US3059077A - Electromagnetic liquid contact relay - Google Patents

Description

Oct. 16, 1962 M. A. TABET ELECTROMAGNETIC LIQUID CONTACT RELAY 2 Sheets-Sheet 1 Filed March 8. 1960 Oct. 16, 1962 M. A. TABET ELECTROMAGNETIC LIQUID CONTACT RELAY 2 Sheets-Sheet 2 Filed March 8, 1960 4INVENTOR MICHAEL A. TABET SUPPLY LOAD United States Patent Otice 3,059,077 Patented Oct. 16, 1962 3,059,077 ELECTROMAGNETIC LIQUID CONTACT RELAY Michael A. Tabet, 1336 Ballentina Blvd., Nortoik 12, Va. Filed Mar. 8, 1960, Ser. No. 13,641 3 Claims. (Cl. 200-112) The present invention relates to circuit making and breaking devices of the type wherein an armature is shifted from one operative position to another position in response to a relatively small change in the flux to which the armature is subjected providing a sensitive relay and the invention more specifically pertains to means enclosing the armature and providing separate mercury pools through which a circuit is completed in one position of the relay.

Various types of switches are known wherein a load circuit is completed from one terminal to another by mercury which bridges electrodes carried by the container for the mercury. In one type of relay the level of the liquid is altered by displacing the 4mercury by means of a plunger responding to an electromagnetic iield but a high energy level is required to actuate such a relay. Other liquid contact switches are actuated by tilting an envelope containing mercury to shift the liquid to a contact making or breaking position. The known types of liquid contact switches or relays all require relatively high energy levels for operation and are thus not adaptable to circuit conditions wherein the relay must respond to small current values and a narrow range of uctuations in the current flowing in the circuit supplying the operating coil of the relay.

It is accordingly an object of the present invention to provide a relay of the liquid Contact type with the elements thereof so constructed and arranged that the switch is accurately responsive to small current values in the range of a quarter ampere and less and which is consistently responsive to predetermined changes in current values flowing in the operating coil.

Another object of the invention is to provide a relay of the liquid contact type which includes enclosure means coniining mercury in one pool into which an electrode carried by the armature is adapted to extend with another electrode carried 4by the armature adapted to extend into a second pool of mercury coniined in another area or charnber of the enclosure means so that a circuit is established from one mercury pool to the other when the armature is in one position whereby the load circuit through the -relay is interrupted when the armature is actuated by the eld developed by the operating coil without shifting or `displacing the mercury.

A more specific object of the invention is to provide an electromatic actuated relay wherein an insulating barrier in association with other portions of a sealed container maintains mercury into two separate pools and an armature provided within the container carries electrodes which extend into the separate pools of mercury when the operating coil is deenergized so that a circuit is completed from one pool to the other and a relay wherein a relatively low energy level is required to shift the armature and withdraw the electrodes `from one or both of the mercury pools.

Other objects and features of the invention will be appreciated and become apparent to those skilled in the circuit making and breaking art -as the present disclosure proceeds and upon consideration of the following Adetailed description taken in conjunction with the accompanying drawings wherein several embodiments of the invention -arefdisclosed In the drawings:

FIG. l is a side elevational view of a relay exhibiting the invention.

FIG. 2 is a sectional View taken on the line 2-2 of FIG. 1 on an enlarged scale and showing the switch in a closed position.

FIG. 3 is a similar view showing the open position.

FIG. 4 is a perspective View of the armature on an enlarged scale.

FIG. 5 is a transverse section taken on the line 5-5 of FIG. 3.

PEG. 6 is an elevational View of the sealed container for the armature and the mercury pools.

FIG. 7 is a sectional view on an enlarged scale showing a modified armature and insulating barrier.

FIG. 8 is a similar View taken at a right angle to FIG. 7 showing the armature in the raised position.

FIG. 9 is an enlarged perspective view of the armature and the electrodes carried thereby employed in the embodiment shown in FIGS. 7 and 8.

FIG. l0 is a plan View of the insulating barrier incorporated in the embodiment shown in FIGS. 7 and 8.

FIG. ll is a diagrammatic view of portions of the relay showing one type of circuit connections.

FIG. 12 isa fragmentary sectional view showing -a shading coil on the iixed core and taken on the line 12-12 of FIG. 2.

IThe invention is directed to a relay wherein a load circuit through the relay is completed by electrodes or conductive elements carried Kby the armature which extend into separate and electrically isloated pools of mercury. The electrodes or conductive elements and the armature `are so designed and constructed as to -have a small mass yand because no appreciable quantity of mercury is displaced the energy required to shift the armature in response to an electromagnetic field is of a low value. It is for these purposes that the armature is formed principally as a hollow cylinder which extends into the open axis of an operating coil and the annular wall of the hollow cylinder occupies -a position close to the inner turns of the coil whereby the air gap between the coil and the effective portion of the armature is at a minimum. The shape and arrangement of the insulating barrier in association with other portions of the sealed container and which maintain the mercury in Vdistinct pools forms another feature of the invention.

" projection 12 which in cooperation with a nut 14 (FIG.

l) serves as one terminal of the relay. The disc-shaped bottom wall 11 and the projection 12 are formed of a metal having good electrical conductive properties. A frusto-conical shaped barrier 1S is arranged within the container 10 and the base end thereof is seated and supported on the bottom wall 11. The barrier 15 is formed of insulating material of any suitable type and may be formed of a ceramic material which is bonded to an upturned peripheral flange 16 carried by the bottom wall by an annular joint 17. The upright wall structure for the container 10 is formed of metal having good electrical conducting characteristics and this element may take the form of a metal tube 18. A second terminal 19 (FIG. l) for the relay is carried by the peripheral wall of the tube 1S. The frusto-conical shaped barrier 15 includes an upstanding annular ilange 21 at the base end and this iiange surrounds the lower portion of the tube 18. When the insulating barrier 15 is formed of ceramic material an annular bond 22 sea'ls the perimeter of the tube 18 with respect to the llange 21.

The upper end of the tube 18 is closed and this closure means includes a plate 23 of annular shape which may be formed integral with an inverted cup-shaped member 24. The annular plate 23 and the cup-shaped member Z4 are desirably formed of a ceramic material or any suitable material having low magnetic permeability characteristics. The perimeter of the annular plate 23 is jointed to the upper end of the tube 18 by means of an annular bond 26. The inverted cup-shaped member 24 is provided for accommodating an armature 28 of relatively small mass. The armature 28 is best shown in FIG. 4 and it includes a cylindrical shaped or tubular portion 31 which is open at its upper end 32 and open at its llower end 33. The external diameter of the tubular portion 31 is such as to tit within the inverted cupshaped member 24 of the container 10 with a minimum of clearance but suiiicient to provide for free axial movements of the armature.

The tubular member 31 of the armature carries two circumferentially spaced legs 34 and 36 which extend below the lower end 33 of the tubular portion 31. The legs 33 and 34 carry a transversely disposed arm 37 which is formed of metal having good electrical conductive properties. An electrode 38 depends from one end of the arm 37 and a similar electrode 39 depends from the other end of the arm 37. The electrodes 38 and 39 diverge outwardly in proceeding downwardly and are of such cross section as to carry load currents. The armature 28 and the parts carried thereby is arranged within the container prior to the closing thereof so that when the container is sealed the armature will be encased within the container. The armature may be added in the manufacturing process at any suitable stage prior to closure of the container.

The frusto-conical barrier at the apex end thereof is provided with an aperture 41 with its axis aligned with the axis of the inverted cup-shaped member 24. A passage 4Z extends through the threaded projection 12 and air may be removed from the container itl through this passage and an inert gas may be added through the passage 42. A limited quantity of mercury or any electrically conductive liquid is added to the container through the passage 42 which may be closed by suitable means such as a plug 43. While the mercury is added to the container 1() through the passage 42 it is free to move through the aperture 41 and it is possible that a major portion of the limited quantity of mercury will be accommodated within the chamber beyond the frusto-conical barrier 15. When the container is erected to a vertical position some of the mercury passes downwardly through the aperture 41 and this movement of the liquid continues until the level of the liquid exteriorly of the frusto-conical barrier 15 is no longer above the level of the upper end of thefrustoconical barrier in the vicinity of the aperture 41. The limited quantity of mercury is thereby separated into two distinct pools. The mercury above and exteriorly of the inclined portion of the barrier 15 arranges itself in an annular pool 44. The annular pool of mercury is in contact with the tube 1S but is insulated from the bottom wall 11 of the container by the base portion of the truste-conical barrier 15. The mercury which is moved downwardly through the aperture 41 forms a mercury pool 45. The mercury pool 45 is in electrical circuit relationship with the bottom Wall 11 but is not in electrical conductive relationship with the tube 18. In the degenerized condition of the relay disclosed the electrodes 38 and 39 extend into the annular mercury pool 44. The circumferential spacing of the electrodes 38 and 39 maintains electrical circuit relationship of at least one of these electrodes with the mercury pool 44 even when the relay assembly is not maintained with its axis in a true vertical position.

The armature 28 carries an electrode 46 which is in electrical conductive relationship with the arm 37. The electrode 46 extends below the arm 37 and in the deenergized condition of the relay the electrode 46 extends through the aperture 41 and into the mercury pool 45 which is supported on the bottom wall of the container and confined within the frusto-conical barrier 15. The

4 mercury pool 45 is in electrical conductive relationship to the bottom wall 11 and the projection 12 which serves as a terminal for the relay.

An operating coil 50 for the relay is carried by a spool type frame formed of insulating material. The internal diameter of a sleeve 52 ofthe coil Aframe is of such dimensions as to fit snugly about the external diameter of the inverted cup-shaped member 24. A lower annular flange 53 of coil frame engages and lies along the upper face of the annular plate 23 of the container 1t). The peripheral wall of the cup-shaped member 24 and the thickness of the sleeve 52 are as small as possible so as to reduce to a minimum the air gap between the armature 28 and the coil 50. A stationary core 56 is mounted in the upper end of the sleeve 52 and this core may if desired be provided with a shading coil 55 as shown in FIGS. 2 and l2 particularly when the relay is to be operated by alternating current. The core 56 is adjustable axially of the coil 50 and any suitable means may be provided for effecting such adjustment. In the embodiment illustrated a rod 57 is carried by the core 56 in threaded engagement with a bracket 5S supported in any suitable manner such as by the upper annular flange 54 of the coil frame. Rotation of the threaded rod 57 adjusts the axial position of the core 56 to vary the pick-up point of the armature 28. The threaded rod 57 may be maintained in an adjusted position by means of a lock nut 59.

In handling the assembled relay such :as during shipment the mercury in the annular pool 45 lwithin the frusto-iconical carrier 15 may pass through the aperture 41 so that substantially all of the mercury may be aI- ranged in the container 10 externally yof the barrier 15. When the relay is erected in a vertical position as shown the mercury may tend to bridge the aperture 41 because of the surface tension of the mercury and any gas that is trapped in the lower chamber of the container within the barrier 15 may be suliicient to prevent Ia suiiicient quantity of mercury to pass downwardly through the aperture 42. In order to vent the lower chamber later-ally disposed holes `61 are provided in the electrode 46 which is of tubular construction. Any gas that is trapped under pressure below the frusto-conical barrier 15 may enter the tubular electrode 46 through the holes `61 and pass into a hollow stem 62 which forms an extension of the electrode 46. The hollow stem 462 extends through the arm 37 and into the tubular portion 31 of the larmature. The upper portion of the hollow stem 62 is provided with laterally disposed holes `64 so that gas pressures of the two chambers in the container 1t) may become equal. The lower end of the electrode 46 is closed as indicated at 66 and the upper end `of the stern 62 is closed as indicated at 67. The lateral disposition of the holes 61 and 64 avoid the possibility of free particles closing these apertures. When the relay is in the deenergized condition `the lower end of the tubular electrode 46 engages the bottom wall 11 and limits downward movement of the armature. The holes 61 are so located that they remain above the normal level of the mercury in the pool 45.

The relay has -utility for the purpose of completing and interrupting a load circuit wherein the current is relatively high and the control current relatively low. The relay has been found suitable to control street lighting equipment wherein such a lamp is energized in response to the absence of natural light falling on a photoelectric device such as indicated at 68 in FIG. l1. The photoelectric device 68 in the absence of a predeterminedlevel of light has such `high resistance that the circuit supplying current `to the coil 50 is such that the ux delveloped thereby is insuiiicient to lift the armature 28. The load circuit `from one side of the supply extends through the terminal 19, the sleeve 18 of the container 1t), the mercury pool 44, the electrode 38, the arm 37 'and the electrode 46 and the mercury pool 45 to the bottom wall 11 and terminal 12 so that the load circuit is closed. When suiicient light falls on the photoelecbric unit 68 the resistance thereof is reduced and the current owing in the coil 50 increases and the change in the current -owing in the coil 50 may be `gradual and of Ia small value and usually less than one-fourth of an am pere. The armature 28 and the electrodes carried thereby is of such small mass and the periphery tubular portion v31 of the armature is -so closely located to the turns of the operating coil 50 that the armature is lifted at -a given value of current llowing in the coil 50. As the armature 28 is raised the electrodes '38 and 39 are removed frorn contact with the annular mercury pool 44. The load circuit is accordingly interrupted and the la-mp is no longer energized. The upper end of the tubular portion 31 of the armature engages the closed end 69 of the inverted `cup shaped member 24 to limit upward movement of the armature.

A modication is shown in FIGS. 7 to 10 wherein the stem 62 carried by the armature in thev first embodiment is omitted and a vent passage 71 is provided through the wall of la. modified frusto-conical barrier 15a. In this embodiment a projection 7-2 of insulating material such as a suitable ceramic extends `above the level of the mercury forming the annular pool 44. The projection 72 may be *formed integral with the frusta-conical barrier 15a and the passage 71 terminates :above Ithe level of the limited quantity of mercury. In lthe event the entire quantity should be arranged exteriorly of the barrier 15a. The lower end of the passage 71 is in communication with the chamber below the frustoconical barrier 15a so that the pressures within the two chambers may lbe equalized to facilitate the return of mercury through the aperture 41.

While the invention has been described with reference to specic structural characteristics and with regard to various types of material it will be appreciated that changes may be made in these structural elements as well as the general organization including the materials forming various parts of the Irelay. Such modifications and others including the types yof circuits that may be ernployed in association with the relay may be made without departing from the spirit and scope of the invention as set forth in the app-ended claims.

What I claim and desire to secure by Letters Patent is:

1. In an electromagnetically actuated relay, a sealed container, la frusto-conical barrier of electrical insulating material within said container, :a quantity of mercury within said container below said frusto-conical barrier, a quantity of mercury within said container exteriorly of said l)Srusto-conical barrier, 'an armature within said container, `an electrode carried by said armature Iadapted to extend into the mercury located exterior-ly of said ifrustoconical barrier, said frusto-conical barrier having Ian :aperture in the apex portion thereof, a second electrode carried by the armature in electrical conductive relationship with the iirst electrode adapted to depend through said aperture int-o the mercury below the frusto-conical barrier, a coil `for shifting said armature, tubular means extending above said frusto-conical barrier having yan opening therein providing a passage from an `area adjacent and under the apex portion of said barrier to a zone above said frusto-conical barrier for venting gases trapped below the frusto-conical barrier.

2. In an electromagnetically actuated relay according to claim l wherein said tubular means -is carried by said armature.

3. In an electromagnetically :actuated relay according to clai-In 1 wherein the tubular means is carried by the frusto-conical barrier.

References Cited in the rile of this patent UNITED STATES PATENTS 536,811 Lemp Apr. 2, 1895 773,119 AChristmas Oct. 25, 1904 1,604,495 Steinmayer Oct. 26, 1926 2,072,210 Klinkhamer Mar. 2, 1937

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