US3048678A - Magnetic relays - Google Patents

Description

1952 s. F. REED ET AL 3,048,678

MAGNETIC RELAYS Filed June 10, 1960 4 t s t 1 IIIIIIIIIIIIIIIIIIIIA VII/i1 .75. E I. 0

INVENTORS STANLEY E REED DONALD E. REED EMMETT F. DEADY ATTORNEY FIG. I

Aug. 7, 1962 s. F. REED ET AL 3,048,678

MAGNETIC RELAYS Filed June 10, 1960 4 Sheets-Sheet 2 //V VE N 7' OR? STANLEY F. REED DONALD E. REED EMMETT E DEADY ATTORNEY Aug. 7, 1962 s. F. REED ET AL 3,048,678

MAGNETIC RELAYS Filed June 10, 1960 4 Sheets-Sheet 3 f 4 /2 f 2' /2 f 701 g 723 702 f ful vzs Fla STANLEY F'REED DONALD E. REED EMMETT F DEADY ATTORNEY Aug. 7, 1962 s. F. REED ET AL 3,043,678

MAGNETIC RELAYS Filed June 10, 1960- 4 Sheets-Sheet 4 V/l/I/I/Il/IIIIII/l/I/I FIG. l4.

g/f/IIIIIKII13IZI/IfiI/I/II/III? v 1 "III/[ I III/I/I/I/IIII/I/II/IIIIII/I/Ib x g g INVENTORS STANLEY F. REED \E DONALD E. REED EMMETT F. DEADY.

ATTORNEY FIG. l3.

United States Patent 3,048,678 MAGNETIC RELAYS Stanley F. Reed, McLean, Va., Donald E. Reed, Kenslngton, Md., and Emmett F. Deady, Arlington, Va., as-

signors, by mesne assignments, to Space Components Inc., Washington, D.C., a corporation of the District of Columbia Filed June 10, 1960, Ser. No. 31,509 20 Claims. (Cl. 200-93) This invention relates generally to electric circuit relays of the polarized type and specifically provides a polarized relay structure of simplified form which 18 economical to produce.

It is a particular object of this invention to provide polarized electric circuit relays which are simple in design, economical to fabricate, reliable in operation and readily adaptable to size modification dependent upon the nature of the intended utilization.

It is a second object to provide such relays having a minimum number of parts and a minimum number of precision operations in the fabrication thereof and yet have at least the operating characteristics and reliability of prior art relays.

It is a third object to provide such relays in which no spring loaded members are utilized in the electrical or magnetic circuits and therefore no spring elements are subject to fatigue and eventual failure.

It is a fourth object to provide such relays which are magnetically secured in each of their operating positions.

It is a further object to provide novel and useful constructions for relays in which the above objects are attained.

These, together with other objects and advantages which will become subsequently apparent, reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming a part hereof, wherein like numerals refer to like parts throughout, and in which:

FIG. 1 shows a perspective view in partial section of a first form of the relay of this invention.

FIG. 2 shows a central sectional elevational view of the device of FIG. 1.

FIG. 3 shows a sectional plan view of the device of FIGS. 1 and 2 taken substantially as indicated by line 33, FIG. 2.

'FIG. 4 shows diagrammatically an alternative armature-pole piece orientation which may be utilized with therelay of FIGS. 1 to 3.

FIG. 5 shows diagrammatically the armature-pole piece orientation of the relay of FIGS. 1 to 3 and a flux path associated therewith.

FIG. 6 shows diagrammatically another armature-pole piece orientation which may be utilized with the relay of FIGS. 1 to 3. p 7

FIG. 7 shows diagrammatically an additional armaturepole piece orientation which may be utilized with the relay of FIGS. 1 to 3.

FIG. 8 shows diagrammatically a further armaturepole piece orientation which may be utilized with the relay of FIGS. 1 to 3.

'FIG. 9 shows diagrammatically another armature-pole piece orientation which may be utilized with the relay of FIGS. 1 to 3.

FIG. 10 shows a perspective View in partial section of a second form of the relay of this invention.

FIG. 11 shows a central sectional elevational view of the device of FIG. 10.

FIG. 12 shows a sectional plan view of the device of FIGS. 10 and 11 taken substantially as indicated by line 12--12, FIG. 11. Y

3,048,678 Patented Aug. 7, 1962 ice FIG. 13 shows a perspective view in partial section of 'a third form of the relay of this invention.

FIG. 14 shows a central sectional elevational view of the device of FIG. 13.

FIG. 15 shows a plan view of the device of FIGS. 13 and 14 taken substantially as indicated by line 1515, FIG. 14, with top closure removed.

Referring now to the drawings, the first form of our invention is shown in FIGURES l to 3. The relay container 1 comprises an annular housing 2, a header 3, an adjustable closure assembly 4, a supporting cover 5, and a separating closure 6. Header 3, closure assembly 4, and separating closure '6 may be hermetically sealed to housing 2 to provide a hermetically sealed coil chamber 7 and a hermetically sealed contact chamber 8. Supporting cover 5 may also be sealed to housing 2, but such a seal would be unnecessary for most generalpurpose relays. Two operating electromagnets 9 are provided within coil chamber 7. Each electromagnet 9 comprises a U -shaped pole piece 10, a coil of insulated wire 11, insulating boards 12 at each end thereof, and leads 13 connectable to a source of direct current potential through control-circuit header pins 14 extending through header 3. Pins 14 are hermetically sealed in header 3, and pole piece terminal portions 15 are herv metically sealed in separating closure 6. Pole piece terminal portions 15 form a generally quadrangular configuration substantially flush with the upper surface of separating closure 6. Electro-magnets 9 may be entirely supported by their pole piece terminal portions 15 or the entire coil chamber '7 may be filled with an encapsulating material after assembly and thereby support the elements therein. An armature 16 is pivotally retained within contact chamber 8 and is operable to retain one oftwo operating positions. Armature 16 is of H-shaped configuration with the cross-member 17 there of being permanently magnetized along the longitudinal axis thereof to provide two operative magnetic poles of opposite polarity at the ends thereof; and with the leg elements 18 thereof being integrally secured in fixed rela tion theretoQand consisting of magnetically responsive material. The terminal portions 19 of the leg elements 18 are substantially adjacent to terminal portions 15 of pole pieces 10. Coils 11 are connected to a source of direct current potential and may be connected in such a manner that only one coil 11 is energized at a time or preferably in such a manner that both coils 11 are energized and aid in the motion of armature 16. Due to the permanent magnetization of cross-member 17, even when coils 11 are deenergized, the magnetically responsive leg elements 18 of armature 16 retain a minimal magnetization of the same polarity as the pole of magnetized cross-member 1'7 integral therewith. Therefore, the coil 11 of one electromagnet 9 may be connected to the potential source to attract one set of terminal portions 19 of armature leg elements 18 and the coil 11 of the second electromagnet 9 connected to the potential source to repel the second set of terminal portions 19 of armature leg elements 18 thereby bringing armature 16 to a first operating position. Further, when the polarity of the applied potential is reversed, the magnetic circuit interaction of pole piece terminal portions 15 and terminal portions 19 of leg elements 18 would be reversed and the armature 16 rotated to the second of two operating positions. It should be noted that this minimal magnetization will retain armature 16 in the last operating position until at least a minimal pulse of current of proper polarity is applied to electromagnets 9. Further, it is clear from the above that armature 16 is operable from one of said two operating positions to the other of said two operating positions upon the passage of a minimal operating current pulse, and that armature 16 will remain in this position until a minimal pulse of current of opposite polarity is applied to electromagnets 9, and that the maintenance of current is not required to operate this relay. An adjustable closure assembly 4 is provided to enclose the contact chamber 8, and is shown to cornprise annular elements and 21 held in relative position by stiff diaphragm 22 hermetically sealed thereto. Annular element 20 has two sets of paired contacts 23 mounted thereon and insulated therefrom. Supporting cover '5 is secured to housing 2 and serves the pimary function of supporting four adjusting screws 24 so that they may be displaced with respect to adjustable closure assembly 4 and thereby provide adjustment of contacts 23 with respect to armature 16. Such adjustment, provided without impairing the hermetic seal of the contact chamber 8, serves the dual purpose of allowing variation in operating characteristics, and in reducing the precision required in the fabrication of this type of relay. Contacts 23 are connected to pass-through pins 25 hermetically sealed in separating closure 6 and pass-through pins 25 are connected to controlled-circuit header pins 26 hermetically sealed in header 3. Mounted between leg elements 18 of armature 16 on each side of cross-member 17 are insulating support blocks 27 and mounted thereon are contact blocks 28. It should he especially noted that armature 16 is disposed in two planes inclined at a slight angle and meeting along the cross-member 17 thereof and that contacts 23 are so disposed that the terminal portions 19 of leg elements 18 never make contact with pole piece terminal portions 15, but rather leave a minimal air gap 29 therehetween. It is seen that the two operating magnetic circuits of this relay include a pole piece 10, one half of each leg element 18 of armature 16, permanent magnet cross-member 17, and the two minimal air gaps 29 at each end of the associated pole piece 10. Minimal air gaps 29 serve the dual functions of always providing a magnetically maintained contact pressure between contacts 23 and their respective contact blocks 28; and eliminating the objectionable formation of local poles in the terminal portions 19 of leg elements 18.

Alternative methods of providing a hermetically sealed contact chamber and adjustability of contact displacement would include terminating housing 2 at separating closure 6; mounting contacts 23 on a rigid closure member equivalent to annular element 20; providing a sealed bellows between separating closure 6 and such rigid closure member; and mounting the rigid closure member on four spring-loaded adjusting screws external to said bellows to provide relative motion between said separating closure 6 and said rigid closure member. It should he noted that the form of relay disclosed in FIGS. 1 to 3 is specifically adapted to provide a hermetically sealed coil chamber 7 and a hermetically sealed contact chamber 8. However, in the event that only sealed enclosures are required, O-ring seals may be substituted for any of the hermetic seals utilized therein, and in the event that such seals are not required, the supporting structure and fabrication may be simplified by the elimination of any of these seals, thereby allowing the use of a straight core for the electromagnets 9 with the ends thereof disposed adjacent to the terminal portions 19 of the leg elements 18 of the H-shaped armature 16. Further, annular element 20, separating closure 6, and header 3 may be composed of insulating material, such as ceramic, or from conducting material and the contacts associated therewith insulated therefrom.

While the form of the invention shown in FIGS. 1 to 3 has been disclosed as a two position stable relay, without physical modification, but by the exaggerated displacement of adjusting screws 24, one set of contacts 23 may he displaced so as to prevent armature 16 from reaching a central position and thereby convert this device into a one-position stable relay which would always assume one position upon deenergization and would assume one of two positions upon energization dependent upon the polarity of the energizing potential.

' other operative position.

Further, it should be noted that while contacts 23 have been shown side by side and contact blocks 28 utilized to complete the electrical circuit, other specific utilizations of the relay of FIGS. 1 to 3 might eliminate contact blocks 28 and permit passage of the controlled-circuit current through a portion of armature 16 itself, or one stationary contact 23 provided and the circuit completed through armature 16 by means of a pivot contact or a pig-tail connection.

FIGS. 4 to 9 illustrate in diagrammatic form alternative configurations of separating closure, and armature which may he utilized in the relay shown in FIGS. 1 to 3 to provide the necessary relative motion therehetween.

In FIG. 4, terminal portions 115 of pole pieces extend substantially above the surface of separating closure 106, armature 116 is planar, and the terminal portions of pole pieces 110 are angled to provide the minimal effective air gap 129 therebetween when armature 116 is in its operative positions.

In FIG. 5 armature 216 and separating closure 206 are similar to the analogous elements of FIGS. 1 to 3. A flux path 200 is illustrated in dot-dash lines and it is to be understood that a similar flux path is provided through the opposite half of the armature 216 when it is in the Further, it should be understood that analogous fiux paths 200 are provided for each alternative: form of relay disclosed. In FIG. 6 the separating closure 306 is angled rather than the armature 316.

In FIG. 7 both separating closure 406 and armature 416 are angled downward and in FIG. 9 both separating closure 506 and armature 516 are angled upward. It should he noted that for configurations such as shown in FIGS. 7 and 9, the retaining pivot structure may he eliminated for special-type relays with the armature merely supported by the angled separating closure. This will allow inherent wiping action at the contact surfaces without sacrificing the springless nature of the device.

In FIG. 8 both separating closure 606 and armature 616 are planar with the pivot point 600 of the armature 616 raised substantially above the separating closure 606 and the terminal portions 619 of the leg elements chamfered as shown at 650 to provide a minimal air gap.

The form of relay shown in FIGS. 1 to 3 utilized with an extreme modification of the armature-pole piece orientation of FIG. 9 would result in the folding of the leg portions into a single element and provide a U-shaped armature such as shown in FIGS. 10 to 12.

The relay of FIGS. 10 to 12 is functionally analogous to the relays of FIGS. 1 to 9, but in place of the H-shaped armature, a U-shaped armature 716 is utilized. This is a more compact, less versatile modification and superior in operation for some purposes. The relay container 701 comprises housing 702, header 703, top closure 704, and separating closure 706. Each of these container elements may be hermetically sealed to its mating elements to produce a hermetically sealed coil chamber 707 and at hermetically sealed contact chamber 708. In this embodiment, separating closure 706 is in the form of a V-shaped trough 760 with transverse ends 761. Transverse ends 761 support retaining boss 762 which is recessed to provide a spring cavity 763 to spring load a ball pivot 764. A pair of these pivots is provided to secure armature 716 in pivotal relation to the stationary portions of the relay. Controlled circuit contacts 723 are hermetically sealed in the separating closure 706, and both controlled circuit pins 726 and control circuit pins 714 are hermetically sealed in header 703. Leg elements 718 and permanent magnet cross-member 717 are integrally secured in fixed relation. An insulating block 727 is supported between leg elements 718 of armature 716, and contact blocks 728 are mounted on either side thereof. The electrical connections and operation of this relay are analogous to those of the relays of FIGS. 1 to 9, except that the flux path for each side of this relay would pass through the same portion of leg elements 718 and permanent magnet cross-member 717 of U-shaped aramature 716'.

The relay of FIGS. 13 to 15 is a further embodiment of the relay of this invention. The relay container 801 comprises housing 802, header 803, separating closure 806 and top closure 804. Each of these container elements may be hermetically sealed to its mating elements to produce a hermetically sealed coil chamber 807 and a hermetically sealed contact chamber 808. In this embodiment, the two electromagnets 809 are disposed in the coil chamber 807 in the shape of an X, thereby producing a quadrangular pattern in the contact chamber 808, but with opposite corners of the quadrangle connected by pole pieces 810*. Pole pieces 810 extend substantially above separating closure 806 and are hermetically sealed therein. In order to provide a minimal air gap 829 and to improve the magnetic circuits associated therewith, terminal portions 815 of pole pieces 810 are provided with flat portions 870. An I-shaped armature 816 is provided with a permanent magnet central portion 817 magnetized along the longitudinal axis thereof, and two ends 818 of magnetically responsive material. Armature 816 is pivoted at 871 for motion in the plane parallel to separating closure 806. At least one contact block 828 is insulatedly supported on armature 816 to complete the controlled electrical circuit. It should be noted that contacts 823 are so positioned as to provide minimal air gaps 829 for each operative position of armature 816. The electrical conncetions and operation of this relay are analogous to those of FIGS. 1 to 12.

The modifications with respect to seal and contact orientations discussed hereinabove with respect to the embodiment shown in FIGS. 1 to 3 can be incorporated in the embodiments of FIGS. to 12 and 13 to 15.

It should be noted that each of these armatures which are disclosed as a composite of a central portion and end portions might be fabricated of powdered constituents of different magnetic permeabilities and retentivities so arranged as to provide a maximum permanent magnetization at the central portion of the armature and a minimal permanent magnetization at the ends thereof. Further, it should be noted that while each of the pole pieces has been represented as of unitary U-shaped configuration, any of the pole pieces of the relays of this invention could be fabricated of three or more elements to facilitate assembly procedures. In addition the U-shape shown may be utilized, but instead of the pole pieces being integrally secured in the separating closure, magnetically responsive inserts may be hermetically sealed in the separating closure immediately adjacent to the terminal portions of the pole pieces and the electromagnets supported by other conventional means. Moreover, in place of the two electromagnets shown, one electromagnet may be utilized with a single pole piece, but with said pole piece terminating in a Y-shaped configuration at each end thereof, thereby providing four terminal portions forming a generally quadrangular pattern with diagonally opposite corners of said quadrangle comprising magnetic poles of opposite polarity. These four terminal portions would function in the same manner as the terminal portions illustrated when two electromagnets are utilized.

The invention has been described in connection with several exemplary embodiments therefor, but it is to be understood that these embodiments are given by way of illustration and not limitation; other changes and modifications in the details of the apparatus can also be made without departing from the spirit of the invention as defined in the appended claims.

We claim:

1. In an arrangement of the character described; a housing; two electromagnets supported within said housing, each of said electromagnets having an energizing coil adapted to be connected to a difference of potential and a pole piece having two terminal portions, said terminal portions forming magnetic poles of opposite polarity only whenever a difference of potential of a predetermined magnitude is applied to said coils; an armature pivotally mounted within said housing for movement between first and second operative positions, said armature comprising a central portion and at least two operative end portions, said central portion being permanently magnetized and said end portions consisting of magnetically responsive material integrally secured in fixed relation to said central portion, said end portions of said armature and said terminal portions of said pole pieces so oriented that said armature assumes the first of said operative positions whenever a difference of potential of a first polarityis applied to said coils and assumes the second of said operative positions Whenever a difference of potential of polarity opposite to said first polarity is applied to said coils; at least one contact supported'within said housing; a portion of an electrical circuit within said housing including said contact; a contact member operatively associated with said armature to close said portion of said circuit including said contact whenever said armature assumes one of said operative positions, whereby the conductivity of said circuit is controllable by the energization and polarity of said coils.

2. The combination set forth in claim 1, wherein said contact is so positioned with respect to said armature that said end portions of said armature are always separated from said terminal portions of said pole pieces by a predetermined air gap.

3. The combination set forth in claim 1, wherein said armature is substantially H-shaped.

4. The combination set forth in claim 3, wherein said contact is so positioned with respect to said armature that said end portions of said armature are always separated from said terminal portions of said pole pieces by a predetermined air gap.

5. The combination set forth in claim 1, wherein said armature is substantially U-shaped.

6. The combination set forth in claim 5, wherein said contact is so positioned with respect to said armature that said end portions of said armature are always separated from said terminal portions of said pole pieces by a predetermined air gap.

7. The combination set forth in claim 1, wherein said armature is substantially I-shaped. I

8. The combination set forth in claim 7, wherein said contact is so positioned with respect to said armature that said end portions of said armature are always separated from said terminal portions of said pole pieces by a predetermined air gap.

9. In an arrangement of the character described; an enclosing container having a housing, a header, a closure member, and a separating closure, said closure member and said separating closure hermetically sealed to said housing to provide a hermetically sealed contact chamber; said separating closure, said housing, and said header cooperating to provide a coil chamber; a pairof electromagnets positioned within said coil chamber; each of said electromagnets comprising a pole piece with two terminal portions and an energizing coil of insulated wire; said energizing coils adapted to be connected to a (litterence .of potential; said two terminal portions of each of said pole pieces forming magnetic poles of opposite polarity only whenever a difference of potential of a predetermined magnitude is applied to said coils; said we minal portions of said pole pieces hermetically sealed in said separating closure in a generally quadrangular pattern; an H-shaped armature pivotally mounted in said contact chamber for movement between first and second operative positions; said armature comprising a permanent magnet cross-member and two leg elements integrally secured in fixed relation thereto, said leg elements having terminal portions comprising magnetically responsive material; said terminal portions of said leg elements operatively associated with said terminal portions of said pole pieces so that said armature assumes said first operative position whenever said coils are connected to a difference of potential of a first polarity and assumes said second operative position whenever said coils are connected to a difference of potential of polarity opposite to said first polarity; at least one contact supported within said contact chamber; a portion of an electrical circuit within said contact chamber connected to said contact; a contact member operatively associated with said armature to close said portion of said circuit whenever said armature assumes one of said operative positions, whereby the conductivity of said circuit is controllable by the energization and polarity of said coils.

10. The combination set forth in claim 9, wherein said coil chamber is hermetically sealed.

11. The combination set forth in claim 9, wherein said contact is so positioned with respect to said armature that said terminal portions of said leg elements are alway separated from said terminal portions of said pole pieces by a predetermined air gap.

12. The combination set forth in claim 11, wherein said coil chamber is hermetically sealed.

13. In an arrangement of the character described; an enclosing container having a housing, a header, a closure member, and a separating closure, said closure member and said separating closure hermetically sealed to said housing to provide a hermetically sealed contact chamber; said separating closure, said housing, and said header cooperating to provide a coil chamber; a pair of electromagnets positioned within said coil chamber; each of said electromagnets comprising a pole piece with two terminal portions and an energizing coil of insulated wire; said energizing coils adapted to be connected to a difference of potential; said two terminal portions of each of said pole pieces forming magnetic poles of opposite polarity only whenever a difference of potential of a predetermined magnitude is applied to said coils; said terminal portions of said pole pieces hermetically sealed in said separating closure; a U-shaped armature pivotally mounted in said contact chamber for movement between first and second operative positions; said armature comprising a permanent magnet cross-member and two leg elements integrally secured in fixed relation thereto, said leg elements having terminal portions comprising magnetically responsive material; said terminal portions of said leg elements operatively associated with said terminal portions of said pole pieces so that said armature assumes said first operative position whenever said coils are connected to a difference of potential of a first polarity and assumes said second operative position whenever said coils are connected to a difference of potential of a polarity opposite to said first polarity; at least one contact supported within said contact chamber; a portion of an electrical circuit within said container connected to said contact; a contact member operatively associated with said armature to close said portion of said circuit whenever said armature assumes one of said operative positions, whereby the conductivity of said circuit is controllable by the energization and polarity of said coils.

14. The combination set forth in claim 13, wherein said coil chamber is hermetically sealed.

15. The combination set forth in claim 13, wherein said contact is so positioned with respect to said armature that said terminal portions of said leg elements are always separated from said terminal portions of said pole pieces by a predetermined air gap.

16. The combination set forth in claim 15, wherein said coil chamber is hermetically sealed.

17. In an arrangement of the character described; an enclosing container having a housing, a header, -a closure member, and a separating closure, said closure member and said separating closure hermetically sealed to said housing to provide a hermetically sealed contact chamber; said separating closure, said housing, and said header cooperating to provide a coil chamber; .a pair .of electromagnets positioned within said coil chamber; each of said electromagnets comprising a pole piece with two terminal portions and an energizing coil of insulated wire; said energizing coils adapted to be connected to a difference of potential; said two terminal portions of each of said pole pieces forming magnetic poles of opposite polarity only whenever a difference of potential of a predetermined magnitude is applied to said coils; said terminal portions of said pole pieces hermetically sealed in said separating closure in a generally quadrangular pattern; an I-shaped armature pivotally mounted in said contact chamber for movement between first and second operative positions; said armature comprising a permanent magnet central section and two end portions integrally secured in fixed relation thereto, said end portions comprising magnetically responsive material; said end portions of said armature operatively associated with said terminal portions of said pole pieces so that said armature assumes said first operative position whenever said coils are connected to a difference of potential of a first polarity and assumes said second operative position whenever said coils are connected to a rdifierence of potential of a polarity opposite to said first polarity; at least one contact supported within said contact chamber; a portion of an electrical circuit within said container connected to said contact; a contact member operatively associated. with said armature to close said portion of said circuit whenever said armature assumes one of said operative positions, whereby the conductivity of said circuit is controllable by the energization and polarity of said coils.

18. The combination set forth in claim -17, wherein said coil chamber is hermetically sealed.

19. The combination set forth in claim 17, wherein said contact is so positioned with respect to said armature that said end portions of said armature are always separated from said terminal portions of said pole pieces by a predetermined air gap.

20. In an arrangement of the character described; a housing; electromagnet means supported within said housing, said electromagnet means having energizing coil means adapted to be connected to a difference of potential and pole piece means with four terminal portions magnetically associated therewith, said four terminal portions oriented to form a generally quadrangular pattern, said four terminal portions forming four magnetic poles only whenever a diiference of potential of a predetermined magnitude is applied to said coil means with the terminal portions at diagonally opposite corners of said quadrangle forming magnetic poles of opposite polarity; an armature pivotally mounted within said housing for movement between first and second operative positions, said armature comprising a central portion and at least two operative end portions, said central portion being permanently magnetized and said end portions consisting of magnetically responsive material integrally secured in fixed relation to said central portion, said end portions of said armature and said four terminal portions so oriented that said armature assumes the first of said operative positions whenever a difference of potential of a first polarity is applied to said coil means and assumes the second of said operative positions whenever a difference of potential of polarity opposite to said first polarity is applied to said coil means; at least one contact supported within said housing; a portion of an electrical circuit within said housing connected to said contact; a contact member operatively associated with said armature to close said portion of said circuit including said contact whenever said armature assumes one of said operative positions, whereby the conductivity of said circuit is controllable by the energization and polarity of said coil means.

(References on following page) References Cited in the file of this patent UNITED STATES PATENTS 838,192 Kitsee Dec. 11, 1906 2,515,771 Hall July 18,1950 2,636,094 Russell Apr. 21, 1953 5 2,794,157 Chisholm May 28, 1957 Russell et a1. Nov. 25, 1958 Babcock Feb. 3, 1959 Fisher Apr. 28, 1959 Wharton Oct. 27, 1959 Fischer June 14, 1960 Rhodes Mar. 21, 1961

Images