JP6179004B2 - Electromagnetic radiation device - Google Patents

Description

  The present invention relates to an electromagnetic wave radiation device that radiates an electromagnetic wave to generate an electromagnetic wave plasma.

  2. Description of the Related Art Conventionally, electromagnetic wave emission devices that generate electromagnetic wave plasma by emitting electromagnetic waves are known. For example, Patent Document 1 describes this type of electromagnetic wave radiation device.

  FIG. 8 of Japanese Patent Application Laid-Open No. 51-77719 describes an internal combustion engine having an electromagnetic wave radiation device that can switch a microwave supply destination to four systems by a distributor (switcher). In this internal combustion engine, microwave energy is coupled to the burning plasma mixture via a spark plug. The distributor rotates the rotor and switches the switch.

JP 51-77719 A

  By the way, in the conventional electromagnetic wave emission apparatus, since the terminal antenna which supplies electromagnetic waves is switched by a mechanical switch, it is difficult to finely adjust the switching timing. For example, when electromagnetic waves are radiated sequentially to the plurality of combustion chambers of the engine in accordance with the ignition timing, it is difficult to finely adjust the switching timing with respect to changes in the engine speed.

  The present invention has been made in view of such a point, and an object thereof is to improve controllability of switching timing in an electromagnetic wave radiation device capable of switching terminal antennas that supply electromagnetic waves among a plurality of terminal antennas. There is.

  The first invention relates to an electromagnetic wave oscillator that oscillates an electromagnetic wave, a plurality of terminal antennas to which the electromagnetic wave output from the electromagnetic wave oscillator is radiated, and an electromagnetic wave output from the electromagnetic wave oscillator between the plurality of terminal antennas. The present invention is directed to an electromagnetic wave radiation device that includes a switching device that switches a terminal antenna to be supplied, and that generates electromagnetic wave plasma using electromagnetic waves radiated from the terminal antenna. And, in this electromagnetic wave radiation device, the switch receives a cavity resonator that forms a resonance space for resonating the electromagnetic wave output from the electromagnetic wave oscillator, and an electromagnetic wave generated by the electromagnetic wave oscillator, An input-side antenna that radiates the electromagnetic wave to the resonant space; and a plurality of output-side antennas that are provided corresponding to each of the terminal antennas, and that receive the electromagnetic wave output to the corresponding terminal antenna in the resonant space; An electromagnetic wave transmission line connecting the output antenna and the terminal antenna, respectively, and adjusting means for adjusting the electrical characteristics or conduction state of the transmission line; By switching the transmission line that allows the electromagnetic wave to pass between the lines, the output-side antenna that receives the electromagnetic wave is switched in the resonance space.

  In the first invention, in the switch, an electromagnetic wave is radiated from the input side antenna to the resonance space, and the terminal antenna that supplies the electromagnetic wave is switched by switching the output side antenna that receives the radiated electromagnetic wave. Switching of the output-side antenna that receives electromagnetic waves is performed by controlling adjusting means that adjusts the electrical characteristics or conduction state of the transmission line of each electromagnetic wave. That is, switching of the terminal antenna that supplies electromagnetic waves is performed by controlling the adjusting means.

  According to a second aspect, in the first aspect, each of the output side antennas is exposed to a strong electric field region where an electric field is relatively strong in the resonance space.

  In a third aspect based on the second aspect, the cavity resonator is provided with a plurality of the output-side antennas for one strong electric field region.

  According to a fourth invention, in the first or second invention, when the input side antenna receives a microwave, at least resonance points equal to or more than the number of the output side antennas are formed, and each of the output side antennas Are opposed to the resonance points of the input antenna at intervals.

  In a fifth aspect based on the fourth aspect, the input-side antenna is formed in a spiral shape.

  According to a sixth invention, in any one of the first to fifth inventions, the electromagnetic wave oscillator continuously outputs an electromagnetic wave pulse, and the electromagnetic wave oscillator oscillates the electromagnetic wave pulse over an electromagnetic wave driving period. The control means which continues switching the terminal antenna which supplies is provided.

  In the present invention, switching of the terminal antenna that supplies electromagnetic waves is performed by controlling adjusting means that adjusts the electrical characteristics or conduction state of the transmission line of each electromagnetic wave. Switching of the terminal antenna that supplies electromagnetic waves is performed by electrical adjustment. Therefore, the switching timing can be finely adjusted relatively easily, and the controllability of the switching timing can be improved.

  In the second invention, each output-side antenna is exposed to the strong electric field region in the resonance space, so that microwaves can be transmitted with high efficiency in the switch.

  In the third invention, the cavity resonator is provided with a plurality of output-side antennas for one strong electric field region, so that the cavity resonator can be made compact.

  In the fifth invention, since the input-side antenna is formed in a spiral shape, the volume occupied in the length direction of the input-side antenna can be reduced, and the cavity resonator can be made compact. .

  In the sixth aspect of the invention, since the oscillation of the electromagnetic wave is controlled so as to continuously output the electromagnetic wave pulse, the oscillation control of the electromagnetic wave can be facilitated.

FIG. 1 is a schematic configuration diagram of an internal combustion engine according to an embodiment. FIG. 2 is a block diagram of the electromagnetic wave emission device according to the embodiment. FIG. 3 is a schematic configuration diagram of a switch according to the embodiment. FIG. 4 is a schematic configuration diagram of an adjustment mechanism according to Modification 1 of the embodiment. FIG. 5 is a schematic configuration diagram of a switch according to the second modification of the embodiment. FIG. 6 is a time chart showing the switching timing of the microwaves in the electromagnetic wave emission device of Modification 2 of the embodiment. FIG. 7 is a schematic configuration diagram of a switch according to Modification 3 of the embodiment.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The following embodiments are essentially preferable examples, and are not intended to limit the scope of the present invention, its application, or its use.
Embodiment 1

The first embodiment is a multi-cylinder engine 10 including an electromagnetic wave emission device 13 according to the present invention. The electromagnetic wave emission device 13 constitutes a part of a plasma generation device 30 that generates microwave plasma by radiating microwaves to the combustion chamber 20 of each cylinder 24. The engine 10 includes an engine body 11 and a plasma generation device 30.
-Engine body-

  As shown in FIG. 1, the engine body 11 includes a cylinder block 21, a cylinder head 22, and a piston 23. A plurality of cylinders 24 having a circular cross section are formed in the cylinder block 21. A piston 23 is provided in each cylinder 24 so as to reciprocate. The piston 23 is connected to the crankshaft via a connecting rod (not shown). The crankshaft is rotatably supported by the cylinder block 21.

The cylinder head 22 is placed on the cylinder block 21 with the gasket 18 interposed therebetween. The cylinder head 22 defines the combustion chamber 20 together with the cylinder 24 and the piston 23. The cylinder head 22 is provided with one spark plug 15 for each cylinder 24. The cylinder head 22 has an intake port 25 and an exhaust port 26 for each cylinder 24. The intake port 25 is provided with an intake valve 27 and an injector 29. On the other hand, the exhaust port 26 is provided with an exhaust valve 28.
-Plasma generator-

  As shown in FIG. 2, the plasma generation device 30 includes a discharge device 12 and an electromagnetic wave emission device 13. The plasma generation device 30 generates microwave plasma obtained by enlarging the discharge plasma by supplying microwave energy radiated by the electromagnetic wave radiation device 13 to the discharge plasma generated by the discharge device 12.

  The discharge device 12 is provided for each combustion chamber 20. The discharge device 12 includes a pulse generator 14 that outputs a high voltage pulse, and a discharger 15 that generates a discharge in a discharge gap when the high voltage pulse from the pulse generator 14 is applied.

  The pulse generator 14 is, for example, an automobile ignition coil. The pulse generator 14 is connected to a direct current power source (for example, an automobile battery) (not shown). When the pulse generator 14 receives the ignition signal from the electronic control device 35, the pulse generator 14 boosts the voltage applied from the DC power supply, and outputs the boosted high voltage pulse to the discharger 15. The discharger 15 is, for example, an automobile spark plug. A high voltage pulse is supplied to the spark plug 15 via a mixer 34 described later. In the spark plug 15, when a high voltage pulse is supplied, dielectric breakdown occurs in the discharge gap between the center electrode 41 and the ground electrode 42, and discharge plasma (spark discharge) is generated.

  The electromagnetic wave radiation device 13 includes an electromagnetic wave power source 31, an electromagnetic wave oscillator 32, a switch 33, a mixer 34, and a terminal antenna 41. In the present embodiment, the center electrode 41 of the spark plug 15 also serves as the terminal antenna 41. In the electromagnetic wave radiation device 13, an electromagnetic power source 31, an electromagnetic wave oscillator 32, and a switch 33 are provided one by one, and a mixer 34 and a terminal antenna 41 are provided for each combustion chamber 20.

  When receiving an electromagnetic wave drive signal from the electronic control device 35, the electromagnetic wave power supply 31 supplies a pulse current to the electromagnetic wave oscillator 32. The electromagnetic wave drive signal is a pulse signal. The electromagnetic wave power supply 31 outputs a pulse current at a predetermined duty ratio from the rising point to the falling point of the electromagnetic wave drive signal. The pulse current is continuously output over the time of the pulse width of the electromagnetic wave drive signal.

  The electromagnetic wave oscillator 32 is, for example, a magnetron. When receiving the pulse current, the electromagnetic wave oscillator 32 outputs a microwave pulse. The electromagnetic wave oscillator 32 continuously outputs the microwave pulse over the time of the pulse width of the electromagnetic wave driving signal. The electromagnetic wave oscillator 32 can use another oscillator such as a semiconductor oscillator instead of the magnetron.

  The switch 33 switches the antenna that supplies the microwave output from the electromagnetic wave oscillator 32 among the plurality of terminal antennas 41. The switch 33 is controlled by the electronic control unit 35. Details of the switch 33 will be described later.

The mixer 34 receives the high voltage pulse from the pulse generator 14 and the microwave from the electromagnetic wave oscillator 32 at separate input terminals, and outputs the high voltage pulse and the microwave from the same output terminal to the spark plug 15. . The mixer 34 is configured to be able to mix high voltage pulses and microwaves. In the mixer 34, the first input terminal is electrically connected to the pulse generator 14, the second input terminal is electrically connected to the switch 33, and the output terminal is electrically connected to the terminal antenna 41. .
-Switcher-

  The switch 33 will be described in detail. As shown in FIG. 3, the switch 33 includes a cavity resonator 50, an input side antenna 51, an output side antenna 52, and an adjustment mechanism 53. The cavity resonator 50 forms a resonance space 60 for resonating the microwave output from the electromagnetic wave oscillator 32. The input-side antenna 51 receives the microwave generated by the electromagnetic wave oscillator 32 and radiates the microwave to the resonance space 60. The same number of output antennas 52 as the terminal antennas 41 are provided. The output side antenna 52 is provided corresponding to each of the terminal antennas 41. The output-side antenna 52 receives the microwave output to the corresponding terminal antenna 41 in the resonance space 60. The adjusting mechanism 53 is provided in each of the microwave transmission lines 55 that connect the output-side antenna 52 and the terminal antenna 41. The adjusting mechanism 53 constitutes adjusting means for adjusting the electrical characteristics or conduction state of the transmission line 55. The switch 33 is configured so that each adjustment mechanism 53 is controlled by the electronic control unit 35 and switches the transmission line 55 that allows the microwaves to pass between the plurality of transmission lines 55, thereby receiving the microwave in the resonance space 60. The side antenna 52 is switched.

  Specifically, the cavity resonator 50 is a box-shaped member that does not transmit microwaves. The cavity resonator 50 is formed in a rectangular parallelepiped shape. The length L in the longitudinal direction of the resonance space 60 satisfies the relationship L = n × (λ / 2), where λ is the wavelength of the microwave radiated from the input side antenna 51 to the resonance space 60. Note that n is a natural number of 2 or more, and is appropriately set according to the number of output-side antennas 52.

  The input-side antenna 51 is a rod-shaped conductor, and receives the microwave generated by the electromagnetic wave oscillator 32. In this embodiment, the cavity resonator 50 is integrated with the electromagnetic wave oscillator 32 (magnetron), and the output antenna of the electromagnetic wave oscillator 32 also serves as the input side antenna 51. The input-side antenna 51 receives microwaves generated by the main body (vacuum tube) of the electromagnetic wave oscillator 32. The input side antenna 51 may be connected to the output antenna of the electromagnetic wave oscillator 32 via a coaxial cable or a coaxial waveguide.

The input side antenna 51 is provided on one end side in the longitudinal direction of the cavity resonator 50. The input side antenna 51 passes through the bottom surface (lower surface) of the cavity resonator 50 in FIG. 3 and is exposed to the resonance space 60. The microwave generated by the main body (vacuum tube) of the electromagnetic wave oscillator 32 is radiated from the input side antenna 51 to the resonance space 60. In the resonance space 60, the microwave resonates in the TE ₁₀ mode, for example. In addition, the resonance space 60 in FIG. 3 is the figure which looked at the inside of the resonance space 60 from the side. In FIG. 3, the path of the switching signal and the electromagnetic wave drive signal is shown, but the path of the ignition signal is omitted, and this point is the same in FIGS. 5 and 7.

  Each output side antenna 52 is a rod-shaped conductor, and receives the microwave radiated from the input side antenna 51 to the resonance space 50. Each output-side antenna 52 penetrates the upper surface of the cavity resonator 50 in FIG. 3 and is exposed to the resonance space 60. The output side antennas 52 are arranged at equal intervals in the longitudinal direction of the cavity resonator 50. Each output-side antenna 52 is disposed at the antinode of the standing wave formed by the microwave in the resonance space 60. Each output antenna 52 is exposed to a strong electric field region where the electric field is relatively strong in the resonance space 60. Each output antenna 52 has a protruding length in the resonance space 50 according to the characteristic impedance of the transmission line 55 connected to the output antenna 52. The protruding length of each output-side antenna 52 is, for example, a quarter of the wavelength λ of the microwave output from the electromagnetic wave oscillator 32.

  One end of a micro transmission line 55 (for example, a coaxial cable) is connected to the base end of each output antenna 52. The other end of the transmission line 55 is connected to the second input terminal of the mixer 34. Each output antenna 52 is connected to the terminal antenna 41 via the mixer 34. Each output-side antenna 52 receives the microwave output to the corresponding terminal antenna 41.

  Each adjustment mechanism 53 is a switch element that switches the transmission line 55 between a conductive state (on state) and a non-conductive state (off state). Each adjustment mechanism 53 is switched on / off in response to a switching signal output from the electronic control unit 35. As the switch element, a Schottky diode, a PIN diode, a FET switch, an IC switch, a MEMS switch, or the like can be used. In the transmission line 55, since microwaves with relatively high power flow to generate microwave plasma, a switch element with high withstand voltage is suitable.

The switch 33 is controlled by the electronic control unit 35 so that only one of the plurality of adjusting mechanisms 53 is in a conductive state. Only the output side antenna 52 corresponding to the adjustment mechanism 53 in the conductive state receives the microwave in the resonance space 60. Then, the microwave received by the output antenna 52 is supplied to the corresponding terminal antenna 41. In the switch 33, the adjustment mechanism 53 to be in a conductive state is switched in order. As a result, the output-side antenna 52 that receives the microwave in the resonance space 60 is switched in order, and the terminal antenna 41 to which the microwave is supplied is switched in order.
-Operation of plasma generator-

  The operation of the plasma generation device 30 will be described with reference to the operation of the engine body 11.

  The engine 10 performs a plasma ignition operation for igniting the air-fuel mixture in the combustion chamber 20 with the microwave plasma generated by the plasma generator 30. The ignition timing is shifted between the plurality of combustion chambers 20.

  In each cylinder 24, immediately before the piston 23 reaches top dead center, the intake valve 27 is opened and the intake stroke is started. Then, immediately after the piston 23 passes through the top dead center, the exhaust valve 28 is closed, and the exhaust stroke ends. The electronic control unit 35 outputs an injection signal to the injector 29 corresponding to the cylinder 24 during the intake stroke, and causes the injector 29 to inject fuel.

  Subsequently, immediately after the piston 23 passes the bottom dead center, the intake valve 27 is closed, and the intake stroke is completed. When the intake stroke ends, the compression stroke starts. The electronic control unit 35 outputs an ignition signal to the pulse generator 14 corresponding to the cylinder 24 during the compression stroke, immediately before the piston 23 reaches top dead center. As a result, the high voltage pulse output from the pulse generator 14 is supplied to the spark plug 15. As a result, discharge plasma is generated in the discharge gap of the spark plug 15.

  The electronic control unit 35 outputs an electromagnetic wave drive signal to the electromagnetic wave power supply 31 immediately before the high voltage pulse is output from the pulse generator 14 corresponding to each cylinder 24. Prior to the output of the electromagnetic wave drive signal, the adjustment mechanism 53 of the switch 33 is switched so that the spark plug 15 corresponding to the pulse generator 14 to which the ignition signal is input becomes the microwave supply destination. ing. The electronic control unit 35 switches the adjustment mechanism 53 of the transmission line 55 connected to the terminal antenna 41 of the cylinder 24 to be ignited this time to the conducting state, and adjusts the transmission mechanism 55 of the transmission line 55 connected to the terminal antenna 41 of the cylinder 24 previously ignited. Is switched to the non-conducting state.

  As a result, a pulse current is output from the electromagnetic wave power supply 31 to the electromagnetic wave oscillator 32, and a microwave pulse is output from the electromagnetic wave oscillator 32. The microwave pulse is radiated from the terminal antenna 41 (the center electrode 41 of the spark plug 15) to the combustion chamber 20. The microwave pulse is continuously emitted immediately before and after the discharge plasma is generated. At the timing when the discharge plasma is generated, a strong electric field region (a region where the electric field strength is relatively strong in the combustion chamber 20) is formed near the tip of the center electrode 41 by the microwave pulse. The discharge plasma absorbs microwave energy and expands to become a relatively large microwave plasma. In the combustion chamber 20, the air-fuel mixture is ignited by the microwave plasma, and combustion of the air-fuel mixture is started.

  Note that the emission start timing of the microwave pulse from the terminal antenna 41 may be after the generation of the discharge plasma as long as the discharge plasma is not extinguished.

In the cylinder 24, the piston 23 is moved to the bottom dead center side by the expansion force when the air-fuel mixture burns. Then, immediately before the piston 23 reaches bottom dead center, the exhaust valve 28 is opened and the exhaust stroke is started. As described above, the exhaust stroke ends immediately after the start of the intake stroke.
-Effect of the embodiment-

  In the present embodiment, switching of the terminal antenna 41 that supplies the microwave is performed by controlling each adjustment mechanism 53 that adjusts the conduction state of the transmission line 55 of each microwave. Switching of the terminal antenna 41 that supplies the microwave is performed by electrical adjustment. Therefore, the switching timing can be finely adjusted relatively easily, and the controllability of the switching timing can be improved.

In the present embodiment, since each output antenna 52 is exposed to the strong electric field region in the resonance space 60, the switch 33 can transmit microwaves with high efficiency.
-Modification 1 of embodiment-

  In the first modification, the adjustment mechanism 53 is configured to be able to adjust the self-inductance, the resistance value, or the capacitance as the electrical characteristics. In the switch 33, the adjustment mechanism 53 is controlled to adjust the electrical characteristics of each transmission line 55, so that the transmission line 55 through which the microwave is most likely to pass is switched among all the transmission lines 55. The output-side antenna 53 connected to the transmission line 55 through which waves most easily pass receives the microwaves in the resonance space 60.

  For example, when each adjustment mechanism 53 adjusts the self-inductance, among all the adjustment mechanisms 53, the self-inductance of the adjustment mechanism 53 of the transmission line 55 connected to the output-side antenna 53 that wants to receive microwaves is minimized. Adjusted.

For example, as shown in FIG. 4, the adjusting mechanism 53 includes a cylindrical insulator 61 through which the transmission line 55 is inserted, a coil 62 wound around the outer peripheral surface of the insulator 61, and the coil 62 as a power source 65. And an electric circuit 63 connected to the electric circuit 63 and a switch 64 provided in the electric circuit 63. When the switch 64 of the adjustment mechanism 53 is set to the on state, the self-inductance of the portion inserted through the insulator 61 of the transmission line 55 increases due to the magnetic field formed by the current flowing through the coil 62. In the switch 33, the switch 64 of the adjustment mechanism 53 of the transmission line 55 of the output antenna 53 that does not receive microwaves is set to the on state, and the adjustment mechanism 53 of the transmission line 55 of the output antenna 53 that receives microwaves is set. The switch 64 is set to an off state.
-Modification 2 of embodiment-

  In the second modification, as shown in FIG. 5, in the cavity resonator 50, output-side antennas 52 are respectively provided on two surfaces facing each other. In FIG. 5, a plurality of output-side antennas 52 are arranged at equal intervals in the longitudinal direction on the upper and lower surfaces of the cavity resonator 50, respectively. In the cavity resonator 50, a pair of upper-side output-side antennas 52 and lower-side output-side antennas 52 are arranged at positions of antinodes of standing waves formed by microwaves. According to the second modification, since a plurality of output-side antennas 52 are provided for one strong electric field region in the cavity resonator 50, a large number of systems can be obtained without enlarging the cavity resonator 50 so much. Microwaves can be distributed to

  In the second modification, the plasma generation device 30 constitutes an exhaust gas purification device that purifies exhaust gas using plasma. The plasma generator 30 is provided so that the discharge gap of each spark plug 15 is located in the exhaust flow path in the exhaust pipe 65. Radiation ends of the terminal antennas 41a to 41f (center electrode) of each spark plug 15 are exposed to the exhaust passage.

  The plasma generation device 30 includes a plasma control device 70 (control means) that controls the discharge device 12 and the electromagnetic wave emission device 13. The plasma generator 30 controls the on / off of the electromagnetic wave power source 31 of the electromagnetic wave emission device 13 and outputs an ignition signal to the pulse generator 14 during the electromagnetic wave driving period in which the electromagnetic wave power source 31 is set to the on state. At the same time, a switch signal is output to the switch 33.

  The exhaust gas purification operation by the plasma generator 30 will be described.

  In the exhaust gas purification operation, for example, when the circulation of the exhaust gas is started in the exhaust pipe 65, the plasma control device 70 outputs a drive start signal, and the electromagnetic wave power supply 31 is set to the on state. Then, the electromagnetic wave power supply 31 starts to output a pulse current at a predetermined duty ratio, and the electromagnetic wave oscillator 32 receiving the pulse current starts to output a microwave pulse at a predetermined duty ratio. The electromagnetic wave driving period starts. The electromagnetic wave driving period is continued until the plasma control device 70 outputs a driving end signal and the electromagnetic wave power supply 31 is set to the off state.

  During the electromagnetic wave driving period, microwave pulses are continuously output at a predetermined duty ratio. Further, during the electromagnetic wave driving period, as shown in FIG. 6, the plasma control device 70 is configured so that the microwaves for a certain time are sequentially supplied to all the terminal antennas 41 a to 41 f. A switching signal is output to the adjusting mechanism 53. Moreover, the plasma control apparatus 70 supplies an ignition signal to the pulse generator 14 corresponding to the terminal antennas 41a to 41f from which microwaves are radiated. As a result, high voltage pulses are supplied to the terminal antennas 41a to 41f that are emitting microwaves, and the discharge plasma generated by the high voltage pulses absorbs microwave energy and expands.

  Here, when the exhaust gas is purified by plasma, the decomposition rate of harmful substances in the exhaust gas increases as the time during which the exhaust gas contacts the plasma becomes longer. For this reason, the electromagnetic wave power source 31 is improved while the microwave pulse is continuously output to the electromagnetic wave oscillator 32 so that the microwave plasma is generated without interruption at any position in the exhaust flow path. Makes it easier to control.

In the cavity resonator 50, the configuration in which the output-side antennas 52 are provided on the two surfaces facing each other can also be adopted when the plasma generation device 30 is applied to the engine 10.
—Modification 3 of Embodiment—

  In Modification 3, as shown in FIG. 7, each output-side antenna 52 faces the input-side antenna 51 at a predetermined interval.

The input side antenna 51 is configured such that a plurality of resonance points are formed at predetermined positions when microwaves are input. Each output antenna 52 faces each resonance point in the input antenna 51. The direction of each output antenna 52 is set in consideration of the direction of the electric field and magnetic field at the resonance point. In the modified example 3, since the input side antenna 51 is formed in a spiral shape, the length of the occupied space of the input side antenna 51 is shortened.
<< Other Embodiments >>

  The embodiment may be configured as follows.

  In the embodiment, the plasma generation device 30 may omit the discharge device 12 and generate the microwave plasma only with the electromagnetic wave emission device 13. In this case, the peak power required to generate the microwave plasma increases, but the apparatus configuration can be simplified. Further, instead of the discharge device 12, a glow plug that emits thermoelectrons may be used. In this case, the thermoelectrons are accelerated by microwave energy, and microwave plasma is generated.

  In the above embodiment, the center electrode 41 to which a high voltage pulse is supplied is used as the terminal antenna. However, the terminal antenna 41 may be provided separately from the center electrode 41. The terminal antenna 41 can be provided, for example, so as to penetrate the ignition plug 15 or can be provided on the cylinder head 22.

  In the embodiment, when there are three or more terminal antennas 41, the switch 33 transmits the electromagnetic waves so that the number of terminal antennas 41 that simultaneously supply electromagnetic waves is plural (a number smaller than the total number of terminal antennas 41). The terminal antenna 41 to be supplied may be switched. For example, in the above-described embodiment, the combination of the plurality of adjustment mechanisms 53 set to the on state is changed.

  In the embodiment, a plurality of terminal antennas 41 may be provided for one combustion chamber 20. In the combustion chamber 20, microwaves are radiated from the plurality of terminal antennas 41 at different timings. In the vicinity of the plurality of terminal antennas 41, microwave plasma is generated at different timings.

  As described above, the present invention is useful for an electromagnetic wave emission device that generates electromagnetic wave plasma by emitting an electromagnetic wave.

13 Electromagnetic radiation device
30 Plasma generator
32 Electromagnetic wave oscillator
33 selector
41 Terminal antenna
50 Cavity resonator
51 Input antenna
52 Output antenna
53 Adjustment mechanism (adjustment means)
55 Microwave transmission line (electromagnetic wave transmission line)
60 Resonance space

Claims (6)

An electromagnetic wave oscillator that oscillates electromagnetic waves;
A plurality of terminal antennas from which electromagnetic waves output from the electromagnetic wave oscillator are radiated;
A switch for switching a terminal antenna for supplying an electromagnetic wave output from the electromagnetic wave oscillator between the plurality of terminal antennas;
An electromagnetic wave radiation device that generates electromagnetic wave plasma using electromagnetic waves radiated from the terminal antenna or heats a target substance,
The switch is
A cavity resonator that forms a resonance space for resonating an electromagnetic wave output from the electromagnetic wave oscillator;
An input side antenna that receives an electromagnetic wave generated by the electromagnetic wave oscillator and radiates the electromagnetic wave to the resonance space;
A plurality of output-side antennas provided corresponding to each of the terminal antennas and receiving electromagnetic waves output to the corresponding terminal antenna via a transmission path in the resonance space;
A cylindrical insulator that is provided in an electromagnetic wave transmission line that connects the output antenna and the terminal antenna, and that adjusts the self-inductance of the transmission line, and the outer periphery of the insulator A coil wound around the surface, an electrical circuit for connecting the coil to a power source, and a control means comprising a switch provided in the electrical circuit ,
A self-inductance state is controlled by turning on and off the switch of the adjusting unit , and a transmission line that transmits electromagnetic waves is switched between a plurality of transmission lines, and an output antenna that receives the electromagnetic waves in the resonance space is switched. Electromagnetic radiation device. In the electromagnetic wave emission device according to claim 1,
Each of the output side antennas is exposed to a strong electric field region where an electric field is relatively strong in the resonance space. In the electromagnetic wave emission device according to claim 2,
In the cavity resonator, the plurality of output antennas are provided for one strong electric field region. In the electromagnetic wave emission device according to claim 1 or 2,
When the input antenna receives microwaves, at least resonance points equal to or greater than the number of the output antennas are formed.
Each of the output side antennas is opposed to each resonance point of the input side antenna at an interval, and the electromagnetic wave radiation device is characterized in that: In the electromagnetic wave emission device according to claim 4,
The electromagnetic wave radiation device, wherein the input-side antenna is formed in a spiral shape. In the electromagnetic wave emission device according to any one of claims 1 to 5,
The electromagnetic wave oscillator continuously outputs an electromagnetic wave pulse,
An electromagnetic wave radiation device comprising: a control unit that continuously switches a terminal antenna that supplies an electromagnetic wave over an electromagnetic wave driving period in which the electromagnetic wave oscillator oscillates an electromagnetic wave pulse.

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