JP2010270715A - Internal combustion engine with sequential two-stage supercharger and method for controlling the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an internal combustion engine with a sequential two-stage supercharger and a method for controlling the internal combustion engine with the sequential two-stage supercharger that can secure the active temperature of a catalyst even when it is cold. <P>SOLUTION: In an diesel engine 1 with the sequential two-stage supercharger, a low pressure stage supercharger 3B is operated in the open state of an exhaust bypass valve 3C2 of a bypass pipe 3C1 connecting an inlet and an outlet of a high pressure stage turbine 3At of a high pressure stage supercharger 3A until an engine cooling water temperature, a fuel flow rate, or both of them reach the preset values when the engine is cold after the start of the engine. The heat radiation quantity of exhaust gas can thereby be reduced by not passing through the high pressure stage supercharger 3A. Since a combustion temperature in an engine body 2 can be raised by reducing the intake air quantity into the engine body 2, an exhaust gas temperature at the inlet of a post-treating device 11 can be raised to secure the active temperature of the catalyst in the post-treating device 11. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an internal combustion engine with a sequential two-stage supercharger and a control method thereof, and more specifically, a sequential two-stage supercharger capable of ensuring a catalyst activation temperature even when the engine is cold. The present invention relates to an internal combustion engine and a control method therefor.

  In recent years, research on premixed compression ignition combustion that enables simultaneous reduction of nitrogen oxides (NOx) and smoke has been actively conducted in diesel engines. This premixed compression ignition combustion generates and burns a uniform and lean mixture at an early stage, and as a technical problem, if the engine load is increased, pre-ignition occurs and it becomes difficult to control the ignition timing. There is a problem limited to the low load region.

  In order to expand the operating range by this premixed compression ignition combustion, a part of the exhaust gas is taken out from the exhaust system, returned to the intake system, and the EGR rate of EGR (Exhaust Gas Recirculation) added to the mixture is increased. It is effective to suppress the combustion by reducing the oxygen concentration of the air-fuel mixture and to secure the air-fuel ratio (A / F). As a specific countermeasure, for example, a sequential two-stage turbocharger is used, and a high boost is obtained from a low-speed and low-load region by a high-pressure small turbocharger to secure a high EGR rate and a high air-fuel ratio. (See, for example, Patent Document 1).

  In addition, the sequential two-stage turbocharger is a means to achieve both a reduction in fuel consumption in low-medium speed / low-medium load (urban) driving with a high-pressure stage turbocharger and a high output with a low-pressure stage turbocharger. Is also an effective means.

  However, in a diesel engine with a multistage turbocharger, such as a sequential two-stage turbocharger, the post-processing is performed from the engine body (cylinder head) compared to a diesel engine with a single-stage supercharger. As the exhaust path to the inlet of the device becomes longer, the temperature at the inlet of the aftertreatment device decreases, and as a result, the operating range that does not reach the catalyst activation temperature when the engine is cold increases, resulting in hydrocarbon (HC) and carbon monoxide ( There is a problem that the amount of exhaust gas such as CO) increases.

  For example, in Patent Document 2, the temperature at the turbine outlet of the low-pressure supercharger is lower than the temperature at the turbine outlet of the single-stage supercharger in an engine with a sequential two-stage supercharger. For this reason, a problem has been disclosed that the regeneration capability of the exhaust gas purification device at the rear stage of the turbine outlet is lowered.

JP 2007-262964 A JP 2007-255358 A

  An object of the present invention is to provide a sequential type two-stage supercharger-equipped internal combustion engine capable of ensuring a catalyst activation temperature even when cold and a control method therefor.

  In order to achieve the above object, an internal combustion engine with a sequential two-stage supercharger according to the present invention has a high-pressure supercharger and a low-pressure supercharger connected in series in two stages in order from the main body side of the internal combustion engine. In an internal combustion engine with a sequential type two-stage supercharger, when the internal combustion engine is cold, the high-pressure supercharger until the temperature of the internal combustion engine cooling water, the fuel flow rate, or both reaches a preset value. It has a control means which performs the control which opens the valve | bulb of the bypass pipe which connects the inlet_port | entrance and exit of this high pressure stage turbine, and operates the said low pressure stage supercharger. At this time, control is also performed to open the valve of the bypass pipe that connects the inlet and the outlet of the high-pressure compressor of the high-pressure turbocharger.

  In addition, the sequential two-stage supercharger-equipped internal combustion engine control method according to the present invention for achieving the above-described object includes two high-pressure stage superchargers and two low-pressure stage superchargers in order from the internal combustion engine body side. In a control method for an internal combustion engine with a sequential two-stage supercharger connected in series, when the internal combustion engine is cold, the temperature of the internal combustion engine cooling water, the fuel flow rate, or both are set to preset values. Up to this point, the valve of the bypass pipe that connects the inlet and the outlet of the high-pressure turbine of the high-pressure turbocharger is opened to operate the low-pressure turbocharger. At this time, control is also performed to open the valve of the bypass pipe that connects the inlet and the outlet of the high-pressure compressor of the high-pressure turbocharger.

  In addition, the sequential two-stage supercharger-equipped internal combustion engine control method according to the present invention for achieving the above-described object includes two high-pressure stage superchargers and two low-pressure stage superchargers in order from the internal combustion engine body side. In a control method of an internal combustion engine with a sequential type two-stage supercharger connected in series, when the cooling water temperature, the fuel flow rate, or both of the internal combustion engine is colder than a preset value, the high pressure The step of opening the bypass pipe valve connecting the inlet and outlet of the high-pressure turbine of the stage turbocharger to operate the low-pressure stage turbocharger, the cooling water temperature of the internal combustion engine, the fuel flow rate, or both are determined in advance. A bypass pipe that connects the inlet and the outlet of the high-pressure turbine of the high-pressure turbocharger when the engine is warmed up to a preset value or more and the rotational speed of the internal combustion engine is lower than a preset value Before closing the valve Those having a step of operating the high-pressure stage supercharger.

  In the control method for an internal combustion engine with a sequential two-stage supercharger, when the rotational speed of the internal combustion engine is equal to or higher than a preset value during the warm-up, the high-pressure supercharger The low pressure supercharger is operated by opening a valve of a bypass pipe connecting the inlet and the outlet of the high pressure turbine.

  According to the present invention, when the internal combustion engine is cold, the high pressure stage supercharger is operated by opening the bypass pipe valve that connects between the inlet and outlet of the high pressure stage turbine of the high pressure stage turbocharger and operating the low pressure stage turbocharger. By not using a machine, the heat release amount of exhaust gas in the exhaust pipe can be reduced, and the combustion temperature in the internal combustion engine body can be increased by reducing the intake air amount in the internal combustion engine body. The exhaust gas temperature at the inlet of the processing apparatus can be increased. For this reason, since the catalyst activation temperature in the aftertreatment device can be ensured, the discharge amount of HC, CO, NOx, etc. can be reduced.

1 is a configuration diagram of an internal combustion engine with a sequential two-stage supercharger according to an embodiment of the present invention. It is a graph which shows the change of the engine coolant temperature with respect to time. It is a graph which shows the on / off state of the exhaust bypass valve with respect to time. It is a graph which shows the engine speed with respect to time. 5 is a configuration diagram showing a state of the sequential two-stage supercharger-equipped internal combustion engine of FIG. 1 after time t0 to t1 and time t2 of FIGS. FIG. 5 is a configuration diagram showing a state of the sequential type two-stage supercharger-equipped internal combustion engine of FIG. 1 at times t1 to t2 of FIGS. FIG. 2 is a graph showing a concept of a supercharger control mode region when the internal combustion engine with a sequential two-stage supercharger in FIG. 1 is cold. It is a graph which shows the concept of the supercharger control mode area | region at the time of the cold of the conventional internal combustion engine with a two-stage supercharger of a sequential type.

  Hereinafter, a sequential type two-stage supercharger-equipped internal combustion engine and a control method thereof according to embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 shows a configuration diagram of an internal combustion engine with a sequential two-stage supercharger according to the present embodiment.

  The internal combustion engine with a sequential two-stage supercharger according to the present embodiment is expanded based on self-ignition that occurs when, for example, fuel is supplied to air that has been compressed and heated to high temperature in a cylinder (combustion chamber). The diesel engine (hereinafter simply referred to as the engine) 1 has a configuration for pushing out the piston in the cylinder. In addition, this invention is not limited to a diesel engine, It can also apply to a gasoline engine etc.

  The engine 1 includes an engine body 2, a sequential two-stage supercharging system 3, an EGR (Exhaust Gas Recirculation) system 4, and a control device (Engine Control Unit: ECU) 5. ing. The broken line arrows indicate the wiring electrically connected to the control device 5 and the direction of the signal flowing through the wiring.

  The engine body 2 is provided with an engine coolant temperature sensor (an internal combustion engine coolant temperature sensor) 7 that detects the temperature of coolant of the engine 1. The engine coolant temperature sensor 7 is electrically connected to the control device 5 and transmits a temperature detection signal to the control device 5. Reference numeral 8 denotes an exhaust manifold, and reference numeral 9 denotes an intake manifold.

  The sequential two-stage supercharging system 3 has a configuration in which a high-pressure supercharger 3A and a low-pressure supercharger 3B are connected in series in order from the engine body 2 side, and according to the operating state of the engine 1 In order to select an appropriate supercharger, bypass parts 3C, 3D, and 3E are provided.

  The high pressure supercharger 3A has a high pressure turbine 3At and a high pressure compressor 3Ac. The high-pressure turbine 3At and the high-pressure compressor 3Ac are integrally formed by providing a plurality of blades at both ends of a single shaft, and the exhaust gas force discharged from the engine body 2 by the high-pressure turbine 3At. In response to the rotational driving, the high-pressure compressor 3Bc is linked to the driving force to send the compressed air to the engine body 2.

  The low pressure stage supercharger 3B includes a low pressure stage turbine 3Bt and a low pressure stage compressor 3Bc. The low-pressure turbine 3Bt and the low-pressure compressor 3Bc are integrally formed by providing a plurality of blades at both ends of a single shaft, and the exhaust gas force discharged from the engine body 2 by the low-pressure turbine 3Bt. In response to the rotation, the low-pressure compressor 3Bc is driven by the driving force to send the compressed air to the engine body 2. The capacity of the low pressure stage turbine 3Bt is larger than the capacity of the high pressure stage turbine 3At, and the capacity of the low pressure stage compressor 3Bc is larger than the capacity of the high pressure stage compressor 3Ac.

  First, the exhaust system of the two-stage supercharging system 3 will be described. The inlet of the high-pressure turbine 3At is connected to the exhaust manifold 8 through the upstream exhaust pipe 10a and further connected to the combustion chamber of the engine body 2. Further, the outlet of the high-pressure turbine 3At is connected to the inlet of the low-pressure turbine 3Bt through the downstream exhaust pipe 10b.

  The inlet and outlet of the high pressure turbine 3At are directly connected through the bypass portion 3C without going through the high pressure turbine 3At. The bypass part 3C has a bypass pipe 3C1 and an exhaust bypass valve 3C2 arranged at a midway position thereof. One end of the bypass pipe 3C1 is connected to the exhaust manifold 8, and the other end is connected to the exhaust pipe 10b. The exhaust bypass valve 3C2 is a valve that opens and closes the bypass pipe 3C1. The actuator that opens and closes the exhaust bypass valve 3C2 is electrically connected to the control device 5, and the opening and closing operation is controlled by the control device 5.

  The outlet of the low pressure turbine 3Bt is connected to the exhaust pipe 10c on the downstream side. Further, the inlet and outlet of the low-pressure stage turbine 3Bt are directly connected through the bypass portion 3D without going through the low-pressure stage turbine 3Bt. The bypass unit 3D includes a bypass pipe 3D1 and a waste gate valve 3D2 disposed in the middle of the bypass pipe 3D1. The bypass pipe 3D1 has one end connected to the exhaust pipe 10b and the other end connected to the exhaust pipe 10c. The waste gate valve 3D2 is a valve that opens and closes the bypass pipe 3D1. The actuator that opens and closes the waste gate valve 3D2 is electrically connected to the control device 5, and the opening and closing operation is controlled by the control device 5.

In the exhaust pipe 10c, the post-processing device 11 is installed and connected downstream of the connection position with the bypass pipe 3D1. This post-processing device 11 is a device for detoxifying harmful components in the gas generated and exhausted in the combustion chamber of the engine body 2 and has, for example, a DPF (Diesel Particulate Filter) with a catalyst. The DPF is a catalyst carrier filter or a particulate filter with an oxidation catalyst and a catalyst. When the temperature of the exhaust gas is relatively high, CO and HC in the exhaust gas are harmless by carbon dioxide (CO ₂₎ due to the oxidation action of the catalyst. ), Water (H ₂ O), and particulate matter (PM) in the exhaust gas is collected, and the collected PM is burned by the oxidizing action of the catalyst and removed for regeneration. Has the function to perform. Therefore, in order to maintain the purification / regeneration capability of the post-processing device 11 and to prevent the exhaust resistance from increasing due to clogging due to PM collection and deposition, the post-processing device 11 is introduced. It is preferable to keep the exhaust gas temperature and the inlet temperature of the aftertreatment device 11 high.

  Next, the intake system of the sequential two-stage supercharging system 3 will be described. An intake pipe 14a on the upstream side is connected to the inlet of the low-pressure compressor 3Bc. An air cleaner is connected further upstream of the intake pipe 14a so that the purified air can be supplied into the combustion chamber of the engine body 2.

  The outlet of the low-pressure compressor 3Bc is connected to the inlet of the high-pressure compressor 3Ac through the intake pipe 14b. The outlet of the high-pressure compressor 3Ac is connected to the intake manifold 9 through the intake pipe 14c and further connected to the combustion chamber of the engine body 2. Note that an intercooler 15 is installed between the high-pressure compressor 3Ac and the intake manifold 9 in the intake pipe 14c.

  The inlet and outlet of the high-pressure compressor 3Ac are directly connected through the bypass unit 3E without going through the high-pressure compressor 3Ac. The bypass portion 3E has a bypass pipe 3E1 and an intake bypass valve 3E2 disposed at a midway position thereof. One end of the bypass pipe 3E1 is connected to the intake pipe 14b, and the other end is connected to an upstream portion of the intake pipe 14c from the intercooler 15. The intake bypass valve 3E2 is a valve that opens and closes the bypass pipe 3E1. The actuator that opens and closes the intake bypass valve 3E2 is electrically connected to the control device 5, and the opening and closing operation is controlled by the control device 5.

  The EGR system 4 described above is a system in which a part of the exhaust gas after combustion is taken out and led to the intake side to be sucked again, and is connected between the exhaust manifold 8 and the intake manifold 9. The EGR system 4 includes an EGR pipe 4a, and an EGR valve 4b and an EGR cooler 4c that are sequentially arranged from the downstream side in the middle of the EGR pipe 4a. One end of the EGR pipe 4a is connected to the exhaust manifold 8, and the other end is connected to a downstream portion of the intercooler 15 in the intake pipe 14c. The EGR valve 4b is a valve that opens and closes the EGR pipe 4a. The actuator that opens and closes the EGR valve 4 b is electrically connected to the control device 5, and the opening and closing operation is controlled by the control device 5.

  The control device 5 described above controls the opening / closing operation of the bypass units 3C, 3D, and 3E according to the temperature state and the operating state of the engine 1, whereby the high-pressure supercharger 3A of the two-stage supercharging system 3 and Which of the low-pressure stage superchargers 3B is to be operated is selected.

  That is, when the engine 1 is warming up, when the engine is in a low speed to medium speed range (low load operation to medium load operation), the small-capacity high-pressure supercharger 3A is operated, and the medium speed to high speed range. In the case of (medium load operation to high load operation), the large-capacity low-pressure supercharger 3B is operated. In the transition region where both are switched, the bypass portions 3C and 3E are operated to control the opening and closing of the exhaust bypass valve 3C2 and the intake bypass valve 3E2.

  Further, the control device 5 for the engine 1 according to the present embodiment sets the cooling water temperature, the fuel flow rate (load) or both of the engine 1 in advance when the engine 1 is cold after the engine 1 is started. In the case where the value is smaller than the set value, the bypass unit 3C is operated regardless of the engine speed until the cooling water temperature of the engine 1, the fuel flow rate (load), or both become a preset value or more, and the exhaust gas is discharged. The bypass valve 3C2 is opened, and the large-capacity low-pressure supercharger 3B is operated. At this time, the waste gate valve 3d2 of the bypass portion 3D is closed, and the bypass portion 3E is operated to open the intake bypass valve 3E2.

  Thus, when the engine is cold, the exhaust gas discharged from the engine body 2 does not pass through the high-pressure supercharger 3A, so that the heat release amount of the exhaust gas in the exhaust pipe can be reduced. Since the combustion temperature in the combustion chamber of the engine body 2 can be increased by reducing the amount of intake air into the combustion chamber, the exhaust gas temperature at the inlet of the aftertreatment device 11 can be increased. For this reason, since the catalyst activation temperature in the aftertreatment device 11 can be ensured, the discharge amount of hydrocarbons (HC), carbon monoxide (CO), nitrogen oxides (NOx) and the like can be reduced.

  The coolant temperature of the engine 1 is measured by the control device 5 based on the detection information sent from the engine coolant temperature sensor 7 to the control device 5 described above. Further, the fuel flow rate is measured by the control device 5 based on the measurement information sent from the fuel flow measurement device to the control device 5. Further, the load is derived by the control device 5 based on the measured fuel flow rate.

  Next, an example of a method for controlling the engine 1 will be described with reference to FIGS. 2 to 4 are graphs respectively showing changes in the coolant temperature of the engine 1 with respect to time, the on / off state of the exhaust bypass valve, and the engine speed. 5 shows the state of the flow of intake air and exhaust gas (solid arrow) of the engine 1 after time t0 to t1 and time t2 in FIGS. 2 to 4, and FIG. 6 shows time t1 in FIGS. The state of the flow of intake air and exhaust gas (solid arrow) of the engine 1 at ~ t2 is shown.

  First, as shown in FIGS. 2 to 4, after the engine 1 is started, when the cooling water temperature of the engine 1 is smaller than a preset value T1 (time t0 to t1: cold), FIG. As shown in FIG. 3, the low pressure supercharger 3B is operated by opening the exhaust bypass valve 3C2 and closing the waste gate valve 3D2. In this case, the exhaust gas discharged from the engine main body 2 enters the low pressure stage turbine 3Bt of the low pressure stage supercharger 3B through the bypass pipe 3C1 from the exhaust manifold 8 without passing through the high pressure stage turbine 3At, and passes through the low pressure stage turbine 3Bt. The post-processing apparatus 11 is entered. That is, since the exhaust gas discharged from the engine body 2 reaches the aftertreatment device 11 without passing through the high pressure turbine 3At of the high pressure turbocharger 3A, the exhaust gas is released as compared with the case through the high pressure turbine 3At. The amount of heat can be reduced. For this reason, the exhaust gas temperature at the inlet of the aftertreatment device 11 can be raised.

  At this time, the intake bypass valve 3E2 is opened in the intake system of the engine 1. In this case, the intake gas is supercharged by the low-pressure compressor 3Bc of the low-pressure supercharger 3B, supplied to the intake manifold 9 through the bypass pipe 3E1, and supplied to the combustion chamber of the engine body 2. Thereby, since the intake air amount into the combustion chamber of the engine body 2 can be reduced, the combustion temperature in the combustion chamber of the engine body 2 can be raised. For this reason, since the temperature of exhaust gas becomes high, the exhaust gas temperature of the inlet_port | entrance of the post-processing apparatus 11 can be raised.

  Therefore, in the control method of the engine 1 of the present embodiment, the catalyst activation temperature in the aftertreatment device 11 can be ensured even in the cold state, so that exhaust gases such as HC, CO, NOx, etc. are discharged. The amount can be reduced.

  Subsequently, as shown in FIG. 2 to FIG. 4, during the time when the coolant temperature of the engine 1 becomes equal to or higher than a preset value T1 (time t1 to t2: during warm-up), as shown in FIG. The high pressure supercharger 3A is operated by closing the exhaust bypass valve 3C2 and opening the waste gate valve 3D2. In this case, the exhaust gas discharged from the engine body 2 enters the high-pressure turbine 3At of the high-pressure supercharger 3A from the exhaust manifold 8 through the exhaust pipe 10a, passes through the high-pressure turbine 3At, and passes through the bypass pipe 3D1 to the aftertreatment device 11. to go into.

  At this time, in the intake system of the engine 1, the intake bypass valve 3E2 is closed. As a result, the intake gas flows into the high pressure compressor 3Ac of the high pressure supercharger 3A, is supercharged by the high pressure compressor 3Ac, and is supplied to the combustion chamber of the engine body 2 through the intake manifold 9.

  Subsequently, as shown in FIG. 2 to FIG. 4, after the time t2 when the engine speed becomes equal to or higher than a preset value, the exhaust bypass valve 3C2 and the intake bypass valve 3E2 are opened as shown in FIG. Then, the waste gate valve 3D2 is closed, and the low-pressure supercharger 3B is operated as described above. Thus, according to the control method of the engine 1 of the present embodiment, it is possible to smoothly select the supercharger as a whole while improving environmental performance, and to realize stable operation.

  FIG. 7 is a graph showing the concept of the supercharger control mode region when the engine 1 of the present embodiment is cold, and FIG. 8 is a supercharger control mode region when the conventional engine is cold for comparison. It is a graph which shows the concept of.

  In the engine 1 of the present embodiment, as shown in FIG. 7, the supercharger is switched according to the engine rotation speed and the fuel flow rate (load) value in addition to the engine rotation speed. That is, the low pressure supercharger 3B is operated in a region where the fuel flow rate (load) is smaller than a preset value even in a region where the engine speed is low. On the other hand, in the prior art, as shown in FIG. 8, the turbocharger is switched exclusively according to the engine speed, and the region where the fuel flow rate (load) is low when the engine speed is low. Even so, the high-pressure supercharger 3A is operated.

  The internal combustion engine with a sequential two-stage supercharger and its control method according to the present invention open a bypass pipe valve that connects between the turbine side inlet and outlet of the high-pressure supercharger when the internal combustion engine is cold. By operating the low-pressure stage supercharger, the catalyst activation temperature in the aftertreatment device can be secured, and the exhaust gas emissions such as HC and CO can be reduced. The present invention can be used for an internal combustion engine having a feeder and a control method thereof.

1 Two-stage turbocharged diesel engine 2 Engine body (internal combustion engine body)
3 Two-stage turbocharging system 3A High-pressure stage turbocharger 3At High-pressure stage turbine 3Ac High-pressure stage compressor 3B Low-pressure stage turbocharger 3Bt Low-pressure stage turbine 3Bc Low-pressure stage compressor 3C Bypass section 3C1 Bypass pipe 3C2 Exhaust bypass valve 3D Bypass section 3D1 Bypass Pipe 3D2 Wastegate valve 3E Bypass section 3E1 Bypass pipe 3E2 Intake bypass valve 4 EGR system 5 Control device (control means)
7 Engine coolant temperature sensor (Internal combustion engine coolant temperature sensor)
10a Exhaust pipe 10b Exhaust pipe 10c Exhaust pipe 11 Post-processing device 14a Intake pipe 14b Intake pipe 14c Intake pipe

Claims (4)

  In an internal combustion engine with a sequential two-stage supercharger in which a high-pressure stage turbocharger and a low-pressure stage turbocharger are connected in series in series from the internal combustion engine body side, when the internal combustion engine is cold, the internal combustion engine Until the cooling water temperature, the fuel flow rate, or both of them reaches a preset value, the valve of the bypass pipe that connects the inlet and the outlet of the high-pressure turbine of the high-pressure turbocharger is opened. An internal combustion engine with a sequential two-stage supercharger, comprising control means for controlling the operation of the machine.   In a control method for an internal combustion engine with a sequential two-stage supercharger in which a high-pressure stage supercharger and a low-pressure stage supercharger are connected in series in series from the internal combustion engine main body side, when the internal combustion engine is cold, Until the cooling water temperature, the fuel flow rate, or both of the internal combustion engine reach preset values, the valve of the bypass pipe connecting the inlet and the outlet of the high-pressure turbine of the high-pressure turbocharger is opened and the low-pressure A control method for an internal combustion engine with a sequential two-stage supercharger for operating a stage supercharger. In a control method for an internal combustion engine with a sequential type two-stage supercharger in which a high-pressure stage turbocharger and a low-pressure stage supercharger are connected in series in series from the internal combustion engine body side,
When the cooling water temperature of the internal combustion engine, the fuel flow rate, or both are colder than a preset value, the valve of the bypass pipe that connects the inlet and outlet of the high-pressure turbine of the high-pressure turbocharger is opened. Operating the low-pressure supercharger,
When the temperature of the cooling water of the internal combustion engine, the fuel flow rate or both are warming up above a preset value and the rotational speed of the internal combustion engine is lower than a preset value, the high pressure supercharging A method for controlling an internal combustion engine with a sequential two-stage supercharger in which a valve of a bypass pipe connecting an inlet and an outlet of a high-pressure turbine of the engine is closed to operate the high-pressure supercharger.   During the warm-up, when the rotational speed of the internal combustion engine is equal to or higher than a preset value, a valve of a bypass pipe that connects an inlet and an outlet of a high-pressure turbine of the high-pressure turbocharger is opened to open the low-pressure stage. The method for controlling an internal combustion engine with a sequential two-stage supercharger according to claim 3, wherein the supercharger is operated.

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