JP6537271B2 - Internal combustion engine - Google Patents

Description

  The present invention relates to an internal combustion engine associated with an exhaust gas turbocharger.

  A turbo engine equipped with an exhaust gas turbocharger is known as an internal combustion engine for vehicles. The exhaust turbocharger is configured to coaxially couple and interlock a drive turbine disposed on the exhaust passage side of the internal combustion engine and a compressor disposed on the intake passage side. Then, by utilizing the remaining energy of the exhaust to rotate the turbine and, consequently, the impeller (compressor wheel) of the compressor and causing the compressor to perform a pumping action, the intake air is pressurized and compressed (supercharged) and fed to the cylinder Can.

  Recently, a two-stage turbo (sequential turbo) engine using two exhaust turbochargers in combination has also been developed (see, for example, the following patent documents). In a series two-stage turbo system, two exhaust turbochargers are connected in series. On the intake passage, the compressor of the high-speed turbocharger is located upstream of the compressor of the low-speed turbocharger. In the exhaust passage, the turbine of the high speed turbocharger is located downstream of the turbine of the low speed turbocharger. The intake passage is provided with an intake bypass passage bypassing the compressor of the low speed turbocharger, and the exhaust passage is also provided with an exhaust bypass passage bypassing the turbine of the low speed turbocharger.

  In the operating range where the engine speed is relatively low, the intake bypass passage and the exhaust bypass passage are closed to perform intake charging with the low speed turbocharger. On the other hand, in the operating range where the engine speed is relatively high, the intake bypass passage and the exhaust bypass passage are opened to perform intake charging with the high-speed turbocharger.

  When the high speed turbocharger supercharges the intake air, the compressed intake air flows through the intake bypass passage. At this time, negative pressure may be applied to the inlet side of the compressor of the low speed turbocharger, and there is a concern that the lubricating oil may be sucked out of the bearing of the low speed turbocharger.

JP, 2014-214732, A

  According to the present invention, the lubricating oil leaks from the bearing portion of the low speed exhaust turbocharger when the high speed exhaust turbocharger provided in the two-stage turbo engine is operated to perform intake charging. The purpose is to suppress.

In the present invention, a low speed turbine disposed on the exhaust passage and rotated using energy of the exhaust, and a low speed turbine disposed on the intake passage and rotated following the low speed turbine to pressurize and compress intake air A compressor for low-speed exhaust turbocharger, a high-speed turbine disposed downstream of the low-speed turbine above the exhaust passage and rotating using energy of the exhaust, and the low-speed turbine on the intake passage A high-speed exhaust turbocharger having a high-speed compressor disposed upstream of a compressor and driven by the high-speed turbine to rotate and pressurize the intake pressure as an element, and an exhaust bypass passage bypassing the low-speed turbine And an intake bypass valve for opening and closing an intake bypass passage bypassing the low speed compressor, and an engine speed The following low rotational speed operating region in the exhaust bypass valve and said intake air bypass valve closure to said low-speed exhaust turbo supercharger that opening the engine rotational speed to be reduced from that in a given or more high speed operation region while performing a supercharging of the intake air by the high rotational speed operating slightly squeezed while also expanding vital the intake than the opening in the low rotational speed operating region than fully open the opening of said exhaust bypass valve in the region The opening degree of the bypass valve is made larger than that in the low rotation operation region to perform intake air charging by the high speed exhaust turbocharger, and perform intake air charging by the high speed exhaust turbocharger. So that the speed of the low speed exhaust turbocharger does not decrease or stop at the low speed exhaust turbocharger to cause lubricating oil leakage And the constant rotational speed or the internal combustion engine and a control device for performing control for maintaining the range of the vicinity thereof.

  In the control by the control device when performing the supercharging of intake air by the high-speed exhaust turbocharger, the rotational speed of the low-speed exhaust turbocharger is determined by the excess of intake air by the low-speed exhaust turbocharger. By performing the feed, the rotational speed is maintained lower than the rotational speed of the low-speed exhaust turbocharger in the state where the maximum engine torque is output.

  In addition, when performing supercharging of intake air by the high-speed exhaust turbocharger, the control device determines that the differential pressure between the intake pressure on the upstream side and the intake pressure on the downstream side of the low-speed compressor is lower than a predetermined value. Preferably, the exhaust bypass valve is operated.

  According to the present invention, the leakage of lubricating oil from the bearing portion of the low speed exhaust turbocharger can be suitably suppressed when the high speed exhaust turbocharger is operated to carry out intake charging. .

BRIEF DESCRIPTION OF THE DRAWINGS The figure which shows the structure of the internal combustion engine for vehicles of one Embodiment of this invention. The figure which shows the relationship between the driving | operation area | range of the internal combustion engine of the embodiment, and the supercharging by an exhaust gas turbocharger.

  One embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an outline of a vehicle internal combustion engine in the present embodiment. The internal combustion engine of the present embodiment is, for example, a compression-ignition four-stroke engine such as a diesel engine or a HCCI (Homogeneous-Charge Compression Ignition) engine, and a plurality of cylinders 1 (FIG. Are shown). At the ceiling of the combustion chamber of each cylinder 1, an injector 11 for injecting fuel directly into the combustion chamber of the cylinder 1 is installed. Further, a glow plug (residual heat plug) 12 and a swirl control valve 13 are provided in the vicinity of the intake port of each cylinder 1.

  An intake passage 3 for supplying intake air takes in air from the outside and leads it to the intake port of each cylinder 1. An air cleaner 31, a compressor 51 of the exhaust turbocharger 5, a compressor 61 of the exhaust turbocharger 6, a water-cooled intercooler 35, an electronic throttle valve 32, a surge tank 33, and an intake manifold 34 are disposed on the intake passage 3 upstream. Are arranged in this order from.

  The exhaust passage 4 for discharging the exhaust leads the exhaust generated as a result of burning the fuel in the cylinder 1 from the exhaust port of each cylinder 1 to the outside. An exhaust manifold 42, an exhaust turbine 62 of the exhaust turbocharger 6, an exhaust turbine 52 of the exhaust turbocharger 5, and an exhaust purification device 41 are disposed on the exhaust passage 4. The exhaust gas purification device 41 includes a filter (Praticulate Filter) for removing particulate matter contained in exhaust gas, and a catalyst which promotes oxidation or reduction of harmful substances.

  The exhaust turbochargers 5 and 6 are configured to coaxially connect the exhaust turbines 52 and 62 and the impellers of the compressors 51 and 61 via shafts, and interlock them. Then, the turbines 52 and 62 and the impellers of the compressors 51 and 61 are rotationally driven using the energy of the exhaust, and the compressor exerts a pump action with the rotational force to pressurize and compress the intake air (supercharge). And feed it into cylinder 1.

  The internal combustion engine of the present embodiment is a so-called two-stage turbo (sequential turbo) engine including two exhaust turbochargers 5 and 6. The exhaust turbocharger 5 is a high-speed turbocharger that performs work in an operating range where the engine speed is relatively high. On the other hand, the exhaust turbocharger 6 is a low-speed turbocharger that performs work in an operating range where the engine speed is relatively low. The capacity of the low speed turbocharger 6 is smaller than the capacity of the high speed turbocharger 5.

  In the intake passage 3, an intake bypass passage 36 bypassing the compressor 61 of the low speed turbocharger 6 is provided, and a valve 37 for opening and closing the outlet of the intake bypass passage 36 is provided. The intake bypass valve 37 controls the flow rate of intake air flowing through the intake bypass passage 36. There is no intake bypass passage that bypasses the compressor 51 of the high-speed turbocharger 5.

  Furthermore, an exhaust bypass passage 43 bypassing the turbine 62 of the low speed turbocharger 6 and an exhaust bypass passage 44 bypassing the turbine 52 of the high speed turbocharger 5 are also provided in the exhaust passage 4, Exhaust bypass valves 45 and 46 for opening and closing the inlets of the exhaust bypass passages 43 and 44 are provided. The valve 45 controls the flow rate of exhaust flowing through the exhaust bypass passage 43, and the valve 46 controls the flow rate of exhaust flowing through the exhaust bypass passage 44. The exhaust bypass valves 45, 46 may be referred to as WGV (Waste Gate Valve).

  The valves 37 and 46 are VSV (Vaccum Switching Valve) using negative pressure actuators 371 and 461. The negative pressure actuators 371 and 461 are diaphragm actuators, and a negative pressure and an elastic biasing force by a built-in spring are applied to one surface of the diaphragm, and an atmospheric pressure is applied to the other surface. Negative pressure is supplied from a vacuum pump 91. The vacuum pump 91 generates a negative pressure of a certain size. Electromagnetic solenoid valves 372 and 462 are installed on the conduits connecting the diaphragm actuators 371 and 461 and the vacuum pump 91, respectively. The magnitude of the negative pressure actually acting on one surface of the diaphragms of the diaphragm actuators 371 and 461 changes in accordance with the opening degree of the electromagnetic solenoid valves 372 and 462. The degree of opening of the valves 37 and 46 changes in accordance with the difference between the differential pressure of negative pressure and atmospheric pressure acting on both sides of the diaphragm and the elastic biasing force of the spring that elastically biases the diaphragm. That is, it is possible to operate the opening degree of the valves 37 and 46 through the operation of the opening degree of the electromagnetic solenoid valves 372 and 462.

  On the other hand, the valve 45 is an EVRV (Electric Vacuum Regulating Valve) which is a solenoid valve.

  The external EGR (Exhaust Gas Recirculation) devices 2 and 7 recirculate a part of the exhaust flowing through the exhaust passage 4 to the intake passage 3 and mix them with the intake air. The internal combustion engine of this embodiment includes two EGR devices 2 and 7. The EGR device 2 realizes a so-called low pressure loop EGR, and communicates the downstream side of the exhaust gas purification device 41 in the exhaust passage 4 with the upstream side of the compressor 51 of the high speed turbocharger 5 in the intake passage 3. 21 and an EGR valve 22 for opening and closing the EGR passage 21 as elements. The EGR valve 22 controls the flow rate of the low pressure loop EGR gas flowing through the EGR passage 21.

  The EGR device 7 realizes a so-called high pressure loop EGR, and communicates the upstream side of the turbine 62 of the low speed turbocharger 6 in the exhaust passage 4 with the downstream side of the intercooler 35 in the intake passage 3 The elements include an EGR valve 72 that opens and closes the EGR passage 71. The EGR valve 72 controls the flow rate of the high pressure loop EGR gas flowing through the EGR passage 71.

  In addition, an exhaust throttle valve 47 is installed at a position downstream of the connection point of the low pressure loop EGR passage 21 in the exhaust passage 4. The pressure on the upstream side of the compressor 51 in the intake passage to which the low pressure loop EGR passage 21 is connected fluctuates in accordance with the degree of supercharging by the compressor 51. As a result, the flow rate of the EGR gas flowing through the low pressure loop EGR passage 21 changes. The exhaust throttle valve 47, together with the EGR valve 22, functions to converge the flow rate of the low pressure loop EGR gas and, consequently, the EGR rate which is the ratio of the EGR gas occupied in the intake air charged into the cylinder 1 to a target value.

  An ECU (Electronic Control Unit) 0, which is a control device of an internal combustion engine of the present embodiment, is a microcomputer system having a processor, a memory, an input interface, an output interface, and the like.

  The input interface of the ECU 0 includes a vehicle speed signal a output from a vehicle speed sensor that detects an actual vehicle speed of the vehicle, a crank angle signal b output from an engine rotation sensor that detects a rotation angle of a crankshaft and an engine rotational speed, and an accelerator pedal. The accelerator opening signal c output from a sensor that detects the stepping amount of the engine or the opening of the throttle valve 32 as the accelerator opening (in other words, required engine torque or load), in the surge tank 33 of the intake passage 3 (ie , An intake air temperature / intake pressure signal d output from an intake air temperature / intake air pressure sensor that detects the temperature and pressure (supercharge pressure) of intake air flowing into the cylinder 1; an atmospheric pressure sensor that detects atmospheric pressure Atmospheric pressure signal e, the most upstream of the intake passage 3, that is, the downstream of the air cleaner 31 and the upstream of the connection point of the low pressure loop EGR passage 21. Air flow meter for detecting fresh air flow rate and temperature, new air flow rate / temperature signal f outputted from new air temperature sensor, pressure of intake air downstream of compressor 51 of intake passage 3 and upstream of compressor 61 An intake pressure signal g output from an intake pressure sensor for detecting the supercharging pressure by the engine 5 and a cooling water temperature signal h output from a sensor for detecting a cooling water temperature indicative of the temperature of the internal combustion engine are input.

  From the output interface of the ECU 0, the fuel injection signal i to the injector 11, the opening operation signal j to the throttle valve 32, the opening operation signal k to the EGR valve 22, the opening operation to the EGR valve 72 The signal l, the opening operation signal m for the electromagnetic solenoid valve 372 for controlling the opening and closing of the VSV 37, the opening operation signal n for the EVRV 45, and the opening operating signal for the electromagnetic solenoid valve 462 for opening and closing the VSV 46 And outputs an opening operation signal p or the like to the exhaust throttle valve 47.

  The processor of the ECU 0 interprets and executes a program stored in advance in the memory, calculates operating parameters, and controls the operation of the internal combustion engine. The ECU 0 obtains various information a, b, c, d, e, f, g, h necessary for the operation control of the internal combustion engine through the input interface, obtains the engine speed, and fills the cylinder 1 Estimate the fuel injection amount commensurate with the amount of fresh air intake. Also, along with that, the fuel injection timing (including the number of fuel injection per one combustion), the fuel injection pressure, the required EGR rate (or the amount of EGR), the target supercharging of supercharging by the exhaust turbochargers 5 and 6 Determine various operation parameters such as pressure. The ECU 0 applies various control signals i, j, k, l, m, n, o, p corresponding to the operation parameters via the output interface.

  FIG. 2 shows the relationship between the operating region of the internal combustion engine of the present embodiment and the supercharging by the exhaust turbochargers 5 and 6. Referring to FIG. 2, the horizontal axis is the engine speed, and the vertical axis is the engine torque. In a region A1 where the accelerator opening is small and the engine torque output by the internal combustion engine is relatively small, the flow rate of the exhaust flowing through the exhaust passage 4 is small, and the exhaust turbochargers 5 and 6 do little or no work. Therefore, the ECU 0 opens the VSV 37 and 46 and the EVRV 45, respectively, and opens the bypass passages 36, 43 and 44 to reduce the pumping loss of the internal combustion engine as much as possible. At this time, the opening degree of the VSV 46 may be feedback-controlled so that the intake pressure downstream of the compressor 51 and upstream of the compressor 61, which is known with reference to the intake pressure signal g, becomes the target intake pressure. The target intake pressure is preferably set to a value at or near atmospheric pressure known with reference to the atmospheric pressure signal e. In other words, the loss due to the compressor 51 of the high-speed turbocharger 5 in the intake passage 3 becomes smaller, which can contribute to the improvement of the fuel consumption performance.

Although the accelerator opening degree is larger than a certain degree and the engine torque is also larger than a certain degree, supercharging by the low speed turbocharger 6 is performed in the region A2 where the engine rotational speed is relatively low. In the region A2, the ECU 0 fully closes the VSV 37 to close the intake bypass passage 36, and causes all the intake air flowing through the intake passage 3 to flow into the compressor 61. At the same time, the EVRV 45 is fully closed or its opening degree is narrowed, and the exhaust flowing through the exhaust passage 4 is sufficiently introduced into the turbine 62. At this time, the opening degree of the EVRV 45 may be feedback-controlled so as to make the intake pressure known with reference to the intake air temperature / intake pressure signal d follow the target boost pressure. In addition, ECU0 is be learned with reference to the intake pressure signal g, as the intake pressure of the upper stream of the lower flow and compressor 61 of the compressor 51 becomes the target intake pressure, the feedback control of the opening degree of VSV46 . The target intake pressure is preferably set to a value at or near atmospheric pressure known with reference to the atmospheric pressure signal e. In other words, the inlet side of the compressor 61 of the low speed turbocharger 6 does not become negative pressure, and the efficiency of supercharging of the intake air charged into the cylinder 1 is improved, and the compressor 51 of the high speed turbocharger 5 is used. The loss is reduced, which can contribute to the improvement of the fuel efficiency.

The supercharging by the high-speed turbocharger 5 is performed in an area A4 where the accelerator opening degree is greater than a certain degree, the engine torque is also greater than a certain degree, and the engine rotational speed is relatively high. In the area A4, the ECU 0 opens the VSV 37 and the EVRV 45 to open the bypass passages 36, 43. Then, the VSV 46 is fully closed or its opening degree is reduced, and the exhaust flowing through the exhaust passage 4 sufficiently flows into the turbine 52. In this case, absorption of the intake air temperature-intake pressure signal the intake pressure is be learned with reference to d, and / or the upper stream of the lower flow and compressor 61 of the compressor 51 be learned with reference to the intake pressure signal g The opening degree of the VSV 46 is feedback-controlled so that the air pressure follows the target boost pressure.

The region A3 where the accelerator opening is greater than a certain degree, the engine torque is also greater than a certain extent, and the engine speed is medium is a transition region between the low speed turbo region A2 and the high speed turbo region A4 described above. In this transient range A3, supercharging is performed by both the low speed turbocharger 6 and the high speed turbocharger 5. In the process of transitioning from the low speed turbo area A2 to the high speed turbo area A4, as the engine speed increases, the opening degree of each of the VSV 37 and the EVRV 45 gradually widens from approximately fully closed to approximately fully open. At this time, the ECU 0 performs feedback control of the opening degree of the EVRV 45 so as to make the intake pressure known with reference to the intake air temperature / intake pressure signal d follow the target boost pressure. In turn, the opening degree of the VSV 46 gradually decreases as the engine speed increases. ECU0 is be learned with reference to the intake pressure signal g, so as to follow the intake pressure of the upper stream of the lower flow and compressor 61 of the compressor 51 to the target boost pressure, the feedback control of the opening degree of the VSV 46.

  In the high speed turbo range A4, although supercharging by the low speed turbocharger 6 is not actively performed, the rotation of the compressor 61 and the turbine 62 is maintained at a rotation speed that does not cause excessive rotation. This is based on the assumption that the bearing seal of the low-speed turbocharger 6 rotates the shaft, and if the rotation of the compressor 61 and the turbine 62 decreases or stops, lubricating oil leaks (the intake bypass passage 36 opens) When the pressure on the inlet side of the compressor 51 becomes negative, the lubricating oil is absorbed.

  Therefore, the ECU 0 opens the opening degree of the intake bypass valve VSV 37 as large as possible, while setting the opening degree of the exhaust bypass valve EVRV 45 to the compressor 61 and the turbine 62 of the low speed turbocharger 6. In order to maintain the number of revolutions in the range of a predetermined number of revolutions (e.g., about 100,000 rpm) or in the vicinity thereof, an operation of squeezing a little more than full opening is performed. In other words, the ECU 0 controls the opening degree of the EVRV 45 so that the absolute value of the difference between the rotational speed of the low speed turbocharger 6 and the predetermined rotational speed falls below a predetermined value. Here, the predetermined rotation speed is set to a rotation speed lower than the rotation speed of the low speed turbocharger 6 at a point X at which the maximum engine torque is output in the low speed turbo region A2. In addition, the differential pressure between the intake pressure on the upstream side and the intake pressure on the downstream side of the compressor 61 becomes less than or equal to a predetermined value when the rotational speed of the low speed turbocharger 6 converges near the predetermined rotational speed.

  In the memory of the ECU 0, the operating range of the internal combustion engine [engine rotational speed, accelerator opening degree (or engine torque, intake pressure in the surge tank 33, intake (fresh air) amount charged to the cylinder 1)] And map data that defines the relationship between the opening degree of each of the EVRVs 45 is stored. In the high speed turbo range A4, the ECU 0 searches the map using the parameter representing the current operating range of the internal combustion engine as a key, obtains the respective opening degrees of the VSV 37 and EVRV 45, and opens the VSV 37 and EVRV 45 To operate. As a result, the rotation speed of the low speed turbocharger 6 is maintained in the range near the predetermined rotation speed. The degree of opening of VSV 37 and / or the degree of opening of EVRV 45 obtained from the map data is based on the atmospheric pressure and ambient temperature (new air temperature near air cleaner 31), the cooling water temperature of the internal combustion engine, the lubricating oil temperature, etc. The VSV 37 and / or the EVRV 45 may be operated to the corrected opening degree.

  In this embodiment, a low speed turbine 62 disposed on the exhaust passage 4 and rotated using energy of the exhaust, and a low speed turbine disposed on the intake passage 3 and rotated following the low speed turbine 62 to pressurize the intake air. A low speed exhaust turbocharger 6 composed of a low speed compressor 61 for compression, and a high speed turbine disposed downstream of the low speed turbine 62 on the exhaust passage 4 and rotating using energy of the exhaust 52 and an exhaust gas turbo charger for high speed that is disposed upstream of the low speed compressor 61 on the intake passage 3 and is driven by the high speed turbine 52 to rotate and pressurize the intake air by using the high speed compressor 51 as an element A feeder 5, an exhaust bypass valve 45 for opening and closing an exhaust bypass passage 43 for bypassing the low speed turbine 62, and a suction for bypassing the low speed compressor 61. The exhaust bypass valve 45 and the intake bypass valve 37 are closed or the opening degree thereof is reduced in the low speed operation region A2 where the engine rotational speed is less than a predetermined value for the low speed While performing supercharging of intake air by the exhaust turbocharger 6, the exhaust bypass valve 45 and the intake bypass valve 37 are opened or the opening degree thereof is expanded in the high rotation operation area A4 where the engine rotational speed is a predetermined speed or more. The rotational speed of the low speed exhaust turbocharger 6 at the time of executing the supercharging of intake air by the high speed exhaust turbocharger 5 and executing the supercharging of the intake by the high speed exhaust turbocharger 5 The control device 0 performs control to maintain the low speed exhaust turbocharger 6 at or near a predetermined rotation speed so as not to cause lubricating oil leakage. To constitute a combustion engine.

  According to the present embodiment, the high speed exhaust turbocharger 5 provided in the two-stage turbo engine is operated to perform intake air charging from the bearing portion of the low speed exhaust turbocharger 6. Leakage of lubricating oil can be suppressed.

  In addition, in the control by the control device 0 at the time of executing the supercharging of intake air by the high speed exhaust turbocharger 5, the rotational speed of the low speed exhaust turbocharger 6 is set to the low speed exhaust turbocharger. The exhaust bypass valve is maintained at a rotational speed lower than the rotational speed of the low speed exhaust turbocharger 6 in a state (point X) where the maximum engine torque is output by performing intake air charging by the engine 6 (point X) The differential pressure between the intake pressure on the upstream side and the intake pressure on the downstream side of the low speed compressor 61 is controlled to be less than or equal to a predetermined value by operating the opening degree of 45. The turbine 61 of the machine 6 does not take energy of the exhaust gas intentionally, the efficiency of supercharging by the high speed turbocharger 5 is enhanced, and the output of the internal combustion engine is improved and the fuel consumption performance is improved.

  The present invention is not limited to the embodiments detailed above. For example, in the above embodiment, the opening degree of the exhaust bypass valve 45 in the high speed turbo area A4 is operated according to map data formulated in advance, but the low speed turbocharger 6 (the turbine 61 and the compressor 62 When it is possible to actually measure the rotational speed of the) through the sensor, the exhaust bypass valve 45 can be feedback-controlled so that the measured rotational speed converges to a predetermined rotational speed.

  Furthermore, in the high speed turbo area A4, the supercharging pressure in the surge tank 33 known by referring to the intake air temperature / intake pressure signal d, and the downstream of the compressor 51 known by referring to the intake pressure signal g It is also conceivable to feedback-control the exhaust bypass valve 45 so that the differential pressure with the supercharging pressure upstream of the compressor 61 is less than or equal to a predetermined pressure.

  The specific configurations of the other components can be variously modified without departing from the spirit of the present invention.

  The present invention can be applied to an internal combustion engine mounted on a vehicle or the like.

0 ... Control unit (ECU)
1 ... cylinder 3 ... intake passage 36 ... intake bypass passage 37 ... intake bypass valve (VSV)
4 ... Exhaust passage 43 ... Exhaust bypass passage 45 ... Exhaust bypass valve (EVRV)
5: High-speed exhaust turbocharger 51: High-speed compressor 52: High-speed turbine 6 .... Low-speed exhaust turbocharger 61: Low-speed compressor 62: Low-speed turbine

Claims (3)

The low-speed turbine is disposed on the exhaust passage and rotates using energy of the exhaust, and the low-speed compressor is disposed on the intake passage and rotates following the low-speed turbine to pressurize and compress the intake. Low speed exhaust turbochargers,
A high speed turbine disposed downstream of the low speed turbine on the exhaust passage and rotated using energy of the exhaust, and upstream of the low speed compressor on the intake passage and rotated following the high speed turbine High-speed exhaust turbochargers that use high-speed compressors to pressurize and
An exhaust bypass valve for opening and closing an exhaust bypass passage bypassing the low speed turbine;
An intake bypass valve that opens and closes an intake bypass passage that bypasses the low speed compressor;
The exhaust bypass valve and the intake bypass valve are closed or the opening degree thereof is reduced in the low rotation operation range where the engine rotation speed is lower than a predetermined speed or lower than that in the high rotation operation region where the engine rotation speed is more than the predetermined speed while performing a supercharging of the intake air by the exhaust turbocharger, the high speed operation while slightly squeezing than fully open the opening of said exhaust bypass valve in the region than in the low rotational speed operating region thereof opening In addition, the opening degree of the intake bypass valve is expanded more than that in the low rotation operation region to perform intake charging by the high speed exhaust turbocharger, and intake by the high speed exhaust turbocharger. Rotation speed of the low speed exhaust turbocharger at the time of performing supercharging of the engine, the rotation of the low speed exhaust turbocharger decreases or stops, and the lubricating oil leaks An internal combustion engine and a control device for performing control for maintaining the range of the predetermined rotation speed or near so as not to cause. In the control by the control device when performing the supercharging of intake air by the high-speed exhaust turbocharger, the rotational speed of the low-speed exhaust turbocharger is determined by the intake turbocharging by the low-speed exhaust turbocharger. The internal combustion engine according to claim 1, wherein the rotational speed is maintained lower than the rotational speed of the low-speed exhaust turbocharger in a state where the maximum engine torque is output by executing. When performing supercharging of intake air by the high-speed exhaust turbocharger, the control device is configured such that the differential pressure between the intake pressure on the upstream side and the intake pressure on the downstream side of the low-speed compressor is less than or equal to a predetermined value. The internal combustion engine according to claim 1, wherein the exhaust bypass valve is operated.

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