DE102008054926B4 - Device for controlling a forced-filled engine - Google Patents

Abstract

Apparatus for controlling a forced-charge engine having a turbocharger (30) with a variable turbine mechanism (53), comprising: means (50, B34) for storing a value of a parameter (ηC, ηm, ηT, ηcmT) containing a Boost pressure in an intake passage downstream of a compressor of the turbocharger (30) and a turbine inlet pressure in an exhaust passage upstream of a turbine of the turbocharger (30) linked to means (50, B20, B31, B32, B33, B35) for controlling the variable turbine mechanism on the The basis for an amount of operation for the variable turbine mechanism, wherein the amount of operation is calculated based on a turbocharger model linking the amount of operation and the turbine inlet pressure, the turbine inlet pressure based on the value of the parameter stored in the storage device and a target boost pressure in the intake passage downstream of the compressor who was on the couch means (23) for detecting an intake air pressure as actual boost pressure, means (54) for detecting a pressure in the exhaust passage upstream of the turbine as an actual turbine inlet pressure, means (50, 15) for calculating an engine operating condition; B34, S208, S218, S228) for calculating an actual value of the parameter based on the actual boost pressure and the actual turbine inlet pressure; andmeans (50, B34, S208, S218, S228) for correcting the value of the parameter stored in the memory means based on the actual value of the parameter.

Description

The present invention relates to an apparatus for controlling a positive-filled engine.

The forcibly filled engine is an internal combustion engine in which the charge air is charged by a charger having a variable turbine mechanism.

Conventionally, a turbocharger is known as a charging device for charging charge air using exhaust gas energy. The turbocharger has a compressor disposed in an intake passage, a turbine disposed at an exhaust passage, and a shaft connecting the compressor and the turbine. When the turbine is rotated by the exhaust gas flowing in the exhaust passage, the shaft transmits the rotational force from the turbine to the compressor, and then the compressor performs charging by compressing intake air in the intake passage.

Recently, a variable turbine mechanism for a turbocharger has been proposed for optimizing turbine behavior and adjusting a boost pressure of intake air to a desired pressure. The variable turbine mechanism varies turbine power. For example, one of the variable turbine mechanisms varies a quantity of exhaust gas that effectively acts on turbine blades to adjust turbine performance. In order to keep the performance of the variable turbine mechanism appropriate, it is important to determine an optimum operation amount for the variable turbine mechanism with respect to an operating state of the engine.

DE 10 2004 016 011 A1 discloses a method and apparatus for operating an internal combustion engine. The internal combustion engine includes a compressor, a turbine and an actuator for adjusting the exhaust gas mass flow through the turbine.

US 6,732,523 discloses an apparatus for controlling a turbocharger with a variable turbine mechanism. The device is installed and uses a mathematical model of the charging device to calculate an optimal operating amount for the variable turbine mechanism, such as an optimal opening degree of the turbine blade. In the above-mentioned document, the optimum operation amount, a target operation amount, is determined on the basis of a target boost pressure. The target boost pressure is a pressure of the intake air that is charged by the charging device. The optimum amount of operation is calculated taking into account losses caused by friction of the compressor, the turbines and the shaft.

In the above document, the model is designed using compressor, turbine, and shaft efficiencies. The efficiencies are used as coefficients that can denote the losses of the compressor, the turbine or the shaft. The efficiencies are predetermined at reference values provided based on an experimental measurement made on an actual product of a turbocharger.

However, all turbocharger products may have different efficiencies depending on a difference in columns, such as a. have a gap between the turbine blade and a housing and a difference in the friction of the shaft. Therefore, the predetermined reference efficiencies may be different than the actual efficiencies of the turbocharger that is actually manufactured. If such differences exist between the predetermined reference efficiencies and the actual efficiencies, an accuracy of the model is reduced, and the operation amount for the variable turbine mechanism can hardly be appropriately calculated. As a result, the controller can not quickly control the boost pressure in response to the target boost pressure.

To solve the above-mentioned problems, it is possible to measure the efficiencies for each individual product of the turbocharger. However, too much experimental work and adjustment effort is required. In addition, the aging of each product of the turbocharger remains. Actual efficiencies gradually change when the product is actually used over a long period of time. Due to such aging, the actual efficiencies may deviate from the predetermined reference efficiencies. Therefore, aging can also reduce the accuracy of the model and prevent the boost pressure from reacting rapidly to the target boost pressure.

In view of the above-mentioned problems, an object of the present invention is to control an apparatus for controlling a forced-charge engine which suppresses the influences of the difference between the products and the aging of the product.

It is another object of the present invention to provide an apparatus for controlling a forced-charge engine that is adaptive to the present state of the charging device, and makes it possible to control the amount of operation of the variable turbine mechanism on the engine Calculate the basis of the adapted state of the charging device.

According to a first invention, an apparatus for controlling a forced-charge engine with a turbocharger (US Pat. 30 ) with a variable turbine mechanism ( 53 ) provided. The system has a device ( 50 . B34 ) for storing a value of a parameter (ηC, ηm, ηT, ηcmT), which is the boost pressure in an intake passage downstream of a compressor of the turbocharger (FIG. 30 ) and a turbine inlet pressure in an exhaust passage upstream of a turbine of the turbocharger (US Pat. 30 ). The system also has a device ( 50 . B20 . B31 . B32 . B33 . B35 ) for controlling the variable turbine mechanism based on an operation amount for the variable turbine mechanism. The amount of operation is calculated based on a turbocharger model that links the amount of operation and the turbine inlet pressure. The turbine inlet pressure is calculated based on the stored value of the parameter in the storage device and a target boost pressure in the intake passage downstream of the compressor, which is calculated based on an operating state of the engine. The system also has a device ( 23 ) for detecting an intake air pressure as actual boost pressure, means ( 54 ) for detecting a pressure in the exhaust passage upstream of the turbine as an actual turbine inlet pressure, means ( 50 . B34 . S208 . S218 . S228 ) for calculating an actual value of the parameter on the basis of the actual boost pressure and the actual turbine inlet pressure, and a device ( 50 . B34 . S208 . S218 . S228 ) for correcting the stored value of the parameter in the memory device based on the actual value of the parameter.

According to a second invention, in the apparatus, the calculating means calculates the actual value of the parameter (ηC, ηm, ηT, ηcmT) on the basis of a theoretical actual compressor power ( WC ), which is calculated on the basis of the actual boost pressure, and a theoretical actual turbine power ( wT ) calculated on the basis of the actual turbine inlet pressure. The parameter links a compressor capacity ( WC . WC ) and a turbine power ( WT . wT ).

Both a theoretical compressor capacity and a loss of the compressor are reflected in a theoretical actual compressor capacity. Both theoretical turbine power and turbine loss are reflected in theoretical actual turbine power.

According to a third invention, in the apparatus, the calculating means calculates the actual value comprising at least one of first, second and third parameters (η C, η m, η T, η cm T) on the basis of a theoretical actual compressor power ( WC ), which is calculated on the basis of the actual boost pressure, and a theoretical actual turbine power ( wT ) calculated on the basis of the actual turbine inlet pressure. The first parameter (ηC) links the turbine power ( WC ) and the theoretical actual compressor capacity ( WC ). The second parameter (ηm) links the theoretical actual turbine power ( wT ) and the theoretical actual compressor capacity ( WC ). The third parameter (ηT) links a theoretical actual turbine power ( wT ) and an actual turbine power ( WT ).

According to a fourth invention, in the apparatus, the calculating means fixes two of the parameters and calculates the actual value of the remaining one of the parameters (ηC, ηm, ηT, ηcmT) on the basis of the theoretical actual compressor power ( WC ) and the theoretical actual turbine power ( wT ).

• 1 ist ein Blockdiagramm eines Kraftmaschinensystems gemäß einem ersten Ausführungsbeispiel der Erfindung;
• 2 ist ein vereinfachtes Blockdiagramm des Kraftmaschinensystems gemäß dem ersten Ausführungsbeispiel der Erfindung;
• 3 ist ein Blockdiagramm, das eine Ladesteuerung gemäß dem ersten Ausführungsbeispiel der Erfindung zeigt;
• 4 ist ein Blockdiagramm, das eine Zielwertsteuerung gemäß dem ersten Ausführungsbeispiel der Erfindung zeigt;
• 5 ist ein Ablaufdiagramm zum Berechnen eines Einlassdrucks auf der Grundlage eines Sollladedrucks gemäß dem ersten Ausführungsbeispiel der Erfindung;
• 6 ist eine Graphik, die eine Beziehung zwischen einer theoretischen Verdichterleistung und einem Verdichterwirkungsgrad gemäß dem ersten Ausführungsbeispiel der Erfindung zeigt;
• 7 ist eine Graphik, die eine Beziehung zwischen einer Verdichterleistung und einem mechanischen Wirkungsgrad gemäß dem ersten Ausführungsbeispiel der Erfindung zeigt;
• 8 ist eine Graphik, die eine Beziehung zwischen einer Turbinenleistung und einem Turbinenwirkungsgrad gemäß dem ersten Ausführungsbeispiel der Erfindung zeigt;
• 9 ist eine Graphik, die eine Charakteristik einer Turbine gemäß dem ersten Ausführungsbeispiel der Erfindung zeigt;
• 10 ist ein Ablaufdiagramm zum Berechnen eines Soll-Betätigungsbetrags für einen variablen Turbinenmechanismus gemäß dem ersten Ausführungsbeispiel der Erfindung;
• 11 ist ein Ablaufdiagramm zum Durchführen einer Selbstkorrektur eines Turbinenwirkungsgrads gemäß dem ersten Ausführungsbeispiel der Erfindung;
• 12 ist eine Graphik, die eine Beziehung zwischen einer theoretischen Turbinenleistung und einem Turbinenwirkungsgrad gemäß dem ersten Ausführungsbeispiel der Erfindung zeigt;
• 13 ist ein Kennfeld, das eine Verdichterleistung und einen mechanischen Wirkungsgrad gemäß dem ersten Ausführungsbeispiel der Erfindung zeigt;
• 14 ist ein Kennfeld, das eine theoretische Turbinenleistung und einen Turbinenwirkungsgrad gemäß dem ersten Ausführungsbeispiel der Erfindung zeigt;
• 15 ist ein Ablaufdiagramm zum Durchführen einer Selbstkorrektur eines mechanischen Wirkungsgrads gemäß einem zweiten Ausführungsbeispiel der Erfindung;
• 16 ist ein Kennfeld, das eine Verdichterleistung und einen mechanischen Wirkungsgrad gemäß dem zweiten Ausführungsbeispiel der Erfindung zeigt;
• 17 ist ein Ablaufdiagramm zum Durchführen einer Selbstkorrektur eines Verdichterwirkungsgrads gemäß einem dritten Ausführungsbeispiel der Erfindung; und
• 18 ist ein Kennfeld, das eine theoretische Verdichterleistung und einen Verdichterwirkungsgrad gemäß dem dritten Ausführungsbeispiel der Erfindung zeigt.

Additional objects and advantages of the present invention will become apparent from the following detailed description of preferred embodiments when taken in conjunction with the accompanying drawings.

• 1 Fig. 10 is a block diagram of an engine system according to a first embodiment of the invention;
• 2 is a simplified block diagram of the engine system according to the first embodiment of the invention;
• 3 Fig. 10 is a block diagram showing a charging control according to the first embodiment of the invention;
• 4 Fig. 10 is a block diagram showing a target value control according to the first embodiment of the invention;
• 5 Fig. 10 is a flowchart for calculating an intake pressure based on a target boost pressure according to the first embodiment of the invention;
• 6 Fig. 12 is a graph showing a relationship between a theoretical compressor power and a compressor efficiency according to the first embodiment of the invention;
• 7 Fig. 12 is a graph showing a relationship between a compressor power and a mechanical efficiency according to the first embodiment of the invention;
• 8th Fig. 12 is a graph showing a relationship between turbine power and turbine efficiency according to the first embodiment of the invention;
• 9 Fig. 12 is a graph showing a characteristic of a turbine according to the first embodiment of the invention;
• 10 Fig. 10 is a flowchart for calculating a target operation amount for a variable turbine mechanism according to the first embodiment of the invention;
• 11 Fig. 10 is a flowchart for performing a self-correction of turbine efficiency according to the first embodiment of the invention;
• 12 Fig. 12 is a graph showing a relation between a theoretical turbine power and a turbine efficiency according to the first embodiment of the invention;
• 13 Fig. 11 is a map showing a compressor output and a mechanical efficiency according to the first embodiment of the invention;
• 14 FIG. 11 is a map showing a theoretical turbine power and a turbine efficiency according to the first embodiment of the invention; FIG.
• 15 Fig. 10 is a flow chart for performing self-correction of mechanical efficiency according to a second embodiment of the invention;
• 16 Fig. 11 is a map showing a compressor output and a mechanical efficiency according to the second embodiment of the invention;
• 17 Fig. 10 is a flowchart for performing self-correction of compressor efficiency according to a third embodiment of the invention; and
• 18 FIG. 11 is a map showing a theoretical compressor capacity and a compressor efficiency according to the third embodiment of the invention. FIG.

First embodiment

A first embodiment of the invention will be described below with reference to the drawings. The first embodiment is an engine system having an internal combustion engine and an electronic control system for components of the internal combustion engine. The internal combustion engine in the embodiment is a diesel engine. The internal combustion engine may be an intake-injection type of gasoline engine or a direct-injection type gasoline engine. In the following, the internal combustion engine is referred to as an engine. The engine has a charging device that is powered by exhaust energy, such as a turbocharger.

With reference to 1 and 2 has the engine 10 a cylinder block 11 and a piston 12 in the cylinder block 11 is supported. The engine 10 defines a combustion chamber 14 between an inner surface of the cylinder block 11 , the piston 12 and a cylinder head 13 , The cylinder head 13 supports a fuel injector 15 that opens and closes a fuel supply passage in response to an electric control signal. A common rail 16 is as a Kraftstoffzuführelement for supplying pressurized fuel to the fuel injection valve 15 intended. The system further includes a fuel pump, not shown, for pressurizing the fuel in a fuel tank and supplying the pressurized fuel to the common rail 16 on. The fuel injector 15 injects fuel in response to the electrical control signal. The fuel pressure in the common rail 16 is controlled by controlling the fuel pump by an electronic control system that includes a pressure sensor for detecting an actual fuel pressure in the common rail 16 can have.

The engine 10 has an inlet valve 17 in an inlet port and an outlet valve 18 in an outlet port. An inlet passage 21 communicates with the inlet port. The inlet passage 21 has a balance tank 22 , An intercooler 37 is in the inlet passage 21 disposed at a position upstream of the surge tank 22 lies. A pressure sensor 23 for detecting a boost pressure is at the surge tank 22 arranged. The pressure sensor 23 may be referred to as an inlet pressure sensor. An outlet passage 24 is in communication with the outlet port.

A turbocharger 30 is between the inlet passage 21 and the outlet passage 24 Installed. The turbocharger 30 has a housing for defining a compressor spiral and a turbine spiral. The turbocharger 30 provides a compressor, a turbine, a shaft, and a variable turbine mechanism 53 to disposal. The compressor has a Verdichtlaufrad 31 located in the compressor spiral forming part of the inlet passage 21 is. The turbine has a turbine wheel 32 which is disposed in the turbine scroll, which forms part of the exhaust passage 24 is. The compressor impeller 31 and the turbine wheel 32 are through the wave 33 connected, which is rotatably supported on the housing.

The variable turbine mechanism 53 is called VTM 53 designated. The VTM 53 is arranged on the turbine to vary the turbine power by adjusting a quantity of exhaust gas that is effective on the turbine wheel 32 acts. A variety of known mechanisms can be used for the VTM 53 be used in this embodiment. The variable turbine mechanism may be referred to as variable turbine geometry technology or variable turbine nozzle technology. One of the variable turbine mechanisms may change an opening degree of an exhaust passage directly to the turbine wheel 32 leads. The opening degree can be used as the opening amount for the VTM 53 be designated. Alternatively, the VTM 53 change an opening degree or angle of variable vanes that the exhaust gas flow towards the turbine wheel 32 judge.

In the turbocharger, the shaft is shared with the compressor and the turbine, so that the compressor is rotated when the turbine is driven by the exhaust gas. The VTM 53 the rotation of the turbine wheel varies 32 by adjusting the amount of operation for the VTM 53 , such as the degree of opening of the turbine blade. As a result, it is possible to control a lot of air forced into the engine 10 is loaded by the amount of operation of the VTM 53 is set. The intake air passing through the turbocharger 30 is charged through the intercooler 30 cooled and fed to a downstream side. Cooling the intake air through the intercooler 37 allows an increase in the filling efficiency of the intake air into the combustion chamber. A throttle valve 26 is between the intercooler 37 and the equalization tank 22 arranged.

An air filter, not shown, is at an upstream end of the intake passage 21 arranged. An air flow meter 51 to capture a lot of air is between the air filter and the turbocharger 30 arranged. An intake air temperature sensor 52 For detecting a temperature of the intake air is between the air filter and the turbocharger 30 arranged. The engine system further has a plurality of sensors, such as a crank angle sensor 27 , an accelerator pedal sensor 28 and an atmospheric pressure sensor 29 which are arranged at corresponding positions. The crank angle sensor 27 detects predetermined rotational angular positions of a crankshaft of the engine 10 , For example, the crank angle sensor generates 27 a crank angle signal having pulses at intervals indicative of a predetermined angular rotation, for example, 30 degrees crank angle. The accelerator pedal sensor 28 detects an operation amount of an accelerator pedal. In the event that the engine 10 is mounted on a vehicle, detects the accelerator pedal sensor 28 a degree of operation of the accelerator by the driver. The atmospheric pressure sensor 29 detects a pressure of the ambient air.

A turbine inlet pressure sensor 54 is at the exhaust passage 24 arranged. The turbine inlet pressure sensor 54 detects a pressure of the exhaust gas on an upstream side of the turbine. Further, a catalytic converter, not shown, is in the exhaust passage 24 disposed on a downstream side of the turbine. The catalytic converter has a NOx absorber. An exhaust gas recirculation passage (EGR passage) 42 is provided to the exhaust passage 24 and the inlet passage 21 to connect. The EGR passage 42 is with the exhaust passage 24 on an upstream side of the catalytic converter and with the inlet passage 21 on a downstream side of the compressor of the turbocharger 30 connected. An EGR control valve 44 is at the EGR passage 42 arranged around a cross-sectional area of the EGR passage 42 in response to a control signal. The EGR passage 42 has an EGR cooler for reducing a temperature of the exhaust gas by performing heat exchange with engine cooling water 10 ,

The engine system has an electronic control unit 50 for controlling the engine 10 on. The electronic control unit 50 is called ECU 50 designated. The ECU 50 is mainly configured from a microcomputer with a CPU, a ROM and a RAM. The ECU 50 Executes a stored program in the ROM and performs multiple controls for the engine 10 depending on an operating state of the engine 10 by. The ECU 50 inputs detected signals from the sensors described above. Then the ECU calculates 50 an optimum amount of control for multiple components of the engine system based on the operating state of the engine 10 which is indicated by the detected signals and the predetermined control criteria. Then the ECU controls 50 the components. For example, the ECU calculates 50 an amount of fuel injection, an opening degree of the throttle valve, an amount EGR, and a control amount of a fuel pressure. Then the ECU controls 50 the fuel injection valve 15 , the throttle valve 26 , the EGR control valve 44 and a fuel supply pump.

With reference to 3 A control system for the boost pressure will be explained by the ECU 50 is realized. The ECU 50 calculates a target boost pressure P1E_trg based on the operating state of the engine 10 , Then calculated in a target value control block B30 the ECU 50 a basic operation amount VN_base for the VTM 53 based on the target boost pressure P1E_trg and the other operating state of the engine 10 , such as a lot of intake air and a temperature of the intake air. The basic operation amount VN_base may be referred to as the basic opening degree of variable vanes. In the return rule block B20 calculates the ECU 50 one Feedback operation amount P1E_fb based on a difference ΔP1E (Delta-P1E) between the target boost pressure P1E_trg and the actual boost pressure P1E by the inlet pressure sensor 23 is detected. Next, a target operation amount VN_trg for the VTM 53 based on a sum of the base operation amount VN_base and the return operation amount P1E_fb calculated. The target amount of operation VN_trg is calculated to set an actual boost pressure to the target boost pressure. In this embodiment, the feedback control block uses B20 the PID feedback procedure. Alternatively, the feedback control block B20 use another feedback method such as PD, PI and the feed forward regulator.

With reference to 4 a target value model is explained which is in the target value control block B30 is installed.

First, the ECU calculates 50 the target boost pressure P1E_trg , The target boost pressure P1E_trg may be based on the operating condition of the engine 10 and calculated based on a target engine torque requested by a driver. In the case that the target boost pressure P1E_trg is calculated on the basis of the target torque, the target boost pressure P1E_trg may be calculated based on an engine speed and a target fuel injection amount that may be calculated based on the desired torque. The target torque may be calculated based on the operation amount of the accelerator pedal detected by the accelerator pedal sensor 28 is detected.

Next is a target gas quantity Geng trg that enters the engine 1 is to introduce in the control block B31 calculated. The target gas amount Geng_trg is based on a density of the intake air and a volumetric efficiency of the engine 10 calculated.

In the control block B31 calculates the ECU 50 the density p (rho) of the intake air based on the target intake air temperature Teng_trg , The density ρ can be calculated by the expression (1) given below. The target intake air temperature Teng trg may be calculated as the temperature of intake air necessary to achieve a desired target boost pressure.

The target intake air temperature Teng_trg can be calculated by evaluating a map using the target boost pressure as the index parameter. Alternatively, an actual temperature may be determined by the intake air temperature sensor 52 is detected, as a target intake air temperature Teng_trg be set. In the case that the engine system is the intercooler 37 It is preferable to estimate a temperature of the intake air passing through the intercooler 37 is cooled, and the estimated temperature as a target intake air temperature Teng_trg adjust. $$p=\mathrm{1,293}\cdot \frac{273}{273+TenG\_trG}\cdot \frac{P1e\_trG}{101.325}$$

Next, the ECU calculates 50 a volumetric efficiency ηvol (eta-vol) based on the operating state of the engine 10 , For example, the volumetric efficiency ηvol may be obtained by evaluating a map expressed by the following functional expression (2) based on the engine speed Ne and a fuel injection amount Q is defined. In this embodiment, the volumetric efficiencies ηvol are predetermined based on measured values obtained by experimental operations on the engine 10 be achieved. $$\eta vOl=f\left(Ne.Q\right)$$

Then the target gas quantity Geng_trg in the engine 10 is to be introduced based on a desired operating state of the engine 10 calculated. For example, the target gas quantity Geng_trg obtained by the following expression (3), wherein the engine 10 is a four-stroke engine with reciprocating and a volume of a cylinder is Vh. $$GenG\_trG=\eta vOl\cdot p\cdot \frac{2\cdot VH\cdot Ne}{60}$$

Then it will be in a control block B32 a desired air volume GA_TRG to be charged by the compressor, calculated by the expression (4). The desired air volume GA_TRG is based on the target gas amount Geng_trg and the EGR gas amount Gegr calculated. $$Ga\_trG=GenG\_trG-GeGr$$

In a control block B33 becomes a nominal compressor capacity WC_trg based on a thermodynamic model of the turbocharger 30 and the desired air quantity GA_TRG calculated. Then in the control block B33 a target turbine power WT_trg based on the target airflow GA_TRG and a mechanical efficiency ηm (eta-m). Then, the target turbine inlet pressure becomes P1T_trg based on the target turbine power WT_trg calculated.

With reference to 5 FIG. 10 is a flowchart and a method of calculating the target turbine inlet pressure P1T_trg explained in the control block B33 be executed.

In step S101 becomes a theoretical target compressor capacity wC_trg calculated by an expression (5). In this embodiment, the theoretical target compressor power wC_trg based on the target boost pressure P1E_trg and the target air amount GA_TRG calculated assuming that the compression process in the compressor is an isentropic process. In the expression (5), Cpa indicates the specific heat at a constant pressure of the intake air, κa (Kappa-a) indicates the specific heat ratio T1C the intake air temperature passing through the intake air temperature sensor 52 is detected, and Pa indicates the atmospheric pressure passing through the atmospheric pressure sensor 29 is detected. The specific heat cpa at a constant pressure and the specific heat ratio κa can be obtained as predetermined values. $$wC\_trG=Cpa\cdot T1C\left\{{\left(\frac{P1e\_trG}{Pa}\right)}^{\frac{Ka-1}{Ka}}-1\right\}\cdot Ga\_trG$$

In step S102 becomes a compressor efficiency η C (eta-C) based on the theoretical target compressor power wC_trg calculated. The compressor efficiency η C may be determined by evaluating a compressor efficiency map based on the theoretical target compressor power wC_trg be calculated. The map gets a noticeable small value for the compressor efficiency ηC, when the theoretical target compressor capacity wC_trg is in a certain lower range, as in 6 is shown.

In step S103 becomes a nominal compressor capacity WC_trg calculated. The nominal compressor capacity WC_trg is based on the theoretical target compressor power wC_trg and the compressor efficiency η C expressed by an expression (6). $$WC\_trG=\frac{wC\_trG}{\eta C}$$

In step S104 becomes the mechanical efficiency ηm on the basis of the target compressor capacity WC_trg calculated. For example, the mechanical efficiency ηm may be obtained by evaluating a mechanical efficiency map based on the target compressor power WC_trg be calculated. The characteristic map receives a recognizable small value for the mechanical efficiency ηm, if the nominal compressor output WC_trg is in a certain lower range, as in 7 is shown.

In step S105 becomes a target turbine power WT_trg based on the target compressor power WC_trg and the mechanical efficiency ηm using an expression ( 7 ). $$WT\_trG=\frac{WC\_trG}{\eta m}$$

In step S106 becomes a turbine efficiency ηT (eta-T) based on the target turbine power WT_trg calculated. For example, the turbine efficiency ηT may be determined by evaluating a turbine efficiency map, as in FIG 8th is shown based on the target turbine power WT_trg be calculated. The map gets a recognizable large value for the turbine efficiency ηT when the target turbine power WT_trg is in a certain lower range, as in 8th is shown.

In step S107 becomes a target turbine inlet pressure P1T trg calculated. The target turbine inlet pressure P1T_trg indicates a required pressure at the inlet of the turbine to the desired turbine power WT_trg using the exhaust gas in the present state of the engine 10 to achieve. The target turbine power WT_trg can be calculated by an expression (8). In the expression (8), Cpex indicates a predetermined value of the specific heat at a constant pressure of the exhaust gas, κex (kappa-ex) indicates the specific heat ratio T1T An inlet temperature of the exhaust gas at the inlet of the turbine, Gex indicates a lot of exhaust gas flowing through the turbine, and gives P2T an estimated pressure to the outlet of the turbine. The inlet temperature T1T may be an estimated value based on the operating state of the engine 10 is estimated, or may be a detected value, which is detected by an exhaust gas temperature sensor. In this embodiment, the outlet pressure becomes P2T obtained by a detected pressure by the atmospheric pressure sensor 29 is detected. Alternatively, the outlet pressure P2T be obtained by an outlet pressure which is detected directly by a pressure sensor which is arranged at the outlet of the turbine. $$WT\_trG=\eta T\cdot Cpex\cdot T1T\left\{1-{\left(\frac{P2T}{P1T\_trG}\right)}^{\frac{Kex-1}{Kex}}\right\}\cdot Gex$$

Expression (8) may be converted to expression (9) to the target turbine inlet pressure P1T_trg specify. $$P1T\_trG=P2T\text{/}{\left(1-\frac{WT\_trG}{\eta T\cdot Cpex\cdot T1T\cdot Gex}\right)}^{\frac{Kex}{Kex-1}}$$

As shown in expression (9), the target turbine inlet pressure P1T_trg based on the target turbine power WT_trg and the turbine efficiency ηT. In this embodiment, the turbine efficiency map becomes by a self-correction process during actual operation of the engine 10 corrected. As a result, the optimum value for the target turbine inlet pressure P1T_trg be calculated.

In this embodiment, the target turbine inlet pressure P1T_trg using the expression ( 9 ), which shows a relationship that the target turbine power WT_trg and the target turbine inlet pressure P1T_trg connected. Alternatively, it is possible to set the target turbine inlet pressure P1T_trg using an expression ( 10 ) and a converted form of expression ( 11 ) to obtain. First, the theoretical target turbine power wT_trg calculated by the expression (10). Then, the target turbine inlet pressure becomes P1T_trg by the transformed form of the expression ( 11 ).

For example, in step S107 the theoretical target turbine power wT_trg by the expression (10) based on the target turbine power WT_trg calculated. The turbine efficiency ηT is in the step S106 receive. $$wT\_trG=\frac{WT\_trG}{\eta T}$$

The relationship between the theoretical target turbine power wT_trg and the target turbine inlet pressure P1T_trg can be expressed by the expression (11). $$wT\_trG=Cpex\cdot T1T\left\{1-{\left(\frac{P2T}{P1T\_trG}\right)}^{\frac{Kex-1}{Kex}}\right\}\cdot Gex$$

The target turbine inlet pressure P1T_trg can be obtained by an expression (12) representing a converted form of the expression (12). 11 ). $$P1T\_trG=P2T/{\left(1-\frac{wT\_trG}{Cpex\cdot T1T\cdot Gex}\right)}^{\frac{Kex}{Kex-1}}$$

As described above, alternatively, the target turbine inlet pressure P1T_trg based on the theoretical target turbine power wT_trg be calculated.

As described above, in the control block B33 the target turbine inlet pressure P1T_trg based on the target boost pressure P1E_trg and the target air amount GA_TRG calculated.

Referring again to 4 is in a control block B35 the basic operation amount VN_base to achieve the target turbine inlet pressure P1T_trg calculated. To calculate the base operation amount VN_base uses the ECU 50 predetermined or known turbine characteristics. For example, the in 9 used turbine characteristics. In 9 Each characteristic curve shows a relationship between a solvent expansion ratio nT_trg (pi-T_trg) and a flow rate Gex * of the exhaust gas, wherein the operation amount is kept constant. The solvent expansion ratio nT_trg gives a relationship between the target turbine inlet pressure P1T_trg and the outlet pressure P2T on. The flow rate Gex * indicates a corrected or converted value of the flow rate at a reference temperature and a reference pressure.

With reference to 10 FIG. 10 is a flowchart and a method of calculating the basic operation amount VN_base explained in the control block B35 be executed.

In step S301 a flow rate Gex * is expressed by an expression (13) based on the turbine inlet pressure P1T passing through the turbine inlet pressure sensor 54 is detected, the turbine inlet temperature T1T and the exhaust gas amount Gex calculated. The inlet temperature T1T may be an estimated value based on the operating state of the engine 10 is estimated, or may be a detected value, which is detected by an exhaust gas temperature sensor. In this embodiment, it is assumed that the reference temperature is 288 K and the reference pressure is 101,325 kPa. $$Gex*=\frac{101325}{P1T}\cdot \sqrt{\frac{T1T}{288}}\cdot Gex$$

In step S302 becomes the solo expansion ratio πT_trg by an expression (14) based on the target turbine inlet pressure P1T_trg and the outlet pressure P2T calculated. The outlet pressure P2T can be obtained by an outlet pressure directly detected by a pressure sensor disposed at the outlet of the turbine. Alternatively, the outlet pressure P2T by an estimate based on the exhaust gas amount Gex. Furthermore, the outlet pressure P2T be obtained by a detected atmospheric pressure by the atmospheric pressure sensor 29 is detected. $$\pi T\_trG=\frac{P1T\_trG}{P2T}$$

In step S303 becomes the basic operation amount VN_base by the turbine characteristics based on the flow rate Gex * and the solvent expansion ratio nT_trg calculated. In the 9 Turbine characteristics shown in the ECU 50 saved.

It is possible to have a most accurate control using the basic operation amount VN_base as the target value in the control block in 3 perform.

In the embodiment, in a control block B34 the turbine efficiency ηT stored in the ECU 50 is stored, calculated according to an actual value, which is based on an actual operating state of the engine 10 based.

The following is a configuration of the ECU 50 for correcting at least one parameter during operation of the engine 10 explained. The ECU 50 provides a means for correcting at least one parameter that links the boost pressure and the intake pressure. The means may be referred to as a self-correction device or learning device. The parameter is at least one of the parameters consisting of the turbine efficiency ηT, the mechanical efficiency ηm, the compressor efficiency ηC and an overall efficiency, such as a turbocharger efficiency ηcmT (eta-cmT). The device calculates the parameter based on an actual operating state of the engine 10 , such as compressor power and turbine power. In this embodiment, the turbine efficiency ηT becomes based on a detected operating state of the engine 10 calculated.

A relationship between a compressor power and a turbine power is expressed by Expression (15). In the expression (15), losses such as a friction loss at each of the turbine, the compression and the shaft, the turbine efficiency ηT, the compressor efficiency η C and the mechanical efficiency qm are indicated, respectively. A theoretical actual compressor power wC is based on an actual boost pressure P1E assuming that the compression process of the compressor is an isentropic process. A theoretical actual turbine power wT is based on an actual turbine inlet pressure P1T assuming that the expansion process in the turbine is an isentropic process. $$\frac{wC}{wT}=\eta C\cdot \eta m\cdot \eta T$$

According to the expression (15), the ratio between the theoretical actual compressor power acts WC and the theoretical actual turbine power wT at the same time on three parameters. In this embodiment, the remaining parameters are recorded to calculate a parameter, such as the turbine efficiency ηT.

With reference to 11 A flowchart for calculating the turbine efficiency ηT will be explained.

In step S201 becomes the theoretical actual compressor power WC calculated by an expression (16). In the expression (16), Cpa indicates the specific heat at a constant pressure of the intake air, κa indicates the specific heat ratio T1C the intake air temperature passing through the intake air temperature sensor 52 is detected, and Pa indicates the atmospheric pressure passing through the atmospheric pressure sensor 29 is detected. In addition there P1E the actual boost pressure applied by the inlet pressure sensor 23 is detected, and Ga indicates an actual amount of intake air flow passing through the air flow meter 51 is detected. $$wC=Cpa\cdot T1C\left\{{\left(\frac{P1e}{Pa}\right)}^{\frac{Ka-1}{Ka}}-1\right\}\cdot Ga$$

In step S202 the theoretical actual turbine power wT is calculated by an expression (17). In the expression (17), Cpex indicates a predetermined value of the specific heat at a constant pressure of the exhaust gas, κex indicates the specific heat ratio T1T the inlet temperature of the exhaust gas at the inlet of the turbine on P1T the turbine inlet pressure passing through the turbine inlet pressure sensor 54 is detected, Gex indicates a lot of exhaust gas flowing through the turbine and gives P2T an estimated pressure at the outlet of the turbine. The inlet temperature T1T may be an estimated value based on the operating state of the engine 10 is estimated, or may be a sensed value, which is determined by a Exhaust gas temperature sensor is detected. The value Gex may be based on the intake air amount ga and the fuel injection amount are calculated. The outlet pressure P2T is an estimated value estimated based on the amount of the exhaust gas Gex. The outlet pressure P2T can be obtained by a detected atmospheric pressure passing through the atmospheric pressure sensor 29 is detected. $$wT=Cpex\cdot T1T\left\{1-{\left(\frac{P2T}{P1T}\right)}^{\frac{Kex-1}{Kex}}\right\}\cdot Gex$$

In step S203 is the compressor efficiency ηC based on the theoretical actual compressor power WC calculated. For example, the compressor efficiency η C is calculated using the compressor efficiency map shown in FIG 6 is shown.

In step S204 becomes the actual compressor capacity WC based on the theoretical actual compressor power WC and the compressor efficiency η C using an expression ( 18 ). $$WC=\frac{wC}{\eta C}$$

In step S205 is the mechanical efficiency ηm based on the actual compressor power WC calculated using a mechanical efficiency map as in 7 is shown.

In step S206 is an actual turbine efficiency ηT_act (eta-T_act) using an expression ( 19 ). $$\eta T\_act=\frac{wC}{\eta m\cdot \eta C\cdot wT}$$

In step S207 For example, a correction point, in particular, a stored value of the turbine efficiency to be corrected by the self-correction process, is determined.

The turbine efficiency map showing a relationship between the target turbine power and the turbine efficiency or the actual turbine power and the turbine efficiency is shown in FIG 8th shown. This in 8th The map shown is in the ECU 50 stored in the form of a data matrix, as in 13 is shown. This in 13 shown map is at the step S106 evaluated in the ordinary control process. That in the 8th and 13 The map shown can be referred to as a primary turbine efficiency map. An auxiliary turbine efficiency map showing a relationship between the theoretical target turbine power and the turbine efficiency or the theoretical actual turbine power and the turbine efficiency is shown in FIG 12 shown. This in 12 The map shown is in the ECU 50 stored in the form of a data matrix, as in 14 is shown. This in 14 The map shown is evaluated in the self-correction process. The auxiliary turbine efficiency map is used as a conversion block that converts the turbine efficiency, which is calculated based on the detected values, to the turbine efficiency that is prepared for the ordinary control process.

An imaginary turbine efficiency ηT '(eta-T-prime) is calculated using the method described in U.S. Pat 12 and 14 shown map based on the theoretical actual turbine power wT, which in the step S202 is calculated.

Then, an imaginary actual turbine power WT '(WT-prime) is calculated by an expression (20) based on the imaginary turbine efficiency ηT'. $$WT\text{'}=\eta T\text{'}\cdot wT$$

Then the ECU determines 50 the actual turbine power WTi, which is used as an index in the in 13 shown map, based on the imaginary actual turbine power WT '. The actual turbine power WTi fulfills an expression ( 21 ). Therefore, the actual turbine power WTi corresponds to the imaginary actual turbine power WT ' , In the expressions and the drawings, the suffixes i, i-1, and i + 1 are indexes for referring to the i-th element, the i-1th element, and the i + 1-th element in the map. $$\frac{WTi+WTi-1}{2}<WT\text{'<}\frac{WTi+WTi+1}{2}$$

Then the ECU refers 50 the turbine efficiency ηTi according to the actual turbine power WTi by evaluating the in 13 shown map.

In step S208 corrects the ECU 50 a stored value of the turbine efficiency ηTi in the maps. First, the ECU corrects 50 this in 13 shown map. The ECU 50 calculates a corrected value of the turbine efficiency ηTi by an expression (22) based on the turbine efficiency ηTi determined in step S207 and the actual turbine efficiency ηT_act obtained in step 206 is calculated. Then the ECU saves 50 the corrected value by the Expression (22) is calculated as the turbine efficiency ηTi in the map. A1s As a result, the turbine efficiency ηTi is renewed and updated to a value representing an actual operating state of the turbocharger 30 reproduces. In the expression (22), K is a correction gain and is set to a predetermined value. $$\eta Ti=\eta Ti+K\left(\eta T\_act-\eta Ti\right)$$

Then the ECU corrects 50 this in 14 shown map. The ECU 50 determines the theoretical actual turbine power wTi by an expression (23) based on the turbine efficiency ηTi, which is shown in the map in FIG 13 is stored, and the actual turbine power WTi. The theoretical actual turbine power wTi indicates that an index of the turbine efficiency ηTi should be replaced. Then replace the ECU 50 the stored value of the turbine efficiency ηTi by a value of the turbine efficiency ηTi calculated by the expression (22). $$wTi=\frac{WTi}{\eta Ti}$$

As explained above, in the embodiment, the parameter such as the turbine efficiency ηT, which is for the ordinary control process of the VTM 53 is corrected in a self-correction based on an actual operating state of the engine system.

In the embodiment, in the control block B34 the turbine efficiency ηT stored in the ECU 50 is corrected based on the turbine efficiency ηT calculated based on the actual operating state of the turbocharger. As a result, it is possible to perform the ordinary control process in an appropriate manner. In the embodiment, it is possible to obtain a correct amount for the turbine inlet pressure in the control block B33 to calculate. Therefore, it is possible to improve the control characteristics. In other words, it is possible to obtain accuracy of the target value model by updating the parameter according to the actual operating state of the engine 10 to improve. As a result, it is possible to improve the response of a target value change.

Second embodiment

A second embodiment of the invention will be described below together with the drawings. The second embodiment uses the same engine system explained in the first embodiment except for the self-correction process. In the second embodiment, the mechanical efficiency ηm is corrected by the self-correction process. The mechanical efficiency ηm is in the control block B33 used. The mechanical efficiency ηm is corrected on the basis of the compressor power and the turbine power, both from the actual operating state of the turbocharger 30 be calculated.

The self-correction process for the mechanical efficiency ηm is performed in place of the self-correction process in the previous embodiment. However, it is possible to install and perform the self-correction process in this embodiment in the foregoing embodiment.

A relationship between a compressor power and a turbine power is expressed by Expression (24). In the expression (24), losses such as friction loss at each of the turbine, the compressor and the shaft are indicated by the turbine efficiency ηT, the compressor efficiency ηC and mechanical efficiency ηm, respectively. A theoretical actual compressor power wC is based on an actual boost pressure P1E calculated assuming that the compression process in the compressor is an isentropic process. A theoretical actual turbine power wT is based on an actual turbine inlet pressure P1T assuming that the expansion process in the turbine is an isentropic process. $$\frac{wC}{wT}=\eta C\cdot \eta m\cdot \eta T$$

According to the expression (24), the ratio between the theoretical actual compressor power acts WC and the theoretical actual turbine power wT at the same time on three parameters. In this embodiment, the remaining parameters are recorded to calculate a parameter, such as the mechanical efficiency ηm.

With reference to 15 A flowchart for calculating the mechanical efficiency ηm will be explained.

In step S211 the theoretical actual compressor power wC is calculated by expression (25). In the expression (25), Cpa indicates the specific heat at a constant pressure of the intake air, κa indicates the specific heat ratio T1C the intake air temperature passing through the intake air temperature sensor 52 is detected, and Pa indicates the atmospheric pressure passing through the atmospheric pressure sensor 29 is detected. In addition there P1E the actual boost pressure applied by the inlet pressure sensor 23 is captured, and gives Ga a Actual amount of intake air flow passing through the air flow meter 51 is detected. $$wC=Cpa\cdot T1C\left\{{\left(\frac{P1e}{Pa}\right)}^{\frac{Ka-1}{Ka}}-1\right\}\cdot Ga$$

In step S212 the theoretical actual turbine power wT is calculated by an expression (26). In the expression (26), Cpex indicates a predetermined value of the specific heat at a constant pressure of the exhaust gas, κex indicates the specific heat ratio T1T the inlet temperature of the exhaust gas at the inlet of the turbine on P1T the turbine inlet pressure passing through the turbine inlet pressure sensor 54 is detected, Gex indicates a lot of exhaust gas flowing through the turbine and gives P2T an estimated pressure at the outlet of the turbine. The inlet temperature T1T may be an estimated value based on the operating state of the engine 10 is estimated, or may be a detected value, which is detected by an exhaust gas temperature sensor. The value Gex may be calculated based on the intake air amount Ga and the fuel injection amount. The outlet temperature P2T is an estimated value estimated based on the amount of the exhaust gas Gex. The outlet pressure P2T can be obtained by a detected atmospheric pressure passing through the atmospheric pressure sensor 29 is detected. $$wT=Cpex\cdot T1T\left\{1-{\left(\frac{P2T}{P1T}\right)}^{\frac{Kex-1}{Kex}}\right\}\cdot Gex$$

In step S213 is the compressor efficiency ηC based on the theoretical actual compressor power WC calculated. For example, the compressor efficiency η C is calculated using the compressor efficiency map, as in FIG 6 is shown.

In step S214 becomes the actual compressor capacity WC based on the theoretical actual compressor power WC and the compressor efficiency η C using an expression ( 27 ). $$WC=\frac{wC}{\eta C}$$

In step S215 is the turbine efficiency ηT based on the theoretical actual turbine power wT calculated using the turbine efficiency map as in 12 is shown.

In step S216 is a mechanical actual efficiency ηm_act (eta-m_act) using an expression ( 28 ). $$\eta m\_act=\frac{WC}{\eta T\cdot wT}$$

In step S217 For example, a correction point, in particular a stored value of the mechanical efficiency to be corrected by the self-correction process, is determined.

The map of mechanical efficiency, as in 7 is shown in the ECU 50 stored in the form of a data matrix, as in 16 is shown. Then the ECU determines 50 the actual compressor power WCi, which is used as index on the in 16 map is used, based on the actual compressor power WC using an expression ( 29 ). $$\frac{WCi+WCi-1}{2}<WC<\frac{WCi+WCi+1}{2}$$

Then the ECU refers 50 the mechanical efficiency ηmi according to the actual compressor power WCi by evaluating the in 16 shown map.

In step S218 corrects the ECU 50 a stored value of the mechanical efficiency ηmi in the map, which in 16 is shown. The ECU 50 calculates a corrected value of the mechanical efficiency ηmi by an expression (30) on the basis of the mechanical efficiency nmi obtained in step S217 and the mechanical actual efficiency ηm_act obtained in step S216 is calculated. In the expression (30), K is a correction gain and is set to a predetermined value. $$\eta mi=\eta mi+K\left(\eta m\_act-\eta mi\right)$$

Then the ECU saves 50 the corrected value calculated by the expression (30) as the mechanical efficiency ηmi in the map.

In the embodiment, in the control block B34 the mechanical efficiency ηm in the ECU 50 is corrected based on the mechanical efficiency ηT calculated based on the actual operating state of the turbocharger. As a result, it is possible to carry out the ordinary process in an appropriate way. In the embodiment, it is possible to have a correct amount for the turbine inlet pressure in the control block B33 to calculate. Therefore, it is possible to improve the control characteristics. In other words, it is possible to achieve accuracy of the target value model by updating the parameter according to the actual operating state of the engine 10 to improve. As a result, it is possible to improve the response of a target value change.

Third embodiment

A third embodiment of the invention will be described below together with the drawings. The third embodiment uses the same engine system explained in the first embodiment except the self-correction process. In the third embodiment, the compressor efficiency η C is corrected by the self-correction process. The compressor efficiency ηC is in the control block B33 used. In the control block B34 For example, the compressor efficiency η C is corrected on the basis of a comparison between the compressor power and the turbine power, both from the actual operating state of the engine 10 be calculated.

The self-correction process for the compressor efficiency η C is performed instead of the self-correction process in the foregoing embodiment. However, it is possible to install and execute the self-correction process in this embodiment in the foregoing embodiment.

A relationship between a compressor power and a turbine power is expressed by an expression (31). In expression (24), losses such as friction loss at each of the turbine, the compressor and the shaft are indicated by the turbine efficiency ηT, the compressor efficiency ηC and the mechanical efficiency ηm, respectively. A theoretical actual compressor power wC is based on an actual boost pressure P1E calculated assuming that the compression process in the compressor is an isentropic process. A theoretical actual turbine power wT is based on an actual turbine inlet pressure P1T assuming that the expansion process in the turbine is an isentropic process. $$\frac{wC}{wT}=\eta C\cdot \eta m\cdot \eta T$$

According to the expression (31), the ratio of the theoretical actual compressor power wC and the theoretical actual turbine power wT simultaneously influences three parameters. In this embodiment, the remaining parameters are recorded to calculate a parameter, e.g. the compressor efficiency ηC.

With reference to 17 A flowchart for calculating the compressor efficiency η C will be explained.

In step S221 the theoretical actual compressor power wC is calculated by an expression (32). In the expression (32), Cpa indicates the specific heat at a constant pressure of the intake air, κa indicates the specific heat ratio T1C the intake air temperature passing through the intake air temperature sensor 52 is detected, and Pa indicates the atmospheric pressure passing through the atmospheric pressure sensor 29 is detected. In addition there P1E the actual boost pressure applied by the inlet pressure sensor 23 is detected, and Ga indicates the actual amount of intake air flow passing through the air flow meter 51 is detected. $$wC=Cpa\cdot T1C\left\{{\left(\frac{P1e}{Pa}\right)}^{\frac{Ka-1}{Ka}}-1\right\}\cdot Ga$$

In step S222 the theoretical actual turbine power wT is calculated by an expression (33). In the expression (33), Cpex indicates a predetermined value of the specific heat at a constant pressure of the exhaust gas, κex indicates the specific heat ratio T1T the inlet temperature of the exhaust gas at the inlet of the turbine on P1T the turbine inlet pressure passing through the turbine inlet pressure sensor 54 is detected, Gex indicates an amount of exhaust gas flowing through the turbine and gives P2T an estimated pressure at the outlet of the turbine. The inlet temperature T1T may be an estimated value based on the operating state of the engine 10 can be estimated or can be a sensed value detected by an exhaust gas temperature sensor. The value Gex may be calculated based on the intake air amount Ga and the fuel injection amount. The outlet pressure P2T is an estimated value estimated based on the amount of the exhaust gas Gex. The outlet pressure P2T can be obtained by a detected atmospheric pressure passing through the atmospheric pressure sensor 29 is detected. $$wT=Cpex\cdot T1T\left\{1-{\left(\frac{P2T}{P1T}\right)}^{\frac{Kex-1}{Kex}}\right\}\cdot Gex$$

In step S223 is the mechanical efficiency ηm on the basis of the actual compressor power WC using the in 7 calculated map for mechanical efficiency calculated.

In step S224 is the turbine efficiency ηT on the basis of the theoretical actual turbine power wT using the in 12 calculated turbine efficiency map calculated.

In step S225 For example, an actual compressor efficiency ηC_act (eta-C-act) is calculated by expression (34). $$\eta C\_act=\frac{wC}{\eta m\cdot \eta T\cdot wT}$$

In step S226 For example, a correction point, particularly a stored value of the compressor efficiency to be corrected by the self-correction process, is determined.

The compressor efficiency map used in 6 is shown in the ECU 50 stored in the form of a data matrix, as in 18 is shown. Then the ECU determines 50 the theoretical compressor power wCi, which is used as index in the in 18 map based on the theoretical actual compressor power wC using an expression ( 35 ). $$\frac{wCi+wCi-1}{2}<wC<\frac{wCi+wCi+1}{2}$$

Then the ECU refers 50 the compressor efficiency ηCi according to the theoretical compressor power wCi by evaluating the in 18 shown map.

In step S227 corrects the ECU 50 a stored value of the compressor efficiency ηCi in the in 18 shown map. The ECU 50 calculates a corrected value of the compressor efficiency ηCi by a term (36) based on the compressor efficiency ηCi determined in step S227 and the actual compressor efficiency η C_act obtained in step S225 is calculated. In the expression (36), K is a correction gain and is set to a predetermined value. $$\eta Ci=\eta Ci+K\left(\eta C\_act-\eta Ci\right)$$

Then the ECU saves 50 the corrected value calculated by the expression (36) as the compressor efficiency ηCi in the map.

In the embodiment, in the control block B34 the compressor efficiency ηC stored in the ECU 50 is corrected based on the compressor efficiency η C calculated based on the actual operating state of the turbocharger. As a result, it is possible to perform the ordinary process in an appropriate manner. In the embodiment, it is possible to obtain a correct amount for the turbine inlet pressure in the control block B33 to calculate. Therefore, it is possible to improve the control characteristics. In other words, it is possible to achieve accuracy of the target value model by updating the parameter according to the actual operating state of the engine 10 to improve. As a result, it is possible to improve the response to a target value change.

Fourth embodiment

A fourth embodiment of the invention will be described below together with the drawings. The fourth embodiment uses the same engine system explained in the first embodiment except the self-correction process. In the fourth embodiment, the turbocharger efficiency ηcmT becomes to calculate the target turbine inlet pressure P1T_trg used. The target turbine inlet pressure P1T_trg is based on the target boost pressure P1E_trg , the intake intake air amount GA_TRG and turbocharger efficiency ηcmT. The turbocharger efficiency ηcmT gives the overall efficiency of the turbocharger 30 including compressor efficiency, turbine efficiency and mechanical efficiency. The turbocharger efficiency ηcmT is in the control block B33 used.

For example, in the embodiment, a theoretical target compressor power wC-trg based on the target boost pressure P1E -trg and the desired intake air quantity GA_TRG calculated. Then, the turbocharger efficiency ηcmT becomes based on the theoretical target compressor output wC_trg , calculated using, for example, a map. Then the theoretical target turbine power wT_trg by an expression (37) based on the theoretical target compressor power wC_trg and turbocharger efficiency ηcmT. Finally, the target boost pressure P1E_trg calculated. $$wT\_trG=\eta cmT\cdot wC\_trG$$

Turbocharger efficiency ηcmT stored in ECU 50 is stored as a map, is corrected by the self-correction process. The self-correction process for the turbocharger efficiency ηcmT is used instead of the self-correction process in the previous embodiment performed. However, it is possible to install and execute the self-correction process in this embodiment in the foregoing embodiment.

In the self-correction process, an actual turbocharger efficiency ηcmT_act is calculated by an expression (38) based on the theoretical actual compressor power wC and the theoretical actual turbine power wT, both of which can be calculated, as explained in the preceding embodiments. $$\eta cmT\_act=\frac{wC}{wT}$$

Then the ECU determines 50 a stored value of the turbocharger efficiency ηcmT to be corrected by the self-correction process. The determination is made on the basis of the theoretical actual compressor power wC. The ECU 50 corrects the stored value of the turbocharger efficiency ηcmT based on the actual turbocharger efficiency ηcmT_act.

As explained above, the turbocharger efficiency, which is used to calculate the amount of operation for the VTM 53 is used based on the actual operating state of the engine 10 including the turbocharger 30 updated. Therefore, it is possible to achieve a desired supercharging pressure while eliminating influences of troublesome components such as a difference between respective products of the turbocharger and aging of the product.

As explained above, the efficiency defined as the parameter links the boost pressure and the turbine inlet pressure. In other words, the parameter allows the ECU 50 between the boost pressure and the turbine inlet pressure makes a conversion. Therefore, the ECU 50 calculate the target turbine inlet pressure based on the target boost pressure. Furthermore, the ECU 50 provided with the turbocharger model, which links the operating amount and the turbine inlet pressure. In other words, the turbocharger model allows the ECU 50 makes a conversion between the amount of operation and the turbine inlet pressure.

In one embodiment, the parameter combines compressor power and turbine power. In the other embodiment, the parameter is the compressor efficiency η C, which links the actual compressor power WC and the theoretical actual compressor power wC. In the further exemplary embodiment, the parameter is the mechanical efficiency ηm, which combines the theoretical actual compressor power wT and the theoretical actual compressor power wC. In the further exemplary embodiment, the parameter is the turbine efficiency ηT, which combines the theoretical actual turbine power wT and the actual turbine power WT.

Other embodiments

In the embodiments described above, the theoretical compressor power is calculated based on the boost pressure provided by the intake pressure sensor 23 is detected. Alternatively, in the case where the throttle valve is installed downstream of the turbocharger, it is possible to increase the theoretical compressor performance by correcting the boost pressure provided by the intake pressure sensor 23 is detected to accurately calculate based on an opening degree of the throttle valve. For example, the boost pressure caused by the intake pressure sensor 23 is corrected based on a pressure drop between the upstream side and the downstream side of the throttle valve. The pressure drop is obtained by a map in which pre-measured values of the pressure drop are plotted depending on the opening degree of the throttle valve and the intake flow velocity. The intake air flow rate may be changed with the intake air amount.

Although in the embodiments described above, the engine systems have the throttle valve downstream of the turbocharger, the invention may be applied to an engine system in which the throttle valve is installed upstream of the turbocharger, in particular the compressor.

Although in the above-described embodiments, the engine is the diesel engine, the present invention may be applied to a gasoline engine or a spark-ignition engine.

Although the present invention has been fully described in connection with the preferred embodiments thereof with reference to the accompanying drawings, it is to be noted that various changes and modifications will be apparent to those skilled in the art. Such changes and modifications are intended to be within the scope of the present invention as defined by the appended claims.

The engine system has a turbocharger 30 with a variable turbine mechanism 53 by an ECU 50 is controlled to achieve a desired boost pressure. The ECU 50 uses a mathematical model to calculate an optimal amount of operation for the variable turbine mechanism 53 , The mathematical model includes at least one parameter, such as an efficiency value of a compressor, a turbine, and a shaft. The ECU 50 learns an actual value of the parameter based on a present operating state of the turbocharger. Then the ECU updates 50 a stored parameter based on the learned value. Therefore, it is possible the variable turbine mechanism 53 to control exactly.

Claims (4)

Apparatus for controlling a forced-charge engine having a turbocharger (30) with a variable turbine mechanism (53), comprising: means (50, B34) for storing a value of a parameter (ηC, ηm, ηT, ηcmT) indicative of a boost pressure in an intake passage downstream of a compressor of the turbocharger (30) and a turbine inlet pressure in an exhaust passage upstream of a turbine of the turbocharger (30 ) connected; means (50, B20, B31, B32, B33, B35) for controlling the variable turbine mechanism based on an operation amount for the variable turbine mechanism, wherein the operation amount is calculated based on a turbocharger model linking the operation amount and the turbine inlet pressure, wherein calculating the turbine inlet pressure based on the value of the parameter stored in the storage device and a target boost pressure in the intake passage downstream of the compressor calculated based on an operating state of the engine; means (23) for detecting an intake air pressure as the actual boost pressure; means (54) for detecting a pressure in the exhaust passage upstream of the turbine as the actual turbine inlet pressure; means (50, B34, S208, S218, S228) for calculating an actual value of the parameter based on the actual boost pressure and the actual turbine inlet pressure; and means (50, B34, S208, S218, S228) for correcting the value of the parameter stored in the memory means on the basis of the actual value of the parameter. Apparatus for controlling a positive-filled engine according to Claim 1 wherein the calculating means calculates the actual value of the parameter (ηC, ηm, ηT, ηcmT) based on a theoretical actual compressor power (wC) calculated on the basis of the actual boost pressure and a theoretical actual turbine power (wT), calculated on the basis of the actual turbine inlet pressure, and wherein the parameter combines compressor power (WC, wC) and turbine power (WT, wT). Apparatus for controlling a positive-filled engine according to Claim 1 wherein the calculating means determines the actual value including at least one of a first, a second and a third parameter (η C, η m, η T, η cm T) based on a theoretical actual compressor power (wC) based on the actual Boosting pressure and a theoretical actual turbine power (wT) calculated on the basis of the actual turbine inlet pressure, the first parameter (ηC) being an actual compressor power (WC) and the theoretical actual compressor power (wC) wherein the second parameter (ηm) is linked to a theoretical actual turbine power (wT) and the theoretical actual compressor power (wC), and wherein the third parameter (ηT) is a theoretical actual turbine power (wT) and an actual turbine power ( WT) linked. Apparatus for controlling a positive-filled engine according to Claim 3 wherein the calculating means sets two of the parameters and calculates the actual value of the remaining one of the parameters (ηC, ηm, ηT, ηcmT) based on the theoretical actual compressor power (wC) and the theoretical actual turbine power (wT).

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