JP2006052662A - Internal combustion engine and its operation method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an internal combustion engine and its operating method which are capable of preventing reformed fuel surely from remaining in a reforming device or the like while limiting the cost increase and a deterioration in efficiency of the use of the space. <P>SOLUTION: The internal combustion engine 1 generates motive energy by combusting an air-fuel mixture of the reformed fuel and air within a combustion chamber 3. For this purpose, the internal combustion engine 1 is equipped with the reforming device 20 for reforming a mixture of a hydrocarbon-based fuel and the air to produce the reformed fuel containing CO and H<SB>2</SB>, a bypass pipe L2 for introducing the air into the reforming device 20, a reformed fuel feeding pipe L3 for introducing the reformed fuel from the reforming device 20 to each combustion chamber 3, and an ECU 30 for stopping fuel feed to the reforming device 20 when an engine halting command has been issued and then stopping ignition of the air-fuel mixture after having carried out the ignition of the air-fuel mixture in each combustion chamber 3 during a predetermined period. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an internal combustion engine having a reformer that reforms an air-fuel mixture of fuel and air to generate reformed fuel, and an operating method thereof.

Conventionally, an internal combustion engine having an alcohol reformer that reforms an alcohol fuel such as methanol to obtain CO and H ₂ (reformed fuel) is known. In this type of internal combustion engine, the catalyst bed temperature of the reformer changes to some extent for a while after the reformer is stopped to stop the engine. Therefore, methanol and the like remaining in the reformer after it is stopped may be reformed to generate CO and H _2, but the reformed fuel generated before and after the stop of the internal combustion engine Remaining in the reformer or the downstream passage is not preferable from the viewpoint of preventing deterioration of piping due to hydrogen embrittlement, for example. For this reason, conventionally, in order to prevent the CO and H ₂ generated before and after the engine is stopped from remaining in the reformer or the like, the reformed fuel is passed through the passage connecting the reformer and the intake pipe. 2. Description of the Related Art An internal combustion engine configured to suck and the like in a tank is known (for example, see Patent Document 1).

JP-A-8-291774

  However, as described above, if an internal combustion engine is provided with a pump for recovering reformed fuel or the like from a passage connecting the reformer and the intake pipe, or a tank for storing the recovered reformed fuel or the like, the cost increases. In addition, deterioration of space efficiency (vehicle mountability) cannot be avoided.

  Therefore, the present invention aims to provide an internal combustion engine and an operation method thereof that can reliably suppress the reformed fuel remaining in the reformer and the like while suppressing an increase in cost and a deterioration in space efficiency. And

  An internal combustion engine according to the present invention has a reformer that reforms a mixture of fuel and air to generate a reformed fuel containing a predetermined fuel component, and the mixture of the reformed fuel and air is converted into a combustion chamber. In an internal combustion engine that generates power by burning in, a reformed air passage for introducing air into the reformer, a reformed fuel passage for introducing reformed fuel from the reformer into the combustion chamber, and an engine Control means for stopping the fuel supply to the reformer when the stop command is issued, and then continuing the ignition of the air-fuel mixture in the combustion chamber for a predetermined time and then stopping the ignition of the air-fuel mixture It is characterized by.

  In this internal combustion engine, when an engine stop command is issued, the fuel supply to the reformer is stopped, and thereafter, the ignition of the air-fuel mixture in the combustion chamber, that is, the combustion of the air-fuel mixture in the combustion chamber (piston reciprocating operation) Is continued for a predetermined time. As a result, the reformed fuel (residual reformed fuel) remaining in the reformer, the reformed fuel passage or the like is sucked into the combustion chamber together with the air from the reformed air passage and burned in the combustion chamber. It will be. Therefore, in this internal combustion engine, a reformer, a reformed fuel passage, etc. can be used without using a pump for recovering the reformed fuel from the reformed fuel passage or the like, or a tank for storing the recovered reformed fuel. Therefore, the residual reformed fuel can be substantially eliminated. As a result, according to the internal combustion engine, it is possible to reliably suppress the reformed fuel remaining in the reformer, the reformed fuel passage, and the like while suppressing an increase in cost and a deterioration in space efficiency. Become.

  In this case, the internal combustion engine according to the present invention is provided in the reformed air passage, further includes reformed air supply means for supplying air to the reformer, and the control means stops fuel supply to the reformer. After that, it is preferable to operate the reforming air supply means until the ignition of the air-fuel mixture is stopped.

  If such a configuration is adopted, the reformed fuel remaining in the reforming device, the reformed fuel passage or the like is purged by the air supplied by the reformed air supply means, and the remaining reformed fuel is purged in the combustion chamber. It becomes possible to secure sufficient air necessary for combustion.

  An internal combustion engine according to the present invention is provided in a reformed air passage, and includes a reformed air supply means for supplying air to the reformer and an exhaust purification catalyst for purifying exhaust gas from the combustion chamber. Further, the control means may be one for operating the reformed air supply means for a predetermined time after stopping the ignition of the air-fuel mixture.

  In general, when the ignition of the air-fuel mixture is stopped and the internal combustion engine is stopped (when the reciprocation of the piston stops with the stop of ignition of the air-fuel mixture), the intake valve and the exhaust valve are both opened (over There is a combustion chamber in a lap state. Accordingly, after the ignition of the air-fuel mixture is stopped, the reformed air supply means is operated for a predetermined time, thereby supplying the reformed air through the combustion chamber in which both the intake valve and the exhaust valve are opened. The reformed fuel remaining in the reformer, the reformed fuel passage or the like can be sent to the exhaust purification catalyst by the air from the means. Since the exhaust purification catalyst is sufficiently warmed up immediately after the engine is stopped, the residual reformed fuel is well purified by the exhaust purification catalyst together with the air from the reformed air supply means. As a result, by adopting such a configuration, it is possible to extremely reliably prevent the reformed fuel from remaining in the reformer, the reformed fuel passage, and the like.

  Further, the internal combustion engine according to the present invention further includes a cranking means for cranking the internal combustion engine, and the control means stops the fuel supply to the reformer and then the engine speed falls below a predetermined value. In addition, the cranking means may be operated for a predetermined time before the ignition of the air-fuel mixture is stopped.

  Generally, the amount of reformed fuel produced after the fuel supply to the reformer is stopped is smaller than the reformed fuel produced during normal operation of the reformer. For this reason, after the fuel supply to the reformer is stopped as described above, the combustion state in the combustion chamber becomes unstable, and the reformed fuel (residual reforming) remaining in the reformer, the reformed fuel passage, or the like. There is also a risk that the quality fuel) cannot be satisfactorily sucked into the combustion chamber. On the other hand, as in this internal combustion engine, after stopping the fuel supply to the reformer, if the cranking means is operated when the engine speed falls below a predetermined value, the operation of the internal combustion engine (piston The reciprocating operation) can be stably continued, and the residual reformed fuel can be satisfactorily sucked into the combustion chamber. During this time, the residual reformed fuel can be combusted in the combustion chamber by continuing the ignition of the air-fuel mixture. Therefore, even if such a configuration is adopted, it is possible to extremely reliably prevent the reformed fuel from remaining in the reformer, the reformed fuel passage, and the like.

  The internal combustion engine according to the present invention further includes a cranking means for cranking the internal combustion engine, and the control means stops the fuel supply to the reformer and then the engine speed falls below a predetermined value. Alternatively, the ignition of the air-fuel mixture may be stopped, and then the cranking means may be operated for a predetermined time.

  Thus, the operation of the internal combustion engine (piston is performed by operating the cranking means for a predetermined time after the ignition of the air-fuel mixture is stopped (after the reciprocation of the piston is stopped in accordance with the stop of ignition of the air-fuel mixture). Reciprocating operation), the residual reformed fuel is sucked into the combustion chamber in which the intake valve is open during the intake stroke, and the residual reformed fuel is sent from the combustion chamber to the exhaust purification catalyst during the exhaust stroke. It becomes possible. Then, the residual reformed fuel sent to the exhaust purification catalyst is well purified by the exhaust purification catalyst. Therefore, even if such a configuration is adopted, it is possible to extremely reliably prevent the reformed fuel from remaining in the reformer, the reformed fuel passage, and the like.

  Another internal combustion engine according to the present invention has a reformer that reforms an air-fuel mixture of fuel and air to generate a reformed fuel containing a predetermined fuel component. In an internal combustion engine that generates power by burning in a combustion chamber, a reformed air passage for introducing air into the reformer and a reformer that is provided in the reformed air passage and supplies air to the reformer Air supply means, a reformed fuel passage for introducing reformed fuel from the reformer into the combustion chamber, an exhaust purification catalyst for purifying exhaust gas from the combustion chamber, and a branch from the reformed fuel passage A branch passage connecting the reformer and the exhaust purification catalyst, communication between the reformer and the combustion chamber via the reformed fuel passage, and communication between the reformer and the exhaust purification catalyst via the branch passage. Switching means capable of switching between and the fuel supply to the reformer according to the engine stop command And a control means for controlling the switching means to allow communication between the reforming device and the exhaust purification catalyst via the branch passage and operating the reformed air supply means for a predetermined time after the engine is stopped. It is characterized by.

  In this internal combustion engine, when the engine stop command is issued, the fuel supply to the reformer is stopped and the operation is further stopped. Thereafter, communication between the reformer and the exhaust purification catalyst via the branch passage is allowed, and the reformed air supply means is operated for a predetermined time. As a result, the reformed fuel remaining in the reformer, the reformed fuel passage or the like is sent (purged) to the exhaust purification catalyst through the branch passage by the air from the reformed air supply means. Since the exhaust purification catalyst is sufficiently warmed up immediately after the engine is stopped, the residual reformed fuel is well purified by the exhaust purification catalyst together with the air from the reformed air supply means. Therefore, also in this internal combustion engine, the reformer and the reformed fuel passage are not used without using a pump for recovering the reformed fuel or the like from the reformed fuel passage or the like, or a tank for storing the recovered reformed fuel. Thus, the residual reformed fuel can be substantially eliminated. As a result, according to the internal combustion engine, it is possible to reliably suppress the reformed fuel remaining in the reformer, the reformed fuel passage, and the like while suppressing an increase in cost and a deterioration in space efficiency. Become.

  An operation method of an internal combustion engine according to the present invention includes a reformer that reforms a mixture of fuel and air to generate a reformed fuel containing a predetermined fuel component, and includes a mixture of reformed fuel and air. In the method of operating an internal combustion engine that generates power by burning the fuel in the combustion chamber, when the engine stop command is issued, the fuel supply to the reformer is stopped, and then the ignition of the air-fuel mixture in the combustion chamber is performed for a predetermined time. In this case, at least the reformed fuel remaining in the reformer is sent to the combustion chamber for combustion, and then the ignition of the air-fuel mixture is stopped.

  Another internal combustion engine operating method according to the present invention includes a reforming device that reforms an air-fuel mixture of fuel and air to generate a reformed fuel containing a predetermined fuel component. In an operation method of an internal combustion engine that generates power by combusting an air-fuel mixture in a combustion chamber, the fuel supply to the reformer is stopped in response to the engine stop command, and the reformer that supplies air to the reformer after the engine stops By operating the air supply means for a predetermined time, at least the reformed fuel remaining in the reformer is sent to an exhaust purification catalyst for purifying exhaust gas from the combustion chamber.

  According to the present invention, it is possible to realize an internal combustion engine and an operation method thereof that can reliably suppress remaining reformed fuel in a reformer or the like while suppressing cost increase and space efficiency deterioration. It becomes.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings.

[First Embodiment]
FIG. 1 is a schematic configuration diagram showing a first embodiment of an internal combustion engine according to the present invention. The internal combustion engine 1 shown in the figure is preferably used as a driving source for driving a vehicle, for example. The internal combustion engine 1 generates power by burning an air-fuel mixture containing a fuel component inside a combustion chamber 3 formed in the cylinder block 2 and reciprocating a piston 4 in the combustion chamber 3. Although only one cylinder is shown in FIG. 1, the internal combustion engine 1 of the present embodiment is configured as a multi-cylinder engine (for example, a four-cylinder engine).

  An intake port of each combustion chamber 3 is connected to an intake pipe constituting the intake manifold 5. On the other hand, the exhaust port of each combustion chamber 3 is connected to an exhaust pipe constituting an exhaust manifold 6, and the exhaust manifold 6 is connected to an exhaust purification device 7 including an exhaust purification catalyst. In addition, an intake valve Vi that opens and closes an intake port and an exhaust valve Ve that opens and closes an exhaust port are provided for each combustion chamber 3 in the cylinder head of the internal combustion engine 1. Each intake valve Vi and each exhaust valve Ve are opened and closed by a valve operating mechanism (not shown) having a variable valve timing function, for example. Furthermore, a spark plug 8 is provided for each combustion chamber 3 in the cylinder head of the internal combustion engine 1.

  As shown in FIG. 1, the intake manifold 5 is connected to the supply pipe L1 via a surge tank (not shown). These intake manifolds 5 (each intake pipe), a surge tank (not shown), and an air supply pipe L1 constitute an intake system of the internal combustion engine 1. The air supply pipe L1 is connected to an air intake (not shown) via an air cleaner (not shown), and a throttle valve (in this embodiment, an electronic device) is provided in the middle of the air supply pipe L1 (between the surge tank and the air cleaner). Controlled throttle valve) 9 is incorporated. Further, a bypass pipe (reformed air passage) L2 is branched from the supply pipe L1 at a branch portion BP defined on the upstream side of the throttle valve 9. The bypass pipe L2 includes an air pump (reformed air supply means) 10 and a flow rate adjusting valve 11 in this order from the branching part BP side in the middle, and its tip (an end opposite to the end on the branching part BP side). Is connected to the reformer 20.

  The reformer 20 has a substantially cylindrical main body 21 whose both ends are closed, and an air-fuel mixture supply unit 22 to which the above-described bypass pipe L2 is connected is provided at one end of the main body 21. In addition to the bypass pipe L2, the reforming fuel injection valve 12 is connected to the air-fuel mixture supply unit 22. The reforming fuel injection valve 12 is connected to a fuel tank (not shown) via a fuel supply pipe and a fuel pump (not shown), and mixes hydrocarbon-based fuel such as gasoline when the reformer 20 is used. The air is injected into the air supply unit 22. A water injection valve 14 is connected to the air-fuel mixture supply unit 22. The water injection valve 14 is connected to a water tank (not shown) via a water supply pipe and a water pump (not shown), and injects (sprays) water from the water tank into the air-fuel mixture supply unit 22. To do.

  In the present embodiment, the tip of the bypass pipe L2 and the water injection valve 14 are arranged so as to blow air or water from the side to the nozzle of the reforming fuel injection valve 12. Therefore, the reforming fuel injection valve 12 is opened to inject fuel, and the air pump 10 is operated with the flow rate adjustment valve 11 opened, and the water injection valve 14 is opened to inject water. Then, fuel, air, and water (air mixture) are injected from the spray port (not shown) of the air supply unit 22.

  On the other hand, a reforming reaction unit 23 including a predetermined reforming catalyst is provided in the main body 21 of the reformer 20 at a predetermined interval from the air-fuel mixture supply unit 22. And a reforming reaction section 23, a mixing chamber 24 communicating with the spray port of the mixture supply section 22 is defined. In the present embodiment, the reforming reaction unit 23 is configured by disposing a honeycomb material carrying a predetermined reforming catalyst inside the main body 21. As the reforming catalyst, for example, a catalyst in which rhodium is supported on zirconia can be employed. The mixing chamber 24 is provided with a preheater (not shown) for warming up (preheating) the interior of the reforming reaction section 23 and the mixing chamber 24.

  Further, a reformed fuel supply chamber 25 is defined in the main body 21 on the downstream side of the reforming reaction section 23. A base end of a reformed fuel supply pipe (reformed fuel passage) L3 for connecting the reformer 20 and each combustion chamber 3 is connected to the reformed fuel supply chamber 25. A front end side of the reformed fuel supply pipe L3 is branched toward each combustion chamber 3, and a reformed fuel supply nozzle (not shown) is attached to each front end portion of the reformed fuel supply pipe L3. And each reformed fuel supply nozzle is arrange | positioned in the intake port vicinity of the corresponding combustion chamber 3, for example.

  A plurality of reformed fuel supply pipes may be provided for each combustion chamber 3 so as to communicate each reformed fuel supply nozzle and the reformed fuel supply chamber 25 individually. Although not shown, the internal combustion engine 1 has a normal fuel injection valve provided in each intake port, and the state in which the reforming device 20 is operated or the air to the reforming device 20 and It is possible to obtain power by injecting a hydrocarbon fuel (normal fuel) such as gasoline into each intake port from each normal fuel injection valve with the fuel supply stopped. Note that the normal fuel injection valve may directly inject normal fuel into the corresponding combustion chamber 3.

  As shown in FIG. 1, the internal combustion engine 1 configured as described above includes an electronic control unit (hereinafter referred to as “ECU”) 30 that functions as its control means. The ECU 30 includes a CPU, a ROM, a RAM, an input / output port, a storage device, etc., all not shown. The input / output port of the ECU 30 includes the above-described valve operating mechanism, spark plug 8, air pump 10, flow rate adjusting valve 11, reforming fuel injection valve 12, water injection valve 14, normal fuel injection valve, preheater, A starter (cranking means) 15 such as a cell motor for cranking the internal combustion engine 1 is electrically connected.

  Various sensors such as an accelerator position sensor 31 and a crank angle sensor 32 are connected to the input / output port of the ECU 30. The accelerator position sensor 31 gives a signal indicating the depression amount of an accelerator pedal (not shown) to the ECU 30, and the crank angle sensor 32 gives a signal showing the crank angle of the internal combustion engine 1 to the ECU 30. In addition, a timer 33 is connected to the input / output port of the ECU 30 to measure time from that stage when the ECU 30 is activated. The ECU 30 is based on the measured values of various sensors and timers 33, and in accordance with various control programs, maps, etc., the valve operating mechanism, the spark plug 8, the air pump 10, the flow rate adjusting valve 11, the reforming fuel injection valve 12, the water injection. The valve 14, the normal fuel injection valve, the preheater, the starter 15 and the like are controlled.

When the internal combustion engine 1 described above is operated under predetermined conditions such as when the engine is started or when the load is low, for example, the ECU 30 performs mixing supplied to the reforming reaction unit 23 in response to a request for the reforming device 20. (In this embodiment, the air / fuel ratio of the gas is a substantially constant value. For example, the ratio of oxygen atoms in the air to carbon atoms in the fuel supplied to the mixing chamber 24 is O / C. Is set in a range of approximately 0.8 to 1.05.), The air pump 10, the flow rate adjusting valve 11, the reforming fuel injection valve 12, and the water injection valve 14 are controlled. As a result, fuel, air, and water (air mixture) in an amount corresponding to the request for the reformer 20 are injected into the mixing chamber 24 from the spray port of the air supply unit 22. The fine droplets of fuel and water injected from the air-fuel mixture supply unit 22 are vaporized inside the mixing chamber 24, whereby the fuel, air, and water (water vapor) air-fuel mixture that are uniformly mixed are mixed into the mixing chamber. The flow proceeds to the reforming reaction section 23 while proceeding through 24. In the reforming reaction section 23, the hydrocarbon-based fuel and air are reacted by the reforming catalyst, and the partial oxidation reaction represented by the following formula (1) and the steam reforming represented by the formula (2) are performed. As the quality reaction proceeds, reformed fuel (reformed gas) containing CO and H ₂ is generated.

The reformed fuel obtained as described above flows into the reformed fuel supply chamber 25 from the reforming reaction section 23, and continues to each combustion chamber 3 from the reformed fuel supply chamber 25 via the reformed fuel supply pipe L3. It will be supplied to the intake port. Air is introduced into the intake port of each combustion chamber 3 through the throttle valve 9 of the supply pipe L1 whose opening is adjusted by the ECU 30. Therefore, the reformed gas introduced from the reformer 20 to each intake port is further mixed with air and then sucked into each combustion chamber 3. When each spark plug 8 is ignited at a predetermined timing, the fuel components CO and H ₂ burn in each combustion chamber 3 to cause the piston 4 to reciprocate. Power can be obtained.

By the way, when the internal combustion engine 1 is operated using the reformed fuel generated by the reformer 20 as described above, the reformer is stopped for a while after the reformer is stopped to stop the engine. The catalyst bed temperature in the reforming reaction section 23 of the apparatus 20 changes to some extent. Therefore, methanol and the like remaining in the reformer 20 after the stop may be reformed to generate CO and H _2, but the reformers generated before and after the stop of the internal combustion engine 1 are generated. It is not preferable that the fuel remains in the reforming device 20 or the reformed fuel supply pipe L3 on the downstream side from the viewpoint of preventing deterioration of piping or the like due to hydrogen embrittlement, for example. For this reason, in the internal combustion engine 1 of the present embodiment, when the reformer 20 (fuel reforming) is stopped in order to stop the internal combustion engine 1, the reformed fuel is supplied to the reformer 20 and the reformed fuel supply pipe L3. 2 is executed by the ECU 30 as the control means in order to suppress the remaining.

  In this case, when an engine stop command indicating that the internal combustion engine 1 should be stopped is issued during operation of the internal combustion engine 1 (S10), the ECU 30 closes the reforming fuel injection valve 12 to thereby reform the fuel. The fuel supply to the device 20 is stopped (S12). At the stage where the process of S12 is executed, only the fuel supply from the reforming fuel injection valve 12 is stopped, the air supply from the air pump 10 or the like to the reforming device 20 via the bypass pipe L2, the water injection valve 14 from The water supply (injection) and the ignition operation of the air-fuel mixture by each spark plug 8 are continued.

  After stopping the fuel supply to the reformer 20 in S12, the ECU 30 sets the opening degree of the flow rate adjusting valve 11 of the bypass pipe L2 to a predetermined opening degree (S14). When the opening degree of the flow rate adjusting valve 11 is set to a predetermined opening degree, the ECU 30 acquires the rotational speed (engine speed) Ne of the internal combustion engine 1 based on the signal from the crank angle sensor 32 (S16). It is determined whether the engine speed Ne is zero (S18). The ECU 30 repeatedly executes the processes of S16 and S18 until it is determined that the engine speed Ne has become zero.

  When the ECU 30 determines that the engine speed Ne has become zero in S18, the ECU 30 stops the air pump 10 to stop the supply of air to the reformer 20 (S20). Further, after the process of S20 or almost simultaneously with it, the ECU 30 closes the water injection valve 14 to stop the supply of water to the reformer 20 (S22). Further, the ECU 30 stops the ignition operation of the air-fuel mixture by each ignition plug 8 in each combustion chamber 3 after the processing of S24 or substantially simultaneously (S24), and ends this routine.

  As described above, in the internal combustion engine 1, when the engine stop command is issued, only the fuel supply to the reformer 20 is stopped in S12, and then the modification by the air pump 10 or the like is performed until the process of S24 is executed. The air-fuel mixture ignition operation by the spark plug 8 in each combustion chamber 3, that is, the reciprocating operation of the piston 4 by the combustion of the air-fuel mixture in each combustion chamber 3 is continued for a predetermined time together with the supply of air to the quality device 20. become. As a result, the reformed fuel (residual reformed fuel) remaining in the reforming reaction section 23, the reformed fuel supply chamber 25 and the reformed fuel supply pipe L3 of the reformer 20 is passed through the bypass pipe L2 by the air pump 10. Together with the air supplied to the reformer 20 through the intake stroke, the air-fuel mixture of the residual reformed fuel and air is ignited by the spark plug 8 in each combustion chamber 3. Will be burned.

  Therefore, in the internal combustion engine 1, the reforming of the reforming device 20 can be performed without using a pump for recovering the reformed fuel from the reformed fuel supply pipe L3 or the like, a tank for storing the recovered reformed fuel, or the like. Residual reformed fuel can be substantially eliminated from the inside of the reaction section 23, the reformed fuel supply chamber 25 and the reformed fuel supply pipe L3. As a result, according to the internal combustion engine 1, it is possible to reliably suppress the reformed fuel from remaining in the reformer 20 and the reformed fuel supply pipe L3 while suppressing an increase in cost and a deterioration in space efficiency. This makes it possible to favorably avoid deterioration due to hydrogen embrittlement of the reformed fuel supply pipe L3.

  Further, under the routine of FIG. 2, as described above, the fuel supply to the reformer 20 is stopped in S12 and the ignition of the air-fuel mixture by each spark plug 8 is stopped in S24. Meanwhile, the operation of the air pump 10 is continued. Thus, the reformed fuel remaining in the reforming reaction section 23, the reformed fuel supply chamber 25 and the reformed fuel supply pipe L3 of the reformer 20 by the air pumped to the reformer 20 by the air pump 10. , And sufficient air can be secured to burn the remaining reformed fuel inside each combustion chamber 3.

  Depending on the capacity of the reforming reaction section 23, the reformed fuel supply chamber 25 and the reformed fuel supply pipe L3 of the reformer 20, the fuel supply to the reformer 20 is stopped in S12, and then in S24. Until the ignition of the air-fuel mixture by each spark plug 8 is stopped, the reciprocating operation of the piston 4 due to the combustion of the air-fuel mixture in each combustion chamber 3 remains in the reformer 20 and the reformed fuel supply pipe L3. It is possible that almost all of the reformed fuel is sucked into each combustion chamber 3. In such a case, the reciprocating operation of the piston 4 by the combustion of the air-fuel mixture in each combustion chamber 3 can sufficiently secure the air necessary for burning the residual reformed fuel in each combustion chamber 3. There is. Therefore, in such a case, the air pump 10 may be stopped simultaneously with stopping the fuel supply to the reformer 20 in S12 or at a predetermined timing from S12 to S24.

  Similarly, the supply of water from the water injection valve 14 to the reformer 20 is also performed at the same time as stopping the fuel supply to the reformer 20 in S12, or at a predetermined timing between S12 and S24. The air pump 10 may be stopped. However, after the supply of fuel to the reformer 20 is stopped in S12, the catalyst bed temperature in the reforming reaction section 23 may rise excessively. Accordingly, as in this embodiment, after the fuel supply to the reformer 20 is stopped, the water supply from the water injection valve 14 to the reformer 20 is continued for a while, and the reformer 20 (reforming reaction) is continued. Part 23) is preferably cooled.

  FIG. 3 shows that in the internal combustion engine 1 of FIG. 1, when the reformer 20 is stopped to stop the engine, the reformed fuel remains in the reformer 20 and the reformed fuel supply pipe L3. FIG. 6 is a flowchart illustrating another routine that may be executed to suppress.

  Even when the ECU 30 issues an engine stop command indicating that the internal combustion engine 1 should be stopped during the operation of the internal combustion engine 1 even under the routine of FIG. 3 (S30), the reforming fuel injection valve 12 is closed. As a result, the fuel supply to the reformer 20 is stopped (S32). Even at the stage where the process of S32 is executed, the supply of air to the reformer 20, the supply of water from the water injection valve 14, and the ignition operation of the air-fuel mixture by each spark plug 8 are continued. After stopping the fuel supply to the reformer 20 in S32, the ECU 30 sets the opening degree of the flow rate adjusting valve 11 of the bypass pipe L2 to a predetermined opening degree (S34).

Furthermore, ECU 30, based on a signal from the crank angle sensor 32 acquires the engine rotational speed Ne (S36), determines whether the acquired engine rotational speed Ne is below the threshold value _{N 0} to the predetermined (S38 ). ECU30 is the engine speed Ne is repeatedly executes the processing of S36 and S38 until it is determined that less than the threshold value _{N 0.} Then, ECU 30 is an engine speed Ne at S38 is determines that falls below the threshold value _{N 0,} it stops the ignition operation of the air-fuel mixture by the spark plug 8 in each combustion chamber 3 (S40).

Thus, even when the routine of FIG. 3 is executed in the internal combustion engine 1 described above, when the engine stop command is issued, only the fuel supply to the reformer 20 is stopped in S32, and then in S38. Until it is determined that the engine speed Ne has fallen below the threshold value N ₀ , the reciprocating operation of the piston 4 by the combustion of the air-fuel mixture in each combustion chamber 3 is performed for a predetermined time together with the supply of air to the reformer 20 by the air pump 10 or the like. Will continue. As a result, the reformed fuel (residual reformed fuel) remaining in the reforming reaction section 23, the reformed fuel supply chamber 25 and the reformed fuel supply pipe L3 of the reformer 20 is passed through the bypass pipe L2 by the air pump 10. Together with the air supplied to the reformer 20 through the intake stroke, the air-fuel mixture of the residual reformed fuel and air is ignited by the spark plug 8 in each combustion chamber 3. Will be burned.

On the other hand, if the engine speed Ne is determined to have fallen below the threshold value N ₀ in S38, good residual reformed fuel into the combustion chamber 3 by the reciprocating movement of the piston 4 by the combustion of the mixture in each combustion chamber 3 In this case, the ignition operation of the air-fuel mixture by each ignition plug 8 in each combustion chamber 3 is stopped (S40). Thereby, the operation of the internal combustion engine 1, that is, the reciprocating operation of the piston 4 is stopped in a very short time after the process of S40.

  Here, when the ignition of the air-fuel mixture by each spark plug 8 is stopped and the internal combustion engine 1 is stopped (when the reciprocating operation of the piston 4 is stopped in accordance with the stop of ignition of the air-fuel mixture), at least one of the combustions In the chamber 3, both the intake valve Vi and the exhaust valve Ve are opened (overlapping state). Therefore, even after the ignition of the air-fuel mixture is stopped in S40, the intake valve Vi and the exhaust valve Ve are both opened by operating the air pump 10 as the reformed air supply means for a predetermined time. The reformed fuel remaining in the reforming reaction section 23, the reformed fuel supply chamber 25 and the reformed fuel supply pipe L3 of the reformer 20 is exhausted and purified by the air from the air pump 10 through the combustion chamber 3 It can be fed into the device 7. Then, immediately after the internal combustion engine 1 is stopped, the exhaust purification catalyst of the exhaust purification device 7 is sufficiently warmed up, so the residual reformed fuel sent to the exhaust purification device 7 together with the air from the air pump 10 The exhaust gas purification catalyst will perform a good purification treatment.

ECU30 will start, after resetting the timer 33, if the ignition operation of the air-fuel mixture by each spark plug 8 is stopped in S40 (S42). As a result, the timer 33 starts measuring the elapsed time t since activation, and the ECU 30 reads the elapsed time t measured by the timer 33 (S44). Then, ECU 30 determines whether the elapsed time t measured by the timer 33 exceeds the reference time _{t 0} which is predetermined (S46). The reference time t ₀ is determined in accordance with the volume of the reforming reaction unit 23 and the reforming fuel supply chamber 25 and the reforming fuel supply pipe L3 of the reformer 20, in this embodiment, the elapsed time t is the reference time t _If it exceeds ₀ , it is considered that the remaining reformed fuel has disappeared from the reformer 20 and the reformed fuel supply pipe L3.

S46 at the elapsed time t measured by the timer 33 is determined to exceeds the reference time t ₀ which is determined in advance, ECU 30, by stopping the air pump 10 to stop the supply of air to the reformer 20 At the same time, the water injection valve 14 is closed to stop the supply of water to the reformer 20 (S48), and this routine is terminated. As described above, after the ignition of the air-fuel mixture by each spark plug 8 is stopped in S40, the reformed fuel is supplied to the reformer 20 and the reformed fuel supply pipe L3 by further operating the air pump 10 for a predetermined time. It is possible to very reliably suppress the remaining of the remaining, and it is possible to favorably avoid deterioration due to hydrogen embrittlement of the reformed fuel supply pipe L3.

  4 shows that the reformed fuel remains in the reformer 20 and the reformed fuel supply pipe L3 when the reformer 20 is stopped to stop the engine in the internal combustion engine 1 of FIG. FIG. 10 is a flowchart illustrating yet another routine that may be executed to suppress.

Even under the routine of FIG. 4, the ECU 30 closes the reforming fuel injection valve 12 when an engine stop command indicating that the internal combustion engine 1 should be stopped is issued during the operation of the internal combustion engine 1 (S50). As a result, the fuel supply to the reformer 20 is stopped (S52). Even at the stage where the process of S52 is executed, the supply of air to the reformer 20, the supply of water from the water injection valve 14, and the ignition operation of the air-fuel mixture by each spark plug 8 are continued. After stopping the fuel supply to the reformer 20 in S52, the ECU 30 sets the opening degree of the flow rate adjusting valve 11 of the bypass pipe L2 to a predetermined opening degree (S54). Furthermore, ECU 30 obtains the engine speed Ne based on a signal from the crank angle sensor 32 (S56), determines whether the acquired engine rotational speed Ne falls below the threshold _{N 1} the predetermined (S58 ).

ECU30 is the engine speed Ne is repeatedly executes the processing step S56 and S58 until it is determined that less than the threshold value _{N 1.} While the ECU 30 repeatedly executes the processes of S56 and S58, only the fuel supply to the reformer 20 is stopped, and the air-fuel mixture in each combustion chamber 3 is supplied together with the supply of air to the reformer 20 by the air pump 10 or the like. The reciprocating motion of the piston 4 due to the combustion of is continued for a predetermined time. Accordingly, the reformed fuel (residual reformed fuel) remaining in the reforming reaction section 23, the reformed fuel supply chamber 25 and the reformed fuel supply pipe L3 of the reformer 20 is passed through the bypass pipe L2 by the air pump 10. Together with the air supplied to the reformer 20, the air is sucked into each combustion chamber 3 during the intake stroke, and the mixture of residual reformed fuel and air is ignited by the spark plug 8 in each combustion chamber 3. Will burn.

However, in general, the amount of reformed fuel generated after the fuel supply to the reformer 20 is stopped is smaller than the reformed fuel generated during normal operation of the reformer 20. For this reason, after the fuel supply to the reformer 20 is stopped in S52, the combustion state in each combustion chamber 3 tends to become unstable gradually, and accordingly, the engine speed is set to the threshold value N _1. If it is less than the range, the reformed fuel remaining in the reformer 20 and the reformed fuel supply pipe L3 may not be satisfactorily sucked into each combustion chamber 3.

Therefore, in the routine of FIG. 4, ECU 30, after stopping the fuel supply to the reformer 20 at S52, the engine rotational speed Ne is determined to lower than the threshold _{N 1} at S58, the internal combustion engine 1 Run cranking. Thereby, the operation of the internal combustion engine 1, that is, the reciprocating operation of the piston 4 in each combustion chamber 3 can be stably continued, so that the reforming reaction section 23 and the reformed fuel supply chamber 25 of the reformer 20 The reformed fuel remaining in the reformed fuel supply pipe L3 can be satisfactorily sucked into each combustion chamber 3. During this time, by continuing to ignite the air-fuel mixture by each spark plug 8, the air-fuel mixture of residual reformed fuel and air is ignited and combusted by the spark plug 8 in each combustion chamber 3.

ECU30, when the engine speed Ne at S58 is determined to lower than the threshold _{N 1,} the timer 33 on resetting (S60), to start the starter 15 as cranking means (S62). Further, the ECU 30 starts the timer 33 almost simultaneously with the start of the starter 15 (S64). Thereby, the timer 33 starts measuring the elapsed time t after activation, and the ECU 30 reads the elapsed time t measured by the timer 33 (S66). Then, ECU 30 determines whether the elapsed time t measured by the timer 33 exceeds the reference time _{t 1,} which is predetermined (S68). The reference time t ₁ is determined according to the volumes of the reforming reaction section 23, the reformed fuel supply chamber 25, and the reformed fuel supply pipe L3 of the reformer 20, and in the present embodiment, the elapsed time t is the reference time t. _If it exceeds ₁ , it is considered that the residual reformed fuel has disappeared from the reformer 20 and the reformed fuel supply pipe L3.

When the elapsed time t measured by the timer 33 is determined to exceeds the reference time t _1, which is predetermined at S68, ECU 30, by stopping the starter 15, to stop the cranking of the internal combustion engine 1 (S70 ). Thereafter, the ECU 30 stops the air pump 10, closes the water injection valve 14, stops ignition of the air-fuel mixture by each spark plug 8 (S 72), and ends this routine. Thus, while after stopping the fuel supply to the reformer 20 at S52, when the engine speed Ne falls below a predetermined threshold N _1, until stopping the ignition of the mixture at S72, Even if the cranking of the internal combustion engine 1 is executed, it is possible to extremely reliably prevent the reformed fuel from remaining in the reforming device 20 and the reformed fuel supply pipe L3. The risk of deterioration due to hydrogen embrittlement of L3 can be avoided very well.

  When the routine of FIG. 4 is executed, the reformed fuel (residual reformed fuel) remaining in the reformer 20 and the reformed fuel supply pipe L3 is removed from each combustion chamber 3 by the cranking of the internal combustion engine 1. If the required air can be sufficiently secured, the fuel supply to the reformer 20 is stopped at S52, or at a predetermined time from S52 to S72. The air pump 10 may be stopped at the timing. In the hybrid power unit configured by combining the internal combustion engine 1 and the electric motor, motoring for rotating the crankshaft of the internal combustion engine 1 by the electric motor may be executed instead of the cranking of the internal combustion engine 1. .

  FIG. 5 shows that the reformed fuel remains in the reformer 20 and the reformed fuel supply pipe L3 when the reformer 20 is stopped to stop the engine in the internal combustion engine 1 of FIG. FIG. 6 is a flowchart illustrating another routine that may be executed to suppress.

  Even under the routine of FIG. 5, the ECU 30 closes the reforming fuel injection valve 12 when an engine stop command is issued indicating that the internal combustion engine 1 should be stopped during the operation of the internal combustion engine 1 (S100). As a result, the fuel supply to the reformer 20 is stopped (S102). Also in this case, the air supply to the reformer 20, the water supply from the water injection valve 14, and the air-fuel mixture ignition operation by each spark plug 8 are continued. After stopping the fuel supply to the reformer 20 in S102, the ECU 30 sets the opening degree of the flow rate adjustment valve 11 of the bypass pipe L2 to a predetermined opening degree (S104).

Furthermore, ECU 30 obtains the engine speed Ne based on a signal from the crank angle sensor 32 (S106), and determines whether the obtained engine speed Ne falls below the threshold _{N 2} the predetermined (S108 ). ECU30 is the engine speed Ne is repeatedly executes the processing of S106 and S108 until it is determined that less than the threshold value _{N 2.} Then, ECU 30 is an engine speed Ne at S108 is determines that falls below the threshold value _{N 2,} it stops the ignition operation of the air-fuel mixture by the spark plug 8 in each combustion chamber 3 (S110).

Accordingly, even when the routine of FIG. 5 is executed in the internal combustion engine 1 described above, when the engine stop command is issued, only the fuel supply to the reformer 20 is stopped in S102, and then in S108. until the engine speed Ne is determined to have fallen below the threshold value N _2, the supply of air to the reformer 20 by the air pump 10 or the like, reciprocating movement of the piston 4 by the combustion of the mixture in each combustion chamber 3 for a predetermined time Will continue. As a result, the reformed fuel (residual reformed fuel) remaining in the reforming reaction section 23, the reformed fuel supply chamber 25 and the reformed fuel supply pipe L3 of the reformer 20 is passed through the bypass pipe L2 by the air pump 10. Together with the air supplied to the reformer 20 through the intake stroke, the air-fuel mixture of the residual reformed fuel and air is ignited by the spark plug 8 in each combustion chamber 3. Will be burned.

On the other hand, if the engine speed Ne is determined to have fallen below the threshold value N ₂ at S108, good residual reformed fuel into the combustion chamber 3 by the reciprocating movement of the piston 4 by the combustion of the mixture in each combustion chamber 3 In this case, the ignition operation of the air-fuel mixture by each ignition plug 8 in each combustion chamber 3 is stopped (S110). Thereby, the operation of the internal combustion engine 1, that is, the reciprocating operation of the piston 4 is stopped in a very short time after the process of S100.

  The operation of the internal combustion engine 1 is performed by performing cranking of the internal combustion engine 1 after the ignition of the air-fuel mixture is stopped in S110 (after the reciprocation of the piston 4 is stopped in accordance with the stop of ignition of the air-fuel mixture). That is, the reciprocating operation of the piston 4 sucks the residual reformed fuel into the combustion chamber 3 in which the intake valve Vi is open during the intake stroke, and exhausts the residual reformed fuel from the combustion chamber 3 during the exhaust stroke. It can be sent to the purification device 7. Then, the residual reformed fuel sent to the exhaust purification device 7 is well purified by the exhaust purification catalyst that is still sufficiently warmed up.

When the ECU 30 stops the ignition operation of the air-fuel mixture by the spark plugs 8 in S110, the ECU 30 resets the timer 33 (S112) and starts the starter 15 as the cranking means (S114). Further, the ECU 30 starts the timer 33 almost simultaneously with the start of the starter 15 (S116). As a result, the timer 33 starts measuring the elapsed time t since activation, and the ECU 30 reads the elapsed time t measured by the timer 33 (S118). Then, ECU 30 determines whether the elapsed time t measured by the timer 33 exceeds the reference time _{t 2} which is predetermined (S120). Reference time t ₂ is also determined according to the volume of the reforming reaction unit 23 and the reforming fuel supply chamber 25 and the reforming fuel supply pipe L3 of the reformer 20, in this embodiment, the elapsed time t is the reference time t _If it exceeds ₂ , it is considered that the residual reformed fuel has disappeared from the reformer 20 and the reformed fuel supply pipe L3.

When the elapsed time t measured by the timer 33 is determined to exceeds the reference time _{t 2} which is predetermined at S120, ECU 30, by stopping the starter 15, to stop the cranking of the internal combustion engine 1 (S122 ). Thereafter, the ECU 30 stops the air pump 10 and closes the water injection valve 14 (S124), and ends this routine. Thus, after stopping the fuel supply to the reformer 20 at S102, when the engine speed Ne falls below a predetermined threshold N _2, to stop the ignition of the mixture by the spark plug 8, then Even if the cranking of the internal combustion engine 1 is executed for a predetermined time, it is possible to extremely reliably prevent the reformed fuel from remaining in the reformer 20 and the reformed fuel supply pipe L3. The possibility of deterioration due to hydrogen embrittlement of the quality fuel supply pipe L3 can be avoided very well.

[Second Embodiment]
Hereinafter, a second embodiment of the internal combustion engine according to the present invention will be described with reference to FIGS. 6 and 7. The same elements as those described in relation to the first embodiment described above are denoted by the same reference numerals, and redundant description is omitted.

  The internal combustion engine 1 </ b> A shown in FIG. 6 is also used as a driving source for vehicle travel, and a mixture of reformed fuel and air generated by the reformer 20 is burned in the combustion chamber 3. The power can be generated by reciprocating the piston 4 in the combustion chamber 3. The internal combustion engine 1A of FIG. 6 basically has the same configuration as the internal combustion engine 1 according to the first embodiment described above, but in the internal combustion engine 1A, switching is performed by the ECU 30 in the middle of the reformed fuel supply pipe L3. A controlled three-way valve 16 is incorporated.

  That is, the first port of the three-way valve 16 communicates with the reformed fuel supply chamber 25 of the reformer 20, and the second port of the three-way valve 16 communicates with each reformed fuel supply nozzle. . One end of a branch pipe (branch passage) L4 is connected to the third port of the three-way valve 16. That is, the branch pipe L4 is branched from the middle of the reformed fuel supply pipe L3 via the three-way valve 16, and the tip of the branch pipe L4 is an exhaust purification device 7 for purifying the exhaust gas from the combustion chamber 3. Connected to the inlet (exhaust pipe).

  As a result, when the three-way valve 16 is switched to the reformed fuel supply nozzle side, that is, the intake side, the reformed fuel generated by the reformer 20 passes through the three-way valve 16 and each reformed fuel supply nozzle to each combustion chamber. 3 will be supplied. In addition, when the three-way valve 16 is switched to the branch pipe L4 side, that is, the exhaust side, the reformer 20 passes through a part of the reformed fuel supply pipe L3, the branch pipe L4, and the like to the exhaust system of the internal combustion engine 1, that is, the exhaust gas. It communicates with the purification device 7. The three-way valve 16 is basically set to the reformed fuel supply nozzle side, that is, the intake side during normal operation of the internal combustion engine 1.

  FIG. 7 shows that in the internal combustion engine 1A of FIG. 6, when the reformer 20 is stopped to stop the engine, the reformed fuel remains in the reformer 20 and the reformed fuel supply pipe L3. It is a flowchart which shows the routine performed in order to suppress. In this case, when an engine stop command indicating that the internal combustion engine 1 should be stopped is issued during the operation of the internal combustion engine 1, the ECU 30 closes the reforming fuel injection valve 12, stops the air pump 10, and further Then, the supply of the air-fuel mixture to the reformer 20 is stopped by closing the water injection valve 14, thereby stopping the fuel reforming in the reformer 20 (S200). Further, the ECU 30 stops the operation of the internal combustion engine 1 by stopping the ignition operation of the air-fuel mixture by the ignition plug 8 in each combustion chamber 3 (S202).

  After stopping the operation of the internal combustion engine 1 in S202, the ECU 30 sets the opening degree of the flow rate adjustment valve 11 of the bypass pipe L2 to a predetermined opening degree (S204) and the three-way valve 16 of the reformed fuel supply pipe L3. Is switched from the intake side to the exhaust side, and the communication between the reforming device 20 and the exhaust purification device 7 via the branch pipe L4 is permitted (S206). When the process of S206 is executed, the ECU 30 resets the timer 33 (S208), and then starts the air pump 10 again (S210). As a result, a predetermined amount of air (only) is supplied to the reformer 20, and the air supplied to the reformer 20 passes through the reforming reaction section 23 and the reformed fuel supply chamber 25. Furthermore, it flows into the exhaust purification device 7 via a part of the reformed fuel supply pipe L3 and the branch pipe L4.

Further, the ECU 30 activates the timer 33 almost simultaneously with the activation of the air pump 10 (S212). Thereby, the timer 33 starts measuring the elapsed time t after activation, and the ECU 30 reads the elapsed time t measured by the timer 33 (S214). Then, ECU 30 determines whether or not exceeded the reference time _{t X} which elapsed time t measured by the timer 33 is determined in advance (S216). Reference time t _X is defined in accordance with the volume of such reforming reaction unit 23 and the reforming fuel supply chamber 25 of the reformer 20, in the present embodiment, when the elapsed time t exceeds the reference time t _X, Kai It is considered that the residual reformed fuel has disappeared from the quality device 20 and the reformed fuel supply pipe L3. When the elapsed time t measured by the timer 33 is determined to exceeds the reference time _{t X} which is predetermined at S216, ECU 30 is an air pump 10 is stopped (S218), it terminates the routine.

  Thus, in the internal combustion engine 1A, when the engine stop command is issued, the fuel reforming in the reformer 20 is stopped (S200), and further, the operation (reciprocating operation of the piston 4) is stopped ( S202). Thereafter, communication between the reformer 20 and the exhaust gas purification device 7 via the branch pipe L4 is allowed (S206), and the air pump 10 is operated for a predetermined time (S210 to S218). Thereby, the reformed fuel remaining in the reformer 20 and the reformed fuel supply pipe L3 is sent (purged) to the exhaust gas purification apparatus 7 via the branch pipe L4 and the like by the air pumped by the air pump 10. ) Immediately after the internal combustion engine 1 is stopped, the exhaust purification catalyst of the exhaust purification device 7 is sufficiently warmed up, so that the residual reformed fuel sent to the exhaust purification device 7 together with the air of the air pump 10 The exhaust gas purification catalyst will perform a good purification treatment.

  Therefore, also in the internal combustion engine 1A, the reformer 20 and the reformer can be used without using a pump for recovering the reformed fuel or the like from the reformed fuel supply pipe L3, a tank for storing the recovered reformed fuel, or the like. The residual reformed fuel can be substantially eliminated from the fuel supply pipe L3. As a result, even with the internal combustion engine 1A, it is possible to extremely reliably prevent the reformed fuel from remaining in the reformer 20 and the reformed fuel supply pipe L3 while suppressing an increase in cost and a deterioration in space efficiency. This makes it possible to very well avoid deterioration due to hydrogen embrittlement of the reformed fuel supply pipe L3.

  In the internal combustion engine 1A of FIG. 6, the branch pipe L4 is branched from the reformed fuel supply pipe L3 via the three-way valve 16, but the invention is not limited to this. That is, the branch pipe L4 is branched directly from the reformed fuel supply pipe L3, and between the branch portions of the reformed fuel supply pipe L3 and the branch pipe L4, each reformed fuel supply nozzle, and in the middle of the branch pipe L4. In addition, an open / close valve that is controlled to open and close by the ECU 30 may be provided.

1 is a schematic configuration diagram showing a first embodiment of an internal combustion engine according to the present invention. 2 is a flowchart showing a routine that is executed in order to prevent the reformed fuel from remaining in the reformer or the like in the internal combustion engine shown in FIG. 1. FIG. 6 is a flowchart showing another routine that can be executed in order to prevent the reformed fuel from remaining in the reformer or the like in the internal combustion engine shown in FIG. 1. FIG. 6 is a flowchart showing still another routine that can be executed in order to prevent the reformed fuel from remaining in the reformer or the like in the internal combustion engine shown in FIG. 1. FIG. 6 is a flowchart showing another routine that can be executed in order to prevent the reformed fuel from remaining in the reformer or the like in the internal combustion engine shown in FIG. 1. It is a schematic block diagram which shows 2nd Embodiment of the internal combustion engine by this invention. FIG. 7 is a flowchart showing a routine that is executed in order to prevent the reformed fuel from remaining in the reformer or the like in the internal combustion engine shown in FIG. 6.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,1A Internal combustion engine 3 Combustion chamber 4 Piston 7 Exhaust gas purification device 8 Spark plug 10 Air pump 11 Flow control valve 12 Reforming fuel injection valve 14 Water injection valve 15 Starter 16 Three-way valve 20 Reforming device 21 Main body 22 Mixture supply part 23 reforming reaction section 24 mixing chamber 25 reformed fuel supply chamber L1 air supply pipe L2 bypass pipe L3 reformed fuel supply pipe L4 branch pipe

Claims (8)

A reformer that reforms a mixture of fuel and air to generate a reformed fuel containing a predetermined fuel component, and burns the mixture of the reformed fuel and air in a combustion chamber to generate power. In the internal combustion engine that occurs,
A reformed air passage for introducing air into the reformer;
A reformed fuel passage for introducing reformed fuel from the reformer into the combustion chamber;
Control that stops fuel supply to the reformer when an engine stop command is issued, and then continues ignition of the mixture in the combustion chamber for a predetermined time, and then stops ignition of the mixture And an internal combustion engine.   The reformed air passage further includes a reformed air supply means for supplying air to the reformer, and the control means stops the fuel supply to the reformer and 2. The internal combustion engine according to claim 1, wherein the reformed air supply means is operated until ignition of the engine is stopped.   The control means further comprising a reformed air supply means that is provided in the reformed air passage and supplies air to the reformer, and an exhaust purification catalyst for purifying exhaust gas from the combustion chamber. 2. The internal combustion engine according to claim 1, wherein after the ignition of the air-fuel mixture is stopped, the reformed air supply means is operated for a predetermined time. Further comprising cranking means for cranking the internal combustion engine;
The control means stops the cranking means for a predetermined time after stopping the fuel supply to the reformer and before stopping the ignition of the air-fuel mixture when the engine speed falls below a predetermined value. The internal combustion engine according to claim 1, wherein the internal combustion engine is operated. Further comprising cranking means for cranking the internal combustion engine;
The control means stops the fuel supply to the reformer, stops the ignition of the air-fuel mixture when the engine speed falls below a predetermined value, and then operates the cranking means for a predetermined time. The internal combustion engine according to claim 1, wherein: A reformer that reforms a mixture of fuel and air to generate a reformed fuel containing a predetermined fuel component, and burns the mixture of the reformed fuel and air in a combustion chamber to generate power. In the internal combustion engine that occurs,
A reformed air passage for introducing air into the reformer;
A reformed air supply means provided in the reformed air passage for supplying air to the reformer;
A reformed fuel passage for introducing reformed fuel from the reformer into the combustion chamber;
An exhaust purification catalyst for purifying exhaust gas from the combustion chamber;
A branch passage branched from the reformed fuel passage, and connecting the reformer and the exhaust purification catalyst;
Switching means capable of switching communication between the reformer and the combustion chamber via the reformed fuel passage and communication between the reformer and the exhaust purification catalyst via the branch passage;
In response to an engine stop command, the fuel supply to the reformer is stopped, and after the engine stops, the switching means is controlled to allow communication between the reformer and the exhaust purification catalyst via the branch passage. An internal combustion engine comprising: control means for operating the reformed air supply means for a predetermined time. A reformer that reforms a mixture of fuel and air to generate a reformed fuel containing a predetermined fuel component, and burns the mixture of the reformed fuel and air in a combustion chamber to generate power. In an operating method of an internal combustion engine that occurs,
When an engine stop command is issued, the fuel supply to the reformer is stopped, and then the ignition of the air-fuel mixture in the combustion chamber is continued for a predetermined time, thereby remaining at least in the reformer. A method of operating an internal combustion engine, wherein the reformed fuel is fed into the combustion chamber and burned, and then the ignition of the air-fuel mixture is stopped. A reformer that reforms a mixture of fuel and air to generate a reformed fuel containing a predetermined fuel component, and burns the mixture of the reformed fuel and air in a combustion chamber to generate power. In an operating method of an internal combustion engine that occurs,
By stopping the fuel supply to the reformer in response to an engine stop command and operating the reformed air supply means for supplying air to the reformer for a predetermined time after the engine stops, at least inside the reformer A method of operating an internal combustion engine, wherein the reformed fuel remaining in the engine is sent to an exhaust purification catalyst for purifying exhaust gas from the combustion chamber.

Images