JP4517951B2 - Control device for internal combustion engine - Google Patents

Description

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

  In an internal combustion engine equipped with a turbocharger, there is a case where sufficient acceleration cannot be performed due to a delay in supercharging in the early stage of acceleration from a low speed. Various techniques have been proposed in order to improve such supercharging delay.

  Patent Document 1 describes a technique for reducing the amount of overlap between intake and exhaust valves in order to prevent the supercharging pressure from being lower than the back pressure and reducing the intake charging efficiency during acceleration. In Patent Document 2, the intake air pressure and the exhaust gas pressure are detected by a sensor, and the intake flow effect from the intake side to the exhaust side is used by increasing the overlap amount when the intake pressure is larger than the exhaust pressure. The technology is described.

  Incidentally, it is known that in the early stage of acceleration, a so-called “blowback” in which exhaust gas flows backward to the intake side may occur. Patent Document 3 describes a technique for detecting such blow-back by providing a flow velocity sensor at an intake port.

JP 10-31801 A JP 2003-120361 A JP 2003-83126 A

  However, the techniques described in Patent Documents 1 to 3 described above cannot sufficiently improve the supercharging delay.

  The present invention has been made to solve such problems. The object of the present invention is to control from the intake side to the exhaust side by performing control such that the supercharging pressure is higher than the back pressure. Another object of the present invention is to provide a control device for an internal combustion engine that can appropriately suppress the supercharging delay by promoting the gas flow.

  In one aspect of the present invention, an internal combustion engine controller includes: a turbocharger configured to be capable of adjusting a supercharging pressure by a vane; and a vane opening degree control unit that controls a vane opening degree of the vane. The vane opening degree control means includes a boost pressure higher than a back pressure when accelerating and when an overlap amount between an intake valve and an exhaust valve provided in a cylinder is a predetermined amount or more. Thus, the vane opening degree is controlled.

  The control device for an internal combustion engine includes a turbocharger configured to be capable of adjusting a supercharging pressure by a vane, and a vane opening degree control unit that controls the vane opening degree of the vane. Specifically, the vane opening degree control means is at the time of acceleration (for example, when the vehicle is in an acceleration transient state), and the amount of overlap between the intake valve and the exhaust valve provided in the cylinder is a predetermined amount or more. At a certain time, the vane opening degree is controlled so that the supercharging pressure becomes higher than the back pressure. For example, the vane opening degree control means performs control so that the intake port pressure becomes higher than the exhaust port pressure. By making the supercharging pressure higher than the back pressure, gas flows from the intake side to the exhaust side. Thereby, the gas flow from the intake side to the exhaust side can be promoted. Therefore, according to the control device for an internal combustion engine, intake air can be effectively taken into the internal combustion engine, and exhaust gas can be discharged immediately, thereby reducing a supercharging delay during an acceleration transient. It becomes possible.

  In one aspect of the control apparatus for an internal combustion engine, the vane opening degree control means starts controlling the vane opening degree from a state where the vane opening degree is set based on the operating state of the internal combustion engine.

  In this aspect, the vane opening degree control means sets the vane opening degree based on the operating state of the internal combustion engine, and starts control of the vane opening degree from this state. That is, the vane opening degree control means sets the vane opening degree suitable for the operating state when starting the control of the vane opening degree. This is because the appropriate vane opening at which the internal combustion engine should be set changes in accordance with the rotational speed and load of the internal combustion engine. Therefore, according to the control device for an internal combustion engine, the vane opening degree can be appropriately controlled so that the supercharging pressure becomes higher than the back pressure without being affected by the operating state of the internal combustion engine.

  In another aspect of the control device for an internal combustion engine, the vane opening degree control unit includes an overlap amount control unit that reduces the overlap amount when the vane opening degree reaches an upper limit on the opening side. Controls the vane opening degree to the closing side when the vane opening degree reaches the upper limit on the opening side.

  In this aspect, when the vane opening reaches the upper limit on the open side, the overlap amount control means performs control to reduce the overlap amount, and the vane opening control means controls the vane opening to the close side. To do. This is because when the vane opening reaches the upper limit on the opening side, the boost pressure rises slowly, and the boost pressure may not immediately become higher than the back pressure. That is, in such a case, it is better to close the vane opening and introduce a high-density intake rather than opening the vane opening and introducing a low-density intake. Can be introduced. Therefore, the control device for the internal combustion engine performs control to close the vane opening instead of opening the vane opening when the vane opening reaches the upper limit on the opening side. Thereby, it is possible to appropriately improve the supercharging delay at the time of acceleration transition.

  Preferably, a first relationship in which a magnitude relation between the supercharging pressure and the back pressure is estimated based on a value detected by at least one of a pressure sensor, a temperature sensor, and an oxygen sensor provided in the intake port. Estimating means is provided, and the vane opening degree controlling means controls the vane opening degree based on the magnitude relationship estimated by the first estimating means.

  Specifically, the first estimation means is configured to determine a magnitude relationship between the supercharging pressure and the back pressure based on a value detected by at least one of a pressure sensor, a temperature sensor, and an oxygen sensor provided in the intake port. Guess. When gas is blown back from the exhaust side to the intake side, the pressure or temperature increases or the oxygen concentration decreases at the intake port. Accordingly, by measuring any of the pressure change, temperature change, and oxygen concentration change of the intake port, it is possible to estimate the presence or absence of blowback, that is, the magnitude relationship between the supercharging pressure and the back pressure. . On the other hand, the vane opening degree control means controls the vane opening degree based on the magnitude relationship estimated by the first estimation means. Specifically, the vane opening degree control means controls the vane opening degree so that the supercharging pressure becomes higher than the back pressure when it is estimated that the supercharging pressure is lower than the back pressure.

  More preferably, it comprises second estimating means for calculating the volumetric efficiency of intake air and estimating the magnitude relationship between the supercharging pressure and the back pressure based on the volumetric efficiency, wherein the vane opening degree controlling means is The vane opening degree is controlled based on the magnitude relationship estimated by the second estimation means.

  Specifically, the second estimation means calculates the volumetric efficiency of the intake air, and estimates the magnitude relationship between the supercharging pressure and the back pressure based on the calculated volumetric efficiency. When gas is blown back from the exhaust side to the intake side, the gas flows backward from the exhaust side to the intake side, so that the volumetric efficiency decreases. Therefore, the presence or absence of blow-back can be estimated based on the change in volumetric efficiency, that is, the magnitude relationship between the supercharging pressure and the back pressure can be estimated. On the other hand, the vane opening degree control means controls the vane opening degree based on the magnitude relationship estimated by the second estimation means. Specifically, the vane opening degree control means controls the vane opening degree so that the supercharging pressure becomes higher than the back pressure when it is estimated that the supercharging pressure is lower than the back pressure.

  Preferred embodiments of the present invention will be described below with reference to the drawings.

[First Embodiment]
First, a first embodiment of the present invention will be described.

(Vehicle configuration)
FIG. 1 is a schematic diagram illustrating an overall configuration of a vehicle to which the control device for an internal combustion engine according to the first embodiment is applied. In FIG. 1, a solid line arrow indicates the flow of gas or the like, and a broken line arrow indicates signal input / output.

  The vehicle mainly includes an air cleaner 1, an air flow meter 2, an intake passage 3, a turbocharger 4, an intercooler 5, a throttle valve 6, a surge tank 7, an intake port 8, and an internal combustion engine 9. An exhaust port 10, exhaust passages 11a and 11b, an intake port pressure sensor 12, an exhaust port pressure sensor 13, a variable valve controller 14, a variable nozzle 15, an ECU (Engine Control Unit) 20, Is provided. The exhaust port pressure sensor 13 is provided for each exhaust port 10 corresponding to the exhaust passages 11a and 11b, but is omitted in FIG. 1 for convenience of explanation.

  The air cleaner 1 purifies air (intake air) acquired from the outside and supplies it to the intake passage 3. The air flow meter 2 detects the flow rate of the intake air passing through the intake passage 3. A compressor 4a of the turbocharger 4 is disposed in the intake passage 3, and the intake air is compressed (supercharged) by the rotation of the compressor 4a. In the intake passage 3, an intercooler 5 that cools intake air and a throttle valve 6 that adjusts the amount of intake air supplied to the internal combustion engine 9 are provided.

  The intake air that has passed through the throttle valve 6 is temporarily stored in the surge tank 7 and then flows into the cylinder 9a of the internal combustion engine 9. The internal combustion engine 9 is an in-line four-cylinder engine having four cylinders 9a. The internal combustion engine 9 can be configured as a gasoline engine, a diesel engine, or the like.

  Each cylinder 9a is provided with an intake valve (not shown) for introducing intake air into the cylinder 9a and an exhaust valve (not shown) for discharging the gas (exhaust gas) in the cylinder 9a. . The intake valve and the exhaust valve are each connected to a camshaft (not shown), and the camshaft is connected to the variable valve controller 14. The variable valve control unit 14 opens and closes the intake valve and the exhaust valve via a camshaft (not shown). The variable valve control unit 14 is a device that can variably control the valve opening / closing timing (valve timing), and is controlled by a control signal S4 supplied from the ECU 20. For example, the variable valve control unit 14 can adjust a period during which the intake valve and the exhaust valve are simultaneously open (overlap amount). When the overlap amount is large, a gas flow occurs in a direction corresponding to the pressure difference between the intake side and the exhaust side.

  The intake port 8 is provided with an intake port pressure sensor 12 that detects the pressure in the intake port 8 (hereinafter also referred to as “intake port pressure”). The intake port pressure detected by the intake port pressure sensor 12 is output to the ECU 20 as a detection signal S12. Further, the exhaust port 10 is provided with an exhaust port pressure sensor 13 for detecting the pressure in the exhaust port 10 (hereinafter also referred to as “exhaust port pressure”). The exhaust port pressure detected by the exhaust port pressure sensor 13 is output to the ECU 20 as a detection signal S3. The intake port pressure corresponds to the supercharging pressure, and the exhaust port pressure corresponds to the back pressure.

  Exhaust gas generated by combustion in the internal combustion engine 9 is discharged to the exhaust passages 11a and 11b. Specifically, assuming that the first cylinder, the second cylinder, the third cylinder, and the fourth cylinder are in order from the right in FIG. 1, the exhaust passage 11a is connected to the first cylinder and the fourth cylinder, and the exhaust passage 11b is the second cylinder. The cylinder and the third cylinder are connected. By configuring the exhaust passages 11a and 11b in this manner, blowdown (referred to as discharge of high-pressure gas at the initial stage of the exhaust stroke) between the first and fourth cylinders and the second and third cylinders. )) And the like do not affect each other. That is, at the end of the exhaust stroke, there is no problem that exhaust gas in the cylinder connected to the other exhaust passage is not discharged due to blowdown of the cylinder connected to the other exhaust passage.

  Further, the exhaust passage 11a and the exhaust passage 11b are connected to the turbocharger 4, respectively. Thereby, the exhaust gas that has passed through the exhaust passages 11 a and 11 b rotates the turbine 4 b in the turbocharger 4. The rotational torque of the turbine 4b is transmitted to the compressor wheel in the supercharger 4 and the compressor 4a rotates, so that the intake air passing through the turbocharger 4 is compressed. Thus, the turbocharger 4 is configured as a twin entry type.

  The turbocharger 4 is provided with a variable nozzle 15. The variable nozzle 15 is constituted by a vane and can throttle exhaust gas supplied to the turbocharger. Thereby, the flow volume (flow velocity) of the exhaust gas supplied to the turbocharger 4 is adjusted, and the supercharging pressure can be changed. Specifically, when the variable nozzle 15 is closed, the exhaust gas is throttled, so that the supercharging pressure tends to increase. On the contrary, when the variable nozzle 15 is opened, the throttle to exhaust gas is loosened, so that the supercharging pressure tends to decrease. The opening of the variable nozzle 15 is controlled by a control signal S5 supplied from the ECU 20. The variable nozzle 15 is configured to be able to adjust the amounts of the exhaust gas supplied from the exhaust passage 11a and the exhaust gas supplied from the exhaust passage 11b.

  The ECU 20 includes a CPU, a ROM, a RAM, an A / D converter, an input / output interface, and the like (not shown). The ECU 20 performs in-vehicle control based on outputs supplied from the various sensors described above. Specifically, the ECU 20 controls the opening degree (vane opening degree) of the variable nozzle 15 and the overlap amount based on the intake port pressure and the exhaust port pressure. That is, the ECU 20 functions as a vane opening degree control unit and an overlap amount control unit.

(Control method of variable nozzle)
Next, the control method of the variable nozzle 15 according to the first embodiment will be specifically described.

(1) 1st example First, the control method of the variable nozzle 15 which concerns on the 1st example of 1st Embodiment is demonstrated.

  In the first example, the opening degree of the variable nozzle 15 is controlled so that the intake port pressure becomes higher than the exhaust port pressure when the vehicle is in an acceleration transient state and the overlap amount is sufficient. Such control is performed by setting the intake port pressure to be higher than the exhaust port pressure, thereby promoting the gas flow from the intake side to the exhaust side, thereby increasing the excess during acceleration acceleration (initial stage of acceleration). This is to improve pay delay.

  FIG. 2 is a flowchart showing variable nozzle control processing according to the first example. This process is repeatedly executed by the ECU 20 at a predetermined cycle.

  First, in step S101, the ECU 20 determines whether or not the driving state of the vehicle is an acceleration transient state. In this case, the ECU 20 determines whether or not there is a request for acceleration based on the accelerator opening, the fuel injection amount, and the like. Specifically, the ECU 20 determines whether or not the supercharging pressure condition has reached the required output. If it is an acceleration transient state (step S101; Yes), the process proceeds to step S102. If it is not an acceleration transient state (step S101; No), the process exits the flow.

  In step S102, the ECU 20 determines whether or not the overlap amount is sufficient. Specifically, the ECU 20 obtains the crank angle and the like to determine the current overlap amount, and corresponds to the reference overlap amount (corresponding to a “predetermined amount” used when determining the overlap amount) and the current overlap amount. Judgment is made by comparing the lap amount. The reference overlap amount is determined using a map defined by the operating state of the internal combustion engine 9. According to this map, when the rotational speed of the internal combustion engine is large and the load is small, a large reference overlap amount is determined. Conversely, when the rotational speed of the internal combustion engine is small and the load is large, a small reference overlap amount is determined.

  If the current overlap amount is greater than or equal to the reference overlap amount, that is, if the overlap amount is sufficient (step S102; Yes), the process proceeds to step S104. In this case, a gas flow between the intake side and the exhaust side tends to occur. On the other hand, when the current overlap amount is less than the reference overlap amount, that is, when the overlap amount is not sufficient (step S102; No), the process proceeds to step S103. In this case, a gas flow between the intake side and the exhaust side hardly occurs.

  In step S103, the ECU 20 executes normal variable nozzle control. Specifically, the ECU 20 executes control to close the variable nozzle 15 so that the current supercharging pressure becomes the target supercharging pressure. When the above process ends, the process exits the flow.

  In step S104, the ECU 20 largely closes the variable nozzle 15. In order to execute control for gradually opening the variable nozzle 15 in the subsequent processing, the variable nozzle 15 is first largely closed. When this process ends, the process proceeds to step S105.

  In step S105, the ECU 20 determines whether or not the intake port pressure is greater than the exhaust port pressure. If the intake port pressure is greater than the exhaust port pressure (step S105; Yes), the process proceeds to step S107. In this case, even if the variable nozzle 15 is not changed, a gas flow from the intake side to the exhaust side occurs with the current opening set. On the other hand, when the intake port pressure is equal to or lower than the exhaust port pressure (step S105; No), the process proceeds to step S106. In this case, no gas flows from the intake side to the exhaust side. Therefore, in step S106, the ECU 20 opens the variable nozzle 15 in order to make the intake port pressure larger than the exhaust port pressure. Specifically, the ECU 20 opens the variable nozzle 15 by a predetermined amount. Then, the process proceeds to step S107.

  In step S107, the ECU 20 determines whether or not to continue the control of the variable nozzle 15. In the normal variable nozzle control, it is determined whether or not the control of the variable nozzle 15 is continued. In step S107, the same determination as that performed in the normal variable nozzle control is performed. For example, it is determined whether or not the current boost pressure has reached the target boost pressure. When the control is continued (step S107; Yes), the process returns to step S105 and the determination is performed again. On the other hand, when the control is not continued (step S107; No), the process exits the flow.

  By executing the above processing, the intake port pressure can be set higher than the exhaust port pressure, and the flow of gas from the intake side to the exhaust side can be promoted. As a result, intake air can be effectively taken into the internal combustion engine 9 and exhaust gas can be discharged immediately, so that it is possible to reduce the delay in supercharging during acceleration transients.

(2) Second Example Next, a control method for the variable nozzle 15 according to a second example of the first embodiment will be described.

  The second example is different from the first example described above in that the opening degree of the variable nozzle 15 is controlled based on the differential pressure between the intake port pressure and the exhaust port pressure.

  FIG. 3 is a flowchart showing variable nozzle control processing according to the second example. This process is also repeatedly executed by the ECU 20 at a predetermined cycle.

  Since the processes of steps S201 to S205 and the process of step S207 are the same as the processes of steps S101 to S105 and the process of step S107 according to the first example described above, description of these processes will be omitted. In the variable nozzle control process according to the second example, the process of step S206 is performed instead of step S106 according to the first example. Therefore, here, the process of step S206 will be described.

  In step S206, the ECU 20 opens the variable nozzle 15 based on the differential pressure between the intake port pressure and the exhaust port pressure. Specifically, the ECU 20 opens the opening (hereinafter referred to as “the current opening”) of the variable nozzle 15 based on the pressure difference between the intake port pressure and the exhaust port pressure (hereinafter referred to as “the current opening”). Hereinafter, this opening degree is referred to as “opening opening degree”).

  For example, the ECU 20 determines the opening degree using a map as shown in FIG. In FIG. 4, the horizontal axis indicates the differential pressure (indicated by an absolute value) between the intake port pressure and the exhaust port pressure, and the vertical axis indicates the opening degree. According to this map, the larger the differential pressure between the intake port pressure and the exhaust port pressure, the larger the opening degree is determined as the opening degree. The smaller the differential pressure, the smaller the opening degree is determined. The ECU 20 sets an opening degree obtained by adding the opening degree thus determined to the current opening degree of the variable nozzle 15 for the variable nozzle 15. When the above process ends, the process proceeds to step S207, and it is determined whether or not the control for opening the variable nozzle 15 is continued.

  By executing the above processing, when the exhaust port pressure is considerably higher than the intake port pressure, the variable nozzle 15 can be opened greatly, so that the intake port pressure is immediately set to be higher than the exhaust port pressure. It becomes possible to do. This makes it possible to immediately improve the supercharging delay at the time of transition.

(3) Third Example Next, a control method for the variable nozzle 15 according to a third example of the first embodiment will be described.

  In the third example, the opening degree (hereinafter, this opening degree is referred to as “basic opening degree”) set before starting the control for opening the variable nozzle 15 is changed in accordance with the state of the internal combustion engine 9. Therefore, it differs from the first example and the second example described above. The reason why the basic opening is changed in this way is that the optimum basic opening changes in accordance with the state of the internal combustion engine 9.

  FIG. 5 is a flowchart showing variable nozzle control processing according to the third example. This process is also repeatedly executed by the ECU 20 at a predetermined cycle.

  Since the processes of steps S301 to S303 and the processes of steps S305 to S307 are the same as the processes of steps S101 to S103 and the processes of steps S105 to S107 according to the first example, description of these processes is omitted. . In the variable nozzle control process according to the third example, the process of step S304 is performed instead of step S104 according to the first example. Therefore, here, the process of step S304 will be described.

  In step S <b> 304, the ECU 20 closes the variable nozzle 15 based on the operating state of the internal combustion engine 9. In this case, the ECU 20 changes the basic opening used when closing the variable nozzle 15 according to the operating state of the internal combustion engine 9. The ECU 20 changes the basic opening using an opening determined based on a differential pressure between the intake port pressure and the exhaust port pressure (hereinafter, this opening is referred to as a “change opening”). The variable nozzle 15 is set at the opening degree. That is, the ECU 20 sets the variable nozzle 15 to an opening obtained by adding the change opening to the basic opening. Note that the change opening corresponds to a value obtained by adding the opening degree described above in the process of repeating the process. When the above process ends, the process proceeds to step S305, and it is determined whether or not the intake port pressure is higher than the exhaust port pressure.

  Here, a specific example of a method for determining the basic opening will be described with reference to FIG. FIG. 6 shows a map used when determining the basic opening. In FIG. 6, the horizontal axis indicates the rotational speed of the internal combustion engine 9, and the vertical axis indicates the load (determined by the injection amount or the like) of the internal combustion engine 9. According to this map, when the rotational speed is high and the load is large, the basic opening is set as the opening on the closing side, and when the rotational speed is low and the load is small, the opening on the opening side is set. Is set to the basic opening.

  The process for setting the basic opening described above is executed every time the process (steps S305 to S307) for making the intake port pressure higher than the exhaust port pressure is performed. Specifically, when it is determined in step S307 that control of the variable nozzle 15 is to be continued (step S307; Yes), the process returns to step S304, and the process of step S304 is performed again.

  As described above, according to the variable nozzle control process according to the third example, the process of setting the basic opening according to the operation state of the internal combustion engine 9 is repeatedly executed, and therefore the operation state of the internal combustion engine 9 is affected. Therefore, it is possible to appropriately control the variable nozzle 15 to open. Thereby, it becomes possible to appropriately reduce the supercharging delay at the time of transition.

  In addition, it is not limited to updating (clearing) the change opening every time the process of step S304 is performed, the change opening determined after the process of steps S304 to S307 is stored, and the stored change is stored. The opening degree may be used as an initial value in the next process of step S304. That is, the change opening degree may be learned. This also makes it possible to quickly improve the supercharging delay.

  Also in the process of step S306 according to the third example, the opening degree determined based on the differential pressure between the intake port pressure and the exhaust port pressure is the same as the process of step S206 shown in the second example. You may perform control which opens the variable nozzle 15 using.

(4) Fourth Example Next, a method for controlling the variable nozzle 15 according to a fourth example of the first embodiment will be described.

  In the fourth example, control is performed in consideration of whether or not the opening degree of the variable nozzle 15 has reached the upper limit on the opening side (hereinafter referred to as “limit opening degree”). Different from the first example to the third example. Specifically, when the opening degree of the variable nozzle 15 reaches the limit opening degree, the overlap amount is reduced and the variable nozzle 15 is closed. This is because when the variable nozzle 15 is opened to the limit opening, the intake port pressure rises slowly, and the intake port pressure may not immediately become higher than the exhaust port pressure. In such a case, rather than opening the variable nozzle 15 and introducing low-density intake air, closing the variable nozzle 15 and introducing high-density air intake introduces a larger amount of intake air as a whole. be able to.

  FIG. 7 is a flowchart showing variable nozzle control processing according to the fourth example. This process is also repeatedly executed by the ECU 20 at a predetermined cycle.

  The processes of steps S401, S402, S403, S404, S406, S407, and S409 are the same as the processes of S101, S102, S104, S105, S106, S107, and S103 according to the first example described above, respectively. Explanation of these processes is omitted. Here, the process of step S405 performed before the process of opening the variable nozzle 15 (step S406) and the process of step S408 performed after the process of S405 will be described.

  In step S405, the ECU 20 determines whether or not the variable nozzle 15 may be opened. In this case, the ECU 20 determines whether or not the current opening of the variable nozzle 15 exceeds the limit opening. For example, the ECU 20 determines the limit opening degree using a map defined by the operating state of the internal combustion engine 9.

  FIG. 8 shows an example of a map used when determining the limit opening. FIG. 8 shows the rotational speed of the internal combustion engine 9 on the horizontal axis and the limit opening on the vertical axis. According to this map, a smaller limit opening is determined as the rotation speed is higher, and conversely, a larger limit opening is determined as the rotation speed is lower.

  Returning to FIG. 7, the processing in step S405 will be described. When the opening degree of the variable nozzle 15 exceeds the limit opening degree (step S405; No), the process proceeds to step S408. In this case, even if the variable nozzle 15 is further opened, the intake port pressure rises slowly and the intake port pressure may not be higher than the exhaust port pressure. Therefore, it is not preferable to open the variable nozzle 15 any more. On the other hand, when the opening degree of the variable nozzle 15 does not exceed the limit opening degree (step S405; Yes), the process proceeds to step S406. In this case, there is no problem even if the variable nozzle 15 is opened. In other words, if the variable nozzle 15 is opened, the intake port pressure can be increased. Therefore, in step S406, the variable nozzle 15 is opened.

  In step S408, the ECU 20 performs a process of reducing the overlap amount. Specifically, the ECU 20 controls the variable valve controller 14 to reduce the overlap amount. And a process progresses to step S409 and ECU20 performs normal variable nozzle control. That is, the ECU 20 executes control for closing the variable nozzle 15 from the limit opening. Thereby, compared with the case where control which opens the variable nozzle 15 is continued, an intake port pressure can be raised early. This is because low-density intake air is introduced when the control to open the variable nozzle 15 is continued, but high-density intake air is introduced when the variable nozzle 15 is closed. This is because the intake air of the mass is introduced.

  By executing the above processing, it is possible to prevent the control to open the variable nozzle 15 unnecessarily, and to appropriately improve the supercharging delay at the time of transition.

  In the process of step S403 according to the fourth example, similarly to the process of step S304 shown in the third example, the variable nozzle 15 is set using the basic opening determined from the driving state of the vehicle. You may perform the close process. Further, in the process of step S406, similarly to the process of step S206 shown in the second example described above, it is variable using the opening degree determined based on the differential pressure between the intake port pressure and the exhaust port pressure. The nozzle 15 may be opened.

(5) Fifth Example Next, a control method for the variable nozzle 15 according to a fifth example of the first embodiment will be described.

  In the fifth example, when the intake port pressure is higher than the exhaust port pressure, if the intake port pressure can be maintained higher than the exhaust port pressure even if the variable nozzle 15 is closed, the variable nozzle 15 is closed. Is different from the first to fourth examples described above. In a situation where the intake port pressure can be maintained higher than the exhaust port pressure even when the variable nozzle 15 is closed, the control for increasing the supercharging pressure (internal pressure of the intake passage 3) by closing the variable nozzle 15 is performed. However, the intake port pressure does not become lower than the exhaust port pressure. Therefore, in the fifth example, in such a situation, the boost pressure is increased by performing the control to close the variable nozzle 15 instead of performing the control to open the variable nozzle 15.

  FIG. 9 is a flowchart illustrating variable nozzle control processing according to the fifth example. This process is also repeatedly executed by the ECU 20 at a predetermined cycle.

  Since the processing of steps S501 to S507 is the same as the processing of steps S101 to S107 according to the first example described above, the description thereof is omitted. In the fifth example, when the intake port pressure is higher than the exhaust port pressure (step S505; Yes), instead of determining whether or not to continue the control of the variable nozzle 15, the processing of step S508 and step 509 is performed. I do. Therefore, here, the processing of step S508 and step 509 will be described.

  In step S508, the ECU 20 determines whether or not the variable nozzle 15 may be closed. Specifically, the ECU 20 determines that the variable nozzle 15 may be closed when any of the following (a) to (c) is satisfied.

(A) When the processes of steps S505 to S509 are repeatedly executed, the process of opening the variable nozzle 15 of step S506 has never been performed. (B) The intake port pressure is considerably higher than the exhaust port pressure. (C) When the intake port pressure is lower than the predetermined pressure In the case of the above (a) and (b), even if the variable nozzle 15 is closed, the intake port pressure does not become lower than the exhaust port pressure. The relationship between the intake port pressure and the exhaust port pressure does not reverse. On the other hand, the case corresponding to (c) corresponds to the case where the variable nozzle 15 is not sufficiently closed in step S504. For example, such a situation occurs when the variable nozzle 15 is not closed to a desired opening degree due to secular change or hiss. Even in the case of (c), even if the variable nozzle 15 is closed, the intake port pressure does not become lower than the exhaust port pressure.

  If it is determined that the variable nozzle 15 may be closed (step S508; Yes), the process proceeds to step S509. In step S509, the ECU 20 performs a process of closing the variable nozzle 15. On the other hand, if it is not determined that the variable nozzle 15 may be closed (step S508; Yes), the process proceeds to step S507. In this case, it is determined whether or not to continue control of the variable nozzle 15 in step S509 without changing the opening of the variable nozzle 15.

  As described above, in the variable nozzle control process according to the fifth example, even when the variable nozzle 15 is closed, the intake port pressure can be maintained higher than the exhaust port pressure (any of the above (a) to (c)). When the above condition is satisfied), the variable nozzle 15 is controlled to be closed instead of opening the variable nozzle 15. Thereby, since the supercharging pressure can be effectively increased, it becomes possible to improve the supercharging delay at the time of acceleration transient.

  In the process of step S504 according to the fifth example, similarly to the process of step S304 shown in the third example, the variable nozzle 15 is set using the basic opening determined from the driving state of the vehicle. You may perform the close process. Further, in the process of step S506, as with the process of step S206 shown in the second example described above, it is variable using the opening degree determined based on the differential pressure between the intake port pressure and the exhaust port pressure. The nozzle 15 may be opened.

  Further, during the processing of step S505 and step S506, it is determined whether or not the opening of the variable nozzle 15 exceeds the limit opening, similarly to the processing of step S405 shown in the fourth example described above. May be. Furthermore, when the opening degree of the variable nozzle 15 exceeds the limit opening degree, it is also possible to perform a process of reducing the overlap amount, similar to the process of step S408 shown in the fourth example described above. .

(6) Sixth Example Next, a control method for the variable nozzle 15 according to a sixth example of the first embodiment will be described.

  The sixth example also performs the process of closing the variable nozzle 15 when it is determined that the intake port pressure can be maintained higher than the exhaust port pressure even when the variable nozzle 15 is closed. Similar to the example. However, the sixth example differs from the fifth example in that control is performed to close the variable nozzle 15 based on the differential pressure between the intake port pressure and the exhaust port pressure. By performing control to close the variable nozzle 15 based on the differential pressure, the variable nozzle 15 can be largely closed when the differential pressure is large, and the opening degree of the variable nozzle 15 is immediately set to the target opening degree. be able to. Conversely, when the differential pressure is small, it is possible to prevent the variable nozzle 15 from being closed unnecessarily large and to close it with an appropriate opening degree. Therefore, according to the control method for the variable nozzle 15 according to the sixth example, the opening degree of the variable nozzle 15 can be appropriately set to the target opening degree.

  FIG. 10 is a flowchart showing variable nozzle control processing according to the sixth example. This process is also repeatedly executed by the ECU 20 at a predetermined cycle.

  Since the processing of steps S601 to S608 is the same as the processing of steps S501 to S508 according to the fifth example described above, the description thereof is omitted. In the sixth example, the process of step S609 is performed instead of step S509 of the fifth example. Therefore, here, the process of step S609 will be described.

  In step S609, the ECU 20 closes the variable nozzle 15 based on the differential pressure between the intake port pressure and the exhaust port pressure. Specifically, the ECU 20 closes the current opening of the variable nozzle 15 (the current opening) based on the differential pressure between the intake port pressure and the exhaust port pressure (hereinafter referred to as the opening). Called "closed opening").

  For example, the ECU 20 determines the closing opening degree using a map as shown in FIG. In FIG. 11, the horizontal axis indicates a differential pressure (indicated by an absolute value) between the intake port pressure and the exhaust port pressure, and the vertical axis indicates the closed opening. According to this map, as the differential pressure between the intake port pressure and the exhaust port pressure is larger, a larger opening is determined as the closing opening, and as the differential pressure is smaller, a smaller opening is determined as the closing opening. That is, the larger the differential pressure, the larger the variable nozzle 15 is closed. The smaller the differential pressure, the smaller the variable nozzle 15 is closed. The ECU 20 sets the variable nozzle 15 to an opening obtained by subtracting the closing opening thus determined from the current opening of the variable nozzle 15. When the above processing ends, the processing proceeds to step S607, and it is determined whether or not to continue control of the variable nozzle 15.

  Thus, according to the variable nozzle control processing according to the sixth example, when it is determined that the intake port pressure can be maintained higher than the exhaust port pressure even when the variable nozzle 15 is closed, the target opening degree is reached. The variable nozzle 15 can be closed immediately. Thereby, since the supercharging pressure can be effectively improved, it becomes possible to improve the supercharging delay at the time of acceleration transition.

  In the process of step S604 according to the sixth example, similarly to the process of step S304 shown in the third example, the variable nozzle 15 is set using the basic opening determined from the driving state of the vehicle. You may perform the close process. Further, in the process of step S606, as with the process of step S206 shown in the second example described above, the opening degree determined based on the differential pressure between the intake port pressure and the exhaust port pressure is variable. The nozzle 15 may be opened.

  Further, during the processing of step S605 and step S606, it is determined whether or not the opening of the variable nozzle 15 exceeds the limit opening, similarly to the processing of step S405 shown in the fourth example described above. May be. Furthermore, when the opening degree of the variable nozzle 15 exceeds the limit opening degree, it is also possible to perform a process of reducing the overlap amount, similar to the process of step S408 shown in the fourth example described above. .

[Second Embodiment]
Next, a second embodiment of the present invention will be described.

(Vehicle configuration)
FIG. 12 is a schematic diagram illustrating an overall configuration of a vehicle to which the control device for an internal combustion engine according to the second embodiment is applied. In FIG. 12, a solid line arrow indicates the flow of gas or the like, and a broken line arrow indicates signal input / output.

  The vehicle according to the second embodiment includes an in-cylinder pressure sensor 16, an exhaust temperature sensor 17, an intake air temperature sensor 18, an intake port temperature sensor 25, and an oxygen concentration sensor 26, and includes an ECU 21 instead of the ECU 20. Thus, it is different from the vehicle according to the first embodiment described above. Further, the vehicle according to the second embodiment does not have the exhaust port pressure sensor 13. The same components as those of the vehicle according to the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  Although the in-cylinder pressure sensor 16 is provided for each of the plurality of cylinders 9a, it is omitted in FIG. 12 for convenience of explanation. The exhaust temperature sensor 17 is also provided in each of the exhaust passages 11a and 11b, but is omitted in FIG. 12 for convenience of explanation.

  The in-cylinder pressure sensor 16 detects the internal pressure of the cylinder 9a and outputs the detected pressure to the ECU 21 as a detection signal S6. The exhaust temperature sensor 17 detects the temperature of the exhaust gas, and outputs the detected temperature to the ECU 21 as a detection signal S7. The intake air temperature sensor 18 detects the intake air temperature of the intake manifold, and outputs the detected temperature to the ECU 21 as a detection signal S8.

  The intake port temperature sensor 25 detects the temperature of the intake port 8 and outputs the detected temperature to the ECU 21 as a detection signal S25. The oxygen concentration sensor 26 detects the oxygen concentration in the intake port 8 and outputs the detected oxygen concentration to the ECU 21 as a detection signal S26. Further, the air flow meter 2 detects the flow rate of intake air passing through the intake passage 3 (hereinafter also referred to as “intake air amount”), and outputs the detected intake air amount to the ECU 21 as a detection signal S27.

  ECU21 acquires a detection signal from the various sensors in a vehicle, and controls variable nozzle 15 based on these. Specifically, the ECU 21 estimates the presence / absence of blowback from the exhaust side to the intake side based on the detection signal of at least one of the sensors described above, and controls the opening degree of the variable nozzle 15 based on the estimation result. Do. In other words, the ECU 21 estimates the magnitude relationship between the intake port pressure and the exhaust port pressure, and controls the opening of the variable nozzle 15 based on the estimation result. Thus, ECU21 which concerns on 2nd Embodiment functions as a 1st estimation means and a 2nd estimation means.

(Control method of variable nozzle)
Next, a method for controlling the variable nozzle 15 according to the second embodiment will be described with reference to FIG.

  FIG. 13 is a flowchart showing variable nozzle control processing according to the second embodiment. This process is repeatedly executed by the ECU 21 at a predetermined cycle.

  In the variable nozzle control process according to the second embodiment, instead of comparing the magnitude relationship between the intake port pressure detected by the intake port pressure sensor 12 and the exhaust port pressure detected by the exhaust port pressure sensor 13, the output of other sensors is compared. Is different from the variable nozzle control processing according to the first embodiment described above in that the presence or absence of blowback from the exhaust side to the intake side is estimated, that is, the magnitude relationship between the intake port pressure and the exhaust port pressure is estimated. . Specifically, in the variable nozzle control process according to the second embodiment, the magnitude relationship between the intake port pressure and the exhaust port pressure is estimated without directly detecting the exhaust port pressure.

  Specifically, in the variable nozzle control process according to the second embodiment, the determination in step S905 is performed instead of the determination in steps S105 and S205 described above. The processing in steps S901 to S904 is the same as the processing in steps S101 to S104, and the processing in steps S906 to S907 is the same as the processing in steps S106 to S107. Therefore, these descriptions are omitted, and here the processing in step S905 is performed. Only will be described.

  In step S905, the ECU 21 determines whether or not gas is blown back from the exhaust side to the intake side. Specifically, the ECU 21 determines the presence or absence of blow-back by estimating the magnitude relationship between the intake port pressure and the exhaust port pressure based on a detection signal from a sensor in the vehicle. When it is estimated that the intake port pressure is higher than the exhaust port pressure, that is, when it is estimated that no blowback has occurred (step S905; Yes), the process proceeds to step S907. In step S907, it is determined whether or not the control of the variable nozzle 15 is to be continued. On the other hand, when it is estimated that the intake port pressure is lower than the exhaust port pressure, that is, when it is estimated that blowback has occurred (step S905; No), the process proceeds to step S906. In step S906, the ECU 21 performs control to open the variable nozzle 15.

  As described above, in the second embodiment, the variable nozzle 15 is controlled by estimating the blow-back without using the exhaust port pressure sensor. Thereby, since it is not necessary to provide a highly responsive exhaust port pressure sensor, the configuration of the apparatus can be simplified and the cost can be reduced. In addition, it is possible to suppress the occurrence of problems in durability and mountability of the exhaust port pressure sensor.

  In the process of step S904 according to the second embodiment, similarly to the process of step S304 described in the first embodiment, the variable nozzle 15 is set using the basic opening determined from the driving state of the vehicle. You may perform the close process. Further, in the process of step S906, as with the process of step S206 shown in the first embodiment, the opening degree is determined based on the estimated differential pressure between the intake port pressure and the exhaust port pressure. The variable nozzle 15 may be opened using the opening degree.

  Further, during the processing of step S905 and step S906, it is determined whether or not the opening of the variable nozzle 15 exceeds the limit opening, similarly to the processing of step S405 described in the first embodiment. May be. Furthermore, when the opening degree of the variable nozzle 15 exceeds the limit opening degree, it is also possible to perform a process of reducing the overlap amount, similarly to the process of step S408 shown in the first embodiment.

(Guide method)
Next, a specific example of a method for estimating the magnitude relationship between the intake port pressure and the exhaust port pressure will be described.

  Note that the vehicle shown in FIG. 12 is provided with all the sensors used in the estimation method described below, but when only one of the following estimation methods is used, the vehicle It is only necessary to have a sensor used for the estimation method.

(1) First Example First, an estimation method according to a first example of the second embodiment will be described with reference to FIG.

  FIG. 14 is a graph showing changes in intake port pressure, where the horizontal axis indicates the crank angle and the vertical axis indicates the intake port pressure. Specifically, the intake valve is opened at the crank angle t1, and the exhaust valve is closed at the crank angle t2. The crank angle t1 and the crank angle t2 correspond to an overlap period in which both the intake valve and the exhaust valve are open. The intake port pressure is a pressure detected by the intake port pressure sensor 12.

  In FIG. 14, the solid line indicates the intake port pressure change when there is no blowback, and the broken line indicates the intake port pressure change when there is blowback. From this, it can be seen that the intake port pressure rises immediately after the intake valve is opened when there is blowback, compared to when there is no blowback. Such an increase in the intake port pressure is caused by the backflow of gas from the exhaust side to the intake side. Therefore, the ECU 21 can determine the presence or absence of blow-back by measuring the rate of increase of the intake port pressure immediately after opening the intake valve.

(2) Second Example Next, an estimation method according to a second example of the second embodiment will be described.

  Unlike the first example, the second example estimates the presence or absence of blow-back based on the intake port temperature change instead of the intake port pressure change. This intake port temperature is a temperature detected by the intake port temperature sensor 25.

  Also by using the intake port temperature change, the presence or absence of blow-back can be estimated as in the first example described above. Specifically, when there is blowback, the intake port temperature rises immediately after opening the intake valve. Such an increase in the intake port temperature occurs when the combustion gas (exhaust gas) having a relatively high temperature flows backward from the exhaust side to the intake side. As described above, the ECU 21 can determine the presence or absence of blow-back by measuring the rate of increase of the intake port temperature immediately after opening the intake valve.

(3) Third Example Next, an estimation method according to a third example of the second embodiment will be described. The third example is different from the first example and the second example described above in that the presence or absence of blowback is estimated based on the oxygen concentration in the intake port 8.

  FIG. 15 is a graph showing changes in oxygen concentration, with the abscissa indicating the crank angle and the ordinate indicating the oxygen concentration. Specifically, the intake valve is opened at the crank angle t1, and the exhaust valve is closed at the crank angle t2. The crank angle t1 and the crank angle t2 correspond to an overlap period in which both the intake valve and the exhaust valve are open. The oxygen concentration is a pressure detected by the oxygen concentration sensor 26.

  In FIG. 15, the solid line shows the oxygen concentration change when there is no blowback, and the broken line shows the oxygen concentration change when there is blowback. From this, it can be seen that when there is blowback, the oxygen concentration is reduced immediately after the intake valve is opened compared to when there is no blowback. Such a decrease in the oxygen concentration occurs because the gas after combustion flows backward from the exhaust side to the intake side. Therefore, the ECU 21 can determine the presence or absence of blow-back by measuring the rate of decrease in oxygen concentration immediately after opening the intake valve.

(4) Fourth Example Next, an estimation method according to a fourth example of the second embodiment will be described.

  The fourth example differs from the first to third examples described above in that the blowback is estimated based on the intake port pressure and the in-cylinder pressure when the intake valve is opened. The intake port pressure is a pressure detected by the intake port pressure sensor 12, and the in-cylinder pressure is a pressure detected by the in-cylinder pressure sensor 16.

  When the estimation methods according to the first to third examples are used, if a positive pressure wave is transmitted by the intake pulsation at the overlap timing, it is not possible to accurately determine the presence or absence of the blow-back. There is a case. This is because if intake pulsation occurs at the timing of overlap, intake port pressure or intake port temperature may increase. Therefore, in the fourth example, in order to improve the determination accuracy, the presence or absence of blow-back is determined by using not only the intake port pressure but also the in-cylinder pressure. This is because the in-cylinder pressure is hardly affected by the intake pulsation.

  Specifically, the ECU 21 determines that there is a blow-back when the intake port pressure is less than the in-cylinder pressure. As described above, according to the estimation method according to the fourth example, since the intake port pressure and the in-cylinder pressure of the cylinder 9a are used, it is possible to accurately determine the presence or absence of the blow-back without being affected by the intake pulsation. .

(5) Fifth Example Next, an estimation method according to a fifth example of the second embodiment will be described.

  The fifth example differs from the first example to the fourth example in that the presence or absence of blowback is determined using the predicted exhaust port pressure. The reason why the predicted exhaust port pressure is used is that the predicted exhaust port pressure is hardly affected by the intake pulsation.

  Specifically, in the fifth example, the exhaust port pressure is estimated with reference to a map defined by the intake air amount and the exhaust temperature. This map is created by previously obtaining the relationship among the intake air amount, the exhaust temperature, and the exhaust port pressure through experiments or the like. Further, the intake air amount and the exhaust temperature used when referring to the map are acquired from the air flow meter 2 and the exhaust temperature sensor 17, respectively.

  The ECU 21 determines that there is a blow-back when the intake port pressure detected by the intake port pressure sensor 12 is lower than the exhaust port pressure estimated as described above. By performing the determination as described above, it is possible to accurately determine the presence or absence of blow-back without being affected by the intake pulsation. As described above, according to the estimation method according to the fifth example, since the predicted exhaust port pressure is used, it is possible to accurately determine the presence or absence of the blow-back without being affected by the intake pulsation.

(6) Sixth Example Next, an estimation method according to a sixth example of the second embodiment will be described.

  In the sixth example, from the first example to the fifth example, the presence or absence of blowback is determined based on the change in volumetric efficiency (ratio of the volume of air sucked per cycle with respect to the stroke volume). Different from the example. This volumetric efficiency is calculated based on the intake air amount, the intake air temperature, and the intake port pressure. In this case, the intake air amount is detected by the air flow meter 2, the intake air temperature is detected by the intake air temperature sensor 18, and the intake port pressure is detected by the intake port pressure sensor 12.

  Usually, when exhaust pressure rises and blowback occurs, the gas flows backward from the exhaust side to the intake side, so volume efficiency decreases. Therefore, the ECU 21 estimates the presence or absence of blow-back by calculating the rate of decrease in volume efficiency.

  As described above, the estimation method according to the sixth example also uses the volumetric efficiency, so that it is possible to accurately determine the presence or absence of the blow-back without being affected by the intake pulsation. Furthermore, in the sixth example, since the pressure and temperature at the opening timing of the intake valve are not used for the determination, it is necessary to use a sensor with high response compared to the first to fifth examples described above. Absent. Therefore, according to the sixth example, the cost can be reduced.

[Modification]
The present invention is not limited to application to an in-line four-cylinder engine, and can also be applied to a V-type six-cylinder engine. In this case, since the turbocharger and the variable nozzle are provided for each bank, it is not necessary to configure the turbocharger and the exhaust passage in a twin entry type.

  Moreover, this invention is not limited to controlling a supercharging pressure using the variable nozzle 15 comprised with the vane. In another example, a wastegate valve can be used instead of the variable nozzle 15 to perform control such that the supercharging pressure is higher than the back pressure. In this case, the on / off timing of the wastegate valve may be controlled instead of the vane opening.

1 is a schematic diagram illustrating a schematic configuration of a vehicle to which a control device for an internal combustion engine according to a first embodiment of the present invention is applied. It is a flowchart which shows the variable nozzle control process which concerns on the 1st example of 1st Embodiment. It is a flowchart which shows the variable nozzle control process which concerns on the 2nd example of 1st Embodiment. It is a figure which shows the map used in order to determine an opening degree. It is a flowchart which shows the variable nozzle control process which concerns on the 3rd example of 1st Embodiment. It is a figure which shows the map used in order to determine a basic opening. It is a flowchart which shows the variable nozzle control process which concerns on the 4th example of 1st Embodiment. It is a figure which shows the map used in order to determine a limit opening degree. It is a flowchart which shows the variable nozzle control process which concerns on the 5th example of 1st Embodiment. It is a flowchart which shows the variable nozzle control process which concerns on the 6th example of 1st Embodiment. It is a figure which shows the map used in order to determine the closing opening degree. It is a schematic diagram which shows schematic structure of the vehicle to which the control apparatus of the internal combustion engine which concerns on 2nd Embodiment of this invention was applied. It is a flowchart which shows the variable nozzle control process which concerns on 2nd Embodiment. It is a figure for demonstrating the estimation method which concerns on the 1st example of 2nd Embodiment. It is a figure for demonstrating the estimation method which concerns on the 3rd example of 2nd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 2 Air flow meter 3 Intake passage 4 Turbo supercharger 8 Intake port 9 Internal combustion engine 9a Cylinder 10 Exhaust port 11a, 11b Exhaust passage 12 Intake port pressure sensor 13 Exhaust port pressure sensor 14 Variable valve control part 15 Variable nozzle 16 In-cylinder pressure sensor 17 Exhaust temperature sensor 18 Intake temperature sensor 25 Intake port temperature sensor 26 Oxygen concentration sensor 20, 21 ECU

Claims (5)

A turbocharger configured to be able to adjust the supercharging pressure by the vane;
Vane opening control means for controlling the vane opening of the vane, and
The vane opening degree control means is configured so that the supercharging pressure becomes higher than the back pressure at the time of acceleration and when the overlap amount between the intake valve and the exhaust valve provided in the cylinder is a predetermined amount or more. An internal combustion engine control apparatus that controls the vane opening.   2. The control device for an internal combustion engine according to claim 1, wherein the vane opening degree control means starts the control of the vane opening degree from a state where the vane opening degree is set based on an operating state of the internal combustion engine. . When the vane opening reaches the upper limit on the opening side, comprising an overlap amount control means for reducing the overlap amount,
3. The internal combustion engine according to claim 1, wherein the vane opening degree control unit controls the vane opening degree to a closing side when the vane opening degree reaches an upper limit on the opening side. 4. Control device. First estimation means for estimating a magnitude relationship between the supercharging pressure and the back pressure based on a value detected by at least one of a pressure sensor, a temperature sensor, and an oxygen sensor provided in the intake port is provided. ,
4. The internal combustion engine according to claim 1, wherein the vane opening degree control unit controls the vane opening degree based on a magnitude relationship estimated by the first estimation unit. 5. Engine control device. A second estimating means for calculating a volumetric efficiency of the intake air and estimating a magnitude relationship between the supercharging pressure and the backpressure based on the volumetric efficiency;
4. The internal combustion engine according to claim 1, wherein the vane opening degree control unit controls the vane opening degree based on a magnitude relationship estimated by the second estimation unit. 5. Engine control device.

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