US1984478A - Mercury switch - Google Patents

Description

Dec. I8, 1934.

Filed March 4, 1932 ATTORNEY Patented Dec. 18, 1934 UNITED STATES MERCURY SWITCH Charles Hatay, Berlin-Charlottenburg, Germany,

assignor to General Electric Company, a corporation of New York Application March 4, 1932, Serial No. 596,846 In Germany March 6, 1931 2 Claims.

The present invention relates generally to mercury switches and more particularly the invention relates to such switches in which the movements of a tubular magnetizable body floating in a pool of mercury in the container of the device, controlled by a magnetic field, are made use of to raise or lower the level of said mercury pool and thus make or break the electrical contact between the electrodes of the device.

I have observed that in previous switches of the above type the diameter of the tubular body could not go below a certain limit without the formation of a mercury globule over the tubular body when said body was immersed in the pool of mercury which would prevent the rise of said tubular body and hence the operation of the switch was interrupted. This defect in this type of switch is further enhanced by the adhesion of the mercury to the outer wall of the tubular body and the inner wall of the switch container. Due to this phenomena it has been necessary heretofore to make mercury switches of this type of comparatively large dimension even for a switch of small capacity, which increased the current consumption and the cost of such switches.

The object of the present invention is to make available for use in the arts generally a mercury switch of the above type which is positive in its action. A further object of the invention is to provide a switch of the above type which consumes less current and is less costly to make than previous switches or the same current carrying capacity. Still further objects and advantages attaching to the invention and to its use and operation will be apparent to those skilled in the art from the following particular description and from the appended claims.

4 In accordance with these objects the invention comprises a tubular, magnetizable body having one or more elongated, pointed protuberances at each of its ends to facilitate the immersion and withdrawal of said body from the pool of longation at the ends of the tubular body','and

Fig. 5 is a detailed view of another form of prolongation at the end of the tubular body.

Referring to Fig. l of the drawing the new and novel switch comprises a sealed glass container 1 having metal caps 2 and 2' at each end thereof. A body 3 of mercury is in said container 1. Electrodes 4 and 4' are electrically connected with said caps 2 and 2 and are sealed into said container I. Said electrodes 4 and 4' extend along the longitudinal axis of said container 1, the separation between said electrodes 4 and 4' is greater than the arcing distance of the current applied thereto. A tubular plunger 5 of magnetizable material floats on said mercury pool 3 and is concentric with said container 1. Said plunger 5 is of sufficient length that the walls thereof are between the glass walls of container 1 and the are formed between the electrode 4 and mercury pool 3 when contact therebetween is made or broken at all operating positions of said plunger 5 to protect the glass walls of container 1 from said arc. The lateral movements of said plunger 5 in said container 1 are controlled by projections 6 and 6' on plunger 5 sliding along the-inner wall of said container 1. Said plunger 5 is provided with pointed projections '7 and 7' at each end thereof and an-opening 8 in the walls thereof.

When the magnetizable plunger 5 is attracted downward by a magnetic field generated by a circular winding of an electromagnet placed around said container 1 (omitted from the drawing for purposes of simplicity) and below the horizontal median line of said plunger 5 the points 7' of said plunger 5 separate the mercury pool 3 to facilitate the immersion of said plunger 5 in said mercury pool 3. When plunger 5 is immersed in said mercury pool 3 the mercury displaced thereby rises and bridges the gap between electrodes 4 and 4 'and current flows through said switch. When current is cutof! from the circular winding of the magnet surrounding said container 1 the plunger 5 quickly snaps up, due to its buoyancy in said mercury pool 3 and due to the separation of the mercury covering the top of said plunger 5 by said pointed protuberances 7, to lower the level of said mercury pool 3 to break the electrical contact between said electrodes 4 and 4'. The separating eiiect of said pointed protuberances '1 can be increased by slanting oi! the inner and/or the outer edges of said protuberances 7 as shown in Figs. 4 and 5. The opening 8' in the walls of plunger 5 facilitates the immersion into and withdrawal of said tubular body 5 in the mercury pool 3 by permitting free flow of the mercury into and out of the interior of said tubular body 5 and the distance between the inner wall of container 1 and the outer wall of plunger 5 is made not less than three-fourths of a millimeter to permit the free rise and'fall of mercury therebetween resulting from the immersion and withdrawal of said plunger 5 in said mercury pool 3.

While we have shown and described and have pointed out in the annexed claims certain novel features of the invention, it will be understood that various omissions, substitutions and changes in the forms "of details ,of the device illustrated and in its use and operation may be made by those skilled in the art without departing from the broad spirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1 A mercury switch comprising a tubular container, electrodes sealed therein at each end thereof, a pool of mercury in said container, at least one of said electrodes being out of said mercury when electrical contact is broken in said switch, a plunger in said container, said plunger surrounding the contact point between said mercury and said last named electrode at all operating positions of said plunger, said plunger being totallyimmersed in said mercury when electrical contact is made in said switch, said plunger having a perforated wall and pointed protuberances at each end thereof to facilitate the movements thereof in said mercury pool, the successive movements of said plunger making and breaking the electrical contact between said electrodes.

2. A mercury switch comprising a tubular container, electrodes sealed therein at each end thereof, a pool of mercury in said container, at least one of said electrodes being out of said mercury when electrical contact is broken in said switch, a plunger in said container, said plunger surrounding the contact point between said mercury and said last named electrode at all operating' positions of said plunger, said plunger being totally immersed in said mercury when electrical contact is made in said switch, the distance between the outer wall of said plunger and the inner wall of said container being not less than three-fourths of one millimeter, said plunger having a perforated wall and pointed protuberances at each end thereof to facilitate the movements thereof in said mercury pool, the successive move- 4 ments of said plunger making and breaking the electrical contact between said electrodes.

- CHARLES HATAY.

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