JP2014152689A - Control device for internal combustion engine with turbosupercharger - Google Patents

Abstract

A control device capable of suppressing deterioration of exhaust emission during transient operation in an internal combustion engine with a turbocharger.
An actual gas temperature Tb in an intake manifold of an engine is calculated from a signal from a temperature sensor 60. The actual boost pressure pim of the engine is calculated from the signal of the boost pressure sensor 54. Based on the actual gas temperature Tb and the actual boost pressure pim, the actual cylinder intake air amount Gcyl of the engine is calculated. The actual in-cylinder supply heat amount H is calculated based on the actual in-cylinder intake air amount Gcyl and the actual gas temperature Tb. Based on the engine speed and the fuel injection amount, a steady in-cylinder supply heat amount Hst, which is a heat amount supplied into the cylinder during steady operation, is calculated. The amount of exhaust discharged from the engine to the outside of the system is controlled in accordance with the heat amount difference ΔH between the steady in-cylinder supplied heat amount Hst and the actual in-cylinder supplied heat amount H. Preferably, the target EGR rate or the target supercharging pressure is set so that the exhaust amount is suppressed as the heat amount difference ΔH is larger.
[Selection] Figure 2

Description

  The present invention relates to a control device for an internal combustion engine with a turbocharger.

  Conventionally, for example, Japanese Unexamined Patent Application Publication No. 2007-198142 discloses a technique related to EGR control of a diesel engine. According to the technique described in this publication, the control target value for the EGR opening is calculated based on the fuel injection amount and the engine speed, and the EGR opening and the actual EGR opening are made to coincide with each other. The operation of the valve is controlled. Further, in the technique of the above publication, the EGR opening is controlled to gradually increase to an opening corresponding to the engine operating state at the time of transition immediately after the operating region of the internal combustion engine changes from the EGR stop region to the EGR execution region. The More specifically, over the predetermined engine immediately after the engine operation region changes from the EGR stop region to the EGR execution region, the EGR valve is controlled so that the EGR amount decreases as the actual fresh air amount is insufficient relative to the reference fresh air amount. Operation is controlled.

JP 2007-198142 A JP 2009-281252 A

  In the publication of the above-mentioned Patent Document 1, as a technique for suppressing deterioration of exhaust properties, a method of limiting an excessive decrease in the actual fresh air amount by limiting the EGR amount at the time of transition is disclosed. However, the cause of the deterioration of exhaust properties at the time of transition is not only the decrease in the amount of fresh air. For example, a decrease in the in-cylinder supply heat amount supplied into the cylinder of the engine is one of the factors that deteriorate the exhaust properties at the time of transition. Generally, the actual value of the in-cylinder supply heat amount at the time of transition is lower than the value based on steady performance. When the in-cylinder supply heat amount decreases, the gas temperature that the spray tackles in the air-fuel mixture formation process decreases, thereby inhibiting fuel vaporization. In this case, the mixed state of the in-cylinder gas is deteriorated and the concentration of exhaust components such as HC, CO and smoke is increased, and as a result, the exhaust property is deteriorated. In the technique described in the above publication, no measures are taken against the deterioration of the concentration of the exhaust component due to the decrease in the in-cylinder supply heat amount at the time of transition. For this reason, the technique described in the above publication is insufficient as a device for suppressing deterioration of exhaust properties at the time of transition, and there is still room for improvement.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a control device that can effectively suppress deterioration of exhaust properties during a transition in an internal combustion engine with a turbocharger. To do.

In order to achieve the above object, a first invention provides a control device for an internal combustion engine with a turbocharger,
Means for calculating an actual in-cylinder intake air amount of the internal combustion engine based on a gas temperature and a supercharging pressure sucked into the internal combustion engine;
Means for calculating an actual in-cylinder supply heat amount based on the actual in-cylinder intake air amount and the gas temperature;
Means for calculating a steady in-cylinder supply heat amount, which is a heat amount supplied into the cylinder during steady operation, based on the engine speed and the fuel injection amount;
Control means for controlling an exhaust amount exhausted from the internal combustion engine in accordance with a heat amount difference between the steady in-cylinder supply heat amount and the actual in-cylinder supply heat amount;
It is characterized by having.

According to a second invention, in the first invention,
The internal combustion engine includes an EGR device that recirculates exhaust gas from an exhaust passage to an intake passage,
The control means includes
Target EGR rate calculation means for calculating a target EGR rate according to the heat difference,
Means for operating the EGR device by feedback control so that an actual EGR rate approaches the target EGR rate;
It is characterized by including.

According to a third invention, in the second invention,
The target EGR rate calculation means includes:
Means for calculating a coefficient serving as an index of the concentration of unpurified components in the exhaust gas based on the calorific value difference;
Means for calculating a target fresh air amount that is a target value of the fresh air amount based on the coefficient and an actual fresh air amount that is an actual value of the fresh air amount sucked into the internal combustion engine;
Means for calculating the target EGR rate based on the actual in-cylinder intake air amount and the target fresh air amount;
It is characterized by including.

According to a fourth invention, in the first invention,
The internal combustion engine includes an actuator for controlling a supercharging pressure,
The control means includes
A target boost pressure calculating means for calculating a target boost pressure according to the heat amount difference;
Means for operating the actuator by feedback control to bring the actual boost pressure closer to the target boost pressure;
It is characterized by including.

A fifth invention is the fourth invention,
The target boost pressure calculating means includes
Means for calculating a coefficient serving as an index of the concentration of unpurified components in the exhaust gas based on the calorific value difference;
Means for calculating a target fresh air amount that is a target value of the fresh air amount based on the coefficient and an actual fresh air amount that is an actual value of the fresh air amount sucked into the internal combustion engine;
Means for calculating a target in-cylinder intake air amount based on the target fresh air amount;
Means for calculating the target boost pressure based on the target cylinder intake air amount and the gas temperature;
It is characterized by including.

According to a sixth invention, in the fifth invention,
The internal combustion engine includes an EGR device that recirculates exhaust gas from an exhaust passage to an intake passage,
The target boost pressure calculating means includes means for calculating the target in-cylinder intake air amount based on an actual EGR rate and the target fresh air amount.

  According to the first invention, a calorific value difference between the amount of heat supplied into the cylinder during steady operation (steady in-cylinder supplied heat amount) and the actual amount of heat supplied into the cylinder (actual in-cylinder supplied heat amount) is calculated, The amount of exhaust exhausted from the internal combustion engine (engine) to the outside of the system is controlled in accordance with the heat amount difference. At the time of transient operation, the actual in-cylinder supply heat amount is lower than the steady in-cylinder supply heat amount, so the concentration of unburned components in the exhaust gas is worse than that during steady operation. According to the present invention, the exhaust amount can be controlled in accordance with the difference in heat quantity, so that the exhaust property deterioration can be effectively suppressed by appropriately performing the exhaust amount control in accordance with the deterioration of the exhaust component concentration. It becomes.

  According to the second invention, the EGR device is used as an actuator for controlling the displacement. Under a condition where the in-cylinder intake air amount is constant, the higher the EGR rate, the more the exhaust gas recirculation amount increases. As a result, the exhaust amount to the outside of the engine system becomes small. According to the present invention, the target EGR rate is calculated based on the calorific value difference, and the EGR device is operated so that the actual EGR rate approaches the target EGR rate. Therefore, the exhaust amount is appropriately set according to the deterioration of the exhaust component concentration. It becomes possible to control to.

  According to the third aspect of the invention, the coefficient serving as an index of the exhaust component concentration is calculated based on the calorie difference. Then, a target fresh air amount is calculated based on the coefficient and the actual fresh air amount, and a target EGR rate for realizing the target fresh air amount is calculated. Under the condition that the in-cylinder intake air amount is constant, the smaller the fresh air amount, the higher the EGR rate is calculated. As a result, the exhaust amount to the outside of the system becomes small. For this reason, according to the present invention, it is possible to set an appropriate target EGR rate according to the deterioration of the exhaust component concentration.

  According to the fourth invention, the actuator for controlling the supercharging pressure is used as the actuator for controlling the displacement. The lower the supercharging pressure, the smaller the amount of exhaust gas in-cylinder intake air. As a result, the amount of exhaust to the outside of the engine system becomes smaller. According to the present invention, the target supercharging pressure is calculated based on the heat difference, and the actuator is operated so that the actual supercharging pressure approaches the target supercharging pressure. Can be appropriately controlled.

  According to the fifth aspect of the invention, the coefficient that serves as an index of the exhaust component concentration is calculated based on the calorie difference. Then, a target fresh air amount is calculated based on the coefficient and the actual fresh air amount, and a target supercharging pressure for realizing the target fresh air amount is calculated. For this reason, according to this invention, the target supercharging pressure in which the influence of the calorie | heat amount difference was reflected can be calculated effectively.

  According to the sixth aspect of the invention, even in an engine equipped with an EGR device, the target in-cylinder intake air amount for realizing the target fresh air amount can be accurately calculated by considering the actual EGR rate.

It is a block diagram which shows the structure of the engine system to which the control apparatus of embodiment of this invention is applied. It is a flowchart which shows the routine for EGR control performed by the control apparatus of embodiment of this invention. It is a flowchart which shows the routine for the supercharging pressure control performed by the control apparatus of embodiment of this invention.

  Embodiments of the present invention will be described with reference to the drawings.

Embodiment 1 FIG.
FIG. 1 is a diagram showing a configuration of an engine system to which a control device according to an embodiment of the present invention is applied. The internal combustion engine according to the present embodiment is a diesel engine with a turbocharger (hereinafter simply referred to as an engine). The engine body 2 is provided with four cylinders in series, and an injector 8 is provided for each cylinder. An intake manifold 4 and an exhaust manifold 6 are attached to the engine body 2. An intake passage 10 through which fresh air taken in from the air cleaner 20 flows is connected to the intake manifold 4. A turbocharger compressor 14 is attached to the intake passage 10. A diesel throttle 24 is provided downstream of the compressor 14 in the intake passage 10. An intercooler 22 is provided between the compressor 14 and the diesel throttle 24 in the intake passage 10. The exhaust manifold 6 is connected to an exhaust passage 12 for releasing the exhaust gas emitted from the engine body 2 into the atmosphere. A turbocharger turbine 16 is attached to the exhaust passage 12. The turbocharger is a variable displacement type, and the turbine 16 is provided with a variable nozzle 18. A catalyst device 26 for purifying exhaust gas is provided downstream of the turbine 16 in the exhaust passage 12.

  The engine according to the present embodiment includes an EGR device that recirculates exhaust gas from the exhaust system to the intake system. In the EGR device, a position downstream of the diesel throttle 24 in the intake passage 10 and the exhaust manifold 6 are connected by an EGR passage 30. An EGR valve 32 is provided in the EGR passage 30. An EGR cooler 34 is provided on the exhaust side of the EGR valve 32 in the EGR passage 30. The EGR passage 30 is provided with a bypass passage 36 that bypasses the EGR cooler 34. A bypass valve 38 that switches the direction in which the exhaust gas flows is provided at a location where the bypass passage 36 branched from the EGR passage 30 joins the EGR passage 30 again.

  The engine system according to the present embodiment includes an ECU (Electronic Control Unit) 50. The ECU 50 is a control device that comprehensively controls the entire engine system, and the control device according to the present invention is embodied as one function of the ECU 50.

  The ECU 50 captures and processes a sensor signal provided in the engine system. Sensors are installed in various parts of the engine system. An air flow meter 58 is attached to the intake passage 10 downstream of the air cleaner 20, a supercharging pressure sensor 54 is attached downstream of the diesel throttle 24, and a temperature sensor 60 is attached to the intake manifold 4. An exhaust pressure sensor 56 is attached to the exhaust manifold 6. Further, a rotation speed sensor 52 that detects rotation of the crankshaft, an accelerator opening sensor 62 that outputs a signal corresponding to the opening of the accelerator pedal, and the like are also attached. The ECU 50 processes the signals of the acquired sensors and operates the actuators according to a predetermined control program. The actuator operated by the ECU 50 includes the variable nozzle 18, the injector 8, the EGR valve 32, the diesel throttle 24, and the like. There are many actuators and sensors connected to the ECU 50 other than those shown in the figure, but the description thereof is omitted in this specification.

  The engine control executed by the ECU 50 includes supercharging pressure control and EGR control. In the supercharging pressure control of the present embodiment, the variable nozzle 18 is operated by feedforward control and / or feedback control so that the actual supercharging pressure calculated from the signal of the supercharging pressure sensor 54 becomes the target supercharging pressure. The In EGR control, the EGR valve 32 is operated by feedforward control and / or feedback control so that the actual EGR rate calculated from the signals of the various sensors becomes the target EGR rate. In carrying out the present invention, there is no limitation regarding specific methods of feedforward control and feedback control in supercharging pressure control. Similarly, there is no limitation regarding a specific method of feedforward control and feedback control in EGR control.

  The EGR control executed in the present embodiment is characterized by a method for determining a target EGR rate. In conventional supercharging pressure control and EGR control, a method of determining a control target value based on an engine speed and a fuel injection amount on the assumption that the engine is in a steady operation is general. However, if the control target value is determined uniformly on the premise of the steady state of the engine, the in-cylinder combustion state becomes different from the assumption in the steady state during transient operation such as acceleration or deceleration. End up. That is, in a transient state of the engine, the actual in-cylinder supply heat amount that is the actual value of the in-cylinder supply heat amount that is supplied into the cylinder by intake air is more than the steady in-cylinder supply heat amount that is the in-cylinder supply heat amount assuming steady performance. It will be low. When the in-cylinder supply heat amount decreases, the gas temperature that the spray tackles in the air-fuel mixture formation process decreases, thereby inhibiting fuel vaporization. For this reason, in a transient state of the engine, the mixed state of the in-cylinder gas is deteriorated, and the concentration of exhaust components such as HC, CO and smoke may be deteriorated.

  Therefore, in the engine control executed in the present embodiment, the control for suppressing the exhaust amount to the outside of the engine system by increasing the EGR rate and increasing the exhaust gas recirculation amount in the transient operation in which the exhaust component concentration deteriorates. Run. More specifically, the exhaust amount suppression control according to the deterioration of the exhaust component concentration is realized by reflecting the heat amount difference between the steady in-cylinder supply heat amount and the actual in-cylinder supply heat amount in the target value of the EGR rate. According to such EGR control, since the exhaust amount can be suppressed during transient operation in which the exhaust component concentration deteriorates, it is possible to effectively suppress the situation where the exhaust properties deteriorate. Hereinafter, this EGR control will be described in detail with reference to flowcharts.

  FIG. 2 is a flowchart showing a routine executed by ECU 50 in the present embodiment. The flowchart of FIG. 2 shows a control routine related to EGR control in the engine control executed by the ECU 50. In the engine system according to the present embodiment, the actual boost pressure is set to the target boost pressure. It is assumed that the supercharging pressure control approaching is also performed in parallel by another control routine.

  In step S <b> 1 of the routine shown in FIG. 2, the engine speed is measured from the signal of the speed sensor 52. In step S2, the fuel injection amount is calculated according to the accelerator opening obtained from the signal of the accelerator opening sensor 62. In step S3, the temperature Tb of the gas in the intake manifold 4 is calculated from the signal from the temperature sensor 60. In step S4, the actual boost pressure pim, which is the pressure downstream of the EGR valve 32, is calculated from the signal of the boost pressure sensor 54. The processing in the above steps is processing for obtaining data necessary for processing in the steps described later. Therefore, the order of each step can be changed as appropriate.

In the next steps S5 to S8, processing for calculating an actual value (hereinafter referred to as “actual EGR rate”) egr of the current EGR rate is performed. More specifically, in step S5, an actual value (hereinafter referred to as “actual in-cylinder intake air amount”) Gcyl of the in-cylinder intake air amount is calculated. The actual in-cylinder intake air amount Gcyl can be expressed by the following function using the actual supercharging pressure pim and the intake manifold gas temperature Tb. In the following equation (1), T, a, and b are constants.
Gcyl = (T / Tb) * (a * pim + b) (1)

Next, in step S6, the actual fresh air amount Gn is calculated from the signal of the air flow meter 58. The actual amount of fresh air here is the amount of fresh air that is actually sucked into the cylinder at the present time. In step S7, the actual EGR rate egr is calculated according to the actual in-cylinder intake air amount Gcyl and the actual fresh air amount Gn acquired in steps S5-S6. The actual EGR rate egr can be calculated using the following formula using the actual in-cylinder intake air amount Gcyl and the actual new air amount Gn.
egr = (Gcyl-Gn) / Gcyl (2)

  In the next steps S8 to S13, the transient target EGR rate egrtrgk is calculated. The transient target EGR rate egrtrgk is a target value of the EGR rate in the EGR control executed in the present embodiment, and is calculated as a target value corresponding to the transient operation. The transient target EGR rate egrtrgk is calculated according to the heat amount difference between the steady in-cylinder supply heat amount and the actual in-cylinder supply heat amount. More specifically, in step S8, a steady in-cylinder supply heat amount Hst and a fresh air amount Gst based on steady performance are calculated according to the engine speed and the fuel injection amount acquired in steps S1-S2. The ECU 50 stores a map in which the steady in-cylinder supply heat amount Hst and the fresh air amount Gst are stored in association with the engine speed and the fuel injection amount. Here, the steady in-cylinder supply heat amount Hst and the fresh air amount Gst corresponding to the current operating conditions are calculated using these maps.

Next, in step S9, the actual in-cylinder supply heat amount H is calculated according to the intake manifold gas temperature Tb and the in-cylinder intake air amount Gcyl acquired in steps S2 and S5. The actual in-cylinder supply heat amount H means an actual value of the amount of heat sucked into the cylinder, and is calculated using the following equation using the intake manifold gas temperature Tb and the in-cylinder intake air amount Gcyl.
H = Gcyl * Tb (3)

Next, in step S10, the exhaust component concentration deterioration coefficient K1 is calculated using the heat difference ΔH between the steady in-cylinder supply heat amount Hst and the actual in-cylinder supply heat amount H. The exhaust component concentration deterioration coefficient K1 is a coefficient serving as an index representing the degree of deterioration of the exhaust component concentration. In the ECU 50, the exhaust component concentration deterioration coefficient K1 is stored in association with the calorie difference ΔH. More specifically, the exhaust gas component concentration deterioration coefficient K1 is stored such that K1 = 1 when the heat difference ΔH is 0, and becomes larger as the heat difference ΔH increases. Here, the exhaust component concentration deterioration coefficient K1 corresponding to the calorie difference ΔH is calculated using this map. In the next step S11, the exhaust gas flow rate reduction coefficient K2 is calculated using the following equation (4) using the exhaust gas component concentration deterioration coefficient K1 calculated in step S10. According to the following equation (4), the exhaust flow rate reduction coefficient K2 is calculated such that the larger the heat quantity difference ΔH is, the smaller the value is within a range of 0 <K2 ≦ 1.
K2 = 1 / K1 (K1 ≧ 1, 0 <K2 ≦ 1) (4)

In step S12 of the routine shown in FIG. 2, the transient target fresh air amount Gk is calculated using the exhaust flow rate reduction coefficient K2 calculated in step S11. The transient target fresh air amount Gk is a target value of the new air amount during the transient operation of the engine, and is calculated by the following equation (5) using the exhaust flow rate reduction coefficient K2. According to the following equation (5), the transient target fresh air amount Gk is calculated as a value that is smaller than the fresh air amount Gst that assumes steady performance as ΔH increases.
Gk = Gst * K2 (5)

Next, in step S13, a transient target EGR rate egrtrgk is calculated. The transient target EGR rate egrtrgk is calculated by the following equation (6) using the actual in-cylinder intake air amount Gcyl and the transient target fresh air amount Gk calculated in steps S5 and S12. As described above, the transient target fresh air amount Gk is calculated as a value smaller than the fresh air amount Gst on the premise of steady performance, as ΔH increases. Therefore, according to the following equation (6), the transient target EGR rate egrtrgk is calculated as a larger value as ΔH increases.
egrtrgk = (Gcyl-Gk) / Gcyl (6)

  In step S14, the feedforward value (F / F value) and the feedback value (F / B value) of the opening degree of the EGR valve 32 are calculated so that the actual EGR rate egr becomes the transient target EGR rate egrtrgk. The ECU 50 controls the EGR valve 32 using the calculated F / F value and F / B value.

  By performing EGR control according to the routine described above, the exhaust gas recirculation amount (EGR amount) can be increased during transient operation in which a calorific value difference occurs. The deterioration of properties can be effectively suppressed.

  In addition, according to the engine control of the present embodiment, it is possible to consolidate transient requirements into the EGR rate that is a control target in accordance with the mechanism for suppressing the exhaust amount during transient operation, thus preventing complication of adaptation. Is possible.

  By the way, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. For example, the following modifications may be made.

  In the above embodiment, the target value of the EGR rate is calculated as the control target value of EGR control, and the EGR valve is controlled so that the actual EGR rate becomes the target EGR rate. However, the control target value of EGR control It is also possible to calculate the target value of the EGR amount and control the EGR valve so that the actual EGR amount becomes the target EGR amount. Note that it is not preferable to directly use the operation amount of the actuator (that is, the opening degree of the EGR valve) as the control target value in the EGR control of the present invention. This is because the EGR amount cannot be controlled with high accuracy when the EGR valve has a disturbance element such as machine difference variation. In this respect, if the EGR rate or the EGR amount is used as the control target value, it is possible to absorb the machine difference variation of the EGR valve, and thus it is possible to control the EGR amount that is a control target with high accuracy. .

  In the above-described embodiment, the control device according to the present invention is applied to a diesel engine. However, the control device according to the present invention can also be applied to a spark ignition engine such as a gasoline engine. In the above embodiment, the temperature Tb of the gas in the intake manifold 4 is calculated from the signal of the temperature sensor 60. However, the method for calculating the gas temperature Tb is not limited to the method of directly detecting by the sensor. It is good also as estimating using another well-known method. Similarly, in the above-described embodiment, the actual supercharging pressure pim is calculated from the signal of the supercharging pressure sensor 54, but the calculation method of the actual supercharging pressure pim is not limited to the method of directly detecting by the sensor, It is good also as estimating using another well-known method.

Embodiment 2. FIG.
Next, a second embodiment of the present invention will be described. The second embodiment according to the present invention can be realized by causing the ECU 50 to execute a routine shown in FIG. 3 to be described later using the hardware configuration shown in FIG.

  In the engine control of the first embodiment described above, by setting the target EGR rate according to the heat amount difference between the steady in-cylinder supply heat amount and the actual in-cylinder supply heat amount, the exhaust amount is suppressed according to the deterioration of the exhaust component concentration. It is possible to do. On the other hand, in the engine control executed in the present embodiment, the exhaust amount to the outside of the engine system is reduced by lowering the boost pressure and reducing the in-cylinder intake air amount during transient operation in which the exhaust component concentration deteriorates. Suppress. More specifically, the exhaust amount suppression control according to the deterioration of the exhaust component concentration is realized by reflecting the heat amount difference between the steady in-cylinder supply heat amount and the actual in-cylinder supply heat amount in the target value of the supercharging pressure. According to such supercharging pressure control, since the exhaust amount can be suppressed during transient operation in which the exhaust component concentration deteriorates, it is possible to effectively suppress the situation where the exhaust properties deteriorate. Hereinafter, the supercharging pressure control will be described in detail with reference to flowcharts.

  FIG. 3 is a flowchart showing a routine executed by ECU 50 in the present embodiment. The flowchart in FIG. 3 shows a control routine related to the supercharging pressure control in the engine control executed by the ECU 50. In the engine system according to the present embodiment, the actual EGR rate is changed to the target EGR rate. The approaching EGR control is also performed in parallel by another control routine.

In steps S1-S12 of the routine shown in FIG. 3, the same processing as steps S1-S12 of the routine shown in FIG. 2 is executed. In the next step S21, the transient target in-cylinder intake air amount Gcylk is calculated. The transient target in-cylinder intake air amount Gcylk is a target value of the in-cylinder intake air amount in the supercharging pressure control executed in the present embodiment, and the actual EGR rate egr calculated in steps S7 and S12 and the transient It is calculated by the following equation (7) using the target fresh air amount Gk. The transient target fresh air amount Gk is calculated as a value that is smaller than the fresh air amount Gst that assumes steady performance as ΔH increases. Therefore, according to the following equation (7), the transient target in-cylinder intake air amount Gcylk is calculated as a smaller value as ΔH increases.
Gcylk = Gk / (1-egr) (7)

In the next step S22, the transient target boost pressure pimtrgk is calculated. The transient target supercharging pressure pimtrgk is a target value of the supercharging pressure in the supercharging pressure control executed in the present embodiment, and is calculated as a target value corresponding to the transient operation. The transient target boost pressure pimtrgk can be expressed by the following function using the intake manifold gas temperature Tb and the transient target in-cylinder intake air amount Gcylk calculated in steps S3 and S21. In the following equation (8), T, a, and b are constants. As described above, the transient target in-cylinder intake air amount Gcylk is calculated as a smaller value as ΔH increases. For this reason, according to the following equation (8), the transient target supercharging pressure pimtrgk is calculated as a smaller value as ΔH increases.
pimtrgk = (1 / a) * ((Gcylk * Tb / T) −b) (8)

  In step S23, the feedforward value (F / F value) and the feedback value (F / B value) of the opening of the variable nozzle 18 are calculated so that the actual boost pressure pim becomes the transient target boost pressure pimtrgk. The The ECU 50 controls the variable nozzle 18 using the calculated F / F value and F / B value.

  By performing the supercharging pressure control according to the routine described above, it is possible to reduce the supercharging pressure and reduce the intake air amount in the cylinder during the transient operation in which the heat quantity difference occurs. Deterioration of exhaust properties can be effectively avoided.

  In addition, according to the engine control of the present embodiment, transient requirements can be aggregated to the supercharging pressure that is the control target in accordance with the mechanism for suppressing the displacement during transient operation, thus preventing complication of adaptation. It becomes possible.

  By the way, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. For example, the following modifications may be made.

  In the above-described embodiment, the target value of the supercharging pressure is calculated as the control target value of the supercharging pressure control, and the variable nozzle is controlled so that the actual supercharging pressure becomes the target supercharging pressure. In addition to the variable nozzle, a waste gate valve can be used as the actuator for controlling the supply pressure. However, it is desirable that the wastegate valve in that case can change the opening degree continuously or in multiple stages. Note that it is not preferable to directly use the operation amount of the actuator (that is, the opening of the variable nozzle) as the control target value in the supercharging pressure control of the present invention. This is because the supercharging pressure cannot be controlled with high accuracy when the variable nozzle has a disturbance element such as machine difference variation. In this regard, if the supercharging pressure is used as the control target value, it is possible to absorb the machine difference variation of the variable nozzle, and therefore it is possible to control the supercharging pressure as a control target with high accuracy.

  In the above-described embodiment, the control device according to the present invention is applied to a diesel engine. However, the control device according to the present invention can also be applied to a spark ignition engine such as a gasoline engine. Further, in the above-described embodiment, the supercharging pressure control for suppressing the exhaust amount at the time of transition is performed in the engine including the EGR device, but the above-described supercharging pressure control is performed in the engine not including the EGR device. It is good as well.

  In the above embodiment, the temperature Tb of the gas in the intake manifold 4 is calculated from the signal of the temperature sensor 60. However, the method for calculating the gas temperature Tb is not limited to the method of directly detecting by the sensor. It is good also as estimating using another well-known method. Similarly, in the above-described embodiment, the actual supercharging pressure pim is calculated from the signal of the supercharging pressure sensor 54, but the calculation method of the actual supercharging pressure pim is not limited to the method of directly detecting by the sensor, It is good also as estimating using another well-known method.

2 Engine body 4 Intake manifold 6 Exhaust manifold 18 Variable nozzle 30 EGR passage 32 EGR valve 50 ECU
52 Rotational Speed Sensor 54 Supercharging Pressure Sensor 56 Exhaust Pressure Sensor 60 Temperature Sensor 62 Accelerator Opening Sensor

Claims (6)

In a control device for an internal combustion engine with a turbocharger,
Means for calculating an actual in-cylinder intake air amount of the internal combustion engine based on a gas temperature and a supercharging pressure sucked into the internal combustion engine;
Means for calculating an actual in-cylinder supply heat amount based on the actual in-cylinder intake air amount and the gas temperature;
Means for calculating a steady in-cylinder supply heat amount, which is a heat amount supplied into the cylinder during steady operation, based on the engine speed and the fuel injection amount;
Control means for controlling an exhaust amount exhausted from the internal combustion engine in accordance with a heat amount difference between the steady in-cylinder supply heat amount and the actual in-cylinder supply heat amount;
A control device for an internal combustion engine with a turbocharger, comprising: The internal combustion engine includes an EGR device that recirculates exhaust gas from an exhaust passage to an intake passage,
The control means includes
Target EGR rate calculation means for calculating a target EGR rate according to the heat difference,
Means for operating the EGR device by feedback control so that an actual EGR rate approaches the target EGR rate;
The control apparatus for an internal combustion engine with a turbocharger according to claim 1, comprising: The target EGR rate calculation means includes:
Means for calculating a coefficient serving as an index of the concentration of unpurified components in the exhaust gas based on the calorific value difference;
Means for calculating a target fresh air amount that is a target value of the fresh air amount based on the coefficient and an actual fresh air amount that is an actual value of the fresh air amount sucked into the internal combustion engine;
Means for calculating the target EGR rate based on the actual in-cylinder intake air amount and the target fresh air amount;
The control apparatus for an internal combustion engine with a turbocharger according to claim 2, comprising: The internal combustion engine includes an actuator for controlling a supercharging pressure,
The control means includes
A target boost pressure calculating means for calculating a target boost pressure according to the heat amount difference;
Means for operating the actuator by feedback control to bring the actual boost pressure closer to the target boost pressure;
The control apparatus for an internal combustion engine with a turbocharger according to claim 1, comprising: The target boost pressure calculating means includes
Means for calculating a coefficient serving as an index of the concentration of unpurified components in the exhaust gas based on the calorific value difference;
Means for calculating a target fresh air amount that is a target value of the fresh air amount based on the coefficient and an actual fresh air amount that is an actual value of the fresh air amount sucked into the internal combustion engine;
Means for calculating a target in-cylinder intake air amount based on the target fresh air amount;
Means for calculating the target boost pressure based on the target cylinder intake air amount and the gas temperature;
The control apparatus for an internal combustion engine with a turbocharger according to claim 4, comprising: The internal combustion engine includes an EGR device that recirculates exhaust gas from an exhaust passage to an intake passage,
The internal turbocharger-equipped internal combustion engine according to claim 5, wherein the target supercharging pressure calculating means includes means for calculating the target in-cylinder intake air amount based on an actual EGR rate and the target fresh air amount. Engine control device.

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