JP2009191667A - Supercharging device and supercharging engine system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To expand an operation range for providing high efficiency, in a supercharging device having a low pressure stage turbocharger and a high pressure stage turbocharger. <P>SOLUTION: When an engine speed Ne and the torque Te of an internal combustion engine 10 exist in a low speed-low load area small in exhaust energy, a low pressure stage exhaust control valve 24 is controlled in an opening state, and a high pressure stage exhaust control valve 44 is controlled in a closed state. Since exhaust gas from the internal combustion engine 10 passes through a high pressure stage turbine 42 and flows by bypassing a low pressure stage turbine 22, intake air to a low pressure stage compressor 21 is introduced to a high pressure stage compressor 41 by bypassing the low pressure stage compressor 21. The intake air from a low pressure stage compressor bypass flow passage 25 is pressurized by the high pressure stage compressor 41, and is then introduced to the internal combustion engine 10. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a supercharging device that pressurizes intake air into an engine by using exhaust energy of the engine, and a supercharged engine system.

  A turbocharger (turbocharger) is used as a supercharging device that pressurizes intake air into the engine. The turbocharger generates power in the turbine using the exhaust energy of the engine, and pressurizes the intake air to the engine by driving the compressor using the power of the turbine.

  Furthermore, a series two-stage turbocharger in which a large-capacity low-pressure stage turbocharger and a small-capacity high-pressure stage turbocharger are provided in series has been proposed. In this series two-stage turbocharger, intake air pressurized in two stages by the low-pressure stage turbocharger and the high-pressure stage turbocharger is introduced into the engine. However, in this series two-stage turbocharger, if the engine is operating at high speed and high load with a lot of exhaust energy, the capacity of the high-pressure stage turbocharger will be insufficient, so the total amount of working gas will be high. Can no longer flow through the stage turbocharger. Therefore, for the high-pressure stage turbocharger, a turbine bypass path that bypasses the turbine and a compressor bypass path that bypasses the compressor are provided, and the high-pressure stage turbocharger turbine is bypassed during high-speed, high-load operation of the engine. By flowing the exhaust gas, the intake air pressurized by the low-pressure stage turbocharger and bypassing the high-pressure stage turbocharger is introduced into the engine.

JP 2007-154684 A JP 2001-329849 A JP 2005-256755 A JP 2006-57570 A Christoph et al., “BMW High Precision Fuel Injection in Conjunction With Twin -Turbo Technology: A Combination for Maximum Dynamic and High Fuel Efficiency”, SAE Paper 2007-01-1560, Society of Automotive Engineers, 2007 Robert C. et al., "Series Turbocharging for the Caterpillar (R) Heavy-Duty, On-Highway Truck Engines with ACERT (R) Technology", SAE Paper 2007-01-1561, Society of Automotive Engineers, 2007

  In the above-described series two-stage turbocharger, since the intake air to the engine is pressurized in two stages by the low-pressure stage turbocharger and the high-pressure stage turbocharger, the overall efficiency of the series two-stage turbocharger is as follows. Is the product of the efficiency of the high-pressure turbocharger. Particularly in the small flow rate region, the efficiency of the low-pressure stage turbocharger and the efficiency of the high-pressure stage turbocharger are lowered, and the overall efficiency is lowered. In order to efficiently pressurize the intake air into the engine with the low-pressure stage turbocharger and the high-pressure stage turbocharger, it is desirable to operate the low-pressure stage turbocharger and the high-pressure stage turbocharger in a highly efficient operating region. It is basically difficult to operate both the high-pressure turbocharger and the high-pressure stage turbocharger efficiently over a wide operating range. In particular, when the engine is operating at low speed and low load with low exhaust energy, the low pressure turbocharger is used even though there is not enough exhaust energy to drive a large capacity low pressure turbocharger. Since both the high-pressure stage turbocharger and the high-pressure stage turbocharger are driven, it is difficult to efficiently pressurize the intake air into the engine due to loss of driving of the low-pressure stage turbocharger.

  An object of the present invention is to widen an operating range in which high efficiency can be obtained in a supercharging device including a low-pressure stage turbocharger and a high-pressure stage turbocharger.

  The supercharging device and the supercharging engine system according to the present invention employ the following means in order to achieve the above-described object.

  A supercharging device according to the present invention is a supercharging device that pressurizes intake air to the engine by using exhaust energy of the engine, and includes a low-pressure compressor that pressurizes intake air to the engine, and intake air from the low-pressure compressor. A high-pressure compressor that pressurizes and supplies the engine, a low-pressure turbine that drives the low-pressure compressor using the exhaust energy of the engine, a high-pressure turbine that drives the high-pressure compressor using the exhaust energy of the engine, Low-pressure stage turbine bypass means that can flow exhaust gas from the engine by bypassing the low-pressure stage turbine, and when the low-pressure stage turbine bypass means bypasses the low-pressure stage turbine and flows exhaust gas, Low pressure compressor that bypasses the low pressure compressor and introduces it to the high pressure compressor And when the exhaust flows through the low-pressure turbine, the intake air pressurized by the low-pressure compressor and the high-pressure compressor is introduced into the engine, and the exhaust flows by bypassing the low-pressure turbine. The gist is that the intake air that bypasses the low-pressure compressor and is pressurized by the high-pressure compressor is introduced into the engine.

  In one aspect of the present invention, the low-pressure compressor bypass means bypasses the low-pressure compressor and connects the inlet and the outlet of the low-pressure compressor, and the intake bypass flow in the low-pressure compressor bypass A low-pressure stage intake regulating valve that, when bypassing the low-pressure stage turbine and the exhaust gas flows, allows the bypass flow of the intake air from the inlet to the outlet of the low-pressure stage compressor, When the exhaust flows through the low-pressure turbine, it is preferable to block the intake bypass flow from the outlet to the inlet of the low-pressure compressor. In this aspect, it is preferable that the low-pressure stage intake adjustment valve is a one-way valve.

  In one aspect of the present invention, the low-pressure turbine bypass means is configured such that at least one of the engine speed and torque when the exhaust flows through the low-pressure turbine is lower than when the exhaust flows through the low-pressure turbine. Thus, it is preferable to flow the exhaust gas by bypassing the low-pressure stage turbine.

  In one aspect of the present invention, when the exhaust from the engine can flow by bypassing the high-pressure turbine, and when the high-pressure turbine bypass means bypasses the high-pressure turbine and flows the exhaust, A high-pressure compressor bypass means for introducing the intake air from the low-pressure compressor into the engine by bypassing the high-pressure compressor, and when the exhaust gas flows through the high-pressure turbine, the intake air is pressurized by the low-pressure compressor and It is preferred that the intake air bypassing the high pressure compressor is introduced into the engine.

  In one aspect of the present invention, the high-pressure compressor bypass means bypasses the high-pressure compressor and connects the inlet and outlet of the high-pressure compressor, and the intake bypass flow in the high-pressure compressor bypass A high-pressure stage intake regulating valve that, when bypassing the high-pressure stage turbine and exhaust flows, allows the bypass flow of the intake air from the inlet to the outlet of the high-pressure stage compressor, When exhaust flows through the high-pressure turbine, it is preferable to block the intake bypass flow from the outlet to the inlet of the high-pressure compressor. In this aspect, it is preferable that the high-pressure stage intake adjustment valve is a one-way valve.

  In one aspect of the present invention, the high-pressure turbine bypass means is configured such that at least one of the engine speed and torque when the exhaust flows by bypassing the high-pressure turbine is higher than when the exhaust flows through the high-pressure turbine. Thus, it is preferable to flow exhaust gas by bypassing the high-pressure turbine.

  In one aspect of the present invention, it is preferable that the engine is a cylinder injection internal combustion engine that injects fuel into the cylinder.

  The supercharged engine system according to the present invention is a supercharged engine system comprising an engine and a supercharging device that pressurizes intake air into the engine by using exhaust energy of the engine, wherein the supercharging device The gist of the present invention is the supercharging device according to the present invention.

  According to the present invention, when exhaust flows by bypassing the low-pressure stage turbine, the intake air pressurized by the high-pressure stage compressor is introduced into the engine, bypassing the low-pressure stage compressor, so that the exhaust energy of the engine is small. Sometimes, it is possible to suppress the loss caused by driving the low-pressure stage turbine and use all of the exhaust energy for driving the high-pressure stage turbine. Therefore, even with a small amount of exhaust energy, the operating state of the high-pressure compressor can be quickly transferred to the operating region where the efficiency is high. As a result, the operating range of the supercharging device with high efficiency can be expanded.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention (hereinafter referred to as embodiments) will be described with reference to the drawings.

  FIG. 1 is a diagram showing a schematic configuration of a supercharged engine system including a supercharging device 12 according to an embodiment of the present invention. The supercharging device 12 according to the present embodiment pressurizes intake air to the internal combustion engine 10 using exhaust energy of the internal combustion engine 10, and has a large capacity low pressure stage turbocharger 20 and a small capacity high pressure stage turbocharger. 40.

  The internal combustion engine 10 can be configured by a direct injection internal combustion engine that directly injects fuel into a cylinder, such as a diesel engine or a direct injection gasoline engine. When the internal combustion engine 10 is a direct injection internal combustion engine, the intake air (new air) pressurized by the supercharging device 12 according to the present embodiment is air. In the internal combustion engine 10, exhaust gas recirculation (EGR) is performed in which part of the exhaust gas after combustion is supplied to the intake side as EGR gas. By performing EGR, nitrogen oxides (NOx) generated during combustion can be suppressed. However, if the amount of air in the intake air to the internal combustion engine 10 decreases, soot is likely to be generated during combustion. In the present embodiment, the amount of air supplied to the internal combustion engine 10 can be increased by pressurizing the intake air (air) to the internal combustion engine 10 with the supercharging device 12, and the soot generated during combustion can be suppressed. Can be achieved.

  The low-pressure stage turbocharger 20 includes a large-capacity low-pressure stage compressor 21 that pressurizes intake air to the internal combustion engine 10 and a large-capacity low-pressure stage turbine 22 that rotationally drives the low-pressure stage compressor 21 using the exhaust energy of the internal combustion engine 10. And comprising. The low-pressure stage turbocharger 20 has a characteristic of high efficiency at a large flow rate. The high-pressure turbocharger 40 includes a small-capacity high-pressure compressor 41 that pressurizes intake air from the outlet 21 b of the low-pressure compressor 21 and supplies the pressurized air to the internal combustion engine 10, and a high-pressure compressor 41 that uses the exhaust energy of the internal combustion engine 10. And a high-capacity high-pressure turbine 42 having a small capacity for rotationally driving the engine. The high-pressure stage turbocharger 40 has a characteristic of high efficiency at a small flow rate. The low pressure compressor 21 and the high pressure compressor 41 are provided in series in the intake passage of the internal combustion engine 10. FIG. 1 shows an example in which a high-pressure turbine 42 and a low-pressure turbine 22 are provided in series in the exhaust passage of the internal combustion engine 10, and the low-pressure turbine 22 uses exhaust energy from the outlet 42 b of the high-pressure turbine 42. The low-pressure stage compressor 21 is rotationally driven by using it.

  In order to flow exhaust from the internal combustion engine 10 (exhaust to the inlet 42a of the high-pressure turbine 42) bypassing the high-pressure turbine 42, the inlet 42a and outlet 42b of the high-pressure turbine 42 (inlet 22a of the low-pressure turbine 22) Are connected to each other by bypassing the high-pressure turbine 42. The high-pressure turbine bypass passage 43 is provided with a high-pressure exhaust control valve 44 that controls the exhaust bypass flow in the high-pressure turbine bypass passage 43. The high-pressure stage exhaust control valve 44 is selectively used in an open state that allows the exhaust bypass flow in the high-pressure stage turbine bypass passage 43 and a closed state that blocks the exhaust bypass flow in the high-pressure turbine bypass passage 43. It is possible to switch. Here, the capacity of the high-pressure stage exhaust control valve 44 is set so that the entire flow rate of the exhaust gas from the internal combustion engine 10 can flow through the high-pressure stage exhaust control valve 44.

  In order to flow the intake air from the outlet 21b of the low-pressure stage compressor 21 (intake to the inlet 41a of the high-pressure stage compressor 41) bypassing the high-pressure stage compressor 41, the inlet 41a (the low-pressure stage compressor 21 of the low-pressure stage compressor 21). A high-pressure stage compressor bypass passage 45 is provided that connects the outlet 21b) and the outlet 41b by bypassing the high-pressure compressor 41. The high-pressure stage compressor bypass passage 45 is provided with a one-way valve (check valve) 46 as a high-pressure stage intake adjustment valve that adjusts the bypass flow of the intake air in the high-pressure stage compressor bypass passage 45. Here, the one-way valve 46 allows the intake air bypass flow from the inlet 41a to the outlet 41b of the high-pressure compressor 41 (the flow of the high-pressure compressor bypass passage 45) and the inlet from the outlet 41b of the high-pressure compressor 41 to the inlet. It is provided to block the intake bypass flow (flow in the high-pressure compressor bypass passage 45) to 41a. When the exhaust flows by bypassing the high-pressure turbine 42 and the high-pressure compressor 41 is not pressurizing the intake air, the one-way valve 46 is opened and the bypass flow of the intake air from the inlet 41a to the outlet 41b of the high-pressure compressor 41 Is acceptable. On the other hand, when the exhaust gas flows through the high-pressure turbine 42 and the high-pressure compressor 41 pressurizes the intake air so that the pressure at the outlet 41b becomes higher than the pressure at the inlet 41a, the one-way valve 46 is closed and the high-pressure compressor 41 The intake bypass flow from the outlet 41b to the inlet 41a is blocked.

  When the high-pressure stage exhaust control valve 44 is in the closed state, the exhaust from the internal combustion engine 10 flows through the high-pressure stage turbine 42 without bypassing the high-pressure stage turbine 42 and then introduced into the inlet 22 a of the low-pressure stage turbine 22. Is done. In that case, the intake air from the outlet 21 b of the low-pressure compressor 21 is pressurized by the high-pressure compressor 41 without bypassing the high-pressure compressor 41 and then introduced into the internal combustion engine 10. At that time, the one-way valve 46 blocks the intake air flow from the outlet 41 b of the high-pressure compressor 41 to the inlet 41 a in the high-pressure compressor bypass passage 45. On the other hand, when the high-pressure stage exhaust control valve 44 is in the open state, the exhaust from the internal combustion engine 10 flows through the high-pressure stage turbine bypass passage 43 and bypasses the high-pressure stage turbine 42, and then the low-pressure stage turbine 22. To the inlet 22a. In that case, the one-way valve 46 allows the intake air flow from the inlet 41a to the outlet 41b of the high-pressure compressor 41 in the high-pressure compressor bypass passage 45, and the intake air from the outlet 21b of the low-pressure compressor 21 is The high pressure compressor 41 is bypassed through the high pressure compressor bypass passage 45 without being pressurized by the compressor 41, and then introduced into the internal combustion engine 10.

  Furthermore, in order to flow exhaust gas from the internal combustion engine 10 (exhaust gas to the inlet 22a of the low pressure turbine 22) bypassing the low pressure turbine 22, the inlet 22a of the low pressure turbine 22 (exit 42b of the high pressure turbine 42) and A low-pressure turbine bypass passage 23 is provided to connect the outlet 22b with the low-pressure turbine 22 by bypass. The low-pressure stage turbine bypass passage 23 is provided with a low-pressure stage exhaust control valve 24 that controls the bypass flow of exhaust gas in the low-pressure stage turbine bypass passage 23. The low-pressure stage exhaust control valve 24 is selectively used in an open state that allows an exhaust bypass flow in the low-pressure stage turbine bypass passage 23 and a closed state that blocks an exhaust bypass flow in the low-pressure turbine bypass passage 23. It is possible to switch. Here, the capacity of the low-pressure stage exhaust control valve 24 is set so that the entire flow rate of the exhaust gas from the internal combustion engine 10 can flow through the low-pressure stage exhaust control valve 24.

  Then, in order to flow the intake air to the inlet 21a of the low-pressure stage compressor 21 bypassing the low-pressure stage compressor 21, the inlet 21a and the outlet 21b (the inlet 41a of the high-pressure stage compressor 41) of the low-pressure stage compressor 21 are connected to the low-pressure stage compressor 21. Is provided with a low-pressure compressor bypass passage 25 for bypassing and connecting the two. The low-pressure stage compressor bypass passage 25 is provided with a one-way valve (check valve) 26 as a low-pressure stage intake adjustment valve that adjusts the bypass flow of intake air in the low-pressure stage compressor bypass passage 25. Here, the one-way valve 26 allows the intake air bypass flow from the inlet 21a to the outlet 21b of the low-pressure compressor 21 (the flow of the low-pressure compressor bypass passage 25) and the inlet of the low-pressure compressor 21 from the outlet 21b. It is provided to block the intake bypass flow (flow in the low-pressure compressor bypass flow path 25) to 21a. When the low-pressure stage turbine 22 bypasses the exhaust gas and the low-pressure stage compressor 21 does not pressurize the intake air, the one-way valve 26 is opened, and the intake air bypass flow from the inlet 21a to the outlet 21b of the low-pressure stage compressor 21 is opened. Is acceptable. On the other hand, when the exhaust gas flows through the low-pressure turbine 22 and the low-pressure compressor 21 pressurizes the intake air so that the pressure at the outlet 21b becomes higher than the pressure at the inlet 21a, the one-way valve 26 is closed and the low-pressure compressor 21 The intake bypass flow from the outlet 21b to the inlet 21a is blocked.

  When the low-pressure stage exhaust control valve 24 is in the closed state, the exhaust gas from the internal combustion engine 10 (the outlet 42b of the high-pressure stage turbine 42) flows through the low-pressure stage turbine 22 without bypassing the low-pressure stage turbine 22, It is introduced into the outlet 22 b of the low pressure turbine 22. In that case, the intake air to the inlet 21 a of the low-pressure compressor 21 is pressurized by the low-pressure compressor 21 without bypassing the low-pressure compressor 21 and then introduced into the inlet 41 a of the high-pressure compressor 41. At that time, the one-way valve 26 blocks the intake air flow from the outlet 21 b to the inlet 21 a of the low-pressure compressor 21 in the low-pressure compressor bypass passage 25. On the other hand, when the low-pressure stage exhaust control valve 24 is in the open state, the exhaust from the internal combustion engine 10 (the outlet 42b of the high-pressure stage turbine 42) bypasses the low-pressure stage turbine 22 through the low-pressure stage turbine bypass passage 23. And then introduced into the outlet 22 b of the low-pressure turbine 22. In that case, the flow of intake air from the inlet 21a to the outlet 21b of the low-pressure compressor 21 in the low-pressure compressor bypass passage 25 is allowed by the one-way valve 26, and the intake air to the inlet 21a of the low-pressure compressor 21 is The low pressure compressor 21 bypasses the low pressure compressor 21 through the low pressure compressor bypass passage 25 without being pressurized by the compressor 21, and is then introduced into the inlet 41 a of the high pressure compressor 41.

  The electronic control unit 50 controls the operating state of the supercharger 12 by controlling the open / close state of the low-pressure stage exhaust control valve 24 and the open / close state of the high-pressure stage exhaust control valve 44 based on the operating state of the internal combustion engine 10. Control. Hereinafter, operation | movement of the supercharging apparatus 12 which concerns on this embodiment is demonstrated using FIGS.

  When the electronic control unit 50 is in the low speed / low load region where the rotational speed Ne and torque Te of the internal combustion engine 10 do not exceed the characteristic line A shown in FIG. 2, as shown in FIGS. The low-pressure stage exhaust control valve 24 is opened and the high-pressure stage exhaust control valve 44 is closed. The characteristic line A here is a characteristic line in which the torque Te decreases as the rotational speed Ne of the internal combustion engine 10 increases, as shown in FIG. Here, the characteristic line A can also be set so that the output of the internal combustion engine 10 on the characteristic line A becomes a predetermined constant value WA. By controlling the low-pressure stage exhaust control valve 24 to the open state, as shown in FIG. 3, the exhaust gas flows through the low-pressure stage turbine bypass flow path 23 (bypassing the low-pressure stage turbine 22). 21 is introduced into the inlet 41a of the high pressure compressor 41 through the low pressure compressor bypass passage 25 (bypassing the low pressure compressor 21). Then, by controlling the high-pressure stage exhaust control valve 44 to the closed state, as shown in FIG. 3, the exhaust gas flows through the high-pressure stage turbine 42, so that the intake air from the low-pressure stage compressor bypass passage 25 is taken in by the high-pressure stage compressor. After being pressurized at 41, it is introduced into the internal combustion engine 10. Therefore, in this case, the low-pressure stage turbocharger 20 does not operate and only the high-pressure stage turbocharger 40 operates, and the intake air that bypasses the low-pressure stage compressor 21 and is pressurized by the high-pressure stage compressor 41 is introduced into the internal combustion engine 10. The Hereinafter, the operation mode of the supercharging device 12 is referred to as a high-pressure stage single operation mode. The rotational speed Ne of the internal combustion engine 10 can be detected by, for example, a sensor (not shown), and the torque Te (load) of the internal combustion engine 10 can be calculated from, for example, the fuel injection amount.

  Further, when the electronic control unit 50 is in a medium speed / medium load region in which the rotational speed Ne and the torque Te of the internal combustion engine 10 exceed the characteristic line A shown in FIG. As shown in FIGS. 4 and 6, the low-pressure stage exhaust control valve 24 is closed and the high-pressure stage exhaust control valve 44 is closed. As shown in FIG. 2, the characteristic line B here is set at a higher speed / higher torque side than the characteristic line A, and the characteristic line B decreases as the rotational speed Ne of the internal combustion engine 10 increases. is there. Here, the characteristic line B can also be set so that the output of the internal combustion engine 10 on the characteristic line B becomes a predetermined constant value WB (WB> WA). By controlling the low-pressure stage exhaust control valve 24 to the closed state, as shown in FIG. 4, the exhaust gas flows through the low-pressure stage turbine 22, so that the intake air to the inlet 21 a of the low-pressure stage compressor 21 is received by the low-pressure stage compressor 21. After being pressurized, it is introduced into the inlet 41 a of the high-pressure compressor 41. Then, by controlling the high-pressure stage exhaust control valve 44 to the closed state, as shown in FIG. 4, the exhaust gas flows through the high-pressure stage turbine 42, so that the intake air pressurized by the low-pressure stage compressor 21 is supplied to the high-pressure stage compressor. After being further pressurized at 41, it is introduced into the internal combustion engine 10. Accordingly, in this case, both the low-pressure stage turbocharger 20 and the high-pressure stage turbocharger 40 operate, and the intake air pressurized in two stages by the low-pressure stage compressor 21 and the high-pressure stage compressor 41 is introduced into the internal combustion engine 10. Hereinafter, the operation mode of the supercharging device 12 is referred to as a series operation mode. As shown in FIG. 2, in the low speed / low load region, at least one of the rotational speed Ne and the torque Te of the internal combustion engine 10 is lower than that in the medium speed / medium load region. Therefore, the low-pressure stage exhaust control valve 24 is configured so that at least one of the rotational speed Ne and the torque Te of the internal combustion engine 10 is in the series operation mode (low-pressure stage) in the high-pressure stage single operation mode (the state where the exhaust flows by bypassing the low-pressure stage turbine 22) The low-pressure stage turbine 22 is bypassed so that the exhaust gas flows to a lower level than the state where the exhaust gas flows through the turbine 22.

  Further, when the electronic control unit 50 is in the high speed / high load region where the rotational speed Ne and the torque Te of the internal combustion engine 10 exceed the characteristic line B shown in FIG. 2, as shown in FIGS. The low-pressure stage exhaust control valve 24 is closed and the high-pressure stage exhaust control valve 44 is controlled to be open. By controlling the low-pressure stage exhaust control valve 24 to the closed state, as shown in FIG. 5, exhaust gas flows through the low-pressure stage turbine 22, so that the intake air to the inlet 21 a of the low-pressure stage compressor 21 is received by the low-pressure stage compressor 21. After being pressurized, it is introduced into the inlet 41 a of the high-pressure compressor 41. Since the exhaust flows through the high-pressure turbine bypass passage 43 (bypassing the high-pressure turbine 42) by controlling the high-pressure exhaust control valve 44 to the open state, as shown in FIG. The intake air pressurized by the stage compressor 21 is introduced into the internal combustion engine 10 through the high-pressure stage compressor bypass passage 45 (bypassing the high-pressure stage compressor 41). Therefore, in this case, the high-pressure stage turbocharger 40 is not operated, and only the low-pressure stage turbocharger 20 is operated, and the intake air pressurized by the low-pressure stage compressor 21 and bypassing the high-pressure stage compressor 41 is introduced into the internal combustion engine 10. . Hereinafter, the operation mode of the supercharging device 12 is referred to as a low-pressure stage single operation mode. As shown in FIG. 2, in the high speed / high load region, at least one of the rotational speed Ne and the torque Te of the internal combustion engine 10 is higher than that in the medium speed / medium load region. Therefore, the high-pressure stage exhaust control valve 44 is configured so that at least one of the rotational speed Ne and the torque Te of the internal combustion engine 10 in the low-pressure stage single operation mode (a state in which exhaust flows by bypassing the high-pressure stage turbine 42) The high-pressure turbine 42 is bypassed so that the exhaust gas flows higher than the exhaust gas flowing through the turbine 42.

  The switching from the high-pressure stage single operation mode to the series operation mode can be performed by switching the low-pressure stage exhaust control valve 24 from the open state to the closed state. The low-pressure stage exhaust control valve 24 can be switched from the closed state to the open state. During the switching operation of the low-pressure stage exhaust control valve 24, the opening degree of the low-pressure stage exhaust control valve 24 can be gradually changed. In addition, a hysteresis may be provided between the characteristic line A used for switching determination from the high pressure stage single operation mode to the series operation mode and the characteristic line A used for switching determination from the series operation mode to the high pressure stage single operation mode. it can. For example, as shown in FIG. 7, the characteristic line A2 used for determination of switching from the series operation mode to the high-pressure stage single operation mode is slower than the characteristic line A1 used for determination of switching from the high-pressure stage single operation mode to the series operation mode.・ It can be set to the low torque side. This prevents the switching between the high-pressure stage single operation mode and the series operation mode from being repeated in a short time.

  Further, switching from the series operation mode to the low pressure stage single operation mode can be performed by switching the high pressure stage exhaust control valve 44 from the closed state to the open state, and switching from the low pressure stage single operation mode to the series operation mode. This can be performed by switching the high-pressure stage exhaust control valve 44 from the open state to the closed state. During the switching operation of the high pressure exhaust control valve 44, the opening degree of the high pressure exhaust control valve 44 can be gradually changed. In addition, a hysteresis may be provided between the characteristic line B used for determination of switching from the series operation mode to the low pressure stage single operation mode and the characteristic line B used for determination of switching from the low pressure stage single operation mode to the series operation mode. it can. For example, as shown in FIG. 7, the characteristic line B2 used for determining switching from the low pressure stage single operation mode to the series operation mode is slower than the characteristic line B1 used for determining switching from the series operation mode to the low pressure stage single operation mode.・ It can be set to the low torque side. This prevents the switching between the series operation mode and the low pressure stage single operation mode from being repeated in a short time.

  In the series operation mode, the intake air to the internal combustion engine 10 is pressurized in two stages by the low-pressure stage compressor 21 and the high-pressure stage compressor 41. Therefore, the overall efficiency of the supercharging device 12 is equal to the efficiency of the low-pressure stage turbocharger 20 and the high-pressure stage turbo. This is multiplied by the efficiency of the charger 40. Particularly in the small flow rate region, the efficiency of the low-pressure stage turbocharger 20 and the efficiency of the high-pressure stage turbocharger 40 are reduced, and the efficiency of the entire supercharging device 12 is reduced. When the rotational speed Ne and torque Te of the internal combustion engine 10 are in the low speed / low load region where the exhaust energy is low, if the operation mode of the supercharger 12 is in the series operation mode, the large-capacity low-pressure turbocharger 20 is Even though there is not enough exhaust energy to drive, both the low-pressure stage turbocharger 20 and the high-pressure stage turbocharger 40 are driven, so that the driving of the low-pressure stage turbocharger 20 is lost. As a result, it becomes difficult to efficiently pressurize the intake air to the internal combustion engine 10, and it becomes difficult to obtain a sufficient boost pressure.

  On the other hand, in the present embodiment, when the rotational speed Ne and torque Te of the internal combustion engine 10 are in the low speed / low load region where the exhaust energy is low, the operation mode of the supercharger 12 is controlled to the high pressure stage single operation mode. Thus, loss due to driving of the large-capacity low-pressure stage turbocharger 20 (low-pressure stage turbine 22) is suppressed, and all of the exhaust energy from the internal combustion engine 10 is reduced to the small-capacity high-pressure stage turbocharger 40 (high pressure). It can be used to drive a stage turbine 42). Therefore, even with a small amount of exhaust energy, the operating state of the high-pressure stage turbocharger 40 can be quickly transferred to an operating region where the efficiency of the high-pressure stage compressor 41 is increased. Accordingly, the efficiency of the entire supercharging device 12 can be quickly increased to efficiently pressurize the intake air to the internal combustion engine 10, and a sufficient supercharging pressure can be quickly obtained. As a result, even in the low speed / low load region, the charging efficiency of the internal combustion engine 10 can be increased without causing a reduction in fuel consumption, and so the emission can be reduced such as suppression of soot.

  When the rotational speed Ne and the torque Te of the internal combustion engine 10 are in the medium speed / medium load region, the operation mode of the supercharger 12 is controlled to the series operation mode, so that the low-pressure stage turbo can be generated with sufficient exhaust energy. The charger 20 and the high-pressure stage turbocharger 40 can be driven, and the operating state of the low-pressure stage turbocharger 20 and the high-pressure stage turbocharger 40 is changed to an operating region where the efficiency of the low-pressure stage compressor 21 and the efficiency of the high-pressure stage compressor 41 are increased. It can be transferred quickly. As a result, the overall efficiency of the supercharging device 12 can be increased to efficiently pressurize the intake air to the internal combustion engine 10, and the intake air can be pressurized in two stages to increase the supercharging pressure.

  Further, when the rotational speed Ne and the torque Te of the internal combustion engine 10 are in the high speed / high load region where the exhaust energy is high, the capacity of the high pressure stage turbocharger 40 is insufficient. Can no longer flow. In that case, by controlling the operation mode of the supercharging device 12 to the low-pressure stage single operation mode, the large-capacity low-pressure stage turbocharger 20 can be driven with sufficient exhaust energy, and the operation of the low-pressure stage turbocharger 20 is performed. The state can be shifted to an operating region where the efficiency of the low-pressure compressor 21 is increased. As a result, the efficiency of the entire supercharging device 12 can be increased to efficiently pressurize the intake air to the internal combustion engine 10, and a sufficient supercharging pressure can be obtained.

  Therefore, according to the present embodiment, the operating range of the supercharging device 12 that can obtain high efficiency can be expanded, and a sufficient supercharging pressure can be obtained in a wide operating range. As a result, it is possible to increase the charging efficiency of the internal combustion engine 10 in a wide operating range, and to achieve low emissions such as suppression of soot.

  In the present embodiment, the electronic control unit 50 can also switch the operation mode of the supercharging device 12 based on the rotational speed Ne of the internal combustion engine 10. For example, the electronic control unit 50 controls the operation mode of the supercharging device 12 to the high-pressure stage single operation mode when the rotational speed Ne of the internal combustion engine 10 is in a low speed region lower than the set value Ne1. When the rotational speed Ne is equal to or higher than the set value Ne1 and is in a medium speed range lower than the set value Ne2 (Ne2> Ne1), the operation mode of the supercharger 12 is controlled to the series operation mode, and the rotational speed of the internal combustion engine 10 It is also possible to control the operation mode of the supercharging device 12 to the low-pressure stage single operation mode when Ne is in a high speed region equal to or greater than the set value Ne2. In this example, the low-pressure stage exhaust control valve 24 is configured so that the rotational speed Ne of the internal combustion engine 10 in the high-pressure stage single operation mode (a state in which exhaust flows through the low-pressure stage turbine 22) passes through the series operation mode (the low-pressure stage turbine 22). Therefore, the low-pressure turbine 22 is bypassed so that the exhaust gas flows. The high-pressure stage exhaust control valve 44 is configured so that the rotational speed Ne of the internal combustion engine 10 in the low-pressure stage single operation mode (state in which exhaust flows through the high-pressure stage turbine 42) is exhausted through the series operation mode (through the high-pressure stage turbine 42). The high-pressure turbine 42 is bypassed and the exhaust gas is allowed to flow so as to be higher than that in a state where

  In the present embodiment, the electronic control unit 50 can also switch the operation mode of the supercharging device 12 based on the output Pe (= Te × Ne) of the internal combustion engine 10. For example, the electronic control unit 50 controls the operation mode of the supercharging device 12 to the high-pressure stage single operation mode when the output Pe of the internal combustion engine 10 is in a low output region lower than the set value Pe1. When the output Pe is equal to or higher than the set value Pe1 and in the middle output range lower than the set value Pe2 (Pe2> Pe1), the operation mode of the supercharger 12 is controlled to the series operation mode, and the output Pe of the internal combustion engine 10 is The operation mode of the supercharger 12 can also be controlled to the low pressure stage single operation mode when it is in a high output region that is equal to or greater than the set value Pe2. In this example, the low pressure stage exhaust control valve 24 bypasses the low pressure stage turbine 22 and flows exhaust gas so that the output Pe of the internal combustion engine 10 in the high pressure stage single operation mode is lower than that in the series operation mode. The high-pressure stage exhaust control valve 44 causes the high-pressure stage turbine 42 to bypass and flow exhaust gas so that the output Pe of the internal combustion engine 10 in the low-pressure stage single operation mode is higher than that in the series operation mode.

  In the present embodiment, the electronic control unit 50 can also switch the operation mode of the supercharging device 12 based on the intake air amount Ae supplied to the internal combustion engine 10. For example, when the intake air amount Ae to the internal combustion engine 10 is smaller than the set value Ae1, the electronic control unit 50 controls the operation mode of the supercharger 12 to the high-pressure stage single operation mode, and the intake air amount Ae to the internal combustion engine 10 is controlled. Is set value Ae1 or more and less than set value Ae2 (Ae2> Ae1), the operation mode of supercharger 12 is controlled to the series operation mode, and intake air amount Ae to internal combustion engine 10 is set value Ae2 or more. In addition, the operation mode of the supercharging device 12 can be controlled to the low pressure stage single operation mode. In this example, the low-pressure stage exhaust control valve 24 flows the exhaust by bypassing the low-pressure stage turbine 22 so that the intake air amount Ae to the internal combustion engine 10 in the high-pressure stage single operation mode is lower than in the series operation mode. The high-pressure stage exhaust control valve 44 causes the high-pressure stage turbine 42 to bypass and flow exhaust gas so that the intake air amount Ae to the internal combustion engine 10 in the low-pressure stage single operation mode is higher than that in the series operation mode. The intake air amount Ae supplied to the internal combustion engine 10 can be detected by, for example, a sensor (not shown).

  Also in the example described above, the set value Ne1 (or the set value Pe1 or the set value Ae1) used for the switching determination from the series operation mode to the high pressure stage single operation mode is switched from the high pressure stage single operation mode to the series operation mode. Hysteresis can be provided by setting smaller than the set value Ne1 (or set value Pe1 or set value Ae1) used for the determination. Similarly, a set value Ne2 (or set value Pe2 or set value Ae2) used for switching determination from the low-pressure stage single operation mode to the series operation mode is used as a setting value used for switching determination from the series operation mode to the low-pressure stage single operation mode. Hysteresis can be provided by setting smaller than Ne2 (or set value Pe2 or set value Ae2).

  Further, in the present embodiment, for example, as shown in FIG. 8, the low-pressure turbine 22 and the high-pressure turbine 42 may be provided in parallel with the exhaust passage of the internal combustion engine 10. In the configuration example shown in FIG. 8, the high-pressure turbine bypass flow path 43 connects the inlet 42 a of the high-pressure turbine 42 and the inlet 22 a of the low-pressure turbine 22 by bypassing the high-pressure turbine 42, and the low-pressure turbine bypass flow The passage 23 connects the high-pressure turbine bypass passage 43 (the inlet 22a of the low-pressure turbine 22) and the outlet 22b of the low-pressure turbine 22 by bypassing the low-pressure turbine 22. The low-pressure stage turbine 22 rotationally drives the low-pressure stage compressor 21 using the exhaust energy from the high-pressure stage turbine bypass passage 43. The operation of the configuration example shown in FIG. 8 is the same as that of the configuration example shown in FIG.

  Further, in the present embodiment, as a low-pressure stage intake adjustment valve that adjusts the bypass flow of intake air in the low-pressure stage compressor bypass passage 25, the bypass flow of intake air in the low-pressure stage compressor bypass passage 25 is used instead of the one-way valve 26. It is also possible to use a low-pressure stage intake control valve that can be selectively switched between an allowable open state and a closed state in which the intake-bypass flow in the low-pressure compressor bypass passage 25 is blocked. At that time, the capacity of the low-pressure stage intake control valve is set so that the entire flow rate of the intake air to the internal combustion engine 10 can flow through the low-pressure stage intake control valve. Similarly, as a high-pressure stage intake adjustment valve that regulates the bypass flow of intake air in the high-pressure stage compressor bypass passage 45, an open state that allows the bypass flow of intake air in the high-pressure stage compressor bypass passage 45 instead of the one-way valve 46 It is also possible to use a high-pressure stage intake control valve that can be selectively switched between a closed state in which the bypass flow of intake air in the high-pressure stage compressor bypass passage 45 is blocked. At that time, the capacity of the high-pressure stage intake control valve is set so that the entire flow rate of the intake air to the internal combustion engine 10 can flow through the high-pressure stage intake control valve. The electronic control unit 50 controls the low pressure stage exhaust control valve 24 to be opened, the high pressure stage exhaust control valve 44 to be closed, the low pressure stage intake control valve to be opened, and the high pressure stage intake control valve to be closed. The operation mode of the supercharging device 12 can be controlled to the high pressure stage single operation mode. The electronic control unit 50 controls the low pressure stage exhaust control valve 24 to be closed, the high pressure stage exhaust control valve 44 to be closed, the low pressure stage intake control valve to be closed, and the high pressure stage intake control valve to be closed. Thus, the operation mode of the supercharging device 12 can be controlled to the series operation mode. The electronic control unit 50 controls the low pressure stage exhaust control valve 24 to be closed, the high pressure stage exhaust control valve 44 to be opened, the low pressure stage intake control valve to be closed, and the high pressure stage intake control valve to be opened. Thus, the operation mode of the supercharging device 12 can be controlled to the low pressure stage single operation mode. When the one-way valves 26 and 46 are a low-pressure stage intake control valve and a high-pressure stage intake control valve, the high-pressure stage exhaust control valve 44, the high-pressure stage intake control valve 46, the low-pressure stage exhaust control valve 24, and the low-pressure stage intake control valve The operation modes of the supercharging device 12 can be shifted more continuously using the 26 intermediate opening positions.

  As mentioned above, although the form for implementing this invention was demonstrated, this invention is not limited to such embodiment at all, and it can implement with a various form in the range which does not deviate from the summary of this invention. Of course.

It is a figure showing a schematic structure of a supercharged engine system provided with a supercharging device concerning an embodiment of the present invention. It is a figure explaining an example of the conditions which switch the operation state of the supercharging device which concerns on embodiment of this invention. It is a figure explaining operation | movement of the supercharging apparatus which concerns on embodiment of this invention. It is a figure explaining operation | movement of the supercharging apparatus which concerns on embodiment of this invention. It is a figure explaining operation | movement of the supercharging apparatus which concerns on embodiment of this invention. It is a figure explaining operation | movement of the supercharging apparatus which concerns on embodiment of this invention. It is a figure explaining an example of the conditions which switch the operation state of the supercharging device which concerns on embodiment of this invention. It is a figure which shows the other schematic structure of a supercharged engine system provided with the supercharging device which concerns on embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Internal combustion engine, 12 Supercharging device, 20 Low pressure stage turbocharger, 21 Low pressure stage compressor, 22 Low pressure stage turbine, 23 Low pressure stage turbine bypass flow path, 24 Low pressure stage exhaust control valve, 25 Low pressure stage compressor bypass flow path, 26, 46 One-way valve, 40 High-pressure stage turbocharger, 41 High-pressure stage compressor, 42 High-pressure stage turbine, 43 High-pressure stage turbine bypass flow path, 44 High-pressure stage exhaust control valve, 45 High-pressure stage compressor bypass flow path, 50 Electronic control unit.

Claims (10)

A supercharging device that pressurizes intake air into the engine using engine exhaust energy,
A low-pressure stage compressor that pressurizes the intake air to the engine;
A high-pressure compressor that pressurizes intake air from the low-pressure compressor and supplies it to the engine;
A low-pressure turbine that drives the low-pressure compressor using the exhaust energy of the engine;
A high-pressure turbine that drives the high-pressure compressor using the exhaust energy of the engine;
Low-pressure turbine bypass means capable of flowing exhaust gas from the engine by bypassing the low-pressure turbine;
A low-pressure stage bypass means for bypassing the low-pressure stage compressor and introducing the intake air to the low-pressure stage compressor to the high-pressure stage compressor when the low-pressure stage turbine bypass means bypasses the low-pressure stage turbine and flows exhaust gas;
With
When exhaust flows through a low-pressure turbine, intake air pressurized by the low-pressure compressor and the high-pressure compressor is introduced into the engine,
A supercharging device that bypasses the low-pressure stage compressor and introduces the intake air pressurized by the high-pressure stage compressor to the engine when the exhaust gas flows through the low-pressure stage turbine. The supercharging device according to claim 1,
The low pressure stage compressor bypass means
A low-pressure compressor bypass passage that bypasses the low-pressure compressor and connects the inlet and outlet of the low-pressure compressor;
A low-pressure stage intake regulating valve that regulates the bypass flow of the intake air in the low-pressure stage compressor bypass flow path;
Including
The low-pressure stage intake adjustment valve
If the exhaust flows through the low-pressure stage turbine, allow the bypass flow of the intake air from the inlet to the outlet of the low-pressure compressor,
A supercharger that shuts off the bypass flow of intake air from the outlet to the inlet of a low-pressure compressor when exhaust flows through the low-pressure turbine. The supercharging device according to claim 2,
The supercharging device, wherein the low-pressure stage intake regulating valve is a one-way valve. The supercharging device according to any one of claims 1 to 3,
The low pressure stage turbine bypass means is configured so that at least one of the engine speed and torque when the exhaust gas flows through the low pressure stage turbine is lower than when the exhaust gas flows through the low pressure stage turbine. A turbocharger that bypasses the exhaust and flows exhaust gas. The supercharging device according to any one of claims 1 to 4,
High-pressure turbine bypass means capable of flowing exhaust gas from the engine by bypassing the high-pressure turbine;
When the high-pressure turbine bypass means bypasses the high-pressure turbine and flows exhaust gas, the high-pressure compressor bypass means for introducing the intake air from the low-pressure compressor into the engine by bypassing the high-pressure compressor;
Further comprising
A supercharging device in which, when exhaust flows by bypassing a high-pressure turbine, intake air pressurized by a low-pressure compressor and bypassing the high-pressure compressor is introduced into the engine. The supercharging device according to claim 5,
High pressure compressor bypass means
A high-pressure compressor bypass passage that bypasses the high-pressure compressor and connects the inlet and outlet of the high-pressure compressor;
A high-pressure stage intake regulating valve that regulates the bypass flow of the intake air in the high-pressure stage compressor bypass flow path;
Including
The high-pressure stage intake adjustment valve
When exhaust flows by bypassing the high-pressure turbine, allow bypass flow of intake air from the inlet to the outlet of the high-pressure compressor,
A turbocharger that shuts off the bypass flow of intake air from the outlet to the inlet of the high-pressure compressor when the exhaust flows through the high-pressure turbine. The supercharging device according to claim 6, wherein
The supercharging device, wherein the high-pressure stage intake regulating valve is a one-way valve. The supercharging device according to any one of claims 5 to 7,
The high-pressure stage turbine bypass means is configured so that at least one of the engine speed and torque when the exhaust gas flows by bypassing the high-pressure turbine is higher than when the exhaust gas flows through the high-pressure turbine. A turbocharger that bypasses the exhaust and flows exhaust gas. The supercharging device according to any one of claims 1 to 8,
A supercharging device, wherein the engine is a cylinder injection internal combustion engine that injects fuel into a cylinder. Engine,
A supercharging device that pressurizes intake air into the engine using engine exhaust energy;
A supercharged engine system comprising:
A supercharged engine system, wherein the supercharger is the supercharger according to any one of claims 1 to 9.

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