Air flow calculation system

Abstract

To provide an air flow calculation system capable of calculating with high accuracy an air flow rate passing through a valve on a multi-cylinder engine.SOLUTION: An air flow calculation system W that calculates an air flow rate through a valve passing through an intake pipe 1 that allows air to flow into cylinders of a multi-cylinder engine EG includes: a high-response flow sensor 10 that measures a throttle intake air flow rate flowing into a throttle valve 5 through an intake pipe 7; a pressure sensor 20 that is connected to the intake pipe 1 and measures the intake air pressure of a chamber 3 that allows air to flow into the intake pipe 1; a temperature sensor 30 that measures an intake air temperature of the air flowing into the intake pipe 1; a temperature sensor 40 that measures an atmospheric temperature; and an information processing device 100 that calculates an air flow rate through the valve using a formula set in advance and a measured value on each sensor.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an air flow rate calculation system for calculating a valve-passing air flow rate that passes through an intake pipe through which air flows into the cylinders of a multi-cylinder engine. [Background technology]

[0002] Conventionally, the following methods have been known as methods for calculating the flow rate of air passing through an intake pipe that introduces air into the cylinders of a multi-cylinder engine EG (through-valve air flow rate (miv)).

[0003] Specifically, as shown in FIG. 6, various sensors (not shown) (a temperature sensor for measuring atmospheric temperature, an air flow sensor, a pressure sensor, and a temperature sensor for measuring intake air temperature) measure the atmospheric temperature (Tat), the air flow rate (mth) of air flowing into the throttle valve 5 through the intake pipe 7, the pressure of the air flowing into the chamber 3 (intake pressure (Pin)), and the temperature of the air flowing into the intake pipe 1 (intake air temperature (Tin)).

[0004] A method is known for calculating the air flow rate through the valves (miv) of a multi-cylinder engine using each measurement value (atmospheric temperature (Tat), air flow rate (mth), intake pressure (Pin), intake temperature (Tin)) and the following (Equation 1).

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[0005] As another method, a method is also known in which the air flow rate through the valves (miv) of a multi-cylinder engine is calculated using the respective measurement values ​​(atmospheric temperature (Tat), air flow rate (mth), intake pressure (Pin), intake temperature (Tin)) obtained by the respective sensors as described above and the following (Equation 2).

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[0006] [Non-Patent Document 1] Nishima, Norihiro, Niki, Hajime, Kimura, "Estimation of In-Cylinder Intake Volume for Automotive Engine Control Using Extended Kalman Filter", Transactions of the Society of Instrument and Control Engineers, Vol. 33, No. 5, 397 / 402 (1997), May 1997, explanation of (Equation 4) on page 3 (page 399) [Non-Patent Document 2] Masahiro Kawaguchi, Masatake Yamakita, "Kernel Identification Method of Error Model in Engine Model Identification", Transactions of the Society of Instrument and Control Engineers, Vol. 50, No. 3, 311 / 317 (2014), March 2014, page 2 (312) (Equation 5) Summary of the Invention [Problem to be solved by the invention]

[0007] However, the above-mentioned conventional method for calculating the "valve-passing air flow rate flowing into the multi-cylinder engine EG" has the following problems. Specifically, the method of calculating the valve passing air flow rate flowing into the multi-cylinder engine EG using the above-mentioned (Equation 1) has a problem that the valve passing air flow rate when the engine EG is in a transient state does not match the actual value of the valve passing air flow rate because it does not take into account temperature changes in the intake pipe 1. In other words, the method of calculating the valve passing air flow rate passing through the cylinder (intake pipe) 1 of the multi-cylinder engine EG using the above-mentioned (Equation 1) cannot calculate an accurate valve passing air flow rate when the engine EG is in a transient state.

[0008] Furthermore, the method of calculating the valve passing air flow rate of the multi-cylinder engine EG using the above-mentioned formula (Formula 2) has a problem that the valve passing air flow rate during steady state behavior of the engine EG deviates from the actual air flow rate value because the blowback gas temperature is not taken into consideration. That is, the method of calculating the valve passing air flow rate passing through cylinder (intake pipe) 1 of the multi-cylinder engine EG using the above-mentioned formula (Formula 2) cannot calculate an accurate valve passing air flow rate during steady state behavior of the engine EG.

[0009] The present invention has been made in consideration of the above-mentioned problems, and an object of the present invention is to provide an air flow rate calculation system that can calculate the valve-passing air flow rate of a multi-cylinder engine with high accuracy. [Means for solving the problem]

[0010] In order to solve the above-mentioned problems, the present invention provides an air flow calculation system for calculating a valve passing air flow rate passing through an intake pipe that introduces air into cylinders of a multi-cylinder engine, the system comprising: a high-response flow rate sensor that measures a throttle intake flow rate, which is the air flow rate that flows into a throttle valve of the multi-cylinder engine; a pressure sensor that is connected to the intake pipe and that measures an intake pressure inside a chamber that introduces air into the intake pipe; a first temperature sensor that measures an intake temperature of the air that flows into the intake pipe; a second temperature sensor that measures an atmospheric temperature; and an information processing device that calculates the valve passing air flow rate using a preset calculation formula and the measured values ​​of the sensors, the calculation formula being calculated by calculating a flow rate of the throttle intake flow rate, the intake pressure, the volume of the intake pipe, the intake temperature, the atmospheric temperature, and a gas constant based on a previous equation. The information processing device calculates the valve passing air flow rate, and a temperature rise value due to the influence of a spit back flow rate from the multi-cylinder engine is subtracted from the intake air temperature. The information processing device acquires each measurement value from the high-response flow sensor, the pressure sensor, the first temperature sensor, and the second temperature sensor, and determines whether the behavior of the engine is steady or transient from a differential value obtained by differentiating the intake pressure among the acquired measurement values. When it is determined that the engine is in the transient state, the information processing device calculates the valve passing air flow rate using the arithmetic expression and the measurement values ​​of each of the sensors, and when it is determined that the engine is in the steady state, the information processing device performs a temperature compensation process to make the intake air temperature and the atmospheric temperature the same value, and then calculates the valve passing air flow rate using the arithmetic expression and the measurement values ​​of each of the sensors.

[0011] In this way, the air flow rate calculation system of the present invention determines whether the engine is in a steady state or a transient state. In the present invention, when the multi-cylinder engine is in a transient state, the valve-passing air flow rate flowing into the intake pipe is calculated using the above calculation formula, which subtracts the "temperature rise due to the blowback flow rate from the multi-cylinder engine" from the intake air temperature. In the present invention, when the multi-cylinder engine is in a steady state, the air flow rate calculation system calculates the valve-passing air flow rate flowing into the intake pipe using the above calculation formula after performing temperature compensation processing corresponding to steady state behavior, which sets the atmospheric air temperature and the intake air temperature to the same value. According to this configuration, it is possible to calculate a valve passing air flow rate that is close to the true value whether the engine is in a "steady" or "transient" state.

[0012] Further, it is preferable that the temperature rise due to the influence of the flow rate of the blowback from the engine is a difference value between the intake air temperature when the behavior of the engine is steady and the atmospheric air temperature.

[0013] It is also preferable that the calculation formula is the following formula (A).

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[0014] According to the present invention, it is possible to provide an air flow rate calculation system that can calculate the valve passing air flow rate of a multi-cylinder engine with high accuracy. [Brief description of the drawings]

[0015] [Figure 1] 1 is a schematic diagram showing a configuration of an air flow rate calculation system for a multi-cylinder engine according to an embodiment of the present invention; [Diagram 2] FIG. 11 is a schematic diagram for explaining the temperature rise value due to the influence of the blowback flow rate from the engine, which is reflected in the calculation formula used by the air flow rate calculation system of the embodiment of the present invention to calculate the air flow rate passing through a valve, in which (a) is a schematic diagram showing the average flow rate in one cycle of the engine, and (b) is a schematic diagram showing the relationship between the ambient temperature measured by the system at each time of one cycle shown in (a) and the intake temperature of the air flowing into the intake pipe measured by the system. [Diagram 3]FIG. 1 is a schematic diagram showing the valve passing air flow rate of a multi-cylinder engine calculated by an air flow rate calculation system of an embodiment of the present invention, a reference for the valve passing air flow rate of a multi-cylinder engine, and a valve passing air flow rate calculated by a calculation formula of the conventional art, where (a) and (b) are schematic diagrams showing the relationship between the reference for the valve passing air flow rate of a multi-cylinder engine and the valve passing air flow rate calculated by the calculation formula of the conventional art, and (c) and (d) are schematic diagrams showing the relationship between the reference for the valve passing air flow rate, the valve passing air flow rate calculated by the calculation formula of the conventional art, and the valve passing air flow rate calculated by the air flow rate calculation system of this embodiment. [Figure 4] 4 is a schematic diagram showing a comparison between the valve passing air flow rate calculated by the air flow rate calculation system according to the embodiment of the present invention and a reference of the valve passing air flow rate flowing into each cylinder of a multi-cylinder engine; FIG. [Diagram 5] 4 is a schematic diagram showing a comparison between the valve passing air flow rate calculated by the air flow rate calculation system according to the embodiment of the present invention and a reference of the valve passing air flow rate flowing into each cylinder of a multi-cylinder engine; FIG. [Figure 6] 1 is a schematic diagram for explaining an arithmetic expression for calculating a valve-passing air flow rate passing through an intake pipe that introduces air into cylinders of a multi-cylinder engine of the prior art; FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An air flow rate calculation system according to an embodiment of the present invention will now be described with reference to the drawings.

[0017] First, the configuration of an air flow rate calculation system for a multi-cylinder engine according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic diagram showing the configuration of an air flow rate calculation system for a multi-cylinder engine according to this embodiment.

[0018] As shown in the figure, the air flow calculation system W for a multi-cylinder engine of this embodiment includes a high-response flow sensor 10 that measures the air flow rate (ml) flowing into an intake pipe 7 of a multi-cylinder engine EG (hereinafter simply referred to as "engine EG") installed on an engine bench (engine testing device) not shown, a pressure sensor 20 that measures the pressure of the air flowing into the engine EG (intake pressure (Pin)), a temperature sensor 30 that measures the temperature of the air passing through the intake pipe 1 that flows air into the cylinders of the engine EG (intake air temperature (Tin)), a temperature sensor 40 that measures the ambient air temperature, and an information processing device 100 that acquires measurement values ​​measured by each measuring device (each sensor: high-response flow sensor 10, pressure sensor 20, temperature sensors 30, 40) and calculates the flow rate of air passing through the intake pipe 1 that flows air into the cylinders of the engine EG (valve air flow rate (miv)) using the acquired measurement values ​​and a preset calculation formula.

[0019] The engine EG has three cylinders (not shown) and three intake pipes 1a, 1b, 1c connected to the respective cylinders. One end of each of the three intake pipes 1a, 1b, 1c is connected to a cylinder of the engine EG, and the other end is connected to a chamber 3. A throttle valve 5 is provided upstream of the chamber 3. An intake pipe 7 is connected upstream of the throttle valve 5, and a high-response flow sensor 10 is connected to an end of the intake pipe 7.

[0020] Moreover, the high response flow sensor 10 measures the air flow rate (ml) of the air flowing into the intake pipe 7. Moreover, the high response flow sensor 10 is electrically connected to the information processing device 100, and upon measuring the air flow rate (ml), transmits the measured air flow rate (ml) to the information processing device 100. The air flow rate (ml) measured by the high response flow sensor 10 can be considered to be substantially the same value as the flow rate of air flowing into the throttle valve 5 through the intake pipe 7 (for convenience of explanation, this will be referred to as the "throttle intake flow rate (mth)"). That is, in this embodiment, the high response flow sensor 10 measures the throttle intake flow rate (mth). The high-response flow sensor 10 is an air flow meter that is more responsive to fluctuations in air flow than a hot-wire airflow sensor. For example, a laminar flow meter (laminar flow type flow meter) or an ultrasonic flow meter can be used as the high-response flow sensor 10. In the illustrated example, the high-response flow sensor 10 is a laminar flow meter.

[0021] The pressure sensor 20 is connected to the intake pipe 1 and is installed inside the chamber 3 through which air flows into the intake pipe 1, and measures the pressure (intake pressure (Pin)) of the air flowing into the chamber 3. The pressure sensor 20 is also electrically connected to the information processing device 100, and upon measuring the intake pressure (Pin) inside the chamber 3, transmits the measured intake pressure (Pin) to the information processing device 100.

[0022] The temperature sensor 30 is installed inside the intake pipe 1a and measures the temperature of the air flowing into the intake pipe 1a (intake air temperature (Tin)). The temperature sensor 30 is also electrically connected to the information processing device 100, and upon measuring the intake air temperature (Tin), transmits the measured intake air temperature (Tin) to the information processing device 100. In this embodiment, the temperature sensor 30 is installed in one of the three intake pipes 1a, 1b, and 1c, ie, the intake pipe 1a, to measure the intake temperature (Tin) of the air flowing into the intake pipe 1a, but this is not particularly limited. The temperature sensor 30 may be installed in each of the three intake pipes 1a, 1b, and 1c, to measure the intake temperature (Tin) for each intake pipe 1. It is preferable to use a fast response thermocouple (for example, a fast response thermocouple manufactured by Medotherm, Inc., USA or Ambesmt Co., Ltd.) as the temperature sensor 30.

[0023] The temperature sensor 40 is a sensor for measuring atmospheric pressure, and is installed in a position near the engine EG. The temperature sensor 40 is also electrically connected to the information processing device 100, and when it measures the atmospheric temperature (Tat), it transmits the measured atmospheric temperature (Tat) to the information processing device 100.

[0024] In addition, the engine bench (engine testing device), not shown, is equipped with a dynamometer that applies load to the engine EG being tested, a shaft that connects the rotating shaft of the dynamometer to the rotating shaft of the engine EG, a dynamo control device that controls the operation of the dynamometer, and an engine control device that controls the operation of the engine EG. This engine bench controls the operation of the engine EG, and while the engine EG is running, the high-response flow sensor 10 measures the air flow rate (ml), the pressure sensor 20 measures the intake pressure (Pin), the temperature sensor 30 measures the intake air temperature (Tin), and the temperature sensor 40 measures the ambient air temperature (Tat). Note that the engine bench used is a well-known technology, so a detailed description will be omitted.

[0025] The information processing device 100 has a data acquisition unit 110 that acquires measurement values ​​(air flow rate (ml), intake pressure (Pin), intake temperature (Tin), ambient temperature (Tat)) measured by each measuring device (sensor: high-response flow sensor 10, pressure sensor 20, temperature sensors 30, 40), and an air flow calculation unit 120 that calculates the air flow rate passing through the valve (miv) using each measurement value acquired by the data acquisition unit 10 and a "preset calculation formula."

[0026] Furthermore, the hardware configuration of the information processing device 100 is not particularly limited, but for example, the information processing device 100 can be configured by a computer or ECU (engine control unit) equipped with a CPU, an auxiliary storage device, a main storage device, a network interface, and an input / output interface. In this case, various sensors (high-response flow sensor 10, pressure sensor 20, temperature sensors 30, 40) are connected to the input / output interface. Furthermore, the auxiliary storage device stores programs for realizing the functions of the "data acquisition unit 110, air flow calculation unit 120". The functions of the "data acquisition unit 110, air flow calculation unit 120" are realized by the CPU loading the programs into the main storage device and executing them. In addition, the information processing device 100 is assumed to store the volume (Vin) of the intake pipe 1 of the engine EG prior to the calculation process of the air flow rate through the valve (miv) (the volume (Vin) of the intake pipe 1 is stored in the memory (main memory device or auxiliary memory device) of the information processing device 100).

[0027] The data acquisition unit 10 receives each measurement value (air flow rate (ml), intake pressure (Pin), intake temperature (Tin), and ambient temperature (Tat)) transmitted from each measurement device (high-response flow sensor 10, pressure sensor 20, and temperature sensors 30 and 40).

[0028] The air flow rate calculation unit 120 acquires each measurement value (air flow rate (ml), intake pressure (Pin), intake temperature (Tin), and ambient temperature (Tat)) via the data acquisition unit 10.

[0029] In addition, the air flow rate calculation unit 120 differentiates the received intake pressure (Pin) (by time differentiation or by cycle average), and if the differentiated value is greater than a predetermined threshold value (for example, the threshold value is set to "0"), it determines that the engine EG is in a transient state, and if the differentiated value is equal to or less than the predetermined threshold value, it determines that the engine EG is in a steady state.

[0030] In addition, when the engine EG is determined to be in a transient behavior, the air flow calculation unit 120 calculates the valve passing air flow rate (miv) passing through the intake manifold 1 that brings air into the cylinders of the engine EG using the acquired measurement values ​​(air flow rate (ml), intake pressure (Pin), intake temperature (Tin), ambient temperature (Tat)), the stored volume (Vin) of the intake manifold 1, and the following (Equation A) and (B).

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[0031] The air flow rate (ml) flowing into the intake pipe 7 measured by the high response flow sensor 10 can be considered to be the same value as the air flow rate (throttle intake flow rate (mth)) flowing through the intake pipe 7 into the throttle valve 5. Therefore, as shown in (Equation B), the air flow rate calculation unit 120 substitutes the received air flow rate (ml) as the throttle intake flow rate (mth) into (Equation A) to calculate the air flow rate passing through the valve (miv).

[0032] In addition, when the engine EG is determined to be in steady behavior, the air flow rate calculation unit 120 performs temperature compensation processing corresponding to steady behavior, in which the atmospheric temperature (Tat) and the intake temperature (Tin) are made the same value, as shown in the following (equation C), and then calculates the valve passing air flow rate (miv) passing through the intake pipe 1 of the engine EG using the received (air flow rate (ml), intake pressure (Pin), intake temperature (Tin), atmospheric temperature (Tat)), the stored volume (Vin) of the intake pipe 1, and the above (equations A) and (B).

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[0033] Furthermore, "Tinconst" in the above (Equation A) indicates the intake air temperature (Tin) when the engine EG is in a steady state, and "Tinconst-Tat" indicates the temperature rise value due to the influence of the spit-back flow rate from the engine EG. In other words, (Equation A) is an arithmetic formula in which the temperature rise value (Tinconst-Tat) due to the influence of the spit-back flow rate from the engine EG is subtracted from the intake air temperature (Tin).

[0034] Here, the temperature rise value (Tinconst-Tat) due to the influence of the blowback flow rate from the engine EG will be described with reference to FIG. FIG. 2 is a schematic diagram for explaining the temperature rise value due to the influence of the blowback flow rate from the engine, which is reflected in the calculation formula used by the air flow rate calculation system of this embodiment to calculate the air flow rate passing through the valve, in which (a) is a schematic diagram showing the average flow rate in one cycle of the engine, and (b) is a schematic diagram showing the relationship between the ambient temperature measured by the system at each time of one cycle shown in (a) and the intake temperature of the air flowing into the intake pipe measured by the system.

[0035] As shown in the figure, the intake temperature (Tin) of the air flowing into the intake pipe 1 remains at a substantially constant value of "Tinconst" when the engine EG is in steady state behavior, and when the engine EG changes from steady state behavior to transient behavior, it rises from the "Tinconst" value in a substantially inverted V-shaped waveform, and when the engine EG changes from transient behavior to steady state behavior, it returns to the "Tinconst" value. The ambient air temperature (Tаt) remains at an approximately constant value, and the temperature difference between this ambient air temperature (Tat) and “Tinconst”, which is the value of the intake air temperature (Tin) when the engine EG is operating at a steady state, is the temperature rise value due to the backflow rate from the engine EG.

[0036] In this manner, in this embodiment, when the engine EG is undergoing transient behavior, the air flow rate (miv) flowing into the intake pipe 1 is calculated by subtracting the "temperature rise due to the backflow rate from the engine (Tinconst-Tat)" from the intake air temperature (Tin) as shown in the above (Equation A), while reflecting the temperature change corresponding to the transient behavior. Furthermore, according to this embodiment, when the engine EG is operating in a steady state, a temperature compensation process corresponding to the steady state behavior is performed to set the ambient temperature (Tat) and the intake temperature (Tin) to the same value, and the air flow rate (miv) flowing into the intake pipe 1 is calculated using the above (Equation A). According to this configuration, it is possible to calculate a valve passage air flow rate (miv) that is close to the true value regardless of whether the behavior of the engine EG is "steady" or "transient".

[0037] In the engine EG of this embodiment, the intake stroke is divided for each cylinder, and air flows into each cylinder in turn. Therefore, in this embodiment, air flows into the intake pipe 1a during the intake stroke of the first cylinder, air flows into the intake pipe 1b during the intake stroke of the second cylinder, and air flows into the intake pipe 1c during the intake stroke of the third cylinder. As a result, the air flow rate calculation unit 120 of the information processing device 100 can calculate the valve passing air flow rate (miv) for each intake pipe 1 (i.e., for each cylinder).

[0038] Next, the relationship between the "air flow rate passing through the valve" calculated by the air flow rate calculation system W of the multi-cylinder engine of this embodiment, the "air flow rate passing through the valve" calculated by the calculation formula shown in the above-mentioned conventional technology, and the true value (reference) of the air flow rate passing through the valve will be explained using Figure 3.

[0039] FIG. 3 is a schematic diagram showing the valve passing air flow rate of a multi-cylinder engine calculated by the air flow rate calculation system of this embodiment, a reference for the valve passing air flow rate of a multi-cylinder engine, and the valve passing air flow rate calculated by a calculation formula of the conventional technology, where (a) and (b) are schematic diagrams showing the relationship between the reference for the valve passing air flow rate of a multi-cylinder engine and the valve passing air flow rate calculated by the calculation formula of the conventional technology, and (c) and (d) are schematic diagrams showing the relationship between the reference for the valve passing air flow rate, the valve passing air flow rate calculated by the calculation formula of the conventional technology, and the valve passing air flow rate calculated by the air flow rate calculation system of this embodiment.

[0040] In the graphs of Figures 3(a) and (b), the solid line indicates the change over time of the true value (reference) of the air flow rate passing through the valve of the engine EG, the dashed line indicates the change over time of the "air flow rate passing through the valve (estimated flow rate) calculated using the calculation equation (Equation 1) of the conventional technology described above," and the dotted line indicates the change over time of the "air flow rate passing through the valve (estimated flow rate) calculated using the calculation equation (Equation 2) of the conventional technology described above." In the graphs of Figures 3(c) and (d), the solid line indicates the change over time of the true value (reference) of the air flow rate passing through the valve, the dashed line indicates the change over time of the "air flow rate passing through the valve (estimated flow rate) calculated using the calculation equation (Equation 1) of the conventional technology described above," and the dotted line indicates the change over time of the "air flow rate passing through the valve (estimated flow rate) calculated by the air flow rate calculation system W of this embodiment."

[0041] FIG. 3(b) shows an enlarged view of the portion of the air flow rate passing through the valve that is undergoing the transient behavior shown in FIG. 3(a). FIG. 3(d) shows an enlarged view of the portion of the air flow rate passing through the valve that is undergoing the transient behavior shown in FIG. 3(c). For the sake of convenience, the above-mentioned conventional calculation formulas (Formula 1) and (Formula 2) are shown below again.

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[0042] As shown in Figures 3(a) and (b), the estimated flow rate calculated using the calculation formula (Equation 1) of the conventional technology shows a value close to the reference when the engine EG is in steady-state behavior, but shows a value that differs greatly from the reference when the engine EG is in transient behavior. Furthermore, as shown in Figures 3(a) and (b), the estimated flow rate calculated using the calculation formula (Equation 2) of the conventional technology shows a value that is slightly different from the reference when the engine EG is performing transient behavior, but shows a value that is significantly different from the reference when the engine EG is performing steady-state behavior. Thus, it is clear that the conventional calculation formulas ((Formula 1) and (Formula 2)) cannot accurately calculate the valve passing air flow rate (estimated flow rate) flowing into the intake pipe 1 of the multi-cylinder engine EG.

[0043] On the other hand, as shown in FIG. 3(c), the "air flow rate passing through the valve (estimated flow rate)" calculated by the air flow rate calculation system W of this embodiment has a small difference from the reference value when the engine EG is in a steady state. Also, as shown in FIG. 3(d), it can be seen that the "valve passing air flow rate (estimated flow rate)" calculated by the air flow rate calculation system W of this embodiment has a small difference from the reference even when the engine EG is in a transient state. In addition, when the engine EG is in a transient state, the "air flow rate passing through the valve" calculated by the air flow rate calculation system W of this embodiment has a smaller difference from the reference when compared with the air flow rate passing through the valve (estimated flow rate) calculated by the calculation formula (Formula 1) of the conventional technology. In this way, the air flow rate calculation system W of this embodiment can calculate a valve-passing air flow rate (estimated flow rate) that is close to the true value whether the engine EG is in a “steady” or “transient” state, and the calculation accuracy of the valve-passing air flow rate is improved compared to when the conventional technology's calculation equations (Equation 1, Equation 2) are used.

[0044] Next, the relationship between the "air flow rate through the valve (estimated flow rate)" calculated by the air flow rate calculation system W of the multi-cylinder engine of this embodiment and the true value (reference) of the air flow rate flowing into each cylinder of the engine EG will be explained using Figures 4 and 5.

[0045] Here, Figures 4 and 5 are schematic diagrams showing a comparison between the valve-passing air flow rate (estimated flow rate) calculated by the air flow rate calculation system of this embodiment and the true value (reference) of the valve-passing air flow rate flowing into each cylinder of a multi-cylinder engine.

[0046] In addition, in Figure 4, the solid line indicates the ``valve-passing air flow rate (estimated flow rate)'' calculated by the air flow rate calculation system W of this embodiment, the dotted line (◯) indicates the valve-passing air flow rate (reference) flowing into cylinder 1 (not shown), the dashed line (△) indicates the air flow rate (reference) flowing into cylinder 2 (not shown), and the dot (□) indicates the valve-passing air flow rate (reference) flowing into cylinder 3 (not shown). In addition, in Figure 5, a circle indicates the valve-passing air flow rate (reference) flowing into cylinder 1a through intake pipe 1, a triangle indicates the valve-passing air flow rate (reference) flowing into cylinder 2 through intake pipe 1b, and a square indicates the valve-passing air flow rate (reference) flowing into cylinder 3 (intake pipe 1c) through intake pipe 1c.

[0047] As shown in Figures 4 and 5, the valve-passing air flow rate (estimated flow rate) of the engine EG calculated by the multi-cylinder engine air flow rate calculation system W of this embodiment has a slight quantitative error with respect to the true value (reference) of the valve-passing air flow rate flowing into each cylinder, but it can be seen that there is a correlation and therefore it can be evaluated in terms of checking the differences between the cylinders (it can be evaluated that the valve-passing air flow rate is calculated with high accuracy).

[0048] As described above, according to this embodiment, it is possible to provide an air flow rate calculation system W that can calculate the valve-passing air flow rate flowing into a multi-cylinder engine with high accuracy.

[0049] The present invention is not limited to the above-described embodiment, and various modifications are possible within the scope of the present invention.

[0050] For example, in the above-described embodiment, the information processing device 100 is electrically connected to each sensor (high-response flow sensor, pressure sensor 20, thermometers 30, 40) and receives the measurement values ​​output from each sensor, but is not particularly limited to this. A user of the air flow calculation system W may operate the information processing device 100 to input the measurement values ​​measured by each sensor (high-response flow sensor, pressure sensor 20, thermometers 30, 40) to the information processing device 100. Also, for example, in the above-described embodiment, whether the engine EG is in a transient or steady state behavior is determined based on a differential value obtained by differentiating the intake pressure (Pin) measured by the pressure sensor 20, but the present invention is not limited to this. The determination of whether the engine EG is in a steady state behavior or a transient behavior may be performed based on a signal value other than the differential value of the intake pressure (Pin). [Explanation of symbols]

[0051] EG: Multi-cylinder engine 1, 1a, 1b, 1c...intake pipe 3. Chamber 5...Throttle valve 7…Intake pipe W…Air flow rate calculation system 10...High-response flow sensor 20...Pressure sensor 30...Temperature sensor 40...Temperature sensor 100...Information processing device 110…Data acquisition section 120...Air flow rate calculation unit

Claims

1. An air flow rate calculation system for calculating a valve-passing air flow rate passing through an intake pipe that introduces air into a cylinder of a multi-cylinder engine, comprising: a high-response flow rate sensor that measures a throttle intake flow rate, which is an air flow rate flowing into a throttle valve of the multi-cylinder engine; a pressure sensor connected to the intake pipe for measuring an intake pressure in a chamber through which air flows into the intake pipe; a first temperature sensor that measures an intake temperature of air flowing into the intake pipe; A second temperature sensor for measuring an atmospheric temperature; an information processing device that calculates the valve passing air flow rate using a preset calculation formula and the measurement values ​​of each of the sensors; the calculation formula is for calculating the valve passing air flow rate from the throttle intake air flow rate, the intake pressure, the volume of the intake pipe, the intake temperature, the atmospheric temperature, and a gas constant, and a temperature rise value due to the influence of the blowback flow rate from the multi-cylinder engine is subtracted from the intake temperature; The information processing device includes: acquiring measured values ​​from the high-response flow rate sensor, the pressure sensor, the first temperature sensor, and the second temperature sensor, and determining whether the behavior of the engine is steady or transient from a differential value obtained by differentiating an intake pressure among the acquired measured values; When it is determined that the flow is transient, the flow rate of air passing through the valve is calculated using the arithmetic expression and the measurement values ​​of each of the sensors; When it is determined that the engine is in a steady state, a temperature compensation process is performed to make the intake air temperature and the atmospheric air temperature the same value, and then the air flow rate passing through the valve is calculated using the calculation formula and the measurement values ​​of each of the sensors.

2. 2. The air flow rate calculation system according to claim 1, wherein the temperature rise due to the influence of the flow rate of the blowback air from the engine is a difference value between the intake air temperature when the engine is in a steady state and the atmospheric air temperature.

3. 2. The air flow rate calculation system according to claim 1, wherein the calculation formula is the following formula (A): [0010]

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