JPWO2016021727A1 - Socket and spark plug - Google Patents

Abstract

To provide a socket for supplying a discharge current and electromagnetic waves for spark discharge to a spark plug without providing a separate mixer. The power supply unit 110 electrically connected to the terminal unit 20 of the spark plug 1 and the electromagnetic wave supplied from the electromagnetic wave oscillator 104 are capacitively coupled to the inner conductor 2 of the spark plug 1 through the insulator 3 of the spark plug 1. Thus, an annular antenna 121 that supplies the inner conductor 2 of the spark plug is provided. The annular antenna 121 is preferably configured by winding the end of a coaxial cable used as an electromagnetic wave transmission cable. [Selection] Figure 1

Description

  The present invention relates to a socket for supplying a spark plug with a high voltage for spark discharge and an electromagnetic wave supplied as energy to the spark discharge, and a spark plug attached to the socket.

  2. Description of the Related Art Conventionally, plasma generators have been developed that generate local plasma using spark plug discharge and expand the plasma using electromagnetic waves (microwaves) (see, for example, Patent Document 1). In this plasma generator, a mixer having a mixing circuit that mixes a discharge current (energy for discharge) for spark discharge and energy of electromagnetic waves from the electromagnetic wave generator is provided. Is connected to a connection terminal portion serving as an input terminal of the spark plug. Thereby, the high voltage (discharge current) for spark discharge and the electromagnetic wave are fed to the spark plug through the same transmission line (electric circuit). Therefore, the center electrode of the spark plug serves as both a spark discharge electrode and an electromagnetic wave irradiation antenna.

  However, a mixer that mixes the high-voltage discharge current from the ignition coil and the electromagnetic wave from the electromagnetic wave oscillator in order to flow the high-voltage discharge current and the electromagnetic wave to the center electrode of the ignition plug in this way (hereinafter referred to as a mixer). Is required. This mixer is a circuit for preventing discharge current from leaking to the electromagnetic wave oscillator and electromagnetic wave from leaking to the ignition coil, and its structure is complicated, which causes high cost of the entire apparatus (for example, Patent Document 2). reference).

  Further, both the discharge current and the electromagnetic wave for spark discharge are output from the tip portion of the center electrode. Therefore, the electric field strength generated by the discharge current and the electromagnetic wave between the tip of the center electrode and the ground electrode is highest at the axial core portion of the center electrode. For this reason, since the electric field strength generated by the discharge current and the electromagnetic wave is superimposed, there is a problem that the axial center of the center electrode becomes the highest temperature and the tip of the center electrode is easily melted.

JP 2009-036198 A Japanese Patent Application No. 2013-181700

  The present invention has been made based on the circumstances as described above, and an object of the present invention is to provide a socket for supplying a discharge current and electromagnetic waves for spark discharge to a spark plug without providing a separate mixer. It is an object to provide a spark plug that can be suitably mounted on the vehicle.

A first invention made to solve the above problems is a socket to be attached to a spark plug having a terminal portion that receives power from a high voltage generator,
A power feeding part electrically connected to the terminal part of the spark plug;
An ignition plug socket comprising an annular antenna for supplying electromagnetic waves supplied from an electromagnetic wave oscillator to an inner conductor of an ignition plug through capacitive coupling with an inner conductor of the ignition plug via an insulator of the ignition plug .

  The socket of the present invention supplies electromagnetic waves by capacitive coupling from an annular antenna via an insulator to the surface of the center electrode, which is the inner conductor of the spark plug, and the surface of the conductor cylinder disposed coaxially with the center electrode.

  In this case, the annular antenna can be configured by winding the end of a coaxial cable. An antenna is easily configured by extending and winding an inner conductor of a coaxial cable used as an electromagnetic wave transmitting cable from an outer conductor.

  In addition, the socket body having the feeding portion and the annular antenna inside can be used as an exterior shield having a resonance cavity that resonates electromagnetic waves that flow toward the high voltage generator among electromagnetic waves supplied to the inner conductor. It can be connected via an insulating bushing made of a flexible material. Unlike installation of cavity resonators usually used in electromagnetic equipment, in order to receive the vibration of the internal combustion engine, an earthquake resistant structure is adopted to ensure stable operation of the equipment.

  Further, a coaxial resonator constituting a choke can be disposed in the socket body on the high voltage generator side of the annular antenna. Electromagnetic waves leak to high voltage generators (ignition coils, etc.) to effectively prevent equipment damage.

In addition, a second invention made to solve the above problems is a spark plug to which the socket is attached,
This is an ignition plug in which a coupling coil pattern for impedance matching with the annular antenna is formed on the surface of an insulator having a central electrode electrically connected to a terminal portion that receives power from the outside.

A third invention made to solve the above problem is a spark plug to which the socket is attached,
A center electrode that generates a spark discharge by power feeding from the outside with the ground electrode;
An insulator having a shaft hole into which the center electrode is fitted;
The insulator includes a conductor tube formed coaxially with the center electrode,
The conductor tube is a spark plug in which a spiral cut is formed at a position corresponding to the annular antenna when the socket is mounted.

  The spark plugs of the second and third inventions are spark plugs suitable for mounting the socket of the first invention, and are electromagnetically coupled to electromagnetic waves supplied from an antenna by impedance matching. Is optimized.

As a term of the present invention, when a conductor (center electrode, terminal portion, conductor tube, etc.) is referred to, a metal material such as iron, silver, copper, gold, aluminum, tungsten, molybdenum, titanium, zirconium, niobium, tantalum, This refers to bismuth, lead, tin, or an alloy (for example, stainless steel) or a composite material thereof mainly composed of these materials. When a dielectric (insulator, etc.) is referred to, dielectric material, alumina (AL ₂ O ₃ ), etc. It refers to ceramics etc. as a base material.

  According to the present invention, the discharge current and electromagnetic waves for spark discharge can be supplied to the spark plug without providing a separate mixer, and the cost of the entire apparatus can be reduced by using the socket of the present invention. Can do. Further, even in the case of an ignition plug configured to supply electromagnetic waves by capacitive coupling via a discharge current and an insulator through a terminal portion of the ignition plug, it effectively prevents and supplies the melting of the tip portion of the center electrode. The power loss of electromagnetic waves can be reduced.

It is a front view of the partial cross section figure which shows the socket which concerns on 1st Embodiment. The ignition plug which concerns on 2nd Embodiment is shown, (a) is a front view, (b) is the principal part enlarged view which shows a coil pattern, and the state which formed the helical conductor track | line which open | released both ends, (c) is both ends. The state which short-circuited with the coupling line through the insulating pattern (glass printing) is shown. It is a front view of the partial cross section figure which shows the ignition plug which concerns on 3rd Embodiment. It is a front view of the partial cross section figure which shows the socket which concerns on 4th Embodiment. The antenna of the socket is shown, (a) is a perspective view showing an example in which a notch is 90 °, (b) is 180 °, and (c) is a slit.

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

<Embodiment 1>
-Spark plug socket-
The spark plug socket 100 in this embodiment is a spark plug socket device that is detachably attached to an ignition plug that is attached to a cylinder head of an internal combustion engine or an ignition plug (ignition coil) integrated socket device. And a part that is connected to the spark plug from the ignition coil via the distributor, and a part that is integrated with the spark coil and connected to the spark plug.

  As shown in FIG. 1, this socket 100 is oscillated from an electromagnetic wave oscillator 104 to a socket main body 101, a power feeding unit 110 disposed in the socket main body 101, an annular antenna 121 that radiates electromagnetic waves, and the antenna 121. It is comprised from the cable 120 which supplies the electromagnetic waves which are transmitted, for example, a coaxial cable. As the coaxial cable used as the cable 120, a semi-rigid type coaxial cable can be used in addition to a general coaxial cable.

  The socket body 101 is formed in a cylindrical shape and has a stepped insertion hole 102 therein. The joint portion with the socket body 101, particularly the spark plug 1, is made of a flexible material that can be elastically deformed, an elastic material, for example, an elastically deformable synthetic resin or rubber. The insertion hole 102 includes a small-diameter portion 102a through which a power supply unit 110, which will be described later, is inserted, and a large-diameter portion 102b through which an insulator portion of the spark plug is inserted.

  The power feeding unit 110 is fitted into the small diameter portion 102 a of the insertion hole 102 of the socket body 101. The power supply unit 110 is not particularly limited as long as the terminal unit 20 protruding from the spark plug 1 and the secondary coil side of the ignition coil are electrically connected, but in the present embodiment, the power supply unit 110 is not limited. A hole 111 having a diameter slightly smaller than the outer diameter of the terminal portion 20 is opened so that the connection between the terminal portion 20 and the terminal portion 20 is strong, and the joint portion (the end portion on the spark plug side) is formed into a thin-walled bottomed cylindrical shape. A plurality of notches are formed in the longitudinal direction of the cylindrical peripheral surface. As a result, insertion of the terminal portion 20 is allowed and electrical connection is ensured.

  In the present embodiment, the high voltage from the high voltage generator 103 is supplied to the spark plug 1 through the connection portion 130 that covers the power supply portion 110 protruding from the small diameter portion 102a of the insertion hole 102 of the socket body 101. doing. For a general spark plug, the connecting portion 130 is directly connected to the terminal portion of the spark plug. Therefore, the main body 101 a of the connection unit 130 may be configured integrally with the socket main body 101 and the power supply unit 110 a of the connection unit 130 may be integrated with the power supply unit 110 of the socket 100.

  The antenna 121 is not particularly limited as long as it can supply electromagnetic waves to the inner conductor (the center electrode 2 or the conductor tube 22) of the spark plug 1, but in the present embodiment, the antenna 121 starts from the electromagnetic wave oscillator 104. An inner conductor of a coaxial cable used as a cable 120 for supplying an oscillating electromagnetic wave is extended more than the outer conductor, and the extended portion is turned to form an annular antenna 121.

  As is well known, a coaxial cable is a cable in which an inner conductor, an outer conductor, and an insulator that insulates both conductors are coaxially configured, and the surface of the outer conductor is covered with a protective film. The antenna 121 of the present embodiment is configured by extending an inner conductor of a coaxial cable (cable 120) or an inner conductor covered with an insulator from an outer conductor and a protective coating. The tip of the inner conductor may be an open end, but in this embodiment, it is short-circuited with the outer conductor of the coaxial cable (cable 120). As a result, a short stub is formed at the tip of the antenna. Note that the length of the antenna 121 is preferably configured to be an integral multiple of λ / 4 where λ is the wavelength of the electromagnetic wave to be supplied.

  The antenna 121 configured in an annular shape may be configured by winding a plurality of turns or by a single turn. This number of turns is an element for impedance matching when the spark plug to which the socket 100 is mounted is a spark plug having a coupling coil pattern on the surface of an insulator described later.

  The cable 120 shows an example in which the cable 120 is extended in a straight line. However, in order to optimize the phase of the electromagnetic wave, the cable 120 is wound around the socket body 101 so that the length thereof can be easily changed. It is preferable.

-Spark plug-
The spark plug 1 to which the socket 100 is attached may be a well-known spark plug. However, as shown in FIG. 1, the center electrode 2 and the spark plug 1 can be efficiently irradiated to the combustion chamber. A conductor cylinder 22 (cylindrical conductive member) larger in diameter than the center electrode 2 (excluding the terminal portion 20) is disposed substantially coaxially. Thereby, the transmission path of the electromagnetic wave supplied via the antenna 121 is not the surface of the center electrode 2 but the surface of the conductor cylinder 22, and the electromagnetic wave can be supplied to the combustion chamber in an annular shape.

  The conductor tube 22 may be electrically connected to the terminal portion 20, but may be electrically disconnected from the terminal portion 20 from the viewpoint of reliably blocking the high voltage for discharge supplied from the terminal portion. preferable.

  The conductor tube 22 is not particularly limited as long as it is a metal conductor, but for example, stainless steel, silver, copper, gold, aluminum, tungsten, molybdenum, titanium, zirconium, niobium, tantalum, bismuth, lead, tin, or the main component thereof. An alloy (for example, stainless steel) or a composite material thereof or a material coated with these is used. A coating material (eg, titanium coating) can also be used. The thickness is about 0.04 mm to 0.2 mm, preferably about 0.06 mm to 0.1 mm.

  The electrode tip portion 21 formed at the tip of the center electrode 2 is preferably made of a high melting point and oxidation resistant noble metal (for example, platinum alloy or iridium).

The insulator 3 is formed by a known method, for example, an alumina powder is formed with ceramics based on alumina (AL ₂ O ₃ ) having high insulation and heat and corrosion resistance, by a hydrostatic press, a grinding device, a grindstone, etc. Then, the insulator 3 is manufactured by firing at around 1600 ° C.

As for the insulating cylinder that insulates the center electrode 2 and the conductor cylinder 22, it is preferable to use ceramics based on alumina (AL ₂ O ₃ ) or the like having high insulation properties and heat and corrosion resistance as in the case of the insulator 3. Further, the insulator 3, the conductor tube 22, and the insulating tube may be integrally formed.

  The metal shell 4 is a substantially cylindrical metal case. The metal shell 4 supports the outer periphery of the insulator 3 and accommodates the insulator 3. The inner peripheral surface of the front end portion of the metal shell 4 is separated from the outer peripheral surface of the front end portion of the insulator 3 with a gap. On the outer peripheral surface on the front end side of the metal shell 4, a male screw portion is formed as an attachment structure for attachment to the internal combustion engine. The spark plug 1 is screwed and fixed to the cylinder head by screwing the male screw portion of the metal shell 4 with the female screw portion of the plug hole of the cylinder head. A wrench fitting portion into which a plug wrench is fitted is formed on the upper part of the metal shell 4. In addition, between the wrench fitting part of the metal shell 4 and the insulator 3, powdery talc (talc) is filled as a sealing member, and the end part is crimped.

  The ground electrode 5 forms a discharge gap in which spark discharge occurs with the center electrode 2. The ground electrode 5 includes a ground electrode body 5b and a ground electrode tip 5a. The ground electrode body 5b is a curved plate-like conductor. One end side of the ground electrode main body 5 b is joined to the front end surface of the metal shell 4. The ground electrode body 5b extends from the front end surface of the metal shell 4 along the axis of the spark plug 1 and bends approximately 90 ° inward. The front end side where the ground electrode tip 5a is provided is provided at the front end of the center electrode 2. It faces the electrode tip portion 21 formed.

  In the above configuration, the socket 100 attached to the spark plug 1 supplies a high voltage from the high voltage generator 103 to the terminal portion 20 of the spark plug 1 via the power feeding portion 110, and the supplied high voltage is the terminal portion. 20 and the axial center of the center electrode 2, and a spark discharge (spark discharge) is generated between the electrode tip portion 21 at the tip of the center electrode 2 and the electrode tip portion 5a of the ground electrode 5, that is, in the discharge gap. An electromagnetic wave (microwave) supplied as energy to the spark discharge is passed from the electromagnetic wave oscillator 104 via the cable 120 and the antenna 121 to the inner conductor of the spark plug 1, in this embodiment, the conductor cylinder 22 via the insulator 3. Then, they are capacitively coupled, flow on the surface of the conductor tube 22, and are irradiated (supplied) from the end surface on the ground electrode 5 side toward the combustion chamber in an annular shape. Thus, energy is supplied to the discharge plasma generated in the discharge gap formed between the center electrode 2 and the ground electrode 5, and the plasma is maintained and expanded. Here, the peak portion of the electric field intensity of the irradiated electromagnetic wave is deviated from the axis of the center electrode 2 and deviates from the peak portion of the electric field intensity due to the discharge current. As a result, it is possible to prevent a high temperature at the axial core portion of the center electrode 2 and to effectively prevent the electrode tip portion which is the tip portion of the center electrode 2 from being melted.

-Effect of Embodiment 1-
The discharge current and the electromagnetic wave for spark discharge can be supplied to the spark plug with a simple configuration without separately providing a mixer.

-Modification of Embodiment 1-
In the modification of the first embodiment, the socket body 101 including the power feeding unit 110 and the annular antenna 121 is used as an electromagnetic wave that flows toward the high voltage generator 103 among the electromagnetic waves supplied to the inner conductor of the spark plug 1. It connects with the exterior shield provided with the resonance cavity which resonates through the insulating bushing which consists of flexible materials. In this embodiment, it is assumed that the connection portion 130 and the socket 100 in FIG. 1 are integrated (the socket body 101 and the body portion 101a of the connection portion 130 are integrated).

  A cavity resonator or the like formed of a resonance cavity in a general electromagnetic device is fixed to a transmission path, but in the socket 100 to be attached to an internal combustion engine having a large vibration, an installation coil and an electromagnetic wave oscillator are installed. From the standpoint of securing the cable and shortening the cables (including the cable 120), they are integrally disposed on the top of the socket 100. Therefore, the seismic performance of the device can be improved by connecting via an insulating bushing made of a flexible material. Moreover, the high voltage supply transmission path from the high voltage generator 103 can be provided with coil springs at both ends and can be easily bent to improve the earthquake resistance. By using the coil spring in the transmission path, the coil spring transmits from the antenna 121 to the inner conductor of the ignition plug and functions as a low-pass filter that blocks electromagnetic waves flowing toward the ignition coil side.

<Embodiment 2>
-Spark plug-
The second embodiment is a spark plug according to the present invention. This spark plug is a spark plug attached to the socket of the first embodiment.

  FIG. 2 shows a spark plug according to the second embodiment. The spark plug 1 includes a center electrode 2 electrically connected to a terminal portion 20 that receives power from the outside, an insulator 3 in which a shaft hole 30 into which the center electrode 2 is fitted, and the insulator 3 A discharge in which a spark discharge is generated between the metal shell 4 arranged so as to surround the periphery of the metal plate and the tip of the center electrode 2 (the electrode tip portion 21 of the center electrode 2) extending from the end surface of the metal shell 4. And a ground electrode 5 for forming a gap. And this ignition plug 1 forms the coil pattern 31 for a coupling | bonding which impedance-matches with the cyclic | annular antenna 121 with which the socket of Embodiment 1 is provided on the surface of the insulator 3. FIG.

  The coil pattern 31 formed on the surface of the insulator 3 preferably has a conductor formed on the surface by screen printing. Specifically, on the surface of the insulator, a spiral conductor line 31a (coil pattern) in which both ends of a desired number of turns are opened using a high-conductivity conductor such as silver palladium paste, platinum paste, or silver paste as a raw material. 31) is printed. Thereafter, the coil pattern 31 is covered with glass printing as an insulating material, and the both ends 31b of the glass printing are cut out. Then, the coil pattern 31 which short-circuited the both ends 31b is formed in the surface of an insulator by screen-printing the coupling line 31c which used the silver palladium paste as a raw material so that both ends 31b may be short-circuited. Needless to say, the coil pattern 31 is formed at a position corresponding to the annular antenna 121 when the socket 100 is mounted.

The number of turns of the coil pattern 31 is set to the number of turns obtained by multiplying the number of turns of the antenna 121 by the value N shown in Expression (1) in order to match the impedance with the antenna 121.
N = (Z1 / Z0) ^1/2 Formula (1)
Here, Z1 is the impedance on the antenna side, Z0 is the impedance on the insulator side, and is free space impedance, which is 377 (Ω).
When a coaxial cable having a characteristic impedance of 50Ω is adopted as the antenna 121, N obtained by the equation (1) is N≈3, and when the number of turns of the antenna 121 is 1, the number of turns on the coil pattern 31 side is 3

Further, it is preferable that the coil pattern 31 has a surface area that is 1 / N of the surface area of the antenna 121. For example, if the diameter of the inner conductor of the coaxial cable used as the antenna 121 is 1 mm, the surface area per unit length is 3.14 mm ^{2 and} the surface area of the coil pattern 31 is preferably about 1 mm ² per unit length. .

  In the above configuration, the socket 100 of the first embodiment is attached to the spark plug 1. Then, when a high voltage from the high voltage generator 103 is supplied to the terminal portion 20 of the spark plug 1 via the power feeding portion 110, the supplied high voltage flows through the axial center of the terminal portion 20 and the center electrode 2, and the center electrode Spark discharge (spark discharge) is generated between the electrode tip portion 21 at the tip of 2 and the electrode tip portion 5a of the ground electrode 5, that is, in the discharge gap. Then, the electromagnetic wave (microwave) supplied as energy to the spark discharge passes from the electromagnetic wave oscillator 104 through the cable 120 and the antenna 121, and the impedance-matched coil pattern 31 functions as a secondary coil for coupling. The electromagnetic wave is capacitively coupled to the surface of the inner conductor (center electrode 2) of the spark plug 1 and irradiated (supplied) from the tip of the center electrode toward the combustion chamber. Thus, energy is supplied to the discharge plasma generated in the discharge gap formed between the center electrode 2 and the ground electrode 5, and the plasma is maintained and expanded.

-Modification of Embodiment 2-
In the modification of the second embodiment, a conductor cylinder 22 (cylindrical conductive member) having a diameter larger than that of the center electrode 2 is disposed substantially coaxially with the center electrode 2 in the same manner as the spark plug used in the first embodiment. The conductor tube 22 serves as a transmission path for the supplied electromagnetic wave, efficiently radiates the electromagnetic wave to the combustion chamber, and is supplied as energy to the discharge plasma generated in the discharge gap formed between the center electrode 2 and the ground electrode 5. The plasma is maintained and expanded. Moreover, the peak portion of the electric field strength of the irradiated electromagnetic wave is shifted from the axis of the center electrode 2 and deviates from the peak portion of the electric field strength due to the discharge current. As a result, it is possible to prevent a high temperature at the axial core portion of the center electrode 2 and to effectively prevent the electrode tip portion which is the tip portion of the center electrode 2 from being melted.

-Effect of Embodiment 2-
In the spark plug of the present embodiment, the secondary coil for coupling is formed on the insulator surface by screen printing, so that the electromagnetic wave supplied and the electromagnetic coupling on the spark plug side are optimized.

<Embodiment 3>
-Spark plug-
The third embodiment is a spark plug according to the present invention. This spark plug is a spark plug attached to the socket of the first embodiment.

  FIG. 3 shows a spark plug according to the third embodiment. The spark plug 1 includes a center electrode 2 electrically connected to a terminal portion 20 that receives power from the outside, an insulator 3 in which a shaft hole 30 into which the center electrode 2 is fitted, and the insulator 3 A discharge in which a spark discharge is generated between the metal shell 4 arranged so as to surround the periphery of the metal plate and the tip of the center electrode 2 (the electrode tip portion 21 of the center electrode 2) extending from the end surface of the metal shell 4. And a ground electrode 5 for forming a gap. The spark plug 1 of Embodiment 3 is provided with a conductor cylinder 22 (cylindrical conductive member) having a larger diameter than the center electrode 2 (excluding the terminal portion 20) substantially coaxially with the center electrode 2. The conductor tube 22 has a spiral cut 23 formed at a position corresponding to the annular antenna 121 when the socket 100 of the first embodiment is mounted. In addition, it is preferable that the open end of the insulator 3 on the ground electrode 5 side is formed so as to form a small-diameter stepped portion as shown in FIG.

  The width and interval of the spiral cut 23 are not particularly limited, but as shown in FIG. 3, the cut width is about 0.3 mm and the interval is about 1 mm (a coil having a width of 1 mm is spaced at intervals of 0.3 mm). To be formed). The interval between the spiral cuts 23 is preferably determined by the same calculation as the surface area of the coil pattern 31 described in the second embodiment. The number of turns of the coil formed by the spiral cut 23 is also the same.

  In this way, by forming a coil by the spiral cut 23, the electromagnetic coupling supplied from the antenna 121 and the conductor tube 22 is a combination of dielectric coupling and capacitive coupling, so that the electromagnetic coupling is optimized. The degree of coupling can be increased.

  In the above configuration, the socket 100 of the first embodiment is attached to the spark plug 1. Then, when a high voltage from the high voltage generator 103 is supplied to the terminal portion 20 of the spark plug 1 via the power feeding portion 110, the supplied high voltage flows through the axial center of the terminal portion 20 and the center electrode 2, and the center electrode Spark discharge (spark discharge) is generated between the electrode tip portion 21 at the tip of 2 and the electrode tip portion 5a of the ground electrode 5, that is, in the discharge gap. Then, electromagnetic waves (microwaves) supplied as energy to the spark discharge are transmitted between the antenna 121 and the coil formed by the spiral cut 23 of the conductor tube 22 via the cable 120 and the antenna 121 from the electromagnetic wave oscillator 104. Thus, an electromagnetic wave flows as a combination of dielectric coupling and capacitive coupling, and is irradiated (supplied) from the end of the annular conductor tube 22 toward the ground electrode 5 toward the combustion chamber. Thus, energy is supplied to the discharge plasma generated in the discharge gap formed between the center electrode 2 and the ground electrode 5, and the plasma is maintained and expanded. Moreover, the peak portion of the electric field strength of the irradiated electromagnetic wave is shifted from the axis of the center electrode 2 and deviates from the peak portion of the electric field strength due to the discharge current. As a result, it is possible to prevent a high temperature at the axial core portion of the center electrode 2 and to effectively prevent the electrode tip portion which is the tip portion of the center electrode 2 from being melted.

-Effect of Embodiment 3-
In the spark plug of this embodiment, the coil is formed by forming a spiral cut in the conductor tube (inner conductor) of the spark plug, so that the supplied electromagnetic wave is between the antenna and the conductor tube. It becomes a synthesis of inductive coupling and capacitive coupling, and the degree of coupling of electromagnetic waves can be increased.

<Embodiment 4>
-Spark plug socket-
As in the first embodiment, the ignition plug socket 100 in the present embodiment is an ignition plug socket device or ignition coil (ignition coil) integrated type that is detachably attached to an ignition plug attached to a cylinder head of an internal combustion engine. Of the socket device, which is connected to the ignition plug from the ignition coil via a distributor, and is one that is integrated with the ignition coil and connected to the ignition plug.

  As shown in FIG. 4, the spark plug socket 100 includes a socket body 101, a power feeding unit 110 disposed in the socket body 101, an annular antenna 121 that radiates electromagnetic waves, The antenna 121 includes a cable 120 that supplies an electromagnetic wave oscillated from the electromagnetic wave oscillator 104, for example, a coaxial cable. Except for the structure of the choke 3 and the shape of the antenna 121, the description is omitted for the same parts as in the first embodiment.

  The entire socket body 101 is configured to be covered with a metal cover 130. The cover 130 includes a cylindrical main body 130a, an upper lid 130b, and a lower lid 130c that is grounded by contacting the spark plug 1.

  Reference numeral 140 denotes a metal gasket for reliably grounding the socket 100.

  And the coaxial resonator which comprises the choke 6 is arrange | positioned in the socket main body 101 by the side of the high voltage generator 130 from the cyclic | annular antenna 121. FIG. As a result, electromagnetic waves leak to the high voltage generator 101 (ignition coil or the like), thereby effectively preventing damage to the equipment. It is preferable to fill the insulator 7 up to the inside of the choke 6 and the vicinity of the hole of the power feeding unit 110. The depth L of the choke and the type of insulator 7 (difference in relative dielectric constant) are adjusted by the frequency of the electromagnetic wave to be supplied.

  Moreover, the antenna 121 (coupling ring) of this embodiment is comprised from the cylindrical member which notched part, as shown in FIG. It is preferable that the connection location with the cable 120 for supplying the electromagnetic wave is the upper surface of one end, and the ground line ER connected to the cover 130 (main body portion 130a) is disposed on the upper surface of the other end. The ground line ER is preferably extended from the upper surface of the antenna 121. Further, the angle of the notch is not particularly limited, but 90% of the circumference as shown in FIG. 5 (a), 180% of the circumference as shown in FIG. It is preferable that the wavelength is adjusted to be a quarter wavelength, and a slit 121a can be formed on the peripheral surface of the antenna 121 as shown in FIG. The number of the slits 121a is not particularly limited. However, when the slits 121a are formed in two places as shown in the figure, the length of the electric circuit can be set long by turning the openings upside down. When forming in three places, the opening of the adjacent slit is reversely formed.

  Thereby, the degree of coupling between the antenna 121 and the inner conductor of the spark plug 1 is adjusted well, the reflected wave is reduced, and electromagnetic waves (microwaves) are sufficiently irradiated (supplied) from the tip of the center electrode toward the combustion chamber. Is done. Thus, energy is supplied to the discharge plasma generated in the discharge gap formed between the center electrode 2 and the ground electrode 5, and the plasma is maintained and expanded.

  As described above, according to the present invention, the electromagnetic wave (microwave) supplied as energy to the spark discharge and the spark discharge to the combustion chamber of the internal combustion engine without using a mixer that mixes the high-voltage discharge current and the electromagnetic wave. Therefore, the socket and spark plug of the present invention can be widely used in various internal combustion engines such as automobiles, airplanes, ships and the like. Moreover, it can be used for an internal combustion engine using various fuels (gasoline, light oil, natural gas, surreal gas, etc.) such as a gasoline engine, a diesel engine, and a natural gas engine.

DESCRIPTION OF SYMBOLS 1 Spark plug 2 Center electrode 20 Terminal part 21 Conductor cylinder 23 Spiral cut 3 Insulator 30 Shaft hole 31 Coil pattern 4 Main metal fitting 5 Ground electrode 100 Socket 101 Socket main body 110 Feed part (feed spring)
120 cable 121 antenna

Claims (6)

A socket attached to a spark plug having a terminal portion that receives power from a high-voltage generator,
A power feeding part electrically connected to the terminal part of the spark plug;
A socket provided with an annular antenna that supplies electromagnetic waves supplied from an electromagnetic wave oscillator to the inner conductor of the spark plug by capacitively coupling the electromagnetic plug supplied to the inner conductor of the spark plug via an insulator of the spark plug.   The socket according to claim 1, wherein the annular antenna is configured by winding a tip end of a coaxial cable. A socket body provided with the feeding portion and the annular antenna inside,
The electromagnetic wave supplied to the inner conductor of the spark plug is connected to an exterior shield having a resonance cavity that resonates the electromagnetic wave flowing toward the high voltage generator through an insulating bushing made of a flexible material. 2. The socket according to 2.   The socket according to claim 3, wherein a coaxial resonator constituting a choke is disposed in a socket body closer to a high voltage generator than the annular antenna. A spark plug to which the socket according to claim 1 is mounted,
An ignition plug in which a coupling coil pattern for impedance matching with the annular antenna is formed on a surface of an insulator having a central electrode electrically connected to a terminal portion that receives power from the outside. A spark plug to which the socket according to claim 1 is mounted,
A center electrode that generates a spark discharge by power feeding from the outside with the ground electrode;
An insulator having a shaft hole into which the center electrode is fitted;
The insulator includes a conductor tube formed coaxially with the center electrode,
The conductor tube is a spark plug in which a spiral cut is formed at a position corresponding to the annular antenna when the socket is mounted.

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