JP6323907B2 - engine - Google Patents

Description

  The present invention relates to an engine. Specifically, the present invention relates to an engine equipped with a fuel reformer.

  2. Description of the Related Art Conventionally, a premixed engine is known that supplies gas fuel that has been reformed by mixing and pressurizing liquid fuel with intake air (supply air) or exhaust gas in advance. A premixed engine achieves low smoke and low NOx by reforming and burning liquid fuel into gas fuel that can be burned in a lean state. For example, as described in Patent Document 1.

  The engine described in Patent Document 1 uses one of a plurality of cylinders as a fuel reforming cylinder as a fuel reformer, and reforms the fuel by mixing and compressing liquid fuel, intake air, and exhaust gas. doing. For reforming liquid fuel, it is necessary to mix liquid fuel and intake air and exhaust gas uniformly and leanly at a predetermined ratio.

  However, when high-concentration liquid fuel is injected into the fuel reforming cylinder at a high pressure in order to atomize it, part of the liquid fuel adheres to the cylinder inner wall of the reforming cylinder. The adhering liquid fuel is evaporated and mixed with intake air and exhaust gas, and is scraped off by a piston ring until a reforming reaction occurs. That is, the reforming by the fuel reforming cylinder is disadvantageous in that the efficiency of the reforming reaction is reduced because part of the injected liquid fuel is discharged to the oil pan without being reformed.

JP 2007-332891 A

  The present invention has been made in view of the above situation, and an object thereof is to provide an engine including a fuel reforming device capable of rapidly premixing injected fuel and intake air or exhaust gas without excess or deficiency. To do.

  That is, in the present invention, an engine including a fuel reforming device that reforms fuel by a reciprocating motion of a piston built in a cylinder, and an expansion chamber whose volume changes by the reciprocating motion of the piston in the fuel reforming device. And a reaction chamber having a constant volume, and the expansion chamber and the reaction chamber communicate with each other.

  In the present invention, at least one of intake air and exhaust gas is supplied to the expansion chamber, and fuel is supplied to the reaction chamber.

  In the present invention, at least one of intake air and exhaust gas is supplied from the expansion chamber toward a position shifted from the center of the reaction chamber.

  In the present invention, the communication between the expansion chamber and the reaction chamber is configured not to be blocked by the reciprocating motion of the piston.

  As effects of the present invention, the following effects can be obtained.

  That is, in the present invention, the adiabatic compression of the supply air and the reforming of the fuel are performed in different spaces. As a result, the injected fuel and the intake and exhaust can be rapidly premixed without excess or deficiency.

  In the present invention, since no fuel is supplied to the expansion chamber, all the fuel is reformed without being scraped off by the piston. As a result, the injected fuel and the intake and exhaust can be rapidly premixed without excess or deficiency.

  In the present invention, fuel is supplied in a state where a vortex is generated inside the reaction chamber. As a result, the injected fuel and the intake and exhaust can be rapidly premixed without excess or deficiency.

  In the present invention, since there is no restriction on the setting of the top dead center position of the piston, setting the volume of the expansion chamber at the time of compression as small as possible reduces the amount of intake air and exhaust gas remaining in the expansion chamber, and adiabatic expansion. Oxidation of the reformed fuel at the time is suppressed. As a result, the injected fuel and the intake and exhaust can be rapidly premixed without excess or deficiency.

Schematic which shows the structure of one Embodiment of the engine which concerns on this invention. Schematic which shows the structure of embodiment which has arrange | positioned the reaction chamber to the piston of the cylinder for a modification | reformation of the engine which concerns on this invention. Schematic which shows the structure of embodiment which has arrange | positioned the reaction chamber in the cylinder block of the cylinder for a modification | reformation of the engine which concerns on this invention. Schematic which shows the control structure in one Embodiment of the engine which concerns on this invention. The figure showing the graph showing the relation between the crank position of the cylinder for reforming in one embodiment of the engine concerning the present invention, and fuel injection timing. Schematic which shows the flow of the air supply in the reaction chamber in one Embodiment of the engine which concerns on this invention.

  Below, the engine 1 which is 1st embodiment of the engine which concerns on this invention is demonstrated using FIGS. 1-4.

  As shown in FIG. 1, the engine 1 is a diesel engine using light oil or heavy oil as fuel. The engine 1 is mainly an output cylinder 2, a supercharger 14, a reforming cylinder 15 as a fuel reformer, an intake intercooler 35, a reformed fuel intercooler 36, an EGR gas intercooler 37, and a control device. An ECU 38 is provided. In the present embodiment, the engine 1 is a diesel engine, but the present invention is not limited to this.

  The output cylinder 2 generates power by combustion of fuel and transmits it to the output shaft. The output cylinder 2 includes an output cylinder 3, an output piston 4, an output connecting rod 5, and a sub fuel injection device 6.

  The output cylinder 2 includes an output piston 4 that is slidable inside the output cylinder 3. The output cylinder 3 is configured such that one side is closed by a cylinder head (not shown) and the other side is opened. The open output piston 4 is connected to an output crankshaft 7 which is an output shaft by an output connecting rod 5. The compression ratio of the output cylinder 2 is set to 13 or more (for example, about 13 to 18) in consideration of early ignition and misfire.

  The output crankshaft 7 is provided with an output crank angle detection sensor 8. In the output cylinder 2, a combustion chamber 9 is constituted by the inner wall of the output cylinder 3 and the end face of the output piston 4. The output cylinder 2 is provided with an auxiliary fuel injection device 6 capable of injecting fuel into the combustion chamber 9. The auxiliary fuel injection device 6 is composed of an injector having a hole type nozzle. An intake pipe 11 is connected to the output cylinder 2 via an output intake valve 10, and an exhaust pipe 13 is connected via an output exhaust valve 12. In the present embodiment, the output cylinder 2 may be singular or plural.

  The supercharger 14 is for adiabatically compressing outside air and supplying it to the combustion chamber 9 of the output cylinder 2. The supercharger 14 includes a turbine 14a and a compressor 14b. An exhaust pipe 13 is connected to the turbine 14a so that exhaust from the combustion chamber 9 can be supplied. An intake pipe 11 is connected to the compressor 14b so that outside air can be sucked and supplied to the combustion chamber 9 as intake air. That is, the supercharger 14 is configured to be capable of adiabatic compression by converting the exhaust pressure into rotational power by the turbine 14a and transmitting it to the compressor 14b, and sucking outside air by the compressor 14b.

  The reforming cylinder 15 which is a fuel reformer reforms fuel such as light oil into a lower hydrocarbon fuel (for example, methane) and suppresses premature ignition. The reforming cylinder 15 reforms the fuel by adiabatically compressing the fuel injected into the air-fuel mixture of the intake air and the exhaust gas (EGR gas). The reforming cylinder 15 includes a reforming cylinder head 16, a reforming cylinder 17, a reforming piston 18, a reforming connecting rod 19, a reaction chamber 24, and a main fuel injection device 20.

  In the reforming cylinder 15, one side of the reforming cylinder 17 is closed by a reforming cylinder head 16, and a reforming piston 18 is slidably housed inside. The reforming piston 18 is connected to the reforming crankshaft 21 by a reforming connecting rod 19. The reforming crankshaft 21 is provided with a reforming crank angle detection sensor 22. The reforming piston 18 of the reforming cylinder 15 is configured to be able to reciprocate by power from the reforming crankshaft 21 that is linked to the output crankshaft 7. In the present embodiment, the reforming cylinder 15 is configured to transmit power from the output crankshaft 7, but is not limited to this, and power from an independent power source may be used. . Further, the reforming cylinder 15 may be provided for each output cylinder 2 or may be one for the plurality of output cylinders 2. Further, the output cylinder 2 and the reforming cylinder 15 can be used together.

  In the reforming cylinder 15, an expansion chamber 23 is constituted by the reforming cylinder head 16, the reforming cylinder 17, and the end faces of the reforming piston 18. Accordingly, the expansion chamber 23 is configured such that its volume changes due to the reciprocating motion of the reforming piston 18. The expansion chamber 23 adiabatically compresses the supply air and the fuel by changing the volume.

  Further, the reforming cylinder 15 is formed with a reaction chamber 24 in the reforming cylinder head 16. The reaction chamber 24 is a space in which supply air and fuel are premixed to cause a reforming reaction. The reaction chamber 24 of the reforming cylinder head 16 is formed in a substantially spherical shape. The shape of the reaction chamber 24 is not limited to a substantially spherical shape, and may be any shape that can generate a vortex such as an ellipse. In the reaction chamber 24, a main fuel injection device 20 is provided. The main fuel injection device 20 is configured to inject fuel only into the reaction chamber 24. Therefore, the main fuel injection device 20 is provided at a position where the injected fuel does not reach the inside of the expansion chamber 23 through the communication hole 25. The main fuel injection device 20 includes nozzles such as a pintle type nozzle, a swirl injector, and an air assist injector.

  The reforming cylinder head 16 is formed with a communication hole 25 that connects the expansion chamber 23 and the reaction chamber 24. The communication hole 25 opens at a position biased to one side of the reaction chamber 24, and is configured such that its axis does not pass through the center of the reaction chamber 24. Thus, the reforming cylinder 15 is configured such that the gas flowing into the reaction chamber 24 from the expansion chamber 23 through the communication hole 25 swirls inside the reaction chamber 24 to generate a vortex. The communication hole 25 is formed so as to face the end surface of the reforming piston 18. Thereby, the expansion chamber 23 and the reaction chamber 24 are maintained in a communication state regardless of the position of the top dead center of the reforming piston 18. That is, the reforming cylinder 15 can arbitrarily set the top dead center position of the reforming piston 18. In the present embodiment, the number of the communication holes 25 is one. However, the number of the communication holes 25 is not limited to this, and a plurality of holes may be used as long as they generate a vortex inside the reaction chamber 24.

  The compression ratio of the reforming cylinder 15 is set to 15 or more (for example, about 15 to 20) in consideration of heat loss. Further, the reforming cylinder 15 has the reforming piston 18 at the top dead center position, and the volume ratio of the reaction chamber 24 to the expansion chamber 23 when the volume of the expansion chamber 23 becomes the smallest is 3: 7 or more. It is configured to be. As a result, the reforming cylinder 15 causes the reformed fuel to remain in the expansion chamber 23 when the fuel reformed in the reaction chamber 24 is adiabatically expanded in the expansion chamber 23. The amount oxidized by can be suppressed.

  In the present embodiment, the reaction chamber 24 is formed in the reforming cylinder head 16, but is not limited thereto. For example, as shown in FIG. 2, a reaction chamber 24 may be formed inside the reforming piston 18. The reaction chamber 24 of the reforming piston 18 is formed in a substantially spherical shape. A communication hole 25 that connects the expansion chamber 23 and the reaction chamber 24 is formed in the reforming piston 18. The communication hole 25 opens at a position biased to one side of the reaction chamber 24, and is configured such that its axis does not pass through the center of the reaction chamber 24. Thereby, the reforming cylinder 15 is configured such that the gas flowing into the reaction chamber 24 from the expansion chamber 23 swirls inside the reaction chamber 24 to generate a vortex. In this embodiment, the main fuel injection device 20 is provided in the reforming cylinder head 16. The main fuel injection device 20 is configured to inject fuel into the reaction chamber 24 through a communication hole 25 formed in the reforming piston 18. Thereby, the reforming cylinder 15 can premix the supply air and the fuel inside the reaction chamber 24 even if the reaction chamber 24 is formed in the reforming piston 18 that reciprocates.

  As shown in FIG. 3, the reaction chamber 24 may be formed in a cylinder block 26 in which the reforming cylinder 17 is formed. The reaction chamber 24 of the cylinder block 26 is formed in a substantially spherical shape. A communication hole 25 that connects the expansion chamber 23 and the reaction chamber 24 is formed in the cylinder block 26. The communication hole 25 opens at a position biased to one side of the reaction chamber 24, and is configured such that its axis does not pass through the center of the reaction chamber 24. Thereby, the reforming cylinder 15 is configured such that the gas flowing into the reaction chamber 24 from the expansion chamber 23 swirls inside the reaction chamber 24 to generate a vortex. In this embodiment, the main fuel injection device 20 is provided in the reaction chamber 24.

  As shown in FIG. 1, a supply pipe 28 is connected to the reforming cylinder 15 via a reforming intake valve 27, and an exhaust pipe 30 is connected via a reforming exhaust valve 29. The exhaust pipe 30 is connected to the intake pipe 11. That is, the supply pipe 28 is configured to be able to supply a part of the intake air from the intake pipe 11. The supply pipe 28 is connected to the exhaust pipe 13 via the EGR pipe 31. That is, the supply pipe 28 is configured so that a part of the exhaust gas from the combustion chamber 9 of the output cylinder 2 can be supplied as EGR gas through the EGR pipe 31. Therefore, the expansion chamber 23 of the reforming cylinder 15 is configured to be able to supply a mixture of intake air and EGR gas (hereinafter simply referred to as “supply air”) from the supply pipe 28. The discharge pipe 30 is connected to the intake pipe 11 on the downstream side of the supply pipe 28 via the mixer 30a. Further, the reforming cylinder 15 can discharge lower hydrocarbon fuel (hereinafter simply referred to as “reformed fuel”) whose air-fuel mixture has been reformed from the expansion chamber 23 to the intake pipe 11 through the exhaust pipe 30. It is configured.

  The intake pipe 11 is provided with a first intake metering valve 32 downstream of the connection position of the supply pipe 28 and upstream of the connection position of the discharge pipe 30. The first intake metering valve 32 is composed of an electromagnetic flow control valve. The first intake metering valve 32 can change the opening of the first intake metering valve 32 by acquiring a signal from an ECU 38 which is a control device described later. In the present embodiment, the first intake metering valve 32 is composed of an electromagnetic flow control valve. However, any type that can change the flow rate of intake air may be used.

  A second intake metering valve 33 is provided on the supply pipe 28 upstream of the connection position of the EGR pipe 31. The second intake metering valve 33 is composed of an electromagnetic flow control valve. The second intake metering valve 33 can change the opening degree of the second intake metering valve 33 by acquiring a signal from the ECU 38 described later. In the present embodiment, the second intake metering valve 33 is composed of an electromagnetic flow control valve. However, any type that can change the intake flow rate may be used.

  The EGR pipe 31 is provided with an EGR gas metering valve 34. The EGR gas metering valve 34 is composed of an electromagnetic flow control valve. The EGR gas metering valve 34 can change the opening degree of the EGR gas metering valve 34 by acquiring a signal from an ECU 38 to be described later. In the present embodiment, the EGR gas metering valve 34 is composed of an electromagnetic flow control valve. However, any type that can change the flow rate of the EGR gas may be used.

  With this configuration, the engine 1 is configured so that the mixing ratio between the intake air and the reformed fuel discharged from the expansion chamber 23 of the reforming cylinder 15 can be changed by the first intake metering valve 32. Yes. Further, the engine 1 is configured such that the mixing ratio between the intake air supplied to the expansion chamber 23 and the EGR gas can be changed by the second intake metering valve 33 and the EGR gas metering valve 34.

  The intake intercooler 35, the reformed fuel intercooler 36, and the EGR gas intercooler 37 cool the gas. The intake intercooler 35 is provided in the intake pipe 11. The intake intercooler 35 is configured to be able to cool the intake air adiabatically compressed by the compressor 14b. The reformed fuel intercooler 36 is provided in the discharge pipe 30. The reformed fuel intercooler 36 is configured to cool the reformed fuel discharged from the expansion chamber 23 of the reforming cylinder 15. The reformed fuel intercooler 36 includes a radiator or a heat exchanger that uses air or water as a cooling medium. The EGR gas intercooler 37 is provided in the EGR pipe 31. The EGR gas intercooler 37 is configured to be able to cool the exhaust gas heated by the combustion of fuel.

  The ECU 38 as a control device controls the engine 1. Specifically, the ECU 38 controls the auxiliary fuel injection device 6, the main fuel injection device 20, the first intake metering valve 32, the second intake metering valve 33, the EGR gas metering valve 34, and the like. The ECU 38 stores various programs and data for controlling the engine 1. The ECU 38 may have a configuration in which a CPU, a ROM, a RAM, an HDD, and the like are connected by a bus, or may be configured by a one-chip LSI or the like.

  As shown in FIG. 4, the ECU 38 performs main fuel injection for calculating the main fuel injection amount Qm based on various programs for performing fuel injection control, and the target engine speed Nt and the target output Wt of the engine 1. Intake flow rate map M2, target rotation speed Nt and main fuel for calculating the output intake flow rate A1 to be supplied to the combustion chamber 9 of the output cylinder 2 based on the amount map M1, the target rotation speed Nt and the main fuel injection amount Qm A mixture flow rate map M3 for calculating the reforming intake air flow rate A2 and the EGR gas flow rate A3 supplied to the expansion chamber 23 of the reforming cylinder 15 based on the injection amount Qm, the target rotational speed Nt, and the main fuel injection amount A sub fuel injection amount map M4 and the like for calculating the sub fuel injection amount Qs of the ignition fuel injected into the combustion chamber 9 based on Qm are stored.

  As shown in FIG. 1, the ECU 38 is connected to the auxiliary fuel injection device 6 and can control the fuel injection of the auxiliary fuel injection device 6.

  The ECU 38 is connected to the main fuel injection device 20 and can control the fuel injection of the main fuel injection device 20.

  The ECU 38 is connected to the first intake metering valve 32 and can control opening and closing of the first intake metering valve 32.

  The ECU 38 is connected to the second intake metering valve 33 and can control the opening and closing of the second intake metering valve 33.

  The ECU 38 is connected to the EGR gas metering valve 34 and can control the opening and closing of the EGR gas metering valve 34.

  The ECU 38 is connected to the output crank angle detection sensor 8 and can acquire the output crankshaft angle θ1 detected by the output crank angle detection sensor 8.

  The ECU 38 is connected to the reforming crank angle detection sensor 22 and can acquire the reforming crankshaft angle θ2 detected by the reforming crank angle detection sensor 22.

  Below, the operation | movement aspect of each part of the engine 1 which concerns on 1st embodiment of this invention is demonstrated using FIG. 1, FIG. 4 FIG.

First, intake and exhaust paths in the engine 1 will be described.
As shown in FIG. 1, the outside air sucked by the compressor 14b of the supercharger 14 is discharged to the intake pipe 11 in a state where it is adiabatically compressed as intake air. The intake air is cooled by the intake intercooler 35 and then supplied to the combustion chamber 9 of the output cylinder 2 via the intake pipe 11. A part of the intake air is supplied to the expansion chamber 23 of the reforming cylinder 15 via the supply pipe 28 connected to the intake pipe 11 and the reforming intake valve 27.

  Exhaust gas from the combustion chamber 9 of the output cylinder 2 is discharged to the outside after rotating the turbine 14 a of the supercharger 14 via the exhaust pipe 13. A part of the exhaust gas is supplied as EGR gas to the expansion chamber 23 of the reforming cylinder 15 through the EGR pipe 31 and the supply pipe 28 to which the EGR pipe 31 is connected.

  The supply air (intake air and EGR gas) supplied to the expansion chamber 23 is supplied to the reaction chamber 24 through the communication hole 25. The fuel reformed together with the supply air in the reaction chamber 24 is discharged from the reaction chamber 24 to the expansion chamber 23 by suction by the movement of the reforming piston 18. The reformed fuel discharged from the expansion chamber 23 by compression due to the movement of the reforming piston 18 is returned to the intake pipe 11 through the reforming exhaust valve 29 and the exhaust pipe 30 and supplied to the combustion chamber 9.

  Next, calculation of various predetermined amounts in the ECU 38 will be described. As shown in FIG. 4, the ECU 38 calculates the main fuel injection amount Qm from the fuel injection amount map M1 based on the target rotational speed Nt and the target output Wt of the engine 1 determined from the operation amount of an operation tool (not shown).

  The ECU 38 calculates the output intake flow rate A1 to be supplied to the combustion chamber 9 of the output cylinder 2 from the intake flow rate map M2 based on the target rotational speed Nt and the main fuel injection amount Qm.

  The ECU 38 calculates the reforming intake flow rate A2 and the EGR gas flow rate A3 to be supplied to the expansion chamber 23 of the reforming cylinder 15 from the mixture flow rate map M3 based on the target rotational speed Nt and the main fuel injection amount Qm.

  The ECU 38 calculates the auxiliary fuel injection amount Qs of the ignition fuel injected into the combustion chamber 9 of the output cylinder 2 from the auxiliary fuel injection amount map M4 based on the target rotational speed Nt and the main fuel injection amount Qm.

  The ECU 38 acquires the output crankshaft angle θ1 detected by the output crankangle detection sensor 8 and the reforming crankshaft angle θ2 detected by the reforming crankangle detection sensor 22, and outputs the output cylinder 2 and the reforming crankshaft. The stroke of the cylinder 15 is calculated.

  Next, the mode of fuel reforming in the reforming cylinder 15 will be described with reference to FIGS.

  As shown in FIG. 5, during the suction stroke of the reforming cylinder 15, the reforming cylinder 15 moves from the top dead center toward the bottom dead center in the reforming cylinder 15. That is, the internal pressure of the expansion chamber 23 of the reforming cylinder 15 is reduced by increasing the volume due to the movement of the reforming piston 18. Further, in the suction stroke of the reforming cylinder 15, the reforming cylinder 15 is configured such that the reforming intake valve 27 is opened to supply the supply air. Therefore, the ECU 38 performs reforming during the stroke of the reforming cylinder 15 during the suction stroke (for example, when the reforming piston 18 is near bottom dead center) based on the acquired reforming crankshaft angle θ2. The opening and closing of the second intake metering valve 33 is controlled so that intake air is supplied to the expansion chamber 23 of the cylinder 15 by the calculated intake air flow rate A2. At the same time, the ECU 38 controls the opening and closing of the EGR gas metering valve 34 so that the EGR gas is supplied to the expansion chamber 23 of the reforming cylinder 15 by the calculated EGR gas flow rate A3. As a result, supply air (intake air and EGR gas) is sucked into the expansion chamber 23 at an oxygen concentration suitable for reforming the fuel (supply air suction in FIG. 5).

  In the compression stroke of the reforming cylinder 15, in the reforming cylinder 15, the reforming piston 18 moves from the bottom dead center to the top dead center. In other words, the internal pressure of the expansion chamber 23 of the reforming cylinder 15 increases as the volume decreases due to the movement of the reforming piston 18. As a result, the supply air supplied to the expansion chamber 23 is adiabatically compressed by the reforming piston 18. Then, as shown in FIG. 6, the supply air inside the expansion chamber 23 that is adiabatically compressed flows into the reaction chamber 24 through the communication hole 25 at a high speed (supply supply in FIG. 5). At this time, the supply air forms a high-speed vortex inside the reaction chamber 24 from the positional relationship between the reaction chamber 24 and the communication hole 25. The reforming cylinder 15 adiabatically compresses the supply air to bring the inside of the reaction chamber 24 into a high temperature and high pressure state.

  As shown in FIG. 5, in the compression stroke of the reforming cylinder 15, the ECU 38 calculates the main fuel injection amount Qm calculated in the reaction chamber 24 of the reforming cylinder 15 based on the acquired reforming crankshaft angle θ2. The main fuel injection device 20 is controlled so that only the fuel is supplied. As a result, the reforming cylinder 15 injects fuel into the reaction chamber 24 in which a high-speed vortex is generated in a high temperature and high pressure state (fuel injection in FIG. 5). In the reaction chamber 24, the fuel having an equivalent ratio necessary for reforming into lower hydrocarbon fuel using the reforming intake air flow rate A2 of the intake air supplied to the expansion chamber 23 and the EGR gas flow rate A3 of EGR gas. Is supplied.

  The fuel injected into the reaction chamber 24 is rapidly mixed (premixed) with the supply air by the synergistic effect of the diffusion of the injected fuel and the state of the high-temperature and high-pressure reaction chamber 24 and the high-speed vortex flow. And evaporate. A part of the fuel injected into the reaction chamber 24 adheres to the inner wall of the reaction chamber 24, but there is nothing that slides on the inner wall of the reaction chamber 24 unlike the reforming piston 18 of the expansion chamber 23. Therefore, the fuel adhering to the inner wall of the reaction chamber 24 evaporates by being exposed to a high-speed vortex at a high temperature and a high pressure, and is mixed with the supply air.

  The fuel premixed with the supply air starts the reforming reaction of the fuel when the reforming piston 18 reaches near the top dead center, that is, when the supply air and the fuel are at the highest temperature and high pressure ( Fuel reforming in FIG. At this time, the internal pressure of the reaction chamber 24 becomes lower than the internal pressure of the expansion chamber 23 due to the progress of the reforming reaction, so that the mixture of supply air and fuel does not flow into the expansion chamber 23.

  In the expansion stroke of the reforming cylinder 15, in the reforming cylinder 15, the reforming piston 18 moves from the top dead center to the bottom dead center. That is, the internal pressure of the expansion chamber 23 of the reforming cylinder 15 decreases as the capacity increases due to the movement of the reforming piston 18. Thereby, the reformed fuel in the reaction chamber 24 moves to the expansion chamber 23 (fuel outflow in FIG. 5). Further, the reformed fuel that has flowed out of the reaction chamber 24 into the expansion chamber 23 is adiabatically expanded as the volume of the expansion chamber 23 increases. As a result, the reformed fuel is cooled by adiabatic expansion, and the reforming reaction is stopped when the pressure is reduced (reforming stop in FIG. 5).

  In the exhaust stroke of the reforming cylinder 15, the reforming cylinder 15 moves from the bottom dead center to the top dead center in the reforming cylinder 15. In other words, the internal pressure of the expansion chamber 23 of the reforming cylinder 15 increases as the volume decreases due to the movement of the reforming piston 18. In the exhaust stroke of the reforming cylinder 15, the reforming cylinder 15 is configured such that the reforming exhaust valve 29 is opened to discharge the reformed fuel from the expansion chamber 23. Therefore, the reformed fuel is discharged from the expansion chamber 23 through the reforming exhaust valve 29 and is returned to the intake pipe 11 through the discharge pipe 30 (fuel discharge in FIG. 5).

  The reformed fuel is supplied to the exhaust pipe 30 as a high-temperature fuel gas by the residual heat amount that was not used for the endothermic decomposition reaction during reforming out of the heat amount of the supply air. The high-temperature reformed fuel supplied to the discharge pipe 30 is cooled by the reformed fuel intercooler 36 in the discharge pipe 30. Thereby, early self-ignition in the output cylinder 2 is suppressed. The reformed fuel cooled by the reformed fuel intercooler 36 is supplied to the intake pipe 11 via the mixer 30a.

  As described above, in the reforming cylinder 15, the adiabatic compression of the supply air and the reforming of the fuel are performed in different spaces. The reaction chamber 24 of the reforming cylinder 15 does not slide on the inner wall like the reforming piston 18 of the expansion chamber 23, so that all fuel is reformed without being scraped off by the reforming piston 18. The Specifically, a predetermined amount of fuel injected into the supply air with a predetermined oxygen concentration in the reaction chamber 24 is entirely reformed by the action of a high-speed vortex in the high-temperature and high-pressure state inside the reaction chamber 24. In the compression stroke, it is reformed into a lower hydrocarbon fuel gasified by endothermic decomposition. That is, in the reforming cylinder 15, the supplied reforming intake air flow rate A2, EGR gas flow rate A3, and main fuel injection amount Qm are used to generate reformed fuel without excess or deficiency. In addition, since the top dead center position of the reforming piston 18 is arbitrarily determined in the reforming cylinder 15, the amount of supplied air remaining in the expansion chamber 23 is reduced, and the reformed fuel at the time of adiabatic expansion is reduced. Oxidation is suppressed. Thereby, the injected fuel and the supply air can be rapidly premixed without excess or deficiency.

1 Engine 15 Reforming Cylinder 17 Reforming Cylinder 18 Reforming Piston 23 Expansion Chamber 24 Reaction Chamber

Claims (4)

An engine comprising a fuel reforming device that reforms fuel by reciprocating movement of a piston built in a cylinder,
An engine in which an expansion chamber whose volume is changed by a reciprocating motion of a piston in a fuel reformer and a reaction chamber having a constant volume are configured, and the expansion chamber and the reaction chamber communicate with each other.   The engine according to claim 1, wherein at least one of intake air and exhaust gas is supplied to the expansion chamber, and fuel is supplied to the reaction chamber.   The engine according to claim 1 or 2, wherein at least one of intake air and exhaust gas is supplied from the expansion chamber toward a position shifted from a center of the reaction chamber.   The engine according to any one of claims 1 to 3, wherein communication between the expansion chamber and the reaction chamber is configured not to be blocked by a reciprocating motion of the piston.

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