U.S. patent application number 13/121289 was filed with the patent office on 2011-07-21 for heat retention/cooling control device for pm filter device.
This patent application is currently assigned to KOMATSU LTD.. Invention is credited to Yuuki Ishikawa, Hirofumi Miwa, Hideaki Murakami, Hitoshi Nakanishi, Satoshi Sawafuji.
Application Number | 20110173962 13/121289 |
Document ID | / |
Family ID | 42128687 |
Filed Date | 2011-07-21 |
United States Patent
Application |
20110173962 |
Kind Code |
A1 |
Miwa; Hirofumi ; et
al. |
July 21, 2011 |
Heat Retention/Cooling Control Device for PM Filter Device
Abstract
Provided is a heat retention/cooling control device for a PM
filter device, which controls the temperature of the outer
periphery of the PM filter device to ensure an efficient burning in
the PM filter device and prevents the influence of heat damage on
the periphery of the PM filter device by effectively using moving
air. An engine room and a cooling passage which are demarcated by a
partition wall are provided in parallel in the front-back direction
of an work machine, and an aftercooler, a cooling fan, and a PM
filter device are provided in the cooling passage. When the exhaust
temperature of exhaust gas is lower than a target temperature when
PM is burned, the air volume of the cooling fan is controlled so as
to decrease, thereby increasing the exhaust gas temperature. When
the exhaust temperature of the exhaust gas is higher than the
target temperature, the air volume of the cooling fan is controlled
so as to increase, thereby enhancing the effect of cooling the
outer periphery of the PM filter device.
Inventors: |
Miwa; Hirofumi; (Tochigi,
JP) ; Ishikawa; Yuuki; (Tochigi, JP) ;
Sawafuji; Satoshi; (Tochigi, JP) ; Nakanishi;
Hitoshi; (Tochigi, JP) ; Murakami; Hideaki;
(Tochigi, JP) |
Assignee: |
KOMATSU LTD.
Tokyo
JP
|
Family ID: |
42128687 |
Appl. No.: |
13/121289 |
Filed: |
September 24, 2009 |
PCT Filed: |
September 24, 2009 |
PCT NO: |
PCT/JP2009/066532 |
371 Date: |
March 28, 2011 |
Current U.S.
Class: |
60/311 |
Current CPC
Class: |
F01N 2560/06 20130101;
Y02T 10/12 20130101; F02M 26/05 20160201; F01N 2260/022 20130101;
F01P 7/04 20130101; B01D 46/4218 20130101; F01N 3/033 20130101;
F01N 3/021 20130101; Y02T 10/20 20130101; B01D 2279/30 20130101;
B01D 46/0061 20130101; B01D 46/42 20130101; F01N 3/02 20130101 |
Class at
Publication: |
60/311 |
International
Class: |
F01N 3/02 20060101
F01N003/02 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 29, 2008 |
JP |
2008-278400 |
Claims
1. A heat retention/cooling control device for a PM filter device
for reducing PM as particulate matters contained in an exhaust gas
exhausted from a diesel engine mounted on an work machine
comprising: a cooling passage disposed in parallel with an engine
room configured in a front-back direction of the work machine and
demarcated from the engine room via a partition wall; an
aftercooler disposed in the cooling passage for cooling air
supercharged by a supercharger disposed in the engine room; the PM
filter device which is disposed on a downstream side of the
aftercooler in the cooling passage and into which the exhaust gas
from the engine is introduced; a cooling fan which is disposed in
the cooling passage, cools the aftercooler, and cools an outer
periphery of the PM filter device by waste heat wind which has
cooled the aftercooler; a temperature sensor for detecting an
exhaust gas temperature of the exhaust gas; and a controller
connected to the temperature sensor for controlling an amount of
air of the cooling fan when the PM captured by a filter of the PM
filter device is combusted, wherein when the exhaust gas
temperature detected by the temperature sensor is higher than a
target temperature, the controller performs a control for
increasing a cooling effect to the outer periphery of the PM filter
device by increasing the amount of air from the cooling fan, and
when the exhaust gas temperature detected by the temperature sensor
is lower than the target temperature, the controller performs a
control for assisting to increase and to retain a temperature in
the outer periphery of the PM filter device by reducing the amount
of air from the cooling fan.
2. The heat retention/cooling control device for the PM filter
device according to claim 1, wherein an exhaust pipe for
introducing an exhaust gas exhausted from the engine into the PM
filter device is disposed to receive wind from the cooling fan on
an upstream side of the PM filter device.
Description
TECHNICAL FIELD
[0001] The invention relates to a heat retention/cooling control
device for a PM filter device (a device for capturing particulate
matters (PM) contained in an exhaust gas).
[0002] Note that, in the invention, a front-back traveling
direction when viewed from a side surface of an work machine is
defined as a front-back direction, and a right-left direction when
viewed from a front surface of the work machine is defined as a
vehicle width direction.
BACKGROUND ART
[0003] Conventionally, a PM filter device has been used to prevent
PM (particulate matters) which are particulate substances contained
in an exhaust gas of a diesel engine from being emitted into the
atmosphere as it is. The PM filter device is used as a device which
is disposed in an exhaust passage of the exhaust gas and captures
and reduces PM contained in the exhaust gas by a filter.
[0004] As a basic configuration of the PM filter device, the PM
filter device is configured to capture PM by a filter. Further, the
PM filter device may have a self-cleaning function capable of
combusting PM captured by the filter and refreshing the filter to
prevent deterioration of a filter function when the filter is
clogged.
[0005] As a filter refreshing technology, an oxidation catalyst
disposed upstream of a filter is oxidized and caused to generate
heat by supplying a fuel into an exhaust gas. Then, a temperature
of the exhaust gas that flows into the filter is increased, and PM
deposited on the filter is self-combusted by the exhaust gas whose
temperature has been increased. The filter is refreshed by
eliminating clogging of the filter caused by the PM by combusting
the PM.
[0006] When the PM filter device combusts the PM to eliminate the
clogging of the filter, the PM filter device can improve a
combustion efficiency at the time the PM is combusted by placing
the PM filter device in a high temperature state. However, at this
time, since a temperature of an outer periphery of the PM filter
device also becomes high, a bad influence due to heat (so-called
heat damage) is applied to peripheral equipment disposed in a
periphery of the PM filter device. Further, when a driver's cabin
is disposed in the vicinity of the PM filter device, a temperature
in the driver's cabin is increased when the PM is combusted.
[0007] Various devices have been proposed to prevent the heat
damage by the PM filter device, such as a cooling fan control
device for predicting and preventing a temperature increase in the
periphery of the PM filter device (refer to Patent Document 1), and
a filter refresh control device of a diesel engine by which a
combustion efficiency of a PM filter device is improved (refer to
Patent Document 2). In the filter refresh control device of Patent
Document 2, a heat shield plate is disposed in the periphery of a
PM filter device so that outside air can be taken between the PM
filter device and the heat shield plate and the intake outside air
is caused to flow into a hot air duct, thereby improving the
combustion efficiency of the PM filter device.
[0008] FIG. 7 shows a plan view of the cooling fan control device
of Patent Document 1 as a conventional example 1 of the invention.
As shown in FIG. 7, an engine room 71, in which an engine 70 is
accommodated, is disposed forward of wheels, and a cooling fan 72
is disposed forward of the engine 70. A radiator 73 and a capacitor
74 of an air conditioner are disposed further forward of the
cooling fan 72. A PM filter device 75 is disposed just behind the
engine 70 in the engine room 71.
[0009] Since the radiator 73 and the capacitor 74 of the air
conditioner are cooled by air supplied from the cooling fan 72,
temperatures of cooling water and a refrigerant can be reduced by
the air. Further, temperatures of components such as the engine 70
and the PM filter device 75 disposed in the engine room can be
reduced by waste heat wind from the cooling fan 72.
[0010] Then, a rotation speed of the cooling fan 72 is set to
increase when the temperature of the cooling water is high, when a
load of the air conditioner is large, and when the PM filter device
75 is being refreshed. Further, a control is performed so that a
predetermined time difference is provided until the rotation speed
of the cooling fan 72 is controlled from a time at which a refresh
signal of the PM filter device 75 is received. That is, the control
of the rotation speed of the cooling fan 72 is started after a
start delay time t1 passes.
[0011] FIG. 8 shows a schematic view of the filter refresh control
device of Patent Document 2 as a conventional example 2 of the
invention. As shown in FIG. 8, a heat shield plate 91 is disposed
in the periphery of a PM filter device 90 to prevent an influence
due to heat (heat damage) to peripheral components. Outside air can
be taken from a space formed between the PM filter device 90 and
the heat shield plate 91, and the air taken through the space flows
into a hot air duct 92.
[0012] An intake air switch valve 81 is opened and closed so as to
switch the air taken from the hot air duct 92 and the air taken
from a fresh air duct 80. When the intake air switch valve 81 is
opened, air is taken from the hot air duct 92. When the intake air
switch valve 81 is closed, air is taken from the fresh air duct
80.
[0013] The intake air is cleaned by an air cleaner 82, an intake
amount of the air is detected by an air flow meter 83, and the air
is supercharged by a turbocharger 84. After the air, which is
supercharged by the turbocharger 84 (hereinafter, called
supercharged air) is cooled by an intercooler 85 (corresponding to
an aftercooler), the air is taken into an engine main body 88
flowing through an intake shutter 86 and an intake manifold 87.
[0014] When the intake air switch valve 81 is opened and the air,
which is heated by heat radiated from the PM filter device 90, is
taken into the engine, a temperature of an exhaust gas from the
engine can be increased. Then, since a temperature of the PM filter
device 90 can be promptly increased, a combustion efficiency of the
PM filter device 90 can be improved.
[0015] A fuel supplied from a fuel pump 93 to a common rail 94 is
mixed with the supercharged air cooled by the intercooler 85, and
the supercharged air is taken into the engine main body 88 as an
air/fuel mixed gas. That is, the fuel supplied from the fuel pump
93 to the common rail 94 is injected from an injection nozzle 95
and mixed with the supercharged air cooled by the intercooler
85.
[0016] After the air/fuel mixed gas is ignited and the engine is
driven, an exhaust gas as a combustion gas is exhausted from an
exhaust manifold 89.
[0017] The PM contained in the exhaust gas is captured by, and
deposited on, a filter of the PM filter device 90. Further, a part
of the exhaust gas is returned from the exhaust manifold 89 to the
intake manifold 87 flowing through an EGR cooler 96 and an EGR
valve 97.
[0018] A pressure difference between an inlet and an outlet of the
PM filter device 90 is detected by a difference pressure sensor 98.
Further, an inlet temperature of the PM filter device 90 is
detected by a PM filter device inlet temperature sensor 99, and an
outlet temperature is detected by a PM filter device outlet
temperature sensor 100. The signals detected by the sensors are
sent to an engine control unit 101. When clogging of the filter of
the PM filter device 90 is eliminated and the filter is refreshed,
a control is performed to introduce heated air from the hot air
duct 92 to increase a combustion efficiency of PM deposited on the
filter.
[0019] Incidentally, in, for example, a dump track as an work
machine, cooling devices such as a radiator, an aftercooler, and
the like are ordinarily disposed on a front surface of a vehicle
body so that wind generated when the vehicle travels is positively
used as cold wind.
[0020] Moreover, since a cooling fan for cooling the cooling
devices is often directly coupled with an engine, the cooling
devices are disposed in a limited space on the front surface side
of the engine. Accordingly, as shown also in the conventional
example 1 described above, a configuration in which cooling members
of the radiator, the aftercooler, and the like are overlapped is
employed.
[0021] In the configuration in which the cooling members are
overlapped as described above, a cooling member disposed on a rear
side of the overlapped cooling members is impinged with waste heat
wind preheated by a cooling member disposed in front of the cooling
member. Accordingly, a cooling efficiency of the cooling member
disposed on the rear side is lowered.
[0022] The problem can be solved by increasing a pressure receiving
area of the cooling member impinged with the waste heat wind in the
cooling device disposed on the rear side and increasing an amount
of air of a cooling fan of the cooling device disposed forward.
However, the increase in the pressure receiving area of the cooling
member and the increase in the amount of air of the cooling fan
result in an increase in a size of the cooling device itself
disposed on the rear side and use of a large cooling fan.
[0023] In this case, a new problem arises in that an installation
space, which is necessary to install the cooling device and the
cooling fan configured in the large size cannot be sufficiently
secured, the cooling device and the cooling fan interfere with
other equipment, and noise generated by the cooling fan is
increased. In particular, when heat rejection of the engine
increases, the layout configuration described above cannot overcome
the increased heat rejection.
[0024] To solve the problems, the applicant has proposed a cooling
device of a hydraulic shovel in which an aftercooler is disposed in
a space different from an engine room in which a radiator is
disposed (refer to Patent Document 3).
[0025] FIG. 9 shows a plan view of the cooling device of Patent
Document 3 as a conventional example 3 of the invention. As shown
in FIG. 9, an engine room 51 is disposed in an upper turning body
50 of a large hydraulic shovel in a direction lateral to a
traveling direction of the large hydraulic shovel. An engine 52 is
disposed in the engine room 51 laterally.
[0026] A radiator 55 and a hydraulic oil cooler 54 are disposed in
series forward of a cooling fan 53 directly coupled with the engine
52, and an air cleaner 57 is disposed above the engine 52. The air
cleaner 57 is connected to a turbocharger 56 via an air piping 60,
and the turbocharger 56 is connected to an air-cooled aftercooler
58 via an air piping 59. Further, the air-cooled aftercooler 58 is
connected to the engine 52 via an air piping 61.
[0027] Further, the air-cooled aftercooler 58 is disposed
separately outside the engine room 51 at a position approximately
adjacent laterally to the radiator 55 so as to be located near a
side wall portion side of the large hydraulic shovel.
PRIOR ART DOCUMENTS
Patent Documents
[0028] Patent Document 1: Japanese Patent Application Laid-Open No.
2007-138872
[0029] Patent Document 2: Japanese Patent Application Laid-Open No.
2005-299628
[0030] Patent Document 3: Japanese Patent Application Laid-Open No.
9-125972
SUMMARY OF THE INVENTION
Problems to be Solved by the Invention
[0031] In the cooling fan control device described in Patent
Document 1, the engine 70 and the PM filter device 75 are disposed
together in the engine room 71. Moreover, after the engine is
cooled by the waste heat wind from the cooling fan 72, an outer
periphery of the PM filter device 75 is cooled. Accordingly,
although the outer periphery of the PM filter device 75 can be
cooled a little, an outer periphery of the PM filter device 75, by
which PM is being combusted, cannot be forcibly cooled.
[0032] Accordingly, to prevent a heat damage to peripheral
equipment disposed in the periphery of the PM filter device 75, a
special countermeasure of surrounding the peripheral equipment by
an insulation material, and the like must be taken. Further,
although it is not particularly described to dispose an
aftercooler, even when the aftercooler is disposed, the aftercooler
is disposed in the engine room 71. Thus, a cooling efficiency of an
intake pipe connected to the aftercooler is lowered by warm air in
the engine room 71.
[0033] The filter refresh control device described in Patent
Document 2 is configured only to take the outside air from the
space formed between the PM filter device 90 and the heat shield
plate 91 and cannot forcibly cool an outer periphery of the PM
filter device 90 or control a temperature of the outer periphery of
the PM filter device 90. Moreover, since a periphery of the PM
filter device 90 must be covered with the heat shield plate 91, a
heat shield plate having a special specification must be used as a
heat shield plate that can be used for a long period.
[0034] Further, since the intercooler 85 is disposed in the engine
room, a cooling efficiency of an intake pipe connected to the
intercooler 85 is lowered by warm air in the engine room. In
particular, the air cooled by the intercooler 85 is warmed in an
intake pipe connected to the intercooler 85 by the warm air in the
engine room.
[0035] Further, to improve the combustion efficiency of PM in the
PM filter device 90, the intake air switch valve 81, the hot air
duct 92, and the like need to be disposed. Thus, an arrangement for
disposing the intake air switch valve 81, the hot air duct 92, and
the like becomes complex, and further an installation space for
installing the intake air switch valve 81 and the hot air duct 92
is necessary.
[0036] In the cooling device described in Patent Document 3, to
easily introduce outside air into the air-cooled aftercooler 58,
the air-cooled aftercooler 58 is disposed in the portion near the
side wall portion side of the large hydraulic shovel. Accordingly,
the air-cooled aftercooler 58 is disposed in a portion in a side
direction away from the portion where the engine is disposed in a
vehicle width direction of the large hydraulic shovel.
[0037] Since the cooling device is configured as described above,
the air piping 59, which connects the air-cooled aftercooler 58 to
the turbocharger 56, and the air piping 61, which connects the
air-cooled aftercooler 58 to the engine 52 each have a long length.
Moreover, the air piping 59 and the air piping 61 are disposed long
in the engine room 51.
[0038] In particular, since the air piping 61, through which the
air cooled in the air-cooled aftercooler 58 is caused to flow, is
disposed long in the engine room 51, the air which flows in the air
piping 61 is warmed by the warm air in the engine room 51.
Therefore, even if the air is cooled in the air-cooled aftercooler
58, a cooling effect of the air is lowered thereafter in the air
piping 61.
[0039] Moreover, since the air-cooled aftercooler 58 and the
radiator 62 are disposed along the vehicle width direction of the
large hydraulic shovel, it is difficult to effectively make use of
wind generated by traveling.
[0040] The invention, which has been made to overcome the
disadvantages described above, is to provide a heat
retention/cooling control device for a PM filter device which can
efficiently perform a temperature control of an outer periphery of
the PM filter device when combustion is performed by a filter of
the PM filter device, can cause the PM filter device to efficiently
perform combustion, and moreover does not apply an influence of a
heat damage to the peripheral portion of the PM filter device
effectively making use of wind generated by traveling.
Means for Solving the Problems
[0041] In order to achieve the above object, a heat
retention/cooling control device for a PM filter device for
reducing PM as particulate matters contained in an exhaust gas
exhausted from a diesel engine mounted on an work machine,
includes:
[0042] a cooling passage disposed in parallel with an engine room
configured in a front-back direction of the work machine and
demarcated from the engine room via a partition wall; an
aftercooler disposed in the cooling passage for cooling air
supercharged by a supercharger disposed in the engine room; the PM
filter device which is disposed on a downstream side of the
aftercooler in the cooling passage and into which the exhaust gas
from the engine is introduced; a cooling fan which is disposed in
the cooling passage, cools the aftercooler, and cools an outer
periphery of the PM filter device by waste heat wind which has
cooled the aftercooler;
[0043] a temperature sensor for detecting an exhaust gas
temperature of the exhaust gas; and a controller connected to the
temperature sensor for controlling an amount of air of the cooling
fan when the PM captured by a filter of the PM filter device PM is
combusted,
[0044] being characterized in that, when the exhaust gas
temperature detected by the temperature sensor is higher than a
target temperature, the controller performs a control for
increasing a cooling effect to the outer periphery of the PM filter
device by increasing the amount of air from the cooling fan, and
when the exhaust gas temperature detected by the temperature sensor
is lower than the target temperature, the controller performs a
control for assisting to increase and to retain a temperature in
the outer periphery of the PM filter device by reducing the amount
of air from the cooling fan.
[0045] Also in the invention, an exhaust pipe for introducing an
exhaust gas exhausted from the engine into the PM filter device is
disposed to receive wind from the cooling fan on an upstream side
of the PM filter device.
EFFECT OF THE INVENTION
[0046] In the invention, when the PM captured by the filter of the
PM filter device is combusted, an amount of air of a cooling fan,
which cools an aftercooler and the outer periphery of the PM filter
device, can be controlled by the controller based on an exhaust gas
temperature of an exhaust gas.
[0047] When the exhaust gas temperature of the exhaust gas is
higher than a target temperature at the time the PM captured by the
filter of the PM filter device is combusted, it can be determined
that the exhaust gas temperature is a temperature at which the PM
can be sufficiently combusted in the PM filter. At this time, to
reduce an influence of a heat damage due to combustion, the outer
periphery of the PM filter device can be cooled by increasing the
amount of air from the cooling fan.
[0048] Further, when the exhaust gas temperature of the exhaust gas
is lower than the target temperature at the time the PM is
combusted, it can be determined that the exhaust gas temperature
does not reach a temperature at which the PM can be sufficiently
combusted in the PM filter device. At this time, since a priority
is placed on sufficient combustion of the PM rather than on
reduction of the influence of heat damage, the cooling fan is
controlled to reduce the amount of air therefrom to increase the
exhaust gas temperature.
[0049] When the amount of air from the cooling fan is reduced, a
cooling efficiency of the aftercooler is lowered and a temperature
of the supercharged air taken from the aftercooler into the engine
can be increased. Then, since the temperature of the exhaust gas
exhausted from the engine is also increased, an oxidation catalyst
disposed on an upstream side of the filter can be easily oxidized
and caused to generate heat. With the operation, since the
temperature of the exhaust gas supplied to the filter is increased,
the PM clogged in the filter can be self-combusted.
[0050] When the combustion in the filter is sufficiently performed
and the exhaust gas temperature increases higher than the target
temperature, the cooling fan can be controlled to increase the
amount of air therefrom to cool the outer periphery of the PM
filter device in turn. Then, heat damage due to heat radiated from
the outer periphery of the PM filter device can be prevented.
[0051] In the invention, a cooling passage demarcated from the
engine room across a partition wall is disposed in parallel with
the engine room, and the aftercooler, the cooling fan for cooling
the aftercooler, and the PM filter device, to which the waste heat
wind exhausted from the cooling fan is supplied, are disposed in
the cooling passage.
[0052] With the configuration described above, since the wind
generated by traveling can be separately introduced into the engine
room and the cooling passage, a radiator disposed in the engine
room and the aftercooler disposed in the cooling passage can be
cooled efficiently. Moreover, an outer peripheral surface of the PM
filter device can be efficiently cooled by the waste heat wind by
which the aftercooler is cooled.
[0053] Further, the partition wall can make an inside of the
cooling passage unlikely to be influenced by the warm air in the
engine room. Since the aftercooler can be disposed in the cooling
passage which is unlikely to be influenced by the warm air in the
engine room, a cooling effect of the aftercooler and a cooling
effect when the outer peripheral surface of the PM filter device is
cooled by the waste heat wind after the aftercooler is cooled can
be increased.
[0054] Further, since the partition wall can prevent occurrence of
a turbulent flow caused by collision between the waste heat wind
from the radiator which flows in the engine room, and the waste
heat wind from the aftercooler which flows in the cooling passage,
the partition wall can prevent the amounts of the respective waste
heat wind from being reduced by the occurrence of the turbulent
flow.
[0055] Moreover, the waste heat wind from the radiator, which flows
in the engine room, can be caused to flow in the engine room as a
laminar flow, and the waste heat wind, which flows in the cooling
passage from the aftercooler, can be caused to flow in the cooling
passage as a laminar flow. As a result, the respective air flows
and the respective amounts of air in the engine room and in the
cooling passage can be influenced well.
[0056] Further, since the cooling passage is demarcated from the
engine room across the partition wall, noise generated from a
cooling fan for the radiator and noise from the engine can be
prevented from being leaked to the outside through the cooling
path.
[0057] Further, in the invention, an exhaust pipe, which introduces
the exhaust gas exhausted from the engine into the PM filter
device, can be disposed so as to receive wind from the cooling fan
upstream of the PM filter device. Then, when the PM filter device
performs combustion and is increased in temperature, the exhaust
pipe can be cooled by the wind from the cooling fan whose amount is
increased. With the operation, the exhaust gas temperature of the
exhaust gas introduced into the PM filter device can be prevented
from becoming excessively high.
[0058] Further, when the exhaust gas temperature of the exhaust gas
is lower than the target temperature at the time the PM is
combusted, since the cooling fan is controlled so as to reduce an
amount of air, a temperature drop of the exhaust pipe cooled by the
wind from the cooling fan can be suppressed low. The exhaust gas
can be introduced into the PM filter device without lowering a
temperature of the exhaust gas whose exhaust gas temperature is
increased. This operation can contribute to improving the
combustion efficiency of the PM filter device.
BRIEF DESCRIPTION OF THE DRAWINGS
[0059] FIG. 1 is a plan view showing a disposed state of a heat
retention/cooling control device of a PM filter device.
(embodiment)
[0060] FIG. 2 is a side elevational view of a partition wall when
viewed from an engine room. (embodiment)
[0061] FIG. 3 is a schematic plan view showing a schematic
disposition relation of the heat retention/cooling control device
for the PM filter device. (embodiment)
[0062] FIG. 4 is a block diagram showing a schematic configuration
of the heat retention/cooling control device for the PM filter
device. (embodiment)
[0063] FIG. 5 is a schematic sectional view of the PM filter
device. (embodiment)
[0064] FIG. 6 is a circuit diagram for controlling the number of
revolutions of a cooling fan. (embodiment)
[0065] FIG. 7 is a plan view of a cooling fan control device.
(conventional example 1)
[0066] FIG. 8 is a schematic view of a filter refresh control
device. (conventional example 2)
[0067] FIG. 9 is a plan view of a cooling device of a hydraulic
shovel. (conventional example 3)
BEST MODE FOR CARRYING OUT THE INVENTION
[0068] A typical embodiment of a heat retention/cooling control
device for a PM filter device according to the invention will be
explained below referring to the drawings.
EMBODIMENT
[0069] As shown in FIG. 1, an engine room 11 is disposed along a
front-back direction of an work machine 10, and an engine 12, a
cooling fan 14 disposed forward of the engine 12, a radiator 13 and
a hydraulic oil cooler 19 disposed forward of the cooling fan 14,
and the like are disposed in series in the engine room 11. Further,
an exhaust gas turbocharger 15 as a supercharger is disposed in an
upper portion of the engine 12 in the engine room 11.
[0070] Then, an upper portion of the engine room 11 is covered with
an engine hood 17 (refer to FIG. 2). Outside air above an upper
portion of the engine hood 17 is separated from the engine room 11
in the engine hood 17 by the engine hood 17. The engine room 11,
which is surrounded by the engine hood 17, a partition wall 18 to
be described later, and a lower surface plate of the engine room
11, is configured so that air flows along the front-back direction
of the work machine 10.
[0071] Further, the work machine 10 is mounted with a cab 23
disposed in an upper rear portion of the engine room 11, and right
and left front wheels (not shown), a transmission, an axle device,
and the like are disposed in a region below the cab backward of the
engine room 11.
[0072] A cooling passage 20 is disposed in parallel with the engine
room 11 along the front-back direction of the work machine 10. The
cooling passage 20 is surrounded by an aftercooler cover (not
shown), the partition wall 18, and a lower surface plate (not
shown), and the air, which is taken from an outside air
introduction port disposed forward of the aftercooler cover, flows
backward. As shown in FIG. 2, the partition wall 18 is disposed
under the engine hood 17, and is configured so that air does not
flow between the engine room 11 and the cooling passage 20.
[0073] Note that the aftercooler cover may be configured integrally
with the engine hood 17 that covers an upper portion of the engine
room 11 described above. On the contrary, the aftercooler cover may
have a divided configuration in a structure by which a flow of air
is not inhibited in place of the configuration by which the
aftercooler cover integrally covers up to a PM filter device 25
described later.
[0074] Further, as a part of a wall that configures the partition
wall 18, a side wall surface of an aftercooler 21 disposed in the
cooling passage 20 to be described later may be used. The partition
wall 18 may be configured to demarcate between the engine room 11
and the cooling passage 20 only by a wall without using the side
wall surface of the aftercooler 21. The partition wall 18 may be
configured to perfectly shut off between the engine room 11 and the
cooling passage 20 or may be configured to have a gap through which
air can enter and exit between the engine room 11 and the cooling
passage 20 a little without perfectly shutting off between the
engine room 11 and the cooling passage 20.
[0075] Even if the partition wall 18 is configured to have the gap,
it is preferable to configure the gap so that air, which flows in
the engine room 11, and the air, which flows in the cooling passage
20, are not disturbed by the air which enters from the gap.
[0076] An air cleaner 16, the aftercooler 21, a cooling fan 22 for
cooling the aftercooler 21, and the PM filter device (particulate
matter filter device) 25 the periphery of which is cooled by the
waste heat wind from the cooling fan 22 are disposed in series in
the cooling passage 20. The PM filter device 25 is disposed on a
side of the cab 23 upward of the front wheels (not shown).
[0077] The PM filter device is a device (filter) for reducing PM
(particulate matters) as particulate substances contained in an
exhaust gas of a diesel engine and basically configured as a device
for capturing the PM by the filter. The PM filter device 25 shown
in an illustrated example has a self-cleaning function capable of
refreshing the filter by combusting the PM captured by the filter
to prevent that a filter function from being lowered when the
filter is clogged.
[0078] The cooling fan 14, which is disposed forward of the engine
12, may be directly coupled with the engine 12 or may be driven by
a hydraulic motor driven by an ejection pressure from a hydraulic
pump (not shown) driven by the engine 12 like the cooling fan 22 of
the aftercooler 21. Alternatively, the cooling fan 14 may be driven
by an electrically driven motor.
[0079] When the cooling fan 14 and the cooling fan 22 are driven by
hydraulic motors, respectively, a degree of freedom of disposition
of the radiator 13, the hydraulic oil cooler 19, and the like to
the position at which the aftercooler 21 is disposed can be
increased. Further, the cooling air, which is caused to flow by the
cooling fan 14 and the cooling fan 22, may be configured as a flow
on an intake side with respect to the radiator 13 and the
aftercooler 21 as shown in FIG. 1 or may be configured as a flow on
an ejection side by disposing the cooling fan 14 and the cooling
fan 22 on a front surface side of the radiator 13 and the
aftercooler 21.
[0080] The radiator 13 is connected with a pair of pipings 29 (only
a piping 29 is illustrated in FIG. 1) and can cool cooling water
for cooling the engine 12. The exhaust gas turbocharger 15 is
connected with the air cleaner 16 disposed in the cooling passage
20 via a pipe passage 28. The pipe passage 28 is connected to the
air cleaner 16 passing through an opening 45 formed in the
partition wall 18 as shown in FIG. 2 as well as connected to the
exhaust gas turbocharger 15 in the engine room 11.
[0081] The outside air taken via the air cleaner 16 is supplied to
the exhaust gas turbocharger 15 via the pipe passage 28 and
supercharged by a compressor 15b (refer to FIG. 4) in the exhaust
gas turbocharger 15. After the outside air is supercharged, it is
supplied to the aftercooler 21 via an intake pipe 26a. The
compressor 15b is driven in rotation by the exhaust gas exhausted
from the engine 12.
[0082] The supercharged air cooled by the aftercooler 21 passes
through an intake pipe 26b and taken into the engine 12 via an
intake manifold (not shown). Then, the supercharged air is mixed
with a fuel and used for combustion in the engine 12. The exhaust
gas exhausted from the engine 12 after combustion is introduced
into the exhaust gas turbocharger 15 via an exhaust pipe 27a (refer
to FIG. 4).
[0083] After the exhaust gas introduced into the exhaust gas
turbocharger 15 is used to drive a turbine 15a (refer to FIG. 4),
it is introduced to the PM filter device 25 passing through an
exhaust pipe 27b. The exhaust pipe 27b is disposed so as to receive
the wind from the cooling fan 22 upstream of the PM filter device
25. The turbine 15a (refer to FIG. 4) drives the compressor 15b
(refer to FIG. 4) which supercharges the air taken via the air
cleaner 16.
[0084] The exhaust gas introduced into the PM filter device 25 is
exhausted to outside air passing through an exhaust pipe 27c (refer
to FIGS. 4 and 5) after PM is removed by the filter 32 (refer to
FIG. 5).
[0085] A connection port of the exhaust gas turbocharger 15, which
connects the intake pipe 26a connected to the aftercooler 21, and
an intake manifold of the engine 12 are disposed near the partition
wall 18. Further, as shown in FIG. 2, the partition wall 18 is
formed with an opening 46a and an opening 46b. The opening 46a is
formed as an opening for connecting the intake pipe 26a, which is
connected to the exhaust gas turbocharger 15, to the aftercooler
21, and the opening 46b is formed as an opening through which the
intake pipe 26b, which supplies the air cooled by the aftercooler
21 into the engine 12, passes.
[0086] As shown in FIGS. 1 and 3, the aftercooler 21 is disposed at
a position located laterally with a position where the engine 12 is
disposed. Note that FIG. 3 shows a schematic disposition relation
of the heat retention/cooling control device for the PM filter
device.
[0087] Since the heat retention/cooling control device is
configured as described above, wind generated by traveling can be
separately introduced into the engine room 11 and the cooling
passage 20. Moreover, since lengths of the intake pipes 26a, 26b in
the engine room 11 can be configured short, the air flowing in the
intake pipes 26a, 26b can be prevented from being warmed by the
warm air in the engine room 11.
[0088] With the configuration, since an inside of the cooling
passage 20 is unlikely to be influenced by the warm air in the
engine room 11, a cooling effect to the aftercooler 21 and a
cooling effect to an outer peripheral surface of the PM filter
device 25 can be increased.
[0089] In particular, since the cooling passage 20 can be
configured as a kind of duct which is opened in the front-back
direction, the wind generated by traveling, which is introduced
into the cooling passage 20, and the amount of air, which is
generated by the cooling fan 22 for the aftercooler 21, can be
effectively used as cooling wind for the aftercooler 21 and as
cooling wind for the outer peripheral surface of the PM filter
device 25.
[0090] As a result, an influence of heat to equipment (not shown)
disposed in the periphery of the PM filter device 25 can be
prevented by cooling the outer peripheral surface of the PM filter
device 25 and further an increase in temperature in the cab (not
shown) disposed adjacent to the PM filter device 25 can be
suppressed.
[0091] Moreover, since the noise generated in the engine room 11
can be shut off by the partition wall 18, a leakage of the noise
generated in the engine room 11 to the outside via the cooling
passage 20 can be prevented.
[0092] Further, the connection port of the exhaust gas turbocharger
15 for connecting the intake pipe 26a connected to the aftercooler
21 and the intake manifold of the engine 12 are disposed near the
partition wall 18, the piping lengths of the intake pipes 26a, 26b
in the engine room 11 can be configured short.
[0093] Since the lengths of the intake pipes 26a, 26b in the engine
room 11 can be configured short by the above configuration, the air
flowing in the intake pipes 26a, 26b is not exposed to the warm air
in the engine room 11 for a long time. As described above, the air
flowing in the intake pipes 26a, 26b can be prevented from being
warmed by the warm air in the engine room 11.
[0094] Next, the heat retention-cooling control device for the PM
filter device will be explained using FIGS. 4 and 5. Note that FIG.
4 illustrates a configuration of an ERG device which is disposed in
the engine room 11 demarcated from the cooling passage 20 by the
partition wall 18 and returns a part of the exhaust gas to the
engine 12. Further, FIG. 4 illustrates a configuration of a CCV
device (ventilation device) 42 which returns a blow-by gas, which
is discharged to a crankcase (not shown) of the engine 12, to the
engine 12 together with the air/fuel mixed gas taken into the
engine 12.
[0095] Accordingly, in FIG. 4, the EGR device, which is illustrated
omitting configurations of the radiator 13 and the like disposed in
the engine room 11, includes an EGR cooler 39 and an EGR valve 40
and configured so as to return the part of the exhaust gas into the
engine 12 via the intake pipe 26b after the gas is cooled by the
EGR cooler 39.
[0096] In the illustrated example, after the part of the exhaust
gas is cooled by the EGR cooler 39, it passes through the EGR valve
40 and is returned into the intake pipe 26b via a diaphragm 41
disposed in the intake pipe 26b. That is, the exhaust gas cooled by
the EGR cooler 39 is taken into the intake pipe 26b by a suction
operation in the diaphragm 41. An opening/closing amount of the EGR
valve 40 can be detected by a lift sensor 40a.
[0097] Further, the CCV device 42 is disposed because, although
respective cycles of so-called compression, combustion, and exhaust
are generally performed continuously in a diesel engine, the
air/fuel mixed gas leaks via a gap of a piston ring between the
respective cycles and the blow-by gas is discharged to the
crankcase.
[0098] Since a pressure in the crankcase is increased by the
blow-by gas, a leakage of oil from the crankcase is accelerated. A
conventional diesel engine is configured such that a pressure
increased in the crankcase is released to the atmosphere via a
breather.
[0099] However, it is proposed, from an environmental point of
view, to return the blow-by gas in the crankcase into a combustion
chamber without discharging it to the atmosphere. Thus, there is a
CCV device devised for the purpose. In the CCV device 42 of the
illustrated example which is configured to return the blow-by gas
together with the air/fuel mixed gas to the engine 12 and to
combust them in the engine 12, a pressure can be detected by a
pressure sensor 42a.
[0100] A configuration shown in FIG. 4 will be explained although
this is overlapped with the explanation in FIG. 1. The outside air
introduced from the air cleaner 16 is supplied to the compressor
15b of the exhaust gas turbocharger 15 via a piping 28. A flow rate
of the outside air introduced from the air cleaner 16 can be
detected by an air flow rate sensor 16a. Further, the blow-by gas
from the CCV device 42 joins the piping 28.
[0101] The air supplied to the compressor 15b turns into
supercharged air by the operation of the compressor 15b and
introduced into the aftercooler 21. The supercharged air cooled by
the aftercooler 21 is supplied with fuel while it is cooled, turns
into an air/fuel mixed gas, and is supplied to the engine 12.
Further, as described above, the part of the exhaust gas, which is
cooled by the EGR cooler 39 is mixed with the supercharged air and
supplied to the engine 12 via the diaphragm 41 disposed in the
intake pipe 26b.
[0102] Rotation of the engine 12 can be detected by an engine
rotation sensor 38. Further, a temperature of intake air supplied
to the engine 12 can be detected by an intake air temperature
sensor 37b, and a pressure of the intake air supplied to the engine
12 can be detected by an intake air pressure sensor 37a.
[0103] A part of the exhaust gas generated by the combustion in the
engine 12 is introduced into the EGR cooler 39, and a remaining
exhaust gas is introduced into the turbine 15a of the exhaust gas
turbocharger 15 passing through the exhaust pipe 27a. The turbine
15a is driven in rotation by the exhaust gas introduced thereinto
and drives in rotation the compressor 15b coupled with the turbine
15a. The number of revolutions of the compressor 15b can be
detected by a turbo rotation sensor 15c.
[0104] In the illustrated example, the turbine 15a is configured as
a variable speed turbine, and a capacity of the turbine can be
changed by changing an angle of a swash plate. The number of
revolutions of the turbine 15a can be controlled by changing the
capacity of the turbine. The angle of the swash plate can be
detected by a position sensor 15d.
[0105] The exhaust gas, which drives the turbine 15a in rotation,
is introduced into the PM filter device 25 passing through the
exhaust pipe 27b. As shown in FIG. 5, the PM filter device 25 is
configured such that an oxidation catalyst 31 and the filter 32,
which captures the PM, are accommodated in a cylindrical vessel 30
from an upstream side in a flow direction of the exhaust gas.
Insulation members 35 are disposed around the oxidation catalyst 31
and the filter 32. Further, a dosing injection fuel supply device
36 is disposed halfway of the exhaust pipe 27b for introducing the
exhaust gas into the PM filter device 25.
[0106] The oxidation catalyst 31 is a catalyst for oxidizing a
dosing fuel, which is supplied by the fuel supply device 36, and
causing the dosing fuel to generate heat, and an activation
temperature of the oxidation catalyst 31 is about 250.degree. C. in
terms of an exhaust gas temperature. The temperature of the exhaust
gas can be increased by the heat generated by the oxidation
catalyst 31, and the PM deposited on the filter 32 can be
self-combusted.
[0107] The filter 32 is configured to have a lot of small holes
communicating with each other from, for example, a flow-in side of
the exhaust gas to a flow-out side thereof. The small holes are
configured such that small holes whose flow-in sides are opened and
whose flow-out sides are closed, and small holes whose flow-in
sides are closed and whose flow-out sides are opened are
alternately disposed. When the exhaust gas, which flows into the
small holes whose flow-in sides are opened, passes through boundary
walls between adjacent small holes, the PM is captured by the
boundary walls.
[0108] Although a material of the filter 32 can be appropriately
selected according to a way of use, the filter 32 can be configured
using a ceramics material such as cordierite or silicon carbide,
and a metal material such as stainless steel or aluminum.
[0109] The PM filter device 25 is provided with a difference
pressure sensor 33 for measuring a difference between pressures in
front of and behind the filter 32, a temperature sensor 34a for
detecting a temperature of the exhaust gas introduced from the
exhaust pipe 27b, a temperature sensor 34b for detecting a
temperature of the exhaust gas after it passes through the
oxidation catalyst 31, and a temperature sensor 34c for detecting a
temperature of the exhaust gas after it passes through the filter
32. The exhaust gas, which passes through the filter 32 and from
which the PM is removed, passes through the exhaust pipe 27C and is
exhausted into the atmosphere.
[0110] The cooling fan 22, which cools the aftercooler 21 as well
as supplies the waste heat wind to an outer periphery of the PM
filter device 25, is controlled by a controller 43. The controller
43 controls an amount of air of the cooling fan 22 based on whether
an exhaust gas temperature of the exhaust gas detected by the
temperature sensor 34c is higher or lower than a preset target
temperature.
[0111] That is, when the controller 43 determines that the exhaust
gas temperature of the exhaust gas detected by the temperature
sensor 34c is higher than the preset target temperature at the time
the PM captured by the filter 32 of the PM filter device 25 is
combusted, the controller 43 determines that the PM is sufficiently
combusted in the PM filter device 25 and performs a control for
increasing the amount of air of the cooling fan 22.
[0112] With this operation, the outer periphery of the PM filter
device 25 can be sufficiently cooled by the waste heat wind after
it cools the aftercooler 21. Then, the influence of heat damage
caused by the PM filter device 25 can be prevented so that
peripheral equipment of the PM filter device 25 is not influenced
by the heat damage. At this time, since the exhaust pipe 27b
disposed on an upstream side of the PM filter device 25 can be
cooled by the increased amount of air from the cooling fan 22, the
exhaust gas temperature of the exhaust gas can be prevented from
becoming excessively high.
[0113] Even at the time the PM is combusted in a low outside air
temperature state, when it is determined that the exhaust gas
temperature of the exhaust gas detected by the temperature sensor
34c is lower than the preset target temperature, the cooling fan 22
is controlled so as to reduce the amount of air.
[0114] With this operation, since the supercharged air is
insufficiently cooled in the aftercooler 21, a temperature of the
supercharged air taken from the aftercooler 21 into the engine 12
is increased. Accordingly, the exhaust gas temperature of the
exhaust gas exhausted from the engine 12 is also increased.
Moreover, at this time, since the cooling fan is controlled so as
to reduce the amount of air, a temperature drop of the exhaust pipe
27b cooled by the wind from the cooling fan can be suppressed low.
This contributes to improving a combustion efficiency of the PM
filter device 25.
[0115] Since combustion in the oxide catalyst 31 is liable to
occur, the PM is liable to be self-combusted in the PM filter
device 25. When the PM is sufficiently self-combusted in the PM
filter device 25 and the exhaust gas temperature of the exhaust gas
detected by the temperature sensor 34c becomes higher than the
preset target temperature, the outer periphery of the PM filter
device 25 can be cooled by increasing the amount of air of the
cooling fan 22.
[0116] When the amount of air of the cooling fan 22 is reduced, a
temperature of the outer periphery of the PM filter device 25
cannot be suppressed low. However, when the exhaust gas temperature
of the exhaust gas detected by the temperature sensor 34c is lower
than the preset target temperature, since the temperature of the
outer periphery of the PM filter device 25 does not become so high,
the influence of heat damage to the peripheral equipment disposed
in the periphery of the PM filter device 25 can be reduced.
[0117] A configuration example for controlling the amount of air of
the cooling fan 22 will be explained using FIG. 6. In the
configuration example shown in FIG. 6, the amount of air from the
cooling fan 22 can be controlled by controlling the number of
revolutions of a hydraulic motor 44 for driving the cooling fan 22.
Specifically, the configuration example is configured such that
pressurized oil, which is ejected from a hydraulic pump 47 driven
by the engine 12 and configured as, for example, a gear pump, is
supplied to the hydraulic motor 44.
[0118] To control the pressurized oil ejected from the hydraulic
pump 47 and supplied to the hydraulic motor 44, a flow control
valve 48 is disposed at a position which bypasses an intake side
and a discharge side of the hydraulic motor 44. The flow control
valve 48 is switched by controlling a proportional electromagnetic
valve 49 disposed in a pilot line 24 in response to a control
command from the controller 43.
[0119] The proportional electromagnetic valve 49 is linearly driven
in response to the control command from the controller 43, thereby
controlling a pilot pressure P supplied to the proportional
electromagnetic valve 49. The flow control valve 48 is switched by
controlling the pilot pressure, which is supplied from the pilot
line 24 to switch the flow control valve 48, by the proportional
electromagnetic valve 49. With the operation, a flow rate of the
pressurized oil supplied to the hydraulic motor 44 is changed, and
the number of revolutions of the hydraulic motor 44 is
controlled.
[0120] In the example described above, the configuration example,
in which the hydraulic pump 47 and the hydraulic motor 44 are
configured as a fixed capacity by using the flow control valve 48,
has been explained. However, any one of the hydraulic pump 47 and
the hydraulic motor 44 can be also configured as a variable
capacity type without using the flow control valve 48.
[0121] Further, the cooling fan 22 may be driven by an electrically
driven motor in place of using the hydraulic motor. In this case,
the number of revolutions of the electrically driven motor can be
controlled by controlling a current supplied to the electrically
driven motor, whereby an amount of air from the cooling fan 22 can
be controlled.
[0122] As described above, in the invention, since the aftercooler
21, the cooling fan 22, and the PM filter device 25 are disposed in
the cooling passage 20 independent from the engine room 11, a
combustion control in the PM filter device 25 and a control of an
outer peripheral temperature can be efficiently performed by
controlling the amount of air of the cooling fan 22. Moreover, a
heat retention control to the PM filter device 25 and a cooling
control of the outer periphery can be performed by controlling the
amount of air of the cooling fan 22.
[0123] Note that the configuration example for controlling the
amount of air of the cooling fan 22 using the temperature detected
by the temperature sensor 34c as the exhaust gas temperature of the
exhaust gas has been described. However, the amount of air of the
cooling fan 22 can be controlled using the temperature detected by
the temperature sensor 34a or the temperature sensor 34b or can be
controlled by appropriately combining appropriate detected values
detected by the temperature sensors 34a to 34c.
INDUSTRIAL APPLICABILITY
[0124] The cooling device according to the invention can be
favorably applied to an work machine including a PM filter
device.
REFERENCE NUMERALS
[0125] 10 work machine [0126] 11 engine room [0127] 12 engine
[0128] 15 exhaust gas turbocharger [0129] 18 partition wall [0130]
20 cooling passage [0131] 21 aftercooler [0132] 25 PM filter device
[0133] 31 oxidation catalyst [0134] 32 filter [0135] 43 controller
[0136] 51 engine room [0137] 52 engine [0138] 53 cooling fan [0139]
55 radiator [0140] 56 turbocharger [0141] 58 air-cooled aftercooler
[0142] 70 engine [0143] 71 engine room [0144] 75 PM filter device
[0145] 84 turbocharger [0146] 85 intercooler [0147] 90 PM filter
device [0148] 91 heat shield plate [0149] 92 hot air duct [0150]
101 engine control unit
* * * * *