JP4542489B2 - Exhaust manifold internal temperature estimation device for internal combustion engine - Google Patents

Description

  The present invention relates to an exhaust manifold internal temperature estimating device for an internal combustion engine, and more particularly to an exhaust manifold internal temperature estimating device for an internal combustion engine that estimates an internal temperature of the exhaust manifold of an internal combustion engine equipped with a supercharger.

  Conventionally, when controlling an internal combustion engine, the oxygen concentration in a cylinder is estimated using an intake / exhaust system model, and the amount of harmful substances released from exhaust gas is reduced. At that time, the gas temperature in the exhaust manifold, that is, the temperature in the exhaust manifold is estimated, and the estimated temperature is used as the gas temperature in the EGR device (exhaust gas recirculation device), the input energy in the intake manifold, and the gas temperature in the intake manifold. It is used for estimation.

  As a method for estimating the temperature in the exhaust manifold of an internal combustion engine equipped with a supercharger and an EGR device, a method has been proposed in which calculation is performed using a function having TEX as an argument expressed by the following equation (1) (Patent Literature). 1).

TEX = kGf · qfin · NE · Φ · (Pb / Pex) (1)
However, kGf is a constant, qfin is a command fuel injection amount [g / s], NE is an engine speed [rpm], Φ is an equivalence ratio, Pb is a supercharging pressure, and Pex is an exhaust manifold internal pressure.
JP 2004-156457 A (paragraphs [0064] to [0068] in FIG. 1, FIG. 1)

  However, a comparison between the exhaust manifold temperature estimated by the function with TEX represented by equation (1) as an argument and the measured value of the exhaust manifold temperature confirmed that a deviation occurs depending on the engine speed. It was. Specifically, when the relationship between the exhaust manifold internal temperature T4 and the argument TEX is shown, as shown in FIG. 4, in the region where the engine speed is 2000 rpm or less, the argument TEX and the actually measured exhaust manifold internal temperature T4 The deviation is small, but the deviation becomes large in the region where the engine speed is 2400 rpm or more. Therefore, in the region where the engine rotation speed is 2400 rpm or more, if another value necessary for engine control is estimated using the exhaust manifold temperature T4 estimated using the argument TEX represented by the equation (1), There is a problem that accuracy deteriorates.

  The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to provide an exhaust manifold internal temperature estimation device for an internal combustion engine capable of estimating the exhaust manifold internal temperature more accurately than the prior art. is there.

  The inventor of the present application has investigated the cause of the difference between the estimated value and the actual measurement value according to the equation (1) in the case where a variable nozzle supercharger (variable nozzle turbocharger) is used as a supercharger. As a result, it was found that the difference in energy for driving the turbine depending on the degree of restriction of the variable nozzle affects the argument TEX, and the present invention has been achieved.

In order to achieve the above object, an invention according to claim 1 includes a supercharger and fuel injection amount corresponding value acquisition means for acquiring a fuel injection amount corresponding value corresponding to an injection amount of fuel injected into the engine. The intake air amount acquisition means for acquiring the flow rate of the intake air sucked into the engine, the supercharging pressure acquisition means for acquiring the supercharging pressure, the exhaust manifold pressure acquisition means for acquiring the pressure in the exhaust manifold, An air amount changing means for increasing / decreasing the amount of air pumped by the supercharger, an engine speed detecting means for detecting the engine speed, the fuel injection amount corresponding value, the intake air amount, the supercharging pressure, the exhaust manifold pressure, and an exhaust manifold temperature estimating means for estimating the exhaust manifold temperature based on the aperture amount of the engine speed and the air amount changing means A exhaust manifold temperature estimation apparatus for an internal combustion engine.

Further, in the invention described in claim 1, when the exhaust manifold temperature estimation means estimates the exhaust manifold temperature , the exhaust manifold temperature is estimated by a function having Tex as an argument expressed by the following equation.

Tex = qfin × qwt × faiq × pim / pex / vnpos
However, qfin: indicated injection amount, qwt: fuel flow rate = k1 × qfin × NE × efg
faiq: equivalence ratio = k2 × qfin × efg / ega1st
Pb: Supercharging pressure, efg: Fuel density, ega1st: Intake air amount, NE: Engine rotation speed Pex: Exhaust manifold pressure vnpos: Variable nozzle throttle area coefficient = (1-epvnfin / 100) + EPVNOF
EPVNOF: Variable nozzle throttle area coefficient offset term epvnfin: Variable nozzle throttle opening [%]
k1: constant, k2: constant.

The unit of each quantity is the indicated injection amount [mm ³ / st], fuel flow rate [g / s], supercharging pressure [kPa], fuel density [g / cm ³ ], intake air amount [g / st], engine Assuming that the rotation speed [rpm] and the exhaust manifold pressure [kPa], the constant k1 = 2/60/1000 and the constant k2 = 14.5 / 1000.

In this invention, the fuel injection amount is acquired by the fuel injection amount corresponding value acquisition means, the flow rate of intake air is acquired by the intake air amount acquisition means, and the boost pressure is acquired by the boost pressure acquisition means. As the injection amount, the command injection amount may be used without actually measuring the injection amount, and the supercharging pressure is obtained from, for example, an intake pressure sensor. The pressure in the exhaust manifold may be obtained by installing a pressure sensor, but using the estimation formula, the fuel injection amount per unit time, the actual fresh air flow rate, the supercharging pressure, and the throttle amount of the air amount changing means are used. It may be estimated. Then, the exhaust manifold temperature estimation means estimates the exhaust manifold temperature based on the fuel injection amount, the intake air amount, the boost pressure, the exhaust manifold pressure, the engine rotation speed, and the throttle amount of the air amount changing means.
In addition, according to the present invention, the exhaust manifold temperature can be accurately estimated based on the equipment normally equipped for operation control of the internal combustion engine and the detection signal of the sensor.
According to a second aspect of the present invention, in the first aspect of the present invention, the supercharger is a variable nozzle type turbocharger that is operated by an exhaust flow, and a movable vane in the turbine as the air amount changing means. And the opening degree of the vane can be changed by an actuator. The present invention can be suitably applied to an internal combustion engine including a variable nozzle turbocharger that is generally used as a supercharger.

  According to the present invention, the exhaust manifold temperature can be estimated more accurately than in the prior art.

  Hereinafter, an embodiment in which the present invention is embodied in a diesel engine exhaust manifold temperature estimation device will be described with reference to FIGS. FIG. 1 is a schematic diagram showing a diesel engine (hereinafter simply referred to as an engine) and its peripheral configuration.

  As shown in FIG. 1, an engine 11 as an internal combustion engine (engine) includes a plurality of cylinders 12, and a fuel injection valve 14 is attached to a cylinder head 13 corresponding to each cylinder 12 for each cylinder 12. Yes.

  An intake manifold 15 and an exhaust manifold 16 are connected to the cylinder head 13. The intake manifold 15 is connected to an intake passage (intake pipe) 17. An air cleaner 18 is provided at the inlet of the intake passage 17. The intake passage 17 is disposed so as to pass near the outlet of the exhaust manifold 16.

  The exhaust manifold 16 has an outlet connected to the exhaust passage 21 via the turbine 20 of the supercharger 19. An exhaust purification device 22 is provided in the exhaust passage 21. In this embodiment, a DPNR (diesel, particulate, NOx, reduction system) is used as the exhaust purification device 22. A fuel addition valve 23 is provided between the turbine 20 and the exhaust purification device 22.

  A compressor 24 of the supercharger 19 is provided in the intake passage 17. The supercharger 19 is a known variable nozzle turbocharger that is operated by an exhaust flow. The variable nozzle turbocharger drives the compressor using rotational torque generated in the turbine by the action of the exhaust flow as a drive source, and pumps air. The turbine 20 includes a plurality of movable vanes in a nozzle portion, and the opening degree of the vanes can be changed by an actuator 20a such as a cylinder or a motor. The turbine 20 and the actuator 20a constitute air amount changing means for increasing or decreasing the amount of air pumped by the supercharger 19. The compressor 24 is provided with a rotational torque corresponding to the exhaust flow velocity determined from the exhaust pressure at the outlet of the exhaust manifold 16 and the vane opening.

  An intercooler 25 is provided in the intake passage 17 downstream of the supercharger 19. The intake passage 17 is provided with an intake pressure sensor 26, a throttle valve 27 for adjusting the intake air amount, and an intake air temperature sensor 28 between the intercooler 25 and the inlet of the intake manifold 15. The intake pressure sensor 26 generates a signal representing the pressure in the intake passage (intake pressure, supercharging pressure). The intake pressure sensor 26 constitutes a supercharging pressure acquisition unit that acquires a supercharging pressure. The intake air temperature sensor 28 detects the temperature of fresh air taken into the intake passage 17 via the air cleaner 18 (that is, fresh air temperature), and generates a signal representing the fresh air temperature.

  An air flow meter 29 is provided in the intake passage 17 on the upstream side of the compressor 24. A hot-wire air flow meter is used as the air flow meter 29. The air flow meter 29 measures the mass flow rate (the amount of intake air per unit time, the amount of fresh air per unit time) of the atmosphere (ie, fresh air) newly sucked into the intake passage 17 via the air cleaner 18. A signal (fresh air flow) corresponding to the mass flow of the fresh air is generated. The air flow meter 29 constitutes intake air amount acquisition means for acquiring the flow rate of intake air taken into the engine 11.

  The engine 11 is an engine with an exhaust gas recirculation device (EGR device), and an exhaust gas circulation passage (EGR pipe) 30 is provided between the exhaust manifold 16 and the intake manifold 15 to recirculate part of the exhaust gas to the intake system. ing. One end of the exhaust circulation passage 30 is connected to the exhaust manifold 16, and the other end is connected to the intake manifold 15. An EGR valve 31 and an EGR cooler 32 are provided in the exhaust circulation passage 30, and the EGR gas supply amount from the exhaust system of the engine 11 to the intake system can be adjusted by adjusting the opening of the EGR valve 31.

  The engine 11 is controlled by an ECU (electronic control unit) 33. The ECU 33 includes a microcomputer 33a. The microcomputer 33a includes a memory (ROM and RAM) 33b as a storage device. The ECU 33 is electrically connected to various sensors via an input interface, and is electrically connected to various actuators and the like via an output interface. The ECU 33 receives detection signals of various sensors for detecting the engine operating state. In FIG. 1, for the convenience of illustration, a part of the arrow line indicating the detection signal of the sensor and the command signal from the ECU 33 is omitted.

  The ROM of the ECU 33 stores maps, formulas, and the like used to determine various command values (control values) to be commanded for engine control based on the operating state of the engine 11 obtained from the signals of the various sensors. Has been. The map, formula, and the like include, for example, a map for determining the fuel injection timing from the fuel injection valve 14 and a fuel injection amount, a formula, a map for estimating the exhaust manifold temperature, a formula, and the like. The ROM stores a program for executing fuel injection control of the fuel injection valve 14, a program for estimating the exhaust manifold temperature, and the like.

  The sensors include an intake pressure sensor 26, an intake air temperature sensor 28, an air flow meter 29, an engine rotation speed sensor 34 as an engine rotation speed detection means, a water temperature sensor 35, and an accelerator opening sensor 36.

  The engine rotation speed sensor 34 detects the rotation speed of the engine 11, generates a signal representing the engine rotation speed NE, and can detect the absolute crank angle of each cylinder. The water temperature sensor 35 detects the cooling water temperature of the engine 11 and generates a signal representing the cooling water temperature. The accelerator opening sensor 36 detects an operation amount of an accelerator pedal (not shown), and generates a signal representing the accelerator opening (accelerator operation amount).

  The ECU 33 performs various controls of the engine 11 such as the fuel injection amount of the fuel injection valve 14 and the fuel addition period, the drive amount of the actuator that opens and closes the throttle valve 27, the opening degree of the EGR valve 31, and the like. Further, the ECU 33 estimates the gas temperature in the exhaust manifold, that is, the exhaust manifold temperature.

  Each fuel injection valve 14 is opened for a predetermined time by a drive signal from the ECU 33 (command signal corresponding to the command fuel injection amount qfin), and is supplied from a fuel injection pump (not shown) connected to the fuel tank. High pressure fuel is injected.

  The actuator 20a adjusts the opening degree of the movable vane according to the drive signal from the ECU 33, and makes the exhaust gas passage area flowing into the turbine 20 variable. When the exhaust gas passage area flowing into the turbine 20 is reduced, the supercharging pressure is increased, and when the exhaust gas passage area flowing into the turbine 20 is increased, the supercharging pressure is reduced.

The EGR valve 31 controls the EGR rate by changing the amount of exhaust gas recirculated (EGR gas flow rate) according to the drive signal from the ECU 33.
Next, the operation of the apparatus configured as described above will be described.

  ECU33 grasps | ascertains an operating state from detection signals, such as the airflow meter 29, the engine speed sensor 34, the water temperature sensor 35, and the accelerator opening degree sensor 36. FIG. Then, the fuel injection amount from the fuel injection valve 14, the fuel injection timing, and the exhaust ring flow rate are calculated so that an appropriate combustion state corresponding to the grasped engine operating state (load state) is obtained, and the fuel injection valve 14 And the EGR valve 31 and the like are controlled.

  The ECU 33 estimates the EGR gas temperature and the EGR rate when performing the EGR control. At that time, the gas temperature in the exhaust manifold, that is, the value of the exhaust manifold temperature is required, and the exhaust manifold temperature must also be estimated. is there.

The ECU 33 estimates the exhaust manifold temperature using a function having Tex represented by the following equation (2) as an argument.
Tex = qfin × qwt × faiq × Pb / Pex / vnpos (2)
However, qfin is the command injection amount [mm ³ / st], qwt is the fuel flow rate [g / s], and is expressed by the following equation (3).

qwt = qfin × NE × 2/60 × efg / 1000 (3)
faiq is an equivalent ratio and is represented by the following formula (4).
faiq = 14.5 × qfin × efg / 1000 / ega1st (4)
Further, Pb is a supercharging pressure [kPa], efg is a fuel density [g / cm ³ ], ega1st is an intake air amount [g / st], NE is an engine speed [rpm], Pex is an exhaust manifold pressure [kPa]. In this embodiment, Pex is not an actual measured value by the sensor, but an estimated value calculated by an expression described later. vnpos is a variable nozzle aperture area coefficient and is expressed by the following equation (5).

vnpos = (1-epvnfin / 100) + EPVNOF (5)
However, epvnfin is a variable nozzle aperture opening [%], and EPVNOF is a variable nozzle aperture area coefficient offset term. EPVNOF is obtained in advance for each engine model by a test and stored in the memory 33b. The variable nozzle throttle opening epvnfin becomes a throttle amount corresponding value corresponding to the throttle amount of the air amount changing means for increasing or decreasing the amount of air pumped by the supercharger 19. Therefore, when estimating the exhaust manifold internal temperature, the ECU 33 estimates the exhaust manifold internal temperature using a function having a variable including a variable obtained by dividing the exhaust manifold internal pressure by the throttle amount corresponding value. That is, the ECU 33 estimates the exhaust manifold temperature based on the fuel injection amount corresponding value, the intake air amount, the supercharging pressure, the exhaust manifold internal pressure, the engine rotation speed, and the throttle amount of the air amount changing means. The estimation means is configured.

  The ECU 33 estimates the exhaust manifold internal temperature T4 according to the flowchart of FIG. In step S1, the ECU 33 reads data on the command injection amount qfin, the engine speed NE, the fuel density efg, the intake air amount ega1st, and the supercharging pressure Pb. The fuel density efg is obtained in advance corresponding to the fuel to be used, and is stored in the memory 33b. The command injection amount qfin is obtained from the command value of the ECU 33. At this time, the ECU 33 constitutes fuel injection amount corresponding value acquisition means for acquiring a fuel injection amount corresponding value corresponding to the fuel injection amount injected into the engine. The supercharging pressure Pb is obtained from the detection signal of the intake pressure sensor 26.

  Next, in step S2, the ECU 33 calculates the fuel flow rate qwt from the instructed injection amount qfin, the engine speed NE, and the fuel density efg using the equation (3). Next, in step S3, the ECU 33 calculates an equivalence ratio faiq from the command injection quantity qfin, the fuel density efg, and the intake air quantity ega1st using the equation (4).

Next, in step S4, the ECU 33 calculates the exhaust manifold pressure Pex by the following equation (6). Equation (6) is the same as that described in Patent Document 1.
Pex = fPex (XPex) (6)
However, XPex = (Gf + Gaact) · Pb / Kvn, and Kvn = Avn + avn.

  Here, Gf: fuel injection amount per unit time (g / s), Gaact: actual fresh air flow rate (g / s), Pb: supercharging pressure, Kvn: variable capacity turbocharger throttle coefficient, Avn: variable capacity turbo Charger opening (0 to 100%), avn: positive constant.

  The function fPex and the constant avn are obtained in advance for each engine model by a test and stored in the memory 33b. The variable capacity turbocharger opening degree Avn is the same as the variable nozzle throttle opening degree epvnfin. At this time, the ECU 33 constitutes an exhaust manifold internal pressure acquisition means for acquiring the pressure in the exhaust manifold 16.

  Next, in step S5, the ECU 33 calculates the variable nozzle aperture area coefficient vnpos using the equation (5) from the variable nozzle aperture opening epvnfin and the variable nozzle aperture area coefficient offset term EPVNOF. As described above, the values qfin, qwt, faiq, Pb, Pex, and vnpos for obtaining the argument Tex of the function for estimating the exhaust manifold temperature expressed by the equation (2) are obtained.

  Next, in step S6, the ECU 33 calculates the argument Tex using the expression (2), and then in step S7 calculates the exhaust manifold internal temperature T4 using a map or expression using Tex as an argument.

  The exhaust manifold temperature T4 calculated as described above is used to estimate the EGR gas temperature, EGR rate, intake manifold input energy, and intake manifold gas temperature.

  When TEX represented by the conventional equation (1) is used as an argument of the function used for estimating the exhaust manifold internal temperature T4, as shown in FIG. The temperature T4 has a good correlation with the argument TEX. However, when the engine rotation speed increases to 2400 rpm, 2800 rpm, or 3200 rpm, the characteristic curve deviates. That is, if the exhaust manifold temperature T4 is estimated in the high rotational speed region of 2400 rpm or higher using the characteristic curve shown by the solid line in FIG.

  On the other hand, in this embodiment, instead of the conventional argument TEX expressed by the expression (1), the argument Tex expressed by the expression (2), that is, the argument TEX expressed by the expression (1) is changed to the variable nozzle aperture area coefficient. What is divided by vnpos is used. In this case, as shown in FIG. 3, it was confirmed that the exhaust manifold temperature T4 has a good correlation with the argument Tex even in the high rotation speed region where the engine rotation speed is 2400 rpm or more.

  The reason is considered as follows. In the supercharger 19, the actuator 20a adjusts the vane opening of the turbine 20, that is, the air amount changing means changes the throttle amount, whereby the amount of air pumped by the supercharger 19 is increased or decreased. When the throttle amount increases, the pressure in the exhaust manifold 16 increases, and when the pressure increases, the temperature in the exhaust manifold 16 also increases. The increased temperature is used as energy for driving the turbine 20 of the supercharger 19. In the conventional argument TEX of the expression (1), the exhaust manifold pressure Pex is used as a divisor, so the characteristic curve has a configuration in which the exhaust manifold temperature decreases even if the pressure in the exhaust manifold 16 increases. However, since the expression (2) representing the argument Tex in this embodiment is a configuration in which the exhaust manifold pressure Pex is divided by the variable nozzle throttle area coefficient vnpos, the throttle amount is taken into consideration, and in the high speed rotation region of the engine. Also, deviation from the characteristic curve is suppressed.

  In FIG. 4, the correlation coefficient was 0.977, whereas in FIG. 3, the correlation coefficient increased to 0.987, confirming improvement in estimation accuracy. When the actual injection amount was used instead of the command injection amount qfin, the relationship between the exhaust manifold temperature T4 and the argument Tex was examined in the same manner as in FIG. 3, and the correlation coefficient was improved to 0.992. .

This embodiment has the following effects.
(1) When the ECU 33 estimates the temperature in the engine 11 provided with the supercharger 19, the throttle amount corresponding value corresponding to the throttle amount of the air amount changing means for increasing or decreasing the amount of air pumped by the supercharger 19 is obtained. The exhaust manifold temperature is estimated using a function that includes the variable that contains it as an argument. Therefore, when estimating the exhaust manifold temperature, the exhaust manifold temperature is compared with the conventional technology compared to the case of using a function that does not use a variable that includes a throttle amount corresponding value corresponding to the throttle amount of the air amount changing means. It can be estimated with high accuracy.

  (2) The supercharger 19 is a variable nozzle turbocharger that is operated by an exhaust flow. The turbocharger 19 includes a movable vane in the turbine as air amount changing means, and the opening degree of the vane can be changed by an actuator. Yes. Therefore, the exhaust manifold temperature can be accurately estimated in the engine 11 equipped with the variable nozzle turbocharger generally used as a supercharger.

  (3) The ECU 33 estimates the exhaust manifold temperature using a function having Tex represented by the equation (2) as an argument. Therefore, the exhaust manifold temperature can be accurately estimated based on the equipment normally equipped for operation control of the internal combustion engine and the detection signal of the sensor.

(4) Since the fuel flow rate is calculated from the commanded injection amount, the engine rotational speed NE and the fuel density, a sensor for detecting the fuel flow rate and the injection amount becomes unnecessary.
(5) The supercharging pressure is detected by the intake pressure sensor 26, and an estimated value is used as the exhaust manifold internal pressure Pex instead of the actual exhaust manifold internal pressure. This eliminates the need for a dedicated boost pressure sensor or a sensor for detecting the pressure in the exhaust manifold.

The embodiment is not limited to the above, and may be configured as follows, for example.
○ The argument of the function representing the exhaust manifold temperature only needs to include the throttle amount corresponding value corresponding to the throttle amount of the air amount changing means for increasing or decreasing the amount of air pumped by the turbocharger as a variable. It is not limited to the argument Tex used.

  ○ An actually measured value may be used as the exhaust manifold pressure Pex instead of the estimated value. In that case, it is necessary to provide a sensor for detecting the pressure in the exhaust manifold.

○ The actual injection amount may be used in place of the command injection amount, but the exhaust manifold temperature can be estimated with higher accuracy than in the past even if the command injection amount is used.
O Instead of measuring the supercharging pressure with the intake pressure sensor 26, a dedicated supercharging pressure sensor may be provided.

  The exhaust purification device 22 is not limited to the DPNR. For example, a PM (particulate matter) removing filter (DPF) may be used, or the DPF and the catalyst device may be independent from each other.

The engine 11 is not limited to the configuration in which the cylinders 12 are arranged in one row, and may be applied to a V-type engine or a horizontal engine arranged in two rows.
○ The internal combustion engine is not limited to a diesel engine, but may be applied to a gasoline engine. Moreover, you may apply not only to the engine of a vehicle but to stationary engines, such as an engine for power generators.

  ○ The injection timing tends to advance (advance) as the engine rotation changes from a low region to a high region, and is therefore dependent on rotation. Therefore, the estimation accuracy can be improved by making the map for estimating the exhaust manifold temperature a two-dimensional map having Tex and NE (engine speed) as axes.

The following technical idea (invention) can be understood from the embodiment.
(1) before SL internal combustion engine is a diesel engine.

The schematic diagram which shows the engine of one Embodiment, and its periphery structure. The flowchart which shows the estimation procedure of the temperature in an exhaust manifold. The graph which shows the influence of a variable nozzle aperture area coefficient. The graph which shows the influence of an engine speed when not considering a variable nozzle aperture area coefficient.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Engine as an internal combustion engine, 16 ... Exhaust manifold, 19 ... Supercharger, 20 ... Turbine which comprises air quantity change means, 20a ... Similarly actuator, 26 ... Intake pressure sensor as supercharging pressure acquisition means, 29 ... An air flow meter as intake air amount acquisition means, 33... ECU constituting fuel injection amount corresponding value acquisition means and exhaust manifold internal pressure acquisition means, 34... Engine rotation speed sensor as engine rotation speed detection means.

Claims (2)

A turbocharger ,
Fuel injection amount corresponding value acquisition means for acquiring a fuel injection amount corresponding value corresponding to an injection amount of fuel injected into the engine;
Intake air amount acquisition means for acquiring the flow rate of intake air sucked into the engine;
A supercharging pressure acquisition means for acquiring a supercharging pressure;
Exhaust manifold pressure acquisition means for acquiring the pressure in the exhaust manifold;
An air amount changing means for increasing or decreasing the amount of air pumped by the supercharger;
Engine rotation speed detection means for detecting the rotation speed of the engine;
Exhaust manifold internal temperature for estimating the exhaust manifold internal temperature based on the fuel injection amount corresponding value, the intake air amount, the supercharging pressure, the exhaust manifold internal pressure, the engine speed, and the throttle amount of the air amount changing means An exhaust manifold temperature estimation device for an internal combustion engine, comprising: an estimation means ;
The exhaust manifold internal temperature estimating means estimates the exhaust manifold internal temperature by a function having Tex expressed by the following equation as an argument when estimating the exhaust manifold internal temperature.
Tex = qfin × qwt × faiq × Pb / Pex / vnpos
However, qfin: indicated injection amount, qwt: fuel flow rate = k1 × qfin × NE × efg
faiq: equivalence ratio = k2 × qfin × efg / ega1st
Pb: supercharging pressure, efg: fuel density, ega1st: intake air amount
NE: Engine speed
Pex: Exhaust manifold pressure
vnpos: variable nozzle aperture area coefficient = (1−epvnfin / 100) + EPVNOFEEPVNOF: variable nozzle aperture area coefficient offset term
epvnfin: Variable nozzle throttle opening [%]
k1: constant, k2: constant The turbocharger is a variable nozzle type turbocharger actuated by the exhaust stream, wherein said an air amount movable vanes to the turbine as a changing unit, and is capable of changing the opening degree of the vane by an actuator Item 2. The exhaust manifold internal temperature estimation device according to Item 1 .

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