JP2008157037A - Internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an internal combustion engine of a direct injection type provided with a function of plasma treatment even for the suppression of deposits. <P>SOLUTION: A fuel injection device 20 of the internal combustion engine 1A is provided with a plasma-generating part for causing a plasmatic state, and a fuel injection part for injecting fuel FE. The fuel injection device 20 is placed to face a combustion chamber 4 to make the plasmatic fuel combustible. The internal combustion engine 1A is provided with a controller 6. In the case that when the EGR gas produced by recirculating gas, air and exhaust gas is supplied to the plasma-generating part, and deposit adhesion is anticipated on the fuel injection part, the amount of air conveyance to the plasma generation part is increased by the controller 6. In the state that the adhesion of deposits is anticipated, the amount of air conveyance is increased, and ozone is locally generated to efficiently remove the deposits, or prevent them from being generated. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an internal combustion engine of a type in which a fuel injection valve is inserted into a combustion chamber to directly inject fuel, a so-called direct injection internal combustion engine. In particular, the present invention relates to an internal combustion engine that takes into account the suppression of deposits adhering to the injection hole of a fuel injection valve.

  In an internal combustion engine such as a gasoline engine, an output is obtained by burning an air-fuel mixture obtained by mixing air and fuel in a combustion chamber. Here, it is desirable that the fuel to be used has high reactivity and is combusted in the combustion chamber. If such a fuel is used, complete combustion can be promoted to improve fuel consumption and exhaust. Patent Document 1 proposes an improvement technique from such a viewpoint. Patent document 1 is disclosing about the apparatus which plasma-processes the fuel and reducing agent which are used with an internal combustion engine. This apparatus includes a plasma torch that converts gas into plasma, and an injector that injects fuel or the like into a region to which plasma is supplied. In an internal combustion engine that employs the technology disclosed in Patent Document 1, components are decomposed (cracked) when the injected fuel comes into contact with plasmaized gas. Since such fuel is atomized and has a high activity state, when it is burned in the combustion chamber, it is possible to improve fuel consumption and exhaust.

JP 2006-9703 A

  By the way, in recent years, attention has been focused on an internal combustion engine called a direct injection type in which fuel is directly injected into a combustion chamber from the viewpoint of improving fuel efficiency. If the technique of Patent Document 1 is applied to a direct injection internal combustion engine, it can be expected that fuel vaporization and reactivity are enhanced to realize efficient combustion.

  However, in the case of a direct injection type internal combustion engine, it is known that deposits are deposited (deposited) on the fuel injection port (injection hole) of the injector through continuous operation. Here, the deposit is a soot-like substance in which fuel or lubricating oil remains unburned inside the internal combustion engine, and is also referred to as a carbon deposit. If deposits adhere to the injector nozzle holes, the fuel flow rate decreases, the spray shape is deformed, and the startability and acceleration of the internal combustion engine deteriorate, and the exhaust gas increases. Therefore, consideration must be given to suppressing deposits adhering to the injector. However, since Patent Document 1 does not consider such points, an improvement from the viewpoint of deposit suppression is desired.

  Accordingly, an object of the present invention is to provide a direct injection type internal combustion engine having a plasma processing function capable of suppressing deposits.

  An object of the present invention is to provide an internal combustion engine in which a fuel injection device including a plasma generation unit that converts gas into plasma and a fuel injection unit that injects fuel is disposed so as to face the combustion chamber so that the plasma-treated fuel can be combusted. When an EGR gas obtained by recirculating air and exhaust gas as the gas is supplied to the plasma generation unit, and deposit adhesion to the fuel injection unit is expected, the engine is supplied to the plasma generation unit. This can be achieved by an internal combustion engine comprising control means for increasing the amount of air introduced.

  According to the present invention, when the control means is expected to deposit deposits on the fuel injection section, the amount of air introduced into the plasma generation section is increased, so ozone is generated locally to efficiently remove or deposit deposits. Can be prevented. Therefore, it is possible to provide a direct injection internal combustion engine having a plasma processing function capable of suppressing deposits.

  And the said control means may be made to estimate the said deposit adhesion based on being in the operation area | region where the temperature of the nozzle hole of the said fuel injection part becomes more than predetermined temperature.

  And a fuel injection valve for injecting fuel in the middle of an intake passage for supplying intake air to the combustion chamber, wherein the control means stops fuel injection from a fuel injection portion of the fuel injection device, and When the fuel is injected from the fuel injection valve, the deposit adhesion may be predicted.

  ADVANTAGE OF THE INVENTION According to this invention, the direct injection type internal combustion engine provided with the plasma processing function which can also suppress a deposit can be provided.

  Hereinafter, an internal combustion engine according to an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram schematically illustrating a schematic configuration of an internal combustion engine 1A according to the first embodiment. In this internal combustion engine 1A, a piston 3 is arranged in a cylinder 2 so as to be movable up and down, like a conventional internal combustion engine. A recess 3 a is formed on the upper surface of the piston 3, and the combustion chamber 4 is located above the recess 3 a. A spark plug 5 is provided so as to face the combustion chamber 4. Further, an intake port 10 for supplying intake air to the combustion chamber 4 and an exhaust port 12 for exhausting exhaust gas generated in the combustion chamber 4 are respectively connected. An intake valve 11 is provided at the opening of the intake port 10 on the combustion chamber 4 side, and an exhaust valve 13 is provided at the exhaust port 12. The intake port 10 is a part of an intake passage, and an air cleaner, an air flow meter, a throttle valve, and the like are appropriately arranged on the upstream side of the intake passage, but are not shown here.

  This internal combustion engine 1A is a direct injection type in which fuel is directly injected into the combustion chamber 4. Therefore, the fuel injection device 20 that injects the fuel is disposed so as to face the combustion chamber 4. The fuel injection device 20 has a function of not only injecting the fuel FE into the combustion chamber 4 but also plasma-treating the sprayed fuel. Further, the configuration around the fuel injection device 20 will be described.

  The fuel injection device 20 uses a fuel injection valve (hereinafter referred to as an injector) that is a structure for injecting fuel into the combustion chamber 4 as a main body to generate plasma for promoting atomization of the injected fuel. It has a structure with a plasma device added. That is, the fuel injection device 20 is configured as a composite fuel injection device including a fuel injection unit that injects fuel and a plasma generation unit.

  As shown in the figure, the fuel injection device 20 is connected to the fuel tank 8 via the hydraulic pump 9 and also connected to a pulse power source 7 used for plasma generation. The fuel injection device 20 is designed so that air and EGR (Exhaust Gas Recirculation) gas can be used as a gas (carrier gas) used when plasma processing the fuel. Therefore, the internal combustion engine 1A includes a gas supply structure 15 that supplies air and EGR gas. The gas supply structure 15 may be a structure for supplying EGR gas in which air (outside air) and exhaust gas are recirculated to the fuel injection device 20, and may be set appropriately. For example, the gas supply structure 15 may be a structure in which an air introduction pipe 16 branched from the intake passage and a reflux pipe 17 that circulates exhaust gas from the exhaust port 12 are simply assembled. On the downstream side of the gas supply structure 15, a gas switching valve 18 that switches between air supplied to the fuel injection device 20 and EGR gas and a gas pump 19 that pressure-feeds the gas to the fuel injection device 20 are arranged. The gas switching valve 18 may be configured to selectively switch between air and EGR gas, or may be configured to change the mixing ratio of air and EGR gas according to the opening of the valve body.

  Note that air and EGR gas employed as gas to be converted into plasma here contain appropriate moisture. When this moisture is converted into plasma, OH radicals and O radicals are generated. These radicals promote cracking and lightening of the fuel, and bind to the end of the molecular chain of the fuel cleaved by plasma to prevent the formation of unsaturated hydrocarbons and suppress the formation of deposits. Furthermore, since the EGR gas has a relatively low oxygen concentration, it is preferable in that it has a low tendency to oxidize fuel when it is made into plasma.

  FIG. 2 is a diagram schematically showing the main configuration of the fuel injection device 20 shown in FIG. As described above, the fuel injection device 20 is a fuel injection device having a main body of an injector that functions as a fuel injection unit, and includes a plasma unit that performs plasma processing on the injected fuel. The plasma generating part of the fuel injection device 20 uses, for example, discharge plasma. An injector 25 is disposed in the center of the conductive cylindrical conduit 22 through which the gas PG to be converted into plasma is circulated. The nozzle body 26 of the injector 25 is designed to function as a discharge electrode.

  An insulating material 24 is disposed between the cylindrical conduit 22 and the injector 25. The cylindrical conduit 22 and the injector 25 are connected to the ground and the pulse power source 7 (see FIG. 1) so as to serve as counter electrodes. Either cylindrical conduit 22 or injector 25 can be a cathode or an anode. Further, either the cylindrical conduit 22 or the injector 25 can be grounded.

  In use of the plasma generator of the fuel injection device 20, a discharge is generated between the cylindrical conduit 22 and the injector 25 by the pulse power source 7. A gas passage 23 is formed between the injector 25 and the insulating material 24. This gas passage 23 is connected to the gas pump 19 shown in FIG. Therefore, air, EGR gas, or a mixture thereof is supplied to the gas passage 23 as the gas PG to be turned into plasma. Therefore, as schematically shown in FIG. 2, the plasma region 21 is formed at the tip of the injector 25 by the gas converted into plasma.

  By bringing the fuel FE injected from the injection hole 27 formed in the nozzle body 26 of the injector 25 into contact with the plasma region 21, the plasma treatment is performed to promote atomization and increase the activation.

  Referring to FIG. 1 again, each part of the internal combustion engine 1A described above is entirely controlled by an electronic control unit (hereinafter referred to as ECU 6). The ECU 6 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), an input / output circuit, and the like (not shown). The ECU 6 is supplied with outputs from various sensors such as a crank angle sensor that detects the rotational speed of the internal combustion engine, a water temperature sensor that detects the coolant temperature that cools the cylinder, and an accelerator sensor that detects the amount of depression of the accelerator pedal. ing. Based on the outputs of these sensors, the ECU 6 controls the operation of the intake valve 11 and the exhaust valve 13, the drive timing of the fuel injection device 20, the ignition timing of the spark plug 5, and the like, thereby smoothly controlling the internal combustion engine 1. To drive. For this purpose, the ROM stores programs in which various processes executed by the CPU are described.

  In particular, the ECU 6 of this embodiment controls the fuel injection device 20 having a function of plasma processing of fuel to improve fuel consumption and exhaust while suppressing deposit adhesion. This point will be further described. The fuel injection device 20 shown in FIG. 2 is disposed so as to face the combustion chamber 4 of FIG. Therefore, the deposit DP may adhere and accumulate around the nozzle hole 27 while the internal combustion engine 1A is driven for a long time and fuel is repeatedly injected from the injector 25 of the fuel injection device 20. When the deposit adhesion amount exceeds a certain level, it becomes an obstacle to the fuel FE injected from the injection hole 27, and its flow rate and spray shape are deteriorated.

  By the way, there are cases where deposits are likely to adhere to the injector during operation of the internal combustion engine 1A and situations where it is difficult to adhere. For example, in an operating situation in which the internal combustion engine is operated at a high load for a certain time or longer, the temperature in the combustion chamber becomes very high, so the deposited deposit can be burned and removed. On the other hand, the temperature in the combustion chamber is not so high in operating conditions such as immediately after the start of the internal combustion engine. Therefore, the deposit adhering to the nozzle hole may be left as it is, or the deposit adhesion amount may be further increased, resulting in a situation where the flow rate and the spray shape are deteriorated. An operating situation in which the temperature at the tip of the injector 25 is a predetermined temperature corresponds to this. For example, deposits are likely to occur when the temperature at the tip of the injector is, for example, about 150 ° C. or higher in an operating situation where the engine speed is low and the load is low, such as during idling.

The ECU 6 of the internal combustion engine 1A uses the EGR gas as a gas for plasma processing of the fuel when an EGR device (not shown) is driven and the EGR gas can be used. The ECU 6 increases the amount of air introduced as the gas when the operating condition in which deposit adhesion is expected as described above. The ECU 6 controls the gas switching valve 18 of FIG. 1 to select air (or increase the air ratio) as the gas to be used, and controls the gas pump 19 to supply the required flow rate to the fuel injection device 20. The ECU 6 controls the pulse power source 7 to turn the air into plasma. Plasmaized air generates ozone (O ₃ ). Since ozone generated in this way is highly oxidative, it can promote complete combustion of deposits mainly composed of carbon. The completely burned deposit becomes a form of carbon dioxide (CO ₂ ), is detoxified, and is discharged together with the exhaust gas.

  As described above, the ECU 6 of the internal combustion engine 1A selects air as a gas to be converted into plasma when deposits on the injector are expected from the operating state. Then, ozone is locally generated near the tip of the injector to remove deposits. Therefore, the internal combustion engine 1 </ b> A is an excellent internal combustion engine that is provided with a plasma processing function to improve fuel consumption and exhaust, and further suppress deposit adhesion.

  From the viewpoint of protecting the air environment, ozone emission should be regulated. In the case of the present embodiment, since the region adhering to the deposit attached to the tip of the injector 25 of the fuel injection device 20 is limited, ozone is generated temporarily and locally and consumed for deposit processing. It will not be a problem.

  FIG. 3 is a diagram schematically illustrating a schematic configuration of the internal combustion engine 1B according to the second embodiment. In the description of the second embodiment, the same parts as those in the internal combustion engine 1A of the first embodiment are denoted by the same reference numerals in FIG.

  In the internal combustion engine 1B, an injector 30 serving as a second fuel injection valve is disposed in the intake port 10. Since the internal combustion engine 1B includes the injector 25 and the injector 30 of the fuel injection device 20 described above, an efficient operation can be performed by selectively adopting an injector that injects fuel according to an operation state. Also in the second embodiment, the ECU 6 controls the fuel injection timing of the injector 25 and the injector 30 in the fuel injection device 20. Further, the ECU 6 generates gas that has been converted into plasma by the fuel injection device 20 as necessary.

  When the ECU 6 selectively controls the injector that injects fuel according to the operating state of the internal combustion engine 1B, the fuel is injected only from the injector 30 on the intake port 10 side, and the combustion in the combustion chamber 4 is injected into the fuel. It may be assumed that a situation occurs in which the plasma processing of the apparatus 20 is driven to perform plasma processing. In such a situation, since fuel is not injected from the injector 25 of the fuel injection device 20, deposits easily adhere to the injection holes 27. If this deposit is left unattended, the above-described problem will occur when fuel is injected from the injector 25 of the fuel injection device 20 next time.

  Therefore, from the viewpoint of removing deposits attached to the injector 25 and preventing adhesion, the ECU 6 of the internal combustion engine 1B drives the injector 30 on the intake port 10 side to inject fuel, and fuel injection from the fuel injection device 20 is performed. In the case where the plasma processing is performed without performing this, air is used as a gas supplied to the fuel injection device 20. Or when the ratio of the air of the gas to be used and the EGR gas can be adjusted, the amount of air introduced is increased.

  Even in the internal combustion engine 1B of the second embodiment described above, when the ECU 6 is expected to deposit deposits on the injector 25 from the operating state, the amount of air introduced as the gas to be converted into plasma is increased. Then, ozone is locally generated near the tip of the injector to remove or prevent deposits. Therefore, also in the case of the internal combustion engine 1B, by providing the plasma processing function, it becomes an internal combustion engine that can improve fuel consumption and exhaust, and can suppress deposit adhesion.

  Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to the specific embodiments, and various modifications and changes can be made within the scope of the gist of the present invention described in the claims. It can be changed.

1 is a diagram schematically showing a schematic configuration of an internal combustion engine 1A according to Embodiment 1. FIG. It is a figure which shows typically the main structures of the fuel-injection apparatus shown in FIG. FIG. 6 is a diagram schematically illustrating a schematic configuration of an internal combustion engine 1B according to a second embodiment.

Explanation of symbols

1 (1A, 1B) Internal combustion engine 2 Cylinder 4 Combustion chamber 7 Pulse power supply 6 ECU (control means)
DESCRIPTION OF SYMBOLS 10 Intake port 13 Exhaust port 20 Fuel injection apparatus 25 Injector (fuel injection part)
22, 26 Plasma generator 26 Nozzle body 27 Injection hole 30 Injector (fuel injection valve)
DP deposit FE fuel

Claims (3)

An internal combustion engine in which a fuel injection device including a plasma generation unit that converts gas into plasma and a fuel injection unit that injects fuel is disposed so as to face a combustion chamber, and the plasma-treated fuel is combustible. ,
EGR gas obtained by recirculating air and exhaust gas as the gas is supplied to the plasma generation unit,
An internal combustion engine comprising control means for increasing the amount of air introduced into the plasma generator when deposits are expected to adhere to the fuel injector. 2. The internal combustion engine according to claim 1, wherein the control unit predicts the deposit adhesion based on an operation region in which a temperature in the vicinity of the injection hole of the fuel injection unit is equal to or higher than a predetermined temperature. . A fuel injection valve for injecting fuel in the middle of an intake passage for supplying intake air to the combustion chamber;
The said control means stops the fuel injection from the fuel injection part of the said fuel injection apparatus, and predicts the said deposit adhesion when injecting fuel from the said fuel injection valve. The internal combustion engine described.

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