JP3988650B2 - Internal EGR amount estimation device for internal combustion engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an internal EGR amount estimation device for an internal combustion engine.
[0002]
[Prior art]
Conventionally, in a spark ignition type internal combustion engine, in order to reduce NOx (nitrogen oxide) by suppressing combustion temperature by increasing inactive components in combustion gas and to reduce fuel consumption by reducing pump loss, a variable valve mechanism is provided. In some cases, the overlap amount between the exhaust valve opening period and the intake valve opening period is expanded to increase the internal EGR amount. In this case, it is desirable to perform control for correcting the ignition timing, fuel injection amount, valve opening / closing timing, and the like according to the internal EGR amount.
[0003]
In Patent Document 1, the basic value of the internal EGR amount is calculated from the engine operating conditions (load, rotation speed, air-fuel ratio, EGR rate, intake negative pressure, etc.) under no overlap conditions. It is disclosed that the amount of increase correction due to overlap calculated based on time, its center crank angle position, and intake pressure is added to the basic value to calculate the internal EGR amount.
[0004]
[Patent Document 1]
JP 2001-221105 A
[0005]
[Problems to be solved by the invention]
However, in Patent Document 1, since the operating state of the engine changes and the combination of the load, the rotational speed, the combustion air-fuel ratio, the intake negative pressure, and the like change, the internal EGR amount is uniquely estimated by correcting the overlap amount. It was difficult.
[0006]
It is also conceivable to estimate the in-cylinder temperature from the exhaust temperature in the steady state of the engine, thereby improving the estimation accuracy of the internal EGR amount. However, in the transient state such as start, acceleration, fuel cut, etc. As the temperature rises and falls quickly and the estimation accuracy of the in-cylinder temperature is not sufficient, the error of the actual internal EGR amount with respect to the internal EGR amount calculated value may increase.
[0007]
In addition, during cooling after start-up, after fuel cut operation during deceleration, and at high water temperature during high-speed and high-load operation, valve components (particularly the shaft section) are thermally expanded due to temperature changes such as valves and cylinder heads. The valve clearance changes, and the valve opening / closing timing based on the cam twist angle is different from the actual valve opening / closing timing, which may cause an error in the actual internal EGR amount with respect to the calculated internal EGR amount.
[0008]
Although it is possible to improve the estimation accuracy of the internal EGR amount by detecting the exhaust temperature and the valve temperature based on the output of the temperature sensor, the addition of the sensor increases the cost and causes a delay in the response of the sensor. If this happens, an error will occur. It is also possible to estimate the exhaust temperature and valve temperature according to the fuel injection amount without providing a temperature sensor, but these estimated temperatures are balanced with a balance between the heat generation amount and the heat dissipation amount of the engine. In a transient state where the estimated temperature is not balanced, an error occurs in the estimated temperature, and the error of the actual internal EGR amount with respect to the calculated internal EGR amount may increase. For this reason, the actual ignition timing and the required injection amount cannot be satisfied, which may lead to deterioration in drivability and fuel consumption / exhaust.
[0009]
The present invention has been made to solve the above problem, and an object of the present invention is to accurately estimate the amount of internal EGR even in a transient state of the engine.
[0010]
[Means for Solving the Problems]
Therefore, in the present invention, The valve timing (exhaust valve closing timing, intake valve opening timing, etc.) is calculated based on the amount of change in the opening / closing timing of the variable valve timing mechanism, but the valve temperature and valve clearance are estimated and the valve timing is corrected by the valve clearance. Here, the estimated valve temperature value is calculated by calculating the valve equilibrium temperature in a steady state of the engine and giving a time delay to the change in the valve equilibrium temperature. Then, the in-cylinder temperature and the in-cylinder pressure when the exhaust valve is closed, and the gas constant of the exhaust gas composition according to the combustion air-fuel ratio are calculated, and based on at least these, the in-cylinder gas amount when the exhaust valve is closed And the amount of blown-back gas during the overlap between the exhaust valve opening period and the intake valve opening period is calculated. Then, the internal EGR amount is calculated based on the in-cylinder gas amount and the blowback gas amount.
[0012]
【The invention's effect】
According to the present invention, even in a transient state, the in-cylinder temperature or the valve temperature can be accurately estimated, the internal EGR amount can be estimated more accurately, and the ignition timing, fuel injection amount, and valve opening / closing timing are appropriately set. Doing so can improve drivability and improve fuel economy and exhaust.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a system configuration diagram of an internal EGR amount estimating apparatus for an internal combustion engine.
[0014]
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. The lift characteristics (opening / closing timing) of the intake valve 5 and the exhaust valve 6 are obtained by changing the cam phase with respect to the cam shaft by the variable valve solenoids 22 and 23 of the variable valve timing mechanism provided on the intake side and the exhaust side. The valve timing can be controlled.
[0015]
The intake passage 7 is provided with an electronically controlled throttle valve 19, which controls the amount of fresh intake air. The fuel is supplied by an injector 20 provided in the intake passage 7 for each cylinder (or directly facing each combustion chamber 3). In the combustion chamber 3, the air-fuel mixture is ignited by the spark plug 4 and burned, and is discharged to the exhaust passage 8.
[0016]
Here, the operations of the electronically controlled throttle valve 19, the injector 20, the spark plug 4 (power-trailer built-in ignition coil 21), and the variable valve solenoids 22 and 23 are controlled by an engine control unit (ECU) 30.
[0017]
For these controls, the ECU 30 receives signals from various sensors.
The crank angle sensor 14 outputs a crank angle signal in synchronism with the engine rotation, and thereby can detect the engine speed together with the crank angle position. The cam angle sensors 16 and 17 can detect the cam angles of the intake valve 5 and the exhaust valve 6, thereby detecting the operating states of the variable valve solenoids 22 and 23.
[0018]
An air flow meter 9 that detects the amount of fresh intake air in the intake passage 7, an intake pressure sensor 10 that detects the intake pressure downstream of the electronic control throttle valve 19, and an exhaust pressure sensor 11 that detects the exhaust pressure in the exhaust passage 7. An output signal from a water temperature sensor 15 for detecting the coolant temperature of the engine 1, an accelerator opening sensor 18 for detecting the accelerator opening, and a knock sensor 25 for detecting vibration (particularly knocking vibration) of the engine 1 is also input to the ECU 30, These states can be detected. The knock sensor 25 can detect operational vibrations (such as seating vibrations) of the intake valve 5 and the exhaust valve 6.
[0019]
Further, an ON-OFF signal from the starter switch 26 is also input to the ECU 30.
Next, estimation of the internal EGR amount and the internal EGR rate performed by the ECU 30 will be described below. 2 to 14 are control configuration diagrams, FIGS. 15 to 32 are control flowcharts, FIGS. 33 to 39 and 42 are tables for obtaining each value, and FIGS. 40 and 41 are valve timing change amounts. It is a figure which shows the definition of positive / negative direction.
[0020]
The calculation of the internal EGR rate MRESFR will be described with reference to the control configuration diagram of the internal EGR rate calculating means in FIG. 2 and the internal EGR rate MRESFR calculation flow in FIG.
[0021]
The intake fresh air amount calculation means shown in FIG. 2 calculates the intake fresh air amount (fresh air mass) MACYL, the target combustion equivalent ratio calculation means calculates the target combustion equivalent ratio TFBYA, the internal EGR amount calculation means calculates the internal EGR amount MRES, Based on these calculated values, the internal EGR rate calculating means calculates the internal EGR rate MRESFR.
[0022]
In step 1 of FIG. 15 (denoted as “S1” in the figure, the same applies hereinafter), the intake fresh air amount MACYL per cylinder is calculated based on the intake fresh air amount measured by the air flow meter 9.
[0023]
In step 2, the engine speed detected based on the signal from the crank angle sensor 14, the accelerator opening detected based on the signal from the accelerator opening sensor 18, and the signal from the water temperature sensor 15 are detected. A target combustion equivalent ratio TFBYA determined according to the cooling water temperature is calculated.
[0024]
The target combustion equivalent ratio TFBYA is expressed by the following equation from the target combustion air-fuel ratio when the stoichiometric air-fuel ratio (stoichiometric) is 14.7, and becomes 1 when the target combustion air-fuel ratio is stoichiometric.
[0025]
TFBYA = 14.7 / target combustion air-fuel ratio (1)
Step 3 will be described later FIG. The internal EGR amount MRES per cylinder is calculated according to the flowchart of FIG.
[0026]
In step 4, the internal EGR rate MRESFR (the ratio of the internal EGR amount to the total gas amount per cylinder) is calculated by the following equation, and the process ends.
MRESFR = MRES / {MRES + MACYL × (1 + TFBYA / 14.7)} (2)
Here, regarding the calculation of the internal EGR amount MRES in step 3, the control configuration diagram of the internal EGR amount calculating means in FIG. FIG. The internal EGR amount calculation flow will be described.
[0027]
When the exhaust valve shown in FIG. 3 is closed (shown as “EVC” in the figure), the in-cylinder gas amount calculation means is an overlap between the in-cylinder gas amount MRESCYL, the intake valve 5 and the exhaust valve 6 (“O / The medium blowback gas amount calculation means calculates the blowback gas amount MRESOL, and the internal EGR amount calculation means calculates the internal EGR amount MRES based on these calculated values.
[0028]
In step 5 of FIG. 16, an exhaust valve closing cylinder internal gas amount MRESCYL, which is the amount of gas remaining inside the cylinder when the exhaust valve is closed, is calculated according to the flowchart of FIG. 17 described later.
[0029]
In step 6, an overlapped return gas amount MRESOL, which is the amount of gas returned from the exhaust side to the intake side during overlap, is calculated according to the flowchart of FIG.
[0030]
In step 7, the in-cylinder gas amount MRESCYL when the exhaust valve is closed and the overlapped blow-back gas amount MRESOL are added to calculate the internal EGR amount MRES by the following equation.
[0031]
MRES = MRESCYL + MRESSOL (3)
Here, regarding the calculation of the in-cylinder gas amount MRESCYL when the exhaust valve is closed in step 5, the control configuration diagram of the exhaust gas valve closing-time cylinder gas amount calculating means in FIG. 4 and the exhaust valve closing time in-cylinder of FIG. This will be described using the gas amount MRESCYL calculation flow.
[0032]
The target combustion equivalent ratio calculation means shown in FIG. 4 calculates the target combustion equivalent ratio TFBYA of the exhaust gas, and the exhaust gas constant calculation means calculates the gas constant REX based on this value. The in-cylinder volume calculating means when the exhaust valve is closed calculates the in-cylinder volume VEVC, the in-cylinder temperature calculating means when the exhaust valve is closed is calculated as the in-cylinder temperature TEVC, and the pressure calculating means when the exhaust valve is closed is calculated as the in-cylinder pressure PEVC. Based on these calculated values, the exhaust gas valve closing cylinder interior gas amount calculation means calculates the cylinder gas amount MRESCYL.
[0033]
In step 8 of FIG. 17, the in-cylinder volume VEVC when the exhaust valve is closed is obtained according to the flowchart of FIG.
In step 9, the gas constant REX of the exhaust gas corresponding to the target combustion equivalent ratio TFBYA is obtained from the table shown in FIG. FIG. 33 is an exhaust gas constant REX calculation table, in which the horizontal axis represents the target combustion equivalent ratio TFBYA, and the vertical axis represents the exhaust gas constant REX. Note that dotted lines in FIG. 33 indicate stoichiometry.
[0034]
In step 10, the exhaust valve closing in-cylinder temperature TEVC is estimated according to the flow shown in FIG.
In step 11, based on the exhaust pressure detected based on the signal of the exhaust pressure sensor 11, the exhaust valve closing cylinder pressure PEVC is estimated. The in-cylinder pressure PEVC when the exhaust valve is closed is determined by the mixture volume and the in-pipe resistance of the exhaust system, and may be obtained from a table corresponding to the mixture volume flow rate.
[0035]
In step 12, the calculated exhaust valve closing cylinder volume VEVC, exhaust gas constant REX, exhaust valve closing cylinder temperature TEVC, and exhaust valve closing cylinder pressure PEVC calculated in steps 8 to 11 are calculated. From this, the exhaust gas valve closing cylinder interior gas amount MRESCYL remaining inside the cylinder when the exhaust valve is closed is calculated by the following equation.
[0036]
MRESCYL = (PEVC × VEVC) / (REX × TEVC) (4)
Here, regarding the calculation of the gas amount MRESOL that is blown back from the exhaust side to the intake side during the overlap of step 6 in FIG. 16, the control configuration diagram of the calculation of the blowback gas amount during overlap in FIG. 5 and the blowback during overlap in FIG. This will be described using the gas amount MRESOL calculation flow.
[0037]
In FIG. 5, the target combustion equivalent ratio calculation means calculates the equivalent ratio TFBYA, and the exhaust gas constant calculation means calculates the gas constant REX based on this calculated value. The overlapping effective area calculation means calculates the effective area ASUMOL according to FIG. These calculated values, engine speed calculation means, exhaust gas specific heat ratio calculation means, exhaust valve closing cylinder temperature calculation means, exhaust valve closing cylinder pressure calculation means, intake pressure calculation means, choke excess Based on the calculated values by the supply determination calculation means, the overlapped blowback gas amount calculation means calculates the blowback gas amount MRESOL.
[0038]
In step 13 of FIG. 18, the overlapping effective area ASUMOL is calculated according to the flowchart of FIG. 29 described later.
In step 14, the engine speed NRPM is calculated based on the signal from the crank angle sensor 14.
[0039]
In step 15, the exhaust gas specific heat ratio SHEATR is calculated from the map shown in FIG. This control configuration is shown in FIG.
The target combustion equivalent ratio calculation means shown in FIG. 6 calculates the target combustion equivalent ratio TFBYA, the exhaust valve closing cylinder temperature calculation means calculates the cylinder temperature TEVC, and based on these calculated values, the exhaust gas specific heat ratio calculation means Calculates the exhaust gas specific heat ratio SHEATR.
[0040]
FIG. 34 is an exhaust gas specific heat ratio calculation map, in which the horizontal axis represents the target combustion equivalent ratio TFBYA, and the vertical axis represents the exhaust gas specific heat ratio SHEATR. The dotted line in the figure indicates the stoichiometric position. When the target combustion equivalent ratio TFBYA is in the vicinity of the stoichiometric ratio, the exhaust gas specific heat ratio SHEATR decreases, and when it reaches the rich side or lean side, the specific heat ratio SHEATR increases. A case where the in-cylinder temperature TEVC at the time of closing the exhaust valve changes is indicated by a thick arrow. Here, the exhaust gas specific heat ratio SHEATR is obtained in accordance with the target combustion equivalent ratio TFBYA calculated in step 2 of FIG. 15 and the exhaust valve closing cylinder temperature TEVC calculated in step 10 of FIG.
[0041]
In step 16, a supercharging determination TBCRG and a choke determination CHOKE are performed according to a control block diagram of a supercharging / choke determination means in FIG. 7 described later and a supercharging determination TBCRG / choke determination CHOKE flow in FIG. 19.
[0042]
In step 17, it is determined whether or not the supercharging determination flag TBCRG in step 16 is 0, that is, the supercharging state. When the supercharging determination flag TBCRG is 0, the process proceeds to step 18, and when the supercharging determination flag TBCRG is not 0, the process proceeds to step 21.
[0043]
In step 18, it is determined whether or not the choke determination flag CHOKE in step 16 is 0, that is, the choke state.
If the choke determination flag CHOKE is 0, the process proceeds to step 19 to calculate the blow-back gas flow rate MRESOLtmp during overlap when there is no supercharging and no choke from the flow of FIG.
[0044]
On the other hand, if the choke determination flag CHOKE in step 16 is not 0 in step 18, the process proceeds to step 20, and from the flow of FIG. Is calculated.
[0045]
If the supercharging determination flag TBCRG in step 16 is 1, that is, the supercharging state is set in step 17 and the choke determination flag CHOKE is 0 in step 21, the process proceeds to step 22, and the flow of FIG. From this, the blow-back gas flow rate MRESOLtmp during the overlap with supercharging and without choke is calculated.
[0046]
On the other hand, if the choke determination flag CHOKE in step 16 is 1 in step 21, the process proceeds to step 23, and the blow-back gas flow rate MRESOLtmp with supercharging and with choke is calculated from the flow of FIG.
[0047]
After calculating the blow back gas flow rate MRESOLtmp in steps 19, 20, 22, and 23, the process proceeds to step 24.
In step 24, the amount of blown-back gas MRESOL during overlap is calculated by accumulating the blown-back gas flow rate MRESOLtmp and the integrated effective area ASUMOL during the overlap period according to the state of supercharging and choking. Calculated by the formula.
[0048]
MRESOL = (MRESOLtmp × ASUMOL × 60) / (NRPM × 360) (5)
Here, the supercharging / choke determination in step 16 will be described with reference to the control block diagram of the supercharging / choke determining means in FIG. 7 and the supercharging determination TBCRG / choke determination CHOKE flow in FIG.
[0049]
As shown in FIG. 7, based on the calculated values of the exhaust gas specific heat ratio calculating means, the exhaust valve closing cylinder pressure calculating means, and the intake pressure calculating means, the supercharging / choke determining means determines the supercharging determination TBCRG and the choke determination CHOKE. And do.
[0050]
In step 25 of FIG. 19, the ratio between the intake pressure PIN detected based on the signal of the intake pressure sensor 10 and the exhaust valve closing-time cylinder pressure PEVC calculated in step 11 of FIG. The ratio PINBYEX is calculated by the following equation.
[0051]
PINBYEX = PIN / PEVC (6)
In step 26, it is determined whether or not the intake / exhaust pressure ratio PINBYEX is 1 or less, that is, the supercharging state.
[0052]
When the intake / exhaust pressure ratio PINBYEX is 1 or less, that is, when there is no supercharging, the routine proceeds to step 27, the supercharging determination flag TBCRG is set to 0, and the routine proceeds to step 30.
[0053]
On the other hand, if the intake / exhaust pressure ratio PINBYEX is greater than 1, that is, if there is supercharging, the process proceeds to step 28, the supercharging determination flag TBCRG is set to 1, and the process proceeds to step 29, which is calculated in step 15 of FIG. The exhaust gas specific heat ratio SHEATR is set as the air-fuel mixture specific heat ratio MIXAIRSHR obtained from the table shown in FIG. 35 (SHEATR = MIXAIRSHR).
[0054]
FIG. 35 is an air-fuel mixture specific heat ratio MIXAIRSHR calculation table, in which the horizontal axis represents the target combustion equivalent ratio TFBYA, and the vertical axis represents the air-fuel mixture specific heat ratio MIXAIRSHR. The dotted line in the figure indicates stoichiometry, and the specific heat ratio MIXAIRSHR is large on the lean side and small on the rich side. Then, an air-fuel mixture specific heat ratio MIXAIRSHR corresponding to the target combustion equivalent ratio TFBYA calculated in step 2 of FIG. 15 is obtained from the table.
[0055]
Then, in step 29, the exhaust gas specific heat ratio SHEATR is replaced with the mixture specific heat ratio MIXAIRSHR (SHEATR = MIXAIRSHR), so that the gas flow during the overlap at the time of supercharging such as turbocharging or inertial supercharging is removed from the intake system. Even when going to the exhaust system (blows through), the specific heat ratio of the gas passing through the orifice is changed from the specific heat ratio of the exhaust gas to the specific heat ratio of the intake gas mixture, thereby accurately estimating the amount of gas blown through and the internal EGR amount. Is calculated with high accuracy.
[0056]
In step 30, based on the exhaust gas specific heat ratio SHEATR calculated in step 15 or step 29, the minimum and maximum choke determination threshold values SLCHOKE and SLCHOKEH are calculated by the following equations.
[0057]
SLCHOKEL = {2 / (SHEATR + 1)} ^ {SHEATR / (SHEATR-1)} (7a)
SLCHOKEH = {2 / (SHEATR + 1)} ^ {-SHEATR / (SHEATR-1)} (7b)
The choke determination threshold values SLCHOKE and SLCHOKEH calculate the limit value for choking.
[0058]
In step 30, if the power calculation is difficult due to the control configuration, the calculation results of equations (7a) and (7b) are preliminarily obtained from the minimum choke determination threshold value SLCHOKE table and the maximum choke determination threshold value SLCHOKEH. You may memorize | store it as a table and may obtain | require according to exhaust gas specific heat ratio SHEATR.
[0059]
In step 31, it is determined whether or not the intake / exhaust pressure ratio PINBYEX calculated in step 25 is in a range not less than the minimum choke determination threshold value SLCHOKEEL and not more than the maximum choke determination threshold value SLCHOKEH, that is, the choke state.
[0060]
When the intake / exhaust pressure ratio PINBYEX is within the range, that is, when it is determined that there is no choke, the routine proceeds to step 32 where the choke determination flag CHOKE is set to zero.
[0061]
On the other hand, if the intake / exhaust pressure ratio PINBYEX is not within the range, that is, if it is determined that choke is present, the routine proceeds to step 33, where the choke determination flag CHOKE is set to 1.
[0062]
Further, the calculation of the blowback gas flow rate MRESOLtmp in step 19 of FIG. 18 will be described using the flow of calculation of the blowback gas flow rate during overlap when there is no supercharging and no choke in FIG.
[0063]
In step 34, based on the gas constant REX of the exhaust gas calculated in step 9 of FIG. 17 and the in-cylinder temperature TEVC at the time of closing the exhaust valve calculated in step 10, the gas flow calculation formula density term MRSOLD is calculated as follows. Calculate by the formula.
[0064]
MRSOLD = SQRT {1 / (REX × TEVC)} (8)
Here, SQRT is a coefficient related to temperature and gas constant. If it is difficult to calculate the density term MRSOLD of the gas flow rate calculation formula because of the control configuration, the calculation result of the formula (8) is stored in advance as a map, according to the exhaust gas constant REX and the in-cylinder temperature TEVC. You may ask.
[0065]
In step 35, based on the exhaust gas specific heat ratio SHEATR calculated in step 15 of FIG. 18 and the intake exhaust pressure ratio PINBYEX calculated in step 25 of FIG. 19, the gas flow rate calculation formula pressure difference term MRSOLP is expressed by the following formula. calculate.
[0066]
MRSOLP = SQRT [SHEATR / (SHEATR-1) × {PINBYEX ^ (2 / SHEATR) −PINBYEX ^ ((SHEATR + 1) / SHEATR)}] (9)
In step 36, the exhaust valve closing cylinder pressure PEVC calculated in step 11 of FIG. 17, the gas flow rate calculation formula density term MRSOLD and the gas flow rate calculation formula pressure calculated in steps 34 and 35 of FIG. Based on the difference term MRSOLP, the blowback flow rate MRESOLtmp during the overlap when there is no supercharging and no choke is calculated by the following equation.
[0067]
MRESOLtmp = 1.4 × PEVC × MRSOLD × MRSOLP (10)
Further, the blowback gas flow rate MRESOLtmp in step 20 will be described using the blowback gas flow rate calculation flow with no supercharging and with choke in FIG.
[0068]
In step 37, the gas flow rate calculation formula density term MRSOLD is calculated from the above-described equation (8) as in step 34 of FIG.
In step 38, based on the exhaust gas specific heat ratio SHEATR calculated in step 15 of FIG. 18, the gas flow calculation formula choke pressure difference term MRSOLPC is obtained by the following formula.
[0069]
MRSOLPC = SQRT [SHEATR × {2 / (SHEATR + 1)} ^ {(SHEATR + 1) / (SHEATR-1)}] (11)
If the power calculation is difficult due to the control configuration, the calculation result of equation (11) is stored in advance as a gas flow rate calculation type choke pressure difference term MRSOLPC map, and the exhaust gas specific heat ratio SHEATR is stored. You may ask for it.
[0070]
In step 39, the exhaust valve closing-time cylinder pressure PEVC calculated in step 11 of FIG. 17, the gas flow rate calculation formula density term MRSOLD calculated in step 37 of FIG. 21, and the choke time calculated in step 38. Based on the pressure difference term MRSOLPC, the reflow rate MRESOLtmp during the overlap with no supercharging and with choke is calculated by the following equation.
[0071]
MRESOLtmp = PEVC × MRSOLD × MRSOLPC (12)
The calculation of the average blown gas flow rate MRESOLtmp during the overlap in step 22 will be described using the blown gas flow rate calculation flow with supercharging and without choke in FIG.
[0072]
In step 40, based on the exhaust gas specific heat ratio SHEATR calculated in step 29 of FIG. 19 and the intake exhaust pressure ratio PINBYEX calculated in step 25, the gas flow calculation formula supercharging pressure difference term MRSOLPT is expressed by the following equation. Ask.
[0073]
MRSOLPT = SQRT [SHEATR / (SHEATR-1) × {PINBYEX ^ (− 2 / SHEATR) −PINBYEX ^ (− (SHEATR + 1) / SHEATR)}] (13)
If the power calculation is difficult due to the control configuration, the calculation result of equation (13) is stored in advance as a gas flow rate calculation type supercharging pressure difference term MRSOLPT map, and the exhaust gas specific heat ratio SHEATR and the intake air You may obtain | require according to exhaust pressure ratio PINBYEX.
[0074]
In step 41, on the basis of the intake pressure PIN detected based on the signal of the intake pressure sensor 10 and the supercharging pressure difference term MRSOLPT calculated in step 40, the engine blows back during overlap with supercharging and without choke. The gas flow rate MRESOLtmp is calculated by the following equation.
[0075]
MRESOLtmp = −0.152 × PIN × MRSOLPT (14)
Here, the blow-back gas flow rate MRESOLtmp shows a negative value, which can represent the gas flow rate that blows from the intake system to the exhaust system during the overlap, and the internal EGR amount is reduced based on this.
[0076]
The calculation of the blowback gas flow rate MRESOLtmp in step 23 will be described with reference to the blowback gas flow rate calculation flow during overlap with supercharging and choke in FIG.
[0077]
In step 42, as in step 38 of FIG. 21, the gas flow rate calculation formula choke pressure difference term MRSOLPC is obtained from the formula (11) or a map.
In step 43, based on the intake pressure PIN and the gas flow calculation formula pressure difference term MRSOLPC during choke, the blow-back gas flow rate MRESOLtmp during supercharging and choke is calculated by the following formula.
[0078]
MRESOLtmp = −0.108 × PIN × MRSOLPC (15)
Here, when the blow-back gas flow rate MRESOLtmp shows a negative value, the gas flow rate that blows from the intake side to the exhaust side during the overlap can be expressed, and the internal EGR amount is reduced.
[0079]
Here, in steps 19, 20, 22, and 23, the blow-back gas flow rate MRESOLtmp is calculated according to the state of supercharging and the presence or absence of choke. Then, after calculating the overlapped blow-back gas amount MRESOL in step 24 described above, the process proceeds from step 6 to step 7 in FIG. 16, and in step 7 described above, the internal EGR amount MRES is calculated. Then, the process proceeds from step 3 to step 4 in FIG. 15, the above-described internal EGR rate MRESFR is calculated, and the process ends.
[0080]
Further, regarding the calculation of the cylinder volume VEVC when the exhaust valve is closed in step 8 of FIG. 17, the control configuration diagram of the calculation of the cylinder volume VEVC when the exhaust valve is closed shown in FIG. 8 and the contents of the cylinder when the exhaust valve is closed shown in FIG. This will be described using the product VEVC calculation flow.
[0081]
The in-cylinder volume calculating means shown in FIG. 8 closes the exhaust valve geometrically determined from the piston position when the exhaust valve is closed based on a calculated value VTEOFS of the exhaust valve timing change amount calculating means described later. The valve time cylinder internal volume VEVC is calculated.
[0082]
In step 44 in FIG. 24, an exhaust valve timing change amount VTEOFS, which is a change amount toward the overlap increasing side, that is, the direction in which the exhaust valve closes later, is calculated according to the flowchart of FIG.
[0083]
In step 45, the exhaust valve closing-time cylinder internal volume VEVC is obtained from the table shown in FIG. 36 in accordance with the exhaust valve timing change amount VTEOFS.
FIG. 36 is a table for calculating the in-cylinder volume VEVC when the exhaust valve is closed. The horizontal axis indicates the exhaust valve timing change amount VTEOFS, and the horizontal axis indicates the in-cylinder volume VEVC when the exhaust valve is closed.
[0084]
In an engine having a mechanism for changing the relationship between the position of the piston 2 and the in-cylinder volume VEVC when the exhaust valve is closed, the in-cylinder volume VEVC when the exhaust valve is closed is determined from the table according to the change amount. May be.
[0085]
In an engine having a mechanism for changing the compression ratio, the exhaust valve closing cylinder internal volume VEVC corresponding to the amount of change in the compression ratio may be obtained from a table.
Here, regarding the calculation of the exhaust valve timing change amount VTEOFS in step 44 in FIG. 24, the control configuration diagram of the calculation of the exhaust valve timing change amount VTEOFS in FIG. 9 and the exhaust valve timing change amount VTEOFS calculation flow in FIG. 25 are used. I will explain.
[0086]
In FIG. 9, the exhaust valve timing basic change amount calculating means detects the exhaust valve timing basic change amount (exhaust cam twist angle) detected from the signals of the crank angle sensor 14 and the exhaust side cam angle sensor 17 in accordance with the relative relationship between them. VTCNOWE is calculated. The valve timing change amount correction amount calculation means calculates a valve timing change amount correction amount VTCLE based on the calculated value VCLE of the valve clearance amount calculation means. Then, the exhaust valve timing change amount calculating means calculates the exhaust valve timing change amount VTEOFS based on these calculated values VTCNOWE and VTCLE and the calculated value VTHOSE of the valve timing correction learning value calculating means.
[0087]
In step 46 of FIG. 25, the exhaust valve timing basic change amount (exhaust cam twist angle) VTCNOWE is calculated based on the signals of the crank angle sensor 14 and the exhaust side cam angle sensor 17.
[0088]
In step 47, the valve clearance amount VCLE is calculated according to the flowchart of FIG.
In step 48, an exhaust valve timing change amount correction amount VTCLE is obtained from the table shown in FIG. 37 (a) according to the exhaust valve clearance amount VCLE.
[0089]
FIG. 37A is an exhaust valve timing change amount correction amount VTCLE calculation table, where the horizontal axis represents the exhaust valve clearance amount VCLE, and the vertical axis represents the exhaust valve timing change amount relative to the valve timing at the reference clearance amount (in the steady state). The correction amount VTCLE is shown. According to this, when the clearance amount VCLE of the exhaust valve 6 becomes smaller (toward the left side), the valve closing timing is delayed by VTCLE, and therefore it is necessary to increase and correct the valve timing change amount toward the overlap increasing side. Show.
[0090]
In step 49 of FIG. 25, the valve timing correction learning value VTHOSE is calculated according to the flowchart of FIG. 27 described later.
In step 50, the exhaust valve timing change amount VTEOFS is set to the exhaust valve timing basic change amount (exhaust cam twist angle) VTCNOWE, the exhaust valve timing change correction amount VTCLE based on the change in the valve clearance amount VCLE according to the valve temperature VTMPE, the cam wear / The exhaust valve timing correction learned value VTHOSE based on the learned value of the change in the valve clearance VCLE due to shim wear is added to obtain the following equation.
[0091]
VTEOFS = VTCNOWE + VTCLE + VTHOSE (16)
Here, the calculation of the valve clearance amount VCLE in step 47 will be described with reference to the control configuration diagram of the exhaust valve clearance amount VCLE calculation in FIG. 10 and the valve clearance amount VCLE calculation flow in FIG.
[0092]
The valve clearance amount calculation means of FIG. 10 is based on the calculated value of the valve temperature calculation means for calculating the valve temperature VTMPE from the fuel injection amount corresponding to the intake fresh air amount MACYL calculated based on the signal of the air flow meter 9. A valve clearance amount VCLE is calculated. Here, the valve temperature calculation means calculates the valve temperature VTMPE according to a temperature calculation flow of FIG. The final fuel injection amount TI is based on the actual intake fresh air amount (mass) MACYL detected by the air flow meter 9, and the basic fuel injection amount TP = K × MACYL / NRPM (K is a constant) equivalent to stoichiometry. And is corrected by the target combustion equivalent ratio TFBYA corresponding to the target air-fuel ratio or corrected by the air-fuel ratio feedback correction coefficient LAMBDA as shown in the following equation.
[0093]
TI = TP × TFBYA × LAMBDA (17)
In step 51 of FIG. 26, the valve temperature VTMPE is calculated according to the valve temperature calculation flow of FIG. In this flow, the intake valve 5 and the exhaust valve 6 are calculated independently, but the processing is the same, so the exhaust valve 6 will be described.
[0094]
In step 52, the provisional valve clearance amount VCLEtmp is calculated according to the exhaust valve temperature VTMPE by the following equation.
VCLEtmp = −KVTMPE × (VTMPE−90) + VCLSTDE (18)
Here, -KVTMPE is a coefficient that is relatively determined by the material and length of the exhaust valve 6, and mainly considering the case where the expansion of the valve 6 in the axial direction is large, expansion of other parts (for example, a cylinder head or the like). Is determined without consideration. VCLSTDE is a reference valve clearance amount at a reference temperature (90 ° C. in this case). If the valve temperature VTMPE increases, the clearance amount VCLEtmp decreases.
[0095]
In step 53, it is determined whether or not the provisional valve clearance amount VCLEtmp is 0 or more. If VCLEtmp is 0 or more (VCLEtmp ≧ 0), the process proceeds to step 55. On the other hand, if VTCLEtmp is less than 0 (VCLEtmp <0), the process proceeds to step 54, and the process proceeds to step 55 with VCLEtmp = 0. This is because the valve clearance amount VCLE does not become a negative value.
[0096]
In step 55, the valve clearance amount VCLE is replaced with the provisional valve clearance amount VCLEtmp (VCLE = VCLEtmp).
Next, the calculation of the valve timing correction learned value VTHOSE in step 49 of FIG. 25 will be described using the control configuration diagram of the valve timing correction learned value calculation of FIG. 11 and the valve timing correction learned value VTHOSE calculation flow of FIG. To do.
[0097]
In FIG. 11, the valve timing basic change amount calculation means calculates the valve timing basic change amount (exhaust cam twist angle) VTCNOWE from the signals of the crank angle sensor 14 and the cam angle sensor 17. The valve closing timing estimated value calculating means calculates the valve closing timing estimated value VCLTE based on the valve timing basic change amount VTCNOWE and the valve timing change amount correction amount calculating means VTCLE. On the other hand, the valve closing timing actual value calculation means calculates the valve closing timing actual value VCLTRE from the valve closing timing actual value determination means, and the signals of the crank angle sensor 14 and the knock sensor 25. Then, the valve timing correction learning value calculation means calculates the valve timing correction learning value VTHOSE based on the valve closing timing estimated value VCLTEE and the valve closing timing actual value VCLTRE.
[0098]
In step 56 in FIG. 27, a valve timing actual value calculation permission flag FVTHOSE is calculated according to the flowchart in FIG. 28 described later.
In step 57, it is determined whether or not a valve timing actual value calculation permission flag FVTHOSE is 1. Thus, it is determined whether or not the valve closing timing can be properly detected. If the flag FVTHOSE = 1, the process proceeds to step 58. On the other hand, if the flag FVTHOSE = 0, a return is returned.
[0099]
In step 58, the actual seating timing of the valve 6, that is, the actual valve closing timing is determined by the relative relationship between the signal of the knock sensor 25 that detects vibration generated when the exhaust valve 6 is seated and the signal of the crank angle sensor 14. VCLTRE (degATDC) is calculated.
[0100]
In step 59, the valve closing timing estimated value VCLTE is calculated by adding the valve closing timing VCLTSTDE and the exhaust valve timing variation correction amount VTCLE by the following equation.
[0101]
VCLTEE = VCLTSTDE + VTCLE (degATDC) (19)
Here, VCLTSTDE is the valve closing timing when the basic change amount of the valve timing is 0 in the reference valve clearance amount (the valve clearance amount in the warm state).
[0102]
In step 60, the provisional valve timing correction amount VTHOSEtmp is calculated from the difference (VCLTRE−VCLTEE) between the actual value VCLTRE and the estimated value VCLTEE of the valve closing timing.
[0103]
In step 61, it is determined whether or not the absolute value of the error between the provisional valve timing correction amount VTHOSEtmp and the valve timing correction learned value VTHOSE is equal to or greater than a predetermined value SLVCL. If the absolute value of the error is greater than or equal to the predetermined value SLVCL, the process proceeds to step 62. On the other hand, if it is less than or equal to the predetermined value SLVCL, a return is returned.
[0104]
In step 62, the provisional valve timing correction amount VTHOSEtmp is substituted for the valve timing correction learning value VTHOSE (VTHOSE = VTHOSEtmp).
[0105]
Here, if the error becomes larger on the positive side, the actual valve closing timing is further delayed. Therefore, this error may be added to the valve timing change amount. However, in reality, this error is a negative value because the clearance is enlarged mainly due to shim wear and cam wear, and the actual valve closing timing is advanced.
[0106]
Here, calculation of the valve timing actual value calculation permission flag FVTHOSE in step 56 will be described using the valve timing actual value calculation permission flag FVTHOSE calculation flow of FIG.
[0107]
In step 63, it is determined that the basic change amount of the valve timing is 0 (VTCNOW = 0), in step 64, it is determined that the water temperature is equal to or higher than the predetermined water temperature VTHOSTW, and in step 65, the rotational speed is determined to be equal to or lower than the predetermined rotational speed VTHOSNE. When it is determined at 66 that the throttle opening is equal to or less than the predetermined opening VTHOSTVO, the valve timing actual value calculation permission flag FVTHOSE is set to 1 (FVTHOSE = 1) at step 67. This is for estimating whether the operation state is suitable for calculating the valve timing actual value VCLTRE.
[0108]
On the other hand, if any one of Step 63 to Step 66 is not established, the routine proceeds to Step 68, where the valve timing actual value calculation permission flag FVTHOSE is set to 0 (FVTHOSE = 0). This is because when these conditions are not satisfied, the valve timing actual value VCLTRE is not suitable for calculation.
[0109]
Next, regarding the calculation of the effective area integrated value ASUMOL during overlap in step 13 of FIG. 18, the control configuration diagram of the effective area calculation during overlap of FIG. 12 and the flow of calculating the effective area integrated value during overlap of FIG. It explains using.
[0110]
The effective area integrated value calculation means during overlap in FIG. 12 calculates the effective area calculation value ASUMOL during overlap based on the calculation results of the intake valve timing change amount calculation means and the exhaust valve timing change amount calculation means.
[0111]
In step 69 of FIG. 29, the intake valve timing change amount VTIOFS is calculated according to the flowchart of FIG.
In step 70, the exhaust valve timing change amount VTEOFS is calculated according to the flowchart of FIG.
[0112]
In step 71, the effective area integrated value ASUMOL during overlap is obtained from the effective area integrated value calculation map during overlap shown in FIG. 38 according to the intake valve timing change amount VTIOFS and the exhaust valve timing change amount VTEOFS.
[0113]
FIG. 38 is a characteristic diagram regarding the effective area during the overlap, and the horizontal axis represents the intake valve timing variation VTIOFS, and the vertical axis represents the exhaust valve timing variation VTEOFS. When the intake valve timing change amount VTIOFS and the exhaust valve timing change amount VTEOFS are increased, the overlap change amount is increased, and the effective area integrated value ASUMOL is increased.
[0114]
Here, FIG. 39 is an explanatory diagram of the effective area integrated value ASUMOL during overlap, where the horizontal axis indicates the crank angle and the vertical axis indicates the opening area of the intake valve 5 and the exhaust valve 6. The effective opening area at a certain point during the overlap is the smaller of the exhaust valve opening area and the intake valve opening area. That is, the effective area integrated value ASUMOL in the entire period during the overlap is an integral value (shaded portion in the drawing) during the period in which the intake valve 5 and the exhaust valve 6 are open. Thus, by calculating the overlapping effective area integrated value ASUMOL, the overlap amount between the intake valve 5 and the exhaust valve 6 can be simulated as one orifice (outflow hole), and the state of the exhaust system Intake system From this state, the flow rate passing through this orifice can be simply calculated.
[0115]
Next, regarding the calculation of the intake valve timing change amount VTIOFS in step 69 of FIG. 29, the control configuration diagram of the intake valve timing change amount VTIOFS calculation of FIG. 13 and the intake valve timing change amount VTIOFS calculation flow of FIG. explain. Note that the intake valve 5 is described as having a large overlap amount, that is, a case where the valve opening timing is advanced.
[0116]
In FIG. 13, the intake valve timing basic change amount calculating means calculates the intake valve timing basic change amount (intake cam twist angle) VTCNOW from the signals of the crank angle sensor 14 and the intake side cam angle sensor 16. The valve timing change amount correction amount calculation means calculates the valve timing change amount correction amount VTCLI based on the calculated value VCLI of the valve clearance amount calculation means. Then, the intake valve timing change amount calculation means calculates the intake valve timing change amount VTEOFS based on the intake valve timing basic change amount VTCNOW, the valve timing change amount correction amount VTCLI, and the valve timing correction learning value calculation means calculated value VTHOSI. To do.
[0117]
In step 72 of FIG. 30, the intake valve timing basic change amount (intake cam twist angle) VTCNOW is calculated based on the signals of the crank angle sensor 14 and the intake side cam angle sensor 16.
[0118]
In step 73, the intake valve clearance amount VCLI is calculated from the valve temperature VTMPI according to the flowchart of FIG. Here, the provisional valve clearance amount VCLItmp calculated in step 52 is calculated by the following equation according to the intake valve temperature VTMPI.
[0119]
VCLItmp = −KVTMPI × (VTMPI−90) + VCLSTDI (20)
Here, -KVTMPI is a coefficient that is relatively determined by the material and length of the intake valve 5, and mainly considering the case where the expansion of the valve 5 in the axial direction is large, the expansion of other parts (for example, the cylinder head or the like). Is determined without consideration. VCLSTDI is a reference valve clearance amount (clearance amount when warm (about 90 ° C.)).
[0120]
In step 74, the intake valve timing change amount correction amount VTCLI is obtained from the table shown in FIG. 37 (b) according to the intake valve clearance amount VCLI.
[0121]
FIG. 37B is an intake valve timing change amount correction amount VTCLI calculation table, where the horizontal axis indicates the intake valve clearance amount VCLI, and the vertical axis indicates the intake valve timing change amount correction amount VTCLI with respect to the valve timing at the reference clearance amount. ing. According to this, if the clearance amount VCLI of the intake valve 5 is reduced, the valve opening timing is advanced by VTCLI, so that it is necessary to increase and correct the valve timing change amount toward the overlap increasing side.
[0122]
In step 75, the intake valve timing correction learning value VTHOSI is calculated according to the flowchart of FIG. Here, in step 58 of FIG. 27, when the intake valve 5 moves away from the valve seat, that is, when the lifter of the intake valve 5 collides with the cam, the signal of the knock sensor 25 and the signal of the crank angle sensor 14 are detected. The valve lift timing, that is, the actual valve opening timing value VCLTRI (degBTDC) is calculated based on the relative relationship between the valve lift timing and the valve lift timing.
[0123]
In step 59, the valve opening timing estimated value VCLTEI is calculated by adding the valve timing change amount correction amount VTCLI to the valve opening timing estimated value VCLTSTDI according to the following equation.
[0124]
VCLTEI = VCLTSTDI + VTCLI (degBTDC) (21)
Here, the valve opening timing estimated value VCLTSTDI is the valve opening timing when the basic change amount (intake cam twist angle) of the intake valve timing in the reference valve clearance amount (warm) is zero.
[0125]
In step 60, the provisional valve timing correction amount VTHOSItmp is calculated according to VCLTRI-VCLTEI. This error is mainly due to shim wear and cam wear, and the amount of clearance increases and the actual valve opening timing is delayed. Therefore, it shows a negative value. At this time, since the valve opening timing is delayed, the valve timing change amount is canceled.
[0126]
In step 76, the intake valve timing change amount VTIOFS is set to the intake valve timing change amount correction amount VTCLI based on the change in the intake valve timing basic change amount (intake cam twist angle) VTCNOW and the valve clearance amount VCLI according to the valve temperature VTMPI of the intake valve 5. The intake valve timing correction learning value VTHOSI based on the learned value of the change in the valve clearance amount VCLI due to cam wear and shim wear is added to calculate the following equation.
[0127]
VTIOFS = VTCNOW + VTCLI + VTHOSI (22)
Here, FIG. 40 is a diagram showing the definition of the positive / negative direction of the exhaust valve timing change amount, and FIG. 41 is a diagram showing the definition of the positive / negative direction of the intake valve timing change amount.
[0128]
In FIG. 40, the amount of change in the exhaust valve timing is positive on the advance side (clockwise). In FIG. 41, the amount of change in intake valve timing is positive on the retard side (counterclockwise). Both the intake valve 5 and the exhaust valve 6 are in the direction of increasing the overlap amount.
[0129]
Next, regarding the calculation of the exhaust valve closing cylinder temperature TEVC in step 10 of FIG. 17 and the calculation of the exhaust valve temperature VTMPE and the intake valve temperature VTMPI in step 51 of FIG. 26, the temperatures TEVC, VTMPE, This will be described using the control configuration diagram of VTMPI calculation and the temperature TEVC, VTMPE, and VTMPI calculation flow of FIG.
[0130]
The equilibrium temperature calculation means in FIG. 14 calculates the in-cylinder equilibrium temperature TEQEVC, the exhaust valve equilibrium temperature VTMPEQE, and the intake valve equilibrium temperature VTMPEQI, which are the in-cylinder temperature or valve temperature in the steady state, based on the engine operating state. Then, the difference calculating means includes in-cylinder temperature TEVC (-1), exhaust valve temperature VTMPE (-1), intake valve temperature VTMPI (-1), in-cylinder equilibrium temperature TEQEVC, exhaust valve equilibrium temperature VTMPEQE in the previous cycle, Differences TDEVC, VTMPDE, and VTMPDI from the intake valve equilibrium temperature VTMPEQI are calculated. On the other hand, the responsiveness calculating means calculates predetermined ratios KTEVC, KVTMPE, KVTMPI of the in-cylinder temperature TEVC, the exhaust valve temperature VTMPE, and the intake valve temperature VTMPI. Then, the integration calculation means integrates the predetermined ratios KTEVC, KVTMPE, KVTMPI of the responsiveness calculation means to the difference values TDEVC, VTMPDE, VTMPDI of the difference calculation means. And an addition calculating means adds each temperature TEVC (-1), VTMPE (-1), VTMPI (-1) in the previous cycle, and the integrated value of the integrating calculating means.
[0131]
In step 77 of FIG. 31, it is determined whether or not an ON signal is input from the starter switch 26. If the ON signal has been input, the routine proceeds to step 78 where the in-cylinder temperature TEVC and the valve temperatures VTMPE, VTMPI are set to the cooling water temperature TWN and initialized. On the other hand, if it is not time to switch from OFF to ON, the routine proceeds to step 79.
[0132]
In step 79, a heat generation amount FHEAT (cal / sec) at a predetermined time in the engine is calculated from a heat generation amount calculation flow shown in FIG.
In step 80, in-cylinder equilibrium temperature TEQEVC and valve equilibrium temperatures VTMPEQE and VTMPEQI are obtained from the table shown in FIG. 42 according to the heat generation amount FHEAT.
[0133]
FIG. 42 is a calculation table for each part equilibrium temperature TEQEVC, VTMPEQE, and VTMPEQI, where the horizontal axis indicates the heat generation amount FHEAT, and the vertical axis indicates the in-cylinder equilibrium temperature TEQEVC, the exhaust valve equilibrium temperature VTMPEQE, and the intake valve equilibrium temperature VTMPEQI.
[0134]
In step 81, as shown in the following equation, each part difference value is set as a difference between each part equilibrium temperature TEQEVC, VTMPEQE, VTMPEQI and each part temperature TEVC (-1), VTMPE (-1), VTMPI (-1) in the previous cycle. Calculate TDEVC, VTMPDE, and VTMPDI.
[0135]
TDEVC = TEQEVC-TEVC (-1) (23a)
VTMPDE = VTMPEQE−VTMPE (−1) (23b)
VTMPDI = VTMPEQI−VTMPI (−1) (23c)
In Step 82, the process proceeds to Step 83 only when the REF signal for each fuel injection cycle (for example, 180 ° for the 4-cylinder, 120 ° for the 6-cylinder) is input from the crank angle sensor 14.
[0136]
In step 83, each part temperature TEVC (-1), VTMPE (-1), VTMPI (-1) of the previous cycle is individually changed in accordance with each part difference value TDEVC, VTMPDE, VTMPDI as shown in the following equation. The in-cylinder temperature TEVC, the exhaust valve temperature VTMPE, and the intake valve temperature VTMPI are calculated by adding the values obtained by integrating the ratios KTEVC, KVTMPE, and KVTMPI indicating the responsiveness set to.
[0137]
TEVC = TEVC (−1) + TDEVC × KTEVC (24a)
VTMPE = VTMPE (-1) + VTMPDE × KVTMPE (24a)
VTMPI = VTMPI (-1) + VTMPDI × KVTMPI (24a)
Here, the ratios KTEVC, KVTMPE, and KVTMPI indicating the responsiveness are set to a larger value as the specific heat of the temperature measurement portion is smaller, and individually set so that the responsiveness to each part equilibrium temperature TEQEVC, VTMPEQE, and VTMPEQI is accelerated. Is done.
[0138]
Next, calculation of the heat generation amount FHEAT in step 79 of FIG. 31 will be described using the heat generation amount calculation flow of FIG.
In step 84, it is determined whether the target combustion equivalent ratio TFBYA is greater than 1 (TFBYA> 1), that is, whether the air-fuel ratio is rich. If it is rich (TFBYA> 1), the process proceeds to step 85, and the target combustion equivalent ratio TFBYAHT for calorific value calculation is set to 1. This is because even if the air-fuel ratio is rich, it contributes to the actual heat generation because it is the same as the heat generation amount at the stoichiometric air-fuel ratio. On the other hand, when the target combustion equivalent ratio TFBYA is 1 or less (TFBYA ≦ 1), the routine proceeds to step 86, where the heat generation amount calculation target equivalent ratio TFBYAHT is set to the target combustion equivalent ratio TFBYA (TFBYAHT = TFBYA).
[0139]
In step 87, the heat generation amount FHEAT is calculated by the following equation.
FHEAT = (TFBYAHT × HBN− (TFBYA−TFBYAHT) × HUBN) × TP × NRPM × K (25)
Here, HBN is the calorific value (cal / sec) when the fuel per unit injection pulse width is completely burned. HUBN is the latent heat of vaporization (cal / sec) when the fuel per unit injection pulse width is completely vaporized. TP indicates a basic injection pulse width (ms) equivalent to stoichiometric per one cylinder cycle, and is a value calculated based on the intake air amount. The rotational speed NRPM (rpm) is a value calculated based on the signal of the crank angle sensor 14. K is a coefficient indicating how many times the fuel is injected per revolution, and a value of 2 is substituted for 4 cylinders, and a value of 3 is substituted for 6 cylinders. Each value is substituted according to the number of cylinders.
[0140]
According to this embodiment, the means (steps 10 and 83) for estimating the in-cylinder temperature TEVC when the exhaust valve is closed, the means (step 11) for calculating the in-cylinder pressure PEVC when the exhaust valve is closed, and the combustion Based on the means (step 9) for calculating the gas constant REX of the exhaust gas composition corresponding to the air-fuel ratio, and at least the cylinder temperature TEVC, the cylinder pressure PEVC, and the gas constant REX, the cylinder gas amount when the exhaust valve is closed Means for calculating MRESCYL (step 12), means for calculating the blow-back gas amount MRESOL during the overlap of the exhaust valve opening period and the intake valve open period (step 24), the in-cylinder gas amount MRESCYL and the blow-back gas amount MRESOL And a means (step 7) for calculating the internal EGR amount MRES on the basis of Means (step 80) for calculating the in-cylinder equilibrium temperature TEQEVC that is the in-cylinder temperature in the steady state based on the state, and the estimated in-cylinder temperature TEVC with a time delay with respect to the change in the in-cylinder equilibrium temperature TEQEVC And means for calculating (steps 81 to 83). Therefore, in particular, in the transient operation state, the in-cylinder temperature TEVC inside the cylinder changes every moment, but the internal EGR amount MRES can be calculated based on the changing in-cylinder temperature TEVC. The estimation accuracy of the internal EGR amount MRES at the time can be improved, and drivability and fuel consumption / exhaust can be improved by appropriately setting the ignition timing, the fuel injection amount, and the valve opening / closing timing. Based on the state quantity (temperature TEVC, pressure PEVC, gas constant REX) inside the cylinder after the end of combustion, the internal EGR amount MRES can be calculated from the physical equation. Furthermore, it is possible to cope with a density change due to a temperature / pressure change and a density change due to a gas constant change accompanying a combustion air-fuel ratio change.
[0141]
Further, according to the present embodiment, the in-cylinder equilibrium temperature calculating means calculates the heat generation amount FHEAT per predetermined time based on the parameters related to the heat generation amount FHEAT in the engine (target combustion equivalent ratio TFBYA, basic injection amount TP, rotation speed NRPM). Means (steps 79 and 87), and means (step 80) for estimating the in-cylinder equilibrium temperature TEQEVC based on the calorific value FHEAT per predetermined time. Therefore, even during full-open operation or during rich combustion immediately after start-up, the fuel that is not oxidized does not generate heat, and the increase in the estimation error of the in-cylinder temperature TEVC due to this fuel can be prevented, and the internal EGR amount MRES is more accurate. It can be estimated well and can improve drivability and improve fuel economy and exhaust.
[0142]
Further, according to the present embodiment, the in-cylinder temperature estimated value calculating means calculates the difference TDEVC between the in-cylinder equilibrium temperature TEQEVC and the previous in-cylinder temperature estimated value TEVC (−1) (step 81), and the previous time. Means for adding a predetermined ratio (TDEVC × KTEVC) of the difference TDEVC to the estimated in-cylinder temperature TEVC (−1) and updating the estimated in-cylinder temperature TEVC with a first-order lag (steps 82 and 83). Composed. For this reason, the estimation accuracy of the in-cylinder temperature TEVC can be improved and the internal EGR amount MRES can be improved even when the equilibrium temperature changes suddenly due to a fuel cut, or during a transient in which the balance between the heat generation amount and the heat dissipation amount is lost, such as during startup and acceleration. Can be estimated accurately, and fuel consumption, exhaust and drivability can be prevented from being deteriorated.
[0143]
Further, according to the present embodiment, the in-cylinder temperature estimated value update means updates the in-cylinder temperature estimated value for each fuel injection cycle (step 82). For this reason, the rise or fall of the in-cylinder temperature is performed for each calorific value due to combustion in response to the input of the REF signal of the crank angle sensor 14, and can be followed in accordance with the phenomenon of the transient state.
[0144]
Further, according to the present embodiment, the in-cylinder temperature estimated value calculating means includes an initial setting means for initially setting the in-cylinder temperature estimated value TEVC based on the engine coolant temperature TWN when the engine is started (step) 78). For this reason, the in-cylinder temperature TEVC when the engine is stopped converges to the cooling water temperature TWN, so that the temperature can be estimated immediately after starting.
[0145]
Further, according to the present embodiment, the valve timing variable mechanisms (variable valve solenoids) 22 and 23 for changing the opening / closing timings of the exhaust valve 6 and the intake valve 5, and the opening / closing timing change amounts VTEOFS of the valve timing variable mechanisms 22 and 23, A means for calculating the valve timing based on VTIOFS, a means for estimating the in-cylinder temperature TEVC when the exhaust valve is closed calculated by the valve timing calculation means (steps 10 and 83), and a valve timing calculation means. Means for calculating in-cylinder pressure PEVC when the exhaust valve is closed (step 11), means for calculating a gas constant REX of the exhaust gas composition corresponding to the combustion air-fuel ratio (step 9), at least in-cylinder temperature TEVC, cylinder Based on the internal pressure PEVC and gas constant REX, the in-cylinder gas amount when the exhaust valve is closed Means for calculating RESCYL (steps 5 and 12), means for calculating the blowback gas amount MRESOL during the overlap of the exhaust valve opening period and the intake valve opening period based on the calculation result of the valve timing calculation means (step 6, 24) and means (step 7) for calculating the internal EGR amount MRES based on the in-cylinder gas amount MRESCYL and the blow-back gas amount MRESSOL, and the valve timing calculating means estimates the valve temperatures VTMPE and VTMPI. Means (step 51), means for estimating the valve clearance amount VCLE according to the estimated valve temperature values VTMPE and VTMPI (steps 47 and 55), and means for correcting the valve timing based on the valve clearance amount VCLE (step 48, 49), and The lube temperature estimating means calculates the valve equilibrium temperatures VTMPEQE and VTMPEQI which are the valve temperatures VTMPE and VTMPI in the steady state based on the engine operating state (step 80), and takes time with respect to changes in the valve equilibrium temperatures VTMPEQE and VTMPEQI. Means for calculating the valve temperature estimated values VTMPE and VTMPI with a delay (steps 81 to 83). Therefore, in particular, in the transient operation state, the valve temperatures VTMPE and VTMPI of the exhaust valve 6 or the intake valve 5 change every moment, and the internal EGR amount MRES is based on the changing valve temperatures VTMPE and VTMPI. Therefore, it is possible to improve the estimation accuracy of the internal EGR amount MRES during transient operation, and to improve drivability and fuel efficiency / exhaust by appropriately setting the ignition timing, fuel injection amount, and valve opening / closing timing. .
[0146]
Further, according to the present embodiment, the valve equilibrium temperature calculation means calculates the heat generation amount FHEAT for each predetermined time based on the parameters related to the heat generation amount FHEAT in the engine (target combustion equivalent ratio TFBYA, basic injection amount TP, rotation speed NRPM). And means for calculating the valve equilibrium temperatures VTMPEQE and VTMPEQI based on the calorific value FHEAT per predetermined time (step 80). For this reason, even during full-open operation or during rich combustion immediately after start-up, the fuel that is not oxidized does not generate heat, the increase in valve temperature estimation error due to this fuel can be prevented, and the internal EGR amount can be estimated more accurately. , Improving drivability and improving fuel economy and exhaust.
[0147]
Further, according to the present embodiment, the valve temperature estimated value calculating means calculates the differences VTMPDE and VTMPDI between the valve equilibrium temperatures VTMPEQE and VTMPEQI and the previous valve temperature estimated values VTMPE (-1) and VTMPE (-1). (Step 81) and the previous estimated valve temperature values VTMPE (-1) and VTMPE (-1) are added with a predetermined ratio (VTMPDE × KVTMPE, VTMPDI × KVTMPI) of the difference VTMPDE and VTMPDI to estimate the valve temperature based on the first order delay. Means for updating the values VTMPE and VTMPI (steps 82 and 83). For this reason, the estimated accuracy of the valve temperatures VTMPE and VTMPI can be improved even when the valve equilibrium temperatures VTMPEQE and VTMPEQI change suddenly due to fuel cuts, or during transitions where the balance between the amount of heat generated and the amount of heat released is lost during startup and acceleration. In addition, the internal EGR amount MRES can be accurately estimated, and deterioration of fuel consumption, exhaust, and drivability can be prevented.
[0148]
Further, according to the present embodiment, the valve temperature estimated value update means updates the valve temperature estimated values VTMPE and VTMPI for each fuel injection cycle (step 82). For this reason, the valve temperatures VTMPE and VTMPI are increased or decreased by the input of the REF signal of the crank angle sensor 14 for each calorific value due to combustion, and can be followed in accordance with a transient phenomenon.
[0149]
Further, according to the present embodiment, the estimated valve temperature calculation means includes an initial setting means for initially setting the estimated valve temperature values VTMPE and VTMPI based on the engine coolant temperature TWN when the engine is started (step) 78). For this reason, the valve temperatures VTMPE and VTMPI when the engine is stopped converge to the temperature TWN of the cooling water, so that the temperature can be estimated immediately after starting.
[0150]
Further, according to the present embodiment, the valve temperature estimating means (step 51), the valve clearance estimating means (step 47), and the valve timing correcting means (steps 48 and 49) are independent for each of the intake valve 5 and the exhaust valve 6. Provided. For this reason, even if the valve clearance amounts VCLE and VCLI are different from each other due to the temperature range of the intake valve 5 and the exhaust valve 6 being different and the materials of the valves 5 and 6 being different, the valve timing change amount is also different. VTEOFS and VTIOFS are calculated, and the internal EGR amount MRES can be accurately estimated. And even if the valve timing is different due to the design of the intake / exhaust cam profile, the valve timing can be calculated in consideration of the valve timing correction amounts VTHOSE and VTHOSI according to the valve clearance amounts VCLE and VCLI, and the internal EGR can be accurately calculated. The quantity MRES can be estimated.
[0151]
Further, according to the present embodiment, the valve timing correction means includes means (step 58) for detecting the actual valve timings VCLTRE and VCLTRI based on the operating vibrations of the valves 5 and 6 under predetermined conditions (steps 63 to 66). Means (step 59) for estimating the valve timing corrected by the valve clearance amounts VCLE and VCLI under predetermined conditions (steps 63 to 66), and the actual valve timings VCLTRE and VCLTRI and the estimated valve timings VCLTEE and VCLTEI Means (step 60) for calculating errors VTHOSEtmp and VTHOSItmp, and means (step 49) for calculating valve timing correction learning values VTHOSE and VTHOSI based on the errors VTHOSEtmp and VTHOSItmp. Further, the valve timing correction learning value VTHOSE the lube timing corrected by VTHOSI (step 50). For this reason, it is possible to detect vibrations of the valves 5 and 6 with high accuracy (low rotation range where seating noise can be detected with high accuracy, low load range where knocking does not occur, valve timing basic variation that is unlikely to cause valve timing error is 0 and warm. The actual valve timing (valve closing timing actual value) VCLTRE and VCLTRI can be detected in the area after the machine). The error between the actual valve timings VCLTRE and VCLTRI based on the detected value of the valve vibration and the estimated valve timings (valve closing timing estimated values) VCLTEE and VCLTEI is due to wear. In this case, since the valve timing is uniformly affected, the error due to deterioration with time can be prevented by correcting the error in advance.
[0152]
Further, according to the present embodiment, the actual valve timing calculation means (step 58) detects the operation vibration of the valve by the knock sensor 25. For this reason, the vibration of the actual valve timing can be detected by the input of the existing knock sensor 25, and the cost can be reduced.
[0153]
Further, according to the present embodiment, the in-cylinder gas amount calculating means when the exhaust valve is closed includes means for calculating the in-cylinder volume VEVC when the exhaust valve is closed (steps 8 and 45), and the in-cylinder gas amount when the exhaust valve is closed. It comprises temperature estimation means (steps 10 and 83), exhaust valve closing cylinder pressure calculation means (step 11), and gas constant calculation means (step 9), and based on these calculated values. The in-cylinder gas amount MRESCYL when the exhaust valve is closed is calculated from the physical equation (step 24). Therefore, taking into account the cylinder volume VEVC when the exhaust valve is closed, the internal EGR amount MRES is accurately calculated from the physical equation based on the state quantity (volume VEVC, temperature TEVC, pressure PEVC, gas constant REX) inside the cylinder. Can be estimated well. Even in the case of control construction including multidimensional parameters, the internal EGR amount MRES is calculated based on the physical formula in accordance with each parameter, so that construction can be easily performed and adaptation becomes easy.
[0154]
Further, according to the present embodiment, the overlapping blow-back gas amount calculating means (steps 6 and 24) includes the exhaust valve closing cylinder temperature estimation means (steps 10 and 83) and the exhaust valve closing cylinder pressure. Calculation means (step 11), gas constant calculation means (step 9), means for calculating the intake pressure PIN (step 25), and means for calculating the specific heat ratio SHEATR corresponding to the exhaust gas composition change (steps 15 and 29) ), Means for calculating the effective area integrated value ASUMOL during the overlap between the exhaust valve opening period and the intake valve opening period (step 13), means for calculating the engine speed NRPM (step 14), and supercharging TBCRG And means for determining the presence or absence of choke CHOKE (steps 17, 18, and 20), and based on these calculated values, Calculating the blown-back gas amount MRESOL during Rappu. For this reason, the blow-back gas amount MRESOL can be calculated with high accuracy in accordance with the state amount (overspeed NRPM, exhaust gas specific heat ratio SHEATR, supercharging TBCRG, choke CHOKE) during the overlap. And it can respond to the density change by the change of a state quantity, and the orifice passage volume flow rate change, and can calculate the blow-back gas amount MRESOL during overlap with high accuracy in any operation state.
[0155]
In the present embodiment, the variable valve timing mechanism is provided for both the intake valve 5 and the exhaust valve 6. However, the present invention is not limited to this, and any one of the lift characteristics of the intake valve 5 and the exhaust valve 6 has a lift characteristic. The present invention can be applied to a variable valve overlap amount.
[Brief description of the drawings]
FIG. 1 is a system configuration diagram of an internal EGR amount estimation apparatus.
FIG. 2 is a control configuration diagram of internal EGR rate calculation means.
FIG. 3 is a control configuration diagram of internal EGR amount calculation means.
FIG. 4 is a control configuration diagram of the cylinder gas amount calculation means when the exhaust valve is closed.
FIG. 5 is a control configuration diagram for calculating the amount of blown back gas during overlap.
FIG. 6 is a control configuration diagram of exhaust gas specific heat ratio calculation means.
FIG. 7 is a control configuration diagram of supercharging / choke determining means.
FIG. 8 is a control configuration diagram for calculating the cylinder volume when the exhaust valve is closed.
FIG. 9 is a control configuration diagram for calculating an exhaust valve timing change amount.
FIG. 10 is a control configuration diagram for calculating an exhaust valve clearance amount.
FIG. 11 is a control configuration diagram for calculating a valve timing correction learning value.
FIG. 12 is a control configuration diagram for calculating an effective area during overlap.
FIG. 13 is a control configuration diagram for calculating an intake valve timing change amount;
FIG. 14 is a control configuration diagram for temperature estimation calculation.
FIG. 15: Internal EGR rate calculation flow
FIG. 16: Internal EGR amount calculation flow
FIG. 17 Flow of calculating in-cylinder gas amount when exhaust valve is closed
FIG. 18 Flow of calculating the amount of blown back gas during overlap
FIG. 19: Supercharge determination / choke determination flow
FIG. 20: Flow of calculation of blown gas flow when there is no supercharging and no choke
[Fig.21] Flow of calculation of blow-back gas flow when there is no supercharging and choke
[Fig.22] Flow of calculation of blown back gas flow with supercharging and without choke
[Fig. 23] Flow of calculation of blow-back gas flow with supercharging and with choke
FIG. 24 Flow of calculating cylinder volume when exhaust valve is closed
FIG. 25 is an exhaust valve timing change calculation flow.
FIG. 26: Valve clearance amount calculation flow
FIG. 27 is a flowchart for calculating a valve timing correction learning value.
FIG. 28 is a flowchart for calculating an actual valve timing value permission flag.
FIG. 29 is a flow for calculating the accumulated effective area during overlap.
FIG. 30 is an intake valve timing change calculation flow.
FIG. 31: Temperature calculation flow
FIG. 32: Heat generation amount calculation flow
FIG. 33: Exhaust gas constant calculation table
FIG. 34: Exhaust gas specific heat ratio calculation table
FIG. 35: Mixture specific heat ratio calculation table
FIG. 36: In-cylinder volume calculation table when exhaust valve is closed
FIG. 37: Exhaust / intake valve timing change amount correction amount calculation table
Fig. 38 Effective area characteristics during overlap
FIG. 39 is an explanatory diagram of an integrated effective area value during overlap.
FIG. 40 is a diagram showing the definition of the positive / negative direction of the exhaust valve timing variation.
FIG. 41 is a diagram showing the definition of the positive / negative direction of the intake valve timing change amount.
FIG. 42 is a characteristic diagram showing the relationship between the calorific value and the equilibrium temperature.
[Explanation of symbols]
1 engine
5 Intake valve
6 Exhaust valve
9 Air flow meter
10 Intake pressure sensor
11 Exhaust pressure sensor
14 Crank angle sensor
15 Water temperature sensor
16 Intake side cam angle sensor
17 Exhaust side cam angle sensor
18 Accelerator position sensor
25 knock sensor
26 Starter switch
30 ECU

Claims (15)

A variable valve timing mechanism for changing the opening / closing timing of at least one of the exhaust valve and the intake valve;
Means for calculating the valve timing based on the opening / closing timing change amount of the valve timing variable mechanism;
Means for estimating an in-cylinder temperature when the exhaust valve is closed, calculated by the valve timing calculating means;
Means for calculating an in-cylinder pressure when the exhaust valve is closed calculated by the valve timing calculating means;
Means for calculating the gas constant of the exhaust gas composition according to the combustion air-fuel ratio;
Means for calculating an in-cylinder gas amount when the exhaust valve is closed based on at least the in-cylinder temperature, the in-cylinder pressure, and the gas constant;
Means for calculating the amount of blown back gas during the overlap between the exhaust valve opening period and the intake valve opening period calculated by the valve timing calculating means;
Means for calculating an internal EGR amount based on the in-cylinder gas amount and the blow-back gas amount;
Comprising
The valve timing calculation means includes means for estimating the valve temperature, means for estimating the valve clearance according to the estimated value of the valve temperature, and means for correcting the valve timing based on the valve clearance,
The valve temperature estimating means calculates a valve equilibrium temperature which is a valve temperature in a steady state based on an engine operating state, and calculates a valve temperature estimated value with a time delay with respect to the change of the valve equilibrium temperature. Means for estimating the internal EGR amount of an internal combustion engine. The valve equilibrium temperature calculation means includes means for calculating a heat generation amount per predetermined time based on a parameter relating to a heat generation amount in the engine, and means for estimating a valve equilibrium temperature based on the heat generation amount per predetermined time. The internal EGR amount estimation apparatus for an internal combustion engine according to claim 1, comprising: The valve temperature estimated value calculation means includes means for calculating a difference between the valve equilibrium temperature and the previous valve temperature estimated value, and adds a predetermined ratio of the difference to the previous valve temperature estimated value to cause the valve temperature by a primary delay. The internal EGR amount estimation device for an internal combustion engine according to claim 1 or 2 , comprising means for updating the estimated value. 4. The internal EGR amount estimation device for an internal combustion engine according to claim 3, wherein the valve temperature estimated value update means updates the valve temperature estimated value for each fuel injection cycle. The valve temperature estimation value calculation unit of claim 1 to claim 4, characterized in that it is configured to include an initialization means for initializing the valve temperature estimate based on the engine coolant temperature when starting the engine The internal EGR amount estimation apparatus for an internal combustion engine according to any one of the above. It said valve temperature estimation means, the valve clearance estimation means, and valve timing correcting means, to any one of claims 1 to 5, characterized in that it is provided independently for each of the intake and exhaust valves The internal EGR amount estimation apparatus for an internal combustion engine as described. The valve timing correction means includes means for calculating actual valve timing based on valve operating vibration under predetermined conditions, means for estimating valve timing after correction by valve clearance under predetermined conditions, and the actual valve timing. And means for calculating an error between the estimated valve timing and a means for calculating a valve timing correction learning value based on the error, wherein the valve timing is further corrected by the valve timing correction learning value. The internal EGR amount estimation apparatus for an internal combustion engine according to any one of claims 1 to 6 . 8. The internal EGR amount estimation device for an internal combustion engine according to claim 7 , wherein the operation vibration of the valve is detected by a knock sensor. The in-cylinder gas amount calculating means when the exhaust valve is closed includes means for calculating an in-cylinder volume when the exhaust valve is closed, in-cylinder temperature estimating means when the exhaust valve is closed, and in-cylinder when the exhaust valve is closed a pressure calculating means is configured to include a said gas constant calculating means, according to claim 1, based on these calculated values, the physical equation and calculates an in-cylinder gas amount during the exhaust valve closing The internal EGR amount estimation apparatus for an internal combustion engine according to any one of claims 8 to 9 . The overlapped blow-back gas amount calculating means includes the exhaust valve closing cylinder temperature estimating means, the exhaust valve closing cylinder pressure calculating means, the gas constant calculating means, and an intake pressure calculating means. Means for calculating a specific heat ratio corresponding to an exhaust gas composition change, means for calculating an effective area integrated value during overlap of the exhaust valve opening period and the intake valve opening period, and means for calculating the engine speed is configured to include means for determining whether a supercharging and choking, and based on these calculated values, of claims 1 to 9, characterized in that to calculate the blow-back gas amount in the overlap The internal EGR amount estimation apparatus for an internal combustion engine according to any one of the above. The in-cylinder temperature estimation means includes a means for calculating an in-cylinder equilibrium temperature that is an in-cylinder temperature in a steady state based on an engine operating state, and a time delay with respect to a change in the in-cylinder equilibrium temperature. The internal EGR amount estimation apparatus for an internal combustion engine according to any one of claims 1 to 10, further comprising: means for calculating a temperature estimation value . The in-cylinder equilibrium temperature calculating means includes means for calculating a heat generation amount per predetermined time based on a parameter relating to a heat generation amount in the engine, means for estimating the in-cylinder equilibrium temperature based on a heat generation amount per predetermined time, The internal EGR amount estimation device for an internal combustion engine according to claim 11 , comprising: The in-cylinder temperature estimated value calculating means is a means for calculating a difference between the in-cylinder equilibrium temperature and the previous in-cylinder temperature estimated value, and adding a predetermined ratio of the difference to the previous in-cylinder temperature estimated value to perform a primary operation. 13. The internal EGR amount estimation device for an internal combustion engine according to claim 11 or 12 , comprising means for updating an estimated in-cylinder temperature value with a delay. 14. The internal EGR amount estimation device for an internal combustion engine according to claim 13, wherein the in-cylinder temperature estimated value update means updates the in-cylinder temperature estimated value for each fuel injection cycle. The in-cylinder temperature estimation value calculating means according to claim 11 claim, characterized in that it is configured to include an initialization means for initializing a cylinder temperature estimated value based on the engine coolant temperature when starting the engine The internal EGR amount estimation apparatus for an internal combustion engine according to any one of 14 .

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