JP2009013849A - Control device for diesel engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device for a diesel engine capable of accurately estimating exhaust pressure and exhaust temperature, and accurately calculating an EGR rate. <P>SOLUTION: The diesel engine 10 is equipped with an EGR device 70 for taking in gas from a passage 50a (exhaust passage) and making it flow in a passage 40a (intake passage). An ECU 100 has a function (fuel information obtaining means) for obtaining at least one of a theoretical air-fuel ratio, density, and a heat generating amount as fuel property information which is information regarding the property of the supplied fuel; and a function (exhaust state estimating means) for estimating the exhaust pressure and the exhaust temperature in the exhaust passage (passage 50a) based on the obtained fuel property. Even when a fuel with a different property from the prescribed diesel fuel is supplied, by reflecting the obtained fuel property information (theoretical air-fuel ratio, density, heat generation amount), a more accurate exhaust temperature and exhaust pressure can be estimated. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a control technique for a diesel internal combustion engine, and more particularly to calculation of an EGR rate in a diesel internal combustion engine equipped with an exhaust gas recirculation (EGR) device.

  In a diesel-type internal combustion engine (hereinafter simply referred to as “diesel engine”), in order to reduce harmful components in exhaust gas such as nitrogen oxides, in general, a part of exhaust gas discharged from a cylinder is used. A so-called exhaust gas recirculation device (hereinafter referred to as an EGR device) is provided in which the gas is taken in from the exhaust passage, flows into the intake passage, and flows again into the cylinder from the intake passage. The EGR device allows inert exhaust gas to flow into the cylinder from the intake passage along with fresh air, thereby increasing the gas charging efficiency in the cylinder and reducing pump loss. In addition, the inflow of inert gas in the cylinder The combustion temperature is lowered to suppress the generation of harmful components such as nitrogen oxides in the exhaust gas.

  Such an EGR device is generally provided with an EGR passage that connects the exhaust passage and the intake passage, and an EGR valve that controls the flow rate of exhaust gas flowing through the EGR passage (hereinafter referred to as EGR gas). By controlling the opening degree of the EGR valve by the actuator, the flow rate of the inactive EGR gas flowing into the cylinder is adjusted to an optimum value.

  As a diesel engine provided with an EGR device, for example, there is one described in Patent Document 1 below. This diesel engine controls the fuel injection timing and ignition timing in addition to the EGR device and the throttle valve according to the temperature of the exhaust purification catalyst, thereby suppressing the generation of nitrogen oxides and at the time of start-up warm-up We are trying to activate the exhaust purification catalyst early.

Japanese Utility Model Publication No. 6-30512

  By the way, as a control variable for controlling the diesel engine, there is an “EGR rate” indicating the ratio of the flow rate of EGR gas to the flow rate of gas flowing into the cylinder. The control device of the diesel engine controls the opening degree of the EGR valve via the actuator so that the EGR rate becomes an optimum value. The control device of the diesel engine controls the opening degree of the EGR valve based on the calculated EGR rate, and adjusts the ratio of the EGR gas in the cylinder to an optimum value, thereby reducing harmful components in the exhaust gas. I am trying. Therefore, it is necessary to calculate the EGR rate with high accuracy in a control device for a diesel engine.

  By the way, since EGR gas is high-temperature burned gas, it is difficult to directly detect the flow rate of EGR gas flowing into the cylinder (hereinafter simply referred to as “EGR gas flow rate”). In the apparatus, the flow rate of fresh air flowing into the cylinder (hereinafter simply referred to as “inflowing fresh air flow rate”) is usually calculated from the flow rate of gas flowing into the cylinder (hereinafter simply referred to as “inflowing gas flow rate”). By dividing, the EGR gas flow rate is calculated. Note that “fresh air” means air sufficiently containing oxygen introduced from the outside air duct. The inflow fresh air flow rate can be detected with high accuracy by detecting it from an air flow meter provided in the diesel engine.

  On the other hand, the inflow gas flow rate is calculated based on the engine rotation speed of the diesel engine and a predetermined map, and the calculated basic flow rate after the fresh air and EGR gas are merged. Correction is performed using the gas temperature, that is, the temperature of the gas sucked into the cylinder (hereinafter simply referred to as “intake air temperature”) and the pressure of the gas sucked into the cylinder (hereinafter referred to as intake pressure). ing. As the intake pressure, for example, a boost pressure detected by a boost pressure sensor can be used. On the other hand, the intake air temperature is calculated based on the exhaust gas temperature and the exhaust gas pressure. That is, in order to accurately obtain the “inflow gas flow rate” and the “EGR rate”, it is necessary to accurately estimate the exhaust temperature and the exhaust pressure.

  The exhaust temperature and the exhaust pressure are estimated using a map showing the relationship between the inflow fresh air flow rate and the fuel injection amount. The map for estimating the exhaust gas temperature and the exhaust gas pressure is obtained by conducting a fitting experiment using a light oil (diesel fuel) having a predetermined fuel property as a reference. For this reason, in the diesel engine, when a fuel having a different fuel property from a predetermined light oil is supplied, there is a problem that it is impossible to accurately estimate the exhaust pressure and the exhaust temperature in the exhaust passage.

  The present invention has been made in view of the above, and even when fuels having different fuel properties are supplied, the exhaust pressure and the exhaust temperature can be estimated more accurately and the EGR rate can be accurately calculated. An object of the present invention is to provide a control device for a diesel engine.

  A control device for a diesel engine according to the present invention is a control device for a diesel engine that includes an EGR device that takes gas from an exhaust passage and flows it into an intake passage, and is fuel property information that is information related to the properties of fuel that is supplied. A fuel information acquisition unit that acquires at least one of the theoretical air-fuel ratio, density, and calorific value; and an exhaust state estimation unit that estimates exhaust pressure and exhaust temperature in the exhaust passage based on the acquired fuel property information And an EGR rate calculating means for calculating an EGR rate based on the estimated exhaust gas temperature and exhaust gas pressure.

  In the control device for a diesel engine according to the present invention, the fuel information acquisition unit acquires the heat generation amount, and the exhaust state estimation unit estimates the exhaust pressure based on the acquired heat generation amount. it can.

  In the control device for a diesel engine according to the present invention, the fuel state acquisition means may acquire the density, and the exhaust state estimation means may estimate the exhaust pressure based on the acquired density.

  In the control device for a diesel engine according to the present invention, the exhaust state estimating means can estimate the exhaust temperature based on the estimated exhaust pressure.

  In the control device for a diesel engine according to the present invention, the fuel information acquisition means acquires the theoretical air-fuel ratio, and the exhaust state estimation means estimates the exhaust temperature based on the acquired theoretical air-fuel ratio. be able to.

  In the control apparatus for a diesel engine according to the present invention, the fuel information acquisition means may acquire the density, and the exhaust state estimation means may estimate the exhaust temperature based on the acquired density.

  In the control device for a diesel engine according to the present invention, the fuel information acquisition means acquires the fuel property information every time the diesel engine is started. When the fuel property information is different from the previous value, the fuel property information And an exhaust state estimating means for estimating the exhaust temperature and the exhaust pressure based on the updated fuel property information.

  According to the present invention, even when a fuel having a fuel property different from that of the predetermined light oil is supplied, the obtained fuel property information (theoretical air-fuel ratio, density, and calorific value) is reflected to more accurately perform exhaust. Temperature and exhaust pressure can be estimated. Based on the estimated exhaust gas temperature and exhaust gas pressure, the EGR rate can be calculated with high accuracy.

  Hereinafter, the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. In addition, constituent elements in the following embodiments include those that can be easily assumed by those skilled in the art or those that are substantially the same.

  First, schematic configurations of a diesel engine and a vehicle system according to the present embodiment will be described with reference to FIG. FIG. 1 is a schematic diagram showing a schematic configuration of a vehicle system including a diesel engine. In FIG. 1, only the main parts related to the present invention are schematically shown for the diesel engine and the vehicle system.

  The diesel engine according to the present embodiment is a compression self-ignition internal combustion engine that spontaneously ignites the fuel by supplying the fuel to the atmosphere in the combustion chamber that has been compressed to a high temperature. A diesel engine is mounted on a motor vehicle as a prime mover, and the motor vehicle is provided with an electronic control unit (hereinafter referred to as an ECU) as control means for controlling a vehicle system including the diesel engine. Hereinafter, one cylinder among the plurality of cylinders of the diesel engine will be described.

  As shown in FIG. 1, the diesel engine 10 is a so-called direct injection type diesel engine 10 in which a fuel injection device 30 provided for each cylinder directly injects fuel into the cylinder. The diesel engine 10 includes a turbocharger 60 that compresses intake air by the kinetic energy of exhaust gas discharged from the cylinder, and a part of the exhaust gas discharged from the cylinder is taken from the exhaust passage and flows into the intake passage. A so-called exhaust gas recirculation device 70 (hereinafter referred to as an EGR device) is provided. In order to control the diesel engine 10 configured as described above, the vehicle system 1 is provided with an electronic control device 100 (hereinafter referred to as an ECU) for the diesel engine 10.

  The diesel engine 10 is provided with a cylinder block 12, a piston 16, a connecting rod 17, a crankshaft 18, and a cylinder head 20 as parts of an engine body system in which a cylinder is formed. A cylinder bore 14 is formed in the cylinder block 12, and the piston 16 reciprocates in the cylinder bore 14 by a piston ring (not shown) slidingly contacting an inner wall surface 15 (hereinafter referred to as a cylinder wall) of the cylinder bore 14. Exercise.

  The mechanical power generated by the diesel engine 10 is output from the crankshaft 18 by the reciprocating motion of the piston 16 being converted into the rotational motion of the crankshaft 18 via the connecting rod 17. In the vicinity of the crankshaft 18, a crank angle sensor 80 for detecting a rotation angle position of the crankshaft (hereinafter referred to as a crank angle) is provided. The crank angle sensor 80 sends a signal related to the detected crank angle to the ECU 100.

  Further, the cylinder block 12 is provided with a water temperature sensor 82 for detecting the temperature of cooling water circulating through the engine body (12, 20) of the diesel engine 10 (hereinafter simply referred to as “water temperature”). The water temperature sensor 82 sends a signal related to the detected water temperature to the ECU 100.

  A cylinder head 20 is coupled to the cylinder block 12 so as to face the top surface of the piston 16 and close the cylinder bore 14. The wall surface 22 facing the top surface of the piston 16 in the cylinder head 20 is hereinafter referred to as a ceiling wall.

  The space surrounded by the cylinder wall 15 of the cylinder block 12, the top surface of the piston 16, and the ceiling wall 22 of the cylinder head 20 described above is a so-called “cylinder”.

  The cylinder head 20 is provided with an intake port 24 that guides intake air from an intake passage, which will be described later, into the cylinder on one side of the cylinder bore 14 with the axis of the cylinder bore 14 interposed therebetween. An exhaust port 26 for discharging exhaust gas from the inside to an exhaust passage to be described later is formed.

  The cylinder head 20 is provided with intake and exhaust valves (not shown) corresponding to the cylinder side openings of the intake port 24 and the exhaust port 26. These intake and exhaust valves are driven by receiving mechanical power from the camshaft 28.

  The camshaft is rotationally driven by receiving mechanical power from the crankshaft 18. That is, the intake valve and the exhaust valve open and close according to the rotation angle position (crank angle) of the crankshaft 18. In the vicinity of the camshaft 28, a cam angle sensor (not shown) for detecting a rotation angle position of the camshaft (hereinafter referred to as a cam angle) is provided. The cam angle sensor sends a signal related to the detected cam angle to the ECU 100.

  When the intake valve is opened, the intake port 24 communicates with the inside of the cylinder, and the diesel engine 10 can intake air in an intake passage, which will be described later, from the intake port 24 into the cylinder. When the exhaust valve is opened, the exhaust port 26 communicates with the inside of the cylinder, and the diesel engine 10 can exhaust the exhaust gas in the cylinder from the exhaust port 26 to an exhaust passage described later. .

  The diesel engine 10 includes an external air duct 41 that introduces air from outside air, and an air cleaner that removes dust from the intake air (hereinafter referred to as intake air) as intake system parts that guide air from outside air into the cylinder. 42, an air flow meter 88 for measuring the flow rate of the intake air, an intercooler 45 for cooling the air compressed by the turbocharger 60, a throttle valve 46 for adjusting the flow rate of the intake air, and the intake air for each cylinder. An intake manifold 48 is provided as a distribution pipe that distributes the air.

  The intake manifold 48 is connected to the cylinder head 20 on the downstream side in the flow direction of intake air (hereinafter simply referred to as “downstream side”), and the passage 40a formed in the intake manifold 48 is connected to the intake port 24 of each cylinder. Communicating with

  On the other hand, a throttle valve 46 is provided on the upstream side of the intake manifold 48 in the flow direction of the intake air (hereinafter simply referred to as “upstream side”). The throttle valve 46 adjusts the incoming fresh air flow rate sucked into the cylinder. The opening degree of the throttle valve 46 is controlled by the ECU 100.

  The intake manifold 48 is provided with a supercharging pressure sensor 92 that detects the pressure of the intake air in the passage 40a (hereinafter referred to as supercharging pressure). Specifically, the supercharging pressure sensor 92 detects the supercharging pressure (intake pressure) in the passage 40a between the throttle valve 46 and the cylinder. The supercharging pressure sensor 92 sends a signal related to the detected supercharging pressure to the ECU 100.

  An intake pipe 47 is connected to the upstream side of the throttle valve 46. The passage 40 c formed in the intake pipe 47 communicates with the passage 40 a in the intake manifold 48. An intercooler 45 is connected to the upstream side of the intake pipe 47. The intercooler 45 is configured as a heat exchanger, and cools the intake air that has been compressed by a compressor 62 of the turbocharger 60 described later and has reached a high temperature.

  The intake pipe 47 is provided with an intake air temperature sensor 90 that detects the temperature of intake air in the passage 40c (hereinafter referred to as intake air temperature). Specifically, the intake air temperature sensor 90 detects the intake air temperature in the passage 40 c between the intercooler 45 and the throttle valve 46. The intake air temperature sensor 90 sends a signal related to the detected intake air temperature to the ECU 100.

  An intake pipe 44 is connected to the upstream side of the intercooler 45. The passage 40e formed in the intake pipe 44 communicates with the passage 40c in the intake pipe 47 via a passage (not shown) in the intercooler 45. A compressor 62 of the turbocharger 60 is connected to the upstream side of the intake pipe 44. The passage 40e in the intake pipe 44 communicates with the compressor housing 62a of the turbocharger 60.

  An intake pipe 43 is connected to the upstream side of the compressor 62 of the turbocharger 60. A passage 40 g formed in the intake pipe 43 communicates with the compressor 62 of the turbocharger 60. An air cleaner 42 is connected to the upstream side of the intake pipe 43, and an outside air duct 41 is provided on the upstream side of the air cleaner 42. The passage 40 g in the intake pipe 43 communicates with the outside air duct 41 through the air cleaner 42.

  An air flow meter 88 is provided on the downstream side of the element of the air cleaner 42. The air flow meter 88 is a flow rate of air sufficiently containing oxygen introduced from the outside air duct 41 (hereinafter referred to as fresh air), that is, a flow rate of fresh air flowing into the cylinder (hereinafter referred to as “intake air amount”). ) Is detected. The air flow meter 88 sends a signal related to the detected intake air amount to the ECU 100.

  Further, an outside air temperature sensor 86 for detecting the temperature of the intake air flowing from the outside air duct 41 is provided at the same place as the air flow meter 88. The outside air temperature sensor 86 sends a signal related to the detected outside air temperature to the ECU 100.

  The fresh air introduced from the outside air duct 41 passes through the air cleaner 42, the flow rate is detected by the air flow meter 88, and is compressed by the compressor 62 of the turbocharger 60. The fresh air that has been compressed to a high temperature is cooled by the intercooler 45 and flows to the throttle valve 46. The fresh air whose flow rate is adjusted by the throttle valve 46 flows into the intake manifold 48 and flows into each cylinder provided in the diesel engine 10.

  The “intake passage” means a passage formed by the above-described intake system components and intake piping, through which fresh air introduced from the outside air duct passes before flowing into the cylinder. In the present embodiment, the intake passage includes not only the passage 40 a in the intake manifold 48 but also the intake port 24 of the cylinder head 20.

  Further, the diesel engine 10 includes an exhaust manifold 52 that joins exhaust gases from the cylinders and leads them to the turbocharger 60 as exhaust system parts that exhaust the exhaust gases from the cylinders to the outside air, and a turbocharger. An exhaust pipe 53 that guides exhaust gas from the machine 60 to the outside air, and an exhaust purification catalyst (not shown) that purifies harmful components in the exhaust gas are provided. A passage 50a (exhaust passage) is formed in the exhaust manifold 52, and exhaust gases discharged from a plurality of cylinders of the diesel engine 10 are joined together and guided to a turbine 64 of a turbocharger 60 described later. .

  The turbocharger 60 has a compressor 62 provided between the intake pipe 43 and the intake pipe 44 and a turbine 64 provided between the exhaust manifold 52 and the exhaust pipe 53. is doing. A compressor wheel 62c that compresses air by rotating is accommodated in the housing 62a of the compressor 62, and a turbine wheel 64c that is rotationally driven by the flow of exhaust gas is accommodated in the housing 64a of the turbine 64. ing. The compressor wheel 62c and the turbine wheel 64c are integrally coupled.

  In the turbocharger 60, the turbine wheel 64c and the compressor wheel 62c are rotationally driven by the kinetic energy of the exhaust gas flow flowing into the turbine housing 64a from the passage 50a (exhaust passage), and the air in the compressor housing 62a is compressed. To the intercooler 45. The exhaust gas in the turbine housing 64a flows downstream in the exhaust pipe 53, and after harmful components in the exhaust gas are purified by an exhaust purification catalyst (not shown), the exhaust gas is released to the outside air.

  The turbocharger 60 in the present embodiment is a so-called variable nozzle turbocharger 60, and a plurality of movable blades 67 provided on the upstream side of the turbine wheel 64c in the turbine housing 64a and movable. And an actuator 68 for driving the wing 67. The actuator 68 changes the attitude (inclination) of the movable blade 67 so that the turbocharger 60 has a variable nozzle opening (hereinafter referred to as “Vn opening”) that is a flow path width between adjacent movable blades 67. Can be adjusted). The Vn opening degree of the turbocharger 60 is controlled by the ECU 100 via the actuator 68.

  The “exhaust passage” means a passage through which exhaust gas discharged from the cylinder passes before flowing into the turbine 64 of the turbocharger 60. In this embodiment, the exhaust passage includes not only the passage 50 a in the exhaust manifold 52 but also the exhaust port 26 of the cylinder head 20.

  The diesel engine 10 is provided with a fuel injection device 30 as a fuel supply system component for supplying fuel into the cylinder. The fuel injection device 30 is provided for each cylinder, and a nozzle portion (not shown) provided with an injection hole is disposed in the center portion of the ceiling wall 22 of the cylinder head 20 so as to be exposed in the cylinder. Yes. Each fuel injection device 30 is supplied with fuel at a predetermined fuel pressure (for example, 180 MPa) from a common fuel rail (not shown).

  The fuel injection device 30 is composed of a piezo-type fuel injection valve, and can perform fuel injection a plurality of times during one cycle. The injection period of the fuel injection device 30 in each cycle, that is, the injection timing and the injection time length (valve opening time) are controlled by the ECU 100 via a driver unit (not shown).

  Further, the diesel engine 10 is provided with a so-called exhaust gas recirculation device 70 (hereinafter referred to as an EGR device) that takes a part of the exhaust gas discharged from the cylinder from the exhaust passage and flows it into the intake passage. . The EGR device 70 includes an EGR passage that connects the exhaust passage and the intake passage, an EGR valve 77 that adjusts the flow rate of exhaust gas that flows through the EGR passage (hereinafter referred to as EGR gas), an EGR cooler 74 that cools the EGR gas, The details will be described below.

  The exhaust manifold 52 described above is provided with an EGR gas intake 71, and an EGR pipe 72 is connected to the intake 71. An EGR cooler 74 is connected to the EGR pipe 72 on the downstream side in the flow direction of the EGR gas (hereinafter simply referred to as “downstream side”). The EGR cooler 74 is constituted by a heat exchanger, and can cool the inflow EGR gas. An EGR pipe 76 is connected to the downstream side of the EGR cooler 74.

  An EGR valve 77 is disposed at the downstream end of the EGR pipe 76. The EGR valve 77 is an electromagnetic valve. An EGR pipe 78 is connected to the downstream side of the EGR valve 77. The EGR pipe 78 connects an EGR gas outlet 79 provided in the intake manifold 48 and an EGR valve 77. The opening degree of the EGR valve 77 is controlled by the ECU 100.

  The “EGR passage” is formed by the EGR pipes 72, 76, 78, the EGR cooler 74, and the EGR valve 77 until the exhaust gas introduced from the intake port 71, that is, the inert gas, reaches the outlet 79. It means the flow path that passes through. In the present embodiment, the EGR passage includes not only the passage in the EGR pipes 72, 76, and 78 but also the passage formed in the EGR cooler 74 and the EGR valve 77. That is, the flow rate of EGR gas flowing through the EGR passage is controlled by the ECU 100 via the EGR valve 77.

  When the EGR valve 77 is opened, the EGR device 70 takes a part of the exhaust gas flowing through the passage 50a, that is, the exhaust passage, from the intake 71 into the EGR passage. Then, after the exhaust gas (EGR gas) taken into the EGR passage is cooled by the EGR cooler 74, the flow rate is adjusted by the EGR valve 77, and flows from the outlet 79 to the passage 40a, that is, the intake passage. The EGR gas flowing into the intake passage is mixed with fresh air sufficiently containing oxygen introduced from the outside air duct 32 and flows into each cylinder from the intake port 24.

  In this way, the EGR device 70 increases the gas charging efficiency in the cylinder and reduces the pump loss by causing the EGR gas, which is an inert exhaust gas containing almost no oxygen, to flow into the cylinder from the intake passage. At the same time, the combustion temperature in the cylinder can be lowered to suppress the generation of nitrogen oxides.

  The vehicle system 1 including the diesel engine 10 described above is provided with an accelerator pedal position sensor 102 that detects the amount of operation of the accelerator pedal by the driver. The accelerator pedal position sensor 102 sends a signal related to the detected accelerator pedal operation amount (hereinafter referred to as accelerator operation amount) to the ECU 100. In addition, the vehicle system 1 is provided with an atmospheric pressure sensor 104 that detects the atmospheric pressure in an environment where the automobile is placed. The atmospheric pressure sensor 104 sends a signal related to the detected atmospheric pressure to the ECU 100.

  Further, the vehicle system 1 is provided with a fuel temperature sensor 106 for detecting the temperature of fuel supplied into the fuel tank (hereinafter referred to as fuel temperature). The fuel temperature sensor 106 sends a signal related to the fuel temperature to the ECU 100.

  Further, the vehicle system 1 is provided with a function of detecting information (hereinafter referred to as fuel property information) relating to the properties of the fuel supplied (hereinafter referred to as fuel information detecting means and indicated by reference numeral 108 in FIG. 1). It has been. The fuel property information includes at least one of the theoretical air fuel ratio of the fuel, the density of the fuel, and the calorific value of the fuel. This fuel information detecting means 108 can be realized by providing a fuel property sensor capable of detecting fuel property information in a fuel tank (not shown) for storing fuel to be supplied to the diesel engine 10, for example. The fuel information detection means 108 sends the detected fuel property information to the ECU 100.

  In the vehicle system 1 configured as described above, the ECU 100 detects a signal related to the crank angle from the crank angle sensor 80, a signal related to the water temperature from the water temperature sensor 82, and a signal related to the outside air temperature from the outside air temperature sensor 86. And a signal relating to the intake air amount from the air flow meter 88, a signal relating to the intake air temperature of fresh air from the intake air temperature sensor 90, and a signal relating to the supercharging pressure from the supercharging pressure sensor 92. ECU 100 also receives a signal related to the amount of accelerator operation from accelerator pedal position sensor 102, a signal related to atmospheric pressure from atmospheric pressure sensor 104, and a signal related to fuel temperature from fuel temperature sensor 106. In addition, the ECU 100 receives signals relating to the theoretical air-fuel ratio, density, and heat generation amount as fuel property information of the fuel supplied from the fuel information detection means 108 described above.

  Based on these signals, the ECU 100 calculates various control variables. The control variables include the crankshaft rotation angle position (crank angle), the crankshaft rotation speed (hereinafter referred to as engine rotation speed), and the mechanical power output from the crankshaft by the diesel engine 10 (hereinafter referred to as engine load). ), Water temperature, outside air temperature, intake air amount, intake air temperature, supercharging pressure, accelerator operation amount, atmospheric pressure, fuel temperature, and the like. Further, the ECU 100 calculates the theoretical air-fuel ratio, density, and heat generation amount as fuel property information of the fuel that has been supplied. Further, the ECU 100 calculates an average air amount [g / sec] per hour introduced from the outside air duct from the detected intake air amount.

  The ECU 100 determines the fuel injection amount of the fuel injection device 30, the opening degree of the throttle valve 46, and the Vn opening degree of the variable nozzle turbocharger 60 based on the operating state of the diesel engine 10 ascertained from these control variables. Then, the opening degree of the EGR valve 77 can be determined and controlled.

Incidentally, in the diesel engine 10, there is an EGR rate as a control parameter for determining the opening degree of the EGR valve 77. The “EGR rate” is the ratio of the flow rate of EGR gas to the flow rate of gas flowing into the cylinder. The EGR rate is calculated by the following equation (e).
(EGR rate) = ((inflow gas flow rate) − (inflow fresh air flow rate)) / (inflow gas flow rate)
... (e)

  Here, the “inflow gas flow rate” is a flow rate of gas flowing into the cylinder from the intake passage, and the gas includes fresh air and EGR gas. On the other hand, the inflow fresh air flow rate is a flow rate of fresh air flowing into the cylinder from the intake passage, and does not include EGR gas. The unit of the inflow gas flow rate and the inflow fresh air flow rate is [g / rev]. The inflow fresh air flow rate [g / rev] can be calculated from the average air amount [g / sec] calculated based on the signal from the air flow meter 88 and the engine speed.

  The EGR rate has an optimum value according to the operating state of the diesel engine 10, and the ECU 100 sets a target EGR rate (hereinafter referred to as a target EGR rate) according to the operating state of the diesel engine 10. The actuators (EGR valve 77, throttle valve 46, etc.) are controlled so that the actual EGR rate matches the target EGR rate. Therefore, the ECU 100 needs to accurately calculate the actual EGR rate based on the control variables obtained from various sensors. In calculating the EGR rate, the inflow fresh air flow rate can be accurately calculated from the intake air amount (average air amount) detected by the air flow meter 88.

  On the other hand, as the inflow gas flow rate, a basic flow rate (basic flow rate) is calculated from the engine rotation speed of the diesel engine 10 and a predetermined map, and further, the fresh air and the EGR gas merge with the calculated basic flow rate. Correction is made using the temperature of the later gas, that is, the temperature of the gas sucked into the cylinder (hereinafter simply referred to as “intake air temperature”) and the pressure of the gas sucked into the cylinder (hereinafter referred to as intake pressure). It is carried out. The boost pressure detected by the boost pressure sensor 92 can be used as the intake pressure. On the other hand, the intake air temperature is calculated based on the exhaust gas temperature and the exhaust gas pressure. That is, in order to accurately obtain the “inflow gas flow rate” and the “EGR rate”, it is necessary to accurately estimate the exhaust temperature and the exhaust pressure in the exhaust passage into which the EGR gas is taken.

  The exhaust temperature and the exhaust pressure are estimated using a map showing the relationship between the inflow fresh air flow rate and the fuel injection amount. Since the map for estimating the exhaust temperature and the exhaust pressure is obtained by performing a conformity experiment based on diesel oil having a predetermined fuel property, in a diesel engine, the map of the predetermined diesel oil and fuel property is obtained. When different fuels are supplied, there arises a problem that the exhaust pressure and the exhaust temperature cannot be accurately estimated. That is, there arises a problem that a “deviation” generated between the estimated exhaust pressure and exhaust temperature and the actual value becomes large.

  Therefore, in the control device (ECU) for the diesel engine according to the present embodiment, the theoretical air-fuel ratio, density, and calorific value are acquired as information relating to the properties of the fuel that has been refueled (hereinafter referred to as fuel property information). It has a fuel information acquisition means and an exhaust state estimation means for estimating the exhaust pressure and exhaust temperature in the exhaust passage based on the acquired fuel property information, and EGR based on the estimated exhaust temperature and exhaust pressure. The rate is calculated and will be described below with reference to FIGS. FIG. 2 is a flowchart showing a fuel change determination routine executed by the ECU. FIG. 3 is a flowchart showing an exhaust pressure estimation routine executed by the ECU. FIG. 4 is a flowchart showing an exhaust temperature estimation routine executed by the ECU.

  First, the fuel change determination routine will be described with reference to FIGS. 1 and 2. The fuel change determination routine is performed every time the diesel engine 10 is started. Specifically, in the vehicle vehicle system 1 of the automobile on which the diesel engine 10 is mounted, the ignition relay that supplies power to various components of the diesel engine 10 is turned on. When it becomes (ON), the ECU 100 starts.

  When the fuel change determination routine is started, first, in step S100, the ECU 100 initializes the fuel change flag to an off state. The fuel change flag is a flag for determining whether or not the fuel property information has changed from the previous time. When the flag is in an ON state, this time the fuel property information is different from the previous time. Indicates that there has been a change in information.

  In step S102, the ECU 100 stores the previously stored fuel property information value (hereinafter referred to as the previous value) stored in a flash memory (not illustrated) (hereinafter simply referred to as “memory”) in the memory. Is obtained as a control variable. The fuel property information includes the theoretical air-fuel ratio, fuel density, and heat generation amount of the fuel supplied at the previous refueling.

  Note that the diesel engine 10 is adapted to the control constants related to the fuel property information by performing an experiment or the like using diesel fuel (light oil) having a predetermined property. In the ECU 100, fuel property information obtained by using diesel fuel having a predetermined property, that is, the theoretical air-fuel ratio, density, and calorific value is preset as control constants and stored in a ROM (not shown) of the ECU 100. Has been.

  In step S <b> 104, the ECU 100 newly acquires fuel property information from the fuel information detection unit 108. The control variable related to the fuel property information includes the theoretical air-fuel ratio, the density, and the heat generation amount of the fuel supplied at the time of the current refueling. Hereinafter, the fuel property information obtained at the time of refueling will be referred to as “current value”.

  The method for acquiring the fuel property information is not limited to the method for acquiring the fuel property information from the fuel information detection means 108 such as the above-described fuel property sensor. For example, when refueling, an automobile user or a fuel station staff operates an input device (not shown) to transmit fuel property information to the ECU 100, and the ECU 100 may acquire it. Further, at the time of refueling, the fuel property information may be automatically sent to the ECU 100 from a device provided in the fuel stand to acquire the fuel property information.

  In step S110, the ECU 100 determines whether or not the fuel property information is the same as the previous value stored in the memory and the current value obtained during the current refueling. That is, it is determined whether or not the fuel supplied this time has substantially the same properties as the fuel supplied last time. Specifically, among the control variables, the theoretical air-fuel ratio, density, and calorific value are compared with the previous value and the current value, respectively.

  If the fuel property information is the same between the previous value and the current value (Yes), that is, if it is determined that the fuel supplied this time is substantially the same as the fuel supplied last time, the ECU 100 executes the fuel determination routine. finish.

  On the other hand, when it is determined that the fuel property information is different (No) between the previous value and the current value, that is, when it is determined that the fuel supplied this time is not substantially the same as the fuel supplied last time, the ECU 100 Updates the fuel property information from the previous value to the current value (S112). ECU 100 overwrites the previous value with the current value of the fuel property information and stores it in the memory.

  In step S114, the ECU 100 supplies the fuel having the property different from the fuel supplied last time, that is, at least one physical property among the theoretical air-fuel ratio, density, and calorific value of the fuel. After determining that the value has changed and turning on the fuel change flag, the fuel determination routine is terminated.

  Next, the exhaust pressure estimation routine will be described with reference to FIGS. The exhaust pressure estimation routine estimates the exhaust pressure according to the operating state of the diesel engine 10 and is repeatedly executed when the diesel engine 10 is in operation.

  First, in step S120, the ECU 100 determines whether or not the fuel change flag is on. That is, it is determined whether or not there is a change in the properties of the fuel supplied and it is necessary to newly update the fuel property information used for estimating the exhaust pressure.

  When it is determined that the fuel change flag is in the on state (Yes), the ECU 100 acquires the fuel property information stored in the memory, that is, the theoretical air-fuel ratio, density, and calorific value (S122). The fuel property information used in the exhaust pressure estimation routine is updated to the acquired fuel property information. That is, the acquired fuel property information is used in the current exhaust pressure estimation routine.

  On the other hand, when it is determined that the fuel change flag is not in the on state (No), the ECU 100 does not update the fuel property information used in the exhaust pressure estimation routine. The fuel property information used from the previous time is used as it is in the present exhaust pressure estimation routine.

  In step S <b> 124, the ECU 100 acquires a control variable related to the operating state of the diesel engine 10. These control variables include fuel temperature [K], fuel injection amount [mm3 / st], engine speed [rpm], Vn opening [%], average air amount [g / sec], supercharging pressure [Pa]. And atmospheric pressure [Pa].

  The “Vn opening degree” is an index indicating the opening degree of the flow path formed between the movable blades in the variable nozzle supercharger, and is 0% when the flow path is fully open and when the flow path is fully closed. A value of 100% is obtained.

In step S126, ECU 100 calculates the specific gravity of the fuel based on the density and the fuel temperature. Specifically, the fuel temperature correction coefficient is calculated from the fuel temperature and a predetermined fuel temperature correction coefficient map, and the specific gravity of the fuel is calculated from the fuel temperature correction coefficient and the density by the following equation (1).
(Specific gravity) = (Density) × (Fuel temperature correction coefficient) (1)
Note that a fuel temperature correction coefficient map showing the relationship between the fuel temperature correction coefficient and the density is obtained in advance by a matching experiment or the like, and is stored in a ROM (not shown) of the ECU as a control constant. Thus, the density as the acquired fuel property information is reflected in the specific gravity of the fuel.

In step S128, the ECU 100 performs unit conversion of the fuel injection amount. Based on the fuel injection amount [mm3 / st], which is a volume injection amount per cylinder injection, the engine rotational speed, and the calculated specific gravity, the ECU 100 uses the following equation (2) to calculate per cylinder per second. The fuel injection amount [g / sec], which is the mass injection amount of is calculated.
(Fuel injection amount [g / sec]) = (fuel injection amount [mm3 / st]) × (engine rotational speed) × 2/60 × (density) / 1000 (2)

In step S130, the ECU 100 calculates the turbo throttle area by the following equation (3) based on the Vn opening.
(Turbo throttle area) = (1−Vn opening / 100) (3)
That is, when the Vn opening is fully closed (100%), the turbo throttle area is zero, and when it is fully open (0%), the turbo throttle area is “1”.

In step S132, the ECU 100 sets the average air amount [g / sec], the fuel injection amount [g / sec], the heat generation amount acquired in step S122, the predetermined light oil heat generation amount, the supercharging pressure, and the turbo throttle area. Based on the following equation (4), the exhaust pressure map argument is calculated.
(Exhaust pressure map argument) = (intake air amount) + ((fuel injection amount) × (acquired heat generation amount) / heat generation amount of predetermined light oil)) × supercharging pressure × turbo throttle area (4)

  Here, the exhaust pressure map argument is an index for calculating the standard exhaust pressure using a predetermined map described later. The calorific value of the predetermined light oil is set to 42.96 [MJ / kg]. In the present embodiment, the “calorific value” of the fuel means “low calorific value” that does not include latent heat of vapor. The intake air amount indicates the amount of air per time detected by the air flow meter 88. Thus, the stoichiometric air-fuel ratio as the acquired fuel property information is reflected in the exhaust pressure map argument.

  In step S134, ECU 100 calculates an exhaust pressure under standard conditions (hereinafter referred to as a standard exhaust pressure) from an exhaust pressure map argument. Specifically, the standard exhaust pressure is calculated from an exhaust pressure map argument and a predetermined standard exhaust pressure map indicating the relationship between the exhaust pressure map argument and the standard exhaust pressure. The standard exhaust pressure map is obtained in advance by a matching experiment or the like, and is stored in the ROM of the ECU 100 as a control constant.

  The “standard condition” means a standard environmental condition in which an experiment for adapting various control constants of the diesel engine 10 is performed, and the diesel engine 10 is adapted at a predetermined atmospheric pressure. That is, the “standard exhaust pressure” is obtained as a differential pressure (gauge pressure) with respect to a predetermined atmospheric pressure.

In step S136, the ECU 100 calculates the exhaust pressure based on the standard exhaust pressure and the atmospheric pressure. Specifically, the environmental pressure is calculated from the atmospheric pressure and a predetermined environmental pressure map showing the relationship between the atmospheric pressure and the environmental pressure. At the same time, the exhaust pressure, which is the absolute pressure in the exhaust passage (passage 50a), is calculated from the environmental pressure and the standard exhaust pressure by the following equation (5).
(Exhaust pressure) = (Standard exhaust pressure) + (Environmental pressure) (5)
Note that an environmental pressure map indicating the relationship between the environmental pressure and the atmospheric pressure is obtained in advance by a conformance experiment or the like, and is stored in the ROM of the ECU 100 as a control constant. After estimating the exhaust pressure in the passage 50a (exhaust passage) in step S136, the process returns to step S120 again.

  As described above, the ECU 100 estimates the exhaust pressure in the passage 50a (exhaust passage) shown in FIG. 1 based on the fuel property information (theoretical air-fuel ratio, density, and calorific value) acquired in step S122. Can do. Since the density as the fuel property information is reflected in the calculation of the specific gravity of the fuel (S126), the specific gravity of the fuel is accurately calculated even when fuel having a fuel property different from the predetermined light oil is supplied. can do. In addition, the calculation of the exhaust pressure map argument indicating the exhaust pressure (S132) reflects the stoichiometric air-fuel ratio as the fuel property information, so that the fuel having a fuel property different from that of the predetermined light oil is supplied. However, the exhaust pressure in the passage 50a (exhaust passage) can be accurately estimated.

  Next, the exhaust gas temperature estimation routine will be described with reference to FIGS. The exhaust gas temperature estimation routine estimates the exhaust gas temperature according to the operating state of the diesel engine 10 and is repeatedly executed when the diesel engine 10 is in operation.

  First, in step S150, the ECU 100 determines whether or not the fuel change flag is on. That is, it is determined whether or not there is a change in the properties of the fuel supplied and it is necessary to newly update the fuel property information used for estimating the exhaust pressure.

  When it is determined that the fuel change flag is in the on state (Yes), in step S152, the ECU 100 displays the theoretical air-fuel ratio as the fuel property information stored in the memory and the temperature corrected density [g / cm3]. get. The “temperature corrected density” is obtained by correcting the density as the fuel property information by the fuel temperature. Further, the fuel injection amount [g / sec], which is the mass injection amount per second, calculated in step S128 of the exhaust pressure estimation routine is acquired.

  On the other hand, when it is determined that the fuel change flag is not in the on state (No), the ECU 100 does not update the fuel property information used in the exhaust gas temperature estimation routine. The fuel property information used from the previous time is used as it is in the exhaust temperature estimation routine of this time.

  In step S154, the ECU 100 acquires a control variable related to the operation state of the diesel engine 10. These control variables include fuel temperature [K], fuel injection amount [mm3 / st], average air amount [g / sec], water temperature [° C.], fresh air intake temperature [° C.], and supercharging pressure [Pa]. , And fuel injection amount [mm3 / st].

In step S156, the ECU 100 converts the average air amount [g / sec] into a unit to obtain the intake air amount per rotation [g / rev], and per cylinder according to the following equation (6). The amount of fresh air inflow [g / st] is calculated.
(Inflow fresh air amount [g / st]) = (intake air amount per rotation [g / rev]) / 2
... (6)

In step S158, the ECU 100 calculates an equivalence ratio by the following equation (7) based on the theoretical air fuel ratio of the fuel, the fuel injection amount, the fuel density, and the inflow fresh air amount.
(Equivalent ratio) = (theoretical air / fuel ratio) × (fuel injection amount) × (temperature corrected density) / 1000 / (inflow fresh air amount) (7)

  The equivalence ratio is an index indicating the concentration of the fuel supplied to the intake air in the cylinder, and is the ratio between the actual fuel amount and the fuel amount when burning at the stoichiometric air-fuel ratio. In the equivalent ratio calculated by the above equation (7), the density as the acquired fuel property information is reflected.

In step S160, the ECU 100 sets an exhaust temperature map argument by the following equation (8) based on the equivalence ratio, the fuel injection amount, the supercharging pressure, and the exhaust pressure calculated by the exhaust pressure estimation routine described above. calculate.
(Exhaust temperature map argument) = (fuel injection amount) × (equivalent ratio) × (supercharging pressure) / (estimated exhaust pressure) (8)

  Here, the exhaust temperature map argument is an index for calculating the standard exhaust temperature using a predetermined map described later. The calculation of the exhaust gas temperature map argument includes the exhaust gas pressure estimated as the equivalence ratio, and the acquired fuel property information (theoretical air-fuel ratio, density, and calorific value) is reflected.

  In step S162, ECU 100 calculates an exhaust temperature under standard conditions (hereinafter referred to as standard exhaust temperature) from the exhaust temperature map argument. Specifically, the standard exhaust temperature is calculated from an exhaust temperature map argument and a predetermined standard exhaust temperature map indicating the relationship between the exhaust temperature map argument and the standard exhaust temperature. The standard exhaust temperature map is obtained in advance by a conformance experiment or the like, and is stored in the ROM of the ECU 100 as a control constant.

  The “standard condition” means a standard environmental condition in which an experiment for adapting various control constants of the diesel engine 10 is performed, and the diesel engine 10 is adapted at a predetermined outside air temperature.

In step S164, ECU 100 calculates the exhaust temperature based on the standard exhaust temperature, the water temperature, and the fresh air intake temperature. Specifically, the water temperature correction coefficient for the exhaust gas temperature is calculated from a predetermined water temperature correction map showing the relationship between the water temperature and the water temperature correction coefficient for the water temperature and the exhaust gas temperature. At the same time, the intake air temperature correction coefficient of the exhaust air temperature is calculated from a predetermined intake air temperature correction map showing the relationship between the fresh air intake temperature and the intake air temperature correction coefficient of the fresh air intake temperature and the exhaust gas temperature. Then, based on the water temperature correction coefficient, the intake air temperature correction coefficient, and the standard exhaust temperature, the exhaust temperature in the passage 50a (exhaust passage) is calculated by the following equation (9).
(Exhaust temperature) = (Standard exhaust temperature) x (Water temperature correction coefficient) x (Intake temperature correction coefficient) (9)
The intake air temperature correction map indicating the relationship between the air temperature and the intake air temperature correction coefficient of the exhaust temperature and the intake air temperature correction map indicating the relationship between the intake air temperature and the intake air temperature correction coefficient of the exhaust gas temperature are obtained in advance by a conformity experiment or the like. And stored in the ROM of the ECU 100 as a control constant. After estimating the exhaust temperature in the exhaust passage (passage 50a) in step S164, the process returns to step S150 again.

  As described above, the ECU 100 determines the fuel property information (theoretical air-fuel ratio, density) acquired in step S152 and the fuel property information (theoretical air-fuel ratio, density, and heat value) in the exhaust pressure estimation routine (S120 to S136). The exhaust temperature in the exhaust passage (passage 50a, see FIG. 1) can be estimated based on the exhaust pressure estimated based on In the calculation of the equivalence ratio (S158), the stoichiometric air-fuel ratio and density are reflected as fuel property information. Therefore, even when fuel having a fuel property different from the predetermined light oil is supplied, the equivalence ratio is accurately determined. Can be calculated. In addition, in the calculation of the exhaust gas temperature map argument indicating the exhaust gas temperature (S160), the exhaust gas pressure estimated by reflecting the fuel property information (theoretical air-fuel ratio, density, and calorific value) is used. Can accurately estimate the exhaust temperature in the exhaust passage even when fuel having different fuel properties is supplied.

  By executing the exhaust pressure estimation routine and the exhaust temperature estimation routine described above, the ECU 100 reflects the fuel property information of the fuel that is supplied even when fuel having a fuel property different from that of the predetermined light oil is supplied. Thus, the accurate exhaust pressure and exhaust temperature in the exhaust passage can be estimated.

  Based on the estimated exhaust pressure and exhaust temperature, the ECU 100 estimates an “intake gas temperature” that is a gas temperature sucked into the cylinder after the fresh air and the EGR gas merge, and calculates an “inflow gas flow rate”. presume. Then, the EGR rate can be accurately calculated from the estimated “inflow gas flow rate” and the “inflow fresh air flow rate” calculated from the intake air amount detected by the air flow meter by the above-described equation (e). it can.

  As described above, in this embodiment, a function (fuel information acquisition means) that acquires at least one of the theoretical air-fuel ratio, density, and calorific value as fuel property information that is information related to the properties of fuel supplied. ) And the function of estimating the exhaust pressure and exhaust temperature in the exhaust passage based on the acquired fuel property information (exhaust state estimating means), and the function of calculating the EGR rate based on the estimated exhaust temperature and exhaust pressure (EGR rate calculation means), the obtained fuel property information (theoretical air-fuel ratio, density, calorific value) is obtained even when fuel having a fuel property different from the predetermined light oil is supplied. Reflecting this, the exhaust temperature and the exhaust pressure can be estimated more accurately. Based on the estimated exhaust gas temperature and exhaust gas pressure, the EGR rate can be calculated with high accuracy.

  Further, in the present embodiment, the fuel information acquisition means acquires the heat generation amount, and the exhaust state estimation means estimates the exhaust pressure based on the acquired heat generation amount. Even when fuels with different calorific values are supplied, the exhaust pressure can be estimated accurately and the EGR rate can be calculated with high accuracy.

  Further, in this embodiment, the fuel state acquisition means acquires the density, and the exhaust state estimation means estimates the exhaust pressure based on the acquired density, so the predetermined light oil has a density. Even when different fuels are supplied, the exhaust pressure can be accurately estimated and the EGR rate can be calculated with high accuracy.

  In the present embodiment, the exhaust state estimating means estimates the exhaust temperature based on the estimated exhaust pressure, so the exhaust pressure and the exhaust temperature can be estimated accurately, and the EGR rate can be accurately calculated. Can be calculated.

  The fuel information acquisition means acquires the stoichiometric air-fuel ratio, and the exhaust state estimation means estimates the exhaust gas temperature based on the acquired theoretical air-fuel ratio. Even when different fuel is supplied, the exhaust gas temperature can be accurately estimated, and the EGR rate can be calculated with high accuracy.

  The fuel information acquisition means acquires the density, and the exhaust state estimation means estimates the exhaust temperature based on the acquired density, so that light oil having a density different from the predetermined light oil was supplied. Even in this case, the exhaust gas temperature can be accurately estimated, and the EGR rate can be calculated with high accuracy.

  The fuel information acquisition means acquires fuel property information every time the diesel engine is started. When the fuel property information is different from the previous value, the fuel information acquisition means has a function of updating the fuel property information (fuel information update means). And the exhaust state estimation means estimates the exhaust temperature and the exhaust pressure based on the updated fuel property information. If a fuel having a different fuel property from the fuel that was refueled last time is refueled this time, the exhaust temperature and the exhaust gas are based on the updated fuel property information (this value) immediately after starting the diesel engine after refueling. The pressure can be estimated. It is possible to prevent the exhaust pressure and the exhaust temperature from being estimated based on the fuel property information of the fuel different from the fuel supplied.

  In the above-described embodiment, the ECU 100 acquires the theoretical air-fuel ratio, density, and calorific value as the fuel property information of the fuel that has been refueled, and based on the acquired fuel property information (control variable), the exhaust pressure and Although the exhaust gas temperature is estimated, the acquired fuel property information is not limited to the theoretical air fuel ratio, density, and calorific value. For example, the theoretical air-fuel ratio and the calorific value are acquired as the fuel property information (control variable), and the exhaust temperature and exhaust pressure are set for the density using values (control constants) set in advance for a predetermined light oil. It may be estimated. Further, as fuel property information, control variables other than the stoichiometric air-fuel ratio, density, and calorific value, for example, information on fuel evaporation properties, kinematic viscosity, cetane number is acquired, and based on these acquired control variables, The exhaust pressure and the exhaust temperature in the exhaust passage may be estimated.

  In the above-described embodiments, the diesel engine is provided with a variable nozzle turbocharger and an intercooler. However, the configuration of the diesel engine to which the present invention is applicable is not limited to this aspect. Absent. The present invention can be applied to any internal combustion engine having an EGR device that takes gas from the intake passage and flows it into the intake passage. For example, the present invention can also be applied to a diesel engine that is not provided with a supercharger.

  As described above, the control device for a diesel engine according to the present invention is useful for a diesel engine provided with an EGR device that takes gas from an exhaust passage and flows it into an intake passage, and in particular, controls the opening of an EGR valve. This is suitable for a diesel engine equipped with an EGR device capable of adjusting the flow rate of EGR gas flowing from the exhaust passage to the intake passage.

1 is a schematic diagram illustrating a schematic configuration of a vehicle system including a diesel engine according to an embodiment. It is a flowchart which shows the fuel change determination routine which the control apparatus (ECU) of the diesel engine which concerns on an Example performs. It is a flowchart which shows the exhaust pressure estimation routine which the control apparatus (ECU) of the diesel engine which concerns on an Example performs. It is a flowchart which shows the exhaust gas temperature estimation routine which the control apparatus (ECU) of the diesel engine which concerns on an Example performs.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vehicle system 10 Diesel engine 12 Cylinder block 20 Cylinder head 24 Intake port (intake passage)
26 Exhaust port (exhaust passage)
30 Fuel injector (fuel injection valve)
40a passage (intake passage)
42 Air Cleaner 45 Intercooler 46 Throttle Valve 48 Intake Manifold 50a Passage (Exhaust Passage)
52 Exhaust Manifold 60 Turbocharger 62 Compressor 64 Turbine 70 EGR Device 74 EGR Cooler 77 EGR Valve 80 Crank Angle Sensor 82 Water Temperature Sensor 88 Air Flow Meter 90 Intake Air Temperature Sensor 92 Supercharging Pressure (Intake Pressure) Sensor 100 Electron for Diesel Engine Control unit (ECU)
102 Accelerator pedal position sensor

Claims (7)

A control device for a diesel engine equipped with an EGR device that takes gas from an exhaust passage and flows it into an intake passage,
Fuel information acquisition means for acquiring at least one of the theoretical air-fuel ratio, density, and calorific value as fuel property information, which is information related to the properties of fuel supplied;
Exhaust state estimating means for estimating the exhaust pressure and the exhaust temperature in the exhaust passage based on the acquired fuel property information;
EGR rate calculating means for calculating an EGR rate based on the estimated exhaust temperature and exhaust pressure;
A control device for a diesel engine, comprising: The control device for a diesel engine according to claim 1,
The fuel information acquisition means acquires the calorific value,
The exhaust state estimation means estimates the exhaust pressure based on the acquired calorific value,
A diesel engine control device. The control device for a diesel engine according to claim 1 or 2,
The fuel state acquisition means acquires the density,
The exhaust state estimating means estimates the exhaust pressure based on the acquired density.
A diesel engine control device. The control device for a diesel engine according to claim 2 or 3,
The exhaust gas state estimating means estimates the exhaust gas temperature based on the estimated exhaust gas pressure. In the control apparatus of the diesel engine of any one of Claims 1-4,
The fuel information acquisition means acquires the theoretical air-fuel ratio,
The exhaust state estimating means estimates the exhaust temperature based on the acquired theoretical air-fuel ratio,
A diesel engine control device. In the control apparatus of the diesel engine of any one of Claims 1-5,
The fuel information acquisition means acquires density,
The exhaust state estimating means estimates the exhaust temperature based on the acquired density.
A diesel engine control device. In the control apparatus of the diesel engine of any one of Claims 1-6,
Fuel information acquisition means
Each time the diesel engine is started, fuel property information is acquired.
When the fuel property information is different from the previous value, it has a fuel information update means for updating the fuel property information,
The exhaust state estimating means estimates the exhaust temperature and the exhaust pressure based on the updated fuel property information.
A diesel engine control device.

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