U.S. patent application number 10/661579 was filed with the patent office on 2004-04-01 for control unit for internal combustion engine.
This patent application is currently assigned to Hitachi, Ltd.. Invention is credited to Nagano, Masami, Nakagawa, Shinji, Ohsuga, Minoru.
Application Number | 20040060285 10/661579 |
Document ID | / |
Family ID | 19048782 |
Filed Date | 2004-04-01 |
United States Patent
Application |
20040060285 |
Kind Code |
A1 |
Nakagawa, Shinji ; et
al. |
April 1, 2004 |
Control unit for internal combustion engine
Abstract
A control unit for an internal combustion engine can activate a
three-way catalyst at the early stage and can lessen the
deterioration of the exhaust in an internal combustion engine such
as HC, CO, and NOx, etc. from the exhaust gas when starting. The
control unit for an internal combustion engine is provided with the
three-way catalyst and HC adsorbent on an exhaust side. The control
unit alternately controls the A/F between a rich state and a lean
state in order to quicken the activation of the three-way catalyst
when the internal combustion engine starts.
Inventors: |
Nakagawa, Shinji;
(Hitachinaka, JP) ; Ohsuga, Minoru; (Hitachinaka,
JP) ; Nagano, Masami; (Hitachinaka, JP) |
Correspondence
Address: |
CROWELL & MORING LLP
INTELLECTUAL PROPERTY GROUP
P.O. BOX 14300
WASHINGTON
DC
20044-4300
US
|
Assignee: |
Hitachi, Ltd.
|
Family ID: |
19048782 |
Appl. No.: |
10/661579 |
Filed: |
September 15, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10661579 |
Sep 15, 2003 |
|
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10193207 |
Jul 12, 2002 |
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6675574 |
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Current U.S.
Class: |
60/284 ;
60/285 |
Current CPC
Class: |
F02D 41/1408 20130101;
Y02T 10/12 20130101; Y02T 10/26 20130101; Y02T 10/22 20130101; F02D
2200/0418 20130101; F02D 41/008 20130101; F02D 41/1454 20130101;
F02D 2200/0802 20130101; F02D 41/1475 20130101; F02D 37/02
20130101; F02D 41/024 20130101 |
Class at
Publication: |
060/284 ;
060/285 |
International
Class: |
F01N 003/10 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 13, 2001 |
JP |
2001-213873 |
Claims
What is claimed is:
1. A control unit for an internal combustion engine including the
three way catalyst and HC adsorbent on an exhaust side, wherein
said control unit alternately controls the A/F between a rich state
and a lean state in order to quicken the activation of said three
way catalyst when said internal combustion engine starts.
2. A control unit for an internal combustion engine including the
three way catalyst on an exhaust side, wherein control unit has a
means for detecting completion of the evaporation of moisture in
said three way catalyst directly or indirectly, and wherein control
unit alternately controls the A/F between a rich state and a lean
state in order to quicken the activation of said three way catalyst
after the completion of the evaporation of moisture in said three
way catalyst is detected.
3. The control unit for an internal combustion engine according to
claim 2, wherein the ignition time is retarded for the period until
moisture in said three way catalyst evaporates directly after the
start of said internal combustion engine.
4. A control unit for an internal combustion engine including the
three way catalyst on an exhaust side, wherein control unit has a
means for detecting the temperature of said three way catalyst
directly or indirectly, and wherein control unit alternately
controls the A/F between a rich state and a lean state in order to
quicken the activation of the three way catalyst when the
temperature of said three way catalyst is a value within the fixed
range.
5. A control unit for an internal combustion engine including the
three way catalyst on an exhaust side, wherein control unit has a
means for detecting the operating state of the internal combustion
engine, and wherein control unit alternately controls the A/F
between a rich state and a lean state in order to quicken the
activation of the three way catalyst based on the operating
state.
6. A control unit for an internal combustion engine including the
three way catalyst and HC adsorbent on an exhaust side in the
order, wherein control unit has a means for detecting the
temperature of said HC adsorbent directly or indirectly, and
wherein control unit alternately controls the A/F between a rich
state and a lean state in order to change the temperature of said
HC adsorbent.
7. The control unit for an internal combustion engine according to
claim 6, wherein control unit alternately controls the A/F between
a rich state and a lean state when the temperature of said HC
adsorbent is within the fixed range.
8. A control unit for an internal combustion engine including a
catalyst which has the three way catalyst and HC adsorbent in the
same carrier on an exhaust side, wherein control unit alternately
controls the A/F between a rich state and a lean state in order to
change the temperature of said HC adsorbent.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to a control unit for an
internal combustion engine, especially to a control unit for an
internal combustion engine to activate quickly the three way
catalyst when the internal combustion engine starts, and to do
efficiently the adsorption and the purification of HC.
[0002] The demand of the work on the energy saving in the world
scale and the environmental protection keeps strengthening more and
more in the environment which surrounds the car in recent years,
and the fuel cost restriction and the Emission Control, etc. have
been reinforced.
[0003] In general, three way catalyst having the function of
oxidizing HC and CO in the exhaust gas exhausted to the exhaust
pipe by the internal combustion engine and reducing NOx to clear
said Emission Control has been installed in the automobile engine.
Although said three way catalyst can purify HC, CO, and NOx in
exhaust gas at a temperature more than a fixed one, it cannot
usually purify enough HC, CO, and NOx at a temperature below a
fixed temperature.
[0004] In general, an internal combustion engine is at low
temperature when starting. Because the purification performance of
exhaust gas is remarkably low for the period to becoming of the
three way catalyst more than a fixed temperature as shown in FIG. 7
(FIG. 7 shows an example of HC), it is important to activate the
three way catalyst at the early stage when starting to decrease HC,
CO, and Nox in exhaust gas. Therefore, a lot of the techniques have
been proposed so far.
[0005] In the technology and according to the Japanese Patent
Application Laid-Open No. 5-33705, by alternately supplying the
rich exhaust and the lean exhaust to said three way catalyst; CO
and HC including in the rich exhaust and O2 in the lean exhaust are
made to react with each other, and the catalyst is warmed up with
the heat of reaction.
[0006] Though in said technology CO and HC including in the rich
exhaust and O2 in the lean exhaust are made to burn by alternately
supplying the rich exhaust and the lean exhaust to said three way
catalyst, All necessarily exhausted HC and CO does not burn, and
are exhausted outside through the catalyst. Therefore, there is a
problem that HC and CO is not improved though the object of warming
up the catalyst can be achieved. Especially, HC deterioration when
starting becomes a big problem by the restriction reinforcement of
the exhaust gas in recent years.
SUMMARY OF THE INVENTION
[0007] The present invention was performed considering said
problems. An object of the present invention is to provide a
control unit for an internal combustion engine in which the three
way catalyst is activated at the early stage when the internal
combustion engine starts, and the deterioration of components such
as HC, CO, and NOx in exhaust gas from an internal combustion
engine is reduced.
[0008] A control unit for an internal combustion engine including
the three way catalyst and HC adsorbent on an exhaust side, wherein
said control unit alternately controls the A/F between a rich state
and a lean state in order to quicken the activation of said three
way catalyst when said internal combustion engine starts (FIG.
1).
[0009] The control unit for an internal combustion engine of the
present invention configured like the above-mentioned can raise the
temperature of the three way catalyst by alternately supplying rich
exhaust and lean exhaust to the three way catalyst, and by the heat
of reaction of CO, HC in the rich exhaust and O2 in the lean
exhaust. In addition, by installing HC adsorbent in the downstream
of the three way catalyst and by supplying the rich exhaust and the
lean exhaust, the three way catalyst can be activated at the early
stage without deteriorating the exhaust gas by adsorbing HC emitted
from the downstream of the three way catalyst by using HC
adsorbent.
[0010] Moreover, a control unit for an internal combustion engine
according to another embodiment of the present invention is
characterized by a control unit for an internal combustion engine
including the three way catalyst on an exhaust side, wherein
control unit has a means for detecting completion of the
evaporation of moisture in said three way catalyst directly or
indirectly, and wherein control unit alternately controls the A/F
between a rich state and a lean state in order to quicken the
activation of said three way catalyst after the completion of the
evaporation of moisture in said three way catalyst is detected (see
FIG. 2). Further, the ignition time is retarded for the period
until moisture in said three way catalyst evaporates directly after
the start of said internal combustion engine.
[0011] In the control unit for an internal combustion engine of the
present invention configured like the above-mentioned, the reason
for the supply of rich/lean exhaust to the three way catalyst is
that the temperature of precious metals in the three way catalyst
are raised. If the precious metals have been partially activated,
the reaction proceeds further in that part, and the activation of
precious metals in the catalyst is advanced continuously by the
heat of reaction. The three way catalyst can be activated at the
early stage without deteriorating the exhaust by supplying
rich/lean exhaust after water in the three way catalyst evaporates,
because the heat of reaction can be efficiently supplied to
precious metals if there is no moisture in the three way catalyst.
Moreover, the exhaust temperature is raised by making the ignition
time retarded directly after the start, moisture in the catalyst
evaporates promptly, and the supply of rich/lean exhaust is
controlled at the early stage, because the activation time is
shortened by time for water to evaporate short.
[0012] Further, a control unit for an internal combustion engine
according to a further embodiment of the present invention is
characterized by a control unit for an internal combustion engine
including the three way catalyst on an exhaust side, wherein
control unit has a means for detecting the temperature of said
three way catalyst directly or indirectly, and wherein control unit
alternately controls the A/F between a rich state and a lean state
in order to quicken the activation of the three way catalyst when
the temperature of said three way catalyst is a value within the
fixed range (FIG. 3).
[0013] The control unit for an internal combustion engine of the
present invention configured like the above-mentioned can estimate
the evaporation of the moisture in the catalyst by directly or
indirectly detecting the temperature of the catalyst, and control
the supply rich/lean exhaust with a high degree of accuracy by
setting the temperature of the catalyst to the value within the
fixed range.
[0014] Further, a control unit for an internal combustion engine
according to a further embodiment of the present invention is
characterized by a control unit for an internal combustion engine
including the three way catalyst on an exhaust side, wherein
control unit has a means for detecting the operating state of the
internal combustion engine, and wherein control unit alternately
controls the A/F between a rich state and a lean state in order to
quicken the activation of the three way catalyst based on the
operating state (FIG. 4).
[0015] The control unit for an internal combustion engine of the
present invention configured like the above-mentioned can control
the supply rich/lean exhaust with a higher degree of accuracy by
estimating the temperature of the catalyst and estimating the
evaporation of the moisture in the catalyst based on the operating
state of the internal combustion engine, for instance, the time
after the engine starts, the water temperature, total air flow rate
after the engine starts and so on.
[0016] Further, the control unit for an internal combustion engine
according to a further embodiment of the present invention is
characterized by a control unit for an internal combustion engine
including the three way catalyst and HC adsorbent on an exhaust
side in the order, wherein control unit has a means for detecting
the temperature of said HC adsorbent directly or indirectly, and
wherein control unit alternately controls the A/F between a rich
state and a lean state in order to change the temperature of said
HC adsorbent. The control unit alternately controls the A/F between
a rich state and a lean state when the temperature of said HC
adsorbent is within the fixed range (FIG. 5).
[0017] In the control unit for an internal combustion engine of the
present invention configured like the above-mentioned, the HC
adsorbent has the characteristic that HC is adsorbed at a
temperature below a fixed one, and is desorbed at a temperature
more than a fixed one because the HC adsorbent loses the adsorbent
characteristic. In general, HC desorption temperature is lower than
the activating temperature of the three way catalyst, the
difference between these temperatures is large, and there is a
temperature raise characteristic in which each phase of HC
adsorbent, desorption, and purification becomes the best. And, the
temperature of said three way catalyst is adjusted by controlling
the supply of rich/lean exhaust appropriately with paying attention
to the above-mentioned. As a result, it is possible to control so
that the temperature raise characteristic of the HC adsorbent may
become the best.
[0018] Further, a control unit for an internal combustion engine
according to a further embodiment of the present invention is
characterized by a control unit for an internal combustion engine
including a catalyst which has the three way catalyst and HC
adsorbent in the same carrier on an exhaust side, wherein control
unit alternately controls the A/F between a rich state and a lean
state in order to change the temperature of said HC adsorbent (FIG.
6).
[0019] In the control unit for an internal combustion engine of the
present invention configured like the above-mentioned, the
temperature of the three way catalyst is raised by the heat of
reaction of O2 in the lean exhaust and CO, HC in the rich exhaust
by alternately supplying the rich exhaust and the lean exhaust to
the catalyst supported by the same carrier. In addition, HC
separated from the three way catalyst is adsorbed by the HC
adsorbent by supplying the rich exhaust and the lean exhaust. As a
result, the exhaust gas is not deteriorated, and the three way
catalyst is activated at the early stage. However, it is preferable
that the temperature in the downstream of the catalyst is set such
that the evaporation of the moisture in the three way catalyst is
not completed but the adsorbed HC in HC adsorption catalyst begins
to separate. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] The present invention will be understood more fully from the
detailed description given hereinafter and from the accompanying
drawings of the preferred embodiment of the present invention,
which, however, should not be taken to be limitative to the
invention, but are for explanation and understanding only In the
drawings:
[0021] FIG. 1 shows a control unit for an internal combustion
engine according to claim 1.
[0022] FIG. 2 shows a control unit for an internal combustion
engine according to claim 2.
[0023] FIG. 3 shows a control unit for an internal combustion
engine according to claim 4.
[0024] FIG. 4 shows a control unit for an internal combustion
engine according to claim 5.
[0025] FIG. 5 shows a control unit for an internal combustion
engine according to claim 6.
[0026] FIG. 6 shows a control unit for an internal combustion
engine according to claim 8.
[0027] FIG. 7 shows the temperature of three way catalyst under
running of a vehicle and a HC emission characteristic after three
way catalyst.
[0028] FIG. 8 shows the whole internal combustion engine system
according to a first embodiment of the control unit for an internal
combustion engine of the present invention.
[0029] FIG. 9 shows the internal construction of a control unit for
the internal combustion engine shown in FIG. 8.
[0030] FIG. 10 shows a control unit for an internal combustion
engine shown in FIG. 9.
[0031] FIG. 11 shows a basic fuel calculation unit in the control
block diagram of FIG. 10.
[0032] FIG. 12 shows an A/F correction term calculation unit in the
control block diagram of FIG. 10.
[0033] FIG. 13 shows a rich/lean control permission judgement unit
in the control block diagram of FIG. 10.
[0034] FIG. 14 shows a #1 cylinder A/F calculation unit in the
control block diagram of FIG. 10.
[0035] FIG. 15 shows a #2 cylinder A/F calculation unit in the
control block diagram of FIG. 10.
[0036] FIG. 16 shows a #3 cylinder A/F calculation unit in the
control block diagram of FIG. 10.
[0037] FIG. 17 shows a #4 cylinder A/F calculation unit in the
control block diagram of FIG. 10.
[0038] FIG. 18 shows the whole internal combustion engine system
according to a second embodiment of the control unit for an
internal combustion engine of the present invention.
[0039] FIG. 19 shows the internal construction of a control unit
for the internal combustion engine shown in FIG. 18.
[0040] FIG. 20 shows a rich/lean control permission judgement unit
in the control unit for an internal combustion engine of FIG.
18.
[0041] FIG. 21 shows the whole internal combustion engine system
according to a third embodiment of the control unit for an internal
combustion engine of the present invention.
[0042] FIG. 22 shows the internal construction of a control unit
for the internal combustion engine shown in FIG. 21.
[0043] FIG. 23 shows a control unit for an internal combustion
engine shown in FIG. 21.
[0044] FIG. 24 shows a rich/lean control permission judgement unit
in the control block diagram of FIG. 23.
[0045] FIG. 25 shows the whole internal combustion engine system
according to a fourth embodiment of the control unit for an
internal combustion engine of the present invention.
[0046] FIG. 26 shows a fifth embodiment of the control unit for an
internal combustion engine of the present invention.
[0047] FIG. 27 shows an ignition time calculation unit in the
control block diagram of FIG. 26.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0048] The present invention will be discussed hereinafter in
detail in terms of the preferred embodiment according to the
present invention with reference to the accompanying drawings. In
the following description, numerous specific details are set forth
in order to provide a thorough understanding of the present
invention. It will be obvious, however, to those skilled in the art
that the present invention may be practiced without these specific
details. In other instance, well-known structures are not shown in
detail in order to avoid unnecessary obscurity of the present
invention.
[0049] Some embodiments of a control unit for an internal
combustion engine of the present invention are explained in detail
hereafter referring to the drawing.
[0050] [First Embodiment]
[0051] FIG. 8 shows the whole internal combustion engine system
according to a first embodiment of the control unit for an internal
combustion engine of the present invention.
[0052] Internal combustion engine 1 is configured of the internal
combustion engine of the multi-cylinder type. In an air intake
system, air from the outside passes air cleaner 19, flows into
combustion chamber 9a in cylinder 9 through intake manifold 6.
Although an amount of the inflow air is chiefly adjusted with
throttle 3, the air amount is adjusted with ISC valve 5 installed
in air passage 4 for the by-pass at idling, and the engine speed of
the internal combustion engine is controlled. Fuel injection valve
7 for each cylinder is installed in intake manifold 6. Sparking
plug 8 is installed in cylinder 9 of each cylinder, and intake
valve 29 and exhaust valve 30 are also arranged therein.
[0053] Moreover, in an exhaust system, exhaust manifold 10 is
connected to cylinder 9 of each cylinder, and three way catalyst 11
and HC adsorption catalyst 18 are arranged in the exhaust manifold
10 in the order. Air flow sensor 2 is arranged in intake manifold 6
of the air intake system, which detects an amount of the intake
air. Crank angle sensor 15 outputs a signal every one degree of the
rotation angle of the crankshaft. In throttle opening sensor 17
installed in electronic throttle 3, the opening of electronic
throttle 3 is detected, and in water temperature sensor 14, the
temperature of the cooling water for the internal combustion engine
is detected.
[0054] Each signal from air flow sensor 2, opening sensor 17
installed in throttle 3, crank angle sensor 15, and water
temperature sensor 14 is sent to control unit 16. The operating
state of internal combustion engine 1 is obtained from these sensor
outputs, and the main manipulated variable of the ignition time and
the basic injection amount of the fuel are calculated
appropriately. Fuel injection amount calculated in control unit 16
is converted into a valve-open pulse signal and is sent to fuel
injection valve 7 installed in the intake pipe of each cylinder.
Therefore, fuel injection amount can be controlled every
cylinder.
[0055] Moreover, the predetermined ignition time is calculated in
control unit 16, and a driving signal is sent to sparking plug 8 so
that it can be ignited at its ignition time. The fuel injected from
fuel injection valve 7 flows into combustion chamber 9a of internal
combustion engine 1, and forms the air-fuel mixture by being mixed
with the air from intake manifold 6. The air-fuel mixture is
exploded by the spark generated by sparking plug 8, and the energy
generated at that time becomes the power source for internal
combustion engine 1.
[0056] The exhaust gas after explosion is sent to three way
catalyst 11 through exhaust manifold 10 to purify HC, CO, and Nox.
HC adsorption catalyst 18 has the three way characteristic inside,
that is, the function of purifying the desorbed HC.
[0057] A/F sensor 12 is installed between cylinder 9 of internal
combustion engine 1 and three way catalyst 11, which has a linear
output characteristic with respect to the oxygen concentration
included in the exhaust gas. Because the relationship between the
oxygen concentration included in the exhaust gas and the A/F is
approximately linear, it is possible to detect the A/F by A/F
sensor 12 which detects the oxygen concentration. Moreover,
temperature sensor 13 is installed in the downstream of three way
catalyst 11. Therefore, the detection of the temperature in the
downstream of three way catalyst 11 is enabled.
[0058] In control unit 16, the A/F in the upstream of three way
catalyst 11 is calculated from a signal of A/F sensor 12, and the
amount of the fuel supplied to internal combustion engine 1 is
controlled to become an A/F whose purification efficiency is the
highest in three way catalyst 11.
[0059] FIG. 9 shows the inside of the control unit (ECU) 16 shown
in FIG. 8. The output value of each sensor of air flow sensor 2,
A/F sensor 12, temperature sensor 13, water temperature sensor 14,
internal combustion engine revolution speed sensor 15, and throttle
valve opening sensor 17 is input in ECU 16, and after the signal
processing such as noise rejection etc. is carried out in input
circuit 23, the signal is sent to I/O port 24. The value of I/O
port 24 is kept in RAM 22, and the operation processing is carried
out in CPU 20. Control program which describes the content of the
operation processing is written in ROM 21 beforehand. The value
which indicates the amount of each actuator operation calculated
according to control program is kept in RAM 22. Then, it is sent to
I/O port 24. An ON/OFF signal is set as an operation signal of
sparking plug 8, in which it is turned on at a conduction state of
the primary coil in ignition output circuit 25, and it is turned
off at a non-conduction state of the primary coil. The ignition
time is when the operation signal becomes turning-off from
turning-on. The signal for the sparking plug set in I/O port 24 is
amplified into enough energy necessary for combustion in ignition
output circuit 25 and supplied to sparking plug 8. An ON/OFF signal
is set as a driving signal of fuel injection valve 7, in which the
ON/OFF signal is turned on at valve-open and turned off at
valve-close. The driving signal is amplified into energy enough to
open fuel injection valve 7 in fuel injection valve drive circuit
26, and sent to fuel injection valve 7.
[0060] FIG. 10 is a control block diagram showing the entire
control of control unit 16 according to the embodiment shown in
FIG. 9. The control unit 16 comprises basic fuel injection amount
calculation unit 31, A/F correction term calculation unit 32, #1
cylinder A/F correction amount calculation unit 33a, #2 cylinder
A/F correction amount calculation unit 33b, #3 cylinder A/F
correction amount calculation unit 33c, #4 cylinder A/F correction
amount calculation unit 33d, and rich/lean control permission
judgement part 34.
[0061] When the rich/lean control is not permitted, the fuel
injection amount for each cylinder is calculated so that the A/F
for all cylinders may become the theoretical air-fuel ratio. When
rich/lean control is permitted, the A/F for each cylinder is
changed in the specified amount in order to activate three way
catalyst 11 at the early stage by supplying the rich exhaust and
the lean exhaust to the entrance of three way catalyst 11.
Hereinafter, each calculation unit of said control unit 16 will be
explained in detail.
[0062] 1. Basic Fuel Injection Amount Calculation Unit 31.
[0063] FIG. 11 shows basic fuel injection amount calculation unit
31. The basic fuel injection amount calculation unit 31 calculates
the fuel injection amount to achieve the target torque and the
target A/F at the same time in an arbitrary operating condition
based on an amount of the inflow air into internal combustion
engine 1. Concretely, basic fuel injection amount Tp is calculated
as shown in FIG. 11. Here, K is a constant, which always make A/F
adjust the theoretical A/F for the amount of the inflow air.
Further, Cyl indicates the number of cylinders of internal
combustion engines 1, and the number of cylinders is 4 in this
embodiment.
[0064] 2. A/F Correction Term Calculation Unit 32.
[0065] FIG. 12 shows A/F correction term calculation unit 32. Here,
A/F correction term calculation unit 32 feedback-controls A/F based
on the A/F detected by A/F sensor 12 so that the A/F of internal
combustion engine 1 may take the theoretical A/F in an arbitrary
operating condition. Concretely, A/F correction term Lalpha is
calculated from deviation Dltabf between the target A/F Tabf and
the A/F Rabf detected by A/F sensor by using the PID control as
shown in FIG. 12. A/F correction term Lalpha is multiplied by
above-mentioned basic fuel injection amount Tp in order to always
keep A/F of internal combustion engine 1 to the theoretical
A/F.
[0066] 3. Rich/Lean Control Permission Judgement Part 34.
[0067] FIG. 13 shows rich/lean control permission judgement part
34. The rich/lean control permission judgement part 34 performs the
permission judgment of the rich/lean control. Concretely, it makes
the rich/lean control permission flag to FpRL=1 and permits the
rich/lean control if Ten.gtoreq.TenL, Ten.ltoreq.TenH, and
Ne.ltoreq.NeRLp, as shown in FIG. 13. Otherwise, Rich/lean control
is prohibited, and FpRL=0 is set.
[0068] Where, Ten: downstream temperature of the three way
catalyst, and Ne: engine speed of the internal combustion
engine.
[0069] It is preferable to set TenL to the temperature at which the
evaporation of moisture in the three way catalyst is completed. The
temperature becomes generally 50.degree. C.-100.degree. C., which
depends on the location of the sensor, etc. it is preferable to set
TenH to the activation temperature of the three way catalyst. The
temperature becomes 250.degree. C.-400.degree. C., which depends on
the catalyst performance. You should decide both values of TenL and
TenH according to the performance of the real machine performance.
Further, although it is assumed the method to detect the exhaust
gas temperature in the downstream of the catalyst in this
embodiment, various methods of estimating from other operating
condition of the internal combustion engine without measuring the
temperature directly are proposed. Therefore, it is also possible
to use them.
[0070] 4. #1 Cylinder A/F Correction Amount Calculation Unit
33a.
[0071] FIG. 14 shows the #1 cylinder A/F correction amount
calculation unit 33a. In the #1 cylinder A/F correction amount
calculation unit 33a, the amount of the A/F correction in the first
cylinder is calculated. The #1 cylinder A/F correction amount Chos1
is set to 0 at rich/lean control permission flag FpRL=0, and fuel
injection amount for each cylinder is calculated to obtain the
theoretical A/F from the above-mentioned basic fuel injection
amount Tp and A/F correction term Lalpha. The A/F of the first
cylinder is changed in specified amount Kehos1 to supply the
rich/lean exhaust to the entrance of three way catalyst 11 at
rich/lean control permission flag FpRL=1. Concretely, the
processing shown in FIG. 14 is carried out. That is, it is assumed
change amount Chos1=Kehos1 in the equivalence ratio of the #1
cylinder at rich/lean control permission flag FpRL=1, and assumed
Chos1=0 at FpRL=0. It is desirable to set the value of Kehos1 from
the performance of the degree of the temperature-rise of the three
way catalyst and the exhaust according to the characteristic of
internal combustion engine 1 and three way catalyst 11.
[0072] 5. #2 Cylinder A/F Correction Amount Calculation Unit
33b.
[0073] FIG. 15 shows the #2 cylinder A/F correction amount
calculation unit 33b. In the #2 cylinder A/F correction amount
calculation unit 33b, the amount of the A/F correction in the
second cylinder is calculated. The #1 cylinder A/F correction
amount Chos2 is set to 0 at rich/lean control permission flag
FpRL=0, and fuel injection amount for each cylinder is calculated
to obtain the theoretical A/F from the above-mentioned basic fuel
injection amount Tp and A/F correction term Lalpha. The A/F of the
first cylinder is changed in specified amount Kehos2 to supply the
rich/lean exhaust to the entrance of three way catalyst 11 at
rich/lean control permission flag FpRL=1. Concretely, the
processing shown in FIG. 15 is carried out. That is, it is assumed
change amount Chos2=Kehos2 in the equivalence ratio of the #2
cylinder at rich/lean control permission flag FpRL=1, and assumed
Chos2=0 at FpRL=0. It is desirable to set the value of Kehos2 from
the performance of the degree of the temperature-rise of the three
way catalyst and the exhaust according to the characteristic of
internal combustion engine 1 and three way catalyst 11.
[0074] 6. #3 Cylinder A/F Correction Amount Calculation Unit
33c.
[0075] FIG. 16 shows the #3 cylinder A/F correction amount
calculation unit 33c. In the #3 cylinder A/F correction amount
calculation unit 33c, the amount of the A/F correction in the third
cylinder is calculated. The #3 cylinder A/F correction amount Chos3
is set to 0 at rich/lean control permission flag FpRL=0, and fuel
injection amount for each cylinder is calculated to obtain the
theoretical A/F from the above-mentioned basic fuel injection
amount Tp and A/F correction term Lalpha. The A/F of the third
cylinder is changed in specified amount Kehos3 to supply the
rich/lean exhaust to the entrance of three way catalyst 11 at
rich/lean control permission flag FpRL=1. Concretely, the
processing shown in FIG. 16 is carried out. That is, it is assumed
change amount Chos3=Kehos3 in the equivalence ratio of the #3
cylinder at rich/lean control permission flag FpRL=1, and assumed
Chos3=0 at FpRL=0. It is desirable to set the value of Kehos1 from
the performance of the degree of the temperature-rise of the three
way catalyst and the exhaust according to the characteristic of
internal combustion engine 1 and three way catalyst 11.
[0076] 7. #4 Cylinder A/F Correction Amount Calculation Unit
33d.
[0077] FIG. 17 shows the #4 cylinder A/F correction amount
calculation unit 33d. In the #4 cylinder A/F correction amount
calculation unit 33d, the amount of the A/F correction in the forth
cylinder is calculated. The #4 cylinder A/F correction amount Chos4
is set to 0 at rich/lean control permission flag FpRL=0, and fuel
injection amount for each cylinder is calculated to obtain the
theoretical A/F from the above-mentioned basic fuel injection
amount Tp and A/F correction term Lalpha. The A/F of the forth
cylinder is changed in specified amount Kehos4 to supply the
rich/lean exhaust to the entrance of three way catalyst 11 at
rich/lean control permission flag FpRL=1. Concretely, the
processing shown in FIG. 14 is carried out. That is, it is assumed
change amount Chos4=Kehos4 in the equivalence ratio of the #4
cylinder at rich/lean control permission flag FpRL=1, and assumed
Chos4=0 at FpRL=0. It is desirable to set the value of Kehos1 from
the performance of the degree of the temperature-rise of the three
way catalyst and the exhaust according to the characteristic of
internal combustion engine 1 and three way catalyst 11.
[0078] [Second Embodiment]
[0079] FIG. 18 shows the entire system of the internal combustion
engine according to the second embodiment of a control unit for an
internal combustion engine of the present invention. Because the
second embodiment is the same as the first embodiment, excluding
temperature sensor 13 not being provided, the explanation on other
configuration is omitted.
[0080] FIG. 19 shows an internal configuration of control unit 16.
Because its configuration is the same as one of the first
embodiment, excluding the input terminal of temperature sensor 13
not being provided, the explanation on other configuration is
omitted. A control block diagram showing the entire control of
control unit 16 according to this embodiment of FIG. 19 is the same
as one of the first embodiment of FIG. 10, excluding the input
signal of rich/lean control permission judgement part 34 is
different. The control block diagram is not shown in figure and
FIG. 10 is referred instead.
[0081] Control unit 16 of this embodiment comprises basic fuel
injection amount calculation unit 31, A/F correction term
calculation unit 32, #1 cylinder A/F correction amount calculation
unit 33a, #2 cylinder A/F correction amount calculation unit 33b,
#3 cylinder A/F correction amount calculation unit 33c, #4 cylinder
A/F correction amount calculation unit 33d, and rich/lean control
permission judgement part 34. When the rich/lean control is not
permitted, control unit 16 calculates fuel injection amount for
each cylinder so that the A/F for all cylinders may become the
theoretical A/F. When the rich/lean control is permitted, the rich
exhaust and the lean exhaust are supplied to the entrance of three
way catalyst 11, the A/F for each cylinder is changed in the
specified amount in order to activate the three way catalyst 11 at
the early stage. Hereafter, each calculation unit of control unit
16 will be explained in detail.
[0082] 1. Basic Fuel Injection Amount Calculation Unit 31 and 2.
A/F Correction Term Calculation Unit 32.
[0083] Because basic fuel injection amount calculation unit 31 and
A/F correction term calculation unit 32 are the same as the first
embodiment (FIG. 11 and FIG. 12), the explanation is omitted.
[0084] 3. Rich/Lean Control Permission Judgement Part 34
[0085] FIG. 20 shows rich/lean control permission judgement part
34. In the rich/lean control permission judgement part 34, the
permission judgment of rich/lean control is carried out.
Concretely, it makes the rich/lean control permission flag to
FpRL=1 and permits the rich/lean control if water temperature at
start.ltoreq.KTws, inflow air amount integrated value.ltoreq.Qasum,
time TaftL after start or more, time TaftH after start or less, and
Ne.ltoreq.NeRL, as shown in FIG. 13. Otherwise, Rich/lean control
is prohibited, and FpRL=0 is set. Where, Ne: engine speed of the
internal combustion engine.
[0086] it is preferable to perform the rich/lean control to the
activation of three way catalyst 11 after the moisture in three way
catalyst 11 evaporates as shown by the first embodiment. Said each
parameter should be determined to suit the above condition.
[0087] 4. #1 cylinder A/F correction amount calculation unit 33a;
5. #2 cylinder A/F correction amount calculation unit 33b; 6. #3
cylinder A/F correction amount calculation unit 33c; and 7. #4
cylinder A/F correction amount calculation unit 33d. Because the #1
to #4 cylinder A/F correction amount calculation units 33a, 33b,
33c, and 33d are the same as the first embodiment (FIG. 14-FIG.
17), the explanation is omitted.
[0088] [Third Embodiment]
[0089] FIG. 21 shows the entire system of the internal combustion
engine according to the third embodiment of a control unit for an
internal combustion engine of the present invention. Because the
third embodiment is same as the first embodiment, excluding
temperature sensor 27 being installed in the downstream of HC
adsorption catalyst 18, the explanation on other configuration is
omitted.
[0090] FIG. 22 shows an internal configuration of control unit 16.
Because its configuration is the same as one of the first
embodiment, excluding the input terminal of temperature sensor 13
being added, the explanation on other configuration is omitted.
[0091] FIG. 23 is a control block diagram showing the entire
control of control unit 16 according to this embodiment shown in
FIG. 22. Control unit 16 of this embodiment comprises basic fuel
injection amount calculation unit 31, A/F correction term
calculation unit 32, #1 cylinder A/F correction amount calculation
unit 33a, #2 cylinder A/F correction amount calculation unit 33b,
#3 cylinder A/F correction amount calculation unit 33c, #4 cylinder
A/F correction amount calculation unit 33d, and rich/lean control
permission judgement part 34.
[0092] When the rich/lean control is not permitted, control unit 16
calculates fuel injection amount for each cylinder so that the A/F
for all cylinders may become the theoretical A/F. When the
rich/lean control is permitted, the rich exhaust and the lean
exhaust are supplied to the entrance of three way catalyst 11, in
order to activate the three way catalyst 11 at the early stage or
optimize the temperature-rise characteristic of HC adsorption
catalyst 18. Hereafter, each calculation unit of control unit 16
will be explained in detail.
[0093] 1. Basic Fuel Injection Amount Calculation Unit 31 and 2.
A/F Correction Term Calculation Unit 32.
[0094] Because basic fuel injection amount calculation unit 31 and
A/F correction term calculation unit 32 are the same as the first
embodiment (FIG. 11 and FIG. 12), the explanation is omitted.
[0095] 3. Rich/Lean Control Permission Judgement Part 34
[0096] FIG. 24 shows rich/lean control permission judgement part
34. In the rich/lean control permission judgement part 34, the
permission judgment of rich/lean control is carried out. The
rich/lean control has two purposes, the temperature-rise of three
way catalyst 11 and that of HC adsorption catalyst 18. Further, the
permission condition is also divided into the temperature-rise
control of the three way catalyst and that of HC adsorption
catalyst roughly.
[0097] Concretely, it makes three way catalyst temperature-rise
control permission flag to FpCAT=1 if Ten.gtoreq.TenL,
Ten.ltoreq.TenH, and Ne.ltoreq.Nc RL. Otherwise, FpCAT=0. Where,
Ten: three way catalyst downstream temperature and Ne: engine speed
of the internal combustion engine. Further, it makes three way
catalyst temperature-rise control permission flag to FpHC=1 if
Ten2.gtoreq.Ten2L and Ten2.ltoreq.Ten2H, Otherwise, FpHC=0. Where,
Ten: HC adsorption catalyst downstream temperature. It is
preferable to set TenL to the temperature at which the evaporation
of moisture in the three way catalyst is completed. The temperature
becomes generally 50.degree. C.-100.degree. C., which depends on
the location of the sensor, etc.
[0098] It is preferable to set TenH to the activation temperature
of the three way catalyst. The temperature becomes 250.degree.
C.-400.degree. C., which depends on the catalyst performance. It is
preferable to set Ten2L to the temperature at which the adsorbed HC
of the HC adsorption catalyst starts to be desorbed. The
temperature becomes generally 100.degree. C.-200.degree. C., which
depends on the location of the sensor, etc. Further, it is
preferable to set Ten2H to the activation temperature of the three
way catalyst in the HC adsorption catalyst 18. The temperature
becomes 250.degree. C.-400.degree. C., which depends on the
catalyst performance. You should decide the values of TenL, TenH,
Ten2L and Ten2H according to the performance of the real machine
performance.
[0099] 4. #1 cylinder A/F correction amount calculation unit 33a;
5. #2 cylinder A/F correction amount calculation unit 33b; 6. #3
cylinder A/F correction amount calculation unit 33c; and 7. #4
cylinder A/F correction amount calculation unit 33d. Because the #1
to #4 cylinder A/F correction amount calculation units 33a, 33b,
33c, and 33d are the same as the first embodiment (FIG. 14-FIG.
17), the explanation is omitted.
[0100] Although it is assumed the specification which raises
temperature up to the temperature to which three way performance in
HC adsorption catalyst 18 are activated at the quickest velocity
when the adsorbed HC in HC adsorption catalyst 18 starts to desorb
in this embodiment, actually, it is also good to control in
feedback based on the output of temperature sensor 27 according to
the best temperature-rise curve. In this case, the temperature of
HC adsorption catalyst 18 is adjusted by repeating an ON/OFF state
of rich/lean control.
[0101] [Fourth Embodiment]
[0102] FIG. 25 shows the entire system of the internal combustion
engine according to the fourth embodiment of a control unit for an
internal combustion engine of the present invention. Catalyst 28 is
a catalyst in which the HC adsorbent and the three way catalyst are
supported by the same carrier. Because the configuration except the
catalyst 28 is the same as the first embodiment, the explanation of
other configuration is omitted.
[0103] The Control in the control unit for an internal combustion
engine according to this embodiment is the same as that in the
first embodiment. However, it is preferable to set a set
temperature TenH in the downstream of the catalyst not to the
temperature at which the evaporation of moisture in the three way
catalyst is completed, but to the temperature at which the adsorbed
HC of the HC adsorption catalyst starts to be desorbed. The
temperature becomes generally 100.degree. C.-200.degree. C., which
depends on the location of the sensor, etc. Actually, as described
in the first embodiment, it is also good to control in feedback
based on the output of temperature sensor 13 according to the best
temperature-rise curve. In this case, the temperature of HC
adsorption catalyst is adjusted by repeating an ON/OFF state of
rich/lean control.
[0104] [Fifth Embodiment]
[0105] FIG. 26 is a control block diagram showing the entire
control of control unit 16 according to the fifth embodiment of the
present invention. The control unit 16 comprises basic fuel
injection amount calculation unit 31, A/F correction term
calculation unit 32, #1 cylinder A/F correction amount calculation
unit 33a, #2 cylinder A/F correction amount calculation unit 33b,
#3 cylinder A/F correction amount calculation unit 33c, #4 cylinder
A/F correction amount calculation unit 33d, rich/lean control
permission judgement part 34 and ignition time calculation unit 35.
Because control unit 16 is the same as the first embodiment
excluding ignition time calculation unit 35 being provided, the
explanation is omitted.
[0106] Control unit 16 of the internal combustion engine according
to this embodiment has the purposes, to evaporate the moisture in
three way catalyst 11 at the early stage and to heighten an effect
of the rich/lean control. The retard is put at the ignition time
when internal combustion engine 1 is started. Moreover, when the
rich/lean control is not permitted, a fuel injection amount of each
cylinder is calculated so that the A/F of all cylinders may become
the theoretical A/F. When the rich/lean control is permitted, the
A/F of each cylinder is changed in the specified amount to activate
three way catalyst 11 at the early stage by supplying the rich
exhaust and the lean exhaust to the entrance of three way catalyst
11. Hereinafter, each calculation unit of said control unit 16 will
be explained in detail.
[0107] 1. Basic fuel injection amount calculation unit 31; 2. A/F
correction term calculation unit 32; 3. Rich/lean control
permission judgement part 34; 4. #1 cylinder A/F correction amount
calculation unit 33a; 5. #2 cylinder A/F correction amount
calculation unit 33b; 6. #3 cylinder A/F correction amount
calculation unit 33c; 7. #4 cylinder A/F correction amount
calculation unit 33d.
[0108] Because basic fuel injection amount calculation unit 31, A/F
correction term calculation unit 32, rich/lean control permission
judgement part 34, and #1 to #4 cylinder A/F correction amount
calculation units 33a, 3b, 33c and 33d are the same as the first
embodiment (FIG. 11-FIG. 17), the explanation is omitted.
[0109] 8. Ignition Time Calculation Unit
[0110] FIG. 27 shows ignition time calculation unit 35. In the
ignition time calculation unit 35, the permission judgment of
rich/lean control is performed. Final ignition time ADVf is
calculated according to ADVf=ADVb-ADVRTD as shown in FIG. 27.
Where, ADVb: basic ignition time and ADVRTD: ignition time retard
amount. Basic ignition time ADVb is obtained with reference to
basic ignition time MapADVb from basic fuel injection amount Tp and
internal combustion engine revolution speed Ne.
[0111] Ignition time retard amount ADVRTD is ADRTD=KADVRTD if
retard control permission flag FpRTD=1 of the ignition time, and
ADVRTD=0 if FpRTD=0. Retard control permission flag FpRTD of the
ignition time assumes FpRTD=1 when three way catalyst downstream
temperature Ten is Ten.gtoreq.TenL3, Ten.ltoreq.TenH3, and
Ne.gtoreq.NeRTD, and the retard is performed. Otherwise, FpRTD=0,
and the retard is not performed.
[0112] Because one of the purposes of this embodiment is to
evaporate promptly the moisture in three way catalyst 11, it is
preferable to set TenL3 to at least 50.degree. C. or less. Further,
it is preferable to set TenH3 so that the maximum effect may be
achieved in the rich/lean control by setting the activation
temperature of the three way catalyst as the maximum value. It is
preferable to set retard amount KADVRTD to the retard limit
determined according to the stability of the internal combustion
engine and it is determined according to the performance of the
internal combustion engine. Further, basic ignition time map
MapADVb is determined according to the performance of the internal
combustion engine to become a so-called MBT.
[0113] Although the present invention has been illustrated and
described with respect to exemplary embodiment thereof, it should
be understood by those skilled in the art that the foregoing and
various other changes, omission and additions may be made therein
and thereto, without departing from the spirit and scope of the
present invention. Therefore, the present invention should not be
understood as limited to the specific embodiment set out above but
to include all possible embodiments which can be embodied within a
scope encompassed and equivalent thereof with respect to the
feature set out in the appended claims.
* * * * *