JP2004225654A - Internal EGR amount estimation device for internal combustion engine - Google Patents

Abstract

An object of the present invention is to estimate a valve clearance, correct a valve timing based on the valve clearance, and more accurately estimate an internal EGR amount.
A valve timing is calculated based on a change amount of opening / closing timing of variable valve solenoids (22, 23). The in-cylinder gas amount is calculated from the inner volume. Further, the blowback gas amount during the overlap between the intake valve open period and the exhaust valve open period is calculated. Then, the internal EGR amount is calculated based on the calculated values of the in-cylinder gas amount and the blowback gas amount. Here, when calculating the valve timing, the valve clearance amount is estimated based on the valve temperature, and thereby the valve timing is corrected.
[Selection diagram] Fig. 1

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, when the operating state changes, for example, during cold operation after starting, after fuel cut operation during deceleration, or at high water temperature during high-speed high-load operation, valve components (particularly shafts) Due to the thermal expansion of the part, the valve clearance changes, the overlap time differs from the actual one, and the error of the actual internal EGR amount with respect to the internal EGR amount calculation value increases. For this reason, the actual ignition timing and the actual required injection amount cannot be satisfied, and there is a possibility that the drivability is deteriorated and the fuel consumption and the exhaust are deteriorated.
[0006]
The present invention has been made to solve the above problem, and has as its object to estimate the valve clearance, correct the valve timing based on the valve clearance, and more accurately estimate the internal EGR amount.
[0007]
[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 opening / closing timing change amount of the variable valve timing mechanism, but the valve clearance is estimated and the valve timing is corrected based on the valve clearance. . 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 these, the in-cylinder gas amount when the exhaust valve is closed is calculated. calculate. Then, the blow-back gas amount during the overlap between the exhaust valve open period and the intake valve open period is calculated, and the internal EGR amount is calculated based on the in-cylinder gas amount and the blow-back gas amount.
[0008]
【The invention's effect】
According to the present invention, since the valve clearance is estimated and the valve timing is corrected based on the valve clearance, the internal EGR amount can be estimated with higher accuracy, and the ignition timing, the fuel injection amount, and the like can be appropriately set. In addition, drivability can be improved and fuel efficiency and exhaust can be improved.
[0009]
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.
[0010]
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.
[0011]
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.
[0012]
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.
[0013]
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.
[0014]
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. An exhaust gas temperature sensor 12 for detecting an exhaust gas temperature in the exhaust gas passage 8, an O2 sensor (oxygen sensor) 13 for detecting an oxygen concentration contained in the exhaust gas in the exhaust gas passage 8, and a water temperature sensor for detecting a cooling water temperature of the engine 1. 15. The output signals of the accelerator opening sensor 18 for detecting the accelerator opening and the knock sensor 25 for detecting the vibration of the engine 1 (particularly knocking vibration) are also input to the ECU 30, and 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.
[0015]
Next, the estimation of the internal EGR amount and the internal EGR rate performed by the ECU 30 will be described below. 2 to 13 are control configuration diagrams, FIGS. 14 to 29 are control flowcharts, and FIGS. 30 to 37 are tables for obtaining respective values.
[0016]
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.
[0017]
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.
[0018]
In step 1 in FIG. 14 (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.
[0019]
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.
[0020]
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.
[0021]
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.
[0022]
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.
[0023]
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.
[0024]
In step 5 of FIG. 15, an in-cylinder exhaust valve gas amount MRESCYL, which is an amount of gas remaining in the cylinder when the exhaust valve is closed, is calculated according to a flowchart of FIG.
[0025]
In step 6, according to the flowchart of FIG. 17 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.
[0026]
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.
[0027]
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 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. A description will be given using a gas amount MRESCYL calculation flow.
[0028]
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.
[0029]
In step 8 in FIG. 16, the in-cylinder volume VEVC when the exhaust valve is closed is determined according to the flowchart in FIG. 23 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. 30 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. The dotted line in FIG. 30 indicates stoichiometry.
[0030]
In step 10, the in-cylinder temperature TEVC when the exhaust valve is closed is estimated based on the exhaust gas temperature detected based on the signal of the exhaust gas temperature sensor 12. Since the in-cylinder temperature TEVC at the time of closing the exhaust valve changes depending on the amount of heat corresponding to the fuel injection amount of the injector 20, it may be obtained from a table utilizing such characteristics.
[0031]
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.
[0032]
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.
[0033]
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. 9, the 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 using a gas amount MRESOL calculation flow.
[0034]
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. 28 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.
[0035]
In step 13 in FIG. 17, the effective area during overlap ASAMOL is calculated according to the flowchart in FIG. 28 described later.
In step 14, the engine speed NRPM is calculated based on the signal of the crank angle sensor 14.
[0036]
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.
[0037]
FIG. 31 is an exhaust gas specific heat ratio calculation map. 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 in accordance with the target combustion equivalent ratio TFBYA calculated in step 2 of FIG. 14 and the exhaust valve closing cylinder temperature TEVC calculated in step 10 of FIG.
[0038]
In step 16, the supercharging determination TBCRG and the choke determination CHOKE are performed according to the control configuration diagram of the supercharge / choke determination means of FIG. 7 described later and the supercharge determination TBCRG / choke determination CHOKE flow of FIG.
[0039]
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.
[0040]
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 routine proceeds to step 19, where the flow rate of the blowback gas MRESOLtmp during the overlap without supercharging and without the choke is calculated from the flow of FIG.
[0041]
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. 20 described below, the blowback gas flow rate MRESOLtmp during the overlap when there is no supercharging and choke is present. Is calculated.
[0042]
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.
[0043]
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 blowback gas flow rate MRESOLtmp at the time of supercharging and choking is calculated from the flow of FIG.
[0044]
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.
[0045]
MRESOL = (MRESOLtmp × ASUMOL × 60) / (NRPM × 360) (5)
Here, the supercharging / choke judgment in step 16 will be described with reference to the control configuration diagram of the supercharging / choke judging means in FIG. 7 and the flow of the supercharging judgment TBCRG / choke judgment CHOKE in FIG.
[0046]
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.
[0047]
In step 25 of FIG. 18, 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. 16, that is, the intake exhaust pressure The ratio PINBYEX is calculated by the following equation.
[0048]
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.
[0049]
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.
[0050]
On the other hand, if the intake / exhaust pressure ratio PINBYEX is larger than 1, that is, if there is 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. 32 (SHEATR = MIXAIRSHR).
[0051]
FIG. 32 is a mixture specific heat ratio MIXAIRSHR calculation table. 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. 14 is obtained from the table.
[0052]
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.
[0053]
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.
[0054]
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.
[0055]
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.
[0056]
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.
[0057]
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.
[0058]
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.
[0059]
Further, the calculation of the blowback gas flow rate MRESOLtmp in step 19 in FIG. 17 will be described using the flow of calculating the blowback gas flow rate during overlap without supercharging and without choke in FIG.
[0060]
In step 34, the density term MRSOLD of the gas flow rate calculation equation is calculated based on the gas constant REX of the exhaust gas calculated in step 9 in FIG. 16 and the in-cylinder temperature TEVC when the exhaust valve is closed calculated in step 10. It is calculated by the formula.
[0061]
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.
[0062]
In step 35, based on the exhaust gas specific heat ratio SHEATR calculated in step 15 of FIG. 17 and the intake exhaust pressure ratio PINBYEX calculated in step 25 of FIG. 18, the gas flow rate calculation equation pressure difference term MRSOLP is calculated by the following equation. calculate.
[0063]
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. 16, 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.
[0064]
MRESOLtmp = 1.4 × PEVC × MRSOLD × MRSOLP (10)
The blow-back gas flow rate MRESOLtmp in step 20 will be described with reference to the flow chart of FIG. 20 for calculating the blow-back gas flow rate when there is no supercharging and choke is present.
[0065]
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 obtained by the following equation based on the exhaust gas specific heat ratio SHEATR calculated in step 15 in FIG.
[0066]
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.
[0067]
In step 39, the in-cylinder pressure PEVC at the time of closing the exhaust valve calculated in step 11 of FIG. 16, the gas flow rate calculation equation density term MRSOLD calculated in step 37 of FIG. 20, 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.
[0068]
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. 21 for calculating the blowback gas flow rate with supercharging and without choke.
[0069]
In step 40, based on the exhaust gas specific heat ratio SHEATR calculated in step 29 of FIG. 17 and the intake / exhaust pressure ratio PINBYEX calculated in step 25, a gas flow rate calculation supercharging pressure difference term MRSOLPT is calculated by the following equation. Ask.
[0070]
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.
[0071]
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.
[0072]
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.
[0073]
The calculation of the blowback gas flow rate MRESOLtmp in step 23 will be described with reference to the flow chart of FIG.
[0074]
In step 42, similarly to step 38 in FIG. 20, the choke-time pressure difference term MRSOLPC in the gas flow rate calculation equation is obtained from equation (11) or a 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.
[0075]
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.
[0076]
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. Then, after calculating the amount MRESOL of the blown-back gas during the overlap in step 24 described above, the process proceeds from step 6 to step 7 in FIG. 15, 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. 14 to calculate the above-mentioned internal EGR rate MRESFR, and ends the processing.
[0077]
Further, regarding the calculation of the in-cylinder volume VEVC when the exhaust valve is closed in step 8 in FIG. 16, 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.
[0078]
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.
[0079]
In step 44 of FIG. 23, 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.
[0080]
In step 45, the in-cylinder volume VEVC when the exhaust valve is closed is obtained from the table shown in FIG. 33 according to the exhaust valve timing change amount VTEOFS.
FIG. 33 is a calculation table of the in-cylinder volume VEVC when the exhaust valve is closed. The abscissa indicates the exhaust valve timing change amount VTEOFS, and the abscissa indicates the in-cylinder volume VEVC when the exhaust valve is closed.
[0081]
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.
[0082]
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. 23 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.
[0083]
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.
[0084]
In step 46 of FIG. 24, the basic exhaust valve timing 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.
[0085]
In step 47, the valve clearance amount VCLE is calculated according to the flowchart of FIG. 25 described later.
In step 48, an exhaust valve timing variation correction amount VTCLE is obtained from the table shown in FIG. 34A in accordance with the exhaust valve clearance amount VCLE.
[0086]
FIG. 34A 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 amount (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.
[0087]
In step 49 of FIG. 24, a valve timing correction learning value VTHOSE is calculated according to a flowchart of FIG. 26 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.
[0088]
VTEOFS = VTCNOWE + VTCLE + VTHOSE (16) Here, regarding the calculation of the valve clearance amount VCLE in step 47, the control configuration diagram of the calculation of the exhaust valve clearance amount VCLE in FIG. 10 and the valve clearance amount VCLE calculation flow in FIG. 25 are used. Will be explained.
[0089]
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 may be an input by a sensor that directly measures the temperature.
[0090]
In step 51 of FIG. 25, the exhaust valve temperature VTMPE is obtained from the table shown in FIG. 35 according to the fuel injection amount. In this flow, the intake valve 5 and the exhaust valve 6 are calculated independently of each other. However, since the processing is the same, the exhaust valve 6 will be described.
[0091]
FIG. 35 is a valve temperature calculation table in a steady state. The horizontal axis indicates the fuel injection amount, and the vertical axis indicates the exhaust valve temperature VTMPE representing the engine load. FIG. 35A shows the exhaust valve 6 and FIG. 35B shows the intake valve 5, and shows that the valve temperature VTMPE increases as the fuel injection amount increases. 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.
[0092]
TI = TP × TFBYA × LAMBDA (17)
In step 52 of FIG. 25, the provisional valve clearance amount VCLEtmp is calculated according to the following equation in accordance with the exhaust valve temperature VTMPE.
[0093]
VCLEtmp = −KVTMPE × (VTMPE−90) + VCLSTDE (18)
Here, -KVTMPE is a coefficient relatively determined by the material and length of the exhaust valve 6, and mainly considers the case where the expansion of the valve 6 in the axial direction is large, and also considers the expansion of the other (for example, the cylinder head). It is decided not to do it. 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.
[0094]
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, 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.
[0095]
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. 24 will be described with reference to 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.
[0096]
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 a valve timing correction learning value VTHOSE based on the valve closing timing estimated value VCLTEE and the actual valve closing timing VCLTRE.
[0097]
In step 56 of FIG. 26, a valve timing actual value calculation permission flag FVTHOSE is calculated according to a flowchart of FIG. 27 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 detected. If the flag FVTHOSE = 1, the process proceeds to step 58. On the other hand, if the flag FVTHOSE = 0, the process returns.
[0098]
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).
[0099]
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.
[0100]
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 (at the time of warming).
[0101]
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).
[0102]
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.
[0103]
In step 62, the provisional valve timing correction amount VTHSEtmp is substituted for the valve timing correction learning value VTHOSE (VTHOSE = VTHOSEtmp).
[0104]
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 closing timing is advanced.
[0105]
Here, the calculation of the actual valve timing value calculation permission flag FVTHOSE in step 56 will be described using the flow chart for calculating the actual valve timing value calculation permission flag FVTHOSE in FIG.
[0106]
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.
[0107]
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.
[0108]
Next, regarding the calculation of the effective area integrated value during overlap ASAMOL in step 13 of FIG. 17, the control configuration diagram of the calculation of the effective area during overlap in FIG. 12 and the flow of calculating the effective area during overlap in FIG. It will be described using FIG.
[0109]
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.
[0110]
In step 69 of FIG. 28, the intake valve timing change amount VTIOFS is calculated according to the flowchart of FIG. 29 described later.
In step 70, the exhaust valve timing change amount VTEOFS is calculated according to the flowchart of FIG.
[0111]
In step 71, the overlapped effective area integrated value ASAMOL is obtained from the overlapped effective area integrated value ASAMOL map shown in FIG. 36 according to the intake valve timing change amount VTIOFS and the exhaust valve timing change amount VTEOFS.
[0112]
FIG. 36 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.
[0113]
Here, FIG. 37 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.
[0114]
Next, the calculation of the intake valve timing change amount VTIOFS in step 69 in FIG. 28 is performed using the control configuration diagram of the intake valve timing change amount VTIOFS calculation in FIG. 13 and the intake valve timing change amount 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.
[0115]
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.
[0116]
In step 72 of FIG. 29, 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 cam angle sensor 16.
[0117]
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.
[0118]
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 considers a case where the expansion of the valve 5 in the axial direction is large, and also considers the expansion of the other (for example, a cylinder head or the like). It is decided not to do it. VCLSTDI is a reference valve clearance amount (clearance amount in a warm state (about 90 ° C.)).
[0119]
In step 74, an intake valve timing change amount correction amount VTCLI is obtained from the table shown in FIG. 34B according to the intake valve clearance amount VCLI.
[0120]
FIG. 34 (b) is an intake valve timing variation correction amount VTCLI calculation table. The horizontal axis indicates the intake valve clearance amount VCLI, and the vertical axis indicates the intake valve timing variation 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.
[0121]
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. 26, the signal of 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 the signal of the crank angle sensor 14 , The valve lift timing, that is, the actual valve opening timing VCLTRI (degBTDC) is calculated.
[0122]
In step 59, the valve opening timing estimated value VCLTEI is calculated by the following equation.
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.
[0123]
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.
[0124]
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.
[0125]
VTIOFS = VTCNOW + VTCLI + VTHOSI (22)
Here, FIG. 38 is a diagram showing the definition of the change amount of the exhaust valve timing in the positive and negative directions, and FIG. 39 is a diagram showing the definition of the change amount of the intake valve timing in the positive and negative directions.
[0126]
In FIG. 38, the exhaust valve timing change amount is positive on the advance side (clockwise). In FIG. 39, the amount of change in intake valve timing is positive on the retard side (counterclockwise). Both the intake valve 5 and the exhaust valve 5 are in the direction of increasing the overlap amount.
[0127]
According to the present embodiment, the valve timing variable mechanisms (variable valve solenoids) 22, 23 for changing the opening / closing timing of the exhaust valve 6 and the intake valve 5, and the opening / closing timing change amounts VTEOFS, VTIOFS of the variable valve timing mechanisms 22, 23. Means for calculating the valve timing based on the above, means for calculating the in-cylinder temperature TEVC at the time of closing the exhaust valve calculated by the valve timing calculating means (step 10), and closing of the exhaust valve calculated by the valve timing calculating means. Means for calculating the in-cylinder pressure PEVC at the time of the valve (step 11), means for calculating the gas constant REX of the exhaust gas composition corresponding to the combustion air-fuel ratio (step 9), at least the in-cylinder temperature TEVC and the in-cylinder pressure PEVC , Based on the gas constant REX, the in-cylinder gas amount MRESC when the exhaust valve is closed. Means for calculating L (steps 5 and 12); means for calculating the blowback gas amount MRESOL during the overlap between the exhaust valve opening period and the intake valve opening period based on the calculation result of the valve timing calculating means (steps 6 and 12). 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), and the valve timing calculating means estimates the valve clearance amount VCLE. (Step 47) and means (Steps 48 and 49) for correcting the valve timing based on the valve clearance amount VCLE. For this reason, since the valve clearance amount VCLE is estimated and the valve timing is corrected based on this, it is possible to suppress the estimation error of the internal EGR amount MRES caused by a change in the valve clearance amount VCLE. Then, by appropriately setting the ignition timing, the fuel injection amount, and the like based on the internal EGR amount MRES, it is possible to improve drivability and improve fuel economy and exhaust. Further, the internal EGR amount MRES can be calculated from the physical equation (Equation 3) based on the state quantity (temperature TEVC / pressure PEVC / gas constant REX) inside the cylinder after the end of combustion. Then, it is possible to cope with a density change due to a change in temperature and pressure, a density change due to a change in gas constant due to a change in the combustion air-fuel ratio, and the like, and it is possible to accurately estimate the internal EGR amount MRES regardless of operating conditions. In particular, in the transient operation state, since the state quantity inside the cylinder changes every moment, the internal EGR amount MRES can be calculated based on the changing state quantity, so that the estimation accuracy of the internal EGR amount MRES during the transient operation is obtained. Can be improved. Further, even in the control construction including the multidimensional parameters, the internal EGR amount MRES is calculated based on the physical equation according to each parameter, and each control value is determined based on this value MRES. it can.
[0128]
Further, according to the present embodiment, the means for calculating the in-cylinder gas amount when the exhaust valve is closed (steps 5 and 12) includes a means for calculating the in-cylinder volume VEVC when the exhaust valve is closed (steps 8 and 45) and the exhaust gas. A valve closing valve in-cylinder temperature calculating means (Step 10), an exhaust valve closing in-cylinder pressure calculating means (Step 11), and a gas constant calculating means (Step 9) are included. Based on the value, the in-cylinder gas amount MRESCYL when the exhaust valve is closed is calculated by a physical equation (Equation 3) (step 12). 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.
[0129]
Further, according to the present embodiment, the in-cylinder volume calculation means (step 8) when the exhaust valve is closed determines the in-cylinder volume value VEVC that is geometrically determined from the piston position when the exhaust valve is closed. Therefore, it is possible to appropriately calculate the in-cylinder volume VEVC when the exhaust valve is closed, and to obtain a more accurate internal EGR amount MRES. Even in an engine having a mechanism (variable valve opening / closing timing, variable compression ratio) in which the in-cylinder volume VEVC changes when the exhaust valve is closed, the in-cylinder volume VEVC can be easily obtained, and a more accurate internal EGR amount MRES is obtained. Can be calculated. Then, since each value is determined geometrically, it can be easily calculated, and it is not necessary to adapt it by actual operation, and development can be performed efficiently.
[0130]
Further, according to the present embodiment, the gas constant calculation means (step 9) obtains the gas constant REX corresponding to the change in the exhaust gas composition according to the target combustion equivalent ratio TFBYA. For this reason, even when there is a density change due to a change in the exhaust gas composition in accordance with the target combustion equivalent ratio TFBYA, that is, when the target combustion equivalent ratio TFBYA increases or decreases after the operating state is switched, such as after lean operation or startup. , The internal EGR amount MRES can be accurately estimated. The gas constant REX can be calculated from a chemical reaction formula based on the fuel composition and the air composition, and it is not necessary to adapt the gas operation in actual operation, and development can be performed efficiently.
[0131]
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 a means for calculating the in-cylinder temperature when the exhaust valve is closed (Step 10) and a means for calculating the in-cylinder pressure when the exhaust valve is closed. (Step 11), means for calculating gas constant (Step 9), means for calculating intake pressure PIN (Step 25), and means for calculating specific heat ratio SHEATR corresponding to a change in exhaust gas composition (Steps 15, 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), supercharging TBCRG and choke Means (steps 17, 18, and 20) for determining the presence or absence of a CHOKE. Calculating the blown-back gas amount MRESOL during flop. 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.
[0132]
Further, according to the present embodiment, the valve clearance amount estimating means (step 47) is configured to include means (step 51) for calculating the valve temperatures VTMPE and VTMPI, and the valve clearance amount is determined according to the valve temperatures VTMPE and VTMPI. VCLE and VCLI are estimated (steps 52 to 55). For this reason, since the valve clearances VCLE and VCLI are calculated based on the temperature factor that has the largest effect on the valve clearance, even when the temperature change such that the output becomes large after the engine is cold becomes large, the valve clearance may be increased. The amounts VCLE and VCLI can be appropriately estimated, and an internal EGR amount estimation error due to a valve timing error can be suppressed.
[0133]
Further, according to the present embodiment, the valve temperature calculating means (step 51) includes an engine load calculating means, and estimates the valve temperatures VTMPE and VTMPI according to the engine load. Therefore, the valve temperatures VTMPE and VTMPI can be estimated without providing a special temperature sensor, and the cost can be reduced.
[0134]
Further, according to the present embodiment, the valve clearance amount estimating means (step 47) and the valve timing correcting means (steps 48 and 49) are provided independently for each of the intake valve 5 and the exhaust valve 6. 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 / exhaust cam profile, 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 can be estimated.
[0135]
According to the present embodiment, the valve timing correction means (step 49) detects the actual valve timings VCLTRE and VCLTRI based on the operation vibration of the valves 5 and 6 under predetermined conditions (steps 63 to 66). (Step 58), means for estimating the valve timing after correction by the valve clearance amounts VCLE and VCLI under predetermined conditions (steps 63 to 66) (step 59), actual valve timings VCLTRE and VCLTRI, and estimated valve timing VCLTEE. , VTHOSemp and VTHOStmp (step 60), and means for calculating the valve timing correction learning values VTHOSE and VTHOSI based on the errors VTHOStmp and VTHOStmp (step 60). 0) and comprising a further said valve timing correction learning value VTHOSE valve timing corrected by VTHOSI. 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.
[0136]
According to the present embodiment, the operation vibration of the valve of the actual valve timing calculation means (step 58) is detected 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.
[0137]
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 an internal EGR rate calculation flow.
FIG. 15 is an internal EGR amount calculation flow.
FIG. 16 is a flowchart for calculating the in-cylinder gas amount when the exhaust valve is closed.
FIG. 17 is a flow chart for calculating the amount of gas blown back during the overlap.
FIG. 18 is a flowchart of a supercharging determination / choke determination
FIG. 19 is a flow chart for calculating a blowback gas flow rate when there is no supercharging and no choke.
FIG. 20 is a flow chart for calculating the flow rate of blow-back gas when there is no supercharging and there is a choke.
FIG. 21 is a flow chart for calculating the flow rate of blow-back gas when there is supercharging and no choke
FIG. 22 is a flow chart for calculating the flow rate of blow-back gas when there is a supercharge and a choke is present.
FIG. 23 is a flow chart for calculating the in-cylinder volume when the exhaust valve is closed.
FIG. 24 is an exhaust valve timing change amount calculation flow.
FIG. 25 is a flowchart for calculating a valve clearance amount.
FIG. 26 is a flowchart of calculating a valve timing correction learning value.
FIG. 27 is a flowchart for calculating a valve timing actual value calculation permission flag.
FIG. 28 is a flowchart of calculating the effective area integrated value during the overlap.
FIG. 29 is an intake valve timing change amount calculation flow.
FIG. 30 is an exhaust gas constant calculation table
FIG. 31 is an exhaust gas specific heat ratio calculation map.
FIG. 32 is a mixture heat ratio calculation table.
FIG. 33 is an in-cylinder volume calculation table when the exhaust valve is closed.
FIG. 34 is an exhaust / intake valve timing change amount correction amount calculation table
FIG. 35 is an exhaust / intake valve temperature calculation table
FIG. 36 is an effective area characteristic diagram during overlap.
FIG. 37 is an explanatory diagram of an effective area integrated value during overlap.
FIG. 38 is a diagram showing the definition of the amount of change in the exhaust valve timing in the positive and negative directions.
FIG. 39 is a diagram showing a definition of a positive / negative direction of an intake valve timing change amount.
[Explanation of symbols]
1 engine
5 Intake valve
6 Exhaust valve
9 Air flow meter
10 Intake pressure sensor
11 Exhaust pressure sensor
12 Exhaust gas temperature sensor
13 O2 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
30 ECU

Claims (10)

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 calculating 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 based on the calculation result of the valve timing calculating means,
Means for calculating an internal EGR amount based on the in-cylinder gas amount and the blowback gas amount,
The valve timing calculation means,
Means for estimating valve clearance;
An internal EGR amount estimating apparatus for an internal combustion engine, comprising: means for correcting a valve timing by a valve clearance. 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 calculating means,
The exhaust valve closing in-cylinder pressure calculating means,
The gas constant calculation means,
2. The internal EGR amount estimating device for an internal combustion engine according to claim 1, wherein the in-cylinder gas amount when the exhaust valve is closed is calculated by a physical equation based on the calculated values. 3. The internal EGR amount estimation of an internal combustion engine according to claim 2, wherein said exhaust valve closing cylinder volume calculation means calculates a cylinder volume value which is geometrically determined from a piston position when the exhaust valve is closed. apparatus. The internal combustion engine according to any one of claims 1 to 3, wherein the gas constant calculation means obtains a gas constant corresponding to a change in exhaust gas composition according to a target combustion equivalent ratio. EGR amount estimation device. The overlapped blow-back gas amount calculating means,
The exhaust valve closing in-cylinder temperature calculating 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;
5. A means for judging the presence or absence of supercharging and choke, and calculates the blowback gas amount during the overlap based on these calculated values. The internal EGR amount estimating device for an internal combustion engine according to any one of the preceding claims. The valve clearance estimating means is configured to include a means for calculating a valve temperature, and estimates the valve clearance according to the valve temperature. An internal EGR amount estimating device for an internal combustion engine. 7. The internal EGR amount estimating device for an internal combustion engine according to claim 6, wherein the valve temperature calculating means includes an engine load calculating means, and estimates the valve temperature according to the engine load. The internal EGR of an internal combustion engine according to any one of claims 1 to 7, wherein the valve clearance estimating means and the valve timing correcting means are provided independently for each of an intake valve and an exhaust valve. Quantity estimation device. 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,
9. The internal EGR amount estimating apparatus for an internal combustion engine according to claim 1, 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 9, wherein the operation vibration of the valve is detected by a knock sensor.

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