JP2010222988A - Intake air quantity estimation device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an intake air quantity estimation device for an internal combustion engine capable of suppressing the slippage of a cylinder intake air quantity over a wide temperature range from a cold engine state to a state after the completion of engine warm-up, and performing accurate engine operation. <P>SOLUTION: An electronic control device 100 calculates the cylinder intake air quantity by using a relation indicated by a formula: mc=(Ta/Tm)*(A*Pm+C) where intake pipe pressure which is pressure at a downstream of a throttle valve 25 in an intake air passage 20 is indicated as Pm, an air temperature of an upstream of the throttle valve 25 is indicated as Ta, an intake pipe temperature which is an air temperature at the downstream of the throttle valve 25 is indicated as Tm, the cylinder intake air quantity which is the mass of air sucked in a cylinder 11 at a downstream side of an air valve 15 is indicated as mc, and a correction coefficient is indicated as C. A pressure coefficient equivalent to A in the formula is a positive value variably set based on the intake pipe temperature in such a manner that the pressure coefficient becomes larger as the intake pipe temperature becomes lower. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an intake air amount estimation device for an internal combustion engine that estimates an in-cylinder intake air amount that is a mass of air sucked into each cylinder of the internal combustion engine based on an intake pipe pressure and an intake pipe temperature.

  As an intake air amount estimation device for an internal combustion engine, an operation formula created based on a physical model such as a throttle valve model, an intake pipe model, an intake valve model, etc. is used until the intake valve is closed in the intake stroke. There is known an intake air amount estimation device for an internal combustion engine that preliminarily estimates a mass Mc of air filled in a cylinder in advance (for example, Patent Document 1).

  According to such an intake air amount estimation device, the mass Mc, which is the mass of air used for combustion, can be estimated before the intake valve is closed. Accordingly, by setting the fuel injection amount based on the estimated mass Mc, it becomes possible to supply an amount of fuel in the cylinder in accordance with the mass Mc of the air used for combustion, and the throttle opening degree. The engine can be accurately controlled even in a transient state immediately after the engine is changed.

  In Patent Literature 1, an intake pipe pressure Pm that is a pressure at a portion downstream of the throttle valve in the intake passage is used as an arithmetic expression of the intake valve model based on the following formula created based on empirical rules: A method is described in which an in-cylinder intake air amount mc, which is the mass of air sucked into each cylinder, is calculated on the basis of the intake pipe temperature Tm, which is the temperature of air at the downstream side of the throttle valve.

尚、上記の数式における「Ｔａ」は、吸気通路内のスロットル弁よりも上流側の部位における空気の温度であり、ここでは大気温度としている。

Note that “Ta” in the above formula is the temperature of the air in the upstream side of the throttle valve in the intake passage, and here it is the atmospheric temperature.

  If the configuration for calculating the in-cylinder intake air amount mc using the above formula is adopted, the in-cylinder intake air amount is calculated based on the intake pipe pressure Pm and the intake pipe temperature Tm predicted through the throttle valve model and the intake pipe model. mc can be estimated. Based on the in-cylinder intake air amount mc thus estimated, the mass Mc of the air charged in the cylinder before the intake valve is closed is calculated, and the fuel injection amount is set based on this. As described above, accurate engine control can be realized.

International Publication WO2003 / 033897

  By the way, the above formula is a formula created based on the results of experiments and the like, and the values of the coefficients c and d in this formula are the values of the in-cylinder intake air amount mc calculated using this formula. It is set empirically based on the results of experiments and the like so as to be in line with changes in the actual in-cylinder intake air amount with respect to changes in the pipe pressure Pm and the intake pipe temperature Tm. Such experiments are generally performed assuming engine operation after completion of warm-up.

  Therefore, in the intake air amount estimation device for the internal combustion engine that calculates the in-cylinder intake air amount mc using the above formula, it is assumed when the coefficients c and d are set as in the case of cold engine. Under different conditions, the calculated in-cylinder intake air amount mc deviates from the actual in-cylinder intake air amount, which may result in failure to achieve accurate engine control.

  The present invention has been made in view of the above circumstances, and its purpose is to suppress a deviation in the in-cylinder intake air amount over a wide temperature range from when the engine is cold to completion of engine warm-up, and to perform an accurate engine operation. An object of the present invention is to provide an intake air amount estimation device for an internal combustion engine that can be realized.

In the following, means for achieving the above object and its effects are described.
In the first aspect of the present invention, “Pm” is an intake pipe pressure that is a pressure in a portion downstream of the throttle valve in the intake passage, “Ta” is a temperature of air in a portion upstream of the throttle valve, “Tm” is the intake pipe temperature that is the temperature of the air downstream of the throttle valve, “mc” is the in-cylinder intake air amount that is the mass of air sucked into the cylinder, and “C” is the correction coefficient An intake air amount estimation device for an internal combustion engine that calculates an in-cylinder intake air amount using a relationship represented by the following mathematical formula,

当該数式における「Ａ」に相当する圧力係数は、吸気管温度が低いときほど大きくなるように吸気管温度に基づいて可変設定される正の値であることをその要旨としている。

The gist of the pressure coefficient corresponding to “A” in the equation is a positive value that is variably set based on the intake pipe temperature so as to increase as the intake pipe temperature decreases.

  The higher the intake pipe pressure, the larger the pressure difference between the air pressure in the intake passage and the negative pressure generated in the cylinder, and the amount of air taken into the cylinder increases. At this time, when the intake pipe temperature is low, the density of the air in the intake passage is high, so that the mass of air sucked into the cylinder, that is, the in-cylinder intake air amount, is larger than when the intake pipe temperature is high. To do. On the other hand, when the intake pipe temperature is high, the density of the air in the intake passage is low, so that the in-cylinder intake air amount is reduced compared to when the intake pipe temperature is low. That is, the increase / decrease degree of the in-cylinder intake air amount with respect to the change of the intake pipe pressure varies depending on the intake pipe temperature, and the lower the intake pipe temperature, the more the increase / decrease degree of the in-cylinder intake air amount accompanying the increase / decrease of the intake pipe pressure. Will grow.

  On the other hand, when performing an experiment etc. in advance assuming engine operation after completion of warm-up as in the past, and setting each coefficient of the mathematical formula for calculating the cylinder intake air amount based on the result Does not take into account that the degree of increase or decrease in the in-cylinder intake air amount with respect to the intake pipe pressure changes according to the intake pipe temperature as described above. There is a possibility that the intake air amount cannot be accurately calculated.

  In this regard, in the intake air amount estimating apparatus for an internal combustion engine according to claim 1, the pressure coefficient is variably set based on the intake pipe temperature so that the pressure coefficient increases as the intake pipe temperature decreases. I have to. Therefore, it is possible to appropriately calculate the in-cylinder intake air amount in a manner corresponding to the change in the degree of increase / decrease in the in-cylinder intake air amount with respect to the intake pipe pressure in accordance with the intake pipe temperature. That is, the in-cylinder intake air amount can be appropriately estimated even when the engine temperature is low and the intake pipe temperature is particularly low when the engine is cold. Therefore, according to the configuration of the first aspect of the invention, it is possible to suppress the deviation of the in-cylinder intake air amount over a wide temperature range from when the engine is cold to after completion of the engine warm-up, thereby realizing an accurate engine operation. Will be able to.

  According to the second aspect of the present invention, “Pm” is an intake pipe negative pressure that is a pressure at a portion downstream of the throttle valve in the intake passage, and “Ta” is an air temperature at a portion upstream of the throttle valve. , “Tm” is the intake pipe temperature, which is the temperature of the air downstream of the throttle valve, “NE” is the engine speed, and “mc” is the mass of air sucked into the cylinder. An intake air amount estimation device for an internal combustion engine that calculates an in-cylinder intake air amount using a relationship represented by the following mathematical expression when an air amount, “C” is a correction coefficient:

当該数式における「Ａ」に相当する圧力係数は、吸気管温度が低いときほど大きくなるように吸気管温度に基づいて可変設定される正の値であり、「Ｂ」に相当する回転係数は、吸気管温度が大気温度よりも低いときには負の値となる一方、吸気管温度が大気温度よりも高いときには正の値となるとともに、吸気管温度が高いときほど大きくなるように吸気管温度に基づいて可変設定される値であることをその要旨とする。

The pressure coefficient corresponding to “A” in the formula is a positive value variably set based on the intake pipe temperature so that the lower the intake pipe temperature is, the rotation coefficient corresponding to “B” is Based on the intake pipe temperature, a negative value is obtained when the intake pipe temperature is lower than the atmospheric temperature, a positive value is obtained when the intake pipe temperature is higher than the atmospheric temperature, and a higher value is obtained when the intake pipe temperature is higher. The gist is that the value is variably set.

  The air flowing through the intake passage exchanges heat with the wall surface of the intake passage before being sucked into the cylinder. For this reason, the density of air taken into the cylinder also changes due to a temperature change caused by this heat exchange. Here, when the engine speed is low, the flow velocity of the air flowing in the intake passage is slow, so that temperature change due to heat exchange is likely to occur, and the density of the air flowing in the intake passage is affected by the temperature of the wall surface of the intake passage. Change easily. On the other hand, when the engine speed is high, the flow rate of air flowing in the intake passage is high, so that temperature change due to heat exchange hardly occurs, and the density of air flowing in the intake passage is not easily affected by the temperature of the wall surface of the intake passage. .

  Further, when the intake pipe temperature, which is the temperature of air sucked into the cylinder, is lower than the atmospheric temperature, which is the temperature of air sucked into the intake passage, the air sucked into the cylinder through the intake passage is in the intake passage. Cooling by heat exchange reduces its density and improves the efficiency of filling the cylinder with air. On the other hand, when the intake pipe temperature is higher than the atmospheric temperature, the air sucked into the cylinder through the intake passage is warmed by heat exchange in the intake passage to increase its density, and the efficiency of filling the cylinder with air is reduced. .

  That is, when the intake pipe temperature is lower than the atmospheric temperature, the air in the intake passage is cooled and contracted by heat exchange as the engine rotational speed is lower, so that the charging efficiency is improved and the in-cylinder intake air amount is increased. . On the other hand, when the intake pipe temperature is higher than the atmospheric temperature, the higher the engine speed, the more the expansion of the air in the intake passage due to heat exchange is suppressed, so the reduction in charging efficiency is suppressed and the in-cylinder intake air amount Increase.

  In this regard, in the invention described in claim 2, the pressure coefficient is set based on the intake pipe temperature so that the pressure coefficient increases as the intake pipe temperature decreases as in the invention described in claim 1. In addition to variably setting, a rotation coefficient, which is a coefficient related to the engine rotation speed, is variably set based on the intake pipe temperature. The rotation coefficient is set to a negative value when the intake pipe temperature is lower than the atmospheric temperature, and is set to a positive value when the intake pipe temperature is higher than the atmospheric temperature. The value is made larger. According to such a configuration, when the intake pipe temperature is lower than the atmospheric temperature, the calculated cylinder intake air amount increases as the engine rotational speed is lower, while when the intake pipe temperature is higher than the atmospheric temperature, the engine rotation increases. The higher the speed, the greater the calculated cylinder intake air amount. That is, according to the second aspect of the invention, the influence of the intake pipe temperature on the in-cylinder intake air amount is taken into account, and further, the influence of the engine speed on the in-cylinder intake air amount is taken into account. The intake air amount can be calculated, and the in-cylinder intake air amount can be estimated more accurately over a wide temperature range from when the engine is cold to after completion of engine warm-up.

  According to a third aspect of the present invention, in the intake air amount estimating device for an internal combustion engine according to the first or second aspect, the pressure coefficient is “A” is the same pressure coefficient, and “Tm” is the intake pipe temperature. and when,

からなる数式に基づいて算出され、当該数式における「α」は負の値であり、且つ「β」は「Ｔｍ」の可変領域内において「Ａ」の値が常に正の値になるようにその大きさが設定されてなることをその要旨とする。

Where “α” is a negative value and “β” is a positive value so that the value of “A” is always positive in the variable region of “Tm”. The gist is that the size is set.

  To realize an intake air amount estimation device for an internal combustion engine capable of calculating the in-cylinder intake air amount in consideration of the influence of the intake pipe temperature as in the invention described in claim 1 or claim 2 As described above, it is desirable to employ a configuration in which the pressure coefficient is calculated so as to decrease as the intake pipe temperature increases in proportion to the intake pipe temperature. According to such a configuration, it becomes possible to calculate the intake air amount in the cylinder taking into account the influence of the intake pipe temperature by a relatively simple calculation, and without increasing the calculation load excessively, Thus, the in-cylinder intake air amount can be estimated over a wide temperature range from the completion of engine warm-up.

  According to a fourth aspect of the present invention, in the intake air amount estimating device for an internal combustion engine according to the second aspect, when the rotation coefficient is “B” as the rotation coefficient and “Tm” as the intake pipe temperature,

からなる数式に基づいて算出され、当該数式における「ε」は正の値であり、且つ「γ」は吸気管温度が大気温度と等しいときに「Ｂ」の値が「０」になるようにその大きさが設定されてなることをその要旨とする。

The “ε” in the equation is a positive value, and “γ” is such that the value of “B” becomes “0” when the intake pipe temperature is equal to the atmospheric temperature. The gist is that the size is set.

  Further, as in the invention described in claim 2, the intake air amount estimation device for an internal combustion engine capable of calculating the in-cylinder intake air amount in consideration of the influence of the engine rotational speed in addition to the influence of the intake pipe temperature. Specifically, as in the invention described in claim 4, when the intake pipe temperature is equal to the atmospheric temperature, it becomes “0”, and the intake pipe temperature is proportional to the intake pipe temperature. It is desirable to employ a configuration that calculates the rotation coefficient so that the rotation coefficient increases as the value increases. According to such a configuration, it becomes possible to calculate the in-cylinder intake air amount by taking into consideration the influence of the engine rotation speed and the intake pipe temperature by a relatively simple calculation, and without excessively increasing the calculation load, The in-cylinder intake air amount can be estimated over a wide temperature range from when the engine is cold to after completion of engine warm-up, and the calculation accuracy can be improved.

  According to a fifth aspect of the present invention, in the intake air amount estimation device for an internal combustion engine according to any one of the first to fourth aspects, a warm-up completion determination for determining whether or not the warm-up of the internal combustion engine has been completed. And determining that the warm-up completion determination means has not completed the warm-up of the internal combustion engine, the relationship between the intake pipe temperature and the intake pipe pressure and the in-cylinder intake air amount is obtained. While calculating the in-cylinder intake air amount using the relationship represented by the mathematical expression shown, if the warm-up completion determination means determines that the warm-up is complete, An intake air amount estimation device for an internal combustion engine that calculates an in-cylinder intake air amount using a relationship represented by:

当該数式における「ｃ」及び「ｄ」に相当する各係数は、当該数式を利用して算出される筒内吸入空気量の値が、暖機完了後の機関運転を想定して行われる実験において測定される実際の筒内吸入空気量に即した値となるように、予め行う前記実験の結果に基づいて設定されてなることをその要旨とする。

Each coefficient corresponding to “c” and “d” in the formula is calculated in an experiment in which the value of the in-cylinder intake air amount calculated using the formula is assumed to be the engine operation after the warm-up is completed. The gist of the invention is that it is set based on the result of the experiment conducted in advance so as to be a value corresponding to the actual in-cylinder intake air amount to be measured.

  According to the above configuration, after the warm-up is completed, the in-cylinder operation is performed using the relationship represented by the formula in which each coefficient is set based on the result of the experiment performed assuming the engine operation after the warm-up is completed. The intake air amount is calculated. On the other hand, when the engine is cold, in-cylinder intake air is utilized using the relationship represented by the mathematical expression shown in claim 1 or claim 2 in which each coefficient is variably set based on the intake pipe temperature. The amount will be calculated. Therefore, the in-cylinder intake air amount can be estimated in a wide temperature range from when the engine is cold to after completion of engine warm-up.

  Further, according to such a configuration, in the mathematical expression referred to after the completion of warming-up, each coefficient can be set in a manner specialized for engine operation after the completion of warming-up. Further, even in the mathematical expression referred to when the engine is cold, the setting mode of each coefficient variably set based on the intake pipe temperature can be specialized when the engine is cold. Therefore, according to such a configuration, the cylinder intake air amount is calculated using a mathematical expression in which each coefficient is always variably set from when the engine is cold to when the warm-up is completed. The calculation accuracy of the internal intake air amount can be improved.

  According to a sixth aspect of the present invention, in the intake air amount estimation device for the internal combustion engine according to the fifth aspect, when the correction coefficient is “C” and the “Tm” is the intake pipe temperature,

からなる数式に基づいて算出され、当該数式における「η」は負の値であり、且つ「ξ」は機関温度が前記実験の際に想定した機関温度から乖離しているときほど前記補正係数の絶対値が大きくなるようにその大きさが設定されてなることをその要旨とする。

Is calculated based on the mathematical formula, and “η” in the mathematical formula is a negative value, and “ξ” is the value of the correction coefficient as the engine temperature deviates from the engine temperature assumed in the experiment. The gist is that the magnitude is set so that the absolute value becomes large.

  As in the invention described in claim 6, the correction coefficient is calculated so that the absolute value of the correction coefficient increases as the engine temperature deviates from the engine temperature assumed in the experiment. Can also be adopted. According to such a configuration, the correction amount of the in-cylinder intake air amount increases as the engine temperature deviates from the engine temperature assumed in the experiment, and the deviation of the in-cylinder intake air amount due to the difference in engine temperature. Will be suppressed.

1 is a schematic diagram showing a schematic configuration of an internal combustion engine according to an embodiment of the present invention, and a relationship between the internal combustion engine and an electronic control unit that comprehensively controls the internal combustion engine. The block diagram which shows the calculation process of the cylinder intake air amount in the internal combustion engine concerning the embodiment. The flowchart which shows the flow of the process which selects the intake valve model used for calculation of the cylinder intake air amount. The flowchart which shows the flow of a calculation process of the in-cylinder intake air amount by a warm-up intake valve model. The flowchart which shows the flow of a calculation process of the in-cylinder intake air amount by a cold time intake valve model. The graph which shows the relationship between intake pipe temperature and a pressure coefficient. The graph which shows the relationship between intake pipe temperature and a rotation coefficient. The graph which shows the relationship between intake pipe temperature and a correction coefficient. The graph which shows the relationship between the pressure coefficient concerning the example of a change, and intake pipe temperature. The graph which shows the relationship between the rotation coefficient concerning the example of a change, and intake pipe temperature.

  Hereinafter, an embodiment in which an intake air amount estimation device for an internal combustion engine according to the present invention is embodied as an electronic control device that comprehensively controls an internal combustion engine mounted on a vehicle will be described with reference to FIGS. To do. FIG. 1 is a schematic diagram showing a schematic configuration of the internal combustion engine according to the present embodiment and a relationship between the internal combustion engine and the electronic control unit.

  As shown in FIG. 1, a piston 12 is slidably accommodated in a cylinder 11 of the internal combustion engine 10. Thus, a combustion chamber 14 is defined by the inner peripheral surface of the cylinder 11, the top surface of the piston 12, and the cylinder head 13. Although the internal combustion engine 10 is a multi-cylinder internal combustion engine having a plurality of cylinders 11, only one of the plurality of cylinders 11 is shown in FIG.

  The cylinder head 13 is provided with a spark plug 18 so as to face the piston 12 accommodated in each cylinder 11. An intake passage 20 and an exhaust passage 30 are connected to each combustion chamber 14, and a fuel injection valve 17 that injects fuel toward each combustion chamber 14 is provided for each cylinder 11 in the intake passage 20. Yes.

  As shown in FIG. 1, the cylinder head 13 is provided with an intake valve 15 for communicating / blocking the intake passage 20 and the combustion chamber 14 and an exhaust valve 16 for communicating / blocking the exhaust passage 30 and the combustion chamber 14. ing. The intake valve 15 is driven to open and close by an intake camshaft connected to a crankshaft (not shown) via a timing chain, and the exhaust valve 16 is driven to open and close by an exhaust camshaft connected to the crankshaft via a timing chain. .

  As shown on the left side of FIG. 1, an air cleaner 21 is provided at the most upstream portion of the intake passage 20. The air cleaner 21 is provided with a filter 22 that collects dust contained in the sucked air, and the air from which dust has been removed through the air cleaner 21 is sucked into the combustion chamber 14 through the intake passage 20. Yes.

  A surge tank 23 is provided in a portion of the intake passage 20 on the downstream side of the air cleaner 21. The surge tank 23 has a flow passage cross-sectional area that is set to be larger than other portions of the intake passage 20 and has a function of smoothing pulsation of air passing through the intake passage 20.

  Further, as shown in the center of FIG. 1, a throttle valve 25 whose opening degree is controlled by a motor 24 is provided at a portion downstream of the air cleaner 21 in the intake passage 20 and upstream of the surge tank 23. Is provided.

  The opening control of the throttle valve 25, the fuel injection amount control by the fuel injection valve 17, the ignition timing control by the spark plug 18, and the like are executed by the electronic control unit 100 that controls the internal combustion engine 10 in an integrated manner.

  The electronic control unit 100 includes a central processing unit (CPU) that executes various arithmetic processes related to engine control, an arithmetic control program and arithmetic map for engine control, a read-only memory (ROM) that stores various data, and results of arithmetic operations. Etc., a random access memory (RAM) or the like for temporarily storing them.

  As shown in FIG. 1, the following various sensors are connected to the electronic control device 100. The accelerator opening sensor 50 detects an accelerator operation amount Accp, which is an operation amount of the accelerator pedal by the driver. The air flow meter 51 detects the temperature Ta of the air introduced into the intake passage 20 through the air cleaner 21 and the intake air amount GA which is the amount thereof. An intake pressure sensor 52 provided in the surge tank 23 detects the pressure of air in the intake passage 20. An intake pipe temperature sensor 53 provided in the intake passage 20 in the vicinity of the combustion chamber 14 detects the temperature of air taken into the combustion chamber 14. The crank angle sensor 54 detects an engine rotational speed NE that is the rotational speed of the crankshaft of the internal combustion engine 10. The throttle opening sensor 55 detects the throttle opening θ that is the opening of the throttle valve 25. The water temperature sensor 56 detects the engine cooling water temperature THW. The cam angle sensor 57 detects the rotation angle of the intake camshaft.

The electronic control unit 100 comprehensively controls the internal combustion engine 10 based on output signals from these various sensors 50 to 57.
In the internal combustion engine 10 of the present embodiment, the intake valve 15 is closed so that appropriate fuel injection amount control can be realized even in a transient state immediately after the throttle opening θ is changed. When this is done, the mass Mc of the air that will be filled in the cylinder 11 is estimated in advance before the intake valve 15 is closed. Then, the fuel injection amount fc is set based on the estimated mass Mc, and an amount of fuel corresponding to the fuel injection amount fc is supplied into the cylinder 11 until the intake valve 15 in the intake stroke is closed. Like to do.

  In order to realize such fuel injection amount control, the electronic control unit 100 calculates the target throttle opening degree θr based on the accelerator operation amount Accp detected by the accelerator opening degree sensor 50 as shown in FIG. The target throttle opening degree θr is delayed by a predetermined delay time, for example, 64 milliseconds, and reflected in the opening degree control of the throttle valve 25. That is, the electronic control unit 100 feedback-controls the motor 24 with reference to the target throttle opening degree θr calculated based on the accelerator operation amount Accp 64 milliseconds ago, thereby controlling the throttle opening degree θ.

  Further, as shown in FIG. 2, the electronic control unit 100 calculates the predicted throttle opening θt through the electronic control throttle model M1 based on the accelerator operation amount Accp. As described above, the actual throttle opening degree θ is controlled in a state delayed by 64 milliseconds with respect to the change in the accelerator operation amount Accp. Therefore, the electronically controlled throttle model M1 can prefetch the change in the throttle opening θ by this delay time based on the accelerator operation amount Accp. Therefore, in the electronically controlled throttle model M1, the throttle opening θ after 64 milliseconds is calculated as the predicted throttle opening θt in consideration of the operation delay of the motor 24 and the like.

  Then, the electronic control unit 100 calculates the throttle passing air amount mt through the throttle model M2 based on the predicted throttle opening degree θt thus calculated through the electronic control throttle model M1.

  The throttle model M2 calculates the throttle passage air amount mt by using the relationship expressed by the following formula (1) or formula (2) as described in Patent Document 1.

尚、上記の数式（１）及び数式（２）における「Ｐａ」はスロットル弁２５よりも上流側の部位の圧力であり、「Ｔａ」はスロットル弁２５よりも上流側の部位の空気の温度である。このスロットルモデルＭ２にあっては、「Ｐａ」の値として大気圧を使用するとともに、「Ｔａ」としてエアフロメータ５１によって検出される吸入空気の温度Ｔａを使用する。

In the above formulas (1) and (2), “Pa” is the pressure in the upstream portion of the throttle valve 25, and “Ta” is the air temperature in the upstream portion of the throttle valve 25. is there. In the throttle model M2, the atmospheric pressure is used as the value of “Pa”, and the temperature Ta of the intake air detected by the air flow meter 51 is used as “Ta”.

  In the above formulas (1) and (2), “Ct (θt)” is a flow coefficient that changes according to the predicted throttle opening θt, and “At (θt)” changes according to the predicted throttle opening θt. Throttle opening area, “R” is a gas constant, and “κ” is a specific heat ratio.

  In the above formulas (1) and (2), “Pm” is the intake pipe pressure Pm, which is the pressure at the downstream side of the throttle valve 25, and “Tm” is on the downstream side of the throttle valve 25. This is the intake pipe temperature Tm, which is the temperature of the air at the site. In the throttle model M2, the intake pipe pressure Pm and the intake pipe temperature Tm calculated immediately before through the intake pipe model M3 described later are used as “Pm” and “Tm”.

  In the throttle model M2, the formula (1) is used when the atmospheric pressure Pa is a forward flow larger than the intake pipe pressure Pm, and the formula (1) is used when the atmospheric pressure Pa is a reverse flow smaller than the intake pipe pressure Pm. 2) is used.

  Next, the electronic control unit 100, based on the calculated throttle passage air amount mt, passes through the intake pipe model M3, the intake pipe pressure Pm, which is the pressure at the downstream side of the throttle valve 25, and the downstream side of the throttle valve 25. The intake pipe temperature Tm, which is the temperature of the air at the side portion, is calculated.

  Note that the intake pipe model M3 calculates the intake pipe pressure Pm and the intake pipe temperature Tm using the relationship expressed by the following formulas (3) and (4) as described in Patent Document 1. Is to be calculated.

尚、上記の数式（３）及び数式（４）における「Ｖｍ」は吸気通路２０におけるスロットル弁２５から吸気弁１５までの部分の容積である。

Note that “Vm” in the above formulas (3) and (4) is the volume of the portion from the throttle valve 25 to the intake valve 15 in the intake passage 20.

  In the intake pipe model M3, based on the throttle passage air amount mt calculated through the throttle model M2 and the in-cylinder intake air amount mc calculated immediately before through the intake valve model M4 described later, the above formula (3 And intake pipe pressure Pm and intake pipe temperature Tm are calculated using the relationship represented by (4) and (4).

  When the intake pipe pressure Pm and the intake pipe temperature Tm are thus calculated, the electronic control unit 100 is sucked into the cylinder 11 based on the intake pipe pressure Pm and the intake pipe temperature Tm through the intake valve model M4 as shown in FIG. The in-cylinder intake air amount mc, which is the mass of air, is calculated.

  The electronic control unit 100 of the present embodiment includes a cold-time intake valve model and a warm-up intake valve model as the intake valve model M4, and whether or not the internal combustion engine 10 has been warmed up. One of these is selected based on the above, and the cylinder intake air amount mc is calculated. The calculation process of the in-cylinder intake air amount will be described later with reference to FIGS.

  When the in-cylinder intake air amount mc is calculated through the intake valve model M4 in this way, the electronic control unit 100 determines the cylinder 11 until the intake valve 15 is closed in the intake stroke based on the calculated in-cylinder intake air amount mc. The mass Mc of the air filled in is estimated. That is, by integrating the in-cylinder intake air amount mc calculated so far, the mass Mc of the air charged in the cylinder 11 until the intake valve 15 is closed is calculated.

  The electronic control unit 100 sets the fuel injection amount fc based on the calculated mass Mc, drives the fuel injection valve 17 based on the set fuel injection amount fc, and closes the intake valve 15. An amount of fuel corresponding to the fuel injection amount fc set up to is supplied into the combustion chamber 14.

  In this way, the mass Mc, which is the mass of the air that is used for combustion before the intake valve 15 is closed, is estimated, and the fuel injection amount fc is set based on the estimated mass Mc. Even in a transient state, the fuel injection amount control corresponding to the amount of air provided for combustion can be performed, and an accurate engine operation can be realized.

  As described above, in the electronic control device 100 of the present embodiment, when calculating the in-cylinder intake air amount mc through the intake valve model M4, among the cold intake valve model and the warm-up intake valve model, Either one is selected and the in-cylinder intake air amount mc is calculated.

Hereinafter, calculation processing of the in-cylinder intake air amount mc according to the electronic control apparatus 100 of the present embodiment will be described in detail with reference to FIGS.
FIG. 3 is a flowchart showing a flow of processing for selecting an intake valve model used for calculating the in-cylinder intake air amount mc. This process is repeatedly executed at a predetermined control cycle by the electronic control unit 100 during engine operation.

  When this process is started, the electronic control unit 100 first determines whether or not the engine cooling water temperature THW is lower than the threshold value Tth in step S100 as shown in FIG. The threshold value Tth is set so that the warming-up of the internal combustion engine 10 can be determined based on the engine cooling water temperature THW being equal to or higher than the threshold value Tth.

  If it is determined in step S100 that the engine coolant temperature THW is lower than the threshold value Tth (step S100: YES), it is determined that the internal combustion engine 10 has not been warmed up, and the process proceeds to step S200. The electronic control unit 100 executes a calculation process of the in-cylinder intake air amount mc by the cold intake valve model.

  On the other hand, if it is determined in step S100 that the engine coolant temperature THW is equal to or higher than the threshold value Tth (step S100: NO), it is determined that the internal combustion engine has been warmed up, and the process proceeds to step S300. Then, the electronic control unit 100 executes a calculation process of the in-cylinder intake air amount mc by the intake valve model after warming up.

Then, when the in-cylinder intake air amount mc is calculated through the calculation process of step S200 or step S300, the electronic control unit 100 once ends this process.
Hereinafter, the calculation processing of the in-cylinder intake air amount mc by the post-warm-up intake valve model in step S300 will be described with reference to FIG. FIG. 4 is a flowchart showing the flow of the calculation process of the in-cylinder intake air amount mc by the warm-up intake valve model.

  When this calculation process is started, as shown in FIG. 4, the electronic control unit 100 first reads the intake pipe pressure Pm and the intake pipe temperature Tm calculated through the intake pipe model M3 in step S310.

  Then, the process proceeds to step S320, and the in-cylinder intake air amount mc is calculated based on the intake pipe pressure Pm and the intake pipe temperature Tm using the relationship expressed by the following formula (5).

尚、この数式（５）における「Ｔａ」はエアフロメータ５１によって検出される温度Ｔａである。この数式（５）は、特許文献１に記載されているように従来から筒内吸入空気量ｍｃの算出に利用されている数式と同様のものである。

In this equation (5), “Ta” is the temperature Ta detected by the air flow meter 51. This mathematical formula (5) is the same as the mathematical formula conventionally used for calculating the in-cylinder intake air amount mc, as described in Patent Document 1.

  The coefficients c and d in this equation (5) are based on the results of experiments performed under conditions assuming engine operation after completion of warm-up (for example, engine temperature 80 ° C.). The in-cylinder intake air amount mc calculated using 5) is set empirically so that it matches the actual in-cylinder intake air amount.

In step S320, when the in-cylinder intake air amount mc is calculated based on the intake pipe pressure Pm and the intake pipe temperature Tm, the electronic control unit 100 ends this calculation process.
Next, the contents of the calculation processing of the cylinder intake air amount mc by the cold intake valve model in step S200 will be described in detail with reference to FIGS. FIG. 5 is a flowchart showing the flow of processing for calculating the in-cylinder intake air amount mc using the cold intake valve model.

  When this calculation process is started, as shown in FIG. 5, the electronic control unit 100 first reads in the intake pipe pressure Pm and the intake pipe temperature Tm calculated through the intake pipe model M3 in step S210, and at the same time the engine speed NE. Is read.

In step S220, the pressure coefficient A, the rotation coefficient B, and the correction coefficient C are calculated based on the intake pipe temperature Tm.
Specifically, the pressure coefficient A is calculated based on the following mathematical formula (6).

尚、この数式（６）における傾きαは負の値である。また数式（６）における切片βは、正の値であり、且つ図６に示されるように吸気管温度Ｔｍが取り得る温度領域において圧力係数Ａの値が常に正の値になるようにその大きさが設定されている。

Note that the slope α in the equation (6) is a negative value. In addition, the intercept β in the equation (6) is a positive value, and as shown in FIG. Is set.

As a result, the pressure coefficient A calculated here becomes smaller as the intake pipe temperature Tm is higher in proportion to the intake pipe temperature Tm as shown in FIG. 6, and is always a positive value.
The rotation coefficient B is calculated based on the following mathematical formula (7).

尚、この数式（７）における傾きεは正の値である。また数式（７）における切片γは負の値であり、且つ吸気管温度Ｔｍが大気温度と略等しいときに回転係数Ｂが「０」になるようにその大きさが設定されている。ここでは、大気温度を２５℃と想定し、図７に示されるように吸気管温度Ｔｍが２５℃のときに回転係数Ｂが「０」になるように切片γの大きさを設定している。

Note that the slope ε in the equation (7) is a positive value. In addition, the intercept γ in Equation (7) is a negative value, and the magnitude is set so that the rotation coefficient B becomes “0” when the intake pipe temperature Tm is substantially equal to the atmospheric temperature. Here, assuming that the atmospheric temperature is 25 ° C., the magnitude of the intercept γ is set so that the rotation coefficient B becomes “0” when the intake pipe temperature Tm is 25 ° C. as shown in FIG. .

  Thereby, the rotation coefficient B calculated here becomes larger as the intake pipe temperature Tm is higher in proportion to the intake pipe temperature Tm as shown in FIG. 7, and the intake pipe temperature Tm is higher than 25 ° C. On the other hand, it becomes a positive value, while it becomes a negative value when the intake pipe temperature Tm is less than 25 ° C.

  The correction coefficient C is calculated based on the following formula (8).

尚、この数式（８）における傾きηは負の値である。また数式（８）における切片ξは正の値であり、且つ図８に示されるように吸気管温度Ｔｍが６０℃のときに補正係数Ｃが「０」になるようにその大きさが設定されている。

Note that the slope η in the equation (8) is a negative value. In addition, the intercept ξ in the formula (8) is a positive value, and the magnitude is set so that the correction coefficient C becomes “0” when the intake pipe temperature Tm is 60 ° C. as shown in FIG. ing.

  In this way, the magnitude of the intercept ξ is set so that the correction coefficient C becomes “0” when the intake pipe temperature Tm is 60 ° C., assuming that the engine temperature is the engine operation after completion of the warm-up described above. This is because the intake pipe temperature Tm is about 60 ° C. when the engine temperature (for example, 80 ° C.) is assumed in the experiment conducted. That is, here, the magnitude of the intercept ξ is set so that the correction coefficient C becomes “0” when it is estimated that the engine temperature is the engine temperature assumed in the above experiment.

  As a result, the correction coefficient C calculated here becomes smaller as the intake pipe temperature Tm becomes higher than 60 ° C., as shown in FIG. 8, whereas the correction coefficient C becomes smaller as the intake pipe temperature Tm becomes lower than 60 ° C. As the value increases, the engine temperature deviates from the engine temperature (80 ° C.) assumed in the above experiment, and the absolute value increases as the intake pipe temperature Tm deviates from 60 ° C.

When the coefficients A, B, and C are thus calculated based on the intake pipe temperature Tm in step S220, the process proceeds to step S230.
Then, the calculated pressure coefficient A, rotation coefficient B, and correction coefficient C are substituted into the following equation (9) of the cold-time intake valve model, and the intake pipe is utilized using the relationship shown in the equation (9). The in-cylinder intake air amount mc is calculated based on the pressure Pm, the intake pipe temperature Tm, and the engine speed NE.

尚、この数式（９）における「Ｔａ」はエアフロメータ５１によって検出される空気の温度Ｔａである。

In this equation (9), “Ta” is the air temperature Ta detected by the air flow meter 51.

In this way, when the in-cylinder intake air amount mc is calculated in step S230, the electronic control unit 100 ends this calculation process.
As described above, in the electronic control apparatus 100 according to the present embodiment, it is determined whether the warm-up of the internal combustion engine 10 is completed based on the engine coolant temperature THW, and the in-cylinder intake air amount mc is determined according to the result. The formula of the intake valve model used when calculating is switched.

  When the engine is cold, the coefficients A, B, and C in the equation (9) of the cold intake valve model are variably set based on the intake pipe temperature Tm, and the equation ( The in-cylinder intake air amount mc is calculated using the relationship expressed in 9).

According to the embodiment described above, the following functions and effects can be obtained.
(1) The higher the intake pipe pressure Pm, the larger the pressure difference between the air pressure in the intake passage 20 and the negative pressure generated in the cylinder 11, and the amount (volume) of air sucked into the cylinder 11 becomes larger. Increase. At this time, when the intake pipe temperature Tm is low, the density of the air in the intake passage 20 is high. Therefore, the mass of air sucked into the cylinder 11, that is, in-cylinder intake, is higher than when the intake pipe temperature Tm is high. The air amount mc increases. On the other hand, when the intake pipe temperature Tm is high, the density of the air in the intake passage 20 is low, so that the in-cylinder intake air amount mc is reduced compared to when the intake pipe temperature Tm is low. That is, the degree of increase / decrease in the in-cylinder intake air amount mc with respect to the change in the intake pipe pressure Pm varies according to the intake pipe temperature Tm. The degree of increase / decrease in the air amount mc increases.

  In the electronic control apparatus 100 of the above embodiment, the pressure coefficient A is variably set based on the intake pipe temperature Tm so that the pressure coefficient A increases as the intake pipe temperature Tm decreases when the engine is cold. Yes. Therefore, it is possible to appropriately calculate the in-cylinder intake air amount mc in a manner corresponding to the change in the degree of increase / decrease of the in-cylinder intake air amount mc relative to the intake pipe pressure Pm according to the intake pipe temperature Tm. .

  That is, even when the engine temperature is low and the intake pipe temperature Tm is particularly low and the engine is cold, the in-cylinder intake air amount mc can be estimated appropriately. It is possible to suppress the deviation of the cylinder intake air amount mc over a wide temperature range, and to realize an accurate engine operation based on the cylinder intake air amount mc.

  (2) The air flowing through the intake passage 20 exchanges heat with the wall surface of the intake passage 20 before being sucked into the cylinder 11. Therefore, the density of the air taken into the cylinder 11 also changes due to the temperature change caused by this heat exchange. Here, when the engine rotational speed NE is low, the flow rate of air flowing through the intake passage 20 is slow, so that a temperature change is likely to occur due to heat exchange, and the density of the air flowing through the intake passage 20 is the temperature of the wall surface of the intake passage 20. It becomes easy to change under the influence of. On the other hand, when the engine rotational speed NE is high, the flow rate of air flowing through the intake passage 20 is fast, so that a temperature change due to heat exchange hardly occurs, and the density of the air flowing through the intake passage 20 is the temperature of the wall surface of the intake passage 20. Not easily affected.

  Further, when the intake pipe temperature Tm, which is the temperature of the air sucked into the cylinder 11, is lower than the atmospheric temperature Ta, which is the temperature of the air sucked into the intake passage 20, it is sucked into the cylinder 11 through the intake passage 20. The air is cooled by heat exchange in the intake passage 20 to reduce its density, and the efficiency of filling the cylinder 11 with air is improved. On the other hand, when the intake pipe temperature Tm is higher than the atmospheric temperature Ta, the air sucked into the cylinder 11 through the intake passage 20 is warmed by heat exchange in the intake passage 20 to increase its density, and the air to the cylinder 11 is increased. The filling efficiency is reduced.

  That is, when the intake pipe temperature Tm is lower than the atmospheric temperature Ta, the air in the intake passage 20 is cooled and contracted by heat exchange as the engine rotational speed NE is lower, so that the charging efficiency is improved and the cylinder intake air The amount mc increases. On the other hand, when the intake pipe temperature Tm is higher than the atmospheric temperature Ta, the higher the engine rotational speed NE is, the more the expansion of air in the intake passage 20 due to heat exchange is suppressed. The intake air amount mc increases.

  In this regard, in the electronic control device 100 of the above embodiment, when the engine is cold, the rotation coefficient B, which is a coefficient applied to the engine rotation speed NE, is variably set according to the intake pipe temperature Tm. The rotation coefficient B is set to a negative value when the intake pipe temperature Tm is lower than 25 ° C. assumed as the atmospheric temperature, and is set to a positive value when the intake pipe temperature Tm is higher than 25 ° C. The higher the intake pipe temperature Tm, the higher the value. Therefore, when the intake pipe temperature Tm is lower than 25 ° C., the value of the cylinder intake air amount mc calculated as the engine rotational speed NE is lower increases. On the other hand, when the intake pipe temperature Tm is higher than 25 ° C., the engine speed increases. The higher the speed NE, the larger the value of the cylinder intake air amount mc calculated. That is, in the electronic control apparatus 100 of the above embodiment, the influence of the intake pipe temperature Tm on the in-cylinder intake air amount mc is taken into account, and further, the influence of the engine speed NE on the in-cylinder intake air amount mc is taken into account. In addition, the in-cylinder intake air amount mc can be calculated.

  (3) By calculating the pressure coefficient A based on the formula (6), the pressure coefficient A is proportional to the intake pipe temperature Tm, and becomes smaller as the intake pipe temperature Tm is higher. Therefore, the in-cylinder intake air amount mc can be calculated by taking into account the influence of the intake pipe temperature Tm as described above by relatively simple calculation, and without increasing the calculation load of the electronic control unit 100 excessively. The in-cylinder intake air amount mc can be accurately estimated over a wide temperature range from when the engine is cold to after completion of engine warm-up.

  (4) By calculating the rotation coefficient B based on the equation (7), the rotation coefficient B becomes “0” when the intake pipe temperature Tm is 25 ° C., and the intake air is proportional to the intake pipe temperature Tm. The higher the tube temperature Tm, the higher the temperature. Therefore, the in-cylinder intake air amount mc can be calculated by taking into account the influence of the engine speed NE and the intake pipe temperature Tm as described above by relatively simple calculation, and the calculation load of the electronic control unit 100 is excessively increased. Without increasing, the in-cylinder intake air amount mc can be estimated with high accuracy over a wide temperature range from when the engine is cold to after completion of engine warm-up.

  (5) After the warm-up is completed, the in-cylinder intake air amount mc is calculated using the relationship expressed by Equation (5), while the coefficients A, B, and B are calculated based on the intake pipe temperature Tm when the engine is cold. The in-cylinder intake air amount mc is calculated using the relationship expressed by Equation (9) in which C is variably set. Therefore, in Equation (5) referred to after completion of warm-up, the coefficients c and d are set in accordance with engine operation after completion of warm-up, and Equation (9) referred to when the engine is cold. In this case, the setting modes of the coefficients A, B, and C can be specialized when the engine is cold. As a result, the calculation accuracy of the in-cylinder intake air amount mc is improved as compared with the case where the in-cylinder intake air amount mc is always calculated using Equation (9) from when the engine is cold to after completion of warm-up. be able to.

  (6) By calculating the correction coefficient C with reference to Equation (8), the value of the correction coefficient C decreases as the intake pipe temperature Tm becomes higher than 60 ° C., while the intake pipe temperature Tm becomes 60 ° C. The absolute value increases as the intake pipe temperature Tm deviates from 60 ° C. Therefore, when the engine temperature deviates from the engine temperature (80 ° C.) assumed in the experiment conducted assuming the engine operation after completion of warm-up, and the intake pipe temperature Tm deviates from 60 ° C., The correction amount of the cylinder intake air amount mc increases. That is, the larger the deviation from the engine temperature assumed in the experiment, the larger the correction amount, and the deviation of the cylinder intake air amount mc due to the deviation from the assumed engine temperature is suitably suppressed.

In addition, the said embodiment can also be implemented with the following forms which changed this suitably.
In the above embodiment, as the warm-up completion determination means, a configuration is adopted in which it is determined whether or not the engine cooling water temperature THW is lower than the threshold value Tth, and the engine cooling water temperature THW is not lower than the threshold value Tth. It is determined that the warm-up has been completed when it is determined that is equal to or greater than the threshold value Tth. On the other hand, the configuration of the warm-up completion determination unit can be changed as appropriate. For example, it is possible to employ a configuration in which a temperature sensor that directly detects the engine temperature is provided, and it is determined that the warm-up is completed based on the temperature detected by the temperature sensor being equal to or higher than a threshold value.

  In the above embodiment, assuming that the atmospheric temperature is 25 ° C., the magnitude of the intercept γ in Equation (7) is such that the rotation coefficient B is “0” when the intake pipe temperature Tm is 25 ° C. The configuration to be set in is exemplified. On the other hand, the magnitude of the intercept γ is not limited to such a magnitude that the rotation coefficient B is “0” when the intake pipe temperature Tm is 25 ° C., but can be changed as appropriate. However, the magnitude of the intercept γ needs to be set so that the rotation coefficient B becomes “0” when the intake pipe temperature Tm is substantially equal to the atmospheric temperature. It is desirable to set the rotation coefficient B to “0” when the temperature Tm is in the range of about 25 ± 5 ° C.

  In the above-described embodiment, the configuration in which the magnitude of the intercept ξ in Equation (8) is set so that the correction coefficient C becomes “0” when the intake pipe temperature Tm is 60 ° C. On the other hand, the magnitude of the intercept ξ is such that the correction coefficient C is set to “0” when the engine temperature is equal to the engine temperature assumed in an experiment performed assuming engine operation after completion of warm-up. It is only necessary to be set so that it can be changed as appropriate.

  In the above embodiment, the coefficients A, B, and C are variably set based on the intake pipe temperature Tm when it is determined that the warm-up is not completed as described with reference to FIG. A configuration is shown in which the in-cylinder intake air amount mc is calculated using Equation (9) of the cold intake valve model.

  On the other hand, the process for determining whether or not the warm-up has been completed is omitted, and the coefficients A, B, and C are always variable based on the intake pipe temperature Tm from when the engine is cold to after the warm-up is completed. A configuration in which the in-cylinder intake air amount mc is calculated using the set numerical formula (9) may be employed.

  -Although a term relating to the engine rotational speed NE is provided in the mathematical formula (9) and the influence of the intake pipe temperature Tm and the influence of the engine rotational speed NE are taken into account, the in-cylinder intake air amount mc is calculated. A configuration is adopted in which the term relating to the engine rotational speed NE is omitted, and the in-cylinder intake air amount mc is calculated in consideration of only the influence of the intake pipe temperature Tm using the relationship expressed by the following formula (10). You can also.

・各係数Ａ，Ｂ，Ｃは吸気管温度Ｔｍに比例して直線状に変化するものでなくてもよい。

Each coefficient A, B, C does not have to change linearly in proportion to the intake pipe temperature Tm.

  For example, the pressure coefficient A may be variably set according to the intake pipe temperature Tm so as to increase as the intake pipe temperature Tm is low, and may always take a positive value. For example, as shown in FIG. The pressure coefficient A may be set based on the intake pipe temperature Tm with reference to the calculation map.

  The rotation coefficient B becomes a negative value when the intake pipe temperature Tm is lower than the atmospheric temperature, and becomes a positive value when the intake pipe temperature Tm is higher than the atmospheric temperature, and as the intake pipe temperature Tm is higher. What is necessary is just to variably set based on the intake pipe temperature Tm so that it may become large. Therefore, for example, as shown in FIG. 10, a mathematical formula for calculating the rotation coefficient B when the intake pipe temperature Tm is higher than the atmospheric temperature (here, 25 ° C.) and when the intake pipe temperature Tm is lower than the atmospheric temperature. It is also possible to vary the magnitude of the inclination at.

  That is, the intake pipe temperature having a correlation with the engine temperature so that the in-cylinder intake air amount mc can be calculated in a manner in accordance with a change mode of the in-cylinder intake air amount mc that changes at least according to a change in the engine temperature. It is only necessary that the coefficients A, B, and C can be variably set according to Tm.

DESCRIPTION OF SYMBOLS 10 ... Internal combustion engine, 11 ... Cylinder, 12 ... Piston, 13 ... Cylinder head, 14 ... Combustion chamber, 15 ... Intake valve, 16 ... Exhaust valve, 17 ... Fuel injection valve, 18 ... Spark plug, 20 ... Intake passage, 21 DESCRIPTION OF SYMBOLS ... Air cleaner, 22 ... Filter, 23 ... Surge tank, 24 ... Motor, 25 ... Throttle valve, 30 ... Exhaust passage, 50 ... Accelerator opening sensor, 51 ... Air flow meter, 52 ... Intake pressure sensor, 53 ... Intake pipe temperature sensor 54 ... Crank angle sensor, 55 ... Throttle opening sensor, 56 ... Water temperature sensor, 57 ... Cam angle sensor, 100 ... Electronic control unit.

Claims (6)

“Pm” is the intake pipe pressure, which is the pressure in the downstream side of the throttle valve in the intake passage, “Ta” is the air temperature in the upstream side of the throttle valve, and “Tm” is higher than the throttle valve. When the intake pipe temperature, which is the temperature of the air in the downstream portion, “mc” is the in-cylinder intake air amount, which is the mass of air sucked into the cylinder, and “C” is the correction coefficient, the following equation is used. An intake air amount estimation device for an internal combustion engine that calculates an in-cylinder intake air amount using the relationship

The pressure coefficient corresponding to “A” in the equation is a positive value variably set based on the intake pipe temperature so that the pressure coefficient increases as the intake pipe temperature is lower. Estimating device. “Pm” is the intake pipe negative pressure which is the pressure in the downstream side of the throttle valve in the intake passage, “Ta” is the temperature of the air in the upstream side of the throttle valve, and “Tm” is from the throttle valve Also, the intake pipe temperature that is the temperature of the air in the downstream part, “NE” is the engine speed, “mc” is the in-cylinder intake air amount that is the mass of air sucked into the cylinder, and “C” is the correction coefficient An intake air amount estimation device for an internal combustion engine that calculates an in-cylinder intake air amount using a relationship represented by the following mathematical formula,

The pressure coefficient corresponding to “A” in the formula is a positive value variably set based on the intake pipe temperature so that the lower the intake pipe temperature is, the rotation coefficient corresponding to “B” is Based on the intake pipe temperature, a negative value is obtained when the intake pipe temperature is lower than the atmospheric temperature, a positive value is obtained when the intake pipe temperature is higher than the atmospheric temperature, and a higher value is obtained when the intake pipe temperature is higher. An intake air amount estimation device for an internal combustion engine, characterized in that the value is variably set. The intake air amount estimation device for an internal combustion engine according to claim 1 or 2,
The pressure coefficient is “A” as the same pressure coefficient and “Tm” as the intake pipe temperature.

Calculated based on a mathematical formula consisting of
In the formula, “α” is a negative value, and “β” is set so that the value of “A” is always a positive value in the variable region of “Tm”. An intake air amount estimation device for an internal combustion engine characterized by the above. The intake air amount estimation device for an internal combustion engine according to claim 2,
The rotation coefficient is “B” when the rotation coefficient is the same and “Tm” is the intake pipe temperature.

Calculated based on a mathematical formula consisting of
“Ε” in the equation is a positive value, and “γ” is set so that the value of “B” becomes “0” when the intake pipe temperature is equal to the atmospheric temperature. An intake air amount estimation device for an internal combustion engine characterized by the above. In the intake air amount estimation device for an internal combustion engine according to any one of claims 1 to 4,
A warm-up completion determination unit that determines whether or not the warm-up of the internal combustion engine has been completed;
When it is determined by the warm-up completion determining means that the warm-up of the internal combustion engine has not been completed, the mathematical expression indicating the relationship between the intake pipe temperature and the intake pipe pressure and the in-cylinder intake air amount While calculating the in-cylinder intake air amount using the relationship represented,
When the warm-up completion determination unit determines that the warm-up is completed, the intake air amount of the internal combustion engine that calculates the in-cylinder intake air amount using the relationship represented by the following mathematical formula An estimation device,

Each coefficient corresponding to “c” and “d” in the formula is calculated in an experiment in which the value of the in-cylinder intake air amount calculated using the formula is assumed to be the engine operation after the warm-up is completed. An intake air amount estimation device for an internal combustion engine, which is set based on a result of the experiment conducted in advance so as to be a value in accordance with an actual in-cylinder intake air amount to be measured. The intake air amount estimation device for an internal combustion engine according to claim 5,
When the correction coefficient is “C”, and “Tm” is the intake pipe temperature,

Calculated based on a mathematical formula consisting of
“Η” in the formula is a negative value, and “ξ” is so large that the absolute value of the correction coefficient increases as the engine temperature deviates from the engine temperature assumed in the experiment. An intake air amount estimation device for an internal combustion engine, wherein

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