JP4777269B2 - Fuel supply device for internal combustion engine - Google Patents

Description

  The present invention relates to reforming gasoline fuel supplied to an internal combustion engine.

  Patent Document 1 proposes a fuel supply device that reforms gasoline fuel and supplies it to an internal combustion engine. This apparatus takes out reformed gas containing hydrogen and carbon monoxide by adding steam reforming and partial oxidation reforming to gasoline fuel. On the other hand, the unreformed hydrocarbon fuel is used as a high octane fuel having a relatively small molecular weight.

Since the reformed gas has a high combustion rate and has an effect of igniting the air-fuel mixture with certainty, the use of the reformed gas during the lean combustion of the internal combustion engine improves the combustion stability. On the other hand, the high octane fuel has the effect of preventing knocking of the internal combustion engine and improving the output torque and thermal efficiency.
JP 2000-291499 A

  In the prior art, high-octane fuel is obtained as a by-product of partial oxidation reforming and steam reforming for extracting hydrogen and carbon monoxide. Therefore, for example, it is not possible to obtain only a high octane fuel without a reforming reaction. As a result, the amount of high octane fuel may be insufficient compared to the reformed gas.

  Further, the reformed gas obtained by partial oxidation reforming and steam reforming contains about 50% of nitrogen, which is an inert gas, in addition to hydrogen and carbon monoxide. Nitrogen dilutes the fuel and adversely affects combustion stability.

  Accordingly, an object of the present invention is to make it possible to arbitrarily change the production ratio of high burning rate fuel and high octane number fuel.

  Another object of the present invention is to reduce the nitrogen content in high burn rate fuel.

  In order to achieve the above object, the present inventors paid attention to an isomerization reforming reaction and a decomposition reforming reaction of gasoline fuel represented by the following equations.

Isomerization reforming reaction:
Heptane (C ₇ H ₁₆ ) → 2-methylhexane (C ₇ H ₁₆ )
Decomposition and reforming reaction:
Heptane (C ₇ H ₁₆ ) → hydrogen (H ₂ ) + ethylene (C ₂ H ₄ ) + 1-pentene (C ₅ H ₁₀ )
The isomerization reforming reaction produces an isomerized fuel having a high octane number, and the cracking reforming reaction produces a cracked fuel having a high combustion rate. Since these reforming reactions do not require oxygen, the nitrogen content of the produced fuel can be kept low.

  Based on the above considerations, the present invention induces the isomerization reforming reaction of raw fuel and the cracking reforming reaction of raw fuel at different ratios depending on the catalyst temperature in a fuel supply device that supplies fuel to an internal combustion engine. Fuel reforming means, catalyst temperature changing means for changing the catalyst temperature, fuel supply means for supplying the internal combustion engine with the isomerized fuel produced by the isomerization reforming reaction and the cracked fuel produced by the cracking reforming reaction, respectively And a programmable controller for controlling the catalyst temperature changing means.

  The programmable controller determines whether or not there is a request for increasing the ratio of the isomerization reforming reaction, and sets the catalyst temperature changing means so that the catalyst temperature falls below a predetermined temperature in response to the request for increasing the ratio of the isomerization reforming reaction. Control, determine whether there is a request to increase the ratio of the cracking reforming reaction, and control the mechanism for changing the catalyst temperature so that the catalyst temperature exceeds the predetermined temperature in response to the request for increasing the ratio of the cracking reforming reaction. Programmed.

  The present invention also provides a reforming catalyst that induces the isomerization reforming reaction of the raw fuel and the cracking reforming reaction of the raw fuel at different ratios according to the catalyst temperature, catalyst temperature changing means for changing the catalyst temperature, Provided is a control method for a fuel supply device comprising fuel supply means for supplying an isomerized fuel generated by a cracking reforming reaction and a cracked fuel generated by a cracking reforming reaction to an internal combustion engine.

  In this control method, it is determined whether there is a request for increasing the ratio of the isomerization reforming reaction, and the catalyst temperature changing means is set so that the catalyst temperature falls below a predetermined temperature in response to the request for increasing the ratio of the isomerization reforming reaction. It is determined whether there is a request for increasing the ratio of the cracking reforming reaction, and the catalyst temperature changing means is controlled so that the catalyst temperature exceeds a predetermined temperature in response to the request for increasing the ratio of the cracking reforming reaction.

  According to the present invention, the production ratio of high octane fuel (isomerized fuel) and high combustion rate fuel (decomposed fuel) can be arbitrarily changed, and the content ratio of nitrogen in the produced fuel is reduced. be able to.

  Embodiments of the present invention will be described below with reference to the drawings.

  Referring to FIG. 1 of the drawings, a fuel supply device for a four-stroke cycle internal combustion engine 1 for a vehicle includes a fuel reforming system for reforming gasoline fuel stored in a main fuel storage tank 7, and an internal combustion engine 1. And a fuel supply system for supplying various fuels.

  The fuel reforming system reforms the gasoline fuel in the main fuel storage tank 7 using the catalytic converter 5 and the condenser 12. A reforming catalyst 6 is built in the catalytic converter 5. In the catalytic converter 5, the reforming of the gasoline fuel containing heptane is performed through an isomerization reforming reaction and a cracking reforming reaction represented by the following molecular formula.

Isomerization reforming reaction:
Heptane (C ₇ H ₁₆ ) → 2-methylhexane (C ₇ H ₁₆ )
Decomposition and reforming reaction:
Heptane (C ₇ H ₁₆ ) → hydrogen (H ₂ ) + ethylene (C ₂ H ₄ ) + 1-pentene (C ₅ H ₁₀ )
The isomerization reforming reaction means a reaction that does not cause any difference in molecular formula and changes the fuel to an isomeric compound. The cracking and reforming reaction means a reaction in which the fuel is vaporized by the heat of the reforming catalyst 6 to change from a fuel component having a high molecular weight to a fuel component having a low molecular weight. These reforming reactions are different from the partial oxidation reforming and steam reforming of the prior art.

  Referring to FIG. 2, the reforming catalyst 6 is carried on a honeycomb-shaped carrier housed in the housing 5 </ b> A of the catalytic converter 5. The reforming catalyst 6 is composed of beta zeolite and platinum. However, as the material of the reforming catalyst 6, any other material capable of inducing isomerization reforming and cracking reforming reaction of fuel may be used.

  The reforming catalyst 6 has a cylindrical shape, and a through hole 6a is formed in the axial center. When the exhaust pipe 70 of the internal combustion engine 1 passes through the through hole 6a, the heat of the exhaust gas is transmitted to the reforming catalyst 6, and the above reforming reaction of the fuel is activated.

  Such a configuration of the catalytic converter 5 is preferable in that the heat supply to the reforming catalyst 6 can be efficiently performed and the space around the exhaust pipe 70 of the vehicle is effectively used for the arrangement of the catalytic converter 5.

  A fuel injector 8 that injects gasoline fuel in the main fuel storage tank 7 toward the reforming catalyst 6 is provided in the housing 5 </ b> A upstream of the reforming catalyst 6.

  An air supply pipe 13 is connected to the catalytic converter 5. The air supply pipe 13 supplies the air that has passed through the air cleaner to the upstream side of the reforming catalyst 6. The air supply pipe 13 is provided with an air amount control valve 14 as an air amount regulator for controlling the amount of supplied air. The gasoline fuel injected from the fuel injector 8 is mixed with the air supplied from the air supply pipe 13 and supplied to the reforming catalyst 6 as an air-fuel mixture.

  The reforming catalyst 6 performs isomerization reforming by fuel isomerization reaction and cracking reforming by cracking reaction at a reaction rate corresponding to the catalyst temperature.

  Referring to FIG. 3, the reforming catalyst 6 induces mainly an isomerization reforming reaction in the temperature region A, and induces an isomerization reforming reaction and a cracking reforming reaction in parallel in the higher temperature region B. Furthermore, in the higher temperature region C, the decomposition reforming reaction is mainly induced. Here, the temperature regions A, B, and C are set around 450K, 500K, and 550K (K = Kelvin), respectively.

  Referring again to FIG. 1, the reformed gas generated by the reforming catalyst 6 flows from the reformed gas pipe 11 into the condenser 12. The condenser 12 separates the reformed gas into a fuel component obtained by a cracking reforming reaction and a fuel component obtained by an isomerization reforming reaction. In the following description, the former is called cracked fuel and the latter is called isomerized fuel.

  The configuration of the condenser 12 will be described with reference to FIG.

  The condenser 12 is connected to the reformed gas pipe 11 and is disposed at a position higher than the reformed gas pipe 11. A cooling water pipe 18 is spirally arranged inside the cylindrical housing 12 </ b> A of the condenser 12. The cooling water pipe 18 has an inlet and an outlet on the outside of the cylindrical housing 12A. The cylindrical housing 12A is arranged so that the central axis of the cylindrical shape coincides with the vertical line. A cracked fuel pipe 22A is connected to the upper end surface of the housing 12A, and an isomerized fuel pipe 22B is connected to the lower end surface. The reformed gas pipe 11 is connected to the isomerized fuel pipe 22B, and the flow of the reformed gas from the reformed gas pipe 11 into the condenser 12 is performed via a part of the isomerized fuel pipe 22B.

  The inside of the housing 12A is filled with the reformed gas. The condenser 12 cools the reformed gas by heat exchange between the cooling water pipe 18 and the reformed gas, and separates it into a cracked fuel having a low freezing point and an isomerized fuel having a high freezing point. The cracked fuel stays in the housing 12A as a gas and flows into the cracked fuel pipe 22A connected to the upper end of the housing 12A. On the other hand, the isomerized fuel is liquefied in the housing 12A and flows into the isomerized fuel pipe 22B connected to the lower end of the housing 12A.

  Referring again to FIG. 1, the cooling water pipe 18 is connected to the radiator 17 via the pump 19. The pump 19 may be an electric drive type or a type driven using the shaft output of the internal combustion engine 1 as long as it has a function of circulating cooling water between the condenser 12 and the radiator 17.

  The isomerized fuel pipe 22 </ b> B is connected to an isomerized fuel storage tank 20 disposed below the condenser 12. The cracked fuel pipe 22 is connected to the cracked fuel tank 21 via the compressor 23.

  The isomerized fuel is a high-octane fuel having a molecular structure that is monomethyl, dimethyl, and trimethyl, although the molecular weight does not change compared to the unreformed fuel (raw fuel) stored in the main fuel storage tank 7. The point is different. Since the isomerized fuel has a high octane number, it is effective as a fuel for the internal combustion engine 1 to prevent knocking. The isomerized fuel flows down the isomerized fuel pipe 22B and is stored in the isomerized fuel storage tank 20.

  The cracked fuel is a gaseous fuel containing hydrogen, such as hydrogen, methane, or ethylene. When the cracked fuel is supplied to the internal combustion engine 1 together with the gasoline fuel, the cracked fuel increases the combustion speed of the gasoline fuel. The gaseous cracked fuel flowing into the cracked fuel pipe 22A from the condenser 12 is condensed by the compressor 23 driven by the shaft output of the internal combustion engine 1, and stored in the cracked fuel storage tank 21 as a liquid pressurized to a predetermined pressure.

  Gasoline fuel in the main fuel storage tank 7 is supplied to the fuel injector 8 through a fuel pump 10 and a fuel supply pipe 9.

  Next, the fuel supply system will be described.

  Referring to FIG. 1 again, the internal combustion engine 1 is connected to the intake collector 2 via the four intake branch pipes 3 and includes four cylinders.

  The gasoline fuel in the main fuel storage tank 7 is injected into each cylinder of the internal combustion engine 1 by four main fuel injectors 27. For this purpose, the main fuel supply pump 25 pressurizes the gasoline fuel in the main fuel storage tank 7 and distributes it to the main fuel injector 27 via the main fuel pipe 26. The fuel injected from the main fuel injector 27 is mixed with the air sucked into each cylinder of the internal combustion engine 1 from the intake collector 2 through the intake branch pipe 3 to form an air-fuel mixture in the cylinder. The fuel injected from the main fuel injector 27 is unreformed gasoline fuel.

  The fuel in the isomerized fuel storage tank 20 is adjusted to a predetermined pressure by the fuel pump 30 and supplied to the isomerized fuel injector 33 provided in the intake collector 2 through the fuel supply pipe 31. The isomerized fuel injector 33 injects isomerized fuel into the intake collector 2. The injected isomerized fuel is mixed with the air in the intake collector 2 and then sucked into each cylinder of the internal combustion engine 1 through the intake branch pipe 3.

  The cracked fuel in the cracked fuel storage tank 21 is supplied to a cracked fuel injector 35 provided in the intake collector 2 via a cracked fuel supply pipe 37. The cracked fuel injector 35 injects cracked fuel into the intake collector 2. The injected cracked fuel is mixed with the air in the intake collector 2 and then sucked into each cylinder of the internal combustion engine 1 through the intake branch pipe 3.

  Referring to FIG. 5, a combustion chamber 45 is defined in each cylinder of the internal combustion engine 1 by a cylinder head 40, a cylinder block 41, a piston 42, an intake valve 43 and an exhaust valve 44. The intake valve 43 communicates or blocks the intake port 46 connected to the intake branch pipe 3 and the combustion chamber 45. The main fuel injector 27 is provided in the intake port 46. However, the present invention is also applicable to a direct injection internal combustion engine in which the main fuel injector 27 is provided in the combustion chamber 45.

  The exhaust valve 44 communicates or blocks the exhaust port 47 and the combustion chamber 45. The exhaust port 47 communicates with the exhaust branch pipe 4 shown in FIG. As shown in FIG. 1, the internal combustion engine 1 includes four exhaust branch pipes 4 that merge into the exhaust pipe 70.

  Referring to FIG. 5 again, the intake valve 43 is reciprocated periodically between the fully open position and the fully closed position by the intake valve cam 48 and the exhaust valve 44 by the exhaust valve cam 49, respectively.

  The cylinder head 40 is provided with a spark plug 51 for igniting the air-fuel mixture in the combustion chamber 45.

  With the above configuration, the intake air that has passed through the air cleaner is sucked into the combustion chamber 45 of the internal combustion engine 1 through the intake collector 2, the intake branch pipe 3, the intake port 46, and the intake valve 43. In this process, isomerized fuel is injected from the isomerized fuel injector 33 and decomposed fuel is injected from the cracked fuel injector 35 in the intake collector 2 according to operating conditions.

  In the intake port 46, gasoline fuel in the main fuel storage tank 7 is injected from the main fuel injector 27. The spark plug 51 ignites the air-fuel mixture generated in the combustion chamber 45 in the second half of the compression stroke or the first half of the expansion stroke of the piston 42 to burn the air-fuel mixture, and the piston 42 is reciprocated by the combustion pressure. Move.

  The fuel injection timing and injection period of each fuel injector 8, 27, 33, 35 and the ignition timing of the spark plug 51 are in accordance with a command signal output from an engine control unit (hereinafter referred to as ECU) 60 that is a programmable controller. Adjusted. The operation of the fuel pumps 10 and 30, the opening degree of the air amount control valve 14, and the operation of the main fuel supply pump 25 are also controlled by the ECU 60.

  The ECU 60 includes a microcomputer that includes a central processing unit (CPU), a read-only memory (ROM), a random access memory (RAM), and an input / output interface. The ECU 60 can also be composed of a plurality of microcomputers.

  Further, for the above control, the ECU 60 includes an air flow meter 15 that detects the flow rate of air supplied to the reforming catalyst 6, a thermocouple 16 that detects the temperature in the reforming catalyst 6, and the main fuel storage tank 7. A level sensor 28 for detecting the liquid level of the main fuel, a level sensor 29 for detecting the liquid level of the isomerized fuel in the isomerized fuel storage tank 20, and a fuel pressure of the decomposed fuel in the cracked fuel storage tank 21 are detected. The pressure sensor 34, the crank angle sensor 55 for detecting the crank angle and the rotational speed of the internal combustion engine 1, the water temperature sensor 56 for detecting the cooling water temperature of the internal combustion engine 1, and the depression amount (accelerator opening) of the accelerator pedal provided in the vehicle. Detection data is input as signals from the accelerator opening sensor 57 to be detected.

  Next, a fuel injection control routine for the internal combustion engine 1 executed by the ECU 60 as a control routine for the fuel supply system will be described with reference to FIG. The ECU 60 executes this routine at regular intervals during operation of the internal combustion engine 1, that is, for example, every several tens of milliseconds.

  First, in step S1, the ECU 60 reads the engine speed detected by the crank angle sensor 55 and the accelerator opening detected by the accelerator opening sensor 57.

  In the next step S2, the ECU 60 calculates a target engine rotational speed and a target engine load from the engine rotation single degree and the accelerator opening, and determines a corresponding target fuel injection amount. This calculation is executed by a subroutine using a known method.

  In the next step S3, the ECU 60 refers to the characteristic map shown in FIG. 8 stored in advance in the ROM, and based on the target engine speed and the target engine load, the proportion of the main fuel and which reformed fuel is determined. Decide whether to combine with.

  Referring to FIG. 8, here, the engine load is represented by an in-cylinder effective pressure Pe (bar). The in-cylinder effective pressure Pe is a value obtained by subtracting the friction loss due to the sliding of the piston from the average value of the in-cylinder pressure during one stroke cycle. Fuel injection in the internal combustion engine 1 is performed by combining main fuel injection by the fuel injector 27 with either or both of isomerized fuel injection by the isomerized fuel injector 33 and cracked fuel injection by the cracked fuel injector 35. . The map of FIG. 8 represents the ratio between the amount of isomerized fuel injected by the isomerized fuel injector 33 and the amount of decomposed fuel injected by the cracked fuel injector 35.

  In the map of FIG. 8, the load condition where the in-cylinder effective pressure Pe is 5 bar or less is set in the cracked fuel region where only cracked fuel is used as the reformed fuel. When the internal combustion engine 1 is under a low load condition, the target fuel injection amount under the low load condition is set in advance in the calculation of step S2 on the premise of lean combustion. Correspondingly, in this region, the entire amount of reformed fuel to be supplied is made into cracked fuel with a high combustion rate, thereby ensuring reliable ignition of the air-fuel mixture in a lean combustion environment. In the cracked fuel region, the map is set so that the ratio of the split fuel supplied to the main fuel increases as the in-cylinder effective pressure Pe further decreases.

  On the other hand, the low-speed and high-load condition where the in-cylinder effective pressure Pe is larger than 9 bar and the target engine speed is smaller than 4,000 rpm is set in the isomerized fuel region where only the isomerized fuel is used as the reformed fuel. In this area, knocking is prevented by making the total amount of reformed fuel to be supplied an isomerized fuel having a high octane number.

  The upper curve in FIG. 8 represents the maximum load of the internal combustion engine 1. That is, the operation of the internal combustion engine 1 is not performed in a region above this curve.

  A region between the isomerized fuel region and the cracked fuel region is set to an intermediate region that supplies both cracked fuel and isomerized fuel as reformed fuel. In this region, the supply ratio of isomerized fuel is increased as compared with the supply ratio of cracked fuel as the target engine load increases. With this setting, the internal combustion engine 1 operates with optimum fuel consumption corresponding to the operating conditions.

  As described above, the ECU 60 determines the injection amounts of the main fuel, the isomerized fuel, and the cracked fuel with reference to this map based on the target engine speed and the target engine load.

  In the next step S4, the ECU 60 outputs to the fuel injectors 27, 33, 35 signals of pulse widths corresponding to the injection amounts of main fuel, isomerized fuel, and cracked fuel.

  By executing the above routine, the internal combustion engine 1 performs stable lean combustion by supplying cracked fuel under low load conditions, and prevents knocking by supplying isomerized fuel under high load conditions. Therefore, the internal combustion engine 1 can produce a large output as required while suppressing fuel consumption.

  Next, fuel reforming control executed by the ECU 60 will be described.

  From the reforming characteristics of the reforming catalyst 6 described with reference to FIG. 3, if the temperature of the reforming catalyst 6 is appropriately controlled, the amount of isomerized fuel produced and the proportion of cracked fuel produced can be adjusted arbitrarily. it can.

  The fuel that flows down from the condenser 12 through the isomerized fuel pipe 22B and accumulates in the isomerized fuel storage tank 20 is a mixed liquid of the isomerized fuel and the unreformed fuel in FIG. Therefore, what is supplied to the internal combustion engine 1 as the isomerized fuel is not the pure isomerized fuel shown in FIG. 3, but a mixed liquid of the isomerized fuel and the unreformed fuel. However, even a mixed liquid has a higher octane number than gasoline fuel in the main fuel storage tank 7. Therefore, here, the fuel stored in the isomerized fuel storage tank 20 is also referred to as isomerized fuel.

  The temperature of the reforming catalyst 6 depends on the exhaust temperature and the exothermic reaction in the catalytic converter 5. In this embodiment, the basic heat supply required for the reforming reaction depends on the heat of the exhaust gas transmitted from the exhaust pipe 70 to the reforming catalyst 6, and the temperature of the reforming catalyst 6 is adjusted by the catalytic converter 5. This is done by controlling the exothermic reaction. When air and fuel are supplied to the reforming catalyst 6, a part of the fuel is oxidized in the reforming catalyst 6 to generate heat of oxidation. As a result, the temperature of the reforming catalyst 6 increases. On the other hand, when only the fuel is supplied to the reforming catalyst 6, the temperature of the reforming catalyst 6 decreases.

  The ECU 60 arbitrarily adjusts the amount of isomerized fuel generated and the generation ratio of cracked fuel by performing the above control.

  FIG. 7 shows a fuel reforming control routine executed by the ECU 60 as a fuel reforming control routine for this purpose. The ECU 60 executes this routine at regular intervals during the operation of the internal combustion engine 1, that is, for example, every second.

  In step S <b> 11, the ECU 60 reads the amount of isomerized fuel in the isomerized fuel storage tank 20 detected by the level sensor 29 and the amount of decomposed fuel in the decomposed fuel storage tank 21 detected by the pressure sensor 34.

  In step S12, the ECU 60 determines whether or not the amount of isomerized fuel in the isomerized fuel storage tank 20 is below a first predetermined amount. The first predetermined amount corresponds to the lower limit value of the storage amount of isomerized fuel. If the amount of isomerized fuel is below the first predetermined amount, the ECU 60 considers that there is a request for increasing the ratio of the isomerization reforming reaction, and performs control for increasing the amount of isomerized fuel generated in step S13. I do.

  Specifically, the ECU 60 closes the air amount control valve 14 in step S13, and injects fuel in the main fuel storage tank 7 from the fuel injector 8 toward the reforming catalyst 6.

  Referring to FIG. 9B, in the ROM of the ECU 60, a characteristic map shown in the figure is stored in advance in order to determine the fuel injection amount of the fuel injector 8 in this case. The ECU 60 determines the fuel injection amount of the fuel injector 8 with reference to this map based on the target engine speed and the target engine load. This map has a characteristic of increasing the fuel injection amount as the target engine load is higher and the target engine speed is higher.

  The ECU 60 outputs a pulse width signal corresponding to the determined fuel injection amount to the fuel injector 8. By this control, the temperature of the reforming catalyst 6 is controlled to the temperature region A in FIG. 3, and as a result, the amount of isomerized fuel generated increases. After the process of step S13, the ECU 60 ends the routine.

  On the other hand, if the amount of isomerized fuel is greater than or equal to the first predetermined amount in step S12, the ECU 60 determines in step S14 whether or not the amount of cracked fuel in the cracked fuel storage tank 21 is less than the second predetermined amount. The second predetermined amount corresponds to the lower limit value of the storage amount of cracked fuel. When the amount of cracked fuel is below the second predetermined amount, the ECU 60 considers that there is a request for increasing the ratio of the cracking reforming reaction, and performs control for increasing the amount of cracked fuel generated in step S15. .

  Specifically, in step S15, the ECU 60 refers to the characteristic map shown in FIG. 9C stored in advance in the ROM, and determines the fuel injection amount of the fuel injector 8 based on the target engine speed and the target engine load. And the air supply amount of the air amount control valve 14 is determined.

  Referring to FIG. 9C, the ECU 60 opens the air amount control valve 14 to supply air to the reforming catalyst 6 under a low load condition where the target engine load converted to the cylinder effective pressure Pe is 5 bar or less. Then, the fuel in the main fuel storage tank 7 is injected from the fuel injector 8 toward the reforming catalyst 6. In this case, the fuel injection amount is a constant value. On the other hand, the air supply amount is determined with reference to the map of FIG. The map has the characteristic that the air supply is increased as the target engine load is lower. The ECU 60 controls the opening degree of the air amount control valve 14 so that the determined air supply amount is realized.

  When the target engine load converted to the in-cylinder effective pressure Pe does not fall below 5 bar, the ECU 60 closes the air amount control valve 14 and directs the fuel in the main fuel storage tank 7 from the fuel injector 8 to the reforming catalyst 6. Spray. The fuel injection amount is determined with reference to the map of FIG. The map has a characteristic that the fuel injection amount increases as the target engine load increases. The ECU 60 outputs a pulse width signal corresponding to the determined fuel injection amount to the fuel injector 8.

  By the control in step S15, the temperature of the reforming catalyst 6 is controlled to the temperature region C in FIG. 3, and as a result, the generation amount of cracked fuel increases. After the process of step S15, the ECU 60 ends the routine.

  If the cracked fuel amount does not fall below the second predetermined amount in step S14, the ECU 60 performs control such that the reforming catalyst 6 induces both isomerized fuel and cracked fuel generation in step S16.

  Specifically, in step S16, the ECU 60 closes the air amount control valve 14 and injects fuel in the main fuel storage tank 7 from the fuel injector 8 toward the reforming catalyst 6. In order to determine the fuel injection amount of the fuel injector 8 in this case, the characteristic map shown in FIG. 9A is stored in the ROM of the ECU 60 in advance.

  The ECU 60 determines the fuel injection amount of the fuel injector 8 with reference to this map based on the target engine speed of the internal combustion engine 1 and the target engine load. This map has a characteristic of increasing the fuel injection amount as the target engine load is higher and the target engine speed is higher. However, as compared with the map of FIG. 9B having the same characteristics, the fuel injection amount is suppressed relatively small with respect to the same target engine speed and the same target engine load. The ECU 60 outputs a pulse width signal corresponding to the determined fuel injection amount to the fuel injector 8.

  By the process of step S16, the temperature of the reforming catalyst 6 is controlled to the temperature region B of FIG. 3, and as a result, the isomerized fuel and the cracked fuel are generated in a well-balanced manner. After the process of step S16, the ECU 60 ends the routine.

  Through the above routine execution of the ECU 60, it is possible to arbitrarily adjust the generation ratio of the high combustion rate cracked fuel and the high octane number isomerized fuel.

  Air supply to the reforming catalyst 6 by the air amount control valve 14 is limited to the low load condition shown in FIG. 9C, and air is not used for the cracking reforming reaction. The content of nitrogen in the cracked fuel is kept low.

  In the high load operation of the internal combustion engine 1 having a high exhaust temperature, the temperature of the reforming catalyst 6 is also high. In this state, when the amount of isomerized fuel falls below the first predetermined amount, in other words, when the process of step S13 is performed in this state, the temperature of the reforming catalyst 6 must be quickly reduced. . This need can be satisfied by increasing and correcting the fuel injection amount of the fuel injector 8 in step S13 and increasing the fuel supply amount per unit time to the reforming catalyst 6.

  On the other hand, in the low load operation of the internal combustion engine 1 having a low exhaust temperature, the temperature of the reforming catalyst 6 is also low. In this state, when the amount of cracked fuel falls below the second predetermined amount, in other words, when the process of step S15 is performed in this state, the temperature of the reforming catalyst 6 must be quickly raised. This need can be satisfied by increasing and correcting the opening of the air amount control valve 14 in step S15 and increasing the amount of air supplied to the reforming catalyst 6 per unit time.

  According to this embodiment, in the fuel supply device that supplies fuel to the internal combustion engine 1, reforming that induces isomerization reforming reaction of raw fuel and decomposition reforming reaction of raw fuel at different ratios according to the catalyst temperature. Catalyst 6, catalyst temperature changing means (fuel injector 8, air amount control valve 14) for changing the catalyst temperature, isomerized fuel generated by isomerization reforming reaction, and cracked fuel generated by cracking reforming reaction Is a programmable controller that controls fuel supply means (main fuel injector 27, isomerized fuel injector 33, cracked fuel injector 35) and catalyst temperature changing means (fuel injector 8, air amount control valve 14) for supplying the fuel to the internal combustion engine 1, respectively. (ECU 60), and the programmable controller (ECU 60) determines whether there is a request for increasing the ratio of the isomerization reforming reaction. In response to a request to increase the ratio of the isomerization reforming reaction (S12), the catalyst temperature changing means (the fuel injector 8, the air amount control valve 14) is controlled so that the catalyst temperature falls below a predetermined temperature (S13). It is determined whether there is a request for increasing the ratio of the reforming reaction (S14). In response to the request for increasing the ratio of the cracking / reforming reaction, the catalyst temperature changing means (fuel injector 8, air) is set so that the catalyst temperature exceeds a predetermined temperature. Since the quantity control valve 14) is controlled (S15), the production ratio of the high octane fuel (isomerized fuel) and the high combustion rate fuel (decomposed fuel) can be arbitrarily changed, The content ratio of nitrogen in the fuel can be reduced.

  Next, a second embodiment of the present invention will be described with reference to FIGS.

  Referring to FIG. 10, this embodiment further includes an electric heater 58 for heating the reforming catalyst 6 in the catalytic converter 5. Therefore, in this embodiment, the fuel injector 8, the air amount control valve 14, and the electric heater 58 constitute a catalyst temperature changing means. Other configurations of the fuel reformer hardware are the same as those in the first embodiment.

  The electric heater 58 is used under the characteristics shown in FIG.

  That is, the electric heater 58 is energized under the low-load operating condition of the internal combustion engine 1 where the temperature of the reforming catalyst 6 is unlikely to rise, and the reforming catalyst 6 is directly heated by the heat generated by the electric heater 58 to raise the catalyst temperature. . The ECU 60 controls energization of the electric heater 58 in parallel with the temperature control of the reforming catalyst 6 by the routine execution of FIG.

  In order to control energization to the electric heater 58, a heater supply power map having the characteristics shown in FIG. This map is set so that the heater supply power increases as the target engine speed is lower and the target engine load is lower. Based on the target engine speed and the target engine load, the ECU 60 refers to this map to determine the heater power supply and supplies the determined power to the electric heater 58.

  According to this embodiment, the temperature increase control of the reforming catalyst 6 can be performed in a shorter time, particularly at a low temperature.

  Next, a third embodiment of the present invention will be described with reference to FIG. 12, FIG. 13 and FIG.

  Referring to FIG. 13, in this embodiment, the internal combustion engine 1 includes a sub-combustion chamber 50 in the cylinder head 40 adjacent to a combustion chamber (hereinafter referred to as a main combustion chamber) 45 of each cylinder.

  The volume of the auxiliary combustion chamber 50 is set smaller than the volume of the main combustion chamber 45. The auxiliary combustion chamber 50 and the main combustion chamber 45 communicate with each other through an injection hole 52 formed in the cylinder head 40.

  The internal combustion engine 1 further includes a second cracked fuel injector 36 facing the auxiliary combustion chamber 50 in the cylinder head 40. The second cracked fuel injector 36 injects cracked fuel from the cracked fuel storage tank 21 into the auxiliary combustion chamber 50.

  In this embodiment, the internal combustion engine 1 further moves the spark plug 51 provided on the cylinder head 40 facing the main combustion chamber 45 to the position facing the sub-combustion chamber 50 in the first embodiment. Yes.

  Referring to FIG. 12, the second cracked fuel injector 36 injects an amount of cracked fuel corresponding to the pulse width modulation signal from the ECU 60 into the auxiliary combustion chamber 50.

  As in the first embodiment, the intake air that has passed through the air cleaner is sucked into the main combustion chamber 45 through the intake collector 2, the intake branch pipe 3, the intake port 46, and the intake valve 43. The spark plug 51 ignites the cracked fuel in the auxiliary combustion chamber 50 in accordance with an ignition signal output from the ECU 60. The ignition timing is the second half of the compression stroke of the piston or the first half of the expansion stroke.

  The high combustion rate cracked fuel ignited in the sub-combustion chamber 50 causes a substantially columnar torch flame to be ejected from the nozzle holes 52 into the main combustion chamber 45 to burn the air-fuel mixture in the main combustion chamber 45.

  Next, fuel supply control to the main combustion chamber 45 and the sub-combustion chamber 50 performed by the ECU 60 will be described with reference to FIGS.

  Regarding the fuel supply control to the main combustion chamber 45, the ECU 60 refers to the characteristic map shown in FIG. 14A that is substantially the same as FIG. 8 of the first embodiment, and sets the target engine speed and the target engine. The injection amounts of the main fuel, isomerized fuel, and cracked fuel by the fuel injectors 27, 33, and 35 are controlled according to the load.

  Further, in this embodiment, the ECU 60 refers to the characteristic map shown in FIG. 14B together with the injection of cracked fuel by the first cracked fuel injector 35 under the low load condition where the in-cylinder effective pressure Pe is less than 5 bar. Then, the cracked fuel is injected into the auxiliary combustion chamber 50 by the second cracked fuel injector 36. In this case, the injection amount of the cracked fuel of the second cracked fuel injector 36 is extremely smaller than the injection amount of the first cracked fuel injector 35 and is proportional to the injection amount of the first cracked fuel injector 35. Therefore, the amount of cracked fuel injected by the second cracked fuel injector 36 also increases as the target engine load decreases. When the in-cylinder effective pressure Pe does not fall below 5 bar, the cracked fuel is not injected by the second cracked fuel injector 36.

  As described above, in this embodiment, the fuel mixture in the main combustion chamber 45 is supplied to the auxiliary combustion chamber 50 only when the internal combustion engine 1 is under a low load, and the flame in the main combustion chamber 45 is ejected from the injection holes 52. To burn. Therefore, the stability of the combustion of the air-fuel mixture in the main combustion chamber 45 under low load conditions can be further enhanced than in the first embodiment.

  As mentioned above, although this invention has been demonstrated through some specific embodiment, this invention is not limited to each said embodiment. It is possible for those skilled in the art to make various modifications or changes to these embodiments within the scope of the claims.

  For example, in each of the above-described embodiments, the processes in steps S13 to S15 are performed based on the target engine speed of the internal combustion engine 1 and the target engine load. However, the processing in steps S13 to S15 can be performed based on the actual engine speed of the internal combustion engine 1 and the actual engine load.

Schematic configuration diagram of a fuel supply apparatus according to the present invention Perspective view of the inside of a catalytic converter that forms part of the fuel supply system The figure which shows the relationship between the catalyst temperature and the conversion rate of the catalytic converter Perspective view of the inside of the condenser that forms part of the fuel supply system Schematic configuration diagram of a fuel supply system to an internal combustion engine that forms part of the fuel supply device Flow chart of fuel injection control routine Flow chart of fuel reforming control routine The figure explaining the characteristic of the fuel map supplied to an internal combustion engine The figure explaining the characteristic of the operation mode map of the catalytic converter FIG. 2 is a view similar to FIG. 2 but showing a second embodiment of the present invention. The figure explaining the characteristic of the electric power supply map to the electric heater in 2nd Embodiment FIG. 1 is similar to FIG. 1 but shows a third embodiment of the present invention. The schematic block diagram of the fuel supply system to the internal combustion engine in 3rd Embodiment The figure explaining the characteristic of the fuel map supplied to the internal combustion engine in 3rd Embodiment

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 Intake collector 3 Intake branch pipe 4 Exhaust branch pipe 5 Catalytic converter 5A Housing 6 Reforming catalyst 7 Main fuel storage tank 8 Fuel injector 9 Fuel supply pipe 10 Fuel pump 11 Reformed gas pipe 12 Condenser 13 Air supply pipe 14 Air amount control valve 15 Air flow meter 16 Thermocouple 17 Radiator 18 Cooling water pipe 19 Pump 20 Isomerized fuel storage tank 21 Decomposed fuel storage tank 22A Decomposed fuel pipe 22B Isomerized fuel pipe 23 Compressor 25 Main fuel supply pump 26 Main fuel pipe 27 Main fuel injector 28 Level sensor 29 Level sensor 30 Fuel pump 31 Fuel supply pipe 33 Isomerized fuel injector 34 Pressure sensor 35 Cracked fuel injector 36 Second cracked fuel injector 37 Cracked fuel supply pipe 40 Cylinder head 41 Cylinder block 42 Pis Ton 43 Intake valve 44 Exhaust valve 45 Combustion chamber (main combustion chamber)
46 Intake port 47 Exhaust port 48 Intake valve cam 49 Exhaust valve cam 50 Sub chamber 51 Spark plug 52 Injection hole 55 Crank angle sensor 56 Water temperature sensor 57 Accelerator opening sensor 58 Heater 60 Engine control unit (ECU)
70 Exhaust pipe

Claims (32)

In a fuel supply device for supplying fuel to an internal combustion engine,
A reforming catalyst that induces the isomerization reforming reaction of the raw fuel and the cracking reforming reaction of the raw fuel at different ratios depending on the catalyst temperature;
A catalyst temperature changing means for changing the catalyst temperature;
Fuel supply means for supplying the isomerized fuel produced by the isomerization reforming reaction and the cracked fuel produced by the cracking reforming reaction to the internal combustion engine, respectively;
A programmable controller for controlling the catalyst temperature changing means,
The programmable controller determines whether there is a request for increasing the ratio of the isomerization reforming reaction, and provides a catalyst temperature changing means so that the catalyst temperature falls below a predetermined temperature in response to the request for increasing the ratio of the isomerization reforming reaction. To determine whether there is a request for increasing the ratio of the cracking reforming reaction, and to control the catalyst temperature changing means so that the catalyst temperature exceeds a predetermined temperature in response to the request for increasing the ratio of the cracking reforming reaction. A fuel supply device for an internal combustion engine, which is programmed. 2. The fuel supply apparatus for an internal combustion engine according to claim 1, wherein the fuel is gasoline containing heptane, and the isomerization reforming reaction and the cracking reforming reaction are each expressed by the following equations.
Isomerization reforming reaction:
Heptane (C ₇ H ₁₆ ) → 2-methylhexane (C ₇ H ₁₆ )
Decomposition and reforming reaction:
Heptane (C ₇ H ₁₆ ) → hydrogen (H ₂ ) + ethylene (C ₂ H ₄ ) + 1-pentene (C ₅ H ₁₀ ) The catalyst temperature changing means includes a fuel injector that injects raw fuel toward the reforming catalyst,
3. The fuel supply device for an internal combustion engine according to claim 1, wherein the programmable controller is further programmed to control the catalyst temperature by adjusting the fuel injection amount of the fuel injector.   The programmable controller increases the fuel injection amount of the fuel injector as the rotational speed of the internal combustion engine increases or the load of the internal combustion engine increases when it is determined that there is a request for increasing the ratio of the cracking reforming reaction. The fuel supply device for an internal combustion engine according to claim 3, further programmed so as to cause the fuel to flow.   When the programmable controller does not determine that there is a request for increasing the ratio of the isomerization reforming reaction and does not determine that there is a request for increasing the ratio of the cracking reforming reaction, the request for increasing the ratio of the isomerization reforming reaction The fuel injection amount of the fuel injector is increased as the rotational speed of the internal combustion engine is increased or the load of the internal combustion engine is increased while suppressing the fuel injection amount of the fuel injector to be smaller than when it is determined that The fuel supply device for an internal combustion engine according to claim 4, further programmed. The catalyst temperature changing means further includes an air amount adjuster for adjusting the amount of air supplied to the reforming catalyst,
The programmable controller adjusts the amount of fuel supplied to the reforming catalyst via the fuel injector, and controls the catalyst temperature by adjusting the amount of air supplied to the reforming catalyst via the air amount regulator. The fuel supply device for an internal combustion engine according to any one of claims 3 to 5, further programmed.   The internal combustion engine according to claim 6, wherein the programmable controller is further programmed not to perform air supply by the air amount regulator unless it is determined that there is a request for increasing the ratio of the cracking reforming reaction. Fuel supply device.   When it is determined that there is a request for increasing the ratio of the cracking reforming reaction, and the load of the internal combustion engine is smaller than the predetermined load, the programmable controller causes the air amount regulator to supply air and the fuel injector to inject fuel. The fuel supply device for an internal combustion engine according to claim 7, further programmed so as to cause   9. The fuel supply device for an internal combustion engine according to claim 8, wherein the programmable controller is further programmed to increase an air supply amount by an air amount regulator as a load of the internal combustion engine decreases.   When the programmable controller determines that there is a request for increasing the ratio of the cracking reforming reaction and the load of the internal combustion engine is not smaller than the predetermined load, the air controller does not supply air, 10. The internal combustion engine of claim 8, further programmed to increase the fuel injection amount of the fuel injector as the rotational speed increases or as the load of the internal combustion engine increases. Fuel supply device.   When it is determined that there is a request for increasing the ratio of the isomerization reforming reaction, the programmable controller does not determine whether there is a request for increasing the ratio of the cracking reforming reaction. The fuel supply device for an internal combustion engine according to any one of claims 1 to 3, further programmed to control the catalyst temperature changing means so as to adjust.   The predetermined temperature is a temperature at which the reforming catalyst induces an isomerization reforming reaction and a cracking reforming reaction, and the programmable controller requests a ratio increase request for the isomerization reforming reaction and a ratio increase request for the cracking reforming reaction. 4. If none of the above is determined to be present, further programming is performed to control the catalyst temperature changing means to maintain the catalyst temperature at a predetermined temperature. The fuel supply device for an internal combustion engine according to any one of the above.   The predetermined temperature is set to around 500K, and when the programmable controller determines that there is a request for increasing the ratio of the isomerization reforming reaction, the programmable temperature change means is configured to adjust the catalyst temperature to around 450K. And further programmed to control the catalyst temperature changing means to adjust the catalyst temperature to around 550 K when it is determined that there is a request to increase the ratio of the cracking reforming reaction. The fuel supply device for an internal combustion engine according to claim 12.   The programmable controller further includes an electric heater for heating the reforming catalyst, and the programmable controller further increases the power supplied to the electric heater as the rotational speed of the internal combustion engine decreases or the load on the internal combustion engine decreases. 14. The fuel supply device according to claim 1, wherein the fuel supply device is programmed.   The internal combustion engine further includes an exhaust pipe for discharging exhaust gas generated by the combustion of fuel, and the reforming catalyst is disposed at a position in thermal contact with the exhaust pipe. A fuel supply device for an internal combustion engine according to claim 1.   16. The fuel supply device for an internal combustion engine according to claim 15, wherein the reforming catalyst is formed in a columnar shape having a through hole that penetrates the exhaust pipe in the axial direction.   The fuel supply device for an internal combustion engine according to any one of claims 1 to 16, further comprising an isomerized fuel storage tank for storing isomerized fuel.   A sensor for detecting the amount of isomerized fuel stored in the isomerized fuel storage tank is further provided, and the programmable controller has a request for increasing the ratio of the isomerization reforming reaction when the amount of isomerized fuel stored falls below a predetermined amount. 18. The fuel supply system for an internal combustion engine according to claim 17, further programmed to determine.   The fuel supply apparatus for an internal combustion engine according to any one of claims 1 to 18, further comprising a cracked fuel storage tank for storing cracked fuel.   A sensor is further provided for detecting the amount of cracked fuel stored in the cracked fuel storage tank, and the programmable controller determines that there is a request for increasing the ratio of the cracking reforming reaction when the amount of stored cracked fuel falls below a predetermined amount. 20. The fuel supply device for an internal combustion engine according to claim 19, further programmed.   The programmable controller is further programmed to control the fuel supply means to change the supply ratio of isomerized fuel and cracked fuel to the internal combustion engine based on the operating state of the internal combustion engine. The fuel supply device for an internal combustion engine according to any one of claims 1 to 20.   The operating state is a target engine speed and a target engine load of the internal combustion engine, and the programmable controller determines whether the operating state corresponds to a low rotational speed / high load region, and the operating state is low rotational speed / high 24. The method according to claim 21, further comprising: controlling the fuel supply means so as to increase the supply ratio of the isomerized fuel to the internal combustion engine when it is determined that the fuel supply means corresponds to the load region. Fuel supply device for internal combustion engine.   23. The fuel supply device for an internal combustion engine according to claim 22, wherein the low rotational speed / high load region is a region where the engine rotational speed is lower than 4000 rpm and the in-cylinder effective pressure is higher than 9 bar.   The programmable controller determines whether the internal combustion engine is operating in a low load region, and increases the supply of cracked fuel to the internal combustion engine if it is determined that the internal combustion engine is operating in a low load region 24. The fuel supply apparatus for an internal combustion engine according to any one of claims 21 to 23, further programmed to control the fuel supply means.   25. The fuel supply device for an internal combustion engine according to claim 24, wherein the low load region is a region where the effective cylinder pressure is lower than 5 bar.   The programmable controller is further programmed to control the fuel supply means to decrease the supply of cracked fuel to the internal combustion engine as the internal combustion engine increases engine load in a low load region. The fuel supply device for an internal combustion engine according to claim 24 or 25.   The programmable controller supplies both the isomerized fuel and the cracked fuel to the internal combustion engine when it is determined that the internal combustion engine is not operated in the low rotation speed / high load region or the low load region. 27. The internal combustion engine according to claim 26, further programmed to control the fuel supply means so as to decrease the supply ratio of cracked fuel relative to the supply ratio of isomerized fuel as the load of the fuel increases. Fuel supply system.   The internal combustion engine includes a plurality of combustion chambers and an intake collector that distributes air to the combustion chambers. The fuel supply means includes a main fuel injector provided for each combustion chamber that supplies raw fuel to the combustion chambers, and isomerization. The internal combustion engine according to any one of claims 1 to 27, further comprising: an isomerized fuel injector that injects fuel into an intake collector; and a decomposed fuel injector that supplies decomposed fuel to the intake collector. Fuel supply system.   The internal combustion engine further includes a sub-combustion chamber having a smaller volume than the combustion chamber, an injection hole connecting the combustion chamber and the sub-combustion chamber, and ignition means provided facing the sub-combustion chamber, and the fuel supply means is the cracked fuel 30. The fuel supply apparatus for an internal combustion engine according to claim 28, further comprising a second cracked fuel injector for supplying the fuel to the auxiliary combustion chamber.   The programmable controller determines whether or not the internal combustion engine is operated in a low load region, and if the internal combustion engine is not operated in a low load region, the second cracked fuel injector causes the cracked fuel to be injected into the auxiliary combustion chamber. 30. The fuel supply apparatus for an internal combustion engine according to claim 29, further programmed so as not to perform the injection of.   When it is determined that the internal combustion engine is operating in the low load region, the programmable controller increases the supply amount of cracked fuel to the sub-combustion chamber as the load of the internal combustion engine decreases. 31. The fuel supply apparatus for an internal combustion engine according to claim 30, further programmed to control the two cracked fuel injectors. A reforming catalyst that induces the isomerization reforming reaction of the raw fuel and the cracking reforming reaction of the raw fuel at different ratios depending on the catalyst temperature;
A catalyst temperature changing means for changing the catalyst temperature;
Fuel supply means for supplying the isomerized fuel produced by the isomerization reforming reaction and the cracked fuel produced by the cracking reforming reaction to the internal combustion engine, respectively;
In a control method of a fuel supply device comprising:
Determine if there is a demand for increased ratio of isomerization reforming reaction,
In response to a request for increasing the ratio of the isomerization reforming reaction, the catalyst temperature changing means is controlled so that the catalyst temperature falls below a predetermined temperature,
Determine whether there is a request to increase the ratio of cracking reforming reaction,
A control method for a fuel supply device of an internal combustion engine, wherein the catalyst temperature changing means is controlled so that the catalyst temperature exceeds a predetermined temperature in response to a request for increasing the ratio of the cracking and reforming reaction.

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