JP4737191B2 - Intake passage volume calculation device - Google Patents

Description

  The present invention relates to an intake passage volume calculating device for calculating an intake passage volume, particularly an intake passage volume downstream of a throttle valve.

  In order to accurately set the air-fuel ratio of the air-fuel mixture to the target air-fuel ratio, it is necessary to accurately grasp the amount of air supplied into the cylinder of the internal combustion engine (hereinafter referred to as “cylinder charged air amount”). is there. Usually, the cylinder air charge amount is estimated from a large number of sensors such as an air flow meter and a large number of maps using output values from these sensors as arguments. However, when estimating the cylinder air charge amount using the map in this way, in order to make the estimated value of the cylinder air charge more accurate, the number of necessary maps and the number of arguments thereof are required. This increases the man-hours for conforming work.

  Therefore, in recent years, it has been proposed to calculate the cylinder air charge amount by numerical calculation using various models without using a map. In this way, the number of necessary maps can be reduced by using a lot of numerical calculations, which makes it possible to accurately calculate the in-cylinder charged air amount while greatly reducing the number of man-hours required for performing the fitting work. .

  One such model is a model that calculates the amount of air charged in the cylinder based on the flow rate of air passing through the throttle, the pressure in the intake pipe, and the temperature in the intake pipe (for example, Patent Document 1). In calculating the cylinder air charge amount, the intake passage on the downstream side of the throttle valve, that is, the volume of the intake branch pipe, the surge tank, the intake pipe, and the like from the throttle valve to the intake valve is used as a constant.

JP 2005-90437 A JP 2005-248943 A JP 2006-22676 A

  Incidentally, in the model disclosed in Patent Document 1, the volume of the intake passage on the downstream side of the throttle valve is used as a constant. However, the volume of the intake passage used in this model equation does not necessarily match the actual volume of the intake passage. Therefore, it is difficult to precisely determine the volume of the intake passage effective in the above model. In addition, the actual intake passage volume itself may change over time due to product-to-product variations, thermal expansion of the pipes that define the intake passage, and deposit accumulation in the intake port in the case of intake port fuel injection. There is. For this reason, an error may occur in the volume of the intake passage used in the model.

  Accordingly, an object of the present invention is to provide an intake passage volume calculating device capable of accurately calculating the volume of the intake passage on the downstream side of the throttle valve.

In order to solve the above-mentioned problem, in the first invention, in the intake passage volume calculating device for calculating the volume of the intake passage on the downstream side of the throttle valve of the internal combustion engine having the intake valve electromagnetic drive device for driving the intake valve, The volume of the intake passage is calculated based on the pressure change rate in the intake passage on the downstream side of the valve, the flow rate of air passing through the throttle valve, and the total value of the voltage or current applied to the intake valve electromagnetic drive devices of all cylinders.
According to the first aspect of the invention, the volume of the intake passage on the downstream side of the throttle valve is calculated based on the total value of the voltage or current applied to the intake valve electromagnetic drive devices for all cylinders. Since the total value of the voltage or current applied to the intake valve electromagnetic drive system for all cylinders is proportional to the in-cylinder intake air flow rate into all cylinders, the volume of the intake passage on the downstream side of the throttle valve can be reduced by considering this proportional relationship. It can be calculated accurately.

  In the second invention, in the first invention, a relational expression among the pressure change rate of the intake passage on the downstream side of the throttle valve, the volume of the intake passage, the air flow rate through the throttle valve, and the in-cylinder intake air flow rate is used. The in-cylinder intake air flow rate into all the cylinders calculated using the above relational expression when the total value of the voltage or current applied to the cylinder intake valve electromagnetic drive device becomes the first total value, and the total value is the above The ratio of the in-cylinder intake air flow rate into all the cylinders calculated using the above relational expression when the second total value is different from the first total value is the first total value and the second total value. And the volume of the intake passage downstream of the throttle valve is calculated.

  In a third invention, in the second invention, the first total value is a maximum value of a voltage or a current applied to the intake valve electromagnetic drive device during opening of the intake valve of the specific cylinder, and the second total value is This is the minimum value of the voltage or current applied to the intake valve electromagnetic drive device during the opening of the intake valve of the specific cylinder.

In the fourth invention, the in second or third invention, the volume of the intake passage of Vm throttle valve downstream side, Ra the gas constant, the temperature of the intake passage of the Tm, the first sum value V _l, second sum value V _h above, the pressure change rate and the throttle passage of the intake passage when the sum of the voltage or current is added .DELTA.Pm _l and mt _l to the intake valve electromagnetically driven device for all the cylinders becomes the first sum Assuming that the air flow rate, ΔPm _h, and m th _h are the rate of change in pressure in the intake passage and the air flow rate through the throttle when the total value of the voltage or current applied to the intake valve electromagnetic drive devices of all cylinders becomes the second total value, The volume of the intake pipe portion is calculated by the following equation (2).

  According to the present invention, the volume of the intake passage downstream of the throttle valve can be accurately calculated.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The engine body 1 schematically shown in FIG. 1 represents a direct injection spark ignition type internal combustion engine. However, the present invention may be applied to another spark ignition internal combustion engine or a compression self-ignition internal combustion engine.

  As shown in FIG. 1, in the embodiment of the present invention, 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. The intake valve 6 is coupled to a drive device 12 that drives the intake valve 6 electromagnetically without using a cam or the like.

  The intake port 7 of each cylinder is connected to a surge tank 14 via an intake branch pipe 13, and the surge tank 14 is connected to an air cleaner 16 via an intake pipe 15. A throttle valve 18 driven by a step motor 17 is disposed in the intake pipe 15. An air flow meter 19 for detecting the flow rate of air (intake gas) passing through the intake pipe 15 is disposed in the intake pipe 15 upstream of the throttle valve 18. On the other hand, the exhaust port 9 of each cylinder is connected to an exhaust pipe 20, and the exhaust pipe 20 is connected to an exhaust purification device 21. In the following description, the intake passage on the downstream side of the throttle valve, that is, the intake branch pipe 13 from the throttle valve 18 to the intake valve 6, the surge tank 14, the intake pipe 16, and the like are referred to as an intake pipe portion 22.

  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 surge tank 14 is provided with an intake pipe pressure sensor 40 for detecting the pressure of air (intake gas) in the intake pipe and an intake pipe temperature sensor 41 for detecting the temperature of the air in the intake pipe. The intake pipe internal pressure sensor 40 and the intake pipe internal temperature sensor 41 generate output voltages proportional to the intake pipe internal pressure and the intake pipe internal temperature, and these output voltages are input to the input port 36 via the corresponding AD converters 38.

  In addition, a throttle opening sensor 42 for detecting the opening of the throttle valve 18 and an ambient temperature for detecting the ambient air temperature around the internal combustion engine or the temperature of the air taken into the intake pipe 15 (intake air temperature). A sensor 43 and an atmospheric pressure sensor 44 for detecting the atmospheric pressure around the internal combustion engine or the pressure of the air sucked into the intake pipe 15 (intake pressure) are provided, and the output voltage of these sensors corresponds to the corresponding AD. The signal is input to the input port 36 via the converter 38. A load sensor 46 that generates an output voltage proportional to the amount of depression of the accelerator pedal 45 is connected to the accelerator pedal 45, and the output voltage of the load sensor 46 is input to the input port 36 via the corresponding AD converter 38. The For example, the crank angle sensor 47 generates an output pulse every time the crankshaft rotates 30 degrees, and this 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 47. On the other hand, the output port 37 is connected to the spark plug 10, the fuel injection valve 11, the intake valve electromagnetic drive device 12, and the step motor 17 via a corresponding drive circuit 39.

  By the way, in order to set the air-fuel ratio of the air-fuel mixture combusted in the combustion chamber 5 of the internal combustion engine to the target air-fuel ratio, the amount of air (intake gas) filled in the combustion chamber 5 when the intake valve is closed. (Hereinafter referred to as “cylinder charge air amount Mc”), and based on the estimated cylinder charge air amount Mc, the fuel injection valve controls the internal combustion engine so that the air-fuel ratio of the mixture becomes the target air-fuel ratio. The amount of fuel injected into the combustion chamber 5 (or intake passage) (hereinafter referred to as “fuel injection amount”) is determined. Therefore, in order to accurately set the air-fuel ratio of the air-fuel mixture combusted in the combustion chamber 5 of the internal combustion engine to the target air-fuel ratio, it is necessary to accurately estimate the cylinder charge air amount Mc.

  Usually, the in-cylinder charged air amount Mc is estimated from a large number of sensors such as a flow rate sensor (air flow meter) and a large number of maps using output values from these sensors as arguments. However, if a map is used in this way, the ROM of the ECU for storing the map must have a large storage capacity, which increases the manufacturing cost of the internal combustion engine. Further, when the number of maps and the number of arguments thereof are increased, the number of man-hours for fitting work increases.

  Therefore, in some internal combustion engines, the in-cylinder charged air amount Mc is calculated by numerical calculation using various numerical calculation models without using a map. In such an internal combustion engine, the number of necessary maps is reduced as much as possible by using a lot of numerical calculations. This greatly reduces the number of man-hours for performing the fitting work, but also the in-cylinder charged air amount Mc Can be calculated accurately. An example of such a model is an in-cylinder charged air amount model M10 described later.

  By the way, in the numerical calculation model as described above, the volume Vm of the intake pipe portion 22 is used as a constant. However, the volume Vm of the intake pipe portion 22 used in this model does not necessarily match the actual volume of the intake pipe portion 22, and the volume Vm of the intake pipe portion 22 effective in the model is strictly determined from the design value or the like. It is difficult. In addition, the actual volume of the intake pipe portion 22 itself may change over time due to variations among products, thermal expansion of the intake pipe portion 22, accumulation of deposits in the intake port in the case of intake port fuel injection, and the like. . For this reason, if the volume Vm of the intake pipe portion 22 is used as a constant in the numerical calculation model, an error may occur in the volume Vm of the intake pipe portion 22.

  Therefore, in the intake passage volume calculating device according to the embodiment of the present invention, the volume Vm of the intake pipe portion 22 effective when used in a model formula or the like is accurately calculated. A method of calculating the volume Vm of will be described.

ここで、Ｔｍは吸気管部分２２内に存在する空気の温度（以下、「吸気管内温度」と称す）、Ｖｍは吸気管部分２２の容積、Ｒａは気体定数を空気の平均分子量で除算した値である。また、ｍｃｉはｉ番気筒への筒内吸入空気流量であり、よってΣｍｃｉは或る特定の時刻における全気筒への筒内吸入空気流量ｍｃを意味する。 FIG. 2 shows a basic concept of a model in the intake pipe portion 22. In the model shown in FIG. 2, when the gas state equation is applied to the intake pipe portion 22, the intake pipe pressure Pm (or the time change rate of the intake pipe pressure) and the flow rate of air flowing into the intake pipe portion 22 (that is, The relationship of the following formula (3) is established between the throttle passage air flow rate mt) and the flow rate of the intake gas flowing out from the intake pipe portion 22 (that is, the in-cylinder intake air flow rate mc to all cylinders).

Here, Tm is the temperature of the air existing in the intake pipe portion 22 (hereinafter referred to as “intake pipe temperature”), Vm is the volume of the intake pipe portion 22, and Ra is a value obtained by dividing the gas constant by the average molecular weight of air. It is. Further, mci is the in-cylinder intake air flow rate to the i-th cylinder, and therefore Σmci means the in-cylinder intake air flow rate mc to all the cylinders at a specific time.

Therefore, the in-cylinder intake air flow rate mc to all the cylinders can be expressed as the following formula (4) by modifying the above formula (3).

  On the other hand, as described above, in the present embodiment, the intake valve 6 is electromagnetically driven by the intake valve electromagnetic drive device 12, and the in-cylinder intake air flow rate is basically a voltage applied to the intake valve electromagnetic drive device 12. Is proportional to That is, the magnetic flux generated by the coil of the intake valve electromagnetic drive device 12 increases in proportion to the voltage applied to the intake valve electromagnetic drive device 12. As the magnetic flux increases, the lift amount of the intake valve 6 increases. On the other hand, the flow rate of air flowing into the cylinder of each cylinder increases in proportion to the lift amount of the intake valve 6. Therefore, the in-cylinder intake air flow rate mc is proportional to the voltage applied to the intake valve electromagnetic drive device 12.

  FIG. 3 is a time chart of the time change rate ΔPm of the applied voltage to the intake valve electromagnetic drive device 12, the in-cylinder intake air flow rate, and the intake pipe pressure Pm. The example shown in FIG. 3 shows an example of an 8-cylinder internal combustion engine. The broken line in FIG. 3 (A) indicates the applied voltage to the intake valve electromagnetic drive device 12 of each cylinder, while the solid line indicates the total value of the applied voltage to the intake valve electromagnetic drive device 12 of all cylinders. Yes.

As shown in FIG. 3, there is basically no time when no voltage is applied to the intake valve electromagnetic drive device 12 of all cylinders, and a voltage is always applied to at least one intake valve electromagnetic drive device 12. In particular, as shown by the broken line in FIG. 3A, in the case of an eight-cylinder internal combustion engine, the ignition order (for example, the order of the first cylinder, the eighth cylinder, the seventh cylinder, the third cylinder,...) Is continuous. There is a period in which voltage is simultaneously applied to the intake valve electromagnetic drive device 12 of the two cylinders. Therefore, for example, at the times t ₂ , t ₄ , t ₆ , t ₈ , and t _{10 when} the applied voltages to the two intake valve electromagnetic driving devices 12 to which the voltage is continuously applied are the same, the intake valve electromagnetics of all the cylinders. The total value V _a of the applied voltage to the drive device 12 is twice the applied voltage V _b to the intake valve electromagnetic drive device 12 of each cylinder. Of course, when the voltage is applied only to the intake valve electromagnetic drive device 12 of one cylinder (for example, time t ₁ , t ₃ , t ₅ , t ₇ , t ₉ ), the intake valve electromagnetic of all cylinders. The total value of the applied voltages to the drive device 12 is equal to the applied voltage to the intake valve electromagnetic drive device 12 of this one cylinder.

  In this embodiment, an example of an 8-cylinder internal combustion engine has been described. However, if the internal combustion engine has a period in which voltage is simultaneously applied to the intake valve electromagnetic drive device 12 of two cylinders, The present invention can be applied to an internal combustion engine having any number of cylinders. In particular, in the example shown in the time chart of FIG. 3, there are two intake valve electromagnetic drive devices 12 to which a voltage is simultaneously applied. However, in a multi-cylinder internal combustion engine, three intake valve electromagnetic drive devices 12 to which a voltage is simultaneously applied are three. The total value of the voltages applied to the intake valve electromagnetic drive device 12 at this time is the sum of the voltages of the three or more intake valve electromagnetic drive devices 12 to which a voltage is applied.

  Here, when a voltage is applied to the intake valve electromagnetic drive device 12 for all cylinders as shown in FIG. 3A, the in-cylinder intake air flow rate mc to all the cylinders is as shown in FIG. It will change. In FIG. 3B as well, the broken line indicates the in-cylinder intake air flow rate to each cylinder, that is, mci (i means “i-th cylinder”), while the solid line indicates the cylinder to all cylinders. The internal intake air flow rate, that is, mc is shown.

Here, as described above, the in-cylinder intake air flow rate mci to a certain cylinder is proportional to the applied voltage to the intake valve electromagnetic drive device 12 of that cylinder, and therefore, the intake air of all the cylinders at a specific time t ₁ . The ratio between the total value V _l of the applied voltage to the valve electromagnetic drive device 12 and the total value V _h of the applied voltage to the intake valve electromagnetic drive device 12 of all the cylinders at a time t _h different from the time t _l is as described above. It considered equal to the ratio between in-cylinder intake air flow rate mc _h to all the cylinders in the cylinder intake air flow rate mc _l and the different times t _h to all the cylinders at a particular time t _l.

なお、上記式（５）においてΔＰｍ_lは時刻ｔ_lにおける吸気管内圧力Ｐｍの時間変化率を（ΔＰｍ_l＝（ｄＰｍ／ｄｔ）_l）、ΔＰｍ_hは時刻ｔ_hにおける吸気管内圧力Ｐｍの時間変化率を（ΔＰｍ_h＝（ｄＰｍ／ｄｔ）_h）をそれぞれ表している。上記式（５）において、時刻ｔ_lと時刻ｔ_hとは近いため、吸気管内温度Ｔｍは変化せずに一定であると仮定している。 In other words, the in-cylinder intake air flow rate mc _l for all cylinders when the total value of the applied voltages to the intake valve electromagnetic drive device 12 for all cylinders becomes the first voltage total value V _l , the ratio between in-cylinder intake air flow rate mc _h to all cylinders when the sum of the voltage applied to the intake valve electromagnetically driven device 12 becomes a second voltage sum V _h is a first voltage sum V _l It is considered to be equal to the second voltage total value V _h (V _l : V _h = mc _l : mc _h ). From this relationship, the following formula (5) is derived.

In the above equation (5), ΔPm _l is the time change rate of the intake pipe pressure Pm at time t ₁ (ΔPm _l = (dPm / dt) _l ), and ΔPm _h is the time change of the intake pipe pressure Pm at time t _h . The rate is expressed as (ΔPm _h = (dPm / dt) _h ), respectively. In the above equation (5), since the time t ₁ and the time t _h are close, it is assumed that the intake pipe temperature Tm is constant without changing.

Then, the following formula (6) is derived by modifying the above formula (5).

Accordingly, the throttle-passing air flow rate mt _l and mt _h at time t _l and t _h, the time t and the time rate of change .DELTA.Pm _l and .DELTA.Pm _h of the intake pipe pressure at the _l and t _h, all cylinders at the time t _l and t _h The volume Vm of the intake pipe portion 22 is calculated on the basis of the total values V _l and V _h of the applied voltages to the intake valve electromagnetic drive device 12. In this embodiment, the throttle passage air flow rate mt is detected by the air flow meter 19 and the time change rate ΔPm of the intake pipe internal pressure is calculated based on the intake pipe internal pressure Pm detected by the intake pipe internal pressure sensor 40. The intake pipe temperature Tm used in the equation (5) is detected by the intake pipe temperature sensor 41. Thereby, according to the embodiment of the present invention, the volume of the intake pipe portion 22 can be calculated relatively accurately.

In particular, at time t _l , the applied voltage to the intake valve electromagnetic drive device 12 of the specific cylinder (the sixth cylinder in the example shown in FIG. 3) is maximized, and the applied voltage to the intake valve electromagnetic drive device 12 of the other cylinders is increased. The time is zero (time t _{9 in the} example shown in FIG. 3), and the time t _h is the voltage applied to the intake valve electromagnetic drive device 12 of the specific cylinder being opened and the intake valve is being opened. When the applied voltage to the intake valve electromagnetic drive device 12 of the other cylinder becomes the same, that is, when the total value of the applied voltages to the intake valve electromagnetic drive device 12 of all cylinders becomes the minimum (FIG. 3). In the example shown in FIG. 4, it is preferable that the time is t ₈ or t ₁₀ ). That is, the first voltage total value V _l is the maximum value V ₉ of the total value of the applied voltages to the intake valve electromagnetic drive device 12 of the specific cylinder (for example, the sixth cylinder), and the second voltage total value V _h is the above-mentioned specific value. While the voltage is being applied to the intake valve electromagnetic drive device 12 of the cylinder, the minimum value V ₁₀ of the total value of the applied voltages to the intake valve electromagnetic drive device 12 for all the cylinders is set. In this way, by using the maximum value V ₉ and the minimum value V ₁₀ of the total value of the applied voltages to the intake valve electromagnetic drive devices 12 of all cylinders, the volume of the intake pipe portion 22 can be calculated more accurately. .

Here, if there is a response delay in the intake pipe pressure sensor 40, the time change rate ΔPm of the intake pipe pressure measured at a specific time (for example, times t ₉ and t ₁₀ ) becomes the specified time (time t ₉ and t It may not correspond to the actual rate of time change in ₁₀ ). For this reason, instead of measuring the time change rate ΔPm of the intake pipe pressure only at specific times (times t ₉ and t ₁₀ ), the total value of the applied voltages to the intake valve electromagnetic drive devices 12 of all cylinders is maximized. The time change rate of the pressure in the intake pipe is continuously measured for a while from the time (for example, time t ₉ ) and the minimum time (for example, time t ₁₀ ). The time change rate ΔP of the intake pipe pressure at the specific time (time t ₉ and t ₁₀ ) may be selected from the measured time change rate of the intake pipe pressure.

  That is, as shown in FIG. 3C, the rate of time change ΔPm of the intake pipe pressure when the total value of the applied voltages to the intake valve electromagnetic drive devices 12 of all cylinders is maximized should be the smallest. Therefore, the minimum value of the measured time change rate of the intake pipe pressure is selected as the time change rate of the intake pipe pressure when the total value of the applied voltages to the intake valve electromagnetic drive device 12 of all cylinders becomes the maximum. May be. Similarly, since the time change rate ΔPm of the intake pipe pressure when the total value of the applied voltages to the intake valve electromagnetic drive device 12 of all cylinders is minimized should be the largest, the intake valve electromagnetic drive of all cylinders As the time change rate of the intake pipe pressure when the total value of the applied voltages to the device 12 becomes the minimum, the maximum value of the measured time change rate of the intake pipe pressure may be selected.

Further, since the throttle valve passage intake flow rate mt measured by the air flow meter 19 fluctuates, the time when the total value of the applied voltages to the intake valve electromagnetic drive device 12 becomes maximum (for example, time t ₉ ) and the minimum value. since the time (e.g., time t ₁₀₎ the measured throttle passing intake air flow rate mt in is also contemplated that not true value. For this reason, it is preferable that the calculation of the volume Vm of the intake pipe portion 22 is performed during engine steady operation. That is, if the time of engine steady operation, in order to be able to throttle passing intake air flow rate mt is constant, both the throttle valve passage air flow rate mt at time t ₉ and t ₁₀ of the measured throttle passing intake air flow rate It may be an average value.

  In the above-described embodiment, the voltage applied to the intake valve electromagnetic drive device 12 is used to calculate the volume Vm of the intake pipe portion 22, but the current flowing through the intake valve electromagnetic drive device 12 can also be used. It is. That is, the magnetic flux generated by the coil of the intake valve electromagnetic drive device 12 increases in proportion to the current flowing through the intake valve electromagnetic drive device 12 in the same manner as the applied voltage to the intake valve electromagnetic drive device 12, and accompanying this, The lift amount of the intake valve 6 increases. On the other hand, the in-cylinder intake air flow rate to each cylinder increases in proportion to the lift amount of the intake valve 6. Accordingly, the in-cylinder intake air flow rate to each cylinder is proportional to the current flowing through the intake valve electromagnetic drive device 12 as in the case of the applied voltage to the intake valve electromagnetic drive device 12. Therefore, in place of the applied voltage to the intake valve electromagnetic drive device 12 used in the above embodiment, the current flowing through the intake valve electromagnetic drive device 12 can be used in the same manner as described above for the intake pipe portion 22. The volume Vm can be calculated.

Furthermore, in the above-described embodiment, the volume Vm of the intake pipe portion 22 is obtained. However, in the model formula using the volume Vm of the intake pipe portion 22 as a parameter, the volume of the intake pipe portion 22 is not the actual value but the intake pipe. In many cases, a value (Vm / Tm) obtained by dividing the volume of the portion 22 by the temperature in the intake pipe portion 22 is used. In this case, Vm / Tm can be calculated by using the following formula (7) instead of the above formula (6).

  When Vm / Tm is obtained by the above equation (7), it is not necessary to use the intake pipe temperature Tm in calculating Vm / Tm. For this reason, it is not necessary to attach the intake pipe temperature sensor 41, and the manufacturing cost of the internal combustion engine can be reduced.

  Next, the cylinder charge air amount model M10 will be described. In the following, it is assumed that the average in-cylinder charged air amount calculated by the in-cylinder charged air amount model M10 is Mc 'and the average in-cylinder intake air flow rate is mc'.

  The in-cylinder charged air amount model M10 includes an electronically controlled throttle model M11, a throttle model M12, an intake pipe model M13, and an intake valve model M14 as shown in FIG. The electronically controlled throttle model M11 receives the accelerator pedal operation amount Accp detected by the load sensor 46, and the throttle opening at which the actual throttle valve 18 reaches after a predetermined time ΔT (hereinafter referred to as “prefetch throttle opening”). ) Output θt. The throttle model M12 includes a look-ahead throttle opening angle θt output from the electronically controlled throttle model M11 and the atmospheric pressure around the internal combustion engine detected by the atmospheric pressure sensor 44 (or the pressure of air sucked into the intake pipe 15). Pa, the atmospheric temperature around the internal combustion engine detected by the atmospheric temperature sensor 43 (or the temperature of the air sucked into the intake pipe 15) Ta, and the intake branch pipe 13 calculated in the intake pipe model M13 described later. The pressure (intake pipe pressure) Pm is input, and the value of each of these input parameters is substituted into a model equation of a throttle model M12 to be described later, whereby the flow rate of air passing through the throttle valve 18 per unit time (hereinafter referred to as the following) , Referred to as “throttle valve passage air flow rate mt”). The throttle valve passage air flow rate mt calculated in the throttle model M12 is input to the intake pipe model M13.

  The intake pipe model M13 includes a throttle valve passage air flow rate mt calculated in the throttle model M12 and a flow rate of intake gas flowing into the combustion chamber 5 per unit time described in detail below (hereinafter referred to as “average in-cylinder intake”). The definition of the average in-cylinder intake air flow rate mc ′ will be described in detail in the intake valve model M14), and the values of these input parameters are described later in the intake pipe. By substituting into the model equation of the model M13, the pressure of the intake gas existing in the intake branch pipe 13 and the surge tank 14 (hereinafter referred to as “intake pipe pressure Pm”), the intake branch pipe 13 and the surge tank 14 The temperature of the existing intake gas (hereinafter referred to as “intake pipe temperature Tm”) is calculated. The intake pipe internal pressure Pm and the intake pipe internal temperature Tm calculated in the intake pipe model M13 are both input to the intake valve model M14, and the intake pipe internal pressure Pm is also input to the throttle model M12.

  In addition to the intake pipe pressure Pm and the intake pipe temperature Tm calculated in the intake pipe model M13, the atmospheric temperature Ta is input to the intake valve model M14, and the values of these input parameters are set in the intake valve model M14 described later. By substituting into the model equation, the average in-cylinder intake air flow rate mc ′ is calculated. The calculated average in-cylinder intake air flow rate mc 'is converted into an average in-cylinder charged air amount Mc, and the fuel injection amount from the fuel injection valve is determined based on the average in-cylinder charged air amount Mc. Further, the average in-cylinder intake air flow rate mc ′ calculated in the intake pipe model M13 is input to the intake pipe model M13.

  As can be seen from FIG. 4, in the in-cylinder charged air amount model M10, the value of the parameter calculated in one model is used as an input value to another model. There are only three values input to the throttle opening θt, the atmospheric pressure Pa, and the atmospheric temperature Ta, and the average in-cylinder charged air amount Mc is calculated from these three parameters.

  Next, the models M11 to M14 of the cylinder air charge model M10 will be described.

  The electronically controlled throttle model M11 is based on the accelerator pedal operation amount Accp detected by the load sensor 46, and the throttle opening at which the actual throttle valve 18 reaches after a predetermined time ΔT (hereinafter referred to as “prefetch throttle opening”). This is a model for estimating θt. In the present embodiment, the throttle valve electronic control logic uses the accelerator pedal operation amount Accp detected by the load sensor 46 and a map that defines the relationship between the accelerator pedal operation amount Accp and the target throttle opening θt. A throttle opening θt is obtained. The throttle opening degree θt thus determined is sent to the throttle model M12. On the other hand, a value obtained by delaying the throttle opening θt by a predetermined time ΔT (for example, 64 msec) is obtained as the final target throttle opening θr so that the actual throttle opening TA becomes the target throttle opening θr. A drive signal is sent to the step motor 17.

  Thus, the target throttle opening degree θr is equal to the throttle opening degree θt determined according to the accelerator pedal operation amount Accp at a time point a predetermined time ΔT before the current time point. Since the throttle valve 18 is driven based on the target throttle opening degree θr, the throttle opening degree θt is a throttle opening degree that is ΔT ahead of the actual throttle opening degree of the throttle valve 18. In other words, the throttle opening degree θt is a throttle opening degree that the actual throttle valve 18 reaches after a predetermined time ΔT.

In the throttle model M12, the throttle valve passing air flow rate mt is calculated based on the following equation (8) from the atmospheric pressure Pa, the atmospheric temperature Ta, the intake pipe pressure Pm, and the look-ahead throttle opening θt output from the electronically controlled throttle model M11. Is done. Here, μ in the equation (8) is a flow coefficient in the throttle valve, which is a function of the throttle opening θt. At denotes the opening cross-sectional area of the throttle valve and is a function of the throttle opening θt.

Φ (Pm / Pa) is a function shown in the following formula (9), and κ in the formula (9) is a specific heat ratio (a constant value). Since this function Φ (Pm / Pa) can be expressed in a graph as shown in FIG. 5, such a graph is stored as a map in the ROM 34 of the ECU 31 and is actually calculated using the equation (9). Alternatively, the value of Φ (Pm / Pa) may be obtained from the map.

  Expressions (8) and (9) of the throttle model M12 are such that the gas pressure upstream of the throttle valve 18 is the atmospheric pressure Pa, the gas temperature upstream of the throttle valve 18 is the atmospheric temperature Ta, and the gas downstream of the throttle valve 18 is Applying the law of conservation of mass, the law of conservation of energy and the law of conservation of momentum to the model of the throttle valve 18 as shown in FIG. , And by using the Mayer relation.

In the intake pipe model M13, the intake pipe internal pressure Pm and the intake pipe internal temperature Tm are calculated from the throttle valve passage air flow rate mt, the average in-cylinder intake air flow rate mc ′, and the atmospheric temperature Ta based on the following formulas (10) and (11). Is calculated.

Here, the intake pipe model M13 will be described with reference to FIG. When the total gas amount (total intake gas amount) in the intake pipe portion is M, the temporal change in the total gas amount M is the flow rate of the gas flowing into the intake pipe portion, that is, the throttle valve passing air flow rate mt, and the intake pipe portion. Therefore, the following equation (12) is obtained by the law of conservation of mass, and this equation (12) and the equation of state of gas (Pm · Vm). = M · R · Tm), Equation (10) is obtained.

Further, the amount of time change in the gas energy M · Cv · Tm in the intake pipe portion is equal to the difference between the energy of the gas flowing into the intake pipe portion and the energy of the gas flowing out of the intake pipe portion. Therefore, if the temperature of the gas flowing into the intake pipe portion is the atmospheric temperature Ta and the temperature of the gas flowing out of the intake pipe portion is the intake pipe temperature Tm, the following equation (13) is obtained from the energy conservation law. From equation (13) and the gas equation of state, equation (11) is obtained.

In the intake valve model M14, the average in-cylinder intake air flow rate mc ′ is calculated from the intake pipe pressure Pm, the intake pipe temperature Tm, and the atmospheric temperature Ta based on the following equation (14). In the equation (14), a and b are intake valves in the case of an internal combustion engine having a variable valve mechanism that can change the phase angle (valve timing) and operating angle of the intake valve 6 from the engine speed Ne. 6 is a value determined from the phase angle and the working angle.

  The above-described intake valve model M14 will be described with reference to FIG. In general, the average cylinder charge air amount Mc, which is the amount of intake gas sucked into 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). It is determined and proportional to the pressure in the combustion chamber 5 when the intake valve is closed. Further, the pressure in the combustion chamber 5 when the intake valve is closed can be regarded as being equal to the pressure of the gas upstream of the intake valve, that is, the intake pipe pressure Pm. Therefore, the average in-cylinder charged air amount Mc can be approximated as being proportional to the intake pipe pressure Pm.

  Here, the average amount of all intake gas flowing out from the intake pipe portion per unit time, or the amount of intake gas sucked into all the combustion chambers 5 from the intake pipe portion per unit time is defined as one cylinder. The average in-cylinder intake air flow rate mc ′ (which will be described in detail below) is averaged over the intake stroke (in the present embodiment, the crank angle is 180 ° as will be described later). Since Mc is proportional to the intake pipe pressure Pm, it is considered that the average in-cylinder intake air flow rate mc ′ is also proportional to the intake pipe pressure Pm. From this, the above formula (14) is obtained based on the theory and empirical rules. The value a in the equation (14) is a proportionality coefficient, and is obtained from a three-dimensional map using the engine speed Ne, the applied voltage to the intake valve driving device 12 and the like as parameters. This three-dimensional map is obtained in advance experimentally or by calculation, and is stored in the ROM 34 of the ECU 31. The value b is a value representing the burnt gas remaining in the combustion chamber 5 (it is considered that the amount of burnt gas remaining in the combustion chamber 5 when the exhaust valve 8 is closed is divided by a time ΔT180 ° described later). is there. Further, in actual operation, the intake pipe temperature Tm may change greatly during a transition, and therefore Ta / Tm derived based on theory and empirical rule is multiplied as a correction for this.

  Here, the average in-cylinder intake air flow rate mc ′ will be described with reference to FIG. 9 when the internal combustion engine has four cylinders. In FIG. 9, the horizontal axis represents the rotation angle of the crankshaft, and the vertical axis represents the flow rate of the intake gas actually flowing from the intake pipe portion into the combustion chamber 5 per unit time. As shown in FIG. 9, 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. Intake gas flows from the intake pipe portion into the combustion chamber 5 of each cylinder according to the valve opening amount. For example, the displacement of the flow rate of the intake gas flowing into the combustion chamber 5 of each cylinder from the intake pipe portion is as shown by the broken line in FIG. 9, and this is integrated into the combustion chambers of all cylinders from the intake branch pipe 13. The flow rate of the inflowing intake gas is as shown by the solid line in FIG. Further, for example, the average in-cylinder charged air amount Mc to the first cylinder is as shown by hatching in FIG.

  On the other hand, the average in-cylinder intake air flow rate mc 'is obtained by averaging the amount of intake gas flowing into the combustion chambers of all the cylinders from the intake pipe shown by the solid line, and is shown by a one-dot chain line in the drawing. The average in-cylinder intake air flow rate mc ′ indicated by the one-dot chain line is 180 ° in the case of four cylinders (that is, the angle 720 ° at which the crankshaft rotates during one cycle in a four-stroke internal combustion engine). (Average angle divided by the number of cylinders) multiplied by the time ΔT180 ° required for rotation is the average in-cylinder charged air amount Mc. Therefore, the average cylinder intake air amount Mc is calculated by multiplying the average cylinder intake air flow rate mc 'calculated by the intake valve model M14 by ΔT180 ° (Mc = mc' · ΔT180 °). More specifically, in consideration of the fact that the average in-cylinder charged air amount Mc is proportional to the pressure when the intake valve is closed, the average in-cylinder intake air flow rate mc ′ when the intake valve is closed is multiplied by ΔT180 °. Is the average in-cylinder charged air amount Mc.

  In the cylinder charge air amount model M10, the atmospheric temperature Ta and the atmospheric pressure Pa are assumed to be constant. However, the atmospheric temperature Ta and the atmospheric pressure Pa may be changed with time, for example, by the atmospheric temperature sensor 43 for detecting the atmospheric temperature. The detected value is substituted into the above equations (8), (11), and (14) as the atmospheric temperature Ta and the value detected by the atmospheric pressure sensor 44 for detecting the atmospheric pressure as the atmospheric pressure Pa. It may be.

It is a figure which shows the whole internal combustion engine carrying the intake passage volume calculation apparatus of this invention. It is a figure which shows the basic concept of the model of this invention. It is a time chart of the time change rate of the applied voltage to the intake valve electromagnetic drive device, the in-cylinder intake air flow rate, and the intake pipe pressure. It is a block diagram of an air model. It is a figure which shows function (PHI) (Pm / Pa). It is a figure which shows the basic concept of a throttle model. It is a figure which shows the basic concept of an intake pipe model. It is a figure which shows the basic concept of an intake valve model. It is a figure regarding the definition of cylinder filling air amount and cylinder intake air flow rate.

Explanation of symbols

1 Engine Body 5 Combustion Chamber 6 Intake Valve 7 Intake Port 8 Exhaust Valve 11 Fuel Injection Valve 12 Intake Valve Electromagnetic Drive 13 Intake Branch Pipe 14 Surge Tank 15 Intake Pipe 18 Throttle Valve 22 Intake Pipe Portion

Claims (4)

In the intake passage volume calculating device for calculating the volume of the intake passage on the downstream side of the throttle valve of the internal combustion engine comprising the intake valve electromagnetic drive device for driving the intake valve,
Calculating the volume of the intake passage based on the pressure change rate in the intake passage on the downstream side of the throttle valve, the flow rate of air passing through the throttle valve, and the total value of the voltage or current applied to the intake valve electromagnetic drive devices of all cylinders; Intake passage volume calculation device.   The voltage or current applied to the intake valve electromagnetic drive system of all cylinders using the relational expression of the pressure change rate of the intake passage on the downstream side of the throttle valve, the volume of the intake passage, the throttle valve passing air flow rate and the cylinder intake air flow rate When the total value of the cylinders becomes the first total value, the in-cylinder intake air flow rate into all the cylinders calculated using the above relational expression, and the second total value in which the total value is different from the first total value, The intake passage downstream of the throttle valve is assumed that the ratio of the in-cylinder intake air flow rate into all the cylinders calculated using the above relational expression is equal to the ratio between the first total value and the second total value. The intake passage volume calculation device according to claim 1, wherein the volume of the intake passage is calculated.   The first total value is the maximum value of the voltage or current applied to the intake valve electromagnetic drive device during opening of the intake valve of the specific cylinder, and the second total value is the intake valve during opening of the intake valve of the specific cylinder. The intake passage volume calculation device according to claim 2, wherein the intake passage volume is a minimum value of a voltage or a current applied to the electromagnetic drive device. Volume of the intake passage of Vm throttle valve downstream side, Ra the gas constant, the temperature of the intake passage of the Tm, the first sum value above the V _l, the a V _h second sum, the .DELTA.Pm _l and mt _l pressure change rate and the throttle passage air flow rate of the intake passage when the sum of the voltage or current applied to the intake valve electromagnetically driven device for all the cylinders becomes the first sum, the intake valve solenoid of all the cylinders the .DELTA.Pm _h and mt _h When the pressure change rate of the intake passage and the throttle passage air flow rate when the total value of the voltage or current applied to the driving device becomes the second total value, the volume of the intake pipe portion is calculated by the following equation (1). The intake passage volume calculation device according to claim 2 or 3.

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