JP2018204487A - EGR control device and EGR control program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an EGR control device and an EGR control program capable of efficiently controlling EGR of an internal combustion engine provided with a turbocharger, a compressor, and two kinds of exhaust gas recirculation units. SOLUTION: An internal combustion engine 38 is connected to a series intake path connecting an electric compressor 32 in series to a turbocharger 34, a parallel intake path connecting in parallel, or a bypass intake path bypassing the electric compressor 32. Valves B to D22 to 26 for switching the intake path and EGR gas recirculation by the HPL-EGR mechanism 40, EGR gas recirculation by the LPL-EGR mechanism 42, EGR gas by each of the HPL-EGR mechanism 40 and the LPL-EGR mechanism 42 Valve A20 and valve E28 that are switched to each other without recirculation of EGR gas or EGR gas, and a control unit that controls each of the electric compressor motor 30 and each of the valves A to E20 to 28 based on a predetermined operating condition. Prepare [Selection diagram] Figure 1

Description

  The present invention is provided with an EGR control device and an EGR control that are equipped with an LPL (Low Pressure Loop) -EGR (Exhaust Gas Recirculation) mechanism and an HPL (High Pressure Loop) -EGR mechanism to control EGR to recirculate exhaust gas to an intake passage. Regarding the program.

  Various technologies have been proposed as EGR control devices. For example, in the technique described in Patent Document 1, the engine includes a supercharger, an electric compressor provided in an EGR passage, an LPL-EGR mechanism, and an HPL-EGR mechanism, and performs EGR according to the operating state of the engine. I have control.

  Specifically, an intake port connected to the intake passage and an EGR port connected to an EGR passage branched from the exhaust passage are connected to the combustion chamber of the engine. An electric compressor is provided in the EGR passage. When the engine load is light, EGR gas from HPL-EGR is supplied to the engine from the EGR port via the EGR passage. When the engine load is high, the valve is opened and closed so that the exhaust gas flows into the electric compressor through the EGR passage, and the EGR gas from the LPL-EGR is supplied to the engine from the EGR port. Further, when accelerating, the electric compressor and the supercharger are connected in series to supply fresh air from the intake port and the EGR port.

JP-A-2005-23900

  However, in Patent Document 1, an LPL-EGR passage is provided, but unless the electric compressor is operated, EGR gas by LPL-EGR cannot be supplied. If an electric compressor is used during steady operation, electricity is consumed for supercharging, resulting in poor fuel consumption. For this reason, it is desirable to perform steady operation without using an electric compressor in a region that can be operated by supercharging of the supercharger. However, in steady operation without using an electric compressor, a catalyst warm-up effect can be obtained by LPL-EGR. I can't. In addition, there is room for improvement because problems such as reduction in supercharger efficiency and deterioration in fuel efficiency occur due to a decrease in the exhaust flow rate to the turbine at light loads.

  The present invention has been made in consideration of the above facts, and is an EGR control device capable of efficiently controlling EGR of an internal combustion engine having a turbocharger, a compressor, and two types of exhaust gas recirculation units, and An object is to provide an EGR control program.

  In order to achieve the above object, an EGR control device according to the present invention provides a compressor capable of switching between compression and non-compression of intake air with respect to a turbocharger that compresses intake air using exhaust pressure. A path switching unit that switches the intake path of the internal combustion engine to a serial path that is connected in series, a parallel path that connects the compressor in parallel to the turbocharger, or a bypass path that bypasses the compressor; and an exhaust path The EGR gas taken out from the exhaust gas is recirculated by the first exhaust gas recirculation unit that recirculates the EGR gas from the turbocharger to the intake air downstream side of the turbocharger, and is taken out from the exhaust gas downstream side of the first exhaust gas recirculation unit Recirculation of EGR gas by a second exhaust recirculation unit that recirculates EGR gas to the intake path upstream of the turbocharger, and each of the first exhaust recirculation unit and the second exhaust recirculation unit Based on the EGR switching unit that switches EGR gas recirculation or no EGR gas recirculation, and the predetermined operating condition of the internal combustion engine, the compressor, the path switching unit, and the EGR switching unit are controlled. A control unit.

  The serial path may connect the compressor in series to the turbocharger on the intake downstream side of the turbocharger.

  The control unit is configured to perform the turbocharging when a predetermined operating condition for recirculating EGR gas, an operating condition that does not require compression of intake air by the compressor, and a recirculation of EGR gas by the second exhaust recirculation unit. In an operating condition where the operating point of the machine does not reach a flow rate higher than the extreme value of efficiency, the intake path is switched to the bypass path while the compressor is in an uncompressed state, and EGR gas is Each of the compressor, the path switching unit, and the EGR switching unit may be controlled so as to recirculate.

  The control unit includes a predetermined operating condition for recirculating EGR gas, an operating condition for which compression of intake air by the compressor is unnecessary, and the turbocharger when the EGR gas is recirculated by the second exhaust recirculation unit When the operating point is an operating condition where the flow rate is higher than the extreme value of efficiency, and the operating point when the EGR gas is recirculated by the first exhaust gas recirculation unit is lower than the extreme value of efficiency. Further, the compression is performed so that the intake passage is switched to the bypass passage while the compressor is in an uncompressed state, and the EGR gas is recirculated by each of the first exhaust recirculation unit and the second exhaust recirculation unit. Each of the machine, the path switching unit, and the EGR switching unit may be controlled.

  The control unit includes a predetermined operating condition for recirculating EGR gas, an operating condition for which compression of intake air by the compressor is unnecessary, and the turbocharger when the EGR gas is recirculated by the second exhaust recirculation unit When the operating point is an operating condition in which the flow rate is higher than the extreme value of efficiency and the operating point when the EGR gas is recirculated by the first exhaust gas recirculation unit is not lower than the extreme value of efficiency. Further, the compressor, the path switching unit, and the EGR are switched so that the intake path is switched to the bypass path while the compressor is in an uncompressed state, and the EGR gas is recirculated by the first exhaust gas recirculation unit. Each of the switching units may be controlled.

  The controller is configured to switch the intake path to a serial path in a state where a predetermined operating condition for recirculating EGR gas, an operating condition where the compressor needs to compress intake air, and the compressor is in a compressed state. (2) When the operating point of the turbocharger when the EGR gas is recirculated by the exhaust gas recirculation unit does not reach a higher flow rate than the extreme value of efficiency, the compressor is in a compressed state and the intake path is Each of the compressor, the path switching unit, and the EGR switching unit may be controlled such that the EGR gas is recirculated by the second exhaust gas recirculation unit by switching to the series path.

  The control unit is configured to switch the intake path to a serial path in a state where a predetermined operating condition for recirculating EGR gas, an operating condition that requires compression of the intake air by the compressor, and the compressor is in a compressed state. An operating condition in which the operating point of the turbocharger when the EGR gas is recirculated by the exhaust gas recirculation unit is higher than the extreme value of efficiency, and the compressor is in a compressed state, the intake path is changed to the series path. When the EGR gas is recirculated by the first exhaust gas recirculation unit after switching, the operating condition of the turbocharger becomes a lower flow rate side than the extreme value of efficiency, and the intake air while the compressor is in a compressed state When the operating condition of the turbocharger when the path is switched to the parallel path and the EGR gas is recirculated by the second exhaust recirculation unit does not reach the higher flow rate side than the extreme value of efficiency, or EGR Gas A predetermined operating condition for flowing, an operating condition that requires compression of the intake air by the compressor, and switching the intake path to a serial path when the compressor is in compression, and EGR gas is generated by the second exhaust recirculation unit. The operating condition in which the operating point of the turbocharger when recirculated is higher than the extreme value of the efficiency, and the compressor is in a compressed state, the intake path is switched to the series path and the first exhaust gas recirculation is performed. Operating conditions in which the operating point of the turbocharger when the EGR gas is recirculated by the unit is on the lower flow rate side than the extreme value of efficiency, and the compressor is in a compressed state, the intake path is switched to the parallel path and the The operating conditions of the turbocharger when the EGR gas is recirculated by the second exhaust recirculation unit are operating conditions in which the operating point of the turbocharger is higher than the extreme value of efficiency, and the compressor is in a compressed state, and the intake passage is connected in series. Switch to route The operating point of the turbocharger when the EGR gas is recirculated by the second exhaust gas recirculation unit, and the first exhaust gas recirculation unit by switching the intake path to the serial path when the compressor is compressed. The efficiency of the operating point calculated from the operating point of the turbocharger when the EGR gas is recirculated by switching the intake path to the parallel path while the compressor is in compression is the second exhaust. The operating point of the turbocharger when the EGR gas is recirculated by the recirculation unit, and the intake path is switched to the parallel path while the compressor is compressed, and the EGR gas is generated by the first exhaust recirculation unit. When the operating condition is higher than the efficiency of the operating point calculated from the operating point of the turbocharger when recirculating, the compressor switches the intake path to the series path in a compressed state, and the first Exhaust gas recirculation Each of the compressor, the path switching unit, and the EGR switching unit may be controlled so that EGR gas is recirculated by each of the first exhaust gas recirculation unit and the second exhaust gas recirculation unit.

  The control unit is configured to switch the intake path to a serial path in a state where a predetermined operating condition for recirculating EGR gas, an operating condition that requires compression of the intake air by the compressor, and the compressor is in a compressed state. An operating condition in which the operating point of the turbocharger when the EGR gas is recirculated by the exhaust gas recirculation unit is higher than the extreme value of efficiency, and the compressor is in a compressed state, the intake path is changed to the series path. When the EGR gas is recirculated by the first exhaust gas recirculation unit, the operating point of the turbocharger does not become a lower flow rate side than the extreme value of efficiency, and the intake path is in a state where the compressor is compressed When the EGR gas is recirculated by the second exhaust gas recirculation unit and the operating point of the turbocharger does not reach the higher flow rate than the extreme value of efficiency, and the compressor is compressed In the state of More than the operating point of the turbocharger when the intake path is switched to the parallel path and the EGR gas is recirculated by the second exhaust recirculation unit, the intake path is connected in series with the compressor in a compressed state. When the operating point of the turbocharger when the EGR gas is recirculated by the first exhaust gas recirculation unit by switching to a path is an operating condition with higher efficiency, the compressor is in the compressed state and the intake path May be controlled to each of the compressor, the path switching unit, and the EGR switching unit so that the EGR gas is recirculated by the first exhaust gas recirculation unit.

  The control unit is configured to switch the intake path to a serial path in a state where a predetermined operating condition for recirculating EGR gas, an operating condition that requires compression of the intake air by the compressor, and the compressor is in a compressed state. An operating condition in which the operating point of the turbocharger when the EGR gas is recirculated by the exhaust gas recirculation unit is higher than the extreme value of efficiency, and the compressor is in a compressed state, the intake path is changed to the series path. When the EGR gas is recirculated by the first exhaust gas recirculation unit, the operating point of the turbocharger does not become a lower flow rate side than the extreme value of efficiency, and the intake path is in a state where the compressor is compressed When the EGR gas is recirculated by the second exhaust gas recirculation unit and the operating point of the turbocharger does not reach the higher flow rate than the extreme value of efficiency, and the compressor is compressed In the state of More than the operating point of the turbocharger when the intake path is switched to the serial path and the EGR gas is recirculated by the first exhaust recirculation unit, the intake path is arranged in parallel with the compressor being compressed. When the operating point of the turbocharger when the EGR gas is recirculated by the second exhaust gas recirculation unit by switching to a path is an operating condition with higher efficiency, the compressor is in a compressed state and the intake path May be switched to the parallel path, and each of the compressor, the path switching unit, and the EGR switching unit may be controlled so that the EGR gas is recirculated by the second exhaust gas recirculation unit.

  The control unit is configured to switch the intake path to a serial path in a state where a predetermined operating condition for recirculating EGR gas, an operating condition that requires compression of the intake air by the compressor, and the compressor is in a compressed state. An operating condition in which the operating point of the turbocharger when the EGR gas is recirculated by the exhaust gas recirculation unit is higher than the extreme value of efficiency, and the compressor is in a compressed state, the intake path is changed to the series path. When the EGR gas is recirculated by the first exhaust gas recirculation unit, the operating point of the turbocharger does not become a lower flow rate side than the extreme value of efficiency, and the intake path is in a state where the compressor is compressed When the EGR gas is recirculated by the second exhaust gas recirculation unit and the operating point of the turbocharger is higher than the extreme value of efficiency, and the compressor is compressed. In the state When the operating condition of the turbocharger when the path is switched to the parallel path and the EGR gas is recirculated by the first exhaust recirculation unit is not at a higher flow rate than the extreme value of efficiency, or EGR A predetermined operating condition for recirculating gas, an operating condition that requires compression of the intake air by the compressor, and switching the intake path to a serial path while the compressor is compressed, and the second exhaust gas recirculation unit performs EGR. The operating condition in which the operating point of the turbocharger when the gas is recirculated is higher than the extreme value of efficiency, and the compressor is in a compressed state, the intake path is switched to the series path, and the first exhaust When the EGR gas is recirculated by the recirculation unit, the operating condition of the turbocharger becomes a lower flow rate side than the extreme value of efficiency, and the intake path is switched to the parallel path when the compressor is in a compressed state. The operating condition of the turbocharger when the EGR gas is recirculated by the second exhaust gas recirculation unit is set to a higher flow rate side than the extreme value of efficiency, and the compressor is in a compressed state to pass the intake path The operation point of the turbocharger when the EGR gas is recirculated by the second exhaust gas recirculation unit by switching to the serial path, and the intake path is switched to the serial path while the compressor is compressed. The efficiency of the operating point calculated from the operating point of the turbocharger when the EGR gas is recirculated by one exhaust gas recirculation unit switches the intake path to the parallel path when the compressor is in compression. The operating point of the turbocharger when EGR gas is recirculated by the second exhaust gas recirculation unit, and the first exhaust gas recirculation by switching the intake path to the parallel path when the compressor is compressed Depending on the part EGR When the operating condition is not higher than the efficiency of the operating point calculated from the operating point of the turbocharger when the gas is recirculated, the compressor switches the intake path to the parallel path in a compressed state, Each of the compressor, the path switching unit, and the EGR switching unit may be controlled so that EGR gas is recirculated by each of the first exhaust gas recirculation unit and the second exhaust gas recirculation unit.

  The control unit is configured to switch the intake path to a serial path in a state where a predetermined operating condition for recirculating EGR gas, an operating condition that requires compression of the intake air by the compressor, and the compressor is in a compressed state. An operating condition in which the operating point of the turbocharger when the EGR gas is recirculated by the exhaust gas recirculation unit is higher than the extreme value of efficiency, and the compressor is in a compressed state, the intake path is changed to the series path. When the EGR gas is recirculated by the first exhaust gas recirculation unit, the operating point of the turbocharger does not become a lower flow rate side than the extreme value of efficiency, and the intake path is in a state where the compressor is compressed When the EGR gas is recirculated by the second exhaust gas recirculation unit and the operating point of the turbocharger is higher than the extreme value of efficiency, and the compressor is compressed. In the state If the operating point of the turbocharger when the EGR gas is recirculated by the first exhaust gas recirculation unit by switching the path to the parallel path is an operating condition where the operating point is higher than the extreme value of efficiency, the compression Each of the compressor, the path switching unit, and the EGR switching unit is configured to switch the intake path to the parallel path in a compressed state and to recirculate EGR gas by the first exhaust recirculation unit. You may control.

  When the control unit switches the intake path to the series path in a predetermined operating condition that does not recirculate EGR gas, an operating condition that requires compression of the intake air by the compressor, and the compressor is in a compressed state When the operating point of the turbocharger is such that the operating point is not higher than the extreme value of efficiency, the intake path is switched to the series path while the compressor is in a compressed state, and there is no recirculation of EGR gas. Each of the compressor, the path switching unit, and the EGR switching unit may be controlled so that

  When the control unit switches the intake path to the series path in a predetermined operating condition that does not recirculate EGR gas, an operating condition that requires compression of the intake air by the compressor, and the compressor is in a compressed state In the operating condition where the operating point of the turbocharger is higher than the extreme value of the efficiency, the intake path is switched to the parallel path while the compressor is in a compressed state, and there is no recirculation of EGR gas. Each of the compressor, the path switching unit, and the EGR switching unit may be controlled so that

  The control unit is configured to bypass the intake path when the compressor is in an uncompressed state under a predetermined operating condition in which EGR gas is not recirculated and an operating condition in which the compressor does not need to compress intake air. The compressor, the path switching unit, and the EGR switching unit may be controlled so that the EGR gas does not recirculate.

  On the other hand, the EGR control program according to the present invention for achieving the above object causes a computer to function as a control unit in the above EGR control device.

  As described above, according to the present invention, it is possible to efficiently control EGR of an internal combustion engine including a turbocharger, a compressor, and two types of exhaust gas recirculation units.

It is a figure which shows the structure of the internal combustion engine periphery used as the control object of the EGR control apparatus which concerns on this embodiment. It is a block diagram which shows schematic structure of the EGR control apparatus which concerns on this embodiment. (A) is an operable region when the LPL-EGR mechanism is operated with the electric compressor connected in series with the turbocharger, and (B) is the HPL-EGR with the electric compressor connected in series with the turbocharger. Operating range when the mechanism is activated, (C) is the operable range when the LPL-EGR mechanism is operated with the electric compressor connected in parallel to the turbocharger, and (D) is the turbocharging of the electric compressor It is a figure which respectively shows the driving | operation possible area | region at the time of connecting to a machine in parallel and operating the HPL-EGR mechanism. It is a figure which shows arrangement | positioning of the electric compressor suitable for every load (rotation speed and torque) of an internal combustion engine, and an EGR system. (A) is a figure which shows the example which arranged the electric compressor and the turbocharger in series, and actuated the LPL-EGR mechanism, (B) is a figure which shows the efficiency map of the turbo compressor in the case of (A) It is. (A) is a figure which shows the example which has arrange | positioned the electric compressor and the turbocharger in parallel, (B) is a figure which shows the efficiency map of the turbo compressor in the case of (A). (A) is a figure which shows the example which operated the LPL-EGR mechanism, without operating an electric compressor, (B) is a figure which shows the example which operated the HPL-EGR mechanism, without operating an electric compressor. (A) is a figure which shows the comparison result of LPL-EGR and HPL-EGR in the flow volume of an electric compressor, the flow volume to a turbine, supercharger work, and exhaust energy, (B) is the figure of the turbo compressor by an EGR system. It is a figure for demonstrating the movement of an operating point. (A) is a figure which shows the example which operated the LPL-EGR mechanism and stopped the electric compressor, (B) is a figure which shows the efficiency map of the turbo compressor in the case of (A). (A) is a figure which shows the example which operated the LPL-EGR mechanism and the HPL-EGR mechanism, and stopped the electric compressor, (B) is a figure which shows the efficiency map of the turbo compressor in the case of (A). . (A) is a figure which shows the example which act | operated the HPL-EGR mechanism and stopped the electric compressor, (B) is a figure which shows the efficiency map of the turbo compressor in the case of (A). (A) is a figure which shows the example which act | operated by connecting an electric compressor in series by operating an LPL-EGR mechanism, (B) is a figure which shows the efficiency map of the turbo compressor in the case of (A). (A) is a figure which shows the example which act | operated by connecting the electric compressor in series by operating the LPL-EGR mechanism and the HPL-EGR mechanism, and (B) shows the efficiency map of the turbo compressor in the case of (A). FIG. (A) is a figure which shows the example which act | operated by operating an HPL-EGR mechanism and connecting an electric compressor in series, (B) is a figure which shows the efficiency map of the turbo compressor in the case of (A). (A) is a figure which shows the example which act | operated by connecting an electric compressor in parallel by operating an LPL-EGR mechanism, (B) is a figure which shows the efficiency map of the turbo compressor in the case of (A). (A) is a figure which shows the example which act | operated by connecting the electric compressor in parallel by operating the LPL-EGR mechanism and the HPL-EGR mechanism, and (B) shows the efficiency map of the turbo compressor in the case of (A). FIG. (A) is a figure which shows the example which act | operated by connecting the electric compressor in parallel by operating an HPL-EGR mechanism, (B) is a figure which shows the efficiency map of the turbo compressor in the case of (A). (A) is a figure which shows the example which act | operated by connecting an electric compressor in series without EGR, (B) is a figure which shows the efficiency map of the turbo compressor in the case of (A). (A) is a figure which shows the example which act | operated by connecting an electric compressor in parallel without EGR, (B) is a figure which shows the efficiency map of the turbo compressor in the case of (A). (A) is a figure which shows the example which stopped the electric compressor, without EGR, (B) is a figure which shows the efficiency map of the turbo compressor in the case of (A). (A) is a figure which shows the presence or absence of the action | operation of the electric compressor in each of (1)-(12), the connection of the electric compressor 32, and an EGR system, (B) is in each of (1)-(12). It is a figure which shows the open / close state of each valve | bulb. It is a flowchart which shows an example of the flow of the process performed by the control part of the EGR control apparatus which concerns on this embodiment.

  Hereinafter, an example of an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram illustrating a configuration around an internal combustion engine that is a control target of the EGR control device according to the present embodiment.

  As shown in FIG. 1, the internal combustion engine 38 includes an electric compressor 32 as a compressor, an intercooler 36, a turbocharger 34, an HPL-EGR mechanism 40 as a first exhaust recirculation unit, and a second exhaust recirculation. An LPL-EGR mechanism 42 as a circulation unit is provided.

  In the present embodiment, a series intake path 46 as a series path in which the turbocharger 34 and the electric compressor 32 are connected in series, a parallel intake path 48 as a parallel path connected in parallel, and the turbocharger 34. And a bypass intake path 50 as a bypass path that bypasses the electric compressor 32 by passing only through the electric compressor 32.

  In the series intake path 46, the intake air passes in the order of the turbo compressor 33 of the turbocharger 34, the intercooler 36, and the compressor 31 of the electric compressor 32 along the intake path of the internal combustion engine 38. It flows into the internal combustion engine 38.

  The parallel intake path 48 is configured such that the compressor 31 of the electric compressor 32 is connected in parallel to the turbo compressor 33 of the turbocharger 34 along the intake path of the internal combustion engine 38, and the intake air is It passes through each of the turbo compressor 33 and the compressor 31. In addition, the air that has passed through the turbo compressor 33 and passed through the intercooler 36 and the air that has passed through the compressor 31 of the electric compressor 32 merge and flow into the internal combustion engine 38.

  The bypass intake path 50 passes along the intake path of the internal combustion engine 38 in the order of the turbo compressor 33 and the intercooler 36 of the turbocharger 34 and flows into the internal combustion engine 38.

  The series intake passage 46 is provided with a valve C24 that can be controlled to open and close on the intake upstream side of the electric compressor 32, and the parallel intake passage 48 is provided with a valve B22 that can be controlled to open and close the intake air of the electric compressor 32. It is provided upstream. The bypass intake path 50 is provided with a valve D26 that can be opened and closed on the intake downstream side of the intercooler 36. By controlling the opening and closing of each valve, the intake path can be switched.

  On the other hand, the exhaust gas discharged from the internal combustion engine 38 is discharged through the turbine 35 of the turbocharger 34, and the turbine 35 is driven by the exhaust gas, whereby the intake air is compressed by the turbo compressor 33. .

  Each of the HPL-EGR mechanism 40 and the LPL-EGR mechanism 42 takes out the exhaust gas discharged from the internal combustion engine 38 and recirculates the EGR gas to the intake path of the internal combustion engine 38.

  Specifically, in the HPL-EGR mechanism 40, an exhaust gas extraction port is provided in an exhaust passage such as an exhaust manifold of the internal combustion engine 38, and an exhaust gas recirculation port is provided in an intake passage such as an intake manifold. A valve E28 (HPL-EGR valve) is provided between the outlet of the HPL-EGR mechanism 40 and the reflux port. The valve E28 can be controlled to be opened and closed. When the valve E28 is opened, the EGR gas is recirculated to the intake path by the HPL-EGR mechanism 40.

  On the other hand, the LPL-EGR mechanism 42 is provided with an exhaust gas extraction port on the exhaust downstream side of the exhaust gas extraction port of the HPL-EGR mechanism 40 and on the exhaust gas downstream side of the turbine 35. An exhaust gas recirculation port is provided on the upstream side of the path. A valve A20 (LPL-EGR valve) and an EGR cooler 44 are provided between the take-out port and the return port of the LPL-EGR mechanism 42. The valve A20 can be controlled to be opened and closed, and when opened, the EPL gas is recirculated to the intake path by the LPL-EGR mechanism 42. The EGR cooler 44 is provided closer to the intake path than the valve A20, and cools the EGR gas returning to the intake path.

  In the present embodiment, the parallel intake passage 48 is connected to the electric compressor 32 from between the EGR gas return port of the EGR cooler 44 and the LPL-EGR mechanism 42. By opening the valve B22 provided in the parallel intake path 48, EGR gas or fresh air by the LPL-EGR mechanism 42 can be introduced into the parallel intake path 48.

  Note that the valve B22, the valve C24, and the valve D26 correspond to a path switching unit, and the valve A20 and the valve E28 correspond to an EGR switching unit.

  Next, the configuration of the EGR control device 10 according to the present embodiment will be described. FIG. 2 is a block diagram illustrating a schematic configuration of the EGR control device 10 according to the present embodiment.

  The EGR control device 10 includes a control unit 12 that controls EGR of the internal combustion engine 38. For example, as shown in FIG. 2, the control unit 12 includes a computer in which a CPU 12A, a ROM 12B, a RAM 12C, and an I / O (input / output interface) 12D are connected to a bus 12E.

  The ROM 12B stores a program for controlling the EGR, various data, and the like. The program stored in the ROM 12B is expanded in the RAM 12C and executed by the CPU 12A, whereby EGR is controlled.

  A throttle sensor 14, a crank angle sensor 16, an airflow sensor 18, a valve A20, a valve B22, a valve C24, a valve D26, a valve E28, and an electric compressor motor 30 are connected to the I / O 12D.

  The throttle sensor 14 detects the opening degree of the throttle valve or the accelerator and outputs the detection result to the control unit 12.

  The crank angle sensor 16 detects the crank angle of the internal combustion engine 38 in order to detect the rotational speed and outputs the detection result to the control unit 12.

  The airflow sensor 18 detects the flow rate of air flowing into the internal combustion engine 38 and outputs the detection result to the control unit 12.

  The valve A20, the valve B22, the valve C24, the valve D26, and the valve E28 are opened and closed under the control of the control unit 12, respectively.

  The electric compressor motor 30 is driven to rotate under the control of the control unit 12, and the intake air is compressed by the compressor 31.

  The control unit 12 controls driving of each valve and the electric compressor motor 30 based on the operating condition of the internal combustion engine 38. Specifically, the control unit 12 controls the operation of the HPL-EGR mechanism and the LPL-EGR mechanism 42 based on the detection result of each sensor, the operation of the electric compressor 32, and the operation of the electric compressor 32. The connection (parallel connection or series connection) to the turbocharger 34 is controlled. The operation of the HPL-EGR mechanism 40 and the LPL-EGR mechanism 42 is basically performed by the control unit 12 controlling each valve according to a predetermined map to recirculate the EGR gas.

  By the way, when the electric compressor 32 is arranged on the intake downstream side of the turbocharger 34, the operating point of the turbo compressor 33 varies depending on the arrangement of the electric compressor 32 and the turbocharger 34. Specifically, when connected in series, the flow rate to the turbo compressor 33 increases due to the auxiliary supercharging of the electric compressor 32. On the other hand, when connected in parallel, the turbo compressor 33 and the electric compressor 32 are distributed and supercharged, so the flow rate to the turbo compressor 33 decreases. The operating point of the turbo compressor 33 changes depending on whether EGR is set to LPL or HPL. Specifically, when the LPL is used, the EGR gas is recirculated from the exhaust downstream side of the turbine 35 to the intake upstream side of the turbo compressor 33, so that the passing flow rate of the turbo compressor 33 is higher than that of the HPL. When HPL is used, EGR gas is recirculated from the exhaust upstream side of the turbine 35 to the intake air downstream side of the electric compressor 32. Therefore, the EGR gas does not pass through the turbo compressor 33, and the flow rate to the turbo compressor 33 is smaller than that of the LPL. Become. Generally, the supercharger efficiency is different from the operating point of the turbo compressor 33, and if supercharging is performed at an operating point with a low supercharger efficiency, the pump loss increases and the fuel consumption of the internal combustion engine 38 decreases. .

  It is also known that by connecting the electric compressor 32 in series to the turbocharger 34, the responsiveness of supercharging can be improved and the acceleration performance is improved. Here, when the electric compressor 32 is connected in series to the turbocharger 34 and the HPL-EGR mechanism 40 is operated and when the LPL-EGR mechanism 42 is operated, the operable range is shown in FIGS. Shown in B). By appropriately switching the EGR method, supercharging can be performed from low speed to medium speed during steady operation. In particular, in order to comply with the new regulations, there is a problem that the efficiency of the electric compressor 32 is reduced due to the choke or the power output limit in the middle speed range where the EGR amount is required.

  On the other hand, when the electric compressor 32 is connected in parallel to the turbocharger 34 and the HPL-EGR mechanism 40 is operated and the LPL-EGR mechanism 42 is operated, the operable region is shown in FIG. Shown in (D). By connecting in parallel, even if supercharging assistance of the electric compressor 32 with good responsiveness is performed, the boosted gas escapes to the turbocharger 34 side in the transient state, so the responsiveness of supercharging is not improved. Therefore, in general, the electric compressor 32 is not connected in parallel to the turbocharger 34. However, as shown in FIGS. 3C and 3D, it is possible to perform supercharging assist from medium speed to high speed during steady operation.

  As described above, the superchargeable areas are limited due to differences in the connection (parallel connection or direct connection) of the electric compressor 32 to the turbocharger 34 and the EGR method, and the superchargeable areas are respectively Is different.

  Therefore, in the present embodiment, the turbocharger 34 and the electric compressor 32 are provided, and the arrangement of the electric compressor 32 can be selected from a series connection or a parallel connection with respect to the turbocharger 34, and the EGR method is also LPL or HPL. The configuration is selectable. Then, the arrangement of the electric compressor 32 and the combination of the EGR method are selected according to the operating conditions (for example, the load and the rotational speed) of the internal combustion engine 38. As a result, the conventional internal combustion engine can be operated even under conditions where the turbocharger has entered the surge or choke region and could not be operated.

  Further, by selecting the combination, the operating point can be moved to an efficient region of the turbocharger 34, so that the supercharging efficiency can be improved and the fuel consumption can be improved. As shown in FIG. 4, the combination of the arrangement of the electric compressor 32 and the EGR method is based on the load of the internal combustion engine 38, the number of revolutions, the intake air flow rate, the EGR rate, the ratio of LPL and HPL, and the turbo compressor 33 of the turbocharger 34. The operating point is estimated and the one with the highest efficiency is selected.

  Here, the movement of the operating point of the turbocharger 34 by the arrangement of the electric compressor 32 will be described.

  Since the electric compressor 32 obtains power from electric power such as a battery, supercharging can be performed without using exhaust energy. Therefore, it is known that by using the electric compressor 32 and the turbocharger 34 in combination, the work amount obtained from the exhaust energy can be reduced, and the pump loss can be reduced.

  Since the operating point of the turbo compressor 33 of the turbocharger 34 varies depending on the arrangement of the electric compressor 32 and the turbocharger 34, it will be described below.

  As shown in FIG. 5A, when the electric compressor 32 and the turbocharger 34 are arranged in series, as shown in FIG. 5B, the working gas boosted by the turbocharger 34 is further increased. The electric compressor 32 boosts the pressure. For this reason, the pressure at the intake port increases, and the flow rate of the turbocharger 34 passing through the turbo compressor 33 increases. As a result, the operating point of the turbo compressor 33 moves to the high flow rate side. Therefore, when the intake air amount of the internal combustion engine 38 is small, the operating point of the turbo compressor 33 moves to a high efficiency region.

  Further, in the case of supercharger work equal to that before the start of the electric compressor 32, the flow rate of the turbocharger 34 to the turbo compressor 33 increases, so the pressure ratio of the turbocharger 34 decreases. However, since the electric compressor 32 increases the pressure, the total intake pressure increases.

  On the other hand, when the electric compressor 32 and the turbocharger 34 are arranged in parallel as shown in FIG. 6A, the working gas flowing into the turbocharger 34 is shown in FIG. 6B. The electric compressor 32 receives a part and boosts the pressure. At this time, the flow rate boosted by the electric compressor 32 is determined by the output of the electric compressor 32 and the ratio of the turbocharger work of the turbocharger 34. Since the flow rate passing through the turbo compressor 33 decreases, the operating point of the turbo compressor 33 moves to the low flow rate side. Therefore, when the intake air amount of the internal combustion engine 38 is large, the operating point of the turbo compressor 33 moves to a region where the efficiency is high.

  Further, in the case of supercharger work equal to that before the start of the electric compressor 32, the flow rate of the turbo compressor 33 decreases, so the pressure ratio in the turbocharger 34 increases.

  Next, the movement of the operating point of the turbocharger 34 by the EGR method will be described.

  In the LPL-EGR mechanism 42, the EGR gas is recirculated from the exhaust downstream side of the turbine 35 to the intake upstream side of the turbo compressor 33 as shown in FIG. More than when the EGR mechanism 40 is operated. Therefore, the supercharger work becomes larger than HPL. Since the exhaust energy flowing into the turbine 35 is large, the turbocharger work can be obtained even at a low flow rate and a low load.

  On the other hand, in the HPL-EGR mechanism 40, as shown in FIG. 7B, the EGR gas is recirculated from the upstream side of the exhaust from the turbine 35 to the downstream side of the intake of the electric compressor 32 using the differential pressure between the intake and exhaust. . Therefore, the EGR gas does not pass through the turbo compressor 33, and the flow rate to the turbo compressor 33 is reduced as compared with the LPL. Therefore, the supercharger work is smaller than that of LPL.

  That is, as shown in FIG. 8A, the flow rate to the turbo compressor 33 is higher in the LPL than the HPL, and the flow rate to the turbine is higher in the LPL than in the HPL. Further, the supercharger work is larger in the LPL than the HPL, and the exhaust energy is larger in the LPL than the HPL. Further, as shown in FIG. 8B, the HPL operating point moves to the low flow rate side, and the LPL operating point moves to the high flow rate side.

  Next, the arrangement of the electric compressor 32 and the turbocharger 34 and each combination of the HPL-EGR mechanism 40 and the LPL-EGR mechanism 42 will be described.

  In the present embodiment, the arrangement of the electric compressor 32 and the turbocharger 34 and the combinations of the HPL-EGR mechanism 40 and the LPL-EGR mechanism 42 are 12 types (1) to (12) as shown below. It is possible to switch to.

(1) The electric compressor 32 is stopped by operating the LPL-EGR mechanism 42.

(2) The LPL-EGR mechanism 42 and the HPL-EGR mechanism 40 are operated to stop the electric compressor 32.

(3) The HPL-EGR mechanism 40 is operated to stop the electric compressor 32.

(4) The LPL-EGR mechanism 42 is operated to operate the electric compressor 32 connected in series.

(5) The LPL-EGR mechanism 42 and the HPL-EGR mechanism 40 are operated to operate the electric compressor 32 in series.

(6) The HPL-EGR mechanism 40 is operated to operate the electric compressor 32 connected in series.

(7) The LPL-EGR mechanism 42 is operated to operate the electric compressor 32 in parallel.

(8) The LPL-EGR mechanism 42 and the HPL-EGR mechanism 40 are operated to operate the electric compressor 32 in parallel.

(9) The HPL-EGR mechanism 40 is operated to operate the electric compressor 32 in parallel.

(10) Operates by connecting the electric compressor 32 in series without EGR.

(11) Operates by connecting the electric compressor 32 in parallel without EGR.

(12) The electric compressor 32 is stopped without EGR.

Below, each combination of (1)-(12) is demonstrated in detail.
In (1), as shown in FIG. 9A, the valve B22, the valve C24, and the valve E28 are closed, and the valve A20 and the valve D26 are opened. Thus, the sucked air passes through the turbo compressor 33, passes through the bypass intake passage 50 that bypasses the electric compressor 32, and flows into the internal combustion engine 38. Further, the LPL-EGR mechanism 42 is operated to return the EGR gas from the LPL-EGR mechanism 42 to the intake air flow side of the turbo compressor 33.

  In (1), in order to suppress power consumption by the electric compressor 32, the electric compressor 32 is not used. Further, in order to increase the exhaust energy flowing into the turbine 35 and allow the turbocharger to obtain the supercharger work even when the flow rate is low and the load is low, the EGR uses the LPL-EGR mechanism 42 instead of the HPL-EGR mechanism 40. Operate. By setting EGR to LPL, the responsiveness can be improved and the supercharging pressure can be increased while keeping the rotational speed of the turbocharger high. In addition, there is an effect that warming-up is promoted and purification efficiency is improved by flowing a large amount of exhaust gas to an aftertreatment device such as a catalyst. Further, as shown in FIG. 9B, the operating point of the turbo compressor 33 moves to the higher flow rate side than the HPL, so that surge can be avoided and the turbo compressor 33 has high efficiency. The operating point moves to. When EGR is performed when the electric compressor 32 is not used as shown in FIG. 9A, it is determined that the operating point of the turbocharger 33 is on the smaller flow rate side than the extreme value of the efficiency even when refluxing with LPL. This form is used in some cases.

  In (2), as shown in FIG. 10A, the valve B22 and the valve C24 are closed, and the valve A20, the valve D26, and the valve E28 are opened. Thus, the sucked air passes through the turbo compressor 33, passes through the bypass intake passage 50 that bypasses the electric compressor 32, and flows into the internal combustion engine 38. Further, the LPL-EGR mechanism 42 is operated to return the EGR gas from the LPL-EGR mechanism 42 to the intake air flow side of the turbo compressor 33, and the HPL-EGR mechanism 40 is operated to operate the HPL-EGR mechanism 40. The EGR gas is recirculated to the intake downstream side of the electric compressor 32.

  In (2), in order to suppress power consumption by the electric compressor 32, the electric compressor 32 is not used. Further, the EGR rate and the ratio of HPL and LPL can be changed by adjusting the opening degree of each of the valve A20 and the valve E28. Further, when the operating point of the turbo compressor 33 is on the lower flow rate side than the extreme value of efficiency, as shown in FIG. 10B, in order to increase the LPL ratio, the opening degree of the valve A20 is increased. The opening degree of the valve E28 is reduced. On the other hand, when the operating point of the turbo compressor 33 is on the higher flow rate side than the extreme value of efficiency, the opening degree of the valve E28 is increased and the opening degree of the valve A20 is decreased in order to increase the HPL ratio. By changing the ratio between HPL and LPL, the operating point of the turbo compressor 33 is efficiently moved to the extreme value. As shown in FIG. 10A, when EGR is performed when the electric compressor 32 is not used, the operating point of the turbo compressor 33 becomes smaller than the extreme value of efficiency in HPL, and the turbo compressor in LPL. This form is used when 33 operating points are on the larger flow rate side than the extreme value of efficiency.

  In (3), as shown in FIG. 11A, the valve A20, the valve B22, and the valve C24 are closed, and the valve D26 and the valve E28 are opened. Thus, the sucked air passes through the turbo compressor 33, passes through the bypass intake passage 50 that bypasses the electric compressor 32, and flows into the internal combustion engine 38. Further, the HPL-EGR mechanism 40 is operated to return the EGR gas from the HPL-EGR mechanism 40 to the intake air downstream side of the electric compressor 32.

  In (3), in order to suppress power consumption by the electric compressor 32, the electric compressor 32 is not used. The EGR also activates the HPL-EGR mechanism 40 to reduce pump losses by reducing the flow to the turbine and reducing supercharger work. As shown in FIG. 11B, the operating point of the turbo compressor 33 moves to a lower flow rate side than the LPL, so that choke can be avoided and the operating point is in a region where the efficiency of the turbo compressor 33 is high. Move. When performing EGR when the electric compressor 32 is not used as shown in FIG. 111 (A), this form is used when it is determined that the operating point of the turbo compressor 33 is on the larger flow rate side than the extreme value of efficiency even in HPL. Is used.

  In (4), as shown in FIG. 12A, the valve B22, the valve D26, and the valve E28 are closed, and the valve A20 and the valve C24 are opened. Thus, the sucked air passes through the turbo compressor 33, passes through the electric compressor 32 from the serial intake passage 46, and flows into the internal combustion engine 38. Further, the LPL-EGR mechanism 42 is operated to return the EGR gas from the LPL-EGR mechanism 42 to the intake air flow side of the turbo compressor 33.

  In (4), if it is estimated that the turbocharger 34 is the only operating condition where the supercharging pressure is insufficient, the electric compressor 32 is started. When the electric compressor 32 is connected in parallel, the flow rate flowing into the turbo compressor 33 decreases, so that the surge region is entered. Therefore, the operating point of the turbo compressor 33 is moved to the high flow rate side by connecting the electric compressor 32 directly. At this time, the exhaust gas flowing into the turbine 35 is increased so that the turbocharger 34 can obtain the supercharger work even at a low flow rate. Also, the EGR is used to set the operating point of the turbo compressor 33 to the high flow rate side. Operates the LPL-EGR mechanism 42. The operating point of the turbo compressor 33 moves to the high flow rate side due to the effect of the serial connection of the LPL-EGR mechanism 42 and the electric compressor 32. As a result, surge can be avoided, and the operating point moves to a region where the efficiency of the turbo compressor 33 is higher than that of the HPL as shown in FIG. Also, the operating point is moved to a region where the efficiency of the turbo compressor 33 is higher than when the electric compressors 32 are connected in parallel. As shown in FIG. 12A, when EGR is performed when the electric compressor 32 is used, the operating point of the turbo compressor 33 is more than the extreme value of efficiency when the EGR is recirculated by LPL and the electric compressor 32 is connected in series. This form is used when it is determined that the flow rate is low.

  In (5), as shown in FIG. 13A, the valve B22 and the valve D26 are closed, and the valve A20, the valve C24, and the valve E28 are opened. Thus, the sucked air passes through the turbo compressor 33, passes through the electric compressor 32 from the serial intake passage 46, and flows into the internal combustion engine 38. Further, the LPL-EGR mechanism 42 is operated to recirculate EGR gas from the LPL-EGR mechanism 42 to the intake air flow side of the turbo compressor 33, and the HPL-EGR mechanism 40 is operated to operate the HPL-EGR mechanism 40. The EGR gas is recirculated to the intake downstream side of the electric compressor 32.

  In (5), when it is estimated that the operating condition is that the turbocharger 34 alone does not have sufficient supercharging pressure, the electric compressor 32 is started. By connecting the electric compressor 32 in series, the operating point of the turbo compressor 33 moves to the high flow rate side. Further, the EGR rate and the ratio of HPL and LPL can be changed by adjusting the opening degree of each of the valve A20 and the valve E28. Further, when the operating point of the turbo compressor 33 is on the lower flow rate side than the extreme value of efficiency, as shown in FIG. 13B, in order to increase the ratio of LPL, the opening degree of the valve A20 is increased. The opening degree of the valve E28 is reduced. On the other hand, when the operating point of the turbo compressor 33 is on the higher flow rate side than the extreme value of efficiency, the opening degree of the valve E28 is increased and the opening degree of the valve A20 is decreased in order to increase the HPL ratio. By changing the ratio between HPL and LPL, the operating point of the turbo compressor 33 is efficiently moved to the extreme value. As shown in FIG. 13A, when EGR is performed when the electric compressor 32 is used, the operating point of the turbo compressor 33 is more than the extreme value of efficiency when the EGR is recirculated by LPL and the electric compressor 32 is connected in series. This form is used when the operating point of the turbo compressor 33 is on the smaller flow rate side than the extreme value of efficiency when the EGR is recirculated with HPL and the electric compressor 32 is connected in series.

  In (6), as shown in FIG. 14A, the valve A20, the valve B22, and the valve D26 are closed, and the valve C24 and the valve E28 are opened. Thus, the sucked air passes through the turbo compressor 33, passes through the electric compressor 32 from the serial intake passage 46, and flows into the internal combustion engine 38. Further, the HPL-EGR mechanism 40 is operated to return the EGR gas from the HPL-EGR mechanism 40 to the intake air downstream side of the electric compressor 32.

  In (6), when it is estimated that the turbocharger 34 alone is in an operating condition in which supercharging is insufficient, the electric compressor 32 is started. By connecting the electric compressor 32 in series, the operating point of the turbo compressor 33 moves to the high flow rate side. Further, since the operating point of the turbo compressor 33 moves to the low flow rate side as compared with the LPL, the choke can be avoided and the operating point moves to a region where the efficiency of the turbo compressor 33 is high. As shown in FIG. 14A, when the EGR is performed when the electric compressor 32 is used, the operating point of the turbo compressor 33 is more than the extreme value of the efficiency when the EGR is refluxed by HPL and the electric compressor 32 is connected in series. This form is used when it is determined that the efficiency is higher as shown in FIG. 14B compared to the operating point when the EGR is recirculated with LPL and the electric compressor 32 is connected in parallel. Use.

  In (7), as shown in FIG. 15A, the valve C24 and the valve E28 are closed, and the valve A20, the valve B22, and the valve D26 are opened. As a result, the LPL-EGR mechanism 42 operates to recirculate the EGR gas from the LPL-EGR mechanism 42 to the intake air amount flow side of the turbo compressor 33 and to the parallel intake path 48. The sucked air is combined with the air that has passed through the turbo compressor 33 and the EGR gas that has been returned to the parallel intake passage 48 from the LPL-EGR mechanism 42 and passed through the electric compressor 32 to the internal combustion engine 38. Inflow.

  In (7), if it is estimated that the turbocharger 34 is in an operating condition that the supercharging pressure is insufficient, the electric compressor 32 is started. The electric compressor 32 shares a part of the exhaust gas recirculation by connecting the electric compressor 32 in parallel. As a result, the operating point of the turbo compressor 33 moves to the low flow rate side. Further, by setting EGR to LPL, the supercharger work that can increase the flow rate to the turbine 35 as compared to HPL increases, and the flow rate to the turbo compressor 33 increases. As shown in FIG. 15A, when EGR is performed when the electric compressor 32 is used, the operating point of the turbo compressor 33 is more than the extreme value of efficiency when the EGR is recirculated by LPL and the electric compressor 32 is connected in parallel. This form is used when the efficiency is determined to be higher as shown in FIG. 15B compared to the operating point when the EGR is recirculated with HPL and the electric compressor 32 is connected in series when the EGR is recirculated with HPL. Use.

  In (8), as shown in FIG. 16A, the valve C24 is closed and the valve A20, the valve B22, the valve D26, and the valve E28 are opened. As a result, the LPL-EGR mechanism 42 operates to recirculate the EGR gas from the LPL-EGR mechanism 42 to the intake air amount flow side of the turbo compressor 33 and to the parallel intake path 48. Further, the HPL-EGR mechanism 40 is operated to return the EGR gas from the HPL-EGR mechanism 40 to the intake air downstream side of the electric compressor 32. The sucked air is combined with the air that has passed through the turbo compressor 33 and the EGR gas that has been returned to the parallel intake passage 48 from the LPL-EGR mechanism 42 and passed through the electric compressor 32 to the internal combustion engine 38. Inflow.

  In (8), when it is estimated that the turbocharger 34 is in an operating condition that the supercharging pressure is insufficient, the electric compressor 32 is started. The electric compressor 32 shares a part of the exhaust gas recirculation by connecting the electric compressor 32 in parallel. As a result, the operating point of the turbo compressor 33 moves to the low flow rate side. Further, the EGR rate and the ratio of HPL and LPL can be changed by adjusting the opening degree of each of the valve A20 and the valve E28. Further, when the operating point of the turbo compressor 33 is on the lower flow rate side than the extreme value of efficiency, as shown in FIG. 16B, in order to increase the ratio of LPL, the opening degree of the valve A20 is increased. The opening degree of the valve E28 is reduced. On the other hand, when the operating point of the turbo compressor 33 is on the higher flow rate side than the extreme value of efficiency, the opening degree of the valve E28 is increased and the opening degree of the valve A20 is decreased in order to increase the HPL ratio. By changing the ratio between HPL and LPL, the operating point of the turbo compressor 33 is efficiently moved to the extreme value. As shown in FIG. 16A, when the EGR is performed when the electric compressor 32 is used, the operating point of the turbo compressor 33 is more than the extreme value of the efficiency when the EGR is refluxed by LPL and the electric compressor 32 is connected in parallel. This mode is used when the operating point of the turbo compressor 33 becomes smaller than the extreme value of the efficiency when the EGR is recirculated by HPL and the electric compressor 32 is connected in parallel when the EGR is returned to the high flow rate side.

 In (9), as shown in FIG. 17A, the valve A20 and the valve C24 are closed, and the valve B22, the valve D26, and the valve E28 are opened. As a result, the sucked air is separated in front of the turbo compressor 33, and the air that has passed through the turbo compressor 33 and the air that has passed through the electric compressor 32 from the parallel intake path 48 are merged to form the internal combustion engine 38. Flow into. Further, the HPL-EGR mechanism 40 is operated to return the EGR gas from the HPL-EGR mechanism 40 to the intake air downstream side of the electric compressor 32.

  In (9), when it is estimated that the turbocharger 34 is in an operating condition that the supercharging pressure is insufficient, the electric compressor 32 is started. By connecting the electric compressor 32 in parallel, the electric compressor 32 shares part of the intake air. As a result, the operating point of the turbo compressor 33 moves to the low flow rate side. By setting EGR to HPL, the flow rate to the turbine 35 is reduced more than LPL, and the pump loss is reduced. Further, since the flow rate to the turbo compressor 33 is reduced, choking can be avoided. As shown in FIG. 17A, when EGR is performed when the electric compressor 32 is used, the operating point of the turbo compressor 33 is shown in FIG. This form is used when it is determined that the flow rate is larger than the extreme value of efficiency as in B).

  In (10), as shown in FIG. 18A, the valve A20, the valve B22, the valve D26, and the valve E28 are closed, and the valve C24 is opened. Thus, the sucked air passes through the turbo compressor 33, passes through the electric compressor 32 from the serial intake passage 46, and flows into the internal combustion engine 38.

  In (10), as shown in FIG. 18B, the operating point of the turbo compressor 33 moves to the larger flow rate side than when the electric compressor 32 is connected in parallel without EGR. The series connection of the electric compressor 32 is applied without EGR in the case of operating conditions where priority is given to supercharging without using EGR, such as during acceleration or full load, and operating conditions where the intake air has a low flow rate.

  In (11), as shown in FIG. 19A, the valve A20, the valve C24, and the valve E28 are closed, and the valve B22 and the valve D26 are opened. As a result, the sucked air is separated in front of the turbo compressor 33, and the air that has passed through the turbo compressor 33 and the air that has passed through the electric compressor 32 from the parallel intake path 48 are merged to form the internal combustion engine 38. Flow into.

  In (11), as shown in FIG. 19B, the operating point of the turbo compressor 33 moves to a lower flow rate side than when the electric compressor 32 is connected in series without EGR. The parallel connection of the electric compressor 32 is applied without EGR under the operating condition where priority is given to supercharging without using EGR, such as during acceleration or full load, and the operating condition where the intake air has a large flow rate.

  In (12), as shown in FIG. 20A, the valve A20, the valve B22, the valve C24, and the valve E28 are closed and the valve D26 is opened. Thus, the sucked air flows into the internal combustion engine 38 through the turbo compressor 33.

  In (12), it is estimated that the turbocharging pressure is sufficient only with the turbocharger 34, and the electric compressor 32 is not used in order to suppress the power consumption by the electric compressor 32. The operating point of the turbo compressor 33 is a range in which the turbo compressor 33 operates stably as shown in FIG.

  FIG. 21A shows the presence / absence of operation of the electric compressor 32 in each of the above (1) to (12), connection of the electric compressor 32 (bypass, parallel or series), and the EGR method. FIG. 21B shows the open / close state of each valve in each of the above-described (1) to (12). In the present embodiment, FIGS. 21A and 21B are stored in advance in the EGR control device 10 as a map, and control for switching to each state is performed.

  Next, specific processing performed by the control unit 12 of the EGR control device 10 according to the present embodiment configured as described above will be described. FIG. 22 is a flowchart illustrating an example of a flow of processing performed by the control unit 12 of the EGR control device 10 according to the present embodiment.

  In step 100, the CPU 12A determines whether or not it is an EGR area. The determination is made based on, for example, the detection results of the throttle sensor 14, the crank angle sensor 16, and the airflow sensor 18, and whether or not the load, the rotational speed, the intake flow rate, and the like of the internal combustion engine are in a predetermined EGR region. Determine whether. If the determination is negative, the process proceeds to step 102, and if the determination is affirmative, the process proceeds to step 106.

  In step 102, the CPU 12A determines whether or not the operation of the electric compressor 32 is necessary. In this determination, for example, it is determined whether it is necessary to operate the electric compressor 32 based on the detection results of the throttle sensor 14, the crank angle sensor 16, and the airflow sensor 18. If the determination is affirmative, the routine proceeds to step 104. On the other hand, when the result is negative, the operation of each valve and the electric compressor motor 30 is controlled so as to satisfy (12) described above. That is, the valve A20, the valve B22, the valve C24, and the valve E28 are closed, the valve D26 is opened, and the electric compressor motor 30 is stopped.

  In step 104, the CPU 12A determines whether or not the operating point of the turbo compressor 33 when the electric compressor 32 is connected in series is on the higher flow rate side than the extreme value of efficiency. When the determination is negative, the operation of each valve and the electric compressor motor 30 is controlled so as to satisfy (10) described above. That is, the valve A20, the valve B22, the valve D26, and the valve E28 are closed, the valve C24 is opened, and the electric compressor motor 30 is operated. On the other hand, when the determination is affirmative, the operation of each valve and the electric compressor motor 30 is controlled so as to satisfy (11) described above. That is, the valve A20, the valve C24, and the valve E28 are closed, the valve B22 and the valve D26 are opened, and the electric compressor motor 30 is operated.

  In step 106, the CPU 12A determines whether or not the operation of the electric compressor 32 is necessary. In this determination, for example, it is determined whether it is necessary to operate the electric compressor 32 based on the detection results of the throttle sensor 14, the crank angle sensor 16, and the airflow sensor 18. If the determination is negative, the process proceeds to step 108, and if the determination is affirmative, the process proceeds to step 112.

  In step 108, the CPU 12A determines whether or not the operating point of the turbo compressor 34 when the electric compressor 32 is bypassed and LPL is on the higher flow rate side than the extreme value of efficiency. If the determination is affirmative, the process proceeds to step 110. If the determination is negative, the valves and the electric compressor motor 30 are controlled so as to satisfy the above-described (1). That is, control is performed such that the valve B22, the valve C24, and the valve E28 are closed, the valve A20 and the valve D26 are opened, and the electric compressor motor 30 is stopped.

  In step 110, the CPU 12A determines whether or not the operating point of the turbo compressor 34 when the electric compressor 32 is bypassed and HPL is on the lower flow rate side than the extreme value of efficiency. When the determination is negative, each valve and the electric compressor motor 30 are controlled so as to satisfy the above (3). That is, the valve B22 and the valve C24 are closed, the valve A20, the valve D26, and the valve E28 are opened, and the electric compressor motor 30 is controlled to stop. On the other hand, when the determination is affirmative, each valve and the electric compressor motor 30 are controlled so as to satisfy the above (2). That is, the valve B22 and the valve C24 are closed, the valve A20, the valve D26, and the valve E28 are opened, and the electric compressor motor 30 is controlled to stop.

  In step 112, (a) when the electric compressor 32 is connected in series and LPL, (b) when the electric compressor 32 is connected in series and HPL, (c) when the electric compressor 32 is connected in parallel and LPL, (d) electric The operating point of the turbo compressor 33 is calculated for each of the cases where the compressor 32 is connected in parallel and HPL, and the routine proceeds to step 114.

  In step 114, the CPU 12A determines whether or not the operating point (a) is on the higher flow rate side than the extreme value of efficiency. When the determination is affirmative, the routine proceeds to step 116, and when the determination is negative, each valve and the electric compressor motor 30 are controlled so as to satisfy the above-mentioned (4). That is, the valve B22, the valve D26, and the valve E28 are closed, the valve A20 and the valve C24 are opened, and the electric compressor motor 30 is operated.

  In step 116, the CPU 12A determines whether or not the operating point (b) is on the lower flow rate side than the extreme value of efficiency. If the determination is affirmative, the process proceeds to step 124, and if the determination is negative, the process proceeds to step 118.

  In step 118, the CPU 12A determines whether or not the operating point (c) is on the higher flow rate side than the extreme value of efficiency. If the determination is negative, the process proceeds to step 120. If the determination is affirmative, the process proceeds to step 122.

  In step 120, the CPU 12A determines whether or not the efficiency of the operating point (b)> the efficiency of the operating point (c). When the determination is affirmative, each valve and the electric compressor motor 30 are controlled so as to satisfy the above (6). That is, the valve A20, the valve B22, and the valve D26 are closed, the valve C24 and the valve E28 are opened, and the electric compressor motor 30 is operated. On the other hand, if the determination is negative, each valve and the electric compressor motor 30 are controlled so as to satisfy the above (7). That is, the valve C24 and the valve E28 are closed, the valve A20, the valve B22, and the valve D26 are opened, and the electric compressor motor 30 is controlled to operate.

  In step 122, the CPU 12A determines whether or not the operating point (d) is on the higher flow rate side than the extreme value of efficiency. When the determination is negative, each valve and the electric compressor motor 30 are controlled so as to satisfy the above (8). That is, the valve C24 is closed, the valve A20, the valve B22, the valve D26, and the valve E28 are opened, and the electric compressor motor 30 is controlled to operate. On the other hand, when the determination is affirmative, each valve and the electric compressor motor 30 are controlled so as to satisfy (9) described above. That is, the valve A20 and the valve C24 are closed, the valve B22, the valve D26, and the valve E28 are opened, and the electric compressor motor 30 is controlled to operate.

  In step 124, the CPU 12 </ b> A calculates the HPL / LPL ratio and the operating point (e) that are the extreme values of efficiency from the operating points (a) and (b), and proceeds to step 126.

  In step 126, the CPU 12A determines whether or not the operating point (c) is on the higher flow rate side than the extreme value of efficiency. If the determination is affirmative, the process proceeds to step 128. If the determination is negative, each valve and the electric compressor motor 30 are controlled so as to satisfy (5) described above. That is, the valve B22 and the valve D26 are closed, the valve A20, the valve C24, and the valve E28 are opened, and the electric compressor motor 30 is controlled to operate.

  In step 128, the CPU 12 </ b> A calculates the HPL / LPL ratio and the operating point (f) that are the extreme values of efficiency from the operating points (c) and (d), and proceeds to step 130.

  In step 130, the CPU 12A determines whether or not the efficiency of the operating point (e)> the efficiency of the operating point (f). If the determination is affirmative, each valve and the electric compressor motor 30 are controlled so as to satisfy the above (5). That is, the valve B22 and the valve D26 are closed, the valve A20, the valve C24, and the valve E28 are opened, and the electric compressor motor 30 is controlled to operate. On the other hand, when the determination is negative, the valves and the electric compressor motor 30 are controlled so as to satisfy the above (8). That is, the valve C24 is closed, the valve A20, the valve B22, the valve D26, and the valve E28 are opened, and the electric compressor motor 30 is controlled to operate.

  In this way, the control unit 12 performs control, so that the combination of the arrangement of the electric compressor 32 and the EGR method that has the highest efficiency can be selected. Moreover, the supercharger efficiency of the turbocharger 34 can be improved, and the thermal efficiency of the internal combustion engine 38 is improved by reducing the pump loss. Further, since the turbo compressor 33 can perform supercharging by switching the electric compressor 32 even in an operation region where a surge or choke occurs, the operable region of the internal combustion engine 38 is expanded. Further, EGR can be performed over a wide range, and low emission can be achieved. In particular, EGR at high load and medium speed transition is possible with a high supercharging rate, and low emission can be realized.

  In each of the above-described embodiments, the example in which the electric compressor 32 is applied as an example of a compressor that can switch between compression and non-compression of intake air has been described. However, the present invention is not limited to this. For example, a so-called supercharger that mechanically drives the compressor 31 by switching presence or absence of transmission of the driving force of the internal combustion engine by an electromagnetic clutch or the like may be applied as the compressor.

  Moreover, although the process of FIG. 22 performed by the control part 12 in said embodiment was demonstrated as a software process performed when a computer runs a program, it is good also as a process performed by hardware. Alternatively, the processing may be a combination of both software and hardware. Further, a program for processing performed by software may be stored in various storage media and distributed.

  In the above embodiment, the program for performing the processing of FIG. 22 has been described as being stored in the ROM 12B in advance. However, the present invention is not limited to this. For example, the program may be provided in a form recorded on a recording medium such as a CD-ROM (Compact Disk Read Only Memory), a DVD-ROM (Digital Versatile Disk Read Only Memory), and a USB (Universal Serial Bus) memory. Good. Further, the program may be downloaded from an external device via a network.

  Furthermore, the present invention is not limited to the above, and it goes without saying that various modifications can be made without departing from the spirit of the present invention.

10 EGR control device 12 Control unit 20 Valve A
22 Valve B
24 Valve C
26 Valve D
28 Valve E
DESCRIPTION OF SYMBOLS 30 Electric compressor motor 32 Electric compressor 34 Turbo supercharger 38 Internal combustion engine 40 HPL-EGR mechanism 42 LPL-EGR mechanism 46 Series intake path 48 Parallel intake path 50 Bypass intake path

Claims (15)

A serial path for connecting in series a compressor capable of switching between compression and non-compression of intake air to a turbocharger that compresses intake air using exhaust pressure, and the turbocharger A path switching unit that switches the intake path of the internal combustion engine to a parallel path that connects the compressors in parallel or a bypass path that bypasses the compressor;
The EGR gas is recirculated by the first exhaust recirculation unit that recirculates the EGR gas taken out from the exhaust route to the intake passage downstream of the turbocharger, and from the exhaust route downstream of the first exhaust recirculation unit. Recirculation of EGR gas by the second exhaust gas recirculation unit that recirculates the extracted EGR gas to the intake path upstream of the turbocharger, and each of the first exhaust gas recirculation unit and the second exhaust gas recirculation unit EGR gas recirculation by EGR, or EGR switching unit for switching without EGR gas recirculation
A control unit for controlling each of the compressor, the path switching unit, and the EGR switching unit based on a predetermined operating condition of the internal combustion engine;
An EGR control device comprising:   2. The EGR control device according to claim 1, wherein the series path connects the compressor in series to the turbocharger on an intake downstream side of the turbocharger.   The control unit is configured to perform the turbocharging when a predetermined operating condition for recirculating EGR gas, an operating condition that does not require compression of intake air by the compressor, and a recirculation of EGR gas by the second exhaust recirculation unit. In an operating condition where the operating point of the machine does not reach a flow rate higher than the extreme value of efficiency, the intake path is switched to the bypass path while the compressor is in an uncompressed state, and EGR gas is The EGR control device according to claim 1 or 2, wherein each of the compressor, the path switching unit, and the EGR switching unit is controlled so as to recirculate.   The control unit includes a predetermined operating condition for recirculating EGR gas, an operating condition for which compression of intake air by the compressor is unnecessary, and the turbocharger when the EGR gas is recirculated by the second exhaust recirculation unit When the operating point is an operating condition where the flow rate is higher than the extreme value of efficiency, and the operating point when the EGR gas is recirculated by the first exhaust gas recirculation unit is lower than the extreme value of efficiency. Further, the compression is performed so that the intake passage is switched to the bypass passage while the compressor is in an uncompressed state, and the EGR gas is recirculated by each of the first exhaust recirculation unit and the second exhaust recirculation unit. The EGR control device according to any one of claims 1 to 3, which controls each of the machine, the path switching unit, and the EGR switching unit.   The control unit includes a predetermined operating condition for recirculating EGR gas, an operating condition for which compression of intake air by the compressor is unnecessary, and the turbocharger when the EGR gas is recirculated by the second exhaust recirculation unit When the operating point is an operating condition in which the flow rate is higher than the extreme value of efficiency and the operating point when the EGR gas is recirculated by the first exhaust gas recirculation unit is not lower than the extreme value of efficiency. Further, the compressor, the path switching unit, and the EGR are switched so that the intake path is switched to the bypass path while the compressor is in an uncompressed state, and the EGR gas is recirculated by the first exhaust gas recirculation unit. The EGR control device according to claim 1, wherein each of the switching units is controlled.   The controller is configured to switch the intake path to a serial path in a state where a predetermined operating condition for recirculating EGR gas, an operating condition where the compressor needs to compress intake air, and the compressor is in a compressed state. (2) When the operating point of the turbocharger when the EGR gas is recirculated by the exhaust gas recirculation unit does not reach a higher flow rate than the extreme value of efficiency, the compressor is in a compressed state and the intake path is 6. The controller according to claim 1, wherein the compressor, the path switching unit, and the EGR switching unit are controlled to switch to the series path and recirculate EGR gas by the second exhaust gas recirculation unit. 2. The EGR control device according to item 1.   The control unit is configured to switch the intake path to a serial path in a state where a predetermined operating condition for recirculating EGR gas, an operating condition that requires compression of the intake air by the compressor, and the compressor is in a compressed state. An operating condition in which the operating point of the turbocharger when the EGR gas is recirculated by the exhaust gas recirculation unit is higher than the extreme value of efficiency, and the compressor is in a compressed state, the intake path is changed to the series path. When the EGR gas is recirculated by the first exhaust gas recirculation unit after switching, the operating condition of the turbocharger becomes a lower flow rate side than the extreme value of efficiency, and the intake air while the compressor is in a compressed state When the operating condition of the turbocharger when the path is switched to the parallel path and the EGR gas is recirculated by the second exhaust recirculation unit does not reach the higher flow rate side than the extreme value of efficiency, or EGR Gas A predetermined operating condition for flowing, an operating condition that requires compression of the intake air by the compressor, and switching the intake path to a serial path when the compressor is in compression, and EGR gas is generated by the second exhaust recirculation unit. The operating condition in which the operating point of the turbocharger when recirculated is higher than the extreme value of the efficiency, and the compressor is in a compressed state, the intake path is switched to the series path and the first exhaust gas recirculation is performed. Operating conditions in which the operating point of the turbocharger when the EGR gas is recirculated by the unit is on the lower flow rate side than the extreme value of efficiency, and the compressor is in a compressed state, the intake path is switched to the parallel path and the The operating conditions of the turbocharger when the EGR gas is recirculated by the second exhaust recirculation unit are operating conditions in which the operating point of the turbocharger is higher than the extreme value of efficiency, and the compressor is in a compressed state, and the intake passage is connected in series. Switch to route The operating point of the turbocharger when the EGR gas is recirculated by the second exhaust gas recirculation unit, and the first exhaust gas recirculation unit by switching the intake path to the serial path when the compressor is compressed. The efficiency of the operating point calculated from the operating point of the turbocharger when the EGR gas is recirculated by switching the intake path to the parallel path while the compressor is in compression is the second exhaust. The operating point of the turbocharger when the EGR gas is recirculated by the recirculation unit, and the intake path is switched to the parallel path while the compressor is compressed, and the EGR gas is generated by the first exhaust recirculation unit. When the operating condition is higher than the efficiency of the operating point calculated from the operating point of the turbocharger when recirculating, the compressor switches the intake path to the series path in a compressed state, and the first Exhaust gas recirculation The compressor, the path switching unit, and the EGR switching unit are each controlled to recirculate EGR gas by each of the first and second exhaust gas recirculation units. The EGR control device described.   The control unit is configured to switch the intake path to a serial path in a state where a predetermined operating condition for recirculating EGR gas, an operating condition that requires compression of the intake air by the compressor, and the compressor is in a compressed state. An operating condition in which the operating point of the turbocharger when the EGR gas is recirculated by the exhaust gas recirculation unit is higher than the extreme value of efficiency, and the compressor is in a compressed state, the intake path is changed to the series path. When the EGR gas is recirculated by the first exhaust gas recirculation unit, the operating point of the turbocharger does not become a lower flow rate side than the extreme value of efficiency, and the intake path is in a state where the compressor is compressed When the EGR gas is recirculated by the second exhaust gas recirculation unit and the operating point of the turbocharger does not reach the higher flow rate than the extreme value of efficiency, and the compressor is compressed In the state of More than the operating point of the turbocharger when the intake path is switched to the parallel path and the EGR gas is recirculated by the second exhaust recirculation unit, the intake path is connected in series with the compressor in a compressed state. When the operating point of the turbocharger when the EGR gas is recirculated by the first exhaust gas recirculation unit by switching to a path is an operating condition with higher efficiency, the compressor is in the compressed state and the intake path Any one of Claims 1-7 which control each of the said compressor, the said path switching part, and the said EGR switching part so that EGR gas may be recirculated by the said 1st exhaust gas recirculation part by switching to a serial path | route. The EGR control device according to claim 1.   The control unit is configured to switch the intake path to a serial path in a state where a predetermined operating condition for recirculating EGR gas, an operating condition that requires compression of the intake air by the compressor, and the compressor is in a compressed state. An operating condition in which the operating point of the turbocharger when the EGR gas is recirculated by the exhaust gas recirculation unit is higher than the extreme value of efficiency, and the compressor is in a compressed state, the intake path is changed to the series path. When the EGR gas is recirculated by the first exhaust gas recirculation unit, the operating point of the turbocharger does not become a lower flow rate side than the extreme value of efficiency, and the intake path is in a state where the compressor is compressed When the EGR gas is recirculated by the second exhaust gas recirculation unit and the operating point of the turbocharger does not reach the higher flow rate than the extreme value of efficiency, and the compressor is compressed In the state of More than the operating point of the turbocharger when the intake path is switched to the serial path and the EGR gas is recirculated by the first exhaust recirculation unit, the intake path is arranged in parallel with the compressor being compressed. When the operating point of the turbocharger when the EGR gas is recirculated by the second exhaust gas recirculation unit by switching to a path is an operating condition with higher efficiency, the compressor is in a compressed state and the intake path Any one of Claims 1-8 which control each of the said compressor, the said path | route switching part, and the said EGR switching part so that EGR gas may be recirculated by the said 2nd exhaust gas recirculation part. The EGR control device according to claim 1.   The control unit is configured to switch the intake path to a serial path in a state where a predetermined operating condition for recirculating EGR gas, an operating condition that requires compression of the intake air by the compressor, and the compressor is in a compressed state. An operating condition in which the operating point of the turbocharger when the EGR gas is recirculated by the exhaust gas recirculation unit is higher than the extreme value of efficiency, and the compressor is in a compressed state, the intake path is changed to the series path. When the EGR gas is recirculated by the first exhaust gas recirculation unit, the operating point of the turbocharger does not become a lower flow rate side than the extreme value of efficiency, and the intake path is in a state where the compressor is compressed When the EGR gas is recirculated by the second exhaust gas recirculation unit and the operating point of the turbocharger is higher than the extreme value of efficiency, and the compressor is compressed. In the state When the operating condition of the turbocharger when the path is switched to the parallel path and the EGR gas is recirculated by the first exhaust recirculation unit is not at a higher flow rate than the extreme value of efficiency, or EGR A predetermined operating condition for recirculating gas, an operating condition that requires compression of the intake air by the compressor, and switching the intake path to a serial path while the compressor is compressed, and the second exhaust gas recirculation unit performs EGR. The operating condition in which the operating point of the turbocharger when the gas is recirculated is higher than the extreme value of efficiency, and the compressor is in a compressed state, the intake path is switched to the series path, and the first exhaust When the EGR gas is recirculated by the recirculation unit, the operating condition of the turbocharger becomes a lower flow rate side than the extreme value of efficiency, and the intake path is switched to the parallel path when the compressor is in a compressed state. The operating condition of the turbocharger when the EGR gas is recirculated by the second exhaust gas recirculation unit is set to a higher flow rate side than the extreme value of efficiency, and the compressor is in a compressed state to pass the intake path The operation point of the turbocharger when the EGR gas is recirculated by the second exhaust gas recirculation unit by switching to the serial path, and the intake path is switched to the serial path while the compressor is compressed. The efficiency of the operating point calculated from the operating point of the turbocharger when the EGR gas is recirculated by one exhaust gas recirculation unit switches the intake path to the parallel path when the compressor is in compression. The operating point of the turbocharger when EGR gas is recirculated by the second exhaust gas recirculation unit, and the first exhaust gas recirculation by switching the intake path to the parallel path when the compressor is compressed Depending on the part EGR When the operating condition is not higher than the efficiency of the operating point calculated from the operating point of the turbocharger when the gas is recirculated, the compressor switches the intake path to the parallel path in a compressed state, 10. The compressor, the path switching unit, and the EGR switching unit are each controlled so that EGR gas is recirculated by the first exhaust gas recirculation unit and the second exhaust gas recirculation unit. The EGR control device according to any one of the above.   The control unit is configured to switch the intake path to a serial path in a state where a predetermined operating condition for recirculating EGR gas, an operating condition that requires compression of the intake air by the compressor, and the compressor is in a compressed state. An operating condition in which the operating point of the turbocharger when the EGR gas is recirculated by the exhaust gas recirculation unit is higher than the extreme value of efficiency, and the compressor is in a compressed state, the intake path is changed to the series path. When the EGR gas is recirculated by the first exhaust gas recirculation unit, the operating point of the turbocharger does not become a lower flow rate side than the extreme value of efficiency, and the intake path is in a state where the compressor is compressed When the EGR gas is recirculated by the second exhaust gas recirculation unit and the operating point of the turbocharger is higher than the extreme value of efficiency, and the compressor is compressed. In the state If the operating point of the turbocharger when the EGR gas is recirculated by the first exhaust gas recirculation unit by switching the path to the parallel path is an operating condition where the operating point is higher than the extreme value of efficiency, the compression Each of the compressor, the path switching unit, and the EGR switching unit is configured to switch the intake path to the parallel path in a compressed state and to recirculate EGR gas by the first exhaust recirculation unit. The EGR control device according to any one of claims 1 to 10, which is controlled.   When the control unit switches the intake path to the series path in a predetermined operating condition that does not recirculate EGR gas, an operating condition that requires compression of the intake air by the compressor, and the compressor is in a compressed state When the operating point of the turbocharger is such that the operating point is not higher than the extreme value of efficiency, the intake path is switched to the series path while the compressor is in a compressed state, and there is no recirculation of EGR gas. The EGR control device according to any one of claims 1 to 11, wherein each of the compressor, the path switching unit, and the EGR switching unit is controlled so as to become.   When the control unit switches the intake path to the series path in a predetermined operating condition that does not recirculate EGR gas, an operating condition that requires compression of the intake air by the compressor, and the compressor is in a compressed state In the operating condition where the operating point of the turbocharger is higher than the extreme value of the efficiency, the intake path is switched to the parallel path while the compressor is in a compressed state, and there is no recirculation of EGR gas. The EGR control device according to any one of claims 1 to 12, wherein each of the compressor, the path switching unit, and the EGR switching unit is controlled so as to become.   The control unit is configured to bypass the intake path when the compressor is in an uncompressed state under a predetermined operating condition in which EGR gas is not recirculated and an operating condition in which the compressor does not need to compress intake air. The EGR control device according to any one of claims 1 to 13, wherein each of the compressor, the path switching unit, and the EGR switching unit is controlled so that the EGR gas is not recirculated.   The EGR control program for functioning a computer as a control part in the EGR control apparatus of any one of Claims 1-14.