US1951162A - Time delay mercury switch - Google Patents

Description

March 13, 1934. oos

TIME DELAY MERCURY SWITCH Filed March 25, 1932 2 Sheets-Sheet l ATTORNEY March 13, 1934. F. Moos 1,951,162

TIME DELAY MERCURY SWITCH Filed March 25, 1932 2 Sheets-Sheet 2 clglVENTOR cf/omZ/ 733001/ C ATTORNEY Patented Mar. 13, 1934 TIME DELAY MERCURY SWITCH Frank Moos, Jersey ility, N. 5., assignor to General Electric Vapor Lamp Company, Hobokcn, N. it, a corporation of New Jersey Application March 25, 1932, Serial No. 601,232

7 Claims.

The present invention relates to fluid flow switches and particularly to switches of the time delay type.

The invention consists in a fluid flow switch having the unique construction and the novel features hereinafter set forth and claimed.

A particular object of the invention is to provide a fluid flow switch in which either the circuit closing or the. circuit opening is accurately delayed for a predetermined time. Another object of the invention is to provide a structure for a switch of this type which can be easily duplicated to give identical time delay periods. Still other objects and advantages of the invention will appear from the following detailed specification, or from an inspection of the accompanying drawings.

Various attempts have been made heretofore to utilize restricted flow in a fluid flow switch to secure a delayed operation of the switch. Difficulty has always been encountered, however, in producing a switch of this type having an exact, predetermined, time delay, especially in switches having sealed vitreous envelopes in which the variations in physical dimensions are inevitably large, with the result that it has been impossible heretofore to obtain uniformity in this type of switch by any practicable manufacturing procedure. Hence this type of switch has never gone into the extensive use that its advantages merit. I have now discovered that by the use of an inner vessel of a type which can be easily duplicated a constant and predetermined time delay may be obtained, regardless of reasonable variations in the vitreous envelope into which it is sealed. This vessel, according to my novel invention, accurately measures the fluid flow and thus inherently causes the circuit to be made or broken after the exact time delay desired. This structure is easily reproducible by ordinary manufacturing methods, and hence is extremely inexpensive as well as highly satisfactory. For the purpose of illustrating my invention I have shown several embodir ments thereof in the accompanying drawings, in

which Fig. 1 is an elevational view, in part section of a mercury switch of the delayed closing type, showing the mercury in the process of closing the circuit therethrough,

Fig. 2 is a similar view of the same switch in the open circuit position,

Fig. 3 is a sectional view of the same switch taken on the line 3-3 of Fig. 2,

Fig. 4 is an elevational view, in part section,

(01. soc-es) of a mercury switch of the delayed opening type, in the circuit opening position,

Fig. 5 is a sectional view of a modification of the switch of Fig. 1,

Fig. 6 is asectional view taken on the line 0 6-6 of Fig. 5,

Fig. 7 is a sectional view of another modification of the switch of Fig. 1,

Fig. 8 is a sectional view of a modification of the switch of Fig. 4,

Fig. 9 is a sectional view taken on the line 99 of Fig. 8,

Fig. 10 is an elevational view, in part section, of another modification of the switch of Fig. 1, shown in a circuit closing position, and

Fig. 11 is a similar View of the same switch in an open circuit position.

In these drawings, with particular reference to Figs. 1-3, my novel switch has a tubular envelope 1 of any suitable vitreous material such as lead or lime glass, or a borosilicate glass if a more refractory envelope is desired. The inleads 2 and 3, of any suitable metal, are sealed into said envelope 1 through a conventional stem press at one end thereof. The inlead 2 extends along the bottom of said envelope 1, the end thereof being welded to -a metal trough 4 which lies on the bottom of said envelope. Said trough, which may be made of iron, chrome-iron alloy, or other metal which does not readily amalgamate with mercury, has a curvature which is approximately that of the inner wall of the envelope '1, and a depth which approximates the radius thereof. One end of said trough is closed, this end preferably being close to the end of said envelope which is opposite the stem press, while the other end of said trough is open. A sloping battle 5 which is welded to said trough at a point intermediate the ends thereof to form a vessel of predetermined content has a small opening 6 therethrough close to the bottom thereof. Said bafile slopes upwardly away from the closed end of said trough 4 where a delayed circuit closing is desired. The inlead 3 extends along the envelope 1 above the trough 4 to a point near the closed end thereof, and then turns downwardly to a point which is slightly below the level of said closed end when said switch is in the circuit closing position, as shown in Fig. 1. Said inlead 3 is preferably coated with glass or other vitreous insulation to a point near the bend therein. A quantity of mercury 7 which is sufficient to fill the space behind the baffle 5, but no more, when the switch is in the circuit opening position shown in Fig. 1, is enclosed within said envelope 1. An llO are suppressing atmosphere of hydrogen or the like is also preferably sealed within said envelope.

In the use and operation of this switch, assuming it to be in the open circuit position shown in Fig. 2, the switch is abruptly tilted to the position shown in Fig. 1 in order to close the circuit therethrough. The entire amount of the mercury 7 is thereupon trapped behind the bafile 5 and forced to flow through the restricted opening 6. The mercury flowing through this opening forms a pool I which rests against the closed ends of the trough 4, the level of this pool gradually rising until it makes contact with the end of the inlead 3 after a predetermined time of the order of several seconds, closing the circuit through the switch. Further mercury flow after this is, of course, immaterial aside from its effeet in lessening the resistance of the circuit through the switch. So long as the switch is left in this position the circuit therethrough obviously remains closed. Since the mercury pool '7 is thus formed within a vessel which may easily be preformed with a constant volume, and since the relation of the inlead 3 with respect to this pool may be easily adjusted before the stem press carrying the entire inlead assembly is sealed into the envelope 1, it is obvious that the time delay may be accurately predetermined, regardless of reasonable variations in the diameter of the envelope 1 or of the position of the trough 4 therein. As a result switches having this construction may be manufactured without difiiculty with complete uniformity of the producta result which has not been heretofore attainable in time delay switches having vitreous envelopes.

To open the circuit through this switch the envelope 1 is abruptly tilted to the position shown in Fig. 2, whereupon the mercury '7 flows over the sloping baffle 5 without hindrance, opening the circuit through the switch instantaneously, and resetting the switch for the delayed closing operation previously described.

Variations in the time delay of this switch may obviously be produced by varying the size of the opening 6, by extending the end of the inlead 3 (or by moving it nearer to the closed end of the trough 4), by varying the depth of the trough 4, or by varying the diameter of trough 4. All of these variations are easily controlled before the inlead assembly is fused into the envelope 1, so that duplication of the result is easily attained, whatever time delay is desired.

The switch shown in Fig. 4 is in many respects identical with that shown in Figs. 1-3, the trough 4 being supported in the envelope 1 by the inlead 2 in the same manner as previously described. The sloping baffle 5 is reversed, however, to slope upwardly toward the closed end of the trough 4. The inlead 13 extends above said trough 4 to a point just beyond the upper end of said baffle 5, and then downwardly toward the bottom of the trough 4, terminating far enough therefrom, however, to avoid any retention of a mercury globule therebetween. Said inlead 13 is preferably coated from the seal to the point where it bends downward. A quantity of mercury 7 which is preferably in excess of that which will be retained behind the bafile 5 when the switch is in the position shown in Fig. 4 is provided within the envelope 1. A suitable arc suppressing atmosphere is also preferably sealed within said envelope.

Assuming the switch of Fig. 4 to be in the closed circuit position, upon tilting it to the position shown in Fig. 4 any mercury '7 in excess of that which can be retained by the baflie 5 slops over the top of said baffle, leaving an accurately measured pool of mercury 17 behind the baffle. The mercury contained in this pool slowly escapes through the opening 6, lowering the level of said pool until it falls away from the electrode 13, opening the circuit through the switch after on exactly predetermined time. The amount of mercury in this switch should be suflicient to form the desired pool 17 and it is also desirable that it should be sufficient to begin to cover the opening 6 during the circuit opening operation while the pool 17 still has appreciable head, since it has been found that this makes the continued flow of said pool 17 more certain, dash lines indicating the preferred final mercury level. The time delay period of this switch may obviously be varied at will in the same manner as in the delayed closing switch previously described. Likewise the delay period may be accurately controlled without difliculty to produce a highly uniform product.

In some cases it is desirable to make and break the circuit between fluid pools, in order to avail of the higher current capacity of a switch having this type of make and break. The switch of Figs.

and 6 shows how the switch of Fig. 1 may be modified to produce this result. In this switch the tubular envelope 21 has therein a vitreous or refractory body 24 which has substantially the same shape as the trough 4 of the switches previously described, plus a barrier 28 forming a cup 29 at the closed end thereof into which extends inlead 23. A sloping baIIle 25, having an orifice 26 near the bottom thereof is fixed within the body 24 near the open end thereof in any suitable manner. For example, this battle may be inserted within a suitable sloping groove in the body 24, being cemented therein if desired; or as an alternative it may be made integral with said body. The inlead 22 extends downwardly into contact with the bottom of said body 24 at a point between the baffle 25 and the barrier 28 and serves to fix the position of said body within the envelope 21. Mercury 27 is contained within said envelope 21 in an amount similar to that provided in the switch of Fig. 1, plus that required to fill the cup 29. With this construction it is obvious that the delay period is fixed by the shape of the vitreous body 24 and by the size of the orifice 26, and is wholly unaffected by any variations which may occur during assembly and fusion of the various parts of the switch.

In the use and operation of the switch of Figs. 5 and 6, assuming the switch to be in the open circuit position shown, the switch is tilted abruptly to a circuit closing position which is similar to that shown in Fig. 1. All of the mercury 27 (except that in the cup 29) is then trapped behind the baffle 25. This mercury slowly flows through the orifice 26 gradually rising about the inlead 22 until after an exactly predetermined time delay it overflows the barrier 28 and merges with the mercury retained in the cup 29 closing the circuit through the switch. Upon returning the switch to the position shown in Fig. 5 the mercury 27 passes over the top of the baille 25 without hindrance, causing it to separate over the barrier 28 from the mercury which is retained by the cup 29, opening the circuit through the switch and resetting for another circuit closing after a definite delay period, as hereinbefore described.

A further variation of theswitch of Figs. 1 and 5 is shown in Fig. 7. In this switch the trough 34 has a sloping end, in which there is an orifice 36, in place of the open end shown in the previous 100 rid the switch of Fig. 1.

figures. This trough,-which may be easily drawn from sheet metal, thus takes the place of the combined trough 4 and baffle 5 of the switch of Fig. 1, for example, and offers some economy in the manufacture of these switches. A vitreous or refractory cup 39, which may be formed of glass, porcelain, lavite, fused silica, or the like,

is placed within said trough 34 and against the squarely closed end thereof. The inlead 33 extends into said cup 39, and serves to hold both the trough 34 and said cup in fixed position within said envelope 21. The inlead 32 extends into said trough 34 at a point between the sloping end thereof and the cup 39. The operation of this switch is obviously identical with that of the switch of Fig. 5, and hence will not be further described.

Figs. 8 and 9 show how the switch of Fig. 4 may likewise be modified to give a mercury-tomercury make and break. In this modification the tubular envelope 41 has the inleads 42 and 43 sealed into one end thereof through a pinch seal. The inlead 42 is welded to a metal trough 4 in which there is welded a sloping bafilc 5, as in Fig. 4. The inlead 43 extends past said baffle and then curves downwardly into a vitreous cup 49 .which it holds in position within said trough 4.

This cup is made relatively narrow, as shown in Fig. 9, so as to not materially interfere with mercury flow thereby. The inlead 43 is preferably coated from the seal to a point within the cup 49 in order to prevent undesired closings of the circuit through the switch. Mercury 47is supplied within the switch envelope, the amount thereof being similar to that employed in the switch of Fig. 4. An inert arc suppressing atmosphere of hydrogen, ammonia, or the like is preferably used in this switch, as in each of the switches previously described.

In the operation of the switch shown in Figs. 8 and 9, assuming the switch to be in the open circuitposition shown in Fig. 8, when the switch is tilted to the proper angle in the reverse direction the mercury flows over the top of the bafile 5 without hindrance and at once merges with the mercury pool retained in the cup 49, closing the circuit through the switch. Upon returning the switch to the position shown in Fig. 8 a measured quantity of the mercury 1 is retained behind the baflle 5, any excess flowing over the top thereof. This measured quantity slowly flows through the orifice 6, with a gradual lowering of the mercury level about the cup 49 until after an exactly predetermined interval the mer cury 4'7 separates over the rim of said cup 49 from the mercury pool within said cup, opening the circuit through the switch. Thus the circuit is both made and broken between mercury pools in a switch which is easily duplicated by ordinary manufacturing methods.

Each of the switches so far described has had an exact time delay in either the opening or the closing of the circuit, but not both. In some cases it is desirable, however, to delay both the opening and the closing by exactly timed intervals. My novel structure can also be employed to produce this result, a switch for this purpose being shown in Figs. 10 and 11. In this switch the sealed tubular envelope 1, containing a suitable arc suppressing atmosphere, has a trough 4 held therein by the inlead 2 in the same manner as At a point intermediate the ends of said trough 4 there is welded a transverse bafile 55, near the bottom of which there is a small orifice 56. Mercury 57 is sealed within said envelope, said mercury being sufficient in amount to approximately fill the vessel formed by the baflle 55 and the closed end of said trough 4 when said switch is in the position shown in Fig. 10, or when it is first turned to the position shown in Fig. 11, but no more, as shown by dash lines in each of these figures. The inlead 53 extends above the trough 4, turning downwardly thereinto close to the bafile 55. While the lower end thereof approaches the bottom of said trough, it avoids the line of flow of mercury through the orifice 56, either by terminating above said orifice, or through being located at one side thereof. The relative delay periods in closing and opening the circuit are, of course, determined by the position of said inlead 53 with respect to said trough and bailie, the arrangement shown giving the maximum delay for each operation. Movement of said inlead 53 toward the closed end of said trough 4 will shorten both the delay periods, while such a movement, accompanied by a proportionate shortening of the inlead to keep it at a constant position with respect to the mercury level when the switch is in the position shown in Fig. 10 will maintain the closing delay constant, but will decrease the circuit opening delay. Thusany desired ratio may be produced, and both delay periods exactly predetermined, before the assembly is fused into its enclosing envelope, as in each of the switches previously described.

In the operation of this switch, when the envelope l is tilted to the position shown in Fig. 10 the mercury 57 is all trapped above the baffle 55, and slowly flows through the orifice 56 therein, forming a pool therebelow which gradually increases until it reaches the level indicated by the dash line and makes contact with the end of the inlead 53 after an exactly predetermined time delay, closing the circuit through the switch. Upon tilting the switch to the position shown in Fig. 11 the mercury 57 is again all trapped behind the balile 55, as indicated by the dash line, and slowly flows through the orifice 56 until the level thereof falls below the end of the inlead 53 after an exactly predetermined time, opening the circuit through the switch. Thus both the opening and the closing of the switch are delayed for an exact time.

In each of the switches herein described. it is obvious that the timing of the delay periods is entirely determined by the relation of parts of the structure which may be adjusted to their final relative position before sealing into the vitreous envelope, and that the delay period is thus independent of any variations which may result from the fusing process; or from reasonable variations in the dimensions of the vitreous envelope. Thus my novel structure completely avoids the defects produced by such uncontrollable variations in the switches of the prior art, and permits the mass production of mercury switches having a uniform and perfectly controllable time delay.

While I have described my invention by reference to specific examples thereof, it is obvious that it is not limited thereto, but that various changes, omissions, and substitutions, within the scope of the appended claims, may be made therein without departing from the spirit thereof.

I claim as my invention:

1. A fluid flow switch of the time delay type comprising a sealed envelope of vitreous material, inleads sealed thereinto, an electrically conducting fiuid in said envelope, and a separate vessel within said envelope adapted to contain a predetermined quantity of said fluid, one end of said vessel constituting a baifle to the flow of said fluid along said envelope, said end having an orifice therein to permit restricted fluid flow therethrough, the remainder of said vessel fitting the wall of said envelope whereby no fluid can be retained therebetween, said inleads being adapted to cooperate with the fluid within said vessel to complete an electrical circuit through said switch.

2. A mercury switch of the time delay type comprising a sealed envelope of vitreous material, inleads sealed thereinto, mercury in said envelope, and a metallic vessel within said envelope, one end of said vessel constituting a battle to mercury fiow along said envelope, said end having an orifice near the bottom thereof to permit re stricted mercury flow therethrough, one of said inleads being attached to said vessel, and another of said inleads terminating within said vessel.

3. A fluid flow switch of the time delay type comprising a sealed envelope of vitreous material, inleads sealed thereinto, an electrically conducting fluid in said envelope, and a separate vessel within said envelope having a sloping end and adapted to contain a measured quantity of said fluid, said sloping end having an orifice near the bottom thereof to permit restricted fluid flow therethrough, the remainder of said vessel fitting the wall of said envelope whereby no fiuid can be retained therebetween. said fluid connecting said inleads only when it is above a predetermined level in said vessel.

4. A mercury switch of the time delay type comprising a sealed envelope of vitreous material, inleads sealed thereinto, mercury in said envelope, and a separate vessel within said envelope having a sloping end and adapted to contain a measured quantity of said mercury, said sloping end having an orifice near the bottom thereof to permit restricted mercury flow therethrough, the

remainder of said vessel fitting said envelope whereby no mercury can be retained therebetween, each of said inleads being adapted to make contact with mercury retained by said vessel.

5. A mercury switch of the time delay type comprising a sealed envelope of vitreous material, inleads sealed thereinto, mercury in said envelope, a separate vessel within said envelope adaptto contain a measured quantity of said mercury, one end of said vessel constituting a baflle to mercury flow within said envelope, said end having an orifice near the bottom thereof to permit restricted mercury flow therethrough, and a refractory dividing wall within said vessel to retain a pool of mercury within said vessel at all operating positions of said switch, one of said inleads extending into said pool.

6. A mercury switch of the time delay type comprising a sealed envelope of vitreous material, inleads sealed thereinto, mercury in said envelope, a metallic vessel within said envelope adapted to contain a measured quantity of said mercury, one end of said vessel constituting a bafile to mercury flow within said envelope, said end having an orifice near the bottom thereof to permit restricted mercury flow therethrough, and a refractory cup within said vessel, one of said inleads terminating within said cup and the other being connected to said vessel.

7. A mercury switch of the time delay type comprising a sealed envelope of vitreous material, mercury within said envelope, a pair of inleads sealed into said envelope through a common seal, a metallic vessel affixed to one of said inleads, one end of said vessel constituting a bafile to the free flow of said mercury along said envelope, said end having an orifice near the bottom thereof to permit restricted mercury flow therethrough, the other of said inleads terminating at a predetermined point within said vessel.

FRANK MOOS.

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