JPH0238382Y2 - - Google Patents

Description

[Detailed explanation of the idea] This invention relates to an airtight terminal.

Generally, as shown in FIG. 1, an airtight terminal has a structure in which a lead wire 3 is sealed in a metal outer ring 1 through a glass 2 in an airtight and insulated manner. This type of hermetic terminal can be roughly divided into compression sealing type and matching sealing type. In the former case, the metal outer ring 1 is made of iron or low carbon steel, the glass 2 is made of soda barium glass or soda lime glass, and the lead wire 3 is made of iron-nickel alloy, iron-chromium alloy, or iron-nickel-chromium. _{The glass 2 ​ ​ ​}
However, a stronger compressive stress can be applied to the metal outer ring 1, and it has the advantage of being inexpensive and having excellent mechanical strength. On the other hand, in the latter case, the metal outer ring 1 and the lead wire 3 are made of an iron-nickel-cobalt alloy called Kovar, and the glass 2 has an expansion coefficient that is substantially the same as that of the Kovar over a wide temperature range. (α ₁ ≒ α ₂ ≒ α ₃ ) It is made of borosilicate glass and has the feature of excellent airtightness over a wide temperature range.

In the former compression-sealed airtight terminal, strong compressive stress is applied to the glass 2 by the metal outer ring 1, so it goes without saying that the glass 2 must not be destroyed by the compressive stress. but,
The metal outer ring 1 also needs to have mechanical strength that will not be destroyed by its own compressive stress, in other words, by the tensile force as a reaction to the compressive stress that the glass 2 receives. Therefore, in a compression sealing type airtight terminal, generally, when the inner diameter of the metal outer ring 1 is φ1 and the larger diameter is φ2,
It is said that the relationship φ2/φ1≧1.2 is necessary.

In this type of airtight terminal, the withstand voltage and/or insulation resistance between the metal outer ring 1 and the lead wire 3 is given by the creepage distance of the glass 2. Therefore, in order to increase the withstand voltage and/or insulation resistance, the creepage distance of the glass 2 may be increased. However, as shown in FIG.
If a There is a problem in that cracks 4 occur in the glass 2 due to the difference in compressive stress, and the withstand voltage and/or insulation resistance are reduced.

On the other hand, as shown in FIG. 3, it is also conceivable to provide a stepped portion 5 on the metal outer ring 1 to make the diameter φ3 of the upper surface of the glass 2 larger than the diameter φ1 of the lower surface to increase the creepage distance. This method is effective when the wall thickness of the metal outer ring 1 (t = (φ2 - φ1)/2) is sufficiently large, but for the reasons mentioned above, φ2/φ1≧1.2 and φ2/φ3≧1.2 Since the following relationship is required, if the thickness of the metal outer ring 1 is fixed, φ3 cannot be made very large, and as a result, there is a problem that the withstand voltage and/or insulation resistance cannot be improved that much. .

Therefore, the main purpose of this invention is to improve the withstand voltage and/or insulation resistance of a compression-sealed hermetic terminal without increasing the thickness of the metal outer ring.

To summarize, this idea consists of forming one or more steps on both the inner and outer surfaces of a metal outer ring with a given wall thickness, with the inner diameter of the smaller diameter side of the metal outer ring being A, the outer diameter being B, and the larger diameter side of the metal outer ring having one or more steps. When the inner diameter is C and the outer diameter is D,
It is characterized by setting B/A≧1.2 and D/C≧1.2.

The above objects and other objects and features of the present invention will become more apparent from the following detailed description with reference to the drawings.

FIG. 4 shows a sectional view of the first embodiment. In the figure, reference numeral 10 denotes a metal outer ring, which is made of iron or low carbon steel, and has stepped portions 11 and 1 on both the inner and outer sides with a predetermined wall thickness.
2 is provided, and a small diameter portion 13 and a large diameter portion 14 are formed. Further, a flange 15 is provided at the end edge of the large diameter portion 14. 16 is glass,
It is made of soda barium glass or soda lime glass, and its upper and lower surfaces are formed on the same plane as the upper and lower surfaces of the metal outer ring 10. Reference numeral 17 denotes a lead wire, which is made of iron-nickel alloy, iron-chromium alloy, iron-nickel-chromium alloy, etc., or at least the outer surface to be sealed with glass 16 is made of the above-mentioned alloy, and the core is made of a good quality material such as copper. It is composed of a composite made of conductive metals.

In the above configuration, the small diameter portion 13 of the metal outer ring 10
The inner diameter of the large diameter portion 14 is A, the outer diameter is B, and the inner diameter of the large diameter portion 14 is C.
If the outer diameter of the flange 15 is D, both A and B are relatively small in the small diameter portion 13, so it is easy to set the relationship B/A≧1.2. Also, large diameter part 1
4, C becomes larger, but D due to flange 15
can be made sufficiently large, so it is also easy to use D/C.
The relationship can be set to ≧1.2. Therefore, by using the metal outer ring 10 with a relatively small wall thickness, the glass 16
By greatly increasing the creepage distance, the withstand voltage and/or insulation resistance between the metal outer ring 10 and the lead wire 17 can be significantly improved.

Although the above embodiment has been described with respect to the case where the stepped portions 11 and 12 are provided one step each on both the inner and outer surfaces of the metal outer ring 10, it will be easily understood that two or more steps may be provided.

FIG. 5 shows a sectional view of a second embodiment of the invention. This embodiment is for a case where the wall thickness of the metal outer ring 20 is slightly larger than that in the case shown in FIG. This is similar to the embodiment, but differs from the previous embodiment in that no flange is provided. In this embodiment, the inner diameter of the small diameter portion is A and the outer diameter is B, and the inner diameter of the large diameter portion 24 is C and the outer diameter is D.
Similarly to the above, since both A and B of the small diameter portion 23 are relatively small, the relationship of B/A≧1.2 can be easily obtained. Further, in the large diameter portion 24, the flange 15
However, by increasing the thickness of the metal outer ring 20, a relationship of D/C≧1.2 can be obtained. Therefore, the same effects as in the embodiment described above can be obtained.

As described above, this invention provides at least one step on both the inner and outer surfaces of the metal outer ring, the inner diameter of the smaller diameter side of the metal outer ring is A, the outer diameter is B, the inner diameter of the larger diameter side is C, and the outer diameter is When the diameter is D, since B/A≧1.2 and D/C≧1.2 are set, the creepage distance can be increased without causing cracks in the glass, and the distance between the metal outer ring and the lead wire can be increased. withstand voltage and/or
Alternatively, the insulation resistance can be improved.

[Brief explanation of the drawing]

Figure 1 is a sectional view of a typical airtight terminal, Figures 2 and 3 are sectional views of different examples of methods for improving withstand voltage and/or insulation resistance, and Figures 4 and 5 are different examples of this invention. It is a sectional view of the airtight terminal of an example. 10, 20...metal outer ring, 11, 12, 21,
22... Step part, 13, 23... Small diameter part, 14, 2
4... Large diameter portion, 15... Flange, 16, 26...
...Glass, 17, 27...Lead wire.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) An airtight terminal in which a lead wire is hermetically and insulatively sealed inside a metal outer ring through glass, wherein steps are provided on both the inner and outer surfaces of the metal outer ring, When the inner diameter of the smaller diameter side of the metal outer ring is A, the outer diameter is B, the inner diameter of the larger diameter side is C, and the outer diameter is D, then B/A
An airtight terminal characterized by setting ≧1.2 and D/C≧1.2. (2) the metal outer ring is made of iron or low carbon steel;
Utility model registration claim 1, in which the glass is made of soda barium glass or soda lime glass, and at least the outer surface of the lead wire is made of iron-nickel alloy, iron-chromium alloy, or iron-nickel-chromium alloy. Hermetic terminal. (3) The airtight terminal according to claim (2) of the utility model registration, wherein the metal outer ring is provided with an outward flange on the large-diameter side surface of the glass.