US3356813A

US3356813A - Mercury sealed contact switch

Info

Publication number: US3356813A
Application number: US553791A
Authority: US
Inventors: Shinohara Takeo; Maruyama Hiroshi
Original assignee: Nippon Electric Co Ltd
Current assignee: NEC Corp
Priority date: 1965-06-02
Filing date: 1966-05-31
Publication date: 1967-12-05
Anticipated expiration: 1984-12-05

Description

Dec. 5, 1967 v TAKEO SHINOHARA ET AL 3,356,813

MERCURY SEALED CONTACT SWITCH 2 Sheets-Sheet 1 Filed May 31, 1966 FIGQIV INVENTORS TAKEO SHINOHARA HIROSHI MARUYAMA ATTORNEYS Dec. 5, 1967 TAKEO SHINOHARA ET AL 3,356,813

MERCURY SEALED CONTACT SWITCH Filed May 51, 1966 2 Sheets-Sheet F36. 3G. 5 (RRIQR ART) (PRIOR ART) [1\\ 'EN'TU1 TAKEO SHlNOHAFf/A HIROfiHI MARUYAMA M (5 MW" we,

AT TOR NEYE United States Patent 3,356,813 MERCURY SEALED CONTACT SWITCH Takeo Shinohara and Hiroshi Maruyama, Tokyo, Japan, assignors to Nippon Electric Company, Limited, Tokyo, Japan, a corporation of Japan Filed May 31, 1966, Ser. No. 553,791 Claims priority, application Japan, June 2, 1965, 40/ 32,200 3 Claims. ('Cl. 200-152) ABSTRACT OF THE DISCLOSURE An improved miniature mercury sealed contact switch structure with a metal pipe integrally attached to the lower portion thereof in a direction substantially normal to the longitudinal axis with an end portion of the pipe disposed within the lower portion of the switch and serving to inject mercury and gas into the switch vessel.

This invention relates to mercury switches and more particularly to an improved miniature mercury sealed contact switch structure which is unaffected by dust or by corrosive gas in the atmosphere and which can break a comparatively larger amount of current than prior comparable structures.

As is well known, mercury type transfer contact switches and sealed contact switches are of relatively large size so that, until now, these have been entirely unsuitable for certain applications. Furthermore, along with the constant trend of size reduction in communication equipment generally, the miniaturization of electromagnetic devices and particularly mercury sealed contact switches is urgently required.

There are, however, theoretical and industrial technical limits which militate against miniaturization of conventional type mercury sealed contact switches because of various factors, such as for example the surface tension and wetness of mercury, the increase in stiffness or lack of suitable flexibility of the movable reed, and other factors.

Accordingly, it is a principal object of the present invention to provide miniature size mercury sealed contact switches which are relatively short along the longitudinal direction thereof, by overcoming the difficulties observed above.

All of the objects, features and advantages of this invention and the manner of attaining them will become more apparent and the invention itself will be best understood by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawing, in which:

FIG. 1 is a sectional view of one embodiment of a mercury sealed contact switch constructed according to the present invention,

FIG. 2 is a side sectional view thereof,

FIGS. 3, 4 and 5 are partial longitudinal sectional views of embodiments illustrating various contours of the movable reed and high pressure gas and mercury vapor injection pipes used in this invention.

FIGS. 6 and 7 are enlarged sectional views showing the junction or bond between the insulating body portion and the metallic body portion of the switch container or housing used in the present invention,

FIG. 8 is a sectional view of one conventional type switch-over sealed contact switch illustrating the structure thereof,

FIG. 9 is a fragmentary elevation view of one conventional type mercury sealed contact switch relay illustrating the structure thereof, and

FIG. 10 is a fragmental side sectional view of FIG. 9.

3,356,813 Patented Dec. 5, 1967 The operational principle of a conventional sealed mercury contact switch relay will first be explained with reference to FIGS. 9 and 10. As shown in these figures, a magnetic metal tube 9 which serves as a movable reed terminal, and two stationary reeds 18 and 18', are all supported by a cylindrical hollow enclosure 10, preferably composed entirely of insulating material. The surface of a movable reed 19 which is also made of a magnetic material and fixed to the movable reed terminal 9 is wetted by mercury from the mercury pool 12.

In the absence of the

permanent magnets

13 and 14, the movable reed 19 is located between

contacts

11 and 11, and spaced therefrom, these contacts being fixed to the stationary reeds 18 and 18'. A metallic strip 17 is sealed and welded after mercury or gas under pressure is injected into the vessel or enclosure through the tube 9, the latter also serving as a movable reed cylindrical termnial. A yoke 16 made of a magnetic material is provided in order to increase the magnetic sensitivity of the switch, the coils being designated by the reference character 15.

When the permanent magnet 13 has a greater magnetizing force than that of the permanent magnet 14 and is located with respect thereto as shown in FIG. 9, the movable reed 19 is attracted toward the stationary reed 18 associated with the permanent magnet 13 which has a.

greater magnetizing force, thus permitting the movable reed 19 to physically engage the contact 11.

With this arrangement and when the magnetic field N-S which is generated by the coil energized from an external source is applied in the direction shown in FIG. 9, the movable reed 19 is moved toward the stationary reed 18 located on the side of the other magnet 14 opposite to the magnet 13. The operational principles of the structures illustrated in FIGS. 1, 2 and 8 are identical with that just explained, so that the electric switches therein are opened and closed in accordance with these principles.

One of the problems encountered in miniaturizing the prior art sealed type contact switch is that its length must be made longer in order to avoid cracks of the sealing glass due to the deformation of the pipe when the welding seal is made because the movable reed terminal extends. along the axial direction of the cylindrical hollow vessel. Therefore, as shown in FIG. 8, it is preferred to locate the stationary reeds as well as their contacts transversely to the axial direction of the enclosure. However, when this design is employed, it is very difficult to effect sealing and to maintain the desired precision of dimensions, and furthermore the size is necessarily enlarged.

A second problem is that when the length of the movable reed is shortened, the switch cannot be satisfactorily actuated without reducing the thickness of the reed because the stitfness will be increased. Therefore, in order to decrease the stiffness, a bent portion must be provided, however due to miniaturization there is a limit to the inner volume of the enclosure which can accommodate a suitable bend.

A third problem is that the length of the sealed portion that comprises the supporting portion of the cylindrical hollow vessel 10 of insulating material for supporting the movable reed terminal 9 is required to be of the order of 3 mm. from the standpoint of air-tight sealing and mechanical strength of that portion. This tends to place a limit upon the minimum length required for the switch. In accordance with the present invention, the above described problems are eliminated so that a miniature mercury sealed contact switch having a very short length can be obtained.

Referring now to FIGS. 1 and 2, the present invention will be described in more detail. As shown in these figures, a cylindrical, hollow, sealed vessel consisting of an upper insulating body 6 and a lower metallic body 5 is employed. A movable reed 1 is secured to a pipe 3 for injecting into the vessel mercury and gas under high pressure. This pipe 3 is preferably secured directly to the metallic body of the vessel as illustrated in FIGS. 3, 4 and 5. Briefly, according to the present invention, the movable reed terminal which also serves as a metallic pipe for injecting into the vessel mercury and gas under high pressure is positioned in a direction which does not correspond with the axial direction of the vessel, but rather is preferably disposed in a direction substantially normal to the longitudinal direction of the vessel. With this arrange ment, the contact switches of this invention can be made shorter in the longitudinal direction thereof and furthermore the length of the sealing portion can be made shorter while the inner volume of the vessel can be made larger. In FIG. 1, the reference characters 2 and 2' designate fixed reeds with contacts 7 and 7' thereon and the numeral 4 designates mercury. In FIG. 2, a metallic strip 8 is welded to the tube 3 after mercury and gas under high pressure have been injected into the vessel.

FIGS. 3, 4 and 5 show various shapes that may be employed for the base portion of the movable reed to enable the inclusion therein of structure to decrease the stiffness of the reed. These figures also show that a pipe for injecting mercury and gas under pressure may be made integral with the metallic body 5. Throughout these figures the same reference characters designate the same parts illustrated in FIG. 1. The bond between the insulating body 6 and the metallic body 5 does not directly form a part of the metallic body 5 is embedded into the insulating body 6.

The third problem described above is obviated according to the present invention by using a third metallic body at the lower portion of the vessel of the contact switch so that the length corresponding to the length of the seal can be eliminated. Furthermore, the second problem is also obviated so that the inner volume of the vessel can be made larger. This permits shaping the base portion of the movable reed, as illustrated in FIGS. 3, 4 and 5 for example, so that the stiffness of the reed may be decreased and so that sufficient magnetic attractive force may be obtained. The first problem described above is solved by utilizing the metallic plate at the lower portion of the vessel in order to provide sutficient mechanical strength and further :by locating the metallic pipe for injecting mercury and gas under high pressure substantially normal to the longitudinal direction of the vessel. Thus it will be seen that according to the present invention, a miniature mercury sealed contact switch is produced having a length significantly shorter than switches of the prior art.

While the foregoing description sets forth the principles of theinvention in connection with specific apparatus, it is to be understood that the description is made only by way of example and not as a limitation of the scope of the invention as set forth in the objects thereof and in the accompanying claims.

What is claimed is:

1. A mercury sealed contact switch comprising a sealed hollow vessel having a longitudinal axis,

a pair of stationary reeds, a movable reed, and a metal said vessel consisting of an upper portion of insulating material and a lower portion of metallic material and containing mercury in said lower portion and gas above said mercury,

and metal pipe being integrally attached to said lower portion in a direction substantially normal to said longitudinal axis with an end portion thereof dis"- posed within said lower portion and serving to inject said mercury and gas into said vessel during manufacture,

said stationary reeds being arranged generally along said axis,

said stationary reeds further each being attached at an end portion thereof to said upper portion,

said movable reed also being disposed generally along said axis and fixed at an end portion thereof to said end portion of said pipe, and the free end portions of said stationary and movable reeds serving as contacts of said switch, whereby significant reduction in overall length is provided for a switch of given capacity.

2. A mercury sealed contact switch comprising a sealed hollow vessel, two stationary reeds, a movable reed, and a metal pipe,

said vessel consisting of an upper portion of insulating material and a lower portion of metallic material and containing mercury in said lower portion and gas above said mercury,

said stationary reeds being arranged generally along the axis of said vessel,

said stationary reeds each being attached at an end portion thereof to said upper portion,

said movable reed also being disposed generally along said axis and secured at an end portion thereof to said lower portion,

said pipe being integrally attached to said lower portion in a direction substantially normal to said axis with an end portion thereof communicating with said lower portion for injecting said mercury and gas into said vessel during manufacture,

and the free end portions of said stationary and movable reeds serving as contacts of said switch, whereby a significant reduction in overall length is provided for a switch of given capacity.

3. The invention described in claim 2 wherein said movable reed is provided with a circuitous portion at the end thereof which is secured to said lower portion to extend the length of said movable reed, whereby the stiffness of the same is significantly reduced.

References Cited UNITED STATES PATENTS 2,487,052 11/1949 Hastings 335-151 3,018,354 1/1962 Pollard 33558 ROBERT S. MACON, Primary Examiner. ROBERT K. SCHAEFER, Examiner.

HOHAUSER, Assistant Examiner.