JP2017066939A - Control method of internal combustion engine and control device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control method of an internal combustion engine and a control device of the internal combustion engine capable of lowering turbine upstream-side pressure/turbine downstream-side pressure to a prescribed pressure ratio or less even in sudden acceleration of the internal combustion engine.SOLUTION: A control method of an internal combustion engine has a stepping amount prediction step (S115) for predicting an accelerator pedal stepping amount, an exhaust gas flow rate prediction step (S120) for predicting an exhaust gas flow rate on the basis of the accelerator pedal stepping amount and an operation state, a target opening prediction step (S125) for predicting a variable nozzle target opening on the basis of the exhaust gas flow rate and the operation state, an actual opening prediction step (S130) for predicting a variable nozzle actual opening on the basis of a variable nozzle follow-up time memorized in memorizing means, a present opening of a variable nozzle, and a variable nozzle target opening, and an exhaust gas flow rate reduction step (S145-S155) for forcibly and temporarily reducing the flow rate of the exhaust gas when delay in following-up of the variable nozzle actual opening to the variable nozzle target opening, is determined.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a control method for an internal combustion engine including a turbocharger having a variable nozzle capable of controlling a flow rate of exhaust gas to a turbine, and a control device for the internal combustion engine.

  In recent years, an internal combustion engine equipped with a turbocharger having a variable nozzle has been widely used. In such an internal combustion engine, by controlling the opening of the variable nozzle, it is possible to obtain an appropriate boost pressure even when the rotational speed of the internal combustion engine is low, and improve the output characteristics of the internal combustion engine. Can be made. When an internal combustion engine equipped with a turbocharger is operated at a very high load and high rotation, the life of the turbocharger turbine may be shortened. Stress is generated before and after the turbine due to the large pressure difference before and after the turbine that occurs when the internal combustion engine is operated at very high load and high rotation, and the exhaust pulsation that occurs during each explosion process of the internal combustion engine It is. If a stress exceeding a predetermined stress is continuously applied for a long time, the life of the turbine may be shortened. In order to avoid this, it is known that the pressure ratio before and after the turbine (pressure on the upstream side of the turbine / pressure on the downstream side of the turbine) may be controlled to be equal to or less than a predetermined pressure ratio.

  Therefore, in Patent Document 1, the fuel flow rate is calculated from the injection amount and the internal combustion engine speed, the upstream pressure that is the pressure upstream of the turbine is calculated from the fuel flow rate, the intake air flow rate, and the atmospheric pressure, and the fuel flow rate and the intake air are calculated. The upstream temperature, which is the temperature upstream of the turbine, is calculated from the flow rate and the injection amount. The turbine flow rate is calculated based on the fuel flow rate, the intake air flow rate, the upstream pressure, and the upstream temperature, and the upper limit of the opening amount of the variable nozzle based on the calculated turbine flow rate and the pressure ratio / turbine flow rate characteristics. A threshold is calculated, and the opening of the variable nozzle is controlled so that the opening is less than or equal to the upper threshold. By this control, the pressure on the upstream side of the turbine / the pressure on the downstream side of the turbine can be set to a predetermined pressure ratio or less without providing pressure sensors on the upstream side and the downstream side of the turbine.

JP 2014-043829 A

  In the control method for an internal combustion engine described in Patent Document 1, the pressure on the upstream side of the turbine / the pressure on the downstream side of the turbine can be set to a predetermined pressure ratio or less in various operating states of the internal combustion engine. However, in an operating state where the internal combustion engine is decelerating rapidly during deceleration, there is a possibility that the pressure on the upstream side of the turbine / the pressure on the downstream side of the turbine cannot be temporarily suppressed below a predetermined pressure ratio for a short time. .

  The present invention was devised in view of such points, and even when the internal combustion engine is suddenly accelerated, the pressure on the upstream side of the turbine / the pressure on the downstream side of the turbine is set to a predetermined pressure ratio or less. It is an object of the present invention to provide an internal combustion engine control method and an internal combustion engine control apparatus that are capable of performing the above.

  In order to solve the above problems, an internal combustion engine control method and an internal combustion engine control apparatus according to the present invention employ the following means. A first aspect of the present invention is a control method for an internal combustion engine that controls a variable nozzle capable of adjusting a flow rate of exhaust gas to a turbine of a turbocharger, and detects an acceleration request from a driver. A depression amount prediction step for predicting an accelerator pedal depression amount, an exhaust gas flow rate prediction step for predicting an exhaust gas flow rate from the internal combustion engine based on the predicted accelerator pedal depression amount and an operating state of the internal combustion engine, A target opening prediction step for predicting a variable nozzle target opening based on the predicted exhaust gas flow rate and the operating state of the internal combustion engine; a variable nozzle follow-up time stored in advance in storage means; An actual opening prediction step for predicting a variable nozzle actual opening that is an actual opening of the variable nozzle based on the current opening and the variable nozzle target opening; An exhaust gas flow rate reducing step for forcibly reducing the flow rate of exhaust gas from the internal combustion engine when it is determined that the follow-up of the predicted actual variable nozzle opening is delayed with respect to the variable nozzle target opening; Have.

  According to the first aspect of the present invention, the variable nozzle actual opening estimated in consideration of the mechanical response time of the actual variable nozzle with respect to the variable nozzle target opening predicted according to the (rapid) acceleration request is Predict whether or not you can follow without delay. If it is determined that the follow-up of the actual variable nozzle opening is delayed, the flow rate of the exhaust gas is temporarily reduced so that the pressure on the upstream side of the turbine / the pressure on the downstream side of the turbine is less than or equal to a predetermined pressure ratio. Can do. Accordingly, even during the rapid acceleration of the internal combustion engine, the pressure on the upstream side of the turbine / the pressure on the downstream side of the turbine can be set to a predetermined pressure ratio or less.

  Next, a second invention of the present invention is a control method for an internal combustion engine according to the first invention, wherein an electronic throttle capable of adjusting an intake air amount to the internal combustion engine is provided in an intake path of the internal combustion engine. A device is provided, and in the exhaust gas flow rate reduction step, the electronic throttle device is temporarily controlled to the throttle side to forcibly reduce the exhaust gas flow rate temporarily.

  According to the second invention, in the exhaust gas flow rate reduction step, the flow rate of the exhaust gas is temporarily reduced by temporarily controlling the electronic throttle device to the throttle side. Thereby, since the flow rate of the exhaust gas can be temporarily reduced with good responsiveness, the pressure on the upstream side of the turbine / the pressure on the downstream side of the turbine can be set to a predetermined pressure ratio or less.

  Next, a third invention of the present invention is a method for controlling an internal combustion engine according to the first invention, wherein the internal combustion engine is provided with an injector for injecting fuel to be supplied to the internal combustion engine. In the exhaust gas flow rate reduction step, the flow rate of the exhaust gas is forcibly reduced temporarily by temporarily reducing the amount of fuel injected from the injector.

  According to the third invention, in the exhaust gas flow rate reduction step, the flow rate of the exhaust gas is temporarily reduced by temporarily reducing the amount of fuel injected from the injector. Thereby, since the flow rate of the exhaust gas can be temporarily reduced with good responsiveness, the pressure on the upstream side of the turbine / the pressure on the downstream side of the turbine can be set to a predetermined pressure ratio or less.

  Next, a fourth aspect of the present invention is an internal combustion engine control device that controls a variable nozzle capable of adjusting a flow rate of exhaust gas to a turbine of a turbocharger, and detects an acceleration request from a driver. A depression amount prediction means for predicting an accelerator pedal depression amount, and an exhaust gas flow rate prediction means for predicting an exhaust gas flow rate from the internal combustion engine based on the predicted depression amount of the accelerator pedal and an operating state of the internal combustion engine; Target opening prediction means for predicting a variable nozzle target opening based on the predicted exhaust gas flow rate and the operating state of the internal combustion engine; variable nozzle response time stored in advance in storage means; and the variable nozzle Based on the current opening and the variable nozzle target opening, an actual opening prediction means for predicting a variable nozzle actual opening that is an actual opening of the variable nozzle after a predetermined time has elapsed since the present Exhaust gas that temporarily decreases the flow rate of the exhaust gas from the internal combustion engine when it is determined that the follow-up of the predicted variable nozzle actual opening is delayed with respect to the predicted variable nozzle target opening And a flow rate reducing means.

  According to the fourth aspect of the invention, there is provided a control device for an internal combustion engine that can reduce the pressure on the upstream side of the turbine / the pressure on the downstream side of the turbine to a predetermined pressure ratio or less even during sudden acceleration of the internal combustion engine. can do.

It is a figure explaining the schematic structure of the internal combustion engine to which the control method of the internal combustion engine of the present invention is applied. It is a figure explaining the example of the input / output of the control apparatus of an internal combustion engine, and the structure of the said control apparatus. It is a flowchart explaining the process sequence of the control apparatus of an internal combustion engine. In the explanation of the processing procedure of the flowchart, the predicted accelerator pedal depression amount, the predicted exhaust gas flow rate, the predicted variable nozzle target opening, the predicted variable nozzle actual opening, and the state of temporarily reducing the exhaust gas flow rate (electronic throttle It is a time chart explaining the example of the throttle target opening degree of an apparatus.

EMBODIMENT OF THE INVENTION Below, the form for implementing this invention is demonstrated using drawing.
● [Schematic configuration of the internal combustion engine to be controlled (Fig. 1)]
First, a schematic configuration of an internal combustion engine to be controlled will be described with reference to FIG. In the description of the present embodiment, a description will be given using a four-cylinder engine 10 (for example, a diesel engine) as an example of an internal combustion engine. The engine 10 is connected to an intake pipe 11 that introduces intake air into the cylinders 45 </ b> A to 45 </ b> D of the engine 10. The engine 10 is connected to an exhaust pipe 12 through which exhaust gas from each of the cylinders 45A to 45D is discharged. The cylinders 45A to 45D are provided with injectors 43A to 43D connected to the common rail 41 via fuel pipes 42A to 42D. A compressor 35 of the turbocharger 30 is provided in the intake path of the intake pipe 11, and a turbine 36 of the turbocharger 30 is provided in the exhaust path of the exhaust pipe 12. The control device 50 includes at least a control unit 51 and a storage unit 53.

  The flow rate detection means 21 is a flow rate sensor capable of detecting the flow rate of intake air, for example, and is provided in the intake passage 11A. The control means 51 can detect the intake air flow rate that is the flow rate of the intake air taken in by the engine 10 based on the detection signal from the flow rate detection means 21.

  The rotation detection means 22 is a rotation angle sensor that can detect, for example, the rotation speed of the internal combustion engine (for example, the rotation speed of the crankshaft), the rotation angle (for example, the compression top dead center timing of each cylinder), and the like. ing. The control unit 51 can detect the rotation speed, rotation angle, and the like of the engine 10 based on the detection signal from the rotation detection unit 22.

  The atmospheric pressure detection means 23 is an atmospheric pressure sensor, for example, and is provided in the control device 50. The control means 51 can detect the atmospheric pressure based on the detection signal from the atmospheric pressure detection means 23.

  The supercharging pressure detection means 24 is a pressure sensor, for example, and is provided in the intake pipe 11. The control means 51 can detect the pressure of the intake air supercharged by the compressor 35 based on the detection signal from the supercharging pressure detection means 24.

  The accelerator pedal depression amount detection means 25 is an accelerator pedal depression angle sensor, for example, and is provided on the accelerator pedal. The control means 51 can detect the amount of depression of the accelerator pedal by the driver based on the detection signal from the accelerator pedal depression amount detection means 25.

  The turbocharger 30 includes a compressor 35 having a compressor impeller 35A and a turbine 36 having a turbine impeller 36A. The turbine 36 is provided with a variable nozzle 33 capable of controlling the flow rate of the exhaust gas to the turbine impeller 36 </ b> A, and the opening degree of the variable nozzle 33 is adjusted by the driving means 31. The control means 51 can output a control signal to the drive means 31 to adjust the opening of the variable nozzle 33, and based on the detection signal from the opening detection means 32 (for example, a nozzle opening sensor), the variable nozzle It is possible to detect the opening of 33.

  An intake passage 11 </ b> A and an intake pipe 11 are connected to the compressor 35. The compressor 35 sucks intake air from the intake passage 11 </ b> A, compresses it with the compressor impeller 35 </ b> A, and supercharges it by discharging the compressed intake air to the intake pipe 11. An exhaust passage 12 </ b> A and the exhaust pipe 12 are connected to the turbine 36. The high-temperature and high-pressure exhaust gas from the exhaust pipe 12 is introduced into the turbine 36, and the turbine impeller 36A (and the compressor impeller 35A) is rotationally driven to be discharged into the exhaust passage 12A.

  The EGR passage 13 allows the exhaust pipe 12 and the intake pipe 11 to communicate with each other and allows the exhaust gas in the exhaust pipe 12 to recirculate to the intake pipe 11. The EGR valve 14 is disposed in the EGR passage 13 and adjusts the opening degree of the EGR passage 13 based on a control signal from the control means 51.

  Fuel is supplied to the common rail 41 from a fuel tank (not shown), and the fuel in the common rail 41 is maintained at a high pressure and supplied to each of the injectors 43A to 43D via the fuel pipes 42A to 42D. The injectors 43A to 43D are provided corresponding to the respective cylinders 45A to 45D, and inject a predetermined amount of fuel into each cylinder at a predetermined timing by a control signal from the control means 51.

  The electronic throttle device 47 is provided in the intake pipe 11 (intake path), and adjusts the opening of the intake pipe 11 based on a control signal from the control means 51 to adjust the intake flow rate. The control means 51 can adjust the opening of the intake pipe 11 by outputting a control signal to the electronic throttle device 47, and based on the detection signal from the throttle opening detection means 47S (for example, a throttle opening sensor), The opening degree of the electronic throttle device 47 can be detected.

  The control means 51 is, for example, a CPU (Central Processing Unit), and as shown in FIG. 2, detection signals from the various detection means described above are input to detect the operating state of the engine 10 and injectors 43A to 43A. 43D, the EGR valve 14 and the control signal for driving the electronic throttle device 47 are output. The control means 51 can detect the amount of fuel supplied to each of the cylinders 45A to 45D based on a control signal (injection command signal) output to the injectors 43A to 43D. Moreover, the input to the control means 51 and the output from the control means 51 are not limited to the example of FIG.1 and FIG.2. For example, the control means 51 can receive information on the operating state of the transmission that transmits the power of the internal combustion engine to the wheels, and can detect the gear stage (first speed, second speed, third speed, etc.) of the transmission. is there. In addition, description of each means of code | symbol 51A-51E in FIG. 2 is mentioned later.

  The storage means 53 is a storage device such as a Flash-ROM, for example, and stores a program for executing a processing procedure described later, a variable nozzle tracking time, and the like.

[Processing procedure of control means 51 (FIG. 3)]
When the internal combustion engine is operated at a very high load and high rotation, a large pressure difference is generated before and after the turbine impeller 36A. Further, exhaust pulsation occurs at every explosion process of the internal combustion engine. Due to this pressure difference and exhaust pulsation, a stress is generated before and after the turbine impeller 36A, and if the stress exceeding the predetermined stress is continued for a long time, the life of the turbine impeller 36A may be shortened. In particular, in an operating state in which the internal combustion engine is accelerated rapidly during deceleration, the pressure upstream of the turbine / pressure downstream of the turbine (hereinafter, “pressure upstream of the turbine / pressure downstream of the turbine” is expressed as “(pressure) expansion ratio”. It is difficult to set the pressure ratio to a predetermined pressure ratio or less. In the processing of the present application described below, the (pressure) expansion ratio can be set to a predetermined pressure ratio or less even in an operating state where the internal combustion engine is accelerated rapidly during deceleration. Hereinafter, the process of each step of the flowchart shown in FIG. 3 will be described. 3 is executed at a predetermined timing (for example, a predetermined time interval such as several ms to several tens of ms). When the process S100 is activated, the control unit 51 advances the process to Step S110.

  In step S110, the control means 51 determines whether or not there is an acceleration request from the driver. If there is an acceleration request (Yes), the process proceeds to step S115, and if there is no acceleration request (No), the process proceeds to step S190. For example, the control means 51 determines that there is an acceleration request when the increase ratio of the accelerator pedal depression amount detected based on the detection signal from the accelerator pedal depression amount detection means is equal to or greater than a predetermined ratio.

  When the processing proceeds to step S190, the control means 51 performs control of the conventional variable nozzle (because acceleration is not being requested) and ends the processing. Detailed description of the conventional control of the variable nozzle is omitted.

  When the routine proceeds to step S115, the control means 51 predicts the accelerator pedal depression amount (until a predetermined time later) and proceeds to step S120. For example, the control means 51 predicts the accelerator pedal depression amount (within the prediction period) based on the increase rate of the accelerator pedal depression amount detected based on the detection signal from the accelerator pedal depression amount detection means. The predicted accelerator pedal depression amount is, for example, “accelerator pedal depression amount (A)” indicated by a dotted line in “accelerator pedal depression amount” in FIG. 4. The processes of steps S110 and S115 correspond to a depression amount prediction step of detecting an acceleration request from the driver and predicting the accelerator pedal depression amount. And the control means 51 which is performing the said depression amount prediction step operate | moves as the depression amount prediction means 51A shown in FIG.

  In step S120, the control means 51 predicts the exhaust gas flow rate (until a predetermined time later) and proceeds to step S125. For example, the control means 51 is based on the accelerator pedal depression amount predicted in step S115 and the operating state of the engine 10 (internal combustion engine) (for example, the rotational speed, the gear position of the transmission, the required torque, the EGR amount, etc.). The flow rate of the exhaust gas from the engine 10 (internal combustion engine) is predicted. When predicting the exhaust gas flow rate, the control means 51 predicts the intake air amount and the fuel injection amount in consideration of, for example, the increase in the rotational speed and the boost pressure, and based on the predicted intake air amount and the fuel injection amount, Predict the exhaust gas flow rate. The predicted exhaust gas flow rate is, for example, “exhaust gas flow rate (B)” indicated by a dotted line in “exhaust gas flow rate” of FIG. The process of step S120 corresponds to an exhaust gas flow rate prediction step of predicting the exhaust gas flow rate from the internal combustion engine based on the predicted accelerator pedal depression amount and the operating state of the internal combustion engine. And the control means 51 which is performing the said exhaust gas flow volume prediction step operate | moves as the exhaust gas flow volume prediction means 51B shown in FIG.

  In step S125, the control means 51 predicts the variable nozzle target opening (until a predetermined time) and proceeds to step S130. For example, the control means 51 predicts the variable nozzle target opening (within the prediction period) based on the exhaust gas flow rate predicted in step S120 and the operating state of the engine 10 (internal combustion engine). When the control unit 51 predicts the variable nozzle target opening, the control unit 51 sets a variable nozzle opening that can make the (pressure) expansion ratio equal to or less than a predetermined pressure ratio with respect to the exhaust gas flow rate predicted in step S120. The variable nozzle target opening is calculated. The predicted variable nozzle target opening is, for example, “variable nozzle target opening (C)” indicated by a one-dot chain line in “variable nozzle opening” in FIG. The process of step S125 corresponds to a target opening degree prediction step for predicting the variable nozzle target opening degree based on the predicted exhaust gas flow rate and the operating state of the internal combustion engine. And the control means 51 which is performing the said target opening prediction step operate | moves as the target opening prediction means 51C shown in FIG.

  In step S130, the control means 51 predicts a variable nozzle actual opening that is an actual opening of the variable nozzle (until a predetermined time), and proceeds to step S135. For example, the control means 51, the variable nozzle follow-up time stored in advance in the storage means 53, the current opening degree of the variable nozzle detected based on the detection signal from the opening degree detection means, and the variable predicted in step S125. Based on the target nozzle opening, the actual variable nozzle opening (within the prediction period) is predicted. The opening of the variable nozzle is mechanically controlled using an electric motor or the like, and a mechanical delay may occur. The variable nozzle following time corresponding to the mechanical delay is obtained by various experiments and stored in the storage means.

  When the predicted variable nozzle actual opening is predicted to cause a follow-up delay, for example, “variable nozzle actual opening (D1) (follow-up delay occurs) indicated by a dotted line in“ variable nozzle opening ”in FIG. )). Further, when it is predicted that no follow-up delay will occur, for example, “variable nozzle actual opening (D2) indicated by a two-dot chain line in“ variable nozzle opening ”of FIG. 4 (when no follow-up delay occurs) ) ". The process of step S130 is performed based on the variable nozzle follow-up time stored in the storage unit in advance, the current opening of the variable nozzle, and the variable nozzle target opening predicted in step S125. This corresponds to an actual opening degree prediction step for predicting the degree. And the control means 51 which is performing the said actual opening prediction step operate | moves as the actual opening prediction means 51D shown in FIG.

  In step S135, the control unit 51 determines whether or not it is predicted that there is a follow-up delay of the variable nozzle. If it is predicted that a follow-up delay will occur (Yes), the process proceeds to step S140A and the follow-up delay does not occur. If predicted (No), the process proceeds to step S140B. For example, the control means 51 determines whether or not the variable nozzle actual opening predicted in step S130 can follow the variable nozzle target opening predicted in step S125 without delay, and follows for a predetermined time or more. When it is predicted that a delay will occur, it is predicted that a tracking delay will occur.

  When the process proceeds to step S140B, the control unit 51 controls the variable nozzle with the “variable nozzle target opening (C)” of the “variable nozzle opening” shown in FIG. In this case, since it is predicted that there is no follow-up delay, as shown in “Predicted variable nozzle actual opening (D2) (when no follow-up delay occurs)” of “Variable nozzle opening” in FIG. The actual opening of the variable nozzle is controlled. It should be noted that the “variable nozzle opening” shown in FIG. 4 is the “closed” direction at the top and the “open” direction at the bottom. That is, “the variable nozzle target opening (C) shown in FIG. 4 is controlled as the upper limit opening” means that when the upper part is replaced with the “open” direction, the variable nozzle target opening (C) is below the variable nozzle target opening (C). It will be controlled so that there is no.

  When the process proceeds to step S140A, the control unit 51 controls the variable nozzle so that the “variable nozzle target opening (C)” of the “variable nozzle opening” shown in FIG. 4 is reached, and the process proceeds to step S145. In this case, since it is predicted that there is a follow-up delay, even if the variable nozzle is controlled with the target of “variable nozzle target opening (C)”, “predicted variable” of “variable nozzle opening” in FIG. As shown in "Nozzle actual opening (D1) (when follow-up delay occurs)", a follow-up delay occurs with respect to the variable nozzle target opening (C).

  When the process proceeds to step S145, the control means 51 calculates the target intake air amount and proceeds to step S150. For example, when the variable nozzle is controlled with the variable nozzle actual opening (within the prediction period) based on the variable nozzle actual opening predicted in step S130 and the operating state of the internal combustion engine, the control means 51 Further, an exhaust gas flow rate capable of setting the (pressure) expansion ratio to be equal to or lower than a predetermined pressure ratio is calculated, and a target intake air amount that is an intake air flow rate corresponding to the calculated exhaust gas flow rate is calculated.

  In step S150, the control means 51 calculates the throttle target opening, which is the target opening of the electronic throttle device, based on the target intake air amount, and proceeds to step S155. For example, the control unit 51 determines the flow rate of the intake air detected by the flow rate detection unit 21 (within the prediction period) based on the target intake air amount calculated in step S145 and the operating state (rotation speed) of the internal combustion engine. The throttle target opening is calculated so that becomes the target intake air amount. The throttle target opening (E1) (see FIG. 4) calculated in step S150 is the target opening of the electronic throttle device when a follow-up delay occurs in the variable nozzle, and the follow-up delay of the variable nozzle occurs. In order to temporarily reduce the flow rate of the exhaust gas during a certain period, the electronic throttle device is set to be temporarily controlled to the throttle side. On the other hand, the “throttle target opening (E2) (when no follow-up delay has occurred in the variable nozzle)” indicated by a one-dot chain line in the “electronic throttle opening” of FIG. 4 is the process shown in FIG. An example of the throttle target opening (E2) calculated by another process (not shown) is shown.

  In step S155, the control means 51 controls the electronic throttle device with the throttle target opening (E1) shown in FIG. Note that the “electronic throttle opening” shown in FIG. 4 is the “closed” direction at the top and the “open” direction at the bottom. That is, “the throttle target opening (E1) shown in FIG. 4 is controlled as the lower limit opening” means that the throttle target opening (E1) is not exceeded when the upper part is replaced with the “open” direction. It will be to control.

  The processes of steps S135, S145, S150, and S155 are the variable nozzle actual opening predicted in the actual opening prediction step (S130) with respect to the variable nozzle target opening predicted in the target opening prediction step (S125). Is determined to be delayed, this corresponds to an exhaust gas flow rate reduction step for forcibly reducing the exhaust gas flow rate from the internal combustion engine. And the control means 51 which is performing the said exhaust gas flow volume reduction step operate | moves as the exhaust gas flow volume reduction means 51E shown in FIG.

  In the processing of steps S145, S150, and S155, when the follow-up delay of the variable nozzle occurs, the flow rate of the exhaust gas is temporarily set so that the (pressure) expansion ratio is less than or equal to a predetermined pressure ratio. As a means for reducing, the intake air amount is temporarily reduced using an electronic throttle device, but the invention is not limited to this means.

  For example, the fuel injection amount from the injector may be temporarily reduced. In this case, instead of steps S145, S150, and S155, for example, the control unit 51 uses the variable nozzle actual opening based on the variable nozzle actual opening predicted in step S130 and the operating state of the internal combustion engine. When the variable nozzle is controlled, an exhaust gas flow rate that can reduce the (pressure) expansion ratio to a predetermined pressure ratio or less is calculated, and based on the calculated exhaust gas flow rate and the operating state of the internal combustion engine, A fuel injection amount from the injector is calculated. And the control means 51 outputs the control signal based on the calculated fuel injection quantity, and controls an injector. In this case, in order to temporarily reduce the flow rate of the exhaust gas, the fuel injection amount from the injector is temporarily reduced.

  In the above description of the present embodiment, the control method of the internal combustion engine has been mainly described. However, the control device 50 of the internal combustion engine, which is a device for implementing the control method of the internal combustion engine, is shown in FIG. It may be configured.

  As described above, the internal combustion engine control method and internal combustion engine control apparatus described in the present embodiment operate when the (pressure) expansion ratio during acceleration may exceed a predetermined pressure ratio, and the turbine is damaged. Can be prevented and the life can be extended. Moreover, in order to prevent the follow-up delay of the variable nozzle actual opening, it is possible to suppress an excessive load on an actuator such as an electric motor. If the (pressure) expansion ratio is not likely to exceed a predetermined pressure ratio, not during acceleration, the processing of FIG. 3 described in the present embodiment is not executed (the conventional control in step S190 is performed). Therefore, useless reduction in supercharging pressure is suppressed, and reduction in power of the internal combustion engine can be avoided. In addition, it is possible to avoid a shortage of the EGR amount due to the fact that the variable nozzle cannot be closed to the variable nozzle opening required for exhaust. Furthermore, in addition to the above-described effects, it is possible to appropriately avoid the occurrence of smoke deterioration due to the rich air-fuel ratio due to the decrease in supercharging pressure caused by opening the variable nozzle.

  The internal combustion engine control method and internal combustion engine control apparatus of the present invention are not limited to the configuration, processing, operation, and the like described in the present embodiment, and various modifications, additions, and deletions are possible without departing from the scope of the present invention. Is possible.

  The target control system to which the internal combustion engine control method and the internal combustion engine control apparatus according to the present invention are applied is not limited to that shown in the example of FIG. 1, and various types of turbochargers having variable nozzles are provided. It is possible to apply to an internal combustion engine.

  Further, the above (≧), the following (≦), the greater (>), the less (<), etc. may or may not include an equal sign.

10 Engine (Internal combustion engine)
DESCRIPTION OF SYMBOLS 11 Intake pipe 12 Exhaust pipe 13 EGR passage 14 EGR valve 21 Flow rate detection means 22 Rotation detection means 23 Atmospheric pressure detection means 24 Supercharging pressure detection means 25 Accelerator pedal depression amount detection means 30 Turbocharger 31 Drive means 32 Opening degree detection Means 33 Variable nozzle 35 Compressor 35A Compressor impeller 36 Turbine 36A Turbine impeller 41 Common rail 43A-43D Injector 45A-45D Cylinder 47 Electronic throttle device 47S Throttle opening detection means 50 Control device 51 Control means 51A Depression amount prediction means 51B Exhaust gas flow prediction Means 51C Target opening degree predicting means 51D Actual opening degree predicting means 51E Exhaust gas flow rate reducing means 53 Storage means

Claims (4)

A control method for an internal combustion engine for controlling a variable nozzle capable of adjusting a flow rate of exhaust gas to a turbine of a turbocharger,
A depression amount predicting step for detecting an acceleration request from the driver and predicting an accelerator pedal depression amount;
An exhaust gas flow rate predicting step for predicting an exhaust gas flow rate from the internal combustion engine based on the predicted accelerator pedal depression amount and the operating state of the internal combustion engine;
A target opening prediction step for predicting a variable nozzle target opening based on the predicted exhaust gas flow rate and the operating state of the internal combustion engine;
Based on the variable nozzle tracking time stored in advance in the storage means, the current opening of the variable nozzle, and the variable nozzle target opening, the variable nozzle actual opening that is the actual opening of the variable nozzle An actual opening prediction step for predicting the degree,
Exhaust gas flow rate that forcibly decreases the flow rate of exhaust gas from the internal combustion engine when it is determined that the follow-up of the predicted actual variable nozzle opening is delayed with respect to the predicted variable nozzle target opening A reduction step,
A method for controlling an internal combustion engine. A control method for an internal combustion engine according to claim 1,
The intake passage of the internal combustion engine is provided with an electronic throttle device capable of adjusting the intake air amount to the internal combustion engine,
In the exhaust gas flow rate reduction step, by temporarily controlling the electronic throttle device to the throttle side, the flow rate of the exhaust gas is forcibly reduced temporarily.
A method for controlling an internal combustion engine. A control method for an internal combustion engine according to claim 1,
The internal combustion engine is provided with an injector for injecting fuel to be supplied to the internal combustion engine,
In the exhaust gas flow rate reduction step, by temporarily reducing the amount of fuel injected from the injector, the flow rate of the exhaust gas is forcibly reduced temporarily,
A method for controlling an internal combustion engine. A control device for an internal combustion engine that controls a variable nozzle capable of adjusting a flow rate of exhaust gas to a turbine of a turbocharger,
A depression amount prediction means for detecting an acceleration request from the driver and predicting an accelerator pedal depression amount;
Exhaust gas flow rate predicting means for predicting the exhaust gas flow rate from the internal combustion engine based on the predicted accelerator pedal depression amount and the operating state of the internal combustion engine;
Target opening degree predicting means for predicting a variable nozzle target opening degree based on the predicted exhaust gas flow rate and the operating state of the internal combustion engine;
Based on the variable nozzle response time, the current opening of the variable nozzle, and the variable nozzle target opening previously stored in the storage means, the actual opening of the variable nozzle after a predetermined time has elapsed since the present time. An actual opening prediction means for predicting a variable nozzle actual opening that is a degree;
Exhaust gas flow rate that forcibly decreases the flow rate of exhaust gas from the internal combustion engine when it is determined that the follow-up of the predicted actual variable nozzle opening is delayed with respect to the predicted variable nozzle target opening A reduction means,
Control device for internal combustion engine.

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