JP2013108475A - Operation control method of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve such problems that, in an existing internal combustion engine in which two turbochargers are arranged in series, when the drive torque thereof is required to be boosted, the power boost may be temporarily interrupted.SOLUTION: An operation control method of an internal combustion engine includes: a first turbocharger 23; a second turbocharger 24 arranged upstream of an exhaust path 22 relative to the first turbocharger 23 in series with the first turbocharger and mainly used in a low revolution region of an engine 10; a first on-off valve 36 for opening and closing a first bypass path 35 that bypasses an exhaust turbine 23e of the first turbocharger 23; and a third on-off valve 31 for opening and closing a third bypass path 30 that bypasses an air-intake turbine 24i of the second turbocharger 24. The operation control method closes the first on-off valve 36 to block the first bypass path 35, and then opens the third on-off valve 31 to open the third bypass path 30 when a request for boosting a drive torque relating to the engine 10 is issued.

Description

  The present invention relates to an operation control method for an internal combustion engine comprising a first turbocharger and a second turbocharger arranged in series with respect to the first turbocharger.

  An internal combustion engine in which a plurality of turbochargers are incorporated in order to improve the output of the internal combustion engine is known from Patent Document 1 and Patent Document 2. Both of these are a first turbocharger and a second turbocharger which is arranged in series with the upstream side of the exhaust passage from the first turbocharger and used mainly in the low rotation region of the internal combustion engine. It has a turbocharger. In such a configuration, the first on-off valve for opening and closing the first bypass passage that bypasses the exhaust turbine of the first turbocharger and the exhaust turbine of the second turbocharger are provided. A second opening / closing valve for opening / closing a bypassing second bypass passage is also generally provided.

  In Patent Document 1, when the vehicle is in a high-speed and high-load operation region, the first on-off valve is controlled to be fully closed and the second on-off valve is controlled to be fully open so that the first turbocharger A technique for maximizing the function of a machine is disclosed.

  Further, in Patent Document 2, when the vehicle is in a low rotation and low load operation region and it is desired to raise the exhaust gas temperature, the first on-off valve is controlled to be fully closed and the second on-off valve is controlled. A technique is disclosed in which is controlled to a fully open state.

JP 2009-191667 A JP 2010-203426 A

  In Patent Document 1, since the valve closing operation of the first on-off valve and the valve opening operation of the second on-off valve are controlled simultaneously, the second on-going operation is performed before the first on-off valve is fully closed. There is a possibility that a part of the exhaust gas flows from the second bypass passage to the first bypass passage through the on-off valve. As a result, there is a risk that a so-called breathing phenomenon may occur in which the output of the internal combustion engine temporarily decreases.

  In Patent Document 2, since the first on-off valve is controlled to be fully closed and the second on-off valve is controlled to be fully open despite the vehicle being in the low rotation and low load operation region, Will pass through the intake turbine of the first turbocharger. As a result, negative pressure is generated and the lubricating oil is sucked out from the turbine rotating shaft, resulting in a problem that consumption of the lubricating oil increases. In addition, since exhaust gas is intentionally guided to the exhaust turbine of the first turbocharger having poor supercharging efficiency, there is a problem that fuel efficiency is also deteriorated.

  An object of the present invention is to provide an operation control method for an internal combustion engine that can achieve both an increase in output and suppression of fuel consumption in an internal combustion engine in which a plurality of turbochargers are incorporated.

  An operation control method for an internal combustion engine according to the present invention includes a first turbocharger and a first turbocharger arranged in series upstream of the first turbocharger in the exhaust passage and in a low rotation region of the internal combustion engine. A second turbocharger that is mainly used, a first on-off valve for opening and closing a first bypass passage that bypasses an exhaust turbine of the first turbocharger, and the second turbocharger. A second on-off valve for opening and closing a second bypass passage that bypasses the exhaust turbine of the charger, and a third bypass passage for opening and closing a third bypass passage that bypasses the intake turbine of the second turbocharger. 3. An operation control method for an internal combustion engine comprising three on-off valves, wherein when there is a request for increasing drive torque related to the internal combustion engine, and when there is a request for increase in drive torque related to the internal combustion engine, the first The first on-off valve is closed to A step of closing the pass passage, and a step of closing the first on-off valve to close the first bypass passage and then opening the third on-off valve to open the third bypass passage. It is characterized by this.

  According to the present invention, when there is a request to increase the driving torque related to the internal combustion engine, the first on-off valve is closed to close the first bypass passage, and all the exhaust gas is transferred to the exhaust turbine of the first turbocharger. Then, supercharging by the first turbocharger is started. Next, the third on-off valve is opened to open the third bypass passage, and the third bypass where the intake air supercharged by the intake turbine of the first turbocharger is provided with the third on-off valve is arranged. It is led to the internal combustion engine through the passage.

  In the internal combustion engine operation control method according to the present invention, the method further includes the step of opening the third on-off valve to open the third bypass passage, and then opening the second on-off valve to open the second bypass passage. be able to.

  Further, the method further comprises a step of detecting the pressure of the third bypass passage upstream and downstream of the third on-off valve, and the pressure difference between the third bypass passage upstream and downstream of the third on-off valve. When is less than or equal to a predetermined value, it is preferable to execute a step of opening the second on-off valve to open the second bypass passage.

  An auxiliary drive motor connected to the first turbocharger and capable of driving the turbocharger is further provided. After closing the first on-off valve and closing the first bypass passage, the auxiliary drive motor is driven to drive the first turbocharger. The method may further comprise assisting the increase in rotation of the turbocharger. In this case, the step of suppressing the overspeed of the first turbocharger by opening the first on-off valve and guiding the exhaust gas to the first bypass passage, and the overspeed of the first turbocharger are prevented. Prior to the suppressing step, a step of stopping energization of the auxiliary drive motor can be further included.

  According to the operation control method for an internal combustion engine of the present invention, when there is a request for increasing the drive torque related to the internal combustion engine, the first bypass passage is closed and then the third bypass passage is opened. All can be led to the exhaust turbine of the first exhaust turbocharger. As a result, a decrease in the supercharging pressure can be suppressed to prevent a so-called breathing phenomenon of supercharging, and a more natural acceleration feeling can be obtained.

  When the second bypass passage is opened after the third bypass passage is opened, the supercharging pressure obtained by the first turbocharger is guided to the third bypass passage, and as a result, Pumping loss can be reduced and fuel consumption can be improved.

  When the pressure difference between the third bypass passage on the upstream side and the downstream side of the third on-off valve is equal to or smaller than a predetermined value, the second bypass passage is opened by executing a step of opening the second bypass passage. The step of performing can be performed after the third bypass passage is reliably opened.

  After the first bypass passage is closed, when the auxiliary drive motor is driven to assist the increase in rotation of the first turbocharger, the supercharging pressure is quickly increased by the first turbocharger. Can be expected.

  When energizing the auxiliary drive motor is stopped in advance when suppressing the excessive rotation of the first turbocharger, useless power consumption can be avoided.

1 is a conceptual diagram schematically showing an intake / exhaust system of an internal combustion engine that is a subject of the present invention. It is a graph which represents typically the relationship between the flow volume regarding the 1st and 2nd turbocharger, a pressure ratio, and efficiency. It is a flowchart showing the control procedure of the supercharging pressure in the embodiment shown in FIG. The opening degree of the accelerator pedal, the turbine shaft rotational speed of the first and second turbochargers, and the open / closed states of the intake bypass valve, the first exhaust bypass valve, and the second exhaust bypass valve in the embodiment shown in FIG. 4 is a time chart schematically showing a relationship between energization of the auxiliary drive motor and on / off. It is a flowchart showing another control procedure of the supercharging pressure in the embodiment shown in FIG.

  An embodiment in which the operation control method according to the present invention is applied to a compression ignition type internal combustion engine in which a sequential type two-stage turbocharger is incorporated will be described in detail with reference to FIGS. However, the present invention is not limited to such an embodiment, and the configuration can be freely changed according to required characteristics. For example, the present invention is also effective for a spark ignition type internal combustion engine in which gasoline, alcohol, LNG (liquefied natural gas) or the like is used as fuel and is ignited by a spark plug.

  The main part of the engine system in the present embodiment is schematically shown in FIG. 1, but in addition to a valve operating mechanism for intake and exhaust, a throttle valve, and an EGR device, some of the sensors necessary for smooth operation of the engine, etc. Are also omitted for convenience.

The engine 10 in the present embodiment is a compression ignition type multi-cylinder (four cylinders in the illustrated example) internal combustion that spontaneously ignites by directly injecting light oil as fuel into the combustion chamber 12 in a compressed state from the fuel injection valve 11. Is an institution. However, a single cylinder internal combustion engine may be used due to the characteristics of the present invention. The amount of fuel from the fuel injection valve 11 is supplied into the combustion chamber 12 and the injection timing is controlled by the ECU (E lectronic C ontrol U nit ) 15 based on the operating state of the vehicle. The driving state of the vehicle referred to here includes the crank angle phase of the engine 10 detected by the crank angle sensor 13, the depression amount of the accelerator pedal 14 by the driver, and the like. The amount of depression of the accelerator pedal 14 is detected by the accelerator opening sensor 16, and the detection information is output to the ECU 15. In the present embodiment, the ECU 15 continuously calculates the change rate of the depression amount of the accelerator pedal 14, that is, the change rate α _n of the accelerator opening, based on the detection information from the accelerator opening sensor 16. When this exceeds a positive predetermined value αR, it is determined that there is a request for increasing the driving torque of the engine 10.

  An intake pipe 18 connected to the engine 10 via the intake manifold 17 defines an intake passage 19 together with the intake manifold 17. Similarly, the exhaust pipe 21 connected to the engine 10 via the exhaust manifold 20 defines an exhaust passage 22 together with the exhaust manifold 20.

  The first and second turbochargers 23 and 24 are arranged in series across the intake pipe 18 and the exhaust pipe 21. The second turbocharger 24 mainly used in the low rotation region of the engine 10 is arranged downstream of the intake passage 19, that is, upstream of the exhaust passage 22 relative to the first turbocharger 23. .

  An induction type auxiliary drive motor 25 whose operation is controlled by the ECU 15 is connected to the turbine shaft 23a of the first turbocharger 23 in the present embodiment. When there is a request to increase the driving torque of the engine 10, the ECU 15 energizes the auxiliary driving motor 25 to assist the rapid rotation and rise of the turbine shaft 23a having a relatively large inertial mass. In the present embodiment, energization of the auxiliary drive motor 25 is performed immediately after the first exhaust bypass valve, which will be described later, is fully closed, thereby avoiding unnecessary power consumption as much as possible.

  The intake pipe 18 upstream and downstream of the intake passage 19 where the intake turbine 23 i of the first turbocharger 23 is located has a first intake bypass pipe 26 arranged in parallel to the intake pipe 18. The branch part 27d and the junction part 27c are formed. That is, both ends of the first intake bypass pipe 26 are connected to the intake pipe 18 by the upstream branch portion 27d and the downstream junction portion 27c of the intake passage 19, and the intake turbine of the first turbocharger 23 is connected. A first intake bypass passage 27 that bypasses 23i is defined. Therefore, the first intake bypass passage 27 branched from the intake passage 19 at the branching portion 27d bypasses the intake turbine 23i of the first turbocharger 23, and the intake passage 19 at the junction 27c on the downstream side thereof. Join again.

  A mechanical check valve 28 that can open and close the first intake bypass passage 27 is incorporated in the middle of the first intake bypass pipe 26, and the differential pressure between the upstream side and the downstream side of the check valve 28 is increased. Accordingly, the opening degree is automatically changed.

  In the present invention, the first intake bypass passage 27 and the check valve 28 described above can be omitted. However, by providing the check valve 28, the rotation of the turbine shaft 23a can be lubricated. Lubricating oil can be prevented from being sucked out to the intake passage 19 side.

  A second intake bypass pipe 29 arranged in parallel to the intake pipe 18 is provided in the intake pipe 18 upstream and downstream of the intake passage 19 where the intake turbine 24 i of the second turbocharger 24 is located. The branch part 30d and the junction part 30c are formed. That is, both ends of the second intake bypass pipe 29 are connected to the intake pipe 18 by the upstream branch portion 30d and the downstream junction portion 30c of the intake passage 19, and the intake turbine of the second turbocharger 24 is connected. A second intake bypass passage 30 that bypasses 24i is defined. Accordingly, the second intake bypass passage 30 branched from the intake passage 19 at the branch portion 30d functions as the third bypass passage in the present invention, and bypasses the intake turbine 24i of the second turbocharger 24. It merges with the intake passage 19 again at the downstream junction 30c. A branch portion 30d between the intake pipe 18 and the second intake bypass pipe 29 is located on the downstream side of the intake passage 19 with respect to the junction 27c between the first intake bypass pipe 26 and the intake pipe 18.

  In the middle of the second intake bypass pipe 29, an intake bypass valve 31 for opening and closing the second intake bypass passage 30 is provided as a third on-off valve of the present invention. An intake bypass valve drive motor 32 is connected to the intake bypass valve 3125, and its operation is controlled by the ECU 15 in accordance with the driving state of the vehicle. It is also effective to connect a valve opening sensor (not shown) for detecting the opening degree of the intake bypass valve 31 to the intake bypass valve 31 and output the detection information to the ECU 15. In this case, it becomes possible to more appropriately control the operation start timing of a second exhaust bypass valve drive motor, which will be described later, based on information from the valve opening sensor.

  An intercooler 33 for cooling the intake air is incorporated in the intake pipe 18 further downstream than the junction 29 c between the intake pipe 18 and the second intake bypass pipe 29 in order to increase the filling density of the intake air flowing through the intake passage 19. Yes.

  On the other hand, a first exhaust bypass pipe disposed in parallel to the exhaust pipe 21 is provided in the exhaust pipe 21 upstream and downstream of the exhaust passage 22 where the exhaust turbine 23e of the first turbocharger 23 is located. A branching portion 35d and a merging portion 35c are formed. That is, both ends of the first exhaust bypass pipe 34 are connected to the exhaust pipe 21 by the upstream branching portion 35d and the downstream joining portion 35c of the exhaust passage 22, and the exhaust turbine of the first turbocharger 23 is connected. A first exhaust bypass passage 35 that bypasses 23e is defined. Accordingly, the first exhaust bypass passage 35 branched from the exhaust passage 22 at the branch portion 35d functions as the first bypass passage in the present invention, and bypasses the exhaust turbine 36b of the first turbocharger 23. It joins the exhaust passage 22 at the downstream junction 35c.

  In the middle of the first exhaust bypass pipe 34, a first exhaust bypass valve 36 for opening and closing the first exhaust bypass passage 35 is provided as a first on-off valve in the present invention. A first exhaust bypass valve drive motor 37 is connected to the first exhaust bypass valve 36, and its operation is controlled by the ECU 15 in accordance with the driving state of the vehicle. It is also effective to connect a valve opening sensor (not shown) for detecting the opening of the first exhaust bypass valve 36 to the first exhaust bypass valve 36 and to output the detection information to the ECU 15. In this case, the operation start timing of the intake bypass valve drive motor 32 can be controlled more appropriately based on information from the valve opening sensor.

  The exhaust pipe 21 upstream and downstream of the exhaust passage 22 where the exhaust turbine 24e of the second turbocharger 24 is located has a second exhaust bypass pipe 38 disposed in parallel to the exhaust pipe 21. The branch part 39d and the junction part 39c are formed. That is, both ends of the second exhaust bypass pipe 38 are connected to the exhaust pipe 21 by the upstream branching portion 39d and the downstream joining portion 39c of the exhaust passage 22, and the exhaust turbine of the second turbocharger 24 is connected. A second exhaust bypass passage 39 that bypasses 24e is defined. Accordingly, the second exhaust bypass passage 39 branched from the exhaust passage 22 at the branch portion 39d functions as the second bypass passage in the present invention, and is in a state of bypassing the exhaust turbine 24e of the second turbocharger 24. The air then joins the exhaust passage 22 again at the downstream junction 39c. The junction 39c between the exhaust pipe 21 and the second exhaust bypass pipe 38 is located upstream of the branch passage 35d between the exhaust pipe 21 and the first exhaust bypass pipe 34.

  In the middle of the second exhaust bypass pipe 38, a second exhaust bypass valve 40 for opening and closing the second exhaust bypass passage 39 is provided as a second on-off valve in the present invention. A second exhaust bypass valve drive motor 41 is connected to the second exhaust bypass valve 40, and its operation is controlled by the ECU 15 according to the driving state of the vehicle.

  Exhaust gas for detoxifying harmful substances generated by combustion of the air-fuel mixture in the combustion chamber 12 is disposed in the exhaust pipe 21 located downstream of the joining portion 35 c of the exhaust pipe 21 and the first exhaust bypass pipe 34. A purification device 42 is connected. By this exhaust purification device 42, harmful substances in the exhaust discharged from the engine 10 are adsorbed or rendered harmless, and clean exhaust is released from the exhaust pipe 21 into the atmosphere.

  The previous ECU 15 calculates the change rate αn of the accelerator pedal opening based on the detection information from the accelerator opening sensor 16, and if the driver determines that this is greater than a predetermined positive value αR, the driver accelerates the vehicle. It judges that it is request | required, and performs control of this invention demonstrated below. That is, the ECU 15 closes the first exhaust bypass valve 36 and closes the first exhaust bypass passage 35, then opens the intake bypass valve 31 and opens the second intake bypass passage 30. Thereafter, the second exhaust bypass valve 40 is opened to open the second exhaust bypass passage 39. As a result, all the exhaust gas can be guided to the exhaust turbine 23e of the first exhaust turbocharger 23. As a result, a decrease in the supercharging pressure can be suppressed to prevent a so-called breathing phenomenon of supercharging, and a more natural acceleration feeling can be obtained. In addition, as a result of the supercharging pressure obtained by the first turbocharger 23 being guided to the second intake bypass passage 30, it is possible to reduce intake pumping loss and improve fuel efficiency.

Here, the supercharging efficiency of the first and second turbochargers 23 and 24 is schematically shown in FIG. The dashed contour lines indicate the efficiency of the first turbocharger 23, the solid lines indicate the efficiency of the second turbocharger 24, and the second turbocharger 24 indicated by the solid contour lines is effective. This is a working partial region, that is, a low rotation region of the engine 10. In this partial region, the ECU 15 controls the opening degree of the first exhaust bypass valve 36 other than fully closed so that the first turbocharger 23 does not function. In other words, when the engine speed N _e is out of the partial range of, for example, N _R (in the case of a general passenger car, for example, about 2200 revolutions per minute) or less, the turbine shaft 23 a of the first turbocharger 23. Is rotating at a high speed to some extent, the above-described control of the present invention is not executed. The engine rotational speed N _e is calculated by the ECU15 based on the detection information from the crank angle sensor 13.

FIG. 3 shows a control procedure for such a supercharging pressure. Further, the opening degree of the accelerator pedal 14, the open / closed state of the first exhaust bypass valve 36, the second exhaust bypass valve 40, and the intake bypass valve 31, the turbine shaft rotational speeds of the first and second turbochargers 23, 24, and FIG. 4 schematically shows the relationship between energization on / off of the auxiliary drive motor 25. That is, the change rate αn accelerator opening first at S1 in step determines whether greater than the predetermined value alpha _R. When the change rate α _n of the accelerator opening is equal to or less than the predetermined value α _R , that is, when it is determined that the driver does not desire acceleration of the vehicle, the process is terminated without doing anything.

Further, the rate of change αn accelerator opening is determined in step S1 is greater than the predetermined value alpha _R, that is, when it is determined that there has been increased demand for driving torque about the engine 10 shifts to S2 step. Then, it is determined whether or not the engine speed N _e is smaller than a predetermined value N _{R. When} it is determined that the engine speed N _e is equal to or higher than the predetermined value N _R , that is, the engine 10 is not in the partial region. Quit without doing anything. This is because it is not necessary to execute the control of the present invention because the rotation of the first turbocharger 23a 23a has already increased.

If it is determined in step S2 that the engine speed _Ne is smaller than the predetermined value N _R , that is, the engine 10 is in the partial region, the process proceeds to step S3. In step S3, the first exhaust bypass valve drive motor 37 is driven to forcibly shift the first exhaust bypass valve 36 to the fully closed state. In this way, the first exhaust bypass passage 35 is completely closed, all the exhaust from the engine 10 is caused to flow into the exhaust turbine 23e of the first turbocharger 23, and the first turbocharger 23 is operated. .

  Next, in step S4, the auxiliary drive motor 25 is energized, and the rotation of the turbine shaft 23a of the first turbocharger 23 is rapidly increased. It should be noted that when the auxiliary drive motor 25 is not incorporated, the increase in the turbine shaft rotational speed of the first turbocharger 23 becomes slow as indicated by a two-dot chain line in FIG. That is, by using the auxiliary drive motor 25, the output responsiveness to the depression operation of the accelerator pedal 14 can be enhanced. In the present embodiment, the auxiliary drive motor 25 is energized when the first exhaust bypass valve 36 is fully closed.

  Thereafter, the routine proceeds to step S5, where the intake bypass valve drive motor 32 is driven, and the intake bypass valve 31 is forcibly shifted to the fully open state. As a result, the supercharging pressure obtained by the first turbocharger 23 is supplied to both the intake bypass passage 30 and the intake turbine 24i of the second supercharger 24, thereby suppressing a decrease in the supercharging pressure. Thus, the so-called breathing phenomenon of supercharging can be prevented, and a more natural acceleration feeling can be obtained.

  If the intake bypass valve 31 has shifted to the fully open state, the process immediately proceeds to step S6 to shift the second exhaust bypass valve 40 to the fully open state, and the exhaust from the engine 10 is discharged from the second exhaust bypass passage 39 to the first. It leads to the exhaust turbine 23e of the turbocharger 23. As a result, a load on the second turbocharger 24 is avoided, and the boost pressure obtained by the operation of the first turbocharger 23 is led to the intake bypass passage 30. This can reduce fuel consumption and improve fuel efficiency.

Next, in step S7, it is determined whether or not the change rate α _{n of the} accelerator opening is equal to or less than a predetermined value α _R, that is, whether or not there is a request for increasing the drive torque related to the engine 10. Here, when the change rate α _n of the accelerator opening is equal to or less than the predetermined value α _R , that is, when it is determined that there is no request for increasing the drive torque related to the engine 10, the process proceeds to step S8 and the auxiliary drive motor 25 is moved. Stop energizing. Next, in step S9, the opening degree of the first exhaust bypass valve 36 is controlled by the ECU 15 via the first exhaust bypass valve drive motor 25 in accordance with the operating state at this time, and the process returns to step S1 again to open the accelerator. It is determined whether or not the degree of change rate α _n is greater than a predetermined value α _R.

  As described above, when there is a request for increasing the drive torque in the partial region of the engine 10, the first exhaust bypass valve 36 is fully closed → the intake bypass valve 31 is fully opened → the second exhaust bypass valve 40 is fully opened. As a result, the breathing of the intake air can be reliably prevented. Further, when the fully closed state of the first exhaust bypass valve 36 is released in order to suppress over-rotation of the turbine shaft 23 a of the first turbocharger 23, auxiliary drive is performed prior to driving of the first exhaust bypass valve 36. Since energization to the motor 25 is stopped, wasteful power consumption can be suppressed.

In addition, it is also possible to incorporate a mechanical differential pressure on / off valve in place of the electric intake bypass valve 31 described above. Such a differential pressure on-off valve opens and closes the second intake bypass passage 30 according to the pressure difference of the second intake bypass passage 30 between the upstream side and the downstream side, that is, the differential pressure. In this case, a pair of pressure sensors 43 and 44 for detecting the pressure in the second intake bypass passage 30 upstream and downstream of the differential pressure on-off valve and outputting the detected information to the ECU 15 are incorporated in the second intake bypass pipe 29. Based on this detection information, the second exhaust bypass valve 40 is driven. That, ECU 15 determines that the differential pressure ΔP detected by the pressure sensor 43, 44 is a differential pressure switch valve is fully opened when it becomes less than the predetermined value P _R, the second exhaust bypass valve driving motor 41 Can be operated. In the case of this embodiment, the intake bypass valve drive motor 32 becomes unnecessary.

Such a control procedure of another embodiment according to the present invention is shown in FIG. 5, but the same steps as those of the previous embodiment are denoted by the same step numbers, and redundant description will be omitted. That is, whether or not the change rate alpha _n of the accelerator opening is determined in step S1 is greater than the predetermined value alpha _R, wherein determining the change rate alpha _n of the accelerator opening is larger than the predetermined value alpha _R If so, the process proceeds to step S2. If it is determined in step S2 that the engine rotational speed _Ne is smaller than the predetermined value N _R , the process proceeds to step S3 to drive the first exhaust bypass valve drive motor 37 and the first exhaust bypass valve 36. Is forcibly shifted to the fully closed state. Next, in step S4, the auxiliary drive motor 25 is energized, and the rotation of the turbine shaft 23a of the first turbocharger 23 is rapidly increased.

Then, the differential pressure ΔP of the pressure detected by the pressure sensor 43 at step S15 is equal to or less than the predetermined value P _R, until this pressure difference ΔP is equal to or less than a predetermined value P _R Continue processing. Then, the differential pressure ΔP is equal to or smaller than the predetermined value P _R, that is, when the intake bypass valve 31 is determined to have shifted to the fully open state, and operates the second exhaust bypass valve driving motor 41 proceeds to step S6 Then, the second exhaust bypass valve 40 is shifted to the fully open state. As a result, the exhaust from the engine 10 is guided from the second exhaust bypass passage 39 to the exhaust turbine 23 e of the first turbocharger 23.

Then, the change rate αn accelerator opening is equal to or less than a predetermined value alpha _R at step S7. Here, _{if it} is determined that the change rate α _n of the accelerator opening is equal to or less than the predetermined value α _R , that is, it is determined that the drive torque increase request for the engine 10 has been completed, the process proceeds to step S8 and the auxiliary drive motor. The energization to 25 is stopped. Thereafter, the process returns to the step S1 again to determine whether or not the change rate α _n of the accelerator opening is larger than the predetermined value α _R , but the opening of the first exhaust bypass valve 36 is set to the driving state of the vehicle. It is of course possible to execute the previous step S9 to be controlled accordingly.

  It should be noted that the present invention should be construed only from the matters described in the claims, and in the above-described embodiment, all the changes and modifications included in the concept of the present invention are other than those described. Is possible. That is, all matters in the above-described embodiment are not intended to limit the present invention, and include any configuration not directly related to the present invention. To get.

DESCRIPTION OF SYMBOLS 10 Engine 11 Fuel injection valve 12 Combustion chamber 13 Crank angle sensor 14 Accelerator pedal 15 ECU
16 Accelerator opening sensor 17 Intake manifold 18 Intake pipe 19 Intake passage 20 Exhaust manifold 21 Exhaust pipe 22 Exhaust passage 23 First turbocharger 23a Turbine shaft 23i Intake turbine 23e Exhaust turbine 24 Second turbocharger 24i Intake Turbine 24e Exhaust turbine 25 Auxiliary drive motor 26 First intake bypass pipe 26d Branch portion 26c Merging portion 27 First intake bypass passage 28 Check valve 29 Second intake bypass pipe 29d Branch portion 29c Merging portion 30 Second intake bypass passage 31 Intake air Bypass valve 32 Intake bypass valve drive motor 33 Intercooler 34 First exhaust bypass pipe 34d Branch portion 34c Merging portion 35 First exhaust bypass passage 36 First exhaust bypass valve 37 First exhaust bypass valve drive motor 38 Second exhaust bypass Pass pipe 38d Branching portion 38c Merging portion 39 Second exhaust bypass passage 40 Second exhaust bypass valve 41 Second exhaust bypass valve drive motor 42 Exhaust purification device 43, 44 Pressure sensor

Claims (5)

A first turbocharger;
A second turbocharger that is arranged in series with the upstream side of the exhaust passage relative to the first turbocharger and is mainly used in a low rotation region of the internal combustion engine;
A first on-off valve for opening and closing a first bypass passage that bypasses an exhaust turbine of the first turbocharger;
A second on-off valve for opening and closing a second bypass passage that bypasses the exhaust turbine of the second turbocharger;
An internal combustion engine operation control method comprising a third on-off valve for opening and closing a third bypass passage that bypasses the intake turbine of the second turbocharger,
Determining whether or not there is a request to increase the drive torque for the internal combustion engine;
When there is a request to increase the driving torque related to the internal combustion engine, closing the first on-off valve and closing the first bypass passage;
An internal combustion engine comprising: closing the first on-off valve to close the first bypass passage, and then opening the third on-off valve to open the third bypass passage. Operation control method.   The method further comprises the step of opening the third on-off valve to open the third bypass passage, and then opening the second on-off valve to open the second bypass passage. 2. An operation control method for an internal combustion engine according to 1.   And further detecting the pressure of the third bypass passage upstream and downstream of the third on-off valve, and the pressure of the third bypass passage upstream and downstream of the third on-off valve. 3. The operation of the internal combustion engine according to claim 1, wherein when the difference is equal to or less than a predetermined value, the step of opening the second on-off valve and opening the second bypass passage is executed. Control method. An auxiliary drive motor connected to the first turbocharger and capable of driving the turbocharger;
The method further comprises the step of driving the auxiliary drive motor to assist the increase in rotation of the first turbocharger after closing the first on-off valve and closing the first bypass passage. An operation control method for an internal combustion engine according to any one of claims 1 to 3. Suppressing the over-rotation of the first turbocharger by opening the first on-off valve and guiding the exhaust to the first bypass passage;
5. The operation control of the internal combustion engine according to claim 4, further comprising a step of stopping energization of the auxiliary drive motor prior to the step of suppressing over-rotation of the first turbocharger. Method.

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