JP2010001793A - Internal combustion engine controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an internal combustion engine controller equipped with a fuel reformer in an exhaust route which generates a desired amount of reformed gas by restraining the increase in the temperature of the fuel supplied to the fuel reformer. <P>SOLUTION: A fuel reforming motion is determined whether it is being conducted or not (step 100). In the case where the fuel reforming motion is determined as being stopped, a fuel temperature Ta inside a reforming fuel pipe 38 is measured (step 102). The fuel temperature Ta inside the reforming fuel pipe 38 is determined whether or not it is a predetermined base temperature T1 or below (step 104). In the case where fuel temperature Ta≤base temperature T1 is not approved, a magnet valve 58 is left open for a specified time (steps 106-110). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a control device for an internal combustion engine, and more particularly to a control device for an internal combustion engine provided with a fuel reforming device.

Conventionally, as disclosed in, for example, Japanese Patent Application Laid-Open No. 2006-105011, there is known an internal combustion engine control device including a fuel reformer in an exhaust path of the internal combustion engine. In this control device, a part of the exhaust gas in the exhaust path is introduced into the fuel reformer, and the fuel is added to the exhaust gas, whereby hydrogen (H ₂ ) and carbon monoxide vehicle (CO ) And the like can be generated. The generated reformed gas is selectively introduced into the intake path of the internal combustion engine. Thereby, improvement of a combustion rate, reduction of knocking, etc. can be aimed at.

JP 2006-105011 A JP 2005-76591 A JP 2005-248743 A

  By interposing the fuel reformer in the exhaust path, the reforming operation can be performed by effectively using the exhaust heat. On the other hand, however, when the fuel reformer is exposed to high-temperature exhaust gas, the fuel path for supplying fuel to the fuel reformer is also exposed to a high-temperature environment. In particular, during the period when the reforming operation is stopped, the fuel stays in the fuel pipe, so that the fuel is heated to a high temperature and the fuel density may be reduced. For this reason, when the reforming operation is started, if these fuels are supplied to the fuel reformer, the fuel supply amount is substantially reduced, and a desired amount of reformed gas is generated to generate an internal combustion engine. There was a risk that the engine could not be supplied.

  The present invention has been made to solve the above-described problems. In an internal combustion engine equipped with a fuel reformer, a desired amount is achieved by suppressing a temperature rise of fuel supplied to the fuel reformer. An object of the present invention is to provide a control device for an internal combustion engine capable of generating the reformed gas.

In order to achieve the above object, a first invention is a control device for an internal combustion engine,
A fuel reformer for reforming the supplied reforming fuel and supplying the reformed fuel to the internal combustion engine;
A reforming fuel pipe for the reforming fuel to circulate;
A supply device for supplying reforming fuel flowing through the reforming fuel pipe to the fuel reforming device;
Temperature acquisition means for acquiring the temperature of the reforming fuel staying in the reforming fuel pipe;
A communication pipe having one end connected to the reforming fuel pipe;
A flow means for flowing the reforming fuel retained in the reforming fuel pipe to the communication pipe when the temperature acquired by the temperature acquisition means is higher than a predetermined reference temperature;
It is characterized by providing.

According to a second invention, in the first invention,
The communication pipe is characterized in that the other end is connected to a main fuel pipe for supplying fuel to the internal combustion engine.

According to a third invention, in the first invention,
The other end of the communication pipe is connected to a fuel supply source.

A fourth invention is any one of the first to third inventions,
The temperature acquisition means acquires the temperature of the reforming fuel staying in the reforming fuel pipe based on the operation continuation time of the internal combustion engine after the fuel supply operation of the supply device is stopped. It is characterized by.

According to a fifth invention, in any one of the first to fourth inventions,
The flow means includes an open / close valve that opens and closes the communication pipe, and the open / close valve is opened when the temperature acquired by the temperature acquisition means is higher than a predetermined reference temperature.

  According to the first invention, in the internal combustion engine having the fuel reformer for reforming the supplied reforming fuel, the temperature of the reforming fuel staying in the reforming fuel pipe is a predetermined reference. When the temperature becomes higher than the temperature, the reforming fuel staying in the reforming fuel pipe is circulated from the reforming fuel pipe to the communication pipe. For this reason, according to the present invention, since the high-temperature fuel in the reforming pipe can be circulated to the communication pipe, the fuel temperature in the reforming pipe can be effectively reduced. As a result, the amount of fuel supplied to the fuel reformer can be stabilized, so that a desired amount of reformed gas can be generated.

  According to the second invention, the other end of the communication pipe is connected to a main fuel pipe for supplying fuel to the internal combustion engine. For this reason, according to the present invention, the high-temperature fuel retained in the reforming fuel pipe can be effectively used as the fuel for the internal combustion engine.

  According to the third invention, the other end of the communication pipe is connected to the fuel supply source. For this reason, according to the present invention, the high-temperature fuel remaining in the reforming fuel pipe can be returned to the fuel supply source again.

  According to the fourth aspect of the invention, the temperature of the reforming fuel staying in the reforming fuel pipe is determined based on the operation of the internal combustion engine after the fuel supply operation to the fuel reforming device by the supply device is stopped. Acquired based on duration. In a state where the reforming fuel stays in the reforming fuel pipe, the temperature of the fuel rises as the operation duration time of the internal combustion engine becomes longer. For this reason, according to the present invention, the fuel temperature in the reforming fuel pipe can be accurately obtained based on the operation continuation time of the internal combustion engine.

  According to the fifth aspect of the present invention, an on-off valve for controlling the open / close state of the communication pipe is disposed in the middle of the communication pipe. Therefore, according to the present invention, when the temperature of the reforming fuel staying in the reforming fuel pipe becomes higher than a predetermined reference temperature, the on-off valve is opened to improve the reforming fuel. The high-temperature fuel in the quality pipe can be effectively distributed to the communication pipe.

  Embodiments of the present invention will be described below with reference to the drawings. In addition, the same code | symbol is attached | subjected to the element which is common in each figure, and the overlapping description is abbreviate | omitted. The present invention is not limited to the following embodiments.

Embodiment.
[Configuration of the embodiment]
FIG. 1 is a diagram for explaining a configuration of an internal combustion engine according to an embodiment of the present invention. One end of an intake passage 12 is connected to the intake side of the internal combustion engine 10. The other end of the intake passage 12 is open to the outside, and an air cleaner 14 is disposed in the middle. A throttle valve 16 for controlling the flow rate of the intake air is disposed on the downstream side of the air cleaner 14. A fuel injection valve 52 for injecting fuel into the intake air flowing through the intake passage 12 is disposed downstream of the throttle valve 16 in the intake passage 12.

  One end of an exhaust passage 20 is connected to the exhaust side of the internal combustion engine 10. A fuel reformer 22 is interposed in the middle of the exhaust passage 20. The detailed structure of the fuel reformer 22 will be described later. A U / F catalyst 24 is connected downstream of the fuel reformer 22. The U / F catalyst 24 has a function of purifying unpurified components such as NOx and HC contained in the exhaust gas.

  One end of the EGR passage 26 communicates with the upstream side of the fuel reformer 22 in the exhaust passage 20. In the middle of the EGR passage 26, a fuel injection valve 54 for injecting fuel into the exhaust gas flowing through the EGR passage 26 is disposed. A fuel reformer 22 is interposed in the EGR passage 26 in the vicinity of the downstream side of the fuel injection valve 54. On the downstream side of the fuel reformer 22 in the EGR passage 26, an EGR cooler 28 for cooling the gas flowing in the EGR passage is interposed. The other end of the EGR passage 26 communicates with the downstream side of the throttle valve 16 in the intake passage 12. An EGR valve 30 for controlling the flow rate of gas introduced from the EGR passage 26 to the intake passage 12 is provided in the vicinity of the connection portion of the EGR passage 26 with the intake passage 12.

The fuel reformer 22 includes a three-way catalyst unit 221 for purifying exhaust gas introduced from the exhaust passage 20 and a reforming catalyst for reforming fuel introduced from the EGR passage 26 described later to H ₂ or CO. Part 222. The three-way catalyst part 221 has both ends connected to the exhaust passage 20 described above. On the other hand, the reforming catalyst portion 222 is a catalyst containing a metal such as Rh, Pt, or Ru, and both ends thereof are connected to the EGR passage 26 described above. The three-way catalyst unit 221 and the reforming catalyst unit 222 are isolated from each other without communicating with each other.

  The internal combustion engine 10 includes a fuel tank 32. One end of a main fuel pipe 34 is connected to the fuel tank 32. The fuel in the fuel tank 32 is supplied to the main fuel pipe 34 by a fuel pump 36 provided in the main fuel pipe 34.

  The fuel injection valve 52 described above is connected to the downstream end of the main fuel pipe 34. A reforming fuel pipe 38 communicates with the main fuel pipe 34. The fuel injection valve 54 described above is connected to the downstream end of the reforming fuel pipe 38. A temperature sensor 56 for detecting the temperature of fuel injected from the fuel injection valve 54 is provided at a connection portion of the fuel injection valve 54 in the reforming fuel pipe 38.

  The internal combustion engine 10 of the present embodiment includes a communication pipe 40 for connecting the downstream end of the reforming fuel pipe 38 and the main fuel pipe 34. In the middle of the communication pipe 40, an electromagnetic valve 58 for switching the communication state of the communication pipe 40 is provided.

  As shown in FIG. 1, the control device of this embodiment includes an ECU (Electronic Control Unit) 50. In addition to the temperature sensor 56 described above, various sensors (not shown) for detecting the operating state of the internal combustion engine 10 are connected to the input of the ECU 50. In addition, various actuators such as the fuel injection valves 52 and 54 and the electromagnetic valve 58 described above are connected to the output of the ECU 50.

[Operation of the embodiment]
(About fuel reforming operation)
Next, the operation in the fuel reformer 22 will be described. The fuel reformer 22 includes a three-way catalyst unit 221 for purifying unpurified components in the exhaust gas, and a reformer for generating reformed gas such as hydrogen (H2) and carbon monoxide (CO) from the fuel. And a catalyst part 222. More specifically, the exhaust gas exhausted from the internal combustion engine 10 flows through the exhaust passage 20 and is introduced into the three-way catalyst unit 221 in the fuel reformer 22. In the three-way catalyst unit 221, unpurified components such as NOx and HC are purified to N ₂ , CO _{2 and the} like by the action of the catalyst.

  The exhaust gas discharged from the three-way catalyst unit 221 in the fuel reformer 22 flows through the exhaust passage 20 and is introduced into the U / F catalyst 24. The U / F catalyst 24 is a three-way catalyst and can purify unpurified components that have not been purified by the three-way catalyst unit 221. The gas exhausted from the U / F catalyst 24 passes through a muffler (not shown) and is released to the atmosphere.

  A part of the exhaust gas exhausted from the internal combustion engine 10 to the exhaust passage 20 is introduced into the EGR passage 26. As described above, the fuel injection valve 54 is disposed near the upstream side of the fuel reformer 22 in the EGR passage 26. The fuel injected from the fuel injection valve 54 is vaporized by the exhaust heat of the exhaust gas and is introduced into the reforming catalyst unit 222 in the fuel reformer 22. In the reforming catalyst unit 222, the mixed gas of fuel and exhaust gas is reformed into a high energy component such as hydrogen (H2) or carbon monoxide (CO) by an endothermic reaction.

  The generated reformed gas flows downstream through the EGR passage 26 and is cooled by the EGR cooler 28. Thereafter, the flow rate is controlled by the EGR valve 30 and introduced into the internal combustion engine 10 from the intake passage 12. As a result, it is possible to improve the combustion speed, improve the fuel consumption by reducing the pumping and cooling loss due to the high EGR operation, and suppress the knocking.

(Features of this embodiment)
The start / stop of the fuel reforming operation in the reforming catalyst unit 222 is determined based on the required reformed gas amount. More specifically, the required reformed gas amount is determined based on the temperature feedback of the temperature of the reformed gas reformed by the reforming catalyst unit 222 and the operating conditions of the internal combustion engine 10.

  Here, when the fuel reforming operation in the reforming catalyst unit 222 is stopped, for example, during the warm-up operation, the EGR operation, or the catalyst poisoning recovery process of the internal combustion engine 10, the internal combustion engine 10. Is operating, but fuel injection from the fuel injection valve 54 is stopped. For this reason, the fuel in the reforming fuel pipe 38 stays in the pipe.

  The periphery of the fuel reformer 22 is in a high temperature atmosphere due to the influence of exhaust heat. For this reason, the staying fuel receives heat from the outside of the reforming fuel pipe 38 and is gradually heated. In particular, since the vicinity of the fuel injection valve 54 is close to the fuel reformer, it is more strongly affected by the exhaust heat. When the fuel is heated, vaporization and boiling occur, and the fuel density decreases. For this reason, when the fuel reforming operation is started, if this low density fuel is injected, the initial fuel injection amount may not be stabilized, and the amount of reformed gas produced may decrease. is there. When the amount of the reformed gas decreases, the output of the internal combustion engine 10 is insufficient, the fuel efficiency improvement effect is delayed, and the like.

  Therefore, in the present embodiment, when the temperature of the fuel injected from the fuel injection valve 54 is high, the remaining high-temperature fuel is circulated. More specifically, when the temperature of the fuel injected from the fuel injection valve 54 is higher than a predetermined reference temperature, the electromagnetic valve 58 provided in the communication pipe 40 is opened.

  FIG. 2 is a diagram schematically showing the flow of the fuel system of the internal combustion engine when the fuel reforming operation is stopped. As shown in this figure, when the fuel injection from the fuel injection valve 54 is stopped, when the electromagnetic valve 58 is opened, the downstream end of the reforming fuel pipe 38 and the main fuel pipe 34 communicate with each other. . For this reason, the high-temperature fuel remaining in the reforming fuel pipe 38 passes through the communication pipe 40 and flows to the main fuel pipe 34 and is injected from the fuel injection valve 52 to the internal combustion engine 10.

  When the staying fuel in the reforming fuel pipe 38 flows, the fuel temperature in the reforming fuel pipe 38 decreases. For this reason, when the fuel reforming operation in the reforming catalyst unit 222 is started, it is possible to effectively avoid a situation in which high-temperature fuel with reduced fuel density is introduced into the reforming catalyst unit 222.

  As described above, when the fuel reforming operation is stopped, the fuel temperature in the reforming fuel pipe 38 is prevented from becoming higher than the predetermined reference temperature, so that the fuel at the start of the fuel reforming operation The injection amount can be stabilized. Thereby, since a desired amount of reformed gas can be generated and supplied, the combustion state of the internal combustion engine 10 can be kept good.

[Specific processing in the embodiment]
Next, with reference to FIG. 3, the specific content of the process performed in this Embodiment is demonstrated. FIG. 3 is a flowchart of a routine that the ECU 50 executes while the internal combustion engine 10 is in operation.

  In the routine shown in FIG. 3, it is first determined whether or not a fuel reforming operation is being performed (step 100). Here, specifically, it is determined whether or not fuel is being injected from the fuel injection valve 54. As a result, if it is determined that the fuel reforming operation is being performed, the fuel in the reforming fuel pipe 38 is in circulation, so it is determined that there is no risk of the fuel temperature rising, This routine is immediately terminated.

  On the other hand, if it is determined in step 100 that the fuel reforming operation is stopped, it is determined that the fuel temperature in the reforming fuel pipe 38 may rise, and the next step is performed. Then, the fuel temperature Ta in the reforming fuel pipe 38 is measured (step 102). Here, specifically, the temperature sensor 56 is used for measurement.

  Next, it is determined whether or not the fuel temperature Ta in the reforming fuel pipe 38 is equal to or lower than a predetermined reference temperature T1 (step 104). Here, specifically, the temperature Ta measured in step 102 is compared with a predetermined reference temperature T1. As the predetermined reference temperature T1, a value set in advance through experiments or the like is used as the maximum temperature that can allow the fuel density to decrease. As a result, when the establishment of the fuel temperature Ta ≦ the reference temperature T1 is recognized, it is determined that the fuel density of the fuel is within the allowable range, and this routine is immediately terminated.

  On the other hand, if the establishment of the fuel temperature Ta ≦ the reference temperature T1 is not recognized in step 104, the fuel density of the fuel in the reforming fuel pipe 38 is lowered to such an extent that the fuel injection amount is not stabilized. Therefore, the process proceeds to the next step, and the solenoid valve 58 is opened (step 106). Specifically, the electromagnetic valve 58 is opened here, and the main fuel pipe 34 and the reforming fuel pipe 38 are communicated via the communication pipe 40.

  Next, a specified time counter is started (step 108). The specified time is set in consideration of the length of the reforming fuel pipe 38, the communication pipe 40, and the main fuel pipe 34, the influence of the radiant heat of the internal combustion engine 10, and the like. When the specified time has elapsed, the process proceeds to the next step, and the solenoid valve 58 is closed (step 110). Here, specifically, the communication pipe 40 is blocked, and the communication state between the main fuel pipe 34 and the reforming fuel pipe 38 is blocked.

  As described above, according to the present embodiment, when the fuel temperature Ta in the reforming fuel pipe 38 becomes higher than the predetermined reference temperature T1, the reforming fuel pipe 38 connects the communication pipe 40. Via the main fuel pipe 34 for a specified time. As a result, the high-temperature fuel remaining in the reforming fuel pipe 38 can be circulated to the main fuel pipe 34, so that the temperature of the fuel in the reforming fuel pipe 38 can be effectively reduced. it can.

  By the way, according to the above-described embodiment, the temperature Ta of the fuel in the reforming fuel pipe 38 is measured using the temperature sensor 56, but the method of acquiring the temperature Ta is not limited to this. That is, the temperature of the fuel staying in the reforming fuel pipe 38 increases as the operation duration time of the internal combustion engine 10 increases. For this reason, after the fuel reforming operation is stopped, the operation duration time of the internal combustion engine 10 may be measured, and the fuel temperature Ta in the reforming fuel pipe 38 may be acquired based on the operation duration time. .

  Further, according to the above-described embodiment, when the temperature Ta of the fuel in the reforming fuel pipe 38 is higher than the predetermined reference temperature, the downstream end of the reforming fuel pipe 38 is connected via the communication pipe 40. Although the main fuel pipe 34 is communicated, the communication destination of the reforming fuel pipe 38 is not limited to this. That is, if the high-temperature fuel staying in the reforming fuel pipe 38 can be circulated, it may be returned to the fuel tank 32, for example.

  FIG. 4 is a diagram schematically showing a modification of the piping structure of the fuel system of the internal combustion engine. In the modification shown in FIG. 4, instead of the communication pipe 40 shown in FIG. 2, a return pipe 42 that connects the vicinity of the downstream end of the reforming fuel pipe 38 and the fuel tank 32 is connected. An electromagnetic valve 60 for opening and closing the return pipe 42 is arranged in the middle of the return pipe 42.

  In the system shown in FIG. 4, when the fuel temperature Ta in the reforming fuel pipe 38 becomes higher than a predetermined reference temperature T1, the electromagnetic valve 60 is opened. Thereby, the high-temperature fuel in the reforming fuel pipe 38 can be returned to the fuel tank 32.

  In the above-described embodiment, the fuel reformer 22 is the “fuel reformer” in the first invention, and the reforming fuel pipe 38 is the “reforming fuel pipe” in the first invention. The fuel injection valve 54 corresponds to the “supply device” in the first invention, and the communication pipe 40 corresponds to the “communication pipe” in the first invention. Further, when the ECU 50 executes the process of step 102, the “temperature acquisition means” in the first invention executes the process of step 106, so that the “distribution means” in the first invention. Are realized.

  In the above-described embodiment, the main fuel pipe 34 corresponds to the “main fuel pipe” in the second invention.

  In the above-described embodiment, the fuel tank 32 corresponds to the “fuel supply source” in the third aspect of the invention.

  In the embodiment described above, the electromagnetic valve 58 corresponds to the “open / close valve” in the fifth aspect of the invention.

It is a figure for demonstrating the structure of the internal combustion engine which concerns on embodiment of this invention. It is a figure which shows typically the flow of the fuel system of an internal combustion engine in case the fuel reforming operation | movement is stopped. It is a flowchart of the routine performed in Embodiment 2 of this invention. It is a figure which shows typically the modification of the piping structure of the fuel system of an internal combustion engine.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Internal combustion engine 12 Intake passage 14 Air cleaner 16 Throttle valve 20 Exhaust passage 22 Fuel reformer 221 Three way catalyst part 222 Reforming catalyst part 24 U / F catalyst 26 EGR path 28 EGR cooler 30 EGR valve 32 Fuel tank 34 Main fuel piping 36 Fuel pump 38 Fuel pipe for reforming 40 Communication pipe 42 Return pipe 50 ECU (Electronic Control Unit)
52, 54 Fuel injection valve 56 Temperature sensor 58, 60 Solenoid valve

Claims (5)

A fuel reformer for reforming the supplied reforming fuel and supplying the reformed fuel to the internal combustion engine;
A reforming fuel pipe for the reforming fuel to circulate;
A supply device for supplying reforming fuel flowing through the reforming fuel pipe to the fuel reforming device;
Temperature acquisition means for acquiring the temperature of the reforming fuel staying in the reforming fuel pipe;
A communication pipe having one end connected to the reforming fuel pipe;
A flow means for flowing the reforming fuel retained in the reforming fuel pipe to the communication pipe when the temperature acquired by the temperature acquisition means is higher than a predetermined reference temperature;
A control device for an internal combustion engine, comprising:   2. The control device for an internal combustion engine according to claim 1, wherein the other end of the communication pipe is connected to a main fuel pipe for supplying fuel to the internal combustion engine.   The control device for an internal combustion engine according to claim 1, wherein the communication pipe has the other end connected to a fuel supply source.   The temperature acquisition means acquires the temperature of the reforming fuel staying in the reforming fuel pipe based on the operation continuation time of the internal combustion engine after the fuel supply operation of the supply device is stopped. The control device for an internal combustion engine according to any one of claims 1 to 3, wherein:   The flow means includes an open / close valve that opens and closes the communication pipe, and opens the open / close valve when a temperature acquired by the temperature acquisition means is higher than a predetermined reference temperature. Item 5. The control device for an internal combustion engine according to any one of Items 1 to 4.

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