CN114810436A

CN114810436A - Fuel reforming device

Info

Publication number: CN114810436A
Application number: CN202210048660.1A
Authority: CN
Inventors: 工藤知英
Original assignee: Honda Motor Co Ltd
Current assignee: Honda Motor Co Ltd
Priority date: 2021-01-22
Filing date: 2022-01-17
Publication date: 2022-07-29
Anticipated expiration: 2042-01-17
Also published as: JP2022112890A; JP7154326B2; CN114810436B

Abstract

A fuel reforming device (100) for reforming fuel by an oxidation reaction is provided with a double-layer tube (19) having an outer tube (191) and an inner tube (192) extending in the vertical direction, and a cylindrical space (193) is formed between the outer tube (191) and the inner tube (192). The outer pipe (191) is provided with an introduction hole (194) penetrating the lower part of the outer pipe (191) to introduce fuel and air into the cylindrical space (193), an air discharge hole (195) penetrating the upper part of the outer pipe (191) to discharge air from the cylindrical space (193), and fuel discharge holes (196a, 196b) penetrating between the introduction hole (194) and the air discharge hole (195) of the outer pipe (191) to discharge fuel from the cylindrical space (193). The upper end (193a) and the lower end (193b) of the cylindrical space are closed. The double tube (19) is configured such that the fuel supplied through the introduction hole (194) undergoes an oxidation reaction in the presence of a catalyst in a cylindrical space extending from the lower end (193b) to the fuel discharge holes (196a, 196 b).

Description

Fuel reforming device

Technical Field

The present invention relates to a fuel reforming apparatus for reforming fuel supplied to a compression ignition engine.

Background

Conventionally, there is known an apparatus for reforming a fuel by oxidizing the fuel with an oxidizing agent (see, for example, patent document 1). The apparatus described in patent document 1 is configured as a double-tube reactor in which a reaction field is formed between an outer tube member and an inner tube member which are coaxially provided, a mixed gas of fuel and air is supplied as a reactant, and a mixed gas of reformed fuel and air is discharged as a product.

In the apparatus described in patent document 1, since the reformed fuel and air are discharged as a mixed gas, a gas-liquid separator needs to be provided in a stage subsequent to the double-tube reactor in order to obtain the reformed fuel, and the configuration of the entire fuel reforming apparatus becomes complicated.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2018-178974 (JP 2018-178974A).

Disclosure of Invention

One aspect of the present invention is a fuel reforming apparatus for reforming fuel by an oxidation reaction, including a double-layer tube having an outer tube and an inner tube extending in a vertical direction, and a cylindrical space formed between the outer tube and the inner tube. The outer pipe is provided with an introduction hole penetrating a lower portion of the outer pipe to introduce fuel and air into the cylindrical space, an air discharge hole penetrating an upper portion of the outer pipe to discharge air from the cylindrical space, and a fuel discharge hole penetrating between the introduction hole and the air discharge hole of the outer pipe to discharge fuel from the cylindrical space. The upper and lower ends of the cylindrical space are closed. The double tube is configured such that the fuel supplied through the introduction hole undergoes an oxidation reaction in the presence of a catalyst in a cylindrical space from the lower end to the fuel discharge hole.

Drawings

The objects, features and advantages of the present invention are further clarified by the following description of the embodiments in relation to the accompanying drawings.

Fig. 1 is a diagram schematically showing an example of the internal structure of an engine to which a fuel reforming apparatus according to an embodiment of the present invention is applied.

Fig. 2 is a graph for explaining the relationship between the octane number of fuel and the ignitability.

Fig. 3 is a diagram for explaining a chemical reaction when reforming fuel.

Fig. 4 is a diagram for explaining the degree of progress of the oxidation reaction of the fuel.

Fig. 5 is a diagram schematically showing an example of the configuration of the fuel reforming apparatus according to the embodiment of the present invention.

Fig. 6 is a diagram schematically showing an example of the configuration around the change-over valve of the fuel reforming apparatus of fig. 5.

Fig. 7 is a view schematically showing an example of the configuration of the reformer of fig. 5.

Fig. 8A is a sectional view of the reformer of fig. 5.

Fig. 8B is a diagram illustrating a modification of fig. 8A.

Fig. 9 is a block diagram schematically showing an example of the configuration of a main part around a controller of the fuel reforming apparatus of fig. 5.

Fig. 10A is a flowchart showing an example of the reforming conversion process executed by the fuel reforming apparatus according to the embodiment of the present invention.

Fig. 10B is a diagram illustrating a modification of fig. 10A.

Fig. 11A is a flowchart illustrating an example of the reforming rate adjustment process executed by the fuel reforming apparatus according to the embodiment of the present invention.

Fig. 11B is a diagram illustrating a modification of fig. 11A.

Fig. 12 is a diagram showing a modification of fig. 5.

Fig. 13 is a block diagram schematically showing an example of the configuration of a main part around a controller of the fuel reforming apparatus of fig. 12.

Detailed Description

Embodiments of the present invention will be described below with reference to fig. 1 to 13. A fuel reforming device according to an embodiment of the present invention is applied to a compression ignition engine mounted on a vehicle or the like, and reforms fuel supplied from a fuel tank to the engine as necessary.

The average temperature of the earth is kept warm by greenhouse gases in the atmosphere, which is suitable for living things. Specifically, the greenhouse gas absorbs a part of heat radiated from the surface heated by the sunlight to the space, and radiates the heat to the surface again, thereby keeping the atmosphere in a warm state. When the concentration of greenhouse gases in the atmosphere increases as described above, the average temperature of the earth rises (global warming).

Among greenhouse gases, the concentration of carbon dioxide in the atmosphere, which has a large influence on global warming, is determined by the balance between carbon fixed on the ground or underground in the form of plants or fossil fuels and carbon present in the atmosphere in the form of carbon dioxide. For example, when carbon dioxide in the atmosphere is absorbed by photosynthesis during plant growth, the concentration of carbon dioxide in the atmosphere decreases, and when carbon dioxide is discharged to the atmosphere by combustion of fossil fuel, the concentration of carbon dioxide in the atmosphere increases. In order to suppress global warming, it is necessary to reduce the amount of carbon emission by replacing fossil fuels with renewable energy sources such as sunlight and wind power, and renewable fuels derived from biomass and the like.

As such renewable fuels, low octane gasoline obtained by FT (Fischer-Tropsch) synthesis is becoming popular. Low octane gasoline has high ignitability and can be used in compression ignition engines, but in the course of its popularization, there are also unsold areas. On the other hand, gasoline having a normal octane number, which is used for a spark ignition engine that has been widely used at present, has low ignitability, and when it is used as it is in a compression ignition engine, it is difficult to ensure exhaust gas performance, and there is a possibility that the gasoline may not ignite. Therefore, in the present embodiment, in order to reform the fuel supplied from the fuel tank to the engine as needed, both the low octane gasoline and the normal octane gasoline are compression-ignited in a single engine, and the fuel reforming apparatus is configured as follows.

Fig. 1 is a diagram schematically showing an example of the internal configuration of an engine 1 to which a fuel reforming apparatus according to an embodiment of the present invention is applied. The engine 1 is a compression ignition gasoline engine, and is mounted on a vehicle, for example.

As shown in fig. 1, the engine 1 has a cylinder block 3 forming a cylinder 2 and a cylinder head 4 covering an upper portion of the cylinder block 3. An intake port 5 through which intake air entering the engine 1 passes and an exhaust port 6 through which exhaust gas discharged from the engine 1 passes are provided in the cylinder head 4. An intake valve 7 for opening and closing the intake port 5 is provided in the intake port 5, and an exhaust valve 8 for opening and closing the exhaust port 6 is provided in the exhaust port 6. The intake valve 7 and the exhaust valve 8 are opened and closed by a valve mechanism not shown.

A piston 9 slidable in the cylinder 2 is disposed in each cylinder 2, and a combustion chamber 10 is formed facing the piston 9. An injector 11 is provided in the engine 1 so as to face the combustion chamber 10, and fuel is injected from the injector 11 into the combustion chamber 10. The operation of the injector 11 (fuel injection timing (valve opening timing) and fuel injection amount (valve closing timing)) is controlled by an engine ECU (Electronic Control Unit) 200 (fig. 7). The engine 1 is further provided with a cylinder pressure sensor 12, which is constituted by a piezoelectric crystal type pressure sensor or the like, and detects the pressure in the combustion chamber 10.

When the intake port 5 is opened, the exhaust port 6 is closed, and the piston 9 descends, air (fresh air) is drawn from the intake port 5 into the combustion chamber 10 (intake stroke). When the intake port 5 and the exhaust port 6 are closed and the piston 9 rises, air in the combustion chamber 10 is compressed, and the pressure in the combustion chamber 10 gradually rises (compression stroke). When fuel is injected from the injector 11 into the combustion chamber 10 in the vicinity of the compression top Dead center tdc (top Dead center), a mixture of the fuel and air in the combustion chamber 10 is compressed, the pressure in the combustion chamber 10 gradually rises, and the fuel is combusted by self-ignition. When the fuel starts self-ignition in the combustion chamber 10, the pressure in the combustion chamber 10 rises sharply, and the piston 9 descends (expansion stroke). When the intake port 5 is closed, the exhaust port 6 is opened, and the piston 9 is raised, air (exhaust gas) in the combustion chamber 10 is discharged from the exhaust port 6 (exhaust stroke).

The crankshaft 14 is rotated by the connecting rod 13 by the reciprocating motion of the piston 9 along the inner wall of the cylinder 2. A crank angle sensor 15 that detects a rotation angle (crank angle) of the crankshaft 14 is further provided to the crankshaft 14 of the engine 1. Further, a magnetostrictive torque sensor 16, for example, that detects the output torque of the engine 1 is provided. The engine 1 is further provided with a water temperature sensor or the like for detecting the temperature of the coolant of the engine 1 (engine water temperature), and illustration thereof is omitted.

Fig. 2 is a diagram for explaining the relationship between the octane number and the ignitability of the fuel, and shows an example of the ignition timing ti of a plurality of types of fuels having different octane numbers as a crank angle "°" with reference to the compression top dead center TDC. More specifically, an example of a crank angle at which self-ignition of the fuel starts in the combustion chamber 10 and the pressure in the combustion chamber 10 rises sharply, which is determined based on the pressure in the combustion chamber 10 detected by the in-cylinder pressure sensor 12 and the crank angle detected by the crank angle sensor 15, is shown.

As shown in fig. 2, in the case of the fuel having a low ignitability with an octane number exceeding 70, the ignition timing ti is significantly later than the compression top dead center TDC, and in this case, the maximum thermal efficiency of the engine 1 is significantly reduced, and the combustion becomes unstable. In order to ensure sufficient combustion performance of the engine 1, it is necessary to reform the fuel when the ignition timing ti is equal to or greater than a predetermined crank angle ti0 (e.g., 10 °).

Fig. 3 is a diagram for explaining a chemical reaction in reforming fuel. Fuels containing hydrocarbons as their main component can be oxidized and reformed to produce peroxides by using a catalyst such as N-hydroxyphthalimide (NHPI), thereby improving their ignitability. Specifically, NHPI readily abstracts a hydrogen atom from an oxygen molecule to generate a phthalimide-N-oxygen (PINO) radical. The PINO radical abstracts a hydrogen atom from a hydrocarbon (RH) contained in the fuel to produce an alkyl group (R · s). The alkyl group combines with the oxygen molecule to form an alkylperoxide radical (ROO.). The alkyl peroxy radical abstracts a hydrogen atom from a hydrocarbon contained in the fuel to generate alkyl hydroperoxide (ROOH) as a peroxide.

Fig. 4 is a diagram for explaining the degree of progress of the oxidation reaction of the fuel, and shows an example of changes in the peroxide concentration c1 and the oxide concentration c2 when the oxidation reaction proceeds. As shown in fig. 4, the peroxide concentration c1 increases as the oxidation reaction proceeds, and as the oxidation reaction proceeds further, the peroxide is decomposed into oxides such as ethanol, aldehyde, ketone, etc., the peroxide concentration c1 decreases and the oxide concentration c2 increases.

In order to increase the peroxide concentration c1 in the fuel and improve the ignitability of the fuel until the fuel reaches a state suitable for compression ignition, it is necessary to adjust the degree of progress of the oxidation reaction within an appropriate range. Specifically, it is necessary to adjust the octane number of the fuel after oxidative reforming (reformed fuel) to 70 or less (fig. 2) and the peroxide concentration c1 in the reformed fuel to a predetermined concentration c0 (for example, 0.15mol/l) or more. The peroxide concentration c1 in the reformed fuel can be detected by a suitable concentration sensor.

When the peroxide concentration c1 is lower than the predetermined concentration c0, the peroxide concentration c1 is equal to or higher than the oxide concentration c2 when the degree of progress of the oxidation reaction is insufficient, and the peroxide concentration c1 is lower than the oxide concentration c2 when the degree of progress of the oxidation reaction is excessive. When the hydrocarbon contained in the fuel is decomposed into an oxide, the calorific value of the reformed fuel decreases, and the engine output decreases. That is, the output torque of the engine 1 is proportional to the product of the amount of heat generation of the reformed fuel and the fuel injection amount. The oxide concentration c2 can be estimated based on the fuel injection amount and the output torque of the engine 1.

Fig. 5 to 9 are diagrams schematically showing an example of the configuration of a fuel reforming apparatus (hereinafter referred to as an apparatus) 100 according to an embodiment of the present invention. As shown in fig. 5, the apparatus 100 includes a reforming unit 20 and a controller 50, wherein the reforming unit 20 is provided in a fuel supply path 18 from a fuel tank 17 to an injector 11 of the engine 1, and includes a reformer 19 that oxidatively reforms fuel, and the controller 50 controls the operation of the reforming unit 20.

The fuel tank 17 is provided with a remaining amount meter 17a for detecting the remaining amount of the fuel stored in the fuel tank 17. The residual amount meter 17a is formed of, for example, a float-type level sensor, and outputs a signal corresponding to the level of the fuel in the fuel tank 17.

As shown in fig. 5 and 6, the fuel supply path 18 has a 1 st path 18a from the fuel tank 17 to the injector 11 of the engine 1 through the reformer 19 and a 2 nd path 18b from the fuel tank 17 to the injector 11 of the engine 1 bypassing the reformer 19.

The reforming unit 20 includes a fuel pump 21a that pumps up the fuel stored in the fuel tank 17, a flow meter 22 that detects a flow rate of the fuel, an on-off valve 23 that opens and closes the 1 st path 18a, and a mixer 24 in the 1 st path 18a from the fuel tank 17 to the reformer 19. A 1 st path 18a from the reformer 19 to the injector 11 of the engine 1 is provided with a concentration sensor 26 for detecting a peroxide concentration c1 in the reformed fuel, and a high-pressure pump 27 for pressurizing the fuel. The concentration sensor 26 is, for example, a capacitance-type concentration sensor that measures the dielectric constant of the reformed fuel, and outputs a signal corresponding to the peroxide concentration c1 in the reformed fuel.

As shown in fig. 5 and 6, the reforming unit 20 also has a fuel pump 21b that pumps up the fuel stored in the fuel tank 17 on the 2 nd path 18b, and the fuel pumped up by the fuel pump 21b is supplied to the high-pressure pump 27 via the 2 nd path 18 b. The operation (fuel pressure) of high-pressure pump 27 is controlled by engine ECU200 (fig. 9).

As shown in fig. 6, the reforming unit 20 has a switching valve 28 that switches the fuel supply path 18 to either one of the 1 st path 18a and the 2 nd path 18 b. When the fuel supply path 18 is switched to the 1 st path 18a, the fuel stored in the fuel tank 17 is supplied to the reformer 19 and reformed by the operation of the high-pressure pump 27, and the reformed fuel is supplied to the injector 11 by the high-pressure pump 27 and injected into the combustion chamber 10 (fig. 1). When the fuel supply path 18 is switched to the 2 nd path 18b, the fuel stored in the fuel tank 17 is supplied to the injector 11 by the high-pressure pump 27 without being reformed in the reformer 19 in accordance with the operation of the high-pressure pump 27, and is injected into the combustion chamber 10 (fig. 1).

As shown in fig. 5, the reforming unit 20 includes an air cleaner 31, an air pump 32 for sending air under pressure, a flow meter 33 for detecting the flow rate of air, and an on-off valve 34 for opening and closing the air supply path 30, in the air supply path 30 for supplying air to the mixer 24. The fuel supplied to the mixer 24 through the fuel supply path 18 (1 st path 18a) in accordance with the operation of the high-pressure pump 27 and the air supplied to the mixer 24 through the air supply path 30 in accordance with the operation of the air pump 32 are mixed in the mixer 24 and supplied to the reformer 19.

Fig. 7 is a diagram schematically showing an example of the configuration of the reformer 19. As shown in fig. 7, the reformer 19 includes an outer pipe 191 and an inner pipe 192 extending in the vertical direction, and is configured as a double-pipe reactor in which a cylindrical space 193 is formed between the outer pipe 191 and the inner pipe 192.

The outer tube 191 of the reformer 19 is provided with an introduction hole 194 penetrating the lower portion of the outer tube 191 so that the fuel and air mixed in the mixer 24 (fig. 5) are introduced into the cylindrical space 193 through the 1 st path 18 a. An air discharge hole 195 is provided to penetrate the upper portion of the outer tube 191 so that air is discharged from the cylindrical space 193 through the 3 rd path 18 c. Further,

fuel discharge holes

196a and 196b are provided between the introduction hole 194 and the air discharge hole 195 penetrating the outer tube 191 so that the fuel is discharged from the cylindrical space 193 through the 1 st passage 18 a. The air discharged from the cylindrical space 193 is supplied to the intake port 5 of the engine 1 through the 3 rd passage 18c (fig. 1), and is taken into the combustion chamber 10 together with the fresh air.

The space radially inside the inner tube 192 of the reformer 19 constitutes a circulation path 197 through which engine cooling water as a heat transfer medium circulates. That is, the cooling water of the engine 1 after the warm-up is supplied from below the circulation path 197, raises the temperature of the reformer 19, and circulates to the engine 1 from above the circulation path 197. The temperature of the engine water after warm-up is maintained in a temperature range of 70 to 110 ℃, and therefore, the oxidation reaction of the fuel is appropriately promoted.

The cylindrical space 193 of the reformer 19 is closed at an upper end 193a and a lower end 193 b. The fuel (liquid) introduced into the cylindrical space 193 through the introduction hole 194 flows through the cylindrical space 193 extending from the lower end 193b to the

fuel discharge holes

196a and 196b, and is discharged through the

fuel discharge holes

196a and 196 b. The air (gas) introduced into the cylindrical space 193 through the introduction hole 194 passes through the cylindrical space 193 from the lower end 193b to the upper end 193a, and is discharged through the air discharge hole 195.

The cylindrical space 193 extending from the lower end 193b to the

fuel discharge holes

196a and 196b corresponding to the liquid surface of the fuel functions as a reaction chamber 198 in which the fuel reacts with oxygen in the air (oxidation reaction) to generate reformed fuel. On the other hand, the cylindrical space 193 from the

fuel discharge holes

196a and 196b corresponding to the liquid surface of the fuel to the upper end 193a functions as a gas-liquid separation chamber 199 for performing gas-liquid separation.

Fig. 8A and 8B are sectional views of the reformer 19 shown in fig. 7 taken along line VII-VII, showing a section of a portion corresponding to the reaction chamber 198. As shown in fig. 8A, a catalyst 190 (wall surface support) such as an NHPI catalyst is supported on an inner wall 191a of the outer tube 191 and an outer wall 192a of the inner tube 192, which constitute the inner wall of the reaction chamber 198, to promote the oxidation reaction in the reaction chamber 198.

The reformer 19 can be configured such that the gap g between the inner wall 191a of the outer tube 191 and the outer wall 192a of the inner tube 192 is 2 times or less, for example, 2 times the quenching distance. Accordingly, the inner wall 191a of the outer tube 191 or the outer wall 192a of the inner tube 192 inevitably exists within the range of the quenching distance of the reactant, and thus the safety of the reformer 19 can be improved. In order to further improve the safety, the reformer 19 may be configured such that the gap g is equal to or smaller than the maximum safety gap, for example, the maximum safety gap. By configuring the reaction chamber 198 in which the oxidation reaction of the fuel proceeds with the maximum safety gap, for example, even if a flame enters from an adjacent device, the fire can be immediately extinguished, and therefore, the safety of the reformer 19 can be further improved.

As shown in fig. 8B, the reaction chamber 198 of the reformer 19 may be filled with a solid catalyst 190 in which a catalyst such as an NHPI catalyst is supported (surface-supported) on a carrier such as a silicon wafer instead of wall-surface support, and the gap g of the solid catalyst 190, which is a reaction field of the oxidation reaction, may be set to 2 times the quenching distance or the maximum safety gap.

As shown in fig. 5 and 7, the outer tube 191 of the reformer 19 is provided with a plurality of (2 in the example shown in the figure)

fuel discharge holes

196a, 196b in the vertical direction, and the reforming unit 20 has a switch valve 29 that switches the

fuel discharge holes

196a, 196 b. When the

fuel discharge holes

196a, 196b are switched, the liquid level height of the fuel changes, the heights h1a, h1b of the reaction chamber 198 change, and the heights h2a, h2b of the gas-liquid separation chamber 199 change. By changing the heights h1a and h1b of the reaction chamber 198, the reaction time of the oxidation reaction in the reformer 19 can be adjusted.

The reformer 19 is configured such that the heights h2a, h2b of the gas-liquid separation chamber 199 from the

fuel discharge holes

196a, 196b to the upper end 193a are equal to or greater than the height h0 at which gas-liquid separation can be performed. The inner wall 191a of the outer tube 191 and the outer wall 192a of the inner tube 192, which constitute the inner wall of the gas-liquid separation chamber 199, are subjected to surface treatment such as teflon (registered trademark) processing. By performing such surface treatment, the capillary phenomenon in the gas-liquid separation chamber 199 can be suppressed, and the height h0 at which gas-liquid separation can be performed is minimized.

Fig. 9 is a block diagram schematically showing an example of the configuration of a main part around the controller 50. As shown in fig. 9, the controller 50 is constituted by an Electronic Control Unit (ECU) including a computer having a CPU (central processing unit) 51, a memory 52 such as a ROM (read only memory) or a RAM (random access memory), and other peripheral circuits (not shown) such as an I/O (input/output) interface.

The controller 50 is electrically connected to sensors such as the cylinder pressure sensor 12, the crank angle sensor 15, the torque sensor 16, the

flow meters

22 and 33, the residual amount meter 17a, and the concentration sensor 26, and receives signals from the respective sensors. The controller 50 is electrically connected to actuators such as the

fuel pumps

21a and 21b, the on-off

valves

23 and 34, the switching

valves

28 and 29, and the air pump 32, and sends control signals from the controller 50 to the respective actuators. Controller 50 is configured to be able to communicate with other vehicle-mounted ECUs such as engine ECU200 via a communication Network such as a CAN (Controller Area Network) mounted on the vehicle.

The memory 52 stores various control programs, threshold values used in the programs, and other information. The CPU51 has a functional configuration including a reforming unit control unit 53 that controls the operation of the reforming unit 20, a fuel supply determination unit 54, a reforming non-determination unit 55, and an oxidation progress degree estimation unit 56. That is, the CPU51 functions as the reforming-unit control unit 53, the fuel-supply determining unit 54, the whether reforming is performed determining unit 55, and the oxidation progress degree estimating unit 56.

The fuel cut determination unit 54 determines whether or not the fuel is supplied to the fuel tank 17 based on the change in the remaining amount of the fuel stored in the fuel tank 17 detected by the remaining amount meter 17 a. For example, each time the vehicle and the controller 50 are started, the fuel remaining amount of the previous time is compared with the fuel remaining amount of the present time, and thereby whether or not the fuel is supplied to the fuel tank 17 is determined. Whether or not fuel is supplied may be determined by detecting opening and closing of the fuel lid.

When the fuel cut determination unit 54 determines that the fuel is fed, the whether or not reforming determination unit 55 determines whether or not reforming is necessary based on the ignition timing ti of the fuel. Specifically, the ignition timing ti of the fuel is calculated based on the pressure in the combustion chamber 10 detected by the in-cylinder pressure sensor 12 and the crank angle detected by the crank angle sensor 15, and when the ignition timing ti is equal to or greater than a predetermined crank angle ti0 (fig. 2), it is determined that reforming is necessary. When the ignition timing ti is lower than the prescribed crank angle ti0, it is determined that reforming is not required.

The whether reforming determination portion 55 may also determine whether reforming is required based on the peroxide concentration c1 in the reformed fuel. Specifically, when the peroxide concentration c1 in the reformed fuel detected by the concentration sensor 26 is lower than the predetermined concentration c0 (fig. 4), it is determined that reforming is necessary, and when the peroxide concentration is equal to or higher than the predetermined concentration c0, it is determined that reforming is not necessary.

When the reforming determination unit 55 determines that reforming is necessary, the reforming unit control unit 53 switches the fuel supply path 18 to the 1 st path 18a (reforming on) by the switching valve 28 so that the fuel stored in the fuel tank 17 is supplied to the injector 11 after being reformed in the reformer 19. On the other hand, when it is determined by the yes/no reforming determination section 55 that reforming is not required, the fuel supply path 18 is switched to the 2 nd path 18b (reforming off) by the switching valve 28 so that the fuel stored in the fuel tank 17 is supplied to the injector 11 without being reformed in the reformer 19.

The oxidation progression degree estimation portion 56 determines whether or not the progression degree of the oxidation reaction (oxidation progression degree) in the reformer 19 is within an appropriate range based on the ignition timing ti of the fuel at the time of the start of reforming. Specifically, the ignition timing ti of the reformed fuel is calculated based on the pressure in the combustion chamber 10 detected by the in-cylinder pressure sensor 12 and the crank angle detected by the crank angle sensor 15, and when the ignition timing ti is lower than a predetermined crank angle ti0 (fig. 2), it is determined that the degree of progress of oxidation is within the appropriate range. When the ignition timing ti is equal to or greater than the predetermined crank angle ti0, it is determined that the degree of progress of oxidation is outside the appropriate range.

The oxidation progression degree estimation portion 56 may also determine whether the degree of progression of oxidation is within an appropriate range based on the peroxide concentration c1 in the reformed fuel. Specifically, when the concentration c1 of the peroxide in the reformed fuel detected by the concentration sensor 26 is equal to or higher than a predetermined concentration c0 (fig. 4), it is determined that the degree of progress of the oxidation is within the appropriate range, and when the concentration c1 is lower than the predetermined concentration c0, it is determined that the degree of progress of the oxidation is outside the appropriate range.

When it is determined that the degree of progress of oxidation is outside the appropriate range, the oxidation progress degree estimating unit 56 determines excess or deficiency of the degree of progress of oxidation based on the oxide concentration c2 in the reformed fuel. The oxide concentration c2 in the reformed fuel can be estimated based on the fuel injection amount of the injector 11 and the output torque of the engine 1 detected by the torque sensor 16. The fuel injection amount may be calculated based on the fuel flow rate detected by flow meter 22, or may be calculated based on the fuel pressure (command value for high-pressure pump 27) and the fuel injection amount (command value for injector 11) acquired through communication with engine ECU 200.

The oxidation progress degree estimating unit 56 determines that the degree of progress of oxidation is excessive when the oxide concentration c2 is equal to or higher than the peroxide concentration c1 detected by the concentration sensor 26, and determines that the degree of progress of oxidation is insufficient when the concentration c1 is lower (fig. 4). It may be determined that the degree of progress of oxidation is excessive when the oxide concentration c2 is equal to or higher than the predetermined concentration c0, and that the degree of progress of oxidation is insufficient when the oxide concentration c2 is lower than the predetermined value.

The reforming unit control unit 53 controls the operation of the reforming unit 20 based on the degree of progress of the oxidation reaction estimated by the oxidation progress degree estimation unit 56, and adjusts the reforming rate of the reformer 19. Specifically, the operation of the changeover valve 29 is controlled according to the degree of progress of oxidation, the heights h1a, h1b of the reaction chamber 198 are changed by changing over the

fuel discharge holes

196a, 196b, and the reaction time of the oxidation reaction in the reformer 19 is adjusted. When the fuel discharge hole 196a is switched, the reaction time becomes shorter corresponding to the height h1a of the reaction chamber 198, and the reforming rate of the reformer 19 decreases. When the fuel discharge hole 196b is switched, the reaction time becomes longer according to the height h1b of the reaction chamber 198, and the reforming rate of the reformer 19 increases.

The reforming unit controller 53 may control the operation of the air pump 32 to adjust the amount of air supplied to the reformer 19 and adjust the reforming rate of the reformer 19, in addition to the adjustment of the reaction time due to the switching of the

fuel discharge holes

196a and 196 b. The reaction temperature may be adjusted by adjusting the flow rate of the cooling water circulating between the engine 1 and the reformer 19, thereby adjusting the reforming rate of the reformer 19.

Fig. 10A and 10B are flowcharts showing an example of the reforming conversion process executed by the CPU51 of the controller 50. The process of fig. 10A and 10B begins when, for example, the vehicle and the controller 50 start.

In the process of fig. 10A, first, in S1 (S: process step), the fuel cut determining unit 54 performs a process to determine whether or not fuel is supplied to the fuel tank 17 while the vehicle and the controller 50 are stopped. The routine proceeds to S2A when S1 is affirmative (S1: YES), and ends the process when it is negative (S1: YES). In S2A, the process of the determination section 55 for determining whether or not to reform calculates the ignition timing ti, and determines whether or not the ignition timing ti is equal to or greater than the predetermined crank angle ti 0.

If S2A is affirmative (S2A: yes), the ignitability of the fuel is insufficient and the process proceeds to S3, the processing in the reforming unit controller 53 controls the operation of the switching valve 28 to switch the fuel supply path 18 to the 1 st path 18a, and the reforming in the reformer 19 is started, and the processing is terminated. On the other hand, if S2A is negative (S2A: no), the ignitability of the fuel is sufficient and the process proceeds to S4, and the processing in the reforming unit controller 53 controls the operation of the switching valve 28 to switch the fuel supply path 18 to the 2 nd path 18b, and closes the reforming in the reformer 19, thereby ending the processing.

In the process of fig. 10B, in place of S2A of fig. 10A, in S2B, the process of the reforming-or-not determining section 55 determines whether or not the peroxide concentration c1 is lower than the predetermined concentration c0, and determines whether or not reforming is necessary due to insufficient ignitability of the fuel.

In this way, the ignitability of the fuel in the fuel tank 17 after the fuel supply is evaluated based on the ignition timing ti and the peroxide concentration c1 (S1, S2A, S2B), and when the ignitability is not suitable for the compression ignition, the fuel is reformed in the reformer 19 and supplied to the engine 1 (S3). Therefore, sufficient combustion performance of the compression ignition engine mounted on an FFV (Flexible Fuel Vehicle) capable of fueling a low octane gasoline or a normal octane gasoline can be ensured.

Fig. 11A and 11B are flowcharts showing an example of the reforming rate adjustment process executed by the CPU51 of the controller 50. The processing of fig. 11A and 11B is started when, for example, reforming of the reformer 19 is turned on.

In the process of fig. 11A, first, at S5, it is determined whether or not the reforming of the reformer 19 is on. The routine proceeds to S6A when S5 is affirmative (S5: YES), and ends the process when it is negative (S5: NO). In S6A, the process in the oxidation degree estimating unit 56 calculates the ignition timing ti of the reformed fuel, and determines whether the ignition timing ti is lower than a predetermined crank angle ti 0. If S6A is affirmative (S6A: yes), it is determined that the degree of progress of oxidation in the reformer 19 is within the appropriate range, and the process is terminated.

On the other hand, if S6A is negative (S6A: no), it is determined that the degree of progress of oxidation in the reformer 19 is outside the appropriate range, and the routine proceeds to S7 where the oxide concentration c2 in the reformed fuel is calculated, and it is determined whether or not the oxide concentration c2 is equal to or higher than the peroxide concentration c 1. The process proceeds to S8 when S7 is affirmative (S7: YES), and proceeds to S9 when it is negative (S7: NO). At S8, it is considered that the degree of progress of oxidation is excessive, and the operation of the change-over valve 29 is changed to the fuel discharge hole 196a by the processing of the reforming-unit controller 53, so that the reaction time is shortened to lower the reforming rate of the reformer 19, and the process returns to S6A.

At S9, the process of the oxidation progress degree estimating unit 56 determines whether or not the oxide concentration c2 is lower than the peroxide concentration c 1. The process proceeds to S10 when S9 is affirmative (S9: YES), and proceeds to S11 when it is negative (S9: NO). In S10, it is considered that the degree of progress of oxidation is insufficient, and the operation of the change-over valve 29 is changed over to the fuel discharge hole 196b by the processing of the reforming unit controller 53, so that the reforming rate of the reformer 19 is increased by increasing the reaction time, and the process returns to S6A. At S11, it is determined that device 100 has failed, and the process is terminated by, for example, transmitting a failure code to engine ECU 200.

In the processing of fig. 11B, instead of S6A of fig. 11A, in S6B, the processing of the oxidation degree estimating unit 56 determines whether or not the peroxide concentration c1 in the reformed fuel is equal to or higher than the predetermined concentration c 0.

In this way, by estimating the degree of progress of oxidation in the reformer 19 (S6A, S6B, S7, S9), the reforming rate of the reformer 19 is adjusted in accordance with the degree of progress of oxidation (S8, S10), whereby the fuel can be reformed to a state suitable for compression ignition. In addition, even when gasoline of various octane numbers is added or when a plurality of kinds of gasoline having different octane numbers are mixed in the fuel tank 17, sufficient combustion performance of the compression ignition engine mounted on the FFV can be ensured.

Fig. 12 and 13 are diagrams schematically showing an example of the configuration of an apparatus 100A as a modification of the apparatus 100. The apparatus 100A includes a catalyst tank 40 in addition to the configuration of the apparatus 100, and the catalyst tank 40 stores a catalyst solution in which a catalyst (powder) such as an NHPI catalyst is mixed with an appropriate solvent. The apparatus 100A includes a filter 42, a catalyst pump 43 for pressure-feeding the catalyst solution, a flow meter 44 for detecting the flow rate of the catalyst solution, and an opening/closing valve 45 for opening and closing the catalyst supply path 41, in the catalyst supply path 41 for supplying the catalyst to the reformer 19.

The reformer 19 of the apparatus 100A functions as a fluidized bed reactor in which a catalyst solution and a reactant flow together in the reactor. In this case, the particle diameter of the catalyst (powder) can be reduced, the specific surface area can be increased, and the reaction efficiency can be improved. Further, the NHPI catalyst can be directly supplied to the injector 11 without being separated from the reformed fuel, and therefore the entire apparatus can be configured to be simple.

The reforming unit controller 53 of the apparatus 100A can adjust the reforming rate of the reformer 19 by adjusting the catalyst amount by controlling the operation of the catalyst pump 43 in addition to adjusting the reaction time, the air amount, and the heat transfer medium amount. Specifically, the amount of the catalyst supplied to the reformer 19 can be decreased by controlling the operation of the catalyst pump 43 to decrease the reforming rate of the reformer 19, and the amount of the catalyst supplied to the reformer 19 can be increased to increase the reforming rate of the reformer 19.

The present embodiment can provide the following effects.

(1) The apparatus 100 for reforming fuel by an oxidation reaction includes a reformer 19, and the reformer 19 includes an outer tube 191 and an inner tube 192 extending in the vertical direction, and a cylindrical space 193 (fig. 7) is formed between the outer tube 191 and the inner tube 192. The outer tube 191 is provided with an introduction hole 194 penetrating a lower portion of the outer tube 191 to introduce fuel and air into the cylindrical space 193, an air discharge hole 195 penetrating an upper portion of the outer tube 191 to discharge air from the cylindrical space 193, and

fuel discharge holes

196a, 196b penetrating between the introduction hole 194 and the air discharge hole 195 of the outer tube 191 to discharge fuel from the cylindrical space 193 (fig. 7). The cylindrical space 193 is closed at an upper end 193a and a lower end 193 b. The reformer 19 is configured such that the fuel supplied through the introduction hole 194 undergoes an oxidation reaction in the presence of a catalyst in the cylindrical space 193 extending from the lower end 193b to the

fuel discharge holes

196a and 196 b. Accordingly, the oxidation reaction can be performed in the lower reaction chamber 198 of the reformer 19, which is a single double-tube reactor, and the gas-liquid separation can be performed in the upper gas-liquid separation chamber 199, so that the entire apparatus 100 can be configured simply.

(2) When the gap g between the inner wall 191a of the outer tube 191 and the outer wall 192a of the inner tube 192 is set to 2 times the quenching distance, the heights h2a, h2b from the

fuel discharge holes

196a, 196b to the upper end 193a are equal to or greater than the height h0 at which gas-liquid separation can be performed in the cylindrical space 193 from the

fuel discharge holes

196a, 196b to the upper end 193 a. Since the inner wall 191a of the reformer 19 exists within the range from the reactant distance to the quenching distance, the safety of the reformer 19 can be improved.

(3) When the gap g between the inner wall 191a of the outer tube 191 and the outer wall 192a of the inner tube 192 is set to the maximum relief gap, the heights h2a, h2b from the

fuel discharge holes

196a, 196b to the upper end 193 a. The safety of the reformer 19 can be further improved by configuring the reaction chamber 198 for performing the oxidation reaction with the maximum safety gap.

(4) A plurality of

fuel discharge holes

196a and 196b are provided in the vertical direction. The reaction time of the oxidation reaction can be adjusted by changing the heights h1a, h1b of the reaction chamber 198 by switching the plurality of

fuel discharge holes

196a, 196 b. In this case, since there is no need to adjust the flow rates of the heat transfer medium, air, and catalyst, the entire apparatus can be configured more simply.

In the above-described embodiment, the oxidation reaction in which the fuel reforming apparatus reforms the fuel by the oxidation reaction has been described as an example in which the ignitability of the gasoline having a normal octane number is improved to a level corresponding to the gasoline having a low octane number. For example, it is also possible to reform a gasoline fuel into an ethanol fuel by an oxidation reaction.

In the above embodiment, the specific octane number of the fuel and the concentrations of the peroxide and the oxide in the reformed fuel are described as examples of the threshold value for evaluating whether the ignitability of the fuel is suitable for compression ignition, but the threshold values are not limited to these.

In the above embodiment, the fuel reforming device is applied to the engine 1 mounted on the vehicle (FFV), but the fuel reforming device is not limited to the vehicle-mounted engine, and may be applied to products such as a generator and a working machine.

One or more of the above embodiments and modifications may be arbitrarily combined, or modifications may be combined with each other.

The present invention can provide a fuel reforming apparatus with a simple configuration.

While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the scope of the disclosure of the following claims.

Claims

1. A fuel reforming apparatus (100) for reforming fuel by an oxidation reaction, comprising a double tube (19), wherein the double tube (19) has an outer tube (191) and an inner tube (192) extending in the vertical direction, and a cylindrical space (193) is formed between the outer tube (191) and the inner tube (192),

the outer pipe (191) is provided with an introduction hole (194), an air discharge hole (195), and fuel discharge holes (196a, 196b), the introduction hole (194) penetrates through a lower portion of the outer pipe (191) to introduce fuel and air into the cylindrical space (193), the air discharge hole (195) penetrates through an upper portion of the outer pipe (191) to discharge air from the cylindrical space (193), the fuel discharge holes (196a, 196b) penetrate between the introduction hole (194) and the air discharge hole (195) of the outer pipe (191) to discharge fuel from the cylindrical space (193),

the upper end (193a) and the lower end (193b) of the cylindrical space (193) are closed,

the double tube (19) is configured such that the fuel supplied through the introduction hole (194) undergoes an oxidation reaction in the presence of a catalyst in the cylindrical space (193) from the lower end (193b) to the fuel discharge holes (196a, 196 b).

2. The fuel reforming apparatus (100) according to claim 1,

when the clearance between the inner wall (191a) of the outer tube (191) and the outer wall (192a) of the inner tube (192) is set to 2 times the quenching distance, the height from the fuel discharge holes (196a, 196b) to the upper end (193a) is equal to or greater than the height at which gas-liquid separation can be performed in the cylindrical space (193) from the fuel discharge holes (196a, 196b) to the upper end (193 a).

3. The fuel reforming apparatus (100) according to claim 1,

when the clearance between the inner wall (191a) of the outer pipe (191) and the outer wall (192a) of the inner pipe (192) is set to a maximum safe clearance, the height from the fuel discharge holes (196a, 196b) to the upper end (193a) is equal to or greater than the height at which gas-liquid separation can be performed in the cylindrical space (193) from the fuel discharge holes (196a, 196b) to the upper end (193 a).

4. The fuel reforming apparatus (100) according to any one of claims 1 to 3,

the fuel discharge holes (196a, 196b) are provided in plural numbers in the vertical direction.