Intake air amount measuring device and engine

Abstract

[Problem] To provide an intake air measuring device and an engine capable of suppressing a case where a measured result of a flow rate of intake air flowing in an intake pipe depends on a shape of the intake pipe, and stably measuring the flow rate of the intake air. [Means for Solution] An intake air measuring device (200) has: an intake air distribution mechanism (3) that distributes intake air (CYL) to cylinders (11, 12, 13, 14); a temperature detection mechanism (202) that detects a temperature (Ti) of the intake air (CYL); a pressure detection mechanism (201) that detects a pressure (Pi) of the intake air (CL); and an arithmetic portion (100) that, based on the temperature (Ti) transmitted from the temperature detection mechanism (202) and the pressure (Pi) transmitted from the pressure detection mechanism (201), calculates an intake air amount (mfcyl) of the intake air (CYL). The temperature detection mechanism (202) detects the temperature (Ti) of the intake air (CYL) at a region (W) that is located across a first branch portion (31) and a second branch portion (32) in an interior of the intake air distribution mechanism (3).

Description

TECHNICAL FIELD

[0001] The present application relates to an intake air amount measuring device that measures a flow rate of intake air flowing in an intake air pipe of an engine, and an engine. BACKGROUND

[0002] An intake air control device of an engine having a MAF sensor is disclosed in Patent Literature 1. The MAF sensor described in Patent Literature 1 is provided on an intake pipe on an upstream side of a turbocharger to detect a flow rate of intake air flowing in the intake pipe. As the engine disclosed in Patent Literature 1, generally, in an internal combustion engine such as a diesel engine, a hot-wire type intake air amount sensor (MAF sensor) for detecting an intake air amount of air (intake air) flowing in an intake air pipe is provided on the intake air pipe. Further, the intake air amount is a flow rate of air (intake air) flowing in the intake air pipe, and is also referred to as an intake air flow rate or MAF, etc.

[0003] However, there is a problem that an output characteristic of the intake air amount sensor provided on the intake air pipe depends on a shape of an intake air system (for example, the intake air pipe) on an upstream side of the intake air amount sensor. The intake air system on the upstream side of the intake air amount sensor differs, for example, depending on each application in which an industrial diesel engine or the like is mounted. Therefore, a calibration work of the intake air amount sensor is necessary for each application in which the engine is mounted, and is complicated.

[0004] PRIOR ART DOCUMENTS

[0005] PATENT LITERATURE

[0006] Patent Literature 1: Japanese Patent Application Publication No. 2010-285957 SUMMARY

[0007] PROBLEMS TO BE SOLVED BY THE INVENTION

[0008] The present application has been achieved in order to solve the above-described problems, and has an object to provide an intake air amount measuring device and an engine capable of suppressing a case where a measurement result of a flow rate of intake air flowing in an intake air pipe depends on a shape of the intake air pipe, and capable of stably measuring the flow rate of the intake air.

[0009] MEANS FOR SOLVING THE PROBLEMS

[0010] The above problems are solved by the intake air amount measuring device of the present application, which measures a flow rate of intake air of an engine having three or more cylinders arranged in line, wherein the intake air amount measuring device includes: an intake air distribution mechanism that distributes the intake air to the cylinders of the engine; a temperature detecting mechanism that detects a temperature of the intake air; a pressure detecting mechanism that detects a pressure of the intake air; and a calculation unit that calculates the flow rate based on the temperature transmitted from the temperature detecting mechanism and the pressure transmitted from the pressure detecting mechanism, a length direction of the intake air distribution mechanism is along a direction in which the cylinders of the engine are arranged, the intake air flows into the intake air distribution mechanism from one end of the length direction, the temperature detecting mechanism detects the temperature of the intake air at a region that straddles a first branch portion of the intake air distribution mechanism and a second branch portion of the intake air distribution mechanism, the first branch portion is connected to a first cylinder of the engine that is disposed at a position farthest from the one end in the length direction, and the second branch portion is connected to a second cylinder of the engine that is disposed at a position next to the first cylinder from the one end in the length direction.

[0011] According to the intake air amount measuring device of the present application, the length direction of the intake air distribution mechanism that distributes the intake air to the cylinders of the engine is along the direction in which the cylinders of the engine are arranged. The intake air of the engine flows into the intake air distribution mechanism from one end of the length direction of the intake air distribution mechanism. Also, the calculation unit calculates the flow rate of the intake air based on the temperature of the intake air transmitted from the temperature detecting mechanism and the pressure of the intake air transmitted from the pressure detecting mechanism. The temperature detecting mechanism detects the temperature of the intake air at a region that straddles a first branch portion of the intake air distribution mechanism and a second branch portion of the intake air distribution mechanism. The first branch portion is connected to a first cylinder of the engine that is disposed at a position farthest from the one end of the intake air distribution mechanism in the length direction of the intake air distribution mechanism. The second branch portion is connected to a second cylinder of the engine that is disposed at a position next to the first cylinder from the one end of the intake air distribution mechanism in the length direction of the intake air distribution mechanism. In this way, the temperature detecting mechanism detects the temperature of the intake air at a region in which the flow of the intake air in the region within the intake air distribution mechanism is relatively stable. Also, the calculation unit calculates the flow rate of the intake air based on the temperature of the intake air transmitted from the temperature detecting mechanism and the pressure of the intake air transmitted from the pressure detecting mechanism, without depending on an intake air amount sensor (MAF sensor) that detects the flow rate of the intake air flowing in an intake air pipe. Thus, the intake air amount measuring device of the present application can suppress a case in which the measurement result of the flow rate of the intake air flowing in the intake air pipe depends on the shape of the intake air pipe, and can stably measure the flow rate of the intake air.

[0012] In the intake air amount measuring device of the present application, it is preferable that the pressure detecting mechanism detects the pressure of the intake air at the region.

[0013] According to the intake air amount measuring apparatus of the present application, the pressure detecting mechanism detects the pressure of intake air in a region where the flow of intake air is relatively stable, like the temperature detecting mechanism, in a region in the intake air distributing mechanism. Also, the operation portion operates the flow rate of intake air based on the temperature of intake air transmitted from the temperature detecting mechanism and the pressure of intake air transmitted from the pressure detecting mechanism, not depending on the intake air amount sensor (MAF sensor). Thus, the intake air amount measuring apparatus of the present application can further suppress the case where the measurement result of the flow rate of intake air flowing in the intake air pipe depends on the shape of the intake air pipe, and can further stably measure the flow rate of intake air.

[0014] In the intake air amount measuring apparatus of the present application, it is preferable that the pressure detecting mechanism detects the pressure of intake air at a position closer to the one end than the intake air whose temperature is detected by the temperature detecting mechanism in the length direction.

[0015] According to the intake air amount measuring apparatus of the present application, the pressure detecting mechanism detects the pressure of intake air at a position closer to the one end of the intake air distributing mechanism than the intake air whose temperature is detected by the temperature detecting mechanism in the length direction of the intake air distributing mechanism. Thus, the pressure detecting mechanism does not detect intake air in a region where the flow is disturbed by a probe or the like of the temperature detecting mechanism provided in the intake air distributing mechanism, for example, but detects the pressure of intake air in a more stable region before the flow is disturbed. Thus, the pressure detecting mechanism can more stably detect the pressure of intake air. Thus, the intake air amount measuring apparatus of the present application can further suppress the case where the measurement result of the flow rate of intake air flowing in the intake air pipe depends on the shape of the intake air pipe, and can further stably measure the flow rate of intake air.

[0016] In the intake air amount measuring apparatus of the present application, it is preferable that the intake air amount measuring apparatus further has: an exhaust gas recirculation mechanism that recirculates exhaust gas of the engine; and a differential pressure detecting mechanism that detects a differential pressure between the exhaust gas flowing in the exhaust gas recirculation mechanism and the intake air flowing in the intake air distributing mechanism, and transmits to the operation portion, the operation portion further operates the flow rate based on the differential pressure transmitted from the differential pressure detecting mechanism, the differential pressure detecting mechanism detects the differential pressure based on the pressure of the intake air in the region.

[0017] The intake air amount measuring device according to the present application further has an exhaust gas recirculation mechanism that recirculates exhaust gas of the engine and a differential pressure detecting mechanism. The operation section further operates the flow rate of the intake air based on the differential pressure between the exhaust gas and the intake air transmitted from the differential pressure detecting mechanism. The differential pressure detecting mechanism detects the differential pressure between the exhaust gas flowing in the exhaust gas recirculation mechanism and the intake air flowing in the intake air distribution mechanism and transmits to the operation section. Here, the differential pressure detecting mechanism detects the differential pressure between the exhaust gas and the intake air based on the pressure of the intake air in the region that straddles the first branch section and the second branch section. That is, the detection region of the pressure of the intake air detected by the differential pressure detecting mechanism is the same as the detection region of the pressure of the intake air detected by the pressure detecting mechanism, that is, the region that straddles the first branch section and the second branch section. Thus, in the case where the exhaust gas recirculation mechanism that recirculates the exhaust gas of the engine is provided, the intake air amount measuring device according to the present application can improve the operation accuracy of the flow rate of the intake air flowing in the intake air pipe.

[0018] In the intake air amount measuring device according to the present application, it is preferable that the differential pressure detecting mechanism detect the differential pressure based on the pressure of the intake air in the length direction at a position closer to the one end than the intake air whose temperature is detected by the temperature detecting mechanism.

[0019] The intake air amount measuring device according to the present application, the differential pressure detecting mechanism detects the differential pressure between the exhaust gas and the intake air based on the pressure of the intake air in the length direction of the intake air distribution mechanism at a position closer to the one end of the intake air distribution mechanism than the intake air whose temperature is detected by the temperature detecting mechanism. Thus, the differential pressure detecting mechanism does not detect the differential pressure between the exhaust gas and the intake air based on the pressure of the intake air in the region where the flow is disturbed by the probe or the like of the temperature detecting mechanism provided in the intake air distribution mechanism, for example, but based on the pressure of the intake air in the more stable region before the flow is disturbed. Thus, the differential pressure detecting mechanism can more stably detect the differential pressure between the exhaust gas and the intake air. Thus, in the case where the exhaust gas recirculation mechanism that recirculates the exhaust gas of the engine is provided, the intake air amount measuring device according to the present application can further improve the operation accuracy of the flow rate of the intake air flowing in the intake air pipe.

[0020] In the intake air amount measuring device according to the present application, it is preferable that the differential pressure detecting mechanism detect the differential pressure based on the pressure of the intake air in the length direction at the same position as the intake air whose pressure is detected by the pressure detecting mechanism.

[0021] According to the intake air amount measuring apparatus of the present application, the differential pressure detecting mechanism detects the differential pressure between the exhaust gas and the intake air based on the pressure of the intake air located at the same position in the length direction of the intake air distribution mechanism as the intake air whose pressure is detected by the pressure detecting mechanism. That is, the detection position of the pressure of the intake air detected by the differential pressure detecting mechanism is the same as the detection position of the pressure of the intake air detected by the pressure detecting mechanism, i.e., a position across the region of the first branch portion and the second branch portion. Therefore, the pressure of the intake air in the intake air distribution mechanism for detecting the differential pressure by the differential pressure detecting mechanism and the pressure of the intake air in the intake air distribution mechanism detected by the pressure detecting mechanism are synchronized with each other in time. Therefore, the arithmetic portion calculates the flow rate of the intake air flowing in the intake air distribution mechanism and the flow rate of the exhaust gas flowing in the exhaust gas recirculation mechanism based on one system, i.e., the same state, of the intake air distribution mechanism. Thus, in the case where the exhaust gas recirculation mechanism that recirculates the exhaust gas of the engine is provided, the intake air amount measuring apparatus of the present application can further improve the calculation accuracy of the flow rate of the intake air flowing in the intake air pipe.

[0022] In the intake air amount measuring apparatus of the present application, it is preferable that the differential pressure detecting mechanism detects the differential pressure based on the pressure of the exhaust gas located between the cooling mechanism that cools the exhaust gas flowing in the exhaust gas recirculation mechanism and the flow rate adjusting mechanism that adjusts the flow rate of the exhaust gas flowing in the exhaust gas recirculation mechanism on the downstream side of the cooling mechanism.

[0023] According to the intake air amount measuring apparatus of the present application, the differential pressure detecting mechanism detects the differential pressure between the exhaust gas and the intake air based on the pressure of the exhaust gas located between the cooling mechanism and the flow rate adjusting mechanism provided on the downstream side of the cooling mechanism. Thus, the arithmetic portion can estimate the deterioration condition or the deterioration degree of the cooling mechanism based on the differential pressure transmitted by the differential pressure detecting mechanism.

[0024] The intake air amount measuring apparatus of the present application preferably further includes a partition provided on the exhaust gas recirculation mechanism located between the cooling mechanism and the flow rate adjusting mechanism, the partition having a hole formed therethrough in a direction intersecting the flow of the exhaust gas flowing in the exhaust gas recirculation mechanism, the differential pressure detecting mechanism detecting the differential pressure based on the pressure of the exhaust gas taken out through the hole of the partition.

[0025] The intake air amount measuring apparatus according to the present application, in the case where a exhaust gas recirculation mechanism that recirculates exhaust gas of an engine is provided, a partition is provided on the exhaust gas recirculation mechanism between a cooling mechanism that cools exhaust gas and a flow rate adjusting mechanism that adjusts the flow rate of exhaust gas. Also, a differential pressure detecting mechanism detects a differential pressure based on the pressure of exhaust gas taken out through a hole of the partition. Therefore, the path of a pipe or the like that transmits the pressure of exhaust gas to the differential pressure detecting mechanism is hardly restricted by the structures of the cooling mechanism and the flow rate adjusting mechanism, and can be reliably connected to the partition. In addition, even without changing the structures of the cooling mechanism and the flow rate adjusting mechanism, by changing the structure of the partition, the path of various pipes or the like that transmit the pressure of exhaust gas to the differential pressure detecting mechanism can be easily connected to the partition. Also, the hole of the partition is formed so as to penetrate in a direction that intersects the flow of exhaust gas flowing in the exhaust gas recirculation mechanism. Therefore, the hole of the partition can be prevented from being clogged by particulate matter (PM) contained in exhaust gas. Thus, the differential pressure detecting mechanism can more reliably acquire the pressure (static pressure) of exhaust gas, and detect a differential pressure with higher accuracy based on the pressure (static pressure) of exhaust gas.

[0026] The intake air amount measuring apparatus according to the present application preferably further has: an exhaust gas pressure acquisition path that is connected to the partition and the differential pressure detecting mechanism, and that transmits the pressure of exhaust gas taken out through the hole of the partition to the differential pressure detecting mechanism, at least a portion of the exhaust gas pressure acquisition path that is connected to the partition being made of metal.

[0027] The intake air amount measuring apparatus according to the present application, an exhaust gas pressure acquisition path is connected to the partition and the differential pressure detecting mechanism, and transmits the pressure of exhaust gas taken out through the hole of the partition to the differential pressure detecting mechanism. Also, at least a portion of the exhaust gas pressure acquisition path that is connected to the partition is made of metal. Therefore, the portion of the exhaust gas pressure acquisition path that is connected to the partition can be prevented from being deteriorated or solidified due to the heat of exhaust gas flowing in the exhaust gas recirculation mechanism. Thus, a gap can be prevented from being generated between the portion of the exhaust gas pressure acquisition path that is connected to the partition and the partition, and air outside the exhaust gas pressure acquisition path can be prevented from entering the inside of the exhaust gas pressure acquisition path. Thus, the differential pressure detecting mechanism can detect a differential pressure with higher accuracy. In addition, the portion of the exhaust gas pressure acquisition path that is connected to the partition is made of metal, so the exhaust gas pressure acquisition path can be fastened to the partition by using a threaded structure. Thus, the exhaust gas pressure acquisition path can be prevented from coming off the partition, and the positioning of the exhaust gas pressure acquisition path with respect to the partition can be easily performed.

[0028] Further, the above problems are solved by an engine having an intake air amount measuring device that measures a flow rate of intake air, and having three or more cylinders arranged in line, wherein the intake air amount measuring device includes: an intake air distribution mechanism that distributes the intake air to the cylinders of the engine; a temperature detecting mechanism that detects a temperature of the intake air; a pressure detecting mechanism that detects a pressure of the intake air; and a calculation section that calculates the flow rate based on the temperature transmitted from the temperature detecting mechanism and the pressure transmitted from the pressure detecting mechanism, a length direction of the intake air distribution mechanism is along a direction in which the cylinders of the engine are arranged, the intake air flows into the intake air distribution mechanism from one end of the length direction, the temperature detecting mechanism detects the temperature of the intake air in a region that straddles a first branch portion of the intake air distribution mechanism and a second branch portion of the intake air distribution mechanism, the first branch portion is connected to a first cylinder of the engine that is disposed at a position farthest from the one end in the length direction, and the second branch portion is connected to a second cylinder of the engine that is disposed at a position next to the first cylinder from the one end in the length direction.

[0029] According to the engine having the intake air amount measuring device of the present application, the length direction of the intake air distribution mechanism that distributes the intake air to the cylinders of the engine is along the direction in which the cylinders of the engine are arranged. The intake air of the engine flows into the intake air distribution mechanism from one end of the length direction of the intake air distribution mechanism. Further, the calculation section calculates the flow rate of the intake air based on the temperature of the intake air transmitted from the temperature detecting mechanism and the pressure of the intake air transmitted from the pressure detecting mechanism. The temperature detecting mechanism detects the temperature of the intake air in a region that straddles a first branch portion of the intake air distribution mechanism and a second branch portion of the intake air distribution mechanism. The first branch portion is connected to a first cylinder of the engine that is disposed at a position farthest from the one end of the intake air distribution mechanism in the length direction. The second branch portion is connected to a second cylinder of the engine that is disposed at a position next to the first cylinder from the one end of the intake air distribution mechanism in the length direction. In this way, the temperature detecting mechanism detects the temperature of the intake air in a region in which the flow of the intake air in the region within the intake air distribution mechanism is relatively stable. Further, the calculation section calculates the flow rate of the intake air based on the temperature of the intake air transmitted from the temperature detecting mechanism and the pressure of the intake air transmitted from the pressure detecting mechanism, without depending on an intake air amount sensor (MAF sensor) that detects the flow rate of the intake air flowing in an intake air pipe. Thus, the engine having the intake air amount measuring device of the present application can suppress a case in which the measurement result of the flow rate of the intake air flowing in the intake air pipe depends on the shape of the intake air pipe, and can stably measure the flow rate of the intake air.

[0030] Effects of the Invention

[0031] According to the present application, it is possible to provide an intake air amount measuring device capable of suppressing a case where a measurement result of a flow rate of intake air flowing in an intake pipe depends on a shape of the intake pipe, and stably measuring the flow rate of the intake air, and an engine. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 is a schematic view showing an engine having the intake air amount measuring device of the embodiment of the present application.

[0033] Figure 2 is a schematic view illustrating a result of a turbulent energy of a CFD (Computational Fluid Dynamics) fluid analysis performed by the present inventors.

[0034] Figure 3 is a schematic view illustrating a result of a pressure of the CFD fluid analysis performed by the present inventors.

[0035] Figure 4 is a schematic view illustrating a result of a temperature of the CFD fluid analysis performed by the present inventors.

[0036] Figure 5 is a perspective view showing a specific structure example of the partition and the exhaust pressure acquisition path of the embodiment.

[0037] Figure 6 is a sectional view showing a structure example of the partition of the embodiment. DETAILED DESCRIPTION

[0038] Hereinafter, a preferred embodiment of the present application will be described in detail with reference to the accompanying drawings.

[0039] In addition, since the embodiments described below are preferred specific examples of the present application, various technically preferred limitations are added, but as long as the description below does not particularly limit the recitations of the present application, the scope of the present application is not limited to these modes. In addition, in each drawing, the same reference numerals are assigned to the same constituent elements and detailed description is appropriately omitted.

[0040] (Outline of Engine 1)

[0041] Figure 1 is a schematic view showing an engine having the intake air amount measuring device of the embodiment of the present application.

[0042] First, an outline of the engine 1 having the intake air amount measuring device of the embodiment will be described. Figure 1The engine 1 shown is an internal combustion engine, for example, an industrial diesel engine. The engine 1 is, for example, a vertical in-line multi-cylinder engine such as a supercharged high-output four-cylinder engine with a turbocharger. The engine 1 is mounted, for example, on a vehicle such as a construction machine, an agricultural machine, a mower, and the like.

[0043] Figure 1 The engine 1 shown has a cylinder head 2, an intake manifold 3, an exhaust manifold 4, a turbocharger 5, an intake throttle valve (intake adjusting portion) 6, an EGR (Exhaust Gas Recirculation) valve 7, an EGR cooler 8, and an intake air amount measuring device 200 having an ECU (Electronic Control Unit) 100. Further, it is also possible not to provide an exhaust gas recirculation mechanism such as the EGR valve 7, the EGR cooler 8, and an EGR gas path 23 described later, which recirculates the exhaust gas of the engine 1. The "manifold" is also referred to as a "manifold". In addition, the intake manifold 3 of the present embodiment is an example of the "intake distribution mechanism" of the present application. The ECU 100 of the present embodiment is an example of the "calculation portion" of the present application. The EGR valve 7 of the present embodiment is an example of the "flow adjusting mechanism" of the present application. The EGR cooler 8 of the present embodiment is an example of the "cooling mechanism" of the present application.

[0044] The cylinder head 2 of the engine 1 is, for example, a cylinder head of a vertical in-line multi-cylinder engine having a first cylinder 11, a second cylinder 12, a third cylinder 13, and a fourth cylinder 14. In the present specification, when viewed in the direction in which the plurality of cylinders are arranged, that is, the direction in which the crankshaft extends, the cylinders from the position of the cylinder disposed far from a portion (mixing portion) 24 at which intake air AR that has passed through the intake throttle valve 6 and exhaust recirculation gas ECG that has passed through the EGR valve 7 are mixed with each other will be sequentially referred to as the first cylinder, the second cylinder, the third cylinder, and the fourth cylinder, from the cylinder disposed close to the position of the portion (mixing portion) 24.

[0045] As Figure 1As shown, the intake manifold 3 comprises a main pipe 35 having a starting end 351 at one end for intake air to flow in; and a first branch pipe 31, a second branch pipe 32, a third branch pipe 33, and a fourth branch pipe 34 branching from the main pipe 35. The starting end 351 in this embodiment is an example of "one end" in the present invention. The first branch pipe 31, the second branch pipe 32, the third branch pipe 33, and the fourth branch pipe 34 in this embodiment are examples of the "first branch portion," "second branch portion," "third branch portion," and "fourth branch portion," respectively, in the present invention. The longitudinal direction of the main pipe 35 is along the direction in which the first cylinder 11, the second cylinder 12, the third cylinder 13, and the fourth cylinder 14 are arranged, i.e., in the direction in which the crankshaft extends. The first branch pipe 31, the second branch pipe 32, the third branch pipe 33, and the fourth branch pipe 34 of the intake manifold 3 are connected to the first cylinder 11, the second cylinder 12, the third cylinder 13, and the fourth cylinder 14, respectively. A fuel injection valve 15 is provided in each combustion chamber of the first cylinder 11, the second cylinder 12, the third cylinder 13, and the fourth cylinder 14. The fuel injection valve 15 is connected to a common rail 16. Fuel from a fuel tank (not shown) is delivered to the common rail 16 by a fuel pump. Under the control of the ECU 100, the common rail 16 accumulates the fuel delivered from the fuel pump. The fuel accumulated in the common rail 16 is injected from the fuel injection valve 15 into each combustion chamber.

[0046] (Turbocharger 5)

[0047] like Figure 1 As shown, the turbocharger 5 includes a turbine 5T and an impeller 5B, which supercharge the intake air delivered to the intake manifold 3. Specifically, the impeller 5B portion is connected to the intake pipe 20 and the intake passage 21. The intake passage 21 is connected to the inlet flange 22 of the intake manifold 3 via the intake throttle valve 6. The turbine 5T portion is connected to the exhaust passage 4B. When exhaust gas EG guided through the exhaust passage 4B of the exhaust manifold 4 is supplied to the turbine 5T of the turbocharger 5, the turbine 5T and the impeller 5B rotate at high speed. Due to the high-speed rotation of the impeller 5B, the intake air AR supplied to and compressed by the impeller 5B of the turbocharger 5 passes through the intake passage 21 and is supercharged to the intake manifold 3.

[0048] The exhaust gas EG exhausted from the turbine 5T is exhausted to the outside of the engine 1 through a DPF (Diesel Particulate Filter) 19 and the like.

[0049] like Figure 1As shown, the start end portion 23M of the EGR gas path 23 as the exhaust gas recirculation path is connected to the exhaust manifold 4. Alternatively, the start end portion 23M of the EGR gas path 23 can be connected to the exhaust passage 4B between the exhaust manifold 4 and the turbine 5T. The EGR gas path 23 of the present embodiment is an example of the "exhaust gas recirculation mechanism" of the present application. The end portion 23N of the EGR gas path 23 is connected to the inlet flange 22 between the intake throttle valve 6 and the start end portion 351 of the intake manifold 3. The EGR valve 7, the EGR cooler 8, and the spacer 400 are provided on the EGR gas path 23. The EGR cooler 8 cools the exhaust gas recirculation gas ECG flowing in the EGR gas path 23.

[0050] The ECU 100 controls the operations of the intake throttle valve 6, the EGR valve 7, the common rail 16, and the like. The intake throttle valve 6 controls the supply amount of the intake air AR supplied to the inlet flange 22 of the intake manifold 3 according to the instruction of the ECU 100 based on the depression amount of the accelerator pedal. The EGR valve 7 adjusts the supply amount of the exhaust gas recirculation gas ECG supplied from the exhaust manifold 4 to the inlet flange 22 of the intake manifold 3 according to the instruction of the ECU 100.

[0051] (Intake amount measuring device 200)

[0052] Next, the intake amount measuring device 200 of the present embodiment will be described.

[0053] The intake amount measuring device 200 has a pressure sensor 201, a temperature sensor 202, an EGR differential pressure sensor 203, and the ECU 100. The pressure sensor 201 of the present embodiment is an example of the "pressure detection mechanism" of the present application. The temperature sensor 202 of the present embodiment is an example of the "temperature detection mechanism" of the present application. The EGR differential pressure sensor 203 of the present embodiment is an example of the "differential pressure detection mechanism" of the present application.

[0054] The pressure sensor 201 detects the pressure Pi of the mixed intake air CYL at the first pressure measuring portion 213 provided in the intake manifold 3 and transmits it to the ECU 100. Specifically, an intake pressure acquisition path 230 of a pipe or the like is connected to the intake manifold 3, the pressure sensor 201, and the EGR differential pressure sensor 203. The pressure sensor 201 detects the pressure Pi of the mixed intake air CYL at the first pressure measuring portion 213 taken out and transmitted through the intake pressure acquisition path 230. The mixed intake air CYL is a gas in which the intake air AR that has passed through the intake throttle valve 6 and the exhaust gas recirculation gas ECG that has passed through the EGR valve 7 are mixed with each other.

[0055] The temperature sensor 202 is provided in the intake manifold 3, detects the temperature Ti of the mixed intake air CYL in the intake manifold 3, and transmits it to the ECU 100.

[0056] The EGR differential pressure sensor 203 detects a differential pressure PP between the pressure Pi of the mixed intake gas CYL at the first pressure measuring portion 213 and the pressure Pe of the exhaust recirculation gas ECG at the second pressure measuring portion 223 provided in the EGR gas path 23, and transmits to the ECU 100. Specifically, as shown in Figure 1 the intake air pressure acquisition path 230 is branched from the intake manifold 3 into a portion connected to the pressure sensor 201 and a portion connected to the EGR differential pressure sensor 203. The EGR differential pressure sensor 203 detects the differential pressure PP based on the pressure Pi of the mixed intake gas CYL at the first pressure measuring portion 213 taken out and transmitted through the intake air pressure acquisition path 230. That is, the EGR differential pressure sensor 203 detects the differential pressure PP based on the pressure Pi of the mixed intake gas CYL at the same position as where the pressure Pi of the mixed intake gas CYL is detected by the pressure sensor 201. In other words, the pressure sensor 201 and the EGR differential pressure sensor 203 detect the pressure Pi of the mixed intake gas CYL at the first pressure measuring portion 213 in the intake manifold 3 in time with each other. In addition, the second pressure measuring portion 223 is provided in the EGR gas path 23 between the EGR cooler 8 and the EGR valve 7. Specifically, the exhaust pressure acquisition path 500 of a pipe or the like is connected to the EGR gas path 23, the EGR differential pressure sensor 203. The EGR differential pressure sensor 203 detects the differential pressure PP based on the pressure Pe of the exhaust recirculation gas ECG at the second pressure measuring portion 223 taken out and transmitted through the exhaust pressure acquisition path 500. Further, the setting positions of the first pressure measuring portion 213 and the temperature sensor 202 are described in detail later.

[0057] As shown in Figure 1 a spacer 400 is provided on the EGR gas path 23 between the EGR cooler 8 as a cooling mechanism and the EGR valve 7 as a flow rate adjustment mechanism. The spacer 400 is made of a metal such as stainless steel or iron having heat resistance, for example. The second pressure measuring portion 223 is preferably provided in the spacer 400 made of a metal. The exhaust pressure acquisition path 500 is connected to the spacer 400, the EGR differential pressure sensor 203.

[0058] The exhaust pressure acquisition path 500 has a first portion 501 connected to the spacer 400 and a second portion 502 connected to the first portion 501 and connected to the EGR differential pressure sensor 203. At least the first portion 501 of the exhaust pressure acquisition path 500 connected to the spacer 400 is made of a metal such as stainless steel or iron having heat resistance, for example. The remaining second portion 502 of the exhaust pressure acquisition path 500 is made of a resin such as an engineering plastic or rubber having flexibility and heat resistance. Referring to Figure 5To explain a specific structure example of the partition 400 and the exhaust pressure acquisition path 500, refer to Figure 6 To explain a structure example of the partition 400.

[0059] Figure 5 is a perspective view showing a specific structure example of the partition and the exhaust pressure acquisition path of the present embodiment.

[0060] Figure 6 is a sectional view showing a structure example of the partition of the present embodiment.

[0061] Further, Figure 6 is a sectional view under a cut surface A-A (refer to Figure 5 ) perpendicular to a flow direction of the exhaust recirculation gas ECG flowing in the EGR gas path 23.

[0062] As shown in Figure 5 , the partition 400 is installed between the EGR cooler 8 and the EGR valve 7. Figure 5 The EGR cooler base 550 shown in the figure is fixed to the cylinder head 2 and supports the EGR cooler 8, the EGR valve 7, and the partition 400. The exhaust recirculation gas ECG shown by the arrow is delivered to the EGR valve 7 in order through the EGR cooler base 550, the EGR cooler 8, and the partition 400.

[0063] The partition 400 is arranged in the middle of the flow direction of the exhaust recirculation gas ECG shown by the arrow in the EGR gas path 23 which is an exhaust recirculation path. More specifically, the partition 400 is arranged between the end portion 8M of the EGR cooler 8 and the start portion 7N of the EGR valve 7. The partition 400 is formed in a wall thickness as thin as possible (for example, a wall thickness of about 10 mm) in the flow direction of the exhaust recirculation gas ECG shown by the arrow to prevent the engine 1 from being large-sized.

[0064] In addition, one of the reasons why the EGR differential pressure sensor 203 detects the differential pressure PP based on the pressure Pe of the exhaust recirculation gas ECG taken out from between the EGR cooler 8 and the EGR valve 7 using the partition 400 and the exhaust pressure acquisition path 500 is to detect the deterioration of the EGR cooler 8. For example, when the EGR cooler 8 is slightly clogged with particulate matter, the differential pressure PP based on the pressure Pe of the exhaust recirculation gas ECG located between the EGR cooler 8 and the EGR valve 7 provided on the more downstream side than the EGR cooler 8 changes. Therefore, the exhaust pressure acquisition path 500 is connected to the partition 400 provided between the downstream side of the EGR cooler 8, that is, the end portion 8M and the upstream side of the EGR valve 7, that is, the start portion 7N. And the EGR differential pressure sensor 203 detects the differential pressure PP based on the pressure Pe of the exhaust recirculation gas ECG of the second pressure measuring portion 223 located in the partition 400.

[0065] like Figure 6 As shown, the first portion 501 of the exhaust pressure acquisition path 500 has an external thread portion 503 at the portion connected to the spacer 400. By fastening the external thread portion 503 to the internal thread portion 404 of the spacer 400 using a thread structure, the first portion 501 of the exhaust pressure acquisition path 500 is connected to the spacer 400. Figure 5 As shown, the first portion 501 of the exhaust pressure acquisition path 500 is supported on the spacer 400 via a mounting fixture 520. The mounting fixture 520 is fixed to the spacer 400 by fastening a bolt 521 to the internally threaded portion 403 of the spacer 400, and supports the first portion 501 of the exhaust pressure acquisition path 500. The mounting fixture 520 not only prevents positional deviation of the first portion 501 of the exhaust pressure acquisition path 500, but also prevents the exhaust pressure acquisition path 500 from being separated from the spacer 400 and the EGR differential pressure sensor 203 due to engine vibration, etc.

[0066] like Figure 6 As shown, the mounting surface 405 of the spacer 400 with which the seat surface of the external thread portion 503 contacts and the mounting surface 406 of the spacer 400 on which the mounting fitting 520 is mounted are provided on the same side surface of the spacer 400 ( Figure 6 (left side in the figure). This allows an operator to attach the exhaust pressure acquisition path 500 to the spacer 400 and the mounting fitting 520 to the spacer 400, both from the same side of the exterior of the engine 1. More preferably, the mounting surface 405 of the spacer 400 and the mounting surface 406 of the spacer 400 are coplanar. This allows machining of the mounting surface 405 and the mounting surface 406 of the spacer 400 using the same process, simplifying the structure of the spacer 400.

[0067] like Figure 6 As shown, spacer 400 includes a circular gas through-hole 401 for passage of exhaust gas ECG; two mounting holes 402, 402, disposed on either side of gas through-hole 401; and a gas pressure acquisition hole 410 for acquiring the pressure Pe of exhaust gas ECG at second pressure measuring section 223 within spacer 400. Gas pressure acquisition hole 410 in this embodiment is an example of a "hole" in the present invention.

[0068] The gas through hole 401 allows the exhaust gas ECG to flow back to the Figure 6 In addition, for example, by making the Figure 5The non-illustrated positioning stud of the end portion 8M of the EGR cooler 8 passes through the holes 402, 402, thereby positioning the spacer 400 at the end portion 8M side using the stud.

[0069] The gas pressure acquisition hole 410 is formed through the spacer 400 in a direction, for example, a perpendicular direction TD, which crosses the flow of the exhaust recirculation gas ECG flowing in the EGR gas path 23. In the present embodiment, the gas pressure acquisition hole 410 is formed in the perpendicular direction TD which is perpendicular to the flow of the exhaust recirculation gas ECG flowing in the EGR gas path 23, and passes through the spacer 400 via the female threaded portion 404. In the present specification, "the gas pressure acquisition hole 410 passes through the spacer 400" includes a state in which the gas pressure acquisition hole 410 communicates the gas through hole 401 with the outside of the spacer 400 via the other hole of the female threaded portion 404 or the like. The pressure Pe of the exhaust recirculation gas ECG in the second pressure measuring portion 223 located inside the spacer 400 is taken out through the gas pressure acquisition hole 410, and is transmitted to the EGR differential pressure sensor 203 through the exhaust gas pressure acquisition path 500. In other words, the exhaust gas pressure acquisition path 500 transmits the pressure Pe of the exhaust recirculation gas ECG taken out through the gas pressure acquisition hole 410 to the EGR differential pressure sensor 203. Also, the EGR differential pressure sensor 203 detects the differential pressure PP between the pressure Pe of the exhaust recirculation gas ECG at the second pressure measuring portion 223 taken out through the gas pressure acquisition hole 410 of the spacer 400 and transmitted through the exhaust gas pressure acquisition path 500, and the pressure Pi of the mixed intake air CYL at the first pressure measuring portion 213 taken out through the intake gas pressure acquisition path 230 and transmitted. Figure 6

[0070] Furthermore, the direction of the axis of the gas pressure acquisition hole 410 is not limited to the perpendicular direction TD which is perpendicular to the flow of the exhaust recirculation gas ECG flowing in the EGR gas path 23. The direction of the axis of the gas pressure acquisition hole 410 can be a direction which crosses the flow of the exhaust recirculation gas ECG flowing in the EGR gas path 23, for example, can have a component of a direction opposite to the flow of the exhaust recirculation gas ECG flowing in the EGR gas path 23.

[0071] The ECU 100 calculates the exhaust recirculation air amount mfegr of the exhaust recirculation gas ECG in the EGR gas path 23 which is the exhaust recirculation path, on the basis of the differential pressure PP detected by the EGR differential pressure sensor 203 and the opening degree of the EGR valve 7. The calculation of the exhaust recirculation air amount mfegr will be described later in detail.

[0072] ​The EGR cooler base 550 is fixed to the cylinder head 2 and the start end portion 8N of the EGR cooler 8. Even if the spacer 400 is provided between the EGR valve 7 and the EGR cooler 8, thinning of the EGR cooler base 550 can be achieved to suppress the increase in size of the engine 1. At this time, before and after the thinning of the EGR cooler base 550, the cross-sectional area of the internal flow path of the EGR cooler base 550 is suppressed from changing, and the flow rate, pressure, and temperature of the exhaust recirculation gas ECG flowing in the EGR gas passage 23 are suppressed from changing. For example, the cross-sectional area of the narrowest internal flow path among the internal flow paths of the EGR cooler base 550 is kept the same before and after the thinning of the EGR cooler base 550. Thus, before and after the thinning of the EGR cooler base 550, the pressure Pe of the exhaust recirculation gas ECG at the second pressure measuring portion 223 can be suppressed from changing, and the differential pressure PP detected by the EGR differential pressure sensor 203 can be suppressed from changing. In addition, before and after the thinning of the EGR cooler base 550, the basic performance of the EGR (Exhaust Gas Recirculation) can be suppressed from changing.

[0073] <Example of Calculation of Intake Air Amount mfair in Intake Pipe 20 Using Intake Air Amount Measuring Device 200>

[0074] Next, an example of calculation of the flow rate (intake air amount mfair) of the intake air AR in the intake pipe 20 using the intake air amount measuring device 200 will be described.

[0075] Generally, in an internal combustion engine such as a diesel engine, an intake air amount sensor (MAF sensor) that detects the intake air amount of air (intake air) flowing in an intake pipe is provided on the intake pipe. In addition, the intake air amount is the flow rate of air (intake air) flowing in the intake pipe, and is also referred to as intake air flow rate or MAF, etc. However, the output characteristic of the intake air amount sensor provided on the intake pipe depends on the shape of the intake system (e.g., the intake pipe) on the upstream side of the intake air amount sensor. The intake system on the upstream side of the intake air amount sensor differs, for example, depending on each application in which an industrial diesel engine or the like is mounted. Therefore, the calibration work of the intake air amount sensor is necessary for each application in which an engine is mounted, and is complicated.

[0076] Therefore, in the intake air amount measuring device 200 of the present embodiment, as described below, the ECU 100 suppresses the dependence of the measurement result of the intake air amount mfair in the intake pipe 20 on the shape of the intake pipe 20, and stably measures the intake air amount mfair in the intake pipe 20.

[0077] That is, in the intake air amount calculation method of the present embodiment, the ECU 100 first calculates the flow rate (intake air amount mfcyl) of the intake air CYL supplied into the cylinders of the first to fourth cylinders 11 to 14 shown in FIG. 1, based on the pressure Pi of the intake air CYL in the intake manifold 3 detected by the pressure sensor 201 and the temperature Ti of the intake air CYL in the intake manifold 3 detected by the temperature sensor 202. Specifically, the ECU 100 calculates the intake air amount mfcyl of the intake air CYL based on the pressure Pi of the intake air CYL and the temperature Ti of the intake air CYL using a state equation of gas. Further, in an engine not having an exhaust gas recirculation mechanism such as the EGR gas passage 23, the above-described intake air amount mfcyl is the intake air amount mfair of the intake air AR described later. Figure 1

[0078] Next, the ECU 100 calculates the intake air amount mfair of the intake air AR flowing in the intake pipe 20 shown in FIG. 1, based on the intake air amount mfcyl of the intake air CYL and the exhaust gas recirculation air amount mfegr of the exhaust gas recirculation gas ECG. Specifically, the ECU 100 calculates the intake air amount mfair of the intake air AR flowing in the intake pipe 20 shown in FIG. 1, by calculating the difference between the above-described calculated intake air amount mfcyl and the exhaust gas recirculation air amount mfegr of the exhaust gas recirculation gas ECG flowing in the EGR gas passage 23. Figure 1 Figure 1

[0079] The exhaust gas recirculation air amount mfegr is stored in advance in the ROM or the like of the ECU 100 in the form of an exhaust gas recirculation air amount table (map) as a function of the opening degree of the EGR valve 7 and the differential pressure PP (differential pressure between the pressure Pi of the intake air CYL and the pressure Pe of the exhaust gas recirculation gas ECG). The ECU 100 reads the exhaust gas recirculation air amount table (map) stored in advance in the ROM or the like of the ECU 100, in accordance with the opening degree of the EGR valve 7 and the differential pressure PP detected by the EGR differential pressure sensor 203, when performing the calculation.

[0080] Thus, the ECU 100 is able to calculate the intake air amount mfair of the new intake air AR flowing in the intake pipe 20 shown in FIG. 1, based on the pressure Pi of the intake air CYL in the intake manifold 3 detected by the pressure sensor 201, the temperature Ti of the intake air CYL in the intake manifold 3 detected by the temperature sensor 202, and the differential pressure PP (differential pressure between the pressure Pi of the intake air CYL and the pressure Pe of the exhaust gas recirculation gas ECG) detected by the EGR differential pressure sensor 203. Figure 1 Figure 1

[0081] ​​​​​Thus, in the intake air amount measurement device 200 and the engine 1 of the present embodiment, the ECU 100 can suppress the measurement result of the intake air amount mfair from being dependent on the shape of the intake pipe 20 and stably measure the intake air amount mfair.

[0082] <Setting Positions of the First Pressure Measuring Unit 213 and the Temperature Sensor 202>

[0083] Next, refer to Figures 1-4 , the setting position PS of the first pressure measuring unit 213 and the temperature sensor 202 will be described.

[0084] Figure 2 Schematic diagram illustrating the results of turbulence energy from CFD fluid analysis performed by the present inventors.

[0085] Figure 3 Schematic diagram illustrating the pressure results of CFD fluid analysis performed by the present inventors.

[0086] Figure 4 This is a schematic diagram illustrating the results of temperature analysis of CFD fluid flow performed by the present inventors.

[0087] also, Figure 2 (A) Figure 3 (A) and Figure 4 (A) is a schematic diagram illustrating analysis results during the intake process of the first cylinder 11 . Figure 2 (B) Figure 3 (B) and Figure 4 (B) is a schematic diagram illustrating the analysis results during the intake process of the second cylinder 12 . Figure 2 (C) Figure 3 (C) and Figure 4 (C) is a schematic diagram illustrating the analysis results during the intake process of the third cylinder 13 . Figure 2 (D) Figure 3 (D) and Figure 4 (D) is a schematic diagram illustrating the analysis results during the intake process of the fourth cylinder 14 .

[0088] To further suppress the dependence of the intake air amount mfair measurement result on the shape of the intake pipe 20 and to achieve more stable measurement of the intake air amount mfair, the first pressure measuring unit 213 and the temperature sensor 202 are preferably located at a position within the intake manifold 3 where the pulsation of the mixed intake air CYL is relatively small, that is, where the flow of the mixed intake air CYL within the intake manifold 3 is relatively stable. The pulsation of the mixed intake air CYL within the intake manifold 3 is affected by the opening and closing of the intake valve (not shown) and the exhaust valve (not shown) of the engine 1, and by the mixing of the intake air AR and the exhaust recirculation gas ECG.

[0089] Accordingly, the inventors conducted a CFD (Computational Fluid Dynamics) fluid analysis as exemplified below in order to confirm the turbulent energy, pressure, and temperature of the mixed intake air CYL in the intake manifold 3.

[0090] That is, when the analysis condition outline (physical model) is explained, the subject fluid is three-dimensional gas (air) and is a non-compressible fluid (constant density). The flow of the subject fluid is turbulent flow and is steady flow. The turbulent flow model is the Realizable k-ε model. The velocity distribution of the subject fluid near the wall surface is based on the wall function (2-layer All y+ model). The solver is a segregated solver. Heat transfer calculation is not performed. The reference calculation grid size is 5 mm.

[0091] In addition, as the analysis condition, the engine is a turbo diesel engine. The rated rotation speed of the engine is 2600 rpm. Full load is applied to the engine. The engine is an engine of an EGR specification having the EGR gas path 23, the EGR valve 7, and the EGR cooler 8.

[0092] As shown in (A) to (D) of FIG. 10, the intake manifold 3 as the analysis object has the main pipe 35 having the start end portion 351 at one end for intake air to flow in, and the first branch pipe 31, the second branch pipe 32, the third branch pipe 33, and the fourth branch pipe 34 branched from the main pipe 35. The length direction of the main pipe 35 is along the direction in which the first cylinder 11, the second cylinder 12, the third cylinder 13, and the fourth cylinder 14 are arranged, that is, the direction in which the crankshaft extends. The first branch pipe 31, the second branch pipe 32, the third branch pipe 33, and the fourth branch pipe 34 are connected to the first cylinder 11, the second cylinder 12, the third cylinder 13, and the fourth cylinder 14 of the engine 1, respectively. Figure 2 Figure 4 As shown in (A) to (D) of FIG. 10, the intake manifold 3 as the analysis object has the main pipe 35 having the start end portion 351 at one end for intake air to flow in, and the first branch pipe 31, the second branch pipe 32, the third branch pipe 33, and the fourth branch pipe 34 branched from the main pipe 35. The length direction of the main pipe 35 is along the direction in which the first cylinder 11, the second cylinder 12, the third cylinder 13, and the fourth cylinder 14 are arranged, that is, the direction in which the crankshaft extends. The first branch pipe 31, the second branch pipe 32, the third branch pipe 33, and the fourth branch pipe 34 are connected to the first cylinder 11, the second cylinder 12, the third cylinder 13, and the fourth cylinder 14 of the engine 1, respectively.

[0093] Further, in the example shown in (A) to (D) of FIG. 10, the intake manifold 3 has two first branch pipes 31, two second branch pipes 32, two third branch pipes 33, and two fourth branch pipes 34. That is, each two of the first branch pipe 31, the second branch pipe 32, the third branch pipe 33, and the fourth branch pipe 34 are connected to the first cylinder 11, the second cylinder 12, the third cylinder 13, and the fourth cylinder 14 of the engine 1, respectively. However, the number of branch pipes of the intake manifold 3 connected to each cylinder of the engine 1 is not limited thereto. For example, one each of the first branch pipe 31, the second branch pipe 32, the third branch pipe 33, and the fourth branch pipe 34 are connected to the first cylinder 11, the second cylinder 12, the third cylinder 13, and the fourth cylinder 14 of the engine 1, respectively. Figure 2 Figure 4 As shown in (A) to (D) of FIG. 10, the intake manifold 3 as the analysis object has the main pipe 35 having the start end portion 351 at one end for intake air to flow in, and the first branch pipe 31, the second branch pipe 32, the third branch pipe 33, and the fourth branch pipe 34 branched from the main pipe 35. The length direction of the main pipe 35 is along the direction in which the first cylinder 11, the second cylinder 12, the third cylinder 13, and the fourth cylinder 14 are arranged, that is, the direction in which the crankshaft extends. The first branch pipe 31, the second branch pipe 32, the third branch pipe 33, and the fourth branch pipe 34 are connected to the first cylinder 11, the second cylinder 12, the third cylinder 13, and the fourth cylinder 14 of the engine 1, respectively. ​​

[0094] An inlet flange 22 is connected to the starting end 351 of the intake manifold 3, through which intake air flows. The inlet flange 22 includes an EGR gas path 23 for recirculating exhaust gas from the engine 1. Exhaust gas recirculated through the EGR gas path 23 is mixed with intake air in a mixing section 24 within the inlet flange 22 before flowing into the starting end 351 of the intake manifold 3.

[0095] An example of the result of the turbulence energy of the target fluid based on the CFD fluid analysis performed according to the analysis condition outline (physical model) and analysis conditions described above is as follows: Figure 2 In addition, an example of the result of the pressure of the target fluid based on CFD fluid analysis is shown as follows Figure 3 In addition, the results of the temperature of the target fluid based on CFD fluid analysis are as follows. Figure 4 shown.

[0096] like Figure 2 (A)~ Figure 2 As shown in (D), in any of the intake processes of the first cylinder 11, the second cylinder 12, the third cylinder 13, and the fourth cylinder 14, in the intake manifold 3, the turbulent energy of the target fluid near the third cylinder 13 and the fourth cylinder 14 is higher than the turbulent energy of the target fluid near the first cylinder 11 and the second cylinder 12. Turbulent energy indicates the degree of turbulence of the flow of the target fluid. Therefore, in Figure 2 (A)~ Figure 2 The example of the analysis result shown in (D) indicates that the flow field near the third cylinder 13 and the fourth cylinder 14 in the intake manifold 3 is more likely to become unstable than the flow field near the first cylinder 11 and the second cylinder 12. In other words, Figure 2 (A)~ Figure 2 The example of the analysis result shown in (D) suggests that, in the intake manifold 3 , the flow of the target fluid near the first cylinder 11 and the second cylinder 12 is more stable than the flow of the target fluid near the third cylinder 13 and the fourth cylinder 14 .

[0097] Specifically, if Figure 2 As shown in (A), during the intake process of the first cylinder 11, the turbulent energy of the target fluid in the region 300 of the first branch pipe 31 and the regions 301, 302, 303, and 304 from the third branch pipe 33 to the fourth branch pipe 34 is higher than the turbulent energy of the target fluid in other regions. Figure 2(B) shows, in the intake process of the second cylinder 12, the turbulent energy of the subject fluid in the region 305 of the second branch pipe 32, and the regions 306, 307, and 308 from the third branch pipe 33 to the fourth branch pipe 34 is higher than that in other regions. In addition, as shown in Figure 2 (C) shows, in the intake process of the third cylinder 13, the turbulent energy of the subject fluid in the regions 309 and 310 from the third branch pipe 33 to the fourth branch pipe 34 is higher than that in other regions. In addition, as shown in Figure 2 (D) shows, in the intake process of the fourth cylinder 14, the turbulent energy of the subject fluid in the region 311 of the fourth branch pipe 34 is higher than that in other regions.

[0098] Referring to Figure 2 (A) to Figure 3 (D), in the intake manifold 3, the turbulent energy of the subject fluid in the region W from the first branch pipe 31 connected to the first cylinder 11 to the second branch pipe 32 connected to the second cylinder 12, especially at the position PS between the first branch pipe 31 connected to the first cylinder 11 and the second branch pipe 32 connected to the second cylinder 12, is relatively low. Therefore, it is judged that the flow of the subject fluid in the region W in the intake manifold 3, especially at the position PS, is relatively stable.

[0099] In addition, as shown in Figure 3 (A) to Figure 3 (D), in any one of the intake processes of the first cylinder 11, the second cylinder 12, the third cylinder 13, and the fourth cylinder 14, in the intake manifold 3, the pressure of the subject fluid near the first cylinder 11 and the second cylinder 12 is more stable than that of the subject fluid near the third cylinder 13 and the fourth cylinder 14.

[0100] Specifically, as shown in Figure 3 (A) shows, in the intake process of the first cylinder, the pressure of the subject fluid in the region W is higher than that in the region 321 of the first branch pipe 31, and lower than that in the regions 322 and 323 from the third branch pipe 33 to the fourth branch pipe 34. In addition, as shown in Figure 3 (B) shows, in the intake process of the second cylinder, the pressure of the subject fluid in the region W is higher than that in the region 324 of the second branch pipe 32, and lower than that in the regions 325 and 326 from the third branch pipe 33 to the fourth branch pipe 34. In addition, as shown in Figure 3W in the intake process of the third cylinder is higher than the pressure of the subject fluid in the region 327 of the third branch pipe 33, and is lower than the pressure of the subject fluid in the regions 328 and 329 from the third branch pipe 33 to the fourth branch pipe 34. In addition, as shown in Figure 3 W in the intake process of the fourth cylinder is lower than the pressure of the subject fluid in the regions 331 and 332 of the third branch pipe 33, and is higher than the pressure of the subject fluid in the regions 333 and 334 of the fourth branch pipe 34.

[0101] Referring to Figure 3 (A) to Figure 4 (D), in the intake manifold 3, the variation of the pressure of the subject fluid in the region W from the first branch pipe 31 connected to the first cylinder 11 to the second branch pipe 32 connected to the second cylinder 12, particularly at the position PS between the first branch pipe 31 connected to the first cylinder 11 and the second branch pipe 32 connected to the second cylinder 12, is relatively small. That is, the pressure of the subject fluid in the region W in the intake manifold 3, particularly at the position PS, is relatively stable.

[0102] In addition, as shown in Figure 4 (A) to Figure 4 (D), in any one of the intake processes of the first cylinder 11, the second cylinder 12, the third cylinder 13, and the fourth cylinder 14, in the intake manifold 3, the temperature of the subject fluid near the first cylinder 11 and the second cylinder 12 is more stable than the temperature of the subject fluid near the third cylinder 13 and the fourth cylinder 14.

[0103] Specifically, as shown in Figure 4 (A), in the intake process of the first cylinder, the temperature of the subject fluid in the region W is lower than the temperature of the subject fluid in the regions 341 and 342 from the third branch pipe 33 to the fourth branch pipe 34. In addition, as shown in Figure 4 (B), in the intake process of the second cylinder, the temperature of the subject fluid in the region W is lower than the temperature of the subject fluid in the regions 343 and 344 from the third branch pipe 33 to the fourth branch pipe 34. In addition, as shown in Figure 4 (C), in the intake process of the third cylinder, the temperature of the subject fluid in the region W is higher than the temperature of the subject fluid in the region 345 of the first branch pipe 31, and is lower than the temperature of the subject fluid in the region 346 from the third branch pipe 33 to the fourth branch pipe 34. In addition, as shown in Figure 4 (D), in the intake process of the fourth cylinder, the temperature of the subject fluid in the region W is lower than the temperature of the subject fluid in the regions 347, 348, and 349 of the fourth branch pipe 34.

[0104] Referring to Figure 4 (A) to Figure 1 (D), in the intake manifold 3, the variation of the temperature of the subject fluid is relatively small in the region W from the first branch pipe 31 connected to the first cylinder 11 to the second branch pipe 32 connected to the second cylinder 12, particularly at the position PS between the first branch pipe 31 connected to the first cylinder 11 and the second branch pipe 32 connected to the second cylinder 12. That is, the temperature of the subject fluid in the region W in the intake manifold 3, particularly at the position PS, is relatively stable.

[0105] According to the results of the CFD fluid analysis implemented by the present inventor, when viewed along the direction in which the first cylinder 11, the second cylinder 12, the third cylinder 13, and the fourth cylinder 14 are arranged, that is, the length direction of the main pipe 35 of the intake manifold 3, the turbulent energy of the subject fluid is relatively low, and the pressure and the temperature of the subject fluid are relatively stable in the region far from the upstream end 351 in the region in the intake manifold 3. Therefore, when viewed along the direction in which the first cylinder 11, the second cylinder 12, the third cylinder 13, and the fourth cylinder 14 are arranged, that is, the length direction of the main pipe 35 of the intake manifold 3, the first pressure measuring portion 213 and the temperature sensor 202 are preferably provided in the region far from the upstream end 351 in the region in the intake manifold 3. More specifically, the first pressure measuring portion 213 and the temperature sensor 202 are preferably provided at the position PS across the region W from the first branch pipe 31 connected to the first cylinder 11 to the second branch pipe 32 connected to the second cylinder 12, particularly between the first branch pipe 31 connected to the first cylinder 11 and the second branch pipe 32 connected to the second cylinder 12.

[0106] The intake air amount measuring device 200 according to the present embodiment detects the temperature Ti of the mixed intake air CYL in a region W located across the first branch pipe 31 connected to the first cylinder 11 and the second branch pipe 32 connected to the second cylinder 12. As described above, the first branch pipe 31 is connected to the first cylinder 11 disposed at the position farthest from the start end portion 351 of the intake manifold 3 in the length direction of the intake manifold 3. The second branch pipe 32 is connected to the second cylinder 12 disposed at the position next to the first cylinder 11 in the length direction of the intake manifold 3 from the start end portion 351 of the intake manifold 3. Also, the ECU 100 calculates the intake air amount mfcyl of the mixed intake air CYL and the intake air amount mfair of the intake air AR on the basis of the temperature Ti of the mixed intake air CYL transmitted from the temperature sensor 202 and the pressure Pi of the mixed intake air CYL transmitted from the pressure sensor 201. That is, in the engine having the exhaust gas recirculation mechanism such as the EGR gas path 23, the ECU 100 calculates the intake air amount mfair of the intake air AR by calculating the difference between the intake air amount mfcyl of the mixed intake air CYL and the exhaust gas recirculation air amount mfegr of the exhaust gas recirculation gas ECG. On the other hand, in the engine not having the exhaust gas recirculation mechanism such as the EGR gas path 23, the ECU 100 calculates the intake air amount mfair of the intake air AR by setting the intake air amount mfcyl of the mixed intake air CYL to correspond to the intake air amount mfair of the intake air AR.

[0107] Thus, the temperature sensor 202 detects the temperature Ti of the mixed intake air CYL in a region where the flow of the mixed intake air CYL is relatively stable in the region in the intake manifold 3. Also, the ECU 100 calculates the intake air amount mfcyl of the mixed intake air CYL and the intake air amount mfair of the intake air AR on the basis of the temperature Ti of the mixed intake air CYL transmitted from the temperature sensor 202 and the pressure Pi of the mixed intake air CYL transmitted from the pressure sensor 201, without depending on the intake air amount sensor (MAF sensor) that detects the flow rate of the intake air AR flowing in the intake pipe 20. Thus, the intake air amount measuring device 200 according to the present embodiment can suppress the case where the measurement result of the intake air amount mfair of the intake air AR flowing in the intake pipe 20 depends on the shape of the intake pipe 20, and can stably measure the intake air amount mfair of the intake air AR.

[0108] Further, the pressure sensor 201 detects the pressure Pi of the intake air CYL in a region where the flow of the intake air CYL is relatively stable in the region in the intake manifold 3. Also, as described above, the ECU 100 calculates the intake air amount mfcyl of the intake air CYL and the intake air amount mfair of the intake air AR based on the temperature Ti of the intake air CYL transmitted from the temperature sensor 202 and the pressure Pi of the intake air CYL transmitted from the pressure sensor 201, without depending on the intake air amount sensor (MAF sensor) that detects the flow rate of the intake air AR flowing in the intake pipe 20. Thus, the intake air amount measuring device 200 of the present embodiment can further suppress the case where the measurement result of the intake air amount mfair of the intake air AR flowing in the intake pipe 20 depends on the shape of the intake pipe 20, and can further stably measure the intake air amount mfair of the intake air AR.

[0109] Further, as shown in FIG. 2, the temperature sensor 202 is provided in the intake manifold 3 at a position closer to the end portion 351 of the intake manifold 3 than the first pressure sensor 213. Thus, the temperature sensor 202 detects the temperature Ti of the intake air CYL in the intake manifold 3 at a position closer to the end portion 351 than the position where the first pressure sensor 213 detects the pressure Pi of the intake air CYL. Thus, the temperature sensor 202 can more stably detect the temperature Ti of the intake air CYL. Thus, the intake air amount measuring device 200 of the present embodiment can further suppress the case where the measurement result of the intake air amount mfair of the intake air AR flowing in the intake pipe 20 depends on the shape of the intake pipe 20, and can further stably measure the intake air amount mfair of the intake air AR. ​ Further, as shown in FIG. 2, the temperature sensor 202 is provided in the intake manifold 3 at a position closer to the end portion 351 of the intake manifold 3 than the first pressure sensor 213. Thus, the temperature sensor 202 detects the temperature Ti of the intake air CYL in the intake manifold 3 at a position closer to the end portion 351 than the position where the first pressure sensor 213 detects the pressure Pi of the intake air CYL. Thus, the temperature sensor 202 can more stably detect the temperature Ti of the intake air CYL. Thus, the intake air amount measuring device 200 of the present embodiment can further suppress the case where the measurement result of the intake air amount mfair of the intake air AR flowing in the intake pipe 20 depends on the shape of the intake pipe 20, and can further stably measure the intake air amount mfair of the intake air AR.

[0110] Further, the first pressure measuring portion 213 is provided in the region W that spans the first branch pipe 31 and the second branch pipe 32, and therefore the EGR differential pressure sensor 203 detects the differential pressure PP between the pressure Pi of the mixed intake air CYL in a region in which the flow of the mixed intake air CYL is relatively stable, in the intake manifold 3, and the pressure Pe of the exhaust gas recirculation gas ECG at the second pressure measuring portion 223 provided in the EGR gas path 23. Also, the ECU 100 calculates the intake air amount mfcyl of the mixed intake air CYL and the intake air amount mfair of the intake air AR, based on the temperature Ti of the mixed intake air CYL transmitted from the temperature sensor 202, the pressure Pi of the mixed intake air CYL transmitted from the pressure sensor 201, and the differential pressure PP transmitted from the EGR differential pressure sensor 203. Thus, in the case where the exhaust gas recirculation mechanism that recirculates the exhaust gas of the engine 1 is provided, the intake air amount measuring device 200 of the present embodiment can improve the calculation accuracy of the intake air amount mfair of the intake air AR flowing in the intake pipe 20.

[0111] Further, since the first pressure measuring portion 213 is provided in the length direction of the intake manifold 3 at a position closer to the start end portion 351 of the intake manifold 3 than the temperature sensor 202, the EGR differential pressure sensor 203 detects the differential pressure PP based on the pressure Pi of the mixed intake air CYL at a position in the length direction of the intake manifold 3 that is closer to the start end portion 351 than the mixed intake air CYL whose temperature Ti is detected by the temperature sensor 202. Therefore, the EGR differential pressure sensor 203 detects the differential pressure PP based on the pressure Pi of the mixed intake air CYL in a more stable region before the flow is disturbed, rather than based on the pressure of the mixed intake air CYL in a region whose flow is disturbed by a probe or the like of the temperature sensor 202 provided in the intake manifold 3, for example. Thus, the EGR differential pressure sensor 203 can more stably measure the differential pressure PP. Thus, in the case where the exhaust gas recirculation mechanism that recirculates the exhaust gas of the engine 1 is provided, the intake air amount measuring device 200 of the present embodiment can improve the calculation accuracy of the intake air amount mfair of the intake air AR flowing in the intake pipe 20.

[0112] Further, the EGR differential pressure sensor 203 detects the differential pressure PP based on the pressure Pi of the intake air CYL at the same position (i.e., the first pressure measuring portion 213) in the length direction of the intake manifold 3 as the pressure sensor 201 detects the pressure Pi of the intake air CYL. That is, the detection position of the pressure Pi of the intake air CYL by the EGR differential pressure sensor 203 is the same as the detection position of the pressure Pi of the intake air CYL by the pressure sensor 201, i.e., the position across the region W of the first branch pipe 31 and the second branch pipe 32. Therefore, the pressure Pi of the intake air CYL in the intake manifold 3 for detecting the differential pressure PP by the EGR differential pressure sensor 203 is synchronized in time with the pressure Pi of the intake air CYL in the intake manifold 3 detected by the pressure sensor 201. Thus, the ECU 100 calculates the intake air amount mfcyl of the intake air CYL and the exhaust gas recirculation air amount mfegr of the exhaust gas recirculation gas ECG based on one system, i.e., the same state, of the intake manifold 3. Thereby, in the case where the exhaust gas recirculation mechanism that recirculates the exhaust gas of the engine 1 is provided, the intake air amount measuring device 200 of the present embodiment can improve the calculation accuracy of the intake air amount mfair of the intake air AR flowing in the intake pipe 20.

[0113] Further, the second pressure measuring portion 223 is provided in the EGR gas path 23 between the EGR cooler 8 and the EGR valve 7. Therefore, the EGR differential pressure sensor 203 detects the differential pressure PP based on the pressure Pe of the exhaust gas recirculation gas ECG between the EGR cooler 8 and the EGR valve 7. Thereby, the ECU 100 can estimate the deterioration condition or the deterioration degree of the EGR cooler 8 based on the differential pressure PP transmitted from the EGR differential pressure sensor 203.

[0114] Further, the partition 400 is provided on the EGR gas passage 23 between the EGR cooler 8 and the EGR valve 7. Also, the EGR differential pressure sensor 203 detects the differential pressure PP based on the pressure Pe of the exhaust recirculation gas ECG taken out through the gas pressure taking hole 410 of the partition 400. Therefore, the exhaust pressure taking passage 500 that transmits the pressure Pe of the exhaust recirculation gas ECG to the EGR differential pressure sensor 203 is hardly restricted in structure from the EGR valve 7 and the EGR cooler 8, and can be reliably connected to the partition 400. Further, even if the structure of the EGR cooler 8 and the EGR valve 7 is not changed, by changing the structure of the partition 400, the exhaust pressure taking passage 500 such as various pipes that transmits the pressure Pe of the exhaust recirculation gas ECG to the EGR differential pressure sensor 203 can be easily connected to the partition 400. Also, the gas pressure taking hole 410 of the partition 400 is formed so as to penetrate in a direction intersecting the flow of the exhaust recirculation gas ECG flowing in the EGR gas passage 23. Therefore, the gas pressure taking hole 410 of the partition 400 can be inhibited from being clogged by particulate matter (PM) contained in the exhaust recirculation gas ECG. Thus, the EGR differential pressure sensor 203 can more reliably take the pressure (static pressure) Pe of the exhaust recirculation gas ECG, and detect the differential pressure PP with higher accuracy based on the pressure (static pressure) Pe of the exhaust recirculation gas ECG.

[0115] Further, the exhaust pressure taking passage 500 is connected to the partition 400 and the EGR differential pressure sensor 203, and transmits the pressure Pe of the exhaust recirculation gas ECG taken out through the gas pressure taking hole 410 of the partition 400 to the EGR differential pressure sensor 203. Also, at least the first portion 501 of the exhaust pressure taking passage 500 that is connected to the partition 400 is made of metal. Therefore, the first portion 501 of the exhaust pressure taking passage 500 that is connected to the partition 400 can be inhibited from being deteriorated or solidified by the heat of the exhaust recirculation gas ECG flowing in the EGR gas passage 23. Thus, a gap can be inhibited from being generated between the first portion 501 of the exhaust pressure taking passage 500 that is connected to the partition 400 and the partition 400, and air outside the exhaust pressure taking passage 500 can be inhibited from entering the inside of the exhaust pressure taking passage 500. Thus, the EGR differential pressure sensor 203 can detect the differential pressure PP with higher accuracy. Further, the first portion 501 of the exhaust pressure taking passage 500 that is connected to the partition 400 is made of metal, and therefore the exhaust pressure taking passage 500 can be fastened to the partition 400 by using a threaded structure. Thus, the exhaust pressure taking passage 500 can be inhibited from being detached from the partition 400, and the positioning of the exhaust pressure taking passage 500 with respect to the partition 400 can be easily performed.

[0116] In addition, the second portion 502 of the exhaust pressure acquisition path 500 connected to the EGR differential pressure sensor 203 is made of a resin having flexibility and heat resistance, such as an engineering plastic or rubber. Therefore, even if the first portion 501 of the exhaust pressure acquisition path 500 is made of metal, the second portion 502 of the exhaust pressure acquisition path 500 flexibly corresponds to the position of the EGR differential pressure sensor 203, and thus can be easily connected to the EGR differential pressure sensor 203.

[0117] The above describes the embodiments of the application. However, the application is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the claims. The structure of the above-described embodiments can omit a part thereof, or be arbitrarily combined in a different manner from the above.

[0118] For example, as an example of the engine of the application, the engine 1 of the present embodiment is exemplified. The engine 1 is a turbocharged diesel engine. However, it is not limited thereto, and the engine of the application can be a naturally aspirated diesel engine, a turbocharged gasoline engine, a naturally aspirated gasoline engine, or the like. In addition, the engine 1 is a multi-cylinder engine such as a turbocharged high-output four-cylinder engine. However, the engine 1 is not limited thereto, and can be a three-cylinder or five-cylinder or more engine. The engine 1 can be mounted on a vehicle other than a construction machine, an agricultural machine, or a lawn mower.

[0119] Explanation of reference numerals:

[0120] 1: engine, 2: cylinder head, 3: intake manifold, 4: exhaust manifold, 4B: exhaust passage, 5: turbocharger, 5B: impeller, 5T: turbine, 6: intake throttle valve, 7: EGR valve, 8: EGR cooler, 11: first cylinder, 12: second cylinder, 13: third cylinder, 14: fourth cylinder, 15: fuel injection valve, 16: common rail, 19: diesel particulate filter, 20: intake pipe, 21: intake passage, 22: inlet flange, 23: EGR gas path, 23M: initial end portion, 23N: terminal end portion, 24: mixing portion, 31: first branch pipe, 32: second branch pipe, 33: third branch pipe, 34: fourth branch pipe, 35: main pipe, 100: ECU, 200: intake amount measuring device, 201: pressure sensor, 202: temperature sensor, 203: EGR differential pressure sensor, 213: first pressure measuring portion, 223: second pressure measuring portion, 230: intake pressure acquisition path, 351: initial end portion, 400: spacer, 401: gas through-hole, 402: hole, 403: internally threaded portion, 404: internally threaded portion, 405: mounting surface, 406: placement surface, 410: gas pressure acquisition hole, 500: exhaust pressure acquisition path, 501: first portion, 502: second portion, 503: externally threaded portion, 520: mounting fitting, 521: bolt, 550: EGR cooler base, AR: intake air, CYL: mixed intake air, ECG: exhaust recirculation gas, EG: exhaust gas, PP: differential pressure, PS: set position, Pe, Pi: pressure, Ti: temperature, W: region, mfair, mfcyl: intake amount, mfegr: exhaust recirculation air amount

Claims

1. An intake air amount measuring device that measures a flow rate of intake air of an engine having three or more cylinders arranged in line, wherein the intake air amount measuring device has: an intake air distribution mechanism that distributes the intake air to the cylinders of the engine; a temperature detecting mechanism that detects a temperature of the intake air; a pressure detecting mechanism that detects a pressure of the intake air; and an arithmetic unit that, based on the temperature transmitted from the temperature detecting mechanism and the pressure transmitted from the pressure detecting mechanism, calculates the flow rate, a length direction of the intake air distribution mechanism is along a direction in which the cylinders of the engine are arranged, the intake air flows into the intake air distribution mechanism from one end of the length direction, the temperature detecting mechanism detects the temperature of the intake air at a position in an interior of the intake air distribution mechanism between a first branch portion of the intake air distribution mechanism connected to a first cylinder of the engine disposed at a position farthest from the one end in the length direction and a second branch portion of the intake air distribution mechanism connected to a second cylinder of the engine disposed at a position next to the first cylinder farther from the one end in the length direction, and the pressure detecting mechanism detects the pressure of the intake air at the position between the first branch portion and the second branch portion, which is taken out and transmitted through an intake air pressure acquisition path, at a position closer to the one end in the length direction than the intake air whose temperature is detected by the temperature detecting mechanism.

2. The intake air amount measuring device according to claim 1, wherein the intake air amount measuring device further has: an exhaust gas recirculation mechanism that recirculates exhaust gas of the engine; and a differential pressure detecting mechanism that detects a differential pressure between the exhaust gas flowing in the exhaust gas recirculation mechanism and the intake air flowing in the intake air distribution mechanism and transmits to the arithmetic unit, the arithmetic unit further calculates the flow rate based on the differential pressure transmitted from the differential pressure detecting mechanism, and the differential pressure detecting mechanism detects the differential pressure based on the pressure of the intake air at the position closer to the one end in the length direction than the intake air whose temperature is detected by the temperature detecting mechanism, which is taken out and transmitted through an intake air pressure acquisition path.

3. The intake air amount measuring device according to claim 2, wherein the differential pressure detecting mechanism detects the differential pressure based on the pressure of the intake air at the same position in the length direction as the intake air whose pressure is detected by the pressure detecting mechanism.

4. The intake air amount measuring device according to claim 2 or 3, wherein the differential pressure detecting mechanism detects the differential pressure based on a pressure of the exhaust gas between a cooling mechanism that cools the exhaust gas flowing in the exhaust gas recirculation mechanism and a flow rate adjusting mechanism that adjusts a flow rate of the exhaust gas flowing in the exhaust gas recirculation mechanism on a downstream side of the cooling mechanism. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 5. The intake air amount measuring device according to claim 4, wherein the intake air amount measuring device further has: a partition provided on the exhaust gas recirculation mechanism between the cooling mechanism and the flow rate adjusting mechanism, the partition has a hole formed therethrough in a direction intersecting the flow of the exhaust gas flowing in the exhaust gas recirculation mechanism, the differential pressure detecting mechanism detects the differential pressure based on the pressure of the exhaust gas taken out through the hole of the partition.

6. The intake air amount measuring device according to claim 5, wherein the intake air amount measuring device further has: an exhaust gas pressure obtaining path connected to the partition and the differential pressure detecting mechanism and transmitting the pressure of the exhaust gas taken out through the hole to the differential pressure detecting mechanism, at least a portion of the exhaust gas pressure obtaining path connected to the partition is made of metal.

7. An engine having an intake air amount measuring device that measures a flow rate of intake air and having three or more cylinders arranged in line, wherein the intake air amount measuring device has: an intake air distribution mechanism that distributes the intake air to the cylinders of the engine; a temperature detecting mechanism that detects a temperature of the intake air; a pressure detecting mechanism that detects a pressure of the intake air; and an arithmetic unit that, based on the temperature transmitted from the temperature detecting mechanism and the pressure transmitted from the pressure detecting mechanism, calculates the flow rate, a length direction of the intake air distribution mechanism is along a direction in which the cylinders of the engine are arranged, the intake air flows into the intake air distribution mechanism from one end of the length direction, the temperature detecting mechanism detects the temperature of the intake air in a position in the inside of the intake air distribution mechanism between a first branch portion of the intake air distribution mechanism connected to a first cylinder of the engine provided at a position farthest from the one end in the length direction and a second branch portion of the intake air distribution mechanism connected to a second cylinder of the engine provided at a position next to the first cylinder far from the one end in the length direction, the pressure detecting mechanism detects the pressure of the intake air in the position between the first branch portion and the second branch portion, which is taken out and transmitted through an intake air pressure obtaining path, at a position in the length direction closer to the one end than the intake air whose temperature is detected by the temperature detecting mechanism. ​

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