JP2014062551A - Fuel atomization acceleration apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel atomization acceleration apparatus capable of corresponding to fuel spray for a short time, and capable of performing fuel atomization in a simply and optionally controllable manner.SOLUTION: A fuel atomization acceleration apparatus includes: an electrode pair 150 that supplies charged particles to a space in the vicinity of a fuel jet; and an electromagnetic wave radiator that performs irradiation of electromagnetic waves with an antenna 151, forms a strong electric field in the space in the vicinity of the fuel jet, and generates plasma in the space by supplying energy to the charged particles in the space, and accelerates fuel atomization by changing the surface tension of the fuel jet with the plasma.

Description

  The present invention relates to a fuel atomization promoting device, and more particularly to a atomization promoting device that changes the particle size of a fuel spray by electrical control.

  As a conventional technique for atomizing the fuel spray, a high pressure injection is performed by increasing the valve opening pressure of the injection valve (for example, a common rail system). A fuel injection (for example, Patent Document 1) and a mixture of water and a surfactant and a fuel to form an emulsion (for example, Patent Document 2) have been developed, and some of them are put into practical use. Other conventional techniques for atomizing a liquid include an ultrasonic atomization method and an electrostatic atomization method.

JP 2007-211163 A JP 2007-113570 A

  A method of performing high-pressure injection such as a common rail system requires a robust and highly accurate pressurizing mechanism and a solenoid valve. For this reason, an apparatus for atomizing fuel spray by this method is expensive by itself and hinders its spread.

  In the method described in Patent Document 1, a high voltage is applied to a porous body serving as a minute nozzle to generate heat in order to preheat the fuel. Since time is required for porous heat generation, time response is poor. Further, this method cannot control the particle size.

  In the system described in Patent Document 2, impurities are mixed into the fuel as a result. This impurity may adversely affect combustion.

  In the ultrasonic atomizer, since the amount of liquid to be atomized depends on the area of the interface between the container storing the liquid and the gas phase, the controllability of the amount of liquid to be atomized is poor. It is difficult to apply to a combustion engine that requires precise control of the amount of fuel.

  In the electrostatic atomization method, since atomization is performed by pulling liquid molecules to the gas phase side by Coulomb force, it cannot cope with pressurized fuel injection. With this, fuel injection in a short time cannot be achieved.

  The present invention has been proposed in view of the above-mentioned circumstances, and the object thereof is to enable the atomization of fuel in a manner that can cope with a short time fuel spray and can be controlled easily and arbitrarily. An apparatus for promoting atomization of fuel is provided.

  In order to solve the aforementioned problems and achieve the object, the fuel atomization promoting device according to the present invention has any one of the following configurations.

[Configuration 1]
A device for promoting atomization of fuel injected from an injector, which irradiates electromagnetic waves using a charged particle supply means and an antenna, forms a strong electric field in a space where charged particles exist, and charges in the space Means for generating plasma in this space by supplying energy to the particles, a cavity surrounding the antenna and the charged particle supply means is disposed, and the cavity wall surface faces the injector tip. An opening for communicating the combustion chamber and the inside of the cavity is provided, and the surface tension of the fuel is changed using plasma ejected from the opening.

  In order to promote atomization in a mode that can be controlled at high speed without impeding the flow of fuel, plasma is supplied in the vicinity of the fuel jet in combination with charged particle supply by means of supplying charged particles and electromagnetic wave irradiation. Form. In this method, plasma generation / extinguishment and scale control can be performed at high speed, and the time response is excellent. Moreover, plasma can be formed and maintained remotely. The plasma formed in the vicinity of the fuel heats the fuel and lowers the surface tension. Alternatively, the chemical species constituting the plasma directly act on the fuel molecules on the droplet surface or the liquid column surface to lighten the fuel molecules. In general, the lower the molecular weight, the lower the intermolecular force of the hydrocarbon-based fuel, so that the surface tension is lowered. A whole or partial change in the surface tension promotes atomization.

[Configuration 2]
In the fuel atomization promoting device having the configuration 1, the charged particle supply means supplies the charged particles using the ignition means of the combustion engine.

  In a combustion engine, regardless of the ignition method, ignition means is provided to start combustion. The ignition means generates charged particles by various operations for igniting the fuel or by combustion performed as a result. By supplying the charged particles to the vicinity of the fuel spray, a series of operations for promoting atomization of the fuel is started.

[Configuration 3]
The atomization promoting device having the configuration 1 or the configuration 2 is characterized in that the means for generating plasma maintains the plasma even after changing the surface tension and atomizes the fuel using the plasma. It is what.

  As described above, according to the present invention, it is possible to deal with fuel spray for a short time and to atomize the fuel in a manner that can be easily and arbitrarily controlled.

  The best mode for carrying out the present invention will be described below with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. The structure, function, and operation of the parts with the same reference numerals are the same. Therefore, the description of components having the same reference numerals will not be repeated.

[First Embodiment]
FIG. 1 is a schematic configuration diagram of a fuel atomization promoting apparatus according to a first embodiment. As shown in FIG. 1, the combustion engine 100 is an in-cylinder direct injection type diesel engine, and each cross section (hereinafter, this cross section is referred to as “ The cylinder block 101 has a wall surface forming a circular shape whose center is the intersection of the straight line and the cross section. The cylinder block 101 defines the cylinder C by this wall surface. The diesel engine 100 further includes a cylinder head 102 that is assembled to the cylinder block 101 so as to cover one end portion of the cylinder C via the gasket 104 and has a plurality of through holes that respectively conduct to the cylinder C. The cylinder has a substantially circular portion corresponding in shape to the cross-sectional shape of the cylinder C, and the portion is in sliding contact with a wall surface forming the cylinder C of the cylinder head 101 (hereinafter, this wall surface is referred to as “cylinder inner wall”). The piston block 103 is reciprocally inserted into the cylinder C, and the cylinder block 101, the cylinder head 102, and the piston 103 form a combustion chamber CC. Note that the cylinder block 101 and the cylinder 102 are electrically grounded to the housing.

  A recess called a piston chamber is provided on the cylinder head 102 side of the piston 103, and the opposite side is connected to a crankshaft which is an output shaft of the diesel engine 100 via a connecting rod. Connecting rods and crankshafts and their connecting mechanisms are well known and will not be described here.

  At least one of the through holes of the cylinder head 102 is provided so as to communicate with an exhaust pipe (not shown), and this through hole forms an intake port IN. The cylinder head 102 is further provided with a guide hole penetrating from the intake port IN to the outer wall of the cylinder head 102. A rod-shaped valve stem 121 is reciprocally fitted in the guide hole, and an umbrella-type valve head 122 is provided on the intake port IN side of the valve stem 121. The valve stem 121 and the valve head 122 constitute an intake valve 120 that opens and closes the combustion chamber side end of the intake port IN.

  At least one other through hole of the cylinder head 102 is provided so as to communicate with an exhaust pipe (not shown), and this through hole forms an exhaust port EX. The cylinder head 102 is further provided with a guide hole penetrating from the exhaust port EX to the outer wall of the cylinder head 102. A rod-shaped valve stem 126 is reciprocally fitted in the guide hole, and an umbrella-type valve head 127 is provided on the exhaust port EX side of the valve stem 126. The valve stem 126 and the valve head 127 constitute an exhaust valve 125 that opens and closes the combustion chamber side end of the exhaust port EX. The intake valve 120 and the exhaust valve 125 are each driven by a valve mechanism (not shown) having a cam or a solenoid.

  In yet another one of the through holes of the cylinder head 102, an injector 130 is installed. A nozzle is provided at a tip portion 131 facing the combustion chamber CC of the injector 130, and an electromagnetic valve (not shown) is incorporated therein. The injector 130 is connected to receive fuel from a fuel tank via an oil feed pipe, a pressure accumulating container and a supply pump (not shown), and the oil feed pipe, the pressure accumulating container and the supply pump, and an ECU (engine) for controlling them. A fuel injection system is configured together with a control unit) and an EDU (drive unit). The detailed operation of the fuel injection system itself is well known and will not be described here, but when this fuel injection system is driven, fuel is injected from the nozzle of the tip portion 131. In the present embodiment, at least the tip portion 131 of the injector 130 is made of a conductor such as metal.

  When the fuel injection system injects the fuel, the fuel is ejected without being vaporized, and ejected from the nozzle in the form of droplets, mist, or liquid column. In order to atomize the fuel in such a state, the diesel engine 100 has a configuration described below.

  A discharge line 140 formed by covering a high-voltage conductor and a ground conductor with a dielectric is inserted into another through hole of the cylinder head 102 and joined to the cylinder head 102. An electrode pair 150 consisting of a high voltage electrode and a ground electrode is provided at the end portion of the discharge line 140 on the combustion chamber CC side, and the other end portion causes dielectric breakdown of the working fluid between the high voltage electrode and the ground electrode. A discharge voltage generator 160 that generates a sufficient voltage is connected.

  It is desirable that the discharge line 140 and the electrode pair 150 have thermal durability and mechanical durability enough to withstand the environment in the combustion chamber CC. Therefore, specifically, the discharge line 140 and the electrode pair 150 may be a spark plug for an internal combustion engine. In this case, the plug body and the cylinder head 102 into which the plug body is screwed become the ground conductor of the discharge line 140. When a spark plug is used as the discharge line 140 and the electrode pair 150, the type thereof may be a general monopolar gap type or a so-called multipolar plug. Moreover, what is called a creeping discharge type or a semi-creeping discharge type may be used. As the discharge voltage generator 160, specifically, an ignition coil connected to a 12V power source for automobiles may be used, or other various types of voltage generators may be appropriately selected and used. The voltage generated by the discharging voltage device 160 may be either a DC voltage or an AC voltage.

  Then, the electromagnetic wave transmission line 141 is inserted into another through hole of the cylinder head 102 and joined to the cylinder head 102. An antenna 151 is provided at the end of the electromagnetic wave transmission line 141 on the combustion chamber CC side, and the other end is connected to an electromagnetic wave generator 161 that generates an electromagnetic wave having a predetermined frequency.

  The electromagnetic wave generator 161 includes an oscillator that oscillates upon receiving power supply and generates an electromagnetic wave having a predetermined frequency, and a power source thereof. The oscillator may be either a feedback type or a relaxation type. Moreover, what is called a high frequency generator may be used. Note that a 2.45 GHz oscillation magnetron is inexpensive and has a high output and is suitable as an oscillator. What is necessary is just to select a power supply suitably according to the oscillator to be used. For example, an inverter type pulse power supply device may be used. The electromagnetic wave transmission line 141 may be any type of a coaxial line, a parallel line, and a waveguide. In FIG. 1, a monopole antenna is illustrated as the antenna 151, but the electromagnetic wave transmission line 141 and the antenna 151 may be any ones that can transmit and radiate electromagnetic waves generated by the electromagnetic wave generator 161 well. Specifically, the antenna 151 may be any of a linear antenna, a planar antenna, a three-dimensional antenna, a traveling wave antenna, an EH antenna, a magnetic field antenna, and a dielectric antenna, and may constitute an antenna array. Alternatively, a diversity antenna may be configured. Further, the feeding method to the antenna 151 may be current feeding or voltage feeding.

  It is desirable that both the electrode pair 150 and the antenna 151 are arranged at positions where the spray from the injector 130 does not hit directly. For example, when the injector 130 is of a multi-nozzle, it may be installed during spraying from the nozzle.

  The discharge voltage generator 160 and the electromagnetic wave generator 161 are connected to a controller 171 that receives a predetermined input signal 170. Specifically, the control device 171 is a computer having a CPU (Central Processing Unit), a memory and a nonvolatile storage device, and a signal input / output interface, and is stored in the memory and the nonvolatile storage device. And a function of calculating and outputting a control signal for the discharge voltage generator 160 and a control signal for the electromagnetic wave generator 161 by operating the input signal 170. The input signal 170 may be a fuel injection command signal issued by the ECU. Or the signal which the various sensors installed in the diesel engine 100 output may be sufficient.

  In the above configuration, the electric system including the discharge line 140, the electrode pair 150, and the discharge voltage generator 160 (hereinafter, this system may be referred to as “discharge system”) operates under the control of the control device 171. A charged particle supplier is formed that generates charged particles such as electrons and ions by discharge between the high-voltage electrode and the ground electrode of the electrode pair 150. An electrical system including the electromagnetic wave transmission line 141, the antenna 151, and the electromagnetic wave generator 161 (hereinafter, this system may be referred to as “electromagnetic radiation system”) operates under the control of the control device 171 and radiates electromagnetic waves from the antenna 151. Thus, an electromagnetic wave irradiator is formed that forms an electric field having a strength greater than or equal to a predetermined value in a space including at least a portion where discharge occurs, and gives energy to charged particles to form plasma.

  When the control device 171 receives the input signal 170, the control device 171 gives a control signal corresponding to the state in which the discharge system is operated to the discharge voltage generator 160. In response to this control signal, discharge voltage generator 160 starts applying a voltage to electrode pair 150 via discharge line 140. By applying this voltage, the electrode pair 150 starts to discharge, and charged particles are generated.

  The control device 171 further gives a control signal corresponding to a state in which the electromagnetic wave emission system is operated to the electromagnetic wave generation device 161 so that the electromagnetic wave emission system starts emitting electromagnetic waves during a period in which charged particles are present due to discharge. At this time, it is desirable that the control device 171 gives the control signal to the electromagnetic wave generator 161 at a timing that takes into account the delay in the operation time of the discharge system and the electromagnetic wave radiation system. The electromagnetic wave generator 161 starts oscillation in response to this control signal, and applies an electromagnetic wave to the electromagnetic wave transmission path 141. The applied electromagnetic wave travels in the electromagnetic wave transmission path 141 and is radiated from the antenna 151.

  The charged particles generated by the discharge are irradiated with electromagnetic waves radiated from the antenna and induce a so-called electronic avalanche. That is, the charged particles receive the electromagnetic energy and accelerate to collide with the substance in the second space. The impacted material is ionized and becomes charged particles. By this chain, plasma is formed in the second space. By such a combination of charged particle supply and electromagnetic wave irradiation, plasma is easily started and expanded. Preparation and supply of charged particles that trigger plasma, and plasma formation and expansion are performed using separate mechanisms. This plasma formation method is a plasma formation method by discharge that requires the application of a very high voltage to generate a large-scale plasma, or a plasma formation method using only a microwave that relies on charged particles that occur accidentally as a trigger plasma, It is highly efficient and has excellent time response, and a desired plasma can be obtained at a desired timing.

  The region near the fuel spray is heated by the formation of plasma. Alternatively, charged particles such as electrons collide with the surface of the fuel droplet or the surface of the fuel liquid column, and the chemical composition of the fuel molecules in this portion is changed. The plasma formed in the vicinity of the fuel spray heats the fuel and lowers the surface tension. Moreover, chemical species having high oxidizing power such as OH radicals, oxygen ions, and ozone are generated by the plasma formation. Alternatively, highly oxidizing chemical species such as OH radicals, oxygen ions, and ozone directly act on the fuel molecules on the surface of the fuel droplets or the surface of the fuel liquid column to oxidize the fuel molecules and lighten the fuel molecules. Let In general, the lower the molecular weight, the lower the intermolecular force of the hydrocarbon-based fuel, so that the surface tension is lowered. Or the viscosity of the fuel decreases. Alternatively, the fuel molecules on the surface of the fuel droplets or the surface of the fuel liquid column react with chemical species having high oxidizing power, so that the polarity of the fuel molecules on the surface is generated, and as a result, the surface tension changes.

  When the surface tension is reduced over the entire fuel spray surface, the number of Webers is substantially reduced. Deformation of the free surface is facilitated and the probability of increasing the surface area is increased. For this reason, the diffusion coefficient of fuel is increased and atomization is promoted. When plasma is applied to a part of the surface of the fuel droplet or the surface of the fuel liquid and the surface tension of the part is changed, a surface tension wave is generated on the surface of the fuel liquid or the surface of the fuel liquid. This surface tension wave also contributes to the promotion of atomization. When plasma is applied to a part of the surface, the surface tension is not necessarily reduced. Conversely, even when the surface tension locally increases, dispersion and atomization due to generation of surface tension waves may be promoted.

  Furthermore, other factors also cause changes in the interaction between the fuel and the ambient atmosphere. When the temperature, chemical composition, pressure, and the like of the boundary layer near the surface of the fuel droplet or the fuel liquid column are changed by the action of the plasma, the thickness, density, and velocity gradient of the boundary layer change. In addition, a slip resistance at the interface and a change in shear force in the interface direction also occur. These changes also contribute to atomization promotion.

  After the surface tension is changed in this way, the plasma formation is continued, and if the plasma is further applied to the surface of the fuel droplet or the vicinity of the fuel liquid column, the fuel droplet or the fuel liquid column is split and atomized. . For example, heating is promoted as the surface area increases, and vaporization is promoted. Or, due to fluctuations in pressure such as shock waves accompanying the generation of plasma, the fuel droplets or the fuel liquid column are deformed by external force and eventually split. That is, it atomizes.

  In the present embodiment, the tip portion 131 is projected in order to excite the tip portion 131 of the injector 130, but the structure for exciting is not limited to this. Depending on the frequency of the electromagnetic wave to be used, the shape, structure, material, bonding form with other members, and the like may be appropriately selected so that this portion is excited.

[Second Embodiment]
It is also possible to separately feed electromagnetic waves to the tip portion 131 of the injector 130 and excite the member of the tip portion 131. In this case, the member of the tip portion 131 of the injector 130 may receive power from the electromagnetic wave generator 161. In addition, an electromagnetic wave generation source and a transmission path may be provided separately from the electromagnetic wave generator 161, and power may be received from these sources. Furthermore, when supplying power to the member of the tip portion 131 of the injector 130, this member may also serve as the function of the antenna 151. In addition, an electromagnetic wave may be superimposed on the high-voltage line of the discharge line 140, and the high-voltage electrode of the electrode pair 150 may be used as the antenna 151.

[Third Embodiment]
In the present embodiment, plasma is sprayed on the fuel spray by the flow of the working fluid in the vicinity of the injector 130. Specifically, except that a small-capacity cavity 300 is provided so as to surround the electrode pair 150 and the antenna 151, and the plasma generated in the cavity 300 is ejected in the vicinity of the fuel spray from the injector. This is the same as the first embodiment.

  FIG. 2 is a schematic configuration diagram of the present embodiment. As shown in FIG. 2, in this embodiment, a small-capacity cavity 300 is provided so as to surround the electrode pair 150 and the antenna 151. An opening 302 is provided in a wall surface forming the cavity 300 at a position facing the tip portion 131 of the injector 130 so as to communicate the combustion chamber CC and the space inside the cavity 300.

  In this embodiment, the supply of charged particles by discharge and the formation and expansion of plasma by electromagnetic radiation are both performed in the same manner as in the first embodiment. Part of the energy input in this operation is used for heating the working fluid in the cavity 300. When the working fluid in the cavity 300 is heated, the pressure inside the cavity 300 rises, and a pressure difference is generated inside and outside the cavity 300. Since the inside and the outside of the cavity 300 communicate with each other through the opening 302, a flow from the inside of the cavity 300 to the outside of the cavity is generated, and plasma generated in the cavity 300 by this flow is ejected from the opening 302. Since the opening 302 is provided toward the tip portion 131 of the injector 130, the jetted plasma is introduced in the vicinity of the fuel spray from the injector. As a result, the fuel spray is exposed to charged particles in the plasma and chemical species having high oxidizing power.

  As described above, in the present embodiment, the plasma is accelerated by using the energy as the heat energy in the working fluid when the plasma is generated. Therefore, energy efficiency is high. Moreover, it is excellent in the localization property of plasma, and it becomes easy to maintain the positional relationship between fuel spray and plasma appropriately.

  In the present embodiment, plasma is accelerated and transported by generating a pressure difference using a small-capacity cavity. However, the present invention is not limited to this. The flow and turbulence of the working fluid generated during the operation of the diesel engine 100, such as the flow of squish flow or swirl or tumble generated in the combustion chamber CC, pressure vibration, shock wave, etc., may be used for plasma acceleration / transport.

  [Other variations, etc.]

  In each of the above-described embodiments, the plasma acts directly on the surface of the fuel droplet or the fuel liquid column, and changes the surface tension. However, the plasma is also applied to the flow path surface (for example, the nozzle surface) through which the fuel passes. If it is made to act, the wettability with respect to the fuel of the part can be changed. This can also change the surface tension of the fuel.

  In each of the above-described embodiments, charged particles that trigger plasma formation are prepared and supplied by discharge, but supply of charged particles is not limited to this. For example, thermoelectrons may be emitted by heating with a heater such as a filament, a ceramic heater, or a glow plug. Charged particles may be released by impact or friction such as flint and matches. An ignition device using laser light or the like can also be used for supplying charged particles. You may make it form a flame using the pilot burner used for reignition and flame holding, such as a gas turbine engine, a gunpowder, a lead wire. A flame formed in the combustion chamber CC by compression ignition in the diesel engine 100 can also be used as a source of charged particles. In this way, charged particles are generated by the operation accompanying ignition and combustion in the combustion engine. You may make it form plasma by using this charged particle as a trigger. Conversely, the charged particle supplier or electromagnetic wave emitter described above may be used to assist ignition or assist ignition or combustion.

  The charged particle supplier, electromagnetic wave emitter, and accelerator described above are not necessarily installed in the cylinder head 102. You may install in the cylinder body 101, piston 103, the gasket 104, the intake valve 120, the exhaust valve 125, etc., and you may install in the other member of the diesel engine 100.

  In each embodiment mentioned above, atomization of the fuel from the injector 130 of the direct injection type engine was promoted. However, the present invention is not limited to this. The injector may be applied to a PFI (Port Fuel Injection) type engine or a sub-chamber combustion type engine.

  In each above-mentioned embodiment, although the diesel engine was illustrated as a combustion engine, this invention is not limited to such a thing. It may be a self-ignition engine such as a spark-ignition internal combustion engine such as a gasoline engine, an HCCI (premixed compression auto-ignition) engine, or an SCCI (stratified compression auto-ignition) engine. Further, the engine is not limited to the piston type internal combustion engine, and may be an internal combustion engine such as a rotary engine, a gas turbine engine, or a ram engine. Further, the present invention is applicable to a combustor or a furnace of an external combustion engine that is not limited to an internal combustion engine. Further, the fuel to be atomized is not limited to the fuel immediately after being injected from the injector. The present invention can be applied to any portion in which a working fluid flows in a combustion engine to which the present invention is applied. In these cases, the arrangement and configuration of the charged particle supplier, electromagnetic wave emitter, and accelerator may be appropriately selected according to the combustion engine to be applied and the position through which the liquid phase fuel passes.

  The embodiment disclosed this time is merely an example, and the scope of the present invention is not limited to only the above-described embodiments. The scope of the present invention is indicated by each claim in the claims after considering the description of the specification and the drawings, and includes all modifications within the meaning and scope equivalent to the words described therein. It is a waste.

It is a schematic block diagram of 1st Embodiment. It is a schematic block diagram of 3rd Embodiment.

100 Combustion engine (diesel engine)
101 Cylinder Block 102 Cylinder Head 103 Piston 104 Gasket 120 Intake Valve 125 Exhaust Valve 140 Discharge Line 141 Electromagnetic Wave Transmission Line 150 Electrode Pair 151 Antenna 160 Discharge Voltage Generator 161 Electromagnetic Wave Generator 171 Controller 300 Cavity

Claims (3)

A device for promoting atomization of fuel injected from an injector,
Charged particle supply means;
Means for generating plasma in this space by irradiating electromagnetic waves using an antenna, forming a strong electric field in a space where charged particles exist, and supplying energy to the charged particles in the space;
With
A cavity surrounding the antenna and charged particle supply means is disposed;
An opening for communicating the combustion chamber and the inside of the cavity is provided at a position facing the injector tip portion of the cavity wall surface, and the fuel fine particles are characterized by changing the surface tension of the fuel using plasma ejected from the opening Promotion device. The fuel atomization promoting device according to claim 1, wherein the charged particle supply means supplies charged particles using an ignition means of a combustion engine. The means for generating the plasma maintains the formation of the plasma even after the surface tension is changed, and atomizes the fuel using the plasma. Fuel atomization promoting device.

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