U.S. patent application number 13/641993 was filed with the patent office on 2013-02-07 for control system of internal combustion engine.
This patent application is currently assigned to TOYOTA JIDOSHA KABUSHIKI KAISHA. The applicant listed for this patent is Takamitsu Asanuma, Daichi Imai, Kyoung-Oh Kim, Yuichi Sobue, Kou Sugawara. Invention is credited to Takamitsu Asanuma, Daichi Imai, Kyoung-Oh Kim, Yuichi Sobue, Kou Sugawara.
Application Number | 20130034469 13/641993 |
Document ID | / |
Family ID | 44833874 |
Filed Date | 2013-02-07 |
United States Patent
Application |
20130034469 |
Kind Code |
A1 |
Asanuma; Takamitsu ; et
al. |
February 7, 2013 |
CONTROL SYSTEM OF INTERNAL COMBUSTION ENGINE
Abstract
A control system of an internal combustion engine in which a
catalyst device having oxidation ability is arranged in the exhaust
system, is provided. When a temperature of the catalyst device is
lower than a set temperature, the combustion temperature is made a
first combustion temperature or under or is made a second
combustion temperature or over, to make an amount of lower olefin
in the exhaust gas smaller than that when the combustion
temperature is higher than the first combustion temperature and is
lower than the second combustion temperature. Therefore, an amount
of lower olefin which reduces the oxidation rate of CO in the
catalyst device is decreased so as to realize the quick warming-up
of the catalyst device by using of the oxidation reaction heat of
CO.
Inventors: |
Asanuma; Takamitsu;
(Mishima-shi, JP) ; Sobue; Yuichi; (Susono-shi,
JP) ; Imai; Daichi; (Susono-shi, JP) ;
Sugawara; Kou; (Kakegawa-shi, JP) ; Kim;
Kyoung-Oh; (Susono-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Asanuma; Takamitsu
Sobue; Yuichi
Imai; Daichi
Sugawara; Kou
Kim; Kyoung-Oh |
Mishima-shi
Susono-shi
Susono-shi
Kakegawa-shi
Susono-shi |
|
JP
JP
JP
JP
JP |
|
|
Assignee: |
TOYOTA JIDOSHA KABUSHIKI
KAISHA
Toyota-shi, Aichi
JP
|
Family ID: |
44833874 |
Appl. No.: |
13/641993 |
Filed: |
April 22, 2010 |
PCT Filed: |
April 22, 2010 |
PCT NO: |
PCT/JP2010/057639 |
371 Date: |
October 18, 2012 |
Current U.S.
Class: |
422/114 |
Current CPC
Class: |
F01N 3/0835 20130101;
Y02T 10/26 20130101; Y02T 10/12 20130101; F01N 13/0097 20140603;
F01N 3/103 20130101; F02D 2200/0802 20130101; F02D 41/0255
20130101 |
Class at
Publication: |
422/114 |
International
Class: |
F01N 3/20 20060101
F01N003/20 |
Claims
1. A control system of an internal combustion engine in which a
catalyst device having the oxidation ability is arranged in the
exhaust system, wherein when a temperature of said catalyst device
is lower than a set temperature, the combustion temperature is made
a first combustion temperature or under or is made a second
combustion temperature or over, to make an amount of lower olefin
in the exhaust gas smaller than that when the combustion
temperature is higher than said first combustion temperature and is
lower than said second combustion temperature.
2. A control system of an internal combustion engine according to
claim 1, wherein an engine operating area in which the combustion
temperature becomes higher than said first combustion temperature
and lower than said second combustion temperature is set, and when
the temperature of said catalyst device is lower than the set
temperature, it is prohibited that the engine operates in said
engine operating area.
3. A control system of an internal combustion engine according to
claim 2, wherein the worse the combustion becomes, the more said
engine operating area is expanded to the high engine load side.
Description
TECHNICAL FIELD
[0001] The present invention relates to a control system of an
internal combustion engine.
BACKGROUND ART
[0002] To purify HC and CO in exhaust gas, an oxidation catalyst
device or a three-way catalyst device is arranged in an engine
exhaust system. Such a catalyst device having the oxidation ability
does not activate sufficiently in a low temperature condition like
immediately after the starting-up of the engine. It is desired for
the catalyst device to be warmed up quickly to an activation
temperature in order to increase the purification ability of HC and
CO.
[0003] In the catalyst device having the oxidation ability, CO can
be oxidized at a lower temperature than that at which HC can be
oxidized. Therefore, first, the oxidation reaction heat of CO
raises the temperature of the catalyst device. Incidentally, it is
known that HC obstructs the oxidation of CO and therefore, the
smaller the amount of coexisted HC, the more the oxidation rate of
CO can be increased.
[0004] It has been suggested that a HC adsorption device is
arranged immediately upstream the catalyst device (for example,
refer to International Publication WO 00/27508). Accordingly, an
amount of HC coexisting with CO in the catalyst device can be
reduced by the adsorption of HC in the HC adsorption device.
DISCLOSURE OF THE INVENTION
[0005] Even if the HC adsorption device is arranged immediately
upstream the catalyst device as mentioned above, in an engine
operating state, the oxidation rate of CO cannot be increased very
much and the quick warming-up of the catalyst device cannot be
realized.
[0006] Accordingly, an object of the present invention is to
provide a control system of an internal combustion engine, which
can sufficiently increase the oxidation rate of CO in a catalyst
device having the oxidation ability to realize the quick warming-up
of the catalyst device.
[0007] A control system of an internal combustion engine in which a
catalyst device having the oxidation ability is arranged in the
exhaust system as set forth in claim 1 of the present invention is
provided, characterized in that when a temperature of the catalyst
device is lower than a set temperature, the combustion temperature
is made a first combustion temperature or under or is made a second
combustion temperature or over, to make an amount of lower olefin
in the exhaust gas smaller than that when the combustion
temperature is higher than the first combustion temperature and is
lower than the second combustion temperature.
[0008] A control system of an internal combustion engine as set
forth in claim 2 of the present invention is provided as the
control system of an internal combustion engine as set forth in
claim 1 characterized in that an engine operating area in which the
combustion temperature becomes higher than the first combustion
temperature and lower than the second combustion temperature is
set, and when the temperature of the catalyst device is lower than
the set temperature, it is prohibited that the engine operates in
the engine operating area.
[0009] A control system of an internal combustion engine as set
forth in claim 3 of the present invention is provided as the
control system of an internal combustion engine as set forth in
claim 2 characterized in that the worse the combustion is, the more
the engine operating area is expanded to the high engine load
side.
[0010] According to the control system of an internal combustion
engine as set forth in claim 1 of the present invention, when a
temperature of the catalyst device having the oxidation ability,
which is arranged in the engine exhaust system, is lower than a set
temperature, a combustion temperature is made a first combustion
temperature or under or is made a second combustion temperature or
over, to make an amount of lower olefin, which particularly reduces
the oxidation rate of CO, in the exhaust gas smaller than that when
the combustion temperature is higher than the first combustion
temperature and is lower than the second combustion temperature.
Therefore, the oxidation rate of CO is sufficiently increased so as
to realize the quick warming-up of the catalyst device.
[0011] According to the control system of an internal combustion
engine as set forth in claim 2 of the present invention, in the
control system of an internal combustion engine as set forth in
claim 1, an engine operating area in which the combustion
temperature is higher than the first combustion temperature and
lower than the second combustion temperature is set, and when the
temperature of the catalyst device is lower than the set
temperature, it is prohibited that the engine operates in the
engine operating area. Therefore, the combustion temperature can be
easily made the first combustion temperature or under or made the
second combustion temperature or over.
[0012] According to the control system of an internal combustion
engine as set forth in claim 3 of the present invention, in the
control system of an internal combustion engine as set forth in
claim 2, the worse the combustion becomes, the more the engine
operating area is expanded to the high engine load side due to the
lowering of the combustion temperature. Therefore, even if the
combustion deteriorates, the combustion temperature can be
certainly made the first combustion temperature or under or made
the second combustion temperature or over.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 is a schematic view showing the exhaust system of an
internal combustion engine which is controlled by a control system
according to the present invention.
[0014] FIG. 2 is a time-chart showing changes of the oxidation rate
of CO in an oxidation catalyst device.
[0015] FIG. 3 is a graph showing a relationship between a
combustion temperature and a concentration of lower olefin in the
exhaust gas.
[0016] FIG. 4 is a first flow-chart showing a control of the engine
by the control system according to the present invention.
[0017] FIG. 5 is a second flow-chart showing a control of the
engine by the control system according to the present
invention.
[0018] FIG. 6 is a map showing an area in which the engine
operation is prohibited in the second flow-chart.
BEST MODE FOR CARRYING OUT THE INVENTION
[0019] FIG. 1 is a schematic view showing the exhaust system of an
internal combustion engine which is controlled by a control system
according to the present invention. In the figure, reference
numeral 1 is an exhaust passage and reference numeral 2 is a
three-way catalyst device or a catalyst device having the oxidation
ability with a honeycomb-shaped base material on which at least an
oxidation catalyst such as platinum is carried (including a
NO.sub.x storing/reducing catalyst device). The engine may be a
spark-ignition engine or a diesel engine.
[0020] Reference numeral 3 is a HC adsorption device arranged
upstream the catalyst device 2. The HC adsorption device 3
comprises a honeycomb-shaped base material on which a beta zeolite
or ZMS-5 is carried. The lower the temperature of the device, the
larger an amount of HC that can be adsorbed becomes. Therefore, the
HC adsorption device adsorbs HC in the exhaust gas in low
temperatures and releases the adsorbed HC in high temperatures.
[0021] The catalyst device 2 oxidizes HC and CO in the exhaust gas
to purify them. However, when the oxidation catalyst has not become
an activation temperature, the catalyst device cannot sufficiently
oxidize particular HC and thus it is needed to quickly warm up the
catalyst device immediately after the engine starting-up. The
catalyst device 2 can oxidize CO at a lower temperature than that
at which HC can be oxidized, and thus is warmed up by using of the
oxidation reaction heat of CO at the beginning.
[0022] FIG. 2 is a time-chart showing changes of the oxidation rate
of CO in the catalyst device 2. The solid line shows a case of an
exhaust gas containing about 1600 ppm of propylene C.sub.3H.sub.6
(lower olefin) and CO in which the mixing of propylene is stopped
at a time t0. The dotted line shows a case of an exhaust gas
containing about 1600 ppm of decane C.sub.10H.sub.22 (higher
olefin) and CO in which the mixing of decane is stopped at the time
t0. If HC does not coexist, the oxidation rate of CO increases to
about 100%. However, because propylene or decane coexist, each
oxidation rate of CO becomes lower than 100%. When the mixing of
propylene or decane is stopped, each oxidation rate of CO gradually
increases.
[0023] As shown in FIG. 2, the lower olefin of which carbon atom
number is 5 or under (for example, ethylene or propylene) obstructs
the oxidation of CO in the oxidation catalyst more than the higher
olefin (decane) and thus drops the oxidation rate of CO so
much.
[0024] FIG. 3 is a graph showing a relationship between a
combustion temperature T (maximum combustion temperature) in the
cylinder and a concentration C of lower olefin in the exhaust gas.
The concentration of lower olefin is largest at the combustion
temperature TP (for example, about 1000K). When a combustion
temperature T is this combustion temperature TP or is higher than a
first combustion temperature T1 (for example, about 900K) and lower
than a second combustion temperature T2 (for example, about 1100K),
the concentration of lower olefin becomes relatively high and a
larger amount of lower olefin than that when the combustion
temperature T is the first combustion temperature T1 or under or
the combustion temperature T is the second combustion temperature
T2 or over is exhausted from the cylinder.
[0025] Accordingly, when the temperature of the catalyst device 2
is lower than the activation temperature of the oxidation catalyst
immediately after the engine starting-up, if an operation in which
the combustion temperature is higher than the first combustion
temperature T1 and lower than the second combustion temperature T2
is carried out, a large amount of lower olefin is included in the
exhaust gas. Even if the HC adsorption device 3 is arranged
immediately upstream the catalyst device 2 and a part of the large
amount of lower olefin is adsorbed in the HC adsorption device 3, a
relative large amount of lower olefin obstructs the oxidation of CO
in the oxidation catalyst and thus drops the oxidation rate of CO
so much.
[0026] Therefore, the warming-up of the catalyst device 2 using the
oxidation reaction heat of CO becomes insufficiently and thus the
quick warming-up of the catalyst device cannot be realized. If the
HC adsorption device 3 is not arranged upstream the catalyst
device, when the operation in which the combustion temperature is
higher than the first combustion temperature T1 and lower than the
second combustion temperature T2 is carried out, a large amount of
lower olefin extremely drops the oxidation rate of CO so as to
delay the warming-up of the catalyst device 2 more.
[0027] The control system of the present embodiment controls the
engine according to a first flow-chart shown in FIG. 4 to realize
the quick warming-up of the catalyst device 2. First, at step 101,
it is determined if the temperature (t) (measured or estimated) of
the catalyst device 2 is lower than a set temperature (t') (for
example, the activation temperature of the oxidation catalyst).
When the result at step 101 is negative, the warming-up of the
catalyst device 2 has finished, and therefore at step 102, regular
combustion is carried out.
[0028] On the other hand, when the result at step 101 is positive,
the warming-up of the catalyst device 2 has not finished, and
therefore at step 103, combustion for restraining the production of
lower olefin is carried out. In the combustion for restraining the
production of lower olefin, the combustion temperature T (maximum
combustion temperature) in the cylinder is made the first
combustion temperature T1 or under, or the second combustion
temperature T2 or over.
[0029] For example, when an exhaust valve open timing can be varied
by a variable valve timing mechanism, if the exhaust valve open
timing is advanced to bring forward the combustion finishing time
in an expansion stroke, the combustion temperature can be made the
first combustion temperature T1 or under. On the other hand, if the
exhaust valve open timing is delayed to bring backward the
combustion finishing time in an expansion stroke, the combustion
temperature can be made the second combustion temperature T2 or
over. Further, an addition fuel injection into the cylinder in an
expansion stroke can make the combustion temperature the second
combustion temperature T2 or over.
[0030] When the maximum combustion temperature T is made the second
combustion temperature T2 or over, there is a period in which the
temperature in the cylinder is higher than the first combustion
temperature T1 and is lower than the second combustion temperature
T2. However, this period is very short and may not contribute to
the production of lower olefin.
[0031] Thus, according to the combustion for restraining the
production of lower olefin, an amount of exhausted lower olefin
which extremely drops the oxidation rate of CO in the oxidation
catalyst can be decreased so that the oxidation rate of CO in the
oxidation catalyst is increased so as to realize the quick
warming-up of the catalyst device 2 by the oxidation reaction heat
of CO.
[0032] FIG. 5 is a second flow-chart showing a control of the
engine carried out by the control system of the present embodiment,
to realize the quick warming-up of the catalyst device 2. First, at
step 201, it is determined if the temperature (t) (measured or
estimated) of the catalyst device 2 is lower than the set
temperature (t') (for example, the activation temperature of the
oxidation catalyst). When the result at step 201 is negative, the
warming-up of the catalyst device 2 has been finished and therefore
at step 202, a demanded operation is carried out as it is.
[0033] On the other hand, when the result at step 201 is positive,
at step 203, a current combustion level is determined on the basis
of fuel properties in the fuel tank (for example, cetane number and
a concentration of sulfur), parts deterioration degree (for
example, deterioration degrees of the fuel injector and the
recirculation exhaust gas cooler), and the like. Next, at step 204,
an area A in which an engine operation is prohibited is determined
on the basis of the current combustion level.
[0034] The area A in which an engine operation is prohibited is
shown in FIG. 6, and is an operation area in which the combustion
temperature T (maximum combustion temperature) becomes higher than
the first combustion temperature T1 and lower than the second
combustion temperature T2. The more the combustion level
deteriorates, the higher the engine load in which the combustion
temperature is low becomes. Therefore, the area A in which an
engine operation is prohibited expands to the high engine load
side. Namely, the solid line is the area in which an engine
operation is prohibited when the combustion deterioration level is
low. The dotted line is the area in which an engine operation is
prohibited when the combustion deterioration level is middle. The
chain line is the area in which an engine operation is prohibited
when the combustion deterioration level is high.
[0035] Next, at step 205, it is determined if the current demanded
operation is in the area A in which an engine operation is
prohibited determined at step 204. When the result at step 205 is
negative, at step 206, the demanded operation out of the area A in
which an engine operation is prohibited is carried out as it
is.
[0036] On the other hand, when the result at step 205 is positive,
at step 207, an engine load control is carried out so that the
operation out of the area A in which an engine operation is
prohibited can be carried out at step 206. For example, the engine
load control makes an alternator load increase to increase a
demanded load of the engine. Therefore, the demanded engine
operation can be made out of the area A in which an engine
operation is prohibited.
[0037] Further, for example, when the engine is used in a hybrid
vehicle, the engine load control can make a motor-generator
operates as a generator, can make an amount of power generated by
the motor-generator operating as a generator increase, or can make
a torque generated by the motor-generator operating as a motor
decrease, in order to increase a demanded load of the engine.
Therefore, the demanded engine operation can be made out of the
area A in which an engine operation is prohibited.
[0038] Further, the engine load control can make an amount of power
generated by the motor-generator operating as the generator
decrease, can make the motor-generator operate as the motor, or can
make a torque generated by the motor-generator operating as the
motor increase, in order to decrease a demanded load of the engine.
Therefore, the demanded engine operation can be made out of the
area A in which an engine operation is prohibited.
[0039] Thus, when the warming-up of the catalyst device 2 has not
been finished, an operation exhausting a large amount of lower
olefin is prohibited so that an amount of exhausted lower olefin
which makes the oxidation rate of CO in the oxidation catalyst
extremely decrease can be reduced. Therefore, the oxidation rate of
CO in the oxidation catalyst can be increased to realize the quick
warming-up of the catalyst device 2 by using of the oxidation
reaction heat of CO.
[0040] In the present embodiment, HC adsorption device 3 is
arranged immediately upstream the catalyst device 2 having the
oxidation ability. However, this does not limit the present
invention. Even if the HC adsorption device 3 is omitted, it is
advantageous for the quick warming-up of the catalyst device 2 to
reduce an amount of exhausted lower olefin before finishing the
warming-up of the catalyst device 2.
LIST OF REFERENCE NUMERALS
[0041] 1: exhaust passage
[0042] 2: catalyst device
[0043] 3: HC adsorption device
* * * * *