US2830153A - Relay plunger - Google Patents

Description

April 8, 1958 J. K. LENTZ RELAY PLUNGER Filed Dec'. 3. 1956 Jo/zjle BY a l 2 l A m im v er.

United States Patent O 2,830,153 RELAY PLUNGER Joseph K. Lentzi, Elkhart, Ind., assignor to Durakool, Inc.,

lkhart, Ind., a corporation of Indiana Application December 3, 1956, Serial No. 625,715

9 Claims. (Cl. 200--112) This invention relates generally to mercury relays and more particularly to improvements in plunger assemblies thereof.

Mercury relays having a magnetic plunger floating in a body of mercury within an enclosed electrode casing have been known and used for some time. In the operation of such a mechanism, the plunger assembly is selectively raised or lowered by energizing a solenoid coil or like means to displace the body of mercury and establish contact between a pair of electrodes, one Vof which normally constitutes the outside casing of the relay assembly, and the other which normally extends coaxially into the interior o'f such casing.

Past plunger assemblies have normally constituted a metal shell or sleeve in which is mounted ceramic means including a cup portion for containing a body of mercury. Usually the ceramiccontains passageways for the ow of mercury through the plunger and valve means are sometimes employed to control the rate of such flow to regulate the rate of ascent and descent of the plunger and the operating characteristics of the relay. Heretofore such plunger assemblies have been plagued by a tendency to pick up mercury in small crevices existent between the outer metal shell thereof and the internally disposed ceramic. When the mercury is entrapped in between the several parts of the relay plunger, such plunger gradually assumes a diiferentweight characteristic, which changes its lloatingr position Within the body of mercury. Over a period of time the floating characteristics of the plunger may change enough to destroy the operational characteristics of the relay and in particular to destroy or vary the timing for the operation of the plunger. While various attempts have been made in the past to avoid this undesirable result, a successful solution to the problem has heretofore gone undetected.

' tight seal or junction between the ceramic and metal portions of the plunger. Thus, I prevent mercury from entering crevices or spaces between the ,parts of the plung- With the plungerconstructed according to the con- Icepts and features of my presentinvention, the initial -design characteristics and particularly the floating or sinking operation of the plunger india body of mercury is maintained at a'constant value thereby insuring predetermined` operational characteristics for the relay.

To 'accomplish the results of my invention, I propose 1 to insert a layer of glass or other fusible material between the ceramic and metal portions of the relay plunger,

which glass or ceramic is suitable fused in manufacture to provide a sealed bond between the parts to prevent the entrapment of mercury. As there are no interstices between ceramic and metal member in my improved con- The main object of thisv invention is to provide a new and improved plunger assembly for amercury relay.

2,830,153 Fatented Apr. 8, 19.58

Still another object of my invention is to provide a new and improved plunger assembly for mercury relays in which a sealed or fused bond is provided between the metal and ceramic parts ,of the plunger to prevent the entrapment of mercury therebetween.

Still another object of my invention is to provide a new and improved plunger for a mercury-relay in which the parts are so fused and bonded together that entrapment of mercury by the plunger is successfully avoided. .Y

Still another important object of my invention is to provide a plunger for a mercury relay having a metal shell bonded to a ceramic member by a suitable bonding agent, in which the bonding agent is maintained under compression under normal operating temperatures.

The aboveand further objects, features and advantages of this invention will appear to those familiar in the art from the following detailed description and specifications of the several embodiments thereof illustrated in the accompanying drawings.

In the drawings: j Y

Figure lis a crosssectional view taken substantially along the longitudinalcenter line of a typical relay plunger embodying k"theconcepts and teachings Vof this invention; 1

Figure 2 is another cross-sectional View similar to Figure l illustrating the features of'a modified plunger ernbodying the present invention; a

Figure 3 is still another cross-sectional view similar to Figure 1 illustrating a'third form of plunger assembly embodying the concept of the present invention; and

Figure 4 is another cross-sectional Viewv similar to Figure l showing a still further modified form of plunger in which the teachings of my present invention are employed. l n Y Turning now to the'features ofthe plunger illustrated in Figure 1 of thedrawings, it will be recognized that the plunger assembly, indicated generally by 'numeral 10 therein, comprises an outer metal sleeve 11 formed as asubstantially cylindrical member. Disposed internally of the upper end of sleeve 10 is an arc shield means formed by a first ceramic member 12 according to conventionaly practice. Ceramic 12 coaxially receives an upwardly projecting cup portion 13 of a second ceramic member 14 which extends substantially to the lower end of the shell 11. An annular spacer ring 15 is provided between the lower end of ceramic 14 and a bumper disc 16 mounted within the'lower end of shell 11. Shell'11 is turned over as at 17 to hold the bumper disc, spacer ring and ceramic members in assembly. The upper end of shell 11 is likewise turned inwardly in a substantially frusto-conical formation asV at 18 tol tie the arc shield ceramic 12 within the interior confines of the shell 11. In. this latter respect A it will be understood that arc shield member 12 has .an upwardly extending neck portion 20 which projects upwardly and outwardly 4through the opening provided by the truste-conical portion 18 of shell casing 11'.v

` A rst glass seal 21 is disposed between sloping shoulder portion 22 of ceramic 12 and the inside face of the inwardly turned portion 18 at. the upper end of shell 11. Such bead or seal member 21 is suitably fused in assembly to bond ceramic 12 to shell 11 adjacent the upper end thereof. Asecond annular glass Vseal bead 24 is likewise disposed-adjacent the lower end of ceramic 12 so as to extend around ceramic 12 and beneath its lower end. The annular bead 24 extends between ceramic member 12, the interior face of the shell 11 and an inwardly set shoulder portion 25 of the ceramic 14. Bead 24 is likewise fused Vin final assembly to provide a fusion bond between the shell 11 and the two ceramic members 12 and 14.

yof thermal expansion in the order of 86X 10-7.

While ceramic 14 is shown in cross section, it is to be understood that such contains suitable ports or passageways 26 permitting thepassage of mercury upwardly through the interior of shell 11 so that the same may enter the hollow cup portion 13 of ceramic 14. This construction is according to `conventional and known practice with the flow of mercury being regulated by i ports 27 formed through the bumper member 16.

f outstanding importance in the assembly 10 of Figure l is the provision of suitable materials having cociiicients of expansion adapted to carry out a unique feature of the present invention in which the glass bead members 21 and 24 are maintained in a substantially compressed condition to form a compression seal. This is carried out by constructing the outer metal shell 11 from a suitable metal, such as cold rolled steel, having a coeiiicient of thermal expansion in the order of l30 107, for example. The glass beads 21 and 2a are then made of any suitable commercially available product for this purpose having a lesser coefficient of expansion than the metal 11 as in the order of 89x10-Fl and a fusion point of approximately 1000 F. The ceramic members 12 and 14 are preferably constructed of Steatite or a like commercial product having a coeicient In the normal operation of a device of this character, the arc shield ceramic 12, as well as the cup portion 13 of ceramic 14, are subjected to high temperatures at the ilash caused at make and break of circuit through the relay. It would appear from the expansion coefiicients noted hereinabove that the metal having a greater rate of thermal expansion than the glass and ceramic would not permit the compression of the glass between ceramic and metal. However, having a greater rate of expansion than the ceramic or glass, the metal also has a greater rate of contraction. In the inital manufacture the glass, ceramic and metal are heated to a temperature of approximately l800 F., which is morethan adequate to fuse and seal the glass to the ceramic and metal, since the same has a fusion temperature of around l000 F. as noted above. As the assembly cools after fusion of the glass beads 21 and 24, the glass sets up at approximately 1000D F. while the metal sleeve 11 continues to contract faster than the glass and ceramic, therefore, placing the glass under compression as the cooling proceeds. YIn most normal operations of the plunger thel operating temperatures do not exceed 1000 F. so that the initial compression of the glass is not relieved even though it is reduced as the metal is heated from the arc or ash at make and break of circuit through the relay. If the heating of the relay plunger at any time exceeds the fusion temperature for the glass, the latter becomes plastic again, but upon succeeding cooling the above described cycle for providing a compression seal is repeated.

I have found that a plunger constructed according to the. concepts laid` out in Figure l is most successful in substantially preventing the entrapment of mercury be- -tween the ceramic member 1.2 and metal shell 11. The

provision of the two- spaced glass beads 21 and 24 acting as a compression seals suitably maintain their sealed integrity throughout the operating temperatures of the device to prevent the entry of any mercury in the spacing 30 surrounding ceramic 12.

Turning now to the aspects of a modiiiedv plunger assembly a shown in Figure 2, it will be recognized that the same includes an outer metal shell 31,. an arc shield ceramic 32 receptive of a central cup. portion 33 associated with a second ceramic member 34. As in the assembly 10 first described, the shell 31 is turned over at its lower end, as at 35, in anV annular fashion, and at its upper end, as at 36, to hold the 'ceramic members against longitudinal displacement. First and second glass@ bead members 37 and 3S are provided adjacent the upper and lower ends, respectively, of the arc shield ceramic 32 to fuse such ceramic member to the interior side walls or" shell 3l. A spacer ring 39 is provided between the lower end of ceramic 34 and a bumper plate 40 which ormulates the extreme or lowermost end of the plunger assembly. It will be recognized that the assembly of Figure 2 differs from that of Figure l in that the lower end of the arc shield ceramic 32 rests against shoulder portion il of the second ceramic member 34 with glass bead serving to bond both of said ceramics together opposite their point of junction, as well as joining these members to the interior side walls of the metal sleeve 31. By comparison with the structure of Figure 1, bead 24 in that figure serves to hold the shield ceramic 12 in a spaced relation relative to the lower or second ceramic 14. Although both the beads 24 and 38 of Figures l and 2, respectively, serve to bond the two ceramic members one to the other, as well as to the inside face of the metal sleeves involved, the modified form of Figure 2 is thought to be a somewhat more stable structure than that of Figure l, since the two ceramic members are engaged in abutting relationship as shown and are, therefore, longitudinally fixed within shell 31.

From Figure 2 the cross-shaped configuration of the second `ceramic members 34 will be recognized, the same comprising plural finger walls 42 extending outwardly from a central cylindrical core portion 43 to provide necessary passageways for the mercury to flow upwardly to the interior of the cup formed by the portion 33 of ceramic 34. The cross-shaped configuration employed in ceramic 34 is likewise suitably employed for ceramic 1li of the device in Figure l to provide the necessary mercury passageways as previously related.

Turning now to the features ofthe second modified form of plunger 10b, illustrated in Figure 3, it will be understood that such assembly includes an outer metal sleeve 50', a first arc shield ceramic 51 disposed near the top of sleeve 50 and coaxially of a second ceramic 52. Ceramic 52 has a central cup portion 53 adjacent its upper end which extends into the hollow interior of the arc ceramic 5l. The remaining portion of the assembly is as before described with ceramicv 52 being spaced from the lower end of an inwardly turned ange portion 54 of the sleeve Si) by means of an annular spacing ring 55. The lower end of the plunger assembly is defined by a bumper shield 562 The upper end of sleeve 50 is turned inwardly as at 57 to embrace the upwardly extending open threat portion 5S of the arc ceramic member 5l. To provide a sea-l between the two ceramic members and the metal sleeve, a glass'bead 60is employed, the same extending from shoulder portion 61 of the lower vor second ceramic 52 concentrically about the exterior walls of the shield ceramic 51. In this respect, it will be noted that glass bead 60 completely envelops all the portions of the shield ceramic 51 which reside within the interior of thc metal sleeve 50.

The structure illustrated. in Figure 3 is improved over that of Figures l and 2 because of thecontinuous annular nature of the bead 60since such provides a solid construction from the exterior of the metal sleeve to the interior of the shield ceramic .51, thus to give stability against shock and to increase the area of the seal. The increased seal area effectively prevents liquid, such as mercury, from lodging between the ceramic 60 and corresponding to the ceramic members 14, 34 and 52, previously described. The glass bead or envelope 71 likewise bonds with a spacer ring 73 adjacent an inwardly turned flange portion 74 and a bumper 75 at the lower end of the plunger assembly. Bead 71 also is fused to the inside walls of the metal sleeve 70. In this particular arrangement it will be appreciated that the entire internal surface of the plunger is concealed by the presence of the glass envelope 71 and that the structure therein is simplified over those of Figures 1, 2 and 3 by the elimination therefrom of the arc or shield ceramic member normally disposed in the upper end of the metal sleeve. In this respect, the glass envelope itself acts to shield the metal of the sleeve 70 from the effects of arcing at the make and break of contact in the plunger. Preferably, to withstand high temperatures and etchingj the glass of envelope should be of a synthetic quartz type having a coefficient of expansion less than the cold rolled steel used for sleeve 70, or alternatively a Steatite ceramic liner can be used in place of the glass liner 71, for example, Steatite No. 196 manufactured by American Lava Company, Chattanooga, Tennessee. It will also be noticed that the assembly if Figure 4 provides full sealed engagement between glass 71 and the surfaces of ceramic 72 contacted thereby.

In the above described forms of the invention, it is a feature common to all that the glass seal or bead members have a coefiicient of expansion less than that of the outer metal shell. By this arrangement, normal operating temperatures occurring within the plunger, cause the glass to be maintained in a compressed state to enhance its sealed relationship with the outer metal sleeve irrespective of its fusion connection with the outer metal shell and the ceramic members involved. By so providing the sealing medium under compression at all times during normal usage, I am assured against the entrapment of mercury or similar liquids between the several parts of the assembly.

It is believed that those familiar with the art will recognize the present invention as a marked advancement in the art. While I have herein shown and described the features of my invention in conjunction with four typical embodiments thereof, it is to be appreciated that the numerous changes, modifications and substitutions of equivalents may be resorted to therein without necessarily departing from the spirit and scope of my invention. As a consequence, it is not my intention to be limited to the particular forms of my invention herein described and illustrated except as may appear in the following appended claims.

I claim:

1. In a plunger assembly for mercury relays and the like, the combination comprising, a tubular metal shell member, an insulator member mounted coaxially within said shell member, and seal means disposed between said two members under compression therebetween and making a fused bond therewith.

2. In a plunger assembly for a mercury relay, the combination comprising, a substantially cylindrical ceramic member, a metal shell member concentrically surrounding said ceramic member, an annular glass seal means disposed between said ceramic and shell members to prevent the entrapment of mercury therebetween, said glass seal means having fused connection with said two members and being maintained under compression therebetween in the normal operating temperature range for the relay.

3. In a plunger assembly for a mercury relay, the combination comprising, a substantially cylindrical ceramic member, a metal shell member concentrically surrounding said ceramic member, an annular glass seal means disposed between said ceramic and shell members to prevent the entry and entrapment of mercury therebetween, said glass seal means having a smaller coefficient 6 of thermal expansion than said metal shell member whereby the same is held under compression by said metal shell member between the latter and said ceramic member in the normal operating temperature range for the relay.

4. In a plunger assembly for mercury relays and the like, the combination comprising, a substantially cylindrical ceramic member, an outer metal shell member surrounding said ceramic member, and seal means disposed between said ceramic and metal shell members for maintaining the same in concentric disposition, said seal means being maintained under compression and having fused connection with said shell and ceramic members.

5. The combination as set forth in claim 4 in which said seal means comprises glass having a smaller coefficient of thermal expansion than the metal of said shell member whereby the same is held under compression by said shell metal at temperatures below the fusion point of said glass.

6. A plunger assembly for use in a tubular body of a mercury relay to displace mercury contained therein, comprising, a tubular open-ended metal shell, a first insulating member mounted coaxially within the upper interior of said shell, a second insulating member mounted coaxially within the lower interior of said shell and having means defining a passageway for mercury, a first annular compression seal means bonding the upper end of said first insulating member to the inside walls of said shell, and a second compression seal means bonding the lower end of said first insulating member to the upper end of said second insulating member and the inside walls of said shell at a point intermediate the ends of the latter, said two compression seal means serving to prevent the passage and entrapment of mercury between said first insulating member and said shell.

7. A plunger assembly for use within a tubular body of a mercury relay comprising, a substantially tubular open-ended metal shell, an insulating member mounted within the interior of said shell and adjacent one end thereof, and an envelope of insulating material disposed between said first insulating member and said shell to cover the interior walls of the latter, said envelope having fused connection with the inside walls of said shell and the exterior walls of said first insulating member thereby to effectively seal said first insulating member to said shell and prevent the entry and passageway of mercury therebetween.

8. The combination as set forth in claim 7 wherein said envelope comprises glass having a lower coeicient of thermal expansion than the metal of said shell such that the latter maintains said envelope under radial compression at temperatures below the fusion point of said glass.

9. A plunger assembly for use in a tubular body of a mercury relay to displace mercury contained therein,

comprising, a tubular open-ended metal shell, a -hollow' insulating member mounted coaxially within the interior of said shell and spaced radially inward therefrom, said insulating member having means defining a passageway for mercury, bumper means disposed at the lower end of said shell and beneath said insulating member and having port means for controlling the passage of mercury, and a vitreous annular seal means disposed between said insulating member and said shell and having a fused bond therewith, said seal means having a lower coefficient of thermal expansion than the metal of said shell and a fusion point substantially lower than the melting point of the metal of said shell whereby the same is radially compressed by said shell at temperatures below its said fusion point.

References Cited in the file of this patent UNITED STATES PATENTS Cianchi May 9, 1939

Images