Fuel reforming system

Abstract

To provide a fuel reforming system enabling efficient generation of hydrogen gas and suitable for mounting to a vehicle.SOLUTION: A fuel reforming system 1 for a vehicle mounted with a reciprocal engine 3 includes a decomposition device 6 that decomposes hydrocarbon fuel into carbon and hydrogen gas by using heat and pressure of combustion gas Gb and a catalyst 66b and holds carbon, etc. The decomposition device 6 communicates with a combustion chamber 3a via a third port 37 that can be opened / closed. A reforming space 62 in which a reforming member 66 with the catalyst 66b is incorporated is provided on a side of a connection portion with the third port 37 in the decomposition device 6. An additional space 63 that stores residual gas Gr remaining in the third port 37 and the decomposition device 6 when the combustion gas Gb is introduced through the third port 37 is provided in an inner part of the decomposition device 6 on the side opposite to the connection portion with the third port 37.SELECTED DRAWING: Figure 8B

Description

[Technical Field]

[0001] The disclosed technology relates to a fuel reforming system for a vehicle equipped with a reciprocating engine. [Background technology]

[0002] Patent Document 1 describes an apparatus (cracker) that directly decomposes hydrocarbons into carbon and hydrogen. This decomposition apparatus includes a reactor that houses a catalyst. When a raw material gas containing hydrocarbons is supplied to the reactor, carbon produced by a catalytic reaction adheres to the catalyst. A reaction gas containing hydrogen passes through the reactor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-104521 Summary of the Invention [Problem to be solved by the invention]

[0004] Carbon neutral initiatives are being sought in the field of vehicle technology (for example, four-wheeled automobiles). To achieve carbon neutrality in vehicles equipped with engines that use hydrocarbon fuels (including gasoline and / or diesel), new technologies for recovering carbon (C) or carbon dioxide (CO2) from hydrocarbon fuels are required, in addition to improving the thermal efficiency of the engine and / or improving exhaust emission performance.

[0005] If you want to capture carbon or carbon dioxide in a vehicle equipped with an engine that uses hydrocarbon fuel, (1) capturing carbon dioxide after the combustion of hydrocarbon fuels; or (2) Decomposing the hydrocarbon fuel into carbon and hydrogen gas before combustion of the hydrocarbon fuel, and recovering the carbon; It is possible that...

[0006] Considering that the captured carbon dioxide or carbon will be stored in the vehicle, option (2) is more advantageous in terms of fuel efficiency because carbon dioxide is heavier than carbon. Also, option (2) allows hydrogen gas to be used as engine fuel. Combustion of hydrogen gas has the added advantage of not producing carbon oxides due to combustion.

[0007] Therefore, it is conceivable to mount the above-mentioned cracking device on a vehicle. The cracking device is equipped with a heating device for raising the temperature of the catalyst. Therefore, when the cracking device is mounted on a vehicle, it is possible to use the heat of the combustion gas from the engine to raise the temperature of the catalyst and the hydrocarbon fuel.

[0008] However, in order to efficiently generate hydrogen gas in a cracking device, it is necessary to bring heated hydrocarbon fuel into contact with a heated catalyst to promote the reforming reaction, and therefore it is necessary to distribute the hydrocarbon fuel over the entire catalyst.

[0009] On the other hand, when hydrocarbon fuel is decomposed into hydrogen gas and carbon in a cracker and the hydrogen gas is removed from the cracker, residual gas containing impurities such as nitrogen remains inside the cracker along with the carbon. This residual gas prevents the hydrocarbon fuel from coming into contact with the catalyst. Therefore, the residual gas interferes with the reforming reaction.

[0010] The same goes for carbon. If there is too much carbon inside the cracker, it will interfere with the reforming reaction. Therefore, if there is too much carbon, it needs to be removed from the cracker.

[0011] The technology disclosed herein provides a fuel reforming system suitable for on-board use in a vehicle that enables efficient production of hydrogen gas. [Means for solving the problem]

[0012] The disclosed technology relates to a fuel reforming system for a vehicle equipped with a reciprocating engine in which a combustion chamber in which combustion takes place is defined inside a cylinder in which a piston reciprocates.

[0013] The fuel reforming system includes a cracker that uses the heat and pressure of the combustion gas generated in the combustion chamber and a catalyst to decompose hydrocarbon fuel into carbon and hydrogen gas and retain the carbon, and a hydrocarbon fuel supply unit that supplies the hydrocarbon fuel to the cracker.

[0014] The cracker is in communication with the combustion chamber via an openable / closable port. A reforming space containing a reforming member including the catalyst is provided on the side of the cracker where the cracker is connected to the port. An additional space is provided adjacent to the reforming space on the side of the cracker opposite the side where the cracker is connected to the port, for accommodating residual gas remaining in the port and inside the cracker when the combustion gas is introduced into the cracker through the port.

[0015] This fuel reforming system utilizes the functions of a reciprocating engine, using the heat and pressure of the combustion gas generated in the combustion chamber and a catalyst to decompose hydrocarbon fuel into carbon and hydrogen gas. Therefore, this fuel reforming system can generate hydrogen gas with simple equipment, making it suitable for use in vehicles.

[0016] The hydrogen gas produced can be used as fuel for a reciprocating engine, and the carbon produced is retained by the cracker, making the process carbon-neutral.

[0017] The cracker is provided with a reforming space containing a catalyst-containing reforming member on the combustion gas inlet side. That is, the reforming reaction that produces hydrogen gas occurs in the reforming space. On the opposite side of the cracker, an additional space is provided adjacent to the reforming space to accommodate the port and residual gas remaining inside the cracker when the combustion gas is introduced into the cracker.

[0018] When combustion gas is introduced into the cracker through the ports, the residual gas remaining in the cracker is pushed deeper into the cracker, forming a mass of residual gas deep inside the cracker. Residual gas is cooler than combustion gas and does not contain hydrocarbon fuel. However, it contains a large amount of inert gas. In other words, reforming reactions do not occur in areas where residual gas masses exist.

[0019] In contrast, this fuel reforming system can accommodate the residual gas mass in the additional space, allowing the high-temperature, high-pressure combustion gas to be distributed evenly throughout the reforming space. This allows hydrogen gas to be produced efficiently without wasting hydrocarbon fuel.

[0020] The fuel reforming system may further include a capacity variable mechanism that varies the capacity of the additional space, and the capacity of the additional space may be varied depending on the operating state of the reciprocating engine.

[0021] Generally, the higher the load on a reciprocating engine, the greater the combustion energy required. Therefore, the higher the load on a reciprocating engine, the higher the pressure (temperature) of the combustion gas. Therefore, the difference (differential pressure) between the pressure of the residual gas remaining in the port and cracker and the pressure of the combustion gas introduced from the combustion chamber into the cracker is large when the load on the reciprocating engine is high and small when the load on the reciprocating engine is low.

[0022] A small differential pressure results in a larger residual gas mass. On the other hand, a large differential pressure results in a smaller residual gas mass because it is more compressed. Therefore, as the load on a reciprocating engine changes, the optimum volume of the additional space also changes.

[0023] In contrast, this fuel reforming system is configured so that the capacity of the additional space can be varied according to the operating state of the reciprocating engine, making it possible to change the capacity of the additional space and maintain it at an optimum state.

[0024] The fuel reforming system may also be configured such that the carbon is held in the decomposer in a state in which it can be separated, and an openable and closable discharge passage is connected to the additional space, so that the carbon separated from the decomposer can be discharged through the discharge passage.

[0025] The carbon produced in the reforming reaction adheres to the catalyst. Therefore, as the amount of carbon buildup increases, the cracker's cracking performance deteriorates. Therefore, in order to maintain the cracker's cracking performance, it is necessary to remove carbon from the cracker once it has accumulated to a certain extent.

[0026] In contrast, this fuel reforming system is configured so that an exhaust passage is connected to the additional space, and the carbon separated from the cracker can be discharged through the exhaust passage. Therefore, carbon that accumulates in the cracker can be automatically removed as needed. This restores the hydrogen gas yield and maintains the cracking capacity of the cracker.

[0027] The fuel reforming system may also be configured such that the reciprocating engine executes a six-stroke cycle consisting of an intake stroke in which at least intake air is introduced into the combustion chamber through an intake port as the piston descends, a compression stroke in which the mixture containing the hydrogen gas supplied to the combustion chamber is compressed as the piston rises, an expansion stroke in which the piston descends as the mixture is burned, a recompression stroke in which the combustion gas is compressed as the piston rises, a re-expansion stroke in which the piston descends, and an exhaust stroke in which exhaust gas is discharged through an exhaust port as the piston rises, and in the recompression stroke, the combustion gas is introduced into the cracker through the port, thereby forcing the residual gas into the additional space and storing it.

[0028] During the recompression stroke, the combustion gas in the combustion chamber is pressurized by the rising piston. This gas is then introduced into the cracker, increasing the internal pressure of the cracker. As a result, the residual gas also contracts, reducing its volume. This allows the optimum volume of additional space to be reduced, allowing the cracker to be made more compact. [Effects of the Invention]

[0029] The disclosed technology makes it possible to efficiently generate hydrogen gas by utilizing the functions of a reciprocating engine, thereby realizing a fuel reforming system suitable for installation in a vehicle. [Brief explanation of the drawings]

[0030] [Figure 1] 1 is a schematic diagram of a fuel reforming system. [Figure 2] FIG. 2 is a block diagram of a control system. [Figure 3] FIG. 1 is a diagram for explaining a six-stroke cycle. [Figure 4] 10 is an example of the operation of each valve, the injection timing of the reformed fuel, and the change in the internal pressure of the cracker. [Figure 5] 1 is an example of a control map. [Figure 6] FIG. 2 is a schematic diagram for explaining the structure of a decomposer. [Figure 7] FIG. 2 is a simplified diagram for explaining the function of a decomposer. [Figure 8A] FIG. 1 is a diagram for explaining a structural problem of a cracker (comparative example). [Figure 8B] FIG. 1 is a diagram for explaining a structural problem of a cracker (Example). [Figure 9] FIG. 3 is a simplified diagram for explaining a second fuel reforming system. [Figure 10] FIG. 10 is a simplified diagram for explaining a third fuel reforming system. [Figure 11A] 10 is a flowchart of control by the third fuel reforming system. [Figure 11B] 10 is a flowchart of control by the third fuel reforming system. DETAILED DESCRIPTION OF THE INVENTION

[0031] The disclosed technology will be described below, however, the following description is merely exemplary in nature.

[0032] (Configuration of fuel reforming system) FIG. 1 shows a fuel reforming system 1 mounted on a vehicle. A hydrocarbon fuel is stored in a fuel tank mounted on the vehicle. The hydrocarbon fuel is, for example, gasoline. The hydrocarbon fuel is not limited to gasoline. The fuel reforming system 1 decomposes the hydrocarbon fuel into carbon and hydrogen gas. The carbon is stored in a decomposer 6, which will be described later. The hydrogen gas is used as fuel for a reciprocating engine 3. The fuel reforming system 1 achieves carbon neutrality for vehicles that are equipped with hydrocarbon fuel.

[0033] The fuel reforming system 1 includes a reciprocating engine 3 (hereinafter simply referred to as the engine 3). The engine 3 includes a cylinder 31 and a piston 32 that reciprocates within the cylinder 31. A combustion chamber 3a is formed at the upper end of the cylinder 31, the lower surface of which is partitioned by the piston 32. The engine 3 includes a plurality of cylinders 31.

[0034] The multiple cylinders 31 are aligned, for example, in the direction in which the crankshaft of the engine 3 extends. The pistons 32 of each cylinder 31 are connected to the crankshaft via connecting rods. The connecting rods convert the reciprocating motion of the pistons 32 into rotation of the crankshaft. The crankshaft is connected to the drive wheels via a transmission. The engine 3 outputs driving force for running the vehicle.

[0035] The engine 3 has an intake port 33. The intake port 33 is connected to the upper part of the cylinder 31, i.e., to the combustion chamber 3a. Each cylinder 31 has one or more intake ports 33. Each cylinder 31 may have, for example, two intake ports 33. The intake port 33 is connected to an intake pipe. As will be described later, intake air is introduced into the combustion chamber 3a through the intake port 33. The intake air includes at least fresh air (outside air). The intake air may also include EGR (Exhaust Gas Recirculation) gas.

[0036] The engine 3 has an intake valve 34. The intake valve 34 is a poppet valve that opens and closes the intake port 33. When the intake valve 34 opens, intake air is introduced into the combustion chamber 3a. An intake valve train 41 shown in FIG. 2 opens and closes the intake valve 34. The intake valve train 41 has, for example, an intake camshaft mechanically connected to the intake valve 34.

[0037] The intake valve train 41 can continuously change the valve timing of the intake valve 34 (so-called S-VT (Sequential-Valve Timing)). The intake valve train 41 can also continuously change the valve lift of the intake valve 34 (so-called CVVL (Continuously Variable Valve Lift)). The intake valve train 41 can employ a known hydraulic or electric mechanism. The intake valve train 41 changes the valve timing and / or valve lift depending on the operating state of the engine 3.

[0038] The engine 3 has an exhaust port 35. The exhaust port 35 is connected to the combustion chamber 3a. Each cylinder 31 has one or more exhaust ports 35. Each cylinder 31 may have, for example, one exhaust port 35. The exhaust port 35 is connected to an exhaust pipe. As will be described later, exhaust gas is discharged from the combustion chamber 3a through the exhaust port 35.

[0039] The engine 3 has an exhaust valve 36. The exhaust valve 36 is a poppet valve that opens and closes the exhaust port 35. When the exhaust valve 36 opens, exhaust gas is discharged to the outside of the cylinder 31. An exhaust valve train 42 shown in FIG. 2 opens and closes the exhaust valve 36. The exhaust valve train 42 has, for example, an exhaust camshaft mechanically connected to the exhaust valve 36.

[0040] The exhaust valve train 42 can continuously change the valve timing of the exhaust valve 36 (so-called S-VT). The exhaust valve train 42 can also continuously change the valve lift of the exhaust valve 36 (so-called CVVL). A known hydraulic or electric mechanism can be used for the exhaust valve train 42. The exhaust valve train 42 changes the valve timing and / or valve lift according to the operating state of the engine 3.

[0041] The engine 3 has a third port 37. In this embodiment, the third port 37 corresponds to the "port" in the disclosed technology. The third port 37 is in communication with the combustion chamber 3a. Each cylinder 31 has at least one third port 37. Each cylinder 31 may have, for example, one third port 37.

[0042] A typical engine 3 has two intake ports and two exhaust ports per cylinder 31. The engine 3 in Fig. 1 has two intake ports 33, one exhaust port 35, and one third port 37 per cylinder 31. For ease of understanding, Fig. 1 depicts the exhaust port 35 and the third port 37 at different positions.

[0043] The engine 3 has an on-off valve 38. The on-off valve 38 is a poppet valve that opens and closes a third port 37. A third valve train 43 shown in FIG. 2 opens and closes the on-off valve 38. The third valve train 43 has, for example, a third camshaft mechanically connected to the on-off valve 38. The third valve train 43 opens the on-off valve 38 twice during one cycle.

[0044] The third valve train 43 can also stop the opening and closing of the on-off valve 38. A known hydraulic or electric mechanism can be used as the valve stopping mechanism that stops the opening and closing of the on-off valve 38. The valve stopping mechanism may be incorporated, for example, into a rocker arm interposed between the third camshaft and the on-off valve 38. The valve stopping mechanism may also be incorporated into a lash adjuster that supports the rocker arm. The on-off valve 38 may be mechanically connected to the intake camshaft or the exhaust camshaft.

[0045] An intake port injector 44 is attached to the engine 3. An injection hole of the intake port injector 44 faces the inside of the intake port 33. The intake port injector 44 injects hydrocarbon fuel as fuel into the inside of the intake port 33. A hydrocarbon fuel supply unit 45 is connected to the intake port injector 44. The hydrocarbon fuel supply unit 45 has a fuel tank that stores hydrocarbon fuel and a fuel pump that pressure-feeds the hydrocarbon fuel.

[0046] A third port injector 46 is attached to the engine 3. An injection hole of the third port injector 46 faces the inside of the third port 37. The third port injector 46 injects hydrocarbon fuel as fuel for reforming (reformed fuel) into the inside of the third port 37. The hydrocarbon fuel supply unit 45 is also connected to the third port injector 46.

[0047] As a result, the hydrocarbon fuel supply unit 45 supplies hydrocarbon fuel to the intake port injector 44 and the third port injector 46 .

[0048] A hydrogen injector 47 is attached to the engine 3. The injection hole of the hydrogen injector 47 faces the combustion chamber 3a. The hydrogen injector 47 injects hydrogen gas into the combustion chamber 3a.

[0049] It is also possible to attach an injector that injects hydrocarbon fuel to the engine 3 so as to face the combustion chamber 3a, and attach a hydrogen injector that injects hydrogen gas to the engine 3 so as to face the inside of the intake port 33.

[0050] The cracker 6 is connected to the third port 37. The cracker 6 is in communication with the combustion chamber 3a via the third port 37. The cracker 6 decomposes the hydrocarbon fuel into carbon and hydrogen gas. A cracker 6 is attached to each cylinder 31. The cracker 6 may be common to multiple cylinders 31.

[0051] The cracker 6 uses the heat and pressure of the combustion gas generated in the combustion chamber 3a and a catalyst to decompose the hydrocarbon fuel into carbon and hydrogen gas. The cracker 6 is a so-called membrane reactor that performs a reforming reaction. The decomposition of a hydrocarbon fuel, for example, isooctane, is expressed by the following chemical reaction formula:

[0052] iC8H18(g) = 8C(s) + 9H2

[0053] The generated hydrogen gas is then extracted from the cracker 6. The generated carbon is retained inside the cracker 6. Collecting the solid carbon prevents an increase in the vehicle weight. The fuel reforming system 1 is suitable as an on-board system. The cracker 6 will be described in detail later.

[0054] The cracker 6 is connected to a hydrogen gas supply unit 5. The hydrogen gas generated in the cracker 6 is sent to the hydrogen gas supply unit 5. The hydrogen gas supply unit 5 includes a gas tank for storing hydrogen gas, an on-off valve for controlling the flow of hydrogen gas into and out of the gas tank, and the like. The hydrogen gas supply unit 5 is also connected to a hydrogen injector 47.

[0055] The hydrogen gas supply unit 5 supplies hydrogen gas to the hydrogen injector 47. This hydrogen gas is hydrogen gas decomposed from hydrocarbon fuel. That is, in this fuel reforming system 1, hydrogen gas obtained by removing carbon from hydrocarbon fuel is reused as fuel.

[0056] (Controller) Figure 2 shows a block diagram of the control system 2 installed in the vehicle. The fuel reforming system 1 cooperates with this control system 2. The fuel reforming system 1 and the control system 2 share devices as necessary. The control system 2 has a controller 21. The controller 21 is composed of hardware such as a processor, memory, and interface, and software such as a database and control program.

[0057] The rotation speed sensor 22 is electrically connected to the controller 21. The rotation speed sensor 22 is attached to the engine 3. The rotation speed sensor 22 outputs a measurement signal corresponding to the rotation speed of the crankshaft to the controller 21. The controller 21 obtains the rotation speed of the engine 3 based on the measurement signal of the rotation speed sensor 22.

[0058] The accelerator sensor 23 is electrically connected to the controller 21. The accelerator sensor 23 is attached to an accelerator pedal. The accelerator sensor 23 outputs a signal corresponding to the depression amount of the accelerator pedal to the controller 21. The controller 21 obtains the required load of the engine 3 based on the measurement signal of the accelerator sensor 23.

[0059] The crank angle sensor 24 is electrically connected to the controller 21. The crank angle sensor 24 is attached to the engine 3. The crank angle sensor 24 outputs a signal corresponding to the angle of the crankshaft to the controller 21. The controller 21 obtains the position of the piston 32 in each cylinder 31 based on the signal from the crank angle sensor 24.

[0060] The hydrogen gas sensor 25 is attached to the cracker 6. The hydrogen gas sensor 25 measures the amount of hydrogen gas produced in the cracker 6. The controller 21 outputs a control signal to the hydrogen gas sensor 25. Based on the control signal from the controller 21, the hydrogen gas sensor 25 outputs a signal corresponding to the amount of hydrogen gas (hydrogen gas concentration) to the controller 21. The controller 21 determines the degree of performance degradation of the cracker 6 based on the signal from the hydrogen gas sensor 25.

[0061] The intake valve train 41, exhaust valve train 42, and third valve train 43 described above are each electrically connected to the controller 21. The controller 21 outputs a control signal to each of the intake valve train 41, exhaust valve train 42, and third valve train 43 depending on the operating state of the engine 3. The intake valve train 41 changes the valve timing and / or valve lift of the intake valve 34 based on the control signal from the controller 21. The exhaust valve train 42 changes the valve timing and / or valve lift of the exhaust valve 36 based on the control signal from the controller 21. The third valve train 43 switches the on-off valve 38 between open and closed states based on the control signal from the controller 21.

[0062] The intake port injector 44, the third port injector 46, and the hydrogen injector 47 are each electrically connected to the controller 21. The controller 21 outputs a control signal to each of the intake port injector 44, the third port injector 46, and the hydrogen injector 47. The intake port injector 44 injects a predetermined amount of hydrocarbon fuel into the intake port 33 at a predetermined timing based on the control signal from the controller 21. The third port injector 46 injects a predetermined amount of hydrocarbon fuel into the third port 37 at a predetermined timing based on the control signal from the controller 21. The hydrogen injector 47 injects a predetermined amount of hydrogen gas into the combustion chamber 3a at a predetermined timing based on the control signal from the controller 21.

[0063] The control system 2 has an ignition plug 27. The ignition plug 27 is attached to the engine 3 and faces the combustion chamber 3a. The ignition plug 27 is electrically connected to the controller 21. The controller 21 outputs a control signal to the ignition plug 27. The ignition plug 27 ignites the air-fuel mixture in the combustion chamber 3a at a predetermined timing based on the control signal from the controller 21.

[0064] The control system 2 may include an inverter 28. In this case, the vehicle has a drive motor (assist motor) that outputs driving force for running the vehicle. The inverter 28 controls the drive motor. The inverter 28 is electrically connected to the controller 21. When the output of the engine 3 is insufficient, the controller 21 outputs a control signal to the inverter 28. This activates the drive motor to assist the operation of the engine 3.

[0065] The control system 2 may also have a sliding device 70 (an example of a variable capacity mechanism). In this case, the sliding device 70 is electrically connected to the controller 21. The controller 21 outputs a control signal to the sliding device 70. The sliding device 70 moves a slider, which will be described later, based on the control signal from the controller 21.

[0066] The control system 2 may also include a carbon removal device 80. In this case, the carbon removal device 80 is electrically connected to the controller 21. The controller 21 outputs a control signal to the carbon removal device 80, which activates or stops the carbon removal device 80. Note that the inverter 28, the slide device 70, and the carbon removal device 80 are related to another embodiment of the fuel reforming system 1, which will be described later. Therefore, these will be described separately below.

[0067] (Reciprocating engine operation) The engine 3 of this embodiment executes a six-stroke cycle in order for the cracker 6 to crack hydrocarbon fuel. Figure 3 shows each stroke of the cycle. Figure 4 shows an example of the valve timing and valve lift of each valve, the injection timing of the third port injector 46, and changes in the internal pressure of the cracker 6 during the six-stroke cycle.

[0068] S1 is the intake stroke. During the intake stroke S1, the engine 3 introduces intake air into the combustion chamber 3a as the piston 32 descends. During the intake stroke S1, the intake valve 34 opens. The intake air is introduced into the combustion chamber 3a through the intake port 33. The intake air includes at least fresh air.

[0069] The intake air may contain EGR gas. This EGR gas is so-called external EGR gas that has been recirculated to the intake pipe through the EGR passage. During the intake stroke S1, the exhaust valve 36 may open. When the exhaust valve 36 opens, exhaust gas is introduced into the combustion chamber 3a through the exhaust port 35. The exhaust gas introduced into the combustion chamber 3a is so-called internal EGR gas. Note that the opening / closing valve 38 of the third port 37 is closed.

[0070] 3, the hydrogen injector 47 injects hydrogen gas into the combustion chamber 3a during the intake stroke S1. The hydrogen injector 47 may inject hydrogen gas during the compression stroke S2 ​​following the intake stroke S1. The hydrogen injector 47 may inject hydrogen gas during the period from the intake stroke S1 to the compression stroke S2.

[0071] If there is a shortage of hydrogen gas, the intake port injector 44 may inject hydrocarbon fuel into the intake port 33 during the intake stroke S1 to make up for the shortage. Also, if there is no hydrogen gas, the intake port injector 44 may inject hydrocarbon fuel into the intake port 33 during the intake stroke S1 instead of the hydrogen injector 47.

[0072] When there is a shortage of hydrogen gas supplied to the combustion chamber 3a, the intake port injector 44 injects hydrocarbon fuel to ensure the required amount of fuel for the engine 3. The engine 3 can be operated using hydrocarbon fuel or both hydrocarbon fuel and hydrogen gas.

[0073] S2 is the compression stroke. During the compression stroke S2, the engine 3 compresses the air-fuel mixture in the combustion chamber 3a by the upward movement of the piston 32. The intake valve 34, the exhaust valve 36, and the on-off valve 38 are all closed.

[0074] The spark plug 27 ignites the air-fuel mixture in the combustion chamber 3a near the top dead center of the compression stroke. The air-fuel mixture begins to burn. S3 is the expansion stroke. During the expansion stroke S3, the piston 32 descends due to the combustion of the air-fuel mixture. The intake valve 34, exhaust valve 36, and on-off valve 38 are all closed.

[0075] S4 is a recompression stroke. In the recompression stroke S4, the engine 3 compresses the combustion gas in the combustion chamber 3a by raising the piston 32. In the recompression stroke S4, the on-off valve 38 opens. The compressed combustion gas is introduced into the cracker 6 through the third port 37.

[0076] Furthermore, in the recompression stroke S4, the third port injector 46 injects hydrocarbon fuel into the third port 37. In detail, as indicated by symbol F1 in Fig. 4, the third port injector 46 injects reformed fuel in the latter half of the recompression stroke S4.

[0077] The later the recompression stroke S4, the higher the pressure of the combustion gas. Therefore, the internal pressure of the cracker 6 is also maintained high during the latter half of the recompression stroke S4. Furthermore, high-pressure combustion gas flows in during the latter half of the recompression stroke S4. In this state, hydrocarbon fuel is injected toward the third port 37, so the hydrocarbon fuel can be effectively dispersed into the combustion gas even if the third port 37 is narrow.

[0078] Then, the high-temperature, high-pressure combustion gas in which the hydrocarbon fuel is homogenized is introduced into the cracker 6 .

[0079] As described above, in the cracker 6, the hydrocarbon fuel is cracked into carbon and hydrogen gas by utilizing the heat and pressure of the combustion gas and the catalyst. Because the hydrocarbon fuel is homogenized, it can come into contact with the catalyst efficiently. The high temperature and pressure promote the reforming reaction. Therefore, hydrogen gas can be produced effectively.

[0080] Because the high pressure of the combustion gas in the recompression stroke S4 is applied to the inside of the cracker 6, the hydrogen gas generated inside the cracker 6 is quickly sent to the hydrogen gas supply unit 5. Because the amount of hydrogen gas inside the cracker 6 is reduced, the cracking reaction of the hydrocarbon fuel is promoted. The cracker 6, which utilizes the pressure of the recompression stroke S4 of the engine 3, can generate a relatively large amount of hydrogen gas even though it is small. The generated carbon is stored in the cracker 6.

[0081] S5 is the re-expansion stroke. In the re-expansion stroke S5, the piston 32 descends. The on-off valve 38 opens in the re-expansion stroke S5. When the on-off valve 38 opens, some of the residual gas remaining inside the cracker 6 is discharged from the cracker 6 to the combustion chamber 3a. Since the inside of the cracker 6 can be scavenged, high-temperature combustion gas can be guided to the third port 37 again in the next cycle. Opening the on-off valve 38 in the re-expansion stroke S5 is advantageous in reducing pumping losses of the engine 3.

[0082] S6 is the exhaust stroke. During the exhaust stroke S6, the engine 3 discharges the combustion gas in the combustion chamber 3a through the exhaust port 35 as the piston 32 rises. During the exhaust stroke S6, the exhaust valve 36 opens. The combustion gas in the combustion chamber 3a is discharged to the exhaust port 35. During the exhaust stroke S6, the intake valve 34 and the on-off valve 38 are closed.

[0083] After the exhaust stroke S6, the engine 3 returns to the intake stroke S1.

[0084] Instead of or together with opening the on-off valve 38 in the re-expansion stroke S5, the on-off valve 38 may be opened in the intake stroke S1. If the on-off valve 38 is opened in the intake stroke S1, the residual gas can be discharged from the cracker 6 to the combustion chamber 3a. The combustion gas becomes EGR gas.

[0085] If the on-off valve 38 does not open in the re-expansion stroke S5, the hydrocarbon fuel introduced into the cracker 6 in the re-compression stroke S4 will remain in the cracker 6 for a long time, which has the advantage of promoting the cracking reaction of the hydrocarbon fuel.

[0086] The fuel reforming system 1 stores the carbon produced by the decomposition of hydrocarbon fuel in the cracker 6. The engine 3 then burns the hydrogen gas produced by the decomposition of hydrocarbon fuel, so no carbon oxides are produced by combustion. The fuel reforming system 1 can achieve carbon neutrality.

[0087] The fuel reforming system 1 also decomposes hydrocarbon fuel using the heat and pressure generated by the engine 3. Therefore, no separate dedicated device is required. The fuel reforming system 1 is useful as an in-vehicle system.

[0088] 5 shows a control map of the engine 3. The control map corresponds to an operating region of the engine 3 defined by the rotation speed and required load of the engine 3. The controller 21 operates the engine 3 in accordance with the control map.

[0089] The control map divides the operating range of the engine 3 into a first range 101 and a second range 102. The first range 101 is a range where the rotation speed is lower than a first rotation speed N1. The second range 102 is a range where the rotation speed is equal to or higher than the first rotation speed N1. The first rotation speed N1 may be a rotation speed included in the medium rotation speed range when the operating range of the engine 3 is divided into three equal parts in the direction of rotation speed: a low rotation speed range, a medium rotation speed range, and a high rotation speed range.

[0090] The controller 21 causes the engine 3 to execute a six-stroke cycle in the first region 101. Carbon is recovered from the hydrocarbon fuel while hydrogen gas is used as fuel, making it possible to achieve carbon neutrality.

[0091] On the other hand, a six-stroke cycle has less power output than a typical four-stroke cycle because it has more strokes. Therefore, in this vehicle, when the six-stroke cycle is running and the required load of the engine 3 is equal to or greater than a predetermined load Pe2, the inverter 28 is controlled to drive the drive motor, thereby compensating for the lack of power output from the engine 3 (motor assist).

[0092] The load Pe2 may be a load included in the high load range when the operating range of the engine 3 is divided into three equal parts in the load direction: low load, medium load, and high load.

[0093] In the second region 102, the controller 21 also causes the engine 3 to operate in a normal four-stroke cycle consisting of an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke.

[0094] Specifically, the controller 21 stops the opening and closing of the on-off valve 38. Then, during the period from the intake stroke to the compression stroke, hydrocarbon fuel is injected from the intake port injector 44. Hydrogen gas may also be used as fuel. The engine 3 has a mechanism for changing the speed ratio between the crankshaft and the camshaft when switching between a six-stroke cycle and a four-stroke cycle.

[0095] (decomposer) 6 shows an example of a cracker 6 improved by applying the disclosed technology. The illustrated cracker 6 has a sealed cylindrical case 61. An opening 61a is formed at one end of the case 61, and the third port 37 is connected to the opening 61a. The cracker 6 communicates with the combustion chamber 3a via the third port 37. The other end of the case 61 is sealed with an end wall 61b.

[0096] The interior of the case 61 is divided into two spaces. Specifically, it is divided into a reforming space 62 located on the side of the connection portion with the third port 37, and an additional space 63 located on the opposite side of the connection portion with the third port 37. The reforming space 62 and the additional space 63 are adjacent to each other. The reforming space 62 is larger and occupies most of the interior of the case 61.

[0097] An air collection pipe 64 is attached to the case 61. The air collection pipe 64 penetrates the end wall and extends along the center line A of the case 61. The tip of the air collection pipe 64 is located near the opening 61a. Most of the air collection pipe 64 inside the case 61 is made up of a hydrogen-permeable membrane 65 supported by porous ceramic.

[0098] The reforming space 62 houses a reforming member 66 containing a catalyst 66b. The reforming reaction occurs in the reforming member 66. The illustrated reforming member 66 has a plurality of plate-shaped carriers 66a. These carriers 66a are attached radially to the inner wall of the case 61 and extend along the center line A of the case 61. The tip of each carrier 66a is positioned around the air collection pipe 64.

[0099] The surface of each carrier 66a is coated with a catalyst 66b. The catalyst 66b that can be used to decompose hydrocarbon fuel is, for example, a Ni-Al-Fe alloy. Various catalysts 66b can be used as the catalyst 66b as long as they can be used to decompose hydrocarbon fuel. The exemplary reforming member 66 can increase the surface area of ​​the catalyst 66b. This is advantageous for decomposing the hydrocarbon fuel because it makes it easier for the combustion gas containing the hydrocarbon fuel to come into contact with the catalyst 66b.

[0100] 7 shows a simplified diagram of the cracker 6 to explain the function of the reforming member 66. As described above, in the recompression stroke S4, the hydrocarbon fuel is introduced into the cracker 6 from the third port 37 together with the high-temperature, high-pressure combustion gas (which may contain air). Then, inside the reforming member 66, the hydrocarbon fuel comes into contact with the catalyst 66b, causing a reforming reaction (a partial oxidation reaction when the combustion gas contains air).

[0101] As a result, the hydrocarbon fuel is decomposed into carbon (denoted by the symbol C) and hydrogen gas. The carbon produced by the decomposition of the hydrocarbon fuel adheres to the surface of the catalyst 66b in a separable state. The carbon then accumulates and covers the surface of the catalyst 66b. Therefore, the decomposer 6 retains and stores the carbon.

[0102] As the amount of carbon adhesion increases, it becomes more difficult for the combustion gas containing hydrocarbon fuel to come into contact with the catalyst 66b, inhibiting the generation of hydrogen gas. This deteriorates the decomposition performance of the cracker 6. However, even if the amount of carbon adhesion increases, the state of the reforming member 66 can be reset by separating and removing the carbon from the catalyst 66b. This restores the yield of hydrogen gas and allows the cracker 6 to maintain its decomposition performance.

[0103] By forming the carrier 66a in the shape of a plate extending along the center line A of the case 61, it becomes easier to remove carbon separated from the catalyst 66b. That is, the carbon separated from the catalyst 66b by the combustion gas introduced into the cracker 6 can be collected on the opposite side of the opening 61a. The shape of the carrier 66a can be changed as appropriate depending on the specifications. For example, the carrier 66a may be in the shape of a number of balls.

[0104] The hydrogen-permeable membrane 65 has molecular-sized pores and has the function of selectively allowing hydrogen gas to pass through. The hydrogen gas generated inside the reforming member 66 passes through the hydrogen-permeable membrane 65 due to the pressure of the combustion gas and enters the gas collection pipe 64.

[0105] 1, the hydrogen gas that has entered the gas collection pipe 64 is sent to the hydrogen gas supply unit 5. On the other hand, most of the other gases, such as nitrogen gas and oxygen gas, do not permeate the hydrogen-permeable membrane 65. Therefore, these gases remain inside the reforming member 66 (residual gas).

[0106] (Structural issues with the cracker) It is preferable that the cracker have a high yield of hydrogen gas. Therefore, the reforming member 66 that causes the reforming reaction is usually provided throughout the entire interior of the case 61. This was also the case in crackers before the technology disclosed herein was applied.

[0107] However, this type of cracker has a closed tube structure with one end open 61a and the other closed, which means that when combustion gas is introduced, the influence of residual gas prevents the entire reforming member 66 from being used effectively.

[0108] 8A shows a simplified comparative example of a cracker (pre-improved cracker 600) before the application of the disclosed technology. In the pre-improved cracker 600, a reforming member 66 is provided throughout the interior of the case 61. Before the recompression step S4 in which combustion gas is introduced into the pre-improved cracker 600, the on-off valve 38 is closed. Residual gas Gr remains in the third port 37 and inside the pre-improved cracker 600.

[0109] Then, in the recompression stroke S4, the on-off valve 38 is opened, and hydrocarbon fuel is injected from the third port injector 46. As the piston 32 rises, as shown in the upper diagram of Fig. 8A, the combustion gas Gb, together with the hydrocarbon fuel, is introduced into the improved pre-cracker 600 from the third port 37 side. The combustion gas Gb has a higher pressure than the residual gas Gr.

[0110] Since the improved pre-decomposition unit 600 has a closed tubular structure, the residual gas Gr has no place to escape. Since the reforming space 62 is occupied by the reforming member 66, the flow rate of the combustion gas Gb decreases, and the combustion gas Gb is less likely to mix with the residual gas Gr.

[0111] Therefore, the residual gas Gr is compressed by the combustion gas Gb and forced toward the back of the case 61. As a result, a mass of residual gas Gr at the same pressure as the combustion gas Gb is formed toward the back of the case 61. This mass of residual gas Gr is lower in temperature than the combustion gas Gb and does not contain hydrocarbon fuel. It also contains a large amount of inert gas.

[0112] Therefore, in the portion occupied by this mass of residual gas Gr, no reforming reaction occurs even if the reforming member 66 is present. In other words, the entire reforming member 66 cannot be used effectively. Note that the boundary between the mass of residual gas Gr and the combustion gas Gb is not necessarily clear as shown in the figure. There may be some width, shading, variation, etc.

[0113] In contrast, in the improved cracker to which the disclosed technology is applied, i.e., the cracker 6, as described above, the interior of the case 61 is divided into a reforming space 62 located on the third port 37 side and an additional space 63 located on the opposite side. The reforming member 66 is built into the reforming space 62, and the additional space 63 is an empty space intended to accommodate a mass of residual gas Gr.

[0114] 8B shows a simplified cracker 6 as an example, similar to the comparative example. That is, the additional space 63 is a space into which the residual gas Gr is forced when the combustion gas Gb is introduced into the cracker 6 in the recompression stroke S4. The pressure of the combustion gas Gb in the reforming space 62 and the pressure of the residual gas Gr in the additional space 63 are balanced.

[0115] The capacity of the additional space 63 may be equal to or greater than the capacity of the mass of residual gas Gr. However, from the viewpoint of effective use of the reforming member 66, it is preferable that the capacity be approximately the same as the capacity of the mass of residual gas Gr. The capacity of the additional space 63 is, for example, the capacity when the internal pressure of the cracker 6 is at its highest.

[0116] The inventors conducted a CFD analysis and confirmed that the necessary and sufficient volume of the additional space 63 can be calculated and determined from the volume of the combustion chamber 3a, the volume of the third port 37, the volume of the cracker 6, the compression ratio of the engine 3, etc.

[0117] Therefore, the cracker 6 is provided with an additional space 63 of a necessary and sufficient capacity. Therefore, when the combustion gas Gb is introduced into the cracker 6 in the recompression stroke S4, the residual gas Gr is forced into and accommodated in the additional space 63. The reforming space 62 is then filled with the combustion gas Gb. In the case of this fuel reforming system 1, even if the cracker 6 has a closed-tube structure, the entire reforming member 66 can be effectively utilized.

[0118] Since the volume of the additional space 63 is approximately the same as the volume of the residual gas Gr, the combustion gas Gb hardly enters the additional space 63. Almost all of the hydrocarbon fuel injected as the reforming fuel can be brought into contact with the catalyst 66b. The internal pressure of the cracker 6 can also be maintained high, which is advantageous for the reforming reaction. In addition, since hydrogen gas can be permeated quickly, the generation of hydrogen gas can be promoted.

[0119] This is a very simple improvement that can effectively improve the yield of hydrogen gas. Since no major changes are required, it can be easily implemented. Therefore, it is highly practical.

[0120] Since the capacity of the additional space 63 is set in accordance with the residual gas Gr compressed in the recompression step S4, the capacity can be reduced, and therefore the size of the cracker 6 can be made compact.

[0121] <Modification of fuel reforming system> 9 shows a simplified version of the fuel reforming system 1 (second fuel reforming system 1B). As described above, the second fuel reforming system 1B further includes a slide device 70 (an example of a capacity variable mechanism) that varies the capacity of the additional space 63. The slide device 70 varies the capacity of the additional space 63 depending on the operating state of the engine 3.

[0122] Specifically, the slide device 70 has a disk-shaped slider 70a inside the case 61 on the side opposite the connection portion with the third port 37. The outer periphery of the slider 70a is in close contact with the inner periphery of the case 61, and the air collection pipe 64 passes through its center. The slider 70a has a seal and is configured to prevent gas leakage from the gap between them.

[0123] The slider 70a is driven by an attached drive device 70b, which causes the slider 70a to slide along the center line A of the case 61. The space between the reforming space 62 and the slider 70a corresponds to the additional space 63. The volume of the additional space 63 changes depending on the movement of the slider 70a. Various configurations are possible for the structure of the slide device 70. The optimum configuration can be selected depending on the specifications.

[0124] For example, the slider 70a may be connected to a predetermined crank, and the rotational movement of the crank may be converted into the reciprocating movement of the slider 70a. Alternatively, a rack may be attached to the slider 70a, and the slider 70a may be reciprocated by rotating a predetermined pinion that meshes with the rack. Alternatively, the slider 70a may be connected to a predetermined hydraulic piston, and the slider 70a may be reciprocated by hydraulic control.

[0125] To position the slider 70a, for example, if a crank is used, the rotation angle can be controlled using a variable valve timing mechanism such as the intake valve train described above. If a rack and pinion is used, the rotation angle can be controlled by driving the pinion with a servo motor. If a hydraulic piston is used, the position of the slider 70a can be detected by a sensor and hydraulic control can be performed based on that position.

[0126] Generally, the higher the load on the engine 3, the greater the required combustion energy. Therefore, the higher the load on the engine 3, the higher the pressure (temperature) of the combustion gas Gb. Therefore, in the recompression stroke S4, the difference (differential pressure) between the pressure of the residual gas Gr remaining in the cracker 6 and the pressure of the combustion gas Gb introduced into the cracker 6 from the combustion chamber 3a is large when the load on the engine 3 is high and is small when the load on the engine 3 is low.

[0127] When the pressure difference is small, the mass of residual gas Gr becomes larger. On the other hand, when the pressure difference is large, the mass of residual gas Gr becomes smaller because it is compressed more. Therefore, when the load of the engine 3 changes, the optimal capacity of the additional space 63 also changes.

[0128] In contrast, the second fuel reforming system 1B is configured so that the capacity of the additional space 63 can be varied. Therefore, the capacity of the additional space 63 can be changed and optimized. That is, the controller 21 outputs a control signal to the drive device 70b in accordance with the load of the engine 3. Then, the slider 70a is moved to a position where the additional space 63 has an optimal capacity for that load.

[0129] For example, when the required load on the engine 3 increases, the controller 21 moves the slider 70a in accordance with the required load to reduce the capacity of the additional space 63. This allows a large amount of high-temperature, high-pressure combustion gas Gb to be introduced into the reforming space 62 without entering the additional space 63. This allows the reforming member 66 to be used effectively, and a large amount of hydrogen gas to be produced.

[0130] <Application example of fuel reforming system> 10 shows a simplified application example (third fuel reforming system 1C) of the fuel reforming system 1. The third fuel reforming system 1C is a further improvement of the second fuel reforming system 1B.

[0131] 2, the third fuel reforming system 1C, like the second fuel reforming system 1B, is equipped with a slide device 70 that varies the volume of the additional space 63. The third fuel reforming system 1C also includes a carbon removal device 80. The carbon removal device 80 separates carbon adhering to the catalyst 66b from the catalyst 66b by, for example, applying a physical impact to the carrier 66a or scraping the surface of the carrier 66a with a scraper.

[0132] The third fuel reforming system 1C is designed so that carbon can be automatically discharged from the cracker 6 and recovered.

[0133] In the case of the illustrated decomposer 6, the side opposite the opening 61a in the case 61 is expanded. One end of a discharge passage 81 is connected to this expanded portion. The other end of the discharge passage 81 is connected to a collection box 82. The collection box 82 accumulates the discharged carbon and temporarily stores the carbon until it is collected.

[0134] As shown in the upper diagram of Figure 10, when the slider 70a is in a range of movement (control position 83) according to the load demand of the engine 3, the discharge passage 81 is blocked from the additional space 63 by the slider 70a. As a result, the discharge passage 81 does not communicate with the additional space 63. On the other hand, as shown in the lower diagram of Figure 10, when the slider 70a is moved to a predetermined position (discharge position 84) provided in the expansion portion, the discharge passage 81 communicates with the additional space 63.

[0135] As described above, when combustion gas Gb is introduced from the third port 37, carbon separated from the catalyst 66b is collected on the opposite side of the opening 61a, that is, in the additional space 63. Therefore, if combustion gas Gb is introduced from the third port 37 with the discharge passage 81 communicating with the additional space 63, the carbon can be discharged to the collection box 82 through the discharge passage 81.

[0136] Since it becomes possible to automatically remove carbon that accumulates inside the cracker 6, the state of the reforming member 66 can be reset as necessary. The yield of hydrogen gas is restored, and the cracking power of the cracker 6 can be maintained at an appropriate state.

[0137] The switching of the communication state between the discharge passage 81 and the additional space 63 is not limited to the illustrated embodiment. For example, a cover may be provided at the connection portion of the case 61 to the discharge passage 81, and the switching may be performed by opening and closing the cover. The key is that the discharge passage 81 is configured to be openable and closable.

[0138] (Example of control of the third fuel reforming system) 11A and 11B show an example of control of the third fuel reforming system 1C.

[0139] The controller 21 reads various signals input from the accelerator sensor 23 and the like (step S1). While the engine 3 is operating, the controller 21 identifies the output required of the engine 3 based on the read signals and executes that operation (Yes in step S2). Then, when the operation of the engine 3 ends, the control by the controller 21 also ends (No in step S2).

[0140] The controller 21 refers to the control map and determines whether the engine 3 is operating in the first region 101 (step S3).

[0141] As a result, when the engine 3 operates in the first region 101, the controller 21 performs six-stroke cycle operation, i.e., operation using hydrogen gas as the main fuel (step S4). On the other hand, when the engine 3 does not operate in the first region 101, i.e., when it operates in the second region 102, the controller 21 performs four-stroke cycle operation, i.e., operation using hydrocarbon fuel as the main fuel (step S5).

[0142] When the engine 3 is operating in a six-stroke cycle, the controller 21 estimates the amount of carbon deposited on the catalyst 66b based on signals from the hydrogen gas sensor 25 and other sources. If the amount of carbon deposited becomes excessive, the function of the catalyst 66b will be impaired, resulting in a decrease in the amount of hydrogen gas produced.

[0143] The controller 21 compares the estimated carbon deposition amount Dc with an upper limit Ds of the carbon deposition amount that is preset based on experiments or the like (step S6). If the controller 21 determines that the estimated carbon deposition amount Dc is equal to or greater than the upper limit Ds of the carbon deposition amount, the controller 21 executes the carbon removal mode (step S7).

[0144] 11B shows an example of control in the carbon removal mode. In the carbon removal mode, the controller 21 outputs a control signal to the slide device 70 to move the slider 70a to the discharge position 84 shown in the lower diagram of FIG. 10 (step S10). Then, the controller 21 outputs a control signal to the carbon removal device 80 to operate the carbon removal device 80 (step S11). As a result, carbon adhering to the catalyst 66b is separated from the catalyst 66b.

[0145] The controller 21 determines whether a predetermined carbon removal time ts, which is set in advance based on experiments or the like, has elapsed (step S12). The carbon removal time ts is a time sufficient to reset the catalyst 66b, and is set in accordance with the performance of the carbon removal device 80.

[0146] When the carbon removal time ts has elapsed, the controller 21 stops the carbon remover 80 (step S13). During this time, the engine 3 is operating in a six-stroke cycle, so that the combustion gas Gb is repeatedly introduced into the cracker 6. It is not necessary to inject hydrocarbon fuel from the third port injector 46. In other words, it is sufficient to introduce only the combustion gas Gb.

[0147] At this time, the combustion gas Gb flows easily because the inside of the decomposer 6 is in communication with the collection box 82 via the discharge passage 81. As a result, the separated carbon is discharged from the decomposer 6 to the collection box 82 through the additional space 63 and the discharge passage 81.

[0148] Next, the controller 21 moves the slider 70a to the control position 83 in order to perform a normal six-stroke cycle operation (step S14), and then returns to the processing of FIG. 11A.

[0149] On the other hand, if it is determined that the estimated value Dc of the carbon deposition amount is less than the upper limit Ds of the carbon deposition amount (No in step S6), the controller 21 moves the slider 70a in accordance with the operating state of the engine 3 (step S8). That is, the capacity of the additional space 63 is optimized in accordance with the required load of the engine 3.

[0150] While the engine 3 is running, the controller 21 repeats this process.

[0151] The disclosed technology is not limited to the above-described embodiments, but also includes various other configurations. For example, the individual contents of the first to third fuel reforming systems may be appropriately combined as needed. Vehicles to which the disclosed technology can be applied are not limited to hybrid vehicles. The drive source may be a reciprocating engine only. [Explanation of symbols]

[0152] 1 Fuel reforming system 2. Control System 3 Reciprocating engine 3a Combustion chamber 6 Decomposer 21 Controller 31 cylinders 32 piston 33 Intake port 34 Intake valve 35 exhaust port 36 Exhaust valve 37 Third Port 38 On-off valve 41 Intake valve train 42 Exhaust valve train 43 Third valve train 44 Intake port injector 45 Hydrocarbon fuel supply unit 46 Third port injector 47 Hydrogen Injector 61 cases 61a aperture 62 Reformation Space 63 Additional Space 64 Trachea 65 Hydrogen permeable membrane 66 Modified materials 66a Carrier 66b Catalyst 70 Slide device (variable capacity mechanism) 70a slider 70b Drive unit 80 Carbon removal device 81 Discharge passage 82 Collection Box 83 Control Position 84 Discharge position Gr residual gas Gb Combustion gas

Claims

1. A fuel reforming system for a vehicle equipped with a reciprocating engine in which a combustion chamber in which combustion occurs is defined inside a cylinder in which a piston reciprocates, a cracker that utilizes the heat and pressure of the combustion gas generated in the combustion chamber and a catalyst to decompose the hydrocarbon fuel into carbon and hydrogen gas and retain the carbon; a hydrocarbon fuel supply unit that supplies the hydrocarbon fuel to the cracker; Equipped with the decomposer is in communication with the combustion chamber through a port that can be opened and closed; a reforming space having a reforming member including the catalyst built therein is provided on the side of a connection portion between the cracker and the port, A fuel reforming system in which an additional space is provided adjacent to the reforming space inside the cracker on the opposite side of the connection portion with the port, for accommodating residual gas remaining inside the port and the cracker when the combustion gas is introduced into the cracker through the port.

2. 2. The fuel reforming system of claim 1, Further provided is a capacity variable mechanism that varies the capacity of the additional space, A fuel reforming system in which the volume of the additional space is variable depending on the operating state of the reciprocating engine.

3. 2. The fuel reforming system of claim 1, The carbon is held in the decomposer in a separable state, and an openable and closable discharge passage is connected to the additional space, The fuel reforming system is configured so that the carbon separated from the decomposer can be discharged through the discharge passage.

4. The fuel reforming system according to any one of claims 1 to 3, The reciprocating engine, an intake stroke in which at least intake air is introduced into the combustion chamber through an intake port as the piston descends; a compression stroke in which the mixture containing the hydrogen gas supplied to the combustion chamber is compressed by the rise of the piston; an expansion stroke in which the piston descends due to combustion of the air-fuel mixture; a recompression stroke in which the combustion gas is compressed by the rise of the piston; a re-expansion stroke in which the piston descends; and an exhaust stroke in which exhaust gas is discharged through the exhaust port as the piston rises; and configured to perform a six-stroke cycle consisting of A fuel reforming system in which, during the recompression stroke, the combustion gas is introduced into the cracker through the port, thereby forcing the residual gas into the additional space and storing it therein.

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