US 2522721 A
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Description (OCR text may contain errors)
Sept. 19, 1.950 R. P. MATTERN 2,522,7'21` coNTRoL APPARATUS Filed Jan. 23, 1947 Z (5L/ISS Patented Sept. 19, 1950 CONTROL APPARATUS Raymond P. Mattern, Minneapolis, Minn., as-
sig'nor to Minneapolis-Honeywell Regulator Company, Minneapolis, Minn., a corporation of Delaware Application January 23, 1947, Serial No. 723.679
4 Claims. 1
The present invention relates to liquid contact switches which are characterized by having splash-proof qualities. In particular, the switches are designed so that when situated in an inactive position, the circuit closing liquid will not be splashed or thrown into bridging contact `with its electrodes under conditions such as might be caused by a sudden jarring of the switch. While switches of this character are considered of general utility, they are especially suited for use with marine safety appliances carried by sea-going vessels.
A particular application for this switch is found in the controlling of the energization of a signal lamp on life rafts. For security reasons in time of war and in the interest of maintaining the life of the batteries which energize these lamps during all periods when the lamps are not in actual use, it is necessary that the switch controlling the energization of the lamp operate only when tilted by positive action. It is therefore necessary that the jarring effect of the heavy seas or gunre when transmitted to the switch, does not cause the mercury in it to be tossed into contact with its electrodes.
It is therefore an object of the invention to provide a mercury switch which is provided with means to prevent the mercury from splashing into contact closing relationship ywith its electrodes when the switch is violently jarred or shaken while in an open circuit position.
Another object is to provide a mercury switch of the electrode to mercury type in which a movable object, formed of material whose density is lower than that of mercury, is enclosed within the switch so that when the switch is in an inactive position the object is in floating relationship to the mercury and serves to prevent the latter from accidentally moving into contact bridging relationship with the electrodes when the switch is jarred.
Another object is to provide, in a mercury switch of the type in which a body of mercury and a pair of electrodes are sealed within an enclosure, a member within the enclosure which serves to prevent the mercury from splashing into circuit bridging contact with the electrodes when the switch is jarred while in a relatively normal inactive position.
(Cl. 20D-452) These and other' objects will become apparent from the following specification and claims and in the several figures of the appended drawing in which:
Figure 1 is one form of splash-proof mercury switch shown in an inactive position and with a portion of the envelope removed;
Figure 2 is a partial view of the same switch shown in an active or closed circuit position;
Figures 3 and 4 are modified forms of the switch shown in Figures 1 and 2;
Figures 5 and 6 are modified forms of the switch shown in Figures l and 2, illustrating variations in the shape of the floating object;
Figure 7 is an elevation, with parts in section, of another form` of switch in which the splashproof feature is provided by elements which form an integral part of the envelope;
Figure 8 is a cross-section taken on the lines 8 8 of Figure 7; and
Figure 9 is a cross-section corresponding to Figure 8, of a modification of the switch shown in Figure '7.
Referring now to the several figures of the drawing in which like reference numerals are used to describe similar elements, the invention will be described in detail.
Referring specifically to Figures 1-4, reference numeral I0 indicates .a tubular envelope formed ofglass or the like having a plurality of spaced electrodes II and I2 clamped in one end thereof by the usual pinch seal I3, with a pair of iieXible lead wires I4 and I5 connected to portions of electrodes II and I2 exterior of the pinch seal I3 and held in place by a glob of cement I5. Sealed within the tubular envelope I in the usual hydrogen atmosphere is a pool of mercury I '1, and a number of freely movable balls i8. The balls I8 may be formed of any suitable material such as glass or the like and they must have less density than the mercury. In size, balls I 8 should be of somewhat less diameter than the interior dimensions of envelope Il) so that when the switch is reversed in position, as shown in Figure 2, they will not appreciably impede theflow of mercury from one end of envelope ID to the other end thereof, and so that where a number of balls I8 are used they will tend to form an irregular arrangement as shown in Figures l, 2 and 4.
When a switch of this nature is placed in use it is clamped, by means not shown, in an upright position, and adapted for rotation through an angle of substantially 3.80 degrees between active and inactive positions, as shown in Figures l and 2. The function of balls I8 is to prevent portions of mercury pool I1 from splashing in suilicient quantity to bridge electrodes II and l2 when the switch is jarred while in an inactive position, as shown in Figures 1, 3 and 4. When the craft is suddenly jarred, as for example by gunfire, the switch will vibrate, causing portions of mercury pool I'I to be separated into individual globules which bounce violently within envelope IU. If the globules of mercury thus separated are of very large mass, they will, when thrown upwardly, bridge electrodes II and I2 to complete an electrical circuit through the said electrodes for a momentary period until they return to pool I1 by gravity. When envelope ID'is vibrating under the influence of the aforementioned shock, ball or balls I8 will also be caused to vibrate in such a manner `as to dampen the vibration ofthe separated mercury globules and also to break up the mass of such globules as may become separated from pool I'I, so that any portions of the mercury which continue to travel upwardly will not be of sufiicient dimension to bridge the gap between electrodes II and I2. The number of balls I8 which may be used in any one application will depend upon the severity of theshock to which envelope I8 is subjected and is limited in number only to the extent that they should not appreciably impede the rapid flow of mercury from one end of envelope I to the other end thereof when the switch is reversed in position.
Referring now to Figure 5, this is a modification of the switch shown in Figures 1 4, in which the splash-preventing member is shown in the form of a rod` I9 which may also be formed of glass or other material having less density than mercury. Like balls IS, rod I9 floats on the surface of the mercury pool II along the central axis of envelope It and occupies a substantial portion of the space between mercury pool I1 and electrodes II and I2. The diameter of rod I9 should be less than the internal dimensions L of envelope I0 so as not to appreciably impede the flow of mercury from one end of the envelope to the other when the switch is reversed in position, and yet it should be sufficient to break up a globule of mercury which becomes separated from pool I1 to the extent that the globule cannot bridge electrodes II and I2.
Figure 6 is a modification of the design shown in Figure in that a tubular member 2t having a series of indentations 2l arranged in the wall thereof is used in place of rod member I9. The indentations ZI extend substantially to the central axis of member 2t to prevent a mercury globule from splashing upward through the center portion of member 2t, but they will not prevent the passage of mercury through the center of member 2li-when the switch'is rotated to a circuit closing position. Member is spaced from the inner wall of envelope Ill in the same manner as rod member I9 so as to permit the restricted passage of mercury about its exterior surface.
In Figures 7 and 8, a tubular envelope 25 is provided with the usual spaced apart electrodes I I and' I2 and a'merc'ury pool Il, but differs from envelope I 0 in that a series of conical shaped indentations 2B are provided in the wall of the envelope to prevent separated globules of mercury from being thrown into circuit bridging contact with electrodes I I and I2. The indentations 26 extend inwardly to substantally the central axis of envelope 25 and may be arranged in any suitable manner. As shown indentations 26 are spirally arranged in the surface of envelope 25, this arrangement being effective to avoid splashing, but does not appreciably impede the free ow of mercury from one end of the envelope to the other when the switch is rotated from end to end.
Figure 9 is a cross-sectional view, similar to Figure 8, of a modication of the switch shown in Figure '7. In place of the conical indentations 26 shown in Figures 7 and 8, a series of step-like indentations 2l are used which extend slightly beyond the central axis of the envelope so as to form a zig-zag or tortuous path between mercury pool II and the electrodes II and I2. While the form of construction shown in Figure 9 differs slightly from those shown in the preceding figures in that there is not provided a clear path from one end of the envelope to the other in which the mercury may travel, yet the steps 2l do not actually provide a delay feature, and' the time required for the mercury to travel from one end of the envelope to the other may be regarded as being substantially instantaneous since the steps 21 are spaced far enough apart to merely prevent separated globules of mercury from being thrown directly upward into circuit bridging relationship with electrodes II and I2.
Although numerous changes may become apparent to those skilled in the art, the scope of my invention is defined only by the appended claims.
I claim as my invention:
1. A' mercury switch comprising an enclosed envelope, a plurality of spaced apart electrodes extending through one portion of said envelope, a pool of mercury sealed within said envelope, and a plurality of glass balls sealed within said envelope and freely moveable therein throughout the extent of said envelope to prevent a portion of said mercury from bridging said electrodes when said switch is jarred while in an inactive position, but without impeding the relatively free passage of mercury when said switch is moved between active and inactive positions.
2. A mercury switch comprising an enclosed envelope, a plurality of spaced apart electrodes extending through one endof said envelope, said envelope being partially filled with mercury which in an inactive position of said switch is positioned remote from said electrodes but adapted to move relatively freely in its entirety into and away from contact with said electrodes upon movement of said switch between said inactive and an active position, and splash impeding means positioned within the interior of said envelope and freely moveable therein throughout the extent of said envelope, said splash impeding means being made of an insulating material.
3. An electrically conductive liquid switch comprising an enclosed envelope, a plurality of spaced apart electrodes extending through one end of said envelope, said envelope being partially lled with an electrically conductive liquid which in an inactive position of said switch is positioned remote from Said electrodes but adapted to move relatively freely in its entirety into and away from velope, said splash impedingmeans being made 5 of an insulating material having a density less than that of the liquid.
4. A mercury switch comprising a hermetically sealed cylindrical glass envelope, a plurality of spaced electrodes extending through one end of said envelope, a pool of mercury sealed Within said envelope being situated remote from said electrodes when said switch is in an inactive position, and a nonmetallic member positioned within said switch envelope and freely moveable therein between the ends thereof, said nonmetallic membei' preventing a portion of said mercury from bridging said electrodes when said switch is jarred while in said inactive position but without impeding the rapid iiow of mercury when said switch is moved to an active position.
RAYMOND P. MATTERN.
REFERENCES CITED The following references are of record in the le of this patent:
UNITED STATES PATENTS Number Name Date Re. 19,234 Hendrickson July 10, 1934 1,094,440 Hateld Apr. 28, 1914 1,415,820 Eynon May 9, 1922 1,974,411 Cole Sept. 25, 1934 2,099,483 Hinde Nov. 16, 1937 2,119,944 Mattern June 7, 1938 2,130,500 Lawson Sept. 20, 1938 2,194,873 Schaer Mar. 26, 1940 2,206,436 1940 Spencer July 2,