U.S. patent application number 14/361090 was filed with the patent office on 2014-10-09 for construction machine.
The applicant listed for this patent is HITACHI CONSTRUCTION MACHINERY CO., LTD.. Invention is credited to Masanori Ezawa, Shigehisa Funabashi, Taku Iwase, Tomonori Mamada, Makoto Matsushita, Osamu Watanabe.
Application Number | 20140301839 14/361090 |
Document ID | / |
Family ID | 48535461 |
Filed Date | 2014-10-09 |
United States Patent
Application |
20140301839 |
Kind Code |
A1 |
Funabashi; Shigehisa ; et
al. |
October 9, 2014 |
CONSTRUCTION MACHINE
Abstract
An efficient and quiet construction machine has a heat exchanger
in which the air flowing out from an axial flow fan avoids
collision with the engine. The axial flow fan includes a plurality
of blade pieces, a fan ring which guides a flow of air to the axial
flow fan, a heat exchanger which is disposed on an upstream side or
a downstream side of the flow of air with respect to the axial flow
fan, and a structure which is disposed on the downstream side of
the flow of air with respect to the axial flow fan. The fan ring
includes a suction-side rounded part which reduces a flow channel
on a suction side and a discharge-side rounded part which expands
the flow channel on a discharge side, and each of the blade pieces
is inclined at a sweep forward angle from an axial center toward a
rotation direction.
Inventors: |
Funabashi; Shigehisa;
(Tokyo, JP) ; Iwase; Taku; (Tokyo, JP) ;
Matsushita; Makoto; (Tsuchiura, JP) ; Ezawa;
Masanori; (Tsuchiura, JP) ; Mamada; Tomonori;
(Tsuchiura, JP) ; Watanabe; Osamu; (Tsuchiura,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
HITACHI CONSTRUCTION MACHINERY CO., LTD. |
Tokyo |
|
JP |
|
|
Family ID: |
48535461 |
Appl. No.: |
14/361090 |
Filed: |
November 28, 2012 |
PCT Filed: |
November 28, 2012 |
PCT NO: |
PCT/JP2012/080754 |
371 Date: |
May 28, 2014 |
Current U.S.
Class: |
415/208.2 |
Current CPC
Class: |
B60Y 2306/09 20130101;
B60Y 2200/412 20130101; B60K 11/04 20130101; F04D 29/541 20130101;
F04D 29/164 20130101; F04D 19/002 20130101; E02F 3/32 20130101;
B60K 11/08 20130101; F04D 29/384 20130101; E02F 9/0866
20130101 |
Class at
Publication: |
415/208.2 |
International
Class: |
F04D 19/00 20060101
F04D019/00 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 29, 2011 |
JP |
2011-260760 |
Claims
1. A construction machine comprising: an axial flow fan which
includes a plurality of blade pieces and rotates around an axis; a
fan ring which is disposed around the axial flow fan and guides a
flow of air to the axial flow fan; a heat exchanger which is
disposed on an upstream side or a downstream side of the flow of
air with respect to the axial flow fan; and a structure which is
disposed on the downstream side of the flow of air with respect to
the axial flow fan; wherein: the fan ring includes a suction-side
rounded part which reduces a flow channel on a suction side and a
discharge-side rounded part which expands the flow channel on a
discharge side; each of the blade pieces is formed with a leading
edge, a trailing edge and a tip, inclined at a sweep forward angle
.theta. from an axial center toward a rotation direction, and
attached in a posture in which the blade piece slants forward on
the suction side; and in a state in which the axial flow fan is
attached to an inner side of the fan ring, a first intersection
where the trailing edge of each of the blade pieces intersects the
tip of the same is located within a width range of the
discharge-side rounded part; the sweep forward angle .theta. is
within a range not smaller than 5.degree. and not larger than
25.degree.; and a second intersection where the leading edge of
each of the blade pieces intersects the tip of the same is located
to protrude from the suction-side rounded part toward the upstream
side of the flow or air, so that; the air forms a centripetal flow
on the upstream side of the axial flow fan, and forms a centrifugal
flow on the downstream side of the same to thereby avoid collision
with the structure.
2. A construction machine according to claim 1, wherein: the
plurality of blade pieces are disposed around a columnar hub
attached to a rotary shaft of the axial flow fan; the sweep forward
angle .theta. is defined as an internal angle A of a triangle AOP
formed by connecting points A, O and P, where the point A
designates a center point of the rotary shaft of the axial flow
fan, the point O designates a third intersection where the trailing
edge of the blade piece intersects the hub, and the point P
designates the first intersection; and the internal angle A is
within a range not smaller than 5.degree. and not larger than
25.degree..
3. (canceled)
Description
TECHNICAL FIELD
[0001] The present invention relates to a construction machine
provided with a cooling system for supplying cooling air to a heat
exchanger such as a radiator by means of an axial flow fan.
BACKGROUND ART
[0002] Generally, in a construction machine such as a hydraulic
excavator, a hydraulic pump is driven by a diesel engine so that
hydraulic energy of the hydraulic pump can be used for excavation
work, travelling and so on. To that end, heat exchangers such as a
radiator for cooling the engine and an oil cooler for cooling
hydraulic oil, and a cooling fan for supplying cooling air to these
heat exchangers are disposed together with the engine and the
hydraulic pump inside an engine room.
[0003] For example, Patent Literature 1 has been known as a
background-art technique in this technical field. An example in
which a heat exchanger for a construction machine is cooled by
means of an inexpensive thin axial flow fan has been disclosed in
this Patent Literature 1. This example has a configuration in which
the axial flow fan is rotated by power transmitted from a crank
shaft of the engine through a pulley and a fan belt. The heat
exchanger is often disposed on an upstream side of the axial flow
fan. After the air flowing in from the outside through suction
ports passes through the heat exchanger, the air is guided to the
axial flow fan by a fan shroud and a fan ring. The air pressurized
by the axial flow fan flows around the engine (structure) and is
then released to the outside through an exhaust port.
[0004] In recent years, air-cooling intercoolers or water-cooling
EGR (Exhaust Gas Recirculation) devices have been mounted on
construction machines as units for reducing exhaust gas in order to
respond to the regulation of exhaust gas of diesel engines mounted
on the construction machines. In addition, common rails have been
mounted to control the timing of fuel injection to thereby suppress
emission of exhaust gas.
CITATION LIST
Patent Literature
[0005] Patent Literature 1: JP-A-2010-270670
SUMMARY OF INVENTION
Technical Problem
[0006] For the aforementioned exhaust gas emission control, a heat
exchanger that is an intercooler is newly added to a radiator and
an oil cooler which have been mounted heretofore. It is also
necessary to enhance the heat radiation performance of the radiator
to further cool the water-cooling EGR device. Thus, the flow rate
of air required for cooling has increased in recent construction
machines.
[0007] In addition, a heat exchanger has been increasing in size
correspondingly to the increase in cooling load. However, the
number of devices mounted in a limited space within an engine room
has been increased. Thus, there is a limit to the increase in the
size of the heat exchanger. In the case of a machine where the
frontal area of a heat exchanger cannot be enlarged anymore, the
size of the heat exchanger may be increased to increase the
thickness of the heat exchanger.
[0008] When the frontal area of the heat exchanger is enlarged, the
heat exchanger however becomes large relatively to a fan. Since an
end portion of the heat exchanger has a distance from the fan,
cooling air hardly flow in that portion. It is therefore difficult
to sufficiently exert the effect of the increasing size of the heat
exchanger. The increase in the diameter of the fan corresponding to
the heat exchanger may be considered if the space allows. However,
the increase in power for driving the fan gives restriction to
power which can be used as the construction machine.
[0009] On the other hand, when the size of the heat exchanger is
increased to increase the thickness of the heat exchanger, the
space in the direction of a rotary shaft of the fan needs to be
narrowed correspondingly. When the distance between the heat
exchanger and the fan is reduced correspondingly, the wind speed
distribution of the air passing through the heat exchanger may
deteriorate. When the distance between the fan and the engine is
reduced, the flow flowing out from the fan may collide with the
engine easily to thereby increase the loss of pressure in a flow
channel of the cooling air. Thus, the rotation speed of the fan
required for obtaining the required flow rate of the air increases.
As a result, the shaft power of the fan or the noise increases, and
hence the noise of the construction machine increases and the fuel
consumption deteriorates.
[0010] Further, in the case of the construction machine, suction of
the cooling air due to travelling wind as in a car cannot be
expected. Therefore, all the required flow rate of the cooling air
must be sucked by the fan. Accordingly, the rotation speed of the
fan must be set to be higher than in a car, so that the shaft power
of the fan or the noise may be increased easily. This also affects
the fuel consumption or the noise of the construction machine as a
whole.
[0011] The invention has been accomplished in consideration of the
aforementioned actual circumstances. An object of the invention is
to provide a highly efficient and quiet construction machine in
which the wind speed distribution in a heat exchanger is excellent
so that the air flowing out from an axial flow fan can avoid
collision with an engine.
Solution to Problem
[0012] In order to solve the foregoing problems, the invention
provides a construction machine including: an axial flow fan which
includes a plurality of blade pieces and rotates around an axis; a
fan ring which is disposed around the axial flow fan and guides a
flow of air to the axial flow fan; a heat exchanger which is
disposed on an upstream side or a downstream side of the flow of
air with respect to the axial flow fan; and a structure which is
disposed on the downstream side of the flow of air with respect to
the axial flow fan; wherein: the fan ring includes a suction-side
rounded part which reduces a flow channel on a suction side and a
discharge-side rounded part which expands the flow channel on a
discharge side; each of the blade pieces is formed with a leading
edge, a trailing edge and a tip, inclined at a sweep forward angle
.theta. from an axial center toward a rotation direction, and
attached in a posture in which the blade piece slants forward on
the suction side; and in a state in which the axial flow fan is
attached to an inner side of the fan ring, a first intersection
where the trailing edge of each of the blade pieces intersects the
tip of the same is located within a width range of the
discharge-side rounded part.
[0013] According to the invention configured thus, a centripetal
flow can be formed on the suction side of the axial flow fan, and a
centrifugal flow can be formed on the discharge side of the same.
Thus, cooling air can be made to flow with a good wind speed
distribution up to an end portion of a large-sized heat exchanger
disposed on the upstream side or the downstream side of the flow of
the air with respect to the axial flow fan. In addition, the air
flowing out from the axial flow fan can avoid collision with a
structure such as an engine located on the downstream side. It is
therefore possible to prevent the loss of pressure from increasing
in the flow channel of the cooling air.
[0014] According to the invention, the heat radiation performance
in the heat exchanger can be improved and the hot air around the
engine can be ventilated efficiently. Accordingly, the occurrence
of overheat in the engine or hydraulic oil can be suppressed.
Further, when the heat radiation performance in the heat exchanger
is improved and the loss of pressure in the flow channel of the
cooling air is reduced, the flow rate required for cooling can be
reduced. Accordingly, the rotation speed of the axial flow fan can
be suppressed. This can also contribute to suppression of noise,
improvement of fuel consumption achieved by reduction in driving
power, and so on.
[0015] In addition, in the aforementioned configuration, it is
preferable that the sweep forward angle .theta. is within a range
not smaller than 5.degree. and not larger than 25.degree.. With
this configuration, even when the rotation speed of the axial flow
fan is increased to obtain a design flow rate (100% Q), the
increase in noise generated at that time can be suppressed to a
level (that is, +3 dB or lower) that cannot be sensed by any
person. In addition, even when the loss of pressure increases
because the cooling air receives resistance of the structure which
is located on the discharge side of the cooling air, reduction of
the flow rate can be prevented from falling below an allowable
lower limit value (that is, -10%).
[0016] In addition, in the aforementioned configuration, it is
preferable that a second intersection where the leading edge of
each of the blade pieces intersects the tip of the same is located
to protrude from the suction-side rounded part toward the upstream
side of the flow of air. With this configuration, the centripetal
flow on the suction side of the axial flow fan and the centrifugal
flow on the discharge side of the same can be made smoother.
Accordingly, the heat radiation performance of the heat exchanger
can be further improved.
Advantageous Effects of Invention
[0017] According to the invention, it is possible to provide a
highly efficient and quiet construction machine in which the wind
speed distribution in a heat exchanger is kept so excellent that
the air flowing out from an axial flow fan can avoid collision with
an engine.
BRIEF DESCRIPTION OF DRAWINGS
[0018] [FIG. 1] An external perspective view of a hydraulic
excavator according to a first example of the invention.
[0019] [FIG. 2] A side sectional view of an engine room of the
hydraulic excavator shown in FIG. 1.
[0020] [FIG. 3] An enlarged side view of main parts of an axial
flow fan and a fan ring shown in FIG. 2.
[0021] [FIG. 4] An enlarged plan view of the main part of the axial
flow fan shown in FIG. 2.
[0022] [FIG. 5] A graph showing the relationship between a sweep
forward angle of each blade of the axial flow fan shown in FIG. 2
and relative noise.
[0023] [FIG. 6] A graph showing the relationship between the sweep
forward angle of each blade of the axial flow fan shown in FIG. 2
and a change of the flow rate of air at the time of the increase in
loss of pressure.
[0024] [FIG. 7] A side sectional view of an engine room of a
hydraulic excavator according to a second example of the
invention.
DESCRIPTION OF EMBODIMENTS
[0025] A hydraulic excavator which is an embodiment of a
construction machine according to the invention will be described
below with reference to the drawings. As shown in FIG. 1, the
hydraulic excavator according to a first example is provided with a
crawler 24, an upper rotary body 26 which is disposed on the
crawler 24, a front work machine which is attached to the upper
rotary body 26 so that the front work machine can rotate vertically
to perform excavation work and so on, and a cab 25 which is an
operation room. The front work machine is provided with a boom 21
which is attached to the upper rotary body 26 so that the boom 21
can be depressed and elevated, an arm 22 which is rotatably
attached to a front end of the boom 21, a bucket 23 which is
rotatably attached to a front end of the arm 22, and hydraulic
cylinders which drive these parts. In addition, the upper rotary
body 26 includes an engine room 10 at the rear thereof. The
reference numeral 27 represents a counterweight 27.
[0026] As shown in FIG. 2, an axial flow fan 2, a fan ring 3 which
guides a flow of air to the axial flow fan 2, a heat exchanger 1,
an engine (structure) 4, and a battery 9 are placed in the engine
room 10. In addition, suction ports 7 which serve as inlets/outlets
of the air are provided in an upper portion of the engine room 10,
and exhaust ports 8 are provided in the upper portion and a lower
portion of the engine room 10. As for the positional relation among
the heat exchanger 1, the axial flow fan 2 and the engine 4, the
heat exchanger 1 is located on an upstream side of the flow of air
with respect to the axial flow fan 2, and the engine 4 is located
on a downstream side of the flow of air with respect to the axial
flow fan 2. As a result of the positional relation, the axial flow
fan 2 is requested to form a centripetal flow flowing toward the
center of the fan on the upstream side, and requested to form a
centrifugal flow flowing in the centrifugal direction of the fan on
the downstream side. To that end, forward-swept/forward-slanting
blades are used in this example (as will be described in detail
later).
[0027] The heat exchanger 1 is constituted by a radiator, an oil
cooler and an intercooler, and those devices are disposed in
parallel. In recent years, the heat exchanger 1 tends to increase
in size in order to enhance the cooling capacity. Also in this
example, the entire external shape of the heat exchanger 1 is
larger than that of the axial flow fan 2.
[0028] The engine 4 is provided with a crank shaft (output shaft)
4a. Power for rotating the axial flow fan 2 is transmitted from the
crank shaft 4a through a pulley 5 and a fan belt 6. The fan 2 is
rotated with a rotation speed adjusted properly by the pulley
5.
[0029] Next, the axial flow fan 2 and the fan ring 3 will be
described in detail. The axial flow fan 2 is constituted by a
columnar hub 2b which is attached to a rotary shaft 2c, and a
plurality of blades (blade pieces) 2a which are provided around the
hub 2b, as shown in FIG. 2. In addition, the fan ring 3 formed into
an annular shape is provided around the axial flow fan 2 and
provided with a suction-side rounded part 3a having a curved
surface on the suction side of the axial flow fan 2 and a
discharge-side rounded part 3b having a curved surface on the
discharge side of the same, as shown in FIG. 2 and FIG. 3. That is,
in the fan ring 3, both the suction-side side edge portion and the
discharge-side side edge portion are formed into rounded shapes
respectively.
[0030] Each blade 2a is formed to have a leading edge 2g, a tip 2e
and a trailing edge 2d as shown in FIG. 3. In a state in which the
axial flow fan 2 is attached to an inner side of the fan ring 3, a
second intersection Q where the leading edge 2g intersects the tip
2e protrudes from the suction-side rounded part 3a of the fan ring
3 and on the upstream side (suction side) by a length L, and a
first intersection P where the trailing edge 2d intersects the tip
2e is located within a range of a width W of the discharge-side
rounded part 3b of the fan ring 3.
[0031] Further, the shape of each blade 2a will be described in
detail. As shown in FIG. 3, the blade 2a protrudes on the suction
side in a position where the diameter thereof is larger. Thus, the
blade 2a is inclined (slanting forward) as a whole. In addition, as
shown in FIG. 4, the blade 2a protrudes (is swept forward) in the
rotation direction in a site where the radial position thereof is
larger. The sweep forward angle is .theta.. That is, each blade 2a
of the axial flow fan 2 used in this example is a
forward-swept/forward-slanting blade. The sweep forward angle
.theta. mentioned herein is an angle indicating how the trailing
edge 2d of the blade 2a protrudes in the rotation direction.
Specifically, the sweep forward angle .theta. corresponds to an
internal angle A of a triangle AOP formed by connecting a center
point A of the rotary shaft 2c, a third intersection O where the
trailing edge 2d of the blade 2a intersects the hub 2b, and the
first intersection P.
[0032] Next, the flow of the air made by the axial flow fan 2 will
be described. Each arrow in FIG. 2 and FIG. 3 shows the flow of the
air. Generally, an axial flow fan with
forward-swept/forward-slanting blades is characterized in that a
centripetal flow flowing toward the rotation center of the fan is
formed on the upstream side (suction side) of the fan so that the
fan can also suck the air from the lateral side of the fan
partially. Thus, when the axial flow fan 2 rotates, a flow of the
air is induced due to a difference in pressure occurring between
before and behind the axial flow fan 2. First, the low-temperature
air outside the engine room 10 flows into the engine room 10
through the suction ports 7. When passing through the heat
exchanger 1, the air takes heat away from fluid (such as engine
cooling water, hydraulic oil, compressed air, etc.) inside tubes of
the heat exchanger 1, and the temperature of the air itself becomes
high. After that, the air flows into the axial flow fan 2 to be
thereby increased in pressure, and then flows out from the axial
flow fan 2. The air flows around the engine 4, and is then released
to the outside of the engine room 10 from the exhaust ports 8. Due
to the flow generated thus, it is possible to make a flow of the
air reaching up to the end portion of the heat exchanger 1 even if
the heat exchanger 1 is larger than the axial flow fan 2. It is
therefore possible to achieve heat exchange with high
efficiency.
[0033] On the other hand, the axial flow fan with
forward-swept/forward-slanting blades is characterized in that the
air easily flows out in the axial flow direction along the rotary
shaft 2c on the downstream side (discharge side) of the fan.
Therefore, there is a possibility that the air flowing out from the
axial flow fan 2 may directly collide with the engine 4 to thereby
increase the loss of pressure.
[0034] In the case of this example, therefore, the first
intersection P where the trailing edge 2d intersects the tip 2e is
located within the range of the width W of the discharge-side
rounded part 3b of the fan ring 3, as shown in FIG. 3. In this
manner, the air flowing out from the axial flow fan 2 flows along
the discharge-side rounded part 3b of the fan ring 3 due to the
Coanda effect, so that the flow of the air can flow in the radial
direction easily to be a centrifugal flow. As a result, the air
flowing out from the axial flow fan 2 can avoid collision with the
engine 4, so that the increase in loss of pressure can be
suppressed. In addition, since the discharge-side rounded part 3b
of the fan ring 3 also serves as a diffuser, it is also possible to
expect an effect that a flow flowing out with a high absolute
velocity and from the first intersection P located at a rear end of
each blade 2a is reduced in velocity effectively to increase the
static pressure.
[0035] As understood from the above description, in the hydraulic
excavator according to this example, effective heat exchange can be
achieved by a good wind speed distribution in the heat exchanger 1,
and the air flowing out can be prevented from colliding with the
engine 4 on the downstream side of the axial flow fan 2. Thus, it
is possible to attain a flow channel configuration with a low loss
of pressure.
[0036] On the other hand, in the hydraulic excavator, noise of the
axial flow fan 2 or the engine 4 leaks from opening portions (the
suction ports 7 and the exhaust ports 8) so as to increase ambient
noise. Therefore, there is a need to provide the opening portions,
if possible, in an upper surface or a lower surface of the engine
room 10 so as to prevent fan noise or engine noise from being
transmitted directly to any person around the hydraulic excavator.
With respect to this point, in the configuration of this example,
inflow (centripetal flow) from the radial direction of the axial
flow fan 2 and outflow (centrifugal flow) to the radial direction
are made compatible. It is therefore favorable to provide the
opening portions in the upper portion of the engine room 10
laterally in view from the rotary shaft 2c of the axial flow fan 2.
It is also possible to contribute to reduction of noise in the
hydraulic excavator as a whole while suppressing the total loss of
pressure.
[0037] When the sweep forward angle .theta. is made too large, the
centripetal flow on the suction side of the axial flow fan 2 and
further the axial flow on the discharge side of the same are
enhanced so that it is difficult to form the centrifugal flow on
the downstream side in spite of the aforementioned configuration.
In addition, according to the value of the sweep forward angle A,
the value of the fan noise may vary and the flow rate may be also
affected. Therefore, in order to obtain a preferable angle range of
the sweep forward angle .theta., the present inventors performed
simulation analysis as follows.
[0038] First, the present inventors performed simulation analysis
about noise when a design flow rate (100% Q) was attained. For
example, when the static pressure of the axial flow fan 2 is low,
the rotation speed of the fan needs to be increased to obtain a
design flow rate (100% Q) required for cooling. Increase in
rotation speed for attaining the design flow rate can be converted
into a change in noise as shown in FIG. 5. FIG. 5 shows the change
in noise with reference to the sweep forward angle
.theta.=0.degree.. The sweep forward angle .theta. is desired to be
designed to attain the lowest noise (that is, near
.theta.=0.degree.) if possible. However, it is said that noise
increase of 3 dB (twice sound energy) corresponds to a level
difference that can be recognized as noise increase by human ears.
It is therefore possible to allow noise increase not larger than
this level. From this point of view, it can be considered that
substantially the lowest level as noise that can be sensed by any
person can be attained if the sweep forward angle .theta. is set to
be not larger than about 25.degree.. That is, it has been found out
from this simulation analysis that the upper limit of the sweep
forward angle .theta. with which noise can be suppressed to be not
larger than +3 dB is 25.degree..
[0039] Next, the present inventors performed simulation analysis
about the reduction of the flow rate when the loss of pressure
(resistance in a flow channel) increased by 30% relatively to that
at the time of design. The result of the simulation analysis is
shown in FIG. 6. Due to the environment in which a construction
machine is operating, rubbish, soil, etc. are deposited on a heat
exchanger. That is, an axial flow fan is operating under such an
environment that the resistance in the flow channel increases
gradually. Practically, after operation for a certain time, the
heat exchanger or a filter is cleaned to remove clogging so as to
suppress the increase of the resistance in the flow channel. In
view of user-friendliness, it is desired to make the interval of
the cleaning as long as possible. In other words, it is desired to
use an axial flow fan in which the reduction of the flow rate can
be kept as small as possible even if the resistance in the flow
channel increases. To this end, it is desirable from FIG. 6 that
the sweep forward angle .theta. is not smaller than about 5.degree.
and not larger than about 40.degree. when 10% as the reduction of
the flow rate is the allowable lower limit.
[0040] From the aforementioned results of the simulation analysis,
it has been found out that the sweep forward angle .theta. serving
as a threshold satisfying both the design requests is not smaller
than 5.degree. and not larger than 25.degree.. Therefore, the sweep
forward angle .theta. of each blade 2a is set to be not smaller
than 5.degree. and not larger than 25.degree. in the axial flow fan
2 according to the example.
[0041] Next, a second example of the invention will be described
with reference to FIG. 7. FIG. 7 shows a side sectional view of an
engine room in a hydraulic excavator according to the second
example. In the second example, constituents the same as those in
the first example are referred to by the same numerals
correspondingly, and description thereof will be omitted.
[0042] In this example, an axial flow fan 2 is placed separately
from an engine 4. A heat exchanger 1 is disposed on a downstream
side of the axial flow fan 2. Suction ports 7 are disposed in upper
and lower wall surfaces of an engine room 10 on an upstream side of
the axial flow fan 2, particularly in the side surfaces in view
from a rotary shaft 2c of the axial flow fan 2. The axial flow fan
2 is connected directly to a hydraulic motor 11 and driven thereby.
A fan ring 3 is placed around the axial flow fan 2 in the same
manner as in the first example.
[0043] When the axial flow fan 2 rotates, the air flows into the
engine room 10 through the suction ports 7. The air which has
passed through the axial flow fan 2 undergoes heat exchange in the
heat exchanger 1. Then, the air is discharged to the outside
through upper and lower exhaust ports 8 on the downstream side.
[0044] Also in the configuration of the second example, a
centripetal flow on the upstream side of the axial flow fan 2 and a
centrifugal flow on the downstream side of the same are made
compatible. Thus, the air can flow in smoothly through the suction
ports 7 provided laterally in view from the rotary shaft 2c. In
addition, when the flow flowing out from the axial flow fan 2
enters the heat exchanger 1, the air also enters the end portion of
the heat exchanger 1. Thus, effective heat exchanger can be
attained. Since the suction ports 7 and the exhaust ports 8 are
provided in the upper surface and the lower surface of the engine
room 10, noise from the axial flow fan 2 or the motor 11 can be
prevented from reaching ears of any person around the hydraulic
excavator. Thus, it is possible to contribute to reduction in noise
around the hydraulic excavator.
[0045] Although the effect of the invention has been described
along the aforementioned examples, the invention is not always
limited thereto. In the invention, for example, any method or any
kind can be used as the method for driving the fan or the kind of
the heat exchanger. The effect of the invention can be also
expected in another construction machine than the hydraulic
excavator.
REFERENCE SIGNS LIST
[0046] 1 heat exchanger [0047] 2 axial flow fan [0048] 2a blade
(blade piece) [0049] 2c rotary shaft (axis) [0050] 2d trailing edge
[0051] 2e tip [0052] 2g leading edge
[0053] 3 fan ring
[0054] 3a suction-side rounded part
[0055] 3b discharge-side rounded part
[0056] 4 engine (structure)
[0057] P first intersection
[0058] Q second intersection
[0059] W width of discharge-side rounded part
[0060] .theta. sweep forward angle
* * * * *