JP2016125407A - Internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress leakage of a lubricant from a bearing portion of a low-speed exhaust turbosupercharger when operating a high-speed exhaust turbosupercharger included in a two-stage turbo engine to perform supercharging of intake air.SOLUTION: An internal combustion engine comprises: a low-speed exhaust turbosupercharger with a low-speed turbine and a low-speed compressor; a high-speed exhaust turbosupercharger with a high-speed turbine and a high-speed compressor; an exhaust bypass valve for opening and closing a bypass passage which bypasses the low-speed turbine; an intake bypass valve for opening and closing a bypass passage which bypasses the low-speed compressor; and a control device which performs control for closing, or reducing openings of, both the bypass valves in a low-rotation operation region to perform supercharging with the low-speed exhaust turbosupercharger, while opening, or increasing the openings of, both the bypass valves in a high-rotation operation region to perform supercharging with the high-speed exhaust turbosupercharger, as well as maintaining a number of rotation of the low-speed exhaust turbosupercharger at or near a predetermined number of rotation.SELECTED DRAWING: Figure 1

Description

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

  As an internal combustion engine for vehicles, a turbo engine provided with an exhaust turbocharger is known. The exhaust turbocharger is configured such that a drive turbine disposed on the exhaust passage side of the internal combustion engine and a compressor disposed on the intake passage side are coaxially connected and interlocked. The remaining energy of the exhaust is used to rotate the turbine, and thus the compressor impeller (compressor wheel), and pump the compressor so that the intake air is compressed (supercharged) and sent to the cylinder. Can do.

  Recently, a two-stage turbo (sequential turbo) engine that uses two exhaust turbochargers has also been developed (see, for example, the following patent document). In an in-line 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. On the exhaust passage, the turbine of the high-speed turbocharger is located downstream of the turbine of the low-speed turbocharger. An intake bypass passage that bypasses the compressor of the low-speed turbocharger is provided in the intake passage, and an exhaust bypass passage that bypasses the turbine of the low-speed turbocharger is also provided in the exhaust passage.

  In the operation region where the engine speed is relatively low, the intake bypass passage and the exhaust bypass passage are closed, and the intake air is supercharged by the low-speed turbocharger. On the other hand, in the operation region where the engine speed is relatively high, the intake bypass passage and the exhaust bypass passage are opened, and the intake air is supercharged by the high-speed turbocharger.

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

JP 2014-214732 A

  The present invention prevents leakage of lubricating oil 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 supercharging of the intake air. The intended purpose is to suppress it.

  In the present invention, a low-speed turbine that is arranged on the exhaust passage and rotates by utilizing the energy of the exhaust, and a low-speed turbine that is arranged on the intake passage and rotates by following the low-speed turbine to compress and compress the intake air. A low-speed exhaust turbocharger having a compressor as an element, a high-speed turbine that is disposed downstream of the low-speed turbine on the exhaust passage and rotates using the energy of the exhaust, and the low-speed turbine on the intake passage A high-speed exhaust turbocharger including a high-speed compressor that is arranged upstream of a compressor and rotates following the high-speed turbine to compress and compress the intake air, and an exhaust bypass passage that bypasses the low-speed turbine An exhaust bypass valve that opens and closes the engine, an intake bypass valve that opens and closes an intake bypass path that bypasses the low-speed compressor, and an engine speed. In the following low speed operation region, the exhaust bypass valve and the intake bypass valve are closed or the opening degree thereof is reduced, and supercharging of the intake air is performed by the low speed exhaust turbocharger, while the engine speed is predetermined. In the above high speed operation region, the exhaust bypass valve and the intake bypass valve are opened or the opening thereof is expanded to perform supercharging of the intake air by the high speed exhaust turbocharger, and the high speed exhaust turbocharger. Control for maintaining the rotational speed of the low-speed exhaust turbocharger when performing supercharging of intake air by the turbocharger at a rotational speed that does not cause lubricating oil leakage in the low-speed exhaust turbocharger An internal combustion engine comprising the apparatus.

  In the control by the control device when the supercharging of the intake air by the high-speed exhaust turbocharger is executed, the rotation speed of the low-speed exhaust turbocharger is set to the intake air supercharging by the low-speed exhaust turbocharger. By maintaining the engine speed, the engine speed is kept lower than the engine speed of the low-speed exhaust turbocharger when the maximum engine torque is output.

  Further, when supercharging the intake air by the high-speed exhaust turbocharger, the control device causes the differential pressure between the intake pressure on the upstream side and the intake pressure on the downstream side of the low-speed compressor to be a predetermined value or less. Thus, it is preferable to operate the exhaust bypass valve.

  According to the present invention, it is possible to suitably suppress leakage of lubricating oil from the bearing portion of the low-speed exhaust turbocharger when the high-speed exhaust turbocharger is operated to perform intake supercharging. .

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 | region of the internal combustion engine of the embodiment, and supercharging by an exhaust turbo supercharger.

  An embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an outline of an internal combustion engine for a vehicle in the present embodiment. The internal combustion engine of the present embodiment is a compression ignition type four-stroke engine such as a diesel engine or a HCCI (homogeneous-charge compression ignition) engine, and a plurality of cylinders 1 (one of which is shown in FIG. 1). Are shown). An injector 11 that directly injects fuel into the combustion chamber of the cylinder 1 is installed on the ceiling of the combustion chamber of each cylinder 1. 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.

  The intake passage 3 for supplying intake air takes in air from the outside and guides it to the intake port of each cylinder 1. On the intake passage 3, 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 upstream. Are arranged in this order.

  The exhaust passage 4 for discharging the exhaust guides 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 emission control device 41 includes a filter that removes particulate matter contained in the exhaust (Particulate Material) and a catalyst that promotes oxidation or reduction of harmful substances.

  The exhaust turbochargers 5 and 6 are configured such that the exhaust turbines 52 and 62 and the impellers of the compressors 51 and 61 are coaxially connected via a shaft and interlocked with each other. Then, the impellers of the turbines 52 and 62 and the compressors 51 and 61 are rotationally driven using the energy of the exhaust, and the compressor is pumped with the rotational force to compress and compress (supercharge) the intake air. 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 works in an operation region where the engine speed is relatively high. On the other hand, the exhaust turbocharger 6 is a low-speed turbocharger that works in an operation region 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 that bypasses the compressor 61 of the low-speed turbocharger 6 is provided, and a valve 37 that opens and closes 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.

  Further, the exhaust passage 4 also includes an exhaust bypass passage 43 that bypasses the turbine 62 of the low-speed turbocharger 6, and an exhaust bypass passage 44 that bypasses the turbine 52 of the high-speed turbocharger 5, and Exhaust bypass valves 45 and 46 for opening and closing the respective 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 and 46 may be referred to as WGV (Waste Gate Valve).

  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 negative pressure and an elastic biasing force by a built-in spring are applied to one surface of the diaphragm, and atmospheric pressure is applied to the other surface. The negative pressure is supplied from the vacuum pump 91. The vacuum pump 91 generates a negative pressure having a certain magnitude. Electromagnetic solenoid valves 372 and 462 are installed on pipes connecting the diaphragm actuators 371 and 461 and the vacuum pump 91, respectively. The magnitude of the negative pressure that actually acts on one surface of the diaphragms of the diaphragm actuators 371 and 461 varies depending on the opening degree of the electromagnetic solenoid valves 372 and 462. The opening degrees of the valves 37 and 46 change according to the difference between the differential pressure between the negative pressure and the atmospheric pressure acting on both surfaces of the diaphragm and the elastic biasing force of the spring that elastically biases the diaphragm. That is, the opening degree of the valves 37 and 46 can be operated 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 an electromagnetic valve.

  External EGR (Exhaust Gas Recirculation) devices 2 and 7 return a part of the exhaust gas flowing through the exhaust passage 4 to the intake passage 3 to be mixed 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 purification device 41 in the exhaust passage 4 to the upstream side of the compressor 51 of the high-speed turbocharger 5 in the intake passage 3. 21 and an EGR valve 22 that opens and closes the EGR passage 21 are included as elements. The EGR valve 22 controls the flow rate of the low-pressure loop EGR gas that flows through the EGR passage 21.

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

  In addition, an exhaust throttle valve 47 is installed in the exhaust passage 4 at a location downstream of the connection location of the low-pressure loop EGR passage 21. 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 varies depending on the degree of supercharging by the compressor 51. As a result, the flow rate of 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 thus the EGR rate, which is the ratio of EGR gas in the intake air charged in the cylinder 1, to the target value.

  An ECU (Electronic Control Unit) 0 serving as a control device for an internal combustion engine according to 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 the actual vehicle speed of the vehicle, a crank angle signal b output from an engine rotation sensor that detects the rotation angle of the crankshaft and the engine speed, and an accelerator pedal. The accelerator opening signal c output from a sensor that detects the amount of depression of the engine or the opening of the throttle valve 32 as an accelerator opening (in other words, a required engine torque or load), and in the surge tank 33 of the intake passage 3 (that is, The intake air temperature / intake pressure signal d output from the intake air temperature / intake pressure sensor for detecting the temperature and pressure (supercharging pressure) of the intake air (flowing into the cylinder 1), and output from the atmospheric pressure sensor for detecting the atmospheric pressure. At the atmospheric pressure signal e, the most upstream of the intake passage 3, that is, downstream of the air cleaner 31 and upstream of the connection point of the low pressure loop EGR passage 21. An air flow meter for detecting the flow rate and temperature of fresh air, a fresh air flow rate / temperature signal f output from a fresh air temperature sensor, an intake pressure downstream of the compressor 51 and upstream of the compressor 61 in the intake passage 3 (high-speed turbocharger) An intake pressure signal g output from an intake pressure sensor that detects a supercharging pressure by the machine 5, a cooling water temperature signal h output from a sensor that detects a cooling water temperature that indicates the temperature of the internal combustion engine, and the like are input.

  From the output interface of the ECU 0, the fuel injection signal i for the injector 11, the opening operation signal j for the throttle valve 32, the opening operation signal k for the EGR valve 22, and the opening operation signal for the EGR valve 72. Opening operation signal m for the electromagnetic solenoid valve 372 that controls the opening / closing drive of the signal l, VSV 37, opening operation signal n for the EVRV 45, and opening operation signal o for the electromagnetic solenoid valve 462 that controls the opening / closing drive of the VSV 46. The opening operation signal p and the like are output to the exhaust throttle valve 47.

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

  FIG. 2 shows the relationship between the operating range of the internal combustion engine of the present embodiment and the supercharging by the exhaust turbochargers 5 and 6. In FIG. 2, the horizontal axis represents the engine speed and the vertical axis represents the engine torque. In a region A1 where the accelerator opening is small and the engine torque output from the internal combustion engine is relatively small, the flow rate of the exhaust gas flowing through the exhaust passage 4 is small, and the exhaust turbochargers 5 and 6 do little or no work. Accordingly, the ECU 0 opens the VSVs 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 an atmospheric pressure obtained by referring to the atmospheric pressure signal e or a value in the vicinity thereof. Then, the loss due to the compressor 51 of the high-speed turbocharger 5 in the intake passage 3 is reduced, which can contribute to improvement in fuel efficiency.

  In the region A2 where the accelerator opening is larger than a certain level and the engine torque is larger than a certain level, but the engine speed is relatively low, supercharging by the low speed turbocharger 6 is performed. In the region A2, the ECU 0 fully closes the VSV 37 and closes 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 reduced, and the exhaust gas 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 that the intake pressure obtained by referring to the intake air temperature / intake pressure signal d follows the target boost pressure. In addition, the ECU 0 feedback-controls the opening degree of the VSV 46 so that the intake pressure upstream of the compressor 51 and downstream 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 an atmospheric pressure obtained by referring to the atmospheric pressure signal e or a value in the vicinity thereof. Then, the inlet side of the compressor 61 of the low-speed turbocharger 6 does not become negative pressure, the supercharging of the intake air charged in the cylinder 1 becomes efficient, and the compressor 51 of the high-speed turbocharger 5 Loss is reduced, which can contribute to improved fuel efficiency.

  In the region A4 where the accelerator opening is larger than a certain level, the engine torque is larger than a certain level, and the engine speed is relatively high, supercharging is performed by the high-speed turbocharger 5. In the area A4, the ECU 0 opens the VSV 37 and the EVRV 45 to open the bypass passages 36 and 43. Then, the VSV 46 is fully closed or its opening degree is reduced, and the exhaust gas flowing through the exhaust passage 4 is sufficiently introduced into the turbine 52. At this time, the intake pressure obtained by referring to the intake air temperature / intake pressure signal d and / or the intake pressure upstream of the compressor 51 and downstream of the compressor 61 obtained by referring to the intake pressure signal g are determined. The opening degree of the VSV 46 is feedback-controlled so as to follow the target boost pressure.

  A region A3 where the accelerator opening is larger than a certain level, the engine torque is larger than a certain level, and the engine speed is medium is a transient region between the low-speed turbo region A2 and the high-speed turbo region A4. In the transition region A3, supercharging is performed by both the low-speed turbocharger 6 and the high-speed turbocharger 5. In the process of transition from the low-speed turbo region A2 to the high-speed turbo region A4, as the engine speed increases, the respective openings of the VSV 37 and the EVRV 45 gradually increase so as to go from substantially fully closed to substantially fully open. At this time, the ECU 0 feedback-controls the opening degree of the EVRV 45 so that the intake pressure obtained by referring to the intake air temperature / intake pressure signal d follows the target boost pressure. In turn, the opening of the VSV 46 gradually decreases as the engine speed increases. The ECU 0 feedback-controls the opening degree of the VSV 46 so that the intake pressure upstream of the compressor 51 and downstream of the compressor 61, which is known with reference to the intake pressure signal g, follows the target boost pressure.

  In the high-speed turbo region A4, the turbocharging by the low-speed turbocharger 6 is not actively performed, but the rotation of the compressor 61 and the turbine 62 is maintained at a rotational 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 ceases or stops, lubricating oil leakage occurs (the intake bypass passage 36 is opened). And when the inlet side of the compressor 51 is in a negative pressure state, the lubricating oil is sucked).

  For this purpose, the ECU 0 keeps the opening degree of the VSV 37 that is the intake bypass valve as large as possible, while setting the opening degree of the EVRV 45 that is the exhaust bypass valve to the low-speed turbocharger 6 (the compressor 61 and the turbine 62). ) Is kept slightly narrower than fully opened so that the rotation number is maintained at a predetermined rotation number (for example, about 100,000 rpm) or a range in the vicinity thereof. 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 is within a predetermined value. Here, the predetermined rotation speed is set to be lower than the rotation speed of the low-speed turbocharger 6 at the point X at which the maximum engine torque is output in the low-speed turbo region A2. Further, when the rotational speed of the low-speed turbocharger 6 converges to the vicinity of the predetermined rotational speed, the differential pressure between the intake pressure on the upstream side of the compressor 61 and the intake pressure on the downstream side becomes equal to or less than a predetermined value.

  In the memory of the ECU 0, the operating area of the internal combustion engine [engine speed, accelerator opening (or engine torque, intake pressure in the surge tank 33, intake air amount filled in the cylinder 1), and VSV 37 are stored in advance. And map data defining the relationship with the respective opening degrees of the EVRV 45 is stored. In the high-speed turbo region A4, the ECU 0 searches the map using the parameter indicating the current operation region of the internal combustion engine as a key, knows the respective opening amounts of the VSV 37 and the EVRV 45, and sets the VSV 37 and the EVRV 45 to the opening amount. To operate. As a result, the rotational speed of the low-speed turbocharger 6 is maintained in the range near the predetermined rotational speed. The opening degree of VSV 37 and / or the opening degree of EVRV 45 obtained from the map data is determined based on the atmospheric pressure, the outside air temperature (new air temperature in the vicinity of the air cleaner 31), the cooling water temperature of the internal combustion engine, the lubricating oil temperature, or the like. You may make it correct | amend and operate VSV37 and / or EVRV45 to the corrected opening degree.

  In the present embodiment, a low-speed turbine 62 that is arranged on the exhaust passage 4 and rotates using the energy of the exhaust, and a low-speed turbine 62 that is arranged on the intake passage 3 and is rotated by the low-speed turbine 62 to pressurize the intake air. A low-speed exhaust turbocharger 6 having a low-speed compressor 61 as a component, and a high-speed turbine that is disposed on the exhaust passage 4 downstream of the low-speed turbine 62 and rotates using the energy of the exhaust gas. 52 and a high-speed exhaust turbocharger that includes a high-speed compressor 51 that is arranged upstream of the low-speed compressor 61 on the intake passage 3 and rotates in accordance with the high-speed turbine 52 to compress and compress the intake air. A feeder 5, an exhaust bypass valve 45 that opens and closes an exhaust bypass passage 43 that bypasses the low speed turbine 62, and an intake that bypasses the low speed compressor 61. The intake bypass valve 37 that opens and closes the bypass passage 36, and the exhaust bypass valve 45 and the intake bypass valve 37 are closed or reduced in the low-speed operation region A2 where the engine speed is equal to or less than a predetermined value. While the supercharging of the intake air is performed by the exhaust turbo supercharger 6, the exhaust bypass valve 45 and the intake bypass valve 37 are opened or the degree of opening thereof is increased in the high speed operation region A4 where the engine speed is a predetermined value or more. In addition to executing the supercharging of the intake air by the high-speed exhaust turbocharger 5, the rotational speed of the low-speed exhaust turbocharger 6 when executing the supercharging of the intake air by the high-speed exhaust turbocharger 5 is set. The low-speed exhaust turbocharger 6 includes a control device 0 that performs control to maintain at or near a predetermined rotational speed that does not cause leakage of lubricating oil. To constitute a combustion engine.

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

  In addition, in the control by the control device 0 when the supercharging of the intake air by the high speed exhaust turbocharger 5 is executed, the rotational speed of the low speed exhaust turbocharger 6 is set to the low speed exhaust turbocharger. The exhaust bypass valve is configured to keep the rotational speed lower than the rotational speed of the low-speed exhaust turbocharger 6 in a state where the maximum engine torque is output by executing supercharging of the intake air by the machine 6 (point X). 45 is operated so 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 61 is less than or equal to a predetermined value, so that the low-speed turbocharger is used in the high-speed turbo region A4. The turbine 61 of the machine 6 does not take away the energy of the exhaust gas easily, the efficiency of supercharging by the high-speed turbocharger 5 is increased, and the output of the internal combustion engine is increased and the fuel efficiency is improved.

  The present invention is not limited to the embodiment described in detail above. For example, in the above-described embodiment, the opening degree of the exhaust bypass valve 45 in the high-speed turbo region A4 is operated in accordance with map data prepared in advance, but the low-speed turbocharger 6 (the turbine 61 and the compressor 62 thereof). ) Can be measured via the sensor, the exhaust bypass valve 45 can be feedback controlled so that the actually measured rotational speed converges to a predetermined rotational speed.

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

  Other specific configurations of each part 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)
DESCRIPTION OF SYMBOLS 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)

A low-speed turbine arranged on the exhaust passage and rotating by utilizing the energy of the exhaust, and a low-speed compressor arranged on the intake passage and rotated in accordance with the low-speed turbine to compress and compress the intake air An exhaust turbocharger for low speed,
A high-speed turbine that is arranged downstream of the low-speed turbine on the exhaust passage and rotates using the energy of exhaust gas, and is arranged upstream of the low-speed compressor on the intake passage and is driven by the high-speed turbine to rotate. A high-speed exhaust turbocharger that uses a high-speed compressor that compresses and compresses intake air,
An exhaust bypass valve that opens and closes an exhaust bypass passage that bypasses the low-speed turbine;
An intake bypass valve that opens and closes an intake bypass passage that bypasses the low-speed compressor;
While closing the exhaust bypass valve and the intake bypass valve in a low speed operation region where the engine speed is less than a predetermined value or reducing the opening thereof, the supercharging of the intake air by the low speed exhaust turbocharger is performed, While opening the exhaust bypass valve and the intake bypass valve in a high speed operation region where the engine speed is equal to or higher than a predetermined value or increasing the opening thereof, supercharging of the intake air by the high-speed exhaust turbocharger is performed, Maintains the speed of the low-speed exhaust turbocharger when the supercharging of the intake air is performed by the high-speed exhaust turbocharger so that no lubricating oil leaks in the low-speed exhaust turbocharger. An internal combustion engine comprising a control device that performs control. In the control by the control device when the supercharging of the intake air by the high speed exhaust turbocharger is executed, the rotational speed of the low speed exhaust turbocharger is set to the supercharging of the intake air by the low speed exhaust turbocharger. The internal combustion engine according to claim 1, wherein the engine speed is maintained at a lower speed than that 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 so that a differential pressure between the intake pressure on the upstream side and the intake pressure on the downstream side of the low-speed compressor is equal to or less than a predetermined value. The internal combustion engine according to claim 1, wherein the exhaust bypass valve is operated.

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