JP2008082286A - Internal combustion engine, and its igniter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently ignite an air-fuel mixture in a combustion chamber with further small energy consumption without complicating a structure. <P>SOLUTION: When a D.C. voltage is applied between a center electrode 51 and a ground electrode 53, a spark plug 31 can ignite the air-fuel mixture in the combustion chamber 3 by D.C. discharge generated in a gap 52 between a tip 51a of the center electrode 51 and a tip 53a of the ground electrode 53. When electromagnetic waves are radiated toward the inside of the combustion chamber 3 from an electromagnetic wave radiator, the spark plug 31 can ignite the air-fuel mixture in the combustion chamber 3 by plasma discharge generated by locally enhancing electromagnetic intensity of the electromagnetic waves in the combustion chamber 3 in the vicinity of the tip 51a of the center electrode 51 and in the vicinity of the tip 53a of the ground electrode 53. By selectively carrying out either ignition by the plasma discharge or by the D.C. discharge, electric energy consumed in igniting the air-fuel mixture can be reduced. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an internal combustion engine and its ignition device, and more particularly to an internal combustion engine capable of igniting an air-fuel mixture in a combustion chamber using electromagnetic waves and its ignition device.

  As an ignition device for this type of internal combustion engine, a device disclosed in Patent Document 1 below is disclosed. Hereinafter, the ignition device for an internal combustion engine of Patent Document 1 will be described with reference to FIG.

  In the ignition device 101 shown in FIG. 17, a coaxial resonator (coaxial line) 103 includes an outer conductor 104 and an inner conductor 105. A supply line 108 is coaxially coupled inductively and / or capacitively to a coupling point 107 provided at one end of the inner conductor 105 of the resonator 103, and a high-frequency signal ( Electromagnetic wave) is supplied to the resonator 103 via the supply line 108. On the other hand, the other end 105a of the inner conductor 105 opened by the resonator 103 enters the combustion chamber of the internal combustion engine, and the other end 105a serves as an ignition pin to ignite the air-fuel mixture in the combustion chamber.

  In addition, the ignition device of the internal combustion engine by the following patent documents 2-5 is indicated. Further, a technique using microwaves for detecting the piston position of an internal combustion engine is disclosed in Patent Document 6 below.

JP 2004-87498 A JP 2006-132518 A JP 2005-183396 A JP 2005-180446 A JP 2005-180435 A U.S. Pat. No. 4,403,504

  In an ignition device that radiates electromagnetic waves into the combustion chamber and ignites the mixture, a leaner mixture can be ignited compared to an ignition device that ignites the mixture by applying a DC voltage to the spark plug. Although possible, the electrical energy consumed when the mixture is ignited increases. Therefore, in an ignition device that can ignite an air-fuel mixture in a combustion chamber using electromagnetic waves, it is required that the air-fuel mixture can be efficiently ignited with less energy consumption without complicating the configuration.

  An object of the present invention is to provide an internal combustion engine that can efficiently ignite an air-fuel mixture in a combustion chamber with less energy consumption without complicating the configuration, and an ignition device thereof.

  The internal combustion engine and its ignition device according to the present invention employ the following means in order to achieve the above-described object.

  An ignition apparatus for an internal combustion engine according to the present invention is an ignition apparatus for an internal combustion engine that ignites an air-fuel mixture in a combustion chamber, and a DC discharge that is generated by applying a DC voltage between ignition electrodes protruding into the combustion chamber. An ignition plug capable of igniting the air-fuel mixture in the combustion chamber, an electromagnetic wave generation source for generating an electromagnetic wave, an electromagnetic wave emitter for radiating the electromagnetic wave generated in the electromagnetic wave generation source toward the combustion chamber, When a DC voltage is applied between the ignition electrodes, the spark plug ignites the air-fuel mixture in the combustion chamber by a DC discharge generated between the ignition electrodes, and the electromagnetic wave generated by the electromagnetic wave generation source When radiated from an electromagnetic wave emitter into the combustion chamber, the mixture in the combustion chamber should be ignited by plasma discharge generated by locally increasing the electric field strength of the electromagnetic wave in the combustion chamber in the vicinity of the ignition electrode. Abstract To.

  In the present invention, an air-fuel mixture in the combustion chamber can be ignited by applying a DC voltage between the ignition electrodes of the spark plug to generate a DC discharge between the ignition electrodes. Furthermore, the air-fuel mixture in the combustion chamber is ignited by plasma discharge generated by radiating electromagnetic waves into the combustion chamber and locally increasing the electric field strength of the electromagnetic waves in the combustion chamber near the ignition electrode of the spark plug. can do. Thus, not only ignition by plasma discharge using electromagnetic waves but also ignition by direct current discharge of the spark plug can reduce energy consumed when the air-fuel mixture is ignited. Furthermore, since the plasma discharge can be generated by locally increasing the electric field strength of the electromagnetic wave in the combustion chamber using the spark plug, the configuration of the apparatus is not complicated. Therefore, according to the present invention, the air-fuel mixture in the combustion chamber can be efficiently ignited with less energy consumption without complicating the configuration.

  In one embodiment of the present invention, it is preferable that the protruding length of the ignition electrode into the combustion chamber is set to be 0.17 times or more and 0.33 times or less of the wavelength of the electromagnetic wave. According to this aspect, the electric field strength of the electromagnetic wave in the combustion chamber can be efficiently increased in the vicinity of the ignition electrode, and plasma discharge can be efficiently generated.

  In one aspect of the present invention, an electromagnetic wave transmission means for supplying an electromagnetic wave generated by an electromagnetic wave generation source to an ignition plug is provided, and the electromagnetic wave generated by the ignition plug as an electromagnetic wave emitter is burned from the ignition electrode. It is preferable to radiate indoors. According to this aspect, the spark plug can be used to radiate electromagnetic waves toward the combustion chamber, and the electric field strength of the electromagnetic waves in the combustion chamber can be locally increased to generate plasma discharge. The configuration of the apparatus can be simplified. In this aspect, the electromagnetic wave transmission means includes a waveguide, one end of the spark plug is inserted into the waveguide, and the ignition electrode projects into the combustion chamber at the other end of the spark plug. Is preferred.

  In one aspect of the present invention, when igniting an air-fuel mixture in a combustion chamber, a DC voltage is applied between the electrodes for ignition, or an electromagnetic wave is generated by an electromagnetic wave generation source and radiated from an electromagnetic wave radiator toward the combustion chamber. It is preferable to select whether to do this based on the air-fuel ratio of the air-fuel mixture. According to this aspect, an appropriate ignition method can be selected based on the air-fuel ratio of the air-fuel mixture. Further, in this aspect, when the air-fuel ratio of the air-fuel mixture is within the stoichiometric air-fuel ratio and a range in the vicinity thereof, by selecting the method of applying a DC voltage between the ignition electrodes, the air-fuel mixture is ignited. The consumed energy can be reduced. Further, in this aspect, when the air-fuel ratio of the air-fuel mixture is equal to or greater than a predetermined ratio greater than the stoichiometric air-fuel ratio, the method of generating an electromagnetic wave from the electromagnetic wave generation source and radiating it from the electromagnetic wave radiator into the combustion chamber is selected. By doing so, a leaner air-fuel mixture can be ignited.

  An ignition device for an internal combustion engine according to the present invention is an ignition device for an internal combustion engine that ignites an air-fuel mixture in a combustion chamber, and is generated when a DC voltage is applied between discharge electrodes protruding into the combustion chamber. An ignition plug capable of igniting the air-fuel mixture in the combustion chamber by direct current discharge; an electromagnetic wave generation source for generating electromagnetic waves; and an electromagnetic wave transmission means for propagating the electromagnetic waves generated by the electromagnetic wave generation source to the ignition plugs An electrode arranged facing the combustion chamber, the electrode for ignition for locally increasing the electric field strength of the electromagnetic wave in the combustion chamber in the vicinity of the electrode when the electromagnetic wave propagates in the combustion chamber When a DC voltage is applied between the discharge electrodes, the mixture in the combustion chamber is ignited by a DC discharge generated between the discharge electrodes, and when an electromagnetic wave is generated by the electromagnetic wave generation source, the ignition plug From the discharge electrode Towards chamber radiates, ignition electrode is summarized in that igniting the air-fuel mixture in the combustion chamber by a plasma discharge generated by increasing locally the field strength of the electromagnetic wave in the combustion chamber at its near.

  In the present invention, an air-fuel mixture in the combustion chamber can be ignited by applying a DC voltage between the discharge electrodes of the spark plug to generate a DC discharge between the discharge electrodes. Further, the plasma discharge generated by radiating electromagnetic waves from the discharge electrode of the ignition plug toward the combustion chamber and locally increasing the electric field strength of the electromagnetic waves in the combustion chamber in the vicinity of the ignition electrode The mixture can be ignited. Thus, not only ignition by plasma discharge using electromagnetic waves but also ignition by direct current discharge of the spark plug can reduce energy consumed when the air-fuel mixture is ignited. Furthermore, since the electromagnetic wave can be radiated into the combustion chamber using the spark plug, the configuration of the apparatus is not complicated. Therefore, according to the present invention, the air-fuel mixture in the combustion chamber can be efficiently ignited with less energy consumption without complicating the configuration.

  In one aspect of the present invention, the electromagnetic wave transmission means includes a waveguide, one end of the spark plug is inserted into the waveguide, and the discharge electrode projects into the combustion chamber at the other end of the spark plug. It is preferable that In one embodiment of the present invention, when the discharge electrode as the ignition electrode propagates an electromagnetic wave in the combustion chamber, it is preferable to locally increase the electric field strength of the electromagnetic wave in the combustion chamber near the electrode. According to this aspect, the spark plug can be used to radiate electromagnetic waves toward the combustion chamber, and the electric field strength of the electromagnetic waves in the combustion chamber can be locally increased to generate plasma discharge. The configuration of the apparatus can be simplified.

  In one embodiment of the present invention, the length of protrusion of the discharge electrode into the combustion chamber is set to be 0.17 to 0.33 times the wavelength of the electromagnetic wave, so that the electromagnetic wave is burned from the discharge electrode. It can radiate efficiently toward the room. Further, according to one aspect of the present invention, the length of protrusion of the ignition electrode into the combustion chamber is set to be not less than 0.17 times and not more than 0.33 times the wavelength of the electromagnetic wave. Thus, the electric field strength of the electromagnetic wave in the combustion chamber can be increased efficiently, and plasma discharge can be generated efficiently.

  An ignition device for an internal combustion engine according to the present invention is an ignition device for an internal combustion engine that ignites an air-fuel mixture in a combustion chamber, and an electromagnetic wave generation source for generating an electromagnetic wave and an electromagnetic wave generated by the electromagnetic wave generation source. Electromagnetic wave emitter for radiating into the combustion chamber, and an electrode protruding and disposed in the combustion chamber, and an ignition electrode for locally increasing the electric field strength of the electromagnetic wave in the combustion chamber in the vicinity of the electrode And the protruding length of the ignition electrode into the combustion chamber is set to be 0.17 times or more and 0.33 times or less of the wavelength of the electromagnetic wave, and the ignition electrode is in the vicinity of the combustion chamber. The gist is to ignite the air-fuel mixture in the combustion chamber by plasma discharge generated by locally increasing the electric field strength of the electromagnetic wave.

  In the present invention, when the air-fuel mixture in the combustion chamber is ignited, the electric field strength of the electromagnetic wave in the combustion chamber can be increased efficiently in the vicinity of the ignition electrode, and plasma discharge can be generated efficiently. Therefore, according to the present invention, the air-fuel mixture in the combustion chamber can be efficiently ignited with less energy consumption without complicating the configuration.

  Moreover, the internal combustion engine which concerns on this invention is an internal combustion engine which ignites the air-fuel | gaseous mixture in a combustion chamber with an ignition device, Comprising: Let the said ignition device be an ignition device of the internal combustion engine which concerns on this invention.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention (hereinafter referred to as embodiments) will be described with reference to the drawings.

“Embodiment 1”
FIG. 1 is a diagram showing a schematic configuration of an ignition device for an internal combustion engine according to Embodiment 1 of the present invention, together with the internal combustion engine. The ignition device for an internal combustion engine according to the present embodiment can ignite an air-fuel mixture (air / fuel mixture) in the combustion chamber 3 by radiating electromagnetic waves toward the combustion chamber 3.

  The internal combustion engine (engine) includes a cylinder block 20 and a cylinder head 22, and the cylinder block 20 and the cylinder head 22 form a cylinder. The cylinder bore formed in the cylinder block 20 accommodates a piston 11 that reciprocates in the axial direction thereof. The space surrounded by the top surface of the piston 11, the inner wall of the cylinder block 20, and the cylinder head 22 forms a combustion chamber 3.

  The electromagnetic wave generating power source 1 can be constituted by, for example, a solid element, a magnetron, or a traveling wave amplifier tube, and plays a role of generating and amplifying electromagnetic waves (for example, microwaves). The electromagnetic wave generating power source 1 can control the output by controlling the gain and pulse width of the electromagnetic wave. The electromagnetic wave generating power source 1 generates an electromagnetic wave when igniting the air-fuel mixture in the combustion chamber 3, and the generated electromagnetic wave propagates through the electromagnetic wave transmission path 2.

  The end of the electromagnetic wave transmission path 2 faces the combustion chamber 3 through the inside of the cylinder head 22. An electromagnetic wave radiator 4 that radiates an electromagnetic wave generated by the electromagnetic wave generation power source 1 and propagated through the electromagnetic wave transmission line 2 is provided at an end of the electromagnetic wave transmission line 2. As described above, the electromagnetic wave radiator 4 is disposed in the cylinder head 22 so as to face the combustion chamber 3, and thus electromagnetic waves are radiated from the electromagnetic wave radiator 4 into the combustion chamber 3. About the electromagnetic wave emitter 4 here, in order to radiate | emit electromagnetic waves in the combustion chamber 3 with high efficiency, the length x1 equivalent to 17 to 33% of the wavelength of the electromagnetic waves to be used is made to protrude into the combustion chamber 3. Yes. That is, the protrusion length (insertion length) x1 of the electromagnetic wave radiator 4 into the combustion chamber 3 is set to be 0.17 times or more and 0.33 times or less of the wavelength of the electromagnetic wave to be used.

  In addition, as the electromagnetic wave transmission line 2 here, a coaxial cable, a waveguide, etc. can be used, for example. When a coaxial cable is used as the electromagnetic wave transmission path 2, the electromagnetic wave radiator 4 can be configured by, for example, an open inner conductor end of the coaxial cable. On the other hand, when a waveguide is used as the electromagnetic wave transmission path 2, for example, an insulator (for example, a dielectric such as a ceramic having a low dielectric constant) prevents the air-fuel mixture from flowing into the waveguide at the open end of the waveguide. ), The electromagnetic wave radiator 4 can be configured. In addition, the piston 11, the cylinder block 20, and the cylinder head 22 that are made of a conductor also function as a ground conductor, thereby playing a role of shielding electromagnetic waves in the combustion chamber 3.

  In this embodiment, the ignition electrode 10 faces the combustion chamber 3 and is attached to the cylinder head 22. As for the ignition electrode 10 here, a length x2 corresponding to 17 to 33% of the wavelength of the electromagnetic wave used is projected into the combustion chamber 3 with respect to the lower surface of the cylinder head 22 (conductor). That is, the protruding length (insertion length) x2 of the ignition electrode 10 into the combustion chamber 3 is set to be 0.17 times or more and 0.33 times or less of the wavelength of the electromagnetic wave to be used. FIG. 1 shows an example in which the ignition electrode 10 is disposed at the center of the upper surface of the combustion chamber 3 and the tip of the ignition electrode 10 protruding into the combustion chamber 3 has an acute cone shape.

  The ignition electrode 10 serves to locally increase the electric field strength of the electromagnetic wave in the combustion chamber 3 in the vicinity thereof. That is, the electromagnetic wave radiated from the electromagnetic wave emitter 4 fills the combustion chamber 3, but in the vicinity of the tip of the ignition electrode 10, the combustion chamber 3 has a difference in permeability between the ignition electrode 10 and the space in the combustion chamber 3. A high electric field of several tens to several hundred times the average electric field of the electromagnetic wave can be obtained. As a result, in the vicinity of the tip of the ignition electrode 10, a breakdown occurs in which a current flows in the space in the combustion chamber 3 with the supply of electromagnetic waves. Then, starting from that, plasma discharge is generated in a wide range in the combustion chamber 3, whereby the air-fuel mixture in the combustion chamber 3 can be ignited. The region where the plasma discharge occurs here varies depending on the amount of electromagnetic wave energy supplied. In the present embodiment, by adjusting the electromagnetic wave energy supplied into the combustion chamber 3 according to the operating conditions of the internal combustion engine, it is possible to realize appropriate combustion of the air-fuel mixture. As a typical example, a plasma discharge can be generated by radiating an electromagnetic wave having an energy of about 1 J from the electromagnetic wave emitter 4, and an air-fuel mixture can be ignited.

  Further, the above-described operation will be described in detail based on basic calculations and test results using a grounded cylindrical airtight container (constant volume container) 23. As shown in FIG. 2, the electromagnetic wave emitter 4 is provided at the center of the lower plane of the grounded metal container 23, and the ignition electrode 10 is provided on the upper surface thereof. About the electromagnetic wave radiator 4 and the electrode 10 for ignition here, the insertion length in the container 23 can be changed arbitrarily. When electromagnetic waves are emitted from the electromagnetic wave radiator 4 into the container 23, an electric field distribution is generated in the container 23. As shown in FIG. 2, the electric field in the container 23 becomes high in the vicinity of the electromagnetic wave radiator 4 and the ignition electrode 10.

  Here, the insertion length of the ignition electrode 10 into the container 23 is changed in a state where the insertion length of the electromagnetic wave emitter 4 into the container 23 is kept constant (fixed to ¼ of the supplied electromagnetic wave wavelength). Let FIG. 3 shows the relationship between the insertion length of the ignition electrode 10 and the electric field intensity directly below the ignition electrode 10 in that case. However, in FIG. 3, it is set as the dimensionless length which divided the insertion length of the electrode 10 for ignition by the electromagnetic wave wavelength. As shown in FIG. 3, the electric field intensity directly under the ignition electrode 10 is almost saturated when the dimensionless length is 0.17 or more (the insertion length of the ignition electrode 10 is 0.17 times or more of the electromagnetic wave wavelength), It becomes the maximum when the dimensionless length is 0.25 (the insertion length of the ignition electrode 10 is ¼ of the electromagnetic wave wavelength). The electric field intensity immediately below the ignition electrode 10 decreases rapidly when the dimensionless length becomes 0.33 or more (the insertion length of the ignition electrode 10 is 0.33 times or more the electromagnetic wave wavelength). Here, the change in electric field strength when the insertion length of the ignition electrode 10 is changed has been described, but the same change in electric field strength occurs even when the insertion length of the electromagnetic wave radiator 4 is changed.

  The ignition electrode 10 protruding into the container 23 serves to locally concentrate the electric field in the vicinity thereof. The effect of the electric field concentration depends on the insertion length of the ignition electrode 10 and is remarkably obtained at a length corresponding to 17 to 33% of the supplied electromagnetic wave wavelength, and a length corresponding to 25% of the supplied electromagnetic wave wavelength. Is the largest. The degree of electric field concentration also depends on the shape of the ignition electrode 10, and the degree of electric field concentration increases particularly when the tip portion is thin and has an acute angle.

  In this test, when the dimensionless length was about 0.17 or more, plasma discharge occurred in a wide range on the upper surface of the constant volume container 23. In this case, the air in the container 23 is broken down by a high electric field, and plasma discharge is induced in a wide range starting from the air. And it has confirmed that the range which the plasma discharge generate | occur | produces changes according to the supply amount of electromagnetic wave energy. Furthermore, if a hydrocarbon premixed gas is supplied into the vessel 23 and conditions for generating the above-described plasma discharge are adjusted, even a very lean premixed gas that cannot be ignited by a conventional ignition system can be easily ignited. -It was confirmed that it burned. In order to efficiently generate plasma discharge, it is effective to set the insertion length of the ignition electrode 10 within a range where the electric field intensity in the vicinity of the ignition electrode 10 is substantially saturated (to the maximum value).

  From the above results, in this embodiment, by setting the projection length x2 of the ignition electrode 10 into the combustion chamber 3 to be 0.17 times or more and 0.33 times or less of the electromagnetic wave wavelength, the electric field in the vicinity thereof is set. The strength can be increased efficiently, and plasma discharge can be efficiently generated in a wide range in the combustion chamber 3. For this reason, the air-fuel mixture in the combustion chamber 3 can be efficiently ignited with less electromagnetic energy without complicating the configuration of the apparatus. As a result, a leaner air-fuel mixture can be ignited efficiently, and low NOx combustion can be realized with high thermal efficiency. Furthermore, by setting the projection length x2 of the ignition electrode 10 into the combustion chamber 3 to be 0.25 times the electromagnetic wave wavelength (or in the vicinity thereof), the electric field strength in the vicinity thereof is maximized, so that it is most efficient. Plasma discharge can be generated. Further, in the present embodiment, by setting the projection length x2 of the ignition electrode 10 into the combustion chamber 3 to be 0.17 times (or in the vicinity of) the electromagnetic wave wavelength, the heat load on the ignition electrode 10 is set. Plasma discharge can be generated efficiently while reducing. In the present embodiment, in order to efficiently generate plasma discharge, the electric field strength in the vicinity of the ignition electrode 10 when the protrusion length x2 of the ignition electrode 10 is set to 0.25 times the electromagnetic wave wavelength is 1 ( As the maximum electric field value), the protrusion length x2 of the ignition electrode 10 is set so that the electric field strength in the vicinity of the ignition electrode 10 is 0.9 times or more (and 1.0 times or less) of the maximum electric field value. You can also.

“Embodiment 2”
4 and 5 are diagrams showing a schematic configuration of an ignition device for an internal combustion engine according to Embodiment 2 of the present invention, together with the internal combustion engine. In the following description of the second embodiment, the same or corresponding components as those in the first embodiment are denoted by the same reference numerals, and redundant descriptions are omitted.

  In the present embodiment, as compared with the first embodiment, a spark plug 31 having a center electrode 51 and a ground electrode 53 as ignition electrodes is attached to the cylinder head 22 so as to face the combustion chamber 3. In the example shown in FIGS. 4 and 5, the spark plug 31 is disposed at the center of the upper surface of the combustion chamber 3. The center electrode 51 is covered with an insulator 55 except for its both ends. A DC ignition circuit 30 having a switching element 34 and an ignition coil 35 is provided between the spark plug 31 and the DC power source 33, and one end portion 31a (center electrode 51) of the ignition plug 31 is connected to a DC cord. It is connected to the ignition coil 35 via 32. The tip 51 a of the center electrode 51 and the tip 53 a of the ground electrode 53 protrude into the combustion chamber 3 at the other end 31 b of the spark plug 31, and the tip 51 a of the center electrode 51 and the tip of the ground electrode 53. A gap 52 is formed between 53a and 53a. By applying a DC voltage between the center electrode 51 of the spark plug 31 and the ground electrode 53 by the DC ignition circuit 30, the gap 52 between the front end portion 51 a of the center electrode 51 and the front end portion 53 a of the ground electrode 53. DC discharge occurs in That is, the spark plug 31 can perform a direct current discharge using electrical energy stored in the ignition coil 35 or a capacitor (not shown). The air-fuel mixture in the combustion chamber 3 can be ignited by this direct current discharge.

  Furthermore, in this embodiment, the air-fuel mixture in the combustion chamber 3 can also be ignited by radiating the electromagnetic wave generated by the electromagnetic wave generating power source 1 from the electromagnetic wave radiator 4 into the combustion chamber 3. In that case, the spark plug 31 is used as the ignition electrode 10 for locally increasing the electric field strength of the electromagnetic wave in the combustion chamber 3. As shown in FIG. 5, with respect to the ground electrode 53 provided at the other end 31b of the spark plug 31, the electromagnetic wave used for the lower surface of the cylinder head 22 in order to efficiently increase the electric field strength in the vicinity thereof. It is preferable that a length x2 corresponding to 17 to 33% of the wavelength is projected into the combustion chamber 3. That is, it is preferable that the projecting length (insertion length) x2 of the ground electrode 53 into the combustion chamber 3 is set to be not less than 0.17 times and not more than 0.33 times the wavelength of the electromagnetic wave to be used.

  In the present embodiment, the spark plug 31 has a gap between the tip 51 a of the center electrode 51 and the tip 53 a of the ground electrode 53 when a DC voltage is applied between the center electrode 51 and the ground electrode 53. The air-fuel mixture in the combustion chamber 3 can be ignited by the DC discharge generated at 52. On the other hand, when the electromagnetic wave generated by the electromagnetic wave generating power source 1 is radiated from the electromagnetic wave emitter 4 into the combustion chamber 3, the ignition plug 31 is located near the front end portion 51 a of the center electrode 51 and the front end portion of the ground electrode 53. The air-fuel mixture in the combustion chamber 3 can be ignited by plasma discharge generated by locally increasing the electric field strength of the electromagnetic wave in the combustion chamber 3 in the vicinity of 53a (or one of them). In this way, not only ignition by plasma discharge using electromagnetic waves but also ignition by direct current discharge of the spark plug 31 can reduce the electric energy consumed when the air-fuel mixture is ignited. As a typical example, when ignition is performed using electromagnetic waves, energy of electromagnetic waves of about 1 J is required for ignition of the air-fuel mixture, whereas when ignition is performed by DC discharge, about 50 mJ is required. It is possible to ignite the air-fuel mixture with electric energy. Furthermore, since the plasma discharge can be generated by locally increasing the electric field strength of the electromagnetic wave in the combustion chamber 3 by using the spark plug 31, the configuration of the apparatus is not complicated. Therefore, according to this embodiment, the air-fuel mixture in the combustion chamber 3 can be efficiently ignited with less energy consumption without causing complication of the configuration.

  Further, in the present embodiment, the length x2 of the ground electrode 53 of the spark plug 31 protruding into the combustion chamber 3 is set to be 0.17 times or more and 0.33 times or less of the electromagnetic wave wavelength, so that the electric field in the vicinity thereof The strength can be increased efficiently, and plasma discharge can be efficiently generated in a wide range in the combustion chamber 3. Furthermore, by setting the projection length x2 of the ground electrode 53 into the combustion chamber 3 to be 0.25 times the electromagnetic wave wavelength (or in the vicinity thereof), the electric field strength in the vicinity thereof becomes the highest, so that the plasma is most efficiently generated. A discharge can be generated. Further, by setting the projection length x2 of the ground electrode 53 into the combustion chamber 3 to be 0.17 times the electromagnetic wave wavelength (or in the vicinity thereof), the plasma discharge is efficiently performed while reducing the thermal load on the spark plug 31. Can be generated well.

  In this embodiment, when the air-fuel mixture in the combustion chamber 3 is ignited, a DC voltage is applied between the center electrode 51 and the ground electrode 53 or an electromagnetic wave is generated by the electromagnetic wave generating power source 1 to generate an electromagnetic wave radiator. Whether to radiate from 4 toward the combustion chamber 3 can be selected by an electronic control unit. Hereinafter, a preferred specific example of the method of igniting the air-fuel mixture in the combustion chamber 3 by the electronic control device will be described.

  Differences in combustion characteristics between when a DC voltage is applied between the center electrode 51 and the ground electrode 53 of the spark plug 31 and when electromagnetic waves are radiated from the electromagnetic wave radiator 4 using the container 23 of the first embodiment. The examination results are shown in FIGS. The thin line in FIG. 6 shows the pressure history in the container 23 when a DC voltage is applied between the center electrode 51 and the ground electrode 53 (when ignition is performed by DC discharge). When igniting by direct current discharge, the mixture of equivalence ratio φ1.0 (theoretical mixture ratio) and φ0.8 burned normally, but the mixture of φ0.6 did not ignite and no increase in pressure was observed. It was.

  On the other hand, the thick line in FIG. 6 shows the pressure history in the container 23 when electromagnetic waves are emitted from the electromagnetic wave radiator 4 (when ignition is performed by plasma discharge). When ignition was performed by plasma discharge, as shown by the thick line in FIG. 6, not only the mixture of φ0.6, but also the pressure increase due to combustion could be confirmed even in the mixture of φ0.4. This result shows that ignition by plasma discharge using electromagnetic waves has a very high effect in improving the lean combustion limit as compared with ignition by DC discharge.

  However, in the range of the equivalence ratio φ that can be combusted by ignition by DC discharge, the effect of ignition using electromagnetic waves is limited. FIG. 7 shows the pressure history in the container 23 in the case where ignition is performed by direct current discharge (direct current discharge ignition system) and in the case of ignition by plasma discharge (electromagnetic wave ignition system) in the φ0.8 air-fuel mixture. As shown in FIG. 7, in the air-fuel mixture of φ0.8, even if ignition is performed by plasma discharge using electromagnetic waves, the combustion promoting effect is limited to about 10% compared to ignition by DC discharge. I understand. Therefore, it can be seen that in the combustion near the theoretical mixture ratio, even if ignition is performed using electromagnetic waves, the combustion promoting effect of the air-fuel mixture is limited.

  From the above results, when the air-fuel ratio of the air-fuel mixture in the combustion chamber 3 is within the stoichiometric air-fuel ratio and the range in the vicinity thereof, the electronic control unit is located between the center electrode 51 of the spark plug 31 and the ground electrode 53. It is preferable to select a method of applying a DC voltage, that is, a method of igniting the air-fuel mixture in the combustion chamber 3 by DC discharge. Thereby, the electric energy consumed when igniting the air-fuel mixture in the combustion chamber 3 can be reduced. On the other hand, when the air-fuel ratio of the air-fuel mixture in the combustion chamber 3 is equal to or greater than a predetermined ratio larger than the stoichiometric air-fuel ratio, that is, when lean combustion is performed, the electronic control unit generates electromagnetic waves by the electromagnetic wave generating power source 1 to It is preferable to select one that radiates from the radiator 4 into the combustion chamber 3, that is, one that ignites the air-fuel mixture in the combustion chamber 3 by plasma discharge. As a result, even a lean air-fuel mixture that is difficult to ignite with direct current discharge can be burned, so that low fuel consumption and low emission can be realized. Note that the air-fuel ratio of the air-fuel mixture in the combustion chamber 3 can be calculated based on, for example, the intake air amount and the fuel injection amount.

  Next, another configuration example of this embodiment will be described.

  FIG. 8 illustrates the intake passage 6, the exhaust passage 7, the intake valve 8, and the exhaust valve 9, and shows an example in which the electromagnetic wave radiator 4 is disposed facing the intake passage 6. In that case, the intake valve 8 or a part thereof is made of a non-conductive material (for example, a dielectric such as ceramic having a low dielectric constant). Thereby, even when the intake valve 8 is closed, the electromagnetic wave radiated from the electromagnetic wave radiator 4 to the intake passage 6 is transmitted through the intake valve 8 and into the combustion chamber 3. As described above, the electromagnetic wave can be radiated into the combustion chamber 3 by making the electromagnetic wave radiator 4 face the intake passage 6.

  FIG. 9 shows an example in which the electromagnetic wave radiator 4 is disposed below the piston 11. In that case, the top 11a of the piston 11 or a part thereof is made of a non-conductive material (for example, a dielectric such as ceramic having a low dielectric constant). As a result, the electromagnetic wave radiated from the electromagnetic wave radiator 4 is transmitted through the piston 11 (top 11a) and propagates into the combustion chamber 3. In this manner, the electromagnetic wave can be radiated into the combustion chamber 3 by arranging the electromagnetic wave radiator 4 below the piston 11.

“Embodiment 3”
10 and 11 are diagrams showing a schematic configuration of an ignition device for an internal combustion engine according to Embodiment 3 of the present invention, together with the internal combustion engine. In the following description of the third embodiment, the same or corresponding components as those of the first and second embodiments are denoted by the same reference numerals, and redundant description is omitted.

  In the present embodiment, compared to the second embodiment, the ignition plug 31 is not only used as an ignition electrode 10 for generating plasma discharge by locally increasing the electric field strength of the electromagnetic wave in the combustion chamber 3. The electromagnetic wave radiator 4 that radiates electromagnetic waves toward the combustion chamber 3 is also used. Further, as in the second embodiment, the air-fuel mixture in the combustion chamber 3 is also generated by direct current discharge generated in the gap 52 between the tip 51a of the center electrode 51 and the tip 53a of the ground electrode 53 of the spark plug 31. Can be ignited.

  In order to perform either electromagnetic wave discharge or direct current discharge through the spark plug 31, between the spark plug 31 and the electromagnetic wave generating power source 1, and between the spark plug 31 and the DC ignition circuit 30, there are electromagnetic waves and direct current. A coupler 14 capable of efficiently energizing both is provided. The coupler 14 here has a waveguide 57 as electromagnetic wave transmission means. As shown in FIG. 11, the electromagnetic wave transmission path 2 having a coaxial structure has a center electrode 2 a protruding into the waveguide 57 with respect to one end 57 a of the waveguide 57. Here, the protruding length (insertion length) x3 of the center electrode 2a into the waveguide 57 is set to 1/4 of the wavelength of the electromagnetic wave used or n times (n is an integer of 2 or more). . The electromagnetic wave transmission path 2 is connected to one end portion 57 a of the waveguide 57 so that the center electrode 2 a coincides with the central axis of the waveguide 57.

  Further, one end 31 a of the spark plug 31 is inserted into the waveguide 57 from the other end 57 b of the waveguide 57. A portion of the spark plug 31 inserted into the waveguide 57 includes a center electrode 51 and an insulator 55 covering the center electrode 51. The insertion length x4 of the spark plug 31 (center electrode 51) into the waveguide 57 is set to 1/4 of the wavelength of the electromagnetic wave to be used or n times the wavelength (n is an integer of 2 or more). The spark plug 31 is inserted into the waveguide 57 so that the center electrode 51 coincides with the central axis of the waveguide 57. Also in this embodiment, the ground electrode 53 provided at the other end 31b of the spark plug 31 burns a length x2 corresponding to 17 to 33% of the wavelength of the electromagnetic wave to be used with respect to the lower surface of the cylinder head 22. It is preferable to protrude into the chamber 3. That is, it is preferable that the projecting length (insertion length) x2 of the ground electrode 53 into the combustion chamber 3 is set to be not less than 0.17 times and not more than 0.33 times the wavelength of the electromagnetic wave to be used. Also in this embodiment, the protruding length (insertion length) of the center electrode 51 into the combustion chamber 3 can be set to 0.17 times or more and 0.33 times or less of the wavelength of the electromagnetic wave to be used.

  With the above configuration, the electromagnetic wave generated by the electromagnetic wave generation power source 1 is efficiently radiated into the waveguide 57 through the electromagnetic wave transmission path 2. The electromagnetic wave propagating through the waveguide 57 is efficiently supplied to the one end 31 a of the spark plug 31. The ignition plug 31 can efficiently radiate the electromagnetic wave supplied to the one end portion 31a from the other end portion 31b (the tip portion 51a of the center electrode 51) toward the combustion chamber 3. That is, the ignition plug 31 can function as the electromagnetic wave radiator 4. And by the plasma discharge which generate | occur | produces when the electric field strength of the electromagnetic wave in the combustion chamber 3 increases locally in the vicinity of the front-end | tip part 51a of the center electrode 51, and the front-end | tip part 53a of the ground electrode 53 (or one of them). The air-fuel mixture in the combustion chamber 3 can be ignited. That is, the spark plug 31 can also function as the ignition electrode 10.

  Further, as shown in FIG. 11, the DC cord 32 is connected to one end portion 31 a (center electrode 51) of the spark plug 31 through a vertical slit 58 provided on the side surface 57 c of the waveguide 57. Therefore, when the electromagnetic wave generating power source 1 does not generate an electromagnetic wave, a DC voltage can be applied between the center electrode 51 of the spark plug 31 and the ground electrode 53 by the DC ignition circuit 30. The air-fuel mixture in the combustion chamber 3 can be ignited by direct current discharge generated in the gap 52 between the portion 51a and the tip 53a of the ground electrode 53.

  Even in the present embodiment described above, the ignition plug 31 is used to selectively perform either plasma discharge ignition or DC discharge ignition, thereby reducing the energy consumption without complicating the configuration. The air-fuel mixture in the combustion chamber 3 can be ignited efficiently. Furthermore, in the present embodiment, the electromagnetic plug can be radiated toward the combustion chamber 3 by using the spark plug 31, so that the configuration of the apparatus can be simplified.

  Furthermore, in the present embodiment, the length x2 of the ground electrode 53 of the spark plug 31 protruding into the combustion chamber 3 is set to be not less than 0.17 times and not more than 0.33 times the electromagnetic wave wavelength, so that an efficient electric field can be obtained. Can concentrate. Furthermore, the electric field concentration can be most efficiently performed by setting the projection length x2 of the ground electrode 53 into the combustion chamber 3 to be 0.25 times the electromagnetic wave wavelength (or in the vicinity thereof). Further, by setting the projection length x2 of the ground electrode 53 into the combustion chamber 3 to be 0.17 times (or in the vicinity of) the electromagnetic wave wavelength, the electric field concentration is efficiently performed while reducing the heat load on the spark plug 31. Can be done well.

  In the present embodiment, the length of the center electrode 51 of the spark plug 31 protruding into the combustion chamber 3 is set to be 0.17 times or more and 0.33 times or less of the electromagnetic wave wavelength, thereby entering the combustion chamber 3. Directed and efficient electromagnetic radiation. Furthermore, electromagnetic radiation can be most efficiently performed by setting the projecting length of the center electrode 51 into the combustion chamber 3 to be 0.25 times (or in the vicinity of) the electromagnetic wave wavelength. Further, by setting the projecting length of the center electrode 51 into the combustion chamber 3 to be 0.17 times the electromagnetic wave wavelength (or in the vicinity thereof), the electromagnetic radiation can be efficiently emitted while reducing the heat load on the spark plug 31. It can be carried out.

  In the present embodiment, as shown in FIG. 12, the electromagnetic wave transmission path 2 having a coaxial structure is connected to the side surface 57c of the waveguide 57, and the center electrode 2a of the electromagnetic wave transmission path 2 is guided from the side surface 57c of the waveguide 57. It can also be inserted into the wave tube 57. The protrusion length (insertion length) x3 of the center electrode 2a into the waveguide 57 here is also set to 1/4 of the wavelength of the electromagnetic wave used or n times (n is an integer of 2 or more). Is preferred. The distance x5 of the center electrode 2a with respect to the one end portion 57a of the waveguide 57 is also preferably set to 1/4 of the wavelength of the electromagnetic wave used or n times (n is an integer of 2 or more). Also, as shown in FIG. 12, by connecting the adjustment electrode 59 to the center electrode 51 of the one end 31a of the spark plug 31, the insertion length x4 of the one end 31a of the spark plug 31 into the waveguide 57 is It can be easily adjusted to 1/4 of the wavelength of the electromagnetic wave used or n times the wavelength (n is an integer of 2 or more).

“Embodiment 4”
13 and 14 are diagrams showing a schematic configuration of an ignition device for an internal combustion engine according to Embodiment 4 of the present invention, together with the internal combustion engine. In the following description of the fourth embodiment, the same or corresponding components as those in the first to third embodiments are denoted by the same reference numerals, and redundant description is omitted.

  In the present embodiment, an annular non-conductor 40 that is coaxial with the spark plug 31 is provided on the lower surface of the cylinder head 22. As the non-conductor 40 here, for example, ceramic can be used. The annular non-conductor 40 surrounds the periphery of the other end portion 31 b of the spark plug 31, and the center electrode 51 and the ground electrode 53 pass through a hole formed in the central portion of the non-conductor 40. Projecting into the combustion chamber 3 with respect to the lower surface of the cylinder head 22. The center electrode 51 is preferably protruded into the combustion chamber 3 by a length x6 corresponding to 17 to 33% of the wavelength of the electromagnetic wave used with respect to the lower surface (conductor) of the cylinder head 22. That is, it is preferable that the projection length (insertion length) x6 of the center electrode 51 into the combustion chamber 3 is set to 0.17 times or more and 0.33 times or less of the wavelength of the electromagnetic wave to be used. The projecting length (insertion length) x2 of the ground electrode 53 into the combustion chamber 3 is also preferably set to be not less than 0.17 times and not more than 0.33 times the wavelength of the electromagnetic wave to be used. Thus, efficient electromagnetic radiation toward the combustion chamber 3 and efficient electric field concentration can be performed using the spark plug 31. The gap 52 between the tip 51a of the center electrode 51 and the tip 53a of the ground electrode 53 is kept at about 0.3 to 1.0 mm, and the center electrode 51 is used when electromagnetic waves are not used. By applying a DC voltage between the ground electrode 53 and the ground electrode 53, the air-fuel mixture in the combustion chamber 3 can be ignited by a DC discharge generated in the gap 52.

  In an internal combustion engine that performs ignition by direct current discharge of the spark plug 31, the length of the spark plug 31 protruding into the combustion chamber 3 is set to about 5 mm in consideration of the heat load. In that case, the optimal frequency of the electromagnetic wave is a high frequency of about a dozen GHz. In this embodiment, by disposing the non-conductor 40 around the other end portion 31b of the spark plug 31, the frequency of the electromagnetic wave to be used can be lowered while reducing the heat load on the spark plug 31. The degree of freedom in the frequency of the electromagnetic wave used can be increased.

“Embodiment 5”
FIG. 15 is a view showing a schematic configuration of an internal combustion engine ignition device according to Embodiment 5 of the present invention together with the internal combustion engine. In the following description of the fifth embodiment, the same or corresponding components as those of the first to fourth embodiments are denoted by the same reference numerals, and redundant description is omitted.

  The internal combustion engine of this embodiment is a direct injection internal combustion engine that directly injects fuel into a cylinder, and a fuel injection valve 61 faces the combustion chamber 3 and is attached to the cylinder head 22. The fuel stored in the fuel tank 64 is pumped up by the fuel pump 63 and supplied to the fuel injection valve 61 through the fuel pipe 62. The fuel injection valve 61 injects the supplied fuel into the combustion chamber 3.

  In the present embodiment, similarly to the third embodiment, the spark plug 31 is used as the electromagnetic wave radiator 4 that radiates electromagnetic waves toward the combustion chamber 3. A specific configuration example for causing the ignition plug 31 to function as the electromagnetic wave radiator 4 is the same as that of the third embodiment. Furthermore, in this embodiment, the fuel injection valve 61 is used as the ignition electrode 10 for generating plasma discharge by locally increasing the electric field strength of the electromagnetic wave in the combustion chamber 3. In order to locally increase the electric field strength of the electromagnetic wave in the vicinity of the tip of the fuel injection valve 61, the tip of the fuel injection valve 61 is made of a conductor and protrudes into the combustion chamber 3. Also for the fuel injection valve 61 here, it is preferable to project into the combustion chamber 3 a length corresponding to 17 to 33% of the wavelength of the electromagnetic wave used with respect to the lower surface of the cylinder head 22. That is, it is preferable that the projecting length (insertion length) of the fuel injection valve 61 into the combustion chamber 3 is set to be not less than 0.17 times and not more than 0.33 times the wavelength of the electromagnetic wave to be used. Thereby, electric field concentration can be efficiently performed in the vicinity of the fuel injection valve 61. For example, the electric field concentration can be most efficiently performed by setting the length of the fuel injection valve 61 protruding into the combustion chamber 3 to be 0.25 times the electromagnetic wave wavelength (or in the vicinity thereof). Further, by setting the length of the fuel injection valve 61 protruding into the combustion chamber 3 to be 0.17 times the electromagnetic wave wavelength (or in the vicinity thereof), the electric field concentration is reduced while reducing the heat load on the fuel injection valve 61. It can be done efficiently. FIG. 15 shows an example in which the tip of the fuel injection valve 61 protruding into the combustion chamber 3 has an acute cone shape.

  Also in the present embodiment described above, the electrical energy consumed when the air-fuel mixture is ignited can be reduced by selectively performing either ignition by plasma discharge or ignition by DC discharge. Furthermore, in this embodiment, since the electromagnetic wave can be radiated into the combustion chamber using the spark plug 31, the configuration of the apparatus is not complicated. Therefore, according to this embodiment, the air-fuel mixture in the combustion chamber 3 can be efficiently ignited with less energy consumption without causing complication of the configuration.

“Embodiment 6”
FIG. 16 is a diagram showing a schematic configuration of an ignition device for an internal combustion engine according to Embodiment 6 of the present invention, together with the internal combustion engine. In the following description of the sixth embodiment, the same or corresponding components as those of the first to fifth embodiments are denoted by the same reference numerals, and redundant description is omitted.

  In the present embodiment, a plurality of protrusions 10 a protruding into the combustion chamber 3 are provided on the top surfaces of the intake valve 8, the exhaust valve 9, and the piston 11. Each protrusion 10a is made of a conductor in order to locally increase the electric field strength of the electromagnetic wave in the vicinity thereof. That is, in this embodiment, each protrusion 10a is used as an ignition electrode 10 for generating plasma discharge by locally increasing the electric field strength of the electromagnetic wave in the combustion chamber 3. The protrusion length of each protrusion 10a into the combustion chamber 3 here is also preferably set to be not less than 0.17 times and not more than 0.33 times the wavelength of the electromagnetic wave to be used. Thereby, the electric field strength can be efficiently increased in the vicinity of each protrusion 10a, and plasma discharge can be efficiently generated in a wide range in the combustion chamber 3. Note that the protrusion 10 a may be provided on any one or more of the top surfaces of the intake valve 8, the exhaust valve 9, and the piston 11.

  As mentioned above, although the form for implementing this invention was demonstrated, this invention is not limited to such embodiment at all, and it can implement with a various form in the range which does not deviate from the summary of this invention. Of course.

It is a figure which shows schematic structure of the ignition device of the internal combustion engine which concerns on Embodiment 1 of this invention with an internal combustion engine. It is a figure which shows the electric field distribution in a container at the time of radiating | emitting electromagnetic waves in a container from an electromagnetic wave radiator. It is a figure which shows the relationship between the insertion length of the electrode for ignition, and the electric field strength directly under the electrode for ignition. It is a figure which shows schematic structure of the ignition device of the internal combustion engine which concerns on Embodiment 2 of this invention with an internal combustion engine. It is a figure which shows schematic structure of the ignition device of the internal combustion engine which concerns on Embodiment 2 of this invention. It is a figure which shows the result of having investigated the difference in the combustion characteristic when a DC voltage is applied between the center electrode and ground electrode of a spark plug, and the case where electromagnetic waves are radiated | emitted from an electromagnetic wave radiator. It is a figure which shows the result of having investigated the difference in the combustion characteristic when a DC voltage is applied between the center electrode and ground electrode of a spark plug, and the case where electromagnetic waves are radiated | emitted from an electromagnetic wave radiator. It is a figure which shows the other schematic structure of the ignition device of the internal combustion engine which concerns on Embodiment 2 of this invention with an internal combustion engine. It is a figure which shows the other schematic structure of the ignition device of the internal combustion engine which concerns on Embodiment 2 of this invention with an internal combustion engine. It is a figure which shows schematic structure of the ignition device of the internal combustion engine which concerns on Embodiment 3 of this invention with an internal combustion engine. It is a figure which shows schematic structure of the ignition device of the internal combustion engine which concerns on Embodiment 3 of this invention. It is a figure which shows the other schematic structure of the ignition device of the internal combustion engine which concerns on Embodiment 3 of this invention. It is a figure which shows schematic structure of the ignition device of the internal combustion engine which concerns on Embodiment 4 of this invention with an internal combustion engine. It is a figure which shows schematic structure of the ignition device of the internal combustion engine which concerns on Embodiment 4 of this invention with an internal combustion engine. It is a figure which shows schematic structure of the ignition device of the internal combustion engine which concerns on Embodiment 5 of this invention with an internal combustion engine. It is a figure which shows schematic structure of the ignition device of the internal combustion engine which concerns on Embodiment 6 of this invention with an internal combustion engine. It is a figure which shows schematic structure of the ignition device of the conventional internal combustion engine.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Electromagnetic wave generation power source, 2 Electromagnetic wave transmission path, 3 Combustion chamber, 4 Electromagnetic wave radiator, 10 Ignition electrode, 11 Piston, 14 Coupler, 20 Cylinder block, 22 Cylinder head, 30 DC ignition circuit, 31 Spark plug, 32 DC cord, 33 DC power source, 51 center electrode, 52 gap, 53 ground electrode, 55 insulator, 57 waveguide, 61 fuel injection valve.

Claims (13)

An ignition device for an internal combustion engine that ignites an air-fuel mixture in a combustion chamber,
An ignition plug capable of igniting an air-fuel mixture in the combustion chamber by a DC discharge generated by applying a DC voltage between the electrodes for ignition protruding into the combustion chamber;
An electromagnetic wave source for generating electromagnetic waves;
An electromagnetic wave emitter for radiating electromagnetic waves generated from an electromagnetic wave source toward the combustion chamber;
With
The spark plug
When a DC voltage is applied between the ignition electrodes, the mixture in the combustion chamber is ignited by a DC discharge generated between the ignition electrodes,
When electromagnetic waves generated from an electromagnetic wave source are radiated from an electromagnetic wave emitter into the combustion chamber, they are burned by plasma discharge generated by locally increasing the electric field strength of the electromagnetic waves in the combustion chamber in the vicinity of the ignition electrode An ignition device for an internal combustion engine that ignites an air-fuel mixture in a room. An ignition device for an internal combustion engine according to claim 1,
An ignition device for an internal combustion engine, wherein a length of projection of the ignition electrode into the combustion chamber is set to be 0.17 times or more and 0.33 times or less of the wavelength of the electromagnetic wave. An ignition device for an internal combustion engine according to claim 1 or 2,
An electromagnetic wave transmission means for supplying the electromagnetic wave generated by the electromagnetic wave generation source to the ignition plug,
An ignition device for an internal combustion engine in which an ignition plug radiates an electromagnetic wave generated by an electromagnetic wave generation source as an electromagnetic wave emitter from an ignition electrode toward a combustion chamber. An ignition device for an internal combustion engine according to claim 3,
The electromagnetic wave transmission means includes a waveguide,
One end of the spark plug is inserted into the waveguide,
An ignition device for an internal combustion engine, wherein an ignition electrode projects into the combustion chamber at the other end of the spark plug. An ignition device for an internal combustion engine according to any one of claims 1 to 4,
When igniting the air-fuel mixture in the combustion chamber, whether to apply a DC voltage between the ignition electrodes or to generate an electromagnetic wave from the electromagnetic wave source and radiate it from the electromagnetic wave emitter into the combustion chamber. An ignition device for an internal combustion engine that is selected based on an air-fuel ratio. An ignition device for an internal combustion engine according to claim 5,
An internal combustion engine ignition device that selects a method of applying a DC voltage between ignition electrodes when the air-fuel ratio of the air-fuel mixture is within the stoichiometric air-fuel ratio and the vicinity thereof. An ignition device for an internal combustion engine according to claim 5 or 6,
When the air-fuel ratio of the air-fuel mixture is equal to or greater than a predetermined ratio greater than the stoichiometric air-fuel ratio, the internal combustion engine ignition is selected to generate an electromagnetic wave from an electromagnetic wave generation source and radiate it from the electromagnetic wave radiator into the combustion chamber apparatus. An ignition device for an internal combustion engine that ignites an air-fuel mixture in a combustion chamber,
A spark plug capable of igniting an air-fuel mixture in the combustion chamber by a DC discharge generated by applying a DC voltage between the discharge electrodes protruding into the combustion chamber;
An electromagnetic wave source for generating electromagnetic waves;
An electromagnetic wave transmission means for propagating the electromagnetic wave generated by the electromagnetic wave generation source to the spark plug;
An electrode arranged facing the combustion chamber, and when an electromagnetic wave propagates in the combustion chamber, an ignition electrode for locally increasing the electric field strength of the electromagnetic wave in the combustion chamber in the vicinity of the electrode;
With
When a DC voltage is applied between the discharge electrodes, the mixture in the combustion chamber is ignited by a DC discharge generated between the discharge electrodes,
When an electromagnetic wave is generated by an electromagnetic wave source, the ignition plug radiates the electromagnetic wave from the discharge electrode toward the combustion chamber, and the ignition electrode locally increases the electric field strength of the electromagnetic wave in the combustion chamber. An ignition device for an internal combustion engine that ignites an air-fuel mixture in a combustion chamber by plasma discharge generated by the above. An ignition device for an internal combustion engine according to claim 8,
The electromagnetic wave transmission means includes a waveguide,
One end of the spark plug is inserted into the waveguide,
An ignition device for an internal combustion engine, wherein a discharge electrode projects into the combustion chamber at the other end of the spark plug. An internal combustion engine ignition device according to claim 8 or 9,
An ignition device for an internal combustion engine, wherein a length of protrusion of the discharge electrode into the combustion chamber is set to be 0.17 times or more and 0.33 times or less of the wavelength of the electromagnetic wave. An ignition device for an internal combustion engine according to any one of claims 8 to 10,
An ignition device for an internal combustion engine, wherein a length of projection of the ignition electrode into the combustion chamber is set to be 0.17 times or more and 0.33 times or less of the wavelength of the electromagnetic wave. An ignition device for an internal combustion engine that ignites an air-fuel mixture in a combustion chamber,
An electromagnetic wave source for generating electromagnetic waves;
An electromagnetic wave emitter for radiating electromagnetic waves generated from an electromagnetic wave source toward the combustion chamber;
An electrode that protrudes into the combustion chamber, the ignition electrode for locally increasing the electric field strength of the electromagnetic wave in the combustion chamber in the vicinity of the electrode;
With
The protruding length of the ignition electrode into the combustion chamber is set to be 0.17 times or more and 0.33 times or less of the wavelength of the electromagnetic wave,
An ignition device for an internal combustion engine that ignites an air-fuel mixture in a combustion chamber by plasma discharge generated by an ignition electrode that locally increases the electric field strength of electromagnetic waves in the combustion chamber in the vicinity thereof. An internal combustion engine that ignites an air-fuel mixture in a combustion chamber by an ignition device,
An internal combustion engine, wherein the ignition device is the internal combustion engine ignition device according to any one of claims 1 to 12.

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