US1984419A - Fluid flow switch and method of making the same - Google Patents

Description

Dec. 18, m4. F, Moos 11,984,419

FLUID FLOW SWITCH AND METHOD OF MAKING THE SAME Filed March 10, 1932 2 Sheets-Sheet 1 Dec. 18, 1934. F. Moos I FLUID FLOW SWITCH AND METHOD OF MAKING THE SAME Filed March 10, 1932 2 Sheets-Sheet 2 ATTORNEY two fluid bodies.

Patented Dec. 18, 1934 UNITED STATES PATENT OFFICE FLUID FLOW SWITCH AND METHOD OF MAKING THE SAME Application March 10, 1932, Serial No. 593,019

14 Claims.

The present invention relates to fluid flow switches, and to the method of making the same.

The invention consists in a novel fluid flow switch, and in the method of making the same, as hereinafter set forth and claimed.

A particular object of the invention is to provide a fluid flow switch which will inherently make and break an electric circuit between fluid pools, regardless of how said switch is handled between said operations. Another object of the invention is to provide a switch of the tilting type which will operate equally well at any rotational position of said switch. A further object of the invention is to provide a switch having 'ahigh current rupturing capacity. Still another object of the invention is to provide a switch of simple and inexpensive construction embodying the foregoing features. Another object of the invention is to provide an exceptionally compact switch, devoid of cups and similar protuberances. Another object of the invention isv to provide a novel method of producing such a device. Still other objects and advantages of the invention will appear from the following detailed specification, or from an inspection of the accompanying drawings.

Fluid flow switches are of two general types; one the type in which a fluid body moves into contact with a metallic electrode, and the other the type in which contact is made by merger of The latter type of switch has an inherently greater current capacity, due both to the fact that the circuit is more effectively ruptured between fluid pools,,and to the fact that a better contact is formed at the instant when the circuit is closed, with a consequent avoidance of the" arcing upon circuit closing which is so characteristic of the other type of switch, espe cially when relatively large currents are being controlled. As heretofore constructed, however, switches of the fluid merger type have had the undesirable feature that if improperly handled the circuit could be closed through these switches by contact between the fluid and a metallic electrode, whereupon the switch would be destroyed by the long-continued arc of make. I have now discovered that by a novel structure of my invention all possibility of closing the circuit through a fluid flow switch except by the desired merger of the fluid pools maybe absolutely precluded, regardless of how the switch is handled. In fact. the mercury pools are so effectively maintained about the inleads that the switch may be operated through extreme angles, or even continuously rotated end over end, without ever making or breaking the circuit except by the desired separation or merger of fluid pools. Moreover, my new switch may be operated with equal facility in any rotational position, due to its symmetry. My novel switch is also of extremely simple and inexpensive construction, especially when made according to a novel process of my invention.

For the purpose of illustrating my invention I have shown a preferred form of my novel switch, together with several modifications thereof, in the accompanying drawings, in which Fig. 1 is an elevational view of a mercury switch in the closed circuit position,

Fig. 2 is an elevational view of the same switch ,in an open circuit position,

Fig. 3 is a cross section of the same switch, taken on the line 33 of Fig. 1,

Fig. 4 is a longitudinal section of the same switch in another position,

Fig. 5 is a view similar to that of Fig. 4 of a slightly modified switch,

Figs. 6 to 9 are elevations, in part section, of other modifications of the switch of Fig. 1, and

Figs. 10 and 11 are sectional view of another modification of the switch of Fig. 1.

In these drawings, with particular reference to Figs. 1-4, there is shown a switch having a tubular envelope 1 within which there is a concentric tubular member 2. One end of said tubular member is fused into said envelope at the pinch seal 3, while the other end thereof terminates a short distance from the other end of said envelope 1. The envelope 1 can be of any suitable vitreous material, such as lead glass, lime glass, or the like, but Where relatively large currents are to be interrupted I prefer to use a glass which is more resistant to heat, such as one of the borosilicate glasses of the type known to the trade as Pyrex or Nonex. The tubular member 2 is preferably of the same material as the envelope 1, although it is obvious that a more refractory material, such as fused silica, may be used therefor by the interposition of a suitable graded joint between this member and said envelope, if desired. A thin metallic sleeve 4 closely fits the outside of the tubular member 2, while a similar sleeve 5 closely fits the inside of said member, eachof said sleeves terminating an appreciable distance from the open end of said tubular member 2. These sleeves, which serve as contact rings, may be of any metal which will not contaminate the fluid. In a mercury switch I find it convenient to use cold rolled steel, for example, since due to its natural resilience slitted sleeves made thereof can be relied upon to make the desired snug fit with said tubular member 2. Inleads 6 and 7 extend through said pinch seal 3 and are welded to the sleeves 4 and 5 respectively. When the inner sleeve 5 is formed of a fiat strip rolled up, as shown, an ear on one end of this strip is preferably turned inward, and the inlead 7 welded to the inturned end, since this allows said inlead 7 to be brought nearer the center of the pinch seal 3 without bending said inlead, allowing more space for the seal-ofi 8. The envelope 1 may be evacuated,- of course, through a centrally located tubulation, connecting with the inside of the tubular member 2, in which case the sealoff tip 8 will be between the inleads 6 and 7, making unnecessary the off-setting of theinlead 7 with respect to the sleeve 5. I find, however, that the envelope 1 is more conveniently evacuated through a tubulation connecting with the annular space between said envelope and the tubular member 2, and hence prefer to use the structure shown. Sufficient mercury, or other electrically conducting fluid, 9 is enclosed within said envelope to extend an appreciable distance above'the open end of the member 2 when the switch is in the position shown in Fig. 4, so, that it is in contact with the sleeves 4 and 5. A suitable arc suppressing atmosphere,

v preferably hydrogen, is sealed within said envelope 1.

The manufacture of these switches is extreme- 1y simple and inexpensive, due to the novel arrangement of the parts thereof. According to the preferred method the sleeves 4 and 5 are formed and the beaded inleads 6 and 7 welded thereto. Said sleeves are then slipped over and inside respectively an open ended vitreous tube which becomes the tubular member 2. The envelope 1 is then placed over this assembly, with a tubule extending into the space between said assembly and said envelope. The end of said envelope and the adjacent end of the tubular member 2 are then heated and pinched down about the inleads 6 and 7, a single operation thus pinched down' on the inlead '7.

' the pinch seal 3 in two steps.

of the softened glass not to close the passage in the tubule. Several ways are now known of tubulating through a pinch seal, however, hence the details thereof need not be discussed here. The switch is then exhausted and the mercury and hydrogen admitted thereto in any suitable manner, although I prefer to use the method .disclosed in Patent 1,831,935, issued November 1'7, 1931, to Warren R. Walker. The tubulation is then closed in a conventional manner, forming the seal-off tip 8.

In some cases it may be desirable to produce In this case the tubular member 2 and the beaded inleads 6 and are assembled as before, and. the member 2 During this pinching the bead about the inlead 6 merges withthe glass at the pinchforming a unitary .assembly-.- The envelope is then slipped over this assembly and fused thereto, after which the switch is finished'according to the method hereinbefore described. With this method of construction the closed end of the tubular member 2 can be positioned slightly away from the pinch seal 3, as shown in Fig. 5, giving a structure which has certain advantages, including greater immunity to temperature strains.

In operating either the switch of Figs. 1-4, or that shown in Fig. 5, the end of the envelope 1 cooperates with the closed tubular member 2 to form a trap for a pool of themercury 9. No matter how this switch is turned the member 2 will always scoop up and retain a predetermined quantity 9 of mercury, as shown in Fig.2. This mercury 9 is sufficient in quantity to extend beyond the sleeve 5 toward the open end of the lining 2 whenever the switch approaches the circuit closing position, so that the circuit is always closed by the merging of two fluid bodies. Likewise the relative positions of the electrodes and of the lining are such that whenever the mercury pool 9' has been merged with the main body of mercury 9 to close the circuit through the switch it is impossible to move the mercury out of contact with either sleeve without first separating the mercury pools. Thus it is absolutely impossible to either open or close a circuit through this switch, except by the desired separation or merger of fluid pools. Moreover, the switch operates with equal facility at any rotative position. As a result this switch is singularly immune to failures due either to faulty installation or faulty manipulation, and may be described as a foolproof switch.

In some cases, as where particularly large currents are to be interrupted, I find it desirable to cause the arc of rupture to occur far ther inside of the tubular member 2 than is the case with the switch of Figs. 1-4. This may be easily accomplished in either of two ways. As shown in Fig. 6 the open end of the tubular member 2 is flared out, causing the mercury pool 9 to recede farther into said member before it separates from the main body of mercury 9. Or as an alternative the end portion of the tubular member 2" may be made of smaller diameter than that of the remainder of said memher, as shown in Fig. 7, thus furnishing a ledge over which the mercury separates, causing the arc of rupture to occur well within the tubular member. Either of these alternatives obviously reduces the arcing against the end wall of the envelope 1, and thereby tends to increase both the rupturing capacity and the useful life of the device.

In some cases it may be desirable to have a highly refractory tubular member within an envelope of a less refractory material to which it cannot be directly sealed. Such a construction is shown in Fig. 8. The envelope 1 of this switch may consist of any vitreous material, as in the switches previously described. The member 12, which is tubular with one end closed, is made of any desired refractory material, such as lavite, porcelain, fused silica, borosilicate glass, or the like. The inlead 7 extends through a small hole in the closed end of said member 12, and that portion of said lead which extends between said tubular member 12 and the pinch seal 3 is preferably beaded, so that the switch may be operated without regard to its rotative position. For

inlead and said lining have sufficiently similar coefficients of expansion. With this construction the lining 12 is wholly supported in the desired concentric position by the sleeves 4 and 5, and by the associated inleads 6 and 7. Where a soft glass is used for the envelope 1, I flnd it desirable in some cases, especially where relatively large currents are to be interrupted, to provide a cup-shaped lining 14 of more refractory. material, such as that used for the tubular member 12, within the end of said envelope. Said lining 14 overlaps the end of the member 12 by an appreciable distance, and thus very effectively shields the envelope 1 from any arcs of rupture. Any desired means may be used to fix said lining 14 in position, but as shown-the inlead 6 has an extension 6' which is bent outwardly to engage said lining and firmly hold it against the end of the envelope 1, while one or more outwardly extending ears 15 on the sleeve 4 may also be used for the same purpose. With this construction all the inner parts of the switch are interlocked and firmly supported within the envelope 1, with the result that this switch is extremely rugged and resistant to shocks. The operation of this switch is identical with that of the switch of Figs. 1-4, and hence need not be further described.

A modification of the switch of Fig. 8 is shown in Fig. 9. In this switch the open end of the tubular member 12 extends toward the pinch seal 3, while the closed end of said tubular member is against the other end of the envelope 1. With this construction the inlead 7 extends directly into the open end of said member 12, being beaded from the pinch seal to a point some distance inside of said shell 5, so as to permit operation of the switch in any rotative position. This construction permits of an easier assembly, and hence is somewhat cheaper to produce than the switch of Fig. 8. Such a switch operates in the same manner as the other switches described, especially in the larger sizes, where the inlead '7 does not appreciably impede the flow of the mercury 9 into the open end of the tubular member 12.

A further modification of my switch is shown in Fig. 10. The switch shown in this figure has a metal shell 21 substituted for the vitreous envelope 1 of the switches of the previous figures. This metal shell, being conductive, also takes the place of the outer sleeve 4 and the inlead 6 of the other switches illustrated. Various modes of construction may, of course, be used in carrying out my invention while using such a metal envelope, but the simple and. inexpensive form here illustrated is preferred. With this construction a piece of tubing 22 of any suitable vitreous material, having one end flared, has a sleeve 5 fitted therein with the inlead 7 extending through the flared end. A tubule is then inserted within the flared end, after which the vitreous tube 22 is pinched down on said tubule and said lead to make a pinch seal 23 according to the conventional method used in making tipless lamps. This assembly is then placed in the metal envelope or shell 21, and the flare of said tubing 22 is sealed thereto. The metal shell 21 may be made of any desired metal which will not contaminate mercury by amalgamation therewith, and the tubing 22 may be of any material which will fuse to said shell without excessive strain. In practice, however, I find it desirable to form the shell 21 of either iron or a chrome-iron alloy, in which case the tubing 22 is preferably of either lead or lime glass, since either of these glasses seals readily and permanently to either of these metals. The more refractory glasses, such as borosilicate glass, fused silica, and the like may, of course, be used either by making the envelope 21 of a metal, such as molybdenum, to which they can be sealed, or through the interposition of a graded joint between the metal shell and the more refractory part of the tubular member 22. Such a graded joint would preferably come at a point between the pinch seal 23' and the open end of the tube. In order to minimize any strains at the glass-to-metal seal the metal shell 21 is preferably made rather thin at this point, thus reducing the amount of compression which it can exert on the glass. The mode of operation of this switch is identical with that of the switches previously described, connection being made to the main body of mercury 9 either by inserting the envelope 21 in a suitable contact making clip, or by means of a lead 6' welded or soldered thereto. This switch likewise has all the advantages of the other switches, plus the advantages inherent in a metal envelope, such as increased heat radiation, with a consequent increased continuous current carrying capacity, a marked lessening of the breakage hazard, omission of one inlead and the like.

In some cases it is desirable to retain the advantages, such as easy manipulation, obtained by using a soft glass for the tubular member 22, and at the same time to increase the current rupturing capacity of the switch. A structure by which this is conveniently accomplished by a simple modification of the switch of Fig.- 10 is shown in Fig.11. In this modification a tubular lining member 24, of any suitable refractory material, such as lavite, porcelain, fused silica, or the like, is slipped into the open end of the tubular member 22. The outer end of said lining 24 has an outwardly extending flange 25 which engages the end of the tubular member 22, while the inner end of said lining has an inwardly extending flange 26. The metal sleeve 5 is fitted within said lining 24 with one end against said flange 26, said lining being firmly held in place thereby. The frictional fit of the lining 24 in the tubular member 22 is usually adequate to prevent the formation of a current carrying mercury path therebetween, but if desired, packing material, such as asbestos fiber or glass wool, may be interposed therebetween; or the lining and the tubular member may be fused together to form a. ring seal therebetween. The latter operation can be easily carried out, for example, where the lining 24 is of lavite and the tubing 22 is of soft glass, since these materials are readily sealed to each other. In this switch the are always occurs on the refractory lining 24, with the result that very large currents can be interrupted without damage to the switch. In some cases I find it desirable to form three or more projecting ears 27 on the aforesaid flange 25, said ears extending outwardly into contact with the envelope 21, and thereby forming a support for the open end of the tube 22. Said ears are equally spaced and are made narrow enough not to impede free fiow of mercury thereby. With such a construction this switch is exceptionally rugged, and will withstand much abuse. While the use of ears on said flange, as described, offers the most convenient method of producing the desired result, various other expedients, such as studs on the member 22, may obviously be used, if desired, in lieu thereof.

The construction shown in any of these switches permits the handling of relatively large currents in a switch of small size and simple construction. For example, a switch of the type shown in Fig. 1, having a length of approximately one inch and a diameter of about of an inch, will safely carry and interrupt from 10 to 20 amperes at 110 volts D. C., if the en velope and lining are made of a borosilicate glass, such as Nonex. Larger interrupting capacities may be easily obtained either by using a more refractory material, or by increasing the dimensions of the switch. The latter alternative also increases the continuous current carrying capacity as well, and hence is the more desirable solution in most cases.

The construction disclosed in any of these switches is also singularly rugged. In each of these constructions all of the component parts of the switch cooperate with and mutually support each other, thus providing a switch which can successfully withstand severe mechanical shocks and mishandling, either 'in transit, in

installation, or in actual operation.

While I have described my invention by reference to particular embodiments thereof it is to be understood that it is not limited thereto, but that various changes, substitutions or omissions, within the scope of the appended claims,

may be made in the switches described, or in the method of manufacture thereof, without departing from the spirit of my invention. I claim as my invention:-

1. A mercury switch comprising a sealed envelope of vitreous material, mercury therein, a concentric vitreous tube fused to said envelope at one end, the other end of saidtube approaching the opposite end of said envelope, an inlead extending into said envelope through the fused portion of said envelope and tube and extending into said tube, said inlead terminating in a thin shell closely fitting the interior of said tube, and an inlead extending into the space between said tube and said envelope and terminating in a contact ring about said tube.

2. A mercury switch comprising a sealed tubular envelope, mercury therein, a vitreous tube within said envelope, 'an inlead sealed into said envelope, said inlead terminating in a sleeve within said tube, said tube being supported by said sleeve, and means to make contact with the mercury exterior to said tube.

3. A mercury switch comprising a sealed tubular envelope, mercury in said envelope, a concentric vitreous tube within said envelope, one end of said tube being closed and the other end thereof approaching the opposite end of said envelope, an inlead sealed into said envelope, said inlead terminating in a sleeve within said tube, said tube being supported by said sleeve, and an electrical conductor which makes contact with the mercury exterior to said tube whenever said switch is in such a position that said mercury extends within said tube.

4. A mercury switch comprising a sealed tubu lar envelope, mercury therein, a concentric vitreous tube within said envelope, one end of said tube being closed and the other end thereof approaching the opposite end of said envelope, two inleads sealed into said envelope, one of said inleads extending into said tube and being insulated from contact with the mercury exterior thereto, said inlead terminating in a thin sleeve within said tube, the other inlead extending into the space between said tube and said envelope and carrying a sleeve which extends about said tube, said tube being supported by said sleeves, and an arc suppressing atmosphere within said envelope.

5;" A mercury switch comprising a tubular metallic envelope, mercury therein, a concentric vitreous tube within said envelope, said tube being closed at one point and having one end fused to said envelope, while the other end of said tube approaches an end of said envelope, and an inlead extending into said tube.

6. A mercury switch comprising a tubular metallic envelope, mercury therein, a concentric vitreous tube within said envelope, said tube having one end fused to said envelope, while the other end of said tube approaches an end of said envelope, an inlead extending into said tube, said tube being fused to said inleadwhereby said tube serves both to hermetically seal said envelope and to retain a pool of said mercury about said inlead, and a refractory lining for the open end of said tube, said lining having projections which engage said envelope whereby the open end of said tube is rigidly supported.

7. A mercury switch comprising a sealed tubular envelope of vitreous material, mercury therein, a concentric vitreous tube within said envelope, said tube having a closed end a portion of which is integral with one end of said envelope, and an open end which approaches the opposite end of said envelope, said tube cooperating with said envelope to entrap a pool of said mercury in said tube at all positions of said switch, two inleads sealed into said envelope, one of said inleads extending into said tube through the portion thereof which is integral with said envelope while the other extends into the annular space between said tube and said envelope, said inleads terminating in contact rings inside of and outside .of said tube, respectively, the ring inside of said tube being thin and closely fitting said tube and extending .to a point which is at such a distance from the end of said tube that when said switch is tilted the entrapped mercury pool still extends beyond said ring toward theopen end of said tube after saidentrapped pool has separated from the mercury exterior to said tube, but near enough to the end of said tube to make contact .with said entrapped mercury when said tube is vertical with the open end downward, the outer ring making contact with the main mercury body at all times that said body is merged with said entrapped pool, and an arc suppressing atmosphere in said envelope.

8. A mercury switch comprising a sealed tubular envelope, mercury therein, a concentric vitreous tube within said envelope, one end of said tube being closed while the other end thereof is open and approaches an end of said envelope, whereby said tube cooperates with said envelope to entrap a pool of said mercury at all positions of said switch, an inlead sealed into said envolope and extending into said tube, and an electrical conductor which makes contact with said mercury at a point exterior of said tube whenever said switch is in such a position that said mercury extends within the end of said tube, the open end of said tube being flared.

9. The method of producing a mercury switch which comprises forming an inlead with a contact sleeve thereon, inserting said sleeve in a vitreous tube which it snugly fits, placing an enclosing envelope about said tube, and fusing said envelope and said tube together while maintaining said inlead and said envelope in predetermined relation, whereby said tube is maintained in the desired position within said envelope during the fusing operation.

10. The method of producing a mercury switch which comprises forming an inlead with a contact sleeve thereon, inserting said sleeve in a vitreous tube which it snugly fits, placing an other sleeve with an attached inlead about said tube, placing an enclosing envelope about said tube and inleads, inserting a tubulation between said tube and said envelope, heating the end of said envelope and of said tube to the fusing temperature, and pinching them down onto said inleads while maintaining said inleads and said envelope in a predetermined relation.

11. The method of producing a mercury switch which comprises forming an inlead with a contact sleeve thereon, inserting said sleeve in a vitreous tube which it snugly fits, placing another sleeve with an attached inlead about .said tube, placing an enclosing vitreous envelope thereof approaching the opposite end of said envelope, and two inleads sealed into said envelope, one of said inleads passing through the closed end of said tube, and the other supporting the free end of said tube, whereby said tube is supported by said inleads against lateral displacement at two separated points, said first mentioned inlead being insulated between said envelope and said tube.

13. A mercury switch comprising a tubular envelope, mercury therein, a concentric vitreous tube within said envelope, one end of said tube being closed while the opposite'end thereof approaches an end of said envelope, an inlead extending into said tube, an'electrical conductor in the rim of the open end of said envelope, said tube extending within said envelope to a point near the opposite end thereof, and an inlead extending within said tube, said tube being hermetically sealed to said inlead, whereby said tube serves to hermetically seal said envelope and to retain a quantity of mercury about said inlead.

FRANK MOOS.

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