JP4631713B2 - Internal combustion engine - Google Patents

Description

  The present invention relates to an internal combustion engine using reformed fuel.

  There is known an internal combustion engine that includes a reformer that reforms a hydrocarbon-based fuel to generate a reformed fuel containing a gas such as hydrogen or carbon monoxide. By containing hydrogen in the fuel, the ignitability of the internal combustion engine is increased and the combustion speed can be increased. As a result, lean combustion becomes possible, and it is possible to reduce pumping loss and improve the stability of combustion during exhaust gas recirculation. Such an internal combustion engine using reformed fuel is described in Patent Document 1 below. This internal combustion engine is a self-heating engine that mixes air and fuel, burns part of the fuel, and reforms the fuel by the heat generated thereby.

JP 2005-146894 A

  In the self-heating type, since air and fuel are mixed and burned, the generated reformed fuel contains nitrogen in the air, and the proportion of hydrogen decreases accordingly. In addition, a part of the supplied fuel is burned, and the amount of fuel consumption increases accordingly. Furthermore, a compressor for supplying air is required, and there is a problem that the apparatus is increased in size.

  The present invention provides an internal combustion engine that can generate a reformed fuel having a high hydrogen concentration and uses a reformed fuel with a simple configuration.

  The internal combustion engine using the reformed fuel of the present invention has a heating / evaporating section around the internal combustion engine body and a reforming section in the vicinity of the exhaust passage. The evaporated raw material goes to the reforming section heated by the exhaust gas, where the raw material is reformed to generate a reformed fuel. The generated reformed fuel is ejected from the ejection nozzle into the intake passage or the cylinder.

  Since the raw material is reformed by using the exhaust heat so that the raw material is not burned, it is not necessary to supply air, and the proportion of hydrogen can be increased.

  Further, another internal combustion engine using the reformed fuel of the present invention has a heating / evaporating section in the cylinder block or cylinder head around the combustion chamber, and a reforming section in the vicinity of the exhaust passage. The liquid raw material of the reformed fuel is sent to the heating / evaporating section, heated by the heat in the combustion chamber, and evaporated. The evaporated and expanded raw material goes to the reforming section heated by the exhaust gas, where the raw material is reformed to generate reformed fuel. The generated reformed fuel is ejected from the ejection nozzle into the intake passage or the cylinder.

  By evaporating the raw material with the heat around the combustion chamber and reforming the raw material with the heat of the exhaust, the reformed fuel can be obtained without burning the raw material. Further, since the raw material is not burned, it is not necessary to supply air and the ratio of hydrogen can be increased. Furthermore, the surroundings of the combustion chamber are cooled by the evaporation of the raw material in the heating evaporation section, which is advantageous for reducing the capacity of the radiator and also for preventing knocking.

  Further, the internal combustion engine of the present invention can be a multi-cylinder engine. In this case, the heating evaporation unit, the reforming unit, and the injection nozzle are provided for each cylinder. Then, the raw material evaporated in the heating evaporation section of the first cylinder in the compression stroke or the expansion stroke goes to the reforming section of the second cylinder in the next ignition sequence of the first cylinder, where it is reformed. , And ejected from the ejection nozzle to the second cylinder.

  Further, the internal combustion engine of the present invention can be a four-cylinder. The raw material is supplied to the heating evaporation section of this cylinder near the explosion top dead center of the first cylinder, and the evaporated raw material goes to the reforming section of the second cylinder, which is the next explosion cylinder. Quality. Then, it ejects with respect to a 2nd cylinder from an ejection nozzle.

  Furthermore, a heat storage part that stores the heat of the exhaust gas and keeps the reforming catalyst part warm can be integrally provided with a plurality of cylinders. Since the exhaust heat from the plurality of cylinders is sequentially supplied to the heat storage unit, the temperature can be stabilized.

  Further, a reformed fuel tank that stores a part of the generated reformed fuel, and an injection valve that injects the reformed fuel from the tank into the intake passage or the cylinder, as necessary, can be provided.

  The reformed fuel stored in the tank is injected and supplied when the internal combustion engine is started. The reformed fuel that has already been generated can be used when cold, and the ignitability is improved.

  The raw material of the reformed fuel can be organic compound liquid fuel such as gasoline and water.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a schematic configuration of a cylinder head 12 and its periphery of an internal combustion engine 10 according to this embodiment, and FIG. 2 is a schematic configuration of a combustion chamber 14 of one cylinder of the internal combustion engine 10 and its periphery. FIG. The internal combustion engine 10 is a four-cylinder four-process cycle engine. The four cylinders are referred to as the first cylinder 16-1, the second cylinder 16-2, the third cylinder 16-3, and the fourth cylinder 16-4 from the left side in FIG. When it is not necessary to do this, it is simply referred to as cylinder 16. An intake manifold 18 is attached to the cylinder head 12, and each manifold branch is connected to the combustion chamber 14 via an intake port 20 in the cylinder head. The intake manifold 18 and the intake port 20 form an intake passage for supplying intake air to the combustion chamber 14. An exhaust manifold 22 is attached to the cylinder head 12, and each manifold branch is connected to the combustion chamber 14 via an exhaust port 24 in the cylinder head.

  As shown in FIG. 2, the combustion chamber 14 is a space surrounded by the cylinder head 12, the cylinder block 26, and a piston 28 that reciprocates within the cylinder block. An intake valve 30 is provided at an opening of the intake port 20 facing the combustion chamber 14 and is controlled to open and close at a predetermined timing by a drive mechanism (not shown). An exhaust valve 32 is provided at the opening of the exhaust port 24 facing the combustion chamber 14 and is controlled to open and close at a predetermined timing by a drive mechanism (not shown). A spark plug 34 is disposed at a substantially central position of the combustion chamber 14 of the cylinder head 12. The above configuration is basically the same as that of a conventional four-stroke cycle, four-cylinder internal combustion engine.

  The internal combustion engine 10 is provided with a configuration for obtaining reformed fuel. A heating evaporation unit 36 is provided in a portion of the cylinder block 26 around the combustion chamber 14. The heating evaporator 36 includes a heat transfer body 38 whose inner surface faces the combustion chamber 14 and transfers heat in the combustion chamber, and a heat insulator 40 positioned on the opposite side of the heat transfer body 38 with respect to the combustion chamber. Including. A space surrounded by the heat transfer body 38 and the heat insulator 40 is formed, and this space is a heating evaporation chamber 42 in which the raw material liquid is heated and evaporated. Preferably, the heat transfer body 38 has a cylindrical shape, and its inner wall surface faces the combustion chamber 14 and its outer wall surface faces the heating evaporation chamber 42. As shown in FIG. 2, the heat insulator 40 has a ring shape having a substantially U-shaped cross section, surrounds the heating evaporation chamber 42 which is an inner portion of the U shape, and maintains this at a high temperature. The heat insulator 40 can be configured as a vacuum heat insulating layer. Furthermore, the heat transfer body 38 can be provided with one or more fins or protrusions extending from the heat transfer body into the heating evaporation chamber 42.

  A raw material injection valve 44 for injecting the raw material liquid into the heating evaporation chamber 42 is provided. As shown in FIG. 1, a raw material supply pipe 46 is connected to each raw material injection valve 44, a pressurized raw material is supplied, and the raw material injection valve 44 is opened at a predetermined timing to inject fuel liquid. . The raw material liquid may be a liquid mixture of hydrocarbon fuels such as gasoline and light oil, liquid fuels such as alcohols and ethers such as methanol and ethanol, and water.

  The raw material evaporated in the heating evaporation chamber 42 goes to the reforming section 50 through the communication conduit 48. The communication conduit 48 communicates the heating / evaporating section 36 of a certain cylinder 16 with the reforming section 50 of the next ignition sequence of the cylinder 16. In the case of a general four-cylinder four-process engine, the ignition order is No. 1 cylinder-3 cylinder-4 cylinder No. 2-2 cylinder. Therefore, the communication conduit 48 is, for example, the heating evaporation section 36 of the No. 1 cylinder 16-1. And the reforming section 50 of the three-cylinder 16-3 communicate with each other.

  The reforming unit 50 includes a reforming catalyst chamber 52 that is provided near the exhaust port 24 and is heated by exhaust heat, a heat storage body 54 that surrounds the reforming catalyst chamber 52, and a heat insulator 56 that surrounds the heat storage body 54. In the reforming catalyst chamber 52, a ceramic or stainless steel support carrying the catalyst is disposed, and the raw material that has passed through the communication conduit 48 undergoes a reforming reaction by the catalyst and becomes reformed fuel. The heat storage body 54 and the heat insulator 56 are provided to keep the temperature of the reforming catalyst chamber 52 at a high temperature. The heat insulator 56 can be configured as a vacuum heat insulating layer.

  In the present embodiment, the heat accumulator 54 is provided for each cylinder. However, as shown by the one-dot chain line 55 in FIG. As a result, the heat of the exhaust of the other cylinders can be stored, and the temperature variation of the reforming unit can be reduced. In this case, the heat insulator is also provided so as to surround the integrated heat storage body.

  From the reforming catalyst chamber 52, an ejection conduit 58 extends into the intake port 20 of the same cylinder where the reforming section 50 is provided and is connected to the ejection nozzle 60. The reforming unit 50 is further provided with an additional raw material injection valve 62 for directly supplying the raw material liquid. The raw material liquid is additionally injected under predetermined conditions such as when the load is high and the temperature of the catalyst is high.

  As shown in FIG. 1, the four communication conduits 48 have different shapes. That is, the communication conduit 48-1 from the first cylinder 16-1 to the third cylinder 16-3 and the communication conduit 48-4 from the fourth cylinder 16-4 to the second cylinder 16-2 are elongated. Yes, the communication conduit 48-3 from the third cylinder 16-3 to the fourth cylinder 16-4 and the communication conduit 48-2 from the second cylinder 16-2 to the first cylinder 16-1 are bent and contracted. Shape. However, the diameter and length of each communication conduit 48 are equal. This is for equalizing the time for the raw material evaporated in the heating evaporation unit 36 to reach the reforming unit 50. Similarly, the pipe diameter and length of the ejection conduit 58 are the same.

  FIG. 3 is a diagram schematically showing the flow of the evaporated raw material. The raw material evaporated in the heating evaporator 36 of the first cylinder 16-1 is transferred to the third cylinder 16-3, from the third cylinder 16-3 to the fourth cylinder 16-4, and from the fourth cylinder 16-4 to second. To the cylinder 16-2, the second cylinder 16-2 goes to the first cylinder 16-1.

  FIG. 4 is a diagram showing the operation of each cylinder in time series. From the top, they are arranged in the firing order as No. 1, No. 3, No. 4, and No. 2. A solid line A indicates the pressure in the combustion chamber 14. A period B indicated by a broken line is a period during which the intake valve 30 is open, and a period C indicated by a one-dot chain line is a period during which the exhaust valve 32 is open. Further, a period D is a period for injecting the raw material liquid from the raw material injection valve 44 to the heating evaporator 36, and a period E is a period for injecting the reformed fuel to the intake port. Period F is a combustion period.

  In the combustion period F of a certain cylinder, the raw material liquid is injected into the cylinder, and the injection of the raw material liquid causes the reformed fuel to be injected into the next cylinder in the ignition sequence.

  The timing of injecting the raw material liquid into the heating evaporation unit 36 can be within the combustion period of the cylinder as described above. The amount of heat necessary for the evaporation of the raw material liquid is about 5 to 20% of the lower heating value of the fuel when the hydrocarbon fuel and water are added together. The cooling loss of the internal combustion engine is normally about 10 to 40% of the lower heating value of the fuel, which is sufficient to evaporate the raw material liquid. By using cooling using latent heat of vaporization, the cooling efficiency is increased, and the temperature of the cylinder inner wall surface can be maintained at 100 to 200 ° C., which is suitable for engine operation. In addition, it is possible to accurately control the injection amount, the injection timing, and the like by injecting the liquid raw material.

  The volume of the raw material increases due to evaporation in the heating evaporation unit 36. The evaporated raw material is directed to the reforming unit 50 by this expansion. Further, the expansion causes the reformed fuel in the reforming unit 50 to be pushed out toward the ejection nozzle 60. The raw material that has reached the reforming unit 50 in this cycle remains in the reforming unit 50, and the reforming reaction proceeds in the period up to the next cycle. The residence time for reforming the hydrocarbon-based fuel into the hydrogen-containing gas by steam reforming is 200 to 900 ° C. and about several to several tens of milliseconds. In the case of a 4-step cycle engine, at 3000 rpm, one cycle is 40 milliseconds, and the reaction time is sufficient. At 6000 rpm, one cycle is shortened to 20 milliseconds, but since the load is high, the exhaust gas becomes higher temperature and the temperature of the catalyst becomes higher, so that the reforming reaction proceeds sufficiently. In a two-process cycle engine, one cycle takes half the time compared to a four-process cycle engine, but the exhaust loss is high and the amount of unburned gas increases. The heat of the reforming reaction is sufficiently supplied by the heat exchange and the increase of the combustion heat of the unburned gas. As described above, in the internal combustion engine 10, the amount and timing of the reformed fuel injected into the intake port 20 are determined by the amount and timing of the raw material liquid injected by the raw material injection valve 44. Further, when it is necessary to eject a large amount of fuel, the fuel is injected from the additional raw material injection valve 62 in accordance with the ejection timing.

  FIG. 5 is a diagram showing a schematic configuration of an internal combustion engine 70 according to another embodiment of the present invention. About the same structure as the above-mentioned internal combustion engine 10, the same code | symbol is attached | subjected and the description is abbreviate | omitted. The internal combustion engine 70 includes a reformed fuel tank 72 that temporarily stores the generated reformed fuel. The reformed fuel is sent to the reformed fuel tank 72 through a branch conduit 74 branched from the ejection conduit 58. The branch conduit 74 is provided with a control valve 76 to control the conduction state of the branch conduit 74. The branch conduit 74 and the control valve 76 are provided for each cylinder. The reformed fuel stored in the reformed fuel tank 72 is injected into the intake manifold 18 by the injection valve 78. In this embodiment, one injection valve 78 is provided before the intake manifold 18 branches. However, it may be provided for each cylinder after manifold branching or in the intake port 20.

  A control unit 80 that performs control for storing the reformed fuel in the tank is provided. The control unit 80 includes a signal from the pressure sensor 82 that detects the pressure in the reformed fuel tank 72, a signal indicating the temperature of the heating evaporation unit 36 and the reforming unit 50, engine speed, vehicle speed, and the like. A signal indicating information related to the traveling of the vehicle, a signal indicating the driver's intention such as an operation amount of the accelerator pedal, and the like are input. Based on these signals, the control unit 80 controls the material injection valve 44, the control valve 76, and the injection valve 78.

  The control unit 80, for example, when a low load or no load operation is performed after a high load operation, the raw material injection valve 44 so as to inject more raw material liquid than is necessary for driving the vehicle and maintaining the rotation of the internal combustion engine. To control. Since it is after the high load operation, the temperature of the heating evaporation unit 36 and the reforming unit 50 is high, and this is used to control to generate excessive reformed fuel and store the surplus. At this time, the control valve 76 is controlled at an appropriate timing, and surplus reformed fuel is guided to the reformed fuel tank 72. In particular, when the accelerator pedal is returned and the engine brake is applied, by injecting the raw material and storing the surplus of the generated reformed fuel, it can be effectively used for acceleration after deceleration. Further, when the heating evaporator 36 and the like are at a high temperature, the surroundings of the combustion chamber are simultaneously cooled by evaporating more fuel. In addition, after the pressure in the reformed fuel tank 72 reaches a predetermined pressure, the control for storing the reformed fuel is stopped.

  When the temperature of the internal combustion engine is low or for acceleration, the stored reformed fuel can be supplied from the injection valve 78, while the supply amount from the raw material injection valve 44 can be reduced or eliminated. Thereby, harmful components such as unburned hydrocarbons, carbon monoxide, and nitrogen oxides can be greatly reduced. In particular, at the time of cold start, harmful components in the exhaust gas can be greatly reduced by using a reformed fuel with good ignitability. Further, even in a vehicle that performs idling stop, the startability at the time of restart is good.

  The reformed fuel tank 72 is provided with a discharge valve for discharging components that are condensed in the reformed fuel at room temperature. When the engine is cooled after being stopped, water and the like are condensed and discharged out of the tank 72. As a result, the content of the condensate component of the reformed fuel in the reformed fuel tank 72 is reduced, and at the next start-up, fuel containing almost no condensate component can be supplied.

  In the above description, a four-cylinder internal combustion engine has been described. However, the present invention can also be applied to internal combustion engines having other numbers of cylinders. When applied to an engine having a different number of cylinders, the injection timing from the raw material injection valve 44 is set to synchronize with the intake timing of the cylinder to which the reformed fuel is supplied by the injection of the raw material liquid. Moreover, although the example which provides the heating evaporation part 36 in a cylinder block was demonstrated, it can also provide in a cylinder head, and can also provide in the circumference | surroundings of engine bodies, such as a block, instead of the inside of a cylinder block etc.

  In the present embodiment, air is not used to generate the reformed fuel, and the reformed fuel can be prevented from containing nitrogen in the air. This relatively increases the hydrogen content. Further, a compressor for compressing air is not necessary. Further, since the reforming energy is not obtained by burning a part of the raw material, the fuel consumption rate can be improved. Further, by storing the reformed fuel generated in the tank and using it at the time of starting or the like, it is possible to improve startability and reduce harmful components in the exhaust at the time of starting.

1 is a diagram showing a schematic configuration of an internal combustion engine 10 according to an embodiment of the present invention. It is a figure which shows the detailed structure around a combustion chamber. It is a figure which shows the destination where the evaporated raw material is supplied. It is a time chart regarding the operation | movement which concerns on the production | generation and ejection of a reformed fuel. It is a figure which shows schematic structure of the internal combustion engine 70 which concerns on other embodiment of this invention.

Explanation of symbols

  10, 70 Internal combustion engine, 12 cylinder head, 14 combustion chamber, 16 cylinder, 18 intake manifold, 20 intake port, 22 exhaust manifold, 24 exhaust port, 26 cylinder block, 36 heating evaporation section, 38 heat transfer body, 40 heat insulator , 42 Heating evaporation chamber, 44 Raw material injection valve, 50 reforming section, 52 reforming catalyst section, 54 heat accumulator, 56 heat insulator, 58 ejection conduit, 60 ejection nozzle, 72 reformed fuel tank, 78 injection valve.

Claims (8)

An internal combustion engine using reformed fuel,
A heating evaporation section provided around the internal combustion engine body for heating and evaporating a liquid raw material;
A reforming unit provided in the vicinity of the exhaust flow path and heated by exhaust gas, the reforming unit reforming the evaporated raw material to generate a reformed fuel;
An injection nozzle for injecting the reformed fuel into the intake passage or the cylinder;
I have a,
The internal combustion engine is a multi-cylinder engine, and the heating evaporation unit, the reforming unit, and the ejection nozzle are provided for each cylinder,
The raw material evaporated in the heating evaporation section of the first cylinder in the compression stroke or the expansion stroke is directed to the reforming section of the second cylinder in the intake stroke, and is ejected to the second cylinder by the ejection nozzle.
Internal combustion engine. An internal combustion engine using reformed fuel,
A heating evaporation section that is formed in a cylinder block or a cylinder head around the combustion chamber and heats and evaporates the liquid raw material by the heat of the combustion chamber;
A reforming unit provided in the vicinity of the exhaust flow path and heated by exhaust gas, the reforming unit reforming the evaporated raw material to generate a reformed fuel;
An injection nozzle for injecting the reformed fuel into the intake passage or the cylinder;
I have a,
The internal combustion engine is a multi-cylinder engine, and the heating evaporation unit, the reforming unit, and the ejection nozzle are provided for each cylinder,
The raw material evaporated in the heating evaporation section of the first cylinder in the compression stroke or the expansion stroke is directed to the reforming section of the second cylinder in the intake stroke, and is ejected to the second cylinder by the ejection nozzle.
Internal combustion engine. An internal combustion engine using reformed fuel,
A heating evaporation section provided around the internal combustion engine body for heating and evaporating a liquid raw material;
A reforming unit provided in the vicinity of the exhaust flow path and heated by exhaust gas, the reforming unit reforming the evaporated raw material to generate a reformed fuel;
An injection nozzle for injecting the reformed fuel into the intake passage or the cylinder;
I have a,
The internal combustion engine is a four-stroke cycle four-cylinder engine, and the raw material is supplied to the heating and evaporating portion of the first cylinder near the explosion top dead center of the first cylinder. It goes to the reforming part of the second cylinder in the next ignition sequence, and is ejected to the second cylinder by the ejection nozzle.
Internal combustion engine. An internal combustion engine using reformed fuel,
A heating evaporation section that is formed in a cylinder block or a cylinder head around the combustion chamber and heats and evaporates the liquid raw material by the heat of the combustion chamber;
A reforming unit provided in the vicinity of the exhaust flow path and heated by exhaust gas, the reforming unit reforming the evaporated raw material to generate a reformed fuel;
An injection nozzle for injecting the reformed fuel into the intake passage or the cylinder;
I have a,
The internal combustion engine is a four-stroke cycle four-cylinder engine, and the raw material is supplied to the heating and evaporating portion of the first cylinder near the explosion top dead center of the first cylinder. It goes to the reforming part of the second cylinder in the next ignition sequence, and is ejected to the second cylinder by the ejection nozzle.
Internal combustion engine. The internal combustion engine according to any one of claims 1 to 4 , further comprising:
A heat storage unit that stores the heat of exhaust gas and retains the reforming unit, and has an integrated heat storage unit with a plurality of cylinders,
Internal combustion engine. The internal combustion engine according to any one of claims 1 to 5,
A reformed fuel tank for storing a part of the generated reformed fuel; and
An injection valve for injecting the stored reformed fuel into the intake passage or the cylinder;
An internal combustion engine.   The internal combustion engine according to claim 6, wherein the stored reformed fuel is supplied to intake air when the internal combustion engine is started or accelerated. The internal combustion engine according to any one of claims 1 to 7, wherein the raw materials for the reformed fuel are an organic compound liquid fuel and water.

Images