US2295054A - Electrical switch - Google Patents

Description

Sept. 8, 1942. H. B. RUDD ELECTRICAL SWITCH Filed Dec. 23, 1938 2 Sheets-Sheet 1 INVENTOR ATTORNEYS H. B RUDD ELECTRICAL SWITCH Sept. 8, 1942.

2 Sheets-Sheet 2 \INVENTQR Filed Dec. 23, 1938 BY m/P/FVE E000. AT'fORNEYJ drawingainwhich: I

Batented Sept. 8, 1942 Y UNlTED STATES", PATENT OFFICE I. I Y 2,295,054 uncritical. swrrcn Harry B; Budd, Flushing, N. Y. V meanti e-mm 23, 1938, Serial No. 247,330

8 Claims.

My invention relate to electricalswitches of the delayed-action type.

My invention, in a prominent aspect, has reference to switch arrangements wherein mercury from a pool of mercury is caused to flow through a diaphragm or barrier passage having such small cross-sectional area that th mercury is incapable of flowing therethrough solely under the influence of it'sgravitatlonal'head;

Myinvention, in other prominent aspects, re-

Y Figure l is a perspectiveview illustrating an application of my invention"; i

Fig. 2 is a vertical sectional view, partly in elevation, showing the switch andswitch housing of my invention I Fig. 315 a transverse verticai sectional view, partly in elevation,-t'aken on the lipeH of Fig. 2 looking, in, the direction of the arrows;

FlgAis-a vertical'sctional view, partly in elevation, showing th switch of my invention in one of'its positions;

Fig. .5 is a vertical sectional viempartly in elevation, showing the switch ofmy invention in its normal position; c

Fig. 6 is a horizontal sectional view, partly in plan, taken on the line 6--6 of Fig. 2 looking in the direction of the arrows; Fig. 7 is an enlarged sectional view showing a barrier as constructed in. accordance with my invention;

Fig. 8 is a vertical sectional view, partly in elevation, showing a combined toasterand switch arrangement;

Fig. 9 is an end elevational view of the ar-- rangement shown in Fig. 8; v

Fig. 10 is a vertical sectional view, partly in 8 accompanying Referring particularly to Figs. 25 inclusive, A represents a sealed envelope or switch casing formed from any suitable material such, for example, as glass, a phenol condensation product or the like. As herein shown, the casing A comprises a pair of spaced tubular sections a, a shaped so as to form inner and outer passages I or chambers b, b preferably of arcuate configuration or substantially so and arranged. preferably, in concentric relation with respect to each other. The casing A defines an end passage or chamber d by which adjacent ends of the passages or chambers b, b are placed in communication within each other. The casing A also defines another end passage or chamber 1 by which the other adiacent'ends of said passages or chambers b, b

.are placed in communication with each other.

I As "shown in Figs. 4 and 5, the inner surface of the inner casing section a is shaped to form a horizontal ledge g which is disposed at the Junetion between'ithe inner} passage or chamber b and the chamber 1'.

As'shown in Figs. 4 and 5, the casing end chambersd and {may have associated therewith the respective switch contact members i and 1 which extendthrough and are sealed to the casing wall, the inner ends of these contact members being adapted to physically contact with an electricity-conducting medium disposed interiorly of the casing A and the outer ends of said contact members being adapted to be connected elevation, showing another form of switch: and

Fig. 11 is a transverse vertical sectional view, partly in elevation, taken on the line |Ill of Fig. 10 looking in the direction of the arrows.

in an electrical circuit, for example, as hereinafter described."

In accordance with the invention, the casing A should be mounted for oscillatory movement on a fixed axis and, to this end, an arrangement of any suitable character may be utilized. Thus, as shown, a pair of, clamping members I, i may be suitably flxed to said casing A, as by a bolt 2 l and nut 2a coactable therewith, the bolt 2 extending between the casing-sections a, If Transversely fixed to the clampingmembers I, I is'a shaft 3 which may bejournaled for oscillatory movement in the spaced arms In of a bracket 4 having its base suitably secured to a support" 5 which, in one form of the'invention, may carrya housing 6 forming an enclosure for the casing A and associated parts,

Exteriorly of the housing 6, when utilized, the haft 3 may hav a pointer I and an actuating knob '8 fixed thereto, the pointer l coacting with a scale 9, Fig, l, and the motion of said pointer I in one direction being limited by a stop member I0, or equivalent, fixed, in the example shown,

5.3 to the adjacent surface of the housing 6.

Obviously, with the form of the invention shown in Figs. 1-6 inclusive, the stop member In coacts with the pointer I to define the limit of oscillatory movement of the shaft 3 and the thereby-carried casing A in a counter-clockwise direction, Fig. 5. Preferably, the casing A is biased constantly toward the position thereof shown in Fig. 5 and, to this end, for example, there may be utilized a spring I! which is coiled around the shaft 3, one end of said spring l2 being secured to one of the clamping members i and the other end thereof being secured to the adjacent standard arm in. When the shaft 3 and casing A are moved in a clockwise direction, Fig. 5, energy is stored in the spring l2 and, accordingly, said casing A constantly tends to return to the positicn thereof shown in Fig. 5.

In accordance with the invention as illustrated in Figs. 1-5 inclusive, the casing A contains a suitable quantity of mercury material or other ing end passage or chamber f. This diaphragm k is sealed throughout its entire outer edge surface to the adjacent casing surface defining said last named passage or chamber b so that the flow of mercury through the juncture thus formed is prevented in a positive manner.

The aforesaid barrier k is provided with a passage kl through which mercury is caused to flow. In accordance with the invention, the cross-sectional area of this passage kl, or its diameter if circular, is so small that mercury from a pool of mercury confined in part by said barrier k is incapable of flowing therethrough substantially as a uniform stream under the influence of its head unless the surface tension effect of the mercury in or at said passage kl is overcome. Thus, as shown in Fig. 7, the cross-sectional area .of the passage kl is so small that the head of mercury in the pool thereof at the right of the barrier k is incapable of breaking the surface tension of the mercury in said passage kl to an extent sufficient to insure a uniform flow of mercury through said passage kl.

This surface tension effect of the mercury in the passage kl is overcome in a novel manner,

in accordance with the invention, 50 that the de sired uniform flow of mercury is obtained. Thus,

in Fig. 5. I have shown the casing A in its normal attain a common level unless in the meantime mercury is transferred to the pool at the right of the barrier k by clockwise movement of the casing A on its axis.

With the casing A positioned as shownin Fig. 5, the electrical circuit in which the contact members i and j are included is closed by the column of mercury in the inner passage or chamber b. While said casing A remains stationary in the position shown in Fig. 5, mercury, under the influence of the head of said column of mercury, flows from right to left as a substantially uniform stream through the barrier passage kl. Eventually, the top surface of the mercury in the end chamber 1 descends to such extent that said top mercury surface, separates or breaks at the ledge g whereby said electrical circuit is opened in the pool of mercury and not by recession of the mercury from the contact member 7'. This completes the circuit-opening operation although, if the casing A continues to remain stationary, the two mercury pools will reach a common level. I

At any time after the aforesaid circuit has been opened, the knob 8 may be actuated against the action of the spring l2 to thereby rotate the casing A in a clockwise direction to the position illustrated in Fig. 4, for example. By so doing, mercury is transferred, under the influence of gravity, through the separate passages or chambers b, b'so that it returns to the casing end chamber f. Immediately thereafter, the casing A is returned counter-clockwise to its normal position as shown in Fig. 5 and as defined by the stop member I0. During such return movement of the casing A, there is no transfer of mercury through the outer passage or chamber ball of the transferred mercury congregates in the inner passage or chamber b and in the casing end chamber j. Accordingly, as said casing A returns to normal position as described above, the transferred mercury again closes the circuit between the contact members i and 7'.

When the .casing A is in the position shown in Fig. 4, it will be noted that pools of mercury remain in contact with the respective opposite sides of the barrier k. This is an inventive feature of importance because, by so doing, the surface tension effect illustrated in Fig. 7 may not be established. If necessary, a suitable stop member, not shown, may be provided to prevent such excessive clockwise rotation of the casing A from the position thereof shown in Fig. 4 that would result in draining the mercury from one or both sides of the barrier k.

It will be noted that the outer passage or chamber b is of curved or arcuate configuration. This is a feature of importance because, by so shaping said outer passage or chamber b, desired different quantities of mercury may be transferred therethrough with accuracy so that the circuit through the contact members i and 7' may remain closed for selected different periods of time. Thus, the scale 9 shown in Fig. 1 indicates different positions which the casing A may take when mercury is transferred through the outer passage or chamber b in the manner described above. By properly calibrating said scale 9, it follows that the operator may move the pointer ID to a scale mark indicative of a desired period of closure of the contacts 1' and j.

.The delayed-action switch of my invention is capable of manyapplications and, as illustrative of one of such applications, I have indicated in Fig. 1 a circuit arrangement whereby said switch controls the circuit of a conventional electrical toaster 20 provided with the usual grid-shaped heating element 2| included in the circuit of a pair of conductors in the cable 22, these conductors terminating in the respective prong contacts of a conventional plug 23. As illustrated in Fig. 2, the aforesaid support 5 for the switch casing A may carry a socket 24 to which extends the conductors 25 and 23 secured, respectively, to the switch contact members i and 1. Extending from the socket 24 is a cable 21 comprising a pair of conductors adapted to be associated with the respective conductors of a suitable line circuit 23. It will be understood that the arrange-. ment is such that, after the plug of the cable 21 has been associated with the line circuit, the plug 23 may be associated with the socket 24 to thereby connect both sides of the line circuit to the terminals of the grid element 2i, one side of the line including the switch contact members i and 9' in series therewith.

slices of bread may be disposed in the toaster 20 and the knob 8 rotated in a clockwise direction to a desired scale indication, the'scale, in this instance, preferably being calibrated in terms of light, medium, and well done" toast. When the knob 8 is rotated as just described, the switch casing A is likewise rotated to thereby transfer a desired quantity of mercury into the end chamber 1. While the knob 8 is being returned to its original position, as defined by the stop member II), the switch casing A partakes of similar return movement with the result that the circuit through the grid element 2| is closed, such circuit remaining closed until opened by separation of mercury along the horizontal ledge g of the casing A.

In Figs. 8 and 9, I have illustrated another application of my invention relating to the breadtoasting art. As shown, a toaster 30, generally of conventional design, comprises a base 3| and a casing 32 secured thereto and upstanding therefrom. 'Within the casing 32, the grid-shaped heating element 33 may be supported in suitable manner, one end of this grid element terminating in a contact member 34 and the other end thereof terminating in a contact member 35. The cable 36 which is adapted to be associated with the line circuit comprises a pair of conductors 31 and 38, the conductor 31 being connected to the contact member 34 and the conductor 38 leading either to the switch contact member 1' or the other switch contact member being connected to the contact member 35 by a conductor 39. In this manner, the switch contact members i and 7' are included in series with one side of shaft 3 may be journaled in the casing 40 and a bearing bracket 4| suitably secured to theadjacent wall of the casing 32.

In the example of the invention shown in Figs.

The bi-metallic structure 44 is shown in the position taken thereby when the toaster is in its non-heated condition. When the knob 3 is actuated to prepare toast, thepositicn to which it should be moved may be determined by observation of the pointer I and thescale on the plate 42. This operation of preparing toast causes the bi-metallic structure 44 to move upwardly "and, by the link 43, the scale-bearing member is moved slightly in a counter-clockwise direction, Fig. 9. Accordingly, if further toast is immediately prepared, the operator moves the pointer l to the proper scale indication but, by reason of the described counter-clockwise movement of the scalebearing member 42, a slightly smaller quantity of mercury is transferred along the path therefor in the casing A. In this manner, compensation is effected for the heated condition of the toaster. Obviously, when the toaster again becomes cool, the bi-metallic structure 44 is in the position shown and the scale-bearing member 42, likewise, is in its original position.

It will be understood that within the inventive idea of the arrangement of Figs. 8 and 9, the scale-bearing member 42 may be mounted in fixed position and compensation may be efiected for the heated condition of the toaster by causing the bimetallic structure 44 to impart slight movement to the switch casing A. With respect to Figs. 14 inclusive, I have hereinbefore described a switch of one form as constructed in accordance with the invention. It shall be understood that the novel switch of my invention may take a variety of other forms and, in Figs. 10 and 11, I have illustrated a present preferred switch differing from the one hereinbefore described.

Thus, in said Figs. 10 and 11, I have shown a sealed switch casing Ai which may be constructed of suitable material, for example, as hereinbefore described, said casing l containing a body of mercury M. The casingAl comprises a horizontal chamber section m and a depending curved chamber section n. Communicating with the chamber section m are a pair of spaced contact members 0 and p which, when the casing is in normal position as illustrated in Fig. 10,, terminate below a ridge q extending horizontally across said horizontal chamber section m.

Adjacent the juncture between the horizontaland depending casing sections 1n and 11., there is a barrier or diaphragm r sealed to the adjacent casing surface and having a passagef/rl extending 8 and 9, the pointer 9 coacts'with a scale formed on a plate 42 which is movable to different positions depending upon the temperature conditions interiorly of the toaster 30. As illustrative of one form of movable scale arrangement, I-have shown the scale-bearing member 42 as loosely supported on the shaft 3, Figs. 8 and 9. Secured to and depending from the scale-bearing member 42 is a link 43 which, at its lower end, is connected to a bi-metallic structure 44 suitably positioned within the casing 32 so as to be affected by the heat transmitted thereto from the heating element 33. As herein shown although notnecessarily, the bimetallic structure 44 is disposed just above the top wall of the base 3| and one end of said bimetallic structure 44 is suitably secured to said base 3i, as by the bolt 45 and nut 45a.

therethrough. At the side 'of the diaphragm removed from the chamber in which the switch contacts 0 and p are received, the casing is shaped upwardly as indicated at s. The barrier r comprises a downwardly extending section r2 utilizableas hereinafter described.

It shall be understood that the casing Al of Figs. 10 and 11 will have associated therewith a clockwise rotation of the chamber Al causing the transfer of mercury from the depending casing.

chamber 71 to the horizontal casing chamber m along a path extending above the barrier r, or

through a passage in said barrier in case the lat ter extends entirely across the casing AI. Therefore, as the casing Al is shown in Fig. 10, mercury cleanly condition.

flows substantially as a uniform stream through the barrier passage rl in a direction from right to left, such mercury first entering the chamber defined in part by the aforesaid casing section s and then dropping downwardly into the casing chamber n. Eventually, the upper surface of the pool of mercury in the casing chamber m separates at the ridge q to thereby open the circuit to which the contact members and p are connected.

The cross-sectional area of the barrier passage rl is of the same general value as hereinbefore described with respect to the barrier passage kl of the barrier is. That is, mercury from the pool of mercury shown in the casing chamber m is incapable of flowing through said barrier passage sl under the influence of its gravitational head unless the surface tension effect of the mercury in or at said passage rl is overcome. In order to overcome the effect of surface tension in the barrier passage rl, I provide, in accordance with the invention, the chamber defined in part by the aforesaid upwardly extending casing wall s. As indicated in Fig. 10, this chamber last named serves as a reservoir containing a pool of mercury which covers the exit side of the barrier passage rl.

During clockwise rotation of the casing Al from the position thereof'shown in Fig. 10, the depending section r2 of the barrier r serves to entrap the mercury contained in the chamber defined in part by the aforesaid casing wall s, the exit side of the barrier passage rl being uncovered by the mercury which moves into the space defined by said depending barrier section 12. However, as the casing Al is returned counterclockwise to its normal position, the mercury thus entrapped returns to its chamber at the left of the barrier rand effectively prevents the development of any surface tension effect at the barrier passage r2 which would prevent passage of the mercury therethrough substantially as a uniform stream.

With respect to the forms of my novel switch as disclosed, the passage of the mercury through the barrier passage serves to lower the level of the mercury pool into which the switch contacts extend so that the circuit connected to said switch contacts may be opened. It shall be understood that, as well, the arrangement may be such that the mercury, as a result of the passage thereof through the barrier passage, serves to close a circuit rather than open the same. Thus, for example, with the switchshown in Figs. and 11, it will be understood that the switch contact member 0, for example, may be removed from the position shown and mounted so that it extends into the depending casing chamber n at a proper level above the bottom thereof.

As hereinbefore stated, the casings A and Al are sealed. Preferably, before this sealing operation, the switch casings of my invention have the atmospheric air evacuated therefrom, such air being replaced by a suitable inert gas such, for example, as hydrogen gas which serves to quench the spark and to keep the mercury in a Ordinarily, it is desirable for this inert gas to have a pressure exceeding atmospheric pressure by several pounds.

The hereinbefore described barriers or diaphragms may be formed from any suitable material which is non-combinable with mercury such, for example, as nickel, stainless steel, or equivalent. These diaphragms or barriers necessarily are relatively thin particularly in the area thereof provided with the passage to be traversed by mercury. It has been demonstrated in practice that the thickness of the barrier may be of we order of 0.002 of an inch and that the diameter of the passages kl or rl therethrough may be of the order of 0.010 of an inch. It shall be distinctly understood that my invention is not to be limited in these respects. Thus, the thickness of the diaphragm or barrier may vary within rather wide limits and the same is true of the cross-sectional area of the diaphragm or barrier passages kl and rl. With respect to the latter, it will be understood that my invention relates to a condition such as shown in Fig. 7 wherein the gravitational head of the mercury pool is incapable of breaking the surface tension existing at the barrier passage so as to cause uniform flow of the mercury.

It shall be understood that the delayed-action switches of my invention may be of such character that a constant quantity of 'mercury is transferred from one side of the barrier to the other when effecting the re-setting operation by rotatable movement applied to the switch casing. With this arrangement, the various control periods are of the samfev duration. This is a desirable feature in connection with some applications of the invention.

Although I have illustrated and described the novel switch of my invention as utilizable in a particular art, namely, the bread-toasting art, it shall be distinctly understood that my invention, by no means, is-to be thus limited. The delayed-action switch of my invention is capable of use as a control for a large variety of electrical circuits. That is, the novel switches of my invention may be utilized for timing purposes generally such, for example, as the timing of camera exposures, photo-composing machine exposures, traffic lights, other electrical apparatus, etc., etc.

A particularly important advantage of my invention resides in the fact that my switch comprises a diaphragm or barrier passage having cross-sectional area so small that the mercury is incapable of flowing therethrough under the influence of its head unless the surface tension effect of the mercury in or at said passage is overcome. Accordingly, even though the switch comprises a relatively small quantity of mercury, the operation thereof may be delayed over relatively long periods of time. The switches of my invention, then, are of lighter weight, smaller, require less mercury, etc. than do prior art delayed-action switches.

While the invention has been described with respect to certain particular preferred examples which give satisfactory results, .it will be understood by those skilled in the art after understanding the invention, that various changes and modifications may be made without departing from the spirit and scope of the invention and it is intended therefore in the appended claims to cover all such changes and modifications.

What is claimed as new and desired to be secured by Letters Patent is:

1. In a switch of the character described, a casing, a body of mercury in said casing, and a barrier secured interiorly of said casing to form side-by-side chambers therein, said barrier being provided with a passage through which mercury may flow and the' cross-sectional area of said passage being so small that mercury is capable of flowing therethrough as a substantially-uniform stream only when there are pools of mersponse to movement of said casing on its axis,

said casing being selectively movable on its axis diiierent' distances from the normal position thereof whereby diflerent respective quantities of mercury may be passed along said path, and means for passing mercury in reverse direction between said chambers, said means comprising a diaphragm passage having a cross-sectional area so small that mercury is capable of flowing therethrough as a substantially uniform stream only when there are pools of mercury on the respective opposite sides of the diaphragm which cover both sides of said passage.

3. In a switch of the character described. a casing having a normal position, means forming an axis on which said casing is mounted for oscillatory movement, a body of mercury in said casing, said casing having therein a plurality of chambers joined by a path for passing mercury from one chamber to the other chamber in re-t sponse to movement of said casing on its axis, said casing being selectively movable on its axis diflerent distances from the normal position thereof whereby different respective quantities may be passed along said path, said path comprising a curved section serving to facilitate regulation of the quantity of mercury I thus passed along said path, and means for passing mercury in reversedirection between said chambars, said means comprising a diaphragm passage having a cross-sectional area so small that mercury is capable of flowing therethrough as a substantially uniform stream only when there are pools of mercury on the respective opposite sides of the diaphragm which cover both sides of said passage.

HARRY B. RUDD.

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