CONTROL DEVICE OF INTERNAL COMBUSTION ENGINE

The invention relates to a controlled object (63, 52) for variably controlling a control amount relating to the engine and an actuator for changing the operation state of the controlled object. The control device comprises means for determining a control signal to be given to the actuator for feedback controlling the driving state of the actuator to accomplish the target operation state. The control device changes the operation state of the controlled object by driving the actuator when no fuel is supplied to the combustion chamber, measures as a control amount change delay time, the time from the start of the driving of the actuator until the start of the control amount and sets a feedback gain used in the determination of the control signal by the actuator control means in consideration of the measured control amount change delay time.

MODE FOR CARRYING OUT THE INVENTION

An embodiment of a control device of an internal combustion engine of the invention (hereinafter, this embodiment may be referred to as —first embodiment—) will be explained.

In the following explanation, the term “engine operation” means —operation of an internal combustion engine—, the term “engine speed” means —rotation speed of the engine— and the term “fuel injection amount” means —an amount of a fuel injected from a fuel injector—.

An internal combustion engine which a control device of the first embodiment is applied, is shown inFIG. 1.

InFIG. 1,20denotes a body of the engine10,21denotes fuel injectors,22denotes a fuel pump,23denotes a fuel supply passage,30denotes an intake passage,31denotes an intake manifold,32denotes an intake pipe,33denotes a throttle valve,34denotes an intercooler,35denotes an air flow meter,36denotes an air cleaner,37denotes a supercharging pressure sensor,40denotes an exhaust passage,41denotes an exhaust manifold,42denotes an exhaust pipe,60denotes a supercharger,70denotes an acceleration pedal,71denotes an acceleration pedal depression amount sensor,72denotes a crank position sensor and80denotes an electronic control unit.

The intake passage30is constituted by the intake manifold31and the intake pipe32. The exhaust passage40is constituted by the exhaust manifold41and the exhaust pipe42.

The electronic control unit80is constituted by a micro computer. The electronic control unit80has a CPU (a micro processor)81, a ROM (a read only memory)82, a RAM (a random access memory)83, a backup RAM84and an interface85. These CPU81, ROM82, RAM83, backup RAM84and interface85are connected to each other by a bidirectional bus.

The fuel injectors21are arranged on the body20of the engine. The fuel pump22is connected to the fuel injectors21via the fuel supply passage23. The fuel pump22supplies a fuel having a high pressure to the fuel injectors21via the fuel supply passage23.

The fuel injectors are electrically connected to the interface85of the electronic control unit80. The electronic control unit80gives to the fuel injectors21, command signals for making the fuel injectors21inject the fuel.

The fuel pump22is electrically connected to the interface85of the electronic control unit80. The electronic control unit80gives to the fuel pump22, a control signal for controlling the operation of the fuel pump22so as to maintain the pressure of the fuel supplied from the fuel pump22to the fuel injectors21at a predetermined pressure.

The fuel injectors21are arranged on the body20of the engine such that their fuel injection holes are exposed in combustion chambers. Therefore, when the command signal is given from the electronic control unit80to the fuel injector21, the fuel injector21injects the fuel directly into the combustion chamber.

The intake manifold31is divided at its one end to a plurality of pipes and each pipe is connected to a corresponding intake port (not shown) formed corresponding to the combustion chamber of the body20of the engine. The intake manifold31is connected at its other end to one end of the intake pipe32.

The exhaust manifold41is divided at its one end to a plurality of pipes and each pipe is connected to a corresponding exhaust port (not shown) formed corresponding to the combustion chamber of the body20of the engine. The exhaust manifold41is connected at its other end to one end of the exhaust pipe42.

The throttle valve33is arranged in the intake pipe32. When an opening degree of the throttle valve33(hereinafter, this degree may be referred to as —throttle valve opening degree—) is changed, a flow area in the intake pipe32at an area where the throttle valve33is arranged, changes. Thereby, an amount of an air passing through the throttle valve33changes and as a result, an amount of the air suctioned into the combustion chamber changes.

An actuator for changing an operation state of the throttle valve33(i.e. the throttle valve opening degree) is connected to the throttle valve33(hereinafter, this actuator may be referred to as —throttle valve actuator—). The throttle valve actuator is electrically connected to the interface85of the electronic control unit80.

The electronic control unit80gives to the throttle valve actuator, a control signal for driving the throttle valve actuator to control the throttle valve opening degree to a target throttle valve opening degree.

The intercooler34is arranged in the intake pipe32on the upstream side of the throttle valve33. The intercooler34cools the air flowing thereinto.

The air flow meter35is arranged in the intake pipe32on the upstream side of the intercooler34. The air flow meter35is electrically connected to the interface85of the electronic control unit80.

The air flow meter35outputs an output value corresponding to the amount of the air passing therethrough. This output value is input into the electronic control unit80. The electronic control unit80calculates the amount of the air passing through the air flow meter35, as a result, the amount of the air suctioned into the combustion chamber on the basis of the output value.

The air cleaner36is arranged in the intake pipe32on the upstream side of the air flow meter35. The air cleaner36clears the air passing therethrough.

The supercharging pressure sensor37is arranged in the intake passage30(in particular, the intake manifold31) downstream of the throttle valve33. The supercharging pressure sensor37is electrically connected to the interface85of the electronic control unit80.

The supercharging pressure sensor37outputs an output value corresponding to a pressure of the air surrounding the sensor (i.e. a pressure of the air in the intake manifold and suctioned into the combustion chamber). The electronic control unit80calculates the pressure of the air surrounding the supercharging pressure sensor37, that is, the pressure of the air suctioned into the combustion chamber (hereinafter, this pressure may be referred to as —supercharging pressure—) on the output value.

The supercharger60has a compressor61and an exhaust turbine62. The compressor61is arranged rotatably in the intake pipe32upstream of the intercooler34and downstream of the air flow meter35. The exhaust turbine62is arranged rotatably in the exhaust pipe42. These compressor61and exhaust turbine62are connected to each other via a shaft (not shown).

The exhaust turbine62is rotated by an energy of the exhaust gas passing therethrough. The rotation of the exhaust turbine62is transmitted to the compressor61via the shaft. That is, the compressor61is rotated by the rotation of the exhaust turbine62. Then, the air in the intake passage30downstream of the compressor61is compressed by the rotation of the compressor61.

As shown inFIG. 2, the supercharger60has a plurality of wing-shaped vanes63. The vanes63are arranged so as to surround the exhaust turbine62. In addition, the vanes63are arranged and radially equally spaced about a rotation center axis R1 of the exhaust turbine62. Each vane63can rotate about an axis R2 thereof.

Referring to a direction of the extension of each vane63(i.e. a direction shown by a symbol E inFIG. 2) as —extension direction— and referring to a line connecting the rotation center axis R1 of the exhaust turbine62and the turning axis R2 of the vane63to each other (i.e. a line shown by a symbol A inFIG. 2) as —base line—, each vane63can turn such that angles relating to all vanes63, each of which angles is defined between the extension direction E and the base line A corresponding thereto (hereinafter, this angle may be referred to as —vane opening degree—), are maintained equal to each other.

When each vane63is turned such that the vane opening degree decreases (i.e. a flow area defined between adjacent two vanes63decreases), a pressure in the exhaust passage40upstream of the exhaust turbine62increases. As a result, a flow rate of the exhaust gas supplied to the exhaust turbine62increases.

Thus, a rotation speed of the exhaust turbine62increases and as a result, a rotation speed of the compressor61increases. Thus, the degree of the compression of the air in the intake passage30by the compressor61increases. That is, when the vane opening degree decreases, the degree of the compression of the air in the intake passage30by the compressor61increases.

On the other hand, when the vane opening degree increases, the degree of the compression of the air in the intake passage30by the compressor61decreases.

An actuator for driving the vanes63so as to change the opening degree thereof is connected to the vanes63(hereinafter, this actuator may be referred to as —vane actuator—). The vane actuator is electrically connected to the interface85of the electronic control unit80. The electronic control unit80gives to the vane actuator, a control signal for driving the vane actuator to control the vane opening degree to a target vane opening degree.

The acceleration pedal depression amount sensor71is electrically connected to the interface85of the electronic control unit80. The acceleration pedal depression sensor71outputs an output value corresponding to a depression amount of an acceleration pedal70.

This output value is input into the electronic control unit80. The electronic control unit80calculates the depression amount of the acceleration pedal, as a result, a torque required for the engine on the basis of this output value.

The crank position sensor72is arranged adjacent to a crank shaft (not shown) of the engine. The crank position sensor72is electrically connected to the interface85of the electronic control unit80.

The crank position sensor72outputs an output value corresponding to a rotation phase of the crank shaft. This output value is input into the electronic control unit80. The electronic control unit80calculates an engine speed on the basis of this output value.

Next, a control of the fuel injector according to the first embodiment will be explained. In the first embodiment, appropriate fuel injection amounts depending on the depression amount of the acceleration pedal are previously obtained by an experiment, etc.

Then, these obtained fuel injection amounts are memorized in the electronic control unit as target fuel injection amounts TQ in the form of a map as a function of the depression amount Dac of the acceleration pedal as shown inFIG. 3(A).

During the engine operation, the target fuel injection amount TQ corresponding to the current acceleration pedal depression amount Dac is acquired from the map ofFIG. 3(A). Then, the command signal is given from the electronic control unit to the fuel injector so as to inject the fuel of the target fuel injection amount TQ from the fuel injector.

As shown inFIG. 3(A), the target fuel injection amount TQ increases as the acceleration pedal amount Dac increases.

Further, in the first embodiment, when the acceleration pedal depression amount Dac is zero, it is judged that a deceleration is requested for the engine and then, the target fuel injection amount TQ is set as zero. That is, at this time, no fuel is injected from the fuel injector and the fuel injection amount is zero. Hereinafter, this engine operation wherein the fuel injection amount is zero, may be referred to as —uninjection operation—.

Next, a control of the throttle valve according to the first embodiment will be explained. In the first embodiment, appropriate throttle valve opening degrees depending on the engine operation state are previously obtained by an experiment, etc. Then, these obtained throttle valve opening degree are memorized in the electronic control unit as target throttle valve opening degrees TDth in the form of a map as a function of the engine speed N and the engine load L as shown inFIG. 3(B).

During the engine operation, the target throttle valve opening degree TDth corresponding to the current engine speed N and the current load L is acquired. Then, the command signal is given from the electronic control unit for driving the throttle valve so as to control the throttle valve opening degree to this acquired target throttle valve opening degree TDth.

As shown inFIG. 3(B), as the engine speed N increases and as the engine load L increases, the target throttle valve opening degree TDth increases.

Next, a control of the vane according to the first embodiment will be explained. In the first embodiment, appropriate supercharging pressure depending on the engine operation state are previously obtained by an experiment, etc. Then, these obtained supercharging pressure are memorized in the electronic control unit as target supercharging pressure TPim in the form of a map as a function of the engine speed N and the engine load L as shown inFIG. 3(C).

During the engine operation, the target supercharging pressure TPim corresponding to the current engine speed N and the current load L is acquired from the map ofFIG. 3(C). Then, the vane actuator is feedback controlled by the electronic control unit to control the vane opening degree so as to control the actual supercharging pressure (this pressure is detected by the supercharging pressure sensor) to the aforementioned acquired target supercharging pressure TPim.

In particular, when the actual supercharging pressure is lower than the target supercharging pressure, the control signal for driving the vane actuator to drive the vanes so as to decrease the vane opening degree, is given from the electronic control unit to the vane actuator.

On the other hand, when the actual supercharging pressure is higher than the target supercharging pressure, the control signal for driving the vane actuator to drive the vanes so as to increase the vane opening degree, is given from the electronic control unit to the vane actuator.

In the map shown inFIG. 3(C), as the engine speed N increases and as the engine load L increases, the target supercharging pressure TPim increases.

Next, a vane feedback gain used in the control of the vane according to the first embodiment will be explained. In the first embodiment, the vane actuator is driven by the control signal given from the electronic control unit to the vane actuator.

In this regard, the degree of the driving of the vane by the vane actuator is determined on the basis of a deviation of the actual supercharging pressure relative to the target supercharging pressure (hereinafter, this deviation may be referred to as —supercharging pressure deviation—).

Then, a feedback gain (i.e. a vane feedback gain) for defining the manner of the reflection of the supercharging pressure deviation in a vane manipulation amount is used in this determination.

In this regard, in the first embodiment, a calculation expression for calculating the vane feedback gain by using a predetermined parameter, which gain increases a following property of the actual supercharging pressure relative to the target supercharging pressure (hereinafter, this property may be referred to as —target supercharging pressure following property—) to the maximum extent, is previously obtained (hereinafter, this expression may be referred to as —vane feedback gain calculation expression—) and this obtained calculation expression is memorized in the electronic control unit.

This vane feedback gain calculation expression calculates the vane feedback gain so as to calculate a manipulation amount such that when the control signal corresponding to the vane manipulation amount calculated on the basis of the supercharging pressure deviation is given to the vane actuator, a time for the actual supercharging pressure to converge on the target supercharging pressure is shorten to the maximum extent, an overshoot, in which the actual supercharging pressure becomes higher than the target supercharging pressure, decreases to the maximum extent and an undershoot, in which the actual supercharging pressure becomes lower than the target supercharging pressure, decreases to the maximum extent.

A supercharging pressure change delay time is included as a parameter in the vane feedback gain calculation expression.

In this regard, the supercharging pressure change delay time means —time until the supercharging pressure actually starts to change since the control signal for changing the vane opening degree by driving the vane actuator to drive the vane is given to the vane actuator—.

Then, in the first embodiment, during the engine operation, the supercharging pressure change delay time is measured (the detail of this measurement will be explained later), new vane feedback gain is calculated by applying this measured supercharging pressure change delay time to the vane feedback gain calculation expression and this calculated vane feedback gain is used in the calculation of the vane manipulation amount.

The vane feedback gain calculation expression of the first embodiment may be a calculation expression for calculating the vane feedback gain using the classical or modern control theory.

In this regard, in the case that the vane feedback gain calculation expression is a calculation expression for calculating the vane feedback gain by using the modern control theory and as one of the calculation expressions, a state equation expressed by the following equation 1 is used, as shown in the following equation 2, the aforementioned measured supercharging pressure change delay time Δt is reflected in the time relating to the vane opening degree Dv.

In the equations 1 and 2, “Pim(t)” is —supercharging pressure at the time t—, “Dv(t)” is —vane opening degree at the time t—, “Dv(t−Δt)” is —vane opening degree at the time t−Δt—, “A” is —constant matrix (or coefficient matrix) relating to the supercharging pressure— and “B” is —constant matrix (or coefficient matrix) relating to the vane opening degree.

There may be a single vane feedback gain or a plurality of vane feedback gains. For example, in the case that the feedback control of the vane actuator according to the first embodiment is the PID control (i.e. the proportional-integral-derivative control), three feedback gains such as the proportional gain, the integral gain and the derivative gain are the vane feedback gains.

Next, the measurement of the supercharging pressure change delay time according to the first embodiment will be explained. The control signal for driving the vane by a predetermined manipulation amount during the uninjection operation is given from the electronic control unit to the vane actuator.

Then, the time from the supply of the control signal to the vane actuator until the start of the change of the supercharging pressure is measured as the supercharging pressure change delay time. As explained above, new vane feedback gain is calculated by applying this measured supercharging pressure change delay time to the aforementioned vane feedback gain calculation expression.

The aforementioned predetermined manipulation amount (i.e. the amount of the driving of the vane for the measurement of the supercharging pressure change delay time during the uninjection operation) may be any amount as far as this manipulation amount is a manipulation amount which leads to the change of the supercharging pressure for sufficiently realizing the change of the supercharging pressure by the driving of the vane for the measurement of the supercharging pressure change delay time or may be a manipulation amount which decreases or increases the vane opening degree.

However, the pressure of the exhaust gas discharged from the combustion chamber decreases during the uninjection operation and therefore, the supercharging pressure also decreases.

Therefore, in the case that the aforementioned predetermined manipulation amount is a manipulation amount for increasing the vane opening degree (i.e. a manipulation amount for decreasing the supercharging pressure), it is difficult to judge if the decrease of the supercharging pressure is derived from the uninjection operation or from the driving of the vane for the measurement of the supercharging pressure change delay time.

Therefore, in order to realize the change of the supercharging pressure by the driving of the vane for the measurement of the supercharging pressure change delay time, in the case that the aforementioned predetermined manipulation amount is a manipulation amount for increasing the vane opening degree, it is preferred that the aforementioned predetermined manipulation amount is set as a manipulation amount having a relatively large absolute value.

Further, in the case that the aforementioned predetermined manipulation amount is a manipulation amount for decreasing the vane opening degree (i.e a manipulation amount for increasing the supercharging pressure), the absolute value of the aforementioned manipulation amount is relatively small and in the case that the increase of the supercharging pressure due to the driving of the vane according to the manipulation amount does not exceed the decrease of the supercharging pressure due to the uninjection operation, the supercharging pressure does not increase.

In this case, it is difficult to identify the time of the start of the change of the supercharging pressure by the influence of the driving of the vane for the measurement of the supercharging pressure change delay time.

Therefore, in order to identify the time of the start of the change of the supercharging pressure by the driving of the vane for the measurement of the supercharging pressure change delay time, it is preferred that the aforementioned predetermined manipulation amount is set as a manipulation amount having the large absolute value for at least increasing the supercharging pressure even when the aforementioned predetermined manipulation amount is a manipulation amount for decreasing the vane opening degree.

Further, even during the uninjection operation, the large change of the vane opening degree for the measurement of the supercharging pressure change delay time may not be preferred in the drivability point of view.

In this regard, compared with the case that the aforementioned predetermined manipulation amount is a manipulation amount for increasing the vane opening degree, a manipulation amount having a small absolute value can be employed as the aforementioned predetermined manipulation amount in the case that the aforementioned predetermined manipulation amount is a manipulation amount for decreasing the vane opening degree.

Therefore, in the drivability point of view, it is preferred that the aforementioned predetermined manipulation amount is set as a manipulation amount for decreasing the vane opening degree.

Further, in the case that a control for increasing or decreasing the vane opening degree is performed when the uninjection operation starts, in consideration of the transition of the supercharging pressure due to this control, the aforementioned predetermined manipulation amount should be set referring to the aforementioned description relating to the predetermined manipulation amount used in the driving of the vane for the measurement of the supercharging pressure change delay time.

Next, an advantage of using the supercharging pressure change delay time measured as explained above in the calculation of new vane feedback gain, will be explained.

In order to maintain the target supercharging pressure following property high, the control signal given to the vane actuator should be determined in consideration of the time until the supercharging pressure actually starts to change since the control signal for changing the operation state of the vane is given from the electronic control unit to the vane actuator (i.e. the supercharging pressure change delay time).

The pressure of the exhaust gas discharged from the combustion chamber changes depending on a combustion amount in the combustion chamber. In addition, the supercharging pressure is subject to the influence of the pressure of the exhaust gas discharged from the combustion chamber.

In this case, the time from the start of the driving of the vane actuator until the start of the change of the supercharging pressure (i.e. the supercharging pressure change delay time) changes depending on the combustion amount in the combustion chamber.

Then, an amount of the fuel supplied to the combustion chamber continuously changes depending on the requirement for the engine and therefore, the combustion amount in the combustion chamber also continuously changes.

Therefore, in the case that the supercharging pressure change delay time is measured when the combustion is generated in the combustion chamber, the influence of the combustion in the combustion chamber is reflected in the measured supercharging pressure change delay time.

Further, when an environment surrounding the engine (e.g. a temperature of a cooling water of the engine, a temperature of a lubricant oil of the engine, etc.) changes, the change property of the supercharging pressure changes.

In this regard, if the torque is produced by the combustion in the combustion chamber, the engine operation state changes and the supercharging pressure also changes by the influence of this change of the engine operation state.

Thus, the change of the supercharging pressure change delay time due to the change of the environment surrounding the engine as well as the change of the supercharging pressure change delay time due to a factor other than the change of the environment (i.e. the torque) are reflected in the supercharging pressure change delay time measured under the condition where the torque is produced.

Therefore, the supercharging pressure change delay time may not sufficient as the supercharging pressure change delay time to be considered for maintaining the target supercharging pressure following property high.

On the other hand, in the first embodiment, when no fuel is supplied to the combustion chamber, the supercharging pressure change delay time is measured. That is, when no combustion is generated in the combustion chamber, the supercharging pressure change delay time is measured.

Therefore, the thus measured supercharging pressure change delay time is sufficient as the supercharging pressure change delay time to be considered for maintaining the target supercharging pressure following property high.

Then, in the first embodiment, the thus measured supercharging pressure change delay time is considered in the calculation of the vane feedback gain.

Then, this vane feedback gain is used in the feedback control of the vane actuator and therefore, in the first embodiment, there is an advantage that the target supercharging pressure following property is maintained high.

Of course, according to the first embodiment, factors, which change the supercharging pressure responsiveness such as a temperature of the engine, the temperature of the cooling water of the engine, the temperature of the lubricant oil of the engine, the atmospheric pressure, a pressure of the exhaust gas in the exhaust passage downstream of the exhaust turbine and upstream of a catalyst in the case that the catalyst for purifying a particular component in the exhaust gas is arranged in the exhaust passage, a mechanical deterioration of the vane, are considered in order to maintain the target supercharging pressure following property.

Next, an example of a routine for performing the calculation of the vane feedback gain according to the first embodiment will be explained. This example of the routine is shown inFIG. 4. The routine ofFIG. 4is performed every a predetermined time has elapsed.

When the routine ofFIG. 4starts, first, at step100, it is judged if an uninjection operation flag Ffc is set (Ffc=1). In this regard, the uninjection operation flag Ffc is set by the input of “1” when the uninjection operation starts and is reset by the input of “0” when the uninjection operation ends.

At the step100, when it is judged that Ffc=1, that is, it is judged that the uninjection operation is performed, the routine proceeds to the step101.

On the other hand, when it is not judged that Ffc=1, that is, it is judged that the uninjection operation is not performed (in other words, a normal operation is performed), the routine ends directly. That is, in this case, the calculation of new vane feedback gain is not performed.

When it is judged that Ffc=1 at the step100and then, the routine proceeds to the step101, the control signal for driving the vane by a predetermined manipulation amount so as to decrease the vane opening degree is given from the electronic control unit to the vane actuator.

Next, at the step102, it is judged if the uninjection operation flag Ffc is set (Ffc=1), that is, it is judged if the uninjection operation is continued. In this regard, when it is judged that Ffc=1, the routine proceeds to the step103. On the other hand, when it is not judged that Ffc=1, the routine proceeds to the step106.

When it is judged that Ffc=1 at the step102, that is, it is judged that the uninjection operation is continued and then, the routine proceeds to the step103, a counter Tdly indicating the time having elapsed from the giving of the control signal from the electronic control unit to the vane actuator at the step101, that is, the supercharging pressure change delay time is counted up.

Next, at the step104, it is judged if a change amount ΔPim of the supercharging pressure is larger than zero (ΔPim>0).

In this regard, when it is judged that ΔPim>0 (i.e. it is judged that the supercharging pressure starts to increase), the routine proceeds to the step105.

On the other hand, when it is not judged that ΔPim>0, the routine returns to the step102and it is judged if the uninjection operation flag Ffc is set (Ffc=1). In this regard, when it is judged that Ffc=1, the routine proceeds to the step103and the counter Tdly is counted up.

That is, in this routine, until it is judged that ΔPim>0 at the step104, the routine proceeds to the step102and as far as it is judged that Ffc=1, the step103is performed repeatedly and the count up of the counter Tdly is continued.

When it is judged that ΔPim>0 at the step104, that is, it is judged that the supercharging pressure starts to increase and then, the routine proceeds to the step105, the vane feedback gain Kgain is calculated by applying the current counter Tdly to the vane feedback gain calculation expression.

Next, at the step106, the counter Tdly is cleared and then, the routine ends.

When it is not judged that Ffc=1 at the step102, that is, it is judged that the uninjection operation ends and then, the routine proceeds to the step106, the counter Tdly is cleared and then, the routine ends. That is, in this case, once the measurement of the supercharging pressure change delay time Tdly starts, this measurement is stopped since the uninjection operation ends.

Next, another embodiment of the control device of the engine of the invention (hereinafter, this embodiment may be referred to as —second embodiment—) will be explained. The engine which the control device of the second embodiment is applied, is the engine shown inFIG. 1.

The constitution of the second embodiment is the same as that of the first embodiment except for a part thereof and therefore, in the following explanation, mainly, the constitution of the second embodiment different from that of the first embodiment will be explained.

The vane feedback gain used in the control of the vane according to the second embodiment will be explained. In the second embodiment, similar to the first embodiment, the vane manipulation amount is determined on the basis of the supercharging pressure deviation.

Then, similar to the first embodiment, the vane feedback gain is used in this determination. Then, similar to the first embodiment, the vane feedback gain calculation expression is memorized in the electronic control unit.

The supercharging pressure change delay time and the supercharging pressure change rate at the fuel injection being performed being performed are included as parameters in the vane feedback gain calculation expression of the second embodiment.

In this regard, the supercharging pressure change delay time is the same as the —supercharging pressure change delay time— of the first embodiment.

Further, the supercharging pressure change rate at the fuel injection being performed means —rate of the supercharging pressure which changes by the influence of the combustion of the fuel when the fuel is injected from the fuel injector—.

Then, in the second embodiment, during the engine operation, the supercharging pressure change delay time is measured (the detail of this measurement will be explained later), the supercharging pressure change rate at the fuel injection being performed is calculated (the detail of this calculation will be explained later), new vane feedback gain is calculated by applying the measured supercharging pressure change delay time and the calculated supercharging pressure change rate at the fuel injection being performed to the vane feedback gain calculation expression and this calculated vane feedback gain is used in the calculation of the vane manipulation amount.

The vane feedback gain calculation expression of the second embodiment may be a calculation expression for calculating the vane feedback gain by using the classical or modern control theory.

In this regard, in the case that the vane feedback gain calculation expression is a calculation expression for calculating the vane feedback gain by using the modern control theory and as one of the calculation expressions, a state equation expressed by the following equation 3 is used, as shown in the following equation 4, the measured supercharging pressure change delay time Δt is reflected in the time relating to the vane opening degree Dv and the calculated supercharging pressure change rate at the fuel injection being performed is reflected in the constant matrix (or the coefficient matrix) C relating to the fuel injection amount.

In the equations 3 and 4, “Pim(t)” is —supercharging pressure at the time t—, “Dv(t)” is —vane opening degree at the time t—, “Dv(t−Δt)” is —vane opening degree at the time t−Δt—, “Q(t)” is —fuel injection amount at the time t—, “A” is —constant matrix (or coefficient matrix) relating to the supercharging pressure—, “B” is —constant matrix (or coefficient matrix) relating to the vane opening degree and “C” is —constant matrix (or coefficient matrix) relating to the fuel injection amount—.

Next, the measurement of the supercharging pressure change delay time and the calculation of the supercharging pressure change rate at the fuel injection being performed according to the second embodiment will be explained.

In the second embodiment, the control signal for driving the vane by a predetermined manipulation amount during the uninjection operation is given from the electronic control unit to the vane actuator.

Then, the time from the giving of the control signal to the vane actuator until the start of the change of the supercharging pressure is measured as the supercharging pressure change delay time. That is, similar to the first embodiment, the supercharging pressure change delay time is measured.

Further, in the second embodiment, when the uninjection operation is performed and the supercharging pressure change delay time is measured, the command signal for injecting the fuel of a minute amount from the fuel injector is given to the fuel injector.

At this time, the fuel injection amount is set as a small amount so as not to produce the torque in the engine by the combustion of the fuel.

Then, the change rate of the supercharging pressure at this time is calculated as the supercharging pressure change rate at the fuel injection being performed.

As explained above, new vane feedback gain is calculated by applying the thus measured supercharging pressure change delay time and the thus calculated supercharging pressure change rate at the fuel injection being performed to the vane feedback gain calculation expression.

Of course, when the fuel of the minute amount is injected from the fuel injector for the calculation of the supercharging pressure change rate at the fuel injection being performed and the influence of the combustion of the injected fuel remains in the supercharging pressure, the measurement of the supercharging pressure change delay time is not performed.

Further, the order of the performance of the measurement of the supercharging pressure change delay time and the calculation of the supercharging pressure change rate at the fuel injection being performed may be any order and these measurement and calculation may be performed during one uninjection operation and may be performed during the different uninjecton operations, respectively.

Next, an advantage of using the measured supercharging pressure change delay time and the calculated supercharging pressure change rate at the fuel injection being performed as explained above in the calculation of the vane feedback gain, will be explained.

In the second embodiment, there is the following advantage other than the advantage explained relating to the first embodiment. That is, when the operation state of the vane is changed, the supercharging pressure changes.

At this time, even when the change of the operation state of the vane is the same, the manner of the change of the supercharging pressure varies depending on the combustion amount in the combustion chamber.

Then, the fuel injection amount changes continuously depending on the requirement for the engine (e.g. depending on the depression amount of the acceleration pedal) and therefore, the combustion amount in the combustion chamber changes continuously.

On the other hand, in may cases, when the fuel is injected into the combustion chamber, the feedback control of the vane actuator is performed and therefore, if the feedback control of the vane actuator is performed not in consideration of the manner of the change of the supercharging pressure depending on the combustion amount in the combustion chamber, the target supercharging pressure following property decreases, compared with the case that the feedback control of the vane actuator is performed in consideration of the manner of the change of the supercharging pressure depending on the combustion amount in the combustion chamber.

On the other hand, when the combustion is generated in the combustion chamber so as not to produce the torque while the engine performs the uninjection operation, the supercharging pressure changes.

At this time, no torque is produced and therefore, the change rate of the supercharging pressure at this time is not subject to the influence of the torque.

That is, the change rate of the supercharging pressure at this time is subject only to the influence of the combustion in the combustion chamber and the environment surrounding the engine (e.g. the temperature of the cooling water of the engine, the temperature of the lubricant oil of the engine, etc.).

Therefore, if the change rate of the supercharging pressure at this time is calculated and then, the vane feedback gain is set in consideration of this calculated change rate of the supercharging pressure, the combustion in the combustion chamber is reflected in the vane feedback gain.

Thus, when the feedback control of the vane actuator is performed by the control signal determined using this vane feedback gain, even when the fuel injection to the combustion chamber is performed, the target supercharging pressure following property can be maintained high.

Next, an example of a routine for performing the calculation of the vane feedback gain according to the second embodiment will be explained. This example of the routine is shown inFIGS. 5 and 6. The routine ofFIGS. 5 and 6is performed every a predetermined time has elapsed.

When the routine ofFIGS. 5 and 6starts, first, at the step200ofFIG. 5, it is judged if the uninjection operation flag Ffc is set (Ffc=1). The uninjection operation flag Ffc is the same as the uninjection operation flag of the routine ofFIG. 4.

When it is judged that Ffc=1 at the step200, that is, it is judged that the uninjection operation is performed, the routine proceeds to the step201.

On the other hand, when it is not judged that Ffc=1, that is, it is judged that the uninjection operation is not performed (in other words, the normal operation is performed), the routine ends directly. That is, in this case, the calculation of new vane feedback gain is not performed.

When it is judged that Ffc=1 at the step200and then, the routine proceeds to the step201, it is judged if the data of the supercharging pressure change delay time Tdly stored in the electronic control unit at the step206of the routine performed before the routine is performed at this time is still stored in the electronic control unit.

In this regard, when it is judged that the data is still stored in the electronic control unit, the routine proceeds to the step208ofFIG. 6.

On the other hand, when it is not judged that the data is stored in the electronic control unit, the routine proceeds to the step202.

The data of the supercharging pressure change delay time Tdly stored in the electronic control unit is deleted from the electronic control unit by the performance of the step214ofFIG. 6.

When it is not judged that the data of the supercharging pressure change delay time Tdly is still stored in the electronic control unit at the step201and then, the routine proceeds to the step202, the control signal for driving the vane by a predetermined manipulation amount so as to decrease the vane opening degree is given from the electronic control unit to the vane actuator.

Next, at the step203, it is judged if the uninjection operation flag Ffc is set (Ffc=1), that is, it is judged if the uninjection operation is continued. In this regard, when it is judged that Ffc=1, the routine proceeds to the step204. On the other hand, when it is not judged that Ffc=1, the routine proceeds to the step207.

When it is judged that Ffc=1 at the step203, that is, it is judged that the uninjection operation is continued and then, the routine proceeds to the step204, the counter Tdly indicating the time having elapsed from the giving of the control signal from the electronic control unit to the vane actuator at the step202, that is, the supercharging pressure change delay time is counted up.

Next, at the step205, it is judged if the change amount ΔPim of the supercharging pressure is larger than zero (ΔPim>0). In this regard, when it is judged that ΔPim>0 (i.e. it is judged that the supercharging pressure starts to increase), the routine proceeds to the step206. On the other hand, when it is not judged that ΔPim>0, the routine returns to the step203and it is judged if the uninjection operation flag Ffc is set (Ffc=1).

In this regard, when it is judged that Ffc=1, the routine proceeds to the step204and the counter Tdly is counted up. That is, in this routine, until it is judged that ΔPim>0 at the step205, the routine proceeds to the step203and as far as it is judged that Ffc=1, the step204is performed repeatedly and the count up of the counter Tdly is continued.

When it is judged that ΔPim>0 at the step205, that is, it is judged that the supercharging pressure starts to increase and then, the routine proceeds to the step206, the counter Tdly at this time is stored in the electronic control unit.

Next, at the step208ofFIG. 6, it is judged if the uninjection operation flag Ffc is set (Ffc=1), that is, it is judged if the uninjection operation is continued. In this regard, when it is judged that Ffc=1, the routine proceeds to the step209. On the other hand, when it is not judged that Ffc=1, the routine ends directly.

When it is judged that Ffc=1 at the step208, that is, it is judged that the uninjection operation is continued and then, the routine proceeds to the step209, the command signal for injecting the fuel having the minute amount from the fuel injector is given to the fuel injector.

Next, at the step210, the change amount ΔPim of the supercharging pressure is calculated.

Next, at the step211, the change rate Spim of the supercharging pressure is calculated using the change amount ΔPim of the supercharging pressure calculated at the step210.

Next, at the step212, the counter Tdly stored in the electronic control unit is acquired.

Next, at the step213, the vane feedback gain Kgain is calculated by applying the change rate Spim of the supercharging pressure calculated at the step211and the counter Tdly acquired at the step212, that is, the supercharging pressure change delay time to the vane feedback gain calculation expression.

Next, at the step214, the counter Tdly stored in the electronic control unit is deleted and then, the routine ends.

When it is not judged that Ffc=1 at the step203ofFIG. 5, that is, it is judged that the uninjection operation ends and then, the routine proceeds to the step207, the counter Tdly is cleared and then, the routine ends. That is, in this case, once the measurement of the supercharging pressure change delay time Tdly starts, the measurement is stopped since the uninjection operation ends.

Next, further another embodiment of the control device of the engine of the invention (hereinafter, this embodiment may be referred to as —third embodiment—) will be explained. The engine which the control device of the third embodiment is applied, is shown inFIG. 7. InFIG. 7,50denotes an exhaust gas recirculation device (hereinafter, this device may be referred to as —EGR device—).

Comparing the engine shown inFIG. 7with the engine shown inFIG. 1, except that the engine shown inFIG. 7comprises the EGR device50and does not comprise the supercharger60, the constitution of the engine shown inFIG. 7is the same as that of the engine shown inFIG. 1and therefore, the detailed explanation thereof will be omitted.

The exhaust gas recirculation device (hereinafter, this device may be referred to as —EGR device—)50has an exhaust gas recirculation passage (hereinafter, this passage may be referred to as —EGR passage—)51, an exhaust gas recirculation control valve (hereinafter, this valve may be referred to as —EGR control valve—)52and an exhaust gas recirculation cooler (hereinafter, this cooler may be referred to as —EGR cooler—)53.

The EGR device50is a device for introducing to the intake passage30via the EGR passage51, the exhaust gas discharged from the combustion chamber to the exhaust passage40.

The EGR passage51is connected at its one end to the exhaust passage40(in particular, the exhaust manifold41) and is connected at its other end to the intake passage30(in particular, the intake manifold31). That is, the EGR passage51connects the exhaust passage40to the intake passage30.

The EGR control valve52is arranged in the EGR passage51. When an opening degree of the EGR control valve52(hereinafter, this degree may be referred to as —EGR control valve opening degree—) is changed, an amount of the exhaust gas passing through the EGR control valve52and as a result, the amount of the exhaust gas introduced to the intake passage30changes.

The EGR control valve52incorporates an actuator for changing its operation state (i.e. the EGR control valve opening degree) therein (hereinafter, this actuator may be referred to as —EGR control valve actuator—).

The EGR control valve actuator is electrically connected to the electronic control unit80. The electronic control unit80gives to the EGR control valve actuator, a control signal for driving the EGR control valve actuator so as to control the EGR control valve opening degree to the target EGR control valve opening degree.

Next, a control of the EGR control valve according to the third embodiment will be explained. The control of the fuel injector and the control of the throttle valve according to the third embodiment are the same as those according to the first embodiment and therefore, the detailed explanation thereof will be omitted.

Further, in the following explanation, “EGR rate” means —rate of the amount of the exhaust gas relative to the amount of the gas suctioned into the combustion chamber— and “EGR gas” means —exhaust gas introduced to the intake passage by the EGR device—.

In the third embodiment, appropriate EGR rates depending on the engine operation state are previously obtained by an experiment, etc. Then, these obtained EGR rates are memorized in the electronic control unit as target EGR rates TRegr in the form of a map as a function of the engine speed N and the engine load L as shown inFIG. 8.

During the engine operation, the target EGR rate TRegr corresponding to the current engine speed N and the current engine load L is acquired from the map ofFIG. 8.

Then, the EGR control valve actuator is feedback controlled by the electronic control unit to control the EGR control valve opening degree such that the actual EGR rate (this EGR rate will be explained later) corresponds to the aforementioned acquired target EGR rate TRegr.

In particular, when the actual EGR rate is smaller than the target EGR rate, the control signal for driving the EGR control valve actuator to drive the EGR control valve so as to increase the EGR control valve opening degree is given from the electronic control unit to the EGR control valve actuator.

On the other hand, when the actual EGR rate is larger than the target EGR rate, the control signal for driving the EGR control valve actuator to drive the EGR control valve so as to decrease the EGR control valve opening degree is given from the electronic control unit to the EGR control valve actuator.

In the map ofFIG. 8, as the engine speed N increases and as the engine load L increases, the target EGR rate TRege decreases.

Next, the calculation of the actual EGR rate according to the third embodiment will be explained. In the third embodiment, the actual EGR rate Regr is calculated according to the following equation 5. In the equation 5, “Gc” is —total amount of the gas suctioned into the combustion chamber (i.e. the mixture gas of the air and the exhaust gas) in one intake stroke— and “Ga” is —amount of the air supplied to the combustion chamber in one intake stroke—.

For example, the total amount of the gas suctioned into the combustion chamber in one intake stroke can be calculated from the parameters such as the engine speed and supercharging pressure and the amount of the air suctioned into the combustion chamber in one intake stroke can be calculated from the amount of the air detected by the air flow meter.

Next, an EGR control valve feedback gain used in the control of the EGR control valve according to the third embodiment will be explained.

In the third embodiment, the EGR control valve is driven by the control signal given from the electronic control unit to the EGR control valve actuator.

In this regard, the degree of the driving of the EGR control valve by the EGR control valve actuator (hereinafter, this degree may be referred to as —EGR control valve manipulation amount—) is determined on the basis of a deviation of the actual EGR rate relative to the target EGR rate (hereinafter, this deviation may be referred to as —EGR rate deviation—).

Then, a feedback gain (i.e. the EGR control valve feedback gain) for defining the manner of the reflection of the EGR rate deviation in the EGR control valve manipulation amount is used in this determination.

In this regard, in the third embodiment, a calculation expression for calculating the EGR control valve feedback gain by using a predetermined parameter, which gain increases a following property of the actual EGR rate relative to the target EGR rate (hereinafter, this property may be referred to as —target EGR rate following property—) to the maximum extent, is previously obtained (hereinafter, this expression may be referred to as —EGR control valve feedback gain calculation expression—) and this obtained calculation expression is memorized in the electronic control unit.

This EGR control valve feedback gain calculation expression calculates the EGR control valve feedback gain so as to calculate a manipulation amount such that when the control signal corresponding to the EGR control valve manipulation amount calculated on the basis of the EGR rate deviation is given to the EGR control valve actuator, a time for the actual EGR rate to converge on the target EGR rate is shorten to the maximum extent, an overshoot, in which the actual EGR rate becomes higher than the target EGR rate, decreases to the maximum extent and an undershoot, in which the actual EGR rate becomes lower than the target EGR rate, decreases to the maximum extent.

An EGR rate change delay time is included as a parameter in the EGR control valve feedback gain calculation expression.

In this regard, the EGR rate change delay time means —time until the EGR rate actually starts to change since the control signal for changing the EGR control valve opening degree by driving the EGR control valve actuator to drive the EGR control valve is given to the EGR control valve actuator—.

Then, in the third embodiment, during the engine operation, the EGR rate change delay time is measured (the detail of this measurement will be explained later), new EGR control valve feedback gain is calculated by applying this measured EGR rate change delay time to the EGR control valve feedback gain calculation expression and this calculated EGR control valve feedback gain is used in the calculation of the EGR control valve manipulation amount.

The EGR control valve feedback gain calculation expression of the third embodiment may be a calculation expression for calculating the vane feedback gain using the classical or modern control theory.

In this regard, in the case that the EGR control valve feedback gain calculation expression is a calculation expression for calculating the EGR control valve feedback gain by using the modern control theory and as one of the calculation expressions, a state equation expressed by the following equation 6 is used, as shown in the following equation 7, the aforementioned measured EGR rate change delay time Δt is reflected in the time relating to the EGR control valve opening degree Degr.

In the equations 6 and 7, “Regr(t)” is —EGR rate at the time t—, “Degr(t)” is —EGR control valve opening degree at the time t—, “Degr(t−Δt)” is —EGR control valve opening degree at the time t−Δt—, “A” is —constant matrix (or coefficient matrix) relating to the EGR rate— and “B” is —constant matrix (or coefficient matrix) relating to the EGR control valve opening degree.

There may be a single EGR control valve feedback gain or a plurality of EGR control valve feedback gains. For example, in the case that the feedback control of the EGR control valve actuator according to the third embodiment is the PID control (i.e. the proportional-integral-derivative control), three feedback gains such as the proportional gain, the integral gain and the derivative gain are the EGR control valve feedback gains.

Next, the measurement of the EGR rate change delay time according to the third embodiment will be explained.

The control signal for driving the EGR control valve by a predetermined manipulation amount during the uninjection operation is given from the electronic control unit to the EGR control valve actuator.

Then, the time from the supply of the control signal to the EGR control valve actuator until the start of the change of the EGR rate is measured as the EGR rate change delay time.

As explained above, new EGR control valve feedback gain is calculated by applying this measured EGR rate change delay time to the aforementioned EGR control valve feedback gain calculation expression.

The aforementioned predetermined manipulation amount (i.e. the amount of the driving of the EGR control valve for the measurement of the EGR rate change delay time during the uninjection operation) may be any amount as far as this manipulation amount is a manipulation amount which leads to the change of the EGR rate for sufficiently realizing the change of the EGR rate by the driving of the EGR control valve for the measurement of the EGR rate change delay time or may be a manipulation amount which decreases or increases the EGR control valve opening degree.

However, the pressure of the exhaust gas discharged from the combustion chamber decreases during the uninjection operation and therefore, the EGR rate also decreases.

Therefore, in the case that the aforementioned predetermined manipulation amount is a manipulation amount for decreasing the EGR control valve opening degree (i.e. a manipulation amount for decreasing the EGR rate), it is difficult to judge if the decrease of the EGR rate is derived from the uninjection operation or from the driving of the EGR control valve for the measurement of the EGR rate change delay time.

Therefore, in order to realize the change of the EGR rate by the driving of the EGR control valve for the measurement of the EGR rate change delay time, in the case that the aforementioned predetermined manipulation amount is a manipulation amount for decreasing the EGR control valve opening degree, it is preferred that the aforementioned predetermined manipulation amount is set as a manipulation amount having a relatively large absolute value.

Further, in the case that the aforementioned predetermined manipulation amount is a manipulation amount for increasing the EGR control valve opening degree (i.e a manipulation amount for increasing the EGR rate), the absolute value of the aforementioned manipulation amount is relatively small and in the case that the increase of the EGR rate due to the driving of the EGR control valve according to the manipulation amount does not exceed the decrease of the EGR rate due to the uninjection operation, the EGR rate does not increase.

In this case, it is difficult to identify the time of the start of the change of the EGR rate by the influence of the driving of the EGR control valve for the measurement of the EGR rate change delay time.

Therefore, in order to identify the time of the start of the change of the EGR rate by the driving of the EGR control valve for the measurement of the EGR rate change delay time, it is preferred that the aforementioned predetermined manipulation amount is set as a manipulation amount having the large absolute value for at least increasing the EGR rate even when the aforementioned predetermined manipulation amount is a manipulation amount for increasing the EGR control valve opening degree.

Further, even during the uninjection operation, the large change of the EGR control valve opening degree for the measurement of the EGR rate change delay time may not be preferred in the drivability point of view.

In this regard, compared with the case that the aforementioned predetermined manipulation amount is a manipulation amount for decreasing the EGR control valve opening degree, a manipulation amount having a small absolute value can be employed as the aforementioned predetermined manipulation amount in the case that the aforementioned predetermined manipulation amount is a manipulation amount for increasing the EGR control valve opening degree.

Therefore, in the drivability point of view, it is preferred that the aforementioned predetermined manipulation amount is set as a manipulation amount for increasing the EGR control valve opening degree.

Further, in the case that a control for increasing or decreasing the EGR control valve opening degree is performed when the uninjection operation starts, in consideration of the transition of the EGR rate due to this control, the aforementioned predetermined manipulation amount should be set referring to the aforementioned description relating to the predetermined manipulation amount used in the driving of the EGR control valve for the measurement of the EGR rate change delay time.

Next, an advantage of using the EGR rate change delay time measured as explained above in the calculation of new EGR control valve feedback gain, will be explained.

In order to maintain the target EGR rate following property high, the control signal given to the EGR control valve actuator should be determined in consideration of the time until the EGR rate actually starts to change since the control signal for changing the operation state of the EGR control valve is given from the electronic control unit to the EGR control valve actuator (i.e. the EGR rate change delay time).

The pressure of the exhaust gas discharged from the combustion chamber changes depending on a combustion amount in the combustion chamber. In addition, the EGR rate is subject to the influence of the pressure of the exhaust gas discharged from the combustion chamber.

In this case, the time from the start of the driving of the EGR control valve actuator until the start of the change of the EGR rate (i.e. the EGR rate change delay time) changes depending on the combustion amount in the combustion chamber.

Then, the amount of the fuel supplied to the combustion chamber continuously changes depending on the requirement for the engine and therefore, the combustion amount in the combustion chamber also continuously changes.

Therefore, in the case that the EGR rate change delay time is measured when the combustion is generated in the combustion chamber, the influence of the combustion in the combustion chamber is reflected in the measured EGR rate change delay time.

Further, when an environment surrounding the engine (e.g. the temperature of a cooling water of the engine, the temperature of the lubricant oil of the engine, etc.) changes, the change property of the EGR rate changes.

In this regard, if the torque is produced by the combustion in the combustion chamber, the engine operation state changes and the supercharging pressure also changes by the influence of this change of the engine operation state.

Thus, the change of the EGR rate change delay time due to the change of the environment surrounding the engine as well as the change of the EGR rate change delay time due to a factor other than the change of the environment (i.e. the torque) are reflected in the EGR rate change delay time measured under the condition where the torque is produced.

Therefore, the EGR rate change delay time may not sufficient as the EGR rate change delay time to be considered for maintaining the target EGR rate following property high.

On the other hand, in the third embodiment, when no fuel is supplied to the combustion chamber, the EGR rate change delay time is measured. That is, when no combustion is generated in the combustion chamber, the EGR rate change delay time is measured.

Therefore, the thus measured EGR rate change delay time is sufficient as the EGR rate change delay time to be considered for maintaining the target EGR rate following property high.

Then, in the third embodiment, the thus measured EGR rate change delay time is considered in the calculation of the EGR control valve feedback gain.

Then, this EGR control valve feedback gain is used in the feedback control of the EGR control valve actuator and therefore, in the third embodiment, there is an advantage that the target EGR rate following property is maintained high.

Of course, according to the third embodiment, factors, which change the EGR rate responsiveness such as the temperature of the engine, the temperature of the cooling water of the engine, the temperature of the lubricant oil of the engine, the atmospheric pressure, the pressure of the exhaust gas in the exhaust passage upstream of a catalyst in the case that the catalyst for purifying a particular component in the exhaust gas is arranged in the exhaust passage, a mechanical deterioration of the EGR control valve, are considered in order to maintain the target EGR rate following property.

Next, an example of a routine for performing the calculation of the EGR control valve feedback gain according to the third embodiment will be explained. This example of the routine is shown inFIG. 9. The routine ofFIG. 9is performed every a predetermined time has elapsed.

When the routine ofFIG. 9starts, first, at step300, it is judged if the uninjection operation flag Ffc is set (Ffc=1). The uninjection operation flag Ffc is the same as the uninjection operation flag of the routine ofFIG. 4.

When it is judged that Ffc=1 at the step300, that is, it is judged that the uninjection operation is performed, the routine proceeds to the step301.

On the other hand, when it is not judged that Ffc=1, that is, it is judged that the uninjection operation is not performed (in other words, the normal operation is performed), the routine ends directly. That is, in this case, the calculation of new EGR control valve feedback gain is not performed.

When it is judged that Ffc=1 at the step300and then, the routine proceeds to the step301, the control signal for driving the EGR control valve by a predetermined manipulation amount so as to decrease the EGR control valve opening degree is given from the electronic control unit to the EGR control valve actuator.

Next, at the step302, it is judged if the uninjection operation flag Ffc is set (Ffc=1), that is, it is judged if the uninjection operation is continued. In this regard, when it is judged that Ffc=1, the routine proceeds to the step303. On the other hand, when it is not judged that Ffc=1, the routine proceeds to the step306.

When it is judged that Ffc=1 at the step302, that is, it is judged that the uninjection operation is continued and then, the routine proceeds to the step303, a counter Tdly indicating the time having elapsed from the giving of the control signal from the electronic control unit to the EGR control valve actuator at the step301, that is, the EGR rate change delay time is counted up.

Next, at the step304, it is judged if a change amount ΔRegr of the EGR rate is smaller than zero (ΔRegr<0).

In this regard, when it is judged that ΔRegr<0 (i.e. it is judged that the EGR rate starts to decrease), the routine proceeds to the step305.

On the other hand, when it is not judged that ΔRegr<0, the routine returns to the step302and it is judged if the uninjection operation flag Ffc is set (Ffc=1).

In this regard, when it is judged that Ffc=1, the routine proceeds to the step303and the counter Tdly is counted up. That is, in this routine, until it is judged that ΔRegr<0 at the step304, the routine proceeds to the step302and as far as it is judged that Ffc=1, the step303is performed repeatedly and the count up of the counter Tdly is continued.

When it is judged that ΔRegr<0 at the step304, that is, it is judged that the EGR rate starts to decrease and then, the routine proceeds to the step305, the EGR control valve feedback gain Kgain is calculated by applying the current counter Tdly to the EGR control valve feedback gain calculation expression.

Next, at the step306, the counter Tdly is cleared and then, the routine ends.

When it is not judged that Ffc=1 at the step302, that is, it is judged that the uninjection operation ends and then, the routine proceeds to the step306, the counter Tdly is cleared and then, the routine ends. That is, in this case, once the measurement of the EGR rate change delay time Tdly starts, this measurement is stopped since the uninjection operation ends.

Next, another embodiment of the control device of the engine of the invention (hereinafter, this embodiment may be referred to as —fourth embodiment—) will be explained.

The engine which the control device of the fourth embodiment is applied, is the engine shown inFIG. 7.

The constitution of the fourth embodiment is the same as that of the third embodiment except for a part thereof and therefore, in the following explanation, mainly, the constitution of the fourth embodiment different from that of the third embodiment will be explained.

The EGR control valve feedback gain used in the control of the EGR control valve according to the fourth embodiment will be explained.

In the fourth embodiment, similar to the third embodiment, the EGR control valve manipulation amount is determined on the basis of the EGR rate deviation. Then, similar to the third embodiment, the EGR control valve feedback gain is used in this determination.

Then, similar to the third embodiment, the EGR control valve feedback gain calculation expression is memorized in the electronic control unit.

The EGR rate change delay time and the EGR rate change rate at the fuel injection being performed are included as parameters in the EGR control valve feedback gain calculation expression of the fourth embodiment.

In this regard, the EGR rate change delay time is the same as the —EGR rate change delay time— of the third embodiment.

Further, the EGR rate change rate at the fuel injection being performed means —rate of the EGR rate which changes by the influence of the combustion of the fuel when the fuel is injected from the fuel injector—.

Then, in the fourth embodiment, during the engine operation, the EGR rate change delay time is measured (the detail of this measurement will be explained later), the EGR rate change rate at the fuel injection being performed is calculated (the detail of this calculation will be explained later), new EGR control valve feedback gain is calculated by applying the measured EGR rate change delay time and the calculated EGR rate change rate at the fuel injection being performed to the EGR control valve feedback gain calculation expression and this calculated EGR control valve feedback gain is used in the calculation of the EGR control valve manipulation amount.

The EGR control valve feedback gain calculation expression of the fourth embodiment may be a calculation expression for calculating the EGR control valve feedback gain by using the classical or modern control theory.

In this regard, in the case that the EGR control valve feedback gain calculation expression is a calculation expression for calculating the EGR control valve feedback gain by using the modern control theory and as one of the calculation expressions, a state equation expressed by the following equation 8 is used, as shown in the following equation 9, the measured EGR rate change delay time Δt is reflected in the time relating to the EGR control valve opening degree Degr and the calculated EGR rate change rate at the fuel injection being performed is reflected in the constant matrix (or the coefficient matrix) C relating to the fuel injection amount.

In the equations 8 and 9, “Regr(t)” is —EGR rate at the time t—, “Degr(t)” is —EGR control valve opening degree at the time t—, “Degr(t−Δt)” is —EGR control valve opening degree at the time t−Δt—, “Q(t)” is —fuel injection amount at the time t—, “A” is —constant matrix (or coefficient matrix) relating to the EGR rate—, “B” is —constant matrix (or coefficient matrix) relating to the EGR control valve opening degree and “C” is —constant matrix (or coefficient matrix) relating to the fuel injection amount—.

Next, the measurement of the EGR rate change delay time and the calculation of the EGR rate change rate at the fuel injection being performed according to the fourth embodiment will be explained.

In the fourth embodiment, the control signal for driving the EGR control valve by a predetermined manipulation amount during the uninjection operation is given from the electronic control unit to the EGR control valve actuator.

Then, the time from the giving of the control signal to the EGR control valve actuator until the start of the change of the EGR rate is measured as the EGR rate change delay time. That is, similar to the third embodiment, the EGR rate change delay time is measured.

Further, in the fourth embodiment, when the uninjection operation is performed and the EGR rate change delay time is measured, the command signal for injecting the fuel of a minute amount from the fuel injector is given to the fuel injector.

At this time, the fuel injection amount is set as a small amount so as not to produce the torque in the engine by the combustion of the fuel.

Then, the change rate of the EGR rate at this time is calculated as the EGR rate change rate at the fuel injection being performed.

As explained above, new EGR rate feedback gain is calculated by applying the thus measured EGR rate change delay time and the thus calculated EGR rate change rate at the fuel injection being performed to the EGR control valve feedback gain calculation expression.

Of course, when the fuel of the minute amount is injected from the fuel injector for the calculation of the EGR rate change rate at the fuel injection being performed and the influence of the combustion of the injected fuel remains in the supercharging pressure, the measurement of the EGR rate change delay time is not performed.

Further, the order of the performance of the measurement of the EGR rate change delay time and the calculation of the EGR rate change rate at the fuel injection being performed may be any order and these measurement and calculation may be performed during one uninjection operation and may be performed during the different uninjecton operations, respectively.

Next, an advantage of using the measured EGR rate change delay time and the calculated EGR rate change rate at the fuel injection being performed as explained above in the calculation of the EGR control valve feedback gain, will be explained.

In the second embodiment, there is the following advantage other than the advantage explained relating to the first embodiment.

In the fourth embodiment, there is the following advantage other than the advantage explained relating to the third embodiment. That is, when the operation state of the EGR control valve is changed, the EGR rate changes.

At this time, even when the change of the operation state of the EGR control valve is the same, the manner of the change of the EGR rate varies depending on the combustion amount in the combustion chamber.

Then, the fuel injection amount changes continuously depending on the requirement for the engine (e.g. depending on the depression amount of the acceleration pedal) and therefore, the combustion amount in the combustion chamber changes continuously.

On the other hand, in may cases, when the fuel is injected into the combustion chamber, the feedback control of the EGR control valve actuator is performed and therefore, if the feedback control of the EGR control valve actuator is performed not in consideration of the manner of the change of the EGR rate depending on the combustion amount in the combustion chamber, the target EGR rate following property decreases, compared with the case that the feedback control of the EGR control valve actuator is performed in consideration of the manner of the change of the EGR rate depending on the combustion amount in the combustion chamber.

On the other hand, when the combustion is generated in the combustion chamber so as not to produce the torque while the engine performs the uninjection operation, the EGR rate changes.

At this time, no torque is produced and therefore, the change rate of the EGR rate at this time is not subject to the influence of the torque. That is, the change rate of the EGR rate at this time is subject only to the influence of the combustion in the combustion chamber.

Therefore, if the change rate of the EGR rate at this time is calculated and then, the EGR control valve feedback gain is set in consideration of this calculated change rate of the EGR rate, the combustion in the combustion chamber is reflected in the EGR control valve feedback gain.

Thus, when the feedback control of the EGR control valve actuator is performed by the control signal determined using this EGR control valve feedback gain, even when the fuel injection to the combustion chamber is performed, the target EGR rate following property can be maintained high.

Next, an example of a routine for performing the calculation of the EGR control valve feedback gain according to the fourth embodiment will be explained. This example of the routine is shown inFIGS. 10 and 11. The routine ofFIGS. 10 and 11is performed every a predetermined time has elapsed.

When the routine ofFIGS. 10 and 11starts, first, at the step400ofFIG. 10, it is judged if the uninjection operation flag Ffc is set (Ffc=1). The uninjection operation flag Ffc is the same as the uninjection operation flag of the routine ofFIG. 4.

When it is judged that Ffc=1 at the step400, that is, it is judged that the uninjection operation is performed, the routine proceeds to the step401.

On the other hand, when it is not judged that Ffc=1, that is, it is judged that the uninjection operation is not performed (in other words, the normal operation is performed), the routine ends directly. That is, in this case, the calculation of new EGR control valve feedback gain is not performed.

When it is judged that Ffc=1 at the step400and then, the routine proceeds to the step401, it is judged if the data of the EGR rate change delay time Tdly stored in the electronic control unit at the step406of the routine performed before the routine is performed at this time is still stored in the electronic control unit.

In this regard, when it is judged that the data is still stored in the electronic control unit, the routine proceeds to the step408ofFIG. 11.

On the other hand, when it is not judged that the data is stored in the electronic control unit, the routine proceeds to the step402.

The data of the EGR rate change delay time Tdly stored in the electronic control unit is deleted from the electronic control unit by the performance of the step414ofFIG. 11.

When it is not judged that the data of the EGR rate change delay time Tdly is still stored in the electronic control unit at the step401and then, the routine proceeds to the step402, the control signal for driving the EGR control valve by a predetermined manipulation amount so as to decrease the EGR control valve opening degree is given from the electronic control unit to the EGR control valve actuator.

Next, at the step403, it is judged if the uninjection operation flag Ffc is set (Ffc=1), that is, it is judged if the uninjection operation is continued. In this regard, when it is judged that Ffc=1, the routine proceeds to the step404. On the other hand, when it is not judged that Ffc=1, the routine proceeds to the step407.

When it is judged that Ffc=1 at the step403, that is, it is judged that the uninjection operation is continued and then, the routine proceeds to the step404, the counter Tdly indicating the time having elapsed from the giving of the control signal from the electronic control unit to the EGR control valve actuator at the step402, that is, the EGR rate change delay time is counted up.

Next, at the step405, it is judged if the change amount ΔRegr of the EGR rate is smaller than zero (ΔRegr<0). In this regard, when it is judged that ΔRegr<0 (i.e. it is judged that the EGR rate starts to decrease), the routine proceeds to the step406. On the other hand, when it is not judged that ΔRegr<0, the routine returns to the step403and it is judged if the uninjection operation flag Ffc is set (Ffc=1).

In this regard, when it is judged that Ffc=1, the routine proceeds to the step404and the counter Tdly is counted up. That is, in this routine, until it is judged that ΔRegr<0 at the step405, the routine proceeds to the step403and as far as it is judged that Ffc=1, the step404is performed repeatedly and the count up of the counter Tdly is continued.

When it is judged that ΔRegr<0 at the step405, that is, it is judged that the EGR rate starts to decrease and then, the routine proceeds to the step406, the counter Tdly at this time is stored in the electronic control unit.

Next, at the step408ofFIG. 11, it is judged if the uninjection operation flag Ffc is set (Ffc=1), that is, it is judged if the uninjection operation is continued. In this regard, when it is judged that Ffc=1, the routine proceeds to the step409. On the other hand, when it is not judged that Ffc=1, the routine ends directly.

When it is judged that Ffc=1 at the step408, that is, it is judged that the uninjection operation is continued and then, the routine proceeds to the step409, the command signal for injecting the fuel having the minute amount from the fuel injector is given to the fuel injector.

Next, at the step410, the change amount ΔRegr of the EGR rate is calculated.

Next, at the step411, the change rate Sregr of the EGR rate is calculated using the change amount ΔRegr of the EGR rate calculated at the step410.

Next, at the step412, the counter Tdly stored in the electronic control unit is acquired.

Next, at the step413, the EGR control valve feedback gain Kgain is calculated by applying the change rate Sregr of the EGR rate calculated at the step411and the counter Tdly acquired at the step412, that is, the EGR rate change delay time to the EGR control valve feedback gain calculation expression.

Next, at the step414, the counter Tdly stored in the electronic control unit is deleted and then, the routine ends.

When it is not judged that Ffc=1 at the step403ofFIG. 10, that is, it is judged that the uninjection operation ends and then, the routine proceeds to the step407, the counter Tdly is cleared and then, the routine ends. That is, in this case, once the measurement of the EGR rate change delay time Tdly starts, the measurement is stopped since the uninjection operation ends.

Next, further another embodiment of the control device of the engine of the invention (hereinafter, this embodiment may be referred to as —fifth embodiment—) will be explained.

The engine which the control device of the fifth embodiment is applied, is shown inFIG. 12. Comparing the engine shown inFIG. 12with the engine shown inFIG. 1, except that the engine shown inFIG. 12comprises the EGR device50, the constitution of the engine shown inFIG. 12is the same as that of the engine shown inFIG. 1and therefore, the detailed explanation thereof will be omitted.

The constitution of the EGR device50of the engine shown inFIG. 12is the same as that of the EGR device50of the engine shown inFIG. 7and therefore, the detailed explanation thereof will be omitted.

Further, the controls of the fuel injector, the throttle valve and vanes according to the fifth embodiment are the same as those according to the first embodiment and the control of the EGR control valve is the same as that according to the third embodiment and therefore, the detailed explanations thereof will be omitted.

The vane feedback gain used in the control of the vane according to the fifth embodiment will be explained.

In the fifth embodiment, similar to the first embodiment, the vane manipulation amount is determined on the basis of the supercharging pressure deviation. Then, a feedback gain (i.e. the vane feedback gain) for defining the manner of the reflection of the supercharging pressure deviation in the vane manipulation amount is used in this determination.

In this regard, in the fifth embodiment, a calculation expression for calculating the vane feedback gain by using a predetermined parameter, which gain increases the target supercharging pressure following property to the maximum extent, is previously obtained (hereinafter, this expression may be referred to as —vane feedback gain calculation expression—) and this obtained calculation expression is memorized in the electronic control unit.

This vane feedback gain calculation expression calculates the vane feedback gain so as to calculate the vane manipulation amount such that when the control signal corresponding to the vane manipulation amount calculated on the basis of the supercharging pressure deviation is given to the vane actuator, a time for the actual supercharging pressure to converge on the target supercharging pressure is shorten to the maximum extent, an overshoot, in which the actual supercharging pressure becomes higher than the target supercharging pressure, decreases to the maximum extent and an undershoot, in which the actual supercharging pressure becomes lower than the target supercharging pressure, decreases to the maximum extent.

The supercharging pressure change delay time at the vane being manipulated and the supercharging pressure change delay time at the EGR control valve being manipulated are included as parameters in the vane feedback gain calculation expression.

In this regard, the supercharging pressure change delay time at the vane being manipulated means —time until the supercharging pressure actually starts to change since the control signal for changing the vane opening degree by driving the vane actuator to drive the vane under the condition where the EGR control valve opening degree is maintained constant, is given to the vane actuator— and the supercharging pressure change delay time at the EGR control valve being manipulated means —time until the supercharging pressure actually starts to change since the control signal for changing the EGR control valve opening degree by driving the EGR control valve actuator to drive the EGR control valve under the condition where the vane opening degree is maintained constant, is given to the EGR control valve actuator—.

Then, in the fifth embodiment, during the engine operation, these supercharging pressure change delay times are measured (the detail of this measurement will be explained later), new vane feedback gain is calculated by applying these measured supercharging pressure change delay times to the vane feedback gain calculation expression and this calculated vane feedback gain is used in the calculation of the vane manipulation amount.

Next, an EGR control valve feedback gain used in the control of the EGR control valve according to the fifth embodiment will be explained.

In the fifth embodiment, similar to the third embodiment, the EGR control valve manipulation amount is determined on the basis of the EGR rate deviation.

Then, a feedback gain (i.e. the EGR control valve feedback gain) for defining the manner of the reflection of the EGR rate deviation in the EGR control valve manipulation amount is used in this determination.

In this regard, in the fifth embodiment, a calculation expression for calculating the EGR control valve feedback gain by using a predetermined parameter, which gain increases the target EGR rate following property to the maximum extent, is previously obtained (hereinafter, this expression may be referred to as —EGR control valve feedback gain calculation expression—) and this obtained calculation expression is memorized in the electronic control unit.

This EGR control valve feedback gain calculation expression calculates the EGR control valve feedback gain so as to calculate the EGR control valve manipulation amount such that when the control signal corresponding to the EGR control valve manipulation amount calculated on the basis of the EGR rate deviation is given to the EGR control valve actuator, a time for the actual EGR rate to converge on the target EGR rate is shorten to the maximum extent, an overshoot, in which the actual EGR rate becomes higher than the target EGR rate, decreases to the maximum extent and an undershoot, in which the actual EGR rate becomes lower than the target EGR rate, decreases to the maximum extent.

The EGR control rate change delay time at the EGR control valve being manipulated and the EGR rate change delay time at the vane being manipulated are included as parameters in the EGR control valve feedback gain calculation expression.

In this regard, the EGR rate change delay time at the EGR control valve being manipulated means —time until the EGR rate actually starts to change since the control signal for changing the EGR control valve opening degree by driving the EGR control valve actuator to drive the EGR control valve under the condition where the vane opening degree is maintained constant, is given to the EGR control valve actuator— and the EGR rate change delay time at the vane being manipulated means —time until the supercharging pressure actually starts to change since the control signal for changing the vane opening degree by driving the vane actuator to drive the vane under the condition where the EGR control valve opening degree is maintained constant, is given to the vane actuator—.

Then, in the fifth embodiment, during the engine operation, these EGR rate change delay times are measured (the detail of this measurement will be explained later), new EGR control valve feedback gain is calculated by applying these measured EGR rate change delay times to the EGR control valve feedback gain calculation expression and this calculated EGR control valve feedback gain is used in the calculation of the EGR control valve manipulation amount.

Next, the measurement of the supercharging pressure change delay time and the EGR rate change delay time according to the fifth embodiment will be explained.

The control signal for driving the vane by a predetermined manipulation amount under the condition where the EGR control valve opening degree is maintained constant during the uninjection operation is given from the electronic control unit to the vane actuator.

Then, the time from the supply of the control signal to the vane actuator until the start of the change of the supercharging pressure is measured as the supercharging pressure change delay time at the vane being manipulated and the time from the supply of the control signal to the vane actuator until the start of the change of the EGR rate is measured as the EGR rate change delay time at the vane being manipulated.

Further, the control signal for driving the EGR control valve by a predetermined manipulation amount under the condition where the vane opening degree is maintained constant during the uninjection operation is given from the electronic control unit to the EGR control valve actuator.

Then, the time from the supply of the control signal to the EGR control valve actuator until the start of the change of the EGR rate is measured as the EGR rate change delay time at the EGR control valve being manipulated and the time from the supply of the control signal to the EGR control valve actuator until the start of the change of the supercharging pressure is measured as the supercharging pressure change delay time at the EGR control valve being manipulated.

As explained above, new vane feedback gain is calculated by applying these measured supercharging pressure change delay times at the vane being manipulated and at the EGR control valve being manipulated to the aforementioned vane feedback gain calculation expression and new EGR control valve feedback gain is calculated by applying these measured EGR rate change delay times at the vane being manipulated and at the EGR control valve being manipulated to the aforementioned EGR control valve feedback gain calculation expression.

The order of the performance of the measurement of the supercharging pressure change delay time at the vane being manipulated and the EGR rate change delay time at the vane being manipulated and the measurement of the EGR rate change delay time at the EGR control valve being manipulated and the supercharging pressure change delay time at the EGR control valve being manipulated may be performed during one uninjection operation and may be performed during the different uninjecton operations, respectively.

Next, an advantage of using the measured two supercharging pressure change delay times as explained above in the calculation of the vane feedback gain, will be explained.

In order to maintain the target supercharging pressure following property high, the control signal given to the vane actuator should be determined in consideration of the time until the supercharging pressure actually starts to change since the control signal for changing the operation state of the vane is given from the electronic control unit to the vane actuator (i.e. the supercharging pressure change delay time at the vane being manipulated).

In addition, when the EGR rate changes, the supercharging pressure changes and therefore, in order to maintain the target supercharging pressure following property high, the control signal given to the vane actuator should be determined in consideration of the time until the supercharging pressure actually starts to change since the control signal for changing the operation state of the EGR control valve is given from the electronic control unit to the EGR control valve actuator (i.e. the supercharging pressure change delay time at the EGR control valve being manipulated).

The pressure of the exhaust gas discharged from the combustion chamber changes depending on a combustion amount in the combustion chamber. In addition, the supercharging pressure is subject to the influence of the pressure of the exhaust gas discharged from the combustion chamber.

In this case, the time from the start of the driving of the vane actuator until the start of the change of the supercharging pressure changes depending on the combustion amount in the combustion chamber.

Of course, the time from the start of the driving of the EGR control valve actuator until the start of the change of the supercharging pressure changes depending on the combustion amount in the combustion chamber.

Then, the amount of the fuel supplied to the combustion chamber continuously changes depending on the requirement for the engine and therefore, the combustion amount in the combustion chamber also continuously changes.

Therefore, in the case that the supercharging pressure change delay time is measured when the combustion is generated in the combustion chamber, the influence of the combustion in the combustion chamber is reflected in the measured supercharging pressure change delay time.

Further, when an environment surrounding the engine (e.g. the temperature of the cooling water of the engine, the temperature of the lubricant oil of the engine, etc.) changes, the change property of the supercharging pressure changes.

In this regard, if the torque is produced by the combustion in the combustion chamber, the engine operation state changes and the supercharging pressure also changes by the influence of this change of the engine operation state.

Thus, the change of the supercharging pressure change delay time due to the change of the environment surrounding the engine as well as the change of the supercharging pressure change delay time due to a factor other than the change of the environment (i.e. the torque) are reflected in the supercharging pressure change delay time measured under the condition where the torque is produced.

Therefore, the supercharging pressure change delay time may not sufficient as the supercharging pressure change delay time to be considered for maintaining the target supercharging pressure following property high.

On the other hand, in the fifth embodiment, when no fuel is supplied to the combustion chamber, the supercharging pressure change delay time at the operation state of the vane being changed (i.e. the supercharging pressure change delay time at the vane being manipulated) and the supercharging pressure change delay time at the operation state of the EGR control valve being changed (i.e. the supercharging pressure change delay time at the EGR control valve being manipulated) are measured.

That is, when no combustion is generated in the combustion chamber, the supercharging pressure change delay times at the vane being manipulated and at the EGR control valve being manipulated are measured.

Therefore, the thus measured supercharging pressure change delay times are sufficient as the supercharging pressure change delay times to be considered for maintaining the target supercharging pressure following property high.

Then, in the fifth embodiment, the thus measured two supercharging pressure change delay times are considered in the calculation of the vane feedback gain.

Then, this vane feedback gain is used in the feedback control of the vane actuator and therefore, in the fifth embodiment, there is an advantage that the target supercharging pressure following property is maintained high in the case that the engine comprises means for controlling the control amounts (i.e. the supercharging pressure and the EGR rate) which influence each other such as the supercharger and the EGR device.

Of course, according to the fifth embodiment, by considering the supercharging pressure change delay time in the calculation of the vane feedback gain, factors, which change the supercharging pressure responsiveness such as a temperature of the engine, the temperature of the lubricant oil of the engine, the atmospheric pressure, a pressure of the exhaust gas in the exhaust passage downstream of the exhaust turbine and upstream of a catalyst in the case that the catalyst for purifying a particular component in the exhaust gas is arranged in the exhaust passage, a mechanical deterioration of the vane, the mechanical deterioration of the EGR control valve, etc., are considered in order to maintain the target supercharging pressure following property.

Next, an advantage of using the two supercharging pressure change delay times measured as explained above in the calculation of new vane feedback gain, will be explained.

In order to maintain the target EGR rate following property high, the control signal given to the EGR control valve actuator should be determined in consideration of the time until the EGR rate actually starts to change since the control signal for changing the operation state of the EGR control valve is given from the electronic control unit to the EGR control valve actuator (i.e. the EGR rate change delay time at the EGR control valve being manipulated).

In addition, when the supercharging pressure changes, the EGR rate changes and therefore, in order to maintain the target EGR rate following property high, the control signal given to the EGR control valve actuator should be determined in consideration of the time until the EGR rate actually starts to change since the control signal for changing the operation state of the vane is given from the electronic control unit to the vane actuator (i.e. the EGR rate change delay time at the vane being manipulated).

The pressure of the exhaust gas discharged from the combustion chamber changes depending on the combustion amount in the combustion chamber. In addition, the EGR rate is subject to the influence of the pressure of the exhaust gas discharged from the combustion chamber.

In this case, the time from the start of the driving of the EGR control valve actuator until the start of the change of the EGR rate changes depending on the combustion amount in the combustion chamber.

Of course, the time from the start of the driving of the vane actuator until the start of the change of the EGR rate changes depending on the combustion amount in the combustion chamber.

Then, the amount of the fuel supplied to the combustion chamber continuously changes depending on the requirement for the engine and therefore, the combustion amount in the combustion chamber also continuously changes.

Therefore, in the case that the EGR rate change delay time is measured when the combustion is generated in the combustion chamber, the influence of the combustion in the combustion chamber is reflected in the measured EGR rate change delay time.

Further, when an environment surrounding the engine (e.g. the temperature of the cooling water of the engine, the temperature of the lubricant oil of the engine, etc.) changes, the change property of the EGR rate changes.

In this regard, if the torque is produced by the combustion in the combustion chamber, the engine operation state changes and the EGR rate also changes by the influence of this change of the engine operation state.

Thus, the change of the EGR rate change delay time due to the change of the environment surrounding the engine as well as the change of the EGR rate change delay time due to a factor other than the change of the environment (i.e. the torque) are reflected in the EGR rate change delay time measured under the condition where the torque is produced.

Therefore, the EGR rate change delay time may not sufficient as the EGR rate change delay time to be considered for maintaining the target EGR rate following property high.

On the other hand, in the fifth embodiment, when no fuel is supplied to the combustion chamber, the EGR rate change delay time at the operation state of the EGR control valve being changed (i.e. the EGR rate change delay time at the EGR control valve being manipulated) and the EGR rate change delay time at the operation state of the vane being changed (i.e. the EGR rate change delay time at the vane being manipulated) are measured.

That is, when no combustion is generated in the combustion chamber, the EGR rate change delay times at the EGR control valve being manipulated and at the vane being manipulated are measured.

Therefore, the thus measured EGR rate change delay times are sufficient as the EGR rate change delay times to be considered for maintaining the target EGR rate following property high.

Then, in the fifth embodiment, the thus measured two EGR rate change delay times are considered in the calculation of the EGR control valve feedback gain.

Then, this EGR control valve feedback gain is used in the feedback control of the EGR control valve actuator and therefore, in the fifth embodiment, there is an advantage that the target EGR rate following property is maintained high in the case that the engine comprises means for controlling the control amounts (i.e. the supercharging pressure and the EGR rate) which influence each other such as the supercharger and the EGR device.

Of course, according to the fifth embodiment, by considering the EGR rate change delay time in the calculation of the EGR control valve feedback gain, factors, which change the EGR rate responsiveness such as the temperature of the engine, the temperature of the lubricant oil of the engine, the atmospheric pressure, the pressure of the exhaust gas in the exhaust passage downstream of the exhaust turbine and upstream of a catalyst in the case that the catalyst for purifying a particular component in the exhaust gas is arranged in the exhaust passage, a mechanical deterioration of the vane, the mechanical deterioration of the EGR control valve, etc., are considered in order to maintain the target EGR rate following property.

Next, an example of a routine for performing the calculation of the vane feedback gain and the EGR control valve feedback gain according to the fifth embodiment will be explained. This example of the routine is shown inFIGS. 13 to 16. The routine ofFIGS. 13 to 16is performed every a predetermined time has elapsed.

When the routine ofFIGS. 13 to 16starts, first, at step500, it is judged if the uninjection operation flag Ffc is set (Ffc=1). The uninjection operation flag Ffc is the same as the uninjection operation flag of the routine ofFIG. 4.

When it is judged that Ffc=1 at the step500, that is, it is judged that the uninjection operation is performed, the routine proceeds to the step501.

On the other hand, when it is not judged that Ffc=1, that is, it is judged that the uninjection operation is not performed (in other words, the normal operation is performed), the routine ends directly. That is, in this case, the calculation of new vane feedback gain and new EGR control valve feedback gain is not performed.

When it is judged that Ffc=1 at the step500and then, the routine proceeds to the step501, it is judged if the data of the supercharging pressure change delay time Tpvdly at the vane being manipulated stored in the electronic control unit at the step507of the routine performed before the routine is performed at this time and the data of the EGR rate change delay time Trvdly at the vane being manipulated stored in the electronic control unit at the step511of the routine performed before the routine is performed at this time are still stored in the electronic control unit.

In this regard, when it is judged that the data is still stored in the electronic control unit, the routine proceeds to the step516ofFIG. 15.

On the other hand, when it is not judged that the data is stored in the electronic control unit, the routine proceeds to the step502.

The data of the supercharging pressure change delay time Tpvdly at the vane being manipulated and the EGR rate change delay time Trvdly at the vane being manipulated stored in the electronic control unit are deleted from the electronic control unit by the performance of the step532ofFIG. 16.

When it is not judged that the data of the supercharging pressure change delay time Tpvdly at the vane being manipulated and the EGR rate change delay time Trvdly at the vane being manipulated are still stored in the electronic control unit at the step501and then, the routine proceeds to the step502, the control signal for driving the vane by a predetermined manipulation amount so as to decrease the vane opening degree is given from the electronic control unit to the vane actuator.

Next, at the step503, it is judged if the uninjection operation flag Ffc is set (Ffc=1), that is, it is judged if the uninjection operation is continued. In this regard, when it is judged that Ffc=1, the routine proceeds to the step504. On the other hand, when it is not judged that Ffc=1, the routine proceeds to the step509.

When it is not judged that Ffc=1 at the step503and then, the routine proceeds to the step509, the counter Tpvdly indicating the time having elapsed from the giving of the control signal from the electronic control unit to the vane actuator at the step502, that is, the supercharging pressure change delay time at the vane being manipulated (hereinafter, this counter may be referred to as —supercharging pressure change delay time counter at the vane being manipulated) and the counter Trvdly indicating the time having elapsed from the giving of the control signal from the electronic control unit to the vane actuator at the step502, that is, the EGR rate change delay time at the vane being manipulated (hereinafter, this counter may be referred to as —EGR rate change delay time counter at the vane being manipulated), are cleared and then, the routine ends.

When it is judged that Ffc=1 at the step503, that is, it is judged that the uninjection operation is continued and then, the routine proceeds to the step504, it is judged if a supercharging pressure change delay time stored flag at the vane being manipulated Fpv is set (Fpv=1).

In this regard, the supercharging pressure change delay time stored flag at the vane being manipulated Fpv is set at the step508when the supercharging pressure change delay time counter at the vane being manipulated Tpvdly is stored as the supercharging pressure change delay time at the vane being manipulated in the electronic control unit at the step507and is reset at the step533when the supercharging pressure change delay time at the vane being manipulated Tpvdly stored in the electronic control unit at the step532is deleted.

At the step504, when it is judged that Fpv=1, the routine proceeds to the step510ofFIG. 14.

On the other hand, when it is not judged that Fpv=1, the routine proceeds to the step505.

When it is not judged that Fpv=1 at the step504and then, the routine proceeds to the step505, the supercharging pressure change delay time counter at the vane being manipulated Tpvdly is counted up.

Next, at the step506, it is judged if a change amount ΔPim of the supercharging pressure is larger than zero (ΔPim>0). In this regard, when it is judged that ΔPim>0, the routine proceeds to the step507. On the other hand, when it is not judged that ΔPim>0, the routine returns to the step510ofFIG. 14.

When it is judged that ΔPim>0 at the step506and then, the routine proceeds to the step507, the supercharging pressure change delay time counter at the vane being manipulated Tpvdly at this time is stored as the supercharging pressure change delay time at the vane being manipulated in the electronic control unit.

Next, at the step508, the supercharging pressure change delay time stored flag at the vane being manipulated Fpv is set.

When the routine proceeds to the step509ofFIG. 14following the step508or when it is judged that Fpv=1 at the step504and then, the routine proceeds to the step509ofFIG. 14or when it is not judged that ΔPim>0 at the step506and then, the routine proceeds to the step509ofFIG. 14, it is judged if an EGR rate change delay time stored flag at the vane being manipulated Fry is set (Frv=1).

In this regard, the EGR rate change delay time stored flag at the vane being manipulated Fry is set at the step514when the EGR rate change delay time counter at the vane being manipulated Trvdly is stored as the EGR rate change delay time at the vane being manipulated in the electronic control unit at the step513and is reset at the step533when the EGR rate change delay time counter at the vane being manipulated Tpvdly stored in the electronic control unit at the step532is deleted.

At the step510, when it is judged that Frv=1, the routine proceeds to the step515. On the other hand, when it is not judged that Frv=1, the routine proceeds to the step511.

When it is not judged that Frv=1 at the step510and then, the routine proceeds to the step511, the EGR rate change delay time counter at the vane being manipulated Trvdly is counted up.

Next, at the step512, it is judged if a change amount ΔRegr of the EGR rate is larger than zero (ΔRegr>0). In this regard, when it is judged that ΔRegr>0, the routine proceeds to the step513. On the other hand, when it is not judged that ΔRegr>0, the routine returns to the step515.

When it is judged that ΔRegr>0 at the step512and then, the routine proceeds to the step513, the EGR rate change delay time counter at the vane being manipulated Trvdly at this time is stored as the EGR rate change delay time at the vane being manipulated in the electronic control unit.

Next, at the step514, the EGR rate change delay time stored flag at the vane being manipulated Fry is set.

When the routine proceeds to the step515following the step514or when it is judged that Frv=1 at the step510and then, the routine proceeds to the step515or when it is not judged that ΔRegr>0 at the step512and then, the routine proceeds to the step515, it is judged if the supercharging pressure change delay time stored flag at the vane being manipulated Fpv is set (Fpv=1) and the EGR rate change delay time stored flag at the vane being manipulated Fry is set (Frv=1).

In this regard, when it is judged that Fpv=1 and Frv=1, the routine proceeds to the step516ofFIG. 15.

On the other hand, when it is not judged that Fpv=1 and Frv=1, the routine proceeds to the step503ofFIG. 13. That is, in this routine, while the uninjection operation is continued, the steps503to505are performed repeatedly until the measurement of the supercharging pressure change delay time at the vane being manipulated and the EGR rate change delay time at the vane being manipulated are completed.

When it is judged that Fpv=1 and Frv=1 at the step515and then, the routine proceeds to the step516ofFIG. 15or when it if judged that the data of the supercharging pressure change delay time Tpvdly at the vane being manipulated Tpvdly and the EGR rate change delay time at the vane being manipulated Trvdly are still stored in the electronic control unit at the step501ofFIG. 13and then, the routine proceeds to the step516ofFIG. 15, the control signal for driving the EGR control valve by a predetermined manipulation amount so as to decrease the EGR control valve opening degree is given from the electronic control unit to the EGR control valve actuator.

Next, at the step517, it is judged if the uninjection operation flag Ffc is set (Ffc=1), that is, it is judged if the uninjection operation is continued. In this regard, when it is judged that Ffc=1, the routine proceeds to the step518. On the other hand, when it is not judged that Ffc=1, the routine proceeds to the step522.

When it is not judged that Ffc=1 at the step517and then, the routine proceeds to the step523, the counter Tpedly indicating the time having elapsed from the giving of the control signal from the electronic control unit to the EGR control valve actuator at the step516, that is, the supercharging pressure change delay time at the EGR control valve being manipulated (hereinafter, this counter may be referred to as —supercharging pressure change delay time counter at the EGR control valve being manipulated) and the counter Tredly indicating the time having elapsed from the giving of the control signal from the electronic control unit to the vane actuator at the step516, that is, the EGR rate change delay time at the EGR control valve being manipulated (hereinafter, this counter may be referred to as —EGR rate change delay time counter at the EGR control valve being manipulated), are cleared and then, the routine ends.

When it is judged that Ffc=1 at the step517, that is, it is judged that the uninjection operation is continued and then, the routine proceeds to the step518, it is judged if a supercharging pressure change delay time stored flag at the EGR control valve being manipulated Fpe is set (Fpe=1).

In this regard, the supercharging pressure change delay time stored flag at the EGR control valve being manipulated Fpe is set at the step522when the supercharging pressure change delay time counter at the EGR control valve being manipulated Tpedly is stored as the supercharging pressure change delay time at the EGR control valve being manipulated in the electronic control unit at the step521and is reset at the step533when the supercharging pressure change delay time at the EGR control valve being manipulated Tpedly stored in the electronic control unit at the step532is deleted.

At the step518, when it is judged that Fpe=1, the routine proceeds to the step524ofFIG. 16. On the other hand, when it is not judged that Fpe=1, the routine proceeds to the step519.

When it is not judged that Fpe=1 at the step518and then, the routine proceeds to the step519, the supercharging pressure change delay time counter at the EGR control valve being manipulated Tpedly is counted up.

Next, at the step520, it is judged if the change amount ΔPim of the supercharging pressure is smaller than zero (ΔPim<0). In this regard, when it is judged that ΔPim<0, the routine proceeds to the step521. On the other hand, when it is not judged that ΔPim<0, the routine returns to the step524ofFIG. 16.

When it is judged that ΔPim<0 at the step520and then, the routine proceeds to the step521, the supercharging pressure change delay time counter at the EGR control valve being manipulated Tpedly at this time is stored as the supercharging pressure change delay time at the EGR control valve being manipulated in the electronic control unit.

Next, at the step522, the supercharging pressure change delay time stored flag at the EGR control valve being manipulated Fpe is set.

When the routine proceeds to the step524ofFIG. 16following the step522or when it is judged that Fpe=1 at the step518and then, the routine proceeds to the step524ofFIG. 16or when it is not judged that ΔPim<0 at the step520and then, the routine proceeds to the step524ofFIG. 16, it is judged if an EGR rate change delay time stored flag at the EGR control valve being manipulated Fre is set (Fre=1).

In this regard, the EGR rate change delay time stored flag at the EGR control valve being manipulated Fre is set at the step528when the EGR rate change delay time counter at the EGR control valve being manipulated Tredly is stored as the EGR rate change delay time at the EGR control valve being manipulated in the electronic control unit at the step527and is reset at the step533when the EGR rate change delay time counter at the EGR control valve being manipulated Tpedly stored in the electronic control unit at the step532is deleted.

At the step524, when it is judged that Fre=1, the routine proceeds to the step529. On the other hand, when it is not judged that Fre=1, the routine proceeds to the step525.

When it is not judged that Fre=1 at the step524and then, the routine proceeds to the step525, the EGR rate change delay time counter at the EGR control valve being manipulated Tredly is counted up.

Next, at the step526, it is judged if the change amount ΔRegr of the EGR rate is smaller than zero (ΔRegr<0). In this regard, when it is judged that ΔRegr<0, the routine proceeds to the step527. On the other hand, when it is not judged that ΔRegr<0, the routine returns to the step529.

When it is judged that ΔRegr<0 at the step526and then, the routine proceeds to the step527, the EGR rate change delay time counter at the EGR control valve being manipulated Tredly at this time is stored as the EGR rate change delay time at the EGR control valve being manipulated in the electronic control unit.

Next, at the step526, the EGR rate change delay time stored flag at the EGR control valve being manipulated Fre is set.

When the routine proceeds to the step529following the step528or when it is judged that Fre=1 at the step524and then, the routine proceeds to the step529or when it is not judged that ΔRegr<0 at the step526and then, the routine proceeds to the step529, it is judged if the supercharging pressure change delay time stored flag at the EGR control valve being manipulated Fpe is set (Fpe=1) and the EGR rate change delay time stored flag at the EGR control valve being manipulated Fre is set (Fre=1).

In this regard, when it is judged that Fpe=1 and Fre=1, the routine proceeds to the step530.

On the other hand, when it is not judged that Fpe=1 and Fre=1, the routine proceeds to the step517ofFIG. 15. That is, in this routine, while the uninjection operation is continued, the steps517to529are performed repeatedly until the measurement of the supercharging pressure change delay time at the EGR control valve being manipulated and the EGR rate change delay time at the EGR control valve being manipulated are completed.

When it is judged that Fpe=1 and Fre=1 at the step529and then, the routine proceeds to the step530, the supercharging pressure change delay time at the vane being manipulated Tpvdly, the supercharging pressure change delay time at the EGR control valve being manipulated Tpedly, the EGR rate change delay time at the vane being manipulated Trvdly and the EGR rate change delay time at the EGR control valve being manipulated Tredly stored in the electronic control unit are acquired.

Next, at the step531, the vane feedback gain Kvgain is calculated by applying the supercharging pressure change delay times at the vane being manipulated and at the EGR control valve being manipulated Tpvdly and Tpedly acquired at the step530to the vane feedback gain calculation expression and the EGR control valve feedback gain Kegain is calculated by applying the EGR rate change delay times at the vane being manipulated and at the EGR control valve being manipulated Trvdly and Tredly acquired at the step530to the EGR control valve feedback gain calculation expression.

Next, at the step532, the supercharging pressure change delay times at the vane being manipulated and at the EGR control valve being manipulated Tpvdly and Tpedly and the EGR rate change delay times at the vane being manipulated and at the EGR control valve being manipulated Trvdly and Tredly stored in the electronic control unit are deleted.

Next, at the step533, the supercharging pressure change delay time stored flag at the vane being manipulated Fpv, the EGR rate change delay time stored flag at the vane being manipulated Fry, the supercharging pressure change delay time stored flag at the EGR control valve being manipulated Fpe and the EGR rate change delay time stored flag Fre at the EGR control valve being manipulated Fre are reset and then, the routine ends.

Next, further another embodiment of the control device of the engine of the invention (hereinafter, this embodiment may be referred to as —sixth embodiment—) will be explained. The engine which the control device of the sixth embodiment is applied, is the engine shown inFIG. 12.

The constitution of the sixth embodiment is the same as that of the fifth embodiment except for a part thereof and therefore, in the following explanation, mainly, the constitution of the sixth embodiment different from that of the fifth embodiment will be explained.

The vane feedback gain used in the control of the vane according to the sixth embodiment and the EGR control valve feedback gain used in the control of the EGR control valve according to the sixth embodiment will be explained.

In the sixth embodiment, similar to the fifth embodiment, the vane manipulation amount is determined on the basis of the supercharging pressure deviation. Then, the vane feedback gain is used in this determination.

In this regard, similar to the fifth embodiment, the vane feedback gain calculation expression is memorized in the electronic control unit.

Further, in the sixth embodiment, similar to the fifth embodiment, the EGR control valve manipulation amount is determined on the basis of the EGR rate deviation. Then, similar to the fifth embodiment, the EGR control valve feedback gain is used in this determination.

In this regard, similar to the fifth embodiment, the EGR control valve feedback gain calculation expression is memorized in the electronic control unit.

Then, the supercharging pressure change delay time at the vane being manipulated, the supercharging pressure change delay time at the EGR control valve being manipulated and a supercharging pressure change rate at the fuel injection being performed are included as parameters in the vane feedback gain calculation expression.

In this regard, the supercharging pressure change delay time at the vane being manipulated is the same as —supercharging pressure change delay time at the vane being manipulated— of the fifth embodiment and the supercharging pressure change delay time at the EGR control valve being manipulated is the same as —supercharging pressure change delay time at the EGR control valve being manipulated— of the fifth embodiment.

Further, the supercharging pressure change rate at the fuel injection being performed is the same as —supercharging pressure change rate at the fuel injection being performed— of the second embodiment.

Then, in the sixth embodiment, during the engine operation, these supercharging pressure change delay times at the vane being manipulated and the EGR control valve being manipulated are measured (the detail of this measurement will be explained later), the supercharging pressure change rate at the fuel injection being performed is calculated (the detail of this calculation will be explained later), new vane feedback gain is calculated by applying these measured supercharging pressure change delay times and this calculated supercharging pressure change rate at the fuel injection being performed to the vane feedback gain calculation expression and this calculated vane feedback gain is used in the calculation of the vane manipulation amount.

The EGR control rate change delay time at the EGR control valve being manipulated, the EGR rate change delay time at the vane being manipulated and the EGR rate change rate at the fuel injection being performed are included as parameters in the EGR control valve feedback gain calculation expression of the sixth embodiment.

In this regard, the EGR rate change delay time at the EGR control valve being manipulated is the same as —EGR rate change delay time at the EGR control valve being manipulated— of the fifth embodiment and the EGR rate change delay time at the vane being manipulated is the same as —EGR rate change delay time at the vane being manipulated— of the fifth embodiment.

Further, the EGR rate change rate at the fuel injection being performed is the same as —EGR rate change rate at the fuel injection being performed— of the fourth embodiment.

Then, in the sixth embodiment, during the engine operation, these EGR rate change delay times at the EGR control valve being manipulated and the vane being manipulated are measured (the detail of this measurement will be explained later), the EGR rate change rate at the fuel injection being performed is calculated (the detail of this calculation will be explained later), new EGR control valve feedback gain is calculated by applying these measured EGR rate change delay times and this calculated EGR rate change rate at the fuel injection being performed to the EGR control valve feedback gain calculation expression and this calculated EGR control valve feedback gain is used in the calculation of the EGR control valve manipulation amount.

Next, the measurement of the supercharging pressure change delay time the EGR rate change delay time and the calculation of the supercharging pressure change rate and the EGR rate change rate at the fuel injection being performed according to the sixth embodiment will be explained.

In the sixth embodiment, the control signal for driving the vane by a predetermined manipulation amount under the condition where the EGR control valve opening degree is maintained constant during the uninjection operation is given from the electronic control unit to the vane actuator.

Then, the time from the supply of the control signal to the vane actuator until the start of the change of the supercharging pressure is measured as the supercharging pressure change delay time at the vane being manipulated and the time from the supply of the control signal to the vane actuator until the start of the change of the EGR rate is measured as the EGR rate change delay time at the vane being manipulated.

Further, in the sixth embodiment, the control signal for driving the EGR control valve by a predetermined manipulation amount under the condition where the vane opening degree is maintained constant during the uninjection operation is given from the electronic control unit to the EGR control valve actuator.

Then, the time from the supply of the control signal to the EGR control valve actuator until the start of the change of the EGR rate is measured as the EGR rate change delay time at the EGR control valve being manipulated and the time from the supply of the control signal to the EGR control valve actuator until the start of the change of the supercharging pressure is measured as the supercharging pressure change delay time at the EGR control valve being manipulated.

Further, in the sixth embodiment, when the uninjection operation is performed and the measurement of the supercharging pressure change delay time and the EGR rate change delay time at the vane being manipulated and the EGR rate change delay time and the supercharging pressure change delay time at the EGR control valve being manipulated is not performed, the command signal for injecting the fuel having a minute amount from the fuel injector is given to the fuel injector.

At this time, the fuel injection amount is set as a small amount so as not to produce the torque in the engine by the combustion of the fuel.

Then, the change rate of the supercharging pressure at this time is calculated as the supercharging pressure change rate at the fuel injection being performed and the change rate of the EGR rate at this time is calculated as the EGR rate change rate at the fuel injection being performed.

As explained above, new vane feedback gain is calculated by applying the thus measured two supercharging pressure change delay times and the thus calculated supercharging pressure change rate at the fuel injection being performed to the vane feedback gain calculation expression and new EGR control valve feedback gain is calculated by applying the thus measured two EGR rate change delay times and the thus calculated EGR rate change rate at the fuel injection being performed to the EGR control valve feedback gain calculation expression.

Of course, when the fuel of the minute amount is injected from the fuel injector for the calculation of the supercharging pressure change rate at the fuel injection being performed, the influence of the combustion of the injected fuel remains in the supercharging pressure and the EGR rate, the fuel of the minute amount is injected from the fuel injector for the calculation of the EGR rate change rate at the fuel injection being performed and the influence of the combustion of the injected fuel remains in the EGR rate and the supercharging pressure rate, the measurement of the supercharging pressure change delay time and the EGR rate change delay time at the vane being manipulated and the EGR rate change delay time and the supercharging pressure change delay time at the EGR control valve being manipulated is not performed.

Further, the order of the performance of the measurement of the supercharging pressure change delay time and the EGR rate change delay time at the vane being manipulated, the measurement of the EGR rate change delay time and the supercharging pressure change delay time at the EGR control valve being manipulated and the calculation of the supercharging pressure change rate and the EGR rate change rate at the fuel injection being performed may be any order and these measurement and calculation may be performed during one uninjection operation and may be performed during the different uninjecton operations, respectively.

According to the sixth embodiment, by using the supercharging pressure change delay times and the calculated supercharging pressure change rate at the fuel injection being performed in the calculation of new vane feedback gain, for the same reasons as those explained relating to the second and fifth embodiments, the target supercharging pressure following property can be maintained high even when the injection of the fuel to the combustion chamber, in the case that the engine comprises means for controlling the control amounts (i.e. the supercharging pressure and the EGR rate) which influence each other such as the supercharger and the EGR device.

According to the sixth embodiment, by using the EGR rate change delay times and the calculated EGR rate change rate at the fuel injection being performed in the calculation of new EGR control valve feedback gain, for the same reasons as those explained relating to the fourth and fifth embodiments, the target EGR rate following property can be maintained high even when the injection of the fuel to the combustion chamber, in the case that the engine comprises means for controlling the control amounts (i.e. the supercharging pressure and the EGR rate) which influence each other such as the supercharger and the EGR device.

Next, an example of a routine for performing the calculation of the vane feedback gain and the EGR control valve feedback gain according to the sixth embodiment will be explained. This example of the routine is shown inFIGS. 17 to 21. The routine ofFIGS. 17 to 21is performed every a predetermined time has elapsed.

The steps600to629,632and633of the routine ofFIGS. 17 to 21are the same as the steps500to529,532and533of the routine ofFIGS. 13 to 16and therefore, the explanation of these steps is omitted.

When it is judged that Fpe=1 and Fre=1 at the step629ofFIG. 20and then, the routine proceeds to the step629A ofFIG. 21, it is judged if the uninjection operation flag Ffc is set (Ffc=1), that is, it is judged if the uninjection operation is continued.

In this regard, when it is judged that Ffc=1, the routine proceeds to the step620B. On the other hand, when it is not judged that Ffc=1, the routine ends directly.

When it is judged that Ffc=1 at the step629A and then, the routine proceeds to the step629B, the command signal for injecting the fuel having the minute amount from the fuel injector is given to the fuel injector.

Next, at the step629C, the change amount ΔPim of the supercharging pressure and the change amount ΔRegr of the EGR rate are calculated.

Next, at the step629D, the change rate Spim of the supercharging pressure is calculated using the change amount ΔPim of the supercharging pressure calculated at the step629C and the change rate Sregr of the EGR rate is calculated using the change amount ΔRegr of the EGR rate calculated at the step629C.

Next, at the step630, the supercharging pressure change delay time at the vane being manipulated Tpvdly, the supercharging pressure change delay time at the EGR control valve being manipulated Tpedly, the EGR rate change delay time at the vane being manipulated Trvdly and the EGR rate change delay time at the EGR control valve being manipulated Tredly stored in the electronic control unit are acquired.

Next, at the step631, the vane feedback gain Kvgain is calculated by applying the supercharging pressure change delay times at the vane being manipulated and at the EGR control valve being manipulated Tpvdly and Tpedly acquired at the step630and the supercharging pressure change rate Spim calculated at the step629D to the vane feedback gain calculation expression and the EGR control valve feedback gain Kegain is calculated by applying the EGR rate change delay times at the vane being manipulated and at the EGR control valve being manipulated Trvdly and Tredly acquired at the step630and the EGR rate change rate Sregr calculated at the step629D to the EGR control valve feedback gain calculation expression.

In the above-explained embodiments, only when the uninjection operation starts and the supercharging pressure is equal to or higher than a predetermined pressure, the measurement of the supercharging pressure change delay time or the EGR rate change delay time may be performed.

That is, when the uninjection operation starts and the supercharging pressure is lower than the predetermined pressure, the measurement of the supercharging pressure change delay time or the EGR rate change delay time may not be performed.

This has the following advantage. That is, if the supercharging pressure is low, the change of the supercharging pressure when the operation state of the vane changes may be small.

In this case, even when the operation state of the vane is changed for the measurement of the supercharging pressure change delay time (or the EGR rate change delay time at the vane being manipulated), it is difficult to identify the time of the start of the change of the supercharging pressure or the EGR rate by the influence of the change of the operation state of the vane.

However, if the supercharging pressure is high, the change of the supercharging pressure when the operation state of the vane changes is relatively large.

Therefore, the measurement of the supercharging pressure change delay time or the EGR rate change delay time at the vane being manipulated only when the uninjection operation starts and the supercharging pressure is equal to or higher than the predetermined pressure has an advantage that the time of the start of the change of the supercharging pressure or the EGR rate due to the change of the operation state of the vane can be easily identified.

Similarly, if the supercharging pressure is low, the change of the EGR rate when the operation state of the EGR control valve changes may be small.

In this case, even when the operation state of the EGR control valve is changed for the measurement of the EGR rate change delay time (or the supercharging pressure change delay time at the EGR control valve being manipulated), it is difficult to identify the time of the start of the change of the EGR rate or the supercharging pressure by the influence of the change of the operation state of the EGR control valve.

However, if the supercharging pressure is high, the change of the EGR rate when the operation state of the EGR control valve changes is relatively large.

Therefore, the measurement of the EGR rate change delay time or the supercharging pressure change delay time at the EGR control valve being manipulated only when the uninjection operation starts and the supercharging pressure is equal to or higher than the predetermined pressure has an advantage that the time of the start of the change of the EGR rate or the supercharging pressure due to the change of the operation state of the EGR control valve can be easily identified.

Further, the above-explained embodiments are those in the case that the invention is applied to the compression self-ignition type internal combustion engine. However, the invention can be applied to a spark ignition type internal combustion engine (i.e. a gasoline engine).