JP2005317514A - Igniting electrode - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an igniting electrode which is used for a fuel reforming device that forms a reformed gas containing hydrogen and of which airtightness is high. <P>SOLUTION: The igniting electrode 1 is provided with the cylindrical main body fittings 3, a cylindrical insulating ceramics member 7 penetrated through a through-hole 5 of the main body fittings 3, and the rod-shaped center electrode 11 penetrated through the through-hole 9 of the insulating ceramics member 7. At the rear end side of the insulating ceramics member 7, a washer-shaped member is outwardly-fitted into the outer peripheral face of the center electrode 11, and the washer-shaped member is brazing-bonded and joined to the outer peripheral face of the center electrode 11 and the rear end face of the insulating ceramics member 7. On the other hand, at the end side of the main body fittings 3, a cylindrical member with a flange is outwardly-fitted into the insulating ceramics member 7. This cylindrical member with the flange is brazing-bonded and joined to the outer peripheral face of the insulating ceramics member 7 and the rear end face 15 of the main body fittings 3. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an ignition electrode used in a fuel reformer (reformer) that generates reformed gas containing hydrogen by reforming a reforming fuel (reforming raw fuel) containing, for example, hydrocarbons. .

  Conventionally, a reformer has a combustor (or a combustion chamber) that burns reformed raw fuel in order to burn reformed raw fuel containing hydrocarbons to generate reformed gas containing hydrogen, and combustion. A reformer (or reforming reaction section) or the like that is disposed downstream of the reactor and reforms the fuel gas with a catalyst has been disposed.

  In the combustor, an ignition device is used for ignition when the reformed raw fuel is combusted, and a spark plug or a glow plug is used as the ignition device (Patent Document 1). 2, 3).

This type of ignition device has a structure in which a rod-shaped center electrode is inserted into a cylindrical ceramic member. For example, in a spark plug, the center electrode and the ceramic member are integrated by a caulking method using powder filling. Has been. For example, in the glow plug, the center electrode and the ceramic member are integrated by interference fit fitting (see Patent Document 4).
JP 2002-87802 A (page 3, FIG. 1) JP 2003-192307 A (page 4, FIG. 2) JP 2003-54905 A (page 4, FIG. 1) JP 2002-364842 A (page 3, FIG. 1)

  However, when the above-described ignition device is used for the reformer, there is a problem that the conventional ignition device is manufactured by, for example, interference fit fitting or the like, which is not necessarily sufficient in terms of airtightness. .

  In other words, when the gas tightness of the ignition device itself, for example, the airtightness on the outer peripheral side of the center electrode or the like is not sufficient, it affects the air-fuel ratio in the combustor and the efficiency of gas reforming is reduced. Therefore, improvement in the ignition device used in the reformer has been desired.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide an ignition electrode with high airtightness.

  (1) The invention of claim 1 is a cylindrical metal shell, a cylindrical insulating ceramic member that is inserted through the through hole of the metal shell, and a rod-like material that is inserted into the through hole of the insulating ceramic member. An ignition electrode comprising a center electrode, wherein the ignition electrode ignites by performing discharge between the tip side of the center electrode and an electrode other than the ignition electrode, on the rear end side of the insulating ceramic member The gist of the ignition electrode is that the insulating ceramic member and the central electrode are integrated by brazing so as to hermetically seal a gap between the insulating ceramic member and the central electrode.

  In the present invention, the insulating ceramic member and the center electrode are brazed and joined (for example, directly or via a first intermediate member such as a washer-like member) to hermetically seal the gap between the insulating ceramic member and the center electrode. ing.

  Therefore, since the airtightness in the axial direction of the ignition electrode is improved, when this ignition electrode is mounted on, for example, the combustor of the reformer, it is possible to suppress fluctuations in the air-fuel ratio due to gas leakage. Therefore, there is an effect that the efficiency of gas reforming is improved. Moreover, since leakage of combustible gas can be suppressed, there also exists an advantage that safety | security increases.

  (2) The invention of claim 2 is characterized in that a cylindrical metal shell, a cylindrical insulating ceramic member inserted through the through hole of the metal shell, and a rod-like metal inserted through the through hole of the insulating ceramic member. A center electrode, and an ignition electrode that ignites by performing discharge between the front end side of the center electrode and an electrode other than the ignition electrode, on the rear end side of the metal shell The gist of the ignition electrode is characterized in that the insulating ceramic member and the metallic shell are integrated by brazing so as to hermetically seal a gap between the insulating ceramic member and the metallic shell.

  In the present invention, the insulating ceramic member and the metal shell are brazed and joined (for example, directly or via a second intermediate member such as a flanged tubular member), so that the gap between the insulating ceramic member and the metal shell is reduced. Airtight.

  Therefore, since the airtightness in the axial direction of the ignition electrode is improved, when this ignition electrode is mounted on, for example, the combustor of the reformer, it is possible to suppress fluctuations in the air-fuel ratio due to gas leakage. Therefore, there is an effect that the efficiency of gas reforming is improved. Moreover, since leakage of combustible gas can be suppressed, there also exists an advantage that safety | security increases.

  (3) The invention of claim 3 is a cylindrical metal shell, a cylindrical insulating ceramic member that is inserted through the through hole of the metal shell, and a rod-like material that is inserted into the through hole of the insulating ceramic member. An ignition electrode comprising a center electrode, wherein the ignition electrode ignites by performing discharge between the tip side of the center electrode and an electrode other than the ignition electrode, on the rear end side of the insulating ceramic member The insulating ceramic member and the center electrode are integrated by brazing so as to hermetically seal the gap between the insulating ceramic member and the center electrode, and at the rear end side of the metal shell, the insulation The gist of the ignition electrode is that the insulating ceramic member and the metallic shell are integrated by brazing so as to hermetically seal a gap between the ceramic member and the metallic shell.

  As in the first aspect of the present invention, the insulating ceramic member and the center electrode are brazed and joined (for example, directly or via a first intermediate member such as a washer-like member) to form an insulating ceramic. The gap between the member and the center electrode is hermetically sealed, and the insulating ceramic member and the metal shell (for example, directly or via a second intermediate member such as a flanged tubular member) as in the invention of claim 2. B) Brazing and joining to seal the gap between the insulating ceramic member and the metal shell.

  Therefore, the airtightness in the axial direction of the ignition electrode is further improved as compared with the inventions of the first and second aspects. Therefore, when this ignition electrode is mounted on, for example, the combustor of the reformer, the leakage of gas As a result, the air-fuel ratio can be effectively suppressed from fluctuating. Therefore, there is an effect that the efficiency of gas reforming is further improved. Moreover, since leakage of combustible gas can be suppressed, there is also an advantage that safety is further enhanced.

  (4) The invention of claim 4 is characterized in that the insulating ceramic member and the center electrode are brazed and joined via a metal first intermediate member fitted on the center electrode. The gist of the ignition electrode according to 1 or 3.

  In the present invention, the insulating ceramic member and the center electrode are brazed using a first intermediate member (for example, a washer-like member). That is, the insulating ceramic member and the first intermediate member are brazed via the first intermediate member, and the first intermediate member and the center electrode are brazed.

Therefore, even when the shape and material of the insulating ceramic member and the center electrode are limited,
By using the first intermediate member (which can adopt a shape and material suitable for brazing), brazing can be performed easily and reliably. Thereby, there exists an effect that airtightness improves further.

(5) The invention according to claim 5 is characterized in that the first intermediate member is a washer-like member.
The present invention exemplifies a preferable shape of the first intermediate member.

  (6) In the invention of claim 6, the washer-like member is brazed to the rear end side end surface of the insulating ceramic member on the main surface side, and on the inner peripheral surface of the center electrode, The gist of the ignition electrode according to claim 5, wherein the ignition electrode is brazed to the outer peripheral surface.

  The present invention exemplifies the brazing position in the washer-like member. By brazing at this position, the brazing can be performed easily and reliably, and the airtightness can be improved.

  (7) The invention according to claim 7 is characterized in that the insulating ceramic member and the metal shell are brazed and joined via a metal second intermediate member externally fitted to the insulating ceramic member. The gist of the ignition electrode according to Item 2 or 3.

  In the present invention, the insulating ceramic member and the metal shell are brazed using a second intermediate member (for example, a cylindrical member with a flange). That is, the insulating ceramic member and the second intermediate member are brazed using the second intermediate member, and the second intermediate member and the metal shell are brazed.

  Therefore, even when the shape and material of the insulating ceramic member and the metal shell are limited, the second intermediate member (which can adopt a shape and material suitable for brazing) can be brazed easily and reliably. Can do. Thereby, there exists an effect that airtightness improves further.

(8) The invention according to claim 8 is characterized in that the second intermediate member is a cylindrical member with a flange, and the ignition electrode according to claim 7 is characterized.
The present invention exemplifies a preferable shape of the second intermediate member. That is, by using a member having a shape in which the flange projects from the outer peripheral surface of the cylindrical member, the brazed surface is widened, so that there is an advantage that jointability (and hence airtightness) is improved.

  (9) According to the ninth aspect of the present invention, the cylindrical member with the flange is brazed to the rear end side end surface of the metal shell on the main surface side of the flange, and the inner peripheral surface of the cylindrical portion The gist of the ignition electrode according to claim 8, wherein the ignition electrode is brazed to the outer peripheral surface of the insulating ceramic member.

  The present invention exemplifies a brazing position in a flanged cylindrical member, and brazing can be easily and reliably performed at this position to improve airtightness. .

  (10) In the invention of claim 10, the ignition electrode according to claim 8 or 9, wherein the flanged tubular member is accommodated in a recess provided on a rear end side of the metal shell. The gist.

The present invention exemplifies the arrangement of the flanged cylindrical member, and the ignition electrode is compacted without projecting to the outside by housing the flanged cylindrical member in the recess on the rear end side of the metal shell. Can be.

  (11) The invention according to claim 11 is characterized in that the ignition electrode ignites the reformed raw fuel in a reformer that generates reformed gas from the reformed raw fuel. The gist of the ignition electrode according to claim 1.

  The present invention illustrates the use of an ignition electrode. When this ignition electrode is mounted on the combustor of the reformer, it is possible to effectively suppress fluctuations in the air-fuel ratio due to gas leakage, and thus the gas reforming efficiency is further improved. . Moreover, since leakage of combustible gas can be suppressed, there is also an advantage that safety is further enhanced.

  The ignition electrode of each claim is different from, for example, a spark plug that discharges between its own pair of electrodes, and discharges between the center electrode of the ignition electrode itself and an electrode provided separately from the ignition electrode. For example, the reforming raw fuel is ignited.

  The counterpart electrode that forms a pair with the center electrode includes, for example, an electrode provided in a device (for example, a reforming device) to which an ignition electrode is attached. If ignition of gas etc., such as fuel (for example, reforming raw fuel) is possible, there will be no limitation in particular.

  Next, an example (example) of the best mode of the present invention will be described.

  In this embodiment, a reformer for a fuel cell (hereinafter simply referred to as reformer) that generates reformed gas containing hydrogen by reforming a hydrocarbon-based reformed raw fuel such as methanol for use in a fuel cell. For example, an ignition electrode for a reformer (hereinafter simply referred to as an ignition electrode) used in the combustor (or combustion chamber) is used.

a) First, the structure of the ignition electrode of the present embodiment will be described.
As shown in FIGS. 1 and 2, the ignition electrode 1 of the present embodiment is a rod-like electrode that ignites on the tip side, and mainly includes a cylindrical metal shell 3 and a through hole 5 of the metal shell 3. And a cylindrical insulating ceramic member 7 inserted into the insulating ceramic member 7 and a rod-shaped center electrode 11 inserted into the through hole 9 of the insulating ceramic member 7.

Among these, the metal shell 3 is a cylindrical member having an outer diameter of φ20 mm made of JIS SUS316L, and has a through hole 5 having an inner diameter of φ13 mm at the center of the shaft.
A rear concave portion 13 having a larger diameter (φ17.5 mm) than the through hole 5 and notched in a disk shape is provided on the rear end side (upper side in FIG. 1) of the through hole 5. The end face 15 is plated with Ni.

  In addition, an annular cylindrical portion 17 that projects downward along the outer periphery is provided at the lower end on the outer peripheral side of the metal shell 3. Note that the ignition electrode 1 is fixed to the combustor by welding the lower end of the annular cylindrical portion 17 and the side wall of the combustor (which is an attachment target).

  The insulating ceramic member 7 is a columnar member made of alumina and having an outer diameter φ10 mm (annular cylindrical portion 17 portion) × inner diameter φ2.5 mm × length 55 mm, and the front end side and the rear end side are both ends of the metal shell 3. Protruding from.

  Corrugations 19 and 21 are provided in a corrugated manner on the front end side and rear end side of the insulating ceramic member 7 in order to increase the edge distance. Further, between both the corrugations 19 and 21, an annular base portion 23 that protrudes annularly in the radial direction is provided.

  The center electrode 11 is a columnar member having an outer diameter of φ2 mm × length of 68 mm made of a high-temperature heat-resistant electrothermal alloy (trade name: YSS-Esit) based on Fe—Cr—Al. Projecting from both ends of the insulating ceramic member 7. Note that Ni plating is applied to a part of the rear end side of the center electrode 11 (where a washer-like member 31 described later is disposed).

  In particular, in this embodiment, a Kovar washer-like member 31 having a through-hole 33 is disposed on the rear end side of the insulating ceramic member 7 as shown in FIG. That is, an annular plate-shaped washer member 31 having an outer diameter of 5 mm, an inner diameter of 2.1 mm, and a thickness of 0.3 mm is externally fitted to the center electrode 11.

  As shown in an enlarged view in FIG. 4, the washer member 31 is brazed to the outer peripheral surface 35 of the center electrode 11 and the rear end surface 37 of the insulating ceramic member 7 with a brazing material (JIS BAg-8). It is joined.

  That is, the washer-shaped member 31 is brazed to the inner peripheral surface 39 of the through-hole 33 and the outer peripheral surface 35 of the center electrode 11, and the front end side (front end main surface 41) of the main surface and insulating ceramics. The rear end surface 37 of the member 7 is brazed and joined.

  Thereby, the washer-shaped member 31, the center electrode 11, and the insulating ceramic member 7 are joined and integrated, and the gap between the center electrode 11 and the insulating ceramic member 7 is completely hermetically sealed.

  On the other hand, on the rear end side of the metal shell 3, as shown in FIG. 3B, a Kovar flanged cylindrical member 43 having an outer diameter of φ17 mm, an inner diameter of φ10.1 mm, and a height of 5 mm is disposed. That is, a flanged tubular member 43 having a plate thickness of 0.3 mm, which includes a tubular portion 47 having a through-hole 45 and a flange portion 49 projecting perpendicularly from one axial end of the tubular portion 47 outward. The insulating ceramic member 7 is externally fitted.

  As shown in FIG. 5, the flanged cylindrical member 43 is made of brazing material (JIS BAg-8), and the rear surface of the insulating ceramic member 7 (that is, the outer peripheral surface of the annular base 23) 51 and the back of the metal shell 3. It is brazed and joined to the rear end surface 15 of the recess 13 without a gap.

  That is, the flanged tubular member 43 is fitted into the through hole 5 so as to close the through hole 5 with the tubular portion 47 facing the distal end side. The inner peripheral surface 53 of the tubular portion 47 and the outer peripheral surface 51 of the insulating ceramic member 7 are brazed and joined, and the front end side (front end main surface 55) of the main surface of the flange portion 49 and the rear recess 13 are formed. The rear end face 15 is brazed and joined.

  Thereby, the flanged tubular member 43, the insulating ceramic member 7 and the metallic shell 3 are joined and integrated, and the gap between the insulating ceramic member 7 and the metallic shell 3 is completely hermetically sealed.

b) Next, the manufacturing procedure of the ignition electrode 1 of the present embodiment will be described.
First, each member of the metal shell 3, the insulating ceramic member 7, the center electrode 11, the washer member 31, and the flanged tubular member 43 is manufactured according to a standard method.

  Among these, the metal shell 3 is then subjected to Ni plating to improve the brazing property on the rear end surface 15 of the recess 13 (the surface to which the flange portion 49 of the flanged tubular member 43 is joined) 15.

  The insulating ceramic member 7 is made of alumina as a main component (for example, 92% by weight) with some auxiliary materials added, and is an alumina-based sintered body fired at about 1600 ° C. in a tunnel kiln, for example.

  Of the outer peripheral surface 51 of the insulating ceramic member 7, a portion to which the tubular portion 47 of the flanged tubular member 43 is joined and a rear end surface 37 to which the washer-like member 31 of the insulating ceramic member 43 is joined are: In order to improve brazing property, a metallized layer (not shown) is formed by a well-known Mo-Mn method. Ni plating is also applied to the surface of the metallized layer.

Ni plating is applied to a part of the rear end side of the center electrode 11 in order to improve brazing (when the washer-like member 31 is joined).
The entire surface of the washer-like member 31 and the flanged tubular member 43 is also plated with Ni in order to improve brazing.

  Next, the insulating ceramic member 7 in a state where the flanged tubular member 43 is externally fitted is inserted into the through hole 5 of the metal shell 3. Note that the insulating ceramic member 7 may be inserted in a state where the flanged cylindrical member 43 is fitted in the concave portion 17 of the metal shell 3.

  At the same time, the center electrode 11 fitted with the washer-like member 31 is inserted into the through hole 9 of the insulating ceramic member 7. The washer-like member 31 may be externally fitted to the center electrode 11 after the center electrode 11 is fitted into the through hole 9 of the insulating ceramic member 7.

  Then, the metal shell 3, the insulating ceramic member 7, the center electrode 11, the washer member 31, and the flanged tubular member 43 are assembled and brazed while being fixed by a jig (not shown).

  Specifically, a brazing material is disposed in the vicinity of the washer-shaped member 31, or a brazing material foil is disposed between the main surface side of the washer-shaped member 31 and the insulating ceramic member 7. Further, the brazing material is disposed in the vicinity of the tubular portion 47 of the flanged tubular member 43 and the brazing material is disposed in the vicinity of the flange portion 49 of the flanged tubular member 43 (or the flanged tubular member 43. The brazing material foil is disposed between the flange portion 49 and the rear end surface 15 of the metal shell 3. And in this state, it brazes by heating to 800-830 degreeC, for example in a reducing atmosphere, and cooling after that.

  Thereby, the front end side main surface 41 of the washer-like member 31 and the rear end surface 37 of the insulating ceramic member 7 are joined, and the inner peripheral surface 39 of the washer-like member 31 and the outer peripheral surface 35 of the center electrode 11 are joined. Thereby, both members are integrated in a state where the gap between the center electrode 11 and the insulating ceramic member 7 is hermetically sealed.

  Further, the front-end-side main surface 55 of the flange portion 49 of the flanged tubular member 43 and the rear end surface 15 of the metal shell 3 are joined, and the inner peripheral surface 53 of the tubular portion 47 of the flanged tubular member 43 Both members are integrated with each other in a state where the outer peripheral surface 51 of the insulating ceramic member 7 is joined and thereby the gap between the insulating ceramic member 7 and the metal shell 3 is hermetically sealed.

c) Next, a reformer in which the ignition electrode 1 of the present embodiment is used will be described.
As shown in FIG. 6, the reformer 61 in which the ignition electrode 1 is used includes an evaporator 63 to which a reforming raw fuel (for example, fuel containing methanol) and combustion air are supplied, and a reforming catalyst layer 65. And a charged reformer 67.

In the evaporator 63, the ignition electrode 1 is arranged so that the tip end side thereof protrudes into the combustion chamber 69, and the reformed raw fuel atomized by the combustion air is ignited by the ignition electrode 1 ( Ignite). That is, a predetermined voltage is applied between the ignition electrode 1 and a counter electrode (not shown) provided in the combustion chamber 69, and thereby, the reformed raw fuel is generated by a discharge generated between both electrodes. Is ignited.

  Then, by this ignition, methanol partially burns in the combustion chamber 69 and generates heat, so that the remaining methanol and water are evaporated to become high-temperature steam having a temperature higher than the temperature suitable for reforming.

Thereafter, the high-temperature steam is supplied with reforming air, sent to the reformer 67, and reformed by the catalyst layer 65 in the reformer 67.
d) Next, an experimental example performed to confirm the effect of the present embodiment will be described.

  As shown in FIG. 7, the ignition electrode 1 of this embodiment is inserted into the through hole 73 of the container 71 of a commercially available helium leak detector (manufactured by Veeco), and the lower end of the annular cylindrical portion 17 and the upper edge of the through hole 73. The ignition electrode 1 is fixed to the container 71 by welding the part 75.

  Next, the inside of the container 71 is evacuated, and in a vacuum state (pressure: 0.1 to 1 Pa), He gas that is a probe gas (leakage detection gas) is blown around the container 71. At that time, the amount of He gas entering from the outside to the inside of the container 71 including the ignition electrode 1 was measured using a helium leak detector.

As a result, it can be seen that the amount of He leakage is as very low as 1 × 10 ⁻⁹ Pa · m ³ / sec or less, and is extremely excellent in airtightness.
Similarly, when a gas glow test was conducted using a commercially available glow plug (manufactured by Nippon Special Ceramics Co., Ltd.), that is, a glow plug that was not hermetically sealed by brazing as in this example, the amount of He leakage was measured. Was about 1 × 10 ⁻⁴ to 1 × 10 ⁻³ Pa · m ³ / sec, and the airtightness was lower than that of this example.

  e) In this way, the ignition electrode 1 of the present embodiment is brazed between the center electrode 11 and the insulating ceramic member 7 via the washer-like member 31 without any gaps. Since the metal shell 3 is brazed without gaps through a flanged tubular member 43, the airtightness in the axial direction of the ignition electrode 1 is extremely high.

  Thereby, when the ignition electrode 1 is attached to the evaporator 63 of the reformer 61, it is possible to prevent the reforming raw fuel from leaking out of the reformer 61. Gas reforming can be performed well. Moreover, since leakage of combustible gas can be prevented, it is excellent also from the viewpoint of safety.

In addition, this invention is not limited to the said Example at all, and it cannot be overemphasized that it can implement with a various aspect in the range which does not deviate from the summary of this invention.
For example, in the above-described embodiment, brazing is performed through a washer-like member or a flanged cylindrical member, but the center electrode and the insulating ceramic member are brazed without using those members, The metal shell may be brazed.

You may change suitably the shape of a washer-like member or a cylindrical member with a flange. For example, a flanged tubular member may be used instead of the washer member, and vice versa.
Furthermore, although the recessed part which accommodates the cylindrical member with a flange was provided in the rear end side of the main metal fitting, it is not necessary to provide a recessed part by reversing the direction of the cylindrical member with a flange or using a washer-like member. On the contrary, you may provide the recessed part which accommodates a washer-like member (or a cylindrical member with a flange used instead of a washer-like member) in the rear-end side of an insulating ceramic member.

  In addition, since the insulating ceramic member is generally difficult to braze, it is desirable to provide a metallized layer, Ni plating or the like according to a conventional method.

It is a front view which shows a partially broken ignition electrode of an example. It is a top view which shows the ignition electrode of an Example. (A) is a perspective view which shows the washer-like member of the ignition electrode of an Example, (b) is a perspective view which shows a cylindrical member with a flange. It is explanatory drawing which fractures | ruptures and expands and shows the joining state of a washer-like member. It is explanatory drawing which fractures | ruptures and expands and shows the joining state of the cylindrical member with a flange. It is explanatory drawing which shows a reforming apparatus. It is explanatory drawing which shows an experiment method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Ignition electrode 3 ... Main metal fitting 5, 9, 33, 45, 73 ... Through-hole 7 ... Insulating ceramic member 11 ... Center electrode 31 ... Washer-like member 43 ... Cylindrical member 61 with a flange 61 ... Reformer

Claims (11)

A cylindrical metal shell,
A cylindrical insulating ceramic member inserted in the through hole of the metal shell,
A rod-shaped center electrode inserted through the through hole of the insulating ceramic member;
With an ignition electrode equipped with
An ignition electrode that ignites by performing discharge between the tip side of the center electrode and an electrode other than the ignition electrode,
The insulating ceramic member and the central electrode are integrated by brazing joint so that a gap between the insulating ceramic member and the central electrode is hermetically sealed at a rear end side of the insulating ceramic member. Ignition electrode. A cylindrical metal shell,
A cylindrical insulating ceramic member inserted in the through hole of the metal shell;
A rod-shaped center electrode inserted through the through hole of the insulating ceramic member;
With an ignition electrode equipped with
An ignition electrode that ignites by performing discharge between the tip side of the center electrode and an electrode other than the ignition electrode,
Ignition characterized in that the insulating ceramic member and the metallic shell are integrated by brazing joint so that the gap between the insulating ceramic member and the metallic shell is hermetically sealed at the rear end side of the metallic shell. electrode. A cylindrical metal shell,
A cylindrical insulating ceramic member inserted in the through hole of the metal shell,
A rod-shaped center electrode inserted through the through hole of the insulating ceramic member;
With an ignition electrode equipped with
An ignition electrode that ignites by performing discharge between the tip side of the center electrode and an electrode other than the ignition electrode,
At the rear end side of the insulating ceramic member, the insulating ceramic member and the center electrode are integrated by brazing so as to hermetically seal a gap between the insulating ceramic member and the center electrode,
Ignition characterized in that the insulating ceramic member and the metallic shell are integrated by brazing joint so that the gap between the insulating ceramic member and the metallic shell is hermetically sealed at the rear end side of the metallic shell. electrode.   4. The ignition electrode according to claim 1, wherein the insulating ceramic member and the center electrode are joined by brazing via a metal first intermediate member fitted around the center electrode. 5.   The ignition electrode according to claim 4, wherein the first intermediate member is a washer-like member.   The washer-like member is brazed to the rear end side end surface of the insulating ceramic member on the main surface side and brazed to the outer peripheral surface of the center electrode on the inner peripheral surface thereof. The ignition electrode according to claim 5.   4. The ignition electrode according to claim 2, wherein the insulating ceramic member and the metallic shell are brazed and joined via a metal second intermediate member fitted around the insulating ceramic member. 5.   The ignition electrode according to claim 7, wherein the second intermediate member is a cylindrical member with a flange.   The flanged cylindrical member is brazed to the rear end surface of the metallic shell on the main surface side of the flange, and the outer peripheral surface of the insulating ceramic member on the inner peripheral surface of the cylindrical portion. The ignition electrode according to claim 8, wherein the ignition electrode is brazed and joined.   The ignition electrode according to claim 8 or 9, wherein the flanged tubular member is accommodated in a recess provided on a rear end side of the metal shell.   11. The ignition electrode according to claim 1, wherein the ignition electrode ignites the reformed raw fuel in a reformer that generates reformed gas from the reformed raw fuel. Ignition electrode.

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