JP4569373B2 - Internal combustion engine using hydrogen - Google Patents

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 includes a dehydrogenation catalyst. By supplying a hydrogenated fuel to the dehydrogenation catalyst to cause a dehydrogenation reaction, the hydrogenated fuel is converted into a hydrogen rich gas and a dehydrogenated product. To separate. The dehydrogenation catalyst is heated to a temperature at which a dehydrogenation reaction can be performed by waste heat of the hydrogen engine.

  The dehydrogenation catalyst tends to deteriorate when the temperature becomes too high. More specifically, if the temperature of the dehydrogenation catalyst becomes too high, sintering of the precious metals constituting the catalyst may occur, or carbon in the hydrogenated fuel may be liberated and coking may occur covering the catalyst surface. Thus, the function of the dehydrogenation catalyst is likely to be reduced.

  The system disclosed in the above publication includes a cooling water circulation system that cools the dehydrogenation catalyst, and a temperature control device that controls the operation of the cooling water circulation system (see paragraph number 0037 of the publication). This prevents the temperature of the dehydrogenation catalyst from becoming too high.

JP 2003-343360 A JP 7-63218 A

  However, in the above-described conventional system, since it is necessary to provide a cooling water channel or a cooling water pump for cooling the dehydrogenation catalyst, the system becomes complicated and large. For this reason, there is a demand for suppressing deterioration of the dehydrogenation catalyst with a simpler system.

  Further, in the above-described conventional system, management such as periodic replacement of cooling water is necessary, so that maintenance becomes complicated. For this reason, there is also a demand to suppress degradation of the dehydrogenation catalyst with a system that is easy to maintain.

  The present invention has been made to solve the above-described problems, and provides a hydrogen-based internal combustion engine that can effectively suppress deterioration of a dehydrogenation catalyst, has a simple structure, and is easy to maintain. The purpose is to do.

In order to achieve the above object, a first invention is a hydrogen-utilizing internal combustion engine,
A dehydrogenation catalyst which is provided to be heated by the heat of exhaust gas of an internal combustion engine and separates hydrogenated fuel containing organic hydride into hydrogen and dehydrogenated fuel;
Temperature detecting means for detecting the temperature of the dehydrogenation catalyst;
When the temperature of the dehydrogenation catalyst exceeds the first determination value, the supply amount of the hydrogenated fuel to the dehydrogenation catalyst is made larger than when the temperature of the dehydrogenation catalyst is equal to or lower than the first determination value. An increasing means for increasing the amount;
It is characterized by providing.

The second invention is the first invention, wherein
Supply means for supplying hydrogen and dehydrogenated fuel separated by the dehydrogenation catalyst to the internal combustion engine;
When the supply amount of hydrogenated fuel to the dehydrogenation catalyst is increased by the increasing means, the addition of hydrogen supplied to the internal combustion engine is greater than when the supply amount of hydrogenated fuel is not increased. Means for increasing the proportion of hydrogen to increase the proportion;
It is characterized by providing.

The third invention is the second invention, wherein
Lean-burn operation means for lean-burning the internal combustion engine when a lean-burn condition is established;
In the lean burn operation, when the addition ratio of hydrogen supplied to the internal combustion engine is increased by the hydrogen ratio increasing means, the air-fuel mixture is made leaner than when the addition ratio of hydrogen is not increased. Means to
It is characterized by providing.

Moreover, 4th invention is 2nd or 3rd invention,
Normal operating means for normally operating the internal combustion engine with stoichiometric or rich air-fuel mixture when lean burn conditions are not established;
Ignition that advances the ignition timing when the hydrogen addition ratio supplied to the internal combustion engine is increased by the hydrogen ratio increasing means during the normal operation than when the hydrogen addition ratio is not increased. Timing advance means,
It is characterized by providing.

Further, a fifth invention is any one of the first to fourth inventions,
The apparatus further comprises prohibiting means for prohibiting the supply of hydrogenated fuel to the dehydrogenation catalyst when the temperature of the dehydrogenation catalyst exceeds a second determination value that is greater than the first determination value.

Further, a sixth invention is any one of the second to fourth inventions,
Prohibiting means for prohibiting the supply of hydrogenated fuel to the dehydrogenation catalyst when the temperature of the dehydrogenation catalyst exceeds a second determination value greater than the first determination value;
Hydrogen supply prohibiting means for prohibiting supply of hydrogen to the internal combustion engine when supply of hydrogenated fuel to the dehydrogenation catalyst is prohibited by the prohibiting means;
It is characterized by providing.

  According to the first invention, when the temperature of the dehydrogenation catalyst is likely to be excessively high, it is possible to increase the amount of hydrogenated fuel supplied to the dehydrogenation catalyst. By increasing the supply amount of the hydrogenated fuel, a larger amount of dehydrogenation reaction, which is an endothermic reaction, occurs in the dehydrogenation catalyst, so that the temperature of the dehydrogenation catalyst can be lowered. For this reason, according to this invention, since it can suppress effectively that a dehydrogenation catalyst becomes high temperature too much, degradation of a dehydrogenation catalyst can be prevented. Furthermore, since a special mechanism for cooling the dehydrogenation catalyst is unnecessary, the structure is simple and maintenance is easy.

  According to the second invention, when the amount of hydrogenated fuel supplied to the dehydrogenation catalyst is increased, the amount of hydrogen consumption can be increased. Hydrogen, which is a gas, requires a lot of storage space. According to the present invention, when the amount of hydrogen produced increases by increasing the amount of hydrogenated fuel supplied to the dehydrogenation catalyst, the hydrogen can be consumed. It is possible to effectively prevent an excessive amount.

  According to the third aspect of the present invention, when the lean burn operation is performed under the condition that the addition ratio of hydrogen supplied to the internal combustion engine is increased, the air-fuel mixture can be further leaned. Since the exhaust gas temperature decreases as the air-fuel mixture becomes leaner, the exhaust gas temperature can be lowered by further reducing the air-fuel mixture. As a result, the temperature of the dehydrogenation catalyst can be lowered more rapidly. In this case, since the addition ratio of hydrogen having a combustion promoting effect is increased, even a lean air-fuel mixture can be combusted better than the normal hydrogen addition ratio.

  According to the fourth aspect of the invention, the ignition timing can be advanced when the normal operation is performed under the condition that the addition ratio of hydrogen supplied to the internal combustion engine is increased. If the ignition timing is advanced, it approaches MBT. When the ignition timing is brought close to MBT, the work amount of the burned gas increases, that is, exhaust loss decreases, so that the exhaust temperature decreases. Therefore, the exhaust gas temperature can be lowered by advancing the ignition timing in normal operation. As a result, the temperature of the dehydrogenation catalyst can be lowered more rapidly. In this case, since the addition ratio of hydrogen having an anti-knock effect is increased, knocking is less likely to occur than when hydrogen is not added or when the hydrogen addition ratio is small, and the ignition timing can be advanced. Become.

  According to the fifth invention, when the temperature of the dehydrogenation catalyst is excessively high for some reason, the supply of hydrogenated fuel to the dehydrogenation catalyst can be prohibited. Thereby, even when the dehydrogenation catalyst is at an excessively high temperature, the occurrence of catalyst deterioration such as coking can be prevented.

  According to the sixth aspect of the present invention, it is possible to avoid consuming hydrogen in a situation where the production of hydrogen is stopped by prohibiting the supply of hydrogenated fuel to the dehydrogenation catalyst. Therefore, it can be prevented that hydrogen with a relatively small storage amount is lost.

Embodiment 1 FIG.
[Description of system configuration]
FIG. 1 is a diagram for explaining a system configuration according to the first embodiment of the present invention. As shown in FIG. 1, the system of the present embodiment includes an internal combustion engine 10. An intake passage 12 and an exhaust passage 14 communicate with the internal combustion engine 10. The internal combustion engine 10 is provided with a spark plug 13 for igniting the air-fuel mixture in the combustion chamber.

  An air flow meter 15 for detecting the amount of intake air flowing into the internal combustion engine 10 is disposed in the intake passage 12. A throttle valve 16 for controlling the intake air amount is disposed downstream of the air flow meter 15. A hydrogen injector 18 is disposed downstream of the throttle valve 16. A gasoline injector 20 is disposed downstream of the hydrogen injector 18.

  A hydrogen rich gas is supplied to the hydrogen injector 18 at a predetermined pressure, as will be described later. The hydrogen 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 passage 12 according to the valve opening time. In the system shown in FIG. 1, the hydrogen injector 18 is arranged in the intake passage 12, but the arrangement is not limited to this. That is, the hydrogen 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 injector 20 at a predetermined pressure. The gasoline injector 20 opens a valve in response to a drive signal supplied from the outside, and can inject an amount of gasoline into the intake passage 12 according to the valve opening time. In the system shown in FIG. 1, the gasoline injector 20 is arranged in the intake passage 12, but the arrangement is not limited to this. That is, the gasoline injector 20 may be incorporated in the main body of the internal combustion engine 10 so that gasoline can be injected into the cylinder.

  A dehydrogenation reactor 22 is disposed in the middle of the exhaust passage 14. A dehydrogenation catalyst 21 is installed in the dehydrogenation reactor 22. The dehydrogenation catalyst 21 separates hydrogenated gasoline, which is a hydrogenated fuel, into hydrogen and gasoline by a dehydrogenation reaction. The dehydrogenation catalyst 21 is further accommodated in a cylindrical casing in the dehydrogenation reactor 22. A temperature sensor 23 that detects the temperature of the dehydrogenation catalyst 21 is installed in the vicinity of the dehydrogenation catalyst 21.

  When the exhaust gas passing through the exhaust passage 14 passes through the dehydrogenation reactor 22, it flows outside the casing that houses the dehydrogenation catalyst 21. Thereby, the dehydrogenation catalyst 21 can be heated to a temperature at which dehydrogenation reaction is possible (for example, 300 ° C. or more) with the heat of the exhaust gas. Further, the exhaust gas and the dehydrogenation catalyst 21 are not in direct contact.

The hydrogenated gasoline in the present embodiment contains a large amount of organic hydride as compared with general gasoline. 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. Hydrogenated gasoline can be produced, for example, as follows. 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.

  When such hydrogenated gasoline is dehydrogenated, hydrogen-rich gas and normal gasoline are produced. Such a dehydrogenation reaction is an endothermic reaction. Thus, “gasoline” in the present embodiment corresponds to dehydrogenated fuel produced by the dehydrogenation reaction of hydrogenated gasoline.

  In the present embodiment, the hydrogenated fuel and the dehydrogenated fuel are described as hydrogenated gasoline and gasoline, respectively. However, the hydrogenated fuel and the dehydrogenated fuel in the present invention are not limited thereto. . That is, the hydrogenated fuel is not limited to one produced by hydrogenating gasoline, but may be one produced by hydrogenating another type of fuel.

  A hydrogenated gasoline injector 24 is assembled on the top of the dehydrogenation catalyst 21. 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 supplied to the dehydrogenation catalyst 21. As described above, the hydrogenated gasoline supplied to the dehydrogenation catalyst 21 undergoes a dehydrogenation reaction and is separated into a hydrogen-rich gas and gasoline. A catalyst 30 for purifying exhaust gas is disposed downstream of the dehydrogenation reactor 22.

  The system of this embodiment includes a hydrogenated gasoline tank 32 that stores hydrogenated gasoline. The hydrogenated gasoline tank 32 is supplied with hydrogenated gasoline as described above. 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 so that the main portion protrudes into the space above the dehydrogenation reactor 22 in order to avoid direct exposure to the high temperature in the dehydrogenation reactor 22. For this reason, according to the system of this embodiment, the temperature of the hydrogenated gasoline injector 24 does not become unduly high.

  One end of a pipe line 38 is connected to the lower part of the dehydrogenation catalyst 21. The other end of the pipe line 38 communicates with the separation device 40. The mixture of the hydrogen rich gas and gasoline produced in the dehydrogenation catalyst 21 flows into the separation device 40 through the pipe line 38.

  The separation device 40 has a function of cooling the high-temperature hydrogen-rich gas and gasoline supplied from the dehydrogenation catalyst 21 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 separation apparatus 40 can cool hydrogen-rich gas and gasoline efficiently.

  A liquid storage space for storing 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 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 injector 20 at an end thereof. The gasoline in the gasoline buffer tank 48 is pumped up by the pump 62 during operation of the internal combustion engine 10 and is supplied to the gasoline 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 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 injector 18 at the end thereof. According to such a configuration, the hydrogen rich gas is supplied to the hydrogen 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 accelerator opening sensor 76 and a crank angle sensor 78. The accelerator opening sensor 76 is a sensor that detects the amount of depression of the accelerator pedal. The crank angle sensor 78 is a sensor that reverses the Hi output and the Lo output each time the crankshaft of the internal combustion engine 10 rotates by a predetermined rotation angle. According to the output of the crank angle sensor 78, it is possible to detect the rotational position and rotational speed of the crankshaft, and further the engine speed and the like.

  Furthermore, the system of this embodiment includes an ECU (Electronic Control Unit) 80. The ECU 80 is connected to various sensors such as the air flow meter 15, the temperature sensor 23, the accelerator opening sensor 76, and the crank angle sensor 78 described above. The ECU 80 is connected to devices such as the spark plug 13, the throttle valve 16, the injectors 18, 20 and 24, and the pumps 36, 62 and 66. The ECU 80 can drive the various devices described above by performing predetermined processing based on the sensor outputs.

[Outline of Operation of Embodiment 1]
When the internal combustion engine 10 is started, the ECU 80 starts to calculate the target value of the hydrogen rich gas to be supplied to the internal combustion engine 10 and the target value of gasoline according to a predetermined rule based on the operation state. During the operation of the internal combustion engine 10, the hydrogen injector 18 and the gasoline injector 20 are driven so that these target values are realized. As a result, the hydrogen rich gas stored in the hydrogen buffer tank 64 and the gasoline stored in the gasoline buffer tank 48 are each appropriately injected into the intake passage 12.

  If hydrogen and gasoline are supplied to the internal combustion engine 10 at the same time, a significantly large output can be obtained as compared with the case where only hydrogen is used as fuel. Further, as compared with the case where only gasoline is used as the fuel, the limit of the excess air ratio that can ensure stable combustion is significantly increased, and the fuel consumption characteristics and the emission characteristics can be remarkably improved. For this reason, according to the system of the present embodiment, it is possible to realize the internal combustion engine 10 having good fuel consumption characteristics, output characteristics, and emission characteristics.

  In the system of this embodiment, when the temperature of the dehydrogenation catalyst 21 in the dehydrogenation reactor 22 reaches about 300 ° C., the hydrogenated gasoline can be separated into hydrogen-rich gas and gasoline. The ECU 80 determines whether or not the dehydrogenation reactor 22 can execute the separation process based on the output of the temperature sensor 23 after the internal combustion engine 10 is started. When it is determined that the process can be executed, the hydrogenated gasoline injector 24 starts to inject hydrogenated gasoline.

  The injection amount of hydrogenated gasoline from the hydrogenated gasoline injector 24 is calculated by the ECU 80 according to a predetermined rule based on the hydrogen injection amount from the hydrogen injector 18 and the gasoline injection amount from the gasoline injector 20. .

  When injection of hydrogenated gasoline is started in this way, high-temperature gas in which hydrogen-rich gas and gasoline are mixed begins to flow out from the bottom of the dehydrogenation reactor 22. When this high-temperature gas is cooled by the separation device 40, gasoline begins to circulate through the gasoline pipeline 42 and hydrogen-rich gas begins to circulate through the hydrogen pipeline 44. Thereby, gasoline and hydrogen rich gas are supplied to the gasoline buffer tank 48 and the hydrogen buffer tank 64, respectively.

  As described above, the dehydrogenation catalyst 21 is heated by the heat of the exhaust gas. For this reason, when the operation state with a high exhaust temperature continues, the temperature of the dehydrogenation catalyst 21 may become higher than necessary. If the temperature of the dehydrogenation catalyst 21 continues to rise as it is and the dehydrogenation catalyst 21 becomes excessively hot, sintering of the noble metal constituting the catalyst will occur, or carbon in the hydrogenated gasoline will be liberated and the catalyst By causing caulking to cover the surface, it becomes easy to cause a decrease in the function of the dehydrogenation catalyst 21. Therefore, when the temperature of the dehydrogenation catalyst 21 is likely to become excessively high, it is necessary to cool the dehydrogenation catalyst 21.

  In the present embodiment, the dehydrogenation catalyst 21 is cooled by positively utilizing the endotherm due to the dehydrogenation reaction of hydrogenated gasoline. More specifically, when the dehydrogenation catalyst 21 needs to be cooled, the supply amount of hydrogenated gasoline to the dehydrogenation catalyst 21 is increased. By increasing the supply amount of hydrogenated gasoline to the dehydrogenation catalyst 21, a larger amount of dehydrogenation reaction, which is an endothermic reaction, occurs, so the endothermic amount at the dehydrogenation catalyst 21 increases. As a result, the temperature of the dehydrogenation catalyst 21 can be lowered.

  Thus, when the supply amount of hydrogenated gasoline to the dehydrogenation catalyst 21 is increased, the production amounts of hydrogen and gasoline are also increased. As described above, the produced gasoline is stored as a liquid and is not bulky. For this reason, even if the amount of gasoline generated increases, the gasoline buffer tank 48 is unlikely to fill up in a short time. On the other hand, since hydrogen is stored in a gaseous state, it is bulky. For this reason, as the amount of hydrogen generated increases, the hydrogen buffer tank 64 tends to fill up relatively quickly. Therefore, in the present embodiment, when the supply amount of hydrogenated gasoline to the dehydrogenation catalyst 21 is increased, the hydrogen in the fuel supplied to the internal combustion engine 10 is consumed so as to consume more hydrogen than usual. The addition ratio of was increased. Thereby, it can suppress effectively that the hydrogen buffer tank 64 becomes full.

  Further, in the present embodiment, when the hydrogen addition ratio in the fuel supplied to the internal combustion engine 10 is increased, the internal combustion engine is configured so that the exhaust gas temperature is lowered in order to lower the temperature of the dehydrogenation catalyst 21 more quickly. The operating condition of the engine 10 was changed. More specifically, when the lean burn operation is performed, the air-fuel mixture is further leaned, and when the normal operation by the combustion of the stoichiometric or rich air-fuel mixture is performed, the ignition timing is advanced. Hereinafter, this point will be described in detail separately for the lean burn operation and the normal operation.

  In lean burn operation, the exhaust gas temperature decreases as the air-fuel mixture becomes leaner. Therefore, since the exhaust gas temperature is lowered by making the air-fuel mixture further lean in the lean burn operation, the temperature of the dehydrogenation catalyst 21 can be lowered more rapidly. In this case, the reason why the air-fuel mixture can be made leaner is that the addition ratio of hydrogen having a combustion promoting effect is increased, so that even a lean air-fuel mixture is better than the normal hydrogen addition ratio. It is because it can be made to burn.

  In normal operation, generally, when the ignition timing is advanced, it approaches MBT (Minimum advance for the Best Torque). When the ignition timing is brought close to MBT, the work amount of burned gas increases, that is, exhaust loss decreases, so that the exhaust temperature decreases. Accordingly, the exhaust gas temperature is lowered by advancing the ignition timing in the normal operation, so that the temperature of the dehydrogenation catalyst 21 can be lowered more rapidly. In this case, the reason why the ignition timing can be advanced is that, by increasing the hydrogen addition ratio that has a knock prevention effect, the ignition timing can be increased compared to when no hydrogen is added or when the hydrogen addition ratio is small. This is because knocking does not easily occur even at an early stage.

  In the present embodiment, when the temperature of the dehydrogenation catalyst 21 is excessively high for some reason, the supply of hydrogenated gasoline to the dehydrogenation catalyst 21 is prohibited in order to prevent the occurrence of coking. I did it. Further, when the supply of hydrogenated gasoline to the dehydrogenation catalyst 21 is prohibited, the production of hydrogen stops, so that only the gasoline is supplied to the internal combustion engine 10 and the stoichiometric combustion is performed in order to preserve the stored hydrogen. It was decided to.

[Specific Processing in Embodiment 1]
FIG. 2 is a flowchart of a routine executed by the ECU 80 in the present embodiment in order to realize the above function. In the routine shown in FIG. 2, it is first determined whether or not the temperature of the dehydrogenation catalyst 21 exceeds the first determination value (step 100). The first determination value is a temperature for determining whether or not it is necessary to start decreasing the temperature of the dehydrogenation catalyst 21. More specifically, if the temperature of the dehydrogenation catalyst 21 is equal to or lower than the first determination value, there is no possibility that the dehydrogenation catalyst 21 will deteriorate such as sintering and coking, and If the temperature of the dehydrogenation catalyst 21 continues to rise beyond the first determination value, the dehydrogenation catalyst 21 may be deteriorated. In the present embodiment, the first determination value is specifically 500 ° C.

  If it is determined in step 100 that the temperature of the dehydrogenation catalyst 21 is 500 ° C. or less, it can be determined that it is not necessary to lower the temperature of the dehydrogenation catalyst 21 yet. Therefore, in this case, a normal amount of hydrogenated gasoline is supplied to the dehydrogenation catalyst 21 (step 102). The supply amount of hydrogenated gasoline in this case is calculated by the ECU 80 according to a predetermined rule based on the supply amount of hydrogen and gasoline to the internal combustion engine 10 and the like.

  When the normal amount of hydrogenated gasoline is supplied to the dehydrogenation catalyst 21 in step 102, the ECU 80 determines whether or not a lean burn condition that allows lean burn operation is satisfied. Determination of the lean burn condition can be made by a known method based on the accelerator opening, the engine speed, and the like. When the lean burn condition is confirmed, the amount of hydrogen and gasoline calculated according to a predetermined rule are supplied to the internal combustion engine 10. Thereby, lean burn operation is performed. Further, when the lean burn condition is not established, hydrogen and gasoline or only gasoline is supplied to the internal combustion engine 10 so that a stoichiometric or rich air-fuel mixture is formed. As a result, normal operation is performed by combustion of stoichiometric or rich air-fuel mixture.

  On the other hand, if it is found in step 100 that the temperature of the dehydrogenation catalyst 21 exceeds 500 ° C., the temperature of the dehydrogenation catalyst 21 starts to be lowered in order to avoid the deterioration of the dehydrogenation catalyst 21. It can be judged that it is necessary. However, if for some reason the temperature of the dehydrogenation catalyst 21 is high enough to cause coking when hydrogenated gasoline is supplied, it is necessary to avoid supplying hydrogenated gasoline. Therefore, when it is recognized that the temperature of the dehydrogenation catalyst 21 exceeds 500 ° C., it is next determined whether or not the temperature of the dehydrogenation catalyst 21 exceeds the second determination value ( Step 104). The second determination value is a value larger than the first determination value, and is a temperature at which the supply of hydrogenated gasoline must be avoided in order to prevent the dehydrogenation catalyst 21 from deteriorating. More specifically, the second determination value is set to a temperature at which deterioration such as coking may occur when hydrogenated gasoline is supplied to the dehydrogenation catalyst 21. In the present embodiment, the second determination value is specifically 650 ° C.

  When it is determined in step 104 that the temperature of the dehydrogenation catalyst 21 exceeds 650 ° C., supply of hydrogenated gasoline to the dehydrogenation catalyst 21 is prohibited (step 106). Thereby, even if the temperature of the dehydrogenation catalyst 21 exceeds 650 ° C. for some reason, the occurrence of coking can be avoided.

  In this way, when the supply of hydrogenated gasoline to the dehydrogenation catalyst 21 is prohibited, only the amount of gasoline that forms a stoichiometric mixture is supplied to the internal combustion engine 10. That is, an operation by stoichiometric combustion using only gasoline is performed (step 108). That is, the supply of hydrogen to the internal combustion engine 10 is prohibited. As a result, under the situation where the production of hydrogen and gasoline is stopped due to the prohibition of the supply of hydrogenated gasoline to the dehydrogenation catalyst 21, there is no more hydrogen stored in a smaller amount than gasoline. Can be prevented.

  When it is recognized in step 104 that the temperature of the dehydrogenation catalyst 21 is 650 ° C. or less, the temperature of the dehydrogenation catalyst 21 is greater than 500 ° C. and 650 ° C. or less. In this case, it is necessary to start to lower the temperature of the dehydrogenation catalyst 21, and it can be determined that there is no risk of deterioration such as coking even if hydrogenated gasoline is supplied to the dehydrogenation catalyst 21. Therefore, in order to cool the dehydrogenation catalyst 21, the supply amount of hydrogenated gasoline to the dehydrogenation catalyst 21 is increased (step 110). That is, a larger amount of hydrogenated gasoline than that supplied in the processing of step 102 is supplied to the dehydrogenation catalyst 21. Thereby, in the dehydrogenation catalyst 21, the dehydrogenation reaction of hydrogenated gasoline which is an endothermic reaction is performed in a larger amount, so the temperature of the dehydrogenation catalyst 21 is lowered.

  Following the processing of step 110, it is determined whether a lean burn condition is satisfied (step 112). The success or failure of the lean burn condition can be determined by a known method based on the accelerator opening, the engine speed, etc., as described in the processing of step 102 above.

  If the lean burn condition is confirmed in step 112, the lean burn operation is executed (step 114). Here, the lean burn operation is performed at the following two points as compared with the lean burn operation when the processing of step 102 is performed, that is, when the supply amount of hydrogenated gasoline to the dehydrogenation catalyst 21 is not increased. The conditions are different. The first point is that the hydrogen addition ratio in the fuel supplied to the internal combustion engine 10 is increased as compared with the case where the supply amount of hydrogenated gasoline is not increased. As a result, the amount of hydrogen consumed increases, so that the hydrogen buffer tank 64 can be effectively prevented from becoming full even in a situation where the amount of hydrogen produced increases due to an increase in the amount of hydrogenated gasoline supplied. Can do. The second point is that the hydrogen injection amount, gasoline injection amount, intake air amount, etc. are set so that the air-fuel mixture becomes leaner than when the supply amount of hydrogenated gasoline is not increased. Since the limit of lean combustion is widened by increasing the amount of highly combustible hydrogen, combustion with a leaner air-fuel mixture is possible as described above. By making the air-fuel mixture leaner in this way, the exhaust temperature decreases. For this reason, the temperature of the dehydrogenation catalyst 21 can be lowered more rapidly.

  On the other hand, if the lean burn condition is not established in step 112, it can be determined that the lean burn operation cannot be performed, so that the normal operation by the combustion of the stoichiometric or rich air-fuel mixture is executed (step 116). ). The normal operation here has the following two operating conditions when compared with the normal operation when the processing of step 102 is performed, that is, when the supply amount of hydrogenated gasoline to the dehydrogenation catalyst 21 is not increased. It will be different. The first point is that the hydrogen addition ratio in the fuel supplied to the internal combustion engine 10 is increased as compared with the case where the supply amount of hydrogenated gasoline is not increased. As a result, the amount of hydrogen consumed increases, so that the hydrogen buffer tank 64 can be effectively prevented from becoming full even in a situation where the amount of hydrogen produced increases due to an increase in the amount of hydrogenated gasoline supplied. Can do. The second point is that the ignition timing is advanced (advanced) than when the supply amount of hydrogenated gasoline is not increased. Such an advance of the ignition timing becomes possible by increasing the amount of hydrogen added, which has a high knock prevention effect. When the ignition timing is advanced, it approaches MBT, and as a result, exhaust loss decreases, resulting in a decrease in exhaust temperature. For this reason, the temperature of the dehydrogenation catalyst 21 can be lowered more rapidly.

  When the catalyst temperature decrease control including the processing of steps 110 to 116 is started, the ECU 80 monitors the establishment of the catalyst temperature decrease control end condition (step 118). Then, the processing of steps 110 to 116 is repeatedly performed until this end condition is satisfied. As conditions for terminating the catalyst temperature drop control, for example, conditions such that the temperature of the dehydrogenation catalyst 21 has dropped to a predetermined temperature (for example, 400 ° C.), or that a predetermined time has elapsed since the start of the catalyst temperature drop control, etc. Can be set.

  By the way, in the first embodiment described above, when the supply amount of hydrogenated gasoline to the dehydrogenation catalyst 21 is increased, the addition ratio of hydrogen in the fuel supplied to the internal combustion engine 10 is increased. When there is a sufficient storage space for hydrogen, it is not necessary to increase the consumption of hydrogen, so the hydrogen addition ratio may be kept the same as usual.

  In the first embodiment described above, the temperature sensor 23 corresponds to the “temperature detection means” in the first invention. Further, the “increase means” in the first aspect of the present invention is realized by the ECU 80 executing the processing of steps 100 and 110 described above.

  In the first embodiment described above, the hydrogen injector 18 and the gasoline injector 20 correspond to the “supply means” in the second aspect of the present invention. Further, the “hydrogen ratio increasing means” according to the second aspect of the present invention is implemented by the ECU 80 executing the processing of step 114 or 116 described above.

  Further, in the first embodiment described above, the ECU 80 executes the lean burn operation when the lean burn condition is satisfied, whereby the “lean burn operation means” in the third aspect of the invention executes the processing of step 114 above. As a result, the “means for making the air-fuel mixture leaner” in the third aspect of the invention is realized.

  Further, in the first embodiment described above, the ECU 80 performs the normal operation by the combustion of stoichiometric or rich air-fuel mixture when the lean burn condition is not established, whereby the “normal operation means” in the fourth invention is By executing the processing of step 116, the “ignition timing advance means” in the fourth aspect of the present invention is realized.

  In the first embodiment described above, the ECU 80 executes the processing of steps 104 and 106 so that the “prohibiting means” in the fifth and sixth inventions executes the processing of step 108. Thus, the “hydrogen supply prohibiting means” according to the sixth aspect of the present invention is realized.

It is a figure for demonstrating the system configuration | structure of Embodiment 1 of this invention. It is a flowchart of the routine performed in Embodiment 1 of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Internal combustion engine 12 Intake passage 13 Spark plug 14 Exhaust passage 15 Air flow meter 16 Throttle valve 18 Hydrogen injector 20 Gasoline injector 21 Dehydrogenation catalyst 22 Dehydrogenation reactor 23 Temperature sensor 24 Hydrogenated gasoline injector 32 Hydrogenated gasoline tank 36 Pump 40 Separation Device 48 Gasoline buffer tank 62 Pump 64 Hydrogen buffer tank 66 Pump 73 Regulator 80 ECU

Claims (6)

A dehydrogenation catalyst which is provided to be heated by the heat of exhaust gas of an internal combustion engine and separates hydrogenated fuel containing organic hydride into hydrogen and dehydrogenated fuel;
Temperature detecting means for detecting the temperature of the dehydrogenation catalyst;
When the temperature of the dehydrogenation catalyst exceeds the first determination value, the supply amount of the hydrogenated fuel to the dehydrogenation catalyst is made larger than when the temperature of the dehydrogenation catalyst is equal to or lower than the first determination value. An increasing means for increasing the amount;
An internal combustion engine using hydrogen. Supply means for supplying hydrogen and dehydrogenated fuel separated by the dehydrogenation catalyst to the internal combustion engine;
When the supply amount of hydrogenated fuel to the dehydrogenation catalyst is increased by the increasing means, the addition of hydrogen supplied to the internal combustion engine is greater than when the supply amount of hydrogenated fuel is not increased. Means for increasing the proportion of hydrogen to increase the proportion;
The hydrogen-utilized internal combustion engine according to claim 1, comprising: Lean-burn operation means for lean-burning the internal combustion engine when a lean-burn condition is established;
In the lean burn operation, when the addition ratio of hydrogen supplied to the internal combustion engine is increased by the hydrogen ratio increasing means, the air-fuel mixture is made leaner than when the addition ratio of hydrogen is not increased. Means to
The internal combustion engine using hydrogen according to claim 2, comprising: Normal operating means for normally operating the internal combustion engine with stoichiometric or rich air-fuel mixture when lean burn conditions are not established;
Ignition that advances the ignition timing when the hydrogen addition ratio supplied to the internal combustion engine is increased by the hydrogen ratio increasing means during the normal operation than when the hydrogen addition ratio is not increased. Timing advance means,
The hydrogen-utilizing internal combustion engine according to claim 2 or 3, characterized by comprising:   The apparatus according to claim 1, further comprising a prohibiting unit that prohibits supply of hydrogenated fuel to the dehydrogenation catalyst when a temperature of the dehydrogenation catalyst exceeds a second determination value that is greater than the first determination value. 5. The hydrogen-utilizing internal combustion engine according to any one of 1 to 4. Prohibiting means for prohibiting the supply of hydrogenated fuel to the dehydrogenation catalyst when the temperature of the dehydrogenation catalyst exceeds a second determination value greater than the first determination value;
Hydrogen supply prohibiting means for prohibiting supply of hydrogen to the internal combustion engine when supply of hydrogenated fuel to the dehydrogenation catalyst is prohibited by the prohibiting means;
5. The hydrogen-utilizing internal combustion engine according to claim 2, comprising:

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