JP2007291994A - Internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve reformation performance by a reforming catalyst in an internal combustion engine. <P>SOLUTION: In the internal combustion engine, a reforming device 26 having two reforming chambers 29, 30 is connected via an exhaust gas branch pipe 33 branching part of exhaust gas flowing in an exhaust pipe 25; a second injector 34 is attached to the exhaust gas branch pipe 33; a reformed gas introduction pipe 35 and a flow rate control valve 36 are provided for introducing reformed gas generated in the reforming device 26 to an intake pipe 15; and an opening/closing valve 42 is provided on the downstream side of the second reforming chamber 30. An ECU 37 stops generation of the reformed gas in the reforming chamber 30 by closing the opening/closing valve 42 when the bed temperature of the reforming chamber 30 detected by a bed temperature sensor 41 is lower than a preset activation temperature. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an internal combustion engine equipped with a fuel reformer, and in particular, supplies fuel to a part of the recirculation gas of exhaust gas and then reforms it with heat to generate reformed gas. The present invention relates to an internal combustion engine supplied to a passage.

Conventionally, a part of the exhaust gas of an internal combustion engine is taken out and supplied to the intake passage as a recirculation gas, and this recirculation gas is mixed with the intake air, thereby lowering the maximum temperature during combustion and reducing NOx in the exhaust gas. There is an exhaust gas recirculation (EGR) system. As a system improved from this EGR system, in recent years, a part of the fuel is added to the reflux gas, and the mixed gas in which the fuel is mixed with the exhaust gas is heated using the heat of the exhaust gas and the reforming catalyst is passed. Thus, an endothermic reforming reaction is performed on the mixed gas, a reformed gas containing hydrogen (H ₂ ) and carbon monoxide (CO) is generated from the mixed gas, and the reformer gas is supplied to the intake passage. Thus, an efficient exhaust heat recovery and fuel efficiency improvement has been proposed.

  An example of such an exhaust reformer system for an internal combustion engine is described in Patent Document 1 below. In the exhaust reformer system of the internal combustion engine described in Patent Document 1, a fuel injection valve is provided in the intake port, and another fuel injection valve, a fuel evaporator, a reforming catalyst, and a recirculation pipe branched from the exhaust pipe are provided. A reformer gas control valve is provided. Normally, the reformer gas control valve is closed and fuel is injected into the intake port to introduce the air-fuel mixture into the combustion chamber. The control valve is opened, fuel is injected into the reflux pipe, and reformer gas generated by the reforming catalyst is introduced into the combustion chamber and burned.

JP 2004-092520 A

  In the above-described conventional exhaust reformer system for an internal combustion engine, fuel is injected into the recirculation pipe, and the reformed gas is generated by the endothermic reforming reaction with the reformed catalyst using the mixed gas in which the fuel is mixed with the exhaust gas. The generated reformed gas is introduced into the combustion chamber.

  By the way, when the bed temperature of the reforming catalyst supported on the reformer becomes a predetermined active temperature (for example, 600 ° C.) or higher, the reforming reaction of the mixed gas is promoted to generate the reformed gas. it can. However, when the internal combustion engine is started or operated at a light load, the reforming catalyst cannot be sufficiently heated by the heat of the exhaust gas, and the reforming catalyst has not risen to a predetermined activation temperature, and the reforming reaction is not performed. As a result, the generation of the reformed gas becomes insufficient. In this case, in the reforming catalyst of the reformer, a temperature distribution is generated along the flow direction of the exhaust gas. In other words, the upstream reforming catalyst can receive sufficient heat supply from the exhaust gas. However, since the heat of the exhaust gas is taken away here, the temperature of the downstream reforming catalyst decreases and the exhaust gas is exhausted. From this, sufficient heat supply cannot be received, and the reformed gas is not generated and unburned gas is mixed. Then, a sufficient amount of reformed gas cannot be introduced into the combustion chamber, and efficient exhaust heat recovery and fuel efficiency improvement cannot be achieved.

In addition, when the internal combustion engine is started or operated at a light load, the reforming catalyst has not risen to a predetermined activation temperature, and reforming does not proceed sufficiently to hydrogen (H ₂ ) or carbon monoxide (CO). (C) is generated, and a problem referred to as coking that adheres to the reformer (reforming catalyst) occurs, resulting in a reduction in catalyst performance.

  An object of the present invention is to solve such a problem, and an object of the present invention is to provide an internal combustion engine that is improved in reforming performance by a reforming catalyst.

  In order to solve the above-described problems and achieve the object, an internal combustion engine of the present invention includes an intake passage for introducing outside air into a combustion chamber, and first fuel supply means for supplying fuel to the intake passage or the combustion chamber. The fuel is supplied to the exhaust passage for exhausting the exhaust gas discharged from the combustion chamber to the outside, the exhaust gas branch passage for part of the exhaust gas flowing through the exhaust passage, and the exhaust gas branch passage A second fuel supply means; and a reformer having a plurality of reforming chambers for generating the reformed gas by flowing in the exhaust gas flowing through the exhaust gas diversion passage to which fuel is supplied from the second fuel supply means. A reformed gas introduction passage for introducing the reformed gas generated in the reformer into the intake passage, a bed temperature detecting means for detecting a bed temperature of the plurality of reforming chambers, and the plurality of reforming chambers Reforming adjusting means for adjusting the generation operation of the reformed gas in the gas, and the bed temperature And a reforming control means for reducing a reforming gas generation operation by the reforming adjustment means for a reforming chamber whose bed temperature detected by the outlet means is lower than a preset active temperature. Is.

  In the internal combustion engine of the present invention, the plurality of reforming chambers are arranged in series in the exhaust passage along the flow direction of the exhaust gas, and a downstream branch branch passage in the exhaust gas branch passage is the plurality of reformers. An upstream branching passage in the reformed gas introduction passage is connected to the plurality of reforming chambers, and an on-off valve serving as the reforming adjusting means is the diversion branch passage or the introduction branch passage. It is characterized by being provided.

  In the internal combustion engine of the present invention, the plurality of reforming chambers are arranged in series in the exhaust passage along the flow direction of the exhaust gas, and a downstream branch branch passage in the exhaust gas branch passage is the plurality of reformers. And an upstream introduction branch passage in the reformed gas introduction passage is connected to the plurality of reforming chambers, and the second fuel supply means as the reforming adjustment means is connected to the branch flow branch passage. It is characterized by being provided.

  In the internal combustion engine of the present invention, the plurality of reforming chambers are arranged in series along the flow direction of the exhaust gas in the exhaust passage, and the downstream side of the exhaust gas branch passage is connected to the first reforming chamber, The first reforming chamber is connected to the second reforming chamber via a connecting passage, and the upstream side of the reformed gas introduction passage is connected to the second reforming chamber, and serves as the reforming adjusting means. The second fuel supply means is provided in the connection passage.

  In the internal combustion engine of the present invention, the reforming control means reduces the fuel supply amount by the second fuel supply means in accordance with the reformed gas generation operation state in the plurality of reforming chambers by the reforming adjustment means. It is characterized by doing.

  In the internal combustion engine of the present invention, a flow rate adjusting valve is provided in the reformed gas introduction passage, and the reforming control means is in an operation state of generating reformed gas in the plurality of reforming chambers by the reforming adjusting means. Accordingly, the fuel supply amount by the second fuel supply means is decreased, and the opening degree of the flow rate adjusting valve is decreased.

  According to the internal combustion engine of the present invention, the second fuel supply means for supplying fuel to the exhaust gas diversion passage for diverting a part of the exhaust gas flowing through the exhaust passage, and the exhaust gas supplied with the fuel are flowed in and modified. A reformer having a plurality of reforming chambers for generating a quality gas, a reforming gas introduction passage for introducing the reformed gas generated by the reformer into the intake passage, and a plurality of reforming chamber floors A bed temperature detecting means for detecting the temperature, a reforming adjusting means for adjusting the generation operation of the reformed gas in the reforming chamber, and a reforming chamber in which the bed temperature detected by the bed temperature detecting means is lower than a preset active temperature. Since the reforming control means for reducing the generation operation of the reformed gas by the reforming adjustment means is provided, the generation operation of the reformed gas in the reforming chamber in which the bed temperature does not reach the activation temperature is reduced. Prevents unburned gas from being mixed into the reformed gas and ensures proper reforming gas in the combustion chamber. It is possible to introduce, it is possible to suppress the occurrence of coking, a result, it is possible to improve the reforming performance by reformer.

  Embodiments of an internal combustion engine according to the present invention will be described below in detail with reference to the drawings. In addition, this invention is not limited by this Example.

  FIG. 1 is a schematic configuration diagram showing an internal combustion engine according to the first embodiment of the present invention, and FIG. 2 is a flowchart showing control of the reformer in the internal combustion engine of the first embodiment.

  In the internal combustion engine of the first embodiment, as shown in FIG. 1, the engine 11 as the internal combustion engine is a port injection type four-cylinder type, and although not shown, a cylinder head is fastened on a cylinder block. Pistons are fitted in a plurality of cylinder bores so as to be movable up and down. A crankcase is fastened to the lower part of the cylinder block, a crankshaft is rotatably supported in the crankcase, and each piston is connected to the crankshaft via a connecting rod.

  Combustion chambers 12 are formed by cylinder blocks, cylinder heads, and pistons corresponding to four cylinders, and each combustion chamber 12 is formed with an intake port 13 and an exhaust port 14 facing each other at the top. The intake port 13 and the exhaust port 14 can be opened and closed by an intake valve and an exhaust valve (not shown).

  The downstream end of the intake pipe (intake passage) 15 is connected to each intake port 13 via an intake manifold 16, and an air cleaner 17 is attached to the upstream end of the intake pipe 15. An electronic throttle device 19 having a throttle valve 18 is provided on the downstream side of the air cleaner 17. Further, the intake manifold 16 is provided with a first injector (first fuel supply means) 20 capable of supplying fuel to the intake port 13 corresponding to each combustion chamber 12. The first injector 20 is connected to a fuel pump 23 in a fuel tank 22 by a fuel supply pipe 21. Although not shown, each combustion chamber 12 is equipped with a spark plug that ignites the air-fuel mixture. Similar to the first injector 20, the second injector 30 is connected to a fuel pump 23 in the fuel tank 22 by a fuel supply pipe 21.

  On the other hand, an exhaust pipe (exhaust passage) 25 is connected to each exhaust port 14 via an exhaust manifold 24, and a reformer 26 and a three-way catalyst 27 are attached to the exhaust pipe 25. As will be described later, the reformer 26 supplies fuel to a part of the exhaust gas, and then reforms the mixed gas with exhaust heat to generate a reformed gas. The three-way catalyst 27 can simultaneously purify harmful substances such as hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NOx) contained in the exhaust gas. When exhaust gas is in the vicinity of the stoichiometric air-fuel ratio (stoichiometric), harmful substances in the exhaust gas can be purified.

  Here, the reformer 26 will be described in detail. The reformer 26 is arranged with a cylinder 28 connected to the exhaust pipe 25 and a plurality of chambers communicating with each other in the cylinder 28, and a reforming catalyst (for example, Co, Ni, Rh) is disposed inside. The first reforming chamber 29 and the second reforming chamber 30 are supported, and the gas insertion passages 31 and 32 formed through the reforming chambers 29 and 30 in the cylindrical body 28. . In this case, the first reforming chamber 29 and the second reforming chamber 30 are arranged in series in the cylinder 28 along the flow direction of the exhaust gas, and the gas insertion passages 31 and 32 are similarly connected in series. is doing.

  An exhaust gas branch pipe (exhaust gas branch passage) 33 is branched from the upstream side of the reformer 26 in the exhaust pipe 25, and the downstream end of the exhaust gas branch pipe 33 has two branch branches. The pipes (branch branch passages) 33 a and 33 b are branched, and the branch branch pipes 33 a and 33 b are connected to one end portions of the first and second reforming chambers 29 and 30 in the reformer 26. The exhaust gas branch pipe 33 is located upstream of the branch portions of the branch pipes 33a and 33b, and a part of the exhaust gas branched from the exhaust pipe 25 to the exhaust gas branch pipe 33. A second injector (second fuel supply means) 34 for injecting fuel is provided.

  Further, a reformed gas introduction pipe (reformed gas introduction passage) 35 for introducing the reformed gas generated by the reformer 26 into the intake pipe 15 is provided, and one end portion of the reformed gas introduction pipe 35 is provided. Is branched into two introduction branch pipes (introduction branch passages) 35a, 35b, and each introduction branch pipe 35a, 35b is connected to the other end of the first and second reforming chambers 29, 30 in the reformer 26. Yes. The other end of the reformed gas introduction pipe 35 is connected to the downstream side of the electronic throttle device 19 in the intake pipe 15. A flow rate adjusting valve 36 for controlling the amount of reformed gas introduced into the intake pipe 15 is attached to the reformed gas introduction pipe 35. Further, the upstream side and the downstream side of the reformer 26 in the exhaust pipe 25 are communicated with each other by gas insertion passages 31 and 32.

  In the engine 11 of this embodiment, fuel is injected into the intake air flowing through the intake port 13 by the first injector 20, and fuel is injected into the exhaust gas flowing through the exhaust gas branch pipe 28 by the second injector 34. The fuel injection by the first injector 20 is referred to as intake fuel injection, and the fuel injection from the second injector 34 is referred to as exhaust fuel injection.

  Therefore, in a state where the flow rate adjustment valve 36 is opened, a part of the exhaust gas flowing through the exhaust pipe 25 is diverted to the exhaust gas distribution pipe 33, and the second injector 34 performs fuel injection (exhaust fuel) to the exhaust gas. Injection). The mixed gas in which the fuel and the exhaust gas are mixed flows into the reforming chambers 29 and 30 of the reformer 26 and is heated by the heat of the exhaust gas flowing from the exhaust pipe 25 through the gas insertion passages 31 and 32 of the reformer 26. Is done. Then, the mixed gas is vaporized by promoting evaporation, and the vaporized mixed gas undergoes an endothermic reaction to be reformed to generate a reformed gas containing hydrogen, carbon monoxide and the like.

For example, when the exhaust gas is “7.6 CO ₂ + 6.8H ₂ O + 40.8N ₂ ” and the gasoline fuel is “C _7.6 H _13.6 ”, the endothermic reaction is
1.56 (7.6 CO ₂ +6.8 H ₂ O + 40.8 N ₂ ) +3 (C _7.6 H _13.6 ) +984.8 kcal → 31 H ₂ +34.7 CO + 63.6 N ₂
It is represented by That is, according to the endothermic reaction at this time, 31 mol of hydrogen gas and 34.7 mol of carbon monoxide gas are generated from 3 mol of gasoline fuel.

  The reformed gas generated in the reformer 26 flows from the reforming chambers 29 and 30 to the reformed gas introduction pipe 35, the supply amount thereof is adjusted by the opening degree of the flow rate adjusting valve 36, and flows through the intake pipe 15. Supplied to intake air. Then, an air-fuel mixture obtained by mixing the intake air and the reformed gas is introduced from the intake manifold 16 through the intake port 13 into the combustion chamber 12 and ignited by the spark plug to explode. When the exhaust valve is opened, the exhaust gas is exhausted. The gas is discharged from the port 14 to the exhaust pipe 25. In this case, since the reformed gas contains hydrogen, combustion efficiency in the combustion chamber 12 is good, fuel efficiency can be improved, and generation of NOx can be suppressed and exhaust purification efficiency can be improved.

  An electronic control unit (ECU) 37 is mounted on the vehicle, and the ECU 37 controls the drive of the first injector 20, the second injector 34, the spark plug, and the like, so that the fuel injection amount, the injection timing, the ignition timing, etc. Can be controlled. That is, an air flow sensor 38 is mounted on the upstream side of the intake pipe 15, and the measured intake air amount is output to the ECU 37. The electronic throttle device 19 has a throttle position sensor and outputs the current throttle opening to the ECU 37. Further, the crank angle sensor 39 outputs the detected crank angle of each cylinder to the ECU 37, and the ECU 37 discriminates each stroke of intake, compression, expansion (explosion), and exhaust in each cylinder based on the detected crank angle. At the same time, the engine speed is calculated.

  Accordingly, the ECU 37 determines the overall fuel injection amount, injection timing, ignition timing, and the like based on the detected intake air amount, throttle opening (or accelerator opening), engine operating state such as engine speed. Yes. In this case, the total fuel injection amount is the sum of the fuel injection amounts injected by the first injector 20 and the second injector 34.

  In addition, the ECU 37 can control the amount of reformed gas introduced into the intake pipe 15 by drivingly controlling the second injector 34, the flow rate adjusting valve 36, and the like. That is, the reforming chambers 29 and 30 in the reformer 26 are respectively provided with bed temperature sensors (bed temperature detecting means) 40 and 41, and the current temperature of each reforming chamber 29 and 30 (bed temperature). ) Is output to the ECU 37.

  Therefore, the ECU 37 determines whether or not the reformer 26 is at the activation temperature based on the detected bed temperatures of the reforming chambers 29 and 30 in the reformer 26. Further, the ECU 37 calculates the upper limit value of the amount of exhaust gas that can be recirculated to the intake pipe 15 based on the engine speed and the engine load (for example, throttle opening). When the ECU 37 determines that the temperature of the reformer 26 is equal to or higher than the activation temperature, the ECU 37 calculates the amount of reformed gas that can be introduced into the intake pipe 15 based on the amount of exhaust gas that can be recirculated to the intake pipe 15. The opening degree of the flow rate adjusting valve 36 is set, and the exhaust fuel injection amount by the second injector 34 is set. In this case, the first injector 20 is injected by subtracting the exhaust fuel injection amount by the second injector 34 set here from the total fuel injection amount calculated based on the intake air amount, the engine speed, and the like. The intake fuel injection amount to be set is set.

By the way, as described above, the reforming catalyst carried in the reforming chambers 29 and 30 of the reformer 26 has exhaust gas and fuel when the bed temperature becomes equal to or higher than a predetermined activation temperature (for example, 600 ° C.). A good reformed gas can be generated by promoting the reforming reaction of the mixed gas. However, when the internal combustion engine is started or operated at a light load, it becomes difficult to sufficiently heat the reforming catalyst by the heat of the exhaust gas, and the generation of the reformed gas becomes insufficient. In this case, the upstream reforming catalyst can receive sufficient heat supply from the exhaust gas. However, since the heat of the exhaust gas is deprived here, the temperature of the downstream reforming catalyst decreases and the exhaust gas is exhausted. A sufficient heat supply cannot be received from the gas, and a temperature distribution along the flow direction of the exhaust gas occurs. Then, not only a sufficient amount of reformed gas cannot be introduced into the combustion chamber 12, but reforming does not proceed sufficiently to hydrogen (H ₂ ) and carbon monoxide (CO), and carbon (C) is generated. A problem referred to as coking that adheres to the reformer (reforming catalyst) arises, and the catalyst performance deteriorates.

  Therefore, in this embodiment, as a reforming adjusting means for adjusting the reforming gas generating operation in the reforming chambers 29 and 30 of the reformer 26, the open / close valve 42 is provided in the introduction branch pipe 35b of the reformed gas introduction pipe 35. Is provided. Then, the ECU 37 as the reforming control means adjusts the operation of generating the reformed gas for the reforming chambers 29 and 30 in which the catalyst bed temperatures detected by the bed temperature sensors 40 and 41 are lower than the preset activation temperature. That is, when the bed temperature of the reforming chamber 30 detected by the bed temperature sensor 41 is lower than the activation temperature, the on / off valve 42 is closed to prevent introduction of exhaust gas containing fuel into the reforming chamber 30, The generation operation of the reformed gas in the reforming chamber 30 is stopped. Therefore, by stopping the generation of the reformed gas in the reforming chamber 30 that has not reached the activation temperature, the introduction of the reformed gas containing unburned gas into the combustion chamber 12 is stopped, and the occurrence of coking is prevented. The catalyst performance is improved.

  Here, the fuel reforming control in the internal combustion engine of the first embodiment will be described in detail based on the flowchart of FIG.

  In the fuel reforming control in the internal combustion engine of the present embodiment, as shown in FIG. 2, in step S11, the ECU 37 sets a predetermined fuel reforming in which the upstream reforming chamber 29 in the reformer 26 is preset. Determine if quality start conditions are met. Specifically, the bed temperature of the reforming chamber 29 on the upstream side in the reformer 26, that is, the catalyst bed temperature detected by the bed temperature sensor 40 reaches a predetermined activation temperature (for example, 600 ° C.) set in advance. Determine whether or not.

  If the ECU 37 determines in step S11 that the catalyst bed temperature in the upstream reforming chamber 29 in the reformer 26 has not reached the predetermined activation temperature, the routine exits without doing anything. That is, since the catalyst bed temperature of the upstream reforming chamber 29 has not reached the activation temperature, it is determined that fuel reforming cannot be performed in the reformer 26, and fuel reforming is stopped. In this case, the ECU 37 sets the total fuel injection amount calculated from the engine speed, the intake air amount, and the like as the intake fuel injection amount injected by the first injector 20, and the exhaust fuel injection amount injected by the second injector 34. Is set to 0. Therefore, a part of the exhaust gas discharged to the exhaust pipe 25 of the engine 11 is diverted to the exhaust gas branch pipe 33 and passes through the reforming chambers 29 and 30 of the reformer 26, and then the reformed gas introduction pipe 35. The supply amount is adjusted by the opening degree of the flow rate adjustment valve 36 and supplied to the intake air flowing through the intake pipe 15 as EGR gas. Then, the air-fuel mixture obtained by mixing the intake air and the EGR gas is introduced from the intake manifold 16 through the intake port 13 into the combustion chamber 12, and is ignited by the spark plug to explode and enable good combustion. When the exhaust valve is opened, the exhaust gas is discharged from the exhaust port 14 to the exhaust pipe 25.

  In this case, when the catalyst bed temperatures of the reforming chambers 29 and 30 in the reformer 26 do not reach the predetermined activation temperature, the fuel is not injected into the exhaust gas flowing through the exhaust gas branch pipe 33, so the intake pipe 15 The unburned gas can be prevented from flowing into the exhaust gas, and the exhaust gas is recirculated to the intake pipe 15 as EGR gas, so that carbon dioxide contained in the EGR gas is returned to the combustion chamber 12 and recombusted. Thus, the combustion temperature can be lowered to suppress the generation of NOx.

  On the other hand, if it is determined in step S11 that the catalyst bed temperature of the upstream reforming chamber 29 in the reformer 26 has reached a predetermined activation temperature, the process proceeds to step S12. In step S12, the ECU 37 determines whether or not the downstream reforming chamber 30 in the reformer 26 satisfies a predetermined fuel reform start condition set in advance. Specifically, the bed temperature of the reforming chamber 30 on the downstream side in the reformer 26, that is, the catalyst bed temperature detected by the bed temperature sensor 41 reaches a predetermined activation temperature (for example, 600 ° C.) set in advance. Determine whether or not.

  If the ECU 37 determines in step S12 that the catalyst bed temperature of the reforming chamber 30 on the downstream side in the reformer 26 has not reached the predetermined activation temperature, the process proceeds to step S13. In step S13, the on-off valve 42 is closed, and the introduction branch pipe 35b of the reformed gas introduction pipe 35 is closed. Subsequently, in step S14, the second injector 34 injects an amount of fuel corresponding to the reformed gas that can be reformed in the upstream reforming chamber 29. On the other hand, when the ECU 37 determines in step S12 that the catalyst bed temperature of the reforming chamber 30 on the downstream side in the reformer 26 has reached a predetermined activation temperature, the process proceeds to step S15. In step S15, the on-off valve 42 is opened, and the introduction branch pipe 35b of the reformed gas introduction pipe 35 is opened. Subsequently, in step S16, the second injector 34 injects an amount of fuel corresponding to the reformed gas that can be reformed in the upstream reforming chamber 29 and the downstream reforming chamber 30.

  That is, the ECU 37 calculates the total fuel injection amount from the engine speed, the intake air amount, and the like, while determining the maximum exhaust gas amount that can be recirculated to the intake pipe 15 from the engine speed, the throttle opening (engine load), and the like. The amount of reformed gas that can be introduced into the intake pipe 15 is calculated from the maximum exhaust gas amount and the catalyst bed temperature of the reformer 26, and the opening degree of the flow rate adjusting valve 36 is set. Then, the exhaust fuel injection amount that the second injector 34 injects is set based on the catalyst bed temperature of the reformer 26 and the reformed gas amount introduced into the intake pipe 15 through the reformed gas introduction pipe 35. Further, the intake fuel injection amount injected by the first injector 20 is set by subtracting the exhaust fuel injection amount by the second injector 34 from the total fuel injection amount.

  At this time, if the catalyst bed temperatures of the upper and lower reforming chambers 29 and 30 are equal to or higher than the activation temperature, the on-off valve 42 is opened, so that the calculated maximum exhaust gas amount can be introduced into the intake pipe 15. The amount of quality gas becomes maximum, the opening degree of the flow rate adjustment valve 36 is set for this reformed gas amount, and the exhaust fuel injection amount is set based on the reformed gas amount adjusted by the flow rate adjusting valve 36.

  Therefore, the exhaust gas discharged to the exhaust pipe 25 of the engine 11 flows through the gas insertion passages 31 and 32 of the reformer 26 and flows into the three-way catalyst 27, and a part of the exhaust gas is exhaust gas distribution pipe. A predetermined amount of fuel is injected from the second injector 34 to the exhaust gas, and a mixed gas of the fuel and the exhaust gas passes through the branch branch pipes 33a and 33b to each reforming chamber 29 of the reformer 26. , 30. Then, the mixed gas flowing into the reforming chambers 29 and 30 is heated by the heat of the exhaust gas flowing through the gas insertion passages 31 and 32, undergoes an endothermic reaction, is reformed, and reforms containing hydrogen, carbon monoxide, and the like. A quality gas is produced. At this time, since the exhaust fuel injection amount is appropriately adjusted according to the reforming chambers 29 and 30 that can be reformed, when the upper and lower reforming chambers 29 and 30 can be reformed, the maximum amount is good. The reformed gas is generated.

  Then, the reformed gas generated in each of the reforming chambers 29 and 30 flows into the reformed gas introduction pipe 35, the supply amount thereof is adjusted by the opening degree of the flow rate adjusting valve 36, and the intake gas flowing through the intake pipe 15 Supplied against. Then, the air-fuel mixture in which the intake air and the reformed gas are mixed is introduced from the intake manifold 16 through the intake port 13 into the combustion chamber 12, and is ignited by the spark plug to explode and enable good combustion. When the exhaust valve is opened, the exhaust gas is discharged from the exhaust port 14 to the exhaust pipe 25. In this case, since the reformed gas contains hydrogen and carbon monoxide, combustion efficiency in the combustion chamber 12 is good, a large amount of exhaust gas can be recirculated, and fuel efficiency can be improved. Further, since the amount of exhaust gas (EGR gas amount) that can be recirculated by the reformed gas increases, carbon dioxide contained in the exhaust gas can be returned to the combustion chamber 12 for recombustion and the combustion temperature is lowered. By doing so, the generation of NOx can be suppressed, and the exhaust purification efficiency can be improved.

  On the other hand, when the catalyst bed temperature in the reforming chamber 30 on the downstream side is not at the activation temperature and only the catalyst bed temperature in the reforming chamber 29 on the upstream side is equal to or higher than the activation temperature, the on-off valve 42 is closed. The amount of reformed gas that can be introduced into the intake pipe 15 is reduced with respect to the maximum exhaust gas amount, and the opening degree of the flow rate adjusting valve 36 is set and adjusted by the flow rate adjusting valve 36 for this reformed gas amount. An exhaust fuel injection amount is set based on the reformed gas amount. That is, the exhaust fuel injection amount is almost halved.

  Therefore, the exhaust gas discharged to the exhaust pipe 25 of the engine 11 flows through the gas insertion passages 31 and 32 of the reformer 26 and flows into the three-way catalyst 27, and a part of the exhaust gas is exhaust gas distribution pipe. A predetermined amount of fuel is injected from the second injector 34 to the exhaust gas. However, since the introduction branch pipe 35b is closed by the on-off valve 42, the mixed gas of fuel and exhaust gas flows only into the reforming chamber 29 of the reformer 26 through the branch branch pipe 33a. Then, the mixed gas flowing into the reforming chamber 29 is heated by the heat of the exhaust gas flowing through the gas insertion passage 31, undergoes an endothermic reaction, is reformed, and a reformed gas containing hydrogen, carbon monoxide, and the like is generated. The

  At this time, since the exhaust fuel injection amount is appropriately adjusted according to the reforming chambers 29 and 30 that can be reformed, when only the reforming chamber 29 on the upstream side can be reformed, it is good quality and minimum The reformed gas is generated. In the reformer 30 that has not reached the activation temperature, since the introduction branch pipe 35b is closed by the on-off valve 42, the reformed gas introduced into the intake pipe 15 by the reformed gas introduction pipe 35 is reformed. Unburned gas in the reactor 30 is not mixed, and coking of the reformer 26 is prevented.

  Then, the catalyst bed temperature of the reforming chamber 30 on the downstream side in the reformer 26 rises, and in step S12, the ECU 37 determines that the catalyst bed temperature of the reforming chamber 30 on the downstream side in the reformer 26 has a predetermined activity. If it is determined that the temperature has been reached, the process proceeds to step S15, where the open / close valve 42 opens the introduction branch pipe 35b of the reformed gas introduction pipe 35, and then, in step S16, the second injector 34 causes the upstream side modification. An amount of fuel corresponding to the reformed gas that can be reformed in the quality chamber 29 and the downstream reforming chamber 30 is injected.

  As described above, in the internal combustion engine of the first embodiment, the reformer 26 having the two reforming chambers 29 and 30 is provided via the exhaust gas branch pipe 33 that splits a part of the exhaust gas flowing through the exhaust pipe 25. At the same time, a second injector 34 is attached to the exhaust gas branch pipe 33, and a reformed gas introduction pipe 35 and a flow rate adjusting valve 36 for introducing the reformed gas generated by the reformer 26 into the intake pipe 15 are provided. In addition, an on-off valve 42 is provided on the downstream side of the second reforming chamber 30, and the ECU 37 opens and closes the on-off valve when the bed temperature of the reforming chamber 30 detected by the bed temperature sensor 41 is lower than a preset activation temperature. 42 is closed to stop the generation of the reformed gas in the reforming chamber 30.

  Therefore, when the bed temperature of the reforming chamber 30 located on the downstream side is lower than the activation temperature, the generation of the reformed gas in the reforming chamber 30 is stopped to prevent the unburned gas from being mixed into the reformed gas. In addition, an appropriate reformed gas can be introduced into the combustion chamber 12 and the occurrence of coking in the reformer 26 can be suppressed. As a result, the reforming performance of the reformer 26 can be improved. it can.

  Further, the ECU 37 calculates the total fuel injection amount from the engine speed and the intake air amount, calculates the exhaust gas amount that can be recirculated to the intake pipe 15 from the engine speed and the throttle opening (engine load), and this exhaust gas. The amount of reformed gas that can be introduced into the intake pipe 15 is calculated from the amount of gas and the catalyst bed temperature of the reformer 26 to set the opening of the flow rate adjusting valve 36, and the second injector 34 is based on the amount of reformed gas. The exhaust fuel injection amount to be injected is set. Therefore, the amount of reformed gas increases or decreases according to the catalyst bed temperature of the reforming chamber 30 on the downstream side, and therefore the exhaust fuel injection amount is appropriately set according to the increase or decrease of the reformed gas amount. It is possible to reliably prevent the unburned gas from being mixed into the gas.

  FIG. 3 is a schematic configuration diagram showing an internal combustion engine according to the second embodiment of the present invention, and FIG. 4 is a flowchart showing control of the reformer in the internal combustion engine of the second embodiment. In addition, the same code | symbol is attached | subjected to the member which has the same function as what was demonstrated in the Example mentioned above, and the overlapping description is abbreviate | omitted.

  In the internal combustion engine of the second embodiment, as shown in FIG. 3, the engine 11 as the internal combustion engine is a port injection type four-cylinder type. An intake port 13 and an exhaust port 14 are formed to face the four combustion chambers 12, respectively, and can be opened and closed by an intake valve and an exhaust valve (not shown). The downstream end of the intake pipe 15 is connected to each intake port 13 via the intake manifold 16, and the first injector 20 is attached to the intake manifold 16. On the other hand, an exhaust pipe 25 is connected to each exhaust port 14 via an exhaust manifold 24, and a reformer 26 and a three-way catalyst 27 are attached to the exhaust pipe 25.

  The reformer 26 includes a cylindrical body 28, a first reforming chamber 29 and a second reforming chamber 30 which are disposed in the cylindrical body 28 and carry a reforming catalyst therein, and each reforming chamber 29, 30 and gas insertion passages 31, 32 formed so as to penetrate through 30. In this case, the first reforming chamber 29 and the second reforming chamber 30 are arranged in series in the cylinder 28 along the flow direction of the exhaust gas, and the gas insertion passages 31 and 32 are similarly connected in series. is doing. An exhaust gas branch pipe 33 is branched from the upstream side of the reformer 26 in the exhaust pipe 25, and the downstream end of the exhaust gas branch pipe 33 is branched into two branch branch pipes 33a and 33b. The diversion branch pipes 33a and 33b are connected to one end portions of the first and second reforming chambers 29 and 30 in the reformer 26, respectively. A second injector (second fuel supply means) 51 for injecting fuel into each of the branch flow branch pipes 33a and 33b to a part of the exhaust gas branched from the exhaust pipe 25 to the exhaust gas branch pipe 33 and the second A 3-injector (second fuel supply means) 52 is provided.

  Further, a reformed gas introduction pipe 35 for introducing the reformed gas generated by the reformer 26 into the intake pipe 15 is provided, and one end of the reformed gas introduction pipe 35 has two introduction branch pipes 35a. , 35b, and the introduction branch pipes 35a, 35b are connected to the other ends of the first and second reforming chambers 29, 30 in the reformer 26. The other end of the reformed gas introduction pipe 35 is connected to the intake pipe 15, and a flow rate adjusting valve 36 is attached to the reformed gas introduction pipe 35.

  Therefore, when the flow rate adjustment valve 36 is opened, a part of the exhaust gas flowing through the exhaust pipe 25 is diverted to the exhaust gas diversion pipe 33 and further diverted to the diversion branch pipes 33a and 33b. On the other hand, the second and third injectors 51 and 52 perform exhaust fuel injection. In this case, the exhaust gas contains oxygen, and the mixed gas in which the fuel and the exhaust gas containing oxygen are mixed flows into the reforming chambers 29 and 30 of the reformer 26, and from the exhaust pipe 25 to the reformer 26. Are heated by the heat of the exhaust gas flowing through the gas insertion passages 31 and 32. Then, the mixed gas is vaporized by promoting evaporation, and the vaporized mixed gas undergoes an endothermic reaction to be reformed to generate a reformed gas containing hydrogen, carbon monoxide and the like.

  Then, the reformed gas generated in the reformer 26 flows from the reforming chambers 29 and 30 to the reformed gas introduction pipe 35, and the supply amount thereof is adjusted by the opening degree of the flow rate adjusting valve 36. Supplied to the flowing intake air. Then, an air-fuel mixture obtained by mixing the intake air and the reformed gas is introduced from the intake manifold 16 through the intake port 13 into the combustion chamber 12 and ignited by the spark plug to explode. When the exhaust valve is opened, the exhaust gas is exhausted. The gas is discharged from the port 14 to the exhaust pipe 25. In this case, since the reformed gas contains hydrogen, combustion efficiency in the combustion chamber 12 is good, fuel efficiency can be improved, and generation of NOx can be suppressed and exhaust purification efficiency can be improved.

  The ECU 37 mounted on the vehicle determines the total fuel injection amount, injection timing, ignition timing, and the like based on the detected intake air amount, throttle opening (or accelerator opening), engine operating state such as engine speed. Has been decided. The reforming chambers 29 and 30 in the reformer 26 are respectively provided with bed temperature sensors 40 and 41, and the current catalyst bed temperatures of the reforming chambers 29 and 30 are output to the ECU 37. Therefore, the ECU 37 determines whether or not the reformer 26 is at the activation temperature based on the detected bed temperatures of the reforming chambers 29 and 30, and determines that the temperature of the reformer 26 is equal to or higher than the activation temperature. When this is done, the amount of reformed gas that can be introduced into the intake pipe 15 is calculated based on the amount of exhaust gas that can be recirculated to the intake pipe 15, the opening degree of the flow rate adjusting valve 36 is set, and the second and third injectors 51 are set. , 52 is set, the exhaust fuel injection amount is subtracted from the entire fuel injection amount, and the intake fuel injection amount injected by the first injector 20 is set.

  In this embodiment, the third injector 52 is applied as a reforming adjusting means for adjusting the generation operation of the reformed gas in the reforming chambers 29 and 30 of the reformer 26. When the bed temperature of the reforming chamber 30 detected by the bed temperature sensor 41 is lower than the activation temperature, the ECU 37 serving as the reforming control means stops the exhaust fuel injection from the third injector 52 to the reforming chamber 30. The supply of this fuel is stopped, and the generation operation of the reformed gas in the reforming chamber 30 is stopped. Therefore, by stopping the generation of the reformed gas in the reforming chamber 30 that has not reached the activation temperature, the introduction of the reformed gas containing unburned gas into the combustion chamber 12 is stopped, and the occurrence of coking is prevented. The catalyst performance is improved.

  Here, the fuel reforming control in the internal combustion engine of the second embodiment will be described in detail based on the flowchart of FIG.

  In the fuel reforming control in the internal combustion engine of the present embodiment, as shown in FIG. 4, in step S21, the ECU 37 detects the bed temperature of the reforming chamber 29 on the upstream side in the reformer 26, that is, the bed temperature sensor. It is determined whether the catalyst bed temperature detected by 40 has reached a predetermined activation temperature (for example, 600 ° C.) set in advance. If the ECU 37 determines that the catalyst bed temperature in the upstream reforming chamber 29 has not reached the predetermined activation temperature, the routine exits without doing anything.

  That is, since the catalyst bed temperature of the reforming chamber 29 in the reformer 26 has not reached the activation temperature, it is determined that the fuel reforming cannot be performed here, and the fuel reforming is stopped. In this case, the ECU 37 sets the total fuel injection amount calculated from the engine speed, the intake air amount, and the like as the intake fuel injection amount injected by the first injector 20, and the second and third injectors 51, 52 are injected. The exhaust fuel injection amount to be set is set to zero. Therefore, a part of the exhaust gas discharged to the exhaust pipe 25 of the engine 11 is diverted to the exhaust gas branch pipe 33 and passes through the reforming chambers 29 and 30 of the reformer 26, and then the reformed gas introduction pipe 35. The supply amount is adjusted by the opening degree of the flow rate adjustment valve 36 and supplied to the intake air flowing through the intake pipe 15 as EGR gas. Therefore, inflow of unburned gas into the intake pipe 15 can be prevented, and the exhaust gas is returned to the intake pipe 15 as EGR gas, so that carbon dioxide contained in the EGR gas is returned to the combustion chamber 12. Recombustion, the combustion temperature can be lowered, and the generation of NOx can be suppressed.

  On the other hand, if it is determined in step S21 that the catalyst bed temperature of the upstream reforming chamber 29 in the reformer 26 has reached a predetermined activation temperature, the process proceeds to step S22. In step S22, the ECU 37 sets a predetermined activation temperature (for example, 600) in which the bed temperature of the reforming chamber 30 on the downstream side in the reformer 26, that is, the catalyst bed temperature detected by the bed temperature sensor 41 is set in advance. ° C) is determined.

  If the ECU 37 determines in step S22 that the catalyst bed temperature in the downstream reforming chamber 30 has not reached the predetermined activation temperature, the process proceeds to step S23, where the second injector 51 causes the upstream reforming chamber to move. 29, the fuel corresponding to the reformed gas that can be reformed is injected. On the other hand, if the ECU 37 determines in step S22 that the catalyst bed temperature of the reforming chamber 30 on the downstream side in the reformer 26 has reached a predetermined activation temperature, the process proceeds to step S24, and the second and third steps are performed. The injectors 51 and 52 inject an amount of fuel corresponding to the reformed gas that can be reformed in the upstream reforming chamber 29 and the downstream reforming chamber 30.

  That is, if the catalyst bed temperature in the upper and lower reforming chambers 29 and 30 is equal to or higher than the activation temperature, the ECU 37 can reform the maximum exhaust gas amount that can be recirculated to the intake pipe 15 into the intake pipe 15. The gas amount is set, the opening degree of the flow rate adjusting valve 36 is set with respect to the reformed gas amount, and the second and third injectors 51 and 52 are based on the reformed gas amount adjusted by the flow rate adjusting valve 36. An exhaust fuel injection amount is set. Therefore, the exhaust gas circulates through the gas insertion passages 31 and 32 of the reformer 26, and part of the exhaust gas is diverted through the exhaust gas branch pipes 33 to the branch branch pipes 33a and 33b. Then, a predetermined amount of fuel is injected from the second and third injectors 51 and 52, and a mixed gas of fuel and exhaust gas flows into the reforming chambers 29 and 30. Then, the mixed gas flowing into the reforming chambers 29 and 30 is heated by the heat of the exhaust gas flowing through the gas insertion passages 31 and 32, undergoes an endothermic reaction, is reformed, and reforms containing hydrogen, carbon monoxide, and the like. A quality gas is produced. At this time, the exhaust fuel injection amount is appropriately adjusted in accordance with the reforming chambers 29 and 30 that can be reformed. Therefore, when the upper and lower reforming chambers 29 and 30 can be reformed, a high quality and maximum amount can be obtained. A reformed gas is generated.

  Then, the reformed gas generated in each of the reforming chambers 29 and 30 flows into the reformed gas introduction pipe 35, the supply amount thereof is adjusted by the opening degree of the flow rate adjusting valve 36, and the intake gas flowing through the intake pipe 15 Supplied against. Therefore, since the reformed gas containing hydrogen and carbon monoxide is introduced into the combustion chamber 12, combustion efficiency is good, a large amount of exhaust gas can be recirculated, and fuel consumption can be improved. Further, since the amount of exhaust gas (EGR gas amount) that can be recirculated by the reformed gas increases, carbon dioxide contained in the exhaust gas can be returned to the combustion chamber 12 for recombustion and the combustion temperature is lowered. By doing so, the generation of NOx can be suppressed, and the exhaust purification efficiency can be improved.

  On the other hand, when the catalyst bed temperature in the downstream reforming chamber 30 is not at the activation temperature and only the catalyst bed temperature in the upstream reforming chamber 29 is equal to or higher than the activation temperature, the maximum exhaust gas that can be recirculated to the intake pipe 15 The amount of reformed gas that can be introduced into the intake pipe 15 decreases with respect to the amount, and the opening degree of the flow rate adjustment valve 36 is set for this amount of reformed gas, and the reformed gas adjusted by the flow rate adjustment valve 36 The second and third injectors 51 and 52 exhaust fuel injection amounts are set based on the amount. That is, the exhaust fuel injection amount of the third injector 52 is set to zero. Therefore, the exhaust gas discharged to the exhaust pipe 25 of the engine 11 circulates through the gas insertion passages 31 and 32 of the reformer 26, and a part of the exhaust gas passes through the exhaust gas branch pipe 33 to each branch branch pipe 33 a, A predetermined amount of fuel is injected only from the second injector 51 into the exhaust gas. Then, the mixed gas flowing into the reforming chamber 29 is heated by the heat of the exhaust gas flowing through the gas insertion passage 31, undergoes an endothermic reaction, is reformed, and a reformed gas containing hydrogen, carbon monoxide, and the like is generated. The On the other hand, since no fuel is supplied to the reforming chamber 30, only the exhaust gas flows into the reforming chamber 30 so that the reforming reaction does not occur.

  At this time, since the exhaust fuel injection amount is appropriately adjusted according to the reforming chambers 29 and 30 that can be reformed, when only the reforming chamber 29 on the upstream side can be reformed, it is good quality and minimum The reformed gas is generated. Then, since the exhaust gas only passes through the reformer 30 that has not reached the activation temperature, the unburned gas is not mixed into the reformed gas generated in the reforming chamber 29, and the reformer 26. Coking is prevented.

  Then, the catalyst bed temperature of the reforming chamber 30 on the downstream side in the reformer 26 rises, and in step S22, the ECU 37 causes the catalyst bed temperature of the reforming chamber 30 on the downstream side in the reformer 26 to have a predetermined activity. If it is determined that the temperature has been reached, the process proceeds to step S24, and the second and third injectors 51 and 52 correspond to the reformed gas that can be reformed in the upstream reforming chamber 29 and the downstream reforming chamber 30. Inject an amount of fuel.

  As described above, in the internal combustion engine of the second embodiment, the reformer 26 having the two reforming chambers 29 and 30 is provided via the exhaust gas branch pipe 33 that shunts a part of the exhaust gas flowing through the exhaust pipe 25. In addition to the connection, the second and third injectors 51 and 52 are attached to the branching branch pipes 33 a and 33 b of the exhaust gas branch pipe 33, and the reformed gas generated by the reformer 26 is introduced into the intake pipe 15. An exhaust gas is supplied from the third injector 52 when the bed temperature of the reforming chamber 30 detected by the bed temperature sensor 41 is lower than a preset activation temperature. The injection is stopped and the generation of the reformed gas in the reforming chamber 30 is stopped.

  Therefore, when the bed temperature of the reforming chamber 30 located on the downstream side is lower than the activation temperature, the generation of the reformed gas in the reforming chamber 30 is stopped to prevent the unburned gas from being mixed into the reformed gas. In addition, an appropriate reformed gas can be introduced into the combustion chamber 12 and the occurrence of coking in the reformer 26 can be suppressed. As a result, the reforming performance of the reformer 26 can be improved. it can.

  In the second embodiment, the third injector 52 is applied as the reforming adjusting means of the present invention. However, in addition to the third injector 52, as described in the first embodiment, the introduction branch pipe 35b has an on-off valve. May be provided. With this configuration, the reformed gas generated in the first reforming chamber 29 is reliably transferred to the intake pipe 15 by preventing the exhaust gas that has passed through the second reforming chamber 30 from flowing into the reformed gas introduction tube 35. Can be introduced.

  FIG. 5 is a schematic configuration diagram showing the internal combustion engine according to the third embodiment of the present invention, and FIG. 6 is a graph showing the optimum exhaust fuel injection ratio with respect to the catalyst bed temperature in the internal combustion engine of the third embodiment. In addition, the same code | symbol is attached | subjected to the member which has the same function as what was demonstrated in the Example mentioned above, and the overlapping description is abbreviate | omitted.

  In the internal combustion engine of the third embodiment, as shown in FIG. 5, the engine 11 as the internal combustion engine is a port injection type four-cylinder type. An intake port 13 and an exhaust port 14 are formed to face the four combustion chambers 12, respectively, and can be opened and closed by an intake valve and an exhaust valve (not shown). The downstream end of the intake pipe 15 is connected to each intake port 13 via the intake manifold 16, and the first injector 20 is attached to the intake manifold 16. On the other hand, an exhaust pipe 25 is connected to each exhaust port 14 via an exhaust manifold 24, and a reformer 26 and a three-way catalyst 27 are attached to the exhaust pipe 25.

  The reformer 26 includes a cylindrical body 28, a first reforming chamber 29 and a second reforming chamber 30 which are disposed in the cylindrical body 28 and carry a reforming catalyst therein, and each reforming chamber 29, 30 and gas insertion passages 31, 32 formed so as to penetrate through 30. An exhaust gas distribution pipe 33 is branched from the upstream side of the reformer 26 in the exhaust pipe 25, and the downstream end of the exhaust gas distribution pipe 33 is connected to one end of the first reforming chamber 29. ing. A second injector (second fuel supply means) 61 for injecting fuel into the exhaust gas distribution pipe 33 is provided. The other end portion of the first reforming chamber 29 is connected to one end portion of the first reforming chamber 29 via a connecting pipe (connecting passage) 62. A third injector (second fuel supply means) 63 for injecting fuel into the connecting pipe 62 is provided.

  Further, a reformed gas introduction pipe 35 for introducing the reformed gas generated by the reformer 26 into the intake pipe 15 is provided, and one end portion of the reformed gas introduction pipe 35 is in the second reforming chamber 30. Is connected to the other end of the. The other end of the reformed gas introduction pipe 35 is connected to the intake pipe 15, and a flow rate adjusting valve 36 is attached to the reformed gas introduction pipe 35.

  Therefore, in a state where the flow rate adjustment valve 36 is opened, a part of the exhaust gas flowing through the exhaust pipe 25 is diverted to the exhaust gas branch pipe 33, and the second injector 61 performs exhaust fuel injection on the exhaust gas. In this case, the exhaust gas contains oxygen, and the mixed gas in which the fuel and the exhaust gas containing oxygen are mixed flows into the first reforming chamber 29 of the reformer 26 and flows from the exhaust pipe 25 to the reformer 26. Heated by the heat of the exhaust gas flowing through the gas insertion passage 31. Then, the mixed gas is vaporized by promoting evaporation, and the vaporized mixed gas undergoes an endothermic reaction to be reformed to generate a reformed gas containing hydrogen, carbon monoxide and the like. Subsequently, after the reformed gas is generated in the first reforming chamber 29, the exhaust gas containing the reformed gas flows to the connecting pipe 62, and the third injector 63 injects exhaust fuel into the exhaust gas. Do. Here, similarly, the mixed gas of the fuel and the exhaust gas containing oxygen flows into the second reforming chamber 30 and is heated by the heat of the exhaust gas flowing from the exhaust pipe 25 through the gas insertion passage 32 of the reformer 26. . Then, the mixed gas is vaporized by promoting evaporation, and the vaporized mixed gas undergoes an endothermic reaction to be reformed to generate a reformed gas containing hydrogen, carbon monoxide and the like.

  Then, the reformed gas generated in the reformer 26 flows from the reforming chamber 30 to the reformed gas introduction pipe 35, the supply amount thereof is adjusted by the opening degree of the flow rate adjusting valve 36, and the intake air flowing through the intake pipe 15. Supplied against. Then, an air-fuel mixture obtained by mixing the intake air and the reformed gas is introduced from the intake manifold 16 through the intake port 13 into the combustion chamber 12 and ignited by the spark plug to explode. When the exhaust valve is opened, the exhaust gas is exhausted. The gas is discharged from the port 14 to the exhaust pipe 25. In this case, since the reformed gas contains hydrogen, combustion efficiency in the combustion chamber 12 is good, fuel efficiency can be improved, and generation of NOx can be suppressed and exhaust purification efficiency can be improved.

  The ECU 37 mounted on the vehicle determines the total fuel injection amount, injection timing, ignition timing, and the like based on the detected intake air amount, throttle opening (or accelerator opening), engine operating state such as engine speed. Has been decided. The reforming chambers 29 and 30 in the reformer 26 are respectively provided with bed temperature sensors 40 and 41, and the current catalyst bed temperatures of the reforming chambers 29 and 30 are output to the ECU 37. Therefore, the ECU 37 determines whether or not the reformer 26 is at the activation temperature based on the detected bed temperatures of the reforming chambers 29 and 30, and determines that the temperature of the reformer 26 is equal to or higher than the activation temperature. When this is done, the amount of reformed gas that can be introduced into the intake pipe 15 is calculated based on the amount of exhaust gas that can be recirculated to the intake pipe 15, the opening degree of the flow rate adjusting valve 36 is set, and the second and third injectors 61 are set. 63, the exhaust fuel injection amount is set, the exhaust fuel injection amount is subtracted from the total fuel injection amount, and the intake fuel injection amount injected by the first injector 20 is set.

  In this embodiment, the second and third injectors 61 and 63 are applied as reforming adjusting means for adjusting the reforming gas generation operation in the reforming chambers 29 and 30 of the reformer 26. The ECU 37 as the reforming control means sets the exhaust fuel injection amounts from the second and third injectors 61 and 63 based on the bed temperatures of the reforming chambers 29 and 30 detected by the bed temperature sensors 40 and 41. Thus, when the amount of fuel supplied to the reforming chamber 30 is adjusted and the bed temperature of the reforming chamber 30 detected by the bed temperature sensor 41 is lower than the activation temperature, the reformed gas is generated in the reforming chamber 30. Is trying to reduce. Therefore, by reducing the generation of reformed gas in the reforming chamber 30 that has not reached the activation temperature, the introduction of reformed gas containing unburned gas into the combustion chamber 12 is stopped, and the occurrence of coking is prevented. The catalyst performance is improved.

  That is, as shown in FIG. 6, when the reformed gas is generated in each of the reforming chambers 29 and 30 in the reformer 26, the optimum exhaust fuel injection ratio (optimum exhaust fuel injection) for generating this reformed gas. (Amount / EGR gas amount) increases as the catalyst bed temperature of the reformer 26 increases. Therefore, the ECU 37 adjusts the exhaust fuel injection amounts of the second and third injectors 61 and 63 based on the bed temperatures of the reforming chambers 29 and 30 detected by the bed temperature sensors 40 and 41, and also reforms the chamber 30. When the bed temperature is lower than the activation temperature, the exhaust fuel injection amount of the third injector 63 is decreased.

  More specifically, as shown in FIG. 5, if the catalyst bed temperature in the upper and lower reforming chambers 29, 30 is equal to or higher than the activation temperature, the ECU 37 corresponds to the maximum amount of exhaust gas that can be recirculated to the intake pipe 15. Then, the amount of reformed gas that can be introduced into the intake pipe 15 is set, the opening degree of the flow rate adjusting valve 36 is set with respect to this reformed gas amount, and based on the reformed gas amount adjusted by the flow rate adjusting valve 36. Thus, the exhaust fuel injection amounts by the second and third injectors 61 and 63 are set. Therefore, the exhaust gas flows through the gas insertion passages 31 and 32 of the reformer 26, and a part of the exhaust gas is diverted to the exhaust gas branch pipe 33, and a predetermined amount of fuel is supplied from the second injector 51 to the exhaust gas. Is injected, and a mixed gas of fuel and exhaust gas flows into the first reforming chamber 29. Then, the mixed gas flowing into the first reforming chamber 29 is heated by the heat of the exhaust gas flowing through the gas insertion passage 31, undergoes an endothermic reaction, is reformed, and is a reformed gas containing hydrogen, carbon monoxide, or the like. Is generated. Subsequently, the exhaust gas containing the reformed gas flows into the connecting pipe 62, and a predetermined amount of fuel is injected from the third injector 63 to the exhaust gas, and the mixed gas of fuel and exhaust gas is changed to the second modified gas. It flows into the pawn chamber 30. Then, the mixed gas flowing into the second reforming chamber 30 is heated by the heat of the exhaust gas flowing through the gas insertion passage 32, undergoes an endothermic reaction, is reformed, and is a reformed gas containing hydrogen, carbon monoxide, or the like. Is generated. At this time, the exhaust fuel injection amount is appropriately adjusted in accordance with the reforming chambers 29 and 30 that can be reformed. Therefore, when the upper and lower reforming chambers 29 and 30 can be reformed, a high quality and maximum amount can be obtained. A reformed gas is generated.

  Then, the reformed gas generated in each of the reforming chambers 29 and 30 flows into the reformed gas introduction pipe 35, the supply amount thereof is adjusted by the opening degree of the flow rate adjusting valve 36, and the intake gas flowing through the intake pipe 15 Supplied against. Therefore, since the reformed gas containing hydrogen and carbon monoxide is introduced into the combustion chamber 12, combustion efficiency is good, a large amount of exhaust gas can be recirculated, and fuel consumption can be improved. Further, since the amount of exhaust gas (EGR gas amount) that can be recirculated by the reformed gas increases, carbon dioxide contained in the exhaust gas can be returned to the combustion chamber 12 for recombustion and the combustion temperature is lowered. By doing so, the generation of NOx can be suppressed, and the exhaust purification efficiency can be improved.

  On the other hand, when the catalyst bed temperature in the downstream reforming chamber 30 is not at the activation temperature and only the catalyst bed temperature in the upstream reforming chamber 29 is equal to or higher than the activation temperature, the maximum exhaust gas that can be recirculated to the intake pipe 15 The amount of reformed gas that can be introduced into the intake pipe 15 decreases with respect to the amount, and the opening degree of the flow rate adjusting valve 36 is set with respect to this reformed gas amount. The second and third injectors 61 and 63 exhaust fuel injection amounts are set based on the amount.

  That is, the exhaust fuel injection amount of the third injector 63 is set, that is, decreases according to the floor temperature of the reforming chamber 30. Therefore, the exhaust gas discharged to the exhaust pipe 25 of the engine 11 circulates through the gas insertion passages 31 and 32 of the reformer 26, and a part of the exhaust gas is diverted to the exhaust gas branch pipe 33. Thus, a predetermined amount of fuel is injected from the second injector 61. Then, the mixed gas flowing into the reforming chamber 29 is heated by the heat of the exhaust gas flowing through the gas insertion passage 31, undergoes an endothermic reaction, is reformed, and a reformed gas containing hydrogen, carbon monoxide, and the like is generated. The Subsequently, the exhaust gas containing the reformed gas flows into the connecting pipe 62, and a predetermined amount of fuel is injected from the third injector 63 to the exhaust gas, and the mixed gas of fuel and exhaust gas is changed to the second modified gas. It flows into the pawn chamber 30. In this case, since a small amount of fuel is injected into the third injector 63 according to the bed temperature of the second reforming chamber 30, the fuel concentration of the mixed gas flowing into the second reforming chamber 30 decreases. The gas is heated by the heat of the exhaust gas flowing through the gas insertion passage 32, undergoes an endothermic reaction, is reformed, and a small amount of reformed gas containing hydrogen, carbon monoxide, and the like is generated.

  When the reforming chamber 30 has not reached the activation temperature, the exhaust fuel injection amount by the third injector 63 is adjusted (decreased) in accordance with the bed temperature. Therefore, in the reformer 30 that has not reached the activation temperature, Since a reformable amount of fuel is supplied, unburned gas is not mixed into the reformed gas generated by the reformer 26, and coking of the reformer 26 is prevented.

  As described above, in the internal combustion engine of the third embodiment, the first reforming chamber 29 is connected via the exhaust gas branch pipe 33 that shunts a part of the exhaust gas flowing through the exhaust pipe 25, and this first reforming is performed. The chamber 29 is connected to the second reforming chamber 30 via the connecting pipe 62, and the second and third injectors 61 and 63 are attached to the exhaust gas distribution pipe 33 and the connecting pipe 62, and are generated by the reformer 26. A reformed gas introduction pipe 35 and a flow rate adjusting valve 36 for introducing the reformed gas into the intake pipe 15 are provided, and the ECU 37 is an activation temperature at which the bed temperature of the reforming chamber 30 detected by the bed temperature sensor 41 is set in advance. When the temperature is lower, the exhaust fuel injection from the third injector 61 is reduced according to the bed temperature, and the amount of reformed gas generated in the reforming chamber 30 is reduced.

  Therefore, when the bed temperature of the reforming chamber 30 located on the downstream side is lower than the activation temperature, the exhaust fuel injection from the third injector 61 is reduced according to the bed temperature, so that the unburned gas to the reformed gas is reduced. Mixing can be suppressed, and an appropriate reformed gas can be introduced into the combustion chamber 12, and the occurrence of coking in the reformer 26 can be suppressed. As a result, the reforming performance of the reformer 26 is improved. can do.

  Further, in the present embodiment, when the bed temperature of the reforming chamber 30 is lower than the activation temperature, the reformed gas is also used in the reforming chamber 30 by reducing exhaust fuel injection from the third injector 61 according to the bed temperature. , And the mixing of unburned gas into the reformed gas can be suppressed, and the endothermic reaction in the reformer 26 can be used efficiently.

  In each of the above-described embodiments, the bed temperature sensors 40 and 41 are applied as the bed temperature detecting means for detecting the bed temperature of the reforming catalyst in each of the reforming chambers 29 and 30 in the reformer 26. You may obtain | require and estimate based on engine operation states, such as an engine speed, intake air amount, and accelerator opening. In addition, the amount of reformed gas introduced into the intake pipe 15 is calculated based on engine operating conditions such as engine speed, accelerator opening, and catalyst bed temperature, but the flow rate adjustment valve 36 in the reformed gas introduction pipe 35 is opened. It may be calculated from the degree, or may be measured by providing a flow meter downstream of the flow rate adjustment valve 36 in the reformed gas introduction pipe 35.

  Further, in each of the above-described embodiments, the two reforming chambers 29 and 30 are provided in the reformer 26, but three or more may be provided according to the displacement of the internal combustion engine. In this case, although the plurality of reforming chambers 29 and 30 are provided in the cylindrical body 28 in the reformer 26, a plurality of reformers having reforming chambers may be connected to the exhaust pipe 25.

  As described above, the internal combustion engine according to the present invention has a plurality of reforming chambers in the exhaust passage and adjusts the generation operation of the reformed gas according to the bed temperature of each reforming chamber, thereby preventing the occurrence of coking. It suppresses and is useful for any internal combustion engine.

1 is a schematic configuration diagram illustrating an internal combustion engine according to a first embodiment of the present invention. 3 is a flowchart showing control of the reformer in the internal combustion engine of the first embodiment. It is a schematic block diagram showing the internal combustion engine which concerns on Example 2 of this invention. 6 is a flowchart showing control of a reformer in the internal combustion engine of the second embodiment. It is a schematic block diagram showing the internal combustion engine which concerns on Example 3 of this invention. 6 is a graph showing an optimum exhaust fuel injection ratio with respect to catalyst bed temperature in the internal combustion engine of the third embodiment.

Explanation of symbols

11 Engine (Internal combustion engine)
12 Combustion chamber 13 Intake port 14 Exhaust port 15 Intake pipe (intake passage)
19 Electronic throttle device 20 First injector (first fuel supply means)
25 Exhaust pipe (exhaust passage)
26 Reformer 27 Three-way catalyst 28 Cylindrical body 29, 30 Reforming chamber 31, 32 Gas insertion path 33 Exhaust gas branch pipe (exhaust gas branch path)
34 Second injector (second fuel supply means)
35 Reformed gas introduction pipe (reformed gas introduction passage)
36 Flow control valve 37 Electronic control unit, ECU (reforming control means)
38 Airflow sensor 39 Crank angle sensor 40, 41 Floor temperature sensor (floor temperature detection means)
42 On-off valve (reforming stop means)
51, 61 Second injector (second fuel supply means)
52, 63 Third injector (second fuel supply means, reforming stop means)
62 Connection pipe (connection passage)

Claims (6)

  An intake passage for introducing outside air into the combustion chamber, first fuel supply means for supplying fuel to the intake passage or the combustion chamber, an exhaust passage for exhausting exhaust gas discharged from the combustion chamber to the outside, and the exhaust An exhaust gas diversion passage for diverting a part of the exhaust gas flowing through the passage, a second fuel supply means for supplying fuel to the exhaust gas diversion passage, and the exhaust supplied with fuel from the second fuel supply means A reformer having a plurality of reforming chambers that generate reformed gas by introducing exhaust gas flowing through the gas diversion passage, and reforming that introduces the reformed gas generated by the reformer into the intake passage A gas introduction passage, a bed temperature detecting means for detecting a bed temperature of the plurality of reforming chambers, a reforming adjusting means for adjusting a generation operation of the reformed gas in the plurality of reforming chambers, and the bed temperature detecting means. For the reforming chamber where the detected bed temperature is lower than the preset active temperature. Internal combustion engine, characterized in that it comprises a modified control means for reducing the generation operation of the reformed gas by the reforming adjusting means Te.   2. The internal combustion engine according to claim 1, wherein the plurality of reforming chambers are arranged in series in the exhaust passage along a flow direction of exhaust gas, and the plurality of reforming branch passages on the downstream side of the exhaust gas branch passage are the plurality of reforming chambers. An upstream branching passage in the reformed gas introduction passage is connected to the plurality of reforming chambers, and an on-off valve as the reforming adjusting means is the branch flow passage or the branching passage. An internal combustion engine provided in the introduction branch passage.   2. The internal combustion engine according to claim 1, wherein the plurality of reforming chambers are arranged in series in the exhaust passage along a flow direction of exhaust gas, and the plurality of reforming branch passages on the downstream side of the exhaust gas branch passage are the plurality of reforming chambers. The reforming chamber is connected to a plurality of reforming chambers, and the second fuel supply means as the reforming adjusting means is connected to the shunt flow. An internal combustion engine provided in a branch passage.   2. The internal combustion engine according to claim 1, wherein the plurality of reforming chambers are arranged in series in the exhaust passage along a flow direction of the exhaust gas, and a downstream side of the exhaust gas diversion passage is a first reforming chamber. Connected, the first reforming chamber is connected to the second reforming chamber via a connecting passage, the upstream side of the reformed gas introduction passage is connected to the second reforming chamber, and the reforming adjustment is performed. An internal combustion engine characterized in that the second fuel supply means as means is provided in the connecting passage.   5. The internal combustion engine according to claim 1, wherein the reforming control unit is configured to perform the reforming gas generation operation in the plurality of reforming chambers by the reforming adjustment unit. 2. An internal combustion engine characterized in that the amount of fuel supplied by the fuel supply means is reduced. 5. The internal combustion engine according to claim 1, wherein a flow rate adjusting valve is provided in the reformed gas introduction passage, and the reforming control unit includes the plurality of reforming chambers formed by the reforming adjusting unit. An internal combustion engine characterized in that the amount of fuel supplied by the second fuel supply means is reduced and the opening degree of the flow rate adjusting valve is reduced in accordance with the reformed gas generation operation state.

Images