U.S. patent application number 12/326455 was filed with the patent office on 2009-06-11 for exhaust gas purifying system.
Invention is credited to Nami IKEDA, Yoshifumi KATO, Hiroyasu KAWAUCHI, Naotaka KOIDE.
Application Number | 20090145108 12/326455 |
Document ID | / |
Family ID | 40404488 |
Filed Date | 2009-06-11 |
United States Patent
Application |
20090145108 |
Kind Code |
A1 |
KOIDE; Naotaka ; et
al. |
June 11, 2009 |
EXHAUST GAS PURIFYING SYSTEM
Abstract
An exhaust gas purifying system is used for purifying exhaust
gas discharged from an internal combustion engine installed in a
vehicle. The exhaust gas purifying system includes an
electrochemical device and a control device. The electrochemical
device includes an anode, a cathode and an electrolyte layer
disposed between the anode and the cathode. The control device is
operable to control the internal combustion engine and the
electrochemical device. The control device receives data on
condition of the internal combustion engine and controls amount of
electric current to be supplied to the electrochemical device based
on the data. The data represents amount of exhaust gas. When the
control device recognizes that the amount of exhaust gas is
increased, the control device increases the amount of electric
current to be supplied to the electrochemical device.
Inventors: |
KOIDE; Naotaka; (Kariya-shi,
JP) ; IKEDA; Nami; (Kariya-shi, JP) ;
KAWAUCHI; Hiroyasu; (Kariya-shi, JP) ; KATO;
Yoshifumi; (Kariya-shi, JP) |
Correspondence
Address: |
Locke Lord Bissell & Liddell LLP;Attn: IP Docketing
Three World Financial Center
New York
NY
10281-2101
US
|
Family ID: |
40404488 |
Appl. No.: |
12/326455 |
Filed: |
December 2, 2008 |
Current U.S.
Class: |
60/275 |
Current CPC
Class: |
F01N 2240/34 20130101;
B01D 2258/012 20130101; F01N 3/0892 20130101; B01D 53/925 20130101;
B01D 53/326 20130101 |
Class at
Publication: |
60/275 |
International
Class: |
F01N 3/01 20060101
F01N003/01 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 3, 2007 |
JP |
2007-312220 |
Claims
1. An exhaust gas purifying system for purifying exhaust gas
discharged from an internal combustion engine installed in a
vehicle, comprising: an electrochemical device including an anode,
a cathode and an electrolyte layer disposed between the anode and
the cathode; and a control device operable to control the internal
combustion engine and the electrochemical device; wherein the
control device receives data on condition of the internal
combustion engine and controls amount of electric current to be
supplied to the electrochemical device based on the data.
2. The exhaust gas purifying system according to claim 1, wherein
the data represents amount of exhaust gas, wherein when the control
device recognizes that the amount of exhaust gas is increased, the
control device increases the amount of electric current to be
supplied to the electrochemical device, and when the control device
recognizes that the amount of exhaust gas is decreased, the control
device decreases the amount of electric current to be supplied to
the electrochemical device.
3. The exhaust gas purifying system according to claim 1, wherein
the electrochemical device is a plate-like shaped and has the anode
and the cathode on the opposite surfaces thereof, the electrolyte
layer allows ions to move between the anode and the cathode.
4. The exhaust gas purifying system according to claim 1, wherein
the data is at least one of an engine speed, an accelerator pedal
position, a throttle valve opening, oxygen concentration in exhaust
gas and exhaust gas temperature.
5. The exhaust gas purifying system according to claim 1, wherein
the anode is made of platinum based material.
6. The exhaust gas purifying system according to claim 1, wherein
the cathode is made of nickel based material.
7. The exhaust gas purifying system according to claim 1, wherein
the exhaust gas purifying system having a plurality of
electrochemical devices which are placed in an exhaust passage pipe
at a predetermined interval each other in the same orientation such
that each surface of the anode and the cathode is parallel to the
exhaust gas flow.
8. An exhaust gas purifying method for purifying exhaust gas
discharged from an internal combustion engine installed in a
vehicle, wherein the exhaust gas purifying system including an
electrochemical device having an anode, a cathode and an
electrolyte layer disposed between the anode and the cathode
comprising steps of: detecting data on condition of the internal
combustion engine and controlling amount of electric current to be
supplied to the electrochemical device based on the data.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to an exhaust gas purifying
system.
[0002] In a known purifying system, a diesel particulate filter
(DPF) or a selective catalytic reduction (SCR) catalyst with urea
is used for purifying exhaust gas discharged from an internal
combustion engine installed in a vehicle. Some of the systems are
operable to control the purifying capacity in accordance with
conditions of exhaust gas by adjusting the temperature of the
system or of exhaust gas.
[0003] Such a system controlling its purifying capacity by
adjusting the temperature is disclosed in Japanese Unexamined
Patent Application Publication No. 2004-124855. The publication
discloses post fuel injection or delayed fuel injection performed
for increasing the DPF temperature thereby to increase the exhaust
gas purifying capacity. On the other hand, an intake throttle is
fully opened for decreasing the DPF temperature thereby to decrease
the exhaust gas purifying capacity.
[0004] In a conventional exhaust gas purifying system, however, it
has been difficult to accurately control the purifying capacity. In
the above system disclosed in the reference No. 2004-124855, for
example, a time lag occurs from the time when adjusting temperature
is performed to the time when the temperature is actually increased
as controlled. In addition, the system is susceptible to errors due
to external disturbances. Therefore, it is difficult for such
system to ensure the controlling accuracy. Particularly, since the
system controls factors that are related to the internal combustion
engine such as the fuel injection and the intake throttle, it is
difficult for the system to control the purifying capacity without
taking account of running conditions of the vehicle.
[0005] The present invention is directed to providing an exhaust
gas purifying system so as to easily and accurately control the
exhaust gas purifying capacity without affecting running conditions
of the vehicle.
SUMMARY OF THE INVENTION
[0006] In accordance with an aspect of the present invention, an
exhaust gas purifying system is used for purifying exhaust gas
discharged from an internal combustion engine installed in a
vehicle. The exhaust gas purifying system includes an
electrochemical device and a control device. The electrochemical
device includes an anode, a cathode and an electrolyte layer
disposed between the anode and the cathode. The control device is
operable to control the internal combustion engine and the
electrochemical device. The control device receives data on
condition of the internal combustion engine and controls amount of
electric current to be supplied to the electrochemical device based
on the data. The data represents amount of exhaust gas. When the
control device recognizes that the amount of exhaust gas is
increased, the control device increases the amount of electric
current to be supplied to the electrochemical device.
[0007] Other aspects and advantages of the invention will become
apparent from the following description, taken in conjunction with
the accompanying drawings, illustrating by way of example the
principles of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] The features of the present invention that are believed to
be novel are set forth with particularity in the appended claims.
The invention together with objects and advantages thereof, may
best be understood by reference to the following description of the
presently preferred embodiments together with the accompanying
drawings in which:
[0009] FIG. 1 is an illustrative view showing an arrangement of an
exhaust gas purifying system and the related devices according to a
first preferred embodiment of the present invention;
[0010] FIG. 2 is a schematic view of an electrochemical device
according to FIG. 1; and
[0011] FIG. 3 is an illustrative view showing the operation of the
electrochemical device of FIG. 1 in purifying exhaust gas.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0012] The following will describe the first preferred embodiment
of the present invention with reference to FIGS. 1 through 3. FIG.
1 shows an arrangement of an exhaust gas purifying system 120 and
the related devices according to the first preferred embodiment.
The exhaust gas purifying system 120 is used for purifying exhaust
gas discharged from an internal combustion engine 100 installed in
a vehicle. The purification is achieved by decomposing nitrogen
oxides (NOx) and particulate matters (PM) contained in the exhaust
gas as will be described below.
[0013] As shown in FIG. 1, an exhaust passage pipe 110 is connected
to the internal combustion engine 100. The exhaust gas purifying
system 120 is disposed in the middle of the exhaust passage pipe
110. Exhaust gas discharged from the internal combustion engine 100
into the exhaust passage pipe 110 passes through the exhaust gas
purifying system 120. Then, purified gas is discharged out from the
exhaust passage pipe 110. The exhaust gas purifying system 120
includes a plurality of electrochemical devices 10. The
electrochemical device 10, which is known also as an
electrochemical reactor, is used for purifying exhaust gas by
electrochemical reaction. The electrochemical reaction performs by
supplying electric current from an external battery. The
electrochemical device 10 includes an anode 20, a cathode 22 and an
electrolyte layer 24 disposed between the anode 20 and the cathode
22. The electrochemical device 10 is a plate-like shaped and has
the anode 20 and the cathode 22 on the opposite surfaces
thereof.
[0014] Each electrochemical device 10 is spaced apart at a
predetermined interval in the same orientation such that each
surface of the electrodes of the electrochemical devices 10 is
parallel to the flow direction of exhaust gas. Specially, the anode
20 and the cathode 22 of any two adjacent electrochemical devices
10 face and extend parallel to each other. Such arrangement of the
electrochemical devices 10 allows the exhaust gas to pass through
the spaces between the each anode 20 and the cathode 22 in the
exhaust gas purifying system 120.
[0015] FIG. 2 is a schematic view of one of the electrochemical
devices 10. The electrochemical device 10 is electrically connected
at the anode 20 and the cathode 22 to an external battery 30. The
anode 20 of the electrochemical device 10 is connected to the
positive electrode of the battery 30, while the cathode 22 of the
electrochemical device 10 is connected to the negative electrode of
the battery 30. The electrolyte layer 24 of the electrochemical
device 10 includes electrolyte and allows ions to move between the
anode 20 and the cathode 22.
[0016] The anode 20 and the cathode 22 of the electrochemical
device 10 are made of materials functioning as the respective
electrodes. For example, the anode 20 is made of a screen-printed
platinum (Pt) based material while the cathode 22 is made of a
screen-printed nickel (Ni) based material. The electrolyte layer 24
is made of ion-conductive electrolyte material such as
yttria-stabilized zirconia (YSZ) so as to conduct proton or oxygen
ion. The electrochemical device 10 operates most effectively under
a temperature in the range between 600 and 800 degrees Celsius. The
optimal temperature range varies depending on the chemical
composition of the electrolyte layer 24.
[0017] Referring to FIG. 1, the internal combustion engine 100 and
the exhaust passage pipe 110 are provided with detectors for
detecting various data on condition of the internal combustion
engine 100. The detectors include an engine speed sensor 41, an
accelerator position sensor 42, a throttle position sensor 43, an
oxygen sensor 44 and a temperature sensor 45. The engine speed
sensor 41, the accelerator position sensor 42 and the throttle
position sensor 43 are mounted to the internal combustion engine
100. The speed sensor 41 detects the engine speed of the internal
combustion engine 100. The accelerator position sensor 42 detects
the accelerator pedal position. The throttle position sensor 43
detects the throttle valve opening. The oxygen sensor 44 and the
temperature sensor 45 are mounted to the exhaust passage pipe 110.
The oxygen sensor 44 detects the oxygen concentration in exhaust
gas. The temperature sensor 45 detects the exhaust gas temperature.
Each of the sensors 41 through 45 does not necessarily have to be
located at the position as described above and illustrated in FIG.
1. The accelerator position sensor 42 and the throttle position
sensor 43 may be mounted to an accelerator pedal and a throttle
valve respectively. In the illustrated embodiment, the oxygen
sensor 44 and the temperature sensor 45 are mounted to the exhaust
passage pipe 110 on the side upstream of the exhaust gas purifying
system 120 as viewed in the direction of the flow of exhaust gas.
Alternatively, the sensors 44, 45 may be arranged on the opposite
side downstream of the exhaust gas purifying system 120.
[0018] The vehicle is provided with an engine control unit (ECU) 50
serving as a control device receiving the data from the sensors 41
through 45. The ECU 50 is electrically connected to each of the
engine speed sensor 41, the accelerator position sensor 42, the
throttle position sensor 43, the oxygen sensor 44 and the
temperature sensor 45 so as to receive the data. The ECU 50
receives the data from the sensors 41 through 45 periodically, for
example, at every second.
[0019] The ECU 50 is also electrically connected to each of the
electrochemical devices 10 for controlling its performance by
regulating the amount of electric current to be supplied to each of
the electrochemical devices 10 according to the data that
represents the condition of the internal combustion engine 100. The
electric current control is accomplished by changing the state of
an electrical circuit connecting the battery 30 and the
electrochemical device 10 periodically, for example, at every one
second.
[0020] Each of the detected values has a positive correlation with
the amount of exhaust gas. That is, the amount of exhaust gas is
increased with an increase of the engine speed, the accelerator
pedal position, the throttle valve opening, the oxygen
concentration in exhaust gas and the exhaust gas temperature, and
vice versa.
[0021] The ECU 50 controls the operation of the electrochemical
device 10 in a way that the amount of electric current to be
supplied to the electrochemical device 10 is increased in
accordance with an increase of the amount of exhaust gas. Namely,
when the data represents an increase of the amount of exhaust gas,
the ECU 50 recognizes a state that the amount of exhaust gas is
increased and increases the amount of electric current to be
supplied to the respective electrochemical devices 10. On the other
hand, when the data represents a decrease of the amount of exhaust
gas, the ECU 50 recognizes a state that the exhaust gas is
decreased and decreases the amount of electric current to be
supplied to the respective electrochemical devices 10. In other
words, the ECU 50 controls the amount of electric current to be
supplied to the electrochemical device 10 in such a manner that the
amount of electric current is a monotonically increasing function
of each value of the engine speed, the accelerator pedal position,
the throttle valve opening, oxygen concentration in exhaust gas and
exhaust gas temperature. The functional relation between the amount
of electric current supplied to the electrochemical device 10 and
each of the values (engine speed, accelerator pedal position,
throttle valve opening, oxygen concentration in exhaust gas and
exhaust gas temperature) can be specified based on experimental
results and the like.
[0022] Referring to FIG. 1, the ECU 50 is connected to the
electrochemical devices 10 in such a way that the ECU 50 controls
the respective electrochemical devices 10 individually.
Alternatively, the ECU 50 may be connected in such a way that the
ECU 50 controls a plurality of or all of the electrochemical
devices 10 collectively. Furthermore, the ECU 50 also serves as a
common ECU for controlling other various operations of the
vehicle.
[0023] The following will describe the operation of the exhaust gas
purifying system 120. Referring to FIG. 1, exhaust gas produced by
running the internal combustion engine 100 is discharged and flows
into the exhaust gas purifying system 120 through the exhaust
passage pipe 110. Then, the exhaust gas flows inside the exhaust
gas purifying system 120 in contact with or flowing through spaces
around the surfaces of the anode 20 and the cathode 22 of the
electrochemical devices 10. While the exhaust gas is passing
through the exhaust gas purifying system 120, PM and NOx contained
in the exhaust gas are decomposed with the result that the exhaust
gas is purified.
[0024] FIG. 3 shows the operation of the electrochemical device 10
in purifying exhaust gas. Carbon in PM contained in exhaust gas is
reacted on or around the surface of the anode 20 with oxygen ions
conducted through the electrolyte layer 24 thereby to produce
carbon dioxide and electrons. Electrons are attracted by the
positive electrode of the battery 30 and moved to the battery 30.
Carbon dioxide is discharged out of the exhaust passage pipe 110 to
the atmosphere. PM is thus decomposed at the anode 20, with the
result that the exhaust gas is purified. Nitrogen oxides (NOx) in
the exhaust gas are reacted on or around the surface of the cathode
22 with electrons supplied from the battery 30 thereby to produce
oxygen ions and nitrogen. Oxygen ions are attracted by the anode 20
of the electrochemical device 10 and moved through the electrolyte
layer 24. Nitrogen is discharged out of the exhaust passage pipe
110 to the atmosphere. NOx is thus decomposed at the cathode 22,
with the result that the exhaust gas is purified.
[0025] It is noted that the performance of the electrochemical
device 10, which is the exhaust gas purifying capacity, depends on
the amount of electric current supplied to the electrochemical
device 10. The larger the amount of electric current from the anode
20 to the cathode 22 through the electrolyte layer 24 is, the
higher the capacity to decompose PM and NOx in exhaust gas is.
Consequently, the larger amount of exhaust gas is purified.
[0026] The following will describe the control by the ECU 50 and
the process for purifying exhaust gas in the exhaust gas purifying
system 120. While the vehicle is running under a normal condition,
the internal combustion engine 100 is also running under a normal
condition and the data is almost constant. In such a case, the ECU
50 maintains the amount of electric current to be almost constant.
When the vehicle driver operates the accelerator to change the
position, for example, to increase the engine speed. Then, the
engine speed sensor 41 and the accelerator position sensor 42
detect the changes respectively and the data representing such
changes are inputted into the ECU 50. Since the data represent an
increase of amount of exhaust gas, the ECU 50 increases the amount
of electric current to be supplied to the electrochemical device
10. As a result, the exhaust gas purifying capacity of the
electrochemical device 10 is increased. In this way, purifying of
increased amount of exhaust gas is accomplished appropriately.
[0027] As described above, the exhaust gas purifying system 120
according to the preferred embodiment includes the electrochemical
devices 10 and the ECU 50. The ECU 50 is operable to control the
exhaust gas purifying capacity by changing the amount of electric
current to be supplied to the electrochemical device 10 based on
the data on the conditions of the internal combustion engine 100.
Thus, controlling of the exhaust gas purifying capacity of the
exhaust gas purifying system 120 is achieved easily and
accurately.
[0028] Since it is easy to control the amount of electric current,
the exhaust gas purifying system 120 of the present invention is
capable of controlling the exhaust gas purifying capacity more
easily and accurately as compared with the conventional systems
that control the system temperature or exhaust gas temperature for
purification of exhaust gas. Furthermore, the exhaust gas purifying
system 120 of the present invention is capable of avoiding damages
caused by heat generated in the system. More advantageously, the
exhaust gas purifying system 120 controlling the amount of electric
current will not affect running conditions of other vehicle
equipments such as electronic fuel injection system and, therefore,
it contributes to fuel consumption.
[0029] In the above-described preferred embodiment, the data
includes engine speed, accelerator pedal position, throttle valve
opening, oxygen concentration in the exhaust gas and exhaust gas
temperature. In addition, the data may include other data such as
the amount of PM or NOx concentration in exhaust gas. For example,
a sensor for detecting the amount of PM or NOx concentration in the
exhaust gas may be provided in the exhaust passage pipe 110 to
control the amount of electric current to be supplied to the
electrochemical device 10 based on the detected amount of PM or NOx
concentration. In this case, the ECU 50 operates such that the
amount of electric current is increased in accordance with an
increase of the detected amount of PM or NOx concentration.
Alternatively, an acceleration sensor for detecting accelerated
velocity may be installed in the vehicle to control the amount of
electric current to be supplied to the electrochemical device 10
depending on the detected velocity. In this case, the ECU 50 is
operated such that the amount of electric current is increased with
an increase of the detected velocity. The data may include further
other values such as those indicative of the so-called operating
modes of the vehicle.
[0030] Also in the above-described preferred embodiment, the ECU 50
operable to control the exhaust gas purifying capacity by changing
the amount of electric current to be supplied to the
electrochemical device 10. Alternatively, the ECU 50 may be
operable to control the exhaust gas purifying capacity by changing
the voltage to be applied across the electrochemical devices 10 of
the exhaust gas purifying system 120.
[0031] Therefore, the present examples and embodiments are to be
considered as illustrative and not restrictive, and the invention
is not to be limited to the details given herein but may be
modified within the scope of the appended claims.
* * * * *