JP5002987B2 - Engine cylinder intake gas amount measuring device - Google Patents

Description

  The present invention measures the amount of gas sucked into a cylinder of an engine, specifically, the amount of non-combustible gas that does not contribute to combustion among the gas sucked into the cylinder, and further, based on the measured value of the amount of non-combustible gas. The present invention relates to a technique for measuring the amount of air (fresh air) that does not contain non-combustible gas.

  In Patent Documents 1 and 2, the amount of air flowing into the intake manifold of the engine and the amount of air flowing out of the intake manifold and sucked into the cylinder are calculated and the amount of air in the intake manifold is calculated, and the air is sucked into the cylinder. Cylinder volume corrected based on the amount of residual gas (internal EGR gas) corresponding to the valve overlap amount of the intake / exhaust valve, the cylinder volume at the intake valve closing timing, the intake manifold volume, and the intake manifold interior And calculating the amount of air.

Patent Document 3 discloses that the cylinder intake EGR amount is calculated by first-order lag processing of the EGR flow rate flowing into the intake manifold.
Japanese Patent Application No. 2001-221105 Japanese Patent Application No. 2002-227687 Japanese Patent Application No. 10-318047

  In Patent Documents 1 and 2, since the influence of EGR gas (external EGR gas) flowing into the intake manifold via the EGR valve is not considered, when applied to a general engine with an EGR device, the air in the intake manifold Since the calculation error of the density is large and the influence of the cylinder intake EGR gas cannot be corrected, the calculation error of the cylinder intake air amount particularly when the valve timing is suddenly changed in an engine equipped with a variable valve. Was getting bigger.

  Further, in the method of calculating the cylinder intake EGR amount by the first-order lag processing of the EGR flow rate into the intake manifold as in Patent Document 3, when the valve timing is suddenly changed as described above, the cylinder is sucked into the cylinder. Since the phase of the EGR gas changes before the EGR gas flowing into the intake manifold, the calculation error of the cylinder intake EGR gas amount is enlarged.

  The present invention has been made paying attention to such a conventional problem, and calculates the intake amount of non-combustible gas that does not contribute to combustion, such as EGR gas, into the cylinder with high accuracy, and thus, an air cylinder that does not contain non-combustible gas The purpose is to increase the control accuracy of the fuel injection amount by calculating the intake amount to the fuel with high accuracy.

For this reason, the present invention periodically calculates and updates the amount of non-combustible gas that does not contribute to combustion in the intake manifold of the engine, the total amount of gas in the intake manifold, and the total amount of gas sucked into the cylinder. On the other hand, a cylinder intake gas amount measuring device that calculates the amount of non-combustible gas sucked into the cylinder based on these calculated values and calculates the amount of cylinder intake air that does not include non-combustible gas, Includes an internal EGR gas amount that is the sum of the amount of exhaust blown back from the exhaust passage to the intake passage during the valve overlap period and the amount of exhaust retained in the cylinder without being discharged from the cylinder during the exhaust stroke. The total amount of gas inside is obtained by adding the amount of incombustible gas including the amount of internal EGR gas, and the amount of incombustible gas sucked into the cylinder is The ratio of the amount of non-combustible gas in the cylinder divided by the total amount of gas in the intake manifold is multiplied by the total amount of gas sucked into the cylinder. The internal EGR gas amount of the target cylinder is subtracted from the total amount of gas sucked into the cylinder, and the incombustible gas amount sucked into the cylinder is further subtracted.

  According to the present invention, the ratio of the incombustible gas amount in the intake manifold to the total amount of gas in the intake manifold (incombustible gas amount + air amount) is based on the incombustible gas amount sucked into the cylinder with respect to the total amount of gas in the cylinder. Since it can be approximated as being equal to the ratio, the amount of nonflammable gas sucked into the cylinder based on the calculated value of the amount of nonflammable gas in the intake manifold, the total gas amount in the intake manifold, and the total gas amount in the cylinder The amount can be calculated.

In particular, even in a transient state where the valve timing is suddenly changed in an engine equipped with a variable valve, by calculating the total gas amount in the cylinder that changes due to the change in valve timing, the amount of non-combustible gas that changes in the same way can be calculated. It is possible to calculate and update with high response.
Then, by subtracting the amount of incombustible gas in the cylinder from the total amount of gas in the cylinder, the amount of fresh air that does not contain incombustible gas can be calculated with high accuracy, and in particular, the valve timing of the intake valve can be varied. In the engine to be controlled, the accuracy of fuel injection amount control and air-fuel ratio control can be maintained with high accuracy without being affected by valve timing control.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a configuration diagram of an engine (internal combustion engine).
The combustion chamber 3 defined by the piston 2 of each cylinder of the engine 1 is provided with an intake valve 5 and an exhaust valve 6 so as to surround the spark plug 4. Intake is drawn into the combustion chamber 3 from the intake valve 5 through the intake passage 7, and a manifold portion (intake manifold) 8 is disposed in the intake passage 7. Exhaust gas in the combustion chamber 3 is discharged from the exhaust valve 6 through the exhaust passage 9.

  The intake valve 5 is controlled by a variable valve mechanism 5a having variable valve timing (opening / closing timing). The variable valve mechanism 5a may be a method of directly electromagnetically driving the valve body of the intake valve 5 in addition to a method of changing the valve timing by changing the rotation phase of the intake camshaft with respect to the crankshaft, A mechanism that varies not only the valve timing but also the lift amount may be used. The exhaust valve 6 has a fixed valve characteristic in the present embodiment, but may have a configuration in which the valve characteristic can be changed by a variable valve device as in the intake valve.

An intake throttle valve 10 is provided upstream of the manifold portion 8 in the intake passage 7. The intake passage 7 is also provided with an electromagnetic fuel injection valve 11 at the intake port portion of each cylinder.
Further, an EGR passage (exhaust gas recirculation passage) 12 is provided for communicating the exhaust passage 9 and the manifold portion 8 of the intake passage 7. When the EGR valve 13 interposed in the EGR passage 12 is opened, the exhaust gas is exhausted by a pressure difference. Is partly returned to the manifold portion 8.

Here, the operation of the ignition plug 4, the variable valve operating device 5a, the electric throttle valve 10, the fuel injection valve 11 and the EGR valve 13 is controlled by a control unit (ECU) 14.
The ECU 14 outputs a crank angle signal in synchronization with the engine rotation, thereby detecting a crank angle sensor 15 capable of detecting the engine rotational speed Ne together with the crank angle position θ, and an accelerator for detecting an accelerator opening (accelerator pedal depression amount). Pedal sensor 16, hot-wire air flow meter 17 for measuring the air flow rate (mass flow rate) vQth [kg / h] flowing into the manifold portion 8 upstream of the throttle valve 10 in the intake passage 7, the temperature TIN [ K] and the exhaust pressure sensor 19 that detects the exhaust pressure PEX [Pa] of the exhaust passage 9 are input. In a third embodiment to be described later, an exhaust temperature sensor for detecting the exhaust temperature is provided.

The fuel injection timing and the fuel injection amount of the fuel injection valve 11 are controlled based on the engine operating conditions, but the fuel injection amount is basically calculated as described later based on the flow rate vQth measured by the air flow meter 17. The cylinder intake air amount QCYL [g] is controlled so as to have a desired air-fuel ratio.
The ignition timing by the spark plug 4 is controlled to MBT (optimum ignition timing on torque) or a knock limit based on engine operating conditions.

  In the present embodiment, the ECU 14 calculates the balance of gas flow in and out of the manifold portion 8 while calculating the total gas amount MAMANI in the manifold portion 8, the amount of EGR gas MEMANI as a non-combustible gas, and the total gas amount sucked into the cylinder. MACYL is calculated. Then, the ratio MEMANI / MAMANI between the total gas amount and the EGR gas amount in the manifold portion 8 can be approximated to the ratio between the total gas amount sucked into the cylinder and the EGR gas amount, and the cylinder intake EGR gas The amount is calculated, and finally, the cylinder intake air amount not including the EGR gas is calculated, and the fuel injection amount corresponding to the cylinder intake air amount is set and the fuel injection control is performed.

FIG. 2 shows an overall block diagram of fuel injection control.
The cylinder intake air amount calculation unit inputs the manifold passage 8 while inputting the throttle passage air flow rate Qth detected by the air flow meter 17, the EGR gas flow rate QEGR passing through the EGR valve 13, and the engine rotation speed Ne as basic parameters. The cylinder intake air amount MACYL is calculated while calculating the balance of the amount of EGR gas entering and exiting and the total gas amount. The cylinder intake air amount MACYL and other values to be described later are calculated and updated every unit time period Δt.

The cylinder intake EGR gas amount calculation unit inputs the EGR gas flow rate QEGR and the engine rotation speed Ne as basic parameters, and calculates the balance of the amount of EGR gas entering and exiting the manifold unit 8 while taking in the EGR into the cylinder. Gas amount (cylinder suction EGR gas amount) MECYL] is calculated.
Here, EGR gas containing burned components and air have slightly different amounts (mass) in the same state (temperature, pressure), but what we want to finally find is the amount (mass) of air that does not contain EGR gas. Therefore, the EGR gas is handled as air, and the amount (mass) equivalent to air is calculated. The same applies to the following calculation, and the total gas amount is also calculated as the total amount of the amount of EGR gas converted to air and the actual amount of air. This makes it easy to calculate the balance because it can be handled only by air. Or you may make it handle by a molar flow rate and a molar amount, without distinction of EGR gas and air.

Both the calculation units exchange and calculate parameters calculated in the respective balance calculation processes.
The manifold pressure calculation unit calculates a pressure (manifold pressure = intake pressure) PIN in the manifold 8 based on the total gas amount in the manifold and the manifold temperature TIN detected by the temperature sensor 18.

The basic fuel injection pulse width calculation unit calculates a basic fuel injection pulse width Tp based on the cylinder intake air amount MACYL.
The fuel injection pulse width calculation unit corrects the basic fuel injection pulse width Tp to calculate a final fuel injection pulse width Ti.
The fuel injection valve drive unit outputs a fuel injection signal having a pulse width corresponding to the fuel injection pulse width Ti to drive the fuel injection valve 11 and injects a fuel injection amount corresponding to the calculated cylinder intake air amount MACYL. Supply.

FIG. 3 shows details of the in-cylinder EGR gas amount calculation unit.
An EGR gas flow rate QEGRD [kg / h] is calculated by performing dead time correction corresponding to a transmission delay from the EGR valve 13 to the cylinder to the EGR gas flow rate QEGR [kg / h] passing through the EGR valve 13.
The flow rate obtained by subtracting the EGR gas flow rate QECYL [kg / h] flowing out of the manifold unit 8 and sucked into the cylinder from the EGR gas flow rate QEGRD [kg / h] flowing into the manifold unit 8 is an execution period of this calculation. It is converted into a balance amount (change amount) ΔMEMANI [g] of EGR gas in the manifold portion 8 per Δt [s]. When ΔMEMANI [g] is a positive value, the amount of EGR gas in the manifold portion 8 is increased, and when it is a negative value, the amount of EGR gas is decreased.

ΔMEMANI = (QTRM−QCYLz) × Δt × (1000/60/60) (1)
The EGR gas balance amount ΔMEMANI [g] in the manifold is added to the previously calculated value MEMANIz [g] of the EGR gas amount in the manifold to calculate the current EGR gas amount MEMANI [g] in the manifold.

MEMANI = MEMANIz + ΔMEMANI (2)
The EGR gas amount ratio MEGMNR is calculated by dividing the EGR gas amount MEMANI [g] in the manifold by the total gas amount MANANI [g] in the manifold. Here, the total gas amount MAMANI in the manifold is used by inputting a value calculated by adding an EGR gas amount in the manifold portion 8 and an air amount not including the EGR gas in a cylinder air amount calculation unit described later. .

MEGMNR = MEMANI / MAMANI (3)
Then, assuming that EGR gas is contained in the cylinder at the same EGR gas amount ratio as in the manifold section 8, the cylinder total gas amount MACYL0 [g] is multiplied by the EGR gas amount ratio MEGMNR. And the cylinder intake EGR gas amount MECYL [g] per cycle is calculated. Here, the cylinder intake total gas amount MACYL0 [g] is also used by inputting a value calculated by adding the cylinder intake EGR gas amount and the cylinder intake air amount in a cylinder intake air amount calculation unit described later.

MECYL = MACYL0 × MEGMNR (4)
The EGR gas amount MECYL [g] is converted into an EGR gas flow rate QECYL [kg / h] per time taken into the cylinder based on the engine rotational speed Ne.
QECYL = MECYL × Ne × mNREF × 60/1000 (5)
However, mNREF is the total number of intake strokes per engine revolution (in a 4-cycle engine, mNREF = number of engine cylinders / 2).

FIG. 4 shows details of the cylinder intake air amount calculation unit.
The EGR gas flow rate QEGR [kg / h] before the dead time correction is added to the air flow rate (manifold inflow air flow rate) Qth [kg / h] to the manifold portion 8 detected by the air flow meter 17, and the manifold portion 8 calculates the total flow rate of the gas flowing into the manifold 8 (manifold inflow total gas flow rate) QTRM [kg / h].

QTRM = Qth + QEGR (6)
Execution of this calculation is performed by subtracting the total flow rate of gas sucked into the cylinder previously calculated (cylinder intake total gas flow rate) QCYLz [kg / h] from the manifold inflow total gas flow rate QTRM [kg / h]. The total gas balance amount (change amount) ΔMAMANI [g] in the manifold portion 8 per period Δt [s] is converted. When ΔMAMANI [g] is a positive value, the total gas amount in the manifold portion 8 increases, and when it is a negative value, the total gas amount decreases.

ΔMAMANI = (QTRM−QCYLz) × Δt × (1000/60/60) (7)
The in-manifold total gas balance amount ΔMAMANI [g] is added to the previously calculated value MAMANIz [g] of the in-manifold total gas amount to calculate the current in-manifold total gas amount MAMANI [g].

MAMANI = MAMANIz + ΔMAMANI (8)
The total gas amount MAMANI [g] in the manifold is divided by the effective volume VMANI [m ³ ] of the intake manifold to calculate the gas density DMANI [g / m ³ ] in the manifold portion 8.
DMANI = MAMANI / VMANI (9)
Here, as the manifold volume VMANI [m ³ ], a fixed volume (geometric manifold volume VMANI #) from the position of the rotary shaft of the throttle valve to the intake port may be used for simplicity. If the value obtained by adding the total cylinder volume communicating with the manifold portion 8 immediately before the intake valve closes in the cylinder in the stroke is used as the effective volume, the gas density can be calculated with high accuracy.

The in-manifold gas density DMANI [g / m ³ ] is multiplied by the effective stroke volume VCYL [m ³ ] of the cylinder determined by the intake valve closing timing, and the total amount of gas sucked into the cylinder (total amount of cylinder suction gas) ) MACYL0 [g] is calculated. That is, it is handled that there is no substantial difference in gas density between the manifold portion 8 and the cylinder (temperature and pressure are substantially the same).

MACYL0 = DMANI × VCYL (10)
The cylinder intake total gas amount MACYL [g] is converted into a total gas flow rate QCYL [kg / h] per time taken into the cylinder based on the engine rotational speed Ne.
QCYL = MACYL × Ne × NREF × 60/1000 (11)
On the other hand, the cylinder intake EGR amount is subtracted from the cylinder intake gas total amount MACYL0 to calculate the amount of air (Cylinder intake air amount) MACYL [g] that does not include the EGR gas sucked into the cylinder per cycle.

MACYL = MACYL0-MECYL (11)
The cylinder intake air amount MACYL is multiplied by a coefficient KCONST [ms / g] to calculate a real-time basic fuel injection pulse width TPTRMN [ms].
TPTRMN = KCONST × MACYL (12)
In order to avoid the influence of the intake pulsation, the final basic fuel injection pulse width Tp [ms] is calculated by weighted averaging of the TPTRMN [ms].

In this way, the EGR gas amount sucked into the cylinder can be accurately calculated based on the gas amount ratio while periodically calculating the balance of the EGR gas amount and the total gas amount in the manifold portion 8.
Based on the cylinder intake EGR gas amount, the cylinder intake air amount (fresh air amount) that does not include EGR gas is accurately calculated even in a transient state, and highly accurate and responsive fuel injection corresponding to the new air amount is performed. Quantity control (air-fuel ratio control) can be performed.

FIG. 5 shows an embodiment in which a part of the cylinder air amount calculation unit in FIG. 4 is modified.
In FIG. 4, the cylinder intake air amount MACYL is calculated by subtracting the cylinder intake EGR gas amount MECYL calculated in FIG. 3 from the total intake gas amount MACYL0. However, in this embodiment, the EGR gas amount calculated in FIG. The gas amount ratio MEGMNR with respect to the total gas amount is subtracted from 1 (100%) to calculate the gas amount ratio MAGMNR with respect to the total gas amount of the air amount not including the EGR gas, and this gas amount ratio MAGMNR is calculated as the total intake gas amount MACYL0. The cylinder intake air amount MACYL is calculated by multiplying by.

MACYL = (1-MEGMNR) × MACYL0
= MAGGMNR × MACYL0 (13)
4 and 5, the EGR gas flow rate QEGR is used for calculating the total gas amount in the manifold. However, the embodiment of the in-cylinder air amount calculation unit shown in FIG. Then, the EGR gas flow rate QEGR is not used, and the in-manifold EGR gas amount MEMANI calculated in FIG. 3 is changed to the in-manifold air amount MAMANI0 ′ (which is obtained as an integrated value of the air amount balance of the manifold portion 8). By adding, the total gas amount in the manifold is calculated.

MAMANI = MEMANI + MAMANI0 ′ (14)
Further, an air flow rate QCYL ′ [kg / in which is drawn into the cylinder based on the engine rotational speed Ne with respect to the cylinder intake air amount MACYL obtained by subtracting the cylinder intake EGR gas amount MECYL from the cylinder intake total gas amount MACYL0. h].
QCYL ′ = MACYL × Ne × NREF × 60/1000 (15)
In the embodiment described above, the internal EGR amount (cylinder residual gas amount) is most simply calculated by changing the effective stroke volume VCYL of the cylinder from the cylinder volume at the intake valve closing timing to the piston top dead center position. By using the effective stroke volume calculated by subtracting the cylinder volume, the internal EGR amount can be removed in advance.

  However, this method does not take into account the amount of exhaust blow-back due to valve overlap, and the internal EGR gas amount cannot be calculated accurately. Therefore, more precisely, the gas amount ratio of the internal EGR gas amount to the total gas amount in the cylinder is measured in advance based on the intake valve closing timing, the engine rotational speed Ne, and the intake pressure (manifold portion 8 pressure) PIN. The effect of the internal EGR gas amount can be sufficiently removed by using the volume obtained by subtracting the volume corresponding to the gas amount ratio of the internal EGR gas from the cylinder volume at the intake valve closing timing as the cylinder effective volume.

As for the effective volume of the manifold portion 8, the manifold portion 8 communicates immediately before the intake valve closing timing, in addition to the cylinder immediately before the intake valve closing timing, as well as when the intake valve is opened and the intake stroke starts. It is preferable to calculate by subtracting the amount corresponding to the internal EGR gas volume for each of the cylinders.
FIG. 7 shows an embodiment in which the internal EGR gas amount is calculated as a mass and is reflected in the calculation of the balance of the total gas amount in the manifold.

FIG. 8 shows a configuration for calculating the cylinder effective volume and the effective manifold volume in the present embodiment.
First, referring to FIG. 9, based on the intake valve closing timing IVC, the engine rotational speed Ne, and the intake pressure PIN, the cylinder (target cylinder) c1 at the intake valve closing timing IVC and the manifold portion in the IVC of the target cylinder The intake efficiency ITAV1, ITAV2 is calculated for a cylinder (communication cylinder) c4 that communicates with No.8.

  Then, the actual volume of the target cylinder c1 (= VC1 + VPROOF #; VPROOF # is the volume of the combustion chamber portion excluding the space in which the piston moves) is multiplied by the intake efficiency ITAV1, and the effective volume VCYL1 ′ of the target cylinder is calculated. The effective volume VCYL2 ′ of the communication cylinder c4 is calculated by multiplying the actual volume (= VC2 + VPROOF #) of the communication cylinder c4 in IVC by the intake efficiency ITAV2.

VCYL1 ′ = (VC1 + VPROOF #) × ITAV1 (16)
VCYL2 ′ = (VC2 + VPROOF #) × ITAV2 (17)
The geometric manifold volume VMANI # is added to the calculated VCYL1 ′ and VCYL2 ′ to calculate the effective manifold volume VMANI.
VMANI = VMANI # + VCYL1 ′ + VCYL2 ′ (18)
Next, the internal EGR gas amount is calculated as follows. FIG. 10 shows a configuration for calculating the internal EGR gas amount.

  In the present embodiment, the internal EGR gas amount MRES stays in the cylinder without being discharged from the cylinder during the exhaust stroke and the amount of exhaust (blow-back gas amount) MRESOL that blows back from the exhaust passage to the intake passage during the valve overlap period. Calculated as the sum of the exhaust amount (residual gas amount) MRESEVC. Only the valve characteristic of the intake valve 5 is variable, and the valve characteristic of the exhaust valve 6 is constant.

Based on the intake valve closing timing IVC, the exhaust gas temperature TEX, and the pressure PEX, the blowback gas amount MRESOL is calculated by the following equations (19) to (23). TEX and PEX can be detected by an exhaust temperature sensor or an exhaust pressure sensor provided in an exhaust manifold or the like.
The following equation (19) is an equation for finally calculating MRESOL.
MRESOL = (MRESOLtemp × ASUMOL × 60) / (NE × 360) (19)
In the equation (19), MRESOLtemp is an average flow velocity when the exhaust gas blows back. The minute gap formed in the intake port or the exhaust port by the intake valve 5 or the exhaust valve 6 is regarded as an orifice, and the following equation (20) Calculated by

MREStemp = 1.4 × PEVC × MRSOLD × MRSOLP (20)
In Expression (20), PEVC is the pressure in the cylinder at the exhaust valve closing timing EVC, and is approximated by the exhaust pressure PEX immediately before EVC. Similarly, MRSOLD is the density of exhaust gas, and is calculated by the following equation (21) based on the exhaust gas constant REX and the in-cylinder temperature TEVC at EVC.

In Expression (21), REX can be calculated based on the target equivalence ratio, and in the present embodiment, the coefficient KCONST can be adopted as an indication of this. TEVC is approximated by the exhaust temperature TEX immediately before EVC.
In the equation (20), MRSOLP is the pressure of the exhaust gas, and is calculated by the following equation (22) based on the pressure ratio PINBYEX (= PIN / PEX) between the intake manifold and the exhaust manifold. SHEATR is a specific heat ratio and can be calculated based on a target equivalent ratio.

In equation (19), ASUMOL is the integrated opening area of the orifice, and as shown in the following equation (23), the crank formed by the intake valve 5 or the exhaust valve 6 with the smaller lift amount is formed. The section opening area ASIITA for each angle Δθ is calculated by integrating over the entire overlap period.
ASUMOL = Σ (ASIITA × θ) (23)
On the other hand, the staying gas amount calculation unit calculates the staying gas amount MRESEVC by the following equation (24) based on the exhaust gas temperature TEX and the pressure PEX.

MRESEVC = (PEVC × VEVC) / (REX × TEVC) (24)
In the equation (24), the cylinder pressure PEVC and the temperature TEVC can be approximated by the exhaust pressure PEX and the temperature TEX immediately before EVC, and the gas constant REX can be calculated based on the target equivalent ratio. It is as follows. VEVC is the cylinder volume at the exhaust valve closing timing EVC. In this embodiment, since the valve characteristic of the exhaust valve 6 is unchanged, it is calculated in advance and stored in the ECU 14.

Based on the blowback gas amount MRESOL and the staying gas amount MRESEVC calculated as described above, the first internal EGR gas amount MRES1 is calculated for the target cylinder c1 by the following equation (25).
MRES1 = MRESOL1 + MRESEVC1 (25)
Further, based on MRESOL and MRESEVC, the second internal EGR gas amount MRES2 is calculated by the following equation (26) for the communication cylinder.

MRES2 = MRESOL2 + MRESEVC2
= MRESOL1 × OLRATIO + MRESEVC2 (26)
In the equation (26), OLRATIO is the overlap opening area ratio, and is calculated for the communication cylinder, and is calculated for the integrated opening area SIGMAA up to the crank angle θivc during the valve overlap period and the target cylinder. As a ratio with the integrated opening area ASUMOL over the entire period, it is calculated by the following equation (27).

OLRATIO = SIGMAA / ASUMOL (27)
FIG. 11 shows the valve characteristics of the intake valve 5 and the exhaust valve 6 during the overlap period, and the area of the hatched portion corresponds to SIGMAA.
FIG. 12 shows the piston positions of the target cylinder and the communication cylinder at the crank angle θivc. FIG. 12A shows the case of a 4-cylinder engine and FIG. 12B shows the case of a 6-cylinder engine. In the case of a four-cylinder engine, OLRATIO is set to 1 because the communication cylinder c4 has passed the exhaust valve closing timing EVC at θivc when the target cylinder c1 is at the intake valve closing timing IVC. On the other hand, in the case of a 6-cylinder engine, at θivc, one of the two communicating cylinders c2 and c3 passes through EVC, but the other is in the overlap period, so that the OLATIO is 1 for the communicating cylinder c2. For the communication cylinder c3, OLRATIO is set to a value less than 1. When there is no overlap period, the blow-back gas amount MRESOL becomes 0, and the staying gas amount MRESEVC is output as the internal EGR gas amount.

Then, the internal EGR gas amount MRES1 of the target cylinder and the internal EGR gas amount MRES2 of the communicating cylinder are added to calculate the total internal EGR gas amount MRESTL.
Returning to FIG. 7, the total internal EGR gas amount MRESTL [g] calculated as described above is added when calculating the in-manifold total gas amount MAMANI [g], while the cylinder intake total gas amount MACYL0 [g] ], The cylinder intake air amount MACYL [g] is calculated by subtracting the cylinder intake EGR gas amount MECYL [g] from the subtracted value. Further, the balance calculation is performed by converting the cylinder intake total gas amount obtained by subtracting the internal EGR gas amount MRES1 into the cylinder intake total gas flow rate QCYL [kg / h] per hour.

In this way, since the internal EGR gas amount is calculated as a mass and reflected in the calculation of the balance of the air amount MAMANI in the manifold, changes in the state (mainly density) in the intake manifold due to the internal EGR gas are taken into account. Thus, the density of the gas in the cylinder, and hence the cylinder intake air amount QCYL can be calculated more accurately.
In addition, since the internal EGR gas amounts MRES1 and MRES2 are treated as the sum of the blow-back gas amount MRESOL and the staying gas amount MRESEVC, the internal EGR gas amount can be accurately calculated and the communication during the overlap period can be performed. Accurate evaluation of the amount of internal EGR gas related to the cylinder is possible.

Sectional drawing which shows the structure of the engine which concerns on one Embodiment of this invention. The block diagram which shows the fuel-injection control in embodiment same as the above Control block diagram showing cylinder intake EGR gas amount calculation unit Control block diagram showing a first example of a cylinder intake air amount calculation unit Control block diagram showing a second example of the cylinder intake air amount calculation unit Control block diagram showing a third example of the cylinder intake air amount calculation unit Control block diagram showing a third example of the cylinder intake air amount calculation unit The figure which shows the structure of cylinder effective volume and effective manifold volume calculation in the 3rd example same as the above. The figure which shows the state of the gas in an intake manifold and each cylinder in an intake valve closing timing. The figure which shows the structure of internal EGR gas amount calculation. The figure which shows the integrated opening area SIGMAA regarding the communication cylinder in the crank angle (theta) ivc of the intake valve closing timing IVC during an overlap period. The figure which shows the position of each piston of a target cylinder and a communicating cylinder in crank angle (theta) ivc same as the above.

Explanation of symbols

1 engine (internal combustion engine)
DESCRIPTION OF SYMBOLS 5 Intake valve 6 Exhaust valve 7 Intake passage 8 Manifold part 11 Fuel injection valve 12 EGR passage 13 EGR valve 14 Control unit 15 Crank angle sensor 16 Accelerator pedal sensor 17 Air flow meter 18 Temperature sensor 19 Exhaust pressure sensor

Claims (7)

While periodically calculating and updating the amount of non-combustible gas that does not contribute to combustion in the intake manifold of the engine, the total amount of gas in the intake manifold, and the total amount of gas sucked into the cylinder, A cylinder intake gas amount measuring device for measuring the amount of non-combustible gas sucked into a cylinder based on:
The total amount of gas in the intake manifold,
Non-combustible gas that does not contribute to combustion in the intake manifold;
The amount of air in the intake manifold that does not include non-combustible gases that do not contribute to the combustion;
Internal EGR gas that is the sum of the amount of exhaust that blows back from the exhaust passage to the intake passage during the valve overlap period and the amount of exhaust that stays in the cylinder without being discharged from the cylinder during the exhaust stroke;
A cylinder intake gas amount measuring device for an engine, characterized by adding By multiplying the ratio of the amount of non-combustible gas in the intake manifold divided by the total amount of gas in the intake manifold by the total amount of gas sucked into the cylinder, the amount of non-combustible gas sucked into the cylinder is obtained. 2. The cylinder intake gas amount measuring device for an engine according to claim 1, wherein the measuring device measures the cylinder intake gas amount. The amount of incombustible gas in the intake manifold is calculated by calculating the balance between the amount of incombustible gas flowing into the intake manifold and the amount of incombustible gas flowing out from the intake manifold and into the cylinder. The engine cylinder intake gas amount measuring device according to claim 1 or 2 . By subtracting the internal EGR gas from the total amount of gas sucked into the cylinder, and subtracting the amount of incombustible gas sucked into the cylinder from the subtracted value, the amount of air sucked into the cylinder is obtained. The cylinder intake gas amount measuring device for an engine according to any one of claims 1 to 3, wherein the calculation is performed. The engine cylinder intake according to any one of claims 1 to 4, wherein the total amount of gas sucked into the cylinder is calculated based on a balance calculation of the total amount of gas in the intake manifold. Gas quantity measuring device. The engine according to any one of claims 1 to 5, wherein the non-combustible gas flowing into the intake manifold is an external EGR gas or a gas in which all non-combustible gas components and air are mixed. Cylinder intake gas amount measuring device. 7. The engine according to claim 1, wherein in calculating the amount of the non-combustible gas, the non-combustible gas is calculated using a mass equivalent amount of air at the same temperature and the same pressure. Cylinder intake gas amount measuring device.

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