Fuel reforming system for vehicle

Abstract

To provide a compact fuel reforming system suitable for mounting to a vehicle.SOLUTION: A fuel reforming system 1A for a vehicle mounted with a reciprocal engine 3 that executes a predetermined 6-stroke cycle includes a decomposition device 6 that stores carbon. The decomposition device 6 decomposes hydrocarbon fuel into carbon and hydrogen gas by using heat and pressure of combustion gas generated in a combustion chamber 3a, and causes the hydrogen gas to penetrate a hydrogen permeation film 63 for separation. The decomposition device 6 is disposed adjacent to an intake port 33 while communicating with the intake port 33 via the hydrogen permeation film 63, and is configured so that the separated hydrogen gas can be supplied to the combustion chamber 3a through the intake port 33 as fuel.SELECTED DRAWING: Figure 1

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 engine to raise the temperature of the catalyst.

[0008] However, when using hydrogen gas as engine fuel, a gas tank is usually required to store the hydrogen gas. In addition to the gas tank, components such as gas pipes and valves are also required. In other words, a separate hydrogen gas supply system is required to supply hydrogen gas to the engine.

[0009] In a vehicle where space is limited, installing such a hydrogen gas supply system is disadvantageous, and installing such a hydrogen gas supply system in a vehicle increases the vehicle's weight. Therefore, this type of fuel reforming system also has disadvantages when installed in a vehicle.

[0010] The technology disclosed herein provides a fuel reforming system suitable for installation in a vehicle. [Means for solving the problem]

[0011] 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.

[0012] The reciprocating engine is configured to execute 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 a mixture containing fuel 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 re-compression stroke in which 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.

[0013] The fuel reforming system includes a cracker that communicates with the combustion chamber via an openable third port, decomposes hydrocarbon fuel into carbon and hydrogen gas, and stores the carbon, and a hydrocarbon fuel supply unit that supplies the hydrocarbon fuel to the cracker.

[0014] The cracker is configured to use the heat and pressure of the combustion gas generated in the combustion chamber to decompose the hydrocarbon fuel into the carbon and the hydrogen gas, and to separate the hydrogen gas by allowing it to pass through a hydrogen-permeable membrane.The cracker is disposed adjacent to the intake port while communicating with the intake port via the hydrogen-permeable membrane, and is configured so that the separated hydrogen gas can be supplied to the combustion chamber as fuel through the intake port.

[0015] The fuel reforming system is used in vehicles equipped with reciprocating engines that run a specific six-stroke cycle. The fuel reforming system includes a cracker that communicates with the combustion chamber through an openable third port. The cracker utilizes the heat and pressure of the combustion gases generated in the combustion chamber to produce carbon and hydrogen gas from the hydrocarbon fuel.

[0016] Since the heat and pressure of the combustion gas are used to generate carbon and hydrogen gas, a dedicated heating device is not required. This simplifies the fuel reforming system. The generated carbon is stored in the cracker. This reduces carbon emissions.

[0017] The cracker is disposed adjacent to the intake port in communication with the intake port via a hydrogen-permeable membrane, and the separated hydrogen gas can be supplied as fuel to the combustion chamber through the intake port.

[0018] Therefore, the generated hydrogen gas can be supplied as fuel to the combustion chamber through the intake port. Moreover, the hydrogen gas is sent directly from the cracker to the intake port. Therefore, there is no need to install a hydrogen gas supply system such as a gas tank. This makes it possible to realize a fuel reforming system with an extremely compact and simple structure.

[0019] The cracker is located near the combustion chamber, allowing for easy heat transfer. This promotes the reforming reaction and partial oxidation reaction that decompose hydrocarbon fuel into carbon and hydrogen gas. Hydrogen gas can be produced efficiently. The disclosed technology utilizes the functions of a reciprocating engine to realize a fuel reforming system suitable for installation in a vehicle.

[0020] A first injector that injects the hydrocarbon fuel toward the inside of the third port may be attached to the third port, and the hydrocarbon fuel may be injected from the first injector in a latter half of the recompression stroke with the third port open.

[0021] The pressure of the combustion gas is high during the latter half of the recompression stroke when the piston is near top dead center. Therefore, when the third port is open, high-temperature combustion gas flows into the third port, increasing the internal pressure of the cracker. Then, by injecting hydrocarbon fuel toward the third port into which the high-temperature, high-pressure combustion gas is flowing, the hydrocarbon fuel can be effectively vaporized and dispersed into the combustion gas. This allows the high-temperature, high-pressure combustion gas, with the hydrocarbon fuel in a homogenized state, to be introduced into the cracker.

[0022] As a result, the decomposition of carbon and hydrogen gas can be promoted, and hydrogen gas can be produced effectively.

[0023] The cracker may have a case installed along the intake port, a reforming member housed in the case so as to extend along the case, and a closed-pipe passage provided in the center of the reforming member, the open end of which communicates with the third port, and a second injector attached to the cracker for injecting the hydrocarbon fuel from the closed end side of the closed-pipe passage toward the closed-pipe passage, and the hydrocarbon fuel may be injected from the second injector in the first half of the recompression stroke with the third port open.

[0024] During the first half of the recompression stroke, even with the third port open, the pressure inside the cracker is still low. In this state, when hydrocarbon fuel is injected from the closed end of the closed-pipe passage toward the closed-pipe passage, the hydrocarbon fuel passes through the closed-pipe passage toward the third port. At this time, an increasing amount of high-temperature combustion gas is flowing into the third port. The hydrocarbon fuel collides with the combustion gas.

[0025] This prevents the hydrocarbon fuel from entering the combustion chamber, and effectively disperses the hydrocarbon fuel in the high-temperature combustion gas, which is then introduced into the cracker at high temperature and pressure, with the hydrocarbon fuel in a homogenized state.

[0026] As a result, the decomposition of carbon and hydrogen gas can be promoted, and hydrogen gas can be produced effectively.

[0027] The third port may be opened during the re-expansion stroke.

[0028] After the hydrocarbon fuel is decomposed into carbon and hydrogen gas in the cracker, impurity gases such as nitrogen gas remain inside the cracker. Therefore, the gas remaining in the cracker (residual gas) contains a relatively large amount of impurity gases.

[0029] When the amount of impure gas increases, the amount of high-temperature combustion gas required for the reforming reaction decreases. Therefore, such residual gas interferes with the production of hydrogen gas. In response to this, by opening the third port during the re-expansion stroke, the inside of the cracker can be purged. In other words, the amount of residual gas remaining inside the cracker can be reduced.

[0030] Since the inside of the cracker can be scavenged in each cycle, hydrogen gas can be produced in the cracker in each cycle. This is also advantageous in reducing engine pumping losses.

[0031] The cracker may have a communication passage therein that connects the third port with an intake air supply unit located upstream of the intake port, and a regulating valve that can block flow from the third port side toward the intake air supply unit side is installed between the intake air supply unit and the communication passage.

[0032] For example, when a reciprocating engine is operated in the high-load, high-speed range, there is a risk of insufficient charging efficiency. However, with this configuration, the combustion chamber can be connected to the intake air supply section via the communication passage and the third port. In other words, intake air can be introduced into the combustion chamber through these paths in addition to the intake port. This increases charging efficiency, making up for the lack of charging efficiency. [Effects of the Invention]

[0033] The disclosed technology utilizes the functions of a reciprocating engine to efficiently generate hydrogen gas for use as fuel while recovering carbon in a very compact configuration, thereby realizing a fuel reforming system suitable for installation in a vehicle. [Brief explanation of the drawings]

[0034] [Figure 1] 1 is a schematic diagram of a fuel reforming system according to a first embodiment. [Figure 2] 2 is a view seen from the direction of arrow A1 in FIG. [Figure 3] FIG. 1 is a schematic diagram of a decomposer. [Figure 4] FIG. 2 is a block diagram of a control system. [Figure 5] FIG. 1 is a diagram for explaining a six-stroke cycle. [Figure 6] 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 7] 1 is a flowchart of control by a first fuel reforming system; [Figure 8] FIG. 10 is a schematic diagram (corresponding to FIG. 2) of a fuel reforming system according to a second embodiment. [Figure 9] 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 10] FIG. 10 is a diagram showing a predetermined state of the recompression stroke. [Figure 11] 10 is a flowchart of control by the second fuel reforming system; [Figure 12] FIG. 10 is a schematic diagram (corresponding to FIG. 2) of a fuel reforming system according to a third embodiment. [Figure 13] 10 is an example of changes in valve operation, reformed fuel injection timing, and cracker internal pressure. [Figure 14] 10A and 10B are diagrams illustrating predetermined states of the intake stroke. [Figure 15A] 10 is a flowchart of control by a third fuel reforming system; [Figure 15B] 10 is a flowchart of control by a third fuel reforming system; DETAILED DESCRIPTION OF THE INVENTION

[0035] The disclosed technology takes advantage of the unique capabilities of vehicles, allowing them to reform hydrocarbon fuels and effectively use hydrogen gas as a fuel in a compact design.

[0036] That is, it is possible to realize a fuel reforming system suitable for installation in a vehicle. The disclosed technology will be described below with reference to first to third embodiments. However, the following description is essentially merely an example.

[0037] First Embodiment 1 and 2 show an example of a fuel reforming system (first fuel reforming system 1A) mounted on a vehicle. Fig. 2 is a view seen from the direction of arrow A1 in Fig. 1.

[0038] (Configuration of the first fuel reforming system) A hydrocarbon fuel is stored in a fuel tank mounted on a vehicle. The hydrocarbon fuel is, for example, gasoline. The hydrocarbon fuel is not limited to gasoline. The first fuel reforming system 1A decomposes the hydrocarbon fuel into carbon and hydrogen gas.

[0039] The carbon is stored in a cracker 6, which will be described later. The hydrogen gas is used as fuel for the reciprocating engine 3. The first fuel reforming system 1A realizes carbon neutrality for vehicles that are equipped with hydrocarbon fuel.

[0040] The first fuel reforming system 1A includes a reciprocating engine 3 (hereinafter also 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 portion of the cylinder 31, the lower surface of which is partitioned by the piston 32. The engine 3 includes a plurality of cylinders 31.

[0041] 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.

[0042] 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 intake port 33. The intake ports 33 of each cylinder are connected to an intake manifold 33a (an example of an intake air supply unit) located upstream of the intake port 33.

[0043] Fresh air (outside air) is distributed and supplied from the intake manifold 33a to each intake port 33. Then, as will be described later, fresh air is introduced into each combustion chamber 3a through the intake port 33. Therefore, the intake air contains at least fresh air. The intake air may also contain EGR (Exhaust Gas Recirculation) gas. Furthermore, as will be described later, in this engine 3, the intake air may also contain hydrogen gas.

[0044] 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. 4 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.

[0045] 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.

[0046] The engine 3 has exhaust ports 35. The exhaust ports 35 communicate with the combustion chambers 3a. Each cylinder 31 has two exhaust ports 35. Alternatively, the number of exhaust ports 35 may be one. The exhaust ports 35 are connected to an exhaust pipe. As will be described later, exhaust gas is discharged from the combustion chambers 3a through the exhaust ports 35.

[0047] 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. 4 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.

[0048] 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.

[0049] The engine 3 has a third port 37. The third port 37 is connected to the combustion chamber 3a. Each cylinder 31 has one third port 37.

[0050] The third port 37 is adjacent to the intake port 33 and extends along the intake port 33. The third port 37 has an inner diameter equal to or smaller than that of the intake port 33. For ease of understanding, the exhaust port 35 and the third port 37 are depicted in offset positions in FIG. 1.

[0051] The engine 3 has an on-off valve 38. The on-off valve 38 is a poppet valve that opens and closes the third port 37. A third valve train 43 shown in FIG. 4 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.

[0052] The third valve train 43 can also continuously change the valve timing and valve lift of the on-off valve 38. That is, the third valve train 43 can change the valve timing and / or valve lift according to the operating state of the engine 3. However, in a six-stroke cycle described below, the third valve train 43 basically opens the on-off valve 38 twice in one cycle.

[0053] 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.

[0054] A direct injection injector 44 is attached to the engine 3. An injection hole of the direct injection injector 44 faces the combustion chamber 3a. The direct injection injector 44 is connected to a hydrocarbon fuel supply unit 45. The hydrocarbon fuel supply unit 45 has a fuel tank that stores hydrocarbon fuel and a fuel pump that pressure-feeds the hydrocarbon fuel. The hydrocarbon fuel supply unit 45 supplies hydrocarbon fuel to the direct injection injector 44. The direct injection injector 44 injects hydrocarbon fuel as fuel into the combustion chamber 3a.

[0055] A reforming injector 46 is attached to the third port 37. The reforming injector 46 here corresponds to the first injector. The injection holes of the reforming injector 46 face the inside of the third port 37. The reforming injector 46 is also connected to the hydrocarbon fuel supply unit 45. The hydrocarbon fuel supply unit 45 supplies hydrocarbon fuel to the reforming injector 46. The reforming injector 46 injects hydrocarbon fuel for reforming (reformed fuel) toward the inside of the third port 37.

[0056] (decomposer) 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.

[0057] The cracker 6 decomposes the hydrocarbon fuel into carbon and hydrogen gas. A cracker 6 is attached to each cylinder 31. The cracker 6 is disposed adjacent to the intake port 33 and communicates with the intake port 33 via a hydrogen-permeable membrane 63, which will be described later. This allows the separated hydrogen gas to be supplied as fuel to the combustion chamber 3a through the intake port 33.

[0058] FIG. 3 shows the structure of the cracker 6. The cracker 6 generates hydrogen gas through a reforming reaction. The cracker 6 uses a catalyst to decompose hydrocarbon fuel into carbon and hydrogen gas at high temperatures practical for use in a vehicle. The hydrogen gas is then separated by passing it through a hydrogen-permeable membrane 63.

[0059] The cracker 6 is a so-called membrane reactor. The cracking of a hydrocarbon fuel, for example, isooctane, is represented by the following chemical reaction formula:

[0060] iC8H18(g) = 8C(s) + 9H2

[0061] The recovery of solid carbon prevents the weight of the vehicle from increasing. The first fuel reforming system 1A is suitable for use as an in-vehicle system.

[0062] The cracker 6 has a reforming member 60. The reforming member 60 includes a cylindrical support 61 and a ball-shaped carrier 62. A hydrogen-permeable membrane 63 is supported on the outside of the support 61 (the hydrogen-permeable membrane 63 may also be supported on the inside of the support 61).

[0063] A mesh body 61a that receives the carrier 62 is attached to one opening of the support body 61. The inside of the support body 61 communicates with the third port 37 through the mesh body 61a. Meanwhile, the other opening of the support body 61 is sealed with a lid body 61b.

[0064] The support 62 may be, for example, an aluminum oxide ball. A catalyst is applied to the surface of the support 62. A catalyst that can be used to decompose hydrocarbon fuel is, for example, a Ni-Al-Fe alloy. Any catalyst can be used as long as it can be used to decompose hydrocarbon fuel.

[0065] A large number of supports 62 are packed inside the support 61. The use of balls as the supports 62 increases the surface area of ​​the catalyst and improves the cracking performance of the cracker 6. The shape of the supports 62 is not limited to a specific shape.

[0066] Carbon produced by the decomposition of hydrocarbon fuel adheres to the surface of the support 62. The cracker 6 also stores carbon. The use of balls increases the amount of carbon stored in the cracker 6 and allows the cracking performance of the cracker 6 to be maintained for a long period of time even if the amount of carbon stored increases. The use of balls also facilitates the separation of hydrogen gas that is cracked from the hydrocarbon fuel. As will be described later, efficient separation of hydrogen gas also suppresses a decline in the cracking performance of the cracker 6.

[0067] The support 61 is made of, for example, porous ceramic. The porous ceramic is, for example, zirconia. The support 61 has the function of accommodating a catalyst support 62 (described later) and the function of holding a hydrogen-permeable membrane 63.

[0068] The hydrogen-permeable membrane 63 is attached to the outer peripheral surface of the support 61. The hydrogen-permeable membrane 63 is, for example, a Pd alloy membrane. The hydrogen-permeable membrane 63 has molecular-sized pores and selectively allows hydrogen gas to pass through. Hydrogen gas generated inside the support 61 passes through the hydrogen-permeable membrane 63 to reach the outside of the reforming member 60 (see the open arrow in FIG. 3). Impurity gases other than hydrogen gas, such as nitrogen gas, remain inside the support 61. The reforming member 60 can have various structures.

[0069] The cracker 6 has a case 64. The case 64 is installed so as to extend along the intake port 33. The reforming member 60 is housed in the case 64. A portion of the intake port 33 is also housed in the case 64. As a result, the portion of the intake port 33 and the reforming member 60 are located in a sealed communication space 65.

[0070] The intake port 33 has an opening 33b facing the communication space 65. The opening 33b is formed so as to extend along the reforming member 60. The opening 33b may be in the form of a number of holes. In short, it is sufficient that the opening 33b allows hydrogen gas to pass from the communication space 65 into the inside of the intake port 33.

[0071] A space that constitutes a communication space 65 is formed between the outer peripheral surface of the reforming member 60 and the inner peripheral surface of the case 64. The case 64 guides hydrogen gas into the inside of the intake port 33 through the opening 33b.

[0072] A third port 37 is connected to an end of the case 64. More specifically, the third port 37 is connected to one end of the cylindrical support 61 and communicates with its interior. Combustion gas generated in the combustion chamber 3a and reformed fuel (hydrocarbon fuel) injected from the reforming injector 46 are introduced into the inside of the support 61 and the hydrogen-permeable membrane 63 through the third port 37 (see the black arrows in FIG. 3). Inside the support 61, the hydrocarbon fuel is decomposed into carbon and hydrogen gas.

[0073] The hydrogen gas that permeates the hydrogen-permeable membrane 63 flows into the intake port 33 through the communication space 65 (see the white arrows in Figures 1 and 3). The hydrogen gas that flows into the intake port 33 is supplied to the combustion chamber 3a through the intake port 33 and is used as fuel.

[0074] (Controller) FIG. 4 shows a block diagram of the control system 2 installed in the vehicle. The first fuel reforming system 1A cooperates with this control system 2. The first fuel reforming system 1A 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.

[0075] 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.

[0076] 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.

[0077] 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.

[0078] 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, which includes a signal from the crank angle sensor 24.

[0079] Similarly, the exhaust valve train 42 changes the valve timing and / or valve lift of the exhaust valve 36 based on a control signal from the controller 21. The third valve train 43 also switches the on-off valve 38 between open, closed, and stopped based on a control signal from the controller 21. Then, the valve timing and / or valve lift of the on-off valve 38 is changed as necessary.

[0080] The direct injector 44 and the reforming injector 46 are each electrically connected to the controller 21. The controller 21 outputs control signals to the direct injector 44 and the reforming injector 46.

[0081] The direct injector 44 injects a predetermined amount of hydrocarbon fuel into the combustion chamber 3a at a predetermined timing based on a control signal from the controller 21. The reforming injector 46 injects a predetermined amount of reformed fuel into the third port 37 at a predetermined timing based on a control signal from the controller 21.

[0082] 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.

[0083] The control system 2 has an inverter 28. The vehicle has a drive motor 28a (assist motor) that outputs driving force for running the vehicle. The inverter 28 controls the drive motor 28a. 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 28a to assist the operation of the engine 3.

[0084] 4, the cracker temperature sensor 25, the hydrogen gas sensor 26, and the regulating valve opening / closing device 73 are devices related to the embodiment described later, and will be described later.

[0085] (Reciprocating engine operation) The engine 3 executes a six-stroke cycle in order for the cracker 6 to crack the hydrocarbon fuel. Figure 5 shows an example of each stroke in the six-stroke cycle. Figure 6 shows an example of the valve timing and valve lift of each valve, the injection timing of the reformed fuel, and changes in the internal pressure of the cracker 6 in the six-stroke cycle.

[0086] 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.

[0087] The intake air includes at least fresh air. As will be described later, it may also include hydrogen gas. When the intake air containing hydrogen gas is introduced into the combustion chamber 3a, the hydrogen gas is used as fuel. In this engine 3, the amount of hydrocarbon fuel used as fuel can be reduced or eliminated accordingly.

[0088] 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 an EGR passage. As shown by the phantom line in Figure 5, the exhaust valve 36 may open during the intake stroke S1. When the exhaust valve 36 opens, exhaust gas is introduced into the combustion chamber 3a through the exhaust port 35.

[0089] The exhaust gas introduced into the combustion chamber 3a is so-called internal EGR gas. The amount of internal EGR gas in the combustion chamber 3a is adjusted depending on the load on the engine 3. For example, the amount of internal EGR gas in the combustion chamber 3a is adjusted to decrease as the load on the engine 3 increases. Accordingly, the amount of intake air (fresh air) introduced into the combustion chamber 3a increases.

[0090] The engine 3 outputs power according to demand by adjusting the amount of internal EGR gas (and the amount of fresh air). Note that, during the intake stroke S1, the opening / closing valve 38 of the third port 37 is closed.

[0091] In the example of Fig. 5, the direct injector 44 injects hydrocarbon fuel into the combustion chamber 3a during the intake stroke S1. The direct injector 44 may inject hydrocarbon fuel during the compression stroke S2. The direct injector 44 may inject hydrocarbon fuel during the period from the intake stroke S1 to the compression stroke S2. The injection of hydrocarbon fuel forms an air-fuel mixture in the combustion chamber 3a.

[0092] S2 is a compression stroke following the intake stroke S1. 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. During the compression stroke S2, the intake valve 34, exhaust valve 36, and on-off valve 38 are all closed.

[0093] 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 following the compression stroke S2. During the expansion stroke S3, the piston 32 descends due to the combustion of the air-fuel mixture. During the expansion stroke S3, the intake valve 34, exhaust valve 36, and on-off valve 38 are all closed.

[0094] S4 is a recompression stroke following the expansion stroke S3. 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 intake valve 34 and the exhaust valve 36 are closed. As a result, the compressed combustion gas is introduced into the cracker 6 through the third port 37.

[0095] Furthermore, the reforming injector 46 injects reformed fuel into the third port 37 during the recompression stroke S4 depending on the operating state of the engine 3. In detail, as indicated by symbol F1 in Fig. 6, the reforming injector 46 injects reformed fuel in the latter half of the recompression stroke S4.

[0096] The later the recompression stroke S4, the higher the pressure of the combustion gas. The internal pressure of the cracker 6 is lower than the internal pressure of the combustion chamber 3a. Therefore, high-temperature combustion gas flows from the combustion chamber 3a into the cracker 6 while compressing the gas stored inside the cracker 6. In the latter half of the recompression stroke S4, the pressure difference is small, and high-temperature, high-pressure combustion gas flows in.

[0097] In this state, the reformed fuel is injected toward the third port 37 into which the high-pressure combustion gas is flowing, so the reformed fuel can be effectively dispersed into the combustion gas even if the third port 37 is narrow. Thus, the high-temperature, high-pressure combustion gas in which the reformed fuel has been homogenized is introduced into the cracker 6.

[0098] As mentioned above, in the cracker 6, the hydrocarbon fuel is decomposed into carbon and hydrogen gas by the heat of the combustion gas and the catalyst. Because the reformed 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.

[0099] The carbon is stored in the decomposer 6. The hydrogen gas permeates through the hydrogen-permeable membrane 63 due to the internal pressure difference between the decomposer 6 and the intake port 33 (internal pressure of the decomposer 6 > internal pressure of the intake port 33). The hydrogen gas that permeates the hydrogen-permeable membrane 63 is sent to the intake port 33 via the communication space 65. The hydrogen gas sent to the intake port 33 accumulates inside the intake port 33.

[0100] The high pressure of the combustion gas in the recompression step S4 acts on the inside of the cracker 6, so the generated hydrogen gas quickly permeates the hydrogen permeable membrane 63. Because the amount of hydrogen gas inside the cracker 6 is reduced, the decomposition of the reformed fuel is promoted.

[0101] Moreover, the cracker 6 is located near the combustion chamber 3a, which becomes hot, and is integrated with the intake port 33 and the third port 37, which communicate with the combustion chamber 3a. Therefore, the heat of the combustion chamber 3a is easily transferred to the cracker 6, and the cracker 6 can effectively utilize that heat. Therefore, even though the cracker 6 is small, it can efficiently generate a relatively large amount of hydrogen gas.

[0102] S5 is a re-expansion stroke following the re-compression stroke S4. In the re-expansion stroke S5, the intake valve 34 and the exhaust valve 36 are closed. The piston 32 then descends. The on-off valve 38 opens in the re-expansion stroke S5. When the on-off valve 38 opens, the combustion gas stored in the cracker 6 is sucked in and flows into the combustion chamber 3a.

[0103] After the recompression step S4, residual gas remains in the cracker 6. The residual gas contains a large amount of impurity gases such as nitrogen gas. That is, in the cracker 6, hydrogen gas and carbon are removed from the combustion gas through catalytic decomposition and separation by the hydrogen-permeable membrane 63. On the other hand, impurity gases such as nitrogen gas remain. Therefore, the residual gas remaining in the cracker 6 contains a relatively large amount of impurity gases such as nitrogen gas.

[0104] When the amount of impure gas increases, the amount of high-temperature combustion gas required for the reforming reaction decreases. Therefore, the residual gas interferes with the production of hydrogen gas. By opening the third port 37 during the re-expansion stroke S5, the inside of the cracker 6 can be scavenged. In other words, the amount of residual gas remaining inside the cracker 6 can be reduced.

[0105] Since the inside of the cracker 6 can be scavenged in each cycle, hydrogen gas can be produced in the cracker 6 in each cycle. In addition, opening the on-off valve 38 in the re-expansion stroke S5 is also advantageous in reducing pumping loss of the engine 3.

[0106] S6 is an exhaust stroke following the re-expansion stroke S5. 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 (including the residual gas scavenged from the cracker 6) is discharged to the exhaust port 35. During the exhaust stroke S6, the intake valve 34 and the on-off valve 38 are closed.

[0107] After the exhaust stroke S6, the engine 3 returns to the intake stroke S1. During the intake stroke S1, when the intake valve 34 opens, intake air containing hydrogen gas is introduced into the combustion chamber 3a through the intake port 33. When the intake air containing hydrogen gas is introduced into the combustion chamber 3a, as described above, the hydrogen gas is used as fuel. In this engine, the amount of hydrocarbon fuel used as fuel can be reduced or eliminated accordingly.

[0108] At the boundary between the intake stroke S1 and the exhaust stroke S6, the timing at which the intake valve 34 opens and the timing at which the exhaust valve 36 opens slightly overlap with each other around top dead center, i.e., valve overlap. Similarly, at the boundary between the re-expansion stroke S5 and the exhaust stroke S6, the timing at which the on-off valve 38 opens and the timing at which the exhaust valve 36 opens slightly overlap with each other around bottom dead center.

[0109] The first fuel reforming system 1A stores carbon produced by the decomposition of hydrocarbon fuel in a cracker 6. The hydrogen gas produced by the decomposition of hydrocarbon fuel is then combusted in the engine 3. As a result, no carbon oxides are generated as a result of combustion. The first fuel reforming system 1A can achieve carbon neutrality.

[0110] The first fuel reforming system 1A also decomposes hydrocarbon fuel using heat and pressure generated by the engine 3. Therefore, no separate dedicated device is required. Moreover, the decomposer 6 is adjacent to the intake port 33, and the generated hydrogen gas is immediately sent to the intake port 33. Then, during the intake stroke S1, the hydrogen gas is introduced into the combustion chamber 3a as part of the intake air. Therefore, with a very simple configuration, hydrogen gas can be efficiently supplied to the combustion chamber 3a as fuel. The first fuel reforming system 1A is useful as an on-board system.

[0111] When the amount of carbon stored in the cracker 6 increases, the carbon is recovered from the cracker 6. For example, when a vehicle is brought in for maintenance, the support 62 with the carbon attached thereto is taken out from the cracker 6, and the carbon is removed from the support 62 using, for example, a mill. The recovered carbon can be used as industrial carbon. The support 62 from which the carbon has been removed can be re-coated with a catalyst as necessary and then re-filled into the cracker 6.

[0112] In a six-stroke cycle, it is not essential to inject hydrocarbon fuel from the direct injector 44. For example, when the vehicle is decelerating, it is not necessary to inject hydrocarbon fuel from the direct injector 44 (so-called fuel cut). Also, if the output required of the engine 3 is sufficient from the combustion energy of the hydrogen gas contained in the intake air, it is not necessary to inject hydrocarbon fuel from the direct injector 44.

[0113] On the other hand, when a high load is required for the engine 3 or when hydrogen gas as fuel is not required for the engine 3, the engine 3 may be operated using a normal four-stroke cycle. That is, the engine 3 may be operated in the six-stroke cycle described above, omitting the re-compression stroke S4 and the re-expansion stroke S5.

[0114] (Example of control by the first fuel reforming system) An example of control by the first fuel reforming system 1A is shown in Figure 7. It is assumed that the engine 3 performs combustion according to the six-stroke cycle described above.

[0115] 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 operation using the six-stroke cycle described above (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).

[0116] While the engine 3 is operating, the controller 21 determines whether or not hydrogen gas needs to be produced based on the output required of the engine 3, the operating state of the engine 3, etc. (step S3).

[0117] As a result, if it is determined that hydrogen gas needs to be produced, the controller 21 injects reformed fuel in the latter half of the recompression stroke S4 (step S4), as shown in Figure 6. The amount of hydrogen gas produced can be controlled based on the amount of reformed fuel injected, the temperature of the cracker 6, etc. The controller 21 adjusts the amount of reformed fuel injected depending on the operating state of the engine 3.

[0118] On the other hand, if it is determined that the production of hydrogen gas is unnecessary, the controller 21 does not inject the reformed fuel, thereby reducing the consumption of hydrocarbon fuel. While the engine 3 is operating, the controller 21 repeats this process.

[0119] <Second embodiment> 8 shows another example of a fuel reforming system (second fuel reforming system 1B) mounted on a vehicle. The basic configuration of the second fuel reforming system 1B is the same as that of the first fuel reforming system 1A. Therefore, the same reference numerals are used for the same components, and the description thereof will be simplified or omitted.

[0120] (Configuration of the second fuel reforming system) The second fuel reforming system 1B differs from the first fuel reforming system 1A in the configuration of the cracker 6 and the like.

[0121] Specifically, in the case of the cracker 6 of the second fuel reforming system 1B, firstly, the reforming member 60 further includes a tube 60a having a smaller diameter than the support body 61. Similar to the mesh body 61a, the tube 60a has the function of receiving the support body 62, and is provided coaxially with the support body 61 at its center.

[0122] One end of the tube 60a is attached to the mesh body 61a, and the other end of the tube 60a is attached to the lid body 61b, thereby forming a closed pipe passage 66 in the center of the reforming member 60, the open end of which communicates with the third port 37.

[0123] The reforming injector 46 is attached to the cover body 61b. The injection holes of the reforming injector 46 face the inside of the closed pipe passage 66. Therefore, the reforming injector 46 injects reformed fuel from the closed end side of the closed pipe passage 66 toward the closed pipe passage 66. The reforming injector 46 here corresponds to a second injector.

[0124] Secondly, in the case of the cracker 6 of the second fuel reforming system 1B, the case 64 has a non-communicating portion 64a that does not have a communicating space 65. Specifically, a tubular non-communicating portion 64a that surrounds only the reforming member 60 is provided in the portion of the case 64 on the side of the third port 37.

[0125] Accordingly, the opening 33b of the intake port 33 is not formed in the non-communicating portion 64a. The hydrogen-permeable membrane 63 is also not formed in the non-communicating portion 64a. The opening 33b of the intake port 33 is formed in a portion of the case 64 opposite the third port 37, where the communicating space 65 is located.

[0126] (Controller) In the second fuel reforming system 1B, devices are added to the control system 2 of the first fuel reforming system 1A, as shown by the phantom lines in Figure 4. Specifically, a decomposer temperature sensor 25 and a hydrogen gas sensor 26 are further electrically connected to the controller 21.

[0127] The decomposer temperature sensor 25 is attached to the decomposer 6. The decomposer temperature sensor 25 measures the temperature inside the decomposer 6. The controller 21 outputs a control signal to the decomposer temperature sensor 25. Based on the control signal from the controller 21, the decomposer temperature sensor 25 outputs a signal corresponding to the temperature inside the decomposer 6 to the controller 21. Based on the signal from the decomposer temperature sensor 25, the controller 21 determines whether the temperature of the decomposer 6 is appropriate.

[0128] The hydrogen gas sensor 26 is attached to the decomposer 6. The hydrogen gas sensor 26 measures the amount of hydrogen gas. The controller 21 outputs a control signal to the hydrogen gas sensor 26. Based on the control signal from the controller 21, the hydrogen gas sensor 26 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 decomposer 6 based on the signal from the hydrogen gas sensor 26.

[0129] (Reciprocating engine operation) In the second fuel reforming system 1B, as in the first fuel reforming system 1A, the engine 3 executes a six-stroke cycle in order for the cracker 6 to crack the hydrocarbon fuel, i.e., executes the steps shown in FIG.

[0130] However, there are some differences in content from the first fuel reforming system 1A. First, the timing of reformed fuel injection is different. Second, there are two operating modes: normal mode and temperature rise mode. Figure 9 shows an example of the valve timing and valve lift of each valve, the timing of reformed fuel injection, and changes in the internal pressure of the cracker 6 in the normal mode and temperature rise mode.

[0131] The middle chart in Figure 9 shows the valve timing of each valve in normal mode M1. The lower chart shows the valve timing of each valve in temperature-raising mode M2. The upper chart shows the change in the internal pressure of cracker 6 in normal mode M1 and temperature-raising mode M2.

[0132] In the second fuel reforming system 1B, as indicated by symbol F2 in Fig. 9, reformed fuel is injected from the reforming injector 46 in the first half of the recompression stroke S4. This state is shown in Fig. 10. In the recompression stroke S4, the piston 32 rises and the on-off valve 38 opens. This causes the high-temperature combustion gas in the combustion chamber 3a to be introduced into the cracker 6 through the third port 37.

[0133] In the first half of the recompression stroke S4, the internal pressure of the combustion chamber 3a is still low. When the on-off valve 38 opens in this state, the high-temperature combustion gas in the combustion chamber 3a flows gently into the third port 37 because the pressure difference with the internal pressure of the cracker 6 is small.

[0134] In this state, when the reformed fuel is injected from the closed end of the closed pipe passage 66 toward the closed pipe passage 66, the reformed fuel quickly passes through the closed pipe passage 66 toward the third port 37. At this time, an increasing amount of combustion gas is flowing into the third port 37. The reformed fuel collides with the combustion gas.

[0135] This prevents the reformed fuel from entering the combustion chamber 3a. The reformed fuel is then effectively dispersed into the high-temperature combustion gas and vaporized. At this time, the valve lift of the on-off valve 38 may be relatively small. This allows the combustion gas flowing into the third port 37 to be maintained at a high momentum for a long period of time. This is advantageous for preventing the reformed fuel from leaking out and for homogenizing the fuel.

[0136] Then, the fuel gas flowing successively into the third port 37 pushes the high-temperature combustion gas containing the homogenized reformed fuel back into the closed-tube passage 66. The homogenized reformed fuel can be brought into efficient contact with the catalyst. In this state, the pressure inside the cracker 6 gradually increases. This promotes the reforming reaction. This allows hydrogen gas to be produced efficiently.

[0137] The second fuel reforming system 1B operates in a normal mode M1 or a temperature increase mode M2 ​​depending on the temperature of the cracker 6. Specifically, when the temperature of the cracker 6 is suitable for the reforming reaction, it operates in the normal mode M1. When the temperature of the cracker 6 is too low for the reforming reaction, it operates in the temperature increase mode M2.

[0138] In the normal mode M1, the basic operation is the same as that of the first fuel reforming system 1A, except for the injection timing of the reformed fuel. In contrast, in the boost mode M2, as shown by symbol F3 in Fig. 9, the reformed fuel is injected from the reforming injector 46 during the intake stroke S1 (pre-injection). At the same time, an operation to temporarily open the on-off valve 38 (temporary valve opening operation) is performed.

[0139] By pre-injecting, hydrocarbon fuel is supplied to the inside of the third port 37. A relatively small amount of pre-injection is sufficient. Then, during the intake stroke S1, intake air (fresh air) is introduced into the combustion chamber 3a. Accordingly, by opening the on-off valve 38 during the intake stroke S1, a portion of the intake air also flows into the inside of the support body 61.

[0140] The temporary valve opening operation may be performed instantaneously during the first half of the intake stroke S1. In other words, the valve lift of the on-off valve 38 may be small. The valve timing for the temporary valve opening operation is preferably immediately after the pre-injection, that is, immediately after the exhaust valve 36 closes. Because the exhaust valve 36 is closed, there is no exhaust from the combustion chamber 3a.

[0141] Meanwhile, the intake valve 34 begins to open widely, causing a large amount of intake air to flow into the third port 37, which has a relatively low internal pressure, and causing the injected reformed fuel to collide with the intake air.

[0142] As a result, in addition to the hydrocarbon fuel, air (oxygen) is supplied to the cracker 6, creating a condition in which reforming reactions (particularly partial oxidation reactions) are more likely to occur inside the cracker 6. The internal pressure of the cracker 6 also increases slightly. This condition continues through the intake stroke S1, compression stroke S2, and expansion stroke S3.

[0143] Since the cracker 6 is located near the combustion chamber 3a and heat is easily transferred thereto, the combustion in the combustion chamber 3a increases the temperature inside the cracker 6. Moreover, since the partial oxidation reaction is an exothermic reaction, the temperature inside the cracker 6 can be increased even further.

[0144] Furthermore, the inside of the cracker 6 can be maintained in a state where the partial oxidation reaction is likely to occur for a long period of time, thereby promoting the production of hydrogen gas and increasing the amount of hydrogen gas produced.

[0145] Thereafter, in the boost mode M2, the same operation as in the normal mode M1 is performed. However, the injection amount of the reformed fuel may be increased. Also, the valve lift amount of the on-off valve 38 may be increased.

[0146] Due to the preliminary injection and the temporary valve opening operation, the temperature and pressure inside the cracker 6 are set to conditions suitable for the partial oxidation reaction. Therefore, if the injection amount of reformed fuel is increased and the valve lift of the on-off valve 38 in the recompression stroke S4 is also increased, the partial oxidation reaction can be further promoted. The temperature inside the cracker 6 can be raised. The amount of hydrogen gas produced can be increased.

[0147] On the other hand, the amount of impurity gas generated also increases. However, if the valve lift amount in the re-expansion stroke S5 is increased, scavenging can be promoted. Even if the amount of impurity gas increases, it can be effectively removed from the inside of the cracker 6.

[0148] (Example of control by the second fuel reforming system) An example of control by the second fuel reforming system 1B is shown in Figure 11. It is assumed that the engine 3 performs combustion according to the six-stroke cycle described above.

[0149] The controller 21 reads various signals input from the accelerator sensor 23 and the like (step S11). While the engine 3 is operating, the controller 21 identifies the output required of the engine 3 based on the read signals and executes operation using the six-stroke cycle described above (Yes in step S12). Then, when the operation of the engine 3 ends, the control of the controller 21 also ends (No in step S12).

[0150] While the engine 3 is operating, the controller 21 estimates the hydrogen permeation amount Vt (the amount of hydrogen gas permeating the hydrogen-permeable membrane 63) based on a signal from the hydrogen gas sensor 26 and other factors. The controller 21 then determines whether the hydrogen permeation amount Vt is equal to or less than a predetermined lower limit Vmin that is preset in the controller 21 (step S13).

[0151] As a result, if the hydrogen permeation amount Vt is equal to or less than the lower limit value Vmin, the controller 21 adds "1" to the predetermined permeation lower limit number (the number of times the hydrogen permeation amount Vt is equal to or less than the lower limit value Vmin) counted by the controller 21 (step S14).

[0152] Thereafter, the controller 21 determines whether the lower limit number of permeations is less than a predetermined limit number N preset in the controller 21 (step S15). As a result, if the lower limit number of permeations is equal to or greater than the limit number N, the controller 21 suspends the production of hydrogen gas (step S16).

[0153] That is, since it is considered that the amount of impure gas remaining inside the cracker 6 has increased and the reforming reaction is being hindered, the controller 21 executes a process of repeating scavenging (complete scavenging process) without injecting reformed fuel. Specifically, the controller 21 determines whether or not a predetermined set time ts preset in the controller 21 has elapsed (step S17), and repeats operation by the six-stroke cycle until the set time ts has elapsed (No in step S17).

[0154] On the other hand, when the set time ts has elapsed, the controller 21 ends the complete scavenging process and resets the lower limit number of permeation times (step S18).

[0155] In the aforementioned step S13, if the hydrogen permeation rate Vt exceeds the lower limit value Vmin, i.e., if the generation of hydrogen gas is appropriate, the controller 21 determines, based on the signal from the decomposer temperature sensor 25, whether the temperature Td inside the decomposer 6 is equal to or higher than a predetermined judgment temperature Th preset in the controller 21 (step S19).

[0156] In step S15, the controller 21 also makes a similar determination when the lower limit number of permeation times is less than the limit number of times N, that is, when the complete scavenging process is not yet necessary. Furthermore, the controller 21 also makes a similar determination when the complete scavenging process has ended.

[0157] The threshold temperature Th corresponds to the lower limit of the temperature range suitable for the partial oxidation reaction. Therefore, if the temperature Td inside the decomposer 6 is lower than the threshold temperature Th, the partial oxidation reaction cannot be carried out properly. Therefore, when the temperature Td inside the decomposer 6 is lower than the threshold temperature Th (No in step S19), the controller 21 executes the temperature increase mode.

[0158] That is, the controller 21 executes the above-mentioned preliminary injection and temporary valve opening operation (steps S20, S21). As a result, the inside of the cracker 6 is maintained in a state suitable for the partial oxidation reaction. This allows the inside of the cracker 6 to be heated to the judgment temperature Th or higher. This allows the partial oxidation reaction to be carried out appropriately.

[0159] If the temperature Td inside the cracker 6 is equal to or higher than the judgment temperature Th (Yes in step S19), the controller 21 executes the normal mode. That is, the reformed fuel is injected in the recompression stroke S4 (step S22). Furthermore, even after the preliminary injection and temporary valve opening operation in the temperature increase mode are performed, the controller 21 injects the reformed fuel in the recompression stroke S4 (step S22), as in the normal mode. At this time, as described above, the injection amount may be increased, and the valve lift of the on-off valve 38 may also be increased. This allows the amount of hydrogen gas produced to be increased.

[0160] While the engine 3 is running, the controller 21 repeats this process.

[0161] <Third embodiment> 12 shows another example of a fuel reforming system (third fuel reforming system 1C) mounted on a vehicle. The third fuel reforming system 1C has both the same and different configurations as the first fuel reforming system 1A and the second fuel reforming system 1B. Therefore, the same reference numerals are used for the same configurations, and the description thereof will be simplified or omitted.

[0162] (Configuration of the third fuel reforming system) The third fuel reforming system 1C, like the first fuel reforming system 1A, has a reforming injector 46 arranged in the third port 37. It also has a reforming member 60 and a case 64 similar to those of the first fuel reforming system 1A. However, a mesh body 61a is attached to the openings on both sides of the support body 61.

[0163] Similar to the second fuel reforming system 1B, a tube 60a is provided inside the reforming member 60. The tube 60a is formed with a larger diameter (large diameter tube 60a) than the second fuel reforming system 1B. Both ends of the large diameter tube 60a are attached to the mesh bodies 61a. A large diameter communication passage 70 is formed inside the reforming member 60 by the large diameter tube 60a.

[0164] The cracker 6 is connected to the intake manifold 33a via a relay port 71. As a result, the third port 37 is in communication with the intake manifold 33a via the communication passage 70 and the relay port 71. A restriction valve 72 is installed between the intake manifold 33a and the communication passage 70.

[0165] The restriction valve 72 is, for example, a butterfly valve, a rotary valve, or a check valve. The restriction valve 72 allows flow from the intake manifold 33a side to the third port 37 side. That is, in the third fuel reforming system, the third port 37, the communication passage 70, and the relay port 71 can also function as the intake port 33. On the other hand, the restriction valve 72 does not allow flow at least from the third port 37 side to the intake manifold 33a side.

[0166] The illustrated restriction valve 72 is configured to be openable, closable, and blockable by a restriction valve opening / closing device 73. Opening the restriction valve 72 allows intake air to flow from the intake manifold 33a side to the third port 37 side. Closing the restriction valve 72 blocks the flow path. This prevents air from flowing from the intake manifold 33a side to the third port 37 side, as well as from the third port 37 side to the intake manifold 33a side.

[0167] In the third fuel reforming system 1C, as shown by the phantom lines in FIG. 4, a regulating valve opening / closing device 73 is added to the control system 2 of the first fuel reforming system 1A, together with a decomposer temperature sensor 25 and a hydrogen gas sensor 26.

[0168] Specifically, a restriction valve opening / closing device 73 is further electrically connected to the controller 21. The controller 21 outputs a control signal to the restriction valve opening / closing device 73 in accordance with the operating state of the engine 3. The restriction valve opening / closing device 73 opens and closes the restriction valve 72 based on the control signal from the controller 21, which includes a signal from the crank angle sensor 24.

[0169] (Reciprocating engine operation) In the third fuel reforming system 1C, as in the first fuel reforming system 1A, the engine 3 executes a six-stroke cycle in order for the cracker 6 to crack the hydrocarbon fuel, i.e., executes the steps shown in FIG.

[0170] However, the content thereof differs from that of the first fuel reforming system 1 A. The third fuel reforming system 1 C has an operation mode (charging efficiency improvement mode) for improving the charging efficiency.

[0171] This engine 3 has only one intake port 33. Therefore, for example, when the engine 3 is operated in a high load / high rotation range, there is a risk that the charging efficiency may be insufficient. Therefore, the third fuel reforming system 1C compensates for this insufficient charging efficiency by using a charging efficiency improvement mode.

[0172] FIG. 13 shows an example of the changes in the valve timing and valve lift of each valve, the injection timing of the reformed fuel, and the internal pressure of the cracker 6 in the charging efficiency improvement mode.

[0173] In the charging efficiency improvement mode, the restriction valve 72 is opened prior to the intake stroke S1. Then, with the restriction valve 72 open, the on-off valve 38 is opened during the intake stroke S1. FIG. 14 shows an example of the state of the intake stroke S1 in the charging efficiency improvement mode. The valve lift of the on-off valve 38 is set according to the required charging efficiency. Normally, the on-off valve 38 is opened in the same way as the intake valve 34.

[0174] As a result, in addition to the intake air introduced through the intake port 33, the intake air is introduced into the combustion chamber 3a through a path consisting of the relay port 71, the communication passage 70, and the third port 37. As a result, the filling efficiency can be increased.

[0175] Furthermore, when intake air is introduced from one location through the intake port 33, a strong flow (especially a swirl flow) is formed in the combustion chamber 3a. However, by introducing intake air from two locations, this flow can be alleviated. Therefore, the charging efficiency improvement mode improves combustion performance.

[0176] During the intake stroke S1, the piston descends, so the internal pressure of the cracker 6 in communication with the intake port 33 dynamically becomes negative. When the intake stroke S1 ends and the compression stroke S2 ​​begins, the on-off valve 38 closes along with the intake valve 34. As a result, the internal pressure of the cracker 6 returns to positive. The interior of the cracker 6 then becomes filled with intake air (air).

[0177] In the charging efficiency improvement mode, as in the second fuel reforming system 1B, reformed fuel is injected in the first half of the recompression stroke S4, as indicated by symbol F4 in Fig. 13. In the recompression stroke S4, the combustion gas in the combustion chamber 3a is compressed by the rise of the piston 32. Then, the on-off valve 38 opens, and the compressed combustion gas is introduced into the cracker 6 through the third port 37.

[0178] At this time, if the regulating valve 72 is open, the combustion gas quickly flows into the third port 37. Therefore, the injected reformed fuel is effectively dispersed in the combustion gas. Then, the combustion gas in a homogenized reformed fuel state is introduced into the cracker 6. The inside of the cracker 6 is filled with the high-temperature combustion gas and air (oxygen) necessary for the reforming reaction (including the partial oxidation reaction). Therefore, the reforming reaction can be promoted.

[0179] After this, the restriction valve 72 is closed. The restriction valve 72 may be closed before the recompression stroke S4. With the restriction valve 72 closed, the third fuel reforming system 1C has the same configuration as the first fuel reforming system 1A, except for the presence of the communication passage 70. Therefore, in this case, combustion can be performed in the same manner as the first fuel reforming system 1A.

[0180] (Example of control by the third fuel reforming system) 15A shows an example of control by the third fuel reforming system 1 C. It is assumed that the engine 3 performs combustion according to the six-stroke cycle described above.

[0181] The controller 21 reads various signals input from the accelerator sensor 23 and the like (step S31). While the engine 3 is operating, the controller 21 identifies the output required of the engine 3 based on the read signals and executes operation using the six-stroke cycle described above (Yes in step S32). Then, when the operation of the engine 3 ends, the control of the controller 21 also ends (No in step S32).

[0182] While the engine 3 is operating, the controller 21 estimates the hydrogen permeation amount Vt based on the signal from the hydrogen gas sensor 26, etc. Then, the controller 21 determines whether the hydrogen permeation amount Vt is equal to or less than a predetermined lower limit value Vmin that is preset in the controller 21 (step S33).

[0183] As a result, if the hydrogen permeation amount Vt is equal to or less than the lower limit value Vmin, the controller 21 adds "1" to the predetermined lower limit number of permeation attempts counted by the controller 21 (step S34).

[0184] Thereafter, the controller 21 determines whether the permeation lower limit number is less than a predetermined limit number N preset in the controller 21 (step S35). If the permeation lower limit number is equal to or greater than the limit number N, the controller 21 suspends the generation of hydrogen gas (step S36). Then, the controller 21 executes the complete scavenging process.

[0185] That is, it is determined whether a predetermined set time ts preset in the controller 21 has elapsed (step S37), and operation in a six-stroke cycle is repeated until the set time ts has elapsed (No in step S37).

[0186] On the other hand, when the set time ts has elapsed, the controller 21 ends the complete scavenging process and resets the lower limit number of permeation times (step S38).

[0187] In the above-mentioned step S33, if the hydrogen permeation rate Vt exceeds the lower limit value Vmin, that is, if the generation of hydrogen gas is appropriate, the controller 21 estimates the actual filling efficiency (actual filling efficiency) based on various signals and determines whether the actual filling efficiency is insufficient compared to the required appropriate filling efficiency (required filling efficiency) (step S39).

[0188] In step S35, the controller 21 also makes a similar determination when the lower limit number of permeation times is less than the limit number of times N, that is, when the complete scavenging process is not yet necessary. Furthermore, the controller 21 also makes a similar determination when the complete scavenging process has ended.

[0189] As a result, if it is determined that the actual charging efficiency is insufficient for the required charging efficiency, the controller 21 executes operation in the charging efficiency improvement mode (step S40).

[0190] 15B shows a control example of the charging efficiency improvement mode. In the charging efficiency improvement mode, the controller 21 opens the restriction valve 72 prior to the intake stroke S1 (step S41). Thereafter, the controller 21 opens the on-off valve 38 during the intake stroke S1 (step S42), as shown in FIG.

[0191] As a result, as shown in Figure 14, intake air is introduced into the combustion chamber 3a through two paths. As a result, the charging efficiency can be increased and the required charging efficiency can be achieved. The strong flow in the combustion chamber 3a can be alleviated. Therefore, the charging efficiency improvement mode improves combustion performance. The temperature of the combustion gas rises. Then, the inside of the cracker 6 becomes filled with intake air.

[0192] Thereafter, the controller 21 outputs a control signal to the reforming injector 46 to inject the reformed fuel in the first half of the recompression stroke S4 (step S43). Because the restriction valve 72 is open, when the on-off valve 38 opens, the high-temperature combustion gas flows vigorously into the third port 37. Therefore, the injected reformed fuel is effectively dispersed in the combustion gas.

[0193] The high-temperature combustion gas containing the homogenized reformed fuel is then introduced into the cracker 6. The inside of the cracker 6 is filled with the high-temperature combustion gas and air (oxygen) necessary for the reforming reaction, thereby accelerating the reforming reaction.

[0194] The controller 21 closes the regulating valve 72 at a predetermined timing during the recompression stroke S4 (step S44). This timing is a timing at which the combustion gas containing the reformed fuel does not flow out from the cracker 6 toward the relay port 71. For example, the regulating valve 72 may be closed simultaneously with or immediately after the injection of the reformed fuel. As described above, the regulating valve 72 may be closed before the recompression stroke S4.

[0195] The controller 21 may open and close the restriction valve 72 in the re-expansion stroke S5. If the restriction valve 72 is open in the re-expansion stroke S5, the inside of the cracker 6 can be effectively scavenged. The reforming reaction can be promoted. Furthermore, the pumping loss of the engine 3 is reduced, and energy loss can also be suppressed.

[0196] On the other hand, if it is determined that the actual filling efficiency is not insufficient compared to the required filling efficiency, that is, that an appropriate filling efficiency is ensured (No in step S39), the controller 21 determines whether the temperature Td inside the cracker 6 is equal to or higher than the predetermined judgment temperature Th described above, based on the signal from the cracker temperature sensor 25 (step S45).

[0197] As a result, if the temperature Td inside the cracker 6 is equal to or higher than the judgment temperature Th (Yes in step S45), that is, if the temperature inside the cracker 6 is suitable for the reforming reaction, the controller 21 injects the reformed fuel in the latter half of the recompression stroke S4, as in the first fuel reforming system 1A (step S46).

[0198] On the other hand, if the temperature Td inside the cracker 6 is lower than the judgment temperature Th, that is, if the temperature is insufficient to properly carry out the reforming reaction, the controller 21 executes the charging efficiency improvement mode (No in step S45). Executing the charging efficiency improvement mode can increase the temperature inside the cracker 6. This can promote the generation of hydrogen gas.

[0199] After steps S40 and S46, the process returns to the step before step S32. That is, while the engine 3 is running, the controller 21 repeats this series of processes.

[0200] The disclosed technology is not limited to the above-described embodiments, but also includes various other configurations. For example, the contents of the embodiments may be 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]

[0201] 1A~1C Fuel reforming system 2. Control System 3 Reciprocating engine 3a Combustion chamber 6 Decomposer 21 Controller 31 cylinders 32 piston 33 Intake port 33a intake manifold 33b opening 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 Direct Injector 45 Hydrocarbon fuel supply unit 46 Modified Injector 60 Modified materials 61 Support 62 Support 63 Hydrogen permeable membrane 64 cases 65 Communication space 66 Closed Pipe Passage 72 Regulating valve 73 Regulatory valve opening and closing device

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, The reciprocating engine is 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 fuel 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 cracker communicating with the combustion chamber through a third port that can be opened and closed, for cracking the hydrocarbon fuel into carbon and hydrogen gas and storing the carbon; a hydrocarbon fuel supply unit that supplies the hydrocarbon fuel to the cracker; Equipped with the cracker is configured to use heat and pressure of combustion gas generated in the combustion chamber to decompose the hydrocarbon fuel into the carbon and the hydrogen gas, and separate the hydrogen gas by allowing it to permeate through a hydrogen-permeable membrane; The decomposer is disposed adjacent to the intake port in a state of communication with the intake port via the hydrogen-permeable membrane, and the separated hydrogen gas can be supplied as fuel to the combustion chamber through the intake port.

2. 2. The fuel reforming system of claim 1, a first injector is attached to the third port to inject the hydrocarbon fuel toward the inside of the third port; A fuel reforming system in which the hydrocarbon fuel is injected from the first injector in the latter half of the recompression stroke with the third port open.

3. 2. The fuel reforming system of claim 1, The decomposer comprises: a case disposed along the intake port; a modifying member housed in the case so as to extend along the case; a closed-tube passage provided in the center of the reforming member, the open end of the closed-tube passage communicating with the third port; and a second injector is attached to the cracker to inject the hydrocarbon fuel from a closed end side of the closed pipe passage toward the closed pipe passage, A fuel reforming system in which the hydrocarbon fuel is injected from the second injector in the first half of the recompression stroke with the third port open.

4. 4. The fuel reforming system according to claim 2 or 3, A fuel reforming system wherein the third port is opened during the re-expansion stroke.

5. 3. The fuel reforming system according to claim 1 or 2, the cracker has a communication passage therein that communicates the third port with an intake air supply section located upstream of the intake port, A fuel reforming system in which a regulating valve capable of blocking a flow from the third port side toward the intake air supply part side is installed between the intake air supply part and the communication passage.

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