JP2014141934A - Internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To actuate an optimum turbosupercharger with high efficiency when actuating a fuel cell during the stop of an engine body.SOLUTION: An internal combustion engine 1 includes high- and low-pressure stage turbosuperchargers 3H, 3L, a fuel cell 4, an air supply path 25A branching from an intake passage 5 on the downstream side of a high-pressure stage compressor 3HC to supply air to the fuel cell 4, an exhaust path 27A connected to an exhaust passage 6 on the upstream side of a high-pressure stage turbine 3HT to exhaust exhaust gas from the fuel cell 4, a low-pressure stage compressor bypass passage 37 bypassing a low-pressure stage compressor 3LC, and a low-pressure stage compressor bypass valve 38 changeable over to guide intake air to at least one of the low-pressure stage compressor 3LC and the low-pressure stage compressor bypass passage 37. When actuating the fuel cell 4 during the stop of an engine body 2, a control unit 100 changes over the low-pressure stage compressor bypass valve 38 to guide the intake air to the low-pressure stage compressor bypass passage 37.

Description

  The present invention relates to an internal combustion engine, and more particularly, to an internal combustion engine including a multistage turbocharging system and a fuel cell.

  Internal combustion engines with a multi-stage turbocharging system are known. In particular, as a multistage turbocharger system, a two-stage sequential turbosystem in which two turbochargers, a low-pressure turbocharger and a high-pressure turbocharger, are connected in series is known. For example, Patent Literature 1 discloses a turbocharged engine having a large turbocharger and a small turbocharger. In a large turbocharger, a clutch is provided on a connecting shaft that connects a compressor and a turbine, and an electric motor for assisting the rotation of the compressor is provided on a connecting shaft closer to the compressor than the clutch.

JP 2011-58400 A

  On the other hand, it is conceivable to combine a fuel cell with an internal combustion engine equipped with a multistage turbocharging system. In this case, it is advantageous that the air discharged from the compressor of the turbocharger is sent to the fuel cell, and the exhaust gas from the fuel cell is supplied to the turbine of the turbocharger. In this way, it is not necessary to provide a separate air source such as a motor compressor for supplying air to the fuel cell, and at the same time, the exhaust gas from the fuel cell can be used effectively for driving the turbine, and the efficiency and turbo response can be improved. is there.

  In such a configuration, the following problems exist. When the internal combustion engine (specifically, the engine body) is in a stopped state, power generation by the fuel cell is required, and the fuel cell may have to be operated. In order to operate the fuel cell, it is necessary to send necessary air to the fuel cell and exhaust the exhaust gas from the fuel cell. For this reason, at least one of the low-pressure stage turbocharger and the high-pressure stage turbocharger must be operated while the engine body is stopped.

  However, as to which of these is to be operated, it is necessary to fully consider the characteristics of the individual turbochargers and the characteristics of the fuel cell. In addition, it is necessary to devise so as to maximize the efficiency during the operation.

  In order to operate at least one of the low-pressure stage turbocharger and the high-pressure stage turbocharger, it is conceivable to stop the engine body or restart the engine body. However, this inevitably consumes fuel, and the fuel efficiency deteriorates. Further, if the restart is automatically performed, the engine is unexpectedly started for the user, which causes a sense of incongruity.

  Accordingly, the present invention has been made in view of the above circumstances, and one object of the present invention is to operate a fuel cell while the engine body is stopped in an internal combustion engine having a multistage turbocharger system and a fuel cell. At the same time, it is an object of the present invention to provide an internal combustion engine capable of operating an optimum turbocharger with high efficiency.

According to one aspect of the invention,
An intake passage and an exhaust passage connected to the engine body,
A high-pressure stage turbocharger having a high-pressure stage turbine provided upstream of the exhaust passage and a high-pressure stage compressor provided downstream of the intake passage;
A low-pressure stage turbocharger having a low-pressure stage turbine provided downstream of the exhaust passage and a low-pressure stage compressor provided upstream of the intake passage;
A fuel cell;
An air supply path branched from the intake passage downstream of the high-pressure stage compressor and connected to the fuel cell to supply air to the fuel cell;
An exhaust passage extending from the fuel cell and connected to the exhaust passage upstream of the high-pressure turbine to exhaust the fuel cell exhaust;
A low-pressure compressor bypass passage that branches from the intake passage upstream of the low-pressure compressor and joins the intake passage between the low-pressure compressor and the high-pressure compressor to bypass the low-pressure compressor;
A low pressure stage compressor bypass valve that is switchable to direct intake air upstream of the low pressure stage compressor to at least one of the low pressure stage compressor and the low pressure stage compressor bypass passage;
A control unit for controlling the engine body and the low-pressure compressor bypass valve;
With
The control unit switches the low-pressure stage compressor bypass valve to guide the intake air upstream of the low-pressure stage compressor to the low-pressure stage compressor bypass passage when the fuel cell is operated while the engine body is stopped. An internal combustion engine is provided.

  According to this aspect of the present invention, when the fuel cell is operated while the engine body is stopped, the exhaust of the fuel cell is supplied to the exhaust passage on the upstream side of the high-pressure turbine through the exhaust passage. The high-pressure turbine is driven to rotate. At the same time, the high-pressure compressor is rotated, and the air discharged from the high-pressure compressor is supplied to the fuel cell through the air supply path. This allows the fuel cell to operate.

  In order to send the amount of air necessary for the operation of the fuel cell while the engine body is stopped, the high pressure turbocharger is more suitable in size than the low pressure turbocharger. Therefore, by operating the high-pressure turbocharger, it is possible to increase the turbo efficiency and increase the efficiency of the entire system.

  In addition, since the low-pressure stage compressor bypass valve is switched so as to guide the intake air upstream of the low-pressure stage compressor to the low-pressure stage compressor bypass passage, the intake air does not pass through the low-pressure stage compressor bypass passage and passes through the low-pressure stage compressor bypass passage. Will be supplied to. As a result, the flow path resistance is reduced, and the loss caused by the intake air driving the low-pressure compressor is reduced, and the intake air can be efficiently supplied to the high-pressure compressor. As a result, it is possible to increase the turbo efficiency and thus the efficiency of the entire system.

  Thus, according to one aspect of the present invention, when operating the fuel cell while the engine body is stopped, it is possible to operate the optimum turbocharger with high efficiency.

  Here, the “turbine” strictly means a turbine wheel housed in the turbine housing of the turbine. Therefore, in the case of “an exhaust passage upstream of the turbine”, this includes a passage portion in the turbine housing located upstream or inlet of the turbine wheel. The same applies to the “exhaust passage on the downstream side of the turbine”.

  Similarly, “compressor” refers strictly to a compressor wheel housed within the compressor housing of the compressor. Therefore, in the case of “an intake passage on the downstream side of the compressor”, this includes a passage portion in the compressor housing located on the downstream side or the outlet side of the compressor wheel. The same applies to the “intake passage on the upstream side of the compressor”.

  In the case of “an exhaust passage between the high-pressure turbine and the low-pressure turbine”, this is synonymous with “an exhaust passage downstream of the high-pressure turbine and upstream of the low-pressure turbine”. Accordingly, this includes a passage portion in the high-pressure turbine housing located downstream or outlet of the high-pressure turbine wheel and a passage portion in the low-pressure turbine housing located upstream or inlet of the low-pressure turbine wheel. And are included. It will be understood that “the intake passage between the low-pressure compressor and the high-pressure compressor” is interpreted in the same way.

  Preferably, the internal combustion engine branches from the exhaust passage on the upstream side of the low-pressure turbine and bypasses the exhaust passage on the downstream side of the low-pressure turbine to bypass the low-pressure turbine. A passage, and a low-pressure turbine bypass valve that can be switched to guide exhaust gas upstream of the low-pressure turbine to at least one of the low-pressure turbine and the low-pressure turbine bypass passage. When the fuel cell is operated while the engine body is stopped, the control unit switches the low-pressure turbine bypass valve so as to guide the exhaust on the upstream side of the low-pressure turbine to the low-pressure turbine bypass passage.

  According to this, supply of the exhaust gas of the fuel cell to the low pressure turbine is suppressed or prevented. Therefore, the fuel cell exhaust discharged from the high-pressure turbine can be smoothly discharged to the outside, and the driving efficiency of the high-pressure turbine or the high-pressure turbo can be increased. This also makes it possible to deactivate or stop the low-pressure stage turbo.

  Preferably, the low-pressure stage turbine bypass valve includes a waste gate valve provided in the low-pressure stage turbine bypass passage, and the exhaust gas downstream of the branch position of the low-pressure stage turbine bypass passage and upstream of the low-pressure stage turbine. And a low-pressure turbine shutoff valve provided in the passage. When the fuel cell is operated while the engine body is stopped, the control unit opens the wastegate valve and closes the low-pressure turbine shutoff valve.

  According to this, the exhaust of the fuel cell is guided to the low pressure turbine bypass passage and is prevented from being supplied to the low pressure turbine. Accordingly, as described above, the driving efficiency of the high-pressure turbine or the high-pressure turbocharger can be increased.

  Preferably, the internal combustion engine further includes a throttle valve provided in the intake passage on the downstream side of the branch position of the supply passage. The control unit controls the throttle valve to an opening smaller than the opening during idling when the fuel cell is operated while the engine body is stopped.

  According to this, it is possible to suppress or prevent the intake air or air discharged from the high-pressure compressor from leaking out to the engine body side, and to efficiently supply the intake air to the fuel cell.

  Preferably, the internal combustion engine further includes an EGR passage extending from the exhaust passage upstream of the high-pressure stage turbine to the intake passage downstream of the high-pressure compressor, and an EGR valve provided in the EGR passage. . The control unit controls the EGR valve to an opening smaller than the opening during idling when the fuel cell is operated while the engine body is stopped.

  According to this, leakage of the fuel cell exhaust from the exhaust passage to the intake passage can be suppressed or prevented, and the driving efficiency of the high-pressure turbine or the high-pressure turbocharger can be increased.

  According to the present invention, in an internal combustion engine equipped with a multistage turbocharging system and a fuel cell, an optimum turbocharger can be operated with high efficiency when the fuel cell is operated while the engine body is stopped. The excellent effect is demonstrated.

It is the schematic which shows the structure of embodiment of this invention. It is the schematic which shows an oil supply apparatus and a cooling water supply apparatus. It is the compressor map which compared the characteristic of the compressor with a low pressure turbocharger and a high pressure turbocharger. It is a time chart which shows operation | movement of each valve etc. before and after an engine main body stop. It is a figure which shows the flow of the air before an engine main body stop, engine exhaust, and FC exhaust. It is a figure which shows the flow of the air and FC exhaust after an engine main body stop.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  As shown in FIG. 1, an internal combustion engine (engine) 1 includes an engine body 2, a plurality (two) of turbochargers, that is, a low-pressure turbocharger 3L and a high-pressure turbocharger 3H, and a fuel cell. 4. The engine 1 may be either a spark ignition type internal combustion engine (gasoline engine) or a compression ignition type internal combustion engine (diesel engine). In this embodiment, the engine 1 is a spark ignition type internal combustion engine. The engine 1 is mounted on a vehicle (automobile) (not shown).

  Hereinafter, the low-pressure turbocharger is also referred to as “LP turbo”, and the high-pressure turbocharger is also referred to as “HP turbo”. The low pressure stage is also expressed as “LP”, the high pressure stage as “HP”, and the fuel cell as “FC”.

  The engine body 2 includes basic engine components such as a cylinder block, a cylinder head, a crankcase, an oil pan, a head cover, a piston, a connecting rod, a crankshaft, a camshaft, and an intake / exhaust valve. The engine body 2 includes a plurality of cylinders, specifically four cylinders. Each cylinder is provided with a fuel injection injector 41 and a spark plug 42.

  An intake passage 5 and an exhaust passage 6 are connected to the engine body 2, and a low-pressure turbocharger 3L and a high-pressure turbocharger 3H are provided in series so as to straddle the intake passage 5 and the exhaust passage 6. . As is well known, the high-pressure turbocharger 3H is provided on the near side and the low-pressure turbocharger 3L is provided on the far side with respect to the engine body 2.

  The low-pressure stage turbocharger 3L and the high-pressure stage turbocharger 3H constitute a multistage turbocharger system, particularly a two-stage sequential turbosystem. In the exhaust passage 6, a high-pressure turbine 3HT of the high-pressure turbocharger 3H is disposed on the upstream side, and a low-pressure turbine 3LT of the low-pressure turbocharger 3L is disposed on the downstream side thereof. In addition, in the intake passage 5, a low-pressure stage compressor 3LC of the low-pressure turbocharger 3L is arranged upstream, and a high-pressure stage compressor 3LC of the high-pressure turbocharger 3H is arranged downstream thereof. Yes.

  Hereinafter, the low-pressure turbine is also referred to as “LP turbine”, the high-pressure turbine as “HP turbine”, the low-pressure compressor as “LP compressor”, and the high-pressure compressor as “HP compressor”. Further, “upstream side” and “downstream side” refer to the upstream side and the downstream side in the flow direction of intake air or exhaust gas as indicated by arrows in the figure.

  In the intake passage 5, an air flow meter 7 for detecting the amount of intake air is provided upstream of the low-pressure stage compressor 3LC, and an intercooler 8 and an electronically controlled throttle valve 9 are provided downstream of the high-pressure stage compressor 3HC. Are provided in series. An air cleaner (not shown) is provided at the upstream end of the intake passage 5.

  In the exhaust passage 6, an exhaust purification catalyst 10 is provided on the downstream side of the low-pressure stage turbine 3LT. Although only one exhaust purification catalyst 10 is shown in the figure, a plurality of exhaust purification catalysts 10 may be provided. In the case of this embodiment, the exhaust purification catalyst 10 is composed of a three-way catalyst having an oxygen storage capacity. However, the number and type of the exhaust purification catalyst 10 are arbitrary.

  Further, an LP turbine bypass passage 11 is provided in parallel with the exhaust passage 6 so as to bypass or bypass the low-pressure stage turbine 3LT. The LP turbine bypass passage 11 is branched from the exhaust passage 6 on the downstream side of the high-pressure stage turbine 3HT and on the upstream side of the low-pressure stage turbine 3LT, and is connected to the exhaust passage 6 on the downstream side of the low-pressure stage turbine 3LT and on the upstream side of the exhaust purification catalyst 10. Merged. A waste gate valve 12 is provided in the LP turbine bypass passage 11.

  A variable vane or variable nozzle (VN) 13 is provided on the upstream side or the inlet of the high-pressure turbine 3HT in the exhaust passage 6. An HP turbine bypass passage 14 is provided in parallel with the exhaust passage 6 so as to bypass the high-pressure turbine 3HT. The HP turbine bypass passage 14 is branched from the exhaust passage 6 at the position of the exhaust manifold 18 upstream of the variable nozzle 13, and is located downstream of the high-pressure turbine 3 HT and upstream of the branch position of the LP turbine bypass passage 11. To join. An HP turbine bypass valve 19 is provided in the HP turbine bypass passage 14.

  The exhaust manifold 18 forms the most upstream portion of the exhaust passage 6 and is attached to the cylinder head of the engine body 2 to join exhaust gases from the cylinders.

  An HP compressor bypass passage 20 is provided in parallel with the intake passage 5 to bypass the high-pressure compressor 3HC. The HP compressor bypass passage 20 is branched from the intake passage 5 downstream of the low-pressure compressor 3LC and upstream of the high-pressure compressor 3HC, and merges with the intake passage 5 downstream of the high-pressure compressor 3HC and upstream of the intercooler 8. Is done. An HP compressor bypass valve 21 is provided in the HP compressor bypass passage 20.

  An EGR device 44 is provided to circulate a part of exhaust gas (referred to as engine exhaust) from the engine body 2 to the intake side. The EGR device 44 includes an EGR passage 45, an EGR cooler 46, and an EGR valve 47. The EGR passage 45 extends from the exhaust manifold 18 to the intake passage 5 between the throttle valve 9 and the intake manifold 47 and connects the two. The EGR cooler 46 and the EGR valve 47 are provided in the EGR passage 45 in this order from the upstream side.

  The intake manifold 47 constitutes the most downstream portion of the intake passage 5 and is attached to the cylinder head of the engine body 2 to distribute and supply intake air to each cylinder.

  An electric fuel pump 22 is provided to supply fuel to the injector 41 of each cylinder of the engine body 2. The fuel pump 22 sends fuel to the delivery pipe 23. The fuel accumulated in the delivery pipe 23 is directly injected into the cylinder from the injector 41 of each cylinder. Thus, although the engine of this embodiment is a direct injection type, the injection method is not particularly limited, and may be a port injection type.

  An electric FC fuel pump 15 is provided to supply fuel to the fuel cell 4. Between the FC fuel pump 15 and the fuel cell 4, an FC fuel metering valve 16 for adjusting the fuel supply amount to the fuel cell 4 is provided. As described above, in this embodiment, the fuel pump is provided separately for the injector and for the fuel cell, but may be shared.

  As shown in FIG. 2, an oil supply device 61 and a cooling water supply device 71 are provided to supply lubricating oil and cooling water to the low-pressure stage turbocharger 3L and the high-pressure stage turbocharger 3H, respectively. . The oil supply device 61 includes an electric oil supply pump 62, an LP oil passage 63 and an HP oil passage 64 that extend from the oil supply pump 62 to the low-pressure turbocharger 3L and the high-pressure turbocharger 3H, respectively, An LP oil supply valve 65 and an HP oil supply valve 66 provided separately in the oil passage 63 and the HP oil passage 64 are provided.

  Similarly, the cooling water supply device 71 includes an electric cooling water supply pump 72, an LP cooling water passage 73 and an HP that extend from the cooling water pump 72 to the low-pressure turbocharger 3L and the high-pressure turbocharger 3H, respectively. A cooling water passage 74, and an LP cooling water supply valve 75 and an HP cooling water supply valve 76 provided individually in the LP cooling water passage 73 and the HP cooling water passage 74 are provided.

  Returning to FIG. 1, in addition, a battery 17 for supplying electric power to each electrical component or electrical component of the vehicle, and an electric motor, that is, a starter motor 48 for cranking the engine body 2 for starting or starting the engine body 2, Is provided. Although the kind of the battery 17 is arbitrary, in this embodiment, it is a general lead acid battery. The starter motor 48 appropriately rotates the crankshaft of the engine body 2.

  An air supply path 25 is provided to extract air from the intake passage 5 and supply it to the fuel cell 4. The supply passage 25 is branched from the intake passage 5 on the downstream side of the high-pressure compressor 3HC and connected to the fuel cell 4, and the intake passage between the low-pressure compressor 3LC and the high-pressure compressor 3HC. 5 and a second air supply path 25 </ b> B branched from 5 and connected to the fuel cell 4.

  Specifically, an air supply control valve 26 is provided in the air supply path 25. The first air passage 31 branched from the HP compressor bypass passage 20 on the downstream side of the HP compressor bypass valve 21 and connected to the air supply control valve 26, and the HP compressor bypass passage 20 on the upstream side of the HP compressor bypass valve 21 A second air passage 32 that branches and connects to the air supply control valve 26 and a third air passage 33 that connects the air supply control valve 26 and the fuel cell 4 to each other are provided. A branch position of the first air passage 31 in the HP compressor bypass passage 20 is indicated by a reference symbol P1, and a branch position of the second air passage 32 in the HP compressor bypass passage 20 is indicated by a reference symbol P2.

  The first air supply passage 25 </ b> A is formed by a portion from the downstream end to the branch position P <b> 1 in the HP compressor bypass passage 20, the first air passage 31, and the third air passage 33.

  The second air supply passage 25B is formed by a portion from the upstream end to the branch position P2 in the HP compressor bypass passage 20, the second air passage 32, and the third air passage 33.

  In the present embodiment, the downstream portion of the first supply passage 25 </ b> A and the second supply passage 25 </ b> B is commonly formed by the third air passage 33 on the downstream side of the supply control valve 26 or on the fuel cell 4 side. Has been. However, it is naturally possible to form these separately.

  The air supply control valve 26 is a valve for switching the supply source of air (also referred to as FC air) supplied to the fuel cell 4, in other words, the air supply path 25 is connected to the first air supply path 25A and the second air supply path 25A. This is a valve for switching to at least one of the air supply paths 25B. In the case of this embodiment, the air supply control valve 26 is constituted by a single three-way valve, and is installed at the joining position of the first air passage 31 and the second air passage 32. However, the type and installation position are arbitrary. For example, when the first air supply path 25A and the second air supply path 25B are formed completely separately, an air supply control valve is formed by a two-way valve individually provided in the air supply paths 25A and 25B. It doesn't matter.

  Next, an exhaust passage 27 is provided in order to supply or discharge exhaust gas from the fuel cell 4 (referred to as FC exhaust) to the exhaust passage 6. The exhaust passage 27 extends from the fuel cell 4 and connects to the exhaust passage 6 upstream of the high-pressure turbine 3HT, and extends from the fuel cell 4 between the high-pressure turbine 3HT and the low-pressure turbine 3LT. And a second exhaust passage 27 </ b> B connected to the exhaust passage 6.

  Specifically, an exhaust control valve 28 is provided in the exhaust path 27. A first exhaust passage 34 that connects the fuel cell 4 and the exhaust control valve 28 to each other, a second exhaust passage 35 that extends from the exhaust control valve 28 and joins the exhaust manifold 18, and extends from the exhaust control valve 28, HP A third exhaust passage 36 that joins and connects to the exhaust passage 6 downstream of the joining position of the turbine bypass passage 14 and upstream of the branching position of the LP turbine bypass passage 11 is provided. A joining position of the third exhaust passage 36 in the exhaust passage 6 is indicated by a symbol Q.

  The first exhaust passage 27 </ b> A is formed by the first exhaust passage 34 and the second exhaust passage 35. The second exhaust passage 27 </ b> B is formed by the first exhaust passage 34 and the third exhaust passage 36.

  In the present embodiment, on the upstream side of the exhaust control valve 28 or the fuel cell 4 side, the upstream side portion of the first exhaust path 27A and the second exhaust path 27B is formed in common by the first exhaust path 34. . However, it is naturally possible to form these separately.

  The exhaust control valve 28 is a valve for switching the discharge destination of the FC exhaust discharged from the fuel cell 4, in other words, the exhaust path 27 is switched to at least one of the first exhaust path 27A and the second exhaust path 27B. It is a valve for. In the case of this embodiment, the exhaust control valve 28 is constituted by a single three-way valve, and is installed at a branch position between the second exhaust passage 35 and the third exhaust passage 36. However, the type and installation position are arbitrary. For example, when the first exhaust path 27A and the second exhaust path 27B are formed completely separately, the exhaust control valve may be formed by a two-way valve provided individually in the exhaust paths 27A and 27B. .

  In the case of the present embodiment, the first exhaust passage 34 is configured to send exhaust gas from the air electrode (cathode) 4A and the fuel electrode (anode) 4B of the fuel cell 4 to the downstream side after merging. .

  Next, an LP (low pressure stage) compressor bypass passage 37 is juxtaposed with the intake passage 5 to bypass the low pressure compressor 3LC. The LP compressor bypass passage 37 is branched from the intake passage 5 upstream of the low-pressure stage compressor 3LC and downstream of the air flow meter 7, and is taken downstream of the high-pressure stage compressor 3HC and upstream of the branch position of the HP compressor bypass passage 20. It joins the passage 5.

  A switchable LP compressor bypass valve 38 is provided so as to guide intake air upstream of the low-pressure compressor 3LC to at least one of the low-pressure compressor 3LC and the LP compressor bypass passage 37. In the case of this embodiment, the LP compressor bypass valve 38 is constituted by a single three-way valve, and is installed at a branch position of the LP compressor bypass passage 37 in the intake passage 5. However, the type and installation position are arbitrary. For example, the LP compressor bypass valve may be formed by a two-way valve individually provided in the branch position of the LP compressor bypass passage 37 and the intake passage 5 between the low-pressure compressor 3LC and the LP compressor bypass passage 37. Absent.

  In addition, an LP (low pressure stage) turbine shut-off valve 39 is provided in the exhaust passage 6 downstream of the branch position of the LP turbine bypass passage 11 and upstream of the low pressure turbine 3LT. The LP turbine cutoff valve 39 and the waste gate valve 12 constitute an LP turbine bypass valve. As will be understood later, the LP turbine bypass valve is a switchable valve that guides the exhaust gas upstream of the low-pressure stage turbine 3LT to at least one of the low-pressure stage turbine 3LT and the LP turbine bypass passage 11.

  In order to control the engine 1 and the vehicle, an electronic control unit (ECU) 100 as a control device or a control unit is provided. The ECU 100 includes a CPU, a storage device such as a ROM and a RAM, an A / D converter, an input / output interface, and the like. Various programs, data, maps, and the like are stored in the storage device, and the ECU 100 executes various controls by executing these programs.

  In addition to the air flow meter 7 described above, the ECU 100 inputs various signals from the crank angle sensor 51, the accelerator opening sensor 52, the key switch 53, the brake switch 54, the vehicle speed sensor 55, and other various sensors and switches. The ECU 100 also includes the above-described injector 41, spark plug 42, throttle valve 9, waste gate valve 12, variable nozzle 13, EGR valve 47, starter motor 48, fuel pump 22, HP turbine bypass valve 19, HP compressor bypass valve 21, Control signals are output to the FC fuel pump 15, the FC fuel metering valve 16, the air supply control valve 26, the exhaust control valve 28, the LP compressor bypass valve 38, and the LP turbine shut-off valve 39, respectively, to control them.

  Based on the signal from the air flow meter 7, the ECU 100 detects an intake air amount that is the amount of intake air per unit time, that is, an intake flow rate. The ECU 100 detects the load of the engine 1 based on at least one of the accelerator opening detected by the accelerator opening sensor 52 and the intake air amount detected by the air flow meter 7.

  The ECU 100 detects the crank angle itself and the rotational speed of the engine 1 based on the crank pulse signal from the crank angle sensor 51. Here, “the number of rotations” means the number of rotations per unit time and is synonymous with the rotation speed. In the present embodiment, it means rpm per minute.

  Here, the fuel cell 4 will be described in detail. As is well known, the fuel cell 4 generates power by an electrochemical reaction between air and fuel (hydrogen). The fuel cell 4 of this embodiment is a solid oxide type or a solid electrolyte type (SOFC), but other types of fuel cells such as a solid polymer type (PEFC), a phosphoric acid type (PAFC), and a molten carbonate type. (MCFC) can also be used.

The fuel cell 4 is mainly composed of a cell stack formed by stacking a plurality of cells composed of an air electrode 4A, a fuel electrode 4B, and an electrolyte sandwiched between these electrodes with a separator interposed therebetween. Oxygen O ₂ contained in the air sent from the intake passage 5 is substantially supplied to the air electrode 4A. Hydrogen H ₂ obtained by reforming liquid fuel (in this embodiment, gasoline) is substantially supplied to the fuel electrode 4B. Carbon monoxide CO may be supplied to the fuel electrode. In this case, carbon dioxide CO ₂ is discharged after the reaction. The main component of the exhaust gas from the fuel cell 4 is water vapor.

Compared to other types of fuel cells, the advantages of using SOFC are as follows.
(1) Since the operating temperature is relatively high at 450 to 1000 ° C. and close to the engine exhaust temperature, high-temperature FC exhaust can be used for driving the turbine.
(2) Since the operating temperature is high, the fuel can be reformed inside, the reformer can be omitted, and the liquid fuel can be directly supplied.
(3) Power generation efficiency is relatively high (45 to 65%) and compact.

  In the case of this embodiment, the fuel cell 4 functions as a power generation device for charging the battery 17 as a main power source or an auxiliary power source for assisting the main power source. Therefore, unlike a general engine, the engine 1 of the present embodiment does not include a generator or an alternator that is mechanically driven by a crankshaft. A fuel cell 4 is provided in place of the alternator. By omitting the mechanical generator in this way, it is possible to reduce engine mechanical loss and improve fuel efficiency. However, an embodiment in which the fuel cell 4 is used in combination with a mechanical generator and an embodiment in which the fuel cell 4 is used for other purposes such as power are possible.

  Next, a multistage turbocharging system will be described. The high-pressure stage turbocharger 3H is smaller or smaller in diameter than the low-pressure stage turbocharger 3L. The low-pressure stage turbocharger 3L is mainly used for the low engine speed range with the high-pressure stage turbocharger 3H, and the high-speed area turbocharger 3L. It comes to take charge in.

  When the engine speed increases from the idle speed, first, the rotation of the small high-pressure turbocharger 3H starts up, and supercharging by the high-pressure turbocharger 3H is executed. As a result, a high engine torque can be obtained even in a low rotation range. The high-pressure turbocharger 3H has a better supercharging response than the low-pressure turbocharger 3L, and can improve the turbo lag particularly in the emission mode range and the normal range.

  The emission mode region refers to an engine operation region used when the vehicle is operated in accordance with an emission mode (JC08 or the like) defined by the laws and regulations of each country. Further, the normal range refers to an engine operating range that is used when driving a general vehicle. Each of these is a region from a low rotation / low load of the engine to a middle rotation / medium load, and is a region where the high-pressure turbocharger 3H mainly works.

  Thereafter, when the engine speed further increases, the rotation of the relatively large low-pressure turbocharger 3L starts up, and supercharging by the low-pressure turbocharger 3L is executed. As a result, a high engine output can be generated in a high rotation range. Since the low-pressure stage turbocharger 3L is large, it can accept a large amount of exhaust gas in a high rotation range.

  In order to realize such an operation, the HP turbine bypass valve 19 and the HP compressor bypass valve 21 are generally controlled by the ECU 100 as follows. When the engine speed increases from the idle speed, the HP turbine bypass valve 19 and the HP compressor bypass valve 21 are first controlled to be fully closed. Then, the entire amount of engine exhaust is supplied to the HP turbine 3HT without bypassing the HP turbine 3HT. As a result, the rotation of the HP turbine 3HT and then the HP compressor 3HC is started, and supercharging by the HP turbo 3H is performed.

  At this time, the exhaust gas that has passed through the HP turbine 3HT is supplied to the LP turbine 3LT. At this time, much of the exhaust gas energy (pressure energy and thermal energy) has already been consumed. Few. And the amount of work of the LP compressor 3LC is inevitably small. The HP compressor 3HC will supercharge the intake air slightly increased in pressure by the LP compressor 3LC.

  The low speed region where the HP turbine bypass valve 19 and the HP compressor bypass valve 21 are fully closed is a region where supercharging is executed substantially only by the HP turbo 3H. This region is referred to as the HP turbo 3H operating region.

  Thereafter, when the engine speed increases, the HP turbine bypass valve 19 and the HP compressor bypass valve 21 are gradually opened. Then, the amount of engine exhaust that bypasses the HP turbine 3HT increases, the work amount of the HP turbine 3HT decreases, and at the same time, the work amount of the LP turbine 3LT increases. Accordingly, the work amount of the HP compressor 3HC decreases, and at the same time, the work amount of the LP compressor 3LC increases. That is, the supercharging work gradually shifts from the HP turbo 3H to the LP turbo 3L.

  The intermediate rotation region in which the HP turbine bypass valve 19 and the HP compressor bypass valve 21 are at an intermediate opening is a region where supercharging is executed by both the HP turbo 3H and the LP turbo 3L. This area is called a transition area. The transition area is an area having a relatively narrow engine speed.

  Thereafter, when the engine speed further increases, the HP turbine bypass valve 19 and the HP compressor bypass valve 21 are controlled to be fully opened. Then, almost all of the engine exhaust bypasses the HP turbine 3HT and is supplied to the LP turbine 3LT. At this time, since the inlet pressure and the outlet pressure of the HP turbine 3HT are substantially equal, the HP turbine 3HT substantially does not work.

  Along with this, the LP compressor 3LC starts supercharging in earnest. Almost all of the air discharged from the LP compressor 3LC is guided to the engine body side, bypassing the HP compressor 3HC. At this time, the HP compressor 3HC substantially does not work.

  The high rotation region where the HP turbine bypass valve 19 and the HP compressor bypass valve 21 are fully opened is a region where supercharging is performed substantially only by the LP turbo 3L. This region is referred to as the LP turbo 3L operating region.

  As in the case of a normal single turbo that is not a multi-stage type, in the operation region of the LP turbo 3L, when the supercharging pressure reaches a predetermined upper limit pressure, the waste gate valve 12 is opened and the supercharging pressure limiting control is executed. Except this time, the waste gate valve 12 is closed.

  In the operating region of the HP turbo 3H, the opening degree of the variable nozzle 13 is controlled according to the engine operating state, and the inlet pressure of the HP turbine 3HT is controlled. In order to increase the pressure in the exhaust manifold 18 during EGR execution, the opening degree of the variable nozzle 13 may be reduced.

  During operation of the engine body 2 as described above, the LP turbine shut-off valve 39 is opened, and engine exhaust is allowed to flow toward the LP turbine 3LT. Further, the LP compressor bypass valve 38 is switched to the LP compressor 3LC side so that the engine intake air does not pass through the LP compressor bypass passage 37 but passes only through the LP compressor 3LC.

  Now, the engine 1 of the present embodiment including the multi-stage turbocharger system (3L, 3H) and the fuel cell 4 allows the air supplied to the fuel cell 4 to be supplied to the HP compressor 3HC or LP compressor 3LC during the operation of the fuel cell 4. It extracts from the intake passage 5 on the downstream side. That is, the HP compressor 3HC or the LP compressor 3LC is shared with the engine body 2 as an air source for the fuel cell 4, and a part of the intake air whose pressure is increased by these compressors is extracted and supplied to the fuel cell 4. Therefore, it is not necessary to provide a separate air source such as a motor compressor for supplying air to the fuel cell, and the complexity of the apparatus and the increase in cost can be avoided.

  Further, the engine 1 of the present embodiment is configured to supply exhaust gas discharged from the fuel cell 4 to the exhaust passage 6 on the upstream side of the HP turbine 3HT or the LP turbine 3LT while the fuel cell 4 is in operation. Thereby, the FC exhaust can be effectively used for driving the HP turbine 3HT or the LP turbine 3LT.

  For example, in the operating region of the HP turbo 3H, that is, in the low rotation region where the HP turbine bypass valve 19 and the HP compressor bypass valve 21 are fully closed, the ECU 100 switches the supply passage 25 to the first supply passage 25A, That is, the air supply control valve 26 is switched so that the third air passage 33 is connected to or communicates only with the first air passage 31. Then, air is extracted from the downstream side of the HP compressor 3HC performing supercharging, and this air is supplied to the fuel cell 4 through the first air supply path 25A.

  Further, at this time, the ECU 100 switches the exhaust control valve 28 so that the exhaust path 27 is switched to the first exhaust path 27A, that is, the first exhaust path 34 is connected to or communicates only with the second exhaust path 35. Then, the FC exhaust discharged from the fuel cell 4 is supplied or discharged to the exhaust passage 6 (specifically, the exhaust manifold 18) on the upstream side of the HP turbine 3HT through the first exhaust passage 27A. This supplied or exhausted FC exhaust can be effectively used for rotational driving of the HP turbine 3HT.

  Further, for example, in the operation region of the LP turbo 3L, that is, in the high rotation region where the HP turbine bypass valve 19 and the HP compressor bypass valve 21 are fully opened, the ECU 100 switches the supply passage 25 to the second supply passage 25B, That is, the air supply control valve 26 is switched so that the third air passage 33 is connected to or communicates only with the second air passage 32. Then, air is extracted from the downstream side of the LP compressor 3LC performing supercharging and the upstream side of the HP compressor 3HC, and this air is supplied to the fuel cell 4 through the second air supply path 25B.

  Further, at this time, the ECU 100 switches the exhaust control valve 28 so that the exhaust path 27 is switched to the second exhaust path 27B, that is, the first exhaust path 34 is connected or communicated only with the third exhaust path 36. Then, the FC exhaust discharged from the fuel cell 4 is supplied or discharged to the exhaust passage 6 between the HP turbine 3HT and the LP turbine 3LT through the second exhaust passage 27B. The supplied or discharged FC exhaust can be effectively used for the rotational drive of the LP turbine 3LT.

  Of course, the ECU 100 operates the FC fuel pump 15 while the fuel cell 4 is operating, opens the FC fuel metering valve 16, and supplies fuel to the fuel cell 4.

  Incidentally, as described above, when the engine body 2 is in a stopped state, power generation by the fuel cell 4 is required, and the fuel cell 4 may have to be operated. Here, when the engine body 2 is in a stopped state, the fuel injection by the injector 41 and the ignition by the spark plug 42 are not executed, and the crankshaft is stopped rotating. Further, the stop of the engine body 2 includes a case where the engine body 2 is stopped by execution of idle stop control described later. In addition, the case where power generation by the fuel cell 4 is necessary is, for example, when the remaining battery level is reduced below a predetermined threshold due to the operation of an electrical component such as an air conditioner or an electric load, or the battery discharge amount is a predetermined threshold. This is the case when the number increases.

  In order to operate the fuel cell 4, fuel must be supplied to the fuel cell 4 as well as necessary air must be sent to the fuel cell 4 and exhaust gas from the fuel cell 4 must be discharged. Don't be. For this reason, at least one of the low-pressure turbocharger 3L and the high-pressure turbocharger 3H must be operated while the engine body 2 is stopped.

  However, as to which of these is to be operated, it is necessary to fully consider the characteristics of the individual turbochargers and the characteristics of the fuel cell. In addition, it is necessary to devise so as to maximize the efficiency during the operation.

  In order to operate at least one of the low-pressure turbocharger 3L and the high-pressure turbocharger 3H, it is possible to prohibit the engine body 2 from being stopped or restart the engine body 2. However, this inevitably consumes fuel, and the fuel efficiency deteriorates. Further, if the restart is automatically performed, the engine is unexpectedly started for the user, which causes a sense of incongruity.

  Therefore, in the present embodiment, when the fuel cell 4 is operated while the engine body 2 is stopped, the following control is executed in order to operate the optimum turbocharger with high efficiency.

  First, when the fuel cell 4 is operated while the engine body 2 is stopped, the high-pressure turbocharger 3H is operated or used. That is, the FC exhaust discharged from the fuel cell 4 is discharged to the upstream side exhaust passage 6 of the HP turbine 3HT through the first exhaust passage 27A in the same manner as in the operation region or low rotation region of the HP turbo 3H. Then, the HP turbine 3HT is rotationally driven using the discharged FC exhaust gas.

  And HP compressor 3HC coaxially connected with HP turbine 3HT is rotated, and air is discharged from HP compressor 3HC. The discharged air is supplied to the fuel cell 4 through the first air supply path 25A.

  At the same time, fuel is supplied to the fuel cell 4.

  Then, continuously, the HP turbine 3HT and the HP compressor 3HC are rotationally driven by the FC exhaust discharged from the fuel cell 4, and air is supplied to the fuel cell 4 so that the fuel cell 4 can be operated independently. Here, “the fuel cell operates independently” means that the turbine and the compressor are rotated by the exhaust of the fuel cell, and these are not rotated by the engine exhaust or other external force, that is, the engine body 2 is not operated. In this state, air can be supplied to the fuel cell, and when the fuel is supplied, the fuel cell operates and continues to generate power. In other words, the fuel cell itself is operated by rotating the turbine and the compressor only by the exhaust of the fuel cell.

  By the way, the reason for operating not the low-pressure turbocharger 3L but the high-pressure turbocharger 3H is as follows.

  The low-pressure stage turbocharger 3L is larger and larger in capacity than the high-pressure stage turbocharger 3H, and is set to a size that can cover the required air amount at the highest output point of the engine body 2. However, the low-pressure stage turbocharger 3L is too large to send the amount of air necessary for power generation of the fuel cell 4 while the engine body is stopped, and even if it is operated, it can be operated only at low turbo efficiency. . Therefore, the efficiency of the entire system is also reduced.

  FIG. 3 is a compressor map in which the characteristics of the compressor are compared between the low pressure turbocharger 3L and the high pressure turbocharger 3H. The horizontal axis represents the compressor air flow rate, and the vertical axis represents the pressure ratio. A one-dot chain line indicates the characteristics of the low-pressure turbocharger 3L, and a solid line indicates the characteristics of the high-pressure turbocharger 3L. As can be seen from the figure, the characteristics of the high pressure turbocharger 3L are shifted to the low flow rate side and the low pressure ratio side with respect to the characteristics of the low pressure turbocharger 3L.

η _L and η _H indicate high efficiency regions in which the compressor efficiency is equal to or higher than a relatively high threshold in the low pressure turbocharger 3L and the high pressure turbocharger 3H, respectively. S _L, S _H, respectively, shows the surge limit of the low-pressure stage turbocharger 3L and high-pressure stage turbocharger 3H. N _L and N _H respectively indicate operation lines when the low-speed turbocharger 3L and the high-pressure turbocharger 3H have the same turbine speed. X indicated by an asterisk indicates an operating point when the fuel cell 4 is operated while the engine body is stopped.

As can be seen, even by operating the low-pressure stage turbocharger 3L while stopping the engine body, the operating point X is deviates from a high efficiency region eta _L, it is impossible to obtain a high turbo efficiency. In contrast, when operating the high-pressure stage turbocharger 3H during stoppage engine body, now operating point X enters the high efficiency region eta _H, it is possible to obtain a high turbo efficiency.

  Therefore, in order to send the amount of air necessary for the operation of the fuel cell 4 while the engine body is stopped, the high-pressure stage turbocharger 3H is more suitable in size than the low-pressure stage turbocharger 3L. Therefore, by operating the high-pressure stage turbocharger 3H, it is possible to increase the turbo efficiency and thus the overall system efficiency, which is advantageous.

  Second, when the fuel cell 4 is operated while the engine body 2 is stopped, the LP compressor bypass valve 38 is switched so as to guide the intake air upstream of the low-pressure stage compressor 3LC to the LP compressor bypass passage 37.

  Then, the intake air does not pass through the low-pressure stage compressor 3LC but passes through the LP compressor bypass passage 37 and is supplied to the high-pressure stage compressor 3HC. As a result, the flow resistance is reduced, and loss due to the intake air driving the low-pressure compressor 3LC is reduced, and the intake air can be efficiently supplied to the high-pressure compressor 3HC. As a result, it is possible to increase the turbo efficiency and thus the efficiency of the entire system.

  As described above, according to this embodiment, when the fuel cell 4 is operated while the engine body 2 is stopped, it is possible to operate the optimum turbocharger with high efficiency.

  Hereinafter, the control in the present embodiment will be described in more detail. First, idle stop control that can be executed in the present embodiment will be described.

  In general, the idle stop control means that the engine body 2 is automatically stopped when a predetermined stop condition is established such that the vehicle is idle stopped, and then the engine body 2 is automatically restarted when a predetermined release condition is satisfied. This is the control to start. When the stop condition is satisfied, the fuel injection and ignition in the engine body 2 are stopped, and when the release condition is satisfied, the fuel injection and ignition in the engine body 2 are restarted, the starter motor 18 is turned on, and the engine body 2 is restarted. It is started. Note that the idle stop control is also referred to as start-and-stop control or idle reduction control.

For example, the stop condition is satisfied when all of the following conditions are satisfied.
(1) The brake pedal is depressed (determined by the output of the brake switch 54, etc.).
(2) The accelerator pedal is not depressed (determined by the output of the accelerator opening sensor 52).
(3) The vehicle speed is equal to or less than a predetermined vehicle speed (for example, 8 km / h) slightly higher than zero (determined by the output of the vehicle speed sensor 55).
(4) The engine speed is equal to or lower than a predetermined speed (for example, 1000 rpm) slightly higher than the target idle speed (for example, 800 rpm) (the engine speed is calculated based on the output of the crank angle sensor 31).

  Further, for example, the release condition is satisfied when at least one of the above conditions (1) to (3) is not satisfied while the engine body 2 is stopped.

  Next, control when the fuel cell 4 is operated or operated independently while the engine body 2 is stopped will be described with reference to FIGS.

  FIG. 4 shows the operation of each valve and the like before and after the engine body is stopped. Here, the engine body 2 is idled before the engine body is stopped, and the fuel cell 4 is operated. During this time, the engine body 2 is stopped by the execution of the idle stop control, and the fuel cell 4 continues to operate. An example is described. In FIG. 4, t1 is the time when the vehicle is stopped, and t2 is the time when the engine body is stopped. Before the engine main body is stopped, the operation state in the low rotation region described above, that is, only the HP turbo 3H is substantially operated.

  As shown in FIG. 4A, when the engine body is stopped, the engine speed changes from the idle speed Ni to zero. Further, as shown in FIG. 4B, when the engine body is stopped, the LP turbine rotation speed gradually changes from the idling speed NtLi to zero.

  On the other hand, as shown in FIG. 4C, when the engine main body is stopped, the HP turbine rotational speed gradually changes from the idle speed NtHi to a lower rotational speed NtH1 (> 0). This rotational speed NtH1 is maintained. This is because the HP turbo 3H is independently operated as described above.

  As shown in FIG. 4D, the throttle valve 9 is controlled to the opening degree THi at the time of idling before the engine body stops, but the opening degree is smaller than the opening degree THi at the time of idling after the engine body stops. In this embodiment, the fully closed position (opening degree = 0) is set so that the intake passage 5 is completely closed.

  As shown in FIG. 4E, the EGR valve 47 is controlled to the opening degree Vegri at the time of idling before the engine body stops, but after the engine body stops, the opening degree is smaller than the opening degree Vegri at the time of idling. In this embodiment, the fully closed position (opening degree = 0) is set so that the EGR passage 45 is completely closed.

  As shown in FIG. 4F, the HP compressor bypass valve 21 is fully closed before and after the engine body is stopped.

  As shown in FIG. 4G, the air supply control valve 26 is located at a position where air is extracted from the downstream side of the HP compressor 3HC before and after stopping the engine body, in other words, the air supply passage 25 is provided with the first air supply. The position is controlled to switch to the path 25A. This position is referred to as the HP side position and is represented by “HP” in the figure.

  A position where air is extracted from the downstream side of the LP compressor 3LC and the upstream side of the HP compressor 3HC, in other words, a position where the air supply path 25 is switched to the second air supply path 25B is referred to as an LP side position. Indicated in the figure as “LP”.

  As shown in FIG. 4 (H), the waste gate valve 12 is controlled to a fully closed position before the engine main body is stopped, but is opened after the engine main body is stopped, and particularly, an opening larger than the fully closed, preferably It is controlled to the fully open position.

  As shown in FIG. 4 (I), the LP turbine shut-off valve 39 is controlled to the fully open position before the engine main body is stopped, but is closed after the engine main body is stopped, and is particularly controlled to the fully closed position.

  As shown in FIG. 4J, the HP turbine bypass valve 19 is fully closed before and after the engine body is stopped.

  As shown in FIG. 4 (K), the exhaust control valve 28 is located at a position where FC exhaust is supplied to the upstream side of the HP turbine 3HT before and after stopping the engine body, in other words, the exhaust passage 27 is connected to the first air supply passage. The position is switched to 27A. This position is referred to as the HP side position and is represented by “HP” in the figure.

  A position where FC exhaust is supplied to the downstream side LP of the HP turbine 3HT and the upstream side of the LP turbine 3LT, in other words, a position where the exhaust passage 27 is switched to the second exhaust passage 27B is referred to as an LP side position. Indicated in the figure as “LP”.

  As shown in FIG. 4L, the lubricating oil and cooling water for the LP turbo 3L are supplied (ON) to the LP turbo 3L before the engine body stops, but the supply is stopped (OFF) after the engine body stops. ) This is because the LP turbo 3L is stopped when the engine body is stopped (see FIG. 4B).

  As shown in FIG. 4M, the lubricating oil and cooling water for the HP turbo 3H are supplied (ON) to the HP turbo 3H before and after the engine body is stopped. This is because the HP turbo 3H is continuously operated even after the engine body is stopped (see FIG. 4C).

  As shown in FIG. 2, before the engine main body is stopped, the oil supply pump 62 and the cooling water supply pump 72 are operated, and the LP oil supply valve 65, the HP oil supply valve 66, the LP cooling water supply valve 75, and the HP cooling water. Both supply valves 76 are opened. On the other hand, after the engine body is stopped, the oil supply pump 62 and the cooling water supply pump 72 are operated, and the LP oil supply valve 65 and the LP cooling water supply valve 75 are closed, while the HP oil supply valve 66 and the HP cooling water are closed. The supply valve 76 is opened.

  As shown in FIG. 4N, the LP compressor bypass valve 38 is controlled to a position that guides the intake air upstream of the LP compressor 3LC to the LP compressor 3LC before the engine body stops. This position is referred to as the LP side position and is represented by “LP” in the figure.

  On the other hand, the LP compressor bypass valve 38 is controlled to a position where the intake air on the upstream side of the LP compressor 3LC is guided to the LP compressor bypass passage 37, in other words, a position where it is supplied to the HP compressor 3HC after the engine main body is stopped. . This position is referred to as the HP side position and is represented by “HP” in the figure.

  The flow of air, engine exhaust, and FC exhaust before the engine main body stops (during idle operation) corresponding to the operation of these valves and the like is as shown in FIG.

  The engine exhaust is supplied to the HP turbine 3HT to drive the HP turbine 3HT, and then sequentially passes through the LP turbine 3LT and the exhaust purification catalyst 10 and is discharged to the outside.

  The intake air (air) passes through the LP compressor 3LC and is supplied to the HP compressor 3HC, where it is slightly boosted, and then passes through the intercooler 8 and the throttle valve 9 in order to be supplied to the engine body 2.

  EGR gas which is a part of engine exhaust passes through the EGR valve 47 and reaches the intake passage 5.

  The FC exhaust is supplied to the exhaust manifold 18 through the first exhaust passage 27A, where it is merged with the engine exhaust, and then used for driving the HP turbine 3HT.

  The FC air is extracted from the downstream side of the HP compressor 3HC and supplied to the fuel cell 4 through the first air supply path 25A.

  Next, the flow of air and FC exhaust after or after the engine main body is stopped is as shown in FIG. Since the engine body 2 is stopped here, there is no flow of engine exhaust.

  The FC exhaust is supplied to the exhaust manifold 18 through the first exhaust passage 27A and then supplied to the HP turbine 3HT to drive the HP turbine 3HT, as before the engine main body is stopped. Since the waste gate valve 12 is fully open and the LP turbine shut-off valve 39 is fully closed, the FC exhaust is not supplied to the LP turbine 3LT, but passes through the LP turbine bypass passage 11 and reaches the exhaust purification catalyst 10. And then discharged to the outside.

  In this way, the supply of FC exhaust to the LP turbine 3LT is blocked by the LP turbine shut-off valve 39, so that the FC exhaust discharged from the HP turbine 3HT can be smoothly discharged to the outside, and the HP turbine 3HT or HP The driving efficiency of the turbo 3H can be increased. In addition, the LP turbo 3L can thereby be deactivated or stopped.

  Further, since the EGR valve 47 is fully closed, leakage of FC exhaust from the exhaust manifold 18 to the intake passage 5 can be prevented, and this also increases the drive efficiency of the HP turbine 3HT or HP turbo 3H. Can do.

  On the other hand, since the LP compressor bypass valve 38 is at the HP side position, the intake air (air) does not pass through the LP compressor 3LC but passes through the LP compressor bypass passage 37 and is directly supplied to the HP compressor 3HC. As a result, the flow resistance is reduced, and loss due to the intake air driving the LP compressor 3LC is reduced, and the intake air can be efficiently supplied to the HP compressor 3HC. As a result, it is possible to increase the turbo efficiency and thus the efficiency of the entire system.

  After that, the intake air is slightly boosted by the HP compressor 3HC, and does not go to the intercooler 8 side, but the entire amount is directly supplied to the first air supply path 25A. This is because the throttle valve 9 is fully closed so as to completely close the intake passage 5. As a result, it is possible to prevent the intake air from leaking to the engine body 2 side, and the intake air can be efficiently supplied to the fuel cell 4.

  Thereafter, the intake air passes through the first supply passage 25 </ b> A as FC air and is supplied to the fuel cell 4.

  It is possible to start only the fuel cell 4 from the stop state of the engine body 2 and the fuel cell 4. At this time, the ECU 100 turns on the starter motor 48 for a relatively short predetermined time, causes the engine body 2 to perform a motoring operation, and applies an initial motion to the HP turbo 3H. At this time, the fuel cell 4 is activated by the air discharged from the HP compressor 3HC. Thereafter, the HP turbo 3H is continuously operated by FC exhaust, and the fuel cell 4 is operated independently. Also at this time, the operation after stopping the engine body as described above is applicable.

  Although the embodiment of the present invention has been described in detail above, various other embodiments of the present invention are conceivable. For example, the use and type of the internal combustion engine are arbitrary and may be other than those for automobiles.

  In the embodiment, after the engine main body is stopped, the LP compressor bypass valve 38 is completely switched to the HP side so that the intake air does not pass through the LP compressor 3LC but passes only through the LP compressor bypass passage 37. However, the LP compressor bypass valve 38 may be switched to an intermediate position between the LP side and the HP side so that a part of the intake air passes through the LP compressor 3LC and the remaining intake air passes through the LP compressor bypass passage 37. This is because most of the intake air flows to the LP compressor bypass passage 37 having a low flow resistance, and the same effect as described above can be obtained.

  In the embodiment, after the engine main body is stopped, the LP turbine shut-off valve 39 is fully closed so that the FC exhaust does not pass through the LP turbine 3LT but passes through only the LP turbine bypass passage 11. However, the LP turbine shut-off valve 39 does not necessarily need to be fully closed, and may be slightly opened as long as most of the FC exhaust gas can be guided to the LP turbine bypass passage 11, and part of the FC exhaust gas may be part of LP It may be allowed to flow through 3LT. Similarly, the waste gate valve 12 does not necessarily need to be fully opened, and may have an opening smaller than that of the fully opened state.

  In the same way, after the engine main body is stopped, the throttle valve 9 may be opened slightly more than fully closed, or the EGR valve 47 may be opened slightly more than fully closed. However, it is preferable to set these to an opening smaller than the opening at the time of idling.

  The present invention includes all modifications, applications, and equivalents included in the spirit of the present invention defined by the claims. Therefore, the present invention should not be construed as being limited, and can be applied to any other technique belonging to the scope of the idea of the present invention.

1 Internal combustion engine
2 Engine body 3L Low-pressure turbocharger (LP turbo)
3LT Low pressure turbine (LP turbine)
3LC Low-pressure compressor (LP compressor)
3H High-pressure turbocharger (HP turbo)
3HT High-pressure turbine (HP turbine)
3HC high-pressure compressor (HP compressor)
4 Fuel cell (FC)
5 Intake passage 6 Exhaust passage 9 Throttle valve 11 LP turbine bypass passage 12 Waste gate valve 14 HP turbine bypass passage 15 FC fuel pump 16 FC fuel metering valve 17 Battery 19 HP turbine bypass valve 20 HP compressor bypass passage 21 HP compressor bypass valve 25 Air supply path 25A First air supply path 25B Second air supply path 26 Air supply control valve 27 Exhaust path 27A First exhaust path 27B Second exhaust path 28 Exhaust control valve 31 First air path 32 Second Air passage 33 Third air passage 34 First exhaust passage 35 Second exhaust passage 36 Third exhaust passage 37 LP compressor bypass passage 38 LP compressor bypass valve 39 LP turbine shut-off valve 45 EGR passage 47 EGR valve 51 Crank angle sensor 52 Accelerator open Degree sensor 100 Electronic control unit ( ECU)

Claims (5)

An intake passage and an exhaust passage connected to the engine body,
A high-pressure stage turbocharger having a high-pressure stage turbine provided upstream of the exhaust passage and a high-pressure stage compressor provided downstream of the intake passage;
A low-pressure stage turbocharger having a low-pressure stage turbine provided downstream of the exhaust passage and a low-pressure stage compressor provided upstream of the intake passage;
A fuel cell;
An air supply path branched from the intake passage downstream of the high-pressure stage compressor and connected to the fuel cell to supply air to the fuel cell;
An exhaust passage extending from the fuel cell and connected to the exhaust passage upstream of the high-pressure turbine to exhaust the fuel cell exhaust;
A low-pressure compressor bypass passage that branches from the intake passage upstream of the low-pressure compressor and joins the intake passage between the low-pressure compressor and the high-pressure compressor to bypass the low-pressure compressor;
A low pressure stage compressor bypass valve that is switchable to direct intake air upstream of the low pressure stage compressor to at least one of the low pressure stage compressor and the low pressure stage compressor bypass passage;
A control unit for controlling the engine body and the low-pressure compressor bypass valve;
With
The control unit switches the low-pressure stage compressor bypass valve to guide the intake air upstream of the low-pressure stage compressor to the low-pressure stage compressor bypass passage when the fuel cell is operated while the engine body is stopped. An internal combustion engine. A low-pressure turbine bypass passage that branches from the exhaust passage upstream of the low-pressure turbine and joins the exhaust passage downstream of the low-pressure turbine to bypass the low-pressure turbine;
A low-pressure turbine bypass valve that is switchable to guide exhaust upstream of the low-pressure turbine to at least one of the low-pressure turbine and the low-pressure turbine bypass passage;
Further comprising
The control unit switches the low-pressure stage turbine bypass valve to guide the exhaust gas upstream of the low-pressure stage turbine to the low-pressure stage turbine bypass passage when operating the fuel cell while the engine body is stopped. The internal combustion engine according to claim 1. The low-pressure stage turbine bypass valve is provided in a waste gate valve provided in the low-pressure stage turbine bypass passage, and in the exhaust passage downstream of the branch position of the low-pressure stage turbine bypass passage and upstream of the low-pressure stage turbine. A low-pressure stage turbine shut-off valve,
The internal combustion engine according to claim 2, wherein the control unit opens the waste gate valve and closes the low-pressure turbine shut-off valve when operating the fuel cell while the engine body is stopped. . A throttle valve provided in the intake passage downstream from the branch position of the air supply path;
4. The control unit according to claim 1, wherein when the fuel cell is operated while the engine main body is stopped, the control unit controls the throttle valve to an opening smaller than an opening during idling. The internal combustion engine according to one item. An EGR passage extending from the exhaust passage upstream of the high-pressure turbine to the intake passage downstream of the high-pressure compressor; and an EGR valve provided in the EGR passage;
5. The control unit according to claim 1, wherein when the fuel cell is operated while the engine main body is stopped, the control unit controls the EGR valve to an opening smaller than an opening during idling. The internal combustion engine according to one item.

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