U.S. patent application number 12/988912 was filed with the patent office on 2011-02-24 for exhaust gas-aftertreatment device and control method thereof.
This patent application is currently assigned to SK ENERGY CO., LTD.. Invention is credited to Yongwoo Kim, Youngshol Kim, Changq Lee, Haejin Park.
Application Number | 20110041478 12/988912 |
Document ID | / |
Family ID | 41217277 |
Filed Date | 2011-02-24 |
United States Patent
Application |
20110041478 |
Kind Code |
A1 |
Lee; Changq ; et
al. |
February 24, 2011 |
Exhaust Gas-Aftertreatment Device and Control Method Thereof
Abstract
The present invention relates to an exhaust gas-aftertreatment
device and a control method thereof. More specifically, the
invention relates to an exhaust gas-aftertreatment device, which
employs a burner and a metal filter, so that the filter can be
regenerated within a short time at high temperature, and wherein
the burner is operated when the vehicle is idling, and wherein the
filter can be efficiently regenerated by forming a flame in a
stable manner using a dispersion means, and which furthermore has
enhanced durability, and to a method for controlling the same.
Inventors: |
Lee; Changq; (Daejeon,
KR) ; Kim; Yongwoo; (Daejeon, KR) ; Kim;
Youngshol; (Daejeon, KR) ; Park; Haejin;
(Daejeon, KR) |
Correspondence
Address: |
THE WEBB LAW FIRM, P.C.
700 KOPPERS BUILDING, 436 SEVENTH AVENUE
PITTSBURGH
PA
15219
US
|
Assignee: |
SK ENERGY CO., LTD.
Seoul
KR
|
Family ID: |
41217277 |
Appl. No.: |
12/988912 |
Filed: |
April 23, 2009 |
PCT Filed: |
April 23, 2009 |
PCT NO: |
PCT/KR2009/002128 |
371 Date: |
October 21, 2010 |
Current U.S.
Class: |
60/274 ; 60/277;
60/286; 60/303; 60/311; 60/324 |
Current CPC
Class: |
F01N 2560/08 20130101;
F01N 2560/14 20130101; F01N 2240/20 20130101; F01N 2900/12
20130101; Y02T 10/40 20130101; F01N 2240/14 20130101; F01N 9/002
20130101; F01N 2560/06 20130101; F01N 2330/12 20130101; F01N 3/025
20130101; F01N 13/009 20140601; Y02T 10/47 20130101 |
Class at
Publication: |
60/274 ; 60/303;
60/311; 60/324; 60/277; 60/286 |
International
Class: |
F01N 3/00 20060101
F01N003/00; F01N 3/10 20060101 F01N003/10; F01N 3/02 20060101
F01N003/02; F01N 1/00 20060101 F01N001/00; F01N 11/00 20060101
F01N011/00; F01N 9/00 20060101 F01N009/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 23, 2008 |
KR |
10-2008-0037876 |
Claims
1. An exhaust gas-aftertreatment device for reducing exhaust gas
emission from a diesel engine, comprising: a body which has, on one
outer side, an exhaust gas inlet connected with an exhaust pipe to
introduce the exhaust gas into the system, and on the other side,
an exhaust gas outlet for emitting purified exhaust gas; a burner
including a fuel injection means, placed adjacent to the exhaust
gas inlet of the body and having a nozzle section provided at an
end thereof to inject atomized fuel, an ignition means for igniting
the injected fuel, and a dispersion means for guiding the fuel
injected through the fuel injection means and the exhaust gas
introduced through the exhaust gas inlet to a metal filter; the
metal filter provided at the rear end of the burner to burn organic
or particulate matter in the exhaust gas; and a control means for
controlling operation of the burner and determining a state of the
system.
2. The exhaust gas-aftertreatment device of claim 1, wherein the
metal filter is made of Fecalloy.
3. The exhaust gas-aftertreatment device of claim 2, wherein the
surface of the metal filter is heat-treated.
4. The exhaust gas-aftertreatment device of claim 3, wherein the
heat treatment of the surface is carried out in an air atmosphere
at a temperature of 900 to 1000.degree. C. to form an aluminum
oxide film on the surface.
5. The exhaust gas-aftertreatment device of claim 1, wherein the
dispersion means is designed such that the diameter thereof becomes
wider from the fuel injection means in a direction of the metal
filter, and a plurality of openings are formed in the dispersion
means such that the exhaust gas introduced through the exhaust gas
inlet goes through the openings to an inside of the dispersion
means and effectively mixes with the fuel in the dispersion means,
and a flame is formed in a stable manner.
6. The exhaust gas-aftertreatment device of claim 5, wherein the
openings are formed at an angle in a tangential direction of the
dispersion means, such that the exhaust gas that went through the
openings into the dispersion means has a specific flow pattern.
7. The exhaust gas-aftertreatment device of claim 5, wherein the
exhaust gas-aftertreatment device further comprises an air
injection means for injecting air into the nozzle section of the
fuel injection means.
8. The exhaust gas-aftertreatment device of claim 5, wherein the
control means serves to determine the state of the system with the
information provided by a pressure sensor located at the front end
of the exhaust gas-aftertreatment device or the metal filter, two
temperature sensors measuring temperatures of front and rear ends
of the metal filter, RPM sensor of the engine, or GPS (Global
Positioning System) information.
9. The exhaust gas-aftertreatment device of claim 1, wherein the
exhaust gas-aftertreatment device further comprises an alarm means
for notifying of a sensed system state or emergency determined by
the control means.
10. A method for controlling the exhaust gas-aftertreatment device
of any one of claims 1, comprising: an active
regeneration-determining step for determining whether operation of
the burner is required, after operation of the engine; an alarm
signal-transmitting step for notifying an alarm signal to a vehicle
driver with an alarm means, if it is determined in the active
regeneration-determining step that operation of the burner is
required; an idling state-determining step for determining whether
the vehicle is in an idling state, after the alarm
signal-transmitting step; an active regeneration step for operating
the burner to perform active regeneration, if it is determined in
the idling state-determining step that the vehicle is in the idling
state and if a user's instruction to do regeneration operation is
input; and an active regeneration end step for stopping the burner
to end the active regeneration, after performing the active
regeneration step.
11. The method of claim 10, wherein it is determined in the active
regeneration-determining step that, if a pressure measured by a
pressure sensor is higher than a first pressure criteria or if an
average pressure measured by the pressure sensor for a specific
period of time is higher than a second pressure criteria, the
burner should be operated.
12. The method of claim 11, wherein the first pressure criteria is
150-250 mbar, and the second pressure criteria is 75-150 mbar.
13. The method of claim 11, wherein the method further comprises a
system state-checking step for checking the state of the system,
after the operation of the engine.
14. The method of claim 13, wherein the active
regeneration-determining step is performed again when the engine is
operated after the active regeneration end step.
15. The method of claim 10, wherein the amount of fuel injected
into the burner in the active regeneration step is controlled such
that a temperature of a front end of the metal filter is in the
range of 600 to 900.degree. C.
Description
TECHNICAL FIELD
[0001] The present invention relates to an exhaust
gas-aftertreatment device and a control method thereof, and more
particularly to an exhaust gas-aftertreatment device, which employs
a burner and a metal filter, so that the filter can be regenerated
within a short time at high temperature, and wherein the burner is
operated when the vehicle is idling, and wherein the filter can be
efficiently regenerated by forming a flame in a stable manner using
a dispersion means, and which furthermore has enhanced durability,
and to a method for controlling the same.
Background Art
[0002] Diesel engines allow fuel consumption to be reduced while
having high power output compared to gasoline engines. Diesel
engines are therefore mainly used in large vehicles and are also
increasingly being used in light duty vehicles.
[0003] However, diesel engines use 4-stroke engines in which fuel
is injected and burned by compression ignition, so that imperfect
combustion occurs due to the non-uniform distribution of fuel and
air during the auto-ignition of fuel and noxious particulates
(smoke) are generated.
[0004] The noxious particulates are mainly nitrogen oxide (NOx),
particulate matter (PM), and soot, and there are reports that
noxious particulates caused by diesel vehicles account for 40% of
the total amount of air pollution. For this reason, many countries
regulate the emission of particulates, and to be in compliance with
these regulations, particulate reduction systems that are inserted
in exhaust pipes in order to reduce particulates have been
reported.
[0005] The particulate reduction systems can be broadly classified
into: a passive-regeneration system that traps particulates by a
catalytic filter and catalytically oxidizes the trapped
particulates at a given temperature or higher; and an
active-regeneration system that forcibly increases the temperature
of particulates using an external heat source.
[0006] The passive-regeneration particulate reduction system is
problematic in that the passive regeneration of the filter by the
catalyst is difficult in low-speed zones such as traffic jam zones,
because the temperature of particulates is reduced in such
zones.
[0007] In particular, the passive-regeneration particulate
reduction system is difficult to apply to vehicles that idle a lot,
such as cleaning vehicles or low-speed buses in the city or other
places with congested traffic. If it uses low-sulfur diesel (LSD)
or high-sulfur diesel (HSD) as fuel, sulfates which are very
harmful to the human body will be produced, and for this reason,
only ultra-low-sulfur diesel (ULSDP) needs to be used.
[0008] Moreover, if the catalyst does not perform its function, the
exhaust back pressure of the engine will be increased to reduce the
power output and increase the consumption of fuel, and if this
phenomenon continues, not only the filter, but also the engine,
will be damaged.
[0009] Meanwhile, the active-regeneration particulate reduction
system includes, in addition to the passive-regeneration system
with the catalytic filter, an electric heater, a plasma burner,
etc.
[0010] As an example of using the electric heater, Korean Patent
Laid-Open Publication No. 2004-68792 discloses a diesel engine
particulate reduction system as shown in FIG. 1.
[0011] The diesel engine particulate reduction system shown in FIG.
1 serves to regenerate particulates using a catalyst in order to
reduce particulates. In the diesel engine particulate reduction
system, at least one of electric heaters 4 that can spatially
unevenly distribute heat is coupled with a catalytic unit 8 in
order to promote catalytic activation or NO-to-NO.sub.2 conversion
efficiency in low-temperature ranges.
[0012] The diesel engine particulate reduction system shown in FIG.
1 is provided with the electric heaters that activate the catalytic
reaction such that the passive regeneration of the filter smoothly
occurs. However, because it requires a battery of significantly
large capacity to increase the temperature of particulates, it is
difficult to apply in practice. Also, because it needs to be
provided with separate devices, it is large in size and complex in
structure, and thus has low economic efficiency.
[0013] As another example of the active-generation system, a plasma
reactor was proposed. However, the plasma reactor is expensive,
increasing the total cost of production, and it requires a very
high voltage of 100,000 volts to generate plasma, such that a
large-capacity, complex converter for inducing the
plasma-generating voltage is required in vehicles that are operated
at 12 or 24 volts. Also, the plasma reactor is difficult to
maintain, because routine cleaning is required to prevent the
contamination of the ignition unit, and repair for the same reason.
In addition, there is a problem in that the plasma reactor is
difficult to use commercially.
[0014] As still another example of the active-regeneration system,
a burner that generates a flame using diesel fuel as a raw material
can increase the efficiency with which exhaust gases are reduced by
completely combusting the fuel. However, it uses a flame while the
vehicle is running, and thus if a flammable material is located in
the vicinity thereof, there will be a risk of explosion or the
like. In addition, there is a problem in that it is difficult to
form a stable flame, because the flow rate and temperature of
exhaust gas change in a complex manner depending on the running
pattern of the vehicle.
DISCLOSURE
Technical Problem
[0015] The present invention has been made in order to solve the
above-described problems occurring in the prior art, and it is an
object of the present invention to provide an exhaust
gas-aftertreatment device, which employs a burner and a metal
filter, so that the filter can be regenerated within a short time
at high temperature, wherein the burner is operated when the
vehicle is in the idling state, so as to perform the active
regeneration of the filter in a stable manner without a risk
factor, thereby increasing exhaust gas reduction efficiency and
safety, and which furthermore can be applied in all vehicles
without regard to the kind, displacement, running pattern and the
like of an engine, and to a method for controlling the same.
Another object of the present invention is to provide an exhaust
gas-aftertreatment device system which has a dispersion means that
enables the efficiency of filter regeneration to be increased by
effectively mixing fuel with exhaust gas, and which allows the
durability and reliability of the filter to be improved upon by
using a metal filter made of Fecalloy having good thermal
conductivity so as to prevent the filter from being damaged by
cracking or melting.
Technical Solution
[0016] To achieve the above object, in one aspect, the present
invention provides an exhaust gas-aftertreatment device for
reducing exhaust gas emitted from a diesel engine, comprising: a
body which has, on one outer side, an exhaust gas inlet connected
with an exhaust pipe to introduce the exhaust gas into the system,
and on the other side, an exhaust gas outlet for emitting purified
exhaust gas; a burner including a fuel injection means, placed
adjacent to the exhaust gas inlet of the body and having a nozzle
section provided at the end thereof to inject atomized fuel, an
ignition means for igniting the injected fuel, and a dispersion
means for guiding the fuel injected through the fuel injection
means and the exhaust gas introduced through the exhaust gas inlet
to a metal filter; the metal filter provided at the rear end of the
burner to burn organic or particulate matter in the exhaust gas;
and a control means for controlling the operation of the burner and
determining the state of the system.
[0017] In the exhaust gas-aftertreatment device of the present
invention, the metal filter is preferably made of Fecalloy. Also,
the surface of the metal filter is preferably heat-treated. The
heat treatment of the surface is preferably carried out in an air
atmosphere at a temperature of 900 to 1000.degree. C. to form an
aluminum oxide film on the surface.
[0018] Also, the dispersion means is preferably formed such that
the diameter thereof becomes wider from the fuel injection means in
a direction of the metal filter, and a plurality of openings are
preferably formed in the dispersion means such that the exhaust gas
introduced through the exhaust gas inlet goes through the openings
to the inside of the dispersion means and effectively mixes with
the fuel in the dispersion means and a flame is formed in a stable
manner. Herein, the openings are preferably formed at an angle in
the tangential direction of the dispersion means, such that the
exhaust gas that went through the openings into the dispersion
means has a specific flow pattern.
[0019] Moreover, the exhaust gas-aftertreatment device preferably
further comprises an air injection means for injecting air into the
nozzle section of the fuel injection means.
[0020] Furthermore, the control means serves to determine the state
of the system with a pressure sensor located at the front end of
the exhaust gas-aftertreatment device or the metal filter,
temperature sensors and for measuring the temperatures of the front
and rear ends of the metal filter, RPM sensor of the engine, or GPS
(Global Positioning System) information. Also, the exhaust
gas-aftertreatment device preferably further comprises an alarm
means for notifying of a sensed system state or emergency
determined by the control means.
[0021] In another aspect, the present invention provides a method
for controlling the above-described exhaust gas-aftertreatment
device, the method comprising: an active regeneration-determining
step for determining whether operation of the burner is required,
after operation of the engine; an alarm signal-transmitting step
for notifying an alarm signal to a vehicle driver with an alarm
means, if it is determined in the active regeneration-determining
step that the operation of the burner is required; an idling
state-determining step for determining whether the vehicle is in an
idling state, after the alarm signal-transmitting step; an active
regeneration step for operating the burner to perform active
regeneration, if it is determined in the idling state-determining
step that the vehicle is in the idling state and if the user's
instruction to do regeneration operation is input; and an active
regeneration end step of stopping the operation of the burner to
end the active regeneration, after performing the active
regeneration step.
[0022] In the inventive method for controlling the exhaust
gas-aftertreatment device, preferably, it is determined in the
active regeneration-determining step that, if a pressure measured
by a pressure sensor is higher than a first pressure criteria or if
an average pressure measured by the pressure sensor for a specific
period of time is higher than a second pressure, the burner should
be operated. Herein, the first pressure criteria is preferably
150-250 mbar, and the second pressure is preferably 75-150
mbar.
[0023] Moreover, the inventive method for controlling the exhaust
gas-aftertreatment device preferably further comprises a system
state-checking step for checking the state of the system after the
operation of the engine. Furthermore, when the engine is operated
after the active regeneration end step, the active
regeneration-determining step is performed again. In addition,
preferably, the amount of fuel injected into the burner in the
active regeneration step is controlled such that the temperature of
the front end of the metal filter is in the range of 600 to
900.degree. C.
Advantageous Effects
[0024] According to the exhaust gas-aftertreatment device of the
present invention and the method for controlling the exhaust
gas-aftertreatment device, the burner and the metal filter are used
together, and the dispersion means mixes the fuel and the exhaust
gas with each other, so that a flame is formed in a stable manner.
Thus, the filter can be regenerated within a short time by burning
particulates. Also, the metal filter is made of Fecalloly having
good thermal conductivity, and thus damage to the filter caused by
cracking or melting, which has often occurred in the prior ceramic
filters, can be prevented, thereby improving the durability and
reliability of the filter.
[0025] Moreover, according to the exhaust gas-aftertreatment device
of the present invention and the method for controlling the exhaust
gas-aftertreatment device, the burner is operated while a vehicle
is in the idling state, whereby the active regeneration of the
filter can be performed in a stable manner when it is required,
thereby increasing the efficiency of exhaust gas reduction. In
addition, safety can be enhanced by eliminating external risk
factors, and the system and method of the present invention can be
applied in all vehicles without regard to the kind, displacement
and running pattern of an engine.
DESCRIPTION OF DRAWINGS
[0026] FIG. 1 is a schematic diagram showing an exhaust
gas-aftertreatment device according to the prior art.
[0027] FIG. 2 is a schematic diagram showing an exhaust
gas-aftertreatment device according to the present invention.
[0028] FIG. 3 shows a burner of the exhaust gas-aftertreatment
device shown in FIG. 2.
[0029] FIG. 4 is an A-A' cross-sectional view of FIG. 3.
[0030] FIG. 5 shows another burner of the exhaust
gas-aftertreatment device according to the present invention.
[0031] FIG. 6 is a schematic view showing the flow of fuel and
exhaust gas in the exhaust gas-aftertreatment device according to
the present invention.
[0032] FIG. 7 is a schematic diagram showing a method for
controlling the exhaust gas-aftertreatment device according to the
present invention.
[0033] FIG. 8 is a graph showing the temperature and pressure of
exhaust gas in the exhaust gas-aftertreatment device according to
the present invention.
[0034] FIG. 9 is a schematic diagram showing another method for
controlling the exhaust gas-aftertreatment device according to the
present invention.
[0035] FIG. 10 is a schematic diagram showing still another method
for controlling the exhaust gas-aftertreatment device according to
the present invention.
DESCRIPTION OF MAIN REFERENCE NUMERALS USED IN THE DRAWINGS
[0036] 100: exhaust gas-aftertreatment device; 110: body; 111:
exhaust gas inlet; 112: exhaust gas outlet; 120: burner; 121: fuel
injection means; 122: nozzle section; 123: ignition means; 124:
dispersion means; 125: openings; 126: air injection means; 130:
metal filter; 140: control means; 141: pressure sensor; 142 and
143: temperature sensors; 150: alarm means; 200: engine; 210:
exhaust pipe; and S100 to S700: steps of the inventive method for
controlling the exhaust gas-aftertreatment device.
MODE FOR INVENTION
[0037] Hereinafter, the inventive exhaust gas-aftertreatment device
100 having the above-described features and a method for
controlling the same will be described in detail with reference to
the accompanying drawings.
[0038] FIG. 2 is a schematic diagram showing the exhaust
gas-aftertreatment device 100 according to the present invention;
FIG. 3 shows a burner 120 in the exhaust gas-aftertreatment device
100 shown in FIG. 2; FIG. 4 is an A-A' cross-sectional view of FIG.
3; FIG. 5 shows another burner 120 in the exhaust
gas-aftertreatment device 100 according to the present invention;
and FIG. 6 is a schematic view showing the flow of fuel and exhaust
gas in the exhaust gas-aftertreatment device 100 according to the
present invention.
[0039] The exhaust gas-aftertreatment device 100 according to the
present invention is a system for reducing exhaust gas emitted from
a diesel engine 200 and largely comprises: a body 110 having an
exhaust gas inlet 111 through which the exhaust gas is introduced
and an exhaust gas outlet 112 through which the exhaust gas is
emitted; a burner 120 for performing the active generation of a
filter; a metal filter 130 for burning organic or particulate
matter in the exhaust gas; and a control means 140.
[0040] The body 110 is a fundamental body forming the exhaust
gas-aftertreatment device 100 of the present invention and has, on
one side, the exhaust gas inlet 112 connected with an exhaust pipe
210 through which the exhaust gas emitted from the diesel engine
200 flows, and on the other side, the exhaust gas outlet 112
through which the purified exhaust gas is emitted. In the body 110,
the burner 120 and the metal filter 130 are placed sequentially in
the direction of flow of the exhaustion gas.
[0041] FIGS. 2 and 3 show an example in which the exhaust gas inlet
111 and the exhaust gas outlet 112 are provided at the front and
rear ends of the body 110, respectively, so that the exhaust gas
inlet 111, the burner 120, the metal filter 130 and the exhaust gas
outlet 112 are placed sequentially in the movement direction of the
exhaust gas. FIG. 5 shows an example in which the exhaust gas inlet
111 is formed at the upper portion of one side of the body, such
that the exhaust gas has a stepped flow.
[0042] FIGS. 2, 3 and 5 show one embodiment of the exhaust
gas-aftertreatment device 100 according to the present invention,
and the body 110 may be configured in various ways, in addition to
the one shown in the embodiment.
[0043] The burner 120 is an element for active regeneration and
comprises a nozzle section 122 at the end thereof, a fuel injection
means 121 for injecting atomized fuel, an ignition means 123, and a
dispersion means 124 for guiding dispersed fuel.
[0044] The fuel injection means 121 is placed adjacent to the
exhaust gas inlet 111 and has the nozzle section 122 provided
therein, and thus it serves to inject atomized fuel. The amount of
fuel injected is controlled by the control means 140 and influences
a flame formed by the burner 120 to have a direct influence
directly the temperatures of the front and rear ends of the
filter.
[0045] In fuel injection by the nozzle section 122, the angle at
which fuel is injected is preferably controlled to an angle of
about 45-60.degree. such that a flame is formed throughout the
inside of the body 110.
[0046] The control means 140 determines the state of the system
with a pressure sensor 141 placed at the front end of the exhaust
gas-aftertreatment device 100 or the metal filter 130 (FIG. 2 shows
an example in which the pressure sensor 141 is placed at the front
end of the exhaust gas-aftertreatment device 100), two temperature
sensors 142 and 143 for measuring the temperatures of the front and
rear ends of the metal filter 130, the RPM sensor of the engine
200, or global positioning system (GPS) information as indicated by
dotted lines in FIG. 2, and based on the determined results,
transmits a control signal to the fuel injection means 121 as
indicated by a solid line in FIG. 2 so as to inject a programmed
amount of fuel.
[0047] FIG. 2 shows an example wherein the engine RPM, the pressure
sensor 141 located at the front end of the exhaust
gas-aftertreatment device 100, and two temperature sensors 142 and
143 for measuring the temperatures of the front and rear ends of
the metal filters 130 are used as sources of information which is
to be input to the control means 140. However, the control means
140 of the present invention may use only part of the elements
shown in FIG. 2 and may further use the GPS (global positioning
system) information.
[0048] Operational control by the control means 140 will now be
described in detail.
[0049] Although the control of fuel injection amount by the control
means 140 is not shown in the figures, pressure that is applied to
a fuel pump located in a pipe connected with a fuel storage section
can be minutely controlled by controlling the operation of the fuel
pump, and the control of the amount of fuel injected can be
performed by providing additional information from two temperature
sensors 142 and 143 as feedback to be compared with a set
temperature rise pattern or target value.
[0050] Also, the exhaust gas-aftertreatment device 100 of the
present invention may further comprise an air injection means for
injecting air into the nozzle section 122 in order to prevent the
nozzle section 122 of the fuel injection means 121 from being
clogged with particles contained in the exhaust gas. Although FIGS.
3 and 5 show an example in which the air injection means 136 is
provided around the fuel injection means 121 in the form of a
double tube, any configuration that can inject air to prevent the
clogging of the nozzle section 122 may be formed in various
ways.
[0051] The air injection means 126 injects air of specific pressure
at a given interval, wherein the specific pressure is preferably
about 1 bar.
[0052] The exhaust gas-aftertreatment device 100 of the present
invention may comprise, in place of the air injection means 126, an
open/shut means (not shown) for opening and shutting the nozzle
section 122 which performs the same function. More specifically, in
order to prevent the nozzle section 122 from being clogged with the
exhaust gas particles, the open/shut means opens the nozzle section
122 while the fuel is being injected by the fuel injection means
121, and shuts the nozzle section 122 when fuel injection
ceases.
[0053] The ignition means 123 for igniting the injected fuel is
heated to a surface temperature of 1200 to 1500.degree. C., and it
is provided in such a manner that the portion to be heated comes
into contact with the range of fuel injected by the fuel injection
means 121. Also, it is placed so as to form a flame toward the
metal filter 130 and is controlled by the control means 140.
[0054] Herein, in order to effectively increase the temperature of
the exhaust gas and burn the exhaust gas, it is important to stably
maintain the flame. If a large amount of exhaust gas is introduced
through the exhaust gas inlet 111, the flame can become weaker, and
for this reason, the exhaust gas-aftertreatment device 100 is
provided with the dispersion means 124 within the burner 120.
[0055] The dispersion means 124 serves to protect the flame and to
guide the fuel injected through the fuel injection means 121 and
the exhaust gas introduced through the exhaust gas inlet 111 to the
metal filter 130. More specifically, the dispersion means 124 has a
cone shape, the diameter of which gradually becomes wider from the
fuel injection means 121 in the direction of the metal filter, or a
shape similar thereto. It has a plurality of openings 125.
[0056] The openings 125 are formed such that the exhaust gas
introduced through the exhaust gas inlet 111 moves into the
dispersion means 124 in which the flame is formed. A plurality of
these openings is along the length and width directions of the
dispersion means 124.
[0057] Also, as shown in FIG. 4, the openings 125 are preferably
formed at an angle in the tangential direction of the dispersion
means 124, such that the exhaust gas that moved into the dispersion
means 124 through the openings 125 has a certain flow.
[0058] When the openings 125 are formed at an angle, the flow of
the exhaust gas will create a swirling pattern (see FIG. 6). In
this case, thus, the exhaust gas-aftertreatment device 100 of the
present invention has an advantage in that the fuel and the exhaust
gas smoothly mix and are uniformly distributed throughout the metal
filter, thereby increasing the efficiency of exhaust gas
reduction.
[0059] Namely, the exhaust gas-aftertreatment device 100 of the
present invention comprises the dispersion means 124 which prevents
the flame from coming into direct contact with the exhaust gas,
such that the flame is stably formed and the degree of mixing of
the exhaust gas and the fuel is increased, thereby increasing the
efficiency of exhaust gas reduction.
[0060] The metal filter 130 is provided following the burner 120
and is configured to burn organic or particulate matter in the
exhaust gas heated by the burner 120. It is made of Fecalloy having
high temperature resistance, and the surface thereof may be
heat-treated to form an oxide layer.
[0061] Herein, the surface heat-treatment is preferably carried out
at a temperature of 900 to 1000.degree. C. in an air atmosphere to
form an aluminum oxide film that increases the efficiency of
exhaust gas reduction.
[0062] In addition, because the metal filter 130 is exposed to high
temperature because it is in direct contact with a flame, it may be
coated with a catalyst capable of resisting high temperatures.
[0063] The metal filter 130 of the present invention has a low
melting point but high thermal conductivity and low thermal
expansion properties, compared to the prior-art ceramic filter.
Because the exhaust gas-aftertreatment device 100 of the present
invention employs the metal filter 130, it has an advantage in that
it can increase the durability of the filter by solving the problem
of the prior ceramic filter that is damaged by partial cracking or
melting.
[0064] More specifically, filters made of ceramic materials such as
cordierite or silicon carbide (SiC) do not have general thermal
durability due to their high melting point, but have low thermal
conductivity. For this reason, if the amount of exhaust gas is
rapidly increased while a vehicle is running or the flow thereof
becomes non-uniform such that the exhaust gas is locally
excessively trapped, a certain portion of the ceramic filter will
overheat and the heat will not be transferred, and thus will crack
or melt at that portion.
[0065] Particularly, the overheating temperature is more than
2000.degree. C. which is higher than the melting point of the
ceramic filter and thus damages the ceramic filters. Once just if
even a local portion of the ceramic filter is damaged, the flow of
exhaust gas will be deflected more, and thus the durability of the
ceramic filter will fall off more rapidly.
[0066] For this reason, the exhaust gas-aftertreatment device 100
of the present invention employs the metal filter 130 made of
Fecalloy having high thermal conductivity, low thermal capacity and
low thermal expansion properties. Thus, there is an advantage in
that, even if the flow of exhaust gas is deflected so that a
certain portion of the filter overheats, the heat can be rapidly
transferred to the surrounding portion such that the filter can be
prevented from being damaged.
[0067] Moreover, the exhaust gas-aftertreatment device of the
present invention may further comprise an alarm means which is
connected with the control means 140 to notify the vehicle driver
of the sensed system state and emergency determined by the control
means 140.
[0068] The alarm means serves to visually or acoustically notify
the user of the state and may be a means which can use a visual
signal such as LED or an acoustic alarm with a buzzer or recorded
sound either alone or in combination. The alarm means enables the
vehicle driver to directly confirm the state of the exhaust
gas-aftertreatment device 100 and to more actively cope with
problems that have occurred.
[0069] FIG. 7 is a schematic diagram showing a method for
controlling the exhaust gas-aftertreatment device 100 according to
the present invention; FIG. 8 is a graph showing the temperature
and pressure of exhaust gas in the exhaust gas-aftertreatment
device 100 according to the present invention; FIG. 9 is a
schematic diagram showing another method for controlling the
exhaust gas-aftertreatment device 100 according to the present
invention; and FIG. 10 is a schematic diagram showing still another
method for controlling the exhaust gas-aftertreatment device 100
according to the present invention. The inventive method for
controlling the exhaust gas-aftertreatment device 100 is carried
out using the exhaust gas-aftertreatment device 100 and comprises:
an active regeneration-determining step (S100), after the engine
200 has been put into operation; an alarm signal-transmitting step
(S200); an idling state-determining step (S300); an input of
instruction to do regeneration operation (S410); an active
regeneration step (S420); and an active regeneration end step
(S500).
[0070] The active regeneration-determining step S100 is a step for
determining whether the operation of the burner 120 is required. In
this step, the control means 140 determines that, if the pressure
measured by the pressure sensor 141 is higher than a first pressure
criteria or if an the average pressure measured by the pressure
sensor 141 for a given time is higher than a second pressure, the
burner 120 should be operated.
[0071] Preferably, the first pressure criteria is 150-250 mbar, and
the second pressure is 75-150 mbar.
[0072] As shown in FIG. 8, because there is a great change in
exhaust gas pressure and temperature when the vehicle is running,
whether particulates are excessively accumulated is determined
using the maximum pressure and average pressure, thereby
determining whether the active regeneration of the filter is
required.
[0073] In FIG. 8, T.sub.in means a value measured by two
temperature sensor 142 located at the front end of the metal
filter, T.sub.out means a value measured by the temperature sensor
143 located at the rear end of the metal filter, and "Back
Pressure" means a value measured by the pressure sensor 141.
[0074] In the case of vehicles running at low speed, an increase in
back pressure cannot be great, even if particulates are
accumulated. Thus, in the active regeneration-determining step 100
in the method for controlling the exhaust gas-aftertreatment device
100 according to the present invention, at a given time after the
operation of the pressure sensor 141 or the engine 200, an alarm
signal can be transmitted, or the running state of the vehicle can
be determined by looking at the RPM sensor of the engine 200 or GPS
(Global Positioning System) information, or the amount of
particulates trapped by the metal filter 130 can be calculated.
[0075] The alarm signal transmitting step (S200) is a step of
notifying the vehicle driver that the operation of the burner 120
is required. This step serves to eliminate the risk of explosion
caused by a flammable material, which can occur if the burner 120
is operated, during running of the vehicle, in a state in which the
vehicle driver does not recognize it.
[0076] After the user have received the alarm signal, the vehicle
is stopped at a safe place in which there is no risk of fire. If it
is determined in the idling state-determining step (S300) that the
vehicle is in an idling state, and if the user's instruction to do
regeneration operation is input (S410), the burner 120 is then
operated to carry out the active regeneration step (S420).
[0077] If regeneration is performed when running, the concentration
of oxygen in exhaust gas is low and regeneration efficiency is low,
compared to if regeneration is performed in an idling state. Also,
in this case, the filter is cooled due to the weight of the vehicle
to increase the consumption of energy for heating the filter to a
temperature required for regeneration, and a problem of reliability
arises because of the complexity of the system. For these reasons,
according to the method for controlling the exhaust
gas-aftertreatment device of the present invention, after it has
been confirmed in the idling state-determining step (S300) that the
vehicle is in an idling state, the active regeneration of the
filter is performed.
[0078] In the active regeneration step (S420), the burner 120 is
operated while controlling the fuel injection means 121, the
ignition means 123 or the air injection means 126 by the control
means 140, and the exhaust gas can be suitably heated by
controlling the amount of fuel injected. Also, the amount of fuel
injected is controlled by real-time analysis of the value measured
by two temperature sensor 142 located at the front end of the
filter.
[0079] Herein, although the particulates accumulated on the filter
can be burned at a temperature of generally more than 600.degree.
C., the temperature of the front end of the filter can be
controlled to a higher temperature such that the particulates can
be burned within a shorter period of time. The temperature is
generally controlled to about in the range of 600 to 900.degree.
C.
[0080] Of course, the control means 140 controls the amount of fuel
injected based on the temperature measured by the temperature
sensor 143 located at the rear end of the filter, and the active
regeneration of the filter should be performed such that the filter
is not damaged. After the active regeneration step (S420) has been
performed to smoothly burn the exhaust gas, the operation of the
burner 120 is stopped to end active regeneration (S500).
[0081] In addition, as shown in FIG. 9, the method for controlling
the exhaust gas-aftertreatment device 100 of the present invention
may further comprise a step (S600) for checking the state of the
system after the engine 200 has been operated. It is preferable
that the user be alerted by the alarm means of the state that is
checked in the system state checking step S600.
[0082] Also, after the completion of active regeneration, the
vehicle is run and generates exhaust gas, and thus the active
regeneration of the filter may be required again. Accordingly, as
shown in FIG. 10, in the method for controlling the exhaust
gas-aftertreatment device 100 of the present invention, when the
engine 200 is operated after the active regeneration step (S500),
the active regeneration-determining step S100 is performed
again.
[0083] As described above, the method for controlling the exhaust
gas-aftertreatment device 100 according to the present invention
has an advantage in that the active regeneration of the filter is
achieved in a faster and safer manner, because whether the active
regeneration is required is determined by understanding the
information about the vehicle and because the burner 120 is
operated only when the vehicle is idling.
[0084] In particular, in the prior method for controlling the
exhaust gas-aftertreatment device, the types of information that
can be input are the vehicle conditions, such as RPM, exhaust gas
pressure and temperature, and there is a risk of fire, because it
is impossible to understand the environment of the surroundings
where the vehicle is located. On the contrary, in the inventive
method for controlling the exhaust gas-aftertreatment device, the
safety of the regeneration process is ensured, because the driver
understands the surrounding environment and determines whether
regeneration is required.
[0085] In addition, the user can confirm the state of the exhaust
gas-aftertreatment device in real time, and the regeneration of the
filter is performed under the control of the user. Thus, the risk
of accidents can be reduced.
[0086] Although the preferred embodiment of the present invention
has been described for illustrative purposes, those skilled in the
art will appreciate that various modifications, additions and
substitutions are possible, without departing from the scope and
spirit of the invention as disclosed in the accompanying
claims.
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