JP2014098334A - Internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress generation of condensed water in an exhaust manifold when exhaust gas of a fuel cell is supplied to the exhaust manifold.SOLUTION: An internal combustion engine of this invention includes: an exhaust manifold 19 arranged on a turbine upstream side of a turbocharger; a fuel cell 4; an exhaust passage for supplying the exhaust gas of the fuel cell to the exhaust manifold; a cooling water passage 40 connected to an engine body 2, the exhaust manifold and the fuel cell; and switch means 47 and 48 for switching the cooling water passage so as to supply the cooling water after passing through the fuel cell to the exhaust manifold when the engine body is stopped and the fuel cell is operated.

Description

  The present invention relates to an internal combustion engine, and more particularly to an internal combustion engine provided with a turbocharger and a fuel cell.

  It has been proposed to combine a fuel cell with an internal combustion engine. For example, Patent Document 1 discloses supplying anode off gas from a fuel cell to a turbine housing of a supercharger.

JP 2007-016641 A

  When a fuel cell is combined with an internal combustion engine having a turbocharger, it is advantageous to configure the exhaust gas of the fuel cell to be supplied to the turbine of the turbocharger. This is because the exhaust gas of the fuel cell can be effectively used for driving the turbine to improve efficiency and turbo response.

  On the other hand, it is conceivable to supply the exhaust gas from the fuel cell to the exhaust manifold on the upstream side of the turbine. However, this has the following problems: That is, when the exhaust gas of the fuel cell is supplied to the exhaust manifold when the internal combustion engine (specifically, the engine body) is stopped and the fuel cell is operating, the moisture contained in the exhaust gas of the fuel cell is contained in the exhaust manifold. May condense and generate condensed water. On the other hand, when the exhaust valve of any cylinder is open while the internal combustion engine is stopped, the condensed water in the exhaust manifold may enter the cylinder of the cylinder through the exhaust port. Then, the condensed water may cause oil dilution in the cylinder and may cause a water hammer.

  Accordingly, the present invention has been made in view of the above circumstances, and one object thereof is an internal combustion engine that can suppress the generation of condensed water in the exhaust manifold when supplying exhaust gas from a fuel cell to the exhaust manifold. Is to provide.

According to one aspect of the invention,
Turbocharger,
An exhaust manifold disposed upstream of the turbocharger turbine;
A fuel cell;
An exhaust passage for supplying exhaust gas of the fuel cell to the exhaust manifold;
A cooling water path connected to the engine body, the exhaust manifold and the fuel cell;
Switching means for switching the cooling water path, wherein the cooling water after passing through the fuel cell is supplied to the exhaust manifold while the engine body is stopped and the fuel cell is operating. Switching means for switching the cooling water path;
An internal combustion engine is provided.

  Preferably, the switching means switches the cooling water path so that the cooling water is supplied to the fuel cell by bypassing the engine main body while the engine main body is stopped and the fuel cell is operating.

  Preferably, the switching means switches the cooling water path so that the engine main body is bypassed when the stop time of the engine main body reaches a predetermined time or more.

  Preferably, the switching unit switches the cooling water path so as to bypass the fuel cell and supply the cooling water to the exhaust manifold while the engine main body is stopped and the fuel cell is stopped.

  Preferably, the switching unit switches the cooling water path so as to bypass the fuel cell when the temperature of the fuel cell becomes a predetermined temperature or lower.

  Preferably, the engine body is stopped by idle stop control.

  According to the present invention, it is possible to provide an internal combustion engine that can suppress the generation of condensed water in the exhaust manifold when the exhaust gas of the fuel cell is supplied to the exhaust manifold.

It is the schematic which shows the structure of 1st Embodiment of this invention. It is the schematic which shows the structure of a cooling system. It is the schematic which shows the flow of the cooling water when an engine main body is bypassed. It is a flowchart which shows control of 1st Embodiment. It is the schematic which shows the flow of the cooling water when bypassing a fuel cell in 2nd Embodiment of this invention. It is a flowchart which shows control of 2nd Embodiment.

[First Embodiment]
Hereinafter, a first embodiment 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 turbocharger 3, 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 (not shown). Specifically, the engine 1 is mounted on an automatic vehicle including a torque converter and an automatic transmission. The turbocharger 3 is also expressed as “T / C”, the engine body 2 is also expressed as “E / G”, and the fuel cell 4 is also expressed as “F / C” or “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, and each cylinder is provided with a fuel injection injector and a spark plug. The engine body 2 of the present embodiment has an in-line 4-cylinder configuration.

  An intake passage 5 and an exhaust passage 6 are connected to the engine body 2, and a compressor 3 </ b> C of the turbocharger 3 is disposed in the middle of the intake passage 5, and a turbine 3 </ b> T of the turbocharger 3 is disposed in the middle of the exhaust passage 6. .

  In the intake passage 5, an air flow meter 7 for detecting the amount of intake air is provided upstream of the compressor 3C, and an intercooler 8 and an electronically controlled throttle valve 9 are provided in series downstream of the compressor 3C. ing.

  In the exhaust passage 6, an exhaust purification catalyst 10 is provided on the downstream side of the turbine 3T. Although only one exhaust purification catalyst 10 is shown in the figure, a plurality of exhaust purification catalysts 10 may be provided. In the present embodiment, the exhaust purification catalyst 10 is composed of a three-way catalyst. However, the type of the exhaust purification catalyst 10 is arbitrary.

  In the exhaust passage 6, an exhaust manifold 19 is disposed upstream of the turbine 3T. As is well known, the exhaust manifold 19 is for joining the exhaust ports of the respective cylinders formed in the cylinder head of the engine body 2. The exhaust manifold 19 of the present embodiment is formed separately from the engine body 2 and is attached to the cylinder head. However, the exhaust manifold 19 may be formed integrally with the engine body 2, particularly the cylinder head.

  Further, a bypass passage 11 that bypasses the turbine 3T is provided in the exhaust passage 6 so that exhaust gas (referred to as engine exhaust) from the engine body 2 bypasses the turbine 3T and flows downstream thereof. The bypass passage 11 joins the exhaust passage 6 on the upstream side of the exhaust purification catalyst 10. A waste gate valve 12 is provided in the bypass passage 11, and the supercharging pressure can be adjusted by opening and closing the waste gate valve 12. Instead of the bypass passage 11 and the waste gate valve 12, a variable vane or a variable nozzle (VN) may be provided at the turbine inlet.

  In order to supply cooling water and lubricating oil to the turbocharger 3, an electric cooling water pump 13 and a lubricating oil pump 14 are provided, respectively.

  An electric fuel pump 15 is provided to supply fuel to the engine body 2 and the fuel cell 4. The fuel pump 15 is shared by the engine main body 2 and the fuel cell 4, but may be a separate body. Between the fuel pump 15 and the fuel cell 4, a metering valve 16 for adjusting the amount of fuel supplied to the fuel cell 4 is provided.

  In addition, a battery 17 for supplying electric power to each electric component of the vehicle and a motor for cranking the engine body 2 mainly for starting or starting the engine body 2, that is, a starter motor 18 are provided. Although the kind of the battery 17 is arbitrary, in this embodiment, it is a general lead acid battery. The starter motor 18 appropriately rotates the crankshaft of the engine body 2.

  An air supply path 20 for supplying air to the fuel cell 4 is provided. The air supply path 20 branches from the intake passage 5 on the downstream side of the compressor and is connected to the fuel cell 4. Thereby, the air discharged from the compressor 3C can be supplied to the fuel cell 4, and it is not necessary to provide an air source such as a motor compressor. The branch position A of the air supply path 20 is on the upstream side of the intercooler 8.

  An air supply valve 21 is also provided. The supply valve 21 can be switched so as to guide the discharge air from the compressor 3 </ b> C to one or both of the engine body 2 and the fuel cell 4. In the present embodiment, the air supply valve 21 is configured by a single three-way valve, and is provided at the branch position A of the air supply path 20, that is, at the connection position of the air supply path 20 and the intake passage 5. However, the air supply valve may be composed of at least two two-way valves. In this case, a two-way valve may be provided in each of the supply passage 20 and the intake passage 5 downstream from the branch position A.

  The intake valve 21 is connected to an inlet port connected to the intake passage 5 on the compressor 3C side, a first outlet port connected to the intake passage 5 on the engine body 2 side, and an intake passage 20 on the fuel cell 4 side. A second outlet port to be connected. When the inlet port is connected only to the first outlet port, the air supply valve 21 is in the first position, and the discharge air from the compressor 3C is guided only to the engine body 2 side. When the inlet port is connected only to the second outlet port, the air supply valve 21 is in the second position, and the discharge air from the compressor 3C is guided only to the fuel cell 4 side. When the air supply valve 21 is at an intermediate position between the first position and the second position, the discharge air from the compressor 3C is guided to both the engine body 2 side and the fuel cell 4 side. In this way, the air supply valve 21 can adjust the air flow rate ratio with respect to the engine body 2 and the fuel cell 4 in a stepless manner from 0: 100 (%) to 100: 0 (%).

  Further, an exhaust passage 22 for supplying exhaust gas (referred to as FC exhaust) of the fuel cell 4 to the exhaust manifold 19 is provided. The exhaust path 22 extends from the fuel cell 4 and is connected to the exhaust manifold 19.

  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. The storage device stores various control programs, data, maps, and the like, and the ECU 100 executes various controls by executing these control programs.

  In addition to the air flow meter 7 described above, the ECU 100 receives various signals from the crank angle sensor 31, accelerator opening sensor 32, key switch 33, brake switch 34, vehicle speed sensor 35, FC temperature sensor 36, and other various sensors and switches. input. The ECU 100 controls the aforementioned injector, spark plug, throttle valve 9, waste gate valve 12, cooling water pump 13, lubricating oil pump 14, fuel pump 15, metering valve 16, starter motor 18 and air supply valve 21. Output signals and control them.

  A plurality of electric loads 37 (only one is shown) such as an air conditioner, a headlight, a wiper, and a rear defogger are connected to the ECU 100, and the ECU 100 monitors the operating state of these electric loads 37. The ECU 100 turns on the cooling water pump 13 and the lubricating oil pump 14 while the turbocharger 3 is operating.

  Here, the fuel cell 4 will be described in detail. As is well known, the fuel cell 4 is a power generation device that 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 a fuel electrode (anode), an air electrode (cathode), and an electrolyte sandwiched between these electrodes with a separator interposed therebetween. Yes. The air electrode is substantially supplied with oxygen O ₂ contained in the air sent from the compressor 3C. Hydrogen H ₂ obtained by reforming liquid fuel (in this embodiment, gasoline) is substantially supplied to the fuel electrode. 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 of 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 3T.
(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.

  By the way, in this embodiment, ECU100 performs the following idle stop controls. In general, the idle stop control is a control in which the engine is automatically stopped when a predetermined stop condition is established such that the vehicle is idled and then the engine is automatically restarted when a predetermined release condition is satisfied. is there. When the stop condition is satisfied, the fuel injection in the engine body 2 is stopped, and when the release condition is satisfied, the fuel injection in the engine body 2 is restarted, the starter motor 18 is turned on, and the engine body 2 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 34 or the like).
(2) The accelerator pedal is not depressed (determined by the output of the accelerator opening sensor 32).
(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 35).
(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).

  For example, the release condition is satisfied when at least one of the above conditions (1) to (4) is not satisfied.

  Next, the cooling system of the engine 1 of this embodiment is demonstrated with reference to FIG.

  The cooling system is configured to perform cooling by circulating cooling water as a refrigerant to each part. The cooling system is provided in the engine main body 2, the exhaust manifold 19 and the fuel cell 4 as cooling targets, the cooling water path 40 connected to the engine main body 2, the exhaust manifold 19 and the fuel cell 4, and the cooling water path 40. A water pump 41 that circulates and drives the cooling water, and a radiator 42 that is provided in the cooling water passage 40 and appropriately cools the cooling water.

  In the engine body 2, cooling water is circulated through a water jacket formed inside the cylinder head 2A and the cylinder block 2B, and the cooling water is circulated from the cylinder block 2B to the cylinder head 2A. As can be seen, the exhaust manifold 19 is water-cooled, and a cooling water passage is defined in the wall thickness. The fuel cell 4 also has a cooling water passage therein, and the fuel cell 4 that generates heat during operation is cooled with cooling water. The water pump 41 is electric and has a variable capacity, and is controlled by the ECU 100 (see FIG. 1).

  The cooling water passage 40 starts from the water pump 41, passes through the cylinder block 2B, the cylinder head 2A, the fuel cell 4, the exhaust manifold 19, and the radiator 42 in that order, and returns to the water pump 41. The engine bypass passage 44 connected to the main passage 43 so as to bypass the fuel, the FC bypass passage 45 connected to the main passage 43 so as to bypass the fuel cell 4, and the main passage 43 so as to bypass the radiator 46. And a radiator bypass passage 46 connected thereto.

  The engine bypass passage 44 is branched from the main passage 43 on the downstream side of the water pump 41 and on the upstream side of the cylinder block 2B, and is joined to the main passage 43 on the downstream side of the cylinder head 2A and the upstream side of the fuel cell 4. An engine bypass valve 47 is provided at a branch position of the engine bypass passage 44. The engine bypass valve 47 can be switched to guide the cooling water from the water pump 41 to one of the engine body 2 side (main passage 43 side or non-bypass side) and the fuel cell 4 side (engine bypass passage 44 side or bypass side). It is. The former switching position is referred to as a first position, and the latter switching position is referred to as a second position. Although the engine bypass valve 47 of this embodiment is configured by a single three-way valve, it may be configured by at least two two-way valves, similar to the air supply valve 21. The installation position of the engine bypass valve 47 is also arbitrary.

  The FC bypass passage 45 is branched from the main passage 43 on the downstream side of the cylinder head 2A and on the upstream side of the fuel cell 4 (particularly on the upstream side of the joining position of the engine bypass passage 44), and on the downstream side of the fuel cell 4 and the exhaust manifold 19. To the main passage 43 on the upstream side. An FC bypass valve 48 is provided at a branch position of the FC bypass passage 45. The FC bypass valve 48 can be switched to guide the cooling water from the cylinder head 2A to one of the fuel cell 4 side (main passage 43 side or non-bypass side) and the exhaust manifold 19 side (FC bypass passage 45 side or bypass side). It is. The former switching position is referred to as a first position, and the latter switching position is referred to as a second position. The FC bypass valve 48 of the present embodiment is also configured by a single three-way valve, but may be configured by at least two two-way valves, similar to the air supply valve 21. The installation position of the FC bypass valve 48 is also arbitrary.

  The radiator bypass passage 46 is branched from the main passage 43 at the downstream side of the exhaust manifold 19 and the upstream side of the radiator 46, and is joined to the main passage 43 at the downstream side of the radiator 46 and the upstream side of the water pump 41. A thermostat 49 is provided at a branch position of the radiator bypass passage 46. As is well known, the thermostat 49 is a valve that switches the passage in response to the coolant temperature. The thermostat 49 according to the present embodiment functions like a three-way valve, and supplies cooling water from the exhaust manifold 19 to the radiator 46 side (main passage 43 side or non-bypass side) and the water pump 41 side (radiator bypass passage 46 side or bypass side). Can be switched to lead to one of the two. The former switching position is referred to as a first position, and the latter switching position is referred to as a second position.

  The engine bypass valve 47 and the FC bypass valve 48 are switched and controlled by the ECU 100 (see FIG. 1). The cooling water path 40 is switched according to the switching state of the engine bypass valve 47, the FC bypass valve 48 and the thermostat 49. Therefore, the ECU 100, the engine bypass valve 47, the FC bypass valve 48, and the thermostat 49 constitute a switching unit for switching the cooling water path 40.

  The thermostat 49 switches to the second position when the cooling water temperature is lower than a predetermined temperature (for example, 82 ° C.), and sends the cooling water to the radiator bypass passage 46 and returns it directly to the water pump 41. The thermostat 49 switches to the first position when the cooling water temperature is higher than a predetermined temperature, sends the cooling water to the radiator 42 and cools it, and then returns it to the water pump 41.

  According to the configuration of the cooling system, the cooling water path 40 is connected not only to the engine body 2 and the exhaust manifold 19 but also to the fuel cell 4. Therefore, the cooling system of the fuel cell 4 can be integrated or shared with the cooling system of the engine body 2 or the like, and the cooling system of the fuel cell 4 does not have to be provided separately. As a result, the configuration can be simplified.

  Further, the coolant after passing through the fuel cell 4 can be supplied to the exhaust manifold 19 via the main passage 43. The advantages of this will be described in detail later.

  When the exhaust gas of the fuel cell 4 is supplied to the exhaust manifold 19 as shown in FIG. That is, when the exhaust gas from the fuel cell 4 is supplied to the exhaust manifold 19 while the engine body 2 is stopped and the fuel cell 4 is in operation, moisture contained in the exhaust gas from the fuel cell 4 is condensed in the exhaust manifold 19. However, condensed water may be generated. On the other hand, in the case of the in-line four-cylinder engine as in the present embodiment, there is a cylinder in which the exhaust valve is open while the engine body 2 is stopped. Then, the condensed water in the exhaust manifold 19 may enter the cylinder through the exhaust port of the cylinder. The condensed water can cause oil dilution in the cylinder and can cause water hammer.

  Therefore, in the present embodiment, the ECU 100 switches the cooling water path 40 so as to supply the cooling water after passing through the fuel cell 4 to the exhaust manifold 19 while the engine body 2 is stopped and the fuel cell 4 is operating. Thereby, generation | occurrence | production of the condensed water in the exhaust manifold 19 can be suppressed.

  Hereinafter, this point will be described in detail. First, when the engine body 2 is in operation and the fuel cell 4 is also operating, the ECU 100 switches both the engine bypass valve 47 and the FC bypass valve 48 to the first position as the reference position, that is, the main passage 43 side. Then, the cooling water discharged from the water pump 41 sequentially passes through the cylinder block 2B, the cylinder head 2A, the fuel cell 4, and the exhaust manifold 19. Thereafter, the cooling water passes through the radiator 42 or bypasses the radiator 42 and returns to the water pump 41 depending on the position of the thermostat 49.

  Here, the operation / stop of the fuel cell 4 is controlled by the ECU 100. That is, the ECU 100 operates the fuel cell 4 when there is an operation request for the fuel cell 4 such as when the remaining battery level is less than a predetermined value or when the amount of power consumed by the electric load 37 is greater than a predetermined value. Power generation by the battery 4 is performed. Further, the ECU 100 stops the fuel cell 4 when there is no operation request. Note that the conditions constituting the operation request can be set as appropriate. During operation of the fuel cell 4, the ECU 100 controls the air supply valve 21 and the metering valve 16 so that the amount of air and the amount of fuel supplied to the fuel cell 4 are optimized.

  From this state, it is assumed that only the engine main body 2 is temporarily stopped, particularly due to a request for idle stop control. The fuel cell 4 is still in operation (the same applies to the water pump 41). While the engine body 2 is stopped and the fuel cell 4 is operating, the ECU 100 switches the engine bypass valve 47 and the FC bypass valve 48 to the first position, that is, the main passage 43 side so as to maintain the switching state.

  Then, the cooling water heated to a relatively high temperature by the operating fuel cell 4 is supplied to the exhaust manifold 19 so that the exhaust manifold 19 can be heated or kept warm. Thereby, generation | occurrence | production of the condensed water in the exhaust manifold 19 can be suppressed, and the oil dilution by a condensed water and a water hammer can be suppressed. Even when the engine body 2 is stopped, the cooling water discharged from the operating fuel cell 4 has a temperature of about 80 to 90 ° C., which is sufficient to heat or keep the exhaust manifold 19.

  Here, when the engine body 2 is stopped and the fuel cell 4 is in operation, the exhaust gas from the fuel cell 4 is supplied to the turbine 3T via the exhaust passage 22, the exhaust manifold 19, and the exhaust passage 6 to rotate the turbine 3T. To do. Then, the compressor 3 </ b> C is also rotationally driven, and air from the compressor 3 </ b> C is supplied to the fuel cell 4 through the intake passage 5 and the air supply passage 20. At the same time, the fuel pump 15 is operated, the metering valve 16 is opened, and fuel is also supplied to the fuel cell 4. Thereby, the turbocharger 3 is operated while the engine body 2 (crankshaft) is stopped, and a self-sustaining operation state in which the fuel cell 4 continuously operates and generates power is realized. That is, the self-sustained operation state refers to a state in which the fuel cell continues to operate by rotating the turbine and the compressor with the exhaust gas of the fuel cell so that the air can be supplied to the fuel cell and supplying the fuel together.

  Thus, power generation by the fuel cell 4 can be continuously performed while the engine body 2 is stopped. In addition, since the turbocharger 3 is operated while the engine body 2 is stopped, when the engine body is restarted, especially when the driver depresses the accelerator pedal and starts acceleration at the same time as the release of the idle stop control, the boost pressure is increased. Can rise rapidly and improve turbo response.

  By the way, while the engine main body 2 is stopped, as in the case before the stop (during operation), passing the engine main body 2 through the coolant is not very advantageous for the following reason.

  That is, if the engine main body 2 is passed through the cooling water while the engine main body 2 is stopped, the engine main body 2 is gradually cooled by the cooling water, which is disadvantageous for the next engine start, particularly the engine restart in the idle stop control. is there. This is even more the case when cooling water is passed through the radiator 42. In addition, the cooling water heated from the engine body 2 is supplied to the fuel cell 4, which causes a decrease in the cooling efficiency of the fuel cell 4.

  Therefore, in the present embodiment, while the engine main body 2 is stopped and the fuel cell 4 is operating, the cooling water path 40 is switched so that the cooling water is supplied to the fuel cell 4 by bypassing the engine main body 2. Specifically, the ECU 100 switches the engine bypass valve 47 to the second position, that is, the engine bypass passage 44 side. Then, as shown by arrows in FIG. 3, the cooling water discharged from the water pump 41 is supplied to the fuel cell 4 via the engine bypass passage 44, and the cooling water flows through the engine body 2, and This suppresses cooling of the engine body 2 and temperature rise of the cooling water. Therefore, the next engine start, particularly the engine restart in the idle stop control can be advantageously performed, and the decrease in the cooling efficiency of the fuel cell 4 can be suppressed.

  At this time, the FC bypass valve 48 is maintained at the first position (main passage 43 side) as before the engine main body 2 is stopped. Alternatively, the FC bypass valve 48 is intentionally set to the second position (FC bypass passage 45 side). It may be switched to. In any case, the cooling water after passing through the engine bypass passage 44 does not go to the engine body 2 side and the FC bypass passage 45 side. Although FIG. 3 shows an example in which the cooling water passes through the radiator 42, an example in which the cooling water is bypassed without passing through the radiator 42 is naturally possible.

  Next, preferable control of the present embodiment will be described with reference to FIG. The routine shown in FIG. 4 is repeatedly executed by the ECU 100 at every predetermined calculation cycle.

  In step S101, it is determined whether the engine body 2 is stopped and the fuel cell 4 is operating. If no, the process proceeds to step S104, and if yes, the process proceeds to step S102.

  In step S104, the engine bypass valve 47 is switched to the first position, that is, the main passage 43 side (non-bypass side). The routine is then terminated.

  In step S102, it is determined whether an engine bypass condition, which is a precondition for switching the engine bypass valve 47 to the second position, is satisfied. This engine bypass condition is satisfied, for example, when the stop time of the engine main body 2 becomes a predetermined time or longer. If the stop time of the engine main body 2 is prolonged, the temperature of the engine main body 2 is lowered, which is disadvantageous for the next start, and the cooling water temperature is increased, so that the cooling efficiency of the fuel cell 4 is also lowered. Therefore, a predetermined time is set from the viewpoint of startability and cooling efficiency.

  When step S102 is NO, the process proceeds to step S104, and the engine bypass valve 47 is switched to the first position. That is, the engine bypass valve 47 is maintained at the first position before the stop time of the engine main body 2 reaches a predetermined time or longer.

  When step S102 is YES, the process proceeds to step S103, and the engine bypass valve 47 is switched to the second position, that is, the engine bypass passage 44 side (bypass side). The routine is then terminated. As described above, when the stop time of the engine main body 2 becomes a predetermined time or more, the engine bypass valve 47 is switched to the second position.

  Note that, regardless of whether the engine bypass valve 47 is in the first position or the second position, the relatively high-temperature cooling water discharged from the fuel cell 4 is supplied to the exhaust manifold 19, so that the heating effect of the exhaust manifold 19 is achieved. Or the heat retention effect is achieved and the generation of condensed water can be suppressed.

  During execution of this control, the FC bypass valve 48 is maintained at the first position (on the main passage 43 side).

[Second Embodiment]
Next, a second embodiment of the present invention will be described. The description of the same parts as those in the first embodiment will be omitted, and the differences will be mainly described below.

  In the second embodiment, the operation of the FC bypass valve 48 is generally added to the first embodiment. That is, if the fuel cell 4 is passed through the coolant while the engine body 2 is stopped and the fuel cell 4 is stopped, the fuel cell 4 is gradually cooled with the coolant, and the next start of the fuel cell 4 is performed. Disadvantageous. This is even more the case when cooling water is passed through the radiator 42.

  Therefore, in the present embodiment, when the engine body 2 is stopped and the fuel cell 4 is stopped, the cooling water path 40 is switched so that the cooling water is supplied to the exhaust manifold 19 by bypassing the fuel cell 4. Specifically, the ECU 100 switches the FC bypass valve 48 to the second position, that is, the FC bypass passage 45 side. Then, as indicated by arrows in FIG. 5, the cooling water is supplied to the exhaust manifold 19 via the FC bypass passage 45, and the cooling water flows through the fuel cell 4 and the cooling of the fuel cell 4 thereby. Is suppressed. Therefore, the next start-up of the fuel cell 4 can be advantageously performed.

  Although FIG. 5 shows an example in which the cooling water passes through the radiator 42, an example of bypassing without passing through the radiator 42 is naturally possible.

  A preferred control of this embodiment will be described with reference to FIG. The routine shown in FIG. 6 is repeatedly executed by the ECU 100 at every predetermined calculation cycle.

  In step S201, it is determined whether or not the engine body 2 is stopped. If no, the process proceeds to step S211 and the engine bypass valve 47 is switched to the first position (non-bypass side). In step S212, the FC bypass valve 48 is switched to the first position (non-bypass side). Is terminated.

  When step S201 is YES, it progresses to step S202 and it is determined whether the fuel cell 4 is operating.

  In the case of yes, steps S203 to S205 are executed. These steps are the same as steps S102 to S104. After either step S204 or S205 is executed, the FC bypass valve 48 is switched to the first position (non-bypass side) in step S206, and the routine is terminated.

  If step S202 is NO, it means that the fuel cell 4 is stopped. At this time, the routine proceeds to step S207, where it is determined whether an FC bypass condition, which is a precondition for switching the FC bypass valve 48 to the second position (bypass side), is satisfied. This FC bypass condition is satisfied, for example, when the temperature of the fuel cell 4 (particularly the temperature of the cell stack) detected by the FC temperature sensor 36 (see FIG. 1) is below a predetermined temperature. If the temperature of the fuel cell 4 is too low, it is disadvantageous for the next start-up, and therefore an optimum predetermined temperature is set in consideration of this restartability. The predetermined temperature can be set to a temperature (for example, 500 ° C.) slightly higher than the lowest operating temperature (for example, 450 ° C.) of the fuel cell 4, for example.

  When step S207 is NO, the process proceeds to step S209, and the FC bypass valve 48 is switched to the first position (non-bypass side). That is, when the temperature of the fuel cell 4 is higher than the predetermined temperature, the FC bypass valve 48 is maintained at the first position.

  If step S207 is YES, the process proceeds to step S208, and the FC bypass valve 48 is switched to the second position (bypass side). The routine is then terminated. Thus, when the temperature of the fuel cell 4 becomes equal to or lower than the predetermined temperature, the FC bypass valve 48 is switched to the second position, and the temperature drop of the fuel cell 4 is suppressed.

  After either step S208 or S209 is executed, the engine bypass valve 47 is switched to the first position (non-bypass side) in step S210, and the routine is terminated.

  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. The present invention is also applicable to an internal combustion engine and a vehicle without idle stop control. That is, the engine main body does not have to be stopped by idle stop control. For example, the present invention can be applied to the case where the driver sets the key switch to the accessory-on position while the engine body is stopped, uses an electric load (such as an air conditioner), and the fuel cell is activated during this time. The above numerical values are merely examples and can be changed.

  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 3 Turbocharger 3C Compressor 3T Turbine 4 Fuel cell 5 Intake passage 6 Exhaust passage 19 Exhaust manifold 22 Exhaust passage 36 FC temperature sensor 40 Cooling water passage 43 Main passage 44 Engine bypass passage 45 FC bypass passage 47 Engine bypass valve 48 FC Bypass valve 100 Electronic control unit (ECU)

Claims (6)

Turbocharger,
An exhaust manifold disposed upstream of the turbocharger turbine;
A fuel cell;
An exhaust passage for supplying exhaust gas of the fuel cell to the exhaust manifold;
A cooling water path connected to the engine body, the exhaust manifold and the fuel cell;
Switching means for switching the cooling water path, wherein the cooling water after passing through the fuel cell is supplied to the exhaust manifold while the engine body is stopped and the fuel cell is operating. Switching means for switching the cooling water path;
An internal combustion engine comprising: The switching means switches the cooling water path so that the cooling water is supplied to the fuel cell by bypassing the engine main body while the engine main body is stopped and the fuel cell is operating. The internal combustion engine according to claim 1. The internal combustion engine according to claim 2, wherein the switching means switches the cooling water path so as to bypass the engine body when a stop time of the engine body reaches a predetermined time or longer. The switching means switches the cooling water path so that the cooling water is supplied to the exhaust manifold by bypassing the fuel cell while the engine body is stopped and the fuel cell is stopped. The internal combustion engine according to any one of claims 1 to 3. 5. The internal combustion engine according to claim 4, wherein the switching unit switches the cooling water path so as to bypass the fuel cell when the temperature of the fuel cell becomes equal to or lower than a predetermined temperature. The internal combustion engine according to any one of claims 1 to 5, wherein the stop of the engine body is executed by idle stop control.

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