JP2010118185A - Plasma igniting device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To restrain damage of an insulator due to high temperature by realizing superb heat dissipation from its cylindrical tip end forming a chamber for generating plasma, in a plasma ignition device of an internal combustion engine. <P>SOLUTION: In the plasma ignition device provided with a chamber 1 formed by a cylindrical tip end part 2a' of the insulator 2', a center electrode 4 arranged at a base end side of the chamber, a grounding electrode 3 arranged at a tip end side of the chamber, a housing 7' covering an outside of the insulator and fixing the grounding electrode, and a spray nozzle 8 communicated with an inside of the cylinder, a gap communicated with the chamber between the insulator and the housing is sealed with a metal gasket 9' in contact with an end face 2b' of the cylindrical tip end part. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a plasma ignition device for an internal combustion engine.

  In an internal combustion engine, a homogeneous mixture in the entire cylinder or a mixture existing in a part of the cylinder must be reliably ignited by an ignition device. However, a general ignition device that generates a spark in the ignition gap ignites one point of the air-fuel mixture and does not have a very high ignitability.

  As an ignition device having excellent ignitability, a plasma ignition device that injects a plasma jet has been proposed (see, for example, Patent Document 1). The plasma ignition device includes a chamber formed by a cylindrical tip portion of an insulator and extending in the axial direction, a center electrode disposed on the base end side of the chamber, and a ground electrode disposed on the tip end side of the chamber. And high temperature and high pressure plasma is generated in the chamber by a discharge generated by applying a voltage between the center electrode and the ground electrode. The plasma generated in the chamber is ejected as a plasma jet from the nozzle hole communicating with the chamber, and a predetermined area of the air-fuel mixture corresponding to the cross-sectional area of the plasma jet can be ignited simultaneously. Thus, the plasma ignition device has high ignitability.

JP 2008-177142 A JP 06-96836 A JP2007-141786 JP-A-63-167077 JP 2006-294257 A JP2008-45449 JP 2006-1227887 A

  In such a plasma ignition device, since the insulator forming the chamber generally has a low heat transfer coefficient, the high temperature is easily maintained when the insulator is heated to a high temperature by discharge in the chamber when generating plasma. Accordingly, it is necessary to quickly dissipate heat so that the high temperature is maintained and is not damaged.

  In the plasma ignition device, a metal housing is provided outside the insulator, and the heat of the insulator is radiated to the housing. Since the gap between the insulator and the housing communicates with the chamber, a metal gasket is disposed in the gap to ensure the airtightness of the chamber. Thus, strictly speaking, the insulator and the housing are in contact only via the metal gasket, and the heat of the insulator is mainly radiated to the housing via the metal gasket.

  However, since the metal gasket is generally disposed away from the cylindrical tip of the insulator forming the chamber, heat is quickly radiated from the cylindrical tip of the insulator that is at the highest temperature to the housing. In particular, the cylindrical tip of the insulator may be damaged by high temperatures.

  Accordingly, an object of the present invention is to enable good heat dissipation from the cylindrical tip of an insulator forming a chamber for generating plasma in a plasma ignition device for an internal combustion engine, thereby suppressing damage due to high temperature of the insulator. That is.

  The plasma ignition device for an internal combustion engine according to claim 1 according to the present invention includes a chamber formed by a cylindrical distal end portion of an insulator and extending in an axial direction, and a center electrode disposed on a proximal end side of the chamber. A plasma ignition apparatus comprising: a ground electrode disposed on a front end side of the chamber; a housing that covers the outside of the insulator and fixes the ground electrode; and a nozzle hole that communicates the chamber and the inside of the cylinder. A gap communicating with the chamber between the insulator and the housing is sealed by a metal gasket that abuts an end surface of the cylindrical tip.

  The plasma ignition device for an internal combustion engine according to claim 2 according to the present invention is the plasma ignition device for internal combustion engine according to claim 1, wherein at least a portion of the gap in the atmosphere from the metal gasket is a metal powder or It is filled with a liquid.

  A plasma ignition device for an internal combustion engine according to a third aspect of the present invention is the plasma ignition device for an internal combustion engine according to the second aspect, wherein a filling passage communicating with the gap is formed in the housing. The metal powder or the liquid is filled from a passage.

  According to the plasma ignition device for an internal combustion engine of the first aspect of the present invention, a chamber formed by the cylindrical tip portion of the insulator and extending in the axial direction, and a center electrode disposed on the base end side of the chamber A plasma ignition device comprising: a ground electrode disposed on a front end side of the chamber; a housing that covers the outside of the insulator and fixes the ground electrode; and a nozzle hole that communicates the chamber and the inside of the cylinder. A gap communicating with the chamber between the housing and the housing is sealed by a metal gasket that abuts the end surface of the cylindrical tip. As a result, the cylindrical tip of the insulator forming the chamber becomes hot due to the discharge in the chamber for generating plasma, but this heat is quickly dissipated to the housing via the metal gasket that comes into contact immediately. And the damage due to the high temperature of the insulator can be suppressed.

  According to the plasma ignition device for an internal combustion engine according to claim 2 of the present invention, in the plasma ignition device for internal combustion engine according to claim 1, the atmosphere side of the gap between the insulator and the housing is closer to the atmosphere. At least partially filled with metal powder or liquid. The metal powder or liquid filled in this way is in close contact with the insulator and the housing except for the metal gasket that abuts the end surface of the cylindrical tip of the insulator, and provides good heat transfer from the insulator to the housing. The heat of the insulator can be dissipated to the housing also by the filled metal powder or liquid, and damage due to the high temperature of the insulator can be further reliably suppressed.

  According to the plasma ignition device for an internal combustion engine according to claim 3 of the present invention, in the plasma ignition device for internal combustion engine according to claim 2, the housing is formed with a filling passage communicating with the gap, and the filling passage The metal powder or liquid is filled. Thereby, after the insulator is assembled to the housing, the gap between the insulator and the housing can be easily filled with the metal powder or liquid via the filling passage.

  FIG. 7 is a sectional view showing a general plasma ignition device. In the figure, reference numeral 1 denotes a chamber that is formed by a cylindrical distal end portion 2a of an insulator 2 so as to extend in the axial direction of the plasma ignition device and generates plasma. Is disposed, and a ground electrode 3 is disposed on the front end side of the chamber 1. Reference numeral 7 denotes a metal housing that covers the outside of the insulator 2 and fixes the ground electrode 3. The housing 7 and the ground electrode 3 are hermetically joined to each other by welding or the like, and are mechanically and electrically integrated. In the conventional example, the ground electrode 8 faces the chamber 1 and the cylinder, and the nozzle hole 8 that communicates the chamber 1 and the cylinder is formed in the ground electrode 3.

  The ground electrode 3 and the center electrode 4 can be made of a metal having heat resistance and high conductivity, for example, an iron-based metal such as stainless steel, a nickel-based metal, an iridium-based metal, or an iridium alloy. The material of the insulator 2 for insulating the ground electrode 3 from the center electrode 4 is preferably ceramics (for example, alumina ceramics). 5 is a conductor (for example, nickel) for applying a voltage to the center electrode 4, and 6 is a conductive adhesive for electrically connecting the conductor 5 and the center electrode 4.

  FIG. 8 is an enlarged view of the vicinity of the chamber 1 of the plasma ignition device of FIG. 1, and FIG. 6 is a power supply control circuit of the ignition device of FIG. In FIG. 6, 10 is a transistor controlled by the electronic control unit ECU, 11 is a first battery, and 12 is an ignition coil. Reference numeral 13 denotes a capacitor, and reference numeral 14 denotes a control circuit for the second battery 15.

  In the power supply control circuit configured as described above, the ECU first amplifies the voltage of the first battery 11 by the ignition coil 12 by switching of the transistor 10 and applies it between the center electrode 4 and the ground electrode 3. Thus, due to the high voltage acting between the center electrode 4 and the ground electrode 3, as shown by S1 in FIG. 8, the outer peripheral corner of the ground electrode side end surface 4a of the center electrode 4 and the end surface of the ground electrode 3 on the center electrode side A creeping discharge is generated on the inner surface of the cylindrical tip 2a of the insulator 2 between the inner peripheral corner 3b (formed by the injection hole 8) of 3a and a gas (mixing) in the vicinity of the creeping discharge in the chamber 1 is generated. Gas).

  In this way, a part of the gas in the chamber 1 is turned into plasma to generate ions and electrons, and at the same time, the voltage stored in the capacitor is released, and as shown by S2 in FIG. An air discharge is generated in the chamber 1 between the center portion of the end surface 4 a and the inner peripheral corner portion 3 b of the center electrode side end surface 3 a of the ground electrode 3. The control circuit applies a relatively low voltage of the second battery 15 between the center electrode 4 and the ground electrode 3 so that the air discharge continues, but a relatively large current can flow.

  Thus, when most of the gas in the chamber 1 is turned into plasma by the air discharge, the gas in the chamber 1 becomes high temperature and high pressure and is injected from the nozzle hole 8 as a plasma jet, so that the air-fuel mixture in the cylinder is improved. Ignite.

  When the gas in the chamber 1 is turned into plasma, the creeping discharge can be generated at a lower voltage than the air discharge. However, it is not efficient to make most of the gas in the chamber 1 into plasma only by the creeping discharge because the creeping discharge must be sustained for a long time on the inner surface of the side wall of the insulator 2. It is necessary to generate an air discharge. As described above, the voltage necessary for generating the air discharge can be lowered by converting some of the gas into plasma by creeping discharge. Thus, by generating a creeping discharge first and then generating an air discharge, most of the gas in the chamber 1 can be made into plasma without requiring a very high voltage.

  By the way, the cylindrical tip 2a of the insulator 2 forming the chamber 1 for generating plasma rises in temperature even if the creeping discharge in the chamber 1 is a short time, and is generated in the chamber 1 by the subsequent air discharge. If the heat is received from the plasma, it becomes high temperature, and if it is not released quickly, the high temperature is maintained and may be damaged. Of course, the cylindrical tip 2a of the insulator 2 is not limited to such a combination of a creeping discharge and an air discharge, but also when the plasma is generated in the chamber 1 only by the creeping discharge or only by the air discharge. It becomes high temperature.

  By the way, in the plasma ignition device, a gap exists between the insulator 2 and the housing 7 and the ground electrode 3, and this gap must be sealed with a metal gasket in order to communicate with the chamber 1. In the general plasma ignition device shown in FIG. 7, the metal gasket 9 is disposed on a truncated conical surface (tapered surface) spaced from the cylindrical tip 2 a of the insulator 2.

  Thus, in a general plasma ignition device, the insulator 2 and the housing 7 are strictly in contact with each other only through the metal gasket 9, and the heat of the cylindrical tip 2 a of the insulator 2 is radiated to the housing 7. However, in the insulator 2 having a low heat transfer rate, the heat of the cylindrical tip 2a cannot be quickly dissipated through the metal gasket 9 spaced from the cylindrical tip 2a. The tip 2a is very likely to be damaged by high temperatures.

  FIG. 1 is a cross-sectional view similar to FIG. 7 showing a first embodiment of a plasma ignition device for an internal combustion engine according to the present invention. Only the differences from FIG. 7 will be described below. In the present embodiment, the metal gasket 9 ′ for sealing the gap between the insulator 2 ′ and the housing 7 ′ integrated with the ground electrode 3 is the end face 2 b of the cylindrical tip 2 a ′ of the insulator 2 ′. It is positioned to abut. In the present embodiment, the metal gasket 9 ′ is made of a metal having good thermal conductivity and low hardness such as copper, gold, silver, aluminum, or an alloy containing any of these, and the insulator 2 ′. It arrange | positions between end surface 2b 'of cylindrical front-end | tip part 2a', and the center electrode side end surface 3a of the ground electrode 3 integral with housing 7 '.

  As a result, the cylindrical tip 2a ′ of the insulator 2 ′ forming the chamber 1 becomes hot due to the discharge in the chamber 1 for generating plasma, but this heat is in close contact with the metal gasket 9 ′. It is possible to quickly dissipate heat to the housing 7 'via the, so that damage due to the high temperature of the insulator 2' can be sufficiently suppressed. In creeping discharge and air discharge in the chamber 1, the ground electrode 3 has a higher temperature than the center electrode 4 due to the collection of electrons. Thereby, also in the cylindrical distal end portion 2a ′ of the insulator 2 ′, the distal end side (the ground electrode 3 side) is hotter than the proximal end side (the center electrode 4 side), so that the metal gasket 9 ′ is insulated. The contact with the end surface 2b ′ of the cylindrical tip 2a ′ of the body 2 ′ is very advantageous due to the heat radiation of the insulator 2.

  Further, a filling passage 7a ′ is formed in the housing 7 ′ so as to communicate with the atmosphere side from the metal gasket 9 ′ in the gap between the insulator 2 ′ and the housing 7 ′. A gap between the insulator 2 'and the housing 7' is filled with a metal or sodium powder M similar to the metal gasket 9 '. The metal powder M filled in this manner is in close contact with the insulator 2 ′ and the housing 7 ′ except for the metal gasket 9 ′ that is in contact with the end surface 2b ′ of the cylindrical tip 2a ′ of the insulator 2 ′. Since the heat transfer from the insulator 2 'to the housing 7' is possible and the heat of the insulator 2 'can be dissipated to the housing 7' by the filled metal powder M, the insulator 2 ' Damage to the cylindrical tip 2a ′ due to the high temperature can be further reliably suppressed.

  By forming the filling passage 7a ′ in the housing 7 ′ in this way, the metal powder M is filled in the gap between the insulator 2 ′ and the housing 7 ′ after the insulator 2 ′ is assembled to the housing 7 ′. The metal powder M can be easily filled. The metal powder M may be filled at least partially on the atmosphere side of the metal gasket 9 'in the gap between the insulator 2' and the housing 7 '. After the insulator 2 ′ is assembled to the housing 7 ′, air exists in the gap between the insulator 2 ′ and the housing 7 ′. When the metal powder M is filled, this air is absorbed by the plasma ignition device. It may be compressed in a space provided in the upper part, or may be extracted from the upper part of the plasma ignition device.

  Further, as in the present embodiment, when a plurality of filling passages 7a ′ are formed (for example, when two filling passages 7a ′ are formed facing each other in the diameter direction), a plurality of filling passages is formed. The metal powder M may be filled at the same time from 7a ', but one filling passage 7a' can be used for air venting. In this case, air is not supplied from the filling passage 7a 'for air venting. If the metal powder M is pushed out without being filled, the filling can be terminated assuming that the filling of the metal powder M is completed.

  The metal gasket 9 ′ in the gap between the insulator 2 ′ and the housing 7 ′ may be filled with a liquid such as liquid ammonia or methanol instead of the metal powder to the atmosphere side. Similarly to the metal powder, the insulator 2 ′ and the housing 7 are in close contact with each other, and heat can be radiated from the insulator 2 ′ to the housing 7 ′.

  In FIG. 1, reference numeral 20 denotes a cylinder head, and this plasma ignition device is screwed into a mounting hole of the cylinder head 20 by a screw portion 7b 'of the housing 7'. In this case, the gap between the mounting hole and the housing 7 'must be sealed in order to communicate with the cylinder. For this purpose, the metal gasket 21 includes, for example, a truncated conical surface 7c ′ formed on the outer surface of the housing 7 ′ of the plasma ignition device and a cylinder head facing the truncated conical surface 7c ′ inside the cylinder from the threaded portion 7b ′. It is arrange | positioned between the truncated conical surfaces 20a of 20 mounting holes.

  In the present embodiment, the aforementioned filling passage 7a 'is formed in the truncated conical surface 7c' of the outer surface of the housing 7 ', and after the metal powder M is filled, copper spraying is performed to close the filling passage 7a. Yes. After performing this copper spraying in a ring shape on the truncated conical surface 7 c ′, the surface is machined and finished, so that the copper sprayed part can be used as the metal gasket 21.

  FIG. 2 is an enlarged cross-sectional view of the vicinity of the chamber 1 showing a second embodiment of the plasma ignition device for an internal combustion engine according to the present invention. Only differences from the first embodiment will be described below. Also in the present embodiment, the gap communicating with the chamber 1 between the insulator and the housing 700 is sealed by the metal gasket 900 that contacts the end surface 200b of the cylindrical tip portion 200a of the insulator. . As a result, the cylindrical tip 200a of the insulator forming the chamber 1 becomes hot due to the discharge in the chamber 1 for generating plasma, but this heat is quickly passed through the metal gasket 900 that comes into contact immediately. Heat can be radiated to the housing 700, and damage to the insulator due to high temperature can be suppressed.

  Also in this embodiment, the housing 700 and the ground electrode 300 are joined together mechanically and electrically by being hermetically joined to each other by welding or the like. In the present embodiment, the ground electrode 300 faces the chamber 1 but does not face the cylinder, and the housing 700 faces the cylinder but does not face the chamber 1. A nozzle hole 800 communicating with the inside of the cylinder is formed through the ground electrode 300 and the housing 700.

  In the present embodiment, the end surface 200b of the insulating cylindrical tip 200a faces not only the ground electrode 300 but also the housing 700, and the metal gasket 900 is the end surface 200b of the insulating cylindrical tip 200a. And the housing 700. In the first embodiment, the heat of the cylindrical tip 2 a ′ of the insulator is radiated from the metal gasket 9 ′ to the housing 7 ′ via the ground electrode 3, but the ground electrode 3 is discharged by the discharge in the chamber 1. Therefore, the ground electrode 3 radiates its own heat to the housing 7 ′ and then radiates heat from the cylindrical tip portion 2 a ′ of the insulator. Will be late.

  On the other hand, in the present embodiment, the heat of the cylindrical end portion 200a of the insulator can be radiated directly from the metal gasket 900 to the housing 700 without going through the ground electrode 300, which is the first embodiment. In comparison, it is possible to dissipate heat faster from the cylindrical tip portion 200a, and it is further difficult to maintain the cylindrical tip portion 200a at a high temperature.

  FIG. 3 is an enlarged sectional view of the vicinity of the chamber 1 showing a third embodiment of the plasma ignition device for an internal combustion engine according to the present invention. Only differences from the first embodiment will be described below. Also in this embodiment, the gap communicating with the chamber 1 between the insulator and the housing 701 is sealed by the metal gasket 901 that contacts the end surface 201b of the cylindrical tip 201a of the insulator. . As a result, the cylindrical tip portion 201a of the insulator forming the chamber 1 becomes hot due to the discharge in the chamber 1 for generating plasma, but this heat is quickly passed through the metal gasket 901 that comes into contact immediately. Heat can be radiated to the housing 701, and damage due to high temperature of the insulator can be suppressed.

  Also in this embodiment, the housing 701 and the ground electrode 301 are hermetically joined to each other by welding or the like, and are mechanically and electrically integrated. In the present embodiment, the ground electrode 301 faces the chamber 1 but does not face the cylinder, and the housing 701 faces the cylinder but does not face the chamber 1. The nozzle hole 801 that communicates with the inside of the cylinder is formed through the ground electrode 301 and the housing 701.

  In the present embodiment, the end surface 201b of the cylindrical tip portion 201a of the insulator faces only the housing 701, and the metal gasket 901 is formed between the end surface 201b of the cylindrical tip portion 201a of the insulator and the housing 701. Arranged between. Thereby, similarly to the second embodiment, the heat of the cylindrical tip portion 201a of the insulator can be radiated directly from the metal gasket 901 to the housing 701, and the heat radiation from the cylindrical tip portion 201a is faster. In addition, the cylindrical tip 201a can be made difficult to maintain at a high temperature.

  In this embodiment, the center electrode side end surface of the ground electrode 301 is not opposed to the cylindrical tip portion 201a of the insulator, and the outer peripheral corner portion 301b of the center electrode side end surface is positioned in the vicinity of the inner surface of the cylindrical tip portion 201a. Therefore, one corner is used for creeping discharge because the inner peripheral corner portion 301c of the end surface on the center electrode side is used for air discharge for plasma generation. It is possible to prevent exhaustion due to being used for air discharge.

  In this embodiment, the end surface 201b of the cylindrical tip 201a with which the metal gasket 901 abuts is an inclined surface that is inclined with respect to the central axis, that is, a truncated conical surface, whereby the metal gasket 901 is formed. Is centered simply by being pressed by the cylindrical tip 201a of the insulator. In the present embodiment, the cylindrical tip portion 201a also has an end surface with a slight width orthogonal to the central axis. Thus, in the present invention, the end surface of the cylindrical tip portion of the insulator Is intended for the tip side surface intersecting the central axis, and may be composed of a plurality of surfaces.

  FIG. 4 is an enlarged cross-sectional view of the vicinity of the chamber 1 showing a fourth embodiment of the plasma ignition device for an internal combustion engine according to the present invention, and FIG. 5 is a cross-sectional plan view of the cylindrical tip portion of the insulator. Only differences from the first embodiment will be described below. Also in this embodiment, the gap communicating with the chamber 1 between the insulator and the housing 702 is sealed by the metal gasket 902 that contacts the end surface 202b of the cylindrical tip portion 202a of the insulator. . As a result, the cylindrical tip 202a of the insulator forming the chamber 1 is heated by the discharge in the chamber 1 for generating plasma, but this heat is quickly passed through the metal gasket 902 that comes into contact immediately. Heat can be radiated to the housing 702, and damage to the insulator due to high temperature can be suppressed.

  Also in this embodiment, the housing 702 and the ground electrode 302 are hermetically joined to each other by welding or the like, and are mechanically and electrically integrated. As shown in FIG. 5, the ground electrode 302 has a cross-shaped end surface on the center electrode side, and is disposed in a part of the housing 702 facing the chamber 1. The four nozzle holes 802 communicating with the chamber 1 and the inside of the cylinder are formed so as to penetrate the chamber 1 and a part of the housing 702 facing the inside of the cylinder while avoiding the ground electrode 302.

  In this embodiment, the end surface 202b of the insulator cylindrical tip portion 202a faces only the housing 702, and the metal gasket 902 is formed between the end surface 202b of the insulator cylindrical tip portion 202a and the housing 702. Arranged between. Thereby, as in the second embodiment, the heat of the cylindrical tip portion 202a of the insulator can be radiated directly from the metal gasket 902 to the housing 702, and the heat is radiated faster from the cylindrical tip portion 202a. In addition, the cylindrical tip 202a can be hardly maintained at a high temperature.

  In the present embodiment, the center electrode side end surface of the ground electrode 302 is not opposed to the cylindrical tip portion 202a of the insulator, and the four peripheral corner portions 302b are positioned in the vicinity of the inner surface of the cylindrical tip portion 202a. Since the four L-shaped corner portions 302c are used for air discharge for plasma generation, one corner portion is used for creeping discharge and air discharge. It is possible to prevent exhaustion due to being used.

  Also in the present embodiment, the end surface 202b of the cylindrical tip portion 202a with which the metal gasket 902 abuts is an inclined surface that is inclined with respect to the central axis, that is, a truncated conical surface. The center 901 is simply positioned by being pressed by the cylindrical tip 202a. In this embodiment, the nozzle hole 802 through which high-temperature and high-pressure plasma is ejected is formed in the housing 702. Since the plasma does not pass through the ground electrode 302, the ground electrode 302 becomes high temperature due to the passage of the plasma. There is no such thing as melting.

It is sectional drawing which shows 1st embodiment of the plasma ignition apparatus by this invention. It is an enlarged view of the chamber vicinity which shows 2nd embodiment of the plasma ignition device by this invention. It is an enlarged view of the chamber vicinity which shows 3rd embodiment of the plasma ignition apparatus by this invention. It is an enlarged view of the chamber vicinity which shows 4th embodiment of the plasma ignition apparatus by this invention. It is a cross-sectional top view of the cylindrical front-end | tip part of the plasma ignition apparatus of FIG. It is a power supply control circuit of a plasma ignition device. It is sectional drawing of the conventional plasma ignition apparatus. It is an enlarged view of the chamber vicinity of the plasma ignition device of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Chamber 2, 2 'Insulator 2a, 2a', 200a, 201a, 202a Cylindrical front-end | tip part 3, 3 ', 300, 301, 302 Ground electrode 4 Center electrode 8, 800, 801, 802 Injection hole 9, 9' , 900, 901, 902 Metal gasket

Claims (3)

  A chamber formed by a cylindrical distal end portion of the insulator and extending in the axial direction; a center electrode disposed on the proximal end side of the chamber; a ground electrode disposed on the distal end side of the chamber; and the insulator In the plasma ignition device comprising a housing that covers the outside of the chamber and that fixes the ground electrode, and a nozzle hole that communicates the chamber and the cylinder, a gap that communicates with the chamber between the insulator and the housing Is hermetically sealed by a metal gasket that contacts the end face of the cylindrical tip.   2. The plasma ignition device for an internal combustion engine according to claim 1, wherein the atmosphere side of the gap from the metal gasket is at least partially filled with metal powder or liquid.   The plasma ignition device for an internal combustion engine according to claim 2, wherein a filling passage communicating with the gap is formed in the housing, and the metal powder or the liquid is filled from the filling passage.

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