JP2006090174A - Exhaust gas turbo charger for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust turbo charger for an internal combustion engine capable of exhibiting enhanced supercharging responsiveness since the speed of an engine is low. <P>SOLUTION: This exhaust turbo charger is equipped with a compressor 17 provided in an intake passage of the internal combustion engine and pressurizing intake gas, an exhaust turbine 24 provided in an exhaust passage of the internal combustion engine and rotated and driven by the exhaust gas, and a compressor driving means 66 for driving the compressor so as to have the speed of the compressor equal to or more than a target lowest speed at least by a power source different from the exhaust gas. The exhaust turbo charger is further provided with a bypass passage 68 for bypassing the compressor, and a bypass valve 69 for opening and closing the bypass passage; and the bypass valve is opened and the compressor driving means drives the compressor when an engine load is low. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

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

  An exhaust turbocharger of an internal combustion engine supercharges intake gas by using the pressure of exhaust gas discharged from the internal combustion engine. When the engine speed is low, the flow rate of the exhaust gas discharged from the engine body is small, and the pressure of the exhaust gas is also low. Accordingly, in the case of rapid acceleration when the engine speed is low, the increase in the exhaust gas pressure is delayed, and accordingly, the increase in the supercharging pressure is also delayed. In particular, in an internal combustion engine equipped with an exhaust turbocharger, the compression ratio is set to be low by the amount of supercharging by the exhaust turbocharger. In such a case, while the increase in supercharging pressure is delayed, the internal combustion engine Output torque is low.

  Therefore, in the supercharging device described in Patent Document 1, a hydraulic turbine is provided on the shaft of the exhaust turbocharger, and the hydraulic oil pressurized by a hydraulic pump connected to the engine body is injected into the hydraulic turbine, thereby rotating the engine. The exhaust turbocharger is supercharged from a low number. In addition, in order to prevent the compressor of the exhaust turbocharger from over-rotating by the hydraulic turbine, a bypass passage for bypassing the compressor is provided in the intake passage, and the rotation speed of the compressor is likely to exceed the allowable value. In this case, the bypass passage is opened so that the intake gas on the downstream side of the compressor is returned to the upstream side of the compressor.

JP-A-6-323153 JP-A-1-177413 JP 2002-195046 A

  By the way, when the internal combustion engine is performing idling operation or low load operation, the output torque required for the internal combustion engine is small, and it is not necessary to supercharge the intake gas. For this reason, in the supercharging device described in Patent Document 1, when the engine load is low, a hydraulic pump for pressurizing the hydraulic oil is disconnected from the engine body so as not to pressurize the hydraulic oil.

  However, in this case, for example, if a vehicle equipped with an internal combustion engine needs to be accelerated rapidly, that is, if the engine load suddenly increases, the hydraulic pump must first be connected to the engine body to pressurize the hydraulic oil. Don't be. It takes time until the hydraulic oil is actually pressurized after the hydraulic pump is connected to the engine body, and therefore it takes time to drive the compressor of the exhaust turbocharger by the hydraulic turbine. That is, even with the supercharging device described in Patent Document 1, the supercharging response is not high, and there is a time lag from when the throttle pedal is depressed until the output torque actually increases.

  Accordingly, an object of the present invention is to provide an exhaust turbocharger for an internal combustion engine having high supercharging response from when the engine speed is low.

In order to solve the above-mentioned problems, in the first invention, a compressor that is provided in an intake passage of an internal combustion engine and pressurizes intake gas, and an exhaust turbine that is provided in the exhaust passage of the internal combustion engine and is driven to rotate by exhaust gas And an exhaust gas turbocharger for an internal combustion engine that bypasses the compressor by a compressor driving means for driving the compressor so that the rotational speed of the compressor becomes at least the target minimum rotational speed by a power source different from the exhaust gas. A bypass passage and a bypass valve for opening and closing the bypass passage are further provided, and when the engine load is low, the bypass valve is opened and the compressor driving means drives the compressor. did.
According to the first invention, the compressor is driven to rotate by the compressor driving means even when the engine load is low. Therefore, immediately after the engine load suddenly increases, the compressor is rotated at the target minimum speed, and the intake gas can be sufficiently supercharged. Therefore, the supercharging response is high, and there is almost no lime lag from the increase in engine load to the increase in supercharging pressure.
Further, when the engine load is low, the required torque of the internal combustion engine is small, so that it is not necessary to supercharge the intake gas. However, if the compressor is driven to rotate when the engine load is low, the intake gas is usually supercharged and the load for driving the compressor becomes large. On the other hand, according to the first invention, when the engine load is low, the bypass valve is opened. When the bypass valve is opened, most of the intake gas flows without going through the compressor. As a result, the intake gas is not supercharged and the load on the drive of the compressor is reduced. As a result, energy required for driving the compressor is reduced, and fuel efficiency is improved.
The “target minimum rotational speed” is a rotational speed at which a certain amount of intake gas can be supercharged by at least the compressor, and changes according to the engine rotational speed. The “compressor driving means” is, for example, an electric motor or a hydraulic device that can be rotationally driven by the compressor.

According to a second invention, in the first invention, when the engine load becomes a high load, the bypass valve is closed and the compressor is simply driven by exhaust gas through the exhaust turbine. The compressor driving means drives the compressor while the rotational speed of the compressor does not reach the target minimum rotational speed.
For example, when the engine speed is low, even if the engine load suddenly increases, the flow rate of the exhaust gas discharged from the engine body is small and the pressure of the exhaust gas is low. Depending on the exhaust turbine, the compressor may not be able to rotate enough to supercharge the intake gas. According to the second invention, when the compressor load cannot be sufficiently rotated by the exhaust turbine when the engine load becomes high, the compressor speed is maintained at the target minimum speed by the compressor driving means. . For this reason, even when the engine load suddenly increases when the engine speed is low, the intake gas can be sufficiently supercharged.

  In a third invention, in the first or second invention, a one-way clutch is provided between the exhaust turbine of the exhaust turbocharger and the compressor, and the rotation of the exhaust turbine is transmitted to the compressor. The rotation of the compressor is not transmitted to the exhaust turbine.

  According to the present invention, since the compressor is rotated at the target minimum speed immediately after the engine load suddenly increases, the supercharging response is high, and from the increase of the engine load to the increase of the supercharging pressure. There is almost no lime rug. Therefore, an exhaust turbocharger for an internal combustion engine having high supercharging response from when the engine speed is low is provided.

  The exhaust turbocharger of the present invention will be described in detail below with reference to the drawings. FIG. 1 is an overall view of an internal combustion engine including an exhaust turbocharger according to the present invention. The illustrated internal combustion engine is a direct injection type spark ignition type internal combustion engine, but the present invention can also be applied to other internal combustion engines such as a port injection type spark ignition type internal combustion engine and a compression ignition type internal combustion engine. It is.

  Referring to FIG. 1, 1 is an engine body, 2 is a cylinder block, 3 is a piston that reciprocates in the cylinder block 2, 4 is a cylinder head fixed on the cylinder block 2, and 5 is a piston 3 and a cylinder head 4. A combustion chamber formed therebetween, 6 is an intake valve, 7 is an intake port, 8 is an exhaust valve, and 9 is an exhaust port. As shown in FIG. 1, a spark plug 10 is arranged at the center of the cylinder inner wall surface of the cylinder head 4, and a fuel injection valve 11 is arranged around the cylinder inner wall surface of the cylinder head 4. A cavity 12 extending from the lower side of the fuel injection valve 11 to the lower side of the spark plug 10 is formed on the top surface of the piston 3.

  The intake port 7 of each cylinder is connected to a surge tank 14 via a corresponding intake branch pipe 13, and the surge tank 14 is connected to an outlet of a compressor 17 of an exhaust turbocharger 16 via an intake pipe 15. An inlet portion of the compressor 17 is connected to an air cleaner 19 via an intake pipe 18. A throttle valve 21 driven by a step motor 20 is disposed in the intake pipe 15 between the surge tank 14 and the exhaust turbocharger 16. An air flow meter 22 for detecting the flow rate of air (intake gas) sucked into the combustion chamber 5 is disposed in the intake pipe 18 upstream of the exhaust turbocharger 16. On the other hand, the exhaust port 9 is connected to the inlet portion of the exhaust turbine 24 of the exhaust turbocharger 16 via the exhaust branch pipe 23. An outlet portion of the exhaust turbine 24 is connected to a casing 27 containing a catalyst 26 through an exhaust pipe 25.

  The electronic control unit (ECU) 40 comprises a digital computer, and is connected to each other by a bidirectional bus 41, a ROM (read only memory) 42, a RAM (random access memory) 43, a CPU (microprocessor) 44, an input port 45, And an output port 46. The output signal of the air flow meter 22 is input to the input port 45 via the corresponding AD converter 47.

  A load sensor 51 that generates an output voltage proportional to the amount of depression is connected to the accelerator pedal 50. The output voltage of the load sensor 51 is input to the input port 45 via the corresponding AD converter 47. The input port 45 is connected to a crank angle sensor 52 that generates an output pulse each time the crankshaft rotates, for example, 30 °. On the other hand, the output port 46 is connected to the spark plug 10, the fuel injection valve 11, and the step motor 20 via a corresponding drive circuit 48, and these operations are controlled by the ECU 40.

  2 and 3 are enlarged views schematically showing the exhaust turbocharger 16. As described above, the exhaust turbocharger 16 includes the compressor 17 and the exhaust turbine 24. The compressor 17 includes a compressor impeller 61 and a housing communicated with the intake pipes 15 and 18, and the exhaust turbine 24 includes a turbine wheel 62 and a housing communicated with the exhaust pipes 23 and 25. The compressor impeller 61 and the turbine wheel 62 are connected by a shaft 63. A one-way clutch 64 is disposed at the connecting portion between the turbine wheel 62 and the shaft 63, and the rotation of the turbine wheel 62 is transmitted to the compressor impeller 62, but the rotation of the compressor impeller 61 is not transmitted to the turbine wheel. Therefore, the compressor 17 may rotate at a higher speed than the exhaust turbine 24, but the exhaust turbine 24 does not rotate at a higher speed than the compressor 17.

  An electric motor 66 is connected to the shaft 63 via a speed increasing gear 65, and the shaft 63 is rotated by the rotation of the electric motor 66. The electric motor 66 is connected to the output port 46 of the ECU 40 and its operation is controlled by the ECU 40. As described above, since the rotation of the shaft 63 is not transmitted to the turbine wheel 62 by the one-way clutch 64, the rotation of the electric motor 66 is transmitted only to the compressor impeller 61. The electric motor 66 is also provided with a one-way clutch 67, and the rotation of the electric motor 66 is transmitted to the compressor impeller 61, but the rotation of the compressor impeller 61 is not transmitted to the electric motor 66. Therefore, although the compressor 17 may rotate at a higher speed than the rotation speed obtained by multiplying the rotation speed of the electric motor 66 by the speed increase ratio of the speed increasing gear 65, the electric motor 66 changes the speed of the compressor 17 to the speed increase ratio. It will not rotate at a higher speed than the number of revolutions divided by.

  That is, the compressor 17 has the higher one of the number of revolutions of the exhaust turbine 24 or the number of revolutions of the electric motor 66 multiplied by the speed increasing ratio of the speed increasing gear (hereinafter referred to as “speed increasing speed”). It can be rotated at the number of rotations.

  An intake bypass passage 68 for bypassing the compressor 17 is provided between the intake pipe 18 upstream of the exhaust turbocharger 16 and the intake pipe 15 downstream of the exhaust turbocharger 16. A bypass valve 69 for opening and closing the intake bypass passage 68 is disposed. Therefore, when the bypass valve 69 is opened, the intake gas passes through the intake bypass passage 68 without passing through the compressor 17 of the exhaust turbocharger 16 and is located downstream of the exhaust turbocharger 16 from the intake pipe 18 upstream of the exhaust turbocharger 16. It flows to the intake pipe 15. Accordingly, at this time, the intake gas is not supercharged by the compressor 17. On the other hand, when the bypass valve 69 is closed, the intake gas flows from the intake pipe 18 to the intake pipe 15 via the compressor 17. At this time, the intake gas is supercharged according to the rotation of the compressor 17.

  On the other hand, an exhaust bypass passage 70 for bypassing the exhaust turbine 24 is provided between the exhaust pipe 23 upstream of the exhaust turbocharger 16 and the exhaust pipe 25 downstream of the exhaust turbocharger 16. A waste gate valve 71 for opening and closing the exhaust bypass passage 70 is provided. The wastegate valve 71 is opened when the supercharging pressure in the intake pipe 15 becomes a constant pressure, and is adjusted so that the supercharging pressure does not increase any more. As the exhaust turbocharger 16 rotates at a higher speed, the boost pressure becomes higher. However, if the boost pressure becomes too high, the internal combustion engine is damaged, so that the waste gate valve 71 does not increase the boost pressure beyond a certain level. It is something to control.

  By the way, the rotational speed of the compressor 17 of the exhaust turbocharger 16 affects the supercharging pressure of the intake gas. Basically, the higher the rotational speed of the compressor 17, the higher the supercharging pressure of the intake gas sucked into the combustion chamber 5. Become. The intake gas supercharging pressure affects the output torque of the internal combustion engine. Basically, the higher the intake gas supercharging pressure, the larger the output torque of the internal combustion engine. Therefore, in general, the higher the rotational speed of the compressor 17 of the exhaust turbocharger 16, the greater the output torque of the internal combustion engine.

  Therefore, in order to output the torque required for the internal combustion engine, the higher the torque required for the internal combustion engine, that is, the higher the engine load, the higher the rotation speed of the compressor 17 needs to be. For this reason, for example, when the engine load of the internal combustion engine suddenly increases because the driver of the vehicle equipped with the internal combustion engine depresses the accelerator pedal strongly, it is necessary to increase the rotational speed of the compressor 17. is there.

  However, in an ordinary exhaust turbocharger without the electric motor 66 or the intake bypass passage 68 as in the above embodiment, the pressure of exhaust gas discharged from the engine body is low when the engine speed is low and the engine load is low. The exhaust turbocharger does not rotate so much, and even if the engine load of the internal combustion engine suddenly increases, the pressure of the exhaust gas discharged from the engine body increases after the engine load increases. It takes time to do so, and it takes time to increase the rotational speed of the exhaust turbocharger. Further, in such a case, the exhaust turbocharger is increased in rotational speed from a state in which the exhaust turbocharger hardly rotates, so that the inertia of the exhaust turbocharger is also large, which increases the rotational speed of the compressor. Requires a lot of energy.

  Therefore, in reality, when the engine load suddenly increases with the engine speed being low, the engine load increases from when the engine load increases to when the compressor speed actually increases, that is, the engine load increases. There was a time lag between when the pressure increased and when the boost pressure actually increased and the required torque was actually output.

  Therefore, in the present invention, in order to eliminate such a time lag, the compressor 17 is rotated by the electric motor 66 from when the engine speed is low and the engine load is low. Specifically, the rotational speed of the electric motor 66 is feedback-controlled so that the rotational speed of the compressor 17 becomes the target minimum rotational speed. Thereby, the rotation speed of the compressor 17 is set to at least the target minimum rotation speed.

  The target minimum rotational speed is a rotational speed at which a certain amount of intake gas can be supercharged by the compressor 17 at an arbitrary engine rotational speed, and changes according to the engine rotational speed. In particular, it is set so that it increases when the engine speed increases and decreases when the engine speed decreases. For example, it is proportional to the engine speed. Further, the target minimum rotational speed is set to be higher than the rotational speed when the exhaust turbine 24 is rotated by the exhaust gas when the engine rotational speed is low and the engine load is low. The target minimum speed is obtained in advance experimentally or by calculation according to the engine speed, and is stored in the ROM 42 of the ECU 40 as a map.

  Therefore, in the present embodiment, the rotational speed of the compressor 17 of the exhaust turbocharger 16 is equal to or higher than the target minimum rotational speed corresponding to the engine rotational speed, regardless of the engine rotational speed. That is, when the rotational speed of the exhaust turbine 24 is lower than the target minimum rotational speed, the compressor 17 is rotated at the target minimum rotational speed by the electric motor 66. At this time, the rotation of the turbine wheel 62 of the exhaust turbine 24 is not transmitted to the compressor impeller 61 by the one-way clutch 64 disposed in the exhaust turbine 24. On the other hand, when the rotational speed of the exhaust turbine 24 is higher than the target minimum rotational speed, the compressor 17 is rotated by the exhaust turbine 24 at a rotational speed higher than the target minimum rotational speed. At this time, the rotation of the electric motor 66 is not transmitted to the compressor impeller 61 by the one-way clutch provided in the electric motor 66.

  Thus, in the present invention, when the engine speed is low, the flow rate of the exhaust gas is small, the exhaust turbine 24 is not driven sufficiently by the exhaust gas, and the engine load is low, the electric motor 66 The compressor 17 is driven. For this reason, even if the engine load suddenly increases, the rotational speed of the compressor 17 has already increased to the target minimum rotational speed at that time, and therefore the intake gas can be supercharged to some extent by the compressor 17. . For this reason, in the present invention, even if the engine load suddenly increases, there is no need to wait for the pressure increase of the exhaust gas discharged from the engine main body 1 due to the rotation increase of the compressor 17, and the engine load suddenly increases. The time lag from when the supercharging pressure increases until the required torque is actually output is shortened.

  In general, when the engine load suddenly increases from a low engine speed, the flow rate of the exhaust gas discharged from the engine body 1 is small and the pressure of the exhaust gas is low. Therefore, the rotational speed of the exhaust turbine 24 is unlikely to increase, and the compressor 17 cannot be rotated by the exhaust turbine 24 so that the intake gas can be sufficiently supercharged. The same can be said for the case where the rotational speed of the compressor 17 reaches the target minimum rotational speed when the engine load suddenly increases. That is, even in such a case, when the engine load suddenly increases, the exhaust gas pressure is not sufficiently high. Therefore, the rotational speed of the exhaust turbine 24 is difficult to increase, and particularly when the engine rotational speed is low. The compressor 17 cannot sufficiently supercharge intake gas only by the driving force of the exhaust turbine 24.

  In contrast, in the present invention, at least when the engine load is suddenly increased, the rotational speed of the compressor 17 when driven by the exhaust turbine 24 is higher than the rotational speed of the compressor 17 when driven by the electric motor 66. Until this occurs, the compressor 17 is driven by the electric motor 66. For this reason, the intake gas can be sufficiently supercharged by the compressor 17 even while the engine speed is low. When the engine speed increases and the flow rate of the exhaust gas increases and the pressure of the exhaust gas increases and the exhaust turbine 24 is sufficiently driven by the exhaust gas, the compressor 17 does not exhaust the electric motor 66 but the exhaust gas. It is driven by the turbine 24.

  Note that when the rotational speed of the exhaust turbine 24 is higher than the target optimum rotational speed and the compressor 17 is driven by the exhaust turbine 24, the power supply to the electric motor 66 may be stopped. In such a case, since the compressor 17 is not driven by the electric motor 66, the consumed energy can be reduced and the fuel consumption can be improved by stopping the power supply.

  By the way, when the compressor 17 is driven by the electric motor 66 as described above, supercharging is performed by the compressor 17 even when the intake gas does not need to be supercharged by the compressor 17 originally. In particular, when the engine load is low, since the required torque for the internal combustion engine is low, it is not necessary to supercharge the intake gas. Rather, the compressor 17 and the electric motor 66 are loaded by supercharging the intake gas. As a result, the fuel consumption is deteriorated.

  Therefore, in the present invention, in order to solve such a problem, when the engine load is low, the opening of the throttle valve 21 (hereinafter referred to as “throttle opening”) is reduced as shown in FIG. 69 is opened. As a result, the intake gas flows through the intake bypass passage 68 through the intake pipes 18 and 15 without passing through the compressor 17, and the intake gas is not supercharged by the compressor 17 even when the compressor 17 is rotating. That is, even when the compressor 17 is rotating, no load is applied to the compressor 17.

  As described above, when the engine load is low, the compressor 17 is driven by the electric motor 66 so that the rotation speed becomes the target minimum rotation speed, but the compressor is opened by opening the bypass valve 69. No load is applied to 17 and it can rotate freely. Therefore, in this case, the load on the electric motor 66 is also small, and the power consumption for maintaining the rotation of the compressor 17 is also small. For this reason, when the engine load is low, by opening the bypass valve 69, while maintaining the rotation of the compressor 17, the energy consumption can be kept small, and the fuel consumption can be improved.

  On the other hand, when the engine load suddenly increases, such as when the accelerator pedal 50 is greatly depressed, the throttle opening is increased and the bypass valve 69 is closed as shown in FIG. As a result, all the intake gas does not pass through the intake bypass passage 68 but flows through the intake pipes 18 and 15 via the compressor 17. For this reason, supercharging by the compressor 17 is started, and accordingly, the load on the compressor 17 increases, and thus the load on the electric motor 66 also increases. As described above, since the electric motor 66 is feedback-controlled so that the rotation speed of the compressor 17 becomes the target minimum rotation speed, the rotation of the compressor 17 is maintained only by increasing the power supplied to the electric motor 66. Therefore, when the bypass valve 69 is closed, the rotation speed of the compressor 17 does not decrease, and therefore, the supercharging of the intake gas is started by the compressor 17 immediately after the engine load becomes high.

  As described above, in the present invention, when the engine load is low, the bypass valve 68 is opened, thereby reducing the load on the electric motor 66 while maintaining the rotation of the compressor 17 and improving the fuel consumption. When the engine load becomes high, the bypass valve 68 is closed, and the compressor 17 can immediately start supercharging the intake gas.

  As described above, in the present invention, the compressor 17 is rotated by the electric motor 66 from the time when the engine load is low, and the rotation is maintained even if the engine load becomes high, but the engine load is small. In some cases, the compressor 17 is not rotated, and the compressor 17 is rotated by an electric motor after the engine load becomes high. Hereinafter, the merit of rotating the compressor 17 in the case where the compressor 17 is not rotated when the engine load is low will be described.

  When the compressor 17 is rotated by the electric motor 66 when the engine load is low and when the engine load is not rotated, the bypass valve 68 is closed when the engine load suddenly increases. The load is large. Therefore, in any case, the intake gas is supercharged by the compressor 17 by increasing the power supplied to the electric motor 66 when the engine load suddenly increases.

  However, when the compressor 17 is rotated since the engine load is low, the electric power supplied to the electric motor 66 when the load on the compressor 17 suddenly increases corresponds to an increase in the load on the compressor 17. Only the power is increased. On the other hand, if the compressor 17 is not rotated when the engine load is low, the electric power supplied to the electric motor 66 when the load on the compressor 17 suddenly increases increases the load on the compressor 17. In addition to the amount of electric power corresponding to, the amount of electric power necessary to raise the compressor 17 to the target minimum speed, for example, can be increased. For this reason, if the compressor 17 is not rotated when the engine load is low, a large amount of electric power is supplied to the electric motor 66, and an electric motor with a large output is required, which increases the manufacturing cost. Invite. Furthermore, since the rotational speed of the compressor 17 is increased after the engine load suddenly increases, the time lag from when the engine load increases to when the supercharging pressure actually increases becomes large.

  Therefore, by rotating the compressor 17 from when the engine load is low, the electric motor 66 can be reduced in output, so that the manufacturing cost can be kept low and the compressor is increased after the engine load becomes high. Since there is no need to increase the rotational speed of 17, the time lag from when the engine load increases to when the supercharging pressure actually increases can be shortened.

  FIG. 4 shows a control routine for operation control of the exhaust turbocharger of the present invention. First, at step 101, the engine speed Re is detected from the crank angle sensor 52, and the depression amount (that is, engine load) Accp of the accelerator pedal 50 is detected from the load sensor 51. Next, at step 102, the target minimum speed Rmt of the compressor 17 is calculated from the engine speed Re detected at step 101. In a control routine different from the present control routine, the electric motor 66 is feedback-controlled by PID control or the like so that the speed increase rotational speed becomes the target minimum rotational speed Rmt.

  Next, at step 103, it is determined whether or not the depression amount Accp of the accelerator pedal 50 detected at step 101 is equal to or less than a predetermined amount Accps. When it is determined that the depression amount Accp is equal to or less than the predetermined amount Accps, that is, when it is determined that the engine load is low, the routine proceeds to step 104 where the bypass valve 68 is opened. On the other hand, if it is determined in step 103 that the depression amount Accp is larger than the predetermined amount Accps, that is, if it is determined that the engine load is high, the routine proceeds to step 105 where the bypass valve 68 is closed.

  In the above embodiment, the bypass valve 58 is described as an on-off valve, but the bypass valve may be a valve whose opening degree can be changed continuously. In this case, the opening degree of the bypass valve may be adjusted according to the engine load.

  In the above embodiment, the exhaust turbocharger 16, particularly the compressor 17, is auxiliary driven by the electric motor 66. However, the auxiliary motor may not be driven by the electric motor 66, for example, by hydraulic pressure. It may be driven.

1 is an overall view of an internal combustion engine including an exhaust turbocharger according to the present invention. FIG. 3 is an enlarged view schematically showing an exhaust turbocharger, in which a bypass valve is opened and a throttle opening is small. FIG. 3 is an enlarged view schematically showing an exhaust turbocharger, showing a case where a bypass valve is closed and a throttle opening is large. 3 shows a control routine for operation control of the exhaust turbocharger of the present invention.

Explanation of symbols

16 Exhaust turbocharger 17 Compressor 24 Exhaust turbine 61 Compressor impeller 62 Turbine wheel 63 Shaft 64, 67 One-way clutch 66 Electric motor 68 Intake bypass passage 69 Bypass valve 70 Westgate valve

Claims (3)

A compressor that is provided in the intake passage of the internal combustion engine and pressurizes the intake gas;
An exhaust turbine provided in the exhaust passage of the internal combustion engine and driven to rotate by exhaust gas;
In an exhaust gas turbocharger of an internal combustion engine comprising compressor driving means for driving the compressor so that the rotational speed of the compressor becomes at least a target minimum rotational speed by a power source different from exhaust gas,
A bypass passage for bypassing the compressor; and a bypass valve for opening and closing the bypass passage. When the engine load is low, the bypass valve is opened and the compressor driving means is the compressor. An exhaust turbocharger for an internal combustion engine that drives the engine.   When the engine load becomes high, the bypass valve is closed and the compressor does not reach the target minimum rotational speed only by driving the compressor through the exhaust turbine with exhaust gas. 2. An exhaust gas turbocharger for an internal combustion engine according to claim 1, wherein said compressor driving means drives said compressor.   The one-way clutch is provided between the exhaust turbine of the exhaust turbocharger and the compressor, and the rotation of the exhaust turbine is transmitted to the compressor, but the rotation of the compressor is not transmitted to the exhaust turbine. An exhaust turbocharger for an internal combustion engine according to claim 1.

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