JP2010084549A - Control device and method for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve such a problem that a multidimensional map of which axes are at least a revolution number, a load, valve timing, and the atmospheric pressure is required to take into consideration influence of an amount of highland correction, in which the atmospheric pressure is reduced, in structure calculating the controlled variables of ignition timing based on the revolution number, load, and valve timing so that the scale of the map mounted on an ECU becomes large to increase required memory capacity. <P>SOLUTION: The control device calculates a packing efficiency reference value and an EGR amount reference value based on a polynominal expression using at least the revolution number, intake absolute pressure, the atmospheric absolute pressure or exhaust absolute pressure, and variable valve controlled variables as input, and performs highland correction by a ratio of the intake absolute pressure to the atmospheric absolute pressure. Under a highland condition in which the highland-corrected atmospheric pressure is decreased, a fuel injection amount is calculated based on the highland-corrected packing efficiency, and ignition timing is calculated based on the revolution number, highland-corrected packing efficiency, and the highland-corrected EGR amount. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a control device for an internal combustion engine that suitably controls fuel injection amount and ignition timing under high altitude conditions of the internal combustion engine having a variable valve.

  In an internal combustion engine for automobiles in recent years, an internal combustion engine having a variable valve mechanism in which a valve timing or a valve lift amount is variable in intake valves and exhaust valves tends to be generalized. The variable valve mechanism has been improved in technology from the viewpoint of increasing the degree of freedom of control, expanding the operation range, and improving the response. In particular, a variable valve mechanism that can continuously variably control the valve lift amount has been developed, and the amount of air drawn into the cylinder by the lift continuously variable valve mechanism is controlled by an intake valve instead of the throttle valve. Therefore, an internal combustion engine that realizes a reduction in pump loss and a mirror cycle has been developed. In a control device for an internal combustion engine equipped with such a variable valve mechanism, the amount of intake air flowing through the intake pipe is detected or estimated by an air flow sensor or a pressure sensor provided in the intake pipe. The efficiency is calculated, and the fuel injection amount and the control amount of the ignition timing are calculated based on the charging efficiency.

  Japanese Patent Application Laid-Open No. 9-209895 discloses a technique for suitably correcting the ignition timing in accordance with the deviation of the actual valve timing from the basic valve timing. In the technique disclosed in Japanese Patent Laid-Open No. 9-209895, when the valve timing shifts to the retard side, the combustion speed associated with a decrease in the internal EGR amount (EGR: Exhaust Gas Recirculation) in the low load range. The ignition timing is corrected to the retarded angle side in response to the increase in the ignition timing, and the ignition timing is corrected to the advanced angle side in response to a decrease in the combustion speed accompanying a decrease in the actual compression ratio in the high load range. On the other hand, when the valve timing shifts to the advance side, the ignition timing is corrected to the advance side to cope with the decrease in the combustion speed accompanying the increase in the internal EGR amount in the low load region, and in the high load region. Corrects the ignition timing to the retard side in order to cope with an increase in the combustion speed accompanying an increase in the actual compression ratio.

Japanese Patent Laid-Open No. 9-209895

  However, in a state where the atmospheric pressure decreases, such as in a high altitude condition, the internal EGR amount that changes based on the valve timing is also affected by the state of the atmospheric pressure. The correction cannot be performed accurately. In addition, since the change in the actual compression ratio when the valve timing deviates to the advance side or the retard side also varies depending on the valve operation angle, in a variable valve with variable valve operation angle, only the valve timing deviation Therefore, the change in the actual compression ratio cannot be taken into consideration. Further, in the configuration for calculating the ignition timing control amount based on the rotational speed, the load, and the valve timing, when considering the above-described effect of the high altitude correction that reduces the atmospheric pressure, at least the rotational speed, the load, the valve timing, and the large Since a multidimensional map with the atmospheric pressure as an axis is required, there is a problem that the map mounted on the ECU becomes large and the memory capacity increases.

  The present invention has been made in order to solve the above-described problems. The object of the present invention is to achieve charging efficiency and EGR even when the variable valve is controlled in a state where the atmospheric pressure is lowered as in the high altitude conditions. It is an object of the present invention to provide a control device for an internal combustion engine that can accurately calculate the amount and suitably control the ignition timing and the fuel injection amount based on these.

A control device for an internal combustion engine provided with a variable valve,
Means for calculating the charging efficiency based on at least the rotational speed, the absolute intake pressure, the atmospheric absolute pressure or the exhaust absolute pressure, and the variable valve control amount; at least the rotational speed, the intake absolute pressure, the atmospheric absolute pressure or the exhaust absolute pressure, and the variable valve control amount; Means for calculating an EGR amount on the basis of, a means for calculating a fuel injection amount on the basis of at least the charging efficiency, and a means for calculating an ignition timing on the basis of at least the rotational speed, the charging efficiency, and the EGR amount,
A control device for an internal combustion engine.

  According to the first aspect of the present invention, since the charging efficiency is calculated based on at least the rotational speed, the absolute intake pressure, the atmospheric absolute pressure or the exhaust absolute pressure, and the variable valve control amount, it is accurate even in high altitude conditions where the atmospheric pressure decreases. The filling efficiency can be calculated well. In addition, since the EGR amount is calculated based on at least the rotational speed, the absolute intake pressure, the atmospheric absolute pressure or the exhaust absolute pressure, and the variable valve control amount, the EGR rate can be accurately calculated even under high altitude conditions where the atmospheric pressure decreases. . In addition, since the fuel injection amount is calculated based on the charging efficiency calculation means corresponding to at least the high altitude conditions, the air-fuel ratio control can be performed with high accuracy even in the high altitude conditions where the atmospheric pressure is reduced, and the deterioration of fuel consumption and exhaust is avoided. can do. Furthermore, since the ignition timing is calculated based on at least the charging efficiency calculating means corresponding to the rotational speed and the high altitude condition and the EGR amount calculating means corresponding to the high altitude condition, the ignition timing control is performed accurately even in the high altitude condition where the atmospheric pressure decreases. It is possible to avoid deterioration of fuel consumption and torque reduction.

  According to the second aspect of the present invention, the intake relative pressure, which is the ratio of the intake absolute pressure to the atmospheric absolute pressure or the exhaust absolute pressure, is calculated, and the charging efficiency is based on at least the rotational speed, the intake relative pressure, and the variable valve control amount. Calculate the reference value. Further, the high altitude correction amount is calculated based on the ratio between the atmospheric absolute pressure and the atmospheric absolute reference pressure, and the charging efficiency under the high altitude condition is calculated by the product of the charging efficiency reference value and the high altitude correction amount. Therefore, it is possible to calculate the charging efficiency with high accuracy even in high altitude conditions where atmospheric pressure decreases.

  According to the third aspect of the present invention, the intake relative pressure, which is the ratio of the intake absolute pressure to the atmospheric absolute pressure or the exhaust absolute pressure, is calculated, and the internal EGR is based on at least the rotational speed, the intake relative pressure, and the variable valve control amount. Calculate the quantity reference value. Further, the high altitude correction amount is calculated based on the ratio between the atmospheric absolute pressure and the atmospheric absolute reference pressure, and the internal EGR amount under the high altitude condition is calculated by the product of the filling efficiency reference value and the high altitude correction amount. Therefore, the internal EGR amount can be calculated with high accuracy even under high altitude conditions where atmospheric pressure decreases.

  According to the fourth aspect of the present invention, since the exhaust absolute pressure is calculated based on at least the rotational speed, the charging efficiency, the exhaust temperature, and the atmospheric absolute pressure, the exhaust absolute pressure can be calculated accurately even under high altitude conditions where the atmospheric pressure decreases. can do.

  According to the invention described in claim 5, since the exhaust pressure sensor for measuring the exhaust absolute pressure is provided in the exhaust flow path, it is possible to detect the exhaust absolute pressure with high accuracy even in high altitude conditions where the atmospheric pressure decreases. it can.

  According to the sixth aspect of the invention, the exhaust gas temperature is calculated based on at least the ignition timing, the air-fuel ratio, and the EGR rate, so that the exhaust gas temperature can be calculated with high accuracy.

  According to the seventh aspect of the present invention, since the exhaust gas temperature sensor for measuring the exhaust gas temperature is provided in the exhaust gas channel, the exhaust gas temperature can be detected with high accuracy.

  According to the eighth aspect of the present invention, since the external EGR amount is calculated based on at least the exhaust absolute pressure, the exhaust temperature, the external EGR valve opening, and the intake absolute pressure, even under high altitude conditions where the atmospheric pressure decreases. The amount of external EGR can be calculated with high accuracy.

  According to the ninth aspect of the present invention, the means for calculating the EGR rate based on at least the charging efficiency, the internal EGR amount, and the external EGR amount, and at least the rotational speed, the charging efficiency, the EGR rate, and the intake valve closing timing are input variables. Therefore, the ignition timing can be calculated with high accuracy even under high altitude conditions where the atmospheric pressure decreases. In addition, since it is not necessary to use a multidimensional map, the memory capacity of the ECU can be reduced.

  According to the tenth aspect of the present invention, the charging efficiency reference value in the reference atmospheric pressure condition is determined by a polynomial having at least the rotational speed, the intake pipe relative pressure, the intake valve operating angle, the intake valve opening timing, and the exhaust valve closing timing as input variables. Therefore, the filling efficiency reference value can be calculated with high accuracy. In addition, since it is not necessary to use a multidimensional map, the memory capacity of the ECU can be reduced.

  According to the eleventh aspect of the present invention, the internal EGR amount reference in the reference atmospheric pressure condition is determined by a polynomial having at least the rotational speed, the intake pipe relative pressure, the intake valve operating angle, the intake valve open timing, and the exhaust valve close timing as input variables. Since the value is calculated, the internal EGR amount reference value can be calculated with high accuracy. In addition, since it is not necessary to use a multidimensional map, the memory capacity of the ECU can be reduced.

  According to the twelfth aspect of the present invention, the air flow sensor is provided in the intake passage upstream of the throttle valve, the pressure sensor is provided in the intake passage downstream of the throttle valve, and the air flow is based on at least the charging efficiency calculation means and the pressure sensor detection value. The sensor flow rate is estimated, and the difference between the air flow sensor detected flow rate and the air flow sensor unit estimated flow rate is corrected as the error of the charging efficiency calculation means, so the charging efficiency calculation result is corrected. The filling efficiency calculation accuracy can be made robust against the error factors. Further, the charging efficiency calculation accuracy does not deteriorate even when the variable valve or the throttle valve changes suddenly.

  According to the thirteenth aspect of the present invention, the air flow sensor is provided in the intake passage upstream of the throttle valve, and the absolute intake pressure downstream of the throttle valve is estimated based on at least the charging efficiency calculation means and the air flow sensor detected flow rate. Further, since the estimated intake absolute pressure is used for the charging efficiency calculation means, the charging efficiency calculation accuracy can be made robust against error factors such as individual variations, environmental changes, and deterioration over time of the internal combustion engine. Further, the charging efficiency calculation accuracy does not deteriorate even when the variable valve or the throttle valve changes suddenly.

  According to the fourteenth aspect of the present invention, means for calculating the target EGR rate based on at least the rotational speed and the load, means for calculating the current EGR rate based on the charging efficiency, the internal EGR amount, and the external EGR amount, and the target Since the variable valve control amount or the external EGR valve opening is calculated based on the EGR rate, the current EGR rate, and the intake relative pressure, the variable valve control amount or the external EGR valve opening can be calculated even in high altitude conditions where the atmospheric pressure decreases. The fuel efficiency and exhaust performance can be controlled to the optimum points within a range that does not deteriorate the combustion stability.

  According to the fifteenth aspect of the present invention, in the case of a high altitude condition where the atmospheric pressure decreases while the charging efficiency is kept constant, in the same overlap period, the ignition timing is set to the retard side as the atmospheric pressure decreases. Since the ignition timing is corrected to the retard side as the overlap period increases at the same atmospheric pressure, the ignition timing can be controlled to the optimum fuel efficiency even in high altitude conditions where the atmospheric pressure decreases.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram for explaining the configuration of an embodiment of the present invention. The system of this embodiment includes an internal combustion engine 1. The internal combustion engine 1 communicates with an intake passage and an exhaust passage. An air flow sensor and an intake air temperature sensor 2 are assembled in the intake passage. A throttle valve 3 is provided downstream of the air flow sensor 2. The throttle valve 3 is an electronically controlled throttle valve that can control the throttle opening independently of the accelerator pedal stroke. An intake manifold 4 communicates with the throttle valve 3 downstream. An intake pipe pressure sensor 5 is assembled to the intake manifold 4. A fuel injection valve 7 for injecting fuel into the intake port is disposed downstream of the intake manifold 4. The internal combustion engine 1 includes an intake valve 8 with a variable valve mechanism that continuously varies valve timing and lift. The variable valve mechanism is assembled with a sensor 9 for detecting the valve timing and the maximum lift. Further, the internal combustion engine 1 is provided with an exhaust valve 10. The exhaust valve 10 is provided with a variable valve mechanism that makes the exhaust valve timing variable. The sensor 11 detects the timing of the exhaust valve. A spark plug 12 having an electrode portion exposed in the cylinder is assembled to the cylinder head portion. Further, a knock sensor 13 for detecting the occurrence of knock is assembled to the cylinder. A crank angle sensor 14 is assembled to the crankshaft. The rotational speed of the internal combustion engine 1 can be detected based on the output signal from the crank angle sensor 14. An O ₂ sensor 15 is assembled in the exhaust passage. The system of this embodiment is provided with an external EGR pipe 16 for returning a part of exhaust gas to the intake pipe and an external EGR valve 17 for controlling the external EGR flow rate. During partial load operation, the pump loss can be reduced by opening the external EGR valve 17 and performing EGR.

  The system of this embodiment includes an ECU (Electronic Control Unit) 17 as shown in FIG. The ECU 18 is connected with the various sensors described above. Actuators such as a throttle valve 3, a fuel injection valve 7, an intake valve 8 with a variable valve mechanism, and an exhaust valve 10 with a variable valve mechanism are controlled by an ECU 18. Furthermore, the operating state of the internal combustion engine 1 is detected based on signals input from the various sensors described above, and the spark plug 12 ignites at a timing determined by the ECU 18 according to the operating state.

  FIG. 2 is a diagram for explaining the change in the overlap period between the intake valve and the exhaust valve when the phase of the intake valve is continuously changed. As the phase of the intake valve is changed to the advance side, the overlap period with the exhaust valve increases. In an internal combustion engine equipped with a variable valve, the variable valve is controlled so that the overlap period occurs under a partial load condition, and internal EGR is generated by once blowing the exhaust gas in the exhaust pipe back to the intake pipe. As the internal EGR increases, the pump loss under the partial load condition can be reduced, and the combustion gas temperature can be reduced, so that the nitrogen oxide in the exhaust gas can be reduced.

  FIG. 3 is a diagram for explaining a valve lift pattern of a variable valve mechanism capable of simultaneously changing the valve operating angle, lift and phase. In an internal combustion engine in which a conventional throttle valve mainly controls the charging efficiency, a negative pressure is generated by restricting the upstream pressure of the intake valve by the throttle valve, so that deterioration of fuel consumption due to pump loss becomes a problem. If the intake air amount can be controlled by the opening / closing timing of the intake valve without reducing the upstream pressure of the intake valve, the fuel consumption deterioration due to the pump loss can be avoided. In the variable valve shown in FIG. 3, the valve opening timing (IVO) is obtained by using a combination of a lift variable mechanism that continuously varies the valve lift and a phase variable mechanism that continuously varies the phase for the intake valve. ) Is fixed, and the valve closing timing (IVC) is changed. By providing such a variable valve mechanism, it is possible to realize an internal combustion engine that mainly controls the variable valve to control the charging efficiency. The variable lift mechanism has a relationship as shown in the lower part of FIG. 3 in which the maximum lift increases as the valve operating angle increases. When the required torque is small, the lift amount is reduced and the IVC is advanced at the same time. The amount can be reduced. At this time, since the piston compression amount can be made relatively small compared with the piston expansion amount by accelerating IVC, the fuel efficiency improvement effect by the Miller cycle effect can be expected in addition to the reduction of the pump loss. Is a feature.

  FIG. 4 is a diagram for explaining the relationship between the overlap period and the internal EGR amount under the low altitude condition and the high altitude condition obtained in a state where the rotation speed and the intake pressure are kept constant. Here, the EGR amount is a value obtained by dividing the mass of burned gas remaining in the cylinder by the mass of air in a standard state corresponding to the stroke volume. As shown in FIG. 4, the internal EGR can be divided into a part caused by blowback determined according to the overlap period and a part determined according to the clearance volume part of the exhaust valve closing timing (EVC). Further, the internal EGR amount is affected by the relationship between the exhaust pressure and the intake pressure. In the case where the exhaust pressure is reduced under the condition where there is an overlap as in the high altitude condition, the amount of internal EGR is greatly reduced due to the reduction in the amount of blowback. On the other hand, under the condition where there is no overlap, even if the exhaust pressure is reduced, the amount of decrease in the internal EGR amount is limited to the portion caused by the clearance volume, so the amount of decrease is relatively small. Therefore, in order to accurately estimate the internal EGR amount under high altitude conditions of an internal combustion engine equipped with a variable valve, at least information on IVO, EVC, intake pressure and exhaust pressure (or atmospheric pressure) is required.

  FIG. 5 is a diagram for explaining the relationship between the overlap period and the charging efficiency in the low altitude condition and the high altitude condition and the relationship between the overlap period and the fuel injection amount, which are obtained in a state where the rotation speed and the intake pressure are kept constant. It is. Here, the charging efficiency is a value obtained by dividing the mass of fresh air sucked into the cylinder by the air mass in a standard state corresponding to the stroke volume. When the intake pressure is kept constant, the filling efficiency increases under high altitude conditions where the atmospheric pressure decreases under conditions where there is an overlap. This is because, as described with reference to FIG. 4, the amount of internal EGR that is blown back into the intake pipe and is again taken into the cylinder decreases. As the overlap period increases, the increase in filling efficiency increases. On the other hand, in the absence of overlap, the decrease in the internal EGR amount is limited to the portion caused by the clearance volume, so the decrease is relatively The increase in filling efficiency is small as well. In order to keep the target air-fuel ratio constant with respect to the change in the charging efficiency described above, it is necessary to perform high altitude correction that changes the fuel injection amount in accordance with the change in the charging efficiency. That is, in order to keep the air-fuel ratio constant under the condition where the intake pressure is constant and there is an overlap, the fuel injection amount increase correction is performed for the charging efficiency increased under the high altitude condition. In an internal combustion engine equipped with a variable valve, it is necessary to change the above-described high altitude correction in accordance with the overlap period and atmospheric pressure. In an internal combustion engine equipped with an air flow sensor upstream of the throttle valve, the increase in the charging efficiency can be detected by the air flow sensor under high altitude conditions. Therefore, under steady conditions, the flow rate detected by the air flow sensor The fuel injection amount can be controlled according to the target air-fuel ratio.

  FIG. 6 shows the relationship between the overlap period and the internal EGR rate in the lowland condition and the highland condition, the relationship between the overlap period and the combustion speed, and the overlap obtained in a state where the rotation speed and the charging efficiency are kept constant. It is a figure explaining the relationship between a period and ignition timing (MBT: Minimum spark advance for Best Torque). The internal EGR rate here can be obtained by the following equation using the internal EGR amount and the charging efficiency.

Internal EGR rate = internal EGR amount / (internal EGR amount + charging efficiency + charging efficiency / air-fuel ratio)
... Formula (1)

  As described with reference to FIGS. 4 and 5, when the atmospheric pressure is reduced under the high altitude condition with the overlap, the internal EGR amount is reduced and the charging efficiency is increased as compared with the low altitude condition. When compared with the same filling efficiency, the internal EGR rate defined by the above equation decreases at high altitude conditions. The EGR rate affects the combustion rate, and the combustion rate decreases as the EGR rate increases. As the combustion speed decreases, the time required from the ignition timing, which is the combustion start timing, to the end of combustion increases, so that the MBT for setting the combustion period to the timing at which the maximum torque is generated advances. Under the high altitude condition and the condition with overlap, as described above, the internal EGR rate decreases, so the combustion speed increases, and the MBT changes from the MBT set under the low altitude condition to the retard side. On the other hand, under the condition where there is no overlap, the amount of decrease in the internal EGR rate is relatively small, and therefore the retardation amount of MBT is also relatively small. As described above, in an internal combustion engine equipped with a variable valve, it can be said that it is necessary to appropriately correct the high altitude of the ignition timing according to the high altitude conditions and the degree of the overlap period.

  FIG. 7 is a diagram for explaining the relationship between the ignition timing and the torque under the low altitude condition and the high altitude condition obtained when the rotational speed and the charging efficiency are kept constant in the case where the overlap period is large and small. There is a convex relationship between the ignition timing and the torque, and the ignition timing is normally set at the maximum torque point (the best fuel efficiency point when the torque is constant), that is, MBT. In order to reduce the pump loss by increasing the overlap period during partial load operation and performing a large amount of internal EGR, the MBT is set to the advance side compared to the condition without overlap. When the atmospheric pressure drop occurs under high altitude conditions with the charging efficiency kept constant, the internal EGR decreases, the combustion speed increases, and the MBT changes to the retard side. If the ignition timing is determined on the basis of the charging efficiency, separation from the original MBT occurs, resulting in a reduction in torque (deterioration of fuel consumption). This tendency increases as the overlap period increases and the atmospheric pressure decreases. By appropriately correcting the ignition timing high altitude according to the overlap period and atmospheric pressure level, the operating state is always set to the optimum point without causing torque reduction even under high altitude conditions of an internal combustion engine equipped with a variable valve. Can be held.

  FIG. 8 shows a charging efficiency based on the rotational speed, valve operating angle, IVO, EVC, intake absolute pressure, atmospheric absolute pressure, intake air temperature, and external EGR rate in an internal combustion engine that mainly controls the charging efficiency with a variable valve. It is a figure explaining the means to calculate. In the block diagram shown in FIG. 8, the ratio between the absolute intake pressure and the absolute atmospheric pressure is first obtained. The absolute intake pressure can be measured by a pressure sensor provided in the intake manifold. The absolute atmospheric pressure can also be measured by providing a pressure sensor upstream of the throttle valve. Also, when the internal combustion engine is started or when the throttle valve opening is fully open, it is assumed that the intake manifold pressure and the atmospheric pressure match, and the absolute atmospheric pressure is measured by the pressure sensor provided in the intake manifold. It is good to do. The ratio between the absolute intake pressure and the atmospheric absolute pressure is input to the block 81. In block 81, the charging efficiency under the reference condition is calculated with the rotational speed, the ratio of the absolute intake pressure to the atmospheric absolute pressure, the valve operating angle, IVO and EVC as inputs. Here, the reference condition indicates the charging efficiency obtained when the atmospheric absolute pressure, the intake air temperature, and the external EGR rate are set as the reference conditions. High altitude correction is performed by multiplying the reference filling efficiency by the ratio of the atmospheric absolute pressure and the atmospheric absolute reference pressure. Further, in block 82, the change from the reference condition of the intake air temperature and the external EGR rate is corrected using the following equation.

Charging efficiency correction amount = (reference intake air temperature / intake air temperature) ^0.5
X (1-external EGR rate-reference external EGR rate) (2)

  The unit of the intake air temperature is K (Kelvin). The filling efficiency corrected with the high altitude can be obtained by the product with the filling efficiency correction amount obtained above.

  FIG. 9 illustrates a means for calculating the internal EGR amount based on the rotational speed, valve operating angle, IVO, EVC, intake absolute pressure and atmospheric absolute pressure in an internal combustion engine that mainly controls a variable valve to control charging efficiency. It is a figure to do. In the block diagram shown in FIG. 9, the ratio between the absolute intake pressure and the absolute atmospheric pressure is first obtained. The ratio of the absolute intake pressure to the absolute atmospheric pressure is input to block 91. At block 91, the internal EGR amount under the reference condition is calculated with the rotational speed, the ratio of the absolute intake pressure to the atmospheric absolute pressure, the valve operating angle, IVO and EVC as inputs. Here, the reference condition indicates an internal EGR amount obtained when the atmospheric absolute pressure is set to the reference condition. By multiplying the reference internal EGR amount by the ratio of the atmospheric absolute pressure and the atmospheric absolute reference pressure, the internal EGR amount corrected for the high altitude can be obtained.

  FIG. 10 shows an internal combustion engine that mainly controls a variable valve to control the charging efficiency, and includes means for calculating exhaust absolute pressure, the exhaust absolute pressure and rotational speed, valve operating angle, IVO, EVC, intake absolute pressure, It is a figure explaining the means to calculate filling efficiency based on atmospheric | atmosphere absolute pressure, intake air temperature, and an external EGR rate. In the block diagram shown in FIG. 10, the ratio between the absolute intake pressure and the absolute exhaust pressure is first obtained. A ratio between the absolute intake pressure and the absolute exhaust pressure is input to the block 101. In block 101, the charging efficiency under the reference conditions is calculated with the rotational speed, the ratio of the absolute intake pressure to the absolute exhaust pressure, the valve operating angle, IVO and EVC as inputs. Here, the reference condition indicates the charging efficiency obtained when the atmospheric absolute pressure, the intake air temperature, and the external EGR rate are set as the reference conditions. High altitude correction is performed by multiplying the reference filling efficiency by the ratio of the atmospheric absolute pressure and the atmospheric absolute reference pressure. In block 102, the exhaust absolute pressure is calculated by inputting the rotational speed, the atmospheric absolute pressure, the air-fuel ratio, the ignition timing, the EGR rate, and the charging efficiency obtained in the previous step. Further, in block 103, the amount of change from the reference condition of the intake air temperature and the external EGR rate is corrected. The filling efficiency corrected for the high altitude can be obtained by the product of the filling efficiency correction amount obtained in the block 103. In this way, the filling efficiency calculating means shown in FIG. 8 can be substituted, and the highland corrected filling efficiency can also be obtained from the block diagram shown in FIG. Further, the present invention is not limited to the method using FIG. 8 or FIG. 10, and instead of the exhaust absolute pressure calculation means shown in block 101, a pressure sensor is provided in the exhaust pipe to directly control the exhaust absolute pressure. The same effect can be obtained even if a measuring method is used.

  FIG. 11 shows an internal combustion engine that mainly controls a variable valve to control the charging efficiency, and includes means for calculating the exhaust absolute pressure, the exhaust absolute pressure and the rotational speed, the valve operating angle, IVO, EVC, the intake absolute pressure, and It is a figure explaining the means to calculate the amount of internal EGR based on atmospheric absolute pressure. In the block diagram shown in FIG. 11, the ratio between the absolute intake pressure and the absolute exhaust pressure is first obtained. The ratio between the absolute intake pressure and the absolute exhaust pressure is input to the block 111. In block 111, the internal EGR amount under the reference condition is calculated by inputting the rotational speed, the ratio of the absolute intake pressure to the absolute exhaust pressure, the valve operating angle, IVO and EVC. Here, the reference condition indicates an internal EGR amount obtained when the atmospheric absolute pressure is set to the reference condition. In block 112, the exhaust absolute pressure is calculated by inputting the rotational speed, the atmospheric absolute pressure, the air-fuel ratio, the ignition timing, the EGR rate, and the charging efficiency obtained in the previous step. By multiplying the reference internal EGR amount by the ratio of the atmospheric absolute pressure and the atmospheric absolute reference pressure, the internal EGR amount corrected for the high altitude can be obtained. In this way, the internal EGR amount calculating means shown in FIG. 9 can be substituted and the high ground corrected internal EGR amount can be obtained also by the block diagram shown in FIG. Further, the present invention is not limited to the system using FIG. 9 or FIG. 11, but instead of the exhaust absolute pressure calculating means shown in the block 112, a pressure sensor is provided in the exhaust pipe to directly control the exhaust absolute pressure. The same effect can be obtained even if a measuring method is used.

  FIG. 12 is a diagram for explaining means for calculating the exhaust pressure change rate based on the cylinder exhaust flow rate, the cylinder exhaust temperature, the outlet exhaust flow rate, and the external EGR amount, and calculating the exhaust absolute pressure based on the exhaust pressure change rate. In the block diagram shown in FIG. 12, first, the exhaust flow rate dGcyl / dt discharged from the cylinder is calculated in block 121 with the rotational speed, air-fuel ratio, and charging efficiency as inputs. Further, the ignition temperature, the air-fuel ratio, and the EGR rate are input, and the exhaust gas temperature Tex discharged from the cylinder is calculated in block 122. For the calculation of the exhaust temperature, a map or a polynomial with the ignition timing, the air-fuel ratio and the EGR rate as axes can be used. Further, the exhaust gas flow rate dGout / dt of exhaust gas discharged from the exhaust pipe to the atmosphere is calculated at block 123 with the exhaust temperature Tex discharged from the cylinder, the atmospheric absolute pressure Patm, and the exhaust pipe flow coefficient μv as inputs. The following equation is used to calculate the exhaust flow rate discharged into the atmosphere.

dGout / dt = μout × Aout × (2 / RexTex) ^0.5
× Ψ (Pex, Patm)
Ψ (Pex, Patm) = (2 / (k + 1)) ^{(1 / (k−1))} × (k / (k + 1)) ^0.5
... Patm / Pex <(2 / (k + 1)) ^{(k / (k-1))}
Ψ (Pex, Patm) = {(k / (k−1)) × ((Patm / Pex) ^{2 / k}
− (Patm / Pex) ^{(k + 1) / k)} } ^0.5
... Patm / Pex ≧ (2 / (k + 1)) ^{(k / (k-1))}
... Formula (3)

  Here, μout is a flow coefficient of the exhaust outlet, Aout is an area of the exhaust pipe outlet, and k is a specific heat ratio. Further, the external EGR flow rate dGegr / dt is calculated in block 124 with the exhaust temperature discharged from the cylinder, the intake absolute pressure, the EGR valve opening, and the exhaust absolute pressure as inputs. The following equation is used to calculate the external EGR flow rate.

dGegr / dt = μegr × Aegr × (2 / RexTex) ^0.5
× Ψ (Pex, Pin)
Ψ (Pex, Pin) = (2 / (k + 1)) ^{(1 / (k−1))} × (k / (k + 1)) ^0.5
... Pin / Pex <(2 / (k + 1)) ^{(k / (k-1))}
Ψ (Pex, Pin) = {(k / (k−1)) × ((Pin / Pex) ^{2 / k}
-(Pin / Pex) ^{(k + 1) / k)} ) ^0.5
... Pin / Pex≥ (2 / (k + 1)) ^{(k / (k-1))}
... Formula (4)

  Here, μegr is the flow coefficient of the external EGR valve, Aegr is the opening area of the external EGR valve, and k is the specific heat ratio. In block 125, exhaust pressure change rate dPex / dt is calculated using the following equation using cylinder exhaust flow rate dGcyl / dt, cylinder exhaust temperature Tex and exhaust outlet flow rate dGout / dt obtained in blocks 121 to 124.

    dPex / dt = (RexTex / Vex) × (dGcyl / dt−dGout / dt−dGegr / dt) (5)

  Here, Rex is the gas constant of the exhaust gas, and Vex is the volume of the exhaust pipe. The exhaust absolute pressure can be calculated by integrating the exhaust pressure change rate dPex / dt obtained in block 125 with time. According to this method, the exhaust pressure can be calculated with high accuracy even under high altitude conditions where the atmospheric pressure of the internal combustion engine that performs external EGR decreases.

  FIG. 13 shows the calculation of the charging efficiency in the reference state based on a polynomial with the rotational speed, the intake relative pressure, the valve operating angle, the IVO and the EVC as parameters in an internal combustion engine that mainly controls the charging efficiency with a variable valve. It is a figure explaining the means to do. In this embodiment, the reference charging efficiency is calculated using a polynomial regression model that takes into account the effects of the rotational speed, intake relative pressure, intake valve operating angle, IVO, and EVC on the charging efficiency. The intake relative pressure is a ratio between the intake absolute pressure and the atmospheric absolute pressure, or a ratio between the intake absolute pressure and the exhaust absolute pressure. Taking the above influencing factors as explanatory variables, consider up to the fourth order term. Furthermore, in order to express the influence of the interaction between the influence factors on the model, an interaction term that maximizes the fourth order is provided. By including higher order terms and interaction terms in the regression model in this way, it is possible to accurately calculate the charging efficiency characteristics of the nonlinear engine. In the present invention, a polynomial is used for the calculation of the filling efficiency in the reference state, but the present invention is not limited to this. That is, a calculation method based on a map or table using the rotational speed, the intake relative pressure, the valve operating angle, IVO, and EVC as parameters may be employed.

  FIG. 14 shows the internal EGR amount in the reference state based on a polynomial with rotational speed, intake air relative pressure, valve operating angle, IVO and EVC as parameters in an internal combustion engine that mainly controls a variable valve to control charging efficiency. It is a figure explaining the means to calculate. In this embodiment, the reference internal EGR amount is calculated using a polynomial regression model that takes into account the effects of the rotational speed, intake relative pressure, intake valve operating angle, IVO, and EVC on the internal EGR amount. The intake relative pressure is a ratio between the intake absolute pressure and the atmospheric absolute pressure, or a ratio between the intake absolute pressure and the exhaust absolute pressure. Taking the above influencing factors as explanatory variables, consider up to the fourth order term. Furthermore, in order to express the influence of the interaction between the influence factors on the model, an interaction term that maximizes the fourth order is provided. By including higher order terms and interaction terms in the regression model in this way, the internal EGR amount characteristic of the nonlinear engine can be calculated with high accuracy. In the present invention, a polynomial is used to calculate the internal EGR amount in the reference state, but the present invention is not limited to this. That is, a calculation method based on a map or table using the rotational speed, the intake relative pressure, the valve operating angle, IVO, and EVC as parameters may be employed.

  FIG. 15 shows an internal combustion engine that mainly controls a variable valve to control charging efficiency, high altitude corrected charging efficiency, high altitude corrected internal EGR amount, high altitude corrected external EGR amount, rotational speed, IVC, intake air temperature, air-fuel ratio. FIG. 5 is a diagram for explaining a means for calculating a high altitude corrected ignition timing control amount using an octane number as an input. In the block diagram shown in FIG. 15, first, in block 151, the EGR rate is calculated based on the internal EGR amount, the external EGR amount, the air-fuel ratio, and the charging efficiency. The EGR rate can be obtained using the following equation.

EGR rate = (external EGR amount + internal EGR amount)
/ (Internal EGR amount + external EGR amount + charging efficiency + charging efficiency / air-fuel ratio)
... Formula (6)

  Next, in block 152, the reference ignition timing is calculated. The reference ignition timing indicates the optimum ignition timing obtained when the EGR rate, the intake air temperature, the air-fuel ratio, and the octane number are set to the reference state. In blocks 153 to 155, each correction amount of the ignition timing is calculated using the EGR rate, the intake air temperature, the air-fuel ratio, and the octane number as inputs. Further, the ignition timing is calculated by adding the calculated correction value to the reference value. The charging efficiency, internal EGR amount, and external EGR amount all correspond to high altitude conditions and variable valves. By adopting a configuration using inputs corresponding to these high altitude conditions and variable valves, it is possible to accurately calculate the ignition timing.

  FIG. 16 shows the calculation of the ignition timing based on a polynomial in which the rotational speed, the charging efficiency, the IVC, the EGR rate, the intake air temperature, the air-fuel ratio, and the octane number are parameters in an internal combustion engine that mainly controls the charging efficiency with a variable valve. It is a figure explaining the means to do. The reference value polynomial is input using rotational speed, charging efficiency, and IVC (intake valve closing angle), and high-order terms and interaction terms are set for these variables. IVC is taken into consideration for the reference value polynomial in the system of the present embodiment in which the intake valve is provided with a variable valve mechanism in which the operating angle and phase are continuously variable, and the actual compression ratio due to piston motion changes greatly due to IVC. This is because the knock behavior, which is an important factor for ignition timing control, is greatly affected by the IVC. The rotational speed, filling efficiency, IVC, and EGR rate are used to input the EGR rate correction value polynomial, and high-order terms and interaction terms are set for these variables. Similarly, an intake air temperature correction value polynomial, an air-fuel ratio correction value polynomial, and an octane number correction value polynomial are set. By adopting a configuration in which each correction value is added to the reference value described above, the ignition timing can be calculated with high accuracy. In the present invention, a polynomial is used for calculating the ignition timing, but the present invention is not limited to this. That is, a calculation method based on a map or table using parameters such as rotational speed, charging efficiency, IVC, internal EGR amount, intake air temperature, air-fuel ratio, external EGR rate, and octane number may be employed.

  The second embodiment of the present invention will be described below with reference to the drawings. The system of the present embodiment is the same as that of the first embodiment except that the intake valve is provided with a variable valve mechanism of which only the phase is variable, and the charging efficiency is mainly used for controlling the throttle valve.

  FIG. 17 shows a means for calculating the charging efficiency based on the rotational speed, IVO, EVC, intake absolute pressure, atmospheric absolute pressure, intake air temperature, and external EGR rate in an internal combustion engine that mainly controls the charging efficiency by a throttle valve. FIG. In the block diagram shown in FIG. 17, first, the ratio between the absolute intake pressure and the absolute atmospheric pressure is obtained. The ratio between the absolute intake pressure and the absolute atmospheric pressure is input to block 171. In block 171, the rotational efficiency, the ratio of absolute intake pressure to atmospheric absolute pressure, IVO and EVC are input, and the charging efficiency under the reference conditions is calculated. Here, the reference condition indicates the charging efficiency obtained when the atmospheric absolute pressure, the intake air temperature, and the external EGR rate are set as the reference conditions. High altitude correction is performed by multiplying the reference filling efficiency by the ratio of the atmospheric absolute pressure and the atmospheric absolute reference pressure. Further, in block 172, the deviation from the reference condition of the intake air temperature and the external EGR rate is corrected. By adopting the above-described configuration, it is possible to obtain the filling efficiency corrected for the high altitude. In addition, this invention is not limited to this, As shown in FIG. 10, it can also be set as the structure provided with the means which calculates exhaust absolute pressure. It is also possible to provide a configuration in which a pressure sensor is provided in the exhaust pipe and the directly measured exhaust pressure is used.

  FIG. 18 is a diagram for explaining means for calculating the internal EGR amount based on the rotational speed, IVO, EVC, intake absolute pressure, and atmospheric absolute pressure in an internal combustion engine that mainly controls the throttle valve and controls the charging efficiency. . In the block diagram shown in FIG. 18, first, the ratio between the absolute intake pressure and the absolute atmospheric pressure is obtained. The ratio between the absolute intake pressure and the absolute atmospheric pressure is input to block 181. In block 181, the rotational speed, the ratio of absolute intake pressure to atmospheric absolute pressure, IVO and EVC are input, and the internal EGR amount under the reference condition is calculated. Here, the reference condition indicates an internal EGR amount obtained when the atmospheric absolute pressure is set to the reference condition. By multiplying the reference internal EGR amount by the ratio of the atmospheric absolute pressure and the atmospheric absolute reference pressure, the internal EGR amount corrected for the high altitude can be obtained. In addition, this invention is not limited to this, As shown in FIG. 11, it can also be set as the structure provided with the means which calculates exhaust absolute pressure. It is also possible to provide a configuration in which a pressure sensor is provided in the exhaust pipe and the directly measured exhaust pressure is used.

  FIG. 19 illustrates a means for calculating the charging efficiency in the reference state based on a polynomial with rotational speed, intake air relative pressure, IVO, and EVC as parameters in an internal combustion engine that mainly controls a throttle valve to control the charging efficiency. It is a figure to do. In the present embodiment, the reference charging efficiency is calculated using a polynomial regression model that takes into account the effects of rotational speed, intake relative pressure, IVO, and EVC on the charging efficiency. The intake relative pressure is a ratio between the intake absolute pressure and the atmospheric absolute pressure, or a ratio between the intake absolute pressure and the exhaust absolute pressure. Taking the above influencing factors as explanatory variables, consider up to the fourth order term. Furthermore, in order to express the influence of the interaction between the influence factors on the model, an interaction term that maximizes the fourth order is provided. By including higher order terms and interaction terms in the regression model in this way, it is possible to accurately calculate the charging efficiency characteristics of the nonlinear engine. In the present invention, a polynomial is used for the calculation of the filling efficiency in the reference state, but the present invention is not limited to this. That is, a calculation method based on a map or a table using the rotational speed, the intake relative pressure, IVO, and EVC as parameters may be used.

  FIG. 20 shows a means for calculating the internal EGR amount in the reference state based on a polynomial equation with rotational speed, intake air relative pressure, IVO and EVC as parameters in an internal combustion engine that mainly controls a throttle valve to control charging efficiency. It is a figure explaining. In the present embodiment, the reference internal EGR amount is calculated using a polynomial regression model that takes into account the effects of the rotational speed, intake relative pressure, IVO, and EVC on the internal EGR amount. The intake relative pressure is a ratio between the intake absolute pressure and the atmospheric absolute pressure, or a ratio between the intake absolute pressure and the exhaust absolute pressure. Taking the above influencing factors as explanatory variables, consider up to the fourth order term. Furthermore, in order to express the influence of the interaction between the influence factors on the model, an interaction term that maximizes the fourth order is provided. By including higher order terms and interaction terms in the regression model in this way, the internal EGR amount characteristic of the nonlinear engine can be calculated with high accuracy. In the present invention, a polynomial is used to calculate the internal EGR amount in the reference state, but the present invention is not limited to this. That is, a calculation method based on a map or a table using the rotational speed, the intake relative pressure, IVO, and EVC as parameters may be used.

  FIG. 21 shows an internal combustion engine that mainly controls a throttle valve to control charging efficiency, high-ground corrected charging efficiency, high-ground corrected internal EGR amount, high-ground corrected external EGR amount, rotational speed, intake air temperature, air-fuel ratio, and octane number. FIG. 6 is a diagram for explaining a means for calculating a high altitude corrected ignition timing control amount with the input of. In the block diagram shown in FIG. 21, first, in block 211, the EGR rate is calculated based on the internal EGR amount, the external EGR amount, the air-fuel ratio, and the charging efficiency. Next, in block 212, the reference ignition timing is calculated. The reference ignition timing indicates the optimum ignition timing obtained when the EGR rate, the intake air temperature, the air-fuel ratio, and the octane number are set to the reference state. In blocks 213 to 215, each correction amount of the ignition timing is calculated by inputting the EGR rate, the intake air temperature, the air-fuel ratio, and the octane number. Further, the ignition timing is calculated by adding the calculated correction value to the reference value. The charging efficiency, internal EGR amount, and external EGR amount all correspond to high altitude conditions and variable valves. By adopting a configuration using inputs corresponding to these high altitude conditions and variable valves, it is possible to accurately calculate the ignition timing.

  FIG. 22 shows a means for calculating an ignition timing based on a polynomial expression using rotational speed, charging efficiency, EGR rate, intake air temperature, air-fuel ratio, and octane number as parameters in an internal combustion engine that mainly controls a throttle valve to control the charging efficiency. FIG. The rotational speed and the filling efficiency are used for the input of the reference value polynomial, and the high-order terms and the interaction terms are set for these variables. The rotational speed, filling efficiency, and EGR rate are used to input the EGR rate correction value polynomial, and high-order terms and interaction terms are set for these variables. Similarly, an intake air temperature correction value polynomial, an air-fuel ratio correction value polynomial, and an octane number correction value polynomial are set. By adopting a configuration in which each correction value is added to the reference value described above, the ignition timing can be calculated with high accuracy. In the present invention, a polynomial is used for calculating the ignition timing, but the present invention is not limited to this. That is, a calculation method based on a map or table using parameters such as rotational speed, charging efficiency, internal EGR amount, intake air temperature, air-fuel ratio, external EGR rate, and octane number may be employed.

  FIG. 23 is a diagram illustrating an intake pipe configuration of an internal combustion engine that uses an airflow sensor and a pressure sensor as the charging efficiency detection means. During steady operation, the flow rate of the air flow sensor unit provided in the upstream portion of the throttle matches the flow rate of the cylinder unit, so that the charging efficiency can be calculated based on the flow rate detected by the air flow sensor. However, in the case of a transient when the throttle valve changes suddenly, the flow rate of the air flow sensor unit starts to change immediately according to the throttle valve opening area and the pressure in the manifold, whereas the flow rate of the cylinder unit It gradually changes based on changes in pressure. On the other hand, when the variable valve changes abruptly, the flow rate in the cylinder portion starts to change immediately in response to the change in the variable valve, whereas the flow rate in the upstream portion of the throttle valve is between the cylinder and the air flow sensor. The behavior of the change is delayed by the compression / expansion motion of the compressible fluid in the manifold interposed between the two. Therefore, since there is a difference between the flow rate of the air flow sensor unit and the flow rate of the cylinder unit during the transition, the fuel injection amount and the ignition timing cannot be appropriately calculated based on the detected value of the air flow sensor. Although the detection by the air flow sensor has a problem such as deterioration of transient prediction accuracy, the steady accuracy has an advantage that it is robust against environmental change, deterioration with time, and individual variation. On the other hand, although the charging efficiency estimation model based on the intake pipe pressure and variable valve has the advantage of being able to follow a rapid change in transients, it is actually difficult to describe all the variation factors in the model. Therefore, it can be said that it is difficult to ensure the steady accuracy within a predetermined range. Utilizing these advantages, a means capable of calculating the charging efficiency with high accuracy in any of the steady state and transient conditions is required.

  FIG. 24 shows an air flow sensor detection value and a model in an internal combustion engine having a variable valve as a main component and controlling the charging efficiency mainly as a throttle valve or a throttle valve as a main component and having an air flow sensor and a pressure sensor. It is a figure explaining the means which calculates filling efficiency based on an estimated value, and the means which calculates fuel injection quantity based on the said filling efficiency. In the block diagram shown in FIG. 24, in block 242, the charging efficiency is calculated based on the rotational speed, the intake absolute pressure, the atmospheric absolute pressure, the variable valve, the intake air temperature, and the external EGR rate. Any of the filling efficiency calculation means shown in FIG. 8, FIG. 10, or FIG. 17 can be used for the block 242. Based on the relationship between the charging efficiency and the rotational speed calculated in block 242, the flow rate of the cylinder portion is calculated in block 244. Based on the cylinder flow rate dGcyl / dt, the intake pipe pressure change rate dPin / dt, the intake air temperature Tin and the external EGR flow rate dGegr / dt calculated in block 244, block 245 calculates the flow rate dGafs / Estimate dt.

dGafs / dt = (Vin / RinTin) × (dPin / dt) + dGcyl / dt−dGegr / dt (7)
Here, Rin is the gas constant of the intake gas, and Vin is the volume of the intake pipe. The difference between the air flow sensor flow rate estimated in block 245 and the actually detected air flow sensor detected flow rate is obtained, and this is converted into charging efficiency in block 243. The converted difference is considered to correspond to the steady state error of the model in block 242. By correcting the filling efficiency calculated in the block 242 using this steady error, the filling efficiency can always be calculated with high accuracy even in a steady state or a transient state. The calculated charging efficiency is used as an input to the ignition timing calculating means shown in FIG. Further, the fuel injection amount is calculated in block 241 based on the charging efficiency, the target air fuel ratio, the exhaust air fuel ratio, and the transient / steady state determination.

  FIG. 25 shows a means for calculating the charging efficiency based on the detected value of the air flow sensor and the model estimated value in the internal combustion engine having only the air flow sensor and controlling the charging efficiency mainly by the throttle valve. It is a figure explaining the means to calculate the fuel injection quantity based on. In the block diagram shown in FIG. 25, in block 252, the charging efficiency is calculated based on the rotational speed, the intake absolute pressure, the atmospheric absolute pressure, the variable valve, the intake air temperature, and the external EGR rate. Any of the filling efficiency calculation means shown in FIG. 8, FIG. 10, or FIG. 17 can be used for the block 252. Based on the relationship between the charging efficiency and the rotational speed calculated in block 252, the flow rate of the cylinder portion is calculated in block 253. Based on the cylinder flow rate dGcyl / dt, the intake air temperature Tin, the external EGR flow rate dGegr / dt and the air flow sensor detected flow rate dGcyl / dt calculated in block 253, in block 254, the intake pipe pressure change rate dPin / dt is calculated by the following equation. Is estimated.

dPin / dt = (RinTin / Vin) × (dGafs / dt + dGegr / dt−dGcyl / dt) (8)
Here, Rin is the gas constant of the intake gas, and Vin is the volume of the intake pipe. The intake pipe absolute pressure can be calculated by integrating the intake pipe pressure change rate determined in block 254 with time. The calculated charging efficiency is used as an input to the ignition timing calculating means shown in FIG. Further, the fuel injection amount is calculated in block 251 based on the charging efficiency, the target air-fuel ratio, the exhaust air-fuel ratio, and the transient / steady state determination.

  FIG. 26 shows a means for calculating the charging efficiency based on the model estimated value and the fuel injection amount based on the charging efficiency in an internal combustion engine having only a pressure sensor for controlling the charging efficiency mainly by the throttle valve. It is a figure explaining the means to calculate. In the block diagram shown in FIG. 26, in block 262, the charging efficiency is calculated based on the rotational speed, the intake absolute pressure, the atmospheric absolute pressure, the variable valve, the intake air temperature, and the external EGR rate. The calculated charging efficiency is used as an input to the ignition timing calculating means shown in FIG. Further, the fuel injection amount is calculated in block 261 based on the charging efficiency, the target air fuel ratio, the exhaust air fuel ratio, and the transient / steady state determination.

  FIG. 27 shows the relationship between the overlap period and the internal EGR rate under the lowland condition and the highland condition, the overlap period, the fuel consumption amount, and the nitrogen oxide concentration obtained in a state where the rotation speed and the charging efficiency are kept constant. It is a figure explaining the relationship between these, and the relationship between an overlap period and combustion stability. When internal EGR is performed, pump loss can be reduced and nitrogen oxide emissions can be reduced. On the other hand, combustion stability deteriorates due to the influence of dilution with burned gas. For this reason, in an internal combustion engine having a variable valve, the control amount of the variable valve is usually set in advance so that as many EGRs as possible can be performed within the range of the combustion stability limit under lowland conditions. In high altitude conditions where the atmospheric pressure decreases, the internal EGR rate increases relative to the increase in the overlap period, so that the internal EGR rate decreases when compared with the same overlap period. There is a problem that the effect of reducing the emission amount of nitrogen oxides cannot be obtained. In the case shown in FIG. 27, the above effect can be obtained even in high altitude conditions by controlling the overlap period to be increased. In order to obtain a sufficient effect even under high altitude conditions, it is necessary to provide means for appropriately controlling the variable valve in accordance with the atmospheric pressure state within a range in which combustion stability is ensured. This applies not only to the variable valve that performs internal EGR control, but also to the external EGR valve that performs external EGR control.

  FIG. 28 is a diagram for explaining a means for calculating the variable valve and the external EGR valve control amount as much as possible to achieve the target EGR rate under high altitude conditions. In the block diagram shown in FIG. 28, first, in block 281, the EGR rate is calculated by inputting the internal EGR amount, the external EGR amount, the air-fuel ratio, and the charging efficiency. Since the EGR rate calculating means uses the high altitude corrected internal EGR amount, external EGR amount and filling efficiency, the EGR rate can be calculated with high accuracy even under high altitude conditions where atmospheric pressure decreases. In block 282, the target EGR rate is calculated with the load and the rotational speed as inputs. As load variables, filling efficiency, volumetric efficiency, intake pipe absolute pressure, and the like can be used. Here, the target EGR rate is preliminarily adapted so as to obtain a sufficient pump loss reduction and nitrogen oxide emission reduction effect within a range in which combustion stability is ensured. In block 283, control amounts of the variable valve and the external EGR valve are calculated based on the ratio of the EGR rate, the target EGR rate, the rotation speed, the intake absolute pressure, and the exhaust absolute pressure. Here, the exhaust absolute pressure is used. However, the present invention is not limited to this, and the same effect can be obtained even if the atmospheric absolute pressure is used.

The figure explaining the structure of embodiment of this invention. The figure explaining the change of the overlap period of an intake valve and an exhaust valve when the phase of an intake valve is changed continuously. The figure explaining the valve lift pattern of the variable valve mechanism which can change the operating angle of a valve, a lift, and a phase simultaneously. The figure explaining the relationship between the overlap period in low-altitude conditions and high-altitude conditions, and the amount of internal EGR obtained in a state where the rotation speed and the intake pressure are kept constant. The figure explaining the relationship between the overlap period and filling efficiency in a low altitude condition and a high altitude condition, and the relationship between an overlap period and a fuel injection amount, obtained in a state where the rotation speed and the intake pressure are kept constant. The relationship between the overlap period and internal EGR rate under low and high altitude conditions, the relationship between overlap period and combustion speed, and the overlap period and ignition timing obtained with the rotational speed and charging efficiency held constant. The figure explaining the relationship with (MBT). The figure explaining the relationship between the ignition timing in low ground conditions and high ground conditions, and a torque obtained in the state which hold | maintained rotation speed and charging efficiency constant about the case where an overlap period is large and small. Means for calculating charging efficiency based on rotation speed, valve operating angle, IVO, EVC, intake absolute pressure, atmospheric absolute pressure, intake air temperature, and external EGR rate in an internal combustion engine that mainly controls a variable valve to control charging efficiency FIG. The figure explaining the means to calculate the amount of internal EGR based on rotation speed, valve operating angle, IVO, EVC, intake absolute pressure, and atmospheric absolute pressure in the internal combustion engine which mainly controls a variable valve and controls charging efficiency. In an internal combustion engine that mainly controls a variable valve to control charging efficiency, the engine has means for calculating exhaust absolute pressure, the exhaust absolute pressure and rotational speed, valve operating angle, IVO, EVC, intake absolute pressure, atmospheric absolute pressure, The figure explaining the means which calculates filling efficiency based on intake air temperature and an external EGR rate. In an internal combustion engine that mainly controls a variable valve and controls the charging efficiency, the internal combustion engine includes means for calculating exhaust absolute pressure. The exhaust absolute pressure and rotational speed, valve operating angle, IVO, EVC, intake absolute pressure, and atmospheric absolute pressure are included. The figure explaining the means to calculate the amount of internal EGR based on. The figure explaining the means which calculates exhaust pressure change rate based on cylinder exhaust flow, cylinder exhaust temperature, outlet exhaust flow, and external EGR amount, and calculates exhaust absolute pressure based on the exhaust pressure change rate. Explains the means for calculating the charging efficiency in the reference state based on a polynomial with rotational speed, intake air relative pressure, valve operating angle, IVO and EVC as parameters in an internal combustion engine that mainly controls the charging efficiency with a variable valve. To do. Means for calculating an internal EGR amount in a reference state based on a polynomial with rotational speed, intake air relative pressure, valve operating angle, IVO, and EVC as parameters in an internal combustion engine that mainly controls a variable valve to control charging efficiency Illustration to explain. In an internal combustion engine that controls the charging efficiency with a variable valve as the main component, input the high altitude corrected charging efficiency, the high altitude corrected internal EGR amount, the high altitude corrected external EGR amount, the rotational speed, the IVC, the intake air temperature, the air fuel ratio, and the octane number. The figure explaining the means to calculate the high altitude corrected ignition timing control amount. Explains the means for calculating the ignition timing based on a polynomial whose parameters are rotational speed, charging efficiency, IVC, EGR rate, intake air temperature, air-fuel ratio, and octane number in an internal combustion engine that mainly controls the charging efficiency with a variable valve. To do. FIG. 6 is a diagram for explaining a means for calculating the charging efficiency based on the rotational speed, IVO, EVC, absolute intake pressure, atmospheric absolute pressure, intake air temperature, and external EGR rate in an internal combustion engine that mainly controls the charging efficiency by a throttle valve. . The figure explaining the means which calculates the amount of internal EGR based on rotational speed, IVO, EVC, intake absolute pressure, and atmospheric | air pressure absolute pressure in the internal combustion engine which mainly controls a throttle efficiency by a throttle valve. The figure explaining the means which calculates the charging efficiency in a reference state based on the polynomial which uses rotation speed, intake air relative pressure, IVO, and EVC as a parameter in the internal combustion engine which controls charging efficiency mainly by a throttle valve. The figure explaining the means which calculates the internal EGR amount in a reference | standard state based on the polynomial which uses rotational speed, intake relative pressure, IVO, and EVC as a parameter in the internal combustion engine which mainly controls throttle efficiency by a throttle valve. In an internal combustion engine that controls the charging efficiency mainly by a throttle valve, the high altitude corrected charging efficiency, the high altitude corrected internal EGR amount, the high altitude corrected external EGR amount, the rotational speed, the intake air temperature, the air-fuel ratio, and the octane number are input. The figure explaining the means which calculates the high altitude corrected ignition timing control amount. FIG. 6 is a diagram for explaining a means for calculating an ignition timing based on a polynomial whose parameters are rotational speed, charging efficiency, EGR rate, intake air temperature, air-fuel ratio, and octane number in an internal combustion engine that mainly controls the charging efficiency by a throttle valve. . The figure explaining the intake pipe structure of the internal combustion engine which uses an airflow sensor and a pressure sensor as a filling efficiency detection means. In an internal combustion engine equipped with an air flow sensor and a pressure sensor that mainly controls a variable valve to control the charging efficiency or a throttle valve mainly controls the charging efficiency, and based on the detected value of the air flow sensor and the estimated model value. FIG. 6 is a diagram for explaining a charging efficiency and a means for calculating a fuel injection amount based on the charging efficiency. Means for calculating the charging efficiency based on the detected value of the air flow sensor and the model estimated value and the fuel injection amount based on the charging efficiency in an internal combustion engine having only the air flow sensor for controlling the charging efficiency mainly by the throttle valve The figure explaining the means to calculate. Means for calculating a charging efficiency based on a model estimated value and a means for calculating a fuel injection amount based on the charging efficiency in an internal combustion engine having only a pressure sensor for controlling the charging efficiency mainly by a throttle valve Illustration to explain. The relationship between the overlap period and the internal EGR rate under low and high altitude conditions, the relationship between the overlap period and fuel consumption and nitrogen oxide concentration, obtained with the rotational speed and filling efficiency kept constant, and The figure explaining the relationship between an overlap period and combustion stability. The figure explaining the means which calculates a variable valve and an external EGR valve control amount as much as possible to become a target EGR rate in highland conditions.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 Air flow sensor and intake temperature sensor 3 Throttle valve 4 Intake manifold 5 Intake pipe pressure sensor 6 Tumble control valve 7 Fuel injection valve 8 Intake variable valve mechanism 9 Valve lift sensor and valve timing sensor 10 Exhaust variable valve mechanism 11 Valve timing Sensor 12 Spark plug 13 Knock sensor 14 Crank angle sensor 15 O ₂ sensor 16 External EGR pipe 17 External EGR valve 18 ECU (Electronic Control Unit)

Claims (15)

A control device for an internal combustion engine provided with a variable valve,
Means for calculating the charging efficiency based on at least the rotational speed, the absolute intake pressure, the atmospheric absolute pressure or the exhaust absolute pressure, and the variable valve control amount; at least the rotational speed, the intake absolute pressure, the atmospheric absolute pressure or the exhaust absolute pressure, and the variable valve control amount; Means for calculating an EGR amount on the basis of, a means for calculating a fuel injection amount on the basis of at least the charging efficiency, and a means for calculating an ignition timing on the basis of at least the rotational speed, the charging efficiency, and the EGR amount,
A control device for an internal combustion engine. A control device for an internal combustion engine according to claim 1,
Means for calculating an intake relative pressure which is a ratio of the intake absolute pressure and the atmospheric absolute pressure or the exhaust absolute pressure; means for calculating a charging efficiency reference value based on at least the rotational speed, the intake relative pressure and the variable valve control amount; Means for calculating a high altitude correction amount based on a ratio between the atmospheric absolute pressure and the atmospheric absolute reference pressure; and means for calculating a charging efficiency under a high altitude condition by a product of the filling efficiency reference value and the high altitude correction amount. thing,
A control device for an internal combustion engine. A control device for an internal combustion engine according to claim 1,
Means for calculating an intake relative pressure which is a ratio of the intake absolute pressure to the atmospheric absolute pressure or the exhaust absolute pressure; means for calculating an internal EGR amount reference value based on at least the rotational speed, the intake relative pressure and the variable valve control amount; Calculating an internal EGR amount under a high altitude condition by means of a product of a high altitude correction amount based on a ratio of the atmospheric absolute pressure and the atmospheric absolute reference pressure, and the internal EGR amount reference value and the high altitude correction amount. Providing means,
A control device for an internal combustion engine. A control device for an internal combustion engine according to claim 1,
Means for calculating exhaust absolute pressure based on at least the rotational speed, the charging efficiency, the exhaust temperature, and the atmospheric absolute pressure;
A control device for an internal combustion engine. A control device for an internal combustion engine according to claim 1,
An exhaust pressure sensor for measuring the exhaust absolute pressure in the exhaust flow path;
A control device for an internal combustion engine. A control device for an internal combustion engine according to claim 1,
Means for calculating an exhaust temperature based on at least the ignition timing, the air-fuel ratio, and the EGR rate;
A control device for an internal combustion engine. A control device for an internal combustion engine according to claim 1,
An exhaust temperature sensor for measuring the exhaust temperature in the exhaust flow path;
A control device for an internal combustion engine. A control device for an internal combustion engine according to claim 1,
Means for calculating an external EGR amount based on at least the exhaust absolute pressure, the exhaust temperature, the external EGR valve opening, and the intake absolute pressure;
A control device for an internal combustion engine. A control device for an internal combustion engine according to claim 1,
Means for calculating an EGR rate based on at least the charging efficiency, the internal EGR amount, and the external EGR amount, and at least the ignition by a polynomial having the rotational speed, the charging efficiency, the EGR rate, and the intake valve closing timing as input variables; Having means for calculating the time,
A control device for an internal combustion engine. A control device for an internal combustion engine according to claim 1,
Means for calculating the charging efficiency reference value in a reference atmospheric pressure condition by a polynomial having at least the rotational speed, the intake pipe relative pressure, the intake valve operating angle, the intake valve opening timing, and the exhaust valve closing timing as input variables;
A control device for an internal combustion engine. A control device for an internal combustion engine according to claim 1,
And means for calculating the internal EGR amount reference value in a reference atmospheric pressure condition by a polynomial having at least the rotational speed, the intake pipe relative pressure, the intake valve operating angle, the intake valve opening timing, and the exhaust valve closing timing as input variables. ,
A control device for an internal combustion engine. A control device for an internal combustion engine according to claim 1,
An air flow sensor in the intake passage upstream of the throttle valve, a pressure sensor in the intake passage downstream of the throttle valve, and means for estimating an air flow sensor unit flow rate based on at least the charging efficiency calculation means and the pressure sensor detection value; Means for correcting the filling efficiency calculation result as an error of the filling efficiency calculating means with a deviation between the air flow sensor detected flow rate and the air flow sensor unit estimated flow rate;
A control device for an internal combustion engine. A control device for an internal combustion engine according to claim 1,
An air flow sensor in the intake flow path upstream of the throttle valve, and at least means for estimating the intake absolute pressure downstream of the throttle valve based on the charging efficiency calculation means and the flow rate detected by the air flow sensor;
A control device for an internal combustion engine. A control device for an internal combustion engine according to claim 1,
Means for calculating a target EGR rate based on at least the rotational speed and load; means for calculating a current EGR rate based on the charging efficiency, the internal EGR amount and the external EGR amount; and the target EGR rate and the current EGR Means for calculating the control amount of the variable valve or the external EGR valve opening based on the rate and the intake relative pressure;
A control device for an internal combustion engine. A control device for an internal combustion engine according to claim 1,
In high altitude conditions where the atmospheric pressure decreases with the charging efficiency held constant, during the same overlap period, there is a means to correct the ignition timing to the retard side as the atmospheric pressure decreases. A means for correcting the ignition timing to the retard side as the lap period increases;
A control device for an internal combustion engine.

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