JP4172359B2 - Control device for internal combustion engine - Google Patents

Description

  The present invention relates to a control device for an internal combustion engine.

  In recent years, an apparatus for modeling an intake system of an internal combustion engine based on fluid dynamics or the like and controlling the internal combustion engine based on a control parameter calculated using the model has been studied. That is, for example, for an intake system of an internal combustion engine, a throttle model, an intake pipe model, an intake valve model, etc. are constructed, and by using these models, the amount of air charged in the cylinder from the throttle valve opening, atmospheric pressure, atmospheric temperature, etc. Etc. are calculated, and the internal combustion engine is controlled based on this.

  As one of the above intake valve models, the intake pipe pressure on the downstream side of the throttle valve (hereinafter referred to as “downstream intake pipe pressure”) and the in-cylinder charged air amount or its equivalent value (for example, in-cylinder intake air) The relationship between the flow rate and the in-cylinder air filling rate, etc., expressed by a linear expression using an appropriate value is known (for example, see Patent Document 1). That is, if this model is used, the in-cylinder charged air amount or its equivalent value can be determined based on the downstream intake pipe pressure, and conversely, the downstream intake pipe amount can be calculated based on the in-cylinder charged air amount or its equivalent value. The pressure can be determined. Here, the conforming value is determined based on the operation state at that time, that is, for example, the engine speed, the opening / closing timing of the intake / exhaust valve, etc. In the control, it is determined based on the map.

JP 2002-180877 A JP 2001-41095 A

  By the way, even if the main body part of the internal combustion engine is the same, if the configuration of the part upstream of the intake system throttle valve, for example, an air cleaner or the like is different, the conforming value takes different values accordingly. ing. This is considered to be due to the fact that the conforming value was found in a form that included the effect of pressure loss that occurred in the upstream portion of the throttle valve of the engine intake system. In the control apparatus for an internal combustion engine provided with the above-mentioned, it is necessary to perform an adaptation operation of newly obtaining the above-mentioned adaptation value and recreating the map every time the configuration of the upstream portion of the engine intake system throttle valve changes. That is, for example, a new map needs to be created every time the configuration of an air cleaner or the like changes, and the number of man-hours for such adaptation becomes enormous. For this reason, conventionally, the control device for an internal combustion engine having the above-described primary equation cannot be easily adapted when the configuration of the upstream portion of the engine intake system throttle valve, for example, the configuration of an air cleaner or the like is changed. There wasn't.

  The present invention has been made in view of the above problems, and its object is to provide an expression that expresses the relationship between the intake pipe pressure on the downstream side of the throttle valve and the in-cylinder charged air amount or an equivalent value by using an appropriate value. An internal combustion engine that obtains the in-cylinder charged air amount or its equivalent value from the intake pipe pressure on the downstream side of the throttle valve, or the in-cylinder charged air pressure on the downstream side of the throttle valve from the in-cylinder charged air amount or its equivalent value based on the equation And a control device for an internal combustion engine that can be easily adapted even when the configuration of the upstream portion of the throttle valve of the engine intake system is changed.

  The present invention provides a control device for an internal combustion engine described in each claim as a means for solving the above-mentioned problems.

In the first aspect of the present invention, the relationship between the downstream side intake pipe pressure and the in-cylinder charged air amount or its equivalent value is approximately expressed by using an adaptive value determined according to the operating state of the internal combustion engine. In the control apparatus for an internal combustion engine having the equation (1), the appropriate value may be the downstream value according to the first equation when the upstream intake pipe pressure upstream of the throttle valve is a predetermined reference pressure. The intake air pressure in the cylinder and the amount of air charged in the cylinder or an equivalent value thereof are approximated so that the upstream intake pipe pressure is at least the pressure loss of the air cleaner. In the case of the current upstream intake pipe pressure, the in-cylinder charged air amount or its equivalent value is the adaptation value, the reference pressure, the current upstream intake pipe pressure, and the upstream intake pipe pressure. Present Determined using the above-described downstream side intake pipe pressure when a flow side intake pipe pressure, to provide a control apparatus for an internal combustion engine.

Further, the invention according to claim 2 approximately represents the relationship between the downstream side intake pipe pressure and the in-cylinder charged air amount or an equivalent value by using an adaptive value determined according to the operating state of the internal combustion engine. In the control apparatus for an internal combustion engine having the first equation, the conforming value is obtained by the first equation when the upstream intake pipe pressure upstream of the throttle valve is a predetermined reference pressure. The downstream intake pipe pressure has an adaptive value determined so that the relationship between the in-cylinder charged air amount or its equivalent value can be expressed approximately, and the upstream intake pipe pressure is at least the pressure loss of the air cleaner. The downstream intake pipe pressure when the current upstream intake pipe pressure is considered in consideration of the above-mentioned values is the conformity value, the reference pressure, the current upstream intake pipe pressure, and the upstream intake pipe pressure are the current upstream pressure. ~ side Determined by using the in-cylinder charged air amount or equivalent value thereof in the case of intratracheal pressure, to provide a control apparatus for an internal combustion engine.

In the first or second aspect of the invention, only the adaptation value when the upstream intake pipe pressure is the reference pressure is provided as the adaptation value of the first equation. When obtaining the in-cylinder charged air amount or its equivalent value or the downstream intake pipe pressure when the upstream intake pipe pressure is the current upstream intake pipe pressure, the adaptation value and the reference pressure are obtained. And the current upstream intake pipe pressure and the downstream intake pipe pressure or the in-cylinder charged air amount or equivalent value when the upstream intake pipe pressure is the current upstream intake pipe pressure. Has been.

  By doing in this way, even when the configuration of the upstream portion of the engine intake system throttle valve such as an air cleaner is changed, if the current upstream intake pipe pressure is obtained, the value and the upstream side Using the adaptive value when the intake pipe pressure is the reference pressure, the in-cylinder charged air amount when the upstream intake pipe pressure is the current upstream intake pipe pressure or an equivalent value thereof, or downstream The side intake pipe pressure can be determined. That is, in the first or second aspect of the invention, even when the configuration of the upstream portion of the engine intake system throttle valve such as an air cleaner is changed, the adaptability value of the first expression is newly obtained. There is no need to fix it. Therefore, according to the first or second aspect of the invention, it is possible to provide a control device for an internal combustion engine that can be easily adapted even when the configuration of the upstream portion of the throttle valve of the engine intake system is changed. it can.

The invention according to claim 3 approximately represents the relationship between the downstream side intake pipe pressure and the in-cylinder charged air amount or its equivalent value by using an adaptive value determined according to the operating state of the internal combustion engine. In the control apparatus for an internal combustion engine having the equation (1), the appropriate value may be the downstream value according to the first equation when the upstream intake pipe pressure upstream of the throttle valve is a predetermined reference pressure. The intake air pressure in the cylinder and the amount of air charged in the cylinder or an equivalent value thereof are approximated so that the upstream intake pipe pressure is at least the pressure loss of the air cleaner. In the case of the current upstream intake pipe pressure, the in-cylinder charged air amount or its equivalent value is the adaptation value, the current upstream intake pipe pressure, and the upstream intake pipe pressure is the current upstream intake pipe internal pressure. Pressure Determined using the above-described downstream side intake pipe pressure in the case where, a control apparatus for an internal combustion engine, the downstream side intake pipe pressure and the throttle valve passing air when the upstream side intake pipe pressure is the reference pressure A second expression representing the relationship with the flow rate, wherein the first expression is an expression that approximately represents the relationship between the downstream intake pipe pressure and the in-cylinder intake air flow rate using the adaptive value. When the upstream intake pipe pressure is the current upstream intake pipe pressure, the in-cylinder intake air flow rate when the steady operation is performed in the operation state in which the adaptive value is determined is the same downstream intake pipe pressure. On the other hand, the in-cylinder intake air flow rate when the in-cylinder intake air flow rate obtained by the first equation matches the throttle valve passing air flow rate obtained by the second equation, and the current upstream intake pipe pressure. obtained by using the door, To provide a control apparatus of the combustion engine.
In the invention according to claim 4, the relationship between the downstream side intake pipe pressure and the in-cylinder charged air amount or its equivalent value is approximated by using an adaptive value determined according to the operating state of the internal combustion engine. In the control apparatus for an internal combustion engine having the equation (1), the appropriate value may be the downstream value according to the first equation when the upstream intake pipe pressure upstream of the throttle valve is a predetermined reference pressure. The intake air pressure in the cylinder and the amount of air charged in the cylinder or an equivalent value thereof are approximated so that the upstream intake pipe pressure is at least the pressure loss of the air cleaner. The downstream intake pipe pressure when the current upstream intake pipe pressure is the same value, the current upstream intake pipe pressure, and the upstream intake pipe pressure are the current upstream intake pipe pressure. A control device for an internal combustion engine, which is obtained by using the in-cylinder charged air amount or an equivalent value thereof, wherein the upstream intake pipe pressure and the throttle valve passage when the upstream intake pipe pressure is the reference pressure A second expression representing a relationship with the air flow rate, wherein the first expression is an expression that approximately represents the relationship between the downstream intake pipe pressure and the in-cylinder intake air flow rate using the adaptive value. When the upstream intake pipe pressure is the current upstream intake pipe pressure, the in-cylinder intake air flow rate during steady operation in the operating state in which the adaptive value is determined is the same downstream intake pipe pressure. The in-cylinder intake air flow rate when the in-cylinder intake air flow rate obtained by the first equation and the throttle valve passing air flow rate obtained by the second equation coincide with each other, Calculated using pressure, To provide a control apparatus of the combustion engine.

The invention according to claim 5, first the relationship between the downstream side intake pipe pressure and the in-cylinder charged air amount or equivalent value thereof was approximately expressed by using an adaptation value determined according to the operating state of the internal combustion engine In the control apparatus for an internal combustion engine having the equation (1), the appropriate value may be the downstream value according to the first equation when the upstream intake pipe pressure upstream of the throttle valve is a predetermined reference pressure. The intake air pressure in the cylinder and the amount of air charged in the cylinder or an equivalent value thereof are approximated so that the upstream intake pipe pressure is at least the pressure loss of the air cleaner. In the case of the current upstream intake pipe pressure, the in-cylinder charged air amount or its equivalent value is the adaptation value, the current upstream intake pipe pressure, and the upstream intake pipe pressure is the current upstream intake pipe internal pressure. Pressure Determined using the above-described downstream side intake pipe pressure in the case where, a control apparatus for an internal combustion engine, the downstream side intake pipe pressure and the throttle valve passing air when the upstream side intake pipe pressure is the reference pressure The first equation is an equation that approximately represents the relationship between the downstream side intake pipe pressure and the cylinder intake air flow rate using the adaptive value. Thus, when the upstream intake pipe pressure is the current upstream intake pipe pressure, the downstream intake pipe pressure when the steady operation is performed in the operation state in which the adaptive value is determined is equal to the same downstream intake pipe pressure. The downstream intake pipe pressure when the in-cylinder intake air flow rate obtained by the first equation matches the throttle valve passing air flow rate obtained by the second equation, the current upstream intake pipe pressure, using is required, To provide a control apparatus of the combustion engine.
According to the sixth aspect of the present invention, the relationship between the downstream side intake pipe pressure and the in-cylinder charged air amount or its equivalent value is approximately expressed by using an adaptive value determined according to the operating state of the internal combustion engine. In the control apparatus for an internal combustion engine having the equation (1), the appropriate value may be the downstream value according to the first equation when the upstream intake pipe pressure upstream of the throttle valve is a predetermined reference pressure. The intake air pressure in the cylinder and the amount of air charged in the cylinder or an equivalent value thereof are approximated so that the upstream intake pipe pressure is at least the pressure loss of the air cleaner. The downstream intake pipe pressure when the current upstream intake pipe pressure is the same value, the current upstream intake pipe pressure, and the upstream intake pipe pressure are the current upstream intake pipe pressure. A control device for an internal combustion engine, which is obtained by using the in-cylinder charged air amount or an equivalent value thereof, wherein the upstream intake pipe pressure and the throttle valve passage when the upstream intake pipe pressure is the reference pressure The first equation is a formula that approximately represents the relationship between the downstream side intake pipe pressure and the cylinder intake air flow rate using the adaptive value. When the upstream side intake pipe pressure is the current upstream side intake pipe pressure, the downstream side intake pipe pressure at the time of steady operation in the operation state in which the adaptive value is determined is the same downstream side intake pipe pressure. On the other hand, the downstream intake pipe pressure and the current upstream intake pipe pressure when the in-cylinder intake air flow rate obtained by the first equation and the throttle valve passing air flow rate obtained by the second equation coincide with each other. Sought using To provide a control apparatus of the combustion engine.

In normal operation, the in-cylinder intake air flow rate generally matches the throttle valve passing air flow rate. Accordingly, the in-cylinder intake air when the in-cylinder intake air flow rate obtained by the first equation and the throttle valve passing air flow rate obtained by the second equation coincide with the same downstream side intake pipe internal pressure. When the upstream intake pipe pressure is the reference pressure, the flow rate or the downstream intake pipe pressure is the in-cylinder intake air flow rate when the steady operation is performed in the operation state in which the adaptive value is determined or the downstream intake pipe internal pressure. It is thought to be pressure. In the inventions according to claims 3 to 6, when the upstream intake pipe pressure thus obtained is the reference pressure, the in-cylinder intake air flow rate or the downstream intake pipe internal pressure during steady operation is calculated. Using the current upstream intake pipe pressure, the in-cylinder intake air flow rate or the downstream intake pipe internal pressure during steady operation when the upstream intake pipe pressure is the current upstream intake pipe pressure is obtained. It is supposed to be.

  By doing in this way, when the upstream intake pipe pressure is the current upstream intake pipe pressure, the in-cylinder intake air flow rate or the downstream intake pipe pressure is determined directly when the steady operation is performed. It is possible to reduce the calculation load.

  According to the invention described in each claim, there is provided an expression that expresses the relationship between the intake pipe pressure downstream of the throttle valve and the in-cylinder charged air amount or its equivalent value using an appropriate value, and based on the expression A control device for an internal combustion engine that obtains an in-cylinder charged air amount or an equivalent value from an intake pipe internal pressure on the downstream side of the throttle valve, or an intake pipe internal pressure on the downstream side of the throttle valve from an in-cylinder charged air amount or an equivalent value, Provided is a control device for an internal combustion engine that can be easily adapted even when the configuration of the upstream portion of the engine intake system throttle valve is changed.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or similar components are denoted by common reference numerals.

  FIG. 1 is a schematic view showing an example in which the control device for an internal combustion engine of the present invention is applied to a direct injection spark ignition type internal combustion engine. The present invention may be applied to other spark ignition internal combustion engines and compression ignition internal combustion engines.

  As shown in FIG. 1, the engine body 1 includes a cylinder block 2, a piston 3 that reciprocates within the cylinder block 2, and a cylinder head 4 fixed on the cylinder block 2. A combustion chamber 5 is formed between the piston 3 and the cylinder head 4. In the cylinder head 4, an intake valve 6, an intake port 7, an exhaust valve 8, and an exhaust port 9 are arranged for each cylinder. Further, as shown in FIG. 1, a spark plug 10 is disposed at the center of the inner wall surface of the cylinder head 4, and a fuel injection valve 11 is disposed around the inner wall surface of the cylinder head 4. A cavity 12 extending from the lower side of the fuel injection valve 11 to the lower side of the spark plug 10 is formed on the top surface of the piston 3.

  The intake port 7 of each cylinder is connected to a surge tank 14 via a downstream intake pipe 13, and the surge tank 14 is connected to an air cleaner 16 via an upstream intake pipe 15. A throttle valve 18 driven by a step motor 17 is disposed in the intake pipe 15. On the other hand, the exhaust port 9 of each cylinder is connected to an exhaust pipe 19, and the exhaust pipe 19 is connected to an exhaust purification device 20.

  The electronic control unit (ECU) 31 comprises a digital computer, and is connected to each other via a bidirectional bus 32, a RAM (random access memory) 33, a ROM (read only memory) 34, a CPU (microprocessor) 35, an input. A port 36 and an output port 37 are provided. The intake pipe 13 is provided with an intake pipe pressure sensor 40 for detecting the pressure in the intake pipe downstream of the throttle valve 18, and the intake pipe pressure sensor 40 outputs an output voltage proportional to the intake pipe pressure. This output voltage is input to the input port 36 via the corresponding AD converter 38. An air flow meter 23 for measuring the flow rate of air passing through the air cleaner 16 is provided immediately downstream of the air cleaner 16 in the intake pipe 15, and a corresponding AD converter 38 is provided for the output voltage. To the input port 36.

  Further, a throttle opening sensor 43 for detecting the opening of the throttle valve 18 and a large pressure for detecting the pressure of the atmosphere around the internal combustion engine or the pressure of the air taken into the intake pipe 15 (intake pressure). An atmospheric pressure sensor 44 and an atmospheric temperature sensor 45 for detecting the temperature of the atmosphere around the internal combustion engine or the temperature of the air sucked into the intake pipe 15 (intake air temperature) are provided, and the output voltage of these sensors also corresponds. Is input to the input port 36 via the AD converter 38.

  The accelerator pedal 46 is connected to a load sensor 47 that generates an output voltage proportional to the amount of depression of the accelerator pedal 46 (hereinafter referred to as “accelerator depression amount”), and the output voltage of the load sensor 47 corresponds to the corresponding AD conversion. It is input to the input port 36 through the device 38. For example, the crank angle sensor 48 generates an output pulse every time the crankshaft rotates 30 degrees, and the output pulse is input to the input port 36. The CPU 35 calculates the engine speed from the output pulse of the crank angle sensor 48. On the other hand, the output port 37 is connected to the spark plug 10, the fuel injection valve 11, the step motor 17 and the like via a corresponding drive circuit 39.

  By the way, in recent years, a control device for an internal combustion engine that models an intake system of the internal combustion engine based on fluid dynamics and controls the internal combustion engine based on a control parameter calculated using the model has been studied. That is, for example, for an intake system of an internal combustion engine, a throttle model, an intake pipe model, an intake valve model, etc. are constructed, and parameters necessary for various controls are calculated by using these models, and the internal combustion engine is based on these parameters. To control.

  Also in the present embodiment, the control of the internal combustion engine using the model is performed in the configuration as shown in FIG. 1, but in this embodiment, among the models used for the control, the intake valve is particularly modeled. For the intake valve model, the concept different from the conventional one explained below is adopted. As a result, the adaptation can be easily performed even when the configuration of the upstream portion of the throttle valve of the engine intake system such as an air cleaner is changed.

  Here, first, a general intake valve model which is a premise of the concept of the intake valve model of the present embodiment will be described. That is, generally, the in-cylinder charged air amount Mc (g), which is the amount of air charged in the combustion chamber 5 when the intake valve 6 is closed, is obtained when the intake valve 6 is closed (when the intake valve is closed). And is proportional to the pressure in the combustion chamber 5 when the intake valve is closed. The pressure in the combustion chamber 5 when the intake valve is closed can be regarded as equal to the pressure of the gas upstream of the intake valve, that is, the downstream intake pipe pressure Pm (kPa). Therefore, the cylinder charge air amount Mc can be approximated as being proportional to the downstream side intake pipe pressure Pm.

  Here, the average amount of the total air flowing out from a portion such as an intake pipe (hereinafter referred to as “intake pipe portion”) 13 ′ from the throttle valve to the intake valve per unit time is averaged, or per unit time When the cylinder intake air flow rate mc (g / s) is obtained by averaging the amount of air sucked into all the combustion chambers 5 from the intake pipe portion 13 'over the intake stroke of one cylinder, filling in the cylinder Since the air amount Mc is proportional to the downstream intake pipe pressure Pm, it is considered that the in-cylinder intake air flow rate mc is also proportional to the downstream intake pipe pressure Pm. From this, the following formula 1 is obtained based on the theory and empirical rules.

  Here, a and b in Equation 1 are adaptive values determined according to the operation state of the internal combustion engine, for example, the engine speed. In the case of an internal combustion engine having a variable valve mechanism that can change the phase angle (valve opening / closing timing) and operating angle of the intake valve or the exhaust valve, the conforming values a and b are the values of the phase angle and operating angle. It is necessary to determine the value according to the value.

  Further, with regard to the above-mentioned conformity values a and b, even if the operating state of the internal combustion engine is the same, the downstream side intake pipe pressure Pm is greater than or equal to a predetermined pressure Pmk (Pm ≧ Pmk) and less than that (Pm <Pmk) It is known that in-cylinder intake air flow rate mc may be obtained more accurately by taking two different values (for example, a1, b1 and a2, b2). In other words, the cylinder intake air flow rate mc can be obtained more accurately by setting the above formula 1 to the following formula 2. In this case, the straight lines represented by these two equations are connected at a point of Pm = Pmk. FIG. 2 illustrates Equation 2.

  By making the above equation 2, the in-cylinder intake air flow rate mc can be obtained more accurately, particularly when the intake valve 6 and the exhaust valve 7 are both open (that is, the valve overlap). ) Is considered to be related to the backflow of burned gas to the intake port 7. That is, when there is a valve overlap, when the downstream side intake pipe pressure Pm is equal to or higher than the predetermined pressure Pmk, the higher the downstream side intake pipe pressure Pm, the more the backflow of burned gas significantly decreases. Compared to when the pressure is less than Pmk, the value of a increases and the value of b decreases.

  Here, the in-cylinder intake air flow rate mc will be described with reference to FIG. 3 as an example in which the internal combustion engine has four cylinders. In FIG. 3, the horizontal axis represents the rotation angle of the crankshaft, and the vertical axis represents the amount of air that actually flows into the combustion chamber 5 from the intake pipe portion 13 'per unit time. As shown in FIG. 3, in a four-cylinder internal combustion engine, the intake valve 6 is opened in the order of, for example, the first cylinder, the third cylinder, the fourth cylinder, and the second cylinder, and the intake valve 6 corresponding to each cylinder is opened. Air flows into the combustion chamber 5 of each cylinder from the intake pipe portion 13 'according to the valve opening amount. The displacement of the flow rate of the air flowing into the combustion chamber 5 of each cylinder from the intake pipe portion 13 'is as shown by the broken line in FIG. 3, and the intake pipe portion 13', which combines these, enters the combustion chamber 5 of all cylinders. The flow rate of the inflowing air is as shown by the solid line in FIG. Further, for example, the in-cylinder charged air amount Mc to the first cylinder corresponds to the hatched portion in FIG.

On the other hand, the in-cylinder intake air flow rate mc is obtained by averaging the amount of air flowing into the combustion chambers 5 of all the cylinders from the intake pipe portion 13 'indicated by the solid line, and is indicated by a one-dot chain line in the figure. Has been. In the cylinder intake air flow rate mc indicated by the one-dot chain line, in the case of four cylinders, the crankshaft is 180 ° (that is, the angle 720 ° at which the crankshaft rotates during one cycle in the four-stroke internal combustion engine) Multiplying the time ΔT _{180 °} required for rotation by the angle divided by the number is the in-cylinder charged air amount Mc. Therefore, the cylinder intake air amount Mc can be calculated by multiplying the cylinder intake air flow rate mc calculated by Equation 1 or 2 by ΔT _{180 °} (Mc = mc · ΔT _{180 °} ). Further, the in-cylinder air filling rate Kl can be calculated by dividing the in-cylinder charged air amount Mc by the mass of air that occupies a volume corresponding to the displacement per cylinder in the state of 1 atm and 25 ° C. it can. Thus, the cylinder charge air amount Mc, the cylinder intake air flow rate mc, and the cylinder air charge rate Kl are proportional to each other, and if any one value is obtained, another value can be obtained. In this sense, it can be said that the in-cylinder intake air flow rate mc and the in-cylinder air filling rate Kl are equivalent values of the in-cylinder charged air amount Mc. As is clear from the above description, the same formula as in the above formulas 1 and 2 can be applied to the cylinder fill air amount Mc and the cylinder air fill rate Kl by appropriately converting the appropriate values. However, in the present specification, the description will be made mainly based on the above formula 1 or 2, that is, based on the in-cylinder intake air flow rate mc.

  By the way, in the control apparatus for an internal combustion engine having the general intake valve model equation described above, that is, the above equation 1 or 2, the above-mentioned conformity values a, b or a1, b1, and a2, b2 (hereinafter, The “adapted values a, b, etc.” are usually obtained from a map prepared in advance. In other words, a map is prepared by measuring the conforming values a, b, etc. for each operating state in advance through experiments or the like, and the map is searched for and obtained as necessary.

  However, the above-mentioned conformity values a, b, etc. obtained by actual measurement are different if the structure of the upstream portion of the intake system throttle valve, for example, an air cleaner, is different even if the main body of the internal combustion engine is the same. It is known that it takes different values with it. This is considered to be because when the conforming values a, b, etc. are obtained by actual measurement, they are obtained in a form including the effect of pressure loss that occurs in the upstream portion of the throttle valve of the engine intake system. As a result, in the control apparatus for an internal combustion engine provided with the equation of the intake valve model including the adaptive values a and b as in the above formula 1 or 2, the configuration of the upstream portion of the engine intake system changes from the throttle valve. An adaptation operation is required in which the adaptation values a and b are newly obtained for each time and the map is recreated. That is, for example, a new map needs to be created every time the configuration of an air cleaner or the like changes, and the number of man-hours for such adaptation becomes enormous. For this reason, in the conventional control device for an internal combustion engine having the equation of the intake valve model as shown in the equation 1 or 2, the configuration of the upstream portion of the engine intake system, for example, the configuration of the air cleaner or the like is changed. It was not easy to fit.

  In contrast, in the present embodiment, when the configuration of the upstream portion of the engine intake system throttle valve is changed by eliminating the influence of the pressure loss on the adaptive value by the method described below. Is also easy to adapt.

  That is, in order to eliminate the influence of the pressure loss on the adaptive value, the intake pipe pressure upstream of the throttle valve 18 (hereinafter referred to as “upstream intake pipe pressure”) is set to a reference pressure Pab (for example, a standard high pressure). Considering the relationship between the downstream side intake pipe pressure Pmb (kPa) and the in-cylinder intake air flow rate mcb (g / s) in the case of the atmospheric pressure Pas), the following equation 3 is obtained in the same manner as the above equation 2. Can be represented.

  Here, A1, B1 and A2, B2 are conforming values determined according to the operating state of the internal combustion engine, similar to the conforming values a1, b1 and a2, b2 of Equation 2, but the upstream intake pipe pressure is When the reference pressure Pab is assumed, the value is an adaptive value determined so that the relationship between the downstream side intake pipe pressure Pmb and the in-cylinder intake air flow rate mcb can be approximately expressed by the above equation (3). These are obtained, for example, as follows.

  That is, as in the case of obtaining the adaptation values a1, b1 and a2, b2 in Equation 2, the cylinder intake air flow rate mc is set at every predetermined interval of the downstream intake pipe pressure Pm in the operating state where the adaptation values are to be obtained. Measure. Thereby, a plot is obtained on the Pm-mc coordinate. When the adaptation values are obtained based on these plots, the adaptation values a1, b1 and a2, b2 are obtained. In other words, the relationship between the downstream side intake pipe pressure Pm and the cylinder intake air flow rate mc obtained at this time includes the effect of pressure loss that occurs at the upstream side of the throttle valve of the intake system of the internal combustion engine used for the measurement. It is a thing.

  On the other hand, the upstream side intake pipe pressure at the time of each measurement is obtained simultaneously with the above measurement. This upstream side intake pipe pressure is determined in consideration of at least the pressure loss of the air cleaner 16, and is hereinafter referred to as the current upstream side intake pipe pressure Pac. The current upstream intake pipe pressure Pac may be detected by providing a pressure sensor immediately upstream of the throttle valve 18, but can be calculated without using the pressure sensor. That is, the difference between the atmospheric pressure Pa and the current upstream intake pipe pressure Pac can be expressed by the following equation 4 according to Bernoulli's theorem.

  Here, ρ is an atmospheric density, v is a flow velocity of air passing through the air cleaner 16, Ga is a flow rate of air passing through the air cleaner 16, and k is a proportional coefficient of v and Ga. If the standard atmospheric density ρ0 and the pressure correction coefficient ekpa and the temperature correction coefficient ektha for converting the standard atmospheric density ρ0 to the current atmospheric density ρ are used, Equation 4 can be rewritten as the following Equation 5. Furthermore, Expression 5 can be rewritten as Expression 6 below using a function f (Ga) having only the flow rate Ga as a variable.

  Equation 6 can be modified as the following equation 7 representing the current upstream intake pipe pressure Pac. In Equation 7, the flow rate Ga can be detected by the air flow meter 23 provided immediately downstream of the air cleaner 16. Further, the pressure correction coefficient ekpa can be set by the detected atmospheric pressure Pa, and the temperature correction coefficient ektha can be set by the detected atmospheric temperature Ta.

  Next, using the current upstream intake pipe pressure Pac measured or calculated in this way, the coordinates (Pm, mc) of each plot on the Pm-mc coordinate obtained by the measurement of the in-cylinder intake air flow rate mc described above. ) Will be corrected. Specifically, the value of coordinates (Pm, mc) representing each plot is multiplied by the reference pressure Pab / the current upstream intake pipe pressure Pac. That is, the following equation 8 is used.

  Then, when the matching value is obtained based on the plot expressed by the coordinates (Pmb, mcb) corrected in this way, the matching values A1, B1, A2, and B2 are obtained. As is clear from the above description, the predetermined pressure Pmkb in the above equation 3 can be expressed by the following equation 9 using the predetermined pressure Pmk in the above equation 2. Further, when the above formula 2 and the above formula 3 are illustrated together with the plots before and after the correction, for example, FIG. 4 is obtained.

  In the present embodiment, only the adaptation values A1, B1, A2, and B2 obtained as described above are provided as maps as the adaptation values used in the equation of the intake valve model. By obtaining these conforming values A1, B1 and A2, B2 as described above, the influence of pressure loss that occurs in the upstream portion of the throttle valve of the engine intake system is eliminated. In other words, these conforming values A1, B1 and A2, B2 are different from the conforming values a1, b1, and a2, b2, etc. in Equation 2, when the configuration of the upstream portion of the engine intake system throttle valve is changed. There is no need to re-fit.

  However, since these adaptation values A1, B1 and A2, B2 are adaptation values when the upstream intake pipe pressure is the reference pressure Pab as described above, these adaptation values A1, B1, and A2 , B2 cannot be directly applied to Equation 2 and used for actual control. This is because in the actual control scene, there is a pressure loss of the air cleaner 16 and the like, and therefore the upstream intake pipe pressure is not the reference pressure Pab but the current upstream intake pipe pressure Pac. .

  Therefore, in the present embodiment, in actual control, that is, when the upstream intake pipe pressure is the current upstream intake pipe pressure Pac, the cylinder intake air flow rate mc is calculated from the actual downstream intake pipe pressure Pm. When obtaining, or when obtaining the downstream intake pipe pressure Pm from the actual in-cylinder intake air flow rate mc, the actual downstream intake pipe pressure Pm or in-cylinder intake air flow rate mc is first expressed by the above equation (8). Then, the value is substituted into the above equation (3). Then, the obtained mcb or Pmb is again substituted into the above equation 8, and the in-cylinder intake air flow rate mc or the downstream intake pipe pressure Pm to be obtained is obtained.

  In other words, using the following equation 10 obtained by substituting the above equation 8 into the above equation 3, the cylinder intake air flow rate mc from the actual downstream intake pipe pressure Pm or the actual cylinder intake air flow rate mc To determine the downstream side intake pipe pressure Pm.

  As is clear from the above formula 10, in the present embodiment, the adaptation values A1, B1, and A2, B2, the current upstream intake pipe pressure Pac, and the downstream intake pipe pressure Pm The intake air flow rate mc can be obtained. Conversely, the downstream side intake pipe pressure Pm can be obtained using the adaptation values A1, B1 and A2, B2, the current upstream side intake pipe pressure Pac, and the cylinder intake air flow rate mc.

  And, as described above, the adaptation values A1, B1 and A2, B2 do not need to be adapted again when the configuration of the upstream portion of the engine intake system throttle valve is changed. For example, the air cleaner is changed. In this case, if the current upstream intake pipe pressure Pac is required, that is, if the pressure loss occurring at the upstream side of the throttle valve of the engine intake system including the air cleaner is required, the conforming value can not be re-adapted. However, the in-cylinder intake air flow rate mc and the downstream intake pipe pressure Pm can be obtained with high accuracy. As described above, the control device for an internal combustion engine according to the present embodiment can be easily adapted even when the configuration of the upstream portion of the engine intake system is changed.

  By the way, the control apparatus for an internal combustion engine of the present embodiment further includes the following formula 11 as an expression of a throttle model that models a throttle valve. Equation 11 represents the relationship between the downstream intake pipe pressure Pmb (kPa) and the throttle valve passage air flow rate mtb (g / s) when the upstream intake pipe pressure is the reference pressure Pab. That is, in the case of Equation 11, as in the case of Equation 3, the influence of the pressure loss that occurs in the upstream portion of the throttle valve of the engine intake system is eliminated.

Here, Ta (K) is the atmospheric temperature and R is a gas constant. Further, μ is a flow coefficient in the throttle valve, which is a function of the throttle valve opening θt, and is determined from a map as shown in FIG. At (m ² ) represents the opening cross-sectional area of the throttle valve (hereinafter referred to as “throttle opening area”), and is a function of the throttle valve opening θt. If μ · At, which summarizes the flow coefficient μ and the throttle opening area At, is a function F (θt) in which only the throttle valve opening θt is a variable, Equation 11 can be rewritten as Equation 12.

  Φ (Pmb / Pab) is a function shown in the following equation (13), and κ in the equation (13) is a specific heat ratio (κ = Cp (isobaric specific heat) / Cv (isovolume specific heat), which is a constant value). is there. Since this function Φ (Pmb / Pab) can be expressed in a graph as shown in FIG. 6, such a graph is saved as a map in the ROM of the ECU, and in actuality, it is not calculated using Equation 13 Alternatively, the value of Φ (Pmb / Pab) may be obtained from the map.

  The above-mentioned formulas 11 to 13 (hereinafter referred to as “formula 11 etc.”) of the throttle model are compared with the modeled throttle valve 18, the upstream intake pipe pressure is the reference pressure Pab, and the gas upstream of the throttle valve 18. The temperature of air is the atmospheric temperature Ta, the pressure of the gas passing through the throttle valve 18 is the downstream intake pipe pressure Pmb, the law of conservation of mass, the law of conservation of energy and the law of conservation of momentum are applied. It is obtained by using the formula and Meyer's relational formula.

  As is apparent from the above description, when the influence of the pressure loss occurring in the upstream portion of the throttle valve of the engine intake system is included, that is, the upstream intake pipe pressure is at least the pressure of the air cleaner 16. Regarding the expression representing the relationship between the downstream side intake pipe pressure Pm and the throttle valve passage air flow rate mt in the case of the current upstream side intake pipe pressure Pac obtained in consideration of the loss, the relationship between the Pmb and the Pm and the above Since the relationship between mtb and the above mt can be expressed as in the following equation 14, the following equation 15 is obtained based on the above equation 11. Similarly, equations corresponding to the above equations 12 and 13 are as shown in the following equations 16 and 17. These Equations 15 to 17 (hereinafter referred to as “Equation 15 etc.”) can be said to be expressions representing the actual downstream side intake pipe pressure Pm and the throttle valve passage air flow rate mt. The engine control device may include the above equation 15 and the like.

  By the way, when controlling the internal combustion engine, particularly when controlling the internal combustion engine using a model, in order to calculate parameters related to the control, the intake pipe pressure Pmta on the downstream side of the throttle valve during steady operation is calculated. In some cases, the cylinder intake air flow rate mcta (or the cylinder charge air amount Mcta or the cylinder air charge rate Klta at the time of steady operation which can be calculated therefrom) may be required. Here, the value at the time of steady operation (the above-mentioned Pmta, mcta, etc.) is a value finally taken when the internal combustion engine is normally operated in a certain state, that is, a value considered as a convergence value.

  These values are mainly used to control the internal combustion engine in order to reduce the control load by avoiding complicated calculations and reducing the amount of calculations, and to improve the accuracy of the calculated parameters. It is done. Conventionally, these values have been obtained using a map, but it took a long time to create the map.

On the other hand, in the present embodiment, when the above Pmta or mcta (or Klta or the like) is required, the calculation is performed by the method described below.
That is, as described above, the control apparatus for an internal combustion engine of the present embodiment has a relationship between the downstream intake pipe pressure Pmb and the cylinder intake air flow rate mcb when the upstream intake pipe pressure is the reference pressure Pab. And the expression representing the relationship between the downstream side intake pipe pressure Pmb and the throttle valve passing air flow rate mtb when the upstream side intake pipe pressure is the reference pressure Pab (ie, the above equation 3) , The above formula 11 etc.).

  When the internal combustion engine is in steady operation, the throttle valve passage air flow rate mtb and the cylinder intake air flow rate mcb coincide. Therefore, if the downstream side intake pipe pressure Pmb when the throttle valve passage air flow rate mtb obtained from the equation (11) and the in-cylinder intake air flow rate mcb obtained from the equation (3) coincide with each other is obtained, it is steady under the operating conditions at that time. The downstream side intake pipe pressure Pmtab at the time of operation is obtained. Similarly, by obtaining the in-cylinder intake air flow rate mcb when the throttle valve passage air flow rate mtb obtained from the above equation 11 and the in-cylinder intake air flow rate mcb obtained from the above equation 3 coincide with each other, The in-cylinder intake air flow rate mctab at the time of steady operation under conditions can be obtained (and the in-cylinder air filling rate Kltab at the time of steady operation can be obtained from this value).

  Then, obtaining Pmtab and mctab as described above is to obtain the intersection point EPb between the curve mtb represented by Equation 11 and the straight line mcb represented by Equation 3 as illustrated in FIG. It is synonymous with. Here, when the intersection point EPb is obtained, the calculation becomes very complicated if it is attempted to obtain the intersection point EPb using the equation 11 representing the curve mtb as it is. Therefore, in order to simplify the calculation, the above equation 11 or the like may be approximated by a linear expression of a plurality of downstream side intake pipe pressures Pmb. That is, the curve mtb is approximated by a plurality of straight lines. Specifically, for example, the throttle valve passage air flow rate mtb is calculated based on the above equation 11 or the like at regular intervals of the downstream side intake pipe internal pressure Pmb, and on the curve mtb at regular intervals of the downstream side intake pipe internal pressure Pmb. A point is obtained, and each straight line connecting these two adjacent points is obtained as an approximate straight line of the curve mtb. A linear expression representing each of these approximate straight lines is an approximate linear expression such as Equation 11 above.

  By the way, the approximation to the linear equation such as Equation 11 is for easily obtaining the intersection point EPb, and therefore, an approximation linear equation such as Equation 11 in the vicinity of the intersection point EPb is required. Therefore, only this approximate linear expression may be obtained. In this case, the in-cylinder intake air flow rate mcb is also obtained based on the above formula 3 at regular intervals of the downstream side intake pipe internal pressure Pmb, and the magnitudes of the throttle valve passage air flow rate mtb and the in-cylinder intake air flow rate mcb are reversed. The position of the intersection point EPb can be specified by finding the place to do.

  That is, the approximate linear expression in the vicinity of the intersection point EPb (that is, the portion where the magnitude of the throttle valve passage air flow rate mtb and the cylinder intake air flow rate mcb is reversed) is, for example, on the curve mtb represented by the above equation 11 or the like. It is a linear expression that represents a straight line that connects two points before and after the point where the magnitudes of the throttle valve passage air flow rate mtb and the cylinder intake air flow rate mcb are reversed.

  By the way, both the downstream side intake pipe pressure Pmtab and the in-cylinder intake air flow rate mctab at the time of steady operation obtained by obtaining the intersection point EPb are set such that the upstream side intake pipe pressure is the reference pressure Pab. Is the case value. Therefore, when the actual value, that is, when the upstream intake pipe pressure is the current upstream intake pipe pressure Pac determined at least in consideration of the pressure loss of the air cleaner 16, the downstream intake pipe pressure Pmta at the time of steady operation is obtained. In order to obtain the in-cylinder intake air flow rate mcta, it is necessary to correct the Pmtab and the mctab obtained as described above using the current upstream intake pipe pressure Pac. This correction can be performed as shown in the following equation (18). The downstream side intake pipe pressure Pmta and the in-cylinder intake air flow rate mcta obtained during the steady operation obtained by the equation 18 are values used in actual control.

  The downstream side intake pipe pressure Pmta and the in-cylinder intake air flow rate mcta at the time of steady operation obtained by the above formula 18 represent the straight line mc representing the above formula 2 shown by the dotted line in FIG. The coordinates of the intersection point EP with the curve mt. Therefore, as a method of obtaining these Pmta and mcta, a method of directly obtaining the intersection point EP between the straight line mc and the curve mt can be considered. However, if it does so, in the process of calculating | requiring the said intersection EP, it will be necessary to perform the correction | amendment using the said current upstream intake pipe pressure Pac frequently, and calculation load will increase. Therefore, when obtaining the downstream side intake pipe pressure Pmta and the cylinder intake air flow rate mcta during the steady operation, the method as described above, that is, the intersection point EPb is first obtained, and finally the coordinates (Pmtab, It is preferable to take a method of correcting the value of mctab) using the current upstream intake pipe pressure Pac.

  In the above description, the description has been made mainly based on the cylinder intake air flow rate mc (or mcb). However, as described above, the cylinder charge air amount Mc, the cylinder intake air flow rate mc, and the cylinder air charge Since the rates Kl are proportional to each other and can be converted into each other by an appropriate coefficient, the cylinders in the case where the upstream intake pipe pressure is the current upstream intake pipe pressure Pac are substantially the same as the above-described methods. The in-cylinder charge air amount Mc and the in-cylinder air charge rate Kl, and the in-cylinder charge air amount Mcta and the in-cylinder air charge during steady operation when the upstream intake pipe pressure is the current upstream intake pipe pressure Pac. It is possible to determine the rate Klta.

FIG. 1 is a schematic view showing an example in which the control device for an internal combustion engine of the present invention is applied to a direct injection spark ignition type internal combustion engine. FIG. 2 is a diagram illustrating an example of the relationship between the downstream side intake pipe pressure Pm and the in-cylinder charged air flow rate mc. FIG. 3 is a diagram relating to the definition of the in-cylinder charged air amount Mc and the in-cylinder intake air flow rate mc. FIG. 4 shows the relationship between the downstream intake pipe pressure Pmb and the cylinder intake air flow rate mcb when the upstream intake pipe internal pressure is the reference pressure, and the upstream intake pipe internal pressure is the current upstream intake pipe internal pressure. It is the figure which showed the relationship between the downstream side intake pipe pressure Pm and the cylinder intake air flow rate mc in the case.

FIG. 5 is a diagram showing the relationship between the throttle valve opening and the flow coefficient. FIG. 6 is a diagram illustrating the function Φ (Pmb / Pab). FIG. 7 is a diagram showing the relationship between the downstream side intake pipe pressure, the throttle valve passing air flow rate and the cylinder intake air flow rate, and the steady state when the upstream side intake pipe pressure is the current upstream side intake pipe pressure. It is a figure for demonstrating the method of calculating | requiring the downstream side intake pipe internal pressure Pmta and the cylinder intake air flow rate mcta at the time of a driving | operation.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Engine body 5 ... Combustion chamber 6 ... Intake valve 7 ... Intake port 8 ... Exhaust valve 9 ... Exhaust port 11 ... Fuel injection valve 13 ... Intake pipe 18 ... Throttle valve 23 ... Air flow meter

Claims (6)

An internal combustion engine having a first equation that approximately represents the relationship between the downstream side intake pipe pressure and the in-cylinder charged air amount or an equivalent value by using an adaptive value determined according to the operating state of the internal combustion engine. In the control device of
When the upstream side intake pipe pressure on the upstream side of the throttle valve is a predetermined reference pressure, the appropriate value is the downstream side intake pipe pressure and the in-cylinder charged air amount or their equivalents according to the first equation. It has a fitness value that is defined so that the relationship with the value can be expressed approximately.
When the upstream intake pipe pressure is the current upstream intake pipe pressure considering at least the pressure loss of the air cleaner, the in-cylinder charged air amount or its equivalent value is the adaptation value, the reference pressure, and the current upstream A control device for an internal combustion engine, which is obtained using a side intake pipe internal pressure and the downstream side intake pipe internal pressure when the upstream side intake pipe internal pressure is the current upstream side intake pipe internal pressure. An internal combustion engine having a first equation that approximately represents the relationship between the downstream side intake pipe pressure and the in-cylinder charged air amount or an equivalent value by using an adaptive value determined according to the operating state of the internal combustion engine. In the control device of
When the upstream side intake pipe pressure on the upstream side of the throttle valve is a predetermined reference pressure, the appropriate value is the downstream side intake pipe pressure and the in-cylinder charged air amount or their equivalents according to the first equation. It has a fitness value that is defined so that the relationship with the value can be expressed approximately.
When the upstream intake pipe internal pressure is the current upstream intake pipe internal pressure taking into account at least the pressure loss of the air cleaner, the downstream intake pipe internal pressure is the adaptation value, the reference pressure, and the current upstream intake pipe internal pressure. And a control device for an internal combustion engine, which is obtained by using the in-cylinder charged air amount or the equivalent value when the upstream intake pipe internal pressure is the current upstream intake pipe internal pressure. An internal combustion engine having a first equation that approximately represents the relationship between the downstream side intake pipe pressure and the in-cylinder charged air amount or an equivalent value by using an adaptive value determined according to the operating state of the internal combustion engine. In the control device of
When the upstream side intake pipe pressure on the upstream side of the throttle valve is a predetermined reference pressure, the appropriate value is the downstream side intake pipe pressure and the in-cylinder charged air amount or their equivalents according to the first equation. It has a fitness value that is defined so that the relationship with the value can be expressed approximately.
When the upstream intake pipe pressure is the current upstream intake pipe pressure considering at least the pressure loss of the air cleaner, the in-cylinder charged air amount or its equivalent value is calculated as follows: the adaptation value, the current upstream intake pipe pressure, A control device for an internal combustion engine, which is obtained using the downstream intake pipe internal pressure when the upstream intake pipe internal pressure is the current upstream intake pipe internal pressure,
A second equation representing the relationship between the downstream intake pipe pressure and the throttle valve passing air flow rate when the upstream intake pipe pressure is the reference pressure;
The first equation is an equation that approximately represents the relationship between the downstream intake pipe pressure and the cylinder intake air flow rate using the adaptive value.
When the upstream intake pipe pressure is the current upstream intake pipe pressure, the in-cylinder intake air flow rate when the steady operation is performed in the operation state in which the adaptive value is determined is the same as the downstream downstream intake pipe pressure. The in-cylinder intake air flow rate when the in-cylinder intake air flow rate obtained by the first equation and the throttle valve passing air flow rate obtained by the second equation coincide with each other and the current upstream intake pipe pressure are used. A control device for an internal combustion engine , which is required . An internal combustion engine having a first equation that approximately represents the relationship between the downstream side intake pipe pressure and the in-cylinder charged air amount or an equivalent value by using an adaptive value determined according to the operating state of the internal combustion engine. In the control device of
When the upstream side intake pipe pressure on the upstream side of the throttle valve is a predetermined reference pressure, the appropriate value is the downstream side intake pipe pressure and the in-cylinder charged air amount or their equivalents according to the first equation. It has a fitness value that is defined so that the relationship with the value can be expressed approximately.
In the case where the upstream intake pipe pressure is the current upstream intake pipe pressure considering at least the pressure loss of the air cleaner, the downstream intake pipe pressure is determined as the adaptation value, the current upstream intake pipe pressure, and the upstream side. A control device for an internal combustion engine, which is obtained using the in-cylinder charged air amount or an equivalent value when the intake pipe internal pressure is the current upstream intake pipe internal pressure,
A second equation representing the relationship between the downstream intake pipe pressure and the throttle valve passing air flow rate when the upstream intake pipe pressure is the reference pressure;
The first equation is an equation that approximately represents the relationship between the downstream intake pipe pressure and the cylinder intake air flow rate using the adaptive value.
When the upstream intake pipe pressure is the current upstream intake pipe pressure, the in-cylinder intake air flow rate when the steady operation is performed in the operation state in which the adaptive value is determined is the same as the downstream downstream intake pipe pressure. The in-cylinder intake air flow rate when the in-cylinder intake air flow rate obtained by the first equation and the throttle valve passing air flow rate obtained by the second equation coincide with each other and the current upstream intake pipe pressure are used. A control device for an internal combustion engine , which is required . An internal combustion engine having a first equation that approximately represents the relationship between the downstream side intake pipe pressure and the in-cylinder charged air amount or an equivalent value by using an adaptive value determined according to the operating state of the internal combustion engine. In the control device of
When the upstream side intake pipe pressure on the upstream side of the throttle valve is a predetermined reference pressure, the appropriate value is the downstream side intake pipe pressure and the in-cylinder charged air amount or their equivalents according to the first equation. It has a fitness value that is defined so that the relationship with the value can be expressed approximately.
When the upstream intake pipe pressure is the current upstream intake pipe pressure considering at least the pressure loss of the air cleaner, the in-cylinder charged air amount or its equivalent value is calculated as follows: the adaptation value, the current upstream intake pipe pressure, A control device for an internal combustion engine, which is obtained using the downstream intake pipe internal pressure when the upstream intake pipe internal pressure is the current upstream intake pipe internal pressure,
A second equation representing the relationship between the downstream intake pipe pressure and the throttle valve passage air flow rate when the upstream intake pipe pressure is the reference pressure;
The first equation is an equation that approximately represents the relationship between the downstream intake pipe pressure and the cylinder intake air flow rate using the adaptive value.
When the upstream side intake pipe pressure is the current upstream side intake pipe pressure, the downstream side intake pipe pressure when the steady operation is performed in the operation state in which the adaptive value is determined is the same as the downstream side intake pipe pressure. The downstream intake pipe pressure and the current upstream intake pipe pressure when the in-cylinder intake air flow rate obtained by the first equation and the throttle valve passing air flow rate obtained by the second equation coincide with each other are used. A control device for an internal combustion engine , which is required. An internal combustion engine having a first equation that approximately represents the relationship between the downstream side intake pipe pressure and the in-cylinder charged air amount or an equivalent value by using an adaptive value determined according to the operating state of the internal combustion engine. In the control device of
When the upstream side intake pipe pressure on the upstream side of the throttle valve is a predetermined reference pressure, the appropriate value is the downstream side intake pipe pressure and the in-cylinder charged air amount or their equivalents according to the first equation. It has a fitness value that is defined so that the relationship with the value can be expressed approximately.
In the case where the upstream intake pipe pressure is the current upstream intake pipe pressure considering at least the pressure loss of the air cleaner, the downstream intake pipe pressure is determined as the adaptation value, the current upstream intake pipe pressure, and the upstream side. A control device for an internal combustion engine, which is obtained using the in-cylinder charged air amount or an equivalent value when the intake pipe internal pressure is the current upstream intake pipe internal pressure,
A second equation representing the relationship between the downstream intake pipe pressure and the throttle valve passage air flow rate when the upstream intake pipe pressure is the reference pressure;
The first equation is an equation that approximately represents the relationship between the downstream intake pipe pressure and the cylinder intake air flow rate using the adaptive value.
When the upstream side intake pipe pressure is the current upstream side intake pipe pressure, the downstream side intake pipe pressure when the steady operation is performed in the operation state in which the adaptive value is determined is the same as the downstream side intake pipe pressure. The downstream intake pipe pressure and the current upstream intake pipe pressure when the in-cylinder intake air flow rate obtained by the first equation and the throttle valve passing air flow rate obtained by the second equation coincide with each other are used. A control device for an internal combustion engine , which is required.

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