US2299346A - Switch - Google Patents

Description

Patenied oct. 2o, 1942 SWITCH Ernst Walter Rickmeyer, Elmhurst, Ill.,assignor to Jefferson Electric Company, Bellwood, Ill.,

a corporation of Illinois Application January 2, 1942, Serial No. 425,393

(Cl. ZIN-152) 8 Claims.

This invention relates to switches, and more particularly to switches in which a fluid contacting element is utilized to make and break an electrical circuit.

In switches utilizing a fluid contacting element, such as mercury, a small operating angle for eiecting the Control of the ilow of mercury b-etween the circuit making and breaking positions is often desirable. Also, due to the inherent surface tension of mercury or other similar fluid contacting elements and the desirability of effecting the making and breaking of the electrical circuit between mercury surfaces, it is important that the mercury in the switch is separated while remaining in contact with a suflicient surface of mercury contacting electrodes of the switch to minimize the contact resistance of the switch.

An object of this invention is to provide a switch in which a fluid contacting element is utilized to make and break an electrical circuit, and

in which a very small angular movement of the switch is required to effect the making and breaking of the circuit.

Another object of this invention is to provide a switch in which a fluid contacting element having high surface tension characteristics is uti-l lized to make and break an electrical cir-cuit, and in which contact is made and broken between quantities of the contacting fluid while keeping ,l suiiicient quantities of the iiuid in contact with the switch electrodes to keep the contact resistance of the switch low.

Another object of this invention is to provide a mercury switch having a metal enclosing shell which serves as one electrode of the switch and including fixed and movable bodies of mercury between which the circuit is made and broken, the switch design being such that the Xed body of Vmercury has a relatively large area of contact with one electrode and is coni-ined in such a way that retention of the xed quantity in place is insured.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawing wherein a preferred embodiment of the present invention is clearly shown.

In the drawing:

Figure 1 is a side sectional View of a switch embodying a preferred form of the present invention;

Figures 2 and 3 are sectional views of the switch shown in Figure 1 with the sections taken respectively on the lines 2-2 and 3 3 of Figure 1 and viewed in the direction indicated by the arrows;

Figure 4 is a perspective view of a part of the switch shown in Figure 1;

Figure 5 is a side sectional View of a, switch embodying a modified form of the present invention;

Figures 6 and 7 are sectional views of the switch shown in Figure 5, with the sections taken respectively on lines 6-6 and 'I-l of Figure 5 and viewed in the direction indicated by the arrows; and

Figure 8 is a perspective View of a part of the switch shown in Figure 5.

Having particular reference to Figures l to 4 inclusive, the switch disclosed has a metal outer shell I6 which provides a housing for the switch and serves as one of the electrodes. This outer shell or housing I Il is preferably made of substantially or commercially pure soft iron which does not contain impurities which would effect amalgamation or oxidize or corrode. Also, at least the inner surface is preferably thoroughly cleaned so that all oxide iilm 4and impurities are removed at the time the switch is assembled. The housing or shell II] has a closed end I2 and an open end I3, and is preferably lined with insulating material, such as ceramic material at the closed end I2 and to a position near the open end I3. The insulating or ceramic lining, for convenience in manufacture, preferably comprises adjoining parts I4 and I5. The lining part I5 is preferably a hollow sleeve in which an inner opening I6 which extends therethrough is tapered to be larger near the open end of the shell than near the closed end of the shell. The lining piece I4 has a recess or depression I'I which is in alignment with the end of the opening I6 of the lining part I57 and has a channel I8 which extends from the recess Il to the inner wall of the shell Ill. The end of the lining part I5 is closely abutted against the inner end of the lining part I4 and provides a sharp angular edge at I9 adjacent the channel I8.

An inner electrode 20 has a disc-like end portion 22 which abuts against and is located by a shoulder 23 on the lining part I5 near the open end of the shell I0 and is separated from the shell by a liange 24 on the end of the lining part I5. The electrode 20 has an integral tongue portion 25 which conforms to and extends inwardly along the surface of the inner opening It in the lining part I5 to a position near the edge I9 at the inner end of the opening I6. A terminal member 26 has a stem 28 which projects from the open end of the shell lil and has its outer surface threaded at 29 for making electrical connections thereto. The stem preferably has an opening 30 therein in alignment with an opening 32 in the end portion 22 of the electrode 2l) which communicates with the switch chamber provided by the opening I6. An insulating washer 33 lits snugly into the open end of the shell I0 and snugly around the stem 28, and abuts against the outer surface of the disclike portion 21 of the terminal member 26. This insulated washer is preferably made of relatively soft rubber which expands upon the application of pressure thereto to provide a gas-tight seal. A second insulating washer 34 of relatively rigid insulating material covers the outer end of the insulating washer 33 and is pressed in position by a metallic washer 35 against which the end surface of the open end of the shell I is swedged or rolled as at 36 to hold the switch parts in assembled relation and apply sealing pressure to the washer 33. 'Ihe washer 35 has a large opening 36 through which the stem 23 extends in spaced relation thereto.

A quantity of mercury is enclosed in the switch chamber, a portion 371 of which is normally trapped in the channel I8 and a portion 38 of which is movable along and in contact with the tongue portion 25 of the inner electrode 2B upon tilting of the switch to make and break a circuit between the inner electrode 29 and the outer electrode or shell i0 through the portion 31 of the mercury. The longitudinal dimension or width of the channel i8, as viewed in Figure 1, is such that the trapped portion of the mercury 31 extends substantially meniscus height above the edge I9. The depth of the channel i3 is such, and is so related to the longitudinal dimension thereof that the trapped quantity of mercury is stable and will remain in the channel during movements of the switch throug-h any normal operating angles. The side walls of the channel I8, as viewed in Figure 3, are preferably substantially radial with respect to the shell iii or diverge outwardly toward the shell to provide a large surface area of contact between the trapped quantity of mercury 31 and the shell il Since the trapped mercury 31 is retained and stable, and since the edge I9 is sharp, the making and breaking of Vthe circuit occurs between the two bodies of mercury, rather than between a body of mercury and one of the electrodes when the switch is moved through normal operating angles.

After the mechanical assembly of the switch, it is preferable that the air is pumped from the interior of the switch through the openings 3i! and 32, and that the switch is then lled with non-oxidizing gas, such as hydrogen, under a pressure sufficient to minimize arcing. After the gas lling, a plug 39 is pressed linto the opening 3i) -to complete the sealing of the switch chamber. This prevents oxidation or corrosion of the mercury and limits the arcing between the bodies of mercury when the circuit is opened and closed by the switch.

Having particular reference to Figures to 8 inclusive, parts bearing reference numerals similar to those used in the description of Figures 1 to 4 inclusive are similar and Vperform substantially similar functions. The switch shown in Figures 1 to 4 inclusive is wha-t is called ya one position switch. With this type of switch, the electrode and the channel I8 should be on the bottom, when the switch is in an operative position, so that the movable portion of the mercury 38 moves along the surface of the inner electrode and into and away from engagement with the trapped portion of the mercury 31. The switch shown in Figures 5 to 8 inclusive is adapted to operate in any position about its longitudinal axis in which it may be placed for operation.

In the switch shown in Figures 5 to 8 inclusive, the metallicshell l0 has therein a cylindrical insulating sleeve 39 made of a material such as a ceramic. An opening 4E) extends longitudinally through the sleeve and has a cylindrical metallic electrode 42 mounted therein which extends from the end of the insulating sleeve 39 which is near the open end I3l of the shell to a position near but spaced from the other end of 4the insulating sleeve 39. A second insulating lining part 43 which is also preferably made of ceramic material ts into the closed end I2 of the shell I@ and preferably has a plurality of integral feet 44 thereon which are preferably small in comparison with the surface of the insulating part and serve to space the second insulating lining part 43 from the end of the insulating sleeve 39 to provide a circumferential channel 45 within the shell IJ, in which channel a quantity of mercury 31 is trapped. This channel 45, like the channel I8 in Figure 1, is so proportioned that the trapped mercury 31 extends substantially meniscus height above an edge 46 at the end of the insulating sleeve 39 and is stable. The edge 46 is preferably angular and sharp, so that with the stable body of mercury 31 trapped in the channel 45 in contact with the shell I3, the cir- -cuit through the switch is made and broken between the trapped and movable quantities of mercury at or near the edge 45. Since the feet 44 are small and are widely spaced apart, the rotation of the switch about its longitudinal axis does not prevent the trapped mercury 31 from remaining in contact with the shell l0. Also, since the electrode 4.2 is cylindrical, the movable quantity of mercury 38 remains in contact with that electrode as the switch is rotated about its longitudinal axis.

The electrode 42 preferably has a flanged -edge 41 which engages a shoulder 43 on the insulatin-g sleeve 39. Also, the hanged edge 41 and the disc-like portion 21 are spaced and insulated from the metallic shell I3 by an extending flange 49 on the insulating sleeve 33. The sealing and preferable gas .filling of the switch are substantially the same as described in connection with the switch shown in Figures 1 to l inclusive.

, I'he structure of both switches is such that they lend themselves well to operation with only small angular movements which eiect the operation.

While the embodiment of the present invention as herein disclosed, constitutes a preferred form, it is to be understood that other for-ms might be adopted, all coming within the scope of the claims which follow.

I claim:

1. A mercury switch comprising, in combination, a cylindrical 'metal shell providing one electrode and having a closed end and an open end, a lining of insulating material fitting into said shell and having an open end adjacent the open end of the shell, said lining having an opening between the ends thereof and near the closed end of the shell, said opening beiner dened by substantially parallel end walls and side walls which are substantially radial with respect to the cylindrical shell, a second electrode insulated from the metal shell by said lining and extending inwardly along the lining from near the open end of the shell, means closing the open end of the shell exterior of the lining and electrode means for making an electrical connection to the second electrode, and a lquantity of mercury within the closed shell, said quantity of mercury being sufcient to provide a stable body in said opening in contact with the shell, and a movable body adaptedto bridge the gap between the Istable body and the second electrode and cover a portion of the surface of the second electrode While bridging said gap and when said shell is disposed at a predetermined angle.

2. A mercury switch comprising, in combination, a cylindrical metal shell providing one electrode and having a closed end and an open end, a lining of ceramic material having an cuter surface contiguous to the inner surface of the shell and having an open end adjacent the open end of the shell, said lining having a pair of end walls spaced apart to provide an opening near the closed end of the shell and having an axially extending adjoining opening, a second electrode tting into and closing the open end of the lining and having a portion extending toward the first mentioned opening, means closing the open end of the shell exterior to the second electrode and lining, means for making an electrical connection to the second electrode, a quantity of mercury within the shell and lining, said pair of end walls being spaced by an amount such that a stable quantity of mercury is trapped therebetween in contact with the shell, and said quantity of mercury being such as to provide a movable body adapted to bridge the space between the second electrode and said stable quantity of mercury when the shell is disposed at a predetermined angle.

3. A mercury switch comprising, in combination, a cylindrical metal shell providing one electrode and having a closed end and an open end, an insulating lining within said shell including a pair of cooperating parts, one of said parts being hollow and having an inner surface tapering outwardly toward the open end of the shell, means integral with one of said parts spacing the pair of parts to provide an o-pening therebetween, a second electrode extending along the inner surface of said hollow part and having an end spaced from said opening, means closing the open end of the shell exterior to the second electrode and lining, means for making an electrical connection to the second electrode, and a quantity of mercury within the closed shell, the spacing of said parts and the quantity of mercury being such that a body of mercury is retained in said opening between the parts and in contact with the shell and a second body of mercury is movable into and out of bridging engagement between the retained body of mercury and the second electrode.

4. A mercury switch comprising, in combination, a hollow metal shell providing one electrode and having a closed end and an open end, an insulating lining within the shell including a pair of cooperating parts, one of said parts being tubular, means intermediate the parts and spacing the parts to provide an opening therebetween, a second electrode extending along the inner surface of the tubular part and having an end spaced from the opening, insulating means closing the open end of the shell exterior to the second electrode and lining, means extending through the insulating means for making an electrical connection to the second electrode, and a quantity of mercury within the closed shell, the spacing of said parts and the quantity of mercury being such that a body of mercury is retained in said opening between the parts and in contact with the shell and a second body of mercury is movable into and out of bridging engagement between the retained body of mercury and the second electrode.

5. A mercury switch comprising, in combination, a hollow metal shell providing one electrode and having a closed end and an open end, an insulating lining within the shell including a pair of cooperating parts, one of said parts being tubular, means comprising a plurality of spaced iingers intermediate the parts and spacing the parts to provide an opening therebetween, a second electrode comprising a tubular conductive element extending along the inner surface of the tubular part and having an end spaced fromv the opening, insulating means closing the open end of the shell exterior to the second electrode and lining, means extending through the insulating means for making an electrical connection to the second electrode, and a quantity of mercury within the closed shell, the spacing of said parts and the quantity of mercury being such that a body of mercury is retained in said opening between the parts and in contact with the shell and a second body of mercury is movable into and out of bridging engagement between the retained body of mercury and the second electrode.

6. In a mercury switch, the combination comprising a metallic shell, a quantity of mercury, a lining of insulating material iitting into the shell and having two cooperating parts, one of said parts being tubular, said parts having an opening therebetween, and said tubular part having a relatively sharp edge adjacent said opening, the dimensions of said opening being such that mercury trapped therein contacts the shell and extends substantially meniscus height above said edge.

'7. A mercury switch adapted to make and break an electrical circuit upon movement to predetermined angular positions and comprising, in combination, a metallic shell providing one electrode and having a closed end and an open end, an insulating lining within the shell having an opening therethrough, a second electrode insulated from the shell and extending toward said opening from the open end of the shell, means closing the open end of the shell, means for making an electrical connection to the second electrode, a quantity of mercury within the closed shell, a portion of said mercury being disposed in said opening in contact with the shell and the remainder being adapted to move within the shell to make and break an electrical circuit between the electrodes, said opening, said second electrode and the quantity of mercury being such that the areas of contact of the mercury with each of the electrodes is larger than the cross sectional area of the mercury when said mercury makes the circuit between the electrodes.

8. A mercury switch comprising, in combination, a metal shell open at one end and closed at the other end, said shell serving as one electrode of the switch, a quantity of mercury Within the shell, means retaining a, substantially iixed quantity of mercury in contact with the shell in a xed position, a second electrode insulated from the shell and extending into the shell toward the retained mercury, a movable body of mercury in contact with the second electrode and adapted to electrically connect the second electrode and retained mercury, means closing the open end of the shell, and means for making an electrical connection to the second electrode.

ERNST WALTER RICKMEYER.

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