JP2011007112A - Controller of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To change a reforming condition of the fuel properly in accordance with the operating condition of the engine in a system to reform the fuel by casting the energy into the fuel for decomposing hydrocarbon molecules in the fuel.SOLUTION: An input energy calculation part 41 selects a proper reforming mode to the engine operating condition among a first reforming mode (the fuel not reformed in the mode), a second reforming mode (in the mode the fuel is reformed by decomposing hydrocarbon molecules of olefin series having many carbon atoms contained in the fuel), and a third reforming mode (in the mode, the fuel is reformed by decomposing all hydrocarbon molecules in the fuel), and calculates an input energy amount required to achieve the selected reforming mode. An input energy control part 42 controls a driving voltage of an ultrasonic radiation device 40 so as to achieve the required input energy amount. Thereby the reformed condition of the fuel is changed according to the energy amount by changing the energy amount to be cast into the fuel in accordance with the engine operating condition.

Description

  The present invention relates to an internal combustion engine control device having a function of reforming fuel by decomposing hydrocarbon molecules in the fuel by inputting energy into the fuel of the internal combustion engine.

  As a technique for reforming the fuel of an internal combustion engine, for example, as described in Patent Document 1 (Japanese Patent Laid-Open No. 2003-90239), the amount of aldehyde is obtained by igniting an air-fuel mixture with a spark plug. In some cases, the fuel is reformed so as to increase the ignitability.

  Further, as described in Patent Document 2 (Japanese Patent Application Laid-Open No. 2004-162586), the fuel is pressurized and heated to a supercritical state, and the fuel in the supercritical state is brought into contact with the reforming catalyst. In some cases, a high-boiling component (heavy component) in the fuel is converted into a low-boiling component (light component) to reform the fuel.

JP 2003-90239 A (second page, etc.) JP 2004-162586 A (2nd page, etc.)

  By the way, the inventor of the present invention inputs energy (for example, ultrasonic energy) to the fuel, dissociates the bonds of hydrocarbon molecules in the fuel, decomposes the hydrocarbon molecules into molecules with fewer carbon atoms, We are researching a system for reforming fuel by changing the properties and composition of the fuel. The following new problems were found during the research process.

  The fuel contains olefinic hydrocarbon molecules and paraffinic hydrocarbon molecules, but olefinic hydrocarbon molecules with double bonds are more paraffinic than paraffinic hydrocarbon molecules without double bonds. However, since the combustibility is poor, if the fuel contains a large amount of olefinic hydrocarbon molecules, the combustibility of the fuel deteriorates when the internal combustion engine is cold, and smoke is likely to be generated. In such a region where smoke is likely to be generated, it is preferable to suppress the generation of smoke by reducing the number of olefinic hydrocarbon molecules in the fuel by reforming the fuel.

  In addition, when the internal combustion engine is operated at a high speed and a high load, the external EGR amount (exhaust gas amount recirculated to the intake side) and the internal EGR amount (exhaust gas amount remaining in the cylinder) increase, resulting in deterioration of combustibility. In areas where there is a concern, the reforming of fuel breaks down all hydrocarbon molecules in the fuel into molecules with fewer carbon atoms, reducing the number of hydrocarbon molecules with more carbon atoms to improve the ignitability and combustibility of the fuel. It is preferable to improve.

  Further, in an area where there is little generation of smoke and there is little possibility of deterioration in combustibility, it is preferable to save energy input to the fuel without reforming the fuel. When the fuel is reformed to improve the ignitability, knocking is likely to occur. Therefore, it is preferable not to reform the fuel, particularly in a knock region such as during low-speed / high-load operation.

  In order to meet these demands, it is necessary to change the reforming state of the fuel (for example, the presence or absence of reforming, the type of hydrocarbon molecules to be decomposed, etc.) according to the operating state of the internal combustion engine. Then, the reforming state of the fuel cannot be changed according to the operating state of the internal combustion engine.

  Accordingly, an object of the present invention is to provide a control device for an internal combustion engine that can change the reforming state of the fuel in accordance with the operating state of the internal combustion engine.

  In order to solve the above-mentioned problems, an invention according to claim 1 is directed to an internal combustion engine provided with fuel reforming means for reforming fuel by decomposing hydrocarbon molecules in the fuel by introducing energy into the fuel of the internal combustion engine. In the engine control device, the input energy calculation means for calculating the amount of energy input to the fuel by the fuel reforming means (hereinafter referred to as “input energy amount”) based on the operating state of the internal combustion engine, and the input energy calculation means The input energy control means for controlling the fuel reforming means so as to realize the input energy amount is provided.

  Focusing on the fact that the reforming state of the fuel (for example, the presence or absence of reforming, the type of hydrocarbon molecules to be decomposed, etc.) changes according to the amount of energy input to the fuel, the operation of the internal combustion engine as in the present invention. If the input energy amount is calculated based on the state (for example, engine speed, engine load, cooling water temperature, external EGR amount, internal EGR amount, etc.) and the fuel reforming means is controlled to realize this input energy amount The amount of energy input to the fuel can be changed according to the operating state of the internal combustion engine, and the reforming state of the fuel can be changed according to the amount of energy. Thereby, the reforming state of the fuel can be appropriately changed according to the operating state of the internal combustion engine.

  In this case, as in claim 2, an ultrasonic irradiation device that irradiates ultrasonic waves is used as the fuel reforming means, and the fuel molecules are irradiated with ultrasonic waves by the ultrasonic irradiation device, so that hydrocarbon molecules in the fuel are removed. You may make it thermally decompose. That is, by irradiating the fuel in the fuel tank or the fuel passage with ultrasonic waves, bubbles (cavitation) are generated in the fuel, and hydrocarbon molecules in the fuel are generated by the high-temperature and high-pressure field generated when the bubbles are compressed and collapsed. Can be pyrolyzed. In this case, by changing the drive voltage of the vibrator that generates ultrasonic waves, the amplitude of the ultrasonic waves can be changed to change the energy input to the fuel.

  Alternatively, as described in claim 3, an ignition plug of an internal combustion engine is used as the fuel reforming means, and the spark plug discharges plasma into a mixture of fuel and air to ionize hydrocarbon molecules in the fuel. It may be disassembled. In this way, the spark plug can be used as the fuel reforming means, and it is not necessary to newly provide the fuel reforming means, and meet the demand for cost reduction, which is an important technical issue in recent years. Can do. In this case, the energy input to the fuel can be changed by changing the discharge power of the spark plug.

  Alternatively, as the fuel reforming means, a variable valve device (for example, a variable valve timing device, a variable valve lift device, etc.) that changes at least the opening / closing timing of the intake valve and / or the exhaust valve of the internal combustion engine as the fuel reforming means. And a fuel injection valve that injects fuel into the cylinder, and this variable valve device provides a negative valve overlap period in which both the exhaust valve and the intake valve are closed in the latter half of the exhaust stroke. The hydrocarbon molecules in the fuel may be thermally decomposed by injecting the fuel into the cylinder by the fuel injection valve during the overlap period. During the negative valve overlap period, the high-temperature combustion gas remaining in the cylinder is compressed by the rise of the piston in the latter half of the exhaust stroke, so that the cylinder is in a high temperature and high pressure state. If some or all of the fuel injected in one cycle is injected into the cylinder within this negative valve overlap period, the fuel injected into the cylinder is exposed to high temperature and high pressure gas in the cylinder. The hydrocarbon molecules in the fuel injected into the fuel can be pyrolyzed. In this way, the variable valve device and the fuel injection valve can be used as the fuel reforming means, and it is not necessary to newly provide the fuel reforming means. Can meet the demands of. In this case, the negative valve overlap period is changed by changing the opening and closing timing of the intake valve and exhaust valve, thereby changing the compression ratio of the combustion gas remaining in the cylinder and changing the maximum temperature in the cylinder. The energy input to the fuel can be changed.

  As mentioned above, the fuel contains olefinic hydrocarbon molecules and paraffinic hydrocarbon molecules, but olefinic hydrocarbon molecules with double bonds are paraffinic without double bonds. Because the flammability is worse than that of hydrocarbon molecules, if the fuel contains many olefinic hydrocarbon molecules, the flammability of the fuel deteriorates and the smoke tends to be generated when the internal combustion engine is cold. Become. Here, there is a characteristic that the binding energy of olefinic hydrocarbon molecules is smaller than the binding energy of paraffinic hydrocarbon molecules. Further, there is a characteristic that the binding energy of a hydrocarbon molecule having a large number of carbon atoms is smaller than the binding energy of a hydrocarbon molecule having a small number of carbon atoms. Therefore, as in claim 5, the amount of input energy is calculated based on the characteristics of the binding energy of hydrocarbon molecules in the fuel so as to decompose hydrocarbon molecules having a large number of carbon atoms in the olefin system in the fuel. good.

  Because of the former characteristic (the characteristic that the binding energy of olefinic hydrocarbon molecules is smaller than the binding energy of paraffinic hydrocarbon molecules), the binding energy of olefinic hydrocarbon molecules and paraffinic hydrocarbon molecules By calculating the intermediate value of the binding energy of the fuel as the amount of input energy and putting the energy into the fuel, it is larger than the binding energy of the olefinic hydrocarbon molecules and smaller than the binding energy of the paraffinic hydrocarbon molecules. Energy can be input and olefinic hydrocarbon molecules can be decomposed without decomposing paraffinic hydrocarbon molecules, thereby reducing olefinic without reducing paraffinic hydrocarbon molecules. It is possible to reduce only the hydrocarbon molecules.

  In this case, from the latter characteristic (characteristic that the binding energy of hydrocarbon molecules with a large number of carbon atoms is smaller than the binding energy of hydrocarbon molecules with a small number of carbon atoms), depending on the number of carbon atoms, The binding energy may be larger than the binding energy of paraffinic hydrocarbon molecules, but at least in the range of the number of carbons contained in the fuel (for example, gasoline) of the internal combustion engine (for example, about 4 to 12), The magnitude relationship of the binding energy is not reversed (that is, the binding energy of the olefinic hydrocarbon molecule is not greater than the binding energy of the paraffinic hydrocarbon molecule). Furthermore, because of the latter characteristics, olefinic hydrocarbon molecules with a large number of carbon atoms are more likely to be decomposed than olefinic hydrocarbon molecules with a small number of carbon atoms, which increases the proportion of hydrocarbon molecules with a small number of carbon atoms. In addition, it is possible to improve ignitability and combustion stability.

  Further, as in claim 6, based on the operating state of the internal combustion engine, the first reforming mode in which the fuel is not reformed, and the olefin-based hydrocarbon molecules in the fuel are decomposed to decompose the fuel molecules. One reforming mode is selected from the second reforming mode for reforming and the third reforming mode for reforming the fuel by decomposing all the hydrocarbon molecules in the fuel. The input energy amount may be calculated according to the quality mode. In this way, it is necessary to select an appropriate reforming mode according to the operating state of the internal combustion engine from the first to third reforming modes and realize the selected reforming mode. The amount of input energy can be calculated.

  Furthermore, as in claim 7, it may be configured to include a control parameter changing means for changing the control parameter of the internal combustion engine in accordance with the reforming mode selected by the input energy calculating means. In this way, the control parameters of the internal combustion engine (for example, fuel injection timing, EGR valve opening, intake valve / exhaust valve opening / closing timing, etc.) are set to appropriate values corresponding to the selected reforming mode. Can do.

  Further, in a system including a variable valve device (for example, a variable valve timing device, a variable valve lift device, etc.) that changes at least the opening / closing timing of an intake valve and / or an exhaust valve of an internal combustion engine as in claim 8 Fuel reforming is performed when the valve overlap period in which both the exhaust valve and the intake valve are opened by the valve device becomes long and the amount of remaining exhaust gas increases by being blown back into the cylinder. The amount of input energy may be calculated. In this way, when the variable valve device increases the internal EGR amount (exhaust gas amount remaining in the cylinder) and there is a concern about deterioration of fuel combustibility, the fuel is reformed to reduce the amount of fuel. Ignition and flammability can be improved.

  Further, in the system including the exhaust gas recirculation device that recirculates a part of the exhaust gas of the internal combustion engine to the intake side as in claim 9, the amount of exhaust gas recirculated to the intake side by the exhaust gas recirculation device increases. Sometimes, the amount of input energy may be calculated so as to reform the fuel. In this way, when the exhaust gas recirculation device increases the amount of external EGR (the amount of exhaust gas recirculated to the intake side) and there is a concern about deterioration of fuel combustibility, fuel reforming is performed. The ignitability and combustibility of the fuel can be improved.

FIG. 1 is a diagram showing a schematic configuration of an engine control system in Embodiment 1 of the present invention. FIG. 2 is a diagram illustrating a schematic configuration of the fuel reforming system according to the first embodiment. FIG. 3 is a flowchart for explaining the flow of processing of the fuel reforming routine of the first embodiment. FIG. 4 is a flowchart for explaining the processing flow of the reforming mode determination routine of the first embodiment. FIG. 5 is a flowchart for explaining the processing flow of the reforming mode determination routine of the second embodiment. FIG. 6 is a diagram showing a schematic configuration of a fuel reforming system according to another embodiment.

  Hereinafter, some embodiments embodying the mode for carrying out the present invention will be described.

A first embodiment of the present invention will be described with reference to FIGS.
First, a schematic configuration of the entire engine control system will be described with reference to FIG.
An air cleaner 13 is provided at the most upstream portion of the intake pipe 12 of the engine 11 that is an internal combustion engine, and an air flow meter 14 that detects the intake air amount is provided downstream of the air cleaner 13. A throttle valve 16 whose opening is adjusted by a motor 15 and a throttle opening sensor 17 that detects the opening (throttle opening) of the throttle valve 16 are provided on the downstream side of the air flow meter 14.

  Further, a surge tank 18 is provided on the downstream side of the throttle valve 16, and an intake pipe pressure sensor 19 for detecting the intake pipe pressure is provided in the surge tank 18. The surge tank 18 is provided with an intake manifold 20 that introduces air into each cylinder of the engine 11, and a fuel injection valve that injects fuel toward the intake port in the vicinity of the intake port of the intake manifold 20 of each cylinder. 21 is attached. An ignition plug 22 is attached to the cylinder head of the engine 11 for each cylinder, and the air-fuel mixture in the cylinder is ignited by spark discharge of the ignition plug 22 of each cylinder.

  The engine 11 includes an intake side variable valve timing device 33 (variable valve device) that changes the valve timing (opening / closing timing) of the intake valve 31 and an exhaust side variable valve timing device 34 that changes the valve timing of the exhaust valve 32. (Variable valve device).

  On the other hand, the exhaust pipe 23 of the engine 11 is provided with an exhaust gas sensor 24 (air-fuel ratio sensor, oxygen sensor, etc.) for detecting the air-fuel ratio or rich / lean of the exhaust gas. A catalyst 25 such as a three-way catalyst for purifying gas is provided.

  Between the upstream side of the exhaust gas sensor 24 in the exhaust pipe 23 and the surge tank 18 on the downstream side of the throttle valve 16 in the intake pipe 12, an EGR pipe for returning a part of the exhaust gas to the intake side 35 is connected, and an EGR valve 36 for adjusting the external EGR amount (the amount of exhaust gas recirculated to the intake side) is provided in the middle of the EGR pipe 35. An EGR device 37 (exhaust gas recirculation device) is constituted by the EGR pipe 35, the EGR valve 36, and the like.

  A cooling water temperature sensor 26 that detects the cooling water temperature and a knock sensor 27 that detects knocking are attached to the cylinder block of the engine 11. A crank angle sensor 29 that outputs a pulse signal every time the crankshaft 28 rotates by a predetermined crank angle is attached to the outer peripheral side of the crankshaft 28, and the crank angle and the engine are determined based on the output signal of the crank angle sensor 29. The rotation speed is detected.

  Outputs of these various sensors are input to a control circuit (hereinafter referred to as “ECU”) 30. The ECU 30 is mainly composed of a microcomputer, and executes various engine control programs stored in a built-in ROM (storage medium) so that the fuel injection amount of the fuel injection valve 21 can be determined according to the engine operating state. The ignition timing of the spark plug 22 is controlled.

Next, a schematic configuration of the fuel reforming system will be described with reference to FIG.
A fuel pump (not shown) for pumping up fuel is provided in the fuel tank 38 for storing fuel, and fuel discharged from the fuel pump passes through the fuel pipe 39 and the fuel injection valve 21 of the engine 11 (see FIG. 1). ). Further, an ultrasonic irradiation device 40 (fuel reforming means) for irradiating the fuel in the fuel tank 38 with ultrasonic waves is provided. The ultrasonic irradiation device 40 irradiates the fuel in the fuel tank 38 with ultrasonic waves to generate bubbles (cavitation) in the fuel, and the hydrocarbons in the fuel are generated by a high-temperature and high-pressure field generated when the bubbles are compressed and collapsed. The fuel is reformed by pyrolyzing the molecules (dissociating the bonds of the hydrocarbon molecules to decompose the hydrocarbon molecules into molecules with fewer carbon atoms, thereby changing the properties and composition of the fuel). In this case, by changing the driving voltage of the vibrator that generates ultrasonic waves, the amplitude of the ultrasonic waves can be changed to change the energy input to the fuel.

  In the first embodiment, paying attention to the fact that the reforming state of the fuel (for example, the presence or absence of reforming, the type of hydrocarbon molecules to be decomposed, etc.) changes according to the amount of energy input to the fuel, the input energy of the ECU 30 The calculation unit 41 (input energy calculation means) calculates the amount of energy (hereinafter referred to as “input energy amount”) that is input to the fuel by the ultrasonic irradiation device 40 based on the engine operating state, and the input energy of the ultrasonic irradiation device 40 is calculated. The control unit 42 (input energy control means) controls the drive voltage (drive voltage of the vibrator) of the ultrasonic irradiation device 40 so as to realize the input energy amount calculated by the input energy calculation unit 41. Thus, the amount of energy input to the fuel is changed according to the engine operating state, and the reformed state of the fuel is changed according to the amount of energy. In addition, it is good also as a structure which gave the function of the input energy calculation part 41 to the control circuit different from ECU30.

  The fuel contains olefinic hydrocarbon molecules and paraffinic hydrocarbon molecules, but olefinic hydrocarbon molecules with double bonds are more paraffinic than paraffinic hydrocarbon molecules without double bonds. However, since the combustibility is poor, if the fuel contains a lot of olefinic hydrocarbon molecules, the combustibility of the fuel deteriorates when the engine 11 is cold, and smoke is likely to be generated. Here, there is a characteristic that the binding energy of olefinic hydrocarbon molecules is smaller than the binding energy of paraffinic hydrocarbon molecules. Further, there is a characteristic that the binding energy of a hydrocarbon molecule having a large number of carbon atoms is smaller than the binding energy of a hydrocarbon molecule having a small number of carbon atoms.

  Because of the former characteristic (the characteristic that the binding energy of olefinic hydrocarbon molecules is smaller than the binding energy of paraffinic hydrocarbon molecules), the binding energy of olefinic hydrocarbon molecules and paraffinic hydrocarbon molecules By calculating the intermediate value of the binding energy of the fuel as the amount of input energy and putting the energy into the fuel, it is larger than the binding energy of the olefinic hydrocarbon molecules and smaller than the binding energy of the paraffinic hydrocarbon molecules. Energy can be input and olefinic hydrocarbon molecules can be decomposed without decomposing paraffinic hydrocarbon molecules, thereby reducing olefinic without reducing paraffinic hydrocarbon molecules. It is possible to reduce only the hydrocarbon molecules.

  In this case, from the latter characteristic (characteristic that the binding energy of hydrocarbon molecules with a large number of carbon atoms is smaller than the binding energy of hydrocarbon molecules with a small number of carbon atoms), depending on the number of carbon atoms, The binding energy may be larger than the binding energy of paraffinic hydrocarbon molecules, but at least in the range of the number of carbons contained in the fuel (for example, gasoline) of the engine 11 (for example, about 4 to 12), The magnitude relationship of the binding energy is not reversed (that is, the binding energy of the olefinic hydrocarbon molecule is not greater than the binding energy of the paraffinic hydrocarbon molecule). Furthermore, because of the latter characteristics, olefinic hydrocarbon molecules with a large number of carbon atoms are more likely to be decomposed than olefinic hydrocarbon molecules with a small number of carbon atoms, which increases the proportion of hydrocarbon molecules with a small number of carbon atoms. In addition, it is possible to improve ignitability and combustion stability.

  In the first embodiment, the input energy calculation unit 41 decomposes the first reforming mode in which the fuel is not reformed based on the engine operating state and the olefinic hydrocarbon molecule having a large number of carbon atoms in the fuel. One reforming mode is selected from the second reforming mode for reforming the fuel and the third reforming mode for reforming the fuel by decomposing all the hydrocarbon molecules in the fuel. The input energy amount is calculated according to the reforming mode.

  Specifically, (1) In an area where the amount of smoke generated is originally small and the possibility of deterioration in combustibility is low, it is preferable to save energy to be input without reforming the fuel. In particular, reforming the fuel improves the ignitability, but also reduces the resistance to knocking that causes abnormal combustion. Therefore, it is preferable not to reform the fuel in a knock region such as during low-speed / high-load operation. In such an operating state, the first reforming mode is selected. When the first reforming mode is selected, the input energy amount is set to 0 and the fuel is not reformed.

  (2) When the engine 11 is cold (when the cooling water temperature is low), the temperature in the combustion chamber is low. In particular, the fuel adhering to the inner wall surface of the cylinder and the piston is insufficiently vaporized and droplet combustion occurs, and smoke is likely to be generated. Therefore, it is preferable to reduce olefinic hydrocarbon molecules that reduce the generation of smoke. In such an operating state, the second reforming mode is selected. When the second reforming mode is selected, an intermediate value between the binding energy of olefinic hydrocarbon molecules and the binding energy of paraffinic hydrocarbon molecules is calculated as the input energy amount. As a result, the olefinic hydrocarbon molecules having a large number of carbon atoms in the fuel are decomposed to reduce the olefinic hydrocarbon molecules.

  (3) When the engine 11 is operated at high speed and high load, it is preferable to reduce hydrocarbon molecules having a large number of carbon atoms in the fuel in order to improve ignitability and combustion stability. In such an operating state, the third reforming mode is selected. When the third reforming mode is selected, an energy amount larger than the paraffinic binding energy is calculated as the input energy amount. As a result, all hydrocarbon molecules in the fuel are decomposed to reduce hydrocarbon molecules having a large number of carbon atoms.

  Furthermore, the base control unit 43 (control parameter changing means) of the ECU 30 controls the control parameters of the engine 11 (for example, the fuel injection timing, the opening degree of the EGR valve 36, the intake air) according to the reforming mode selected by the input energy calculation unit 41. The opening / closing timing of the valve 31 and the exhaust valve 32 is changed.

  Specifically, (1) When the first reforming mode is selected, that is, when the fuel is not reformed, the fuel injection timing, the opening degree of the EGR valve 36, the opening / closing of the intake valve 31 and the exhaust valve 32 Let the time etc. be a standard conformity value (value calculated by a map etc. according to the engine operating state).

  (2) When the second reforming mode is selected, that is, when the generation of smoke is suppressed by reducing olefinic hydrocarbon molecules, for example, when the fuel injection timing is advanced to near the exhaust TDC Therefore, the fuel injection timing adapted to the retard side is advanced so as not to generate the smoke. Thereby, the optimal fuel injection timing can be selected.

  (3) When the third reforming mode is selected, that is, when the combustion stability is improved by reducing hydrocarbon molecules having a large number of carbon atoms, for example, the external EGR amount or variable valve timing by the EGR device 37 Since deterioration of combustion when the internal EGR amount by the devices 33 and 34 increases can be suppressed, the opening degree of the EGR valve 36 is increased to increase the external EGR amount, or the intake valve 31 and the exhaust valve 32 The opening / closing timing is changed to increase the valve overlap amount to increase the internal EGR amount. Thereby, pump loss and heat loss can be reduced, and fuel consumption can be further improved.

  The process relating to fuel reforming described above is executed by the ECU 30 according to the routines shown in FIGS. The processing contents of each routine will be described below.

[Fuel reforming routine]
The fuel reforming routine shown in FIG. 3 is repeatedly executed at a predetermined cycle while the ECU 30 is powered on. When this routine is started, first, in step 101, a reforming mode determination routine of FIG. 4 to be described later is executed, whereby the first reforming mode in which fuel is not reformed based on the engine operating state; A second reforming mode for reforming the fuel by decomposing hydrocarbon molecules having a large number of carbon atoms in the olefin system in the fuel, and a third reforming mode for reforming the fuel by decomposing all the hydrocarbon molecules in the fuel. One reforming mode is selected from the reforming modes.

  Thereafter, the process proceeds to step 102 where the input energy amount is calculated according to the selected reforming mode. In this case, when (1) the first reforming mode (the mode in which fuel is not reformed) is selected, the input energy amount is set to zero. (2) When the second reforming mode (mode in which fuel molecules are reformed by decomposing hydrocarbon molecules with a large number of carbon atoms in olefins in the fuel) is selected, the binding energy of olefinic hydrocarbon molecules And the intermediate value of the binding energy of the paraffinic hydrocarbon molecule is calculated as the input energy amount. (3) When the third reforming mode (a mode in which all the hydrocarbon molecules in the fuel are decomposed to reform the fuel) is selected, an energy amount larger than the paraffinic binding energy is input. Calculate as

  Thereafter, the process proceeds to step 103, and the input energy control unit 42 is instructed to calculate the input energy amount. Thereby, the input energy control unit 42 controls the drive voltage of the ultrasonic irradiation device 40 so as to realize the input energy amount.

  Thereafter, the process proceeds to step 104, and the selected reforming mode is instructed to the base control unit 43. Thereby, the base control unit 43 changes the control parameters of the engine 11 (for example, the fuel injection timing, the opening degree of the EGR valve 36, the opening / closing timing of the intake valve 31 and the exhaust valve 32, etc.) according to the reforming mode. In this case, (1) when the first reforming mode is selected, the fuel injection timing, the opening degree of the EGR valve 36, the opening / closing timing of the intake valve 31 and the exhaust valve 32, and the like are set as the reference conforming values. When (2) the second reforming mode is selected, the fuel injection timing is advanced. (3) When the third reforming mode is selected, the opening degree of the EGR valve 36 is increased to increase the external EGR amount, or the opening / closing timing of one or both of the intake valve 31 and the exhaust valve 32 is changed. The valve overlap amount is increased to increase the internal EGR amount.

[Reform mode judgment routine]
The reforming mode determination routine shown in FIG. 4 is a subroutine executed in step 101 of the fuel reforming routine of FIG. When this routine is started, first, in step 201, the engine speed is equal to or higher than a predetermined value, and the engine load (for example, intake air amount, intake pipe pressure, intake cylinder filling efficiency, etc.) is equal to or higher than a predetermined value. It is determined whether or not a high speed / high load operation is being performed depending on whether or not there is.

  If it is determined in step 201 that the engine is not operating at high speed and high load, the process proceeds to step 202, and whether or not the engine 11 is cold depending on whether or not the coolant temperature is equal to or lower than a predetermined value. Determine whether.

  If it is determined in step 201 that the engine is not operating at high speed and high load, and if it is determined in step 202 that the engine 11 is not cold (after warming up), the amount of smoke generated Therefore, it is determined that it is preferable to save the energy to be input without reforming the fuel, and the process proceeds to step 203, where the first reforming mode is selected. (Mode not reforming fuel) is selected.

  On the other hand, if it is determined in step 202 that the engine 11 is cold (before warming up), smoke is likely to be generated, and therefore, olefinic hydrocarbon molecules that reduce the generation of smoke. Therefore, the process proceeds to step 204 and selects the second reforming mode (mode for reforming the fuel by decomposing hydrocarbon molecules having a large number of carbon atoms in the olefin system in the fuel). .

  If it is determined in step 201 that the engine is operating at high speed and high load, hydrocarbon molecules having a large number of carbon atoms in the fuel may be reduced in order to improve ignitability and combustion stability. If it is determined that the fuel is preferable, the process proceeds to step 205, and a third reforming mode (a mode in which all hydrocarbon molecules in the fuel are decomposed to reform the fuel) is selected.

  In the first embodiment described above, the proper reforming mode according to the engine operating state is divided into the first reforming mode in which the fuel is not reformed, and the olefinic hydrocarbon molecules having a large number of carbon atoms in the fuel are decomposed. Then, the second reforming mode for reforming the fuel and the third reforming mode for reforming the fuel by decomposing all the hydrocarbon molecules in the fuel are selected and the selected reforming is performed. Since the input energy amount necessary for realizing the mode is calculated and the ultrasonic irradiation device 40 is controlled so as to realize the input energy amount, the energy amount to be supplied to the fuel according to the engine operating state is determined. It is possible to change the fuel reforming state in accordance with the amount of energy, and to appropriately change the fuel reforming state in accordance with the engine operating state.

  Further, in the first embodiment, the control parameters of the engine 11 (for example, the fuel injection timing, the opening degree of the EGR valve 36, the opening / closing timing of the intake valve 31 and the exhaust valve 32, etc.) are changed according to the selected reforming mode. Since it did in this way, the control parameter of the engine 11 can be set to the appropriate value corresponding to the selected reforming mode. In the case of a system including a variable valve lift device that changes the lift amount of the intake valve 31 or the exhaust valve 32, the lift amount of one or both of the intake valve 31 and the exhaust valve 32 is selected according to the selected reforming mode. The opening / closing timing of one or both of the intake valve 31 and the exhaust valve 32 may be changed.

  Next, Embodiment 2 of the present invention will be described with reference to FIG. However, description of substantially the same parts as those in the first embodiment will be omitted or simplified, and different parts from the first embodiment will be mainly described.

  In the second embodiment, by executing a reforming mode determination routine of FIG. 5 described later, an external EGR amount (amount of exhaust gas recirculated to the intake side) and an internal EGR amount (amount of exhaust gas remaining in the cylinder) The third reforming mode (a mode in which all the hydrocarbon molecules in the fuel are decomposed to reform the fuel) is selected in a region where there is a concern about the deterioration of combustibility due to an increase in the fuel.

  The routine of FIG. 5 is obtained by adding the processing of steps 202a and 202b after step 202 of the routine of FIG. 4 described in the first embodiment, and the processing of each other step is the same as that of FIG. .

  In the reforming mode determination routine of FIG. 5, when it is determined at step 202 that the engine 11 is not cold (after warm-up), the routine proceeds to step 202a and based on the opening degree of the EGR valve 36. The external EGR amount is estimated, and the internal EGR amount is estimated based on the valve overlap amount obtained from the opening / closing timing of the intake valve 31 and the exhaust valve 32.

  Thereafter, the process proceeds to step 202b, and whether or not the EGR amount is equal to or greater than a predetermined value is determined by determining whether at least one of the external EGR amount and the internal EGR amount (or the total value of the external EGR amount and the internal EGR amount) is equal to or greater than a predetermined value. It is determined by whether or not.

  If it is determined in step 202b that the EGR amount is equal to or greater than the predetermined value, the external EGR amount or the internal EGR amount increases, and there is a concern that the combustibility may be deteriorated. Therefore, it is determined that it is preferable to reduce hydrocarbon molecules having a large number of carbon atoms in the fuel in order to improve the fuel efficiency, and the process proceeds to step 205, where the third reforming mode (decomposing all hydrocarbon molecules in the fuel is decomposed) is performed. Select the fuel reforming mode.

  On the other hand, if it is determined in step 202b that the EGR amount is smaller than the predetermined value, the amount of smoke generated is originally low and there is little possibility of deterioration in combustibility, and fuel reforming is not performed. Since it is determined that it is preferable to save energy input to the engine, the process proceeds to step 203 to select a first reforming mode (a mode in which fuel is not reformed).

  In the second embodiment described above, the third reforming mode (decomposing all hydrocarbon molecules in the fuel is decomposed in a region where the external EGR amount and the internal EGR amount are increased and the combustibility may be deteriorated. Since the fuel reforming mode) is selected, hydrocarbon molecules having a large number of carbon atoms in the fuel can be reduced, and ignitability and combustion stability can be improved.

[Other Examples]
In each of the first and second embodiments, the ultrasonic irradiation device 40 is provided so as to irradiate the fuel in the fuel tank 38 with ultrasonic waves. However, the present invention is not limited to this. For example, as shown in FIG. As described above, a fuel reforming fuel sub-tank 44 having a fuel storage amount smaller than that of the fuel tank 38 is provided in the middle of the fuel pipe 39, and an ultrasonic irradiation device is used to irradiate the fuel in the fuel sub-tank 44 with ultrasonic waves. A configuration with 40 is also possible. Or it is good also as a structure which provided the ultrasonic irradiation apparatus 40 so that an ultrasonic wave may be irradiated to the fuel in the fuel piping 39. FIG.

  In each of the first and second embodiments, the ultrasonic irradiation device 40 is used as the fuel reforming unit. However, the present invention is not limited to this. For example, the spark plug 22 is used as the fuel reforming unit. It is also possible to ionize and decompose hydrocarbon molecules in the fuel by plasma discharge to a mixture of fuel and air with the spark plug 22. In this way, the spark plug 22 can be used as the fuel reforming means, and it is not necessary to newly provide the fuel reforming means, which satisfies the demand for cost reduction, which is an important technical problem in recent years. be able to. In this case, the energy input to the fuel can be changed by changing the discharge power of the spark plug 22.

  Alternatively, in the case of an in-cylinder injection engine provided with a fuel injection valve that injects fuel into the cylinder, a variable valve device (for example, a variable valve device that changes at least the opening / closing timing of the intake valve and / or the exhaust valve as fuel reforming means) A variable valve timing device, a variable valve lift device, etc.) and a fuel injection valve that injects fuel into the cylinder, and the variable valve device causes both the exhaust valve and the intake valve to close in the second half of the exhaust stroke. The valve overlap period may be provided, and the fuel molecules may be thermally decomposed by injecting fuel into the cylinder by the fuel injection valve during the negative valve overlap period. During the negative valve overlap period, the high-temperature combustion gas remaining in the cylinder is compressed by the rise of the piston in the latter half of the exhaust stroke, so that the cylinder is in a high temperature and high pressure state. If some or all of the fuel injected in one cycle is injected into the cylinder within this negative valve overlap period, the fuel injected into the cylinder is exposed to high temperature and high pressure gas in the cylinder. The hydrocarbon molecules in the fuel injected into the fuel can be pyrolyzed. In this way, the variable valve device and the fuel injection valve can be used as the fuel reforming means, and it is not necessary to newly provide the fuel reforming means. Can meet the demands of. In this case, by changing the negative valve overlap period, it is possible to change the compression ratio of the combustion gas remaining in the cylinder, change the maximum temperature in the cylinder, and change the energy input to the fuel.

  In the first and second embodiments, the reforming mode is changed in three stages according to the engine operating state. However, the reforming mode is changed in two stages or four or more stages according to the engine operating state. You may do it.

  In each of the first and second embodiments, the input energy amount is calculated according to the selected reforming mode. However, the present invention is not limited to this. For example, a variable valve device (for example, a variable valve timing device, variable Fuel reforming is performed when the valve overlap period in which both the exhaust valve and the intake valve are opened by a valve lift device etc. becomes longer and the remaining exhaust gas amount increases by being blown back into the cylinder The input energy amount may be calculated as described above. In this way, when the variable valve device increases the internal EGR amount (exhaust gas amount remaining in the cylinder) and there is a concern about deterioration of fuel combustibility, the fuel is reformed to reduce the amount of fuel. Ignition and flammability can be improved.

  Alternatively, the input energy amount may be calculated so that the reforming of the fuel is performed when the external EGR amount (exhaust gas amount recirculated to the intake side) increases by the EGR device. In this way, when the EGR device increases the amount of external EGR and there is a concern about deterioration of fuel combustibility, it is possible to improve the fuel ignitability and combustibility by reforming the fuel. .

  In addition, the present invention is not limited to the intake port injection type engine as shown in FIG. 1, but includes an in-cylinder injection type engine, and both an intake port injection fuel injection valve and an in-cylinder injection fuel injection valve. It can also be applied to dual-injection engines.

  DESCRIPTION OF SYMBOLS 11 ... Engine (internal combustion engine), 12 ... Intake pipe, 16 ... Throttle valve, 21 ... Fuel injection valve, 22 ... Spark plug, 23 ... Exhaust pipe, 30 ... ECU, 33 ... Intake side variable valve timing device (variable valve device) ), 34... Exhaust variable valve timing device (variable valve device), 37. EGR device (exhaust gas recirculation device), 38. Fuel tank, 40. Ultrasonic irradiation device (fuel reforming means), 41. (Input energy calculation means), 42 ... input energy control section (input energy control means), 43 ... base control section (control parameter changing means), 44 ... fuel sub tank

Claims (9)

In a control device for an internal combustion engine comprising fuel reforming means for decomposing hydrocarbon molecules in the fuel and reforming the fuel by introducing energy into the fuel of the internal combustion engine,
Input energy calculating means for calculating the amount of energy input to the fuel by the fuel reforming means (hereinafter referred to as “input energy amount”) based on the operating state of the internal combustion engine;
A control apparatus for an internal combustion engine, comprising: input energy control means for controlling the fuel reforming means so as to realize the input energy amount calculated by the input energy calculation means.   An ultrasonic irradiation apparatus that irradiates ultrasonic waves is used as the fuel reforming means, and hydrocarbon molecules in the fuel are thermally decomposed by irradiating the fuel with ultrasonic waves using the ultrasonic irradiation apparatus. Item 2. A control device for an internal combustion engine according to Item 1.   An ignition plug of an internal combustion engine is used as the fuel reforming means, and plasma molecules are discharged into a mixture of fuel and air by the ignition plug to ionize and decompose hydrocarbon molecules in the fuel. The control apparatus for an internal combustion engine according to claim 1.   As the fuel reforming means, a variable valve device that changes at least the opening / closing timing of an intake valve and / or an exhaust valve of an internal combustion engine and a fuel injection valve that injects fuel into a cylinder are used. Is provided with a negative valve overlap period in which both the exhaust valve and the intake valve are closed, and fuel is injected into the cylinder by the fuel injection valve during the negative valve overlap period. The control apparatus for an internal combustion engine according to claim 1, wherein hydrocarbon molecules are thermally decomposed.   The input energy calculation means has means for calculating the input energy amount so as to decompose hydrocarbon molecules having a large number of carbon atoms in the olefin system in the fuel based on the characteristics of the binding energy of the hydrocarbon molecules in the fuel. The control device for an internal combustion engine according to any one of claims 1 to 4.   The input energy calculating means reforms the fuel by decomposing the first olefin reforming mode in which the fuel is not reformed based on the operating state of the internal combustion engine and the olefinic hydrocarbon molecule having a large number of carbon atoms in the fuel. One reforming mode is selected from among the second reforming mode and the third reforming mode in which all the hydrocarbon molecules in the fuel are decomposed to reform the fuel, and the selected reforming mode is selected 6. The control apparatus for an internal combustion engine according to claim 5, further comprising means for calculating the amount of input energy in accordance with the control.   The control apparatus for an internal combustion engine according to claim 6, further comprising control parameter changing means for changing a control parameter of the internal combustion engine according to the reforming mode selected by the input energy calculating means. A variable valve device for changing at least the opening and closing timing of an intake valve and / or an exhaust valve of an internal combustion engine;
The input energy calculating means is configured to increase the amount of exhaust gas remaining after the valve overlap period in which both the exhaust valve and the intake valve are opened by the variable valve device is extended and blown back into the cylinder. 8. The control apparatus for an internal combustion engine according to claim 1, further comprising means for calculating the input energy amount so as to reform the fuel. An exhaust gas recirculation device that recirculates part of the exhaust gas of the internal combustion engine to the intake side,
The input energy calculating means has means for calculating the input energy amount so as to reform the fuel when the amount of exhaust gas recirculated to the intake side by the exhaust gas recirculation device increases. The control device for an internal combustion engine according to any one of claims 1 to 8.

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