JP2012119273A - High frequency plasma ignition device and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high frequency plasma ignition device which meets a down-sizing demand in recent years, and has durability hard to cause breakage even if excessive tightening torque is loaded thereon when installed in an internal combustion engine, and to provide a manufacturing method thereof.SOLUTION: A hollow part 22 of a coaxial resonator 23 is demarcated inside an insulator 10 to insulate and hold a high pressure electrode 30, and a discharge part 323 provided at the tip of a high voltage electrode 30, and a tip part of a central conductor 21 of the coaxial resonator 23 are exposed and fixed in a combustion chamber CMB of the internal combustion engine E/G by a housing 70 arranged concentrically to the insulator 10 and covering the outer periphery thereof.

Description

  The present invention relates to a high-frequency plasma ignition device that is mounted on a hardly ignitable combustion engine and ignites the combustion engine, and a method for manufacturing the same.

In an internal combustion engine such as an automobile engine, in order to reduce environmental load substances contained in combustion exhaust and to further improve fuel efficiency, fuel dilution, high supercharging, etc. are being attempted.
In general, a lean combustion engine and a high supercharged air-fuel mixture combustion engine are difficult to ignite, and therefore an ignition device with better ignitability is desired.

In particular, in a so-called spray guide type engine in which a combustible layer in which the mixture ratio of fuel spray and air is close to the stoichiometric air-fuel ratio is arranged only in the vicinity of the spark plug to further dilute the mixture. However, with a relatively small spark discharge of a conventional spark plug, the combustible layer is not always located at the discharge position of the plug, and it is difficult to ignite, or a relatively large ground electrode exists near the flame core, There is a possibility that the effect is great and the combustion speed becomes slow.
Further, in order to purify combustion exhaust gas and reduce fuel consumption, the intake and exhaust valves of the internal combustion engine have been increased in size, and further reduction in the diameter of the ignition device is expected.

In order to solve such problems, the present inventors are an ignition device that is mounted on an internal combustion engine and ignites the internal combustion engine, and oscillates from a power source, a high-frequency oscillation circuit, a high-voltage circuit, and the high-frequency oscillation circuit. A resonance tube that transmits and amplifies the high frequency, and a high-voltage delivery conductor that transmits a high voltage from the high-voltage circuit while maintaining insulation from the resonance tube, and at least the open end of the resonance tube A part of the resonant tube is exposed from the high-voltage circuit after being exposed to the combustion chamber of the internal combustion engine and oscillated high frequency from the high-frequency oscillation circuit into the combustion chamber of the internal combustion engine via the resonant tube. And an ignition device characterized in that a high voltage is applied between the high-voltage delivery conductor and a part of the resonant tube and the high-voltage delivery conductor is discharged (see Patent Document 1). ).
The present inventors made further improvements to the high-frequency plasma ignition device shown in Patent Document 1, and in the high-frequency plasma ignition device 1z shown in FIG. 14, the size of the screw portion 712 for fixing to the internal combustion engine is up to M14. Successfully miniaturized.

However, in the conventional high-frequency plasma ignition device 1z, in order to reduce the size of the device, the thickness of each member is made as thin as possible to withstand practical use, and in addition, a substantially cylinder covering the center electrode 30z to which a high voltage is applied. Since the insulator 10z is provided at a position eccentric with respect to the central axis of the high-frequency plasma ignition device 1z, an appropriate torque is applied when the high-frequency plasma ignition device 1z is fastened to the cylinder head SH of the internal combustion engine E / G. When the above force is applied, the metal housings 70z and 71z bend, and as shown in FIG. 15, insulation is performed using the diameter changing portion 104z locked to the insulator locking portion 705z of the housing 70z as a fulcrum. with respect to a direction perpendicular to the central axis of the body 10z, and the moment M ₂ of the moment M ₁ and reverse screwing direction acts, it cracked at the base of the diameter change portion 104Z, The small diameter portion 102z of Entai 10z has been found that there is a risk that falling off the combustion chamber CMB side.

  Therefore, in view of such circumstances, the present invention is a high-frequency plasma ignition device having a structure that conforms to recent demands for miniaturization and that does not cause damage even when a force exceeding an appropriate torque is applied during assembly. The purpose is to provide a manufacturing method.

In the first invention, an ignition energy supply control device having a high frequency power source that oscillates a high frequency and a high voltage power source that applies a high voltage, an inner conductor, and a predetermined cavity around the inner conductor, A high frequency power is input from the high frequency power source to the coaxial resonator in which the outer conductor is disposed coaxially, the electric field strength at the tip of the inner conductor is increased, and a high voltage is applied to the high voltage electrode from the high voltage power source. Discharge is performed between the discharge portion located on the tip side of the voltage electrode and the tip portion of the center conductor of the center conductor, and the internal combustion engine is ignited with the gas around the tip of the inner conductor being in a high energy plasma state. A high-frequency plasma ignition device,
The cavity of the coaxial resonator is partitioned into a part of the insulator for insulatingly holding the high-voltage electrode, and the tip of the high-voltage electrode and the tip of the coaxial resonator are covered by a housing that covers the outer periphery of the insulator. Is exposed and fixed in the combustion chamber of the internal combustion engine (claim 1).

According to the first invention, since the housing is arranged concentrically with respect to the insulator, the insulation is not affected even when the housing is assembled to an internal combustion engine with an excessive load exceeding an appropriate torque. There is no possibility that a force in the screwing direction or the opposite direction acts on the side surface of the body, and there is no possibility that the insulator is damaged.
Therefore, high reliability can be improved in a high-frequency plasma ignition device that generates a plasma at the tip of the central conductor of the coaxial resonator by applying a high-frequency input and applying a high voltage.

  In the second invention, the outer conductor layer made of a metal film covering the whole or part of the surface of the inner peripheral wall of the resonator cavity portion partitioned inside the insulator, and placed at the center of the resonator cavity portion The coaxial resonator is constituted by the inner conductor (claim 2).

  According to the second invention, even if the thickness of the outer conductor layer of the coaxial resonator is reduced, sufficient strength is ensured by the insulator that partitions the resonator cavity, so that the high-frequency plasma ignition device It is very easy to reduce the size.

  In the third invention, the outer conductor layer has a thickness of 10 μm or more and 100 μm or less (invention 3).

  According to the third aspect of the invention, the outer conductor layer resonates within the resonator cavity without leaking the high frequency input to the center conductor, and forms a portion with high electric field strength at the tip of the center conductor. Thus, it is possible to reduce the size of the high-frequency plasma ignition device that generates plasma and ignites the internal combustion engine.

  In the fourth invention, an ignition energy supply control device having a high-frequency power source that oscillates a high frequency and a high-voltage power source that applies a high voltage, an inner conductor, and a predetermined cavity around the inner conductor, A high frequency power is input from the high frequency power source to the coaxial resonator in which the outer conductor is disposed coaxially, the electric field strength at the tip of the inner conductor is increased, and a high voltage is applied to the high voltage electrode from the high voltage power source. Discharge is performed between the discharge portion located on the tip side of the voltage electrode and the tip portion of the center conductor of the center conductor, and the internal combustion engine is ignited with the gas around the tip of the inner conductor being in a high energy plasma state. A method for manufacturing a high-frequency plasma ignition device, wherein at least an insulating heat-resistant material is used, and a cavity cavity is formed inside by any one of pressure molding, HIP molding, SIP molding, injection molding, or extrusion molding. Ward An insulator forming step for forming an insulator having holes, and an inner peripheral surface of the resonator cavity partition hole and a surface of the resonator engaging portion are plated with a highly heat-resistant conductive material, CVD ( Chemical vapor deposition method), PVD (physical vapor phase method), vacuum deposition, metal foil sticking, printing, direct bonding, outer conductor layer forming step to form the outer conductor layer, and the metal material in a substantially cylindrical shape The above-mentioned insulator is disposed concentrically on the housing formed in the above-described manner, and an assembly and caulking step for caulking and fixing via a predetermined sealing member are provided.

  According to the fourth invention, it is possible to realize a high-frequency plasma ignition device having a highly reliable structure that does not cause breakage even when a force greater than an appropriate torque is applied during assembly.

The outline | summary of the high frequency plasma ignition apparatus in the 1st Embodiment of this invention is shown, (a) is a longitudinal cross-sectional view, (b) is a side view, (c) is a bottom view, (d) is a top view. The effect of this invention is shown with a comparative example, this figure (a) shows the effect with respect to size reduction, FIG. 1 () shown as sectional drawing along AA in FIG.12 (b) shown as a comparative example, and FIG. a) A cross-sectional view taken along the line AA, and FIG. 5B is a characteristic diagram showing the frequency of occurrence of cracks when tightened with excessive torque. The outline | summary of the insulator which is the principal part of the high frequency plasma ignition apparatus of this invention is shown, (a) is a top view, (b) is a longitudinal cross-sectional view along AA in this figure (a), (c) ) Is a side view, and (d) is a bottom view. The partially cutaway perspective view shown about an outer conductor formation process in the manufacturing process of the high frequency plasma ignition device of the present invention. Sectional drawing which shows order of (a) to (b) about a high voltage electrode formation process in the manufacturing process of the high frequency plasma ignition apparatus of this invention following FIG. Sectional drawing which shows the order of a coaxial resonator formation process in order from the manufacturing process of the high frequency plasma ignition device of this invention following FIG. 5 in order of (a) to (b). Sectional drawing which shows the outline | summary of an assembly | attachment process during the manufacturing process of the high frequency plasma ignition device of this invention following FIG. Sectional drawing which shows the outline | summary of a caulking process in the manufacturing process of the high frequency plasma ignition device of this invention following FIG. Sectional drawing which shows the outline | summary of a completion process in the manufacturing process of the high frequency plasma ignition apparatus of this invention following FIG. The partially notched perspective view which shows the modification of the insulator which is the principal part of the high frequency plasma ignition apparatus of this invention shown to (f) from (a). The outline | summary of the high frequency plasma ignition apparatus in the 2nd Embodiment of this invention is shown, (a) is sectional drawing, (b) is the principal part perspective view seen from the combustion chamber side. The outline | summary of the high frequency plasma ignition apparatus in the 3rd Embodiment of this invention is shown, (a) is a partially notched perspective view of the insulator which is the principal part of this embodiment, (b) is sectional drawing of the whole. . Sectional drawing which shows the outline | summary of the high frequency plasma ignition apparatus in the 4th Embodiment of this invention. The outline of the conventional high frequency plasma ignition apparatus is shown as a comparative example, (a) is a longitudinal cross-sectional view, (b) is a side view, (c) is a bottom view, (d) is a top view. The problem of the conventional high-frequency plasma ignition device shown as a comparative example is shown, (a) is a longitudinal sectional view showing a state assembled to an internal combustion engine, and (b) is along AA in this figure (a). An arrow sectional drawing and (c) are schematic diagrams which show the force which acts on the conventional insulator.

With reference to FIG. 1, the outline | summary of the high frequency plasma ignition apparatus 1 in the 1st Embodiment of this invention is demonstrated.
The high-frequency plasma ignition device 1 exhibits good ignitability even in a low-ignition engine such as a lean combustion engine with a high air-fuel ratio or a high supercharged air-fuel mixture combustion engine with a high air-fuel ratio and compression ratio using a supercharger. By applying a high voltage HV to the high-voltage electrode 30 in a state where the electric field strength at the tip of the inner conductor 21 of the coaxial resonator 23 is increased by the oscillation of the high-frequency MW, the high-voltage electrode discharge part 323 and the tip part of the inner conductor 21 The internal combustion engine is ignited with the surrounding gas in a high energy plasma state.

  The high-frequency plasma ignition device 1 supplies an energy supply power supply 90 that controls and supplies the application of the high voltage HV and the oscillation of the high-frequency MW according to the ignition signal IGt transmitted from the engine control device (not shown) according to the operating state of the internal combustion engine. A coaxial connector 40 to which a high frequency MW is input from the energy supply power supply 90 via the coaxial cable 41, a connector fixing portion 50 for fixing the coaxial connector 40, and a high voltage input means 80 from the energy supply power supply 90 through the high voltage input means 80. The high voltage electrode 30 to which the voltage HV is applied, the high voltage electrode 30 is insulated and held, the insulator 10 including the coaxial resonator 23, and the housing 70 that is disposed concentrically with the insulator 10 and covers the outer periphery thereof. The outer conductor made of a metal film that covers all or part of the surface of the inner peripheral wall of the resonator cavity 22 partitioned inside the insulator 10. The layer 20, constitutes a coaxial resonator 23 by an inner conductor 21 placed on the center of the resonator cavity 22.

The insulator 10 is made of a heat-resistant insulating material having excellent thermal conductivity, such as alumina, and is concentric with the insulator head 100 and the housing 70 exposed upward from the housing 70 and expands in the outer diameter direction. Are formed in a substantially stepped columnar shape having an insulator large diameter portion 101 and an insulator small diameter portion 102 having a diameter smaller than that of the insulator large diameter portion 101.
The insulator 10 which is a main part of the present invention is provided with a resonator cavity section hole 110 for partitioning the resonator cavity section 22 on the inner side, and the surface of the inner peripheral wall forms the outer conductor layer 20. Covered with metal film.

The center conductor 21 is made of a heat-resistant conductive material such as Ni or Ir, and has a center conductor grounding portion 210 formed in a substantially disk shape and a center conductor shaft portion 212 extending from the center toward the tip side in a long axis shape. It is constituted by.
The center conductor grounding portion 210 is provided with a center conductor insertion hole 211 penetrating from the base end side toward the tip end side, and the center conductor 400 is inserted through the dielectric layer 401.
A coaxial resonator locking portion 109 is formed on the proximal end side of the resonator cavity portion 22 and the center conductor grounding portion 210 is locked.
A locking portion grounding conductor layer 201 is formed on the surface of the coaxial resonator locking portion 109 so as to continue to the outer conductor layer 20, and is in close contact with the center conductor grounding portion 210, so that the outer conductor layer 20 and the supporting portion grounding conductor are in contact. The layer 201, the center conductor grounding portion 210, and the center conductor shaft portion 212 are electrically connected.
The outer conductor layer 20, the center conductor 21, and the resonator cavity 22 form a coaxial resonator 23.

A high-frequency conductor connecting portion 213 provided at a predetermined position of the central conductor 21 is connected to a central conductor 400 for inputting a high-frequency MW, and is connected to the ignition energy supply control device 90 via the coaxial connector 40 and the coaxial cable 41. Connected to a high-frequency power circuit.
The center conductor 400 is covered with a dielectric layer 401 made of a flexible material such as polytetrafluoroethylene or polyethylene.
The outer periphery of the dielectric layer 401 is covered with an outer conductor metal film 122 provided on the inner peripheral wall of the high-frequency conductor insertion hole 121 formed in the coaxial resonator grounding portion insertion hole sealing insulator 12. The outer conductor metal film 122 prevents leakage of the high frequency MW transmitted through the center conductor 400 to the outside, like the outer conductor network assembly line 412 of the coaxial cable 41.
The central conducting wire 400 is connected to the coaxial cable 41 via the coaxial connector 40 held by the coaxial connector fixing portion 50 and is connected to a high-frequency power supply circuit provided in the external ignition energy supply control device 90.
As the coaxial cable 41, a commercially available cable can be used. The coaxial cable 41 includes a central copper wire 410 made of a conductive material such as a copper wire, a dielectric layer 411 made of a flexible insulating material such as polyethylene, a braided wire, a metal foil, or the like. The outer conductor 412, the insulating coating layer 413 made of a protective material such as insulating polyvinyl, and the connector plug 414 are configured.
The coaxial connector fixing portion 50 is formed in a substantially disk shape using a conductive material, and an insulator head insertion for inserting the connector fixing screw portion 501 for inserting and fixing the coaxial connector 40 and the insulator head 100. A hole 502 is formed.
The coaxial connector fixing part 50 fixes the coaxial connector 40 and presses the coaxial resonator grounding part insertion hole sealing insulator 12 to maintain the center conductor grounding part 210 and the grounding conductor layer 201 in a close contact state. .

The insulator head 100 is provided at a position eccentric to one side from the central axis of the insulator large diameter portion 102.
High-voltage electrode insertion holes 105, 106, and 107 are formed along the central axis of the insulator head 100.
The high voltage electrode 30 to which the high voltage HV is applied is inserted and fixed in the high voltage electrode insertion holes 105, 106, and 107.
The high-voltage electrode 30 includes a high-voltage electrode terminal portion 301 exposed on the proximal end side of the insulator head 100, a high-voltage electrode stem 301 accommodated and held in the high-voltage electrode insertion hole 106, and the high-voltage electrode stem at the high-voltage electrode locking portion 106. The conductive adhesive layer 31 for bonding and fixing 301 and the high voltage electrode 320, the high voltage electrode middle shaft 320 held in the high voltage electrode middle shaft insertion hole 107, and the high pressure exposed to the combustion chamber side and in contact with the lower end surface of the insulator 10. The electrode engaging portion 321, the high-voltage electrode bent portion 322 bent toward the central conductor 21, and the high-voltage electrode discharge portion 323 provided at the tip thereof.

  The insulator large diameter portion 101 is disposed on the distal end side of the coaxial connector fixing portion 50, the sealing member 601, and the insulator diameter changing portion 104 disposed on the proximal end side of the insulator large diameter portion upper surface portion 103. It is clamped over the entire circumference by the crimping portion 708 and the housing locking portion 705 of the housing 70 via the sealing members 602 and 603.

The housing 70 is made of a metal material such as steel, carbon steel, and stainless steel, and is formed in a substantially cylindrical shape.
The housing 70 includes a housing lower portion 701 positioned on the distal end side of the substantially cylindrical housing boss portion 700 and a housing upper portion 703 positioned on the proximal end side, and an insulator small-diameter portion of the insulator 10 is formed inside the housing lower portion 701. A small-diameter portion insertion hole 702 for inserting 102 is formed, and a large-diameter portion insertion hole 704 for inserting the insulator large-diameter portion 101 is formed in the housing upper portion 703. The diameter of the large diameter portion insertion hole 704 is reduced to a mortar shape, and a housing locking portion 705 for locking the insulator diameter changing portion 104 of the insulator 10 is formed. The proximal end side of the housing 70 is crimped A portion 708 is formed to hermetically seal the insulators 10 and 50 through the sealing members 600, 601, and 602.
A housing hexagonal portion 706 is formed on the outer periphery of the housing upper portion 703, and a screw portion 707 for fixing the housing 70 to the combustion chamber of the internal combustion engine is formed on the outer periphery of the housing lower portion 701. The tip of the center conductor 21 and the tip of the outer conductor layer 20 that are fixed to the combustion chamber of the engine and constitute the high voltage electrode discharge part 323 and the coaxial resonator 23 are held in an exposed state in the combustion chamber.
In the present embodiment, the screw diameter of the housing screw portion 707 is formed to M12.

As the high voltage input means 80, a publicly known one is used, and it is constituted by a high voltage input terminal 810 accommodated in the connector cap 800 and a high voltage supply harness 811 connected thereto. The connector cap 800 is made of a heat-resistant insulating material such as silicon, epoxy resin, or phenol resin. A copper wire or the like is used for the high voltage supply harness 811. The high-voltage input terminal 810 is made of a conductive material and is formed in a substantially cylindrical shape. When the connector cap 800 is inserted into the insulator head 100, the high-voltage input terminal 810 and the high-voltage electrode terminal portion 301 are elastic. It becomes a conductive state, and is connected to a high voltage power supply circuit of the ignition energy supply control means 90 provided outside.
The high voltage power supply circuit may be either a CDI type (capacitive discharge type) or a TCI (inductive discharge type), and a known high voltage power supply circuit can be used as appropriate.
In addition to known magnetrons, the high frequency power supply circuit includes a high frequency oscillation circuit that oscillates by converting a direct current supplied from a direct current power source such as an in-vehicle battery into a high frequency alternating current, and a high frequency oscillation generated from the high frequency oscillation circuit. A high-frequency amplifier circuit configured to amplify can be used. As the high-frequency amplifier circuit, a preamplifier that amplifies a high frequency of about several mW oscillated from the high-frequency oscillation circuit to about several W and a preamplifier It can be constituted by a power amplifier that further amplifies the high frequency to about several tens w to 300 w.

  As the power amplifier, it is desirable to use a high-frequency power device including a wide band gap semiconductor such as a Si semiconductor, a SiC semiconductor, a GaN semiconductor, or a diamond semiconductor. A high-frequency power device using a wide band gap semiconductor has good high-frequency characteristics, and can amplify a high frequency to a high output while suppressing frequency fluctuation. The high frequency used in the present invention is a microwave having a wavelength of 10 mm to 1000 mm and a frequency of 300 MHz to 30 GHz. In particular, it is practical to use an ISM band of 2 to 4 GHz.

The ignition energy supply control unit 90 includes a high-frequency oscillation circuit that oscillates a high-frequency MW in accordance with an ignition signal IGt transmitted from an engine control device (not shown) according to the operating state of the internal combustion engine, and a high voltage that applies a high voltage HV. And a power supply circuit.
The high-frequency MW oscillation generates a high-frequency standing wave with the high-frequency conductor connecting portion 213 as a node and the tip of the center conductor 21 as an antinode, and a region having a high electric field strength is formed on the tip end side of the center conductor 21. Is excited to be easily ionized and a high voltage HV is applied to the high-voltage electrode 30, a discharge occurs between the high-voltage electrode discharge part 323 and the tip of the central conductor shaft part 212, resulting in a large volumetric plasma flame. Is generated and the internal combustion engine E / G is ignited.

As shown in FIG. 2A, in the conventional high-frequency plasma ignition device 1z shown as a comparative example, the screw diameter is limited to M14. However, as shown in the present embodiment, the screw diameter is set to M11 to M14. Downsizing to M12 can achieve downsizing of about 30%. In the conventional configuration, since the outer conductor layer 20z is formed of a metal into a cylindrical shape, it is necessary to maintain its own mechanical strength, and it is difficult to obtain a thickness of 1 mm or less.
On the other hand, according to the present invention, the outer conductor layer 20 is formed on the surface of the resonator cavity 22 provided inside the insulator 10, so that the mechanical strength of the outer conductor layer 20 itself is not required at all, and the high frequency MW It is only necessary to secure a minimum film thickness that prevents leakage of the liquid crystal and enables the resonant state of the high frequency MW to be formed in the coaxial resonator 23. Therefore, it is extremely advantageous for downsizing.
Moreover, as shown in this figure (b), in the comparative example, when it was attached to the internal combustion engine with a force exceeding the appropriate torque, damage to the insulator 10z was observed in 4 out of 5 samples. In the example, the insulator 10 was not damaged. This is presumably because the tightening torque applied to the housing hexagonal portion 706 does not act at all in the side surface direction of the insulator 10 because the insulator 10 of the present invention is disposed concentrically with the housing 70. The

With reference to FIG. 3, the structure of the insulator 10 which is the main part of the present invention and the method for forming the same will be described in detail.
The insulator 10 is made of an insulating heat-resistant material such as alumina, and is formed into a substantially stepped column shape by any one of pressure molding, HIP molding, SIP molding, injection molding, or extrusion molding as an insulator forming step. Is formed.
Substantially cylindrical insulator head 100 is formed to project proximally from the insulator upper surface portion 103 at a position around the head center axis CL ₁₀₀ from the center axis CL ₁₀ of the insulator 10 is eccentric to one side ing.
The outer diameter φD ₁₀₀ and the protruding length of the insulator head 100 can be appropriately changed within a range in which leakage discharge does not occur between the housing 70 and the high-voltage electrode 30.
An insulator large diameter portion 101 having a large diameter is formed in the middle part of the insulator 10, and an insulator small diameter portion 102 having a small diameter concentrically with the insulator large diameter portion 101 is formed on the distal end side. Between the portion 101 and the small-diameter portion 102, a diameter changing portion 104 that has a tapered diameter is formed.
Voltage electrode stem insertion hole 105 along the head center axis _{CL 100} of the insulator head 100, the high voltage electrode engaging portion 106, the high-voltage electrode axial rod insertion hole 107 is bored.
A coaxial resonator grounding portion insertion hole 108 for inserting the coaxial resonator grounding portion 211 is formed at a position centering on the resonator central axis CL ₁₁₀ so as to circumscribe the outer circumference circle of the insulator head 100. ing.
Further, a resonator cavity partitioning hole 110 that is connected to the coaxial resonator grounding part insertion hole 108 and partitions the resonator cavity 22 is formed.
The cavity hollow section hole 110 has a diameter smaller than that of the coaxial resonator grounding portion insertion hole 108, and becomes a resonator locking portion 109 for locking the coaxial resonator grounding portion 211 therebetween. ing.
The length L of the cavity hollow section hole 110 is formed to be ¼ of the wavelength λ of the input high frequency MW.
For example, since the wavelength λ of the high frequency MW having the frequency of 2.45 GHz is 122.4 mm, the length L of the resonator cavity partition hole 110 is set to 30.6 mm.
The inner diameter φD ₁₁₀ of the resonator cavity section hole ₁₁₀ is 5.4 mm.
It has been found that the power loss can be reduced if the inner diameter φD ₁₁₀ is set such that the ratio of the inner diameter φD _{110 to} the diameter of the central conductor 21 serving as an antenna is about 3.6.
In this embodiment, φD ₁₀₀ = 4 mm, φD ₁₀₁ = 12 mm, φD ₁₀₂ = 10 mm, φD ₁₀₅ = 2 mm, φD ₁₀₇ = 0.5 mm, φD ₁₀₈ = 6.0 mm, and φD ₁₁₀ = 5.4 mm. Has been.

With reference to FIGS. 4 to 9, an outline of a method for manufacturing the high-frequency plasma ignition device of the present invention will be described.
First, in the outer conductor layer forming step shown in FIG. 4, a highly heat-resistant conductive material such as nickel is applied to the inner peripheral surface of the resonator cavity partition hole 110 formed in the insulator 10 and the surface of the resonator locking portion 109. The outer conductor layer 20 and the ground conductor layer are formed by any one of plating, CVD (chemical vapor deposition), PVD (physical vapor deposition), vacuum deposition, metal foil sticking, printing, and direct bonding using a conductive material. 201 is formed. At this time, the outer conductor layer 20 and the ground conductor layer 201 are integrally formed and are in a conductive state.
Further, a conductor layer is prevented from being formed on portions other than the inner peripheral surface of the resonator cavity partition hole 110 and the surface of the resonator locking portion 109 by masking or the like.
Further, it has been found that the thickness of each conductor layer 20 and 21 should be at least 10 μm and not more than 100 μm in order not to leak high frequency to the outside.
Since high-frequency electricity flows on the surface of a conductor, it is important that the surface has high conductivity. Therefore, a metal material having high conductivity such as silver is thinly plated. Alternatively, in order to reduce the cost, a method such as plating a part may be taken.
Further, in consideration of adhesion strength and durability with the insulator 10, a base layer is formed of nickel or the like, and a conductive layer is formed thereon using a metal material having high conductivity such as silver, platinum, or gold. May be.
In the present embodiment, the film is formed to a thickness of about 50 μm by plating.
The outer conductor layer 20 is formed inside the insulator 10 in any of plating, CVD (chemical vapor deposition), PVD (physical vapor deposition), vacuum deposition, metal foil sticking, printing, and direct bonding. Therefore, a much higher strength can be obtained even when the thickness of the outer conductor is much thinner than when a metal cylinder is formed.

Next, in the high-voltage electrode forming step shown in FIG. 5, as shown in FIG. 5A, the high-voltage electrode input terminal portion 301, the high-voltage electrode stem 302, the conductive adhesive layer 31, and the high-voltage electrode middle shaft portion constituting the high-voltage electrode 30. 320 is inserted into the high-voltage electrode stem insertion hole 105 and the high-voltage electrode middle shaft insertion hole 107, and then, as shown in this figure (b), the high-voltage electrode stem 302 and the high-voltage electrode middle shaft portion 320 are pushed in from above and below to conduct conductive bonding. The layer 31 is heated and melted to form an integrated high-voltage electrode 30. At this time, a resistance component can be mixed in the conductive adhesive layer 31 to form a noise prevention resistor.
Further, a high-voltage electrode locking portion 321 is formed at the lower end of the high-voltage electrode middle shaft portion 320, and a high-voltage electrode bent portion 322 whose tip is bent toward the inner conductor 21 is formed. A high-voltage electrode discharge part 323 using Ni or the like having a high density is formed.
When the high-voltage electrode middle shaft portion 320 is inserted into the high-voltage electrode middle shaft insertion hole 107 of the insulator 10, the high-voltage electrode locking portion 321 contacts the bottom surface of the insulator 10, and the high-voltage electrode discharge portion 323 is placed at a predetermined position. Will be.

Next, the coaxial resonator forming step will be described with reference to FIG.
As shown in FIG. 6A, the outer conductor is formed on the surface of the high-frequency conductor insertion hole 121 formed in the sealing insulator base 120 of the coaxial resonator base portion insertion hole sealing insulator 12 formed in advance in a cylindrical shape. Layer 122 is formed. At this time, the outer conductor layer 122 can be formed by the same method as in the outer conductor layer forming step described above.
The center conductor 400 connected to the coaxial connector 402 and covered with the dielectric layer 401 is inserted into the connector fixing screw portion 501 of the connector fixing portion 50, and further, the center conductor is inserted into the center conductor grounding portion 210 of the center conductor center shaft 212. It is pulled out from the hole 211 and connected to the high-frequency conductor connecting part 213 located at a predetermined height ΔL (for example, 1 mm) from the center conductor grounding part 210 as shown in FIG.
At this time, a flexible material such as polyethylene is used for the dielectric layer 401, and the outer conductor coating using a braided wire or a metal foil is not formed on the outer periphery of the dielectric layer 401 like a normal coaxial cable. Since it can be freely deformed, it can be easily inserted into the high-frequency conductor insertion hole 121.
On the other hand, since the outer conductor layer 122 is formed on the inner peripheral surface of the high-frequency conductor insertion hole 121, the central conductor 400, the dielectric layer 401, and the outer conductor layer 122 constitute a coaxial cable, and high frequency leaks to the outside. There is nothing.
Further, a core conductor 400 that is insulated from the center conductor grounding portion 210 via the dielectric layer 401 is connected through the coaxial resonator grounding portion insertion hole 108 of the insulator 10, and the center conductor grounding portion 210 is connected. It abuts on the coaxial resonator locking part 109.
At this time, the tip of the central conductor shaft portion 212 is in a state of protruding by ΔL toward the tip of the outer conductor layer 20.
The coaxial resonator base portion insertion hole sealing insulator 12 is inserted into the coaxial resonator base portion insertion hole 108 and the center electrode ground portion 211 is pressed so that the center electrode ground portion 211 and the ground conductor layer 201 are brought into close contact with each other. The coaxial resonator base insertion hole 108 is sealed while aiming.
As described above, the coaxial resonator 23 is formed in the insulator 10 by the center conductor 21, the resonator cavity 22, and the outer conductor layer 20.

Next, an assembly process and a caulking process will be described with reference to FIGS.
As shown in FIG. 7, the insulator 10 in which the coaxial resonator 23 and the high-voltage electrode 30 are incorporated through the above-described steps is inserted into the housing 70 through the sealing members 600, 601, and 602.
For the sealing member 600 and the sealing member 602, a metallic sealing member formed in a substantially annular shape is used, and for the sealing member 601, a powder compact obtained by pressing and heat-resistant ceramic powder such as talc is used. It has been.
As shown in FIG. 8, by crimping the opening end of the housing 70, the insulator 10, the sealing members 600, 601 and 602, and the coaxial cable connection portion 50 accommodated in the housing 70 are integrally sealed. .
At this time, the insulator large-diameter portion 101 has a housing crimped portion 708 of the housing 70 disposed concentrically with the insulator 10 via the sealing members 600, 601, 602 and the base portion 502 of the coaxial cable connecting portion 50. And the insulator locking portion 705 are uniformly pressed from the top and bottom over the entire circumference and are kept airtight.
Further, at this time, the coaxial resonator base portion insertion hole sealing insulator 12 is pressed by the coaxial connector fixing portion 50 formed in a substantially disc shape, and the center conductor ground portion 210 and the ground conductor layer 201 are formed. The coaxial resonator engagement part 109 is brought into close contact, and the outer conductor layer 20, the ground conductor layer 201, the center conductor ground part 210, the outer conductor layer 122 in the sealed insulator, the coaxial cable connection part 50, and the housing 70 are electrically connected. It will be in the state.
The bottom surface of the coaxial resonator base portion insertion hole sealing insulator 12 is connected to the outer conductor layer 122 in the sealing insulator in order to ensure conduction between the outer conductor layer 122 in the sealing insulator and the center conductor grounding portion 210. A metal layer may be formed.

  Next, as shown in FIG. 9, the high-frequency plasma ignition device 1 is accommodated in the plug hole PH of the internal combustion engine EG, screwed and fixed to the cylinder head SH via the gasket 603, and the coaxial cable 41 is connected to the coaxial connector portion 40. Are connected to the coaxial resonator 23 and the high-frequency oscillation circuit of the ignition energy supply control device 90, and the connector cap 800 of the high voltage input unit 80 is attached to the high voltage electrode terminal unit 301 to connect the high voltage electrode 30 to the ignition energy. The high voltage power supply circuit of the supply control device 90 is connected.

If the high-frequency MW is input to the center conductor 21, leakage of the high-frequency MW can be prevented, a resonance state can be formed in the resonator cavity 22, and a strong electric field can be generated at the tip of the center conductor shaft portion 211. 20, the ground conductor layer 201 is not necessarily formed on the entire surface of the resonator cavity section 110 and the coaxial resonator locking portion 109.
Therefore, as some modified examples of the high-frequency plasma ignition device 1 of the present invention, the insulators 10a to 10f, which are the main parts shown in FIGS. 10 (a) to 10 (f), will be described.
In addition, since the same code | symbol is attached | subjected about the structure similar to the said embodiment, description is abbreviate | omitted.
As shown in FIGS. 4A and 4B, the outer conductor layers 20a and 20b and the ground conductor layers 201a and 201b may be formed in a mesh shape.
As shown in FIG. 4C, a large number of open holes may exist in the outer conductor layer 20c and the ground conductor layer 201c.
As shown in FIG. 4D, the outer conductor layer 20d and the ground conductor layer 201d may be formed in a staggered pattern.
As shown in this figure (e), the outer conductor layer 20e formed with a constant width in the direction orthogonal to the longitudinal axis direction of the insulator 10e is formed so as to form a horizontal stripe pattern along the axial direction at regular intervals. Also good. As shown in this figure (f), the outer conductor layer 20e formed with a constant width in a direction parallel to the longitudinal axis direction of the insulator 10f is formed so as to form a vertical stripe pattern along the circumferential direction at regular intervals. Also good.
In these modifications, the outer conductor layers 20a to 20f may be modified as appropriate, for example, by adding a conductor layer that crosses in the axial direction or the circumferential direction in order to ensure high-frequency transmission.

With reference to FIG. 11, a high-frequency plasma ignition device 1g according to a second embodiment of the present invention will be described. The present embodiment is different from the above embodiment in that an outer conductive layer body cutout portion 202 is provided in which a part of the outer conductor layer 20g is removed particularly at a position close to the high-voltage electrode discharge portion 323.
In the present embodiment, since the outer conductor layer 20 at a position close to the high-voltage electrode discharge part 323 is partially removed, a high voltage HV is applied to the high-voltage electrode 30 in addition to the same effects as in the above-described embodiment. Sometimes, discharge is not reliably performed between the outer conductor layer 20g and the high-voltage electrode discharge part 323, but the discharge is reliably performed between the tip of the central conductor 21 and the high-voltage electrode discharge part 323, so that plasma is generated in a stable state. be able to. Therefore, a more reliable high-frequency plasma ignition device 1g can be realized.
Note that the outer conductor layer notch 202 may be formed by masking in advance to form the outer conductor layer 20g, or a position close to the high-voltage electrode discharge part 323 after the normal outer conductor layer 20 is formed. The outer conductor layer cutout 202 may be formed by removing a part of the outer electrode layer. Furthermore, this embodiment can be combined with other embodiments.

With reference to FIG. 12, a high-frequency method plasma ignition device 1h according to a third embodiment of the present invention will be described.
In the above embodiment, the configuration in which the center conductor grounding portion 210 is locked to the coaxial resonator locking portion 109 that is reduced in diameter from the coaxial resonator grounding portion insertion hole 108 to the resonator cavity partitioning hole 110 has been described. In the embodiment, as shown in (a), as the insulator 10h, a coaxial resonator grounding portion insertion hole 108h is formed to have a diameter smaller than that of the resonator cavity partitioning hole 110 in FIG. A coaxial resonator locking portion 109h is provided that is reduced in diameter so as to be smaller than the insertion hole 108h and locks the center conductor grounding portion 210h. Further, as shown in FIG. A ground portion conductor layer 201h is formed on the surface of the base end side of the stop portion 109h so as to be electrically connected to the center conductor ground portion 210h. Further, the inner peripheral surface of the center conductor insertion hole 111 and the distal end side of the coaxial resonator locking portion 109h Located at resonance Also forms a ground conductor layer 203 connected to the ground conductor layer 201h on the surface of the resonator cavity bottom 112 defining the cavity 22.
According to the present embodiment, since the coaxial resonator engagement portion 109h is formed to have a diameter reduced toward the inside, in addition to the same effect as the above-described effect, the insulator large diameter portion 101h of the insulator 10; The outer diameter of the insulator small diameter portion 102 can be reduced, and the screw portion 702h can be downsized.

With reference to FIG. 13, the high-frequency plasma ignition device 1i in the 4th Embodiment of this invention is demonstrated.
According to the present invention, since the insulator 10 and the housing 70 are arranged concentrically, as shown in the present embodiment, as the insulator 10h and the housing 70i, a housing lower portion 701i and an insulator small diameter portion 102i are provided. It is also possible to easily adjust the heat value of the plug by enlarging or reducing the gas pocket GP therebetween.
On the other hand, in the conventional high-frequency plasma ignition device 1z, since the insulator 10z is disposed at a position eccentric to the housing 70z, a large deviation occurs in the heat capacity of the portion exposed to the combustion chamber of the internal combustion engine. Therefore, it is not always easy to adjust the heat value of the plug. Therefore, according to the present invention, more stable ignition can be realized.

Here, with reference to FIG. 14, FIG. 15, the problem of the conventional high frequency plasma ignition apparatus 1z shown as a comparative example is explained in full detail. In addition, in order to make contrast with this invention easy, the same code | symbol was attached | subjected about the same structure and z was attached | subjected as a branch number to the corresponding code | symbol about a different point.
In the conventional high-frequency plasma igniter 1z, high-voltage electrode 30, while being held by the insulator 10z formed in a substantially cylindrical shape, the insulator central axis CL ₁₀ which is eccentric to one side from the center axis CL ₁ of the housing 70z The insulator locking portion 705z and the housing caulking portion 708z are interposed via sealing members 600z, 601z, and 602z in which the insulator diameter large portion 101z provided in the middle of the insulator 10z is formed in a substantially annular shape. And are sandwiched from above and below.
Further, the center conductor 21 constituted by the center conductor grounding portion 210 and the center conductor shaft portion 212 is sandwiched between the housing 70 and the housing 71 and partitioned inside the housing lower half portion 71. A coaxial resonator 23z is formed by using the resonator cavity 22z and a part of the housing 71 as the outer conductor 20z.
A high-frequency conductor insertion hole 709z is formed in the housing 70z, the center conductor 400 is inserted through the dielectric layer 401, and the high-frequency introduction portion 213 located at a predetermined height from the center conductor grounding portion 210 of the center conductor central shaft 212. It is connected.
In the conventional high-frequency plasma ignition device 1z, since a part of the housing lower half 71 is used to form the outer conductor 20z, a thickness of a certain value (for example, 1 mm) or more is required. It was difficult to make the size of the portion 712z M14 or less.
In addition, as shown in FIG. 15, the substantially cylindrical insulator 10z that covers the central electrode 30z to which a high voltage is applied is provided at a position that is eccentric with respect to the central axis of the high-frequency plasma ignition device 1z. When the high-frequency plasma ignition device 1z is tightened on the cylinder head SH of the internal combustion engine E / G, if a force greater than an appropriate torque is applied, the metal housings 70z and 71z bend, and the housing 70z is locked with an insulator. the locked a diameter change section 104z in section 705z as a fulcrum, with respect to a direction perpendicular to the central axis of the insulator 10z, acts and the moment M ₂ of the moment M ₁ and reverse screwing direction, the diameter change It has been found that there is a possibility that a crack is generated in the portion 104z and the small diameter portion 102z of the insulator 10z falls out to the combustion chamber CMB side.
In particular, as shown in this figure (c), the rotational moment M ₂ generated by the reaction force received when the housing screw part 712 is fastened to the cylinder head SH is the lower half part (small diameter) of the insulator 10z extending in a long axis shape. Since the distance to the insulator diameter changing portion 104z serving as a fulcrum is long even if a small force is applied to the portion 02z), the force received by the lower half side surface of the insulator 10z from the housing 70z becomes a large moment, and the insulator 10z It is presumed that this will act on the diameter changing portion 104z and cause cracks.

The present invention is not limited to the above embodiment, and the cavity of the coaxial resonator is defined in a part of the insulator for insulatingly holding the high-voltage electrode, and the high-voltage electrode is formed by a housing that covers the outer periphery of the insulator. As long as it does not contradict the gist of the present invention in which the tip portion and the tip portion of the coaxial resonator are exposed and fixed in the combustion chamber of the internal combustion engine, they can be changed as appropriate.
For example, in the embodiment described above, the coaxial resonator grounding portion insertion hole 108 for inserting the coaxial resonator grounding portion 211 into the insulator 10 is formed, and the center conductor 21 is inserted from the base end side of the insulator 10. Although the center conductor grounding portion 211 is locked to the coaxial resonator locking portion 109, the coaxial resonator grounding portion insertion hole 108 is not provided, and the upper end of the resonator cavity partitioning hole 108 is formed in the outer diameter direction. A substantially annular groove having a slightly enlarged diameter is provided in place of the coaxial resonator locking portion 109, and the center conductor grounding portion 211 is formed so as to be elastically deformable in the radial direction. It may be inserted from the front end side of 108 and elastically expanded in the above-mentioned annular groove to lock the center conductor grounding portion 211. However, in such a configuration, care must be taken so that the center conductor grounding portion does not come off from the locking portion due to external vibration.

DESCRIPTION OF SYMBOLS 1 High frequency plasma ignition apparatus 10 Insulator 100 Insulator head 101 Insulator large diameter part 102 Insulator small diameter part 103 Insulator large diameter upper surface part 104 Insulator diameter changing part 105 High voltage electrode stem insertion hole 106 High voltage electrode locking part 107 High-voltage electrode middle shaft insertion hole 108 Coaxial resonator grounding portion insertion hole 109 Coaxial resonator locking portion 110 Resonator cavity section hole 12 Coaxial resonator base portion insertion hole Sealing insulator 120 Sealing insulator base 121 High-frequency conductor insertion hole 122 Outer conductor layer 20 in the sealing insulator Outer conductor layer 201 Ground conductor layer 21 Center conductor 211 Center conductor ground section 212 Center conductor shaft section 213 High-frequency conductor connecting section 22 Resonator cavity section 23 Coaxial resonator
30 High Voltage Electrode 301 High Voltage Electrode Input Terminal Section 302 High Voltage Electrode Stem 31 Conductive Adhesive Layer (Miscellaneous Resistance Layer)
320 High-voltage electrode middle shaft portion 321 High-voltage electrode locking portion 322 High-voltage electrode bent portion 323 High-voltage electrode discharge portion 40 Coaxial connector 400 Center conductor 401 Dielectric layer 41 Coaxial cable 410 Center conductor 411 Dielectric layer 412 Outer body network assembly wire 413 Insulation coating 414 Coaxial Connector 50 Coaxial connector fixing part 500 Connector fixing base 501 Connector mounting hole 502 Insulator insertion hole 600, 601, 602 Sealing member 603 Gasket 70 Housing part 700 Housing boss part 701 Housing lower part 702 Small diameter part insertion hole 703 Housing upper part 704 Large diameter Part insertion hole 705 Insulator locking part 706 Housing hexagon part 707 Housing screw part 708 Housing caulking part 80 High voltage input part 800 High voltage connector cap 810 High voltage input terminal 811 High voltage supply harness 90 Ignition energy Gi supply control part IGt Ignition signal HV High voltage MW High frequency

JP 2010-96109 A

Claims (4)

Ignition energy supply control device having a high-frequency power source that oscillates a high frequency and a high-voltage power source that applies a high voltage, an inner conductor, a predetermined cavity around the inner conductor, and an outer conductor arranged coaxially A high frequency is input from the high frequency power source to the coaxial resonator provided to increase the electric field strength at the tip of the inner conductor, and a high voltage is applied to the high voltage electrode from the high voltage power source to the tip side of the high voltage electrode. A high-frequency plasma ignition device that performs an electric discharge between a discharge portion positioned and a front end portion of the central conductor of the central conductor, and ignites an internal combustion engine with a gas around the front end of the inner conductor as a high energy plasma state. And
The cavity of the coaxial resonator is partitioned into a part of the insulator for insulatingly holding the high-voltage electrode, and the tip of the high-voltage electrode and the tip of the coaxial resonator are covered by a housing that covers the outer periphery of the insulator. A high-frequency plasma ignition device characterized by being exposed and fixed in the combustion chamber of the internal combustion engine.   The coaxial is formed by an outer conductor layer made of a metal film covering all or part of the surface of the inner peripheral wall of the resonator cavity section partitioned inside the insulator, and an inner conductor placed at the center of the resonator cavity section. The high-frequency plasma ignition device according to claim 1, wherein the resonator is configured.   3. The high-frequency plasma ignition device according to claim 1, wherein the outer conductor layer has a thickness of 10 μm or more and 100 μm or less. Ignition energy supply control device having a high-frequency power source that oscillates a high frequency and a high-voltage power source that applies a high voltage, an inner conductor, a predetermined cavity around the inner conductor, and an outer conductor arranged coaxially A high frequency is input from the high frequency power source to the coaxial resonator provided to increase the electric field strength at the tip of the inner conductor, and a high voltage is applied to the high voltage electrode from the high voltage power source to the tip side of the high voltage electrode. Manufacture of a high-frequency plasma ignition device that discharges between a discharge portion positioned and a tip of the center conductor of the center conductor, and ignites an internal combustion engine with a gas around the tip of the inner conductor as a high energy plasma state A method,
Insulator that forms an insulator having a resonator cavity partition hole on the inside using at least an insulating heat-resistant material by any one of pressure molding, HIP molding, SIP molding, injection molding, or extrusion molding Forming process;
The inner peripheral surface of the cavity hollow section hole and the surface of the resonator locking portion are plated, CVD (chemical vapor deposition), PVD (physical vapor deposition) using a conductive material having high heat resistance. The outer conductor layer forming step of forming the outer conductor layer by any one of vacuum deposition, metal foil sticking, printing, direct bonding,
A high frequency device comprising: an assembly in which the insulator is concentrically disposed in a housing formed of a metal material in a substantially cylindrical shape, and caulking and fixing via a predetermined sealing member; A method for manufacturing a plasma ignition device.

Images