JP2006291757A - Control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve fuel economy by suppressing production of coking and improving formation efficiency of reformed gas in a control device for an internal combustion engine. <P>SOLUTION: A fuel reformer 24 forming reformed gas by heating and reforming mixed gas mixing fuel with exhaust gas and a circulation passage 27 for supplying reformed gas formed by the fuel reformer 24 to an intake pipe 15 are provided. The ECU 30 changes mixing ratio of fuel and exhaust gas based on present humidity detected by a humidity sensor 35. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a control device for 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 apparatus for controlling an exhaust reformer system that supplies gas to an intake passage.

  Conventionally, a part of the exhaust gas of the internal combustion engine is taken out and supplied as a recirculation gas to the intake system, and this recirculation gas is mixed with the intake air to lower the maximum temperature during combustion and to reduce 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 (reformer gas) containing hydrogen and carbon monoxide is generated from the mixed gas, and the reformer gas is supplied to the intake system. There has been proposed an exhaust reformer system for an internal combustion engine that efficiently recovers exhaust heat and improves fuel efficiency.

  An example of such an exhaust reformer system for an internal combustion engine is described in Patent Document 1 below.

JP 2004-092520 A

  In the conventional exhaust reformer system for an internal combustion engine, a mixed gas is generated by injecting and mixing a predetermined amount of fuel to the recirculated gas from which a part of the exhaust gas is extracted, and the mixed gas is heated. Then, reformer gas is generated by passing the reforming catalyst. In this case, the amount of fuel injected into the recirculated gas is calculated based on the operating state of the internal combustion engine, that is, the rotational speed, load, and exhaust temperature.

  However, if the mixed gas obtained by mixing the recirculated gas with the fuel amount calculated based on the operating state of the internal combustion engine is heated and then introduced into the reforming catalyst, all the fuel is not reformed to the ideal state, and the reforming catalyst Coking will occur. This coking is a phenomenon in which when the fuel is reformed by the reforming catalyst, carbon in the fuel is deposited and adheres to the cells of the reforming catalyst, and the reforming ability is reduced. For this reason, in general, the actual amount of fuel supplied to the recirculated gas is less than the amount of fuel theoretically calculated based on the operating state of the internal combustion engine, thereby suppressing the occurrence of coking.

  However, if the actual amount of fuel supplied to the reflux gas is less than the amount of fuel theoretically calculated based on the operating state of the internal combustion engine, coking is suppressed, but it is generated by reaction with the reforming catalyst. The amount of reformer gas, that is, the amount of hydrogen is also reduced, so that the combustion of the internal combustion engine cannot be sufficiently improved, and the fuel efficiency cannot be improved reliably.

  The present invention is for solving such a problem, and provides an internal combustion engine control device that improves fuel efficiency by suppressing the occurrence of coking and improving the generation efficiency of reformed gas. For the purpose.

  In order to solve the above-described problems and achieve the object, the control device for an internal combustion engine of the present invention generates reformer gas by heating and reforming a mixed gas composed of fuel and a gas containing oxygen. Fuel reforming means, reformer gas supply means for supplying reformer gas generated by the fuel reforming means to the intake passage of the internal combustion engine, humidity detecting means for detecting humidity, and detection results of the humidity detecting means And a mixing ratio changing means for changing the mixing ratio of the fuel and the gas containing oxygen.

  In the control device for an internal combustion engine according to the present invention, the gas containing oxygen is an exhaust gas of the internal combustion engine, a fuel amount is set based on a rotational speed, a load, and an exhaust gas temperature of the internal combustion engine, and the mixing ratio changing means Is characterized in that the amount of fuel is increased as the humidity detected by the humidity detecting means increases.

  In the control apparatus for an internal combustion engine of the present invention, the mixing ratio changing means increases the fuel amount as the humidity increases when the humidity detected by the humidity detecting means exceeds a preset reference value. It is characterized by.

  In the control device for an internal combustion engine according to the present invention, the gas containing oxygen is the exhaust gas of the internal combustion engine, and the reform start timing is set based on the rotational speed and load of the internal combustion engine. It is characterized by being corrected by the gas temperature.

  The control apparatus for an internal combustion engine according to the present invention is characterized in that the reforming start time is corrected so as to be advanced by an increase in the exhaust gas temperature.

  In the control apparatus for an internal combustion engine according to the present invention, the exhaust gas temperature is estimated from an ambient environment and a combustion state of the internal combustion engine.

  According to the control apparatus for an internal combustion engine of the present invention, a fuel reforming unit that generates reformer gas by heating and reforming a mixed gas composed of a fuel and a gas containing oxygen, and the fuel reforming unit Reformer gas supply means for supplying the generated reformer gas to the intake passage of the internal combustion engine, and the mixing ratio changing means is configured to convert the fuel and oxygen-containing gas based on the current humidity detected by the humidity detection means. Change the mixing ratio. In the fuel reforming means, as the amount of water contained in the mixed gas increases, the reforming efficiency increases. It is possible to improve the fuel efficiency by improving the generation efficiency of the reformed gas.

  Embodiments of an internal combustion engine control apparatus according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

  FIG. 1 is a schematic configuration diagram illustrating an internal combustion engine control apparatus according to Embodiment 1 of the present invention, FIG. 2 is a flowchart illustrating reforming processing in the internal combustion engine control apparatus according to Embodiment 1, and FIG. FIG. 4 is a control map showing an exhaust injection amount with respect to humidity in the control apparatus for an internal combustion engine according to the first embodiment. .

  In the control apparatus for an internal combustion engine of the first embodiment, as shown in FIG. 1, an 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. The pistons are respectively fitted to the 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 configured corresponding to four cylinders by the cylinder block, the cylinder head, and the piston, and each combustion chamber 12 is formed with an intake port 13 and an exhaust port 14 facing each other at the upper portion. 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 15 is connected to the intake port 13 via a surge tank 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. Each intake port 13 corresponding to each combustion chamber 12 is provided with a first injector 20 for injecting fuel, and each first injector 20 is connected to a fuel pump (not shown) via a fuel supply pipe 21. Connected to the fuel tank. Although not shown, each combustion chamber 12 is equipped with a spark plug that ignites the air-fuel mixture.

  On the other hand, an exhaust pipe 22 is connected to the exhaust port 14, and a three-way catalyst 23 that purifies harmful substances such as HC, CO, and NOx contained in the exhaust gas is attached to the exhaust pipe 22. Yes.

  In the engine 11 of this embodiment, fuel is supplied to a part of the exhaust gas recirculation gas, and then reformed by exhaust heat to generate reformed gas (reformer gas). An exhaust reformer system as a fuel reformer that is supplied to the passage is mounted.

  That is, a fuel reformer (fuel reforming means) 24 having a heat exchanger and a fuel evaporator 25 are provided downstream of the three-way catalyst 23 in the exhaust pipe 22. A branch pipe 26 is provided at the downstream end of the fuel evaporator 25 in the exhaust pipe 22, and a reformer gas recirculation passage (reformer gas supply means) 27 is connected to the branch pipe 26. The recirculation passage 27 has a reformer gas control valve 28, and an end thereof is connected to the downstream side of the electronic throttle device 19 in the intake pipe 15. The exhaust gas recirculation passage 27 is provided with a second injector 29 that injects fuel to the recirculation gas as a part of the exhaust gas introduced from the branch pipe 26 into the recirculation passage 27 at the upstream end portion. It penetrates the evaporator 25 and communicates with the fuel reformer 24. In the fuel reformer 24, an exhaust gas passage that communicates with an exhaust pipe 22 and a mixed gas passage that communicates with a reflux passage 27 are partitioned by a partition, and a catalyst that generates reformer gas in the mixed gas passage (for example, (Co, Ni, Rh).

  The engine 11 of this embodiment burns fuel injected into the intake air flowing through the intake port 13 by the first injector 20 and fuel injected into the exhaust gas flowing through the recirculation passage 27 by the second injector 29. The fuel is introduced into the chamber 12 and burned. The fuel injection by the first injector 20 is referred to as intake fuel injection, and the fuel injection from the second injector 29 is referred to as exhaust fuel injection.

  Therefore, when the fuel reforming start condition described later is not satisfied, the reformer gas control valve 28 is closed, and the first injector 20 with respect to the intake air introduced into the combustion chamber 12 from the intake pipe 15 through the intake port 13 Fuel injection (intake fuel injection) is performed, and an air-fuel mixture in which intake air and fuel are mixed is introduced into the combustion chamber 12 to ignite and explode. Discharged.

  On the other hand, when the fuel reforming start condition is satisfied, the reformer gas control valve 28 is opened, and a part of the exhaust gas is introduced from the exhaust pipe 22 into the recirculation passage 27 through the branch pipe 26. The second injector 29 performs fuel injection (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 is vaporized in the fuel evaporator 25 by the evaporation being accelerated by the heat of the exhaust gas flowing through the exhaust pipe 22. To do. Subsequently, the vaporized mixed gas is reformed by causing an endothermic reaction by being heated by the heat of the exhaust gas in the fuel reformer 24. As shown in the following Equation 1, hydrogen and carbon monoxide A reformer gas containing nitrogen is generated.

  The reformer gas generated by the fuel reformer 24 is supplied in an amount adjusted by the opening of the reformer gas control valve 28 and supplied to the intake air flowing through the intake pipe 15. The mixed gas is introduced into the combustion chamber 12 and ignited to explode, and exhaust gas is discharged from the exhaust port 14 to the exhaust pipe 22 when the exhaust valve is opened and closed. In this case, since the reformer gas contains hydrogen, combustion efficiency in the combustion chamber 12 is good, fuel efficiency can be improved, and generation of NOx can be suppressed to improve exhaust purification efficiency.

  In the above description, when the fuel reforming start condition is satisfied, the reformer gas control valve 28 is opened and supplied to the reformer gas intake pipe 15, but the fuel reforming start condition is not satisfied. Even when the exhaust pipe 15 is opened, the reformer gas control valve 28 is opened without injecting the exhaust fuel from the second injector 29 in accordance with the engine operating state. To suppress the generation of NOx.

  By the way, an electronic control unit (ECU) 30 is mounted on the vehicle, and the ECU 30 can control the fuel injection amount, the injection timing, the ignition timing, and the like by drivingly controlling the first injector 20 and the ignition plug. It has become. That is, an air flow sensor 31 is mounted on the upstream side of the intake pipe 15 and outputs the measured intake air amount to the ECU 30. The electronic throttle device 19 has a throttle position sensor and outputs the current throttle opening to the ECU 30. Further, the crank angle sensor 32 outputs the detected crank angle of each cylinder to the ECU 30, and the ECU 30 determines 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. In addition, an accelerator opening sensor 33 that detects the depression amount of the accelerator pedal as an accelerator opening is provided, and the current accelerator opening is output to the ECU 30.

  Accordingly, the ECU 30 determines the fuel injection amount, the injection timing, the ignition timing, and the like based on the detected engine operation state such as the intake air amount, the throttle opening, the accelerator opening, and the engine speed. 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 29.

  The ECU 30 can control the exhaust reformer system by driving and controlling the second injector 29, the reformer gas control valve 28, and the like. That is, the exhaust pipe 22 is provided with an exhaust temperature sensor 34 located downstream of the fuel evaporator 25, and outputs the current exhaust gas temperature to the ECU 30. In this embodiment, the throttle position sensor of the electronic throttle device 19 that detects the throttle opening is applied as the engine load.

  Therefore, as shown in FIG. 3, the fuel reforming region is set in advance based on the engine load (throttle opening) and the engine speed. Further, based on the engine speed, the engine load (throttle opening), and the exhaust gas temperature, the exhaust fuel injection amount injected by the second injector 29 is set, and the opening of the reformer gas control valve 28 is set. The Therefore, when the ECU 30 determines that the current operating state of the engine 11 is in the reforming region, the ECU 30 executes exhaust fuel injection by the second injector 29 to inject a predetermined amount of fuel, and the reformer gas control valve 28. Is opened at a predetermined angle, fuel reforming using the fuel reformer 24 is started, and a predetermined amount of reformer gas is supplied to the intake pipe 15. In this case, the entire fuel injection amount is set based on the engine operating state, and when the second injector 29 executes the exhaust fuel injection, the first injector 20 calculates the exhaust fuel injection amount from the entire fuel injection amount. The subtracted amount of intake fuel injection amount is injected.

  In the present embodiment, the mixing ratio between the exhaust fuel injection amount by the second injector 29 and the exhaust gas introduced into the recirculation passage 27 is changed (mixing ratio changing means). That is, the exhaust fuel injection amount by the second injector 29 set based on the engine speed, the engine load (throttle opening), and the exhaust gas temperature is changed according to the current humidity. That is, if the actual exhaust fuel injection amount by the second injector 29 is a theoretical exhaust fuel injection amount set based on the engine speed, the engine load, and the exhaust gas temperature, coking is likely to occur. Is considered to occur at a ratio of the amount of carbon in the fuel and the amount of moisture in the exhaust gas. If the amount of moisture in the exhaust gas is large, coking is suppressed and produced by a reaction in the fuel reformer 24. There is a tendency that the amount of reformer gas (hydrogen amount) is increased. Therefore, in this embodiment, the amount of exhaust fuel injected by the second injector 29 is changed according to the current humidity.

Here, the humidity sensor 35 provided in the air-conditioning control device is applied as humidity detection means for detecting humidity, and the current humidity outside the vehicle detected by the humidity sensor 35 is output to the ECU 30. Then, the ECU 30 estimates the humidity of the exhaust gas having a correlation with the current humidity, and as shown in FIG. 4, the ECU 30 sets the exhaust fuel injection amount set using the control map of this humidity and the exhaust fuel injection amount. to correct. In this case, when the detected humidity is lower than the predetermined humidity h _s , the exhaust fuel injection amount is set to a predetermined amount Q _s set based on the engine speed, the engine load, and the exhaust gas temperature, and the humidity is equal to or higher than the predetermined humidity h _s. Then, the exhaust fuel injection amount is increased as the humidity increases.

  Here, the reforming process control by the control apparatus for the internal combustion engine of the present embodiment described above will be described in detail based on the flowchart of FIG.

In step S11, the engine speed, engine load (throttle opening), exhaust gas temperature, and humidity are read. In step S12, the exhaust fuel injection amount is calculated based on the engine speed, the engine load, and the exhaust gas temperature. In step S13, it is determined whether or not the current humidity h is equal to or higher than the predetermined humidity h _s . When the humidity h is lower than the predetermined humidity h _s , the process proceeds to step S15 without correcting the exhaust fuel injection amount, and the humidity h is When the humidity is equal to or higher than the predetermined humidity h _s , in step S14, the exhaust fuel injection amount is corrected based on the control map of FIG. In step S15, the opening degree of the reformer gas control valve 28 is calculated based on the engine speed, the engine load (throttle opening degree), and the exhaust gas temperature.

  In step S16, it is determined from the engine load (throttle opening) and the engine speed based on the control map of FIG. 3 whether the current engine operating state is in the fuel reforming region. In step S16, if the current engine operating state is not in the fuel reforming region, the routine exits without doing anything. On the other hand, if the current engine operating state is in the fuel reforming region, reforming processing is executed in step S17.

  That is, by performing exhaust fuel injection by the second injector 29 and opening the reformer gas control valve 28, first, a mixed gas in which fuel and exhaust gas are mixed is introduced into the fuel evaporator 25, and the mixed gas is discharged. Evaporation is promoted to vaporize, and then the vaporized mixed gas is introduced into the fuel reformer 24, and heated by the heat of the exhaust gas to cause an endothermic reaction, thereby including a reformer containing hydrogen, carbon monoxide, and nitrogen. Generate gas. The generated reformer gas is supplied to the intake air flowing through the intake pipe 15 after the supply amount is adjusted by the reformer gas control valve 28 through the reflux passage 27. Then, an air-fuel mixture in which intake air and reformer gas are mixed is introduced into the combustion chamber 12 and is combusted by being ignited by the air-fuel mixture.

  In this case, since the reformer gas contains hydrogen, the combustion efficiency in the combustion chamber 12 is good, and the exhaust fuel injection amount is corrected according to the humidity, thereby suppressing coking and improving fuel efficiency. Is done.

  Thus, in the control apparatus for an internal combustion engine of the first embodiment, the fuel reformer 24 that generates reformer gas by heating and reforming the mixed gas obtained by mixing the fuel with the exhaust gas, and the fuel A reflux passage 27 for supplying reformer gas generated by the reformer 24 to the intake pipe 15 is provided, and the ECU 30 changes the mixing ratio of fuel and exhaust gas based on the current humidity detected by the humidity sensor 35. Like to do.

  Therefore, in the fuel reformer 24, as the amount of water contained in the mixed gas increases, the reforming efficiency increases. Therefore, the fuel reformer 24 becomes an appropriate reformed state by increasing or decreasing the exhaust fuel injection amount in accordance with the humidity change of the exhaust gas. The occurrence of coking can be suppressed, and reformer gas generation efficiency can be improved to improve fuel efficiency.

  Also, the exhaust fuel injection amount is set based on the engine speed, the engine load, and the exhaust gas temperature. When the current humidity exceeds a preset predetermined humidity, the exhaust fuel injection is accompanied by the increase in the humidity. Try to increase the amount. Therefore, a minimum reformer gas amount can be secured by reforming a predetermined amount of fuel, and the amount of reformer gas generated is increased by increasing the exhaust fuel injection amount by the increased humidity. can do.

  In this embodiment, the humidity sensor 35 provided in the air-conditioning control device is applied as the humidity detecting means. However, the present invention is not limited to this, and for example, an exhaust gas having a good heat resistance is attached to the exhaust pipe 22. The humidity may be measured directly.

  FIG. 5 is a schematic configuration diagram showing an internal combustion engine control apparatus according to Embodiment 2 of the present invention, FIG. 6 is a flowchart showing reforming processing in the internal combustion engine control apparatus of Embodiment 2, and FIG. FIG. 8 is a control map showing a reforming region set by an engine speed and a load in the control apparatus for an internal combustion engine according to 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 control apparatus for an internal combustion engine according to the second embodiment, the ECU 30 sets the fuel reforming region based on the engine load (throttle opening) and the engine speed. Further, the ECU 30 sets the exhaust fuel injection amount injected by the second injector 29 and the opening degree of the reformer gas control valve 28 based on the engine speed, the engine load (throttle opening degree), and the exhaust gas temperature. Yes. Therefore, when the ECU 30 determines that the current operating state of the engine 11 is in the reforming region, the ECU 30 executes exhaust fuel injection by the second injector 29 to inject a predetermined amount of fuel, and the reformer gas control valve 28. Is opened at a predetermined angle, fuel reforming using the fuel reformer 24 is started, and a predetermined amount of reformer gas is supplied to the intake pipe 15.

In this embodiment, the reforming start timing by the fuel reformer 24 is corrected by the exhaust gas temperature. As shown in FIG. 7, the exhaust gas temperature at the outlet of the fuel reformer 24 is increased, has a higher hydrogen concentration in the reformer gas, in this case, the exhaust gas temperature t _s is the activity of the fuel reformer 24 Temperature. Therefore, in this embodiment, the fuel reforming region (fuel reforming start line) set based on the engine load and the engine speed is corrected based on the exhaust gas temperature. The fuel reforming start line is corrected to a low rotational speed and a low load side so that the quality start timing is advanced.

Here, as shown in FIG. 5, the three-way catalyst 23 is usually provided with a catalyst temperature sensor 41 that detects the catalyst temperature in order to determine the activation state and the deterioration state of the three-way catalyst 23. The catalyst temperature sensor 41 is applied to detect combustion. Further, an external air temperature sensor 42 provided in the air conditioning control device is applied as a device for detecting the surrounding environment. The catalyst temperature detected by the catalyst temperature sensor 41 and the outside air temperature detected by the outside air temperature sensor 42 are input to the ECU 30, and the ECU 30 estimates the exhaust gas temperature based on the catalyst temperature and the outside air temperature. as shown in FIG. 8, when the exhaust gas temperature estimated is lower than a predetermined value, the fuel reforming start line L _a is fuel reforming region (fuel reforming start line L) high speed and high load side When the estimated exhaust gas temperature is higher than a predetermined value, the fuel reforming region (fuel reforming start line L) is set to the fuel reforming start line L _b on the low rotation speed and low load side. to correct.

  Accordingly, when the catalyst temperature and the outside air temperature are high, it is determined that the temperature of the fuel reformer 24 is sufficiently high regardless of the engine speed and the engine load, and the fuel reforming start line L is rotated at a low speed. The fuel reforming region is expanded by shifting to the number and low load side.

  In this case, the exhaust gas temperature is estimated based on the catalyst temperature and the outside air temperature, but atmospheric pressure, humidity, or the like may be used as the surrounding environment instead of the outside air temperature. Further, an exhaust gas temperature sensor may be provided in the exhaust pipe 22 to directly detect the exhaust gas temperature.

  Here, the reforming process control by the control device for the internal combustion engine of the present embodiment described above will be described in detail based on the flowchart of FIG.

  In step S21, the engine speed, engine load (throttle opening), catalyst temperature, and outside air temperature are read. In step S22, the exhaust gas temperature is estimated based on the catalyst temperature and the outside air temperature, and the exhaust fuel injection amount is calculated based on the engine speed, the engine load, and the exhaust gas temperature. Subsequently, in step S23, the opening degree of the reformer gas control valve 28 is calculated based on the engine speed, the engine load (throttle opening degree), and the exhaust gas temperature.

  In step S24, the fuel reforming region (fuel reforming start line L) is corrected using the control map of FIG. 8 based on the exhaust gas temperature estimated based on the catalyst temperature and the outside air temperature. In step S25, it is determined from the engine load (throttle opening) and the engine speed based on the corrected fuel reforming region control map whether the current engine operating state is in the fuel reforming region. . In step S25, if the current engine operating state is not in the fuel reforming region, the routine exits without doing anything. On the other hand, if the current engine operating state is in the fuel reforming region, reforming processing is executed in step S26.

  That is, by performing exhaust fuel injection by the second injector 29 and opening the reformer gas control valve 28, first, a mixed gas in which fuel and exhaust gas are mixed is introduced into the fuel evaporator 25, and the mixed gas is discharged. Evaporation is promoted and vaporized, and then the vaporized mixed gas is introduced into the fuel reformer 24 and heated by the heat of the exhaust gas to cause an endothermic reaction, and a reformer containing hydrogen, carbon monoxide, and nitrogen Generate gas. The generated reformer gas is supplied to the intake air flowing through the intake pipe 15 after the supply amount is adjusted by the reformer gas control valve 28 through the reflux passage 27. Then, an air-fuel mixture in which intake air and reformer gas are mixed is introduced into the combustion chamber 12 and is combusted by being ignited by the air-fuel mixture.

  In this case, since the reformer gas contains hydrogen, the combustion efficiency in the combustion chamber 12 is good, and the fuel reforming region is corrected according to the exhaust gas temperature, so that the reforming region is appropriate. Thus, reforming efficiency is improved and fuel efficiency is improved.

  Thus, in the control apparatus for the internal combustion engine of the second embodiment, the fuel reformer 24 that generates reformer gas by heating and reforming the mixed gas obtained by mixing the fuel with the exhaust gas, and the fuel A recirculation passage 27 for supplying reformer gas generated by the reformer 24 to the intake pipe 15 is provided, and the ECU 30 estimates the exhaust gas temperature based on the catalyst temperature and the outside air temperature, and fuel according to the exhaust gas temperature. The modified region is corrected.

  Therefore, in the fuel reformer 24, the fuel reforming region is expanded or contracted in accordance with the temperature of the exhaust gas, so that an appropriate reforming state can be achieved, and the occurrence of coking can be suppressed, and reformer gas generation can be achieved. Efficiency can be improved and fuel consumption can be improved.

  Further, the exhaust gas temperature is estimated based on the catalyst temperature detected by the catalyst temperature sensor 41 which is an existing device and the outside air temperature detected by the outside air temperature sensor 42, and without providing an exhaust gas temperature sensor separately, The exhaust gas temperature can be obtained, and an increase in manufacturing cost can be prevented.

  In each of the embodiments described above, the gas containing oxygen is used as the exhaust gas of the engine 11. However, the present invention is not limited to this, and the reforming process may be performed after exhaust fuel is injected into the separately sucked outside air. . In each embodiment, the fuel reforming region is set based on the engine load and the engine speed, and the exhaust fuel injection amount and the reformer gas control valve 28 based on the engine speed, the engine load, and the exhaust gas temperature. However, the present invention is not limited to this, and the accelerator opening, fuel injection amount, intake air amount, volume efficiency, in-cylinder pressure, etc. may be applied. .

  In each embodiment, the internal combustion engine is a port injection type engine, but it may be an in-cylinder injection type engine in which fuel is directly injected into the combustion chamber. In this case, a lean addition to the three-way catalyst is added to the exhaust passage. It is necessary to provide a NOx catalyst.

  As described above, the control device for an internal combustion engine according to the present invention suppresses the occurrence of coking by changing the mixing ratio of the fuel and the exhaust gas based on the humidity, and has the fuel reforming means. Any internal combustion engine can be used for any type of internal combustion engine.

1 is a schematic configuration diagram illustrating a control device for an internal combustion engine according to Embodiment 1 of the present invention. 3 is a flowchart illustrating a reforming process in the control device for an internal combustion engine according to the first embodiment. 3 is a control map showing a reforming region set by an engine speed and a load in the control apparatus for an internal combustion engine according to the first embodiment. 3 is a control map showing an exhaust injection amount with respect to humidity in the control apparatus for an internal combustion engine according to the first embodiment. It is a schematic block diagram showing the control apparatus of the internal combustion engine which concerns on Example 2 of this invention. 6 is a flowchart showing a reforming process in a control device for an internal combustion engine according to a second embodiment. 6 is a graph showing a hydrogen concentration with respect to an exhaust gas temperature in the control device for an internal combustion engine of the second embodiment. 7 is a control map showing a reforming region set by an engine speed and a load in a control device for an internal combustion engine according to a second embodiment.

Explanation of symbols

11 Engine (Internal combustion engine)
DESCRIPTION OF SYMBOLS 12 Combustion chamber 13 Intake port 14 Exhaust port 15 Intake pipe 19 Electronic throttle device 20 1st injector 22 Exhaust pipe 23 Three way catalyst 24 Fuel reformer (fuel reforming means)
25 Fuel evaporator 27 Recirculation passage (reformer gas supply means)
28 Reformer gas control valve 29 Second injector 30 Electronic control unit, ECU (mixing ratio changing means)
32 Crank angle sensor 33 Accelerator opening sensor 34 Exhaust temperature sensor 35 Humidity sensor (humidity detection means)
41 Catalyst temperature sensor 42 Outside air temperature sensor

Claims (6)

  Fuel reforming means for generating reformer gas by heating and reforming a mixed gas comprising a gas containing fuel and oxygen, and the reformer gas generated by the fuel reforming means for the intake passage of the internal combustion engine A reformer gas supply means for supplying the humidity, a humidity detection means for detecting the humidity, and a mixing ratio changing means for changing the mixing ratio of the gas containing fuel and oxygen based on the detection result of the humidity detecting means. A control device for an internal combustion engine.   2. The control apparatus for an internal combustion engine according to claim 1, wherein the gas containing oxygen is an exhaust gas of the internal combustion engine, a fuel amount is set based on a rotation speed, a load, and an exhaust gas temperature of the internal combustion engine, and the mixing The control device for an internal combustion engine, characterized in that the ratio changing means increases the fuel amount as the humidity detected by the humidity detecting means increases.   3. The control apparatus for an internal combustion engine according to claim 2, wherein when the humidity detected by the humidity detection unit exceeds a preset reference value, the mixing ratio changing unit sets the fuel amount as the humidity increases. A control device for an internal combustion engine characterized by increasing.   2. The control apparatus for an internal combustion engine according to claim 1, wherein the gas containing oxygen is an exhaust gas of the internal combustion engine, and a reforming start time is set based on a rotation speed and a load of the internal combustion engine, and the reforming start is performed. A control device for an internal combustion engine, wherein the timing is corrected by an exhaust gas temperature.   5. The control apparatus for an internal combustion engine according to claim 4, wherein the reforming start timing is corrected so as to be advanced by an increase in the exhaust gas temperature. 6. The control apparatus for an internal combustion engine according to claim 4, wherein the exhaust gas temperature is estimated from an ambient environment and a combustion state of the internal combustion engine.

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