JPH04167387A - Constant voltage discharge tube for ignition device and manufacture thereof - Google Patents

Abstract

PURPOSE:To prevent leaks and the like by providing a small hole or the like through one of metal sealing bodies for blocking both end openings of a hollow tubular envelop, and exhausting air from the hollow portion through the small hole or the like, and sealing an inert gas therein, and then heating and melting a small glass sealing body mounted in the small hole so as to block the hole. CONSTITUTION:Both end openings of a hollow tubular envelope 1 are sealed by welding of sealing glass 10 to a first metal sealing body 4 and a second metal sealing body 7. Next a glass sealing body 9 is mounted in the small hole 6 of the sealing body 4 in such a manner as blocking the small hole and the hollow tubular envelop 1 is set in a sealed container and air is exhausted from the container and air is also discharged from the inside of a hollow portion 3 through the small hole 6 in which the glass sealing body 9 is mounted and an inert gas of predeteremined pressure is sealed in the sealed container after exhaustion and then the inert gas of predeteremined pressure is also sealed in the hollow portion 3 via the small hole 6. When the glass sealing body 9 is heated from outside the container by a high-frequency heating device the sealing body 9 is melted in a very short time and the small hole 6 is blocked by welding of the sealing body 9, whereby a constant voltage discharge tube is completed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a constant voltage discharge tube used in series connection with a spark plug in an ignition system for an internal combustion engine, and a method for manufacturing the same.

Conventional Technology In order to prevent carbon, lead compounds, etc. from adhering to the surface of the insulating porcelain body of the spark plug in the ignition system of an internal combustion engine, which would prevent the required voltage from being obtained at the spark plug electrode, It is known to connect discharge tubes, and the applicant has also developed this type of discharge tube in Japanese Patent Application Laid-Open No. 2002-9427.
This is proposed in Publication No. 8 and others.

FIG. 9 shows a cross-sectional view of the discharge tube according to JP-A-2-94278, in which the openings at both ends of the hollow cylindrical envelope 1 are connected to the metal enclosure 7 to which the main electrode 8 is attached. The hollow part 3 is sealed with a metal sealing body 11 to which the main electrode 5 is attached by welding a sealing glass 10, and an inert gas at a predetermined pressure is filled in the hollow part 3.

The filling and sealing of the inert gas into the hollow portion 3 is achieved by sealing one opening by welding the sealing glass 10 with one of the metal sealing bodies 7 and 11, and sealing the other opening of the hollow cylindrical envelope 1. Place the other metal sealing body in the opening of the container and set it in the sealed container, and after filling the hollow part 3 with inert gas by evacuating the sealed container and filling it with inert gas, seal it. This is done by heating and melting the glass and sealing the other opening of the hollow cylindrical envelope with the other metal sealing body.

Problems to be Solved by the Invention In the above-described inert gas filling method, the inert gas is sealed in a sealed container through an unsealed metal sealing body, and then the sealing glass is heated and melted. Since the opening is sealed with a metal sealing body, a small hole may be formed in a portion of the sealing glass, resulting in problems such as a decrease in manufacturing yield and slow leakage over a long period of time.

This is because the sealing glass must be heated and melted for a relatively long time because it is necessary to seal the entire circumference of the metal sealing body with the sealing glass, and the contact area between the sealing glass and the metal sealing body is small. Since the pressure is large, the pressure inside the hollow part becomes higher than the pressure inside the sealed container during heat welding, and it is thought that the pressure difference creates a hole for gas release in a part of the sealing glass.

Therefore, the present invention provides a constant voltage discharge tube for an ignition device and a method for manufacturing the same, which solves the above problems.

Means for Solving the Problems The constant voltage discharge tube of the present invention has a small hole provided in either one of the metal closures that closes the openings at both ends of a hollow cylindrical envelope, and a hollow After the chamber is evacuated and an inert gas is filled in, the small hole is sealed with a glass sealing body.

Such a constant voltage discharge tube of the present invention is provided on one side of a metal sealing body which seals the openings at both ends of a hollow cylindrical envelope having a hollow portion by welding a sealing glass. The hollow part is evacuated through a small hole attached to the glass, an inert gas is filled into the hollow part through the small hole, and then the small hole is sealed by heating and melting a glass sealing body. It will be done.

Another constant voltage discharge tube of the present invention has a small hole communicating with a hollow part of a hollow cylindrical envelope whose openings at both ends are closed by a metal sealing body, and a small hole communicating with the hollow part of the hollow cylindrical envelope through which the hollow part is evacuated. It has a glass sealing body that seals the small hole after sealing in an inert gas.

In such another constant voltage discharge tube of the present invention, the openings at both ends of the hollow cylindrical envelope are sealed with a metal sealing body by welding a sealing glass, which communicates with the hollow part of the hollow cylindrical envelope. The hollow part is evacuated through a small hole, an inert gas is filled into the hollow part through the small hole, and then the small hole is sealed by heating and melting a glass sealed body.

The hollow part of the hollow cylindrical envelope is evacuated through the small hole of the working metal sealing body or the small hole of the hollow cylindrical envelope, and after filling the hollow part with an inert gas, it is attached to the small hole. The small hole is sealed by heating and melting the glass sealing body, and the glass sealing body may be small enough to seal the small hole. The heating time for the glass sealed body is extremely short, and there are no holes in the glass sealed body, so the manufacturing yield of constant voltage discharge tubes is high, and there is no risk of slow leakage in the long term of constant voltage discharge tubes. Not at all.

Example Hereinafter, the present invention will be explained with reference to drawings of embodiments.

1 to 4 are drawings showing a first embodiment of the constant voltage discharge tube of the present invention, and FIG. 1 is an external view of a hollow cylindrical envelope, in which powder of an insulating material such as ceramic is used. By press molding and sintering or cutting a cylinder made of the same material, a hollow part 3 in which an inert gas is filled and grooves 2 are provided on the periphery of both open ends are made.

FIG. 2(A) is an external view of the first metal sealing body 4 having a small hole 6 to which the first main electrode 5 is attached, and FIG.
is a second metal enclosure 7 to which a second main electrode 8 is attached.
This is an external view of the first main electrode 5, in which a sintered body made by press-molding and sintering one type or mixed powder of tungsten, molybdenum, tantalum, etc. is attached to the tip of a rod-shaped metal body of tungsten, tantalum, etc. The second main electrode 8 is made of a rod-shaped metal such as tungsten or tantalum.

In the constant voltage discharge tube of the present invention, first, as shown in the longitudinal cross-sectional view of FIG. The openings at both ends of the envelope 1 are sealed.

Next, a glass sealing body 9 is attached to the small hole 6 of the first metal sealing body 4 so as to close the small hole, and the hollow cylindrical envelope 1 is set in an airtight container (not shown), and the airtight container is evacuated. As a result, the inside of the hollow part 3 is also evacuated through the small hole 6 to which the glass sealing body 9 is attached, and if an inert gas of a predetermined pressure is filled in the closed container after exhausting, the inside of the hollow part 3 is also evacuated through the small hole 6. An inert gas at a predetermined pressure is then filled.

In this state, when the glass sealed body 9 is heated from outside the closed container using, for example, a known high-frequency heating device, the glass sealed body 9 is melted in an extremely short time, and the small holes 6 are formed as shown in FIG.
As shown in the partial sectional view of (a), the glass sealing body 9 is sealed by welding to complete the constant voltage discharge tube.

FIG. 4(b) is a top view of the completed constant voltage discharge tube.

Note that when the glass sealing body 9 is heated and melted, the previously sealed sealing glass 10 is also heated, but the glass sealing body 9
is small enough to seal the small hole 6, and the time for heating and melting it to seal it is extremely short, so it does not reach the point where the sealing glass 10 is melted.

Furthermore, there is no problem in heating the glass sealed body 9 using the above-mentioned high frequency heating device, but if only the glass sealed body is intensively heated and melted with a light beam from outside the sealed container, heating of other parts can be avoided. This can be done more efficiently with almost no loss.

FIG. 5 is a cross-sectional view showing a second embodiment of the constant voltage discharge tube of the present invention.
2 is provided in a hollow cylindrical envelope 13.

In this embodiment, first, the first main electrode 5 is attached to the first main electrode 5.
After sealing both openings of the hollow cylindrical envelope 13 by welding the sealing glass 10 with the metal sealing body 11 and the second metal sealing body 7 to which the second main electrode 8 is attached, the small The hollow cylindrical envelope 13 is installed by attaching the glass sealing body 9 to the hole 12, setting the hollow cylindrical envelope 13 in a closed container (not shown), evacuating the inside of the closed container, and filling it with inert gas at a predetermined pressure. The hollow part 3 is evacuated through the small hole 12 and filled with inert gas at a predetermined pressure.

Next, the glass sealing body 9 attached to the small hole 12 is heated and melted in the same manner as in the previous embodiment, thereby sealing the small hole 12 and completing the constant voltage discharge tube.

Note that the glass sealing body 9 that closes the small hole 6.12 is the sixth
As shown in FIG.
If one or several grooves 16 are provided across the tip portion 14 and the base portion 15 as shown in FIG.

Conversely, even if one or more protrusions are provided on the glass sealed body 9, exhausting and inert gas filling can be similarly performed smoothly.

FIG. 7 is a partial longitudinal cross-sectional view showing a third embodiment of the present invention, in which a small hole 18 of a hollow cylindrical envelope 17 has a step chamber 19.
The glass sealing body 9 is shaped to fit into this step chamber, and the manufacturing method is not particularly different from the second embodiment, but the glass sealing body 9 is welded and the small holes 18 are formed. When sealed, the glass sealing body does not protrude from the outer surface of the hollow cylindrical envelope and can be flush with the outer surface of the hollow cylindrical envelope.

In the first and second embodiments, the exposed portion of the glass sealing body that seals the small hole on the outer surface of the metal sealant or the outer surface of the hollow cylindrical envelope is extremely small and does not pose a problem in use. Alternatively, if the glass sealing body is completely fitted into the step chamber 19 as in this embodiment, it is preferable in terms of appearance, and the problem that the protruding part of the glass sealing body gets in the way during use can be avoided. You can eliminate all of them.

FIG. 8 shows the groove 21.2 in the small hole 25 of the hollow cylindrical envelope 20.
2, 23, and 24 are provided, and the same figure (a) is a longitudinal cross-sectional view, and the same figure (b) is a partial front view seen from the direction of the arrow.

By providing grooves 21, 22, 23, 24 in the small holes,
When the glass sealed body has the shape shown in Fig. 6 (a), exhaust and filling of inert gas are carried out smoothly through these grooves 21, 22, 23, 24, and as shown in Fig. 6 (b). In the case of the shape, the synergistic effect of the grooves 21, 22, 23, 24 and the groove 16 allows for smoother evacuation and filling of inert gas.

Although four grooves are provided for the small hole 24 in this embodiment, it may be provided at one groove, and the number thereof may be determined as appropriate in conjunction with the size of the groove.

Furthermore, at least one protrusion may be provided instead of the groove, and in the case of this protrusion, exhaust gas and inert gas can be smoothly filled through the gap with the glass sealing body.

Effects of the Invention As described above, the constant voltage discharge tube of the present invention has a metal sealing body that seals the openings at both ends of a hollow cylindrical envelope having a hollow portion during evacuation, filling with inert gas, and sealing. or through a small hole provided in the hollow cylindrical envelope, the hollow part is evacuated and filled with inert gas, and then a small glass sealed body attached to the small hole is heated. Since it is only necessary to melt and seal the small hole, the sealing operation can be performed by heating in an extremely short time, and there is no fear of making holes in the glass sealing body, and the operation is also extremely smooth. can be done.

Furthermore, the constant voltage discharge tube manufactured in this manner has no fear of slow leakage from the glass sealing body in which the small holes are sealed.

[Brief explanation of the drawing]

1 to 4 are drawings showing a first embodiment of the constant voltage discharge tube of the present invention, and FIG. 1 is an external view of a hollow cylindrical envelope;
Figure 2 (a) shows the first main electrode attached to the first main electrode.
Fig. 2(b) is an external view of the second metal sealing body with the second main electrode attached, and Fig. 3 is an external view of the first and second metal sealing bodies. Figure 4 (a) is a cross-sectional view of a hollow cylindrical envelope in which both openings of the hollow cylindrical envelope are sealed with a body.
B) is a top view of the finished product of the constant voltage discharge tube, FIG. 5 is a sectional view showing the second embodiment of the constant voltage discharge tube of the present invention, and FIG. 6 (A) is the constant voltage discharge tube of the present invention. An external view showing one embodiment of a glass sealing body for sealing a small hole provided in a metal sealing body of a tube or a hollow cylindrical envelope, and FIG. 6 (b) shows another example of the same glass sealing body. FIG. 7 is a partial sectional view showing a third embodiment of the constant voltage discharge tube of the present invention, and FIG. 8 (A) shows a fourth embodiment of the constant voltage discharge tube of the present invention. 1 and 8 (b) are a front view seen from the direction of the arrow in FIG. 8 (a), and FIG. 9 is a sectional view of a conventional constant voltage discharge tube for an ignition device. 1.13.17.20...Hollow cylindrical envelope, 3...
Hollow part, 4.11... first metal enclosure, 5,...
First main electrode, 6.12.18.25... Small hole, 7.
...Second metal sealing body, 8...Second main electrode, 9...
・Glass sealing body, 10... Sealing glass, 19... Step chamber, 21.22.23.24... Name of attorney Mizo Patent attorney Akira Kokaji and 2 others listed
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Claims (6)

[Claims] (1) A hollow cylindrical envelope made of an insulating material such as ceramic and having a hollow portion and open at both ends, and a first metal enclosure to which a first main electrode is attached and which closes one of the openings. ,
a small hole provided in the first metal sealing body, a second metal sealing body to which a second main electrode is attached and sealing the other opening, and an inert gas sealed in the hollow part. and a glass sealed body that seals the small hole after sealing an inert gas into the hollow part through the small hole. (2) A hollow cylindrical envelope made of an insulating material such as ceramic and having a hollow part and a small hole communicating with the hollow part and open at both ends, and a first main electrode attached to the case and sealing one of the openings. a second metal sealing body to which a second main electrode is attached and which seals the other of the openings; an inert gas sealed in the hollow part; A constant voltage discharge tube for an ignition device, comprising a glass sealing body that seals the small hole after filling the hollow portion with an inert gas through the hole. (3) A hollow cylindrical envelope made of an insulating material such as ceramic and having a hollow portion and open at both ends, with a first metal sealing body having a first main electrode attached and a small hole; and a second metal sealing body to which a second main electrode is attached, a sealing glass body is attached to the small hole, and the hollow part is evacuated through the small hole. A method for manufacturing a constant voltage discharge tube for an igniter, comprising filling the hollow portion with an inert gas at a predetermined pressure via a tube, and then heating and melting the glass sealing body to seal the small hole. (4) A hollow cylindrical envelope made of an insulating material such as ceramic and having a hollow part and a small hole communicating with the hollow part and open at both ends, is connected to a second main electrode to which the first main electrode is attached. a second metal encapsulant and a second main electrode attached thereto;
A glass sealing body is attached to the small hole, the hollow part is evacuated through the small hole, and an inert gas at a predetermined pressure is supplied to the hollow part through the small hole. A method for manufacturing a constant voltage discharge tube for an ignition device, which comprises sealing the small holes by heating and melting the glass sealed body. (5) The constant voltage discharge tube for an ignition device according to claim 2, wherein the small hole has a stepped hole into which the glass sealing body is fitted. (6) The constant voltage discharge tube for an ignition device according to claim 2, wherein at least one or more grooves are provided on the inner periphery of the small hole.