JP2004225650A - Inside egr amount estimating device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve accuracy of estimation of an inside EGR amount even in a transient state of an engine, by estimating a cylinder temperature TEVC or valve temperatures VTMPE, VTMPI with high accuracy. <P>SOLUTION: The cylinder temperature estimation value TEVC, cylinder pressure, and a gas constant in closing an exhaust valve are calculated. Based on at least them, a cylinder gas amount in closing the exhaust valve is calculated, and a split-back gas amount during overlapping an exhaust valve opening period with an intake valve opening period is calculated. Where, the cylinder temperature estimation valve TEVC is calculated with time lag with respect to change in cylinder terminal temperature, by calculating a cylinder terminal temperature TEQEVC in a steady state of the engine. Based on the cylinder gas amount and split-back gas amount, the inside EGR amount is calculated. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an internal EGR amount estimating device for an internal combustion engine.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a spark ignition type internal combustion engine has a variable valve mechanism in order to reduce NOx (nitrogen oxide) by suppressing combustion temperature by increasing inert components in combustion gas and to reduce fuel consumption by reducing pump loss. In some cases, the amount of overlap between the exhaust valve open period and the intake valve open period is expanded to increase the internal EGR amount. In this case, it is desirable to perform control for correcting ignition timing, fuel injection amount, valve opening / closing timing, and the like according to the internal EGR amount.
[0003]
In Patent Document 1, a basic value of an internal EGR amount is calculated from an operating state of an engine under a condition of no overlap (load, rotation speed, air-fuel ratio, EGR rate, intake negative pressure, etc.). It is disclosed that an internal EGR amount is calculated by adding an increase correction amount due to overlap calculated based on time, a center crank angle position thereof, and intake pressure to a basic value.
[0004]
[Patent Document 1]
JP 2001-221105 A
[0005]
[Problems to be solved by the invention]
However, in Patent Literature 1, since the operating state of the engine changes and the combination of load, rotation speed, combustion air-fuel ratio, intake negative pressure, and the like changes, 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 gas temperature in the steady state of the engine, thereby improving the accuracy of estimating the internal EGR amount. Rise and fall quickly, and the accuracy of estimating the in-cylinder temperature is not sufficient, so that the error of the actual internal EGR amount with respect to the internal EGR amount calculation value may increase.
[0007]
Furthermore, during cold start after start-up, after deceleration fuel cut-off operation, and at high water temperature during high-speed high-load operation, valve components (particularly the shaft part) thermally expand due to temperature changes in the valve and cylinder head. Then, the valve clearance changes, the valve opening / closing timing based on the cam twist angle differs from the actual valve opening / closing timing, and the error of the actual internal EGR amount with respect to the internal EGR amount calculation value may increase.
[0008]
Here, it is possible to improve the accuracy of estimating the internal EGR amount by detecting the exhaust gas temperature and the valve temperature based on the output of the temperature sensor. However, adding the sensor increases the cost and causes a response delay of the sensor. In such a case, an error occurs. Further, it is possible to estimate the exhaust gas temperature and the valve temperature according to the fuel injection amount without providing a temperature sensor. However, these estimated temperatures are balanced so that the balance between the heat generation amount and the heat release amount of the engine is balanced. In the transient state in which the estimated temperature does not reach equilibrium, an error occurs in the estimated temperature, and the error of the actual internal EGR amount with respect to the calculated internal EGR amount value may increase. For this reason, the actual ignition timing and the required injection amount cannot be satisfied, and there is a possibility that the drivability is deteriorated and the fuel efficiency and the exhaust are deteriorated.
[0009]
The present invention has been made to solve the above problem, and has as its object to accurately estimate the internal EGR amount even in a transient state of the engine.
[0010]
[Means for Solving the Problems]
For this reason, in the present invention, the in-cylinder temperature estimated value when the exhaust valve is closed, the in-cylinder pressure, and the gas constant are calculated, and the in-cylinder gas amount when the exhaust valve is closed is calculated based on at least these values. Then, the blowback gas amount during the overlap between the exhaust valve open period and the intake valve open period is calculated. Here, the in-cylinder temperature estimated value is calculated by calculating the in-cylinder equilibrium temperature in a steady state of the engine and giving a time delay to a change in the in-cylinder equilibrium temperature. Then, the internal EGR amount is calculated based on the in-cylinder gas amount and the blowback gas amount.
[0011]
Further, 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. However, the valve temperature and valve clearance are estimated, and the valve timing is calculated based on the valve clearance. Is corrected. Here, the valve temperature estimated value is calculated by calculating a valve equilibrium temperature in a steady state of the engine and giving a time delay to a 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 Is calculated, and the blowback gas amount during the overlap between the exhaust valve open period and the intake valve open 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 the 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, the fuel injection amount, and the valve opening / closing timing can be appropriately set. By doing so, it is possible to improve drivability and improve fuel efficiency and exhaust.
[0013]
BEST MODE FOR CARRYING OUT 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 device for an internal combustion engine.
[0014]
A combustion chamber 3 defined by a 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 a spark plug 4. The lift characteristics (opening / closing timing) of the intake valve 5 and the exhaust valve 6 are changed by changing the phase of the cam with respect to the cam shaft by the variable valve solenoids 22 and 23 of the variable valve timing mechanisms provided on the intake and exhaust sides. , And valve timing can be controlled.
[0015]
An electronically controlled throttle valve 19 is provided in the intake passage 7 to control the intake fresh air amount. 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 an ignition plug 4 and burns, and is discharged to an exhaust passage 8.
[0016]
Here, the operations of the electronic control throttle valve 19, the injector 20, the ignition plug 4 (the ignition coil 21 with a built-in power tiger), and the variable valve solenoids 22 and 23 are controlled by an engine control unit (ECU) 30.
[0017]
For these controls, signals from various sensors are input to the ECU 30.
The crank angle sensor 14 outputs a crank angle signal in synchronization with the engine rotation, and thereby can detect the engine rotation 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, and thereby can detect the operating states of the variable valve solenoids 22 and 23.
[0018]
An air flow meter 9 for detecting a fresh intake air amount in the intake passage 7, an intake pressure sensor 10 for detecting intake pressure downstream of the electronic control throttle valve 19, and an exhaust pressure sensor 11 for detecting exhaust pressure in the exhaust passage 7. The ECU 30 also receives the output signals of the water temperature sensor 15 for detecting the temperature of the cooling water of the engine 1, the accelerator opening sensor 18 for detecting the accelerator opening, and the knock sensor 25 for detecting the vibration (particularly knocking vibration) of the engine 1. These states can be detected. The knock sensor 25 is capable of detecting operation vibrations (seating vibrations and the like) 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, the 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 respective values, and FIGS. 40 and 41 are valve timing change amounts. FIG. 4 is a diagram showing the definition of the positive and negative directions of the above.
[0020]
The calculation of the internal EGR rate MRESFR will be described with reference to the control configuration diagram of the internal EGR rate calculation means in FIG. 2 and the internal EGR rate MRESFR calculation flow in FIG.
[0021]
The intake fresh air amount calculating means shown in FIG. 2 calculates the intake fresh air amount (fresh air mass) MACYL, the target combustion equivalent ratio calculating means calculates the target combustion equivalent ratio TFBYA, and the internal EGR amount calculating means calculates the internal EGR amount MRES. Based on these calculated values, the internal EGR rate calculation means calculates the internal EGR rate MRESFR.
[0022]
In step 1 of FIG. 15 (referred to 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 is detected based on the signal of the crank angle sensor 14, the accelerator opening detected based on the signal of the accelerator opening sensor 18, and detected based on the signal of the water temperature sensor 15. A target combustion equivalent ratio TFBYA determined according to the cooling water temperature is calculated.
[0024]
When the stoichiometric air-fuel ratio (stoichiometric) is 14.7, the target combustion equivalent ratio TFBYA is expressed by the following equation from the target combustion air-fuel ratio, and becomes 1 when the target combustion air-fuel ratio is stoichiometric.
[0025]
TFBYA = 14.7 / target combustion air-fuel ratio (1)
In step 3, 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, the calculation of the internal EGR amount MRES in step 3 will be described with reference to the control configuration diagram of the internal EGR amount calculation means in FIG. 3 and the internal EGR amount calculation flow in FIG.
[0027]
When the exhaust valve shown in FIG. 3 is closed (shown as “EVC” in the figure), the in-cylinder gas amount calculation means uses the in-cylinder gas amount MRESCYL and overlaps the intake valve 5 and the exhaust valve 6 (“O / L)), the return gas amount calculating means calculates the return gas amount MRESOL, respectively, and the internal EGR amount calculating means calculates the internal EGR amount MRES based on these calculated values.
[0028]
In step 5 of FIG. 16, an in-cylinder exhaust gas amount MRESCYL when the exhaust valve is closed, which is an amount of gas remaining in the cylinder when the exhaust valve is closed, is calculated according to a flowchart of FIG. 17 described later.
[0029]
In step 6, in accordance with the flowchart of FIG. 18 described later, an overlapped blowback gas amount MRESOL, which is a gas amount blown back from the exhaust side to the intake side during overlap, is calculated.
[0030]
In step 7, the in-cylinder gas amount MRESCYL when the exhaust valve is closed and the blow-back gas amount MRESOL during overlap are added, and the internal EGR amount MRES is calculated by the following equation.
[0031]
MRES = MRESCYL + MRESOL (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 in-cylinder gas amount calculation means when the exhaust valve is closed in FIG. 4 and the in-cylinder gas amount when the exhaust valve is closed in FIG. This will be described with reference to a gas amount MRESCYL calculation flow.
[0032]
The target combustion equivalent ratio calculating means shown in FIG. 4 calculates the target combustion equivalent ratio TFBYA of the exhaust gas, and based on this value, the exhaust gas constant calculating means calculates the gas constant REX. The exhaust valve closing cylinder volume calculating means calculates the cylinder volume VEVC, the exhaust valve closing cylinder temperature calculating means calculates the cylinder temperature TEVC, and the exhaust valve closing pressure calculating means calculates the cylinder pressure PEVC. Then, based on these calculated values, the in-cylinder gas amount calculation means when the exhaust valve is closed calculates the in-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. 24 described later.
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. The horizontal axis indicates the target combustion equivalent ratio TFBYA, and the vertical axis indicates the gas constant REX of the exhaust gas. Note that the dotted line in FIG. 33 indicates stoichiometry.
[0034]
In step 10, the in-cylinder temperature TEVC when the exhaust valve is closed is estimated according to the flow shown in FIG.
In step 11, the in-cylinder pressure PEVC when the exhaust valve is closed is estimated based on the exhaust pressure detected based on the signal of the exhaust pressure sensor 11. The in-cylinder pressure PEVC when the exhaust valve is closed is determined by the air-fuel mixture volume and the pipe resistance of the exhaust system, and may be obtained from a table corresponding to the air-fuel mixture volume flow rate.
[0035]
In step 12, calculated values of the exhaust valve closed cylinder volume VEVC, the exhaust gas gas constant REX, the exhaust valve closed cylinder temperature TEVC, and the exhaust valve closed cylinder pressure PEVC calculated in steps 8 to 11 are calculated. From this, the in-cylinder gas amount MRESCYL when the exhaust valve is closed 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 in step 6 in FIG. 16, a control configuration diagram of the calculation of the gas flow back during overlap in FIG. 5 and the blow back during overlap in FIG. This will be described with reference to a gas amount MRESOL calculation flow.
[0037]
In FIG. 5, the target combustion equivalence ratio calculating means calculates the equivalence ratio TFBYA, and the exhaust gas constant calculating means calculates the gas constant REX based on the calculated value. The effective area during overlap calculation means calculates the effective area ASUMOL according to FIG. 39 described later. Then, these calculated values are compared with the engine speed calculating means, the exhaust gas specific heat ratio calculating means, the in-cylinder temperature calculating means when the exhaust valve is closed, the in-cylinder pressure calculating means when the exhaust valve is closed, the intake pressure calculating means, and the choke excess. On the basis of the values calculated by the supply determination calculating means, the blowback gas amount calculating means during the overlap calculates the blowback gas amount MRESOL.
[0038]
In step 13 of FIG. 18, the effective area ASUMOL during the overlap is calculated according to the flowchart of FIG. 29 described later.
In step 14, the engine speed NRPM is calculated based on the signal of 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 equivalence ratio calculation means shown in FIG. 6 calculates the target combustion equivalence ratio TFBYA, and the in-cylinder temperature at exhaust valve closing calculation means calculates the in-cylinder temperature TEVC, respectively, 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 indicates the target combustion equivalent ratio TFBYA, and the vertical axis indicates the exhaust gas specific heat ratio SHEATR. The dotted line in the figure indicates the position of stoichiometry. When the target combustion equivalent ratio TFBYA is near stoichiometry, the exhaust gas specific heat ratio SHEATR decreases, and when the ratio becomes rich or lean, the specific heat ratio SHEATR increases. Then, the 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 determined according to the target combustion equivalent ratio TFBYA calculated in step 2 of FIG. 15 and the in-cylinder temperature TEVC when the exhaust valve is closed calculated in step 10 of FIG.
[0041]
In step 16, the supercharging determination TBCRG and the choke determination CHOKE are performed according to the control configuration diagram of the supercharging / choke determination means of FIG. 7 described later and the supercharging determination TBCRG / choke determination CHOKE flow of FIG.
[0042]
In step 17, it is determined whether the supercharging determination flag TBCRG in step 16 is 0, that is, the supercharging state is determined. When the supercharging determination flag TBCRG is 0, the process proceeds to step 18. 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 is determined.
If the choke determination flag CHOKE is 0, the process proceeds to step 19, and the flow rate of the blow-back gas MRESOLtmp during the overlap when there is no supercharging and no choke is calculated from the flow of FIG.
[0044]
On the other hand, if it is determined in step 18 that the choke determination flag CHOKE in step 16 is not 0, the flow proceeds to step 20, and from the flow of FIG. Is calculated.
[0045]
In step 17, if the supercharging determination flag TBCRG in step 16 is 1, that is, it is in the supercharging state, and if the choke determination flag CHOKE is 0 in step 21, the process proceeds to step 22, and the flow of FIG. Then, the blow-back gas flow rate MRESOLtmp during the overlap when there is a supercharge and no choke is calculated.
[0046]
On the other hand, when the choke determination flag CHOKE in step 16 is 1 in step 21, the process proceeds to step 23, and the blowback gas flow rate MRESOLtmp at the time of supercharging and choking is calculated from the flow of FIG.
[0047]
After calculating the blowback gas flow rate MRESOLtmp in steps 19, 20, 22, and 23, the process proceeds to step 24.
In step 24, the blow-back gas amount MRESOL during the overlap is calculated by integrating the blow-back gas flow rate MRESOLtmp and the integrated effective area ASAMOL during the overlap period in accordance with the state of the presence or absence of the supercharging and the presence or absence of the choke. It is 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 configuration 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 in-cylinder pressure calculating means for closing the exhaust valve, and the intake pressure calculating means, the supercharging / choke determining means performs 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 in-cylinder pressure PEVC when the exhaust valve is closed calculated in step 11 of FIG. 17, that is, the intake exhaust pressure The ratio PINBYEX is calculated by the following equation.
[0051]
PINBYEX = PIN / PEVC (6)
In step 26, it is determined whether the intake / exhaust pressure ratio PINBYEX is equal to or less than 1, that is, a supercharging state is determined.
[0052]
If the intake / exhaust pressure ratio PINBYEX is 1 or less, that is, if there is no supercharging, the routine proceeds to step 27, where 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 larger than 1, that is, if there is a supercharging, the routine proceeds to step 28, where the supercharging determination flag TBCRG is set to 1, the routine proceeds to step 29, and the calculation is performed in step 15 of FIG. The exhaust gas specific heat ratio SHEATR is defined as an air / fuel mixture specific heat ratio MIXAIRSHR determined from the table shown in FIG. 35 (SHEATR = MIXAIRSHR).
[0054]
FIG. 35 is a calculation table for the mixture specific heat ratio MIXAIRSHR. The horizontal axis indicates the target combustion equivalent ratio TFBYA, and the vertical axis indicates the mixture specific heat ratio MIXAIRSHR. Note that 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, the 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 inertia supercharging is changed from the intake system. Even when going to the exhaust system (blowing through), by changing the specific heat ratio of the gas passing through the orifice from the specific heat ratio of the exhaust gas to the specific heat ratio of the intake air-fuel mixture, the amount of gas flowing through is accurately estimated, and the internal EGR amount Is calculated with high accuracy.
[0056]
In step 30, the minimum and maximum choke determination thresholds SLCHOKEL and SLCHOKEH are calculated by the following equation based on the exhaust gas specific heat ratio SHEATR calculated in step 15 or step 29.
[0057]
SLCHOKEL = {2 / (SHEATR + 1)} SHEATR / (SHEATR-1)} (7a)
SLCHOKEH = {2 / (SHEATR + 1)}-SHEATR / (SHEATR-1)} (7b)
The choke determination threshold values SLCHOKEEL and SLCHOKEH are calculated as choke limit values.
[0058]
If it is difficult in step 30 to calculate the exponentiation due to the control configuration, the calculation results of the equations (7a) and (7b) are previously stored in the minimum choke determination threshold value SLCHOKEL table and the maximum choke determination threshold value SLCHOKEH. It may be stored as a table, and determined in accordance with the exhaust gas specific heat ratio SEATR.
[0059]
In step 31, it is determined whether or not the intake / exhaust pressure ratio PINBYEX calculated in step 25 is in the range of not less than the minimum choke determination threshold SLCHOKEEL and not more than the maximum choke determination threshold SLCHOKEH, that is, a 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 process proceeds to step 32, and the choke determination flag CHOKE is set to 0.
[0061]
On the other hand, if the intake / exhaust pressure ratio PINBYEX is not within the range, that is, if it is determined that there is a choke, the process proceeds to step 33, and the choke determination flag CHOKE is set to 1.
[0062]
In addition, the calculation of the blowback gas flow rate MRESOLtmp in step 19 in FIG. 18 will be described using the flow of calculating the blowback gas flow rate during overlap without supercharging and without choke in FIG. 20.
[0063]
In step 34, the gas flow rate calculation equation density term MRSOLD is calculated based on the gas constant REX of the exhaust gas calculated in step 9 in FIG. 17 and the in-cylinder temperature TEVC when the exhaust valve is closed calculated in step 10. It is calculated by the formula.
[0064]
MRSOLD = SQRT {1 / (REX × TEVC)} (8)
Here, SQRT is a coefficient relating to temperature and gas constant. If it is difficult to calculate the density term MRSOLD in the gas flow rate calculation equation due to the control configuration, the calculation result of the equation (8) is stored in advance as a map, and the calculation result is calculated according to the exhaust gas constant REX and the in-cylinder temperature TEVC. You may ask for it.
[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 equation pressure difference term MRSOLP is calculated by the following equation. calculate.
[0066]
MRSOLP = SQRT [SHEATR / (SHEATR-1) × {PINBYEX} (2 / SHEATR) -PINBYEX} ((SHEATR + 1) / SHEATR)} (9)
In step 36, the in-cylinder pressure PEVC when the exhaust valve is closed calculated in step 11 of FIG. 17, the gas flow rate calculation equation density term MRSOLD and the gas flow rate calculation pressure calculated in steps 34 and 35 of FIG. Based on the difference term MRSOLP, a blowback flow rate MRESOLtmp during overlap without supercharging and no choke is calculated by the following equation.
[0067]
MRESOLtmp = 1.4 × PEVC × MRSOLD × MRSOLP (10)
The blowback gas flow rate MRESOLtmp in step 20 will be described with reference to the flow chart of FIG.
[0068]
In step 37, similarly to step 34 in FIG. 20, the gas flow rate calculation equation density term MRSOLD is calculated from the above equation (8).
In step 38, the gas flow rate calculation equation choke pressure difference term MRSOLPC is determined by the following equation based on the exhaust gas specific heat ratio SHEATR calculated in step 15 in FIG.
[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 equation choke-time pressure difference term MRSOLPC map, and is calculated according to the exhaust gas specific heat ratio SHEATR. You may ask.
[0070]
In step 39, the in-cylinder pressure PEVC at the time of closing the exhaust valve calculated in step 11 in FIG. 17, the gas flow rate calculation formula density term MRSOLD calculated in step 37 in FIG. 21, and the choke time calculated in step 38. Based on the pressure difference term MRSOLPC, the overlap return flow rate MRESOLtmp when there is no supercharging and there is a choke is calculated by the following equation.
[0071]
MRESOLtmp = PEVC × MRSOLD × MRSOLPC (12)
The calculation of the average blowback gas flow rate MRESOLtmp during the overlap in step 22 will be described with reference to the flow chart of 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 rate calculation supercharging pressure difference term MRSOLPT is calculated 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 configuration of the control, the calculation result of the equation (13) is stored in advance as a gas flow rate calculation type supercharged pressure difference term MRSOLPT map, and the exhaust gas specific heat ratio SHEATR and the intake air It may be determined according to the exhaust pressure ratio PINBYEX.
[0074]
In step 41, based on the intake pressure PIN detected based on the signal of the intake pressure sensor 10 and the pressure difference term MRSOLPT during supercharging calculated in step 40, blow back during the 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, when the blowback gas flow rate MRESOLtmp indicates a negative value, the flow rate of gas flowing through the intake system to the exhaust system during the overlap can be represented, 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 flow chart of FIG.
[0077]
In step 42, as in step 38 of FIG. 21, the choke pressure difference term MRSOLPC is obtained from the gas flow rate calculation equation (11) or the map.
In step 43, based on the intake pressure PIN and the gas flow rate calculation type choke-time pressure difference term MRSOLPC, the overlap blowback gas flow rate MRESOLtmp when there is supercharging and choke is calculated by the following equation.
[0078]
MRESOLtmp = −0.108 × PIN × MRSOLPC (15)
Here, when the blowback gas flow rate MRESOLtmp indicates a negative value, the flow rate of the gas flowing from the intake side to the exhaust side during the overlap can be represented, and the internal EGR amount is reduced.
[0079]
Here, in steps 19, 20, 22, and 23, the blowback gas flow rate MRESOLtmp is calculated according to the state of the presence or absence of the supercharging and the presence or absence of the choke. After calculating the amount MRESOL of the blown-back gas during the overlap in the above-described step 24, the process proceeds from step 6 in FIG. 16 to step 7, 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 to calculate the above-mentioned internal EGR rate MRESFR, and ends the processing.
[0080]
In addition, regarding the calculation of the in-cylinder volume VEVC when the exhaust valve is closed in step 8 in FIG. 17, the control configuration diagram of the calculation of the in-cylinder volume VEVC when the exhaust valve is closed in FIG. This will be described using the product VEVC calculation flow.
[0081]
The exhaust-valve-closed-cylinder-in-cylinder-capacity calculating means shown in FIG. 8 is based on a calculated value VTEOFS of the exhaust-valve-timing-change-quantity calculating means described later. The valve-time in-cylinder volume VEVC is calculated.
[0082]
In step 44 of FIG. 24, the exhaust valve timing change amount VTEOFS, which is the change amount toward the overlap increasing side, that is, the direction in which the exhaust valve closing time is delayed, is calculated according to the flowchart of FIG.
[0083]
In step 45, the in-cylinder volume VEVC when the exhaust valve is closed is obtained from the table shown in FIG. 36 according to 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, in which 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 when the exhaust valve is closed and the in-cylinder volume VEVC, the in-cylinder volume VEVC when the exhaust valve is closed according to the amount of change is obtained from a table. You may.
[0085]
In an engine having a mechanism for changing the compression ratio, the in-cylinder volume VEVC when the exhaust valve is closed according to the amount of change in the compression ratio may be obtained from a table.
Here, the calculation of the exhaust valve timing change amount VTEOFS in step 44 in FIG. 24 is performed using the control configuration diagram for calculating the exhaust valve timing change amount VTEOFS in FIG. 9 and the exhaust valve timing change amount VTEOFS calculation flow in FIG. Will be explained.
[0086]
In FIG. 9, the basic change amount of the exhaust valve timing is detected from the signals of the crank angle sensor 14 and the cam angle sensor 17 on the exhaust side in accordance with the relative relationship between the two. Calculate VTCNOWE. The valve timing change amount correction amount calculating means calculates the valve timing change amount correction amount VTCLE based on the calculated value VCLE of the valve clearance amount calculating means. Then, the exhaust valve timing change amount calculating means calculates the exhaust valve timing change amount VTEOFS based on the 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 cam angle sensor 17.
[0088]
In step 47, the valve clearance amount VCLE is calculated according to the flowchart of FIG. 26 described later.
In step 48, the exhaust valve timing change amount correction amount VTCLE is obtained from the table shown in FIG. 37A according to the exhaust valve clearance amount VCLE.
[0089]
FIG. 37 (a) is an exhaust valve timing variation correction amount VTCLE calculation table. The horizontal axis represents the exhaust valve clearance VVCLE, and the vertical axis represents the exhaust valve timing variation relative to the valve timing at the reference clearance (in a steady state). The correction amount VTCLE is shown. According to this, when the clearance amount VCLE of the exhaust valve 6 decreases (goes to the left), the valve closing timing is delayed by VTCLE, so that it is necessary to increase and correct the valve timing change amount toward the overlap increasing side. Is shown.
[0090]
In step 49 of FIG. 25, a valve timing correction learning value VTHOSE is calculated according to a flowchart of FIG. 27 described later.
In step 50, the exhaust valve timing change amount VTEOFS is calculated as the exhaust valve timing basic change amount (exhaust cam twist angle) VTCNOWE, the exhaust valve timing change amount correction amount VTCLE based on the change in the valve clearance amount VCLE due to the valve temperature VTMPE, and cam wear. The exhaust valve timing correction learning value VTHOSE based on the learning value of the change in the valve clearance amount 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 for calculating the exhaust valve clearance amount VCLE in FIG. 10 and the valve clearance amount VCLE calculation flow in FIG.
[0092]
The valve clearance amount calculating means in FIG. 10 calculates the valve temperature VTMPE from the fuel injection amount corresponding to the intake fresh air amount MACYL calculated based on the signal from the air flow meter 9 based on the value calculated by the valve temperature calculating means. Calculate the valve clearance amount VCLE. Here, the valve temperature calculating means calculates the valve temperature VTMPE according to the temperature calculation flow of FIG. 31 described later. 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 based on the stoichiometric basic fuel injection amount TP = K × MACYL / NRPM (K is a constant). This is calculated by correcting the target combustion equivalent ratio TFBYA corresponding to the target air-fuel ratio or correcting the air-fuel ratio with a 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. 31 described later. In this flow, the intake valve 5 and the exhaust valve 6 are calculated independently of each other. However, 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 by the following equation according to the exhaust valve temperature VTMPE.
VCLEtmp = −KVTMPE × (VTMPE−90) + VCLSTDE (18)
Here, -KVTMPE is a coefficient relatively determined by the material and the length of the exhaust valve 6, and mainly considering the case where the expansion of the valve 6 in the axial direction is large, the expansion of other parts (for example, the cylinder head, etc.) is considered. Is determined without consideration. VCLSTDE is a reference valve clearance amount at a reference temperature (here, 90 ° C.). When 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. When 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 learning value VTHOSE in step 49 in FIG. 25 will be described using the control configuration diagram of the valve timing correction learning value calculation in FIG. 11 and the valve timing correction learning value VTHOSE calculation flow in FIG. I do.
[0097]
In FIG. 11, the basic valve timing change amount calculating means calculates the basic valve timing 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 estimation value calculation means calculates the valve closing timing estimation value VCLTEE based on the valve timing basic change amount VTCNOWE and the calculated value VTCLE of the valve timing change amount correction amount calculation means. On the other hand, the actual valve closing timing calculating means calculates the actual valve closing timing VCLTRE from the signals from the crank angle sensor 14 and the knock sensor 25 by the actual valve closing timing determining means and the signals from 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 of FIG. 27, a valve timing actual value calculation permission flag FVTHOSE is calculated according to a flowchart of FIG. 28 described later.
In step 57, it is determined whether or not a valve timing actual value calculation permission flag FVTHOSE is 1. Thereby, it is determined whether or not the valve closing timing can be appropriately detected. If the flag FVTHOSE = 1, the process proceeds to step 58. On the other hand, if the flag FVTHOSE = 0, the process returns.
[0099]
In step 58, the actual seating timing of the valve 6, that is, the actual closing timing of the valve 6, is determined based on the relative relationship between the signal of the knock sensor 25 for detecting vibration generated when the exhaust valve 6 is seated and the signal of the crank angle sensor 14. Calculate VCLTRE (degATDC).
[0100]
In step 59, the valve closing timing estimated value VCLTEE is calculated by the following equation by adding the valve closing timing VCLTSTDE and the exhaust valve timing variation correction amount VTCLE.
[0101]
VCLTEE = VCLTSTDE + VTCLE (degATDC) (19)
Here, VCLTSTDE is the valve closing timing when the basic valve timing change amount is 0 in the reference valve clearance amount (valve clearance amount at the time of warming).
[0102]
In step 60, a provisional valve timing correction amount VTHOStmp is calculated from the difference between the actual value VCLTRE of the valve closing timing and the estimated value VCLTEE (VCLTRE-VCLTEE).
[0103]
In step 61, it is determined whether the absolute value of the error between the provisional valve timing correction amount VTHOSEtmp and the valve timing correction learning value VTHOSE is equal to or greater than a predetermined value SLVCL. If the absolute value of the error is equal to or greater than the predetermined value SLVCL, the process proceeds to step 62. On the other hand, if the value is equal to or less than the predetermined value SLVCL, the process returns.
[0104]
In step 62, the provisional valve timing correction amount VTHSEtmp is substituted for the valve timing correction learning value VTHOSE (VTHOSE = VTHOSEtmp).
[0105]
Here, if the error increases to the positive side, the actual valve closing timing will be further delayed, so this error may be added to the valve timing change amount. However, in practice, the error is a negative value because the clearance increases mainly due to shim wear and cam wear, and the actual valve closing timing is advanced.
[0106]
Here, the 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 in FIG.
[0107]
At step 63, the basic change amount of the valve timing is determined to be 0 (VTCNOW = 0), at step 64, it is determined that the water temperature is equal to or higher than the predetermined water temperature VTHOSTW, and at step 65, the rotation speed is determined to be equal to or lower than the predetermined rotation speed VTHOSNE. When it is determined in step 66 that the throttle opening is equal to or smaller than the predetermined opening VTHOSTVO, in step 67, the valve timing actual value calculation permission flag FVTHOSE is set to 1 (FVTHOSE = 1). This is for estimating whether the operating state is suitable for calculating the actual valve timing value VCLTRE.
[0108]
On the other hand, if any one of the steps 63 to 66 is not established, the routine proceeds to a step 68, where the valve timing actual value calculation permission flag FVTHOSE is set to 0 (FVTHOSE = 0). If these conditions are not satisfied, it is not in a state suitable for calculating the actual valve timing value VCLTRE.
[0109]
Next, regarding the calculation of the effective area integrated value during overlap ASAMOL in step 13 in FIG. 18, the control configuration diagram of the effective area during overlap calculation in FIG. 12 and the flow of calculating the effective area during overlap in FIG. 29 will be described. It will be described using FIG.
[0110]
12 calculates the effective area during overlap ASAMOL 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. 30 described later.
In step 70, the exhaust valve timing change amount VTEOFS is calculated according to the flowchart of FIG.
[0112]
In step 71, the overlapped effective area integrated value ASAMOL is obtained from the overlapped effective area integrated value calculation map 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 of the effective area during the overlap. The horizontal axis indicates the intake valve timing change amount VTIOFS, and the vertical axis indicates the exhaust valve timing change amount VTEOFS. When the intake valve timing change amount VTIOFS and the exhaust valve timing change amount VTEOFS increase, the overlap change amount increases, and the effective area integrated value ASAMOL increases.
[0114]
Here, FIG. 39 is an explanatory diagram of the integrated effective area value ASUMOL during the overlap. 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 ASAMOL for the entire period during the overlap is the integrated value (the hatched portion in the drawing) during the period when the intake valve 5 and the exhaust valve 6 are open. In this manner, by calculating the effective area integrated value ASAMOL during the overlap, the amount of overlap 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 and the intake type The flow rate passing through the orifice can be simply calculated from the above condition.
[0115]
Next, the calculation of the intake valve timing variation VTIOFS in step 69 in FIG. 29 is performed using the control configuration diagram of the intake valve timing variation VTIOFS calculation in FIG. 13 and the intake valve timing variation VTIOFS calculation flow in FIG. explain. The case where the intake valve 5 has a large overlap amount, that is, a case where the valve opening timing is advanced is described.
[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 cam angle sensor 16. The valve timing change amount correction amount calculating means calculates the valve timing change amount correction amount VTCLI based on the calculated value VCLI of the valve clearance amount calculating means. Then, the intake valve timing change amount calculating 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 calculated value VTHOSI of the valve timing correction learning value calculating means. I do.
[0117]
In step 72 of FIG. 30, the basic change amount of intake valve timing (intake cam twist angle) VTCNOW is calculated based on the signals of the crank angle sensor 14 and the intake 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, as the provisional valve clearance amount VCLItmp calculated in step 52, the provisional valve clearance amount VCLItmp 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 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, etc.). Is determined without consideration. VCLSTDI is a reference valve clearance amount (clearance amount in a warm state (about 90 ° C.)).
[0120]
In step 74, an intake valve timing change amount correction amount VTCLI is obtained from the table shown in FIG. 37B according to the intake valve clearance amount VCLI.
[0121]
FIG. 37 (b) is an intake valve timing change amount correction amount VTCLI calculation table. 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. This indicates that if the clearance amount VCLI of the intake valve 5 becomes smaller, the valve opening timing is earlier 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, an intake valve timing correction learning value VTHOSI is calculated according to the flowchart of FIG. Here, in step 58 of FIG. 27, a signal from the knock sensor 25 for detecting vibration when the intake valve 5 separates from the valve seat, that is, when the lifter of the intake valve 5 collides with the cam, and a signal from the crank angle sensor 14 , The valve lift timing, that is, the actual valve opening timing VCLTRI (degBTDC) is calculated.
[0123]
In step 59, the estimated valve opening timing VCLTEI is calculated by adding the valve timing change correction amount VTCLI to the estimated valve opening timing VCLTSTDI according to the following equation.
[0124]
VCLTEI = VCLTSTDI + VTCLI (degBTDC) (21)
Here, the valve opening time estimated value VCLSTSTDI is the valve opening timing when the basic intake valve timing change amount (intake cam twist angle) at the reference valve clearance amount (at the time of warming) is 0.
[0125]
In step 60, the provisional valve timing correction amount VTHOStmp is calculated according to VCLTRI-VCLTEI. This error is mainly due to the increase in clearance due to shim wear and cam wear, 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 movement is such that the valve timing change amount is canceled.
[0126]
In step 76, the intake valve timing change amount VTIOFS, the intake valve timing basic change amount (intake cam twist angle) VTCNOW, the intake valve timing change amount correction amount VTCLI based on the change in the valve clearance amount VCLI due to the valve temperature VTMPI of the intake valve 5 are determined. By adding the intake valve timing correction learning value VTHOSI based on the learning value of the change in the valve clearance amount VCLI due to cam wear and shim wear, it is calculated by the following equation.
[0127]
VTIOFS = VTCNOW + VTCLI + VTHOSI (22)
Here, FIG. 40 is a diagram showing the definition of the change amount of the exhaust valve timing in the positive and negative directions, and FIG. 41 is a diagram showing the definition of the change amount of the intake valve timing in the positive and negative directions.
[0128]
In FIG. 40, the exhaust valve timing change amount has the positive direction on the advance side (clockwise). In FIG. 41, the intake valve timing change amount is positive on the retard side (counterclockwise). Each of the intake valve 5 and the exhaust valve 6 is in a direction to increase the overlap amount.
[0129]
Next, regarding the calculation of the in-cylinder temperature TEVC when the exhaust valve is closed in step 10 in FIG. 17 and the calculation of the exhaust valve temperature VTMPE and the intake valve temperature VTMPI in step 51 in FIG. 26, the temperatures TEVC, VTMPE, A description will be given with reference to a control configuration diagram of VTMPI calculation and a temperature TEVC, VTMPE, and VTMPI calculation flow of FIG.
[0130]
The equilibrium temperature calculating 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 the valve temperature in the steady state, based on the engine operating state. The difference calculating means calculates the in-cylinder temperature TEVC (-1), the exhaust valve temperature VTMPE (-1), the intake valve temperature VTMPI (-1), the in-cylinder equilibrium temperature TEQEVC, the exhaust valve equilibrium temperature VTMPEQE, The 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, and KVTMPI of the in-cylinder temperature TEVC, the exhaust valve temperature VTMPE, and the intake valve temperature VTMPI. Then, the integrating operation means integrates the predetermined ratios KTEVC, KVTMPE, and KVTMPI of the responsiveness calculating means to the difference values TDEVC, VTMPDE, and VTMPDI of the difference calculating means. Then, the addition operation means adds each temperature TEVC (-1), VTMPE (-1), VTMPI (-1) in the previous cycle and the integrated value of the integration operation means.
[0131]
In step 77 of FIG. 31, it is determined whether or not an ON signal has been input from the starter switch 26. If an ON signal has been input, the routine proceeds to step 78, where the in-cylinder temperature TEVC and the valve temperatures VTMPE and VTMPI are set to the cooling water temperature TWN and initialized. On the other hand, if it is not the time of switching from OFF to ON, the process proceeds to step 79.
[0132]
In step 79, the calorific value FHEAT (cal / sec) for each predetermined time in the engine is calculated from the calorific value calculation flow shown in FIG. 32 described later.
In step 80, the in-cylinder equilibrium temperature TEQEVC and the valve equilibrium temperatures VTMPEQE and VTMPEQI are obtained from the table shown in FIG. 42 according to the heat value FHEAT.
[0133]
FIG. 42 is a table for calculating the equilibrium temperatures TEQEVC, VTMPEQE, and VTMPEQI of each section. The horizontal axis indicates the calorific value 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 calculated 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 a REF signal (for example, 180 ° for four cylinders and 120 ° for six cylinders) is input from the crank angle sensor 14 for each fuel injection cycle.
[0136]
In step 83, as shown in the following equation, each part temperature TEVC (-1), VTMPE (-1), and VTMPI (-1) are individually added to each part difference value TDEVC, VTMPDE, VTMPDI according to each part. 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 in (1).
[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 response are set to a larger value as the specific heat of the temperature measurement part is smaller, and individually set so as to increase the response to the equilibrium temperatures TEQEVC, VTMPEQE, and VTMPEQI of each part. Is done.
[0138]
Next, the calculation of the calorific value FHEAT in step 79 in FIG. 31 will be described using the calorific value calculation flow in FIG.
In step 84, it is determined whether the target combustion equivalence ratio TFBYA is greater than 1 (TFBYA> 1), that is, whether the air-fuel ratio is rich. If it is rich (TFBYA> 1), the routine proceeds to step 85, where the target combustion equivalent ratio for calorific value calculation TFBYAHT is set to 1. This is because even if the air-fuel ratio is rich, the contribution to the actual heat generation is the same as the calorific value at the stoichiometric air-fuel ratio. On the other hand, if the target combustion equivalent ratio TFBYA is 1 or less (TFBYA ≦ 1), the routine proceeds to step 86, where the calorific value calculation target equivalent ratio TFBYAHT is set to the target combustion equivalent ratio TFBYA (TFBYAHT = TFBYA).
[0139]
In step 87, the calorific value FHEAT is calculated by the following equation.
FHEAT = (TFBYAHT × HBN− (TFBYA−TFBYAHT) × HUBN) × TP × NRPM × K (25)
Here, HBN is a 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) corresponding to stoichiometry per one cylinder cycle, and is a value calculated based on the intake air amount. The rotation speed NRPM (rpm) is a value calculated based on a signal from the crank angle sensor 14. K is a coefficient indicating how many times fuel is injected per revolution, and in the case of four cylinders, a value of 2 is substituted, and in the case of six cylinders, a value of 3 is substituted. Substitute each value according to the number of cylinders.
[0140]
According to the present embodiment, means for estimating the in-cylinder temperature TEVC when the exhaust valve is closed (steps 10 and 83), means for calculating the in-cylinder pressure PEVC when the exhaust valve is closed (step 11), and combustion Means (step 9) for calculating a gas constant REX of the exhaust gas composition according to the air-fuel ratio, and a cylinder gas amount when the exhaust valve is closed based on at least the cylinder temperature TEVC, the cylinder pressure PEVC and the gas constant REX. A means for calculating MRESCYL (step 12), a means for calculating a blowback gas amount MRESOL during the overlap between the exhaust valve open period and the intake valve open period (step 24), a cylinder gas amount MRESCYL and a blowback gas amount MRESOL. (Step 7) for calculating the internal EGR amount MRES on the basis of the above. Means (step 80) for calculating the in-cylinder equilibrium temperature TEQEVC, which is the in-cylinder temperature in a steady state, based on the state, and the in-cylinder temperature estimation value TEVC with a time delay with respect to the change in the in-cylinder equilibrium temperature TEQEVC. Calculating means (steps 81 to 83). Therefore, in particular, in the transient operation state, the in-cylinder temperature TEVC inside the cylinder changes every moment. However, the internal EGR amount MRES can be calculated based on the changing in-cylinder temperature TEVC. The accuracy of estimating the internal EGR amount MRES at the time can be improved, and by appropriately setting the ignition timing, the fuel injection amount, and the valve opening / closing timing, it is possible to improve drivability and improve fuel efficiency and exhaust. Then, the internal EGR amount MRES can be calculated from the physical equation based on the state quantity (temperature TEVC / pressure PEVC / gas constant REX) inside the cylinder after the end of combustion. Further, it is possible to cope with a density change due to a change in temperature and pressure and a density change due to a change in gas constant due to a change in combustion air-fuel ratio.
[0141]
Further, according to the present embodiment, the in-cylinder equilibrium temperature calculating means calculates the heat value FHEAT for each predetermined time based on the parameters related to the heat value FHEAT in the engine (the target combustion equivalent ratio TFBYA, the basic injection amount TP, and the rotation speed NRPM). (Steps 79 and 87), and a means (Step 80) for estimating the in-cylinder equilibrium temperature TEQEVC based on the heat generation amount FHEAT for each predetermined time. Therefore, even during the full-open operation or during the rich combustion immediately after the start, the fuel that is not oxidized does not generate heat, so that it is possible to prevent an increase in the estimation error of the in-cylinder temperature TEVC due to this fuel and to improve the accuracy of the internal EGR amount MRES. Estimation can be made well, and drivability can be improved and fuel consumption and exhaust can be improved.
[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). Means (Steps 82 and 83) for adding a predetermined ratio (TDEVC × KTEVC) of the difference TDEVC to the in-cylinder temperature estimated value TEVC (-1) and updating the in-cylinder temperature estimated value TEVC by a first-order delay. Be composed. Therefore, even when the equilibrium temperature suddenly changes due to the fuel cut, or during a transition in which the balance between the heat generation amount and the heat release amount is lost, such as during start-up and acceleration, the accuracy of estimating the in-cylinder temperature TEVC can be improved, and the internal EGR amount MRES Can be accurately estimated, and deterioration of fuel efficiency, exhaust, and drivability can be prevented beforehand.
[0143]
Further, according to the present embodiment, the in-cylinder temperature estimated value updating 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 it becomes possible to follow the transient phenomenon.
[0144]
Further, according to the present embodiment, the in-cylinder temperature estimated value calculating means includes an initial setting means for initial setting the in-cylinder temperature estimated value TEVC based on the engine cooling water temperature TWN at the time of starting the engine (step). 78). Therefore, the in-cylinder temperature TEVC when the engine is stopped almost converges to the temperature TWN of the cooling water, so that the temperature can be estimated immediately after the engine is started.
[0145]
Further, according to the present embodiment, variable valve timing mechanisms (variable valve solenoids) 22, 23 for changing the opening / closing timing of the exhaust valve 6 and the intake valve 5, and the amount of change VTEOFS of the opening / closing timing of the variable valve timing mechanisms 22, 23, Means for calculating the valve timing based on VTIOFS, means for estimating the in-cylinder temperature TEVC when the exhaust valve is closed calculated by the valve timing calculating means (steps 10 and 83), and calculation by the valve timing calculating means. Means for calculating the in-cylinder pressure PEVC when the exhaust valve is closed (step 11), means for calculating the gas constant REX of the exhaust gas composition according to the combustion air-fuel ratio (step 9), at least the in-cylinder temperature TEVC and the cylinder Based on the internal pressure PEVC and the 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 between the exhaust valve open period and the intake valve open period based on the calculation result of the valve timing calculation means (step 6, 24) means for calculating the internal EGR amount MRES based on the in-cylinder gas amount MRESCYL and the blowback gas amount MRESOL (step 7). The valve timing calculating means estimates the valve temperatures VTMPE and VTMPI. (Step 51), means (Steps 47 and 55) for estimating the valve clearance amount VCLE according to the estimated values VTMPE and VTMPI of the valve temperature, and means (Step 48) for correcting the valve timing by the valve clearance amount VCLE. 49), and The lube temperature estimating means calculates valve equilibrium temperatures VTMPEQE and VTMPEQI which are the valve temperatures VTMPE and VTMPI in a steady state based on the engine operating state (step 80). Means for calculating the valve temperature estimated values VTMPE and VTMPI with a delay (steps 81 to 83). Therefore, particularly in the transient operation state, the valve temperatures VTMPE and VTMPI of the exhaust valve 6 or the intake valve 5 change every moment, but the internal EGR amount MRES is based on the changing valve temperatures VTMPE and VTMPI. Can be calculated, the accuracy of estimating the internal EGR amount MRES during the transient operation can be improved, and by appropriately setting the ignition timing, the fuel injection amount, and the valve opening / closing timing, the drivability can be improved and the fuel consumption and exhaust can be improved. .
[0146]
Further, according to the present embodiment, the valve equilibrium temperature calculating means calculates the heat value FHEAT for each predetermined time based on the parameters (the target combustion equivalence ratio TFBYA, the basic injection amount TP, and the rotation speed NRPM) relating to the heat value FHEAT in the engine. Means for calculating, and means (step 80) for estimating the valve equilibrium temperatures VTMPEQE and VTMPEQI based on the calorific value FHEAT for each predetermined time. For this reason, even at the time of the full-open operation or at the time of the rich combustion immediately after the start, the non-oxidized fuel does not generate heat, and it is possible to prevent the estimation error of the valve temperature from increasing due to the fuel and to more accurately estimate the internal EGR amount. In addition, drivability can be improved and fuel consumption and exhaust can be improved.
[0147]
Further, according to the present embodiment, the valve temperature estimated value calculating means calculates the differences VTMPDE, VTMPDI between the valve equilibrium temperatures VTMPEQE, VTMPEQI and the previous valve temperature estimated values VTMPE (-1), VTMPE (-1). (Step 81) and adding the predetermined ratios (VTMPDE × KVTMPE, VTMPDI × KVTMPI) of the differences VTMPDE and VTMPDI to the previous estimated valve temperature values VTMPE (−1) and VTMPE (−1) and estimating the valve temperature by the first-order lag. Means for updating the values VTMPE and VTMPI (steps 82 and 83). Therefore, the estimation accuracy of the valve temperatures VTMPE and VTMPI can be improved even when the valve equilibrium temperatures VTMPEQE and VTMPEQI suddenly change due to the fuel cut, or during a transition in which the balance between the amount of heat generation and the amount of heat radiation is lost, such as during start-up and acceleration. In addition, the internal EGR amount MRES can be accurately estimated, and deterioration in fuel efficiency, exhaust, and drivability can be prevented.
[0148]
Further, according to the present embodiment, the valve temperature estimated value updating 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 input of the REF signal of the crank angle sensor 14 for each calorific value due to combustion, and it is possible to follow the transitional phenomenon.
[0149]
Further, according to the present embodiment, the valve temperature estimated value calculating means includes initial setting means for initially setting the valve temperature estimated values VTMPE and VTMPI based on the engine coolant temperature TWN at the time of starting the engine (step S1). 78). Therefore, the valve temperatures VTMPE and VTMPI when the engine is stopped almost converge to the cooling water temperature TWN, so that the temperature can be estimated immediately after the start.
[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, 49) are independent of 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 due to the different temperature ranges of the intake valve 5 and the exhaust valve 6 and the different materials of the valves 5 and 6, the valve timing change amount is different. VTEOFS and VTIOFS are calculated, and the internal EGR amount MRES can be accurately estimated. By designing the intake and exhaust cam profiles, even when the valve timing is different, the valve timing can be calculated in consideration of the valve timing correction amounts VTHOSE and VTHOSI corresponding 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 actual valve timings VCLTRE and VCLTRI based on operation vibrations of the valves 5 and 6 under predetermined conditions (steps 63 to 66). Means for estimating the valve timing after correction based on the valve clearance amounts VCLE and VCLI under predetermined conditions (steps 63 to 66) (step 59) and the actual valve timings VCLTRE and VCLTRI and the estimated valve timings VCLTEE and VCLTEI. Means for calculating the errors VTHOSEtmp and VTHOSItmp (step 60); and means for calculating the valve timing correction learning values VTHOSE and VTHOSI based on the errors VTHOSEtmp and VTHOStmp (step 49). Further, the valve timing correction learning value VTHOSE the lube timing corrected by VTHOSI (step 50). For this reason, a region where the vibrations of the valves 5 and 6 can be accurately detected (a low rotation region where seating noise can be accurately detected, a low load region where knock does not occur, a valve timing basic change amount in which a valve timing error is unlikely to occur is 0 and a warm region). The actual valve timing (actual value of the valve closing timing) VCLTRE and VCLTRI can be detected in the post-machine region). An error between the actual valve timings VCLTRE and VCLTRI based on the detected value of the valve vibration and the estimated valve timings (estimated valve closing timings) VCLTEE and VCLTEI is due to wear. In this case, the valve timing is uniformly affected, so that an error due to deterioration with time can be prevented by correcting this error in advance.
[0152]
Further, according to the present embodiment, the actual valve timing calculating means (step 58) detects the operation vibration of the valve by the knock sensor 25. Therefore, the operation vibration at 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 means for calculating the in-cylinder gas amount when the exhaust valve is closed includes a means for calculating the in-cylinder volume VEVC when the exhaust valve is closed (steps 8 and 45), and the means for calculating the in-cylinder gas when the exhaust valve is closed. It includes temperature estimating means (steps 10 and 83), exhaust valve closing in-cylinder pressure calculating means (step 11), and gas constant calculating means (step 9), based on these calculated values. Then, the in-cylinder gas amount MRESCYL when the exhaust valve is closed is calculated by a physical equation (step 24). Therefore, in consideration of the in-cylinder volume VEVC when the exhaust valve is closed, the internal EGR amount MRES is 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. Then, even in the control construction including the multidimensional parameters, the internal EGR amount MRES is calculated based on the physical formula according to each parameter, so that the construction can be easily performed and the adaptation can be easily performed.
[0154]
Further, according to the present embodiment, the means for calculating the amount of gas to be blown back during the overlap (Steps 6 and 24) includes the means for estimating the in-cylinder temperature when the exhaust valve is closed (Steps 10 and 83) and the in-cylinder pressure when the exhaust valve is closed. Calculation means (Step 11), gas constant calculation means (Step 9), means for calculating intake pressure PIN (Step 25), and means for calculating specific heat ratio SHEATR corresponding to change in exhaust gas composition (Steps 15, 29) ), Means for calculating the effective area integrated value ASUMOLL during the overlap between the exhaust valve open period and the intake valve open period (step 13), means for calculating the engine speed NRPM (step 14), and supercharging TBCRG. And means for determining the presence / absence of choke CHOKE (steps 17, 18, and 20). Calculating the blown-back gas amount MRESOL during Rappu. For this reason, the blowback gas amount MRESOL can be calculated with high accuracy according to the state quantities during the overlap (the rotational speed NRPM, the exhaust gas specific heat ratio SHEATR, the supercharging TBCRG, and the choke CHOKE). Then, it is possible to cope with a change in density or a change in volume flow through the orifice due to a change in the state quantity, and it is possible to accurately calculate the amount MRESOL of the blown-back gas during the overlap 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. The present invention can be applied to a valve that is variable so that the valve overlap amount is variable.
[Brief description of the drawings]
FIG. 1 is a system configuration diagram of an internal EGR amount estimating apparatus.
FIG. 2 is a control configuration diagram of an internal EGR rate calculation unit.
FIG. 3 is a control configuration diagram of an internal EGR amount calculation unit;
FIG. 4 is a control configuration diagram of an in-cylinder gas amount calculation unit when the exhaust valve is closed.
FIG. 5 is a control configuration diagram of calculating the amount of blown-back gas during the overlap;
FIG. 6 is a control configuration diagram of an exhaust gas specific heat ratio calculation unit.
FIG. 7 is a control configuration diagram of a supercharging / choke determining unit.
FIG. 8 is a control configuration diagram for calculating the in-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 of temperature estimation calculation.
FIG. 15 is a flowchart for calculating an internal EGR rate.
FIG. 16 is an internal EGR amount calculation flow.
FIG. 17 is a flowchart for calculating the in-cylinder gas amount when the exhaust valve is closed.
FIG. 18 is a flow chart for calculating the amount of gas blown back during the overlap.
FIG. 19 is a flowchart for determining a supercharging / choke.
FIG. 20 is a flow chart for calculating the flow rate of blow-back gas when there is no supercharging and no choke
FIG. 21 is a flow chart for calculating a blowback gas flow rate when there is no supercharging and there is a choke.
FIG. 22 is a flow chart for calculating the flow rate of blow-back gas when there is supercharging and no choke
FIG. 23 is a flow chart for calculating a blowback gas flow rate when there is supercharging or choke.
FIG. 24 is a flowchart for calculating the cylinder volume when the exhaust valve is closed.
FIG. 25 is an exhaust valve timing change amount calculation flow.
FIG. 26 is a flow chart for calculating a valve clearance amount.
FIG. 27 is a flowchart for calculating a valve timing correction learning value.
FIG. 28 is a flowchart for calculating a valve timing actual value calculation permission flag.
FIG. 29 is a flow chart of calculating an effective area integrated value during overlap;
FIG. 30 is an intake valve timing change amount calculation flow.
FIG. 31 is a flowchart of temperature calculation.
FIG. 32 is a flowchart for calculating a calorific value;
FIG. 33: Exhaust gas gas constant calculation table
FIG. 34: Exhaust gas specific heat ratio calculation table
FIG. 35 is a mixture heat ratio calculation table.
FIG. 36 is an in-cylinder volume calculation table when the exhaust valve is closed.
FIG. 37 is an exhaust / intake valve timing change amount correction amount calculation table
FIG. 38 is a characteristic diagram of an effective area during overlap.
FIG. 39 is an explanatory diagram of an effective area integrated value during overlap.
FIG. 40 is a diagram showing a definition of the amount of change in exhaust valve timing in the positive and negative directions.
FIG. 41 is a diagram showing a definition of a positive / negative direction of an intake valve timing change amount.
FIG. 42 is a characteristic diagram showing a relationship between a calorific value and an 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 cam angle sensor
18 Accelerator opening sensor
25 Knock sensor
26 Starter switch
30 ECU

Claims (15)

Means for estimating the in-cylinder temperature when the exhaust valve is closed,
Means for calculating the in-cylinder pressure when the exhaust valve is closed,
Means for calculating a 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 a blowback gas amount during an overlap between the exhaust valve open period and the intake valve open period,
Means for calculating an internal EGR amount based on the in-cylinder gas amount and the blowback gas amount;
Is composed of
The in-cylinder temperature estimation means,
Means for calculating an in-cylinder equilibrium temperature that is an in-cylinder temperature in a steady state based on the engine operating state;
Means for calculating an in-cylinder temperature estimated value with a time delay with respect to the change in the in-cylinder equilibrium temperature,
An internal EGR amount estimating apparatus for an internal combustion engine, comprising: The in-cylinder equilibrium temperature calculating means is means for calculating a heat value for each predetermined time based on a parameter related to the heat value in the engine, and means for estimating the in-cylinder equilibrium temperature based on the heat value for each predetermined time, The internal EGR amount estimating device for an internal combustion engine according to claim 1, characterized in that: The in-cylinder temperature estimated value calculating means includes means for calculating a difference between the in-cylinder equilibrium temperature and a previous in-cylinder temperature estimated value, and a primary rate by adding a predetermined ratio of the difference to the last in-cylinder temperature estimated value. 3. The internal EGR amount estimating device for an internal combustion engine according to claim 1, further comprising means for updating an in-cylinder temperature estimated value based on a delay. 4. The internal EGR amount estimating device for an internal combustion engine according to claim 3, wherein the in-cylinder temperature estimated value updating unit updates the in-cylinder temperature estimated value for each fuel injection cycle. The cylinder temperature estimated value calculating means includes initial setting means for initially setting the cylinder temperature estimated value based on the engine cooling water temperature at the time of starting the engine. 4. The internal EGR amount estimating device for an internal combustion engine according to any one of 4. A variable valve timing mechanism that changes the opening / closing timing of at least one of the exhaust valve and the intake valve;
Means for calculating valve timing based on the opening / closing timing change amount of the variable valve timing mechanism;
Means for estimating the in-cylinder temperature at the time of closing the exhaust valve calculated by the valve timing calculating means,
Means for calculating the in-cylinder pressure at the time of closing the exhaust valve calculated by the valve timing calculating means,
Means for calculating a 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 a blowback gas amount during the overlap between the exhaust valve open period and the intake valve open period calculated by the valve timing calculating means,
Means for calculating an internal EGR amount based on the in-cylinder gas amount and the blowback gas amount;
Is composed of
The valve timing calculation means,
Means for estimating the valve temperature;
Means for estimating valve clearance according to the estimated value of valve temperature;
Means for correcting valve timing due to valve clearance;
Is composed of
The valve temperature estimating means,
Means for calculating a valve equilibrium temperature that is a valve temperature in a steady state based on the engine operating state;
Means for calculating a valve temperature estimated value with a time delay with respect to the change in the valve equilibrium temperature,
An internal EGR amount estimating apparatus for an internal combustion engine, comprising: The valve equilibrium temperature calculating means includes means for calculating a heat value for each predetermined time based on a parameter related to a heat value in the engine, and means for estimating a valve equilibrium temperature based on the heat value for each predetermined time. 7. The internal EGR amount estimating device for an internal combustion engine according to claim 6, wherein: The valve temperature estimated value calculating means calculates 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, and sets the valve temperature by a first-order lag. 8. The internal EGR amount estimating device for an internal combustion engine according to claim 6, further comprising means for updating an estimated value. 9. The internal EGR amount estimating device for an internal combustion engine according to claim 8, wherein the valve temperature estimated value updating means updates the valve temperature estimated value for each fuel injection cycle. 10. The valve temperature estimation value calculation means according to claim 6, wherein the valve temperature estimation value calculation means includes initial setting means for initially setting a valve temperature estimation value based on an engine cooling water temperature when the engine is started. An internal EGR amount estimating device for an internal combustion engine according to any one of the preceding claims. The valve temperature estimating means, the valve clearance estimating means, and the valve timing correcting means are provided independently for each of an intake valve and an exhaust valve, according to any one of claims 6 to 10, wherein An internal EGR amount estimating device for an internal combustion engine according to any one of the preceding claims. The valve timing correction means,
Means for calculating the actual valve timing based on the operating vibration of the valve under predetermined conditions,
Means for estimating valve timing after correction by valve clearance under predetermined conditions,
Means for calculating an error between the actual valve timing and the estimated valve timing,
Means for calculating a valve timing correction learning value based on the error,
With
12. The internal EGR amount estimating device for an internal combustion engine according to claim 6, wherein the valve timing is further corrected by the valve timing correction learning value. The internal EGR amount estimating device for an internal combustion engine according to claim 12, wherein the operation vibration of the valve is detected by a knock sensor. The in-cylinder gas amount calculating means at the time of closing the exhaust valve,
Means for calculating the cylinder volume when the exhaust valve is closed,
The exhaust valve closing in-cylinder temperature estimating means,
The exhaust valve closing in-cylinder pressure calculating means,
The gas constant calculation means,
The method according to any one of claims 1 to 13, wherein the in-cylinder gas amount at the time of closing the exhaust valve is calculated by a physical equation based on these calculated values. An internal EGR amount estimating device for an internal combustion engine. The overlapped blow-back gas amount calculating means,
The exhaust valve closing in-cylinder temperature estimating means,
The exhaust valve closing in-cylinder pressure calculating means,
The gas constant calculation means,
Means for calculating the intake pressure;
Means for calculating a specific heat ratio corresponding to the exhaust gas composition change,
Means for calculating an effective area integrated value during the overlap between the exhaust valve open period and the intake valve open period,
Means for calculating the engine speed;
Means for determining the presence or absence of supercharging and chalk;
The internal EGR amount of the internal combustion engine according to any one of claims 1 to 14, wherein the amount of the blowback gas during the overlap is calculated based on the calculated values. Estimation device.

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