TITLE
CONTROL APPARATUS AND CONTROL METHOD FOR INTERNAL COMBUSTION
ENGINE
5 [Technical Field]
[0001]
The present invention relates to a control apparatus and a control method of
an internal combustion engine and in particular to a control apparatus and a control
method of an internal combustion engine equipped with a supercharger having a
10 variable flow rate mechanism and an exhaust gas recirculation apparatus.
BACKGROUND ART
[0002]
In an internal combustion engine equipped with a control apparatus for a
15 supercharger equipped with a variable flow rate mechanism being capable of
controlling an intake air amount and an intake air pressure to a combustion chamber
and a control apparatus for an exhaust gas recirculation apparatus (EGR) for
recirculating a part of the exhaust gas to an intake-air passage or a cylinder, such as
a diesel engine, in order to compensate for deficiency of the flow rate of the air
20 entering the cylinder when the EGR is operating, by throttling a guide vane of the
variable flow rate mechanism forming the supercharger (e.g. VFT) equipped with the
variable flow rate mechanism, the exhaust gas pressure increases and in response to
this, a recirculation amount of the exhaust gas recirculated by EGR increases. This
makes it difficult to secure the amount of the air introduced into the combustion
25 chamber or the intake oxygen concentration, thereby increasing black smoke
occurrence. Alternatively, by opening the guide vane of the variable flow rate
mechanism, the exhaust gas pressure declines, and this makes it difficult to secure
the recirculation amount of EGR gas and to obtain NOx reduction effect, etc. As
described above, the control for the EGR and the control for the supercharger
30 equipped with the variable flow rate mechanism have a relationship of mutual
interference that affects each other.
[0003]
Particularly, when a load torque is increase, i.e. in transition, the guide vane of
the variable flow rate mechanism of the VFT is moved toward a closed state to secure
35 the air flow rate. As a result, the exhaust gas pressure increases, the recirculation
amount of the EGR gas becomes more than necessary, the air amount and the intake
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oxygen concentration declines, and occurrence of black smoke becomes evident.
[0004]
As a cooperative control between the control for the EGR and the control for
the supercharger equipped with the variable flow rate mechanism, the technique
5 disclosed in JP2003-21000A (Patent Document l) is known. In JP2003-21000A, a
target air amount and a target supercharging pressure are individually set, and when
calculating EGR valve deviation amount, not just a difference between a detection
value of an intake amount sensor and a target air amount but a difference between a
detection value of an intake pressure sensor and a target air pressure are taken into
10 account. Further, when calculating a deviation amount of the variable geometry
mechanism (VGT) of the supercharger, not just a difference between the detection
value of the intake pressure sensor and the target supercharging pressure but a
difference between the detection value of the intake air amount sensor and the target
air amount are taken into account so as to control the EGR valve and the VGT in a
15 cooperative manner.
[0005]
Further, disclosed in JP2010-249057A (Patent Document 2) is to control the
internal combustion engine by means of a 2-input, 2-output integral-type optimal
servo system by inputting detection values of the air flow amount and the intake air
20 pressure and controlling opening of the EGR valve and opening of the guide vane of
the variable nozzle turbine, and also to change a state feedback gain KF(h) and an
integrating gain Ki(h) of the integral-type optimal servo system according to
operation conditions h of the internal combustion engine.
25 [Citation List]
[Patent Literature]
[0006]
[Patent Document 1]
JP 2003-21000 A
30 [Patent Document 2]
JP 2010-249057 A
SUMMARY
[Technical Problem]
35 [0007]
The technique of Patent Document 1 relates to the cooperative control for
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controlling the EGR valve and VGT valve by taking into account the difference
between the detection value of the intake pressure sensor and the target air pressure
as well as the difference between the detection value of the intake pressure sensor
and the target air pressure. However, a correction coefficient for the mutual control
5 is set by a constant which is set in a map. More specifically, it is a feedback control
using the correction coefficient in a partial operation state and thus, desired
characteristics may not be obtained, and without correspondence to dynamic
characteristics not being sufficiently considered, it is difficult to obtain effects in the
transient operation state
10 [0008]
Disclosed in Patent Document 2 is to control opening of the EGR valve and
opening of the guide vane of the variable nozzle turbine by means of the 2-input, 2"
output integral-type optimal servo system and also to change feedback gain KpCh) and
integrating gain Ki(h) of the integral-type optimal servo system to correspond to the
15 operation conditions h of the internal combustion engine.
There is, however, no disclosure regarding particular procedure of setting the
state feedback gain KrCh) and integrating gain Ki(h) so as to avoid control
interference between the opening of the EGR valve and the opening of the vane of the
variable nozzle turbine.
20 [0009]
Further, the control input signals described in Patent Document 1 and Patent
Document 2 include the air flow rate and the intake air pressure. However, in light
of NOx and smoke exhaust amount reduction effect in the diesel engine, the factor
which affects the exhaust amount of NOx is the intake oxygen concentration and the
25 factor which affects the smoke exhaust amount is the air flow rate. Thus, the control
based on the air flow rate and the intake air pressure is not appropriate for the
control of reducing the NOx and smoke exhaust amount.
[0010]
In view of the above issues, it is an object of the present invention, in an
30 internal combustion engine equipped with a supercharger having an EGR and a
variable flow rate mechanism, to provide a control apparatus and a control method, in
which a 2-input, 2-ouptput integral-type optimal servo system forms a control
apparatus for controlling the supercharger having the EGR and the variable flow rate
mechanism and which makes it possible to obtain efficient and stable reduction effect
35 of reducing NOx and smoke exhaust amount by avoiding interference between the
control for the EGR and the control for the supercharger having the variable flow rate
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mechanism.
[Solution to Problem]
[0011]
5 To achieve the above object, the present invention provides a control apparatus
for an internal combustion engine which comprises an exhaust gas recirculation
device and a supercharger equipped with a variable flow rate mechanism. The
control apparatus is configured to be a 2-input, 2-output integral-type optimal servo
system which uses an intake air amount and an intake oxygen concentration as a
10 controlled variable and an opening of a control valve of the exhaust gas recirculation
device and an opening of a control valve of the supercharger with the variable flow
rate mechanism as a manipulated variable, the control apparatus including an output
feedback system for feedback of the controlled variable from the internal combustion
engine. Further, the control apparatus comprises^ an EGR valve opening controller
15 for controlling the opening of the control valve of the exhaust gas recirculation device;
and a variable flow valve opening controller for controlling the opening of the control
valve of the supercharger with the variable flow rate mechanism. Each of the EGR
valve opening controller and the variable flow valve opening controller comprises a
non-interference controller for non-interference between the controlled variable
20 controlled by the manipulated variable of the control valve of the exhaust gas
recirculation device and the controlled variable controlled by the manipulated
variable of the control valve of the supercharger with the variable flow rate
mechanism with respect to each other.
[0012]
25 According the above control apparatus, the control apparatus is configured to
be a 2-input, 2-output integral-type optimal servo system which uses the intake air
amount and the intake oxygen concentration as the controlled variable and the
opening of a control valve of the exhaust gas recirculation device and the opening of a
control valve of the supercharger with the variable flow rate mechanism as the
30 manipulated variable and the control apparatus includes an output feedback system
for feedback of the controlled variable from the internal combustion engine.
Therefore, compared to two independent control apparatuses for independently
controlling the control valve of the exhaust gas recirculation device and the control
valve of the supercharger with the variable flow rate mechanism, it is possible to
35 perform cooperative control.
[0013]
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Further, the control apparatus comprises^ the EGR valve opening controller for
controlling the opening of the control valve of the exhaust gas recirculation device;
and the variable flow valve opening controller for controlling the opening of the
control valve of the supercharger with the variable flow rate mechanism, and each of
5 the controllers comprises a non-interference controller for non-interference between
the controlled variable controlled by the manipulated variable of the control valve of
the exhaust gas recirculation device and the controlled variable controlled by the
manipulated variable of the control valve of the supercharger with the variable flow
rate mechanism with respect to each other. Therefore, the non-interference
10 controller makes it possible to control the manipulated variable of the control valve of
the exhaust gas recirculation device and the manipulated variable of the control valve
of the supercharger with the variable flow rate mechanism so that they do not
interfere with each other. As a result, it is possible to reduce emissions of smoke and
NOx efficiently and stably.
15 [0014]
Further, it is preferable in the control apparatus of the present invention that
the output feedback system of the controlled variable from the internal combustion
engine includes a first output feedback signal returning to an input side of each of the
controllers and a second output feedback signal returning to an output side of said
20 each of the controllers, and a non-interference gain of the non-interference controller
is set based on an output feedback gain of the second output feedback signal.
[0015]
As described above, the non-interference gain of the non-interference controller
which is provided in each of the EGR valve opening controller and the VFT valve
25 opening controller is set based on an output feedback gain of the second output
feedback signal which is returned to the output side of each of the controllers. More
specifically, by setting the non-interference gain of the non-interference controller
based on the relationship with the output feedback gain, it is possible to configure the
non-interference controller simply.
30 [0016]
It is also preferable in the control apparatus of the present invention that each
of the EGR valve opening controller and the variable flow valve opening controller
comprises: a difference calculator for calculating a difference between a target value
of the controlled variable and the first output feedback signal in said each of the EGR
35 valve opening controller and the variable flow valve opening controller; an integrator
for integrating the difference calculated by the difference calculator; and the non%
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interference controller to which an integrated value calculated by the integrator is
input.
As described above, the non-interference gain is applied to the signal
integrated by the integrator and thus, it is possible to efficiently perform the non
5 interference.
[0017]
It is preferable in the control apparatus of the present invention that each of
the EGR valve opening controller and the variable flow valve opening controller
comprises: a difference calculator for calculating a difference between a target value
10 of the controlled variable and the first output feedback signal in said each of the EGR
valve opening controller and the variable flow valve opening controller! the noninterference
controller to which a difference value calculated by the difference
calculator is input! and an integrator for integrating an output value from the noninterference
controller.
15 As described above, by arranging the integrator downstream from the noninterference
controller, even when change in the engine rotation speed or the fuel
injection amount in the steady operation causes fluctuation of the non-interference
gain, the output from the non-interference controller is integrated by the integrator
and output as the manipulated variable and thus, the non interference is performed
20 in a stable manner.
[0018]
Further, it is preferable in the control apparatus of the present invention that
each of the EGR valve opening controller and the variable flow valve opening
controller comprises: a limiter for limiting the manipulated variable within a certain
25 range! and an anti-windup part.
After the manipulated variable is limited by the limiter and if the target value
of the controlled variable changes, windup (saturation of the integrator) occurs in the
case where the anti-windup part is not provided, and this lowers the controlled
variable responsiveness. In the present embodiment, however, the anti-windup part
30 is provided to prevent occurrence of windup and improve the controlled variable
responsiveness. As a result, it is possible to improve reduction in NOx emission and
black smoke emission in a transient state.
[0019]
Furthermore, it is preferable in the control apparatus of the present invention
35 that the non-interference gain of the non-interference controller is set as map data
which corresponds to a rotation speed and a fuel injection amount of the internal
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combustion engine. By storing the non-interference gain as the map data
corresponding to the operating state of the internal combustion engine, it is possible
to simplify the control apparatus.
[0020]
5 Moreover, according to the present invention, a control method for an internal
combustion engine which comprises an exhaust gas recirculation device and a
supercharger equipped with a variable flow rate mechanism, comprises the steps of
controlling by a 2-input, 2-output integral-type optimal servo system which
uses an intake air amount and an intake oxygen concentration as a controlled
10 variable and an opening of a control valve of the exhaust gas recirculation device and
an opening of a control valve of the supercharger with the variable flow rate
mechanism as a manipulated variable, and controlling by an output feedback system
for feedback of the controlled variable from the internal combustion engine,'
calculating a non-interference gain of a non-interference controller based on an
15 output feedback gain of an output feedback signal, the non-interference controlling
being configured to non-interfere the controlled variable controlled by the
manipulated variable of the control valve of the exhaust gas recirculation device and
the controlled variable controlled by the manipulated variable of the control valve of
the supercharger with the variable flow rate mechanism with respect to each other!
20 and
calculating the manipulated variable of the control valve of the exhaust gas
recirculation device and the manipulated variable of the control valve of the
supercharger with the variable flow rate mechanism based on an output value being
set to the calculated non-interference gain.
25 [0021]
According to this control method of the present invention, by controlling by a
2-input, 2-output integral-type optimal servo system which uses an intake air amount
and an intake oxygen concentration as a controlled variable and an opening of a
control valve of the exhaust gas recirculation device and an opening of a control valve
30 of the supercharger with the variable flow rate mechanism as a manipulated variable,
and controlling by an output feedback system for feedback of the controlled variable
from the internal combustion engine, it is possible to perform cooperative control with
each other, compared to two independent control apparatuses for independently
controlling the control valve of the exhaust gas recirculation device and the control
35 valve of the supercharger with the variable flow rate mechanism.
[0022]
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Further, by calculating a non-interference gain of a non-interference controller
based on an output feedback gain of an output feedback signal, the non-interference
controlling being configured to non-interfere the controlled variable controlled by the
manipulated variable of the control valve of the exhaust gas recirculation device and
5 the controlled variable controlled by the manipulated variable of the control valve of
the supercharger with the variable flow rate mechanism with respect to each other!
and calculating the manipulated variable of the control valve of the exhaust gas
recirculation device and the manipulated variable of the control valve of the
supercharger with the variable flow rate mechanism based on an output value being
10 set to the calculated non-interference gain, it is possible to control in such a manner
that the controlled variable controlled by the manipulated variable of the control
valve of the exhaust gas recirculation device and the controlled variable controlled by
the manipulated variable of the control valve of the supercharger with the variable
flow rate mechanism do not interfere with each other.
15
[Advantageous Effects]
[0023]
According to the control apparatus and control method of the present invention,
in the internal combustion engine provided with EGR and the variable flow
20 mechanism with supercharger, by controlling the turbocharger provided with the EGR
and the variable flow rate mechanism by means of a 2-input, 2-output integral-type
optimal servo system and avoiding mutual interference of the control of the EGR and
the control of the turbocharger with variable flow rate mechanism with each other, it
is possible to reduce emissions of smoke and NOx efficiently and stably.
25
BRIEF DESCRIPTION OF DRAWINGS
[0024]
[FIG.l]
FIG.l is a general schematic view of a diesel engine to which a control apparatus of
30 an internal combustion engine according to a first embodiment of the present
invention is applied.
[FIG.2]
FIG.2 is a cross-sectional view of a main section of a supercharger equipped with a
variable flow rate mechanism.
35 [FIG.3]
FIG.3 is a block diagram illustrating a configuration of the control apparatus
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according to the first embodiment.
[FIG.4A]
FIG.4Ais an explanatory drawing of a non-interference control.
[FIG.4B]
5 FIG.4B is an explanatory drawing of a non-interference control.
[FIG.4C]
FIG.4C is an explanatory drawing of a non-interference control.
[FIG.5]
FIG.5 is a configuration diagram of the control apparatus according to the first
10 embodiment.
[FIG.6A]
FIG.6A is an explanatory drawing of a target intake oxygen concentration setting part.
[FIG.6B]
FIG.6B is an explanatory drawing of a target intake air amount setting part.
15 [FIG.6C]
FIG.6C is an explanatory drawing of an intake oxygen concentration estimating unit.
[FIG.7A]
FIG.7A is a block diagram of a configuration of the control apparatus according to the
first embodiment.
20 [FIG.7B]
FIG.7B is a block diagram of a configuration of the control apparatus according to a
second embodiment.
[FIG.8]
FIG.8 is a configuration diagram of the control apparatus according to the second
25 embodiment.
[FIG.9]
FIG.9 is a configuration diagram of the control apparatus according to a third
embodiment.
30 DETAILED DESCRIPTION
[0025]
Embodiments of the present invention will now be described in detail with
reference to the accompanying drawings. It is intended, however, that unless
particularly specified, dimensions, materials, shapes, relative positions and the like of
35 components described in the embodiments shall be interpreted as illustrative only
and not limitative of the scope of the present invention.
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[0026]
(First Embodiment)

In reference to FIG.l, described is an overall configuration of a diesel engine to
5 which a control apparatus of an internal combustion engine according to the present
invention is applied.
A diesel engine (engine) 1 is provided with an exhaust turbocharger 7 having
an exhaust turbine 3 and a compressor 5 which is coaxially driven to the exhaust
turbine 3. The diesel engine 1 is configured so that air discharged from the
10 compressor 5 of the exhaust turbocharger 7 passes through an intake air passage 9,
enters an intercooler 11 to be cooled. The intake flow rate of the cooled intake air is
controlled by an intake throttle valve 13, and then is made to flow into a combustion
chamber (not shown) of the engine 1 from the intake manifold 15.
[0027]
15 This exhaust turbocharger 7 is a supercharger with a variable flow rate
mechanism (VFT). This exhaust turbocharger 7 includes, as illustrated in FIG.2, an
outer scroll 21 and an inner scroll 19 extending to surround the entire circumference
of the turbine rotor 17 continuously in the circumferential direction. The exhaust
turbocharger 7 is provided with a VFT control valve 23 configured to switch between
20 a state where the exhaust gas flows into the inner scroll 19 alone and a state where
the exhaust gas flows into both the inner scroll 19 and the outer scroll 21.
[0028]
The VFT control valve 23 is provided at one place of an end of the housing 25.
By operating this VFT control valve 23, it is possible to switch the state between the
25 state for allowing the exhaust gas to flow only to the inner scroll 19 and the state for
allowing the exhaust gas to flow to both the inner scroll 19 and the outer scroll 21.
Further, in addition to switching its opening and closing, the opening can be adjusted
to an intermediate-open state so as to arbitrarily adjust the intake flow rate and the
intake air pressure which are supercharged.
30 [0029]
As illustrated in FIG.l, in the engine 1, the high-pressure fuel supplied from a
fuel supply device (not shown) is injected into the combustion chamber by controlling
the fuel injection timing and the injection amount from the fuel injection valve 27 by
a fuel injection control device 29.
35 Further, the combustion gas, i.e. exhaust gas 31 combusted in the combustion
chamber of the engine 1 passes through an exhaust manifold formed by exhaust ports
10
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respectively provided for cylinders and through an exhaust passage 35 to drive the
exhaust turbine 3 of the exhaust turbocharger 7 and become a power source for the
compressor 5. Then, the exhaust gas 31 passes through the exhaust passage 35 and
is discharged through an exhaust gas after-treatment device (not shown).
5 [0030]
An EGR passage 37 is branched from the middle of the exhaust passage 35 or
exhaust manifold 33 so that a part of the exhaust gas is introduced to a downstream
portion of the intake throttle valve 13 through an EGR cooler 39 and an EGR control
valve 41. An, EGR unit 40 is constituted by the EGR passage 37, the EGR cooler 39
10 and the EGR control valve 41.
[0031]
On an upstream side of the exhaust turbocharger 7, an airflow meter 43 and
an atmospheric temperature sensor 45 are provided. In the intake manifold 15, an
intake air temperature sensor 47, an intake air pressure sensor 49 are provided.
15 Further, an engine speed sensor 51 and atmospheric pressure sensor 53 are provided
so that signals from the sensors are incorporated into a control apparatus (ECU) 57
via a signal converter 55. Furthermore, the fuel injection amount signal is taken into
the control apparatus (ECU) 57 from the fuel injection control device 29.
[0032]
20 Moreover, from the control apparatus (ECU) 57, an EGR valve operation
amount signal u l is output to the EGR control valve 41, and a VFT valve operation
amount signal u2 is output to the VFT control valve 23 of the exhaust turbocharger 7.
[0033]

25 The control apparatus 57 is constituted by an integral-type optimal servo
system which integrates an EGR control for controlling the opening of the EGR
control valve 41 and a VFT control for controlling opening of the VFT control valve 23
of the exhaust turbocharger 7.
More specifically, the control apparatus 57 is configured to be a 2-input, 2-
30 output integral-type optimal servo system which uses an intake air amount and an
intake oxygen concentration as a controlled variable and an opening of the EGR
control valve and an opening of the VFT control valve 23 of the exhaust turbocharger
7 as a manipulated variable. Further, the control apparatus 57 includes an output
feedback system for feedback of the intake air amount and the intake oxygen
35 concentration as the controlled variable from the engine 1.
[0034]
11
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This 2-input, 2-output integral-type optimal servo system is described below.
FIG.3 is a block diagram illustrating a configuration of an integral servo
system according to an embodiment of the present invention. The target value r of
the controlled variable (the intake air amount and the intake oxygen concentration) is
5 input, and the target value r is set in advance according to the operation state of the
engine. For instance, the target value r is calculated based on map data which is
described later, arithmetic expression or the like.
[0035]
The adder-subtracter 60 is used to calculate the difference between the target
10 value r and a detection value from the engine 1 which is a controlled object or the
output calculated based on the detection value, (e=r-y). The difference e is
integrated by an integrator 62, and the output v is input to a non-interference
controller 64. Then, the output w of the non-interference controller 64 is input to an
adder-subtracter 66 to calculate by the adder-subtractor 60 the difference between the
15 output w of the non-interference controller 64 and the output Fy from an output
feedback gain unit 68, (u=w-Fy). The calculated value is output to the VFT control
valve 23 of the exhaust turbocharger 7 and the EGR control valve 41 as the
manipulated value u.
The output feedback is formed by a first output feedback for feedback to the
20 adder-subtractor 60 and a second output feedback for feedback to the addersubtractor
66.
[0036]
Here, the theory of the non-interference controller 64 is explained.
When the output feedback gain F (2 x 2 matrix) which is set by the output
25 feedback gain unit 68, is F = 8 (CB) "i using a B matrix, a C matrix and an adjustable
parameter 6 of a state equation. Controlled object P (State variable x, x), the
configuration block diagram shown in FIG.3 is expressed below and the following
expressions (l) to (6) are satisfied.
[0037]
30
12
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x = Ax + B u ( l )
= Ax + B(w-Fy) (•:u = w-Fy) (2)
= Ax- BFCx + Bw {:• y = Cx) ( 3 )
= iA-BFC)x + Bw (4)
Further, from the relationship w = Gv
w = Gv = [c{-A + BFCy'B]\ (5)
G^[c{-A + BFCy'BY (6)
[0038]
By setting a non-interference gain G of the non-interference controller 64 to
satisfy the relationship expression (6), it is possible to perform non-interference.
5 In other words, the non-interference gain G can be set using the output
feedback gain F as well as the A, B and C matrices representing the state equation of
the transfer coefficient which defines the relationship between the intake air amount
and the intake oxygen concentration with respect to the manipulated variable in the
EGR control valve 41 and the VFT control valve 23 which are controlled objects.
10 Thus, it is possible to simply configure the non-interference controller 64.
[0039]
FIG.4 shows non-interference characteristics from v to y and schematically
illustrates a transfer function between v and w which is a transfer function of the
non-interference controller 64 and a transfer function between w and y which is a
15 transfer function of the controlled object P.
The transfer function can be expressed as illustrated in FIG.4A. It becomes
S->0 (t—•GO) in a stable state as illustrated in F1G.4B, and v to y asymptotically moves to
an identity matrix I. In this manner, the non-interference system can be configured.
[0040]
20 FIG.5 shows a block diagram of the control apparatus 57. The control
apparatus 57 is provided with an EGR valve opening controller 70 for controlling the
opening of the EGR control valve 41 of the exhaust gas recirculation device and a VFT
valve opening controller (a variable flow valve opening controller) 72 for controlling
the opening of the VFT control valve 23 of the exhaust turbocharger with the variable
25 flow rate mechanism. Each of the controllers comprises the integrator 62, the noninterference
controller 64 and the output feedback gain unit 68 which have respective
configurations described in reference to FIG.3.
13
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[0041]
A target intake oxygen concentration setting part 80 shown in F1G.6A is
provided. In the target intake oxygen concentrating setting part 80, the target
intake oxygen concentration r l is obtained, for instance, from a target intake oxygen
5 concentration map 82 and using the operating state of the engine 1 as a parameter,
such as the engine speed from the engine speed sensor 51, the fuel injection amount
from the fuel injection control device 29, the atmospheric temperature from the
atmospheric temperature sensor 45 and the atmospheric pressure from the
atmospheric pressure sensor 53.
10 [0042]
As the controlled variable (output) yl of the intake oxygen concentration from
the engine 1, a value estimated by an intake oxygen concentration part 84 illustrated
in FIG.6C is used.
This intake oxygen concentration estimation part 84 calculates based on
15 respective signals of the air flow rate from the air flow meter 43 which indicates the
operating state of the engine 1, the intake manifold pressure and temperature in the
intake manifold 15 from the intake temperature sensor 47 and the intake air pressure
sensor 49, the engine rotation speed from the engine rotation speed sensor 51 and the
fuel injection amount from the fuel injection control device 29.
20 The actual intake oxygen concentration estimated by the intake oxygen
concentration estimation part 84 and the target intake oxygen concentration set by
the target intake oxygen concentration setting part 80 are input to the addersubtractor
60a to calculate the difference el as the output from the adder-subtractor
60a. This calculated value of e l is input to the integrator 62a.
25 [0043]
Similarly, the target intake amount is set by the target intake air amount
setting part 90 illustrated in F1G.6B. In the target intake air amount setting part 90,
the target intake air amount r2 is obtained, for instance, from a target intake air
amount map 92 and using the operating state of the engine 1 as a parameter, such as
30 the engine speed from the engine speed sensor 51, the fuel injection amount from the
fuel injection control device 29, the atmospheric temperature from the atmospheric
temperature sensor 45 and the atmospheric pressure from the atmospheric pressure
sensor 53.
[0044]
35 Further, the controlled variable (output) y2 of the intake air amount from the
engine 1 is obtained based on the signal from the air flow meter 43. Then, the
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difference e2 between the actual intake air amount y2 and the target intake air
amount r2 set by the target intake air amount setting part 90 is calculated as output
from the adder-subtractor 60b. This calculated value of e2 is input to the integrator
62b.
5 [0045]
Next, the difference el calculated by the adder-subtractor 86 of the EGR valve
opening controller 70 is input to the integrator 62a to perform integral calculation.
The output of this integral calculation is then input to the non-interference controller
64 where the output of the integral calculation and the non-interference gain G which
10 is set in advance by the relationship of the expression (6) are multiplied by a
multiplier 96a.
[0046]
The non-interference gain G is decomposed and set as a parameter indicating
the operating state of the engine for each component (Gil, G21, G12, G22), for
15 instance the engine rotation speed Ne and the fuel injection amount Qf set as
parameters. These parameters are stored in a storage part of the control apparatus
57 as the non-interference gain maps 100, 101, 102, 103. Although not shown in
FIG.5, the signals of the engine rotation speed Ne and the fuel injection amount Qf
are input to each of the non-interference gain maps 100, 101, 102, 103.
20 [0047]
In the non-interference gain map 100, the component Gil of the noninterference
gain is set and a gain value that defines the relationship between the
opening degree of the EGR control valve 41 and the intake oxygen concentration is set.
Further, in the non-interference gain map 101, the component G12 of the non-
25 interference gain is set and a gain value which defines the non-interference
relationship between the opening degree of the VFT control valve 23 and the intake
oxygen concentration is stored.
[0048]
Similarly, in the non-interference gain map 103, the component G22 of the non-
30 interference gain is set and a gain value that defines the relationship between the
intake air amount and the opening degree of the VFT control valve 23 is set. Further,
in the non-interference gain map 102, the component G12 of the non-interference gain
is set and a gain value that defines the non-interference relationship between the
intake air amount and the opening degree of the VFT control valve 41 is set.
35 [0049]
The component Gil of the non-interference gain of the EGR valve opening
15
^
12-018PCT
controller 70 is multiplied with the output signal of the integrator 62a by the
multiplier 96a and then input to an adder 105a. Further, the component G12 of the
non-interference gain of the VFT valve opening controller 72 is multiplied with the
output signal of the integrator 62b by the multiplier 96c and then input to the adder
5 105a. Finally, these signals are added together and output as the output signal wl.
[0050]
Similarly, in the VFT valve opening controller, the component G22 of the noninterference
gain is multiplied by the multiplier 96d with the output signal of the
integrator 62b and then input to an adder 105b. Further, the component G21 of the
10 non-interference gain of the EGR valve opening controller 70 is multiplied with the
output signal of the integrator 62a by the multiplier 96b and then input to the adder
105b. Finally, these signals are added together and output as the output signal w2.
[0051]
The output signal wl of the EGR valve opening controller 70 is then input to
15 the adder-subtracter 66a to be added/subtracted with the output signal from the
output feedback gain unit 68 by the adder-subtracter 66a.
The output feedback gain unit 68 is configured to multiply by multipliers 70a
to 70d the output feedback gain F with the intake oxygen concentration and the
intake air amount having been feedbacked.
20 [0052]
By decomposing a 2 x 2 matrix, the output feedback gain F is set as a
parameter indicating the operating state of the engine for each component (Fll, F21,
F12, F22), for instance the engine rotation speed Ne and the fuel injection amount Qf
being set as parameters. These parameters are stored in a storage part of the
25 control apparatus 57 as the output feedback gain maps 105, 106, 107, 108. Although
not shown in FIG.5, the signals of the engine rotation speed Ne and the fuel injection
amount Qf are input to each of the output feedback gain maps 105, 106, 107, 108.
This output feedback gain F is set so that the gain value which can satisfy the
non-interference relationship by the above expression (6) is set.
30 [0053]
In the output feedback gain map 105, the component F l l of the output
feedback gain is set and a gain value that defines the relationship between the intake
oxygen concentration and the opening degree of the EGR control valve 41 is set.
Further, in the output feedback gain map 106, the component F21 of the output
35 feedback gain is set and a gain value for determining the non-interference
relationship between the intake oxygen concentration and the opening degree of the
16
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12-018PCT
VFT control valve 23 is stored.
[0054]
Similarly, in the output feedback gain map 108, the component F22 of the
output feedback gain is set and a gain value that defines the relationship between the
5 intake air quantity and the opening degree of the VFT control valve 23 is set.
Further, in the output feedback gain map 107, the component F12 of the output
feedback gain is set and a gain value for determining the non-interference
relationship between the intake air quantity and the opening degree of the EGR
control valve 41 is stored.
10 [0055]
The output signal wl from the non-interference controller 64 of the EGR valve
opening controller 70 is input to the adder-subtractor 66a, is subtracted with the
output signal from the output feedback gain unit 68, then a nonlinear signal is
converted to a linear output signal in a non-linearity correction part 110a, and finally
15 the linear output signal is processed by limiter processing in a limiter part 112a and
is output as an output signal u l of the opening degree operation amount of the EGR
control valve 41.
[0056]
Similarly, in the VFT valve opening controller 72, the output signals w2 from
20 the non-interference controller 64 is input to the adder-subtractor 66b, is subtracted
with the output signal from the output feedback gain unit 68, then, a nonlinear signal
is converted to a linear output signal in a non-linear correction part 110b, and finally
the linear output signal is processed by limiter processing in a limiter part 112b and
is output as an output signal u2 of the opening degree operation amount of the VFT
25 control valve 23.
[0057]
The limiter parts 112a and 112b are provided to regulate the manipulated
variable of the EGR control valve 41. However, this is not limitative and, in place of
the limiter parts, the maximum and minimum opening degrees of the EGR control
30 valve 41 may be set based on a EGR valve minimum opening map 114 and a EGR
valve maximum opening map 116 that are set optimally according to an operating
state of the engine (the engine rotation speed Ne and the fuel injection amount Qf) as
illustrated in FIG.8.
[0058]
35 This is because, once the EGR valve is fully opened, the intake air amount
tends to remain the same even by changing the opening degree of the VFT control
- 17-
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12-018PCT
valve 23. Thus, the opening is limited, by providing the maximum opening map,
such that the maximum opening degree is the degree that is not affected by change of
the VFT control valve 23. Further, the minimum opening degree is set so that
exhaust gas purification performance can be confirmed at the minimum opening
5 degree, to ensure the exhaust gas purification performance.
[0059]
According to the control apparatus 57 configured as described above, the
control apparatus 57 is configured to be a 2-input, 2-output integral-type optimal
servo system which uses the intake air amount and the intake oxygen concentration
10 as the controlled variable and the opening degree of the EGR control valve 41 and the
opening degree of the VFT control valve 23 of the exhaust turbocharger 7 with the
variable flow rate mechanism, and the control apparatus 57 includes an output
feedback system for feedback of the detected intake air amount from the engine 1 and
the intake oxygen concentration calculated based on the operating state of the engine
15 1. Therefore, compared to two independent control apparatuses for independently
controlling the EGR control valve 41 of the exhaust gas recirculation device and the
VFT control valve 23 of the exhaust turbocharger 7, it is possible to perform
cooperative control.
[0060]
20 Further, the control apparatus 57 comprises the EGR valve opening controller
70 for controlling the opening of the EGR control valve 41 of the exhaust gas
recirculation device and the VFT opening controller 72 for controlling the opening of
the VFT control valve 23 of the exhaust turbocharger 7 with the variable flow rate
mechanism. Furthermore, the non-interference controller 64 is provided for non-
25 interference between the controlled variable controlled by the manipulated variable of
the EGR control valve 41 and the controlled variable controlled by the manipulated
variable of the VFT control valve 23. By the non-interference controller 64, it is
possible to control so that the controlled variable controlled by the manipulated
variable of the EGR control valve 41 does not interfere with the controlled variable
30 controlled by the manipulated variable of the VFT control valve 23.
[0061]
Further, the non-interference gain G of this non-interference controller 64 can
be set using the output feedback gain F as well as the A, B and C matrices
representing the state equation of the transfer coefficient which defines the
35 relationship between the intake air amount and the intake oxygen concentration with
respect to the manipulated variable in the EGR control valve 41 and the VFT control
18
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valve 23 which are controlled objects. Thus, it is possible to simply configure the
non-interference controller 64.
[0062]
(Second Embodiment)
5 Next, referring to FIG.7 and FIG.8, a second embodiment is described. The
second embodiment differs from the first embodiment in that the integral calculation
section 63 of the integrator 62 is placed after addition and subtraction of the output
signal from the non-interference controller 64 and the output feedback gain unit 68.
[0063]
10 FIG.7A is a block diagram of the configuration according to the first
embodiment in which the integral gain is set in an integral gain section 65 and then
calculated in the integral calculation section 63. In contrast, in the second
embodiment illustrated in FIG.7B, the integral calculation section 63 is placed after
the adder-subtractor 66.
15 Therefore, differential processing of the output feedback gain signal is required.
Thus, a differential processing section 120 is arranged before the output feedback
gain unit 68.
[0064]
A specific configuration diagram is illustrated in FIG.8. In the EGR valve
20 opening controller 70, the integral calculation section 63a of the integrator 62a is
provided behind the adder-subtractor 66a. Further, a differential processing unit 120a
is provided at the input to the output feedback gain unit 68.
In the VFT valve opening control unit 72 as well, the integral calculation
section 63b of the integrator 62b is provided behind the adder-subtractor 66b. Further,
25 a differential processing unit 120b is provided at the input to the output feedback
gain unit 68.
The rest of the configuration is substantially the same as that of the first
embodiment illustrated in FIG.5 and thus components already described with
reference to FIG.5 are denoted by the same reference numerals, and thus detailed
30 description thereof will be hereinafter omitted.
[0065]
In this manner, the integral calculation section 63a, 63 of the integrator 62a,
62b is placed after the non-interference gain G is set by the non-interference
controller 64, the output feedback gain F is set by the output feedback gain unit 68
35 and then the output signal obtained by multiplying these gains is added/subtracted by
the adder-subtractor 66a, 66b, so as to perform stable non-interference.
19
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[0066]
More specifically, the non-interference gain G is set by the non-interference
controller 64 based on the non-interference maps 100, 101, 102, 103 whose
parameters include the engine rotation speed or the fuel injection amount and thus,
5 small change in the engine rotation speed or the fuel injection amount in the steady
operation can cause fluctuation of the non-interference gain and this may cause
oscillation of the outputted manipulated variable. In the present embodiment, the
non-interference gain is integrated by the integral calculation section 63a, 63b and
then is output as the manipulated variable to perform the stable non-interference
10 processing. More specifically, even by precisely setting the non-interference gain G
and the output feedback gain F based on the map data using the engine rotation
speed and the fuel injection amount as parameters, it is possible to achieve the steady
non-interference effect with no oscillation of the manipulated variable.
[0067]
15 (Third Embodiment)
Next, a third embodiment is described in reference to FIG.9. The third
embodiment differs from the second embodiment in that an anti-windup part 130 is
provided.
This anti-windup part 130 is configured, as illustrated in FIG.9 so that the
20 output signal u l of the manipulated variable of the opening degree of the EGR control
valve 41 and the output signal u2 of the manipulated variable of the opening degree
of the VFT control valve 23 are input to non-linear sections 132a and 132b,
respectively, and added/subtracted in the adder-subtractors 134a and 134b with the
output of the integral calculation sections 63a and 63b and multiplied by gain in gain
25 sections 136a and 136b and then returned to the input side to be added to the
differences el and e2 in adders 138a and 138b.
[0068]
After the output signals u l and u2 of the manipulated variable are limited by
the limiter, if the target value of the controlled variable changes, windup (saturation
30 of the integrator) occurs in the case where the anti-windup part is not provided, and
this reduces the controlled variable responsiveness. In the present embodiment, by
providing the anti-windup part 130, windup occurrence is prevented and the
controlled variable responsiveness is improved to improve reduction in NOx emission
and black smoke emission in a transient state.
35 [0069]
In the above embodiments, the VFT ((variable flow turbo) equipped with the
20
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VFT control valve 23 as illustrated in FIG.2 is described as the exhaust turbocharger
7 equipped with the variable flow rate mechanism. However, this configuration is
not restrictive and it may be a VGT (variable geometry turbo) configuration which is
configured to vary an exhaust gas amount fed to a turbine wheel by changing the
opening degree of the vanes provided around the turbine wheel, or may be any
configuration as long as the supercharging flow rate is variable.
Further, the intake air amount is calculated based on the detection value from
the air flow meter 43. However, this is not restrictive, and the intake air amount
may be calculated based on a single regarding the operation condition of the engine 1.
[Industrial Applicability]
[0070]
According to the present invention, in the internal combustion engine provided
with EGR and the variable flow mechanism with supercharger, the control apparatus
15 for controlling the turbocharger provided with the EGR and the variable flow rate
mechanism is composed of a 2-input, 2-output integral-type optimal servo system, and
it is possible to avoid mutual interference of the control of the EGR and the control of
the turbocharger with variable flow rate mechanism with each other, reduce
emissions of smoke and NOx efficiently and stably. Thus, it is suitable for use in the
20 control apparatus for the internal combustion engine and the control method.
21

#
•' t ^
• >
I
12-018PCT
, rr.-'^
CLAIMS . , ; -
1. A control apparatus for an internal combustion engine which comprises an
exhaust gas recirculation device and a supercharger equipped with a variable flow
rate mechanism,
5
wherein the control apparatus is configured to be a 2-input, 2-output integraltype
optimal servo system which uses an intake air amount and an intake
oxygen concentration as a controlled variable and an opening of a control valve
of the exhaust gas recirculation device and an opening of a control valve of the
10 supercharger with the variable flow rate mechanism as a manipulated variable,
the control apparatus including an output feedback system for feedback of the
controlled variable from the internal combustion engine,
wherein the control apparatus comprises:
15 an EGR valve opening controller for controlling the opening of the control valve
of the exhaust gas recirculation device; and
a variable flow valve opening controller for controlling the opening of the
control valve of the supercharger with the variable flow rate mechanism, and
20 wherein each of the EGR valve opening controller and the variable flow valve
opening controller comprises a non-interference controller for non-interference
between the controlled variable controlled by the manipulated variable of the
control valve of the exhaust gas recirculation device and the controlled variable
controlled by the manipulated variable of the control valve of the supercharger
25 with the variable flow rate mechanism with respect to each other.
2. The control apparatus according to claim 1,
30 wherein the output feedback system of the controlled variable from the internal
combustion engine includes a first output feedback signal returning to an input
side of each of the controllers and a second output feedback signal returning to
an output side of said each of the controllers, and
35 wherein a non-interference gain of the non-interference controller is set based on
an output feedback gain of the second output feedback signal.
22
15
•U.l'*J^i'i'h'«
'^'* 1^18PCT
oj
a B '«-*
v) ^
3. The control apparatus according to claim 2,
5 wherein each of the EGR valve opening controller and the variable flow valve
opening controller comprises:
a difference calculator for calculating a difference between a target value of the
controlled variable and the first output feedback signal in said each of the
EGR valve opening controller and the variable flow valve opening controller!
10 an integrator for integrating the difference calculated by the difference
calculator; and
the non-interference controller to which an integrated value calculated by the
integrator is input.
4. The control apparatus according to claim 2,
wherein each of the EGR valve opening controller and the variable flow valve
opening controller comprises^
20 a difference calculator for calculating a difference between a target value of
the controlled variable and the first output feedback signal in said each of
the EGR valve opening controller and the variable flow valve opening
controller;
the non-interference controller to which a difference value calculated by the
25 difference calculator is input; and
an integrator for integrating an output value from the non-interference
controller.
30 5. The control apparatus according to any one of claims 1 to 4,
wherein each of the EGR valve opening controller and the variable flow valve
opening controller comprises:
a limiter for limiting the manipulated variable within a certain range; and
35 an anti'windup part.
23
< ^ %.% I 12-018PCT
The control apparatus according to claim 2, 0 \ u
TlW3
wherein the non-interference gain of the non-interference controller is set as map
data which corresponds to a rotation speed and a fuel injection amount of the
internal combustion engine.
7. A control method for an internal combustion engine which comprises an
10 exhaust gas recirculation device and a supercharger equipped with a variable flow
rate mechanism, the control method comprising the steps of
controlling by a 2-input, 2-output integral-type optimal servo system which uses
an intake air amount and an intake oxygen concentration as a controlled
15 variable and an opening of a control valve of the exhaust gas recirculation
device and an opening of a control valve of the supercharger with the variable
flow rate mechanism as a manipulated variable, and controlling by an output
feedback system for feedback of the controlled variable from the internal
combustion engine!
20
calculating a non-interference gain of a non-interference controller based on an
output feedback gain of an output feedback signal, the non-interference
controlling being configured to non-interfere the controlled variable controlled
by the manipulated variable of the control valve of the exhaust gas
25 recirculation device and the controlled variable controlled by the manipulated
variable of the control valve of the supercharger with the variable flow rate
mechanism with respect to each other,' and
calculating the manipulated variable of the control valve of the exhaust gas
30 recirculation device and the manipulated variable of the control valve of the
supercharger with the variable flow rate mechanism based on an output value
being set to the calculated non-interference gain.