JP2006022731A - Internal combustion engine using hydrogen - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase generation amount of hydrogen by improving reaction efficiency, and to improve dehydrogenation reaction performance and exhaust emission control performance in an internal combustion engine using hydrogen. <P>SOLUTION: This internal combustion engine using hydrogen is provided with a casing 74 introduced into an exhaust pipe 14 of the internal combustion engine 10, an exhaust emission control catalyst 78 arranged near the casing 74 in the exhaust pipe 14, a catalyst 72 provided in the casing 74, a hydrogenated gasoline injector 24 for supplying fuel containing organic hydride to the catalyst 72, and a hydrogen supply injector 18 for supplying hydrogen taken from the fuel containing organic hydride by dehydrogenation reaction on the catalyst 72 to the internal combustion engine 10. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a hydrogen-utilizing internal combustion engine.

  Conventionally, as disclosed in, for example, Japanese Patent Application Laid-Open No. 2003-343360, an internal combustion engine system having a hydrogen generation function is known. Specifically, this system uses a hydrogenated fuel containing an organic hydride such as decalin as a raw material to generate a hydrogen rich gas and a dehydrogenated product such as naphthalene, and the generated hydrogen rich gas as a fuel. It has a working hydrogen engine.

  The system disclosed in the above publication separates hydrogenated fuel into a hydrogen-rich gas and a dehydrogenated product using heat generated during the operation of the hydrogen engine. More specifically, hydrogenated fuel is injected onto the catalyst, and a dehydrogenation reaction is caused on the catalyst to take out hydrogen. At this time, in order to efficiently extract hydrogen, the catalyst is heated using the waste heat of the engine.

JP 2003-343360 A JP-A-6-2615 JP 2002-255503 A

  As a method of heating the catalyst using the waste heat of the engine, it is conceivable to heat the catalyst using the energy of the exhaust gas of the engine. However, when hydrogen is extracted by heating the catalyst using the energy of the exhaust gas, if the exhaust heat cannot be used effectively, the amount of hydrogen extracted with respect to the amount of hydrogen required by the engine may be insufficient.

  In addition, it is necessary to purify the exhaust gas discharged from the internal combustion engine. However, if the energy of the exhaust gas is used for the dehydrogenation reaction, the amount of heat supplied to the catalyst for purifying the exhaust gas is reduced, thereby purifying the exhaust gas. The problem is that the performance is degraded. Therefore, it is necessary to improve both the performance of the dehydrogenation reaction and the exhaust purification performance.

  The present invention has been made to solve the above-described problems. In a hydrogen-using engine that causes a dehydrogenation reaction using the energy of exhaust gas, the reaction efficiency is improved and the amount of hydrogen generated is increased. At the same time, it aims at improving both dehydrogenation reaction performance and exhaust gas purification performance.

  In order to achieve the above object, a first invention provides a casing introduced into an exhaust passage of an internal combustion engine, an exhaust purification catalyst disposed in the exhaust passage so as to surround the periphery of the casing, A dehydrogenation reaction catalyst provided in the casing; a fuel supply means for supplying an organic hydride-containing fuel toward the dehydrogenation reaction catalyst; and the organic hydride-containing material by a dehydrogenation reaction on the dehydrogenation reaction catalyst. And hydrogen supply means for supplying hydrogen taken out of the fuel to the internal combustion engine.

  According to a second invention, in the first invention, the casing is provided so as to extend in a longitudinal direction of the exhaust passage.

  A third invention is characterized in that, in the first or second invention, an end of the casing is disposed outside the exhaust passage, and the fuel supply means is provided at the end of the casing. .

  According to the first invention, since the casing provided with the dehydrogenation reaction catalyst is introduced into the exhaust passage, the periphery of the dehydrogenation reaction catalyst can be surrounded by the exhaust gas, and the heat of the exhaust gas is dehydrogenated. It is possible to sufficiently supply the reaction catalyst. In addition, since the exhaust purification catalyst is provided in the exhaust passage so as to surround the periphery of the casing, the combustion heat generated when the unburned components in the exhaust gas are burned in the exhaust purification catalyst is used for the dehydrogenation reaction in the casing. Can be applied to the catalyst. Therefore, exhaust heat of the exhaust gas and combustion heat in the exhaust purification catalyst can be given to the dehydrogenation reaction catalyst, and heat supply to the dehydrogenation reaction catalyst can be performed reliably. Furthermore, since both the dehydrogenation reaction and the exhaust purification can be performed in the vicinity of the region where the casing is provided, the system can be reduced in size.

  According to the second invention, since the casing is provided so as to extend in the longitudinal direction of the exhaust passage, the flow direction of the exhaust gas and the longitudinal direction of the casing can be matched, and the surface area of the dehydrogenation reaction catalyst is maximized. Can be expanded. Therefore, the utilization efficiency of the dehydrogenation reaction catalyst can be increased, and the reaction amount of the dehydrogenation reaction can be increased.

  According to the third invention, since the end of the casing is disposed outside the exhaust passage and the fuel supply means is provided at the end of the casing, there is no need to penetrate the fuel supply means through the exhaust passage. A structure for supplying an organic hydride-containing fuel toward the dehydrogenation reaction catalyst can be easily manufactured.

  An embodiment of the present invention will be described below with reference to the drawings. In addition, the same code | symbol is attached | subjected to the element which is common in each figure, and the overlapping description is abbreviate | omitted. The present invention is not limited to the following embodiments.

  FIG. 1 is a diagram for explaining a configuration of an internal combustion engine system according to each embodiment of the present invention. This system includes an internal combustion engine 10. An intake pipe 12 and an exhaust pipe 14 communicate with the internal combustion engine 10.

  A throttle valve 16 for controlling the intake air amount is incorporated in the intake pipe 12. A hydrogen supply injector 18 is disposed downstream of the throttle valve 16. A gasoline supply injector 20 is disposed at the intake port of the internal combustion engine 10.

  A hydrogen rich gas is supplied to the hydrogen supply injector 18 at a predetermined pressure, as will be described later. The hydrogen supply injector 18 opens a valve in response to a drive signal supplied from the outside, and can inject an amount of hydrogen rich gas into the intake pipe 12 according to the valve opening time. In the system shown in FIG. 1, the hydrogen supply injector 18 is arranged in the intake pipe 12, but the arrangement is not limited to this. That is, the hydrogen supply injector 18 may be incorporated in the main body of the internal combustion engine 10 so that hydrogen can be injected into the cylinder.

  As will be described later, gasoline is supplied to the gasoline supply injector 20 at a predetermined pressure. The gasoline supply injector 20 opens a valve in response to a drive signal supplied from the outside, so that an amount of gasoline corresponding to the valve opening time can be injected into the intake port.

  A dehydrogenation reactor 22 is attached to the exhaust pipe 14. In addition, a hydrogenated gasoline injector 24 is assembled on the upper part of the dehydrogenation reactor 22.

  As will be described later, the hydrogenated gasoline injector 24 is supplied with hydrogenated gasoline at a predetermined pressure. The hydrogenated gasoline injector 24 is opened in response to a drive signal supplied from the outside, so that it corresponds to the valve opening time. An amount of hydrogenated gasoline can be fed into the dehydrogenation reactor 22. Here, the amount of hydrogen required by the internal combustion engine 10 varies depending on the operating state of the internal combustion engine 10. The ECU 80 stores a map that defines the relationship between the amount of hydrogen required by the internal combustion engine 10 and the operating state (engine speed, load (throttle opening)), and obtains the required amount of hydrogen from this map. The valve opening / closing state of the hydrogenated gasoline injector 24 is controlled. Further, the dehydrogenation reactor 22 uses the exhaust heat radiated from the exhaust pipe 14 to separate the hydrogenated gasoline supplied as described above into a hydrogen rich gas and a dehydrogenated gasoline and flow them out. have.

An exhaust temperature sensor 25 is incorporated in the exhaust pipe 14 upstream of the dehydrogenation reactor 22. Further, an O ₂ sensor 26 and a NOx sensor 28 are incorporated in the exhaust pipe 14 downstream of the dehydrogenation reactor 22. The O ₂ sensor 26 is a sensor that emits an output corresponding to the exhaust air-fuel ratio based on the presence or absence of oxygen in the exhaust gas. The NOx sensor 28 is a sensor that emits an output corresponding to the NOx concentration in the exhaust gas. A catalyst 30 for purifying exhaust gas is disposed downstream of these sensors 26 and 28.

  The system of this embodiment includes a hydrogenated gasoline tank 32. In the hydrogenated gasoline tank 32, hydrogenated gasoline containing a large amount of organic hydride as compared with general gasoline is stored. Here, the “organic hydride” is a hydrocarbon (HC) component that causes a dehydrogenation reaction at a temperature of about 300 ° C., and specifically, decalin and cyclohexane correspond to this.

Ordinary gasoline (LFT-1C) contains about 40% of toluene. When toluene is hydrogenated, methylcyclohexane (C ₇ H ₁₄ ), which is an organic hydride, can be produced. That is, hydrogenation gasoline containing about 40% of methylcyclohexane can be generated by hydrogenating toluene contained in ordinary gasoline as a raw material. In the present embodiment, for the sake of convenience, the hydrogenated gasoline tank 32 is supplied with hydrogenated gasoline having such a composition.

  A hydrogenated gasoline supply pipe 34 communicates with the hydrogenated gasoline tank 32. The hydrogenated gasoline supply pipe 34 includes a pump 36 in the middle thereof and communicates with the hydrogenated gasoline injector 24 at the end thereof. Hydrogenated gasoline in the hydrogenated gasoline tank 32 is pumped up by a pump 36 during operation of the internal combustion engine, and is supplied to the hydrogenated gasoline injector 24 at a predetermined pressure.

  The hydrogenated gasoline injector 24 is assembled to the upper part of the dehydrogenation reactor 22 as described above. The dehydrogenation reactor 22 is an apparatus for processing hydrogenated gasoline using exhaust heat. For this reason, during operation of the internal combustion engine, the interior of the dehydrogenation reactor 22 rises to a temperature exceeding 300 ° C.

  The hydrogenated gasoline injector 24 is assembled so that the main portion protrudes into the space above the dehydrogenation reactor 22 in order to avoid direct exposure to the internal temperature. For this reason, according to the system of this embodiment, the temperature of the hydrogenated gasoline injector 24 does not become unduly high.

  In the system shown in FIG. 1, the hydrogenated gasoline injector 24 is cooled by air, but the cooling method is not limited to this. For example, a cooling water passage for guiding the cooling water of the internal combustion engine 10 to the periphery of the hydrogenated gasoline injector 24 may be provided to cool the hydrogenated gasoline injector 24 with water.

  A reaction chamber is formed inside the dehydrogenation reactor 22. The fuel injected from the hydrogenated gasoline injector 24 is separated into hydrogen-rich gas and dehydrogenated gasoline inside the reaction chamber, and is led to a pipe line 38 connected to the dehydrogenation reactor 22. A separation device 40 communicates with the dehydrogenation reactor 22 via a pipe line 38.

As described above, the hydrogenated gasoline used in the present embodiment is obtained by organically hydrating toluene contained in normal gasoline. Therefore, if the hydrogenated gasoline is subjected to a dehydrogenation treatment, hydrogen-rich gas and ordinary gasoline are generated as a result. Specifically, methylcyclohexane C ₇ H ₁₄ which is an organic hydride is separated into hydrogen H ₂ and toluene C ₇ H ₈ as follows by a dehydrogenation reaction.
C ₇ H ₁₄ → C ₇ H ₈ + 3H ₂ (1)
The dehydrogenation reaction represented by the formula (1) is an endothermic reaction.

  For this reason, specifically, a mixture of hydrogen-rich gas and ordinary gasoline is supplied from the dehydrogenation reactor 22 to the separation device 40.

  The separation device 40 has a function of cooling the high-temperature hydrogen-rich gas and dehydrogenated gasoline (ordinary gasoline) supplied from the dehydrogenation reactor 22 and separating them. Similar to the internal combustion engine 10, the separation device 40 is water-cooled by circulating cooling water. For this reason, the separator 40 can cool the hydrogen rich gas and the dehydrogenated gasoline efficiently.

  A liquid storage space for storing dehydrogenated gasoline liquefied by being cooled is provided at the bottom of the separation device 40. Further, a gas storage space for storing the hydrogen-rich gas remaining as a gas is secured above the storage space. The separator 40 is connected with a gasoline pipe line 42 so as to communicate with the liquid storage space, and with a hydrogen pipe line 44 so as to communicate with the gas storage space.

  The gasoline pipeline 42 communicates with the gasoline buffer tank 48. Although FIG. 1 shows a configuration in which the hydrogenated gasoline tank 32 and the gasoline buffer tank 48 are arranged at positions separated from each other, the configuration is not limited to this. That is, they may be housed in a single housing.

  A liquid amount sensor 58 is assembled in the gasoline buffer tank 48. The liquid amount sensor 58 is a sensor that emits an output corresponding to the amount of dehydrogenated gasoline stored therein. In addition, a gasoline supply pipe 60 communicates with the gasoline buffer tank 48. The gasoline supply pipe 60 includes a pump 62 in the middle thereof and communicates with the gasoline supply injector 20 at an end thereof. The dehydrogenated gasoline in the gasoline buffer tank 48 is pumped up by the pump 62 during operation of the internal combustion engine, and is supplied to the gasoline supply injector 20 at a predetermined pressure.

  The hydrogen pipe 44 communicates with the hydrogen buffer tank 64. The hydrogen pipe 44 incorporates a pump 66 for pumping the hydrogen-rich gas in the separator 40 to the hydrogen buffer tank 64 and a relief valve 68 for preventing the discharge side pressure of the pump 66 from becoming excessive. It is. According to the pump 66 and the relief valve 68, the hydrogen rich gas can be fed into the hydrogen buffer tank 64 within a range in which the internal pressure does not become excessive.

  A pressure sensor 70 is assembled in the hydrogen buffer tank 64. The pressure sensor 70 is a sensor that generates an output corresponding to the internal pressure of the hydrogen buffer tank 64. According to the output of the pressure sensor 70, the amount of hydrogen rich gas stored in the hydrogen buffer tank 64 can be estimated.

  A hydrogen supply pipe 71 communicates with the hydrogen buffer tank 64. The hydrogen supply pipe 71 includes a regulator 73 in the middle thereof and communicates with the hydrogen supply injector 18 at an end thereof. According to such a configuration, the hydrogen rich gas is supplied to the hydrogen supply injector 18 by the pressure adjusted by the regulator 73 on the condition that the hydrogen rich gas is stored in the hydrogen buffer tank 64.

The system of this embodiment includes an ECU 80. The ECU 80 has a function of controlling the system of this embodiment. That is, the ECU 80 is supplied with outputs from various sensors such as the O ₂ sensor 26, the NOx sensor 28, the liquid amount sensor 58, and the pressure sensor 70 described above. The ECU 80 is connected to the above-described pumps 36, 62, 66 and actuators such as the injectors 18, 20, 24. The ECU 80 can appropriately drive the various actuators described above by performing predetermined processing based on these sensor outputs.

In the system of the present embodiment configured as described above, the internal combustion engine 10 is operated by lean burn combustion using both gasoline (dehydrogenated fuel) obtained by dehydrogenating hydrogenated gasoline and hydrogen. be able to. According to the operation by lean burn combustion, fuel efficiency and efficiency can be improved. Further, it is possible to suppress the emission of NO _X, it is possible to improve the emission.

  Further, according to the system of the present embodiment, when output is required in a high load, high rotation range, etc., the internal combustion engine 10 can be operated by stoichiometric combustion using only gasoline (dehydrogenated fuel).

  Next, based on FIG.2 and FIG.3, the structure of the dehydrogenation reactor 22 is demonstrated in detail. FIG. 2 is a cross-sectional view showing the configuration of the dehydrogenation reactor 22. As shown in FIG. 2, a catalyst 72 for causing a dehydrogenation reaction is provided in a casing 74, and the casing 74 is inserted into the exhaust pipe 14 with its longitudinal direction facing the exhaust gas flow direction. Yes. Both ends of the casing 74 protrude out of the exhaust pipe 14, and a hydrogenated gasoline injector 24 is provided at the upper end. A heat insulating material 76 is wound around the outer periphery of the exhaust pipe 14 in the region where the casing 74 is inserted.

An exhaust purification catalyst 78 is inserted in a ring shape between the casing 74 and the inner wall of the exhaust pipe 14. The exhaust gas flowing in the exhaust pipe 14 passes through a region where the exhaust purification catalyst 78 is provided. The exhaust purification catalyst 78 has a function similar to that of a normal three-way catalyst, oxidizes unburned components (HC, CO) contained in the exhaust gas, and nitrogen oxides (NO _x ) in the exhaust gas. Has the function of reducing In the internal combustion engine system of the present embodiment, lean burn combustion is mainly performed, so the content of nitrogen oxides in the exhaust gas is relatively small. Therefore, in the exhaust purification catalyst 78, a reaction that mainly burns and oxidizes unburned components in the exhaust gas is performed.

  As shown in FIG. 2, the volume (surface area) of the catalyst 72 is maximized while keeping the expansion of the diameter of the exhaust pipe 14 to a minimum by matching the flow direction of the exhaust gas with the longitudinal direction of the casing 74. Can be expanded. Therefore, the utilization efficiency of the catalyst 72 can be increased.

  FIG. 3 is a cross-sectional view showing a cross section taken along the alternate long and short dash line I-I ′ of FIG. 2. As shown in FIG. 3, the casing 74 is arranged at the center in the exhaust pipe 14 and has a two-layer structure in which a region where exhaust gas flows is arranged outside a region where hydrogenated gasoline is supplied. . An exhaust purification catalyst 78 is inserted in the region where the exhaust gas flows. As a result, the casing 74 is surrounded by the exhaust gas flowing outside in the exhaust pipe 14, and the heat supply to the catalyst 72 can be efficiently performed.

  Further, in the exhaust purification catalyst 78, combustion of unburned components in the exhaust gas is mainly performed, so that combustion heat is generated in the exhaust purification catalyst 78. Therefore, exhaust heat of the exhaust gas and reaction heat due to combustion can be applied to the catalyst 72 in the casing 74.

  In particular, in the case of lean burn combustion, the exhaust gas temperature is lower than that in stoichiometric combustion, so that heat supply to the catalyst 72 may be insufficient with only exhaust heat. Therefore, by supplying combustion heat from the exhaust purification catalyst 78 into the casing 74, the temperature of the catalyst 72 can be reliably raised, and the reaction efficiency can be increased.

  Thereby, the dehydrogenation reaction in the catalyst 72 can be promoted by utilizing the exhaust heat of the exhaust gas and the combustion heat in the exhaust purification catalyst 78. As described above, since the dehydrogenation reaction is an endothermic reaction, as the reaction amount increases, the temperature of the catalyst 72 may decrease and the reaction efficiency may decrease. However, according to the configuration of the present embodiment, the reaction amount is large. Even in this case, it is possible to minimize a decrease in the internal temperature of the catalyst 72. Thereby, a large amount of hydrogen can always be generated stably. Moreover, since the heat insulating material 76 is wound around the exhaust pipe 14 in the region where the casing 74 is inserted, it is possible to minimize the exhaust heat from leaking to the outside, and to further improve the efficiency of using the exhaust heat. .

  Further, since the exhaust purification catalyst 78 can be provided in the dehydrogenation reactor 22, a catalyst for purifying the exhaust can be disposed on the upstream side of the exhaust pipe 14. Therefore, it becomes possible to send exhaust gas having a higher temperature to the exhaust purification catalyst 78 and to warm up the exhaust purification catalyst 78 in a shorter time. Thereby, the exhaust purification catalyst 78 can be activated at an early stage after the engine is started, and the exhaust purification performance can be exhibited.

  Furthermore, according to the configuration of the present embodiment, since the end portion of the casing 74 protrudes to the outside of the exhaust pipe 14, fuel can be supplied to the catalyst 72 simply by mounting the hydrogenated gasoline injector 24 on the end portion. Is possible. Accordingly, it is not necessary to provide an opening for supplying fuel to the catalyst 72 in the exhaust pipe 14 itself, and the fuel can be supplied to the catalyst 72 with a simple configuration. Therefore, the productivity of the dehydrogenation reactor 22 can be increased. In addition, since the dehydrogenation reactor 22 has a two-layer structure, the diameter can be reduced as compared with a structure having three or more layers, and the mountability to the system can be improved. Further, since the dehydrogenation reactor 22 has a two-layer structure, the production can be easily performed.

  Further, since the exhaust purification catalyst 78 is provided in the dehydrogenation reactor 22, both hydrogen generation and exhaust purification can be performed in the dehydrogenation reactor 22. Therefore, the catalyst 30 downstream of the dehydrogenation reactor 22 can be reduced in size, and depending on the purification function of the exhaust purification catalyst 78, there is no need to provide the catalyst 30. As a result, the system can be configured in a simple manner, and downsizing of the system can be achieved.

  2 and 3, an example of a two-layer structure in which an exhaust gas flow path is provided outside the region where the dehydrogenation reaction is performed is shown, but the present invention is not limited to this structure. FIG. 4 is a schematic view showing another configuration of the dehydrogenation reactor 22, and shows a cross section along a direction orthogonal to the flow direction of the exhaust gas, as in FIG. As shown in FIG. 4, a ring-shaped casing 74 may be introduced into the exhaust pipe 14, and an exhaust purification catalyst 78 may be disposed around and around the center of the ring-shaped casing 74. Also with this configuration, both exhaust heat and combustion heat can be applied to the catalyst 72 in the casing 74.

  Further, in FIG. 2, the hydrogenated gasoline injector 24 is provided only at the upper end portion of the casing 74, but the hydrogenated gasoline injector 24 is provided at both ends of the casing 74, so You may make it inject hydrogenated gasoline toward. Thereby, the reaction efficiency in the catalyst 72 can be improved, and the production amount of hydrogen can be increased.

  As described above, according to the present embodiment, the casing 74 containing the catalyst 72 is inserted into the exhaust pipe 14, and the casing 74 is surrounded by the high-temperature exhaust gas. It becomes possible. Further, since the exhaust purification catalyst 78 is provided outside the casing 74 in the exhaust pipe 14, combustion heat when the unburned components are burned by the exhaust purification catalyst 78 can be given to the catalyst 72 in the casing 74. Therefore, exhaust heat of the exhaust gas and reaction heat due to combustion can be given to the catalyst 72 in the casing 74, and heat supply to the catalyst 72 can be reliably performed.

  As a result, the efficiency of heat supply to the catalyst 72 can be increased, and a decrease in the temperature of the catalyst 72 can be suppressed, so that the efficiency of the dehydrogenation reaction in the catalyst 72 can be increased. Therefore, a large amount of hydrogen can always be generated stably. In addition, since both hydrogen generation and exhaust gas purification can be performed in the dehydrogenation reactor 22, the system can be simply configured, and downsizing of the system can be achieved.

It is a mimetic diagram for explaining the composition of the internal-combustion engine system concerning one embodiment of the present invention. It is sectional drawing which shows the structure of the dehydrogenation reactor which concerns on one Embodiment of this invention. FIG. 3 is a cross-sectional view showing a cross section taken along one-dot chain line I-I ′ of FIG. 2. It is sectional drawing which shows the other example of one Embodiment of this invention.

Explanation of symbols

14 Exhaust pipe 18 Hydrogen supply injector 24 Hydrogenated gasoline injector 25 Exhaust temperature sensor 72 Catalyst 74 Casing 78 Exhaust purification catalyst

Claims (3)

A casing introduced into the exhaust passage of the internal combustion engine;
In the exhaust passage, an exhaust purification catalyst arranged so as to surround the periphery of the casing;
A dehydrogenation reaction catalyst provided inside the casing;
Fuel supply means for supplying an organic hydride-containing fuel toward the dehydrogenation reaction catalyst;
Hydrogen supply means for supplying hydrogen extracted from the organic hydride-containing fuel to the internal combustion engine by a dehydrogenation reaction on the dehydrogenation reaction catalyst;
An internal combustion engine using hydrogen.   The hydrogen-utilizing internal combustion engine according to claim 1, wherein the casing is provided so as to extend in a longitudinal direction of the exhaust passage.   The hydrogen-utilized internal combustion engine according to claim 1 or 2, wherein an end of the casing is disposed outside the exhaust passage, and the fuel supply means is provided at the end of the casing.

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