JP2010133303A - Internal combustion engine with supercharger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an internal combustion engine with supercharger sufficiently performing supercharging in a medium-speed area to widen an operating range of a supercharger. <P>SOLUTION: The internal combustion engine with supercharger includes: a low-pressure turbocharger and a high-pressure turbocharger disposed in series with an exhaust passage; an exhaust bypass passage 15 extended from the exhaust passage upstream of the high-pressure turbocharger, bypassing the high-pressure turbocharger, and communicating with the upstream of an inlet of a turbine of the low-pressure turbocharger; an exhaust bypass passage 17 bypassing the low-pressure turbocharger and the high-pressure turbocharger; an exhaust bypass passage 16 extended from the downstream of an outlet of a turbine of the high-pressure turbocharger, bypassing the low-pressure turbocharger, and communicating with the exhaust passage downstream of the low-pressure turbocharger; open/close valves 24-27 respectively disposed to the exhaust passage and each exhaust bypass passage; and a control device controlling opening/closing of the open/close valves. When an operation area is in a medium-speed area, the control device makes exhaust gas from the engine flow into the low-pressure turbocharger through the exhaust bypass passage 15 and controls the opening/closing of each of the open/close valves 24-27 to control supercharging pressure. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a supercharged internal combustion engine.

  Conventionally, it has low-pressure turbo and high-pressure turbo with different capacities, depending on the operating region, it uses properly the series supercharging (two-stage supercharging) and parallel supercharging, and the appropriate supercharging over the entire load range of the engine A supercharging device that can be obtained is known (see, for example, Patent Document 1).

  In this supercharging device, two-stage supercharging is performed when the operation region is a low speed region, while parallel supercharging is performed when the operation region is a high speed region. Here, the two-stage supercharging is a system in which exhaust gas discharged from the engine is circulated in series with respect to the high-pressure turbo and the low-pressure turbo. On the other hand, parallel supercharging is a system in which exhaust gas discharged from an engine is circulated in parallel to a high-pressure turbo and a low-pressure turbo.

  Patent Documents 2 and 3 also describe examples in which such a supercharging method is adopted.

JP 2005-98250 A JP-A-4-164123 JP-A-6-2553

  In the supercharging methods described in Patent Documents 1 to 3, the supercharging in the low and high speed range can be sufficiently performed, but the turbo operation range is narrow, and particularly the supercharging in the medium speed range is insufficient. There is.

  The present invention has been made to solve the above-described problems, and is a supercharger-equipped internal combustion engine that can sufficiently perform supercharging in a medium speed range and can widen the operating range of the supercharger. The purpose is to provide.

  In one aspect of the present invention, a supercharged internal combustion engine includes a low-pressure turbo and a high-pressure turbo, a first bypass passage that bypasses the high-pressure turbo from the upstream of the high-pressure turbo and communicates with the upstream of the low-pressure turbo. A second bypass passage that communicates upstream of the high-pressure turbo and downstream of the low-pressure turbo and bypasses the high-pressure turbo and the low-pressure turbo; bypasses the low-pressure turbo from the downstream of the high-pressure turbo; A third bypass passage communicating downstream; first, second, and third on-off valves that can open and close each of the first bypass passage, the second bypass passage, and the third bypass passage; Control means for controlling the opening and closing of each of the second and third on-off valves, and the control means sends exhaust gas from the internal combustion engine to the first when the operating region is a medium speed region. Causes to flow into the low-pressure turbo through bypass passage, for controlling the boost pressure by controlling the opening and closing of each of said first, second and third on-off valve.

  According to the above-described internal combustion engine with a supercharger, the control means operates only the low-pressure turbo when the operation range is the medium speed range. At that time, the control means appropriately controls the supercharging pressure by controlling the opening and closing of each of the first to third on-off valves. Thereby, the operating range of the supercharger can be extended to the medium speed range.

  In one aspect of the above-described internal combustion engine with a supercharger, the supercharging pressure is controlled by adjusting the opening of the second on-off valve when the operating region is a medium speed region. Thereby, the supercharging pressure can be adjusted to an appropriate state in the medium speed range.

  Preferred embodiments of the present invention will be described below with reference to the drawings.

[Configuration of internal combustion engine with supercharger]
FIG. 1 shows a configuration diagram of a supercharged internal combustion engine 100 according to an embodiment of the present invention. In FIG. 1, solid arrows indicate gas flow, and broken arrows indicate signal input / output.

  The supercharged internal combustion engine 100 includes an engine 1, an air cleaner 2, a low-pressure turbocharger 3, a high-pressure turbocharger 4, a catalytic converter 5, and various passages that connect these components. Each on-off valve which opens and closes various passages and a control device 6 are provided.

  The various passages include an intake passage 11, intake bypass passages 12 and 13, an exhaust passage 14, and exhaust bypass passages 15-17. Each on-off valve includes on-off valves 21 to 27. The on-off valves 21 to 23 are shut-off valves controlled to be either “open” or “closed”, for example. On the other hand, the on-off valves 24 to 27 are, for example, regulating valves whose opening / closing ratio (opening degree) is controlled to an appropriate ratio.

  The engine 1 is connected to an intake passage 11 and an exhaust passage 14, respectively, and generates power by burning a mixture of air (intake air) and fuel supplied from the intake passage 11 side. Examples of the type of the engine 1 include a gasoline engine and a diesel engine.

  The air cleaner 2 is connected to the intake passage 11 and purifies air sucked from outside.

  The low-pressure turbocharger 3 is configured as a large-capacity turbocharger having a large supercharging capability in a low and medium speed range. The low-pressure turbocharger 3 includes a compressor 3C provided on the intake side, a turbine 3T provided on the exhaust side, and a shaft 3a connecting the compressor 3C and the turbine 3T. The compressor 3 </ b> C is provided between the air cleaner 2 and the intake valve (not shown) of the engine 1 in the intake passage 11. The turbine 3T is provided between the exhaust valve (not shown) of the engine 1 and the catalytic converter 5 in the exhaust passage 14. The turbine 3T is rotated by the exhaust gas that passes through the exhaust passage 14. The rotational torque of the turbine 3T is transmitted to the compressor 3C and rotated, whereby the intake air is compressed (ie, supercharged). Hereinafter, for the sake of simplicity, “low pressure turbocharger 3” is referred to as “low pressure TC3”.

  As the low pressure TC3, for example, a well-known fixed nozzle type turbocharger can be employed. The fixed nozzle type turbocharger has a turbine wheel having a plurality of blades and a turbine housing that rotatably holds the turbine wheel. The turbine housing has an inlet through which the exhaust gas flows in and an outlet through which the exhaust gas that has flowed out is discharged, and has a scroll passage that guides the exhaust gas that flows in from the inlet of the turbine housing to the turbine wheel. The scroll flow path has a fixed nozzle with a constant opening area so that exhaust gas flowing from the inlet of the turbine housing is guided to the turbine wheel.

  The high-pressure turbocharger 4 is configured as a small-capacity turbocharger having a large supercharging capability in a medium to high speed range. The high-pressure turbocharger 4 includes a compressor 4C provided on the intake side, a turbine 4T provided on the exhaust side, and a shaft 4a connecting the compressor 4C and the turbine 4T. The compressor 4 </ b> C is provided between the compressor 3 </ b> C of the low pressure TC <b> 3 and the intake valve of the engine 1 in the intake passage 11. The turbine 4T is provided in the exhaust passage 14 between the exhaust valve of the engine 1 and the turbine 3T of the low pressure TC3. For this reason, the high pressure turbocharger 4 is connected in series to the intake passage 11 and the exhaust passage 14 with respect to the low pressure TC3. The turbine 4T is rotated by the exhaust gas passing through the exhaust passage 14, and its rotational torque is transmitted to the compressor 4C to be supercharged. In the following description, “high pressure turbocharger 4” is expressed as “high pressure TC4” for simplification.

  As the high pressure TC4, for example, a fixed nozzle type turbocharger can be adopted as in the low pressure TC3.

  The catalytic converter 5 is connected to the exhaust passage 14 and purifies air pollutants such as nitrogen oxides (NOx) contained in the exhaust gas passing through the exhaust passage 14.

  The intake passage 11 is connected to the air cleaner 2, the compressor 3C of the low pressure TC3, the compressor 4C of the high pressure TC4, and the intake valve of the engine 1, as indicated by the thick line in FIG. In the intake passage 11, an open / close valve 21 is provided between the outlet of the compressor 3 </ b> C of the low pressure TC <b> 3 and the inlet of the compressor 4 </ b> C of the high pressure TC <b> 4.

  One end of the intake bypass passage 12 is connected to the intake passage 11 between the air cleaner 2 and the inlet of the compressor 3C of the low pressure TC3, and the other end is connected between the opening / closing valve 21 and the inlet of the compressor 4C of the high pressure TC4. It is connected to the intake passage 11. An opening / closing valve 22 is provided in the intake bypass passage 12.

  One end of the intake bypass passage 13 is connected to the intake passage 11 between the outlet of the compressor 3C having the low pressure TC3 and the on-off valve 21, and the other end is connected to the outlet of the compressor 4C having the high pressure TC4 and the intake valve of the engine 1. Are connected to the intake passage 11. An opening / closing valve 23 is provided in the intake bypass passage 13.

  1, the exhaust passage 14 is connected to the exhaust valve of the engine 1, the turbine 4T of the high pressure TC4, the turbine 3T of the low pressure TC3, and the catalytic converter 5, respectively. In the exhaust passage 14, an opening / closing valve 26 is provided between the outlet of the turbine 4 T of the high pressure TC 4 and the inlet of the turbine 3 T of the low pressure TC 3.

  One end of the exhaust bypass passage 15 is connected to the exhaust passage 14 between the exhaust valve of the engine 1 and the inlet of the turbine 4T of the high pressure TC4, and the other end is connected to the opening / closing valve 26 and the inlet of the turbine 3T of the low pressure TC3. Are connected to the exhaust passage 14. The exhaust bypass passage 15 corresponds to the first bypass passage of the present invention. An open / close valve 24 is provided in the exhaust bypass passage 15. The on-off valve 24 corresponds to the first on-off valve of the present invention.

  One end of the exhaust bypass passage 16 is connected to the exhaust passage 14 between the outlet of the turbine 4T of the high pressure TC4 and the on-off valve 26, and the other end of the exhaust bypass passage 16 is connected to the outlet of the turbine 3T of the low pressure TC3 and the inlet of the catalytic converter 5. Are connected to the exhaust passage 14. The exhaust bypass passage 16 corresponds to the third bypass passage of the present invention. An open / close valve 25 is provided in the exhaust bypass passage 16. The on-off valve 25 corresponds to the third on-off valve of the present invention.

  One end of the exhaust bypass passage 17 is connected to the exhaust bypass passage 16 upstream of the on-off valve 24, and the other end is connected to the exhaust bypass passage 16 downstream of the on-off valve 25. The exhaust bypass passage 17 corresponds to the second bypass passage of the present invention. An open / close valve 27 is provided in the exhaust bypass passage 17. The on-off valve 27 corresponds to the second on-off valve of the present invention.

  The control device 6 functions as the control means of the present invention and includes an arithmetic device, a storage device, and an input / output device (not shown). The control device 6 executes control for the supercharged internal combustion engine 100 based on outputs and the like supplied from various sensors (not shown). The various sensors include a supercharging pressure sensor that detects the supercharging pressure, an accelerator opening sensor that detects the opening of the accelerator pedal, and an engine speed sensor that detects the engine speed Ne. For example, the control device 6 outputs on / off signals s1 to s7 to the on / off valves 21 to 27 on the basis of the supercharging pressure, the accelerator opening degree, the engine speed Ne, and the like obtained from each of these sensors. Controls opening and closing of 21-27.

(Control of on / off valve for each supercharging mode)
Next, control of the on / off valve for each supercharging mode according to the present embodiment will be described.

  In the supercharger-equipped internal combustion engine 100, three supercharging modes are provided, and the three supercharging modes are switched according to the operation region through the opening / closing control of the on-off valves 21 to 27 by the control device 6. Here, the three supercharging modes indicate a two-stage supercharging mode, a single-stage supercharging mode, and a parallel supercharging mode, which will be described later.

  FIG. 2 shows a chart summarizing the open / close states of the open / close valves 21 to 27 corresponding to these three supercharging modes. In this chart, “◯” indicates that the on-off valve is in the “open” state. “Δ” indicates that the on-off valve is in the “closed to intermediate opening” state. Here, the intermediate opening refers to a state in which the opening / closing valve is opened by half with respect to the fully opening state of the opening / closing valve. “X” indicates that the on-off valve is in the “closed” state.

  Hereinafter, the operation state by three supercharging modes is demonstrated.

  First, the two-stage supercharging mode will be described with reference to FIG. 2 and FIG. FIG. 3A shows an operation state in the two-stage supercharging mode.

  In the “two-stage supercharging mode”, supercharging is performed using the low pressure TC3 and the high pressure TC4. In this case, the control device 6 sets the open / close state of the on-off valves 21 to 27 to the state shown in FIG. 2 and FIG. Thereby, only the intake passage 11 is used on the intake side. Therefore, the air introduced from the outside passes through the intake passage 11, the air cleaner 2, the intake passage 11, the compressor 3C of the low pressure TC3, the intake passage 11, the on-off valve 21, the intake passage 11, the compressor 4C of the high pressure TC4, and the intake passage 11. It flows in order and is introduced into the engine 1.

  On the other hand, on the exhaust side, basically two exhaust paths are used. The exhaust path of the first system is configured only by the exhaust passage 14. In this case, exhaust gas discharged from the engine 1 is exhaust gas passage 14, high pressure TC4 turbine 4T, exhaust gas passage 14, on-off valve 26, exhaust gas passage 14, low pressure TC3 turbine 3T, exhaust gas passage 14, catalytic converter 5, exhaust gas. It flows through the passage 14 in this order. The exhaust passage of the second system is constituted by the exhaust passage 14 and the exhaust bypass passage 15 and is a route that bypasses the turbine 4T of the high pressure TC4. In this case, the exhaust gas discharged from the engine 1 flows through the exhaust passage 14, the exhaust bypass passage 15, the exhaust passage 14, the turbine 3T of the low pressure TC3, the exhaust passage 14, the catalytic converter 5, and the exhaust passage 14 in this order.

  In this two-stage supercharging mode, the supercharging pressure is adjusted by adjusting the opening degree of the on-off valve 24. That is, by adjusting the opening degree of the on-off valve 24, the exhaust flow rate of the exhaust bypass passage 15 that bypasses the turbine 4T of the high pressure TC4 is adjusted, and the supercharging pressure is adjusted.

  Thus, in the two-stage supercharging mode, the air supercharged in two stages of the compressor 3C of the low pressure TC3 and the compressor 4C of the high pressure TC4 is introduced into the engine 1.

  Next, the one-stage supercharging mode will be described with reference to FIGS. 2 and 3B. FIG.3 (b) shows the driving | running state by 1 step | paragraph supercharging mode.

  In the “one-stage supercharging mode”, supercharging is performed using only the low pressure TC3. In this case, the control device 6 sets the open / close states of the open / close valves 21 to 27 to the states shown in FIGS. 2 and 3 (b).

  On the intake side, the air introduced from outside includes the intake passage 11, the air cleaner 2, the intake passage 11, the compressor 3 </ b> C of the low pressure TC 3, the intake passage 11, the intake bypass passage 13, the on-off valve 23, the intake bypass passage 13, and the intake passage 11. In this order and introduced into the engine 1. In the one-stage supercharging mode, since the high pressure TC4 is not used, the on-off valve 21 may be open or closed.

  On the other hand, on the exhaust side, basically one exhaust path is used. The exhaust passage of the first system is constituted by the exhaust passage 14 and the exhaust bypass passage 15, and is a route that bypasses the turbine 4T of the high pressure TC4. In this case, exhaust gas discharged from the engine 1 is exhaust passage 14, exhaust bypass passage 15, on-off valve 24, exhaust bypass passage 15, exhaust passage 14, low pressure TC3 turbine 3T, exhaust passage 14, catalytic converter 5, exhaust gas. It flows through the passage 14 in this order. In addition, since the on-off valve 26 is closed, the high pressure TC4 does not operate.

  The supercharging pressure is adjusted by controlling the opening degree of the on-off valve 27. That is, by adjusting the opening degree of the on-off valve 27, the exhaust gas flow rates in the exhaust bypass passages 16 and 17 that bypass the turbine 3T of the low pressure TC3 are adjusted, and the supercharging pressure is adjusted.

  Next, the parallel supercharging mode will be described with reference to FIGS. FIG. 4 shows an operation state in the parallel supercharging mode.

  In this “parallel supercharging mode”, the supercharging is performed using the low pressure TC3 and the high pressure TC4 in common with the two-stage supercharging mode, but the following points are mainly different.

  That is, paying attention to the intake side, in the two-stage supercharging mode, the air flowing out from the air cleaner 2 side is supercharged by the low pressure TC3 compressor 3C, and the supercharged air flows into the high pressure TC4 compressor 4C. On the other hand, in the parallel supercharging mode, the air flowing out from the air cleaner 2 side directly flows into the low pressure TC3 compressor 3C and the high pressure TC4 compressor 4C. Focusing on the exhaust side, in the two-stage supercharging mode, the exhaust gas after turning the turbine 4T of the high pressure TC4 flows into the turbine 3T of the low pressure TC3 through the exhaust passage 14 and the on-off valve 26. In contrast, in the parallel supercharging mode, exhaust gas directly flows from the engine 1 side through the exhaust bypass passage 15 and the on-off valve 24 to the turbine 3T of the low pressure TC3.

  Specifically, in the case of this parallel supercharging mode, the control device 6 sets the open / close state of the open / close valves 21 to 27 to the states shown in FIGS. As a result, two intake paths are used on the intake side. The intake path of the first system is constituted by the intake passage 11 and the intake bypass passage 12, and is a route that bypasses the compressor 3C of the low pressure TC3. In this case, the air introduced from the outside flows in this order through the intake passage 11, the air cleaner 2, the intake passage 11, the intake bypass passage 12, the on-off valve 22, the intake bypass passage 12, the compressor 4 </ b> C of the high pressure TC 4, and the intake passage 11. It is introduced into the engine 1. That is, the air supercharged by the compressor 4C of the high pressure TC4 is introduced into the engine 1.

  The intake path of the second system is constituted by the intake passage 11 and the intake bypass passage 13, and is a route that bypasses the compressor 4C of the high pressure TC4. In this case, the air introduced from outside passes through the intake passage 11, the air cleaner 2, the intake passage 11, the compressor 3 </ b> C of the low pressure TC 3, the intake passage 11, the intake bypass passage 13, the on-off valve 23, the intake bypass passage 13, and the intake passage 11. It flows in this order and is introduced into the engine 1. That is, the air supercharged by the compressor 3C of the low pressure TC3 is introduced into the engine 1.

  On the other hand, on the exhaust side, basically two exhaust paths are used. The exhaust passage of the first system is the same as the exhaust passage of the first system in the above-described one-stage supercharging mode, and is a path that bypasses the turbine 4T of the high pressure TC4. The exhaust path of the second system is constituted by the exhaust passage 14 and the exhaust bypass passage 16, and is a path that bypasses the turbine 3T of the low pressure TC3. In this case, the exhaust gas discharged from the engine 1 is the exhaust passage 14, the turbine 4T of the high pressure TC4, the exhaust passage 14, the exhaust bypass passage 16, the on-off valve 25, the exhaust bypass passage 16, the exhaust passage 14, the catalytic converter 5, the exhaust gas. It flows through the passage 14 in this order.

  In the parallel supercharging mode, the supercharging pressure is adjusted by adjusting the opening degree of the on-off valve 27. That is, by adjusting the opening degree of the on-off valve 27, the exhaust gas flow rate on the exhaust bypass passage 17 that bypasses the high-pressure TC4 turbine 4T and the low-pressure TC3 turbine T3 is adjusted, and the supercharging pressure is adjusted.

  Next, an example of switching control of the three supercharging modes by the control device 6 will be described with reference to FIG. 2 and FIG.

  FIG. 5A schematically shows an operation region map relating to three supercharging modes defined based on the engine speed Ne and the accelerator opening. In FIG. 5A, the horizontal axis represents the engine speed Ne, and the vertical axis represents the accelerator opening. “Graph g1” indicates a switching line between the two-stage supercharging mode and the first-stage supercharging mode. “Graph g2” indicates a switching line between the one-stage supercharging mode and the parallel supercharging mode. “Graph g3” indicates the fully open state of the accelerator opening.

  First, the control device 6 acquires the accelerator opening through the accelerator opening sensor, and acquires the engine speed Ne through the engine speed sensor. Next, the control device 6 performs the opening / closing control of the on-off valves 21 to 27 based on the operation area map of FIG. 5A and the acquired accelerator opening degree and engine speed Ne, and among the three supercharging modes. Switch to one of the supercharging modes. In this case, the control device 6 switches to the two-stage supercharging mode when the operation region is “low speed region”, switches to the single-stage supercharging mode when the operation region is “medium speed region”, and the operation region is “high speed”. In the case of "range", switch to the parallel supercharging mode.

  Here, the “low speed region” refers to a region A1 in which the engine speed Ne is smaller than the graph g1 in the operation region map of FIG. The “medium speed range” refers to a region A2 where the engine speed Ne is between the graphs g1 and g2. The “high speed region” refers to a region A3 where the engine speed Ne is larger than the graph g3.

  Next, with reference to FIG.5 (b), an example of the effect of the internal combustion engine 100 with a supercharger which concerns on this embodiment compared with the various comparative examples is demonstrated.

  FIG. 5B is a graph showing the relationship between the supercharging mode and the engine torque in the supercharged internal combustion engine according to this embodiment and Comparative Examples 1 and 2. In FIG.5 (b), a vertical axis | shaft shows an engine torque and a horizontal axis shows the engine speed Ne. Further, the “solid line graph g11” indicates the relationship between the three supercharging modes and the engine torque in the supercharged internal combustion engine 100 according to the present embodiment. A “dashed line graph g12” indicates a relationship between the supercharging mode and the engine torque in the supercharger-equipped internal combustion engine according to the first comparative example. Comparative Example 1 has a one-stage supercharging mode that is a supercharging mode in a medium speed region and a parallel supercharging mode that is a supercharging mode in a high speed region, and the operation region depends on either the low speed region or the high speed region. Then, supercharging is performed by switching between these supercharging modes. The “broken line graph g13” indicates the relationship between the supercharging mode and the engine torque in the supercharged internal combustion engine according to the second comparative example. Comparative Example 2 has a two-stage supercharging mode that is a supercharging mode in a low speed region and a one-stage supercharging mode that is a supercharging mode in a medium speed region, and the operation region is in either the low speed region or the high speed region. Accordingly, supercharging is performed by switching the supercharging mode.

  From the graph of FIG. 5B, in the present embodiment, the engine torque in the low speed range is increased as compared with Comparative Example 1, and the engine torque in the high speed range is compared with Comparative Example 2. It has increased.

  In addition, as Comparative Example 3, the turbocharger has a two-stage supercharging mode that is a supercharging mode in a low speed region and a parallel supercharging mode that is a supercharging mode in a high speed region, and the operation region is in either the low speed region or the high speed region. Accordingly, assuming a configuration in which the supercharging mode is switched to perform supercharging, the present embodiment can increase the engine torque in the medium speed range as compared with Comparative Example 3.

  As described above, in the supercharged internal combustion engine 100 according to the present embodiment, between the two-stage supercharging mode that is the supercharging mode in the low speed region and the parallel supercharging mode that is the supercharging mode in the high speed region. A one-stage supercharging mode, which is a supercharging mode in the medium speed range, is added. When the operation region shifts to the medium speed region, the control device 6 switches from the two-stage supercharging mode or the parallel supercharging mode to the one-stage supercharging mode. That is, only the low pressure TC3 is operated in the medium speed range. At that time, the control device 6 appropriately controls the supercharging pressure by controlling the opening / closing of the on-off valves 24 to 27.

  Thereby, the engine torque and output in the medium speed range can be increased. As a result, compared with Comparative Examples 1 to 3, the operating range of the turbocharger can be extended to the medium speed range. Moreover, since the supercharging pressure can be adjusted to an appropriate state even in the middle speed range, the fuel consumption can be greatly improved.

  In the supercharged internal combustion engine 100, the control device 6 temporarily controls the on-off valve 25 to open (for example, an intermediate opening) when the operation region shifts from the medium speed region to the high speed region. It is preferable to do. Thereby, at the time of transition from the medium speed range to the high speed range, it is possible to smoothly switch from the one-stage supercharging mode to the parallel supercharging mode without causing a step in the engine torque.

  Further, in the supercharger-equipped internal combustion engine 100, each of the low pressure TC3 and the high pressure TC4 can be configured as a fixed nozzle type turbocharger. According to this, product cost can be reduced compared with a turbocharger of a variable nozzle (VN) system. As a result, the supercharger-equipped internal combustion engine 100 can be suitably applied to various vehicle types.

  If the product cost of the turbocharger is not a problem, each of the low pressure TC3 and the high pressure TC4 may be configured as a variable nozzle type turbocharger. In this case, it is possible to adjust the supercharging pressure to an appropriate state by adjusting the amount and speed of the exhaust gas flowing into the turbine wheel through the variable nozzle provided in the scroll flow path. Therefore, when using a variable nozzle type turbocharger, the on-off valves 24 to 27 are basically shut-off valves.

The block diagram of the internal combustion engine with a supercharger which concerns on embodiment of this invention is shown. The figure which concerns on control of the on-off valve according to supercharging mode is shown. The operation state by the two-stage supercharging mode and the first-stage supercharging mode is shown. Shows the operating state in parallel supercharging mode. The operation area | region map etc. which concern on three supercharging modes are shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine 3 Low pressure turbocharger 4 High pressure turbocharger 6 Control apparatus 11 Intake passage 12, 13 Intake bypass passage 14 Exhaust passage 15-17 Exhaust bypass passage 21-27 Open / close valve

Claims (2)

Low pressure turbo and high pressure turbo,
A first bypass passage that bypasses the high-pressure turbo from the upstream of the high-pressure turbo and communicates with the upstream of the low-pressure turbo;
A second bypass passage communicating with the upstream of the high-pressure turbo and the downstream of the low-pressure turbo to bypass the high-pressure turbo and the low-pressure turbo;
A third bypass passage that bypasses the low-pressure turbo from the downstream of the high-pressure turbo and communicates with the downstream of the low-pressure turbo;
First, second and third on-off valves capable of opening and closing each of the first bypass passage, the second bypass passage and the third bypass passage;
Control means for controlling the opening and closing of each of the first, second and third on-off valves,
The control means allows the exhaust gas from the internal combustion engine to flow into the low-pressure turbo through the first bypass passage when the operation region is a medium speed region, and the first, second, and third on-off valves. An internal combustion engine with a supercharger, wherein the supercharging pressure is controlled by controlling the opening and closing of each.   2. The supercharged internal combustion engine according to claim 1, wherein the control means controls the supercharging pressure by adjusting an opening degree of the second on-off valve when the operation region is a medium speed region.

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