JP2007113420A - Control device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve fuel economy and exhaust emission characteristics and increase driveability by securing a stable combustion state irrespective of the reforming state of a fuel, in a control device of an internal combustion engine. <P>SOLUTION: If a catalyst temperature Tc detected by a temperature sensor 54 is not in an activating catalyst temperature area (T<SB>1</SB>>Tc>T<SB>2</SB>), a fuel reformer 34 determines that an electric system or a mechanical system causes a trouble. The fuel reformer starts to jet a first fuel by a first injector 27 to start an engine 11, and stops a second fuel jetting by a second injector 40. The fuel reformer also stops the supply of air through an intake pipe 39, and purges mixed gas remaining in the fuel reformer 34 from a connection pipe 49 to an intake pipe 24 utilizing an intake negative pressure. <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, generates a reformed gas by supplying a mixture of air and fuel to a reforming catalyst, and this reformed gas is supplied to an intake passage. The present invention relates to an apparatus for controlling a fuel reforming system to be supplied.

  Conventionally, fuel is injected into air introduced into a combustion chamber of an internal combustion engine, and a mixed gas of air and fuel is passed through a reforming catalyst so that the mixed gas undergoes a reforming reaction. A fuel reforming system for an internal combustion engine that generates reformed gas containing carbon monoxide and supplies the reformed gas to an intake system for combustion to increase the combustion efficiency of the internal combustion engine and improve fuel efficiency. Proposed.

  An example of such a fuel reforming system for an internal combustion engine is described in Patent Document 1 below. In the fuel reforming system for an internal combustion engine described in Patent Document 1, a throttle valve is provided in an intake pipe, a downstream side thereof is connected to a surge tank, and a bypass pipe is provided by branching from the intake pipe. The pipe is provided with a flow control valve and a reformer, the reformer has a reforming reaction section, a fuel injection valve is provided on the upstream side of the reformer, and the downstream side is connected to a surge tank. It has a structure. Therefore, when air is supplied to the reformer through the intake pipe and the bypass pipe, fuel is injected into the air to form a mixed gas, and this mixed gas becomes the reformed gas by the reformer. The quality gas and the air introduced through the intake pipe are mixed in the surge tank, whereby an air-fuel mixture having a predetermined air-fuel ratio is introduced, and this air-fuel mixture is introduced into the combustion chamber and combusted.

JP 2004-315320 A

  In the above-described conventional fuel reforming system for an internal combustion engine, air is supplied to the reformer through the intake pipe and the bypass pipe, and a predetermined amount of fuel is supplied to the air to form a mixed gas, This mixed gas is introduced into a reforming reaction section (reforming catalyst) of the reformer to generate a reformed gas. In the reforming reaction section of this reformer, the hydrocarbon-based fuel and air react with the reforming catalyst, so that a partial oxidation reaction proceeds and a reformed gas containing hydrogen and carbon monoxide as reforming components. However, in order to start a predetermined reaction, it is necessary to set the temperature of the reforming catalyst (catalyst temperature) of the reformer to a predetermined temperature or higher in advance.

  However, in this internal combustion engine fuel reforming system, if the fuel amount relative to the air amount increases or decreases from a predetermined amount due to an electrical system or mechanical failure, the air-fuel ratio of the mixed gas introduced into the reforming reaction section varies. As a result, the reforming catalyst cannot perform an appropriate reforming reaction. For example, when the amount of fuel is increased relative to the amount of air in the reforming reaction section of the reformer, the air-fuel ratio of the introduced mixed gas becomes lower than necessary, and all the fuel is reformed by the reforming catalyst. Unreformed fuel will be discharged without quality. In the case of a rich mixture, carbon accumulates on the surface of the reforming catalyst and inhibits the reforming reaction. As a result, a large amount of unreformed fuel is contained in the reformed gas, combustion of the internal combustion engine is deteriorated, and fuel consumption and exhaust gas characteristics are deteriorated.

On the other hand, if the amount of fuel is reduced relative to the amount of air in the reforming reaction section of the reformer, the air-fuel ratio of the introduced mixed gas becomes higher than necessary, and overheating of the reforming catalyst and reformed gas The CO ₂ concentration in the inside is high and the H ₂ concentration is low, which deteriorates the combustion of the internal combustion engine.

  The present invention is intended to solve these problems, and ensures a stable combustion state regardless of the reformed state of the fuel, thereby improving fuel consumption and exhaust gas characteristics and improving drivability. Another object of the present invention is to provide a control device for an internal combustion engine.

  In order to solve the above-described problems and achieve the object, a control device for an internal combustion engine of the present invention includes an intake passage for introducing outside air into a combustion chamber, and a first fuel that injects fuel into the intake passage or the combustion chamber. A fuel reforming means for generating a reformed gas by reforming a mixed gas composed of an injection means, a gas containing fuel and oxygen with a reforming catalyst, and a first fuel for injecting fuel to the fuel reforming means. 2 fuel injection means, gas supply means for supplying a gas containing oxygen to the fuel reforming means, and a reformed gas supply passage for supplying the reformed gas generated by the fuel reforming means to the intake passage And a fuel injection control means for switchingly controlling the first fuel injection means and the second fuel injection means in accordance with the operating state of the internal combustion engine, the reforming of the fuel reforming means Reforming operation status detection means for detecting operation status And the fuel injection control means starts fuel injection by the first fuel injection means when detecting an abnormality of the fuel reforming means based on the detection result of the reforming operation status detection means, (2) The fuel injection by the fuel injection means and the gas supply by the gas supply means are stopped, and the residual material remaining in the fuel reforming means is transferred from the reformed gas supply passage to the intake passage using intake negative pressure. It is characterized by purging.

  In the control apparatus for an internal combustion engine of the present invention, a heat exchanger is provided for exchanging heat between the gas supplied to the fuel reforming means by the gas supply means and the exhaust gas, and the fuel injection control means is configured to change the fuel. When an abnormality in the quality means is detected, the residual material remaining in the fuel reforming means is heated using the gas heated by the heat exchanger.

  In the control apparatus for an internal combustion engine of the present invention, a catalyst heating means for heating the fuel reforming means is provided, and when the fuel injection control means detects an abnormality of the fuel reforming means, the fuel reforming is performed by the catalyst heating means. The residual material is heated by heating the quality means.

In the control device for an internal combustion engine according to the present invention, the reforming operation state detecting means is a temperature sensor, a CO sensor, or an H ₂ sensor, and the fuel injection control means is a catalyst temperature or a CO concentration detected by each sensor or The fuel reforming means is determined to be abnormal when the H ₂ concentration is not within a preset appropriate range.

  According to the control apparatus for an internal combustion engine of the present invention, when an abnormality of the fuel reforming means is detected based on the reforming operation status of the fuel reforming means, the fuel to the intake passage or the combustion chamber by the first fuel injection means While the injection is started, the fuel injection to the fuel reforming means by the second fuel injection means is stopped, the gas supply by the gas supply means is stopped, and the residual substance remaining in the fuel reforming means is reduced to the intake negative pressure. Since the reformed gas supply passage is purged from the reformed gas supply passage to the intake passage, a predetermined amount of fuel can be supplied into the combustion chamber by fuel injection of the first fuel injection means, and a stable combustion state can be secured. The fuel injection and gas supply to the gas reforming means are stopped, and the mixed gas remaining in the fuel reforming means is purged into the intake passage by the negative intake pressure, thereby allowing unreformed fuel and reforming to the fuel reforming means. Gas residue It is possible to stop.

  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.

  1 is a schematic configuration diagram illustrating a control device for an internal combustion engine according to a first embodiment of the present invention, and FIGS. 2-1 and 2-2 are flowcharts illustrating reforming processing in the control device for the internal combustion engine according to the first embodiment. It is.

  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 a cylinder head 13 is fastened on a cylinder block 12. The pistons 15 are respectively fitted to the plurality of cylinder bores 14 so as to be movable up and down. A crankcase 16 is fastened to the lower part of the cylinder block 12, and a crankshaft 17 is rotatably supported in the crankcase 16. Each piston 15 is connected to the crankshaft 17 via a connecting rod 18. Has been.

  In the engine 11, a combustion chamber 19 is configured by the cylinder block 12, the cylinder head 13, and the piston 15, and the combustion chamber 19 is formed with an intake port 20 and an exhaust port 21 facing each other at an upper portion thereof. The intake port 20 and the exhaust port 21 can be opened and closed by an intake valve 22 and an exhaust valve 23. Therefore, when the camshaft (not shown) rotates, the intake valve 22 and the exhaust valve 23 move up and down at a predetermined timing, open and close the intake port 20 and the exhaust port 21, and the intake port 20, the combustion chamber 19, and the combustion chamber 19 And the exhaust port 21 can communicate with each other.

  The intake pipe (intake passage) 24 has an air cleaner 25 attached to an upstream end portion thereof, and a downstream end portion thereof connected to the intake port 20. An electronic throttle device 26 having a throttle valve is provided on the downstream side of the air cleaner 25. The cylinder head 13 is equipped with a first injector (first fuel injection means) 27 for injecting fuel into the intake port 20, and the first injector 27 is connected to a fuel pump 29 via a fuel supply pipe 28. And connected to the fuel tank 30. A spark plug 31 that ignites the air-fuel mixture in the combustion chamber 19 is attached to the lower surface of the cylinder head 13.

  On the other hand, an exhaust pipe 32 is connected to the exhaust port 21, and a three-way catalyst 33 is attached to the exhaust pipe 32. The three-way catalyst 33 can simultaneously purify harmful substances such as hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NOx) contained in the exhaust gas. When in the vicinity of the stoichiometric air-fuel ratio (stoichiometric), harmful substances in the exhaust gas can be purified.

  In the engine 11 of this embodiment, a fuel reformer is configured such that a mixture of air and fuel is supplied to a heated reforming catalyst to generate reformed gas, and the reformed gas is supplied to the intake passage. A fuel reforming system having a quality device is installed.

  That is, the fuel reformer (fuel reforming means) 34 has a reforming reaction part 36 formed by mounting a reforming catalyst in a cylindrical housing 35, and is adjacent to the reforming reaction part 36. In addition, an air-fuel mixing unit 37 is provided on the upstream side, and a reformed gas discharge unit 38 is provided on the downstream side adjacent to the reforming reaction unit 36. The downstream end of the intake pipe 39 is connected to the air / fuel mixing section 37 of the fuel reformer 34, and a second injector (second fuel) that injects fuel to the intake air introduced through the intake pipe 39. Injection means) 40 is provided, and is connected to the fuel pump 29 and the fuel tank 30 via the fuel supply pipe 28. The reforming catalyst provided in the reforming reaction section 36 has rhodium supported on zirconia, for example, as a noble metal for generating a reformed gas from a mixed gas of oxygen-containing air and fuel.

  Further, the fuel reformer 34 reacts with air and hydrocarbon fuel by a reforming catalyst, and a partial oxidation reaction proceeds, so that a reformed gas containing hydrogen and carbon monoxide as reforming components. In order to perform this reaction properly, the temperature (catalyst temperature) of the reforming reaction section 36 (reforming catalyst) is set to a predetermined temperature (for example, 400 ° C.) or higher in advance. It is necessary to keep. That is, since the reforming reaction using the partial oxidation reaction is an exothermic reaction, if an appropriate air-fuel mixture is continuously supplied, the temperature required for the reforming reaction (about 950 ° C.) is maintained by self-heating. However, since the reforming catalyst is at a normal temperature (atmospheric temperature) at the start of the reforming reaction, the reforming reaction does not occur even if an appropriate air-fuel mixture is supplied thereto. In order to cause the reforming reaction, the reforming catalyst needs to be set to a predetermined temperature (for example, 400 ° C.) or higher in advance. Therefore, the fuel reformer 34 is provided with a heater center electrode (catalyst heating means) 41 at the center of the reforming reaction section 36. A positive electrode 44 connected to the power supply unit 42 and the switch 43 is connected to the center electrode 41, and a negative electrode 45 is connected to the housing 35. In this case, by configuring the reforming catalyst with a metal honeycomb body, a current flows from the center electrode 45 to the metal honeycomb body and the housing 35, and the metal honeycomb body generates heat.

  In the fuel reformer 34, an air control valve 46 and an air pump 47 are attached to the intake pipe 39. A heat exchanger 48 attached to the exhaust pipe 32 is installed at the upstream end of the intake pipe 39. Is provided. On the other hand, an upstream end portion of a connection pipe 49 as a reformed gas supply passage is connected to the reformed gas discharge portion 38 of the fuel reformer 34, and a downstream end portion is a downstream side of the electronic throttle device 26 in the intake pipe 24. It is connected to. In this case, the gas supply means is constituted by the intake pipe 39, the air control valve 46 and the air pump 47.

  Therefore, when the fuel reformer 34 is stopped, external air is drawn into the intake pipe 24 from the air cleaner 25, and the amount of intake air is adjusted by the electronic throttle device 26, so that the intake air passing through the intake port 20 is reduced. The first injector 27 performs fuel injection (first fuel injection). Then, an air-fuel mixture in which intake air and fuel are mixed is introduced into the combustion chamber 19. In this combustion chamber 19, the ignition plug 31 ignites the air-fuel mixture and burns, and the exhaust gas is exhausted when the exhaust valve 23 is opened. The gas is discharged from the port 21 to the exhaust pipe 32.

  On the other hand, when the fuel reformer 34 is operated, the air pump 47 is operated and the air control valve 46 is opened, and the heat exchanger 48 exchanges heat with the exhaust gas so that the heated external air enters the intake pipe 39. The intake air amount is adjusted by the air control valve 46 and then supplied to the fuel reformer 34. The second injector 40 performs fuel injection (second fuel injection) on the intake air. Then, fuel and air are mixed in the air / fuel mixing section 37 to form a mixed gas, and this mixed gas is introduced into the reforming reaction section 36, where it undergoes a partial oxidation reaction with the reforming catalyst heated by energization. As a result, the reformed gas containing hydrogen and carbon monoxide, which is reformed, is generated as shown in the following formula 1.

C _m H _n + (m / 2) O ₂ → mCO + (n / 2) H ₂ (1)

  The reformed gas generated by the fuel reformer 34 is supplied from the reformed gas discharge unit 38 to the intake pipe 24 through the connection pipe 49, and the air-fuel mixture in which the intake air and the reformed gas are mixed enters the combustion chamber 19. In the combustion chamber 19, the ignition plug 31 ignites the air-fuel mixture and combusts. When the exhaust valve 23 is opened, the exhaust gas is discharged from the exhaust port 21 to the exhaust pipe 32. In this case, since the reformed gas contains reformed hydrogen and carbon monoxide, the combustion efficiency in the combustion chamber 19 is good, fuel efficiency can be improved, and the generation of Hc is suppressed and the exhaust gas is suppressed. Purification efficiency can be improved.

  Incidentally, an electronic control unit (ECU) 50 is mounted on the vehicle, and the ECU 50 controls the fuel injection amount, the injection timing, the ignition timing, and the like by drivingly controlling the first injector 27, the spark plug 31, and the like. It is possible. That is, an air flow sensor 51 is mounted on the upstream side of the intake pipe 24, and the measured intake air amount is output to the ECU 50. The electronic throttle device 26 has a throttle position sensor, and outputs the current throttle opening to the ECU 50. Further, the crank angle sensor 52 outputs the detected crank angle of each cylinder to the ECU 50, and the ECU 50 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. Further, an accelerator opening sensor 53 that detects the amount of depression of the accelerator pedal as an accelerator opening is provided, and the current accelerator opening is output to the ECU 50.

  Accordingly, the ECU 50 sets the first fuel injection amount, the injection timing, the ignition timing, and the like based on the detected operating air amount such as the intake air amount, throttle opening, accelerator opening, and engine speed.

  The ECU 50 can control the fuel reforming system by driving and controlling the second injector 40, the air control valve 46, and the like. That is, the reforming reaction section 36 in the fuel reformer 34 is provided with a temperature sensor 54 that detects the temperature of the reforming catalyst, and outputs the current reforming catalyst temperature (hereinafter referred to as catalyst temperature) to the ECU 50. is doing.

  Therefore, the ECU 50 sets the target torque of the engine 11 based on the accelerator opening, sets the amount of reformed air to be supplied to the fuel reformer 34 according to the target torque, and sets the fuel reformer set in advance. Based on the air-fuel ratio of the mixed gas at 34 (for example, A / F = 5.0), the second fuel injection amount for this reformed air amount is set, and the air-fuel ratio of the air-fuel mixture supplied to the combustion chamber 19 is The intake air amount with respect to the reformed gas is set so that the theoretical air-fuel ratio is obtained. Further, the ECU 50 operates the switch 43 based on the catalyst temperature detected by the temperature sensor 54 to heat the fuel reformer 34 by energizing the center electrode 41, thereby reforming the reforming reaction unit 36. Temperature control is performed so that the catalyst has a predetermined catalyst temperature (for example, 400 ° C. or higher).

  In the control device for the internal combustion engine of the present embodiment, the ECU 50 as the fuel injection control means can switch and control the first injector 27 and the second injector 40 according to the operating state of the engine 11, By stopping the first injector 27 and operating the fuel reformer 34 by using the second injector 40, the reformed gas generated by the fuel reformer 34 is supplied to the combustion chamber 19 and burned. The engine 11 is driven.

  By the way, in the control apparatus for an internal combustion engine having such a fuel reforming system, the second fuel injection amount relative to the reformed air amount supplied to the fuel reformer 34 when an electrical system or mechanical failure occurs is obtained. If it increases or decreases from the predetermined value, the air-fuel ratio of the mixed gas introduced into the reforming reaction section 36 varies, and the reforming catalyst cannot execute an appropriate reforming reaction. The content of carbon oxide is lowered and combustion efficiency and fuel consumption cannot be sufficiently improved, or a large amount of unreformed fuel is contained in the reformed gas, and combustion is deteriorated.

  Therefore, in this embodiment, when the ECU 50 detects an abnormality of the fuel reformer 34 due to an electrical system or a mechanical failure, the ECU 50 starts the first fuel injection by the first injector 27, while the second injector 40 And the supply of air through the intake pipe 39 is stopped, and the mixed gas or liquid fuel remaining in the fuel reformer 34 is taken from the connection pipe 49 to the intake pipe using the negative intake pressure. 24 is purged.

  That is, a temperature sensor 54 that detects the temperature of the reforming catalyst in the reforming reaction section 36 is applied as a reforming operation status detecting unit that detects the reforming operation status of the fuel reformer 34. Further, in order to purge the residual gas in the fuel reformer 34 from the connecting pipe 49 to the intake pipe 24, a bypass pipe 55 that supplies air to the fuel reformer 34 even when the fuel reformer 34 is not operating. Is provided in the intake pipe 39 so as to bypass the air control valve 46 and the air pump 47, and an air purge valve 56 is attached to the bypass pipe 55.

  In this case, the liquid fuel adhering to the reforming catalyst of the fuel reformer 34 is vaporized and then purged to the intake pipe 24 as a residual gas, so that a heat exchanger 48 provided in the exhaust pipe 32 is used. Air heated by the heat exchanger 48 is supplied into the fuel reformer 34 to purge residual gas such as fuel into the intake pipe 24.

  Here, the abnormal process control in the reforming process by the control apparatus for the internal combustion engine of the present embodiment described above will be described in detail based on the flowcharts of FIGS. 2-1 and 2-2. The reforming process control described below is a control at the time of starting the engine 11.

In the control apparatus for the internal combustion engine of the present embodiment, as shown in FIG. 2A, in step S11, the ECU 50 energizes the center electrode 41 by turning on the switch 43, thereby turning on the fuel reformer 34. In step S12, the temperature sensor 54 reads the reforming catalyst temperature Tc. In step S13, it is determined whether the catalyst temperature Tc is higher than a predetermined catalyst start temperature T ₀ (for example, 400 ° C.). If the catalyst temperature Tc becomes higher than the catalyst start temperature T ₀ in step S13, the ECU 50 turns off the switch 43 in step S14 to stop energization of the center electrode 41 and fuel. The preheating of the reforming catalyst in the reformer 34 is stopped.

  When the reforming catalyst of the fuel reformer 34 reaches a predetermined temperature, in step S15, the fuel pump 29 is driven and the air pump 47 is driven. In step S16, the second fuel injection is performed by the second injector 40. Then, the air control valve 46 is opened to supply air to the fuel reformer 34. Then, in the air / fuel mixing section 37 of the fuel reformer 34, the air introduced from the intake pipe 39 and the fuel injected from the second injector 40 are mixed to form a mixed gas, and this mixed gas is reformed. The mixed gas is reformed by being partially oxidized with the heated reforming catalyst, and a reformed gas containing reforming components hydrogen and carbon monoxide is generated. .

When the reforming process is started in the fuel reformer 34 in this way, the temperature of the catalyst is increased by the temperature rise due to the reaction heat in the reforming catalyst. In step S17, the ECU 50 reads the reforming catalyst temperature Tc by the temperature sensor 54, and in step S18, whether or not the catalyst temperature Tc is within a predetermined activation catalyst temperature range, for example, the catalyst temperature. It is determined whether Tc is in a region lower than an upper limit value T ₁ (for example, 1000 ° C.) and higher than a lower limit value T ₂ (for example, 800 ° C.). If the catalyst temperature Tc is within a predetermined activated catalyst temperature range (T ₁ >Tc> T ₂ ), the process returns to step S17 and the processes of steps S17 and S18 are repeated. Then, when the reformed gas generated by the fuel reformer 34 is supplied to the intake pipe 24 through the connecting pipe 49, an air-fuel mixture obtained by mixing the intake air and the reformed gas is introduced into the combustion chamber 19, and this combustion chamber At 19, the air-fuel mixture is ignited by the spark plug 31 to combust and the engine 11 is started.

On the other hand, if the catalyst temperature Tc is not in the predetermined activated catalyst temperature range (T ₁ >Tc> T ₂ ) in step S18 when the engine 11 is started, the ECU 50 detects an electric system or mechanical failure. For example, it is determined that the fuel reformer 34 is operating abnormally, and the process proceeds to step S19. Then, as shown in FIG. 2B, in step S19, the second fuel injection by the second injector 40 is stopped, the air control valve 46 is closed, and the supply of air by the intake pipe 39 is stopped. In step S20, the driving of the air pump 47 is stopped. In step S21, cranking of the engine 11 is started by a starter motor (not shown), and first fuel injection by the first injector 27 is started in step S22. Accordingly, fuel injection is performed by the first injector 27 with respect to the intake air introduced from the intake pipe 24 through the intake port 20 into the combustion chamber 19, and an air-fuel mixture in which intake air and fuel are mixed is introduced into the combustion chamber 19. In the combustion chamber 19, the ignition plug 31 ignites the air-fuel mixture and burns, and the engine 11 is started.

  In step S23, the ECU 50 confirms the start of the engine 11 when the engine speed Ne is equal to or higher than the predetermined speed Nes, and opens the air purge valve 56 in step S24. Then, the purge process is executed in step S25. That is, when the engine 11 is started, intake negative pressure is generated in the intake pipe 24, and this intake negative pressure acts on the fuel reformer 34 via the connecting pipe 49. Then, the air heated by the heat exchanger 48 due to the negative pressure acting on the fuel reformer 34 is introduced into the fuel reformer 34 from the intake pipe 39. By increasing the amount, when the liquid fuel adheres to the reforming catalyst of the reforming reaction section 36 and becomes a low temperature, the liquid fuel adhering to the reforming catalyst is vaporized by this heated air, and the residual gas As a result, the connection pipe 49 is purged to the intake pipe 24 by the intake negative pressure. On the other hand, in the fuel reformer 34, when the fuel amount is reduced with respect to the air amount, when abnormal combustion occurs and the temperature becomes high, the reforming that remains together with the air introduced into the fuel reformer 34 is performed. The quality gas is purged from the connecting pipe 49 to the intake pipe 24 by the intake negative pressure.

That is, when the temperature of the reforming reaction section 36 does not reach the activation temperature (for example, 400 ° C.) or more, or when the fuel amount is increased and the air-fuel ratio is excessive and oxygen is insufficient, the partial oxidation reaction is sufficiently performed. This is not done, and the unreformed fuel component increases. On the other hand, when the fuel amount is reduced and the air-fuel ratio is too thin and oxygen is excessive, the complete oxidation reaction proceeds, the concentration of CO ₂ in the reformed gas becomes high, and the reforming catalyst overheats. As described above, when the reforming reaction section 36 is lower than the activation temperature, when the air-fuel ratio is excessively rich or excessively thin, and when the catalyst is greatly deteriorated due to some cause and the reforming reaction is deteriorated, in any case Even so, the abnormality of the fuel reformer 34 can be detected by the catalyst temperature Tc, and the mixed gas or liquid fuel remaining in the fuel reformer 34 can be purged.

If mixed gas or liquid fuel remains in the fuel reformer 34, unreformed fuel or reformed gas with a large amount of CO ₂ is sucked into the engine at the next engine start, which makes starting difficult. If liquid fuel remains in the fuel reformer 34 in a state where the temperature of the reforming reaction portion 36 is low, the internal air-fuel ratio becomes excessive when the fuel reformer 34 is repaired, and the problem occurs again. Will cause. In the present embodiment, the abnormality of the fuel reformer 34 is reliably detected, and the mixed gas or liquid fuel remaining in the fuel reformer 34 is purged to the intake pipe 24 by the intake negative pressure, so that the fuel consumption and exhaust gas characteristics are increased. , Drivability can be improved.

Thereafter, the timer starts to operate in step S26, reads the elapsed time t ₁ by the timer, the elapsed time t ₁ at step S28 is After exceeds a predetermined time t ₀ at step S27, and closes the air purging valve 56 at step S29 To complete the purge process. Then, after resetting the timer in step S30, a lamp or warning sound is emitted as a warning alarm in step S31.

As described above, in the control apparatus for an internal combustion engine according to the first embodiment, the temperature of the reforming catalyst in the reforming reaction section is detected as reforming operation status detecting means for detecting the reforming operation status of the fuel reformer 34. If the catalyst temperature Tc detected by the temperature sensor 54 is not in the activated catalyst temperature range (T ₁ >Tc> T ₂ ), the fuel reformer 34 is in an electric system or mechanical failure. The first fuel injection by the first injector 27 is started and the engine 11 is started, while the second fuel injection by the second injector 40 is stopped and the supply of air through the intake pipe 39 is stopped. Then, the mixed gas remaining in the fuel reformer 34 is purged from the connecting pipe 49 to the intake pipe 24 using the intake negative pressure.

  Therefore, by supplying a predetermined amount of fuel into the combustion chamber 19 by the first fuel injection of the first injector 27, it is possible to ensure a stable combustion state and start the engine 11 reliably, while fuel reforming The fuel injection and air supply to the gas generator 34 are stopped, and the mixed gas remaining in the fuel reformer 34 is purged into the intake pipe 24 by the negative intake pressure, whereby the fuel reformer 34 is not reformed. Residual fuel and reformed gas can be prevented, and as a result, fuel consumption, exhaust gas characteristics, and drivability can be improved.

  The exhaust pipe 32 is provided with a heat exchanger 48 for exchanging heat between the gas supplied to the fuel reformer 34 and the exhaust gas, and the air heated by the heat exchanger 48 is supplied to the fuel reformer 34. The supplied mixed gas is purged. Accordingly, the liquid fuel adhering to the reforming catalyst of the fuel reformer 34 is vaporized by the heated air and then purged as residual gas into the intake pipe 24, so that residual gas such as fuel in the fuel reformer 34 is quickly removed. Can be reliably purged.

  Further, as a reforming operation status detecting means for detecting the reforming operation status of the fuel reformer 34, the temperature sensor 54 for detecting the temperature of the reforming catalyst is applied, so that the abnormality of the fuel reformer 34 is appropriately controlled. Can be determined.

  FIGS. 3A and 3B are flowcharts illustrating the reforming process in the control device for the internal combustion engine according to the second embodiment of the present invention. In addition, since the whole structure in the control apparatus of the internal combustion engine of Example 2 is the same as that of Example 1, while using FIG. 1, it demonstrates to the member which has the function similar to what was demonstrated in Example 1. The same reference numerals are used and duplicate descriptions are omitted.

  In the control apparatus for an internal combustion engine according to the second embodiment, when an abnormality of the fuel reformer 34 due to an electrical system or a mechanical failure is detected, the first fuel injection by the first injector 27 is started, while the second injector 40 is started. And the supply of air through the intake pipe 39 is stopped, and the mixed gas remaining in the fuel reformer 34 is purged from the connecting pipe 49 to the intake pipe 24 using the intake negative pressure. However, at this time, by heating the reforming catalyst of the reforming reaction section 36 in the fuel reformer 34, if liquid fuel adheres to the reforming catalyst, this is surely vaporized early. Can be purged.

  Here, the abnormal process control in the reforming process by the control apparatus for the internal combustion engine of the present embodiment described above will be described in detail based on the flowcharts of FIGS. 3-1 and 3-2. The reforming process control described below is a control at the time of starting the engine 11.

In the control apparatus for an internal combustion engine of the present embodiment, as shown in FIG. 3A, in step S51, the ECU 50 turns on the switch 43 to energize the center electrode 41, thereby causing the fuel reforming reaction section 36. The reforming catalyst is preheated by heating and the reforming catalyst temperature Tc is read by the temperature sensor 54 in step S52. In step S53, to determine whether the catalyst Zhuang temperature Tc is higher than a predetermined catalyst starting Zhuang temperature T ₀ which is set in advance, when the catalyst Zhuang temperature Tc is higher than the catalyst starting Sho temperature T _0, in step S54, The preheating of the reforming catalyst of the fuel reformer 34 is stopped by turning off the switch 43 to stop energization of the center electrode 41.

  When the reforming catalyst of the fuel reformer 34 reaches a predetermined temperature, in step S55, the fuel pump 29 is driven and the air pump 47 is driven. In step S56, the second injector 40 performs the second fuel injection. Then, the air control valve 46 is opened to supply air to the fuel reformer 34. Then, the air introduced from the intake pipe 39 in the air / fuel mixing section 37 of the fuel reformer 34 and the fuel injected from the second injector 40 are mixed to form a mixed gas, which is reformed. The mixed gas is reformed by being introduced into the reaction section 36 and undergoing a partial oxidation reaction with the heated reforming catalyst, and a reformed gas containing hydrogen and carbon monoxide, which is the reforming composition, is generated.

When the reforming process is started in the fuel reformer 34 in this way, the catalyst temperature rises due to the reaction heat in the reforming catalyst, and in step S57, the reforming catalyst temperature Tc is read by the temperature sensor 54, and the step In S58, it is determined whether or not the catalyst temperature Tc is within a predetermined activation catalyst temperature range (T ₁ >Tc> T ₂ ) set in advance. If the catalyst temperature Tc is within a predetermined activated catalyst temperature range (T ₁ >Tc> T ₂ ), the process returns to step S57 and is repeated. During this time, the reformed gas generated by the fuel reformer 34 is supplied to the intake pipe 24 through the connecting pipe 49, and the air-fuel mixture in which the intake air and the reformed gas are mixed is introduced into the combustion chamber 19 and mixed by the spark plug 31. The engine 11 is started by igniting and burning.

On the other hand, if the catalyst temperature Tc is not in the predetermined activated catalyst temperature range (T ₁ >Tc> T ₂ ) in step S58 when the engine 11 is started, the ECU 50 detects an electric system or mechanical failure. For example, it is determined that the fuel reformer 34 is operating abnormally, and the process proceeds to step S59. As shown in FIG. 3-2, in step S59, the second fuel injection by the second injector 40 is stopped and the air control valve 46 is closed to stop the supply of air from the intake pipe 39. In step S60, the driving of the air pump 47 is stopped. In step S61, cranking of the engine 11 is started, and in step S62, first fuel injection by the first injector 27 is started. Accordingly, fuel injection is performed by the first injector 27 with respect to the intake air introduced from the intake pipe 24 through the intake port 20 into the combustion chamber 19, and an air-fuel mixture in which intake air and fuel are mixed is introduced into the combustion chamber 19. The ignition plug 31 ignites the air-fuel mixture and burns, and the engine 11 is started.

  In step S63, the ECU 50 confirms the start of the engine 11 when the engine speed Ne is equal to or higher than the predetermined speed Nes, opens the air purge valve 56 in step S64, and resets the timer in step S65. Then, in step S66, the switch 43 is turned on to energize the center electrode 41, thereby starting the heating of the fuel reformer 34. In step S67, the purge process is executed.

  That is, when the engine 11 is started, intake negative pressure is generated in the intake pipe 24, and this intake negative pressure acts on the fuel reformer 34 via the connecting pipe 49. Then, air is sucked into the fuel reformer 34 from the intake pipe 39 by the negative pressure acting on the fuel reformer 34. At this time, the fuel amount is reduced with respect to the air amount, and the fuel reformer 34 is When abnormal combustion occurs and the temperature rises, the reformed gas remaining together with the air introduced into the fuel reformer 34 is purged from the connecting pipe 49 to the intake pipe 24 by the intake negative pressure. On the other hand, when the fuel amount is increased with respect to the air amount in the fuel reformer 34, the liquid fuel adheres to the reforming catalyst of the reforming reaction section 36 and becomes low temperature. Since the fuel reformer 34 is heated by energizing the electrode 41, the liquid fuel adhering to the high-temperature reforming catalyst is vaporized and purged from the connecting pipe 49 to the intake pipe 24 by the negative intake pressure as residual gas. Is done.

Then, beyond the purge process is started in step S67, the timer starts to operate in step S68, reads the elapsed time t ₁ by the timer at step S69, the elapsed time t ₁ at step S70 is a predetermined time t ₀ Then, in step S71, the switch 43 is turned OFF to stop energization of the center electrode 41, thereby stopping the heating of the fuel reformer 34. In step S72, the air purge valve 46 is closed to end the purge process. In step S73, a lamp or warning sound is emitted as an alarm alarm.

Thus, in the control apparatus for an internal combustion engine of the second embodiment, the catalyst temperature Tc detected by the temperature sensor 54 of the fuel reformer 34 is in the activated catalyst temperature range (T ₁ >Tc> T ₂ ). Otherwise, the fuel reformer 34 determines that there is an abnormality due to an electrical system or a mechanical failure, and starts the first fuel injection by the first injector 27 and starts the engine 11, while starting the second fuel injection by the second injector 40. After stopping the fuel injection and stopping the supply of air through the intake pipe 39, the air purge valve 56 is opened, the reforming catalyst is heated by the center electrode 41, and the mixed gas remaining in the fuel reformer 34 is The intake pipe 24 is purged using the intake negative pressure.

  Accordingly, by heating the reforming catalyst of the fuel reformer 34 by the center electrode 41, the adhering liquid fuel can be vaporized, and the air is introduced into the interior by the intake negative pressure, and the fuel reformer The mixed gas and vaporized gas remaining in 34 can be reliably purged, and unreformed fuel and reformed gas remaining in the fuel reformer 34 can be prevented.

In the second embodiment, the air purge valve 56 is opened and the central electrode 41 is energized, and after a predetermined time t _{0 has} elapsed since the purge process is started, the energization of the center electrode 41 is stopped and the air purge valve 45 is energized. However, the purge process may be terminated by monitoring the temperature of the reforming catalyst of the fuel reformer 34 using the temperature sensor 54.

  Further, in each embodiment, the fuel reformer 34 is determined to be abnormal when the catalyst temperature of the fuel reformer 34 is not in the preset appropriate temperature range. A case where the catalyst temperature deviates to the high temperature region side and a case where the catalyst temperature deviates to the low temperature region side are discriminated, and different processing may be performed in each abnormal situation. For example, when the catalyst temperature of the fuel reformer 34 deviates to the high temperature region side, low temperature air is introduced into the fuel reformer 34 and the internal gas is purged while cooling. On the other hand, when the catalyst temperature of the fuel reformer 34 deviates to the low temperature region side, air heated by the heat exchanger 48 is sent to the fuel reformer 34 or the fuel reformer 34 is heated. Thus, the adhering liquid fuel is vaporized and purged.

In each of the above-described embodiments, the temperature sensor 54 is used as the reforming operation status detection means for detecting the reforming operation status of the fuel reformer 34, and the catalyst temperature of the fuel reformer 34 is preset. The fuel reformer 34 is determined to be abnormal when it is not in the appropriate temperature range, but a CO sensor or an H ₂ sensor is used in place of the temperature sensor 54 as the reforming operation status detection means, and the fuel reforming detected by each sensor. The fuel reformer 34 may be determined to be abnormal when the CO concentration or the H ₂ concentration in the vessel 34 is not within a preset appropriate concentration range.

  In each of the embodiments described above, the internal combustion engine is a port injection type engine, but it may be a cylinder injection type engine that directly injects fuel into the combustion chamber. In this case, a three-way catalyst is added to the exhaust passage. It is necessary to provide a lean NOx catalyst.

  As described above, the control device for an internal combustion engine according to the present invention starts fuel injection into the intake passage or the combustion chamber when the fuel reforming means is abnormal, while fuel injection and gas into the fuel reforming means. Any type of internal combustion engine having the fuel reforming means is configured to stop the supply and purge the mixed gas remaining in the fuel reforming means to the intake passage using the intake negative pressure. It is also suitable for use in other internal combustion engines.

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 flowchart illustrating a reforming process in the control device for an internal combustion engine according to the first embodiment. It is a flowchart showing the reforming process in the control apparatus of the internal combustion engine which concerns on Example 2 of this invention. It is a flowchart showing the reforming process in the control apparatus of the internal combustion engine which concerns on Example 2 of this invention.

Explanation of symbols

11 Engine (Internal combustion engine)
19 Combustion chamber 20 Intake port 21 Exhaust port 24 Intake pipe (intake passage)
26 Electronic throttle device 27 First injector (first fuel injection means)
29 Fuel pump 31 Spark plug 32 Exhaust pipe 33 Three-way catalyst 34 Fuel reformer (fuel reforming means)
39 Intake pipe (gas supply means)
40 Second injector (second fuel injection means)
41 Heater center electrode (catalyst heating means)
46 Air control valve (gas supply means)
47 Air pump (gas supply means)
48 Heat exchanger 49 Connecting pipe (reformed gas supply passage)
50 Electronic control unit, ECU (fuel injection control means)
54 Temperature sensor (reforming operation status detection means)
55 Bypass pipe 56 Air purge valve

Claims (4)

  Reforming a mixed gas comprising an intake passage for introducing outside air into the combustion chamber, first fuel injection means for injecting fuel into the intake passage or the combustion chamber, and a gas containing fuel and oxygen with a reforming catalyst The fuel reforming means for generating the reformed gas in the fuel, the second fuel injection means for injecting the fuel to the fuel reforming means, and the gas supply means for supplying the gas containing oxygen to the fuel reforming means A reformed gas supply passage for supplying the reformed gas generated by the fuel reforming means to the intake passage, and the first fuel injection means and the second fuel injection means according to the operating state of the internal combustion engine. In a control apparatus for an internal combustion engine comprising a fuel injection control means for switching control, a reforming operation status detection means for detecting a reforming operation status of the fuel reforming means is provided, and the fuel injection control means Based on the detection result of the operation status detection means When an abnormality is detected in the fuel reforming means, fuel injection by the first fuel injection means is started, while fuel injection by the second fuel injection means and gas supply by the gas supply means are stopped, and the fuel A control apparatus for an internal combustion engine, wherein residual substances remaining in the reforming means are purged from the reformed gas supply passage to the intake passage using intake negative pressure.   2. The control apparatus for an internal combustion engine according to claim 1, further comprising a heat exchanger for exchanging heat between the gas supplied to the fuel reforming unit and the exhaust gas by the gas supply unit, and the fuel injection control unit A control apparatus for an internal combustion engine, wherein when an abnormality of the fuel reforming means is detected, a residual material remaining in the fuel reforming means is heated using a gas heated by the heat exchanger.   2. The control apparatus for an internal combustion engine according to claim 1, further comprising a catalyst heating means for heating the fuel reforming means, and when the fuel injection control means detects an abnormality in the fuel reforming means, the catalyst heating means A control apparatus for an internal combustion engine, wherein the remaining material is heated by heating the fuel reforming means. 2. The control device for an internal combustion engine according to claim 1, wherein the reforming operation state detection means is a temperature sensor, a CO sensor, or an H ₂ sensor, and the fuel injection control means includes a catalyst temperature detected by each sensor or A control apparatus for an internal combustion engine, characterized in that the fuel reforming means is determined to be abnormal when the CO concentration or H ₂ concentration is not within a preset appropriate range.

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