JP4457954B2 - Valve opening calculation device, valve control device, and valve opening calculation method - Google Patents

Description

  The present invention relates to a technique for obtaining an opening area of a valve from the opening degree of the valve or obtaining an opening degree of the valve from the opening area of the valve.

In Patent Document 1, during the idling operation of the internal combustion engine, the opening degree of the throttle valve is feedback-controlled so that the engine speed approaches the target idle speed, and the correction amount by the feedback is contaminated or clogged in the intake system. An idle rotation control device is disclosed that learns as a change in a decrease in opening area over time.
JP-A-11-182302

  Conventionally, the correlation between the opening of the throttle valve and the opening area of the throttle valve has been corrected with an offset value based on the feedback correction.

  However, since the change characteristic of the opening area with respect to the opening has a characteristic approximated by a function of the second or higher order, the opening area corrected by the offset is not uniform in each opening, and the learning opening is performed. There was a problem that the estimation accuracy of the opening area deteriorated under opening conditions other than degrees.

  The present invention has been made in view of the above problems, and an object of the present invention is to improve the conversion accuracy by a correction process using an offset value in a conversion process between a valve opening and a valve opening area. And

  Therefore, in the present invention, a conversion process is performed between the opening and the diameter of the circle based on the correlation between the opening of the valve and the diameter of a circle having an area approximate to the opening area of the valve. It was.

  According to the above configuration, the correlation between the opening degree of the valve and the diameter of a circle having an area approximating the valve opening area can be approximated by a linear function, and therefore suitable for correcting the correlation with the offset amount. ing.

  Therefore, for example, by giving a change in the decrease in the opening area over time due to dirt or clogging around the valve as an offset correction value, it is possible to accurately correct the correlation at each opening.

  Embodiments of the present invention will be described below.

  FIG. 1 is a system diagram of an internal combustion engine for a vehicle according to an embodiment.

  Air that has passed through the air cleaner 2 is sucked into each cylinder of the internal combustion engine 1 shown in FIG. 1 through the intake duct 3, the intake collector 4, the intake manifold 5, and the intake valve 6.

  The intake air amount of the engine 1 is adjusted by the opening degree (rotation angle) of a butterfly throttle valve 7 interposed in the intake duct 3.

  The throttle valve 7 is an electrically controlled valve that is driven to open and close by a throttle motor 8.

  A fuel injection valve 9 is provided in each intake port portion of each cylinder.

  The air-fuel mixture formed by the fuel (gasoline) injected from the fuel injection valve 9 is ignited and combusted by spark ignition by an ignition plug (not shown) in the combustion chamber 10.

  The combustion exhaust in the combustion chamber 10 is discharged to the atmosphere via an exhaust valve 11, an exhaust manifold 12, and an exhaust duct 13.

  The exhaust duct 13 is provided with a catalytic converter 14 for purifying harmful components in the exhaust.

  The throttle motor 8 and the fuel injection valve 9 are controlled by an engine control unit (ECU) 21 incorporating a microcomputer.

  Detection signals from various sensors are input to the engine control unit 21.

  The various sensors include an atmospheric pressure sensor 22 that detects the atmospheric pressure upstream of the air cleaner 2, and an air flow meter (AFM) 23 that detects the intake air flow rate (mass flow rate) of the engine 1 upstream of the throttle valve 7. An intake pressure sensor 24 for detecting the intake pressure in the intake collector 4, an air / fuel ratio sensor 25 for detecting the exhaust air / fuel ratio on the upstream side of the catalytic converter 14 based on the oxygen concentration in the exhaust, and the rotational speed of the engine 1 A rotation speed sensor 26 for detecting, an accelerator opening sensor 27 for detecting the depression amount (accelerator opening) of an accelerator pedal operated by the driver, and a throttle sensor 28 for detecting the opening (rotation angle) of the throttle valve 7 are provided. It has been.

  The air flow meter 23 includes an intake air temperature sensor 29 for detecting the intake air temperature, and further includes an in-collector temperature sensor 30 for detecting the intake air temperature in the intake air collector 4.

  Here, as shown in FIG. 2, the engine control unit 21 sets a target valve opening, which is a target value of the opening of the throttle valve 7, and the opening detected by the throttle sensor 28 is The throttle motor 8 is feedback-controlled so as to achieve the target valve opening.

  In setting the target valve opening, first, a target opening area that is a target value of the opening area of the throttle valve 7 is set based on the accelerator opening or the target intake air flow rate.

  Next, the target opening area is converted into a target opening diameter that is the diameter (radius or diameter) of a circle having the same area as the target opening area (target setting means), and the target opening diameter is converted into a target valve opening. To do.

  Further, as shown in FIG. 3, the engine control unit 21 converts the throttle valve opening detected by the throttle sensor 28 into an opening diameter that is a diameter of a circle that approximates the opening area (first conversion means). , A function of calculating the opening area of the throttle valve 7 from the opening diameter (second conversion means).

  The opening area of the throttle valve 7 is the sum of the areas when the gap between the throttle valve 7 and the inner wall of the intake duct 3 is projected in the axial direction of the intake duct 3, as shown in FIG. The opening diameter is the radius or diameter of the circle when the opening shape of the opening area is assumed to be a circle.

  The target opening diameter can be directly set based on the accelerator opening or the target intake air flow rate.

  As shown in FIG. 5, the characteristic of the opening area with respect to the opening degree of the throttle valve 7 cannot be approximated by a linear function, but the diameter of a circle having the same area as the opening area of the throttle valve 7 is shown in FIG. As shown, it has a characteristic that can be approximated by a linear function with respect to the throttle valve opening.

  When the opening area is A, the opening is θ, and the opening diameter (radius) is r,

Because

It is because it can approximate.

  By the way, due to dirt or clogging of the valve body of the throttle valve 7 or the intake pipe wall surrounding the throttle valve 7, the throttle opening area corresponding to the throttle opening may change with time.

  Here, in order to cope with the change in the opening area with time, the correlation between the throttle valve opening and the opening area shown in FIG. Since the correlation cannot be approximated by a linear function, the data of the opening area with respect to the throttle valve opening is not uniformly reduced.

  On the other hand, the diameter of a circle (hereinafter also referred to as an opening diameter) that is an area that approximates the opening area of the throttle valve 7 can be approximated by a linear function with respect to the throttle valve opening, as shown in FIG. By offsetting by a certain amount, the data of the opening area with respect to the throttle valve opening can be reduced substantially uniformly.

  Accordingly, a correlation between the diameter of a circle that is an area approximating the opening area of the throttle valve 7 and the throttle valve opening is stored in advance, and the target valve opening corresponding to the target opening area is set based on the correlation. For example, the target valve opening can be corrected and set accurately with respect to the aforementioned dirt and clogging by offset correction (see FIG. 7).

  Therefore, in the present embodiment, as described above, after converting the target opening area to the target opening diameter, the target opening diameter is converted to the target valve opening based on the characteristics shown in FIG. The target opening diameter is corrected with a correction value corresponding to the dirt or clogging (target correcting means), and the target valve opening is determined based on the corrected target opening diameter (fourth converting means).

  Note that the conversion of the target opening diameter to the target valve opening may be performed by storing a characteristic conversion table as shown in FIG. 6 in advance or approximating the characteristic shown in FIG. 6 with a linear function. And the target valve opening may be obtained by calculation from the target opening diameter by the linear function.

  Here, the correlation between the throttle valve opening and the opening diameter can be accurately approximated by a linear function (opening diameter = throttle valve opening × a + b) particularly in the low and medium opening ranges, but in the high opening range, Since the approximation error due to the linear function becomes large, when the target valve opening is obtained by calculation using the linear function, the approximation error can be given as a correction value.

  The correction value of the target opening diameter for dealing with dirt and clogging of the intake system is calculated as shown in FIG.

  First, an opening diameter corresponding to the throttle valve opening detected by the throttle sensor 28 is obtained as a basic opening diameter based on the characteristics shown in FIG.

  The basic opening diameter is obtained from the correlation between the throttle valve opening and the opening diameter in the initial state where there is no dirt or clogging around the throttle valve.

  The throttle valve opening can be converted into an opening area based on the characteristics shown in FIG. 5, and the diameter of a circle having the same area as the opening area can be used as the basic opening diameter.

  On the other hand, the actual opening area of the throttle valve 7 at that time is measured (measuring means), and the diameter of a circle having the same area as the measured opening area is obtained and used as the measured opening diameter (third converting means). ).

  The basic opening diameter is an estimated value based on the assumption that there is no dirt or clogging around the throttle valve, whereas the measured opening diameter is an actual value obtained by detecting dirt or clogging around the throttle valve.

  Here, in the initial state where there is no dirt or clogging, the basic opening diameter and the measurement opening diameter are substantially the same, but if the opening area with respect to the throttle valve opening becomes smaller than the initial due to the occurrence of dirt or clogging over time. The measured aperture diameter is smaller than the basic aperture diameter, and the difference between the basic aperture diameter and the measured aperture diameter indicates the amount of change in the aperture area due to dirt or clogging.

  Therefore, the result of subtracting the difference between the basic opening diameter and the measured opening diameter from the basic opening diameter corresponding to each throttle valve opening (that is, the measured opening diameter) is the actual valve opening area with respect to the throttle opening at that time. The opening area (corrected opening area) obtained from the corrected opening diameter represents the actual throttle opening area (see FIG. 7).

  For example, when the opening area is obtained from the throttle valve opening and the fuel injection amount by the fuel injection valve 9 is controlled based on the intake air amount estimated from the opening area and the engine rotational speed, the corrected opening area described above is used. By using this, the fuel injection amount can be accurately controlled in response to dirt and clogging of the throttle valve 7.

  Further, when the target valve opening corresponding to the target opening area is obtained as in this embodiment, the difference between the basic opening diameter and the measured opening diameter is used as a correction value for the target opening diameter (correction value calculating means). Then, the target opening diameter is increased and corrected with the correction value, and the target valve opening degree corresponding to the increased corrected target opening diameter is set (see FIG. 2).

  As a result, the opening of the throttle valve 7 is controlled to be larger than the initial value so as to compensate for the decrease in the opening area due to dirt or clogging.

  The correction of the target opening diameter based on the difference between the basic opening diameter and the measured opening diameter is based on the correlation approximated by a linear function between the opening diameter and the throttle valve opening as shown in FIG. Therefore, the decrease in the opening area due to dirt or clogging can be accurately corrected over the entire area.

  Next, a method for measuring the opening area of the throttle valve 7 will be described.

  First, the intake system of the engine 1 including the throttle valve 7 is approximated to a tapered nozzle as shown in FIG.

Then, the air flow in the tapered nozzle is a quasi-one-dimensional steady entropy flow, and the mass flow rate m is the throat cross-sectional area A, the inlet side pressure P ₀ , the inlet side temperature T ₀ , the outlet side pressure Pe, and the outlet side temperature Te. , Based on the specific heat ratio k and the gas constant R.

  When Equation 3 is converted into an equation for obtaining the throat cross-sectional area A, Equation 4 is obtained.

  Here, Equation 3 is simplified as shown in Equation 5 under the condition that the flow velocity of the air flowing through the tapered nozzle (throttle valve 7) is the sonic velocity (critical velocity).

When Equation 5 is converted into an equation for obtaining the throat cross-sectional area A, Equation 6 is obtained.

Since the specific heat ratio k and gas constant R can be stored in advance as known values, the temperature T ₀ and the pressure P ₀ on the inlet side, and the mass flow rate under the condition that the flow velocity is the sonic velocity (critical velocity). If m can be detected, the opening area of the throttle valve 7 can be measured based on Equation 6.

Since the inlet-side temperature T ₀ corresponds to the intake air temperature in the engine 1, it can be detected by the intake-air temperature sensor 29. The inlet-side pressure P ₀ is atmospheric pressure in the engine 1, and the atmospheric pressure sensor 22. The mass flow rate m can be detected by the air flow meter 23.

  Therefore, under the critical speed condition, the throttle valve opening area can be easily measured from the detection results of the intake air temperature sensor 29, the atmospheric pressure sensor 22, and the air flow meter 23.

  It should be noted that the atmospheric pressure can be regarded as constant, and if the atmospheric pressure sensor 22 is not provided, the detection result of the intake pressure sensor 24 when the engine 1 is stopped can be regarded as the atmospheric pressure.

  Further, in the case where the opening area of the throttle valve 7 is calculated based on Equation 4 under conditions other than the critical speed, it is necessary to detect the outlet side pressure Pe and the outlet side temperature Te. Since the intake pressure is 1, the intake pressure sensor 24 can detect it, and the outlet temperature Te can be detected by the collector temperature sensor 30.

  Further, when the intake pressure sensor 24 is not provided, the pressure in the collector (the outlet side pressure Pe) can be estimated, and the opening area of the throttle valve 7 can be measured based on the estimated value.

That is, when the collector pressure is P ₂ , the collector volume is Vc, the molar density in the collector is n, and the intake air temperature is T ₂ , the relationship of Equation 7 is established.

When the above equation 7 is converted into an expression for the change in collector pressure P ₂ per calculation period Δt, the following equation 8 is obtained.

Here, if Δn is the difference between the throttle flow rate n _in and the intake flow rate n _out to the cylinder, and the previous value of the collector pressure P ₂ is P _{2 (n−1)} , then Equation 8 is rewritten as Equation 9 It is done.

When Equation 9 is rewritten as an equation for obtaining the collector pressure P ₂ , Equation 10 is obtained.

Accordingly, the collector pressure P ₂ can be estimated by detecting the throttle flow rate n _in , the intake flow rate n _out to the cylinder, and the temperature in the collector.

The intake flow rate n _out to the cylinder is calculated based on Equation 11 where V is the displacement of the engine 1, Ne is the rotational speed (rpm), and η is the efficiency corresponding to the rotational speed Ne.

Further, the mass flow rate detected by the air flow meter 23 can be used as the throttle passage flow rate n _in .

  Further, as a method for measuring the opening area of the throttle valve 7, the actual equivalent ratio is obtained as a result of controlling the fuel injection amount so as to be the target equivalent ratio based on the opening area obtained from the opening degree of the throttle valve 7. It is possible to measure the amount of change in the decrease in the opening area due to dirt or clogging based on whether or not they match.

  That is, when the actual opening area corresponding to the throttle valve opening becomes small due to dirt or clogging, the actual intake air amount becomes smaller than the intake air amount estimated from the throttle opening, and the air-fuel ratio becomes rich.

  Therefore, from the difference between the target equivalence ratio and the actual equivalence ratio (exhaust equivalence ratio) detected by the air / fuel ratio sensor 25, the amount of change in the opening area due to dirt and clogging can be estimated, and the opening area determined from the throttle opening degree. It is determined that the actual opening area is the result of correcting the value by the amount of decrease.

  FIG. 9 is a block diagram showing a method for measuring the opening area based on the above-described exhaust equivalence ratio.

  First, the throttle valve opening is converted into a basic opening diameter based on a conversion characteristic (a conversion table or an arithmetic expression) between the throttle valve opening and the opening diameter set corresponding to the initial state, and based on the basic opening diameter. To calculate the basic opening area.

  On the other hand, the fuel injection amount is controlled from the basic opening area and the engine rotational speed so as to achieve a target equivalent ratio, and the exhaust equivalent ratio as a result of the fuel injection amount control is detected by the air-fuel ratio sensor 25.

  Then, a decrease change in the opening area over time is estimated from the target equivalence ratio and the exhaust equivalence ratio, and the basic opening area is corrected based on the decrease change, thereby obtaining an actual opening area (estimated opening area). )

  Next, the estimated opening area is converted into an opening diameter to obtain an estimated opening diameter, and a difference between the basic opening diameter and the estimated opening diameter is set as a correction value corresponding to a decrease change in the opening area due to dirt or clogging.

  The flowchart of FIG. 10 shows a flow of processing for obtaining the correction value of the opening diameter.

  The routine shown in the flowchart of FIG. 10 is executed every predetermined time (for example, 10 ms).

  In step S1, the opening degree (rotation angle) of the throttle valve 7 detected by the throttle sensor 28 is read.

  In step S2, it is determined whether or not the throttle valve opening is smaller than an upper limit opening (for example, 5 deg).

  If the throttle valve opening is greater than or equal to the upper limit opening, the process is terminated without performing correction value calculation or the like. If the throttle valve opening is smaller than the upper limit opening, the process proceeds to the next step S3. .

  In the region where the throttle valve opening is greater than or equal to the upper limit opening, the ratio of the decrease in the opening area due to dirt or clogging to the entire opening area is small. Setting accuracy is deteriorated.

  Therefore, when the throttle valve opening is equal to or larger than the upper limit opening, the measurement of the opening area and the calculation of the correction value are prohibited to prevent the accuracy of the correction control from deteriorating.

  Further, by prohibiting the measurement of the opening area and the calculation of the correction value when the throttle valve opening is greater than or equal to the upper limit opening, it is possible to avoid performing unnecessary calculation processing and reduce the calculation load.

  In the initial state where the decrease in the opening area due to dirt or clogging is small, the opening that can accurately detect the decrease is small, and the decrease in the opening area increases due to the progress of dirt or clogging. The opening at which the minute can be detected accurately changes to the higher opening.

  Therefore, the larger the correction value (the more the dirt or clogging progresses), the more the upper limit opening is changed, and the opening range for executing the measurement of the opening area and the calculation of the correction value is expanded to the high opening side. Can do.

  In step S3, it is determined whether or not the throttle valve opening exceeds a lower limit opening (for example, 0.8 deg).

  If the throttle valve opening is equal to or lower than the lower limit opening, the process is terminated as it is without calculating a correction value, and the next step S4 is performed when the throttle valve opening exceeds the lower limit opening. move on.

  When the throttle valve opening is below the lower limit opening, the influence of dirt, clogging, and component tolerances is too great, which may lead to correction value setting errors, and the detection accuracy of the throttle valve opening will deteriorate. However, since the calculation accuracy of the basic opening diameter and the basic opening area is lowered, the setting accuracy of the correction value is deteriorated.

  Therefore, when the throttle valve opening is equal to or lower than the lower limit opening, the measurement of the opening area and the calculation of the correction value are prohibited to prevent the correction value setting accuracy from deteriorating.

  The larger the decrease in the opening area due to dirt or clogging, the larger the detection error of the opening area change on the low opening side. Therefore, the larger the correction value (the more the dirt or clogging progresses), the more the lower limit opening is increased. It is preferable to greatly change the opening area where the opening area is measured and the correction value is calculated to be limited to a higher opening side.

  If the throttle valve opening is below the upper limit opening and exceeds the lower limit opening, the process proceeds to step S4, where the absolute value of the change amount of the throttle valve opening per routine execution cycle is a threshold value (for example, 0.2 deg). ) Or less.

  If the absolute value of the change amount is equal to or greater than the threshold value, the process is terminated without performing a correction value calculation or the like. If the absolute value of the change amount is smaller than the threshold value, the process proceeds to step S5.

  When the throttle valve opening is fluctuating, the calculation accuracy of the correction value deteriorates. Therefore, if the absolute value of the change amount is greater than or equal to the threshold value, the measurement of the opening area and the calculation of the correction value are prohibited and correction is performed. This prevents the deterioration of accuracy.

  In step S5, the opening area of the throttle valve 7 is measured as described above.

  In step S6, it is determined whether or not the change rate (%) of the opening area measured in step S5 is below a threshold value (for example, 5%).

  If the change rate is equal to or greater than the threshold value, the process is terminated without performing correction value calculation or the like. If the change rate is smaller than the threshold value, the process proceeds to step S7.

  When the measurement result of the opening area is fluctuating, the calculation accuracy of the correction value is deteriorated. Therefore, when the change rate is equal to or greater than the threshold, the measurement of the opening area and the calculation of the correction value are prohibited, Prevents deterioration.

  In step S7, the measurement result of the opening area in step S5 is converted into a circle diameter having the same area, and this is used as the measurement opening diameter.

  In step S8, the opening diameter shown in the opening area is obtained from the opening of the throttle valve 7 at that time, and this is set as the basic opening diameter.

  In step S9, the difference between the measured opening diameter and the basic opening diameter is set as a correction value for correcting the target opening diameter.

  Since the difference between the measured opening diameter and the basic opening diameter indicates the change in the opening area due to dirt or clogging, the change in the opening area due to dirt or clogging can be obtained by adding the correction value to the target opening diameter. The throttle valve 7 is opened larger so as to compensate for the minute, and it becomes possible to obtain the target opening area even if there is dirt or clogging.

  In particular, since the correlation between the throttle valve opening and the opening diameter can be approximated by a linear function, correction of the reduction change of the opening area is performed on the target opening diameter, and the target opening diameter is converted into the target valve opening. Thus, even if the correction value is not learned, the amount of change in the opening area can be accurately corrected, and the control accuracy of the intake air amount can be improved with simple correction control.

  In the above embodiment, the valve for detecting the opening area is the throttle valve 7 of the internal combustion engine 1, but in addition, an EGR valve for controlling the exhaust gas recirculation amount, a purge valve for controlling the purge air amount from the canister, For the blow-by valve that controls the amount of gas, the processing to obtain the opening area after converting the opening to the opening diameter or the processing to obtain the target opening after converting to the target opening diameter of the target opening area can be performed. it can.

  Further, the intake system from the outside air inlet of the internal combustion engine 1 to the collector inlet is comprehensively regarded as one valve, and the conversion between the opening area and the opening of the valve is once converted into the opening diameter. be able to.

  Further, the valve is not limited to the valve that controls the gas flow rate in the internal combustion engine 1.

1 is a system diagram of an internal combustion engine in an embodiment of the present invention. It is a block diagram which shows the setting process of the target valve opening degree in the said embodiment. It is a block diagram which shows the conversion process from the valve opening degree to the valve opening area in the said embodiment. It is a figure for demonstrating the correlation with the valve | bulb opening area and opening diameter in the said embodiment. It is a graph which shows the correlation with the throttle-valve opening degree and opening area in the said embodiment. It is a graph which shows the correlation with the throttle-valve opening degree and opening diameter in the said embodiment. It is a graph which shows the change by the dirt and clogging of the correlation of the throttle valve opening degree and opening diameter in the said embodiment. It is a figure for demonstrating the approximation process to the taper nozzle of an intake system in the said embodiment. It is a block diagram which shows the measurement process of the opening area based on the exhaust equivalence ratio in the said embodiment. It is a flowchart which shows the setting process of the correction value of the aperture diameter in the said embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine, 2 ... Air cleaner, 3 ... Intake duct, 4 ... Intake collector, 5 ... Intake manifold, 6 ... Intake valve, 7 ... Throttle valve, 8 ... Stroll motor, 9 ... Fuel injection valve, 10 ... Combustion chamber , 11 ... exhaust valve, 12 ... exhaust manifold, 13 ... exhaust duct, 14 ... catalytic converter, 21 ... engine control unit, 22 ... atmospheric pressure sensor, 23 ... air flow meter, 24 ... intake pressure sensor, 25 ... air-fuel ratio sensor, 26 ... Rotational speed sensor, 27 ... Accelerator opening sensor, 28 ... Throttle sensor, 29 ... Intake air temperature sensor, 30 ... Collector internal temperature sensor

Claims (18)

  A valve opening characterized in that conversion processing is performed between the opening and the diameter of the circle based on a correlation between the opening of the valve and a diameter of a circle having an area approximate to the opening area of the valve. Arithmetic unit.   Characterized by comprising conversion means for performing conversion processing between the opening degree and the diameter of the circle based on the correlation between the opening degree of the valve and the diameter of a circle having an area approximate to the opening area of the valve. Valve opening calculation device. The converting means is
First conversion means for converting the opening of the valve into a diameter of a circle based on the correlation;
Second conversion means for converting the diameter of the circle obtained by the first conversion means into the opening area of the valve;
The valve opening calculating device according to claim 2, comprising:   4. The valve opening calculation device according to claim 3, wherein the first conversion means calculates the diameter by a linear function having the valve opening as a variable. The first conversion means is a basic diameter calculating means for calculating a basic diameter in an initial state by a linear function having the opening of the valve as a variable; a correcting means for correcting the basic diameter for each opening of the valve; The valve opening calculating device according to claim 4 , comprising: Measuring means for measuring the actual opening area of the valve;
A third converting means for converting the opening area of the valve measured by the measuring means into a diameter of a circle having an area approximating the opening area;
Correction value calculation means for calculating a correction value for correcting the diameter corresponding to the valve opening based on the difference between the basic diameter and the diameter obtained by the third conversion means;
6. The valve opening arithmetic device according to claim 5, further comprising:   The valve opening arithmetic device according to claim 6, wherein the measuring means measures an opening area of the valve based on a mass flow rate of the gas passing through the valve.   8. The valve opening calculation device according to claim 7, wherein the measuring means measures an opening area of the valve based on a mass flow rate of the gas when a flow velocity of the gas passing through the valve is a critical velocity.   The valve opening arithmetic device according to claim 6, wherein the measuring means measures an opening area of the valve based on a mass flow rate of gas passing through the valve and a pressure before and after the valve.   The valve according to any one of claims 6 to 9, wherein the correction value calculation means calculates the correction value when the valve opening area measured by the measurement means is in a stable state. Aperture calculation device.   The valve opening calculating device according to any one of claims 6 to 10, wherein the correction value calculating means calculates the correction value when the opening of the valve is smaller than an upper limit opening. .   The valve opening calculating device according to any one of claims 6 to 11, wherein the correction value calculating means calculates the correction value when the opening of the valve is larger than a lower limit opening. .   The valve opening area detection according to any one of claims 6 to 12, wherein the correction value calculating means calculates the correction value when a change in the opening of the valve is equal to or less than a threshold value. apparatus.   The valve opening area according to any one of claims 6 to 13, wherein the second conversion means converts the diameter corrected by the correction value calculated by the correction value calculation means into a valve opening area. Detection device. While comprising the valve opening arithmetic unit according to any one of claims 6 to 13,
Target setting means for setting a target of the diameter;
Target correction means for correcting the target diameter based on the correction value;
Fourth conversion means for converting the target diameter corrected by the correction value into a target valve opening based on the correlation;
A valve control device comprising: The valve is a throttle valve of an internal combustion engine;
The valve control device according to claim 15, wherein the target setting means sets the target diameter from a target intake air amount or an accelerator opening of the internal combustion engine. A target opening area setting means for setting a target valve opening area;
16. The valve control device according to claim 15, wherein the target setting means sets a target diameter corresponding to the target valve opening area.   A valve opening calculation method for performing conversion processing between the opening and the diameter based on a correlation between the opening of the valve and a diameter of a circle having an area approximate to the opening area of the valve.

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