JPH01145348A - Enclosure bulb for vacuum load-break switch - Google Patents

Abstract

PURPOSE:To facilitate the production of the title bulb composed of a crystallized glass having excellent mechanical strength and vacuum-maintaining property, by using a crystallized glass having a specific composition. CONSTITUTION:The title bulb is formed of a crystallized glass containing 73-81wt.% of SiO2, 0.5-10wt.% of Al2O3, 0-4wt.% of Na2O, 0-5wt.% of K2O (Na2O+K2O being <=5wt.%), 10-20wt.% of Li2O, 0.1-5wt.% of P2O5, 0-1wt.% of F, 0-4wt.% of As2O3 and 0-4wt.% of Sb2O3 (As2O3+Sb2O3 being <=4wt.%) and having a crystallinity of 30-70%.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention is directed to arrangement! The present invention relates to an envelope pulp for a vacuum switch used in railway lines, and particularly to an envelope valve for a vacuum switch made of crystallized glass.

(Prior art) Vacuum circuit breakers that cut off large currents that occur due to short-circuit accidents in power distribution lines, vacuum contacts that are frequently opened and closed to switch the load current of motors, and sectional switching of power distribution lines. Vacuum switches and the like used in electrical appliances are constructed to open contacts in a high vacuum to diffuse charged particles of the arc and extinguish it, and have excellent breaking performance.

Conventionally, the envelopes of these vacuum switches have been made by sealing 'α poles (2) made of Kovar metal parts on both ends of a cylindrical envelope pulp (1) made of glass or alumina ceramics, as shown in the figure. It is formed by - In general, the properties required for this envelope pulp are: 1) long-term airtightness, 2) high mechanical strength against stress such as impact, and θ.
It can withstand high temperatures during vacuum evacuation, and is suitable for welding structural parts.

(Problems to be Solved by the Invention) However, the envelope glass made of glass has a problem in mechanical strength, and the envelope pulp made of alumina ceramics has a mechanical strength superior to that of glass. However, since a metallization process is required for sealing with metal parts, the manufacturing process is complicated, and there are problems with long-term reliability of airtightness, that is, maintaining the vacuum level, so improvements in these are desired. There is.

The present invention was made to solve the above problems, and provides an envelope valve for a vacuum switch that has excellent mechanical strength, is reliable in long-term maintenance, and has a simple manufacturing process. The purpose is to

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above object, the present invention solves the following problems:
This is an external H-type bulb made of TO2 type crystallized glass. That is, 5IO273 on a weight percent skewer
~81%, human'mOs 0.5~lO%.

Na200~4%r Kz o O"" 5%, N
az O+ Kz 05 or less, 54010-20%
, p, o, 0.1-5%.

FO ~ 1% 1 person s, O, 0 ~ 4%, Sb, O, 0 ~
4%.

λa20. + This is an envelope bulb for a vacuum switch made of crystallized glass containing 0.4% or less of Sb. Further, it is a pulp with a crystallization rate of the crystallized glass of 30 to 70%.

LI2O/2SIO2-based crystallized glass has excellent mechanical strength and excellent sealing properties with metal parts, but
The reason why the glass composition was limited to the above range will be explained.

8 r 02 is the main component forming glass, but 73
If it is less than 81%, the chemical durability will be poor, and if it exceeds 81%, the softening temperature will be high.

When λ203 is less than 0.5%, chemical durability decreases,
If it exceeds 10%, the glass becomes non-uniform, leading to increased striae and increased viscosity, leading to increased melting and processing defects. N a 20・L2
0 is used as an oxidizing agent for glass refining, but if the total amount exceeds 5%, bubble breakage becomes difficult and chemical durability also deteriorates.

L1□0 is an essential component that promotes glass crystallization, but if it is less than 10%, crystallization is insufficient, and if it exceeds 20%, the expansion coefficient becomes excessive.P20II is a nucleation component for glass crystallization. Although it is an essential component as an agent, if it is less than 0.1%, no effect will be obtained, and if it exceeds 5%, the ability to promote crystallization will be poor.

F is added to lower the viscosity of molten glass, but 1
If it exceeds %, devitrification tends to occur during the glass molding process, resulting in poor workability. λg20. , Sb, 0. is added as a clarifying agent, but if the content exceeds 4%, re-foaming will occur during heat processing, which is not preferred.

Next, the reason why the crystallization rate of the glass is limited to the above range will be explained.

The crystallization rate of glass greatly affects its mechanical strength and sealability with metal parts. 1'. If it is less than 30%, the sealing performance is good, but the mechanical strength is no different from that of glass;
If it exceeds 0%, the mechanical strength is sufficient, but the sealing performance deteriorates, resulting in a decrease in product yield, and the long-term reliability of maintaining the vacuum level becomes comparable to that of alumina ceramics.

(Function) The envelope pulp of the present invention is made of Ll, 0.2SiO2-based crystallized glass, and when used in a vacuum switch, increases the mechanical strength of the product and It also has excellent long-term reliability in maintaining temperature, so the product life can be extended.

(Example) An example of the present invention is shown below. Comparative examples are conventional examples of glass surfaces and alumina ceramics. Glass compositions are given in weight percentages. Mechanical strength and υg switching life The mechanical strength and switching life of a vacuum switch using an envelope valve made of each material are shown below. The long-term reliability of maintaining the vacuum level of a vacuum switch is determined by referring to the switching life.

From the above table, it can be seen that the mechanical strength of the envelope bulb of the present invention is significantly superior to that of conventional products, and is comparable to that of vacuum-maintained glass products.

〔Effect of the invention〕

As described above, the present invention is an envelope valve for a vacuum switch made of LI2O-2SiO□-based crystallized glass, and the vacuum opening time is 1 yen! It increases the mechanical strength of the device and has excellent long-term reliability in maintaining the vacuum level, so it has the advantage of extending the product life.

[Brief explanation of the drawing]

The drawing is a -S longitudinal sectional side view showing an example of an envelope of a vacuum switch. 1...Envelope valve 2...[Pole 1
: Envelope bulb 2: Electrode

Claims (2)

[Claims] (1) SiO_273-81%, Al_2 in weight percentage
O_30.5-10%, Na_2O0-4%, K_2O
0-5%, Na_2O+K_2O 5% or less, LI_2O
10-20%, P_2O_30.1-5%, F0-1%
, As_2O_30-4%, Sb_2O_30-4%,
An envelope valve for a vacuum switch made of crystallized glass containing 34% or less of As_2O_3+Sb_2O_3. (2) The envelope valve for a vacuum switch according to claim 1, wherein the crystallized glass has a crystallization rate of 30 to 70%.