JP4214955B2 - Control device for internal combustion engine - Google Patents

Description

  The present invention relates to a control apparatus for an internal combustion engine that includes an in-cylinder pressure sensor that detects an in-cylinder pressure of the internal combustion engine, calculates a gain error with respect to the output characteristic of the in-cylinder pressure sensor, and corrects the output characteristic of the in-cylinder pressure sensor.

Conventionally, as described in Patent Document 1, a method of controlling the operating state of an internal combustion engine based on a detection value of an in-cylinder pressure sensor that detects an in-cylinder pressure of the internal combustion engine is known.
However, as shown in FIG. 2, if there is a gain error in the output characteristics of the in-cylinder pressure sensor, as shown in FIG. 6, the in-cylinder pressure (graph a) detected by the in-cylinder pressure sensor and the true in-cylinder pressure ( Deviation occurs from graph b).

On the other hand, Patent Document 1 discloses a method of correcting output characteristics by obtaining a gain error of an in-cylinder pressure sensor. As shown in FIG. 6, the in-cylinder pressure during non-combustion (referred to as standard in-cylinder pressure) is detected by the in-cylinder pressure sensor at the crank angle (ta in the figure) at least one point in the compression stroke. In this method, the value is compared with the standard value of the true in-cylinder pressure to obtain a gain error ΔGa of the in-cylinder pressure sensor, and the output characteristic of the in-cylinder pressure sensor is corrected by this gain error ΔGa.
Japanese Unexamined Patent Publication No. 2000-240497

However, in the above known technique, since the standard value of the true in-cylinder pressure changes with each cycle, it is difficult to accurately calculate the gain error ΔGa of the in-cylinder pressure sensor. That is, Patent Document 1 describes that as a means for obtaining a standard value, a standard in-cylinder pressure that is set in advance based on design data or detected by an in-cylinder pressure sensor in an initial state (before deterioration) is used. Yes. However, with this method, since the true in-cylinder pressure that changes with each cycle cannot be obtained with high accuracy, even if the gain error ΔGa is calculated by comparing the detected value of the in-cylinder pressure sensor with the standard value, the gain error ΔGa The calculation accuracy of is reduced.
The present invention has been made based on the above circumstances, and an object thereof is to provide a control device for an internal combustion engine that can accurately calculate a gain error with respect to an output characteristic of an in-cylinder pressure sensor.

(Invention of Claim 1)
The present invention relates to an in-cylinder pressure sensor that detects an in-cylinder pressure (referred to as in-cylinder pressure) of an internal combustion engine, an intake pressure sensor that detects a pressure (referred to as intake pressure) in an intake pipe of the internal combustion engine, and an output of the in-cylinder pressure sensor. A control apparatus for an internal combustion engine comprising a gain error calculation means for calculating a gain error with respect to the characteristic, wherein the gain error calculation means takes in an intake pressure corresponding to an in-cylinder pressure at the start of compression of the internal combustion engine from an intake pressure sensor, Standard in-cylinder pressure calculating means for calculating in-cylinder pressure (referred to as standard in-cylinder pressure) corresponding to the non-combustion state excluding the pressure increase due to in-cylinder combustion of the internal combustion engine based on the intake pressure, and the calculated standard Comparing the in-cylinder pressure and the detected value of the in-cylinder pressure sensor, the gain error of the in-cylinder pressure sensor is calculated.

It has been found that the in-cylinder pressure of an internal combustion engine varies greatly depending on the pressure at the start of compression. Therefore, the intake pressure corresponding to the in-cylinder pressure at the start of compression of the internal combustion engine is taken in from the intake pressure sensor, and the in-cylinder pressure is calculated based on the intake pressure, thereby eliminating the pressure increase due to the in-cylinder combustion of the internal combustion engine. The in-cylinder pressure corresponding to the combustion state (standard in-cylinder pressure) can be calculated with high accuracy. As a result, the gain error calculation accuracy can be improved by calculating the gain error by comparing the calculated standard in-cylinder pressure and the detected value of the in-cylinder pressure sensor.
Further, according to the present invention, the standard in-cylinder pressure calculating means corrects the detection time of the intake pressure sensor (the time when intake pressure is taken from the intake pressure sensor) according to the rotational speed of the internal combustion engine.
When the installation position of the intake pressure sensor is far from the cylinder, the in-cylinder pressure (pressure at the start of compression) immediately before the intake valve closes and the detected value of the intake pressure sensor differ due to pressure fluctuations that occur in the intake pipe. There is a case. Since it is known that the cycle of the pressure fluctuation that occurs in the intake pipe depends at least on the rotational speed of the internal combustion engine (referred to as engine speed), compression is achieved by correcting the detection timing of the intake pressure sensor with the engine speed. The in-cylinder pressure at the start can be detected (estimated) with high accuracy.
(Invention of Claim 2)
According to the present invention, the standard in-cylinder pressure calculating means sets the detection time of the intake pressure sensor (the time when intake pressure is taken from the intake pressure sensor) to the intake pipe length from the cylinder position of the internal combustion engine to the installation position of the intake pressure sensor. Or it correct | amends according to at least 1 of the cross-sectional area of an intake pipe, or the cylinder volume of an internal combustion engine, It is characterized by the above-mentioned.
As described in the first aspect of the invention, the cycle of the pressure fluctuation generated in the intake pipe depends on the engine speed, but besides the engine speed, the mounting position of the intake pressure sensor, the cross-sectional area of the intake pipe, the cylinder It also depends on the volume. Therefore, the in-cylinder pressure at the start of compression can be accurately detected (estimated) by correcting the detection timing of the intake pressure sensor by at least one of the installation position of the intake pressure sensor, the cross-sectional area of the intake pipe, the cylinder volume, and the like. .

(Invention of Claim 3 )
3. The control apparatus for an internal combustion engine according to claim 1, wherein the standard in-cylinder pressure calculating means takes in the intake pressure detected immediately before the intake valve of the internal combustion engine closes the intake port from the intake pressure sensor, and calculates the intake pressure. Based on this, the standard in-cylinder pressure is calculated.
By using the intake pressure (detected value of the intake pressure sensor) detected immediately before the intake valve closes the intake port, the intake pressure corresponding to the in-cylinder pressure at the start of compression of the internal combustion engine can be obtained.

(Invention of Claim 4 )
3. The control apparatus for an internal combustion engine according to claim 1 or 2 , wherein the standard in-cylinder pressure calculating means obtains a plurality of intake pressures detected during a certain period immediately before the intake valve of the internal combustion engine closes the intake port from the intake pressure sensor. The standard in-cylinder pressure is calculated based on the intake and the average value of the plurality of intake pressures. By adopting the average value of a plurality of intake pressures, it is possible to eliminate the error due to noise and the influence of intake pulsation, so that the cylinder pressure at the start of compression can be detected (estimated) with high accuracy.

(Invention of Claim 5 )
The control system of any internal combustion engine according to claim 1-4, the gain error calculation means, when a non-combustion state in which the fuel injection into the cylinder is cut, to implement the process of calculating the gain error Features.
For example, when fuel injection is cut, such as when the vehicle is decelerating, naturally, no combustion pressure is generated due to fuel combustion, so the standard in-cylinder pressure corresponding to the non-combustion state excluding pressure rise due to in-cylinder combustion is accurately calculated. it can.

(Invention of Claim 6 )
The control system of any internal combustion engine according to claim 1 to 5, the standard cylinder pressure calculation means, after closing the intake port an intake valve of an internal combustion engine, before at least the combustion pressure from the combustion of the fuel occurs The standard in-cylinder pressure is calculated from one crank angle.
In this case, the gain error calculation process need not be limited to the non-combustion state in which the fuel injection is cut, and can be performed even during a normal combustion cycle. That is, even during normal vehicle travel, if the combustion pressure due to fuel combustion is not generated (for example, the compression stroke), the standard in-cylinder pressure corresponding to the non-combustion state excluding the pressure increase due to in-cylinder combustion is set. It can be calculated with high accuracy.

(Invention of Claim 7 )
The control system of any internal combustion engine according to claim 1 to 6, the standard cylinder pressure calculation means, based on the intake pressure taken from the intake pressure sensor, calculating a standard cylinder pressure using the polytropic equation Features.
According to the present invention, since the intake pressure corresponding to the in-cylinder pressure at the start of compression of the internal combustion engine is detected, the standard in-cylinder pressure can be calculated using a known polytropic equation based on the intake pressure.

(Invention of Claim 8 )
The control system of any internal combustion engine according to claim 1 to 7, as an alternative value correlating with the intake air pressure detected by the intake pressure sensor, intake air quantity detecting an intake air amount of the internal combustion engine (fresh air amount) The standard in-cylinder pressure calculating means has a sensor, calculates the intake pressure by converting the intake air amount detected by the intake air amount sensor into pressure, and calculates the standard in-cylinder pressure based on the intake pressure. .
The detected value of the intake pressure sensor, that is, the intake pressure in the intake pipe has a correlation with the amount of intake air taken into the internal combustion engine. Therefore, instead of using an intake air pressure sensor, an intake air amount sensor (for example, an air flow meter) that detects the intake air amount is used, and after taking the detected value (intake air amount) of the intake air amount sensor, the pressure is converted. The intake pressure can be calculated. The fresh air amount is the amount of outside air taken in by the internal combustion engine, that is, the amount of air that does not contain EGR gas.

  The best mode for carrying out the present invention will be described in detail with reference to the following examples.

FIG. 1 is an in-cylinder pressure waveform diagram of a diesel engine, and FIG. 3 is a configuration diagram showing a control system of the diesel engine.
The internal combustion engine of the present embodiment is, for example, a diesel engine 1 that employs an accumulator fuel injection system as shown in FIG.
In the diesel engine 1, a piston 4 is accommodated in a cylinder 3 formed in a cylinder block 2, and the movement of the piston 4 reciprocating in the cylinder 3 is caused by a crankshaft (not shown) of the diesel engine 1 through a connecting rod 5. To be transmitted as a rotational motion.

A cylinder head 7 that forms a combustion chamber 6 in the upper part of the piston 4 is fixed to the upper end surface of the cylinder block 2. The cylinder head 7 is formed with an intake port 8 and an exhaust port 9 that open to the combustion chamber 6.
The intake port 8 and the exhaust port 9 are opened and closed by an intake valve 10 and an exhaust valve 11 driven by cams (not shown), respectively.

An intake pipe 12 for sucking outside air is connected to the intake port 8, and during the intake stroke in which the intake valve 10 opens the intake port 8, the piston 4 descends in the cylinder 3 to generate an in-cylinder negative pressure. Then, the outside air sucked from the intake pipe 12 flows into the cylinder through the intake port 8.
Further, an exhaust pipe 13 for discharging combustion gas is connected to the exhaust port 9, and the exhaust valve 11 rises from the combustion chamber 6 (inside the cylinder) due to the piston 4 rising during the exhaust stroke in which the exhaust valve 11 opens the exhaust port 9. The extruded combustion gas is discharged to the exhaust pipe 13 through the exhaust port 9.

The accumulator fuel injection system includes a common rail 14 that accumulates high-pressure fuel corresponding to the injection pressure, a fuel supply pump (not shown) that pumps high-pressure fuel to the common rail 14, and high-pressure fuel accumulated on the common rail 14 as diesel. It has an injector 15 or the like that injects into the cylinder (combustion chamber 6) of the engine 1, and is controlled by an electronic control unit (referred to as ECU 16).
The common rail 14 accumulates the high-pressure fuel supplied from the fuel supply pump up to the target rail pressure, and the accumulated high-pressure fuel is supplied to the injector 15 via the fuel pipe 17. The target rail pressure of the common rail 14 is set by the ECU 16. Specifically, the operating state of the diesel engine 1 is detected from the accelerator opening (engine load) and the engine speed, and a target rail pressure suitable for the operating state is set.

The injector 15 has an electromagnetic valve that is electronically controlled by the ECU 16 and a nozzle that injects fuel by the opening operation of the electromagnetic valve. With the tip of the nozzle protruding into the combustion chamber 6, the cylinder head 7 Is attached.
The ECU 16 inputs sensor information detected by various sensors (NE sensor 18, accelerator opening sensor 19, fuel pressure sensor 20, in-cylinder pressure sensor 21, intake pressure sensor 22, etc.) shown in FIG. Based on this, the operation state of the diesel engine 1 is controlled.

  The NE sensor 18 is disposed in the vicinity of the pulsar 23 that rotates in synchronization with the crankshaft of the diesel engine 1, and the number of teeth provided on the outer peripheral portion of the pulsar 23 while the pulsar 23 rotates once with the crankshaft. A plurality of pulse signals corresponding to are output. The ECU 16 detects the engine speed NE by measuring the time interval of the pulse signal output from the NE sensor 18. The accelerator opening sensor 19 detects the accelerator opening from an operation amount (depression amount) of an accelerator pedal (not shown) operated by the driver, and outputs the detected accelerator opening to the ECU 16.

The fuel pressure sensor 20 is attached to the common rail 14, detects the fuel pressure (actual rail pressure) accumulated in the common rail 14, and outputs it to the ECU 16.
The in-cylinder pressure sensor 21 is attached to the cylinder head 7, detects the in-cylinder pressure of the diesel engine 1, and outputs it to the ECU 16.
The intake pressure sensor 22 is attached to the intake pipe 12, detects the intake pressure in the intake pipe 12, and outputs it to the ECU 16.

The ECU 16 performs injection pressure control and injection amount control based on the sensor information.
The injection pressure control is to control the fuel pressure accumulated in the common rail 14, and the discharge amount (pump discharge amount) of the fuel supply pump so that the actual rail pressure detected by the fuel pressure sensor 20 matches the target rail pressure. Feedback control.
The injection amount control controls the injection amount and the injection timing injected from the injector 15, calculates the optimal injection amount and the injection timing according to the operating state of the diesel engine 1, and according to the calculation result, the electromagnetic amount of the injector 15 is calculated. Drive the valve.

Further, the ECU 16 detects the fuel ignition timing (combustion start timing) based on the detection value (cylinder pressure) of the in-cylinder pressure sensor 21 in order to optimally control the fuel injection timing, for example.
By the way, as shown in FIG. 2, the cylinder pressure sensor 21 has a gain error in output characteristics (changes in output sensitivity) due to use conditions such as temperature and changes with time, and the detection accuracy of the combustion start timing decreases. There is a fear.
Therefore, the ECU 16 has a function of gain error calculation means for calculating the gain error of the in-cylinder pressure sensor 21 and correcting the output characteristics.

Hereinafter, a processing procedure for calculating the gain error of the in-cylinder pressure sensor 21 will be described with reference to a flowchart shown in FIG.
Note that the processing shown in FIG. 4 is performed when the cylinder of the diesel engine 1 is in a non-combustion state, for example, when fuel injection is cut, such as during vehicle deceleration.
Step 10 ... The intake valve closing timing at which the intake valve 10 closes the intake port 8 is input.
Step 20: The timing for taking in the detected value (referred to as sensor value Pm) from the intake pressure sensor 22 is determined. Here, it is set immediately before the closing timing of the intake valve 10, for example, 5 ° CA (crank angle) before the closing timing of the intake valve 10.

Step 30: The cylinder volume V1 corresponding to the crank angle when the sensor value Pm is taken from the intake pressure sensor 22 is read from the memory built in the ECU 16. The cylinder volume V1 is substantially equal to the cylinder volume when the intake valve 10 closes the intake port 8. Note that data indicating the correlation between the crank angle and the cylinder volume is stored in the memory of the ECU 16.
Step 40... The sensor value Pm is captured from the intake pressure sensor 22 at the capture time determined at Step 20 (time t1 shown in FIG. 1). The sensor value Pm acquired from the intake pressure sensor 22 corresponds to the in-cylinder pressure at the start of compression of the diesel engine 1.

  Step 50: The polytropic index n is read from the memory. The polytropic index n can be obtained from, for example, the intake pressure and the engine speed, and is stored on a map having the intake pressure and the engine speed as coordinate axes. Accordingly, the polytropic index n is obtained by map search using the sensor value Pm (intake pressure) acquired in step 40 and the engine speed NE at that time.

Step 60 (standard in-cylinder pressure calculating means of the present invention): A period from when the intake valve 10 closes the intake port 8 to when the exhaust valve 11 opens the exhaust port 9 (both the intake valve 10 and the exhaust valve 11 are closed) In a certain period), when a crank angle at a certain point is called a standard point, an in-cylinder pressure (referred to as a standard in-cylinder pressure Pb) at the standard point (time t2 shown in FIG. 1) is calculated. This standard in-cylinder pressure Pb is calculated using the following polytropic equation (1).
Pb = Pm × (V1 / V2) ⁿ (1)
V1: Cylinder volume when intake valve is closed V2: Cylinder volume at standard point

Step 70: The detection value Ps of the in-cylinder pressure sensor 21 detected at the standard point (time t2 in FIG. 1) is taken in.
Step 80: The standard in-cylinder pressure Pb obtained in step 60 is compared with the detected value Ps of the in-cylinder pressure sensor 21 taken in step 70, and the gain error ΔGa of the in-cylinder pressure sensor 21 is calculated from the following equation (2). calculate.
ΔGa = Ps / Pb ………………………… (2)

(Effect of Example 1)
It has been found that the in-cylinder pressure at the time of compression of the diesel engine 1 varies greatly depending on the pressure at the start of compression. On the other hand, in the first embodiment, the intake pressure corresponding to the in-cylinder pressure at the start of compression, that is, the intake pressure immediately before the intake valve 10 closes the intake port 8 is detected by the intake pressure sensor 22 and is taken into the ECU 16. Thus, the pressure at the start of compression is detected (estimated). As a result, since the true in-cylinder pressure (standard in-cylinder pressure Pb) at the standard point (time t2) can be calculated with high accuracy, the standard in-cylinder pressure Pb and the detected value Ps of the in-cylinder pressure sensor 21 taken in at the same time t2 , The calculation accuracy of the gain error ΔGa is improved, and the output characteristics of the in-cylinder pressure sensor 21 can be accurately corrected according to the gain error ΔGa.

  In the first embodiment, an example in which the in-cylinder pressure sensor 21 is used to detect the ignition timing of the fuel has been described, but other examples of use of the in-cylinder pressure sensor 21 include, for example, an injection amount and a combustion There are methods for estimating the temperature, etc., and even in these cases, it goes without saying that the method of calculating the gain error of the in-cylinder pressure sensor 21 described in the first embodiment and correcting the output characteristics can be applied.

In step 20 of the first embodiment, the timing at which the sensor value Pm is captured from the intake pressure sensor 22 is set immediately before the closing timing of the intake valve 10, for example, 5 ° CA (crank angle) before the closing timing of the intake valve 10. In addition to this, for example, a plurality of intake pressures detected during a certain period immediately before the intake valve 10 closes the intake port 8 is taken in from the intake pressure sensor 22, and an average of the plurality of intake pressures is taken. The standard in-cylinder pressure can also be calculated based on the value.
According to this method, by obtaining the average value of a plurality of intake air pressures that have been taken in, it is possible to eliminate the effects of detection errors due to noise and the effects of intake air pulsation, so that reliability is improved and the intake pressure corresponding to the in-cylinder pressure at the start of compression is improved. The atmospheric pressure can be detected with higher accuracy.

Further, as shown in FIG. 5, when the attachment position of the intake pressure sensor 22 attached to the intake pipe 12 is away from the cylinder 3, immediately before the intake valve 10 is closed due to the pressure fluctuation generated in the intake pipe 12. In-cylinder pressure (pressure at the time of starting compression) at the time and the detected value of the intake pressure sensor 22 may be different.
Here, it is known that the period of the pressure fluctuation generated in the intake pipe 12 depends at least on the engine speed. Therefore, the in-cylinder pressure at the start of compression can be accurately detected (estimated) by correcting the detection timing of the intake pressure sensor 22 (the timing at which the ECU 16 takes in the sensor value Pm from the intake pressure sensor 22) with the engine speed.

  Further, the cycle of the pressure fluctuation generated in the intake pipe 12 includes, for example, the length of the intake pipe 12 from the cylinder position to the installation position of the intake pressure sensor 22, the cross-sectional area of the intake pipe 12, the cylinder other than the engine speed. It also depends on the volume. Therefore, the detection timing of the intake pressure sensor 22 is corrected by at least one of the mounting position of the intake pressure sensor 22, the cross-sectional area of the intake pipe 12, the cylinder volume, etc. in addition to the correction based on the engine speed. Furthermore, the in-cylinder pressure at the start of compression can be detected (estimated) with high accuracy.

  The calculation process of the gain error by the ECU 16 does not need to be performed only when the fuel injection is cut and is in a non-combustion state, and can also be performed during a normal combustion cycle. That is, even when the vehicle is running normally (when fuel injection is being performed), the pressure increase due to in-cylinder combustion is excluded before the combustion pressure due to fuel combustion occurs (for example, the compression stroke) The standard in-cylinder pressure corresponding to the non-combustion state can be calculated. Therefore, if the standard point (crank angle when calculating the standard in-cylinder pressure) described in the first embodiment is set before the combustion pressure is generated after the intake valve 10 closes the intake port 8, the influence of the combustion pressure is affected. The standard in-cylinder pressure can be calculated by the same method as in the first embodiment without receiving the above.

  In the first embodiment, an example in which the standard in-cylinder pressure is calculated based on the sensor value Pm of the intake pressure sensor 22 is described. However, as an alternative value correlated with the intake pressure, an intake air amount sensor 24 (for example, an air flow meter) shown in FIG. It is also possible to use the intake air amount Ma (the amount of fresh air that does not contain EGR gas) that is detected in step (1). In this case, the ECU 16 calculates the intake pressure by converting the intake air amount Ma taken in from the intake amount sensor 24, and calculates the standard in-cylinder pressure by the method described in the first embodiment based on the intake pressure. You can also.

It is a cylinder pressure waveform figure of a diesel engine (Example 1). It is an output characteristic figure of a cylinder pressure sensor. It is a block diagram which shows the control system of a diesel engine. It is a flowchart which shows the process sequence for calculating a gain error. It is explanatory drawing of the intake system which shows the calculation (estimation) error of the compression start pressure concerning the attachment position of an intake pressure sensor. It is a cylinder pressure waveform figure of an internal combustion engine (prior art).

Explanation of symbols

1 Diesel engine (internal combustion engine)
3 Cylinder 8 Intake Port 10 Intake Valve 12 Intake Pipe 16 ECU (Control Device / Gain Error Calculation Means)
21 In-cylinder pressure sensor 22 Intake pressure sensor 24 Intake air amount sensor

Claims (8)

An in-cylinder pressure sensor for detecting an in-cylinder pressure of an internal combustion engine (referred to as in-cylinder pressure);
An intake pressure sensor for detecting a pressure in an intake pipe of the internal combustion engine (referred to as intake pressure);
Based on the information obtained from the intake pressure sensor, Bei example a gain error calculation means for calculating a gain error for the output characteristics of the cylinder pressure sensor,
The gain error calculating means includes
A cylinder corresponding to a non-combustion state in which an intake pressure corresponding to the in-cylinder pressure at the start of compression of the internal combustion engine is taken from the intake pressure sensor and a pressure increase due to in-cylinder combustion of the internal combustion engine is excluded based on the intake pressure. A standard in-cylinder pressure calculating means for calculating an internal pressure (referred to as a standard in-cylinder pressure);
Calculated the by comparison with a standard cylinder pressure and the detection value of the cylinder pressure sensor, a control apparatus for an internal combustion engine that to calculate the gain error of the cylinder pressure sensor,
The control apparatus for an internal combustion engine, wherein the standard in-cylinder pressure calculating means corrects the detection timing of the intake pressure sensor in accordance with a rotation speed of the internal combustion engine. An in-cylinder pressure sensor for detecting an in-cylinder pressure of an internal combustion engine (referred to as in-cylinder pressure);
An intake pressure sensor for detecting a pressure in an intake pipe of the internal combustion engine (referred to as intake pressure);
Based on information obtained from the intake pressure sensor, a gain error calculation means for calculating a gain error with respect to the output characteristic of the in-cylinder pressure sensor,
The gain error calculating means includes
A cylinder corresponding to a non-combustion state in which an intake pressure corresponding to the in-cylinder pressure at the start of compression of the internal combustion engine is taken from the intake pressure sensor and a pressure increase due to in-cylinder combustion of the internal combustion engine is excluded based on the intake pressure. A standard in-cylinder pressure calculating means for calculating an internal pressure (referred to as a standard in-cylinder pressure);
A control device for an internal combustion engine that calculates a gain error of the in-cylinder pressure sensor by comparing the calculated standard in-cylinder pressure and a detection value of the in-cylinder pressure sensor,
The standard in-cylinder pressure calculating means determines the detection timing of the intake pressure sensor, the intake pipe length from the cylinder position of the internal combustion engine to the installation position of the intake pressure sensor, the cross-sectional area of the intake pipe, or the internal combustion engine A control apparatus for an internal combustion engine, wherein the correction is made according to at least one of the cylinder volumes . The control apparatus for an internal combustion engine according to claim 1 or 2 ,
The standard in-cylinder pressure calculating means takes in the intake pressure detected immediately before the intake valve of the internal combustion engine closes the intake port from the intake pressure sensor, and calculates the standard in-cylinder pressure based on the intake pressure. A control device for an internal combustion engine. The control apparatus for combustion engine among according to claim 1 or 2,
The standard in-cylinder pressure calculating means takes in a plurality of intake pressures detected during a predetermined period immediately before the intake valve of the internal combustion engine closes the intake port from the intake pressure sensor, and based on an average value of the plurality of intake pressures. And a control device for an internal combustion engine , wherein the standard in-cylinder pressure is calculated . In the control device for an internal combustion engine according to any one of claims 1 to 4,
The control apparatus for an internal combustion engine, wherein the gain error calculation means performs the gain error calculation process in a non-combustion state in which fuel injection into a cylinder is cut off . In the control device for an internal combustion engine according to any one of claims 1 to 5,
The standard in-cylinder pressure calculating means calculates the standard in-cylinder pressure at at least one crank angle before the combustion pressure due to fuel combustion occurs after the intake valve of the internal combustion engine closes the intake port. A control device for an internal combustion engine. The control device for an internal combustion engine according to any one of claims 1 to 6,
The control apparatus for an internal combustion engine, wherein the standard in-cylinder pressure calculating means calculates the standard in-cylinder pressure using a polytropic formula based on the intake pressure taken in from the intake pressure sensor. The control device for an internal combustion engine according to any one of claims 1 to 7 ,
As an alternative value correlated with the intake pressure detected by the intake pressure sensor, an intake air amount sensor that detects an intake air amount (fresh air amount) of the internal combustion engine,
The internal cylinder engine is characterized in that the standard in-cylinder pressure calculating means calculates an intake air pressure by converting an intake air amount detected by the intake air amount sensor, and calculates the standard in-cylinder pressure based on the intake air pressure. Control device .

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