan shroud
70 are upstream opening 71 and downstream opening 72 being open in
curved bell-mouth shape, the upstream opening 71 and the downstream
opening 72 being connected to a parallel portion 73 being parallel
(parallel in cross section) to the axis line of rotation axis (not
shown) of the fan 4. The parallel portion 73 is formed by an inner
circumference of a recessed groove 74 provided consecutively along
the circumferential direction of the fan shroud 20.
[0173] A porous damping material 80 is disposed in the recessed
groove 74. Surface of the porous damping material 80 opposing the
fan 4 is a flat portion 81 parallel to the parallel portion 73 and
substantially consecutive with the surface of openings 72 and 73 on
both sides. Upstream and downstream end portion 82 of the damping
material 80 is covered with elevational portion 75 of the recessed
groove 74, so that dust drawn into the fan shroud 20 does not bump
into the end portion 82 of the damping material 80 even when the
dust is snapped by the fan 4. In other words, the elevational
portion 75 of the recessed groove 74 forms a protector of the
present invention.
[0174] As in the above-described damping material 40, the damping
material 80 is made of synthetic resin such as urethane resin and
polyethylene terephtalate and has a layered cover portion 83 on the
flat portion 81 side.
[0175] Material of the cover portion 83 is selected from resin
sheet of acrylic resin, cloth sheet woven from polyester resin
fiber or aluminum glass fiber etc. considering influence on damping
ability of the damping material 80 and required weather resistance
and durability, and the selected material is adhered or thermally
bonded to the damping material 80. The cover portion 83 is superior
in water-proofness to water-repellant processing of the surface of
the damping material 80 and is harder than the porous portion of
the damping material 80 and has enough strength not to be easily
damaged by collision with the dust snapped by the fan 4.
[0176] Thickness of the cover portion 83 is 10 to 200 .mu.m, for
instance, in engine cooling system of construction equipment,
though different from the material of the cover portion 83 and the
damping material 80 and the required characteristic.
[0177] Incidentally, the parallel portion 73 of the damping
material 80 itself may be treated by chemical or heat to form the
layered cover portion (cover layer) having approximately the same
thickness. Further, the cover portion according to the present
invention may be completely exposed to the fan 4 side or,
alternatively, may be formed on a middle layer portion adjacent to
the exposed surface.
[0178] Following effects as well as the above-described effects 1)
to 5), 10) and 11) can be obtained according to the present
embodiment.
[0179] 15) Since the surface of the damping material 80 is superior
in water-proofness and is covered with the cover portion 83 having
superior strength, absorption of rainwater sucked into the fan
shroud can be securely prevented and the damping material 80 does
not easily break by collision against the dust snapped by the fan
4, thus preventing the dust from directly bumping into the porous
portion of the damping material 80. Accordingly, degradation and
damage of the damping material 80 on account of water and dust can
be prevented, thus improving weather resistance and durability.
[0180] 16) Since the cover portion 83 is hard to some extent,
firmness of the damping material 80 can be improved, thus making
the damping material 80 difficult to be flexed. Accordingly, the
damping material 80 can be easily fitted into the recessed groove
74 of the fan shroud 70, thus facilitating production of the fan
shroud 20.
[0181] 17) Since it is only necessary that the damping material 80
is attached to the flat parallel portion 73 of the recessed groove
74, the damping material 80 is unlikely to be partially detached as
compared to attaching the damping material to a curved surface, so
that the damping material 80 can be securely and easily attached to
the parallel portion 73, thus facilitating production of the fan
shroud 20.
[0182] 18) Since the damping material 80 is disposed in the
recessed groove 74 of the fan shroud 70 and the upstream and
downstream end portion 82 of the damping material 80 is concealed
by the elevational portion 75 of the recessed groove 74, the end
portion 82 can be prevented from peeled off from the fan shroud 70,
thus further improving the durability of the damping material
80.
[0183] 19) Since the surface opposing the end of the fan 4 is the
flat portion 81 parallel to the axis line direction, gap (tip
clearance) of the narrow area between the fan 4 and the damping
material 80 can be set wider in width direction of the damping
material 80 as compared to an arrangement where the whole damping
material 80 is curved. Accordingly, since the damping material 80
is proximal to the end of the fan 4 in large area in the width
direction, the jet current in accordance with the swirl can be
efficiently damped, thus improving damping effect.
[0184] [Eleventh Embodiment]
[0185] The eleventh embodiment will be described below with
reference to FIG. 12.
[0186] In the present embodiment, upstream and downstream openings
76 and 77 of the fan shroud 70 are smaller than the openings 71 and
72 of the tenth embodiment (see FIG. 11).
[0187] The surface of the damping material 80 opposing the end of
the fan 4 is composed of flat portion 81 and upstream curved
portion 84 and downstream curved portion 85 provided on both sides
of the flat portion 81, the respective curved portions 84 and 85
being level and consecutive with the surface of the openings 76 and
77.
[0188] Combined size of the upstream curved portion 84 and the
upstream opening 76 is substantially the same as the upstream
opening 71 shown in FIG. 11. Entirety of the curved portion 84 and
the opening 76 forms the upstream bell-mouth shape opening of the
present invention.
[0189] The combined size of the downstream curved portion 85 and
the downstream opening 77 is substantially the same as the
downstream opening 72 shown in FIG. 11. Entirety of the curved
portion 85 and the opening 77 forms the downstream bell-mouth
opening of the present invention.
[0190] Further, the damping material 80 of the present embodiment
has the cover portion 83 to improve weather resistance and
durability.
[0191] The other arrangement is the same as the tenth
embodiment.
[0192] According to the present embodiment, following effects can
be obtained as well as above effects of 1) to 5), 10), 11) and 15)
to 19).
[0193] 20) In the present embodiment, though the entire size of the
bell-mouth portion of the fan shroud 70 is substantially the same
as the tenth embodiment, the curved openings 76 and 77 of the fan
shroud 70 are smaller and a part of the bell-mouth portion is
formed by the curved portions 84 and 85 of the damping material 80,
so that width W2 of the fan shroud 70 of the present embodiment can
be smaller than the width W1 shown in FIG. 11 with the same width w
of the damping material 80 to maintain the damping property, thus
reducing the size of the fan shroud 70 and the radiator hood
10.
[0194] [Twelfth Embodiment]
[0195] In the twelfth embodiment shown in FIG. 13, the whole fan
shroud 70 has bell-mouth shape and a recessed groove 74 curved
along the upstream opening 71 and the downstream opening 72 is
provided thereto. The recessed groove 74 is a groove having
so-called "lip", which has two projections 74A consecutive along
the circumferential direction on the opening side of the recessed
groove 74, the projection 74A engaging the damping material 80. In
other words, the projections 74A forms the engage member according
to the present invention.
[0196] Cover portion 83 is formed on a surface of the damping
material 80 and the surface is level with the surface of the
openings 71 and 72 of the fan shroud 70 including the projections
74A.
[0197] Incidentally, though the thickness of the projections 74A
and the cover portion 83 is the same in FIG. 13, the thickness may
be independently defined and not necessarily the same.
[0198] Following effect can be obtained in the present embodiment
in addition to the effects 1) to 5), 10), 11), 15), 16) and
18).
[0199] 21) Since the projections 74A for engaging the damping
material 80 is provided to the fan shroud 70, the damping material
80 is not likely to be peeled off from the recessed groove 74, thus
maintaining good attachment of the damping material 80 to improve
reliability.
[0200] [Modifications]
[0201] Incidentally, the noise reduction mechanism of fan device
according to the present invention is not restricted to the
above-described embodiment but includes other arrangements as long
as an object of the present invention can be achieved, and
following modifications are also included in the scope of the
present invention.
[0202] For instance, though the fan shrouds 20 and 70 of first to
eighth and tenth to twelfth embodiments are configured in
bell-mouth shape by the curved openings 21, 22, 71 and 72, the fan
shroud according to the present invention may have linearly widened
upstream and downstream openings 21 and 22 as shown in FIG. 14 (the
first modification), and parallel portion 25 may be provided
between the openings. In this case, though the effect 5) described
in the first embodiment may not be sufficiently performed, the
other effects 1) to 4) and 6) to 8) can be also attained.
[0203] The fan shroud may be configured to have the same size in
the upstream opening and the downstream opening or may be
cylindrical composed only of the parallel portion 25 as shown in
FIG. 15 (second modification). Further alternatively, the fan
shroud may be composed only of linear opening 21 extending into the
upstream radiator hood 10 as shown in FIG. 16 (third modification)
or may be composed only of linear opening 22 extending toward
downstream as shown in FIG. 17 (fourth modification). In this case,
the damping chamber 50 or the space 52 can be formed by the space
surrounded by the radiator hood 10, the end plate 13 and the fan
shroud 20.
[0204] Further, the fan shroud may have a configuration shown in
double-dotted line in FIG. 8. The above arrangement is also
included in the present invention by attaching the damping material
to the fan shroud.
[0205] The configuration of the radiator hood is also defined in
any manner, and the radiator hood may be formed in bell-mouth shape
consecutive with the fan shroud shown in single-dotted line in FIG.
8.
[0206] Though the upstream opening 21 of the fan shroud 20 extends
farther toward the upstream side to increase degree of enclosure of
the damping chamber, the size of the upstream opening 21 may be
arranged to be substantially the same as or smaller than the
downstream opening 22 and a separate adjusting member 16 may be
provided to inner circumference of the radiator hood 10 to enhance
degree of enclosure of the damping chamber 50, as shown in FIG. 18
(fifth modification). At this time, the damping material 45 may
preferably be attached to the adjusting member 16.
[0207] Though the end plate 13 directly fixed to the radiator hood
10 side is used in the above-described respective embodiments, the
end plate 13 may be fixed to the upstream side of the cover hood 30
supported at the engine 2 side and the end plate 13 may be abutted
to the radiator hood 10 through the damping material 46 etc.
working also as a sealing member. In other words, the end plate of
the present invention is only required to be provided to fan side
of the radiator hood and may be fixed to any member.
[0208] When the end plate 13 and the fan shrouds 20 and 70 are
formed as independent body, these components may be connected by
bolts and nuts as well as integrating by welding etc.
[0209] Further, the fan shroud may be supported by the end plate or
other support member independent from the end plate. However, the
end plate preferably works also as the support member in economical
viewpoint, since the support member is not necessary to be provided
as an independent component.
[0210] The fan shroud 20 and damping material 40 shown in FIG. 20
(seventh embodiment) is included in the scope of the present
invention. In other words, the fan shroud 20 is a cylinder having
the same inner diameter on the whole and is not formed in
bell-mouth shape, the inner shape of the damping material 40 itself
is bell-mouth shape.
[0211] The material of the radiator hood, the fan shroud, the end
plate is not restricted to metal but may be resin.
[0212] The porous damping material is not restricted to foamed
urethane resin and PET (polyethylene terephtalate) but any porous
material having damping property can be used. Such damping material
is, for instance, porous PTFE (polytetrafluoroethylene), foamed FEP
(fluorinated ethylene propylene) having superior weather resistance
and heat resistance as well as damping property. However, foamed
urethane resin is more preferable in view of inexpensiveness and
good damping property.
[0213] Further, the damping material is not restricted to
single-layered material but may have a plurality of layer. In this
arrangement, the damping material proximal to the exposed surface
preferably has smaller hole diameter for further efficiently
reducing the noise. Incidentally, such layer is for improving the
damping effect, which is different from the cover portion described
in the tenth embodiment etc.
[0214] In the arrangement of the first embodiment, the combination
of holes 14, 15 and 23 and attachment of the damping material 43
and 44 to either one of the radiator hood 10 and the end plate 13
can be decided in any manner, which is not restricted to
combinations shown in the second to seventh embodiments. For
instance, though not shown, the damping material may be attached
only to the end plate and not to the radiator hood. Alternatively,
the damping material may be attached to both of the radiator hood
and the end plate and the hole may be drilled only to the end
plate. Incidentally, the portion onto which the hole is drilled is
preferably covered with the damping material on flow channel side
of the cooling water in order to prevent the impulsive sound.
[0215] The cover portion for improving weather resistance and
durability may be formed on the damping material 40 of first to
eighth embodiments and first to seventh modifications, and the
damping materials 41 to 46 shown in respective figures may have the
cover portion.
[0216] Further, the end portion of the damping material 40 to 46
may be protected by the protector as necessary, and may be
prevented from falling off from the radiator hood 10, the fan
shroud 20 and the cover hood 30 using the engage member.
[0217] FIG. 21 shows an example where the bell-mouth shape of the
fan shroud 70 extends along the thickness portion on upstream end.
According to the arrangement, the cooling air on the upstream can
be more smoothly sucked in, thus reducing further noise and
improving cooling efficiency. Incidentally, the bell-mouth portion
may extend over the downstream thickness portion, so that the
cooling air can be smoothly flowed out on the downstream side.
[0218] The protector according to the present invention is not
restricted to the elevational portion 75 of the recessed groove 74
described in the tenth to twelfth embodiments. For instance, the
end portion of the damping material may be protected by a circular
member fixed along the peripheral direction of the fan shroud.
Specific shape of the protector may be defined in any manner for
implementation.
[0219] FIGS. 22 to 24 show modifications of engage member according
to the present invention.
[0220] In FIG. 22, the recessed groove 74 is a dovetail groove,
which is open to be narrowed toward the fan 4. In the recessed
groove 74, the slanting elevational portion 75 as the protector
works also as the engage member and the damping material 80 does
not come off from the fan shroud 70 being engaged with the
elevational portion 75. Angle .theta. of the elevational portion 75
is not restricted as long as the damping material 80 does not come
off, which is preferably 10 to 30 degrees.
[0221] FIG. 23 shows an independent annular member 78 as the engage
member fixed to ends of the upstream and downstream side by vis
etc. and the damping material 80 is engaged by a portion projecting
toward the recessed groove 74 of the annular member 78.
[0222] FIG. 24 shows an example where rivet 79 made of synthetic
resin is used as the engage member. The rivet 79 pierces the
cylindrical member 79A for securing thickness of elastic damping
material 80.
[0223] Incidentally, any configuration can be used for the engage
member, which is not restricted to the above. For instance, a
plurality of circumferential portions of the damping material 80
may be engaged using a piece-shaped bracket. Further, when the
damping material is not contained in the recessed groove 74, the
damping material may be engaged using a proper annular member,
bracket, rivet and the like.
[0224] Further, the end configuration of the fan according to the
present invention is not restricted to the specific configuration
described in the above embodiments and the modifications, but may
be configured as shown in FIG. 25.
[0225] The end of the fan 4 shown in FIG. 25 is curved to be
recessed in the middle along the shape of the fan shroud 70, so
that the gap between the end of the fan 4 and the fan shroud 70
(including the porous damping material 40) becomes constant. Such
arrangement is also included in the present invention in that the
damping material 40 is attached to the fan shroud 70 and noise
reduction is possible.
[0226] Further, since the cooling air flows smoothly from the
upstream to the downstream along the end configuration of the fan
4, the flow rate can be increased while reducing the noise.
[0227] [Thirteenth Embodiment]
[0228] FIG. 26 shows a primary portion of an application of the
noise reduction mechanism of a fan device according to the present
invention to an engine cooling system 1 of construction equipment
such as an excavator.
[0229] Basic arrangement of the engine cooling system 1 is the same
as the above-described first embodiment (see FIG. 1), and detailed
explanation of the components mentioned therein (the engine 2, the
radiator 3, the fan 4, the outer fringe 12, the end plate or the
support 13 of the shroud, the fan shroud 20 and the porous damping
material 40) are omitted.
[0230] The fan shroud 20 has a simple arrangement where ends of a
metal band is connected by welding etc. to be a cylinder, which is
spaced apart by a predetermined gap from the rotation locus of the
end of the fan 4. A, for instance, resin-made porous damping
material 30 is exposed on substantially entire inner circumference
of the fan shroud 20, thus reducing jet noise and impulsive sound
generated between the end of the fan 4 and the fan shroud 20.
[0231] The porous damping material 40 is composed of a plurality of
(four or six, in the present embodiment) porous members 401 adhered
along the circumference of the fan shroud 20. The porous members
401 has a semi-oval cross section with an upstream opening 402
opening toward upstream in a bell-mouth fashion and a downstream
opening 403 opening toward downstream side in a bell-mouth fashion
extending approximately from the support member 13, which is curved
as shown in FIG. 27. At this time, the radius R1 of an attachment
surface 404 of the porous member 401 is equal to the inner diameter
R2 (FIG. 26) of the inner circumference (attached surface) of the
fan shroud 20. Further, the respective openings 402 and 403 of the
porous member 401 are formed in the bell-mouth shape, thus smoothly
flowing the cooling air between the end of the fan 4 and the fan
shroud 20. As described below, the porous member 401 is a
die-molding product molded using a die.
[0232] The respective porous members 401 are disposed so that both
ends in the longitudinal direction confront with each other, the
confronting portions being hidden by the belt 140 shown in FIGS. 26
and 28. A belt 140 is a dropout prevention member according to the
present invention, which passes through an insert hole 13 of the
support 13 to be wound around the confronting portion of the porous
member 401 and the fan shroud 20. The end of the belt 140 is
mutually connected by an appropriate joint 141. Accordingly, the
porous member 401 does not easily come off even when the porous
member 401 is peeled, thus avoiding problem of contacting the fan
4. Though the material of the belt 140 is not limited, the same
material as the fan shroud 20 such as metal and resin may
preferably be used.
[0233] Further, as shown enlarged in FIG. 28, a rigid protection
layer 405 with the foam being collapsed is formed on the surface of
the porous member 401. The protection layer 405 is thin at an
approximately center relative to the flow direction of the cooling
air (wind direction), which becomes initially thick and gradually
becomes thin toward both ends. In other words, the foam is well
formed at the position adjacent to the surface thereof because the
protection layer 405 at the center relatively close to the end
locus of the fan 4, thus not impairing damping properties of the
porous damping material 40.
[0234] Next, a molding method of the porous member 401 constituting
the porous damping material 40 will be described below with
reference to FIG. 29(A) to FIG. 29(C).
[0235] In FIG. 29(A), a cavity 153 having an approximately
semi-oval cross section corresponding to final configuration of the
porous member 401 can be formed by engaging an upper die 151 and a
lower die 152. A foam material 406 having larger volume than the
volume of the cavity 153 and having a square cross section is
prepared and is packed in the cavity 153. The foam material 406 may
preferably be a synthetic resin such as a foamed urethane resin and
polyethylene terephthalate (PET).
[0236] In FIG. 29(B), the foam material 406 is filled in the cavity
153 by engaging the respective dies 51 and 52. At this time, since
the volume of the foam material 406 is larger than the volume of
the cavity 153, the foam is collapsed on the surface of the foam
material 406 and contact area against the cavity 153 is enlarged
with the dense foam. Especially, since the original configuration
of the foam material 406 has square cross section, the position of
the curve of the cavity 153 provided to the lower die 152 shown in
double-dotted line in the figure is greatly collapsed.
[0237] Subsequently, the curve of the cavity 153 of the lower die
152 is heated by a heater 154 installed in the lower die 152.
[0238] Then, as shown in FIG. 29(C), the surface of the foam
material 406 in contact with the curve of the cavity 153 is melted
and solidified to form the protection layer 405. The protection
layer 405 is thick at the above-described double-dotted line
portion having large contact area against the cavity 153 and the
foam thereon is greatly collapsed. It is speculated that this is
because the heat during the heating process is well transmitted on
account of the large contact area, so that the foam material is
comparatively well melted.
[0239] The porous member 401 is molded as described above.
[0240] According to the present embodiment, following effects can
be obtained.
[0241] (A1) Since the porous member 401 constituting the porous
damping material 40 is a die-molding product made using the die 150
having the cavity 153, the porous member 401 having an
approximately semi-oval cross section with bell-mouth configuration
and curved in the longitudinal direction can be easily
obtained.
[0242] (A2) Since the bell-mouth configuration is arranged on the
porous member 401, the bell-mouth configuration is not necessary to
be arranged on the fan shroud 20 and the fan shroud 20 can be
formed in a simple cylindrical shape. Accordingly, the fan shroud
20 can be manufactured without using a large press die etc., thus
greatly reducing the cost for the die and the components.
[0243] (A3) Since the porous member 401 is formed in a curved shape
and has the same diameter R1 as the inner diameter R2 of the fan
shroud 20, the porous member 401 can be directly attached to the
inner circumference of the fan shroud 20, thus facilitating
attachment process.
[0244] Further, since the wrinkle is not generated in attaching the
porous member 401, the surface condition can be kept well, thus
preventing excessive jet noise against the end of the fan 4.
[0245] (A4) Since the porous damping material 40 is composed of the
plurality of the porous member 401, the size of the die 150 can be
reduced, thus further reducing die cost.
[0246] Further, since the porous member 401 can be formed in short
length, the porous member 401 can be easily handled and the storing
space can be reduced, thus facilitating transportation thereof and
reducing management cost.
[0247] (A5) Since the porous member 401 has the bell-mouth
configuration, the wind flow of the cooling air required for heat
exchange at the radiator 3 can be sufficiently secured even when
the frequency of the fan 4 is lowered, thus further reducing the
noise.
[0248] (A6) Since the porous member 401 is not only adhered to the
fan shroud 20 but is attached to the fan shroud by the belt 140,
the dropout of the porous member 401 can be prevented even when the
adhesion of the porous member 401 is deteriorated, thus preventing
problem of contact of the porous member 401 against the fan 4 in
advance.
[0249] Since it is only required for the belt 140 to be wound
around the porous member 401 and the fan shroud 20 by being
inserted to the insert hole 13 of the support 13, the belt 140 can
be easily attached.
[0250] Further, since the belt 140 is would around to cover the
confronting portion of the adjacent porous members 401, the
boundary portion between the porous members 401 easily peeled off
by collision of sand dust etc. can be effectively protected by the
belt 140, thus improving durability thereof.
[0251] (A7) Since the rigid protection layer 405 is formed on the
surface of the porous member 401, the porous member 401 can be
effectively protected from dust and rain, thus improving weather
resistance and durability of the porous member 401 and, in
consequence, the entire porous damping material 40.
[0252] Further, the protection layer 405 can be easily formed by
using the foam material 406 having larger volume than the volume of
the cavity 153 and heating the surface of the foam material 406 to
melt and solidify.
[0253] (A8) Since the foam material with square cross section is
packed in the cavity 153 having semi-oval cross section, the
protection layer 405 is thin at the center relative to the flow
direction of the cooling air and is thick toward both ends.
Accordingly, the foam is sufficiently retained at the central
portion relatively close to the end locus of the fan 4 even at the
position adjacent to the surface of the porous member 401, thus
securely reducing the jet noise. On the other hand, the dust and
rain can be securely prevented by the thick protection layer 405 on
both end sides, i.e. the air inlet side on the upstream and the air
outlet side on the downstream.
[0254] [Thirteenth to Twentieth Modifications]
[0255] Incidentally, the scope of the present invention related to
molding method is not limited to the above-described thirteenth
embodiment but includes modifications described below.
[0256] For instance, though the fan shroud 20 of the thirteenth
embodiment is cylindrical, a frustum fan shroud 61 enlarging toward
downstream side or a fan shroud 62 with V-shaped cross section
having enlarging circumference toward both upstream side and
downstream side can be preferably used as shown in FIGS. 30 and 31
(the thirteenth and fourteenth modifications). In other words, the
configuration of the fan shroud may be designed in any shape
considering convenience in manufacture and attachment process of
the porous damping material.
[0257] Further, as shown in a fan 63 illustrated in FIG. 30, the
end shape of the fan may also be designed at will. The end of the
fan 63 has a center-dented shape so that the gap against the porous
damping material 40 can be constant. According to the present
arrangement, since the cooling air can flow smoothly from the
upstream side toward the downstream side along the end
configuration of the fan 63, the flow rate can be increased while
reducing noise.
[0258] The porous member of the present invention may be designed
in any cross section considering convenience in manufacture and
attachment process, which may, for instance, be disposed in plural
not only along circumference of the fan shroud 62 but also in flow
direction of the cooling air as shown in the porous member 64
attached to the fan shroud 62 having V-shaped cross section
illustrated in FIG. 31. Especially, since the porous member 64 uses
the identical porous member 64 on the upstream side and the
downstream side that is attached in different directions, only one
type of molding die is necessary.
[0259] Further, the porous member may have cross section as shown
in porous members 65 and 66 illustrated in FIGS. 32 and 33 (the
fifteenth and sixteenth modifications). In the porous member 65
shown in FIG. 32, a linear portion 67 is formed at the center along
the flow direction of the cooling air, and bell-mouth upstream
opening 68 and a downstream opening 69 are provided respectively on
the upstream side and downstream side thereof. In the porous member
66 shown in FIG. 33, a linear portion 71 is formed at the center
along the flow direction of the cooling air, and a linear upstream
enlarging portion 72 and a downstream enlarging portion 73 are
provided respectively on the upstream side and downstream side
thereof.
[0260] As in the above-described seventh modification (see FIG.
10), the molding method may be applied to an arrangement where the
fan shroud 74 itself is made of porous damping material
(seventeenth modification).
[0261] Though the porous member 401 of the aforesaid thirteenth
embodiment is molded in a curved shape having a radius R1, the
porous member 401 may be formed in a short linear shape as in the
porous member 77 shown in FIG. 34 (the eighteenth modification).
Since the porous member 77 with the present configuration is
linearly shaped, the porous member 77 can be easily molded in
elongated shape, which may be cut in a desired length. Further,
since no predetermined radius R1 is not defined unlike the porous
member 401 of the aforesaid embodiment, the porous member 77 can be
appropriately fitted to fan shrouds having any inner diameter by
being curved to be attached.
[0262] Further, the arrangement of the porous damping material of
the present invention is not limited to be composed of a plurality
of porous member, but may be molded in a single continuous
elongated porous damping material to be directly attached to the
fan shroud.
[0263] Though the belt 140 of the aforesaid embodiment is entirely
would around the porous damping material 40 (porous member 401) and
the fan shroud 20, when the fan shroud 79 having a fringe along
circumference thereof is used as shown in FIG. 35 (the nineteenth
modification), the belt 140 may be fixed to the fringe 78 by a
joint 81 such as a rivet to prevent the porous damping material 40
from dropping out.
[0264] Incidentally, the belt 140 is not only wound to cover the
boundary of the adjacent porous member 401, but may be wound around
at any position in circumferential direction.
[0265] Further, since the fan shroud 89 having the fringe 78 can
protect the edge portion along the circumference of the porous
member 401 by the fringe 78, the porous member 401 can also be
prevented from peeling off.
[0266] The dropout prevention member of the present invention may
not only be the belt 140 but also be a net 82 shown in FIG. 36 (the
twentieth modification). The net 82 is arranged by braiding metal
thread etc. in a net and does not cause impulsive sound of the
cooling air when the net 82 is provided on the surface of the
porous damping material 40. The net 82 can be attached to the
fringe 78 etc. of the fan shroud 79 by the joint 81 through a thin
attachment member 83 along the circumference.
[0267] The porous member 401 of the aforesaid embodiments is molded
by packing a predetermined volume of the foam material 406 into the
die 150. However, the porous member 401 may be molded by directly
feeding a molten resin and a foaming agent into the die while
foaming the resin inside the die cavity to mold into the final
porous member shape. Though the molding method of the present
invention does not include the present method, since the porous
member or the porous damping material can be manufactured by die
molding, the porous damping material of the present invention
includes such an arrangement.
[0268] The noise reduction mechanism according to the present
invention can be used not only to the engine cooling system of
excavator, but also can be used to engine cooling system of
special-purpose vehicle including other construction equipment and
ordinary automobile, and industrial cooling system such as cooling
tower for cooling plant cooling water in various factories. In
short, the present invention can be applied not only to a mechanism
where the fan is driven by an engine but also to a mechanism having
motor-driven fan.
* * * * *