Armature keeper for an electromagnetic relay

Oct. 29, 1957 , _{u EARLE 2 8n 681}

ARMATURE KEEPER FOR AN ELECTROMAGNETIC RELAY Original Filed Oct. 26, 1950

FIG. I

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United States Patent Office

2,811,681

Patented Oct. 29, 1957

2,811,681

ARMATURE KEEPER FOR AN ELECTROMAGNETIC RELAY

Edwin L. Earle, Chicago, Ill,, assignor, by mesne assignments, to International Telephone and Telegraph Corporation, a corporation of Maryland

Original application October 26, 1950, Serial No. 192,260.

Divided and this application December 2, 1953, Serial ¹⁰No. 395,717

Claim. (CI. 317—198)

This invention relates to an armature keeper for an 15 electromagnetic relay, particularly of the type used in telephone switchboards. Its principal object is to provide a new and improved retaining structure which facilitates maintenance of the armature keeper aligned in its desired adjusted position while being secured in that position. 20

General description

This application constitutes a division of my prior application, Serial No. 192,260, filed October 26, 1950, for a General Purpose Relay, now Patent No. 2,686,85θ’ ²⁵

In the relay construction to which this invention is directed, a relay comprises essentially (1) a spring stack, (2) an armature for operating it, and (3) an electromagnet for controlling the armature. The electromagnet has a return plate on the end of which the armature is rotatably held by an armature keeper secured to the return plate by a screw. A specific object of the invention is to maintain the keeper aligned in its desired adjusted position while its securing screw is being tightened

In carrying out the stated specific object, the upper surface of the magnetic support plate has a raised guide aligned with the securing screw, and the armature keeper has a notched-out portion, or slot, which receives both the screw and the guide. A feature of this construction is that approximate alignment of the keeper with the armature is assured in addition to the prevention of rotation of the keeper out of its position of adjusted alignment when the securing screw is being tightened.

Other objects and features will appear as the descrip- 45 tion progresses.

Fig. 1 is a plan view of a relay embodying the invention.

Fig. 2 is a side elevation view of the relay of Fig. 1.

Fig. 3 is a plan view of the device with the switch assembly removed. ₅θ

Fig. 4 is a front elevation view of the structure of Fig. 3 with the armature assembly removed.

Referring particularly to Figs. 1 and 2, the relay includes an electromagnet 10, its armature 11, a twin stack switch assembly 12 both stacks of which are actuable 55 by the electromagnet through the armature, and an Lshaped return plate 13 on which the switch assembly and armature are mounted.

The electromagnet 10 includes a coil 14 and a cylindrical magnetic core 16 extending therethrough. The 60 rear end of the core is threadedly received within an opening in the vertical portion of the return plate 13 rendering it longitudinally adjustable. A locknut 17 is provided to retain the core in a desired longitudinal position 01 adjustment.

^J 65 ' The electromagnet 10 has a rounded front spoolhead 18 flat on its upper edge, and a square rear spoolhead 19 which may be seen in profile in Fig. 4. The flat edges of the spoolheads retain this coil against rotation by reason of the squared relation of one edge of each with the under 70 surface of the horizontal portion of the return plate 13.

Rearwardty extending winding terminals 20 for coil 14 are located in a row along the lower edge of the rear spoolhead 19. The upstanding base portions of the terminals are kept out of engagement with the vertical rear portion of the return plate 13 by an insulating spacing collar 21, which encircles the core 16 between the return plate 13 and the spoolhead 19.

_Λ The coil is retained in its longitudinal position at the iront of the electromagnet by a spring clip 22 engaged within an annular groove in the front portion of the core.

As shown in Figs. 1, 2, and 3, the armature is held in position at the front of return plate 13 by a keeper-member 23. The keeper-member 23 is provided with a pair of arms 24 preferably disposed, as shown in Fig. 2, so that they make about equal angles with parts 26 and 27 which comprise the angularly disposed arms of the bellcrank armature 11. The smooth working surfaces of such arms bear against the bent portion of armature 11 to prevent its upward or forward displacement. As shown in igs. 1 and 3, lateral movement of the armature is prevented by the rounded side portions of portion 28 of the keeper. This method of mounting the armature insures its reliable operation when mounted in any desired altitude.

To enable the keeper-member 23 and armature to be mounted on the return plate, an aperture or cut-out portion is provided in the arm 26 of armature 11 through which a flat bifurcated extending portion 28 of the keeper may be fastened to the return plate 13. The bifurcated extension portion comprises a pair of arms 29 defining a slot within which a fastening screw 30 is snugly accommodated for threaded engagement with a hole in the top of the return plate 13 so that the arms 29 can be either tightened against the return plate or slidably disengaged from the return plate upon loosening the screw 30

A raised cylindrical guide portion 31 is formed on the upper surface of the return plate just behind the screw 30 and underlying the front part of the switch assembly by a semi-perforating operation on the under side of the return plate. The raised portion 31 cooperates with the slot m the armature keeper to key it against rotation while the retaining screw 30 is being tightened in place. Besides keying the keeper against rotation the raised portion 31 is also used as a. guide to locate the keeper in proper position for association with the armature 11. That is while the keeper 23 is being mounted, the screw 30 and the raised perforation 31 both act to automatically align the keeper laterally by reason of their fixed location one behind the other on the return plate 13 and their snug nt within the slot formed in the keeper extension 28 by ™ ²⁹‘ ^{The Jength} ,^{of the sl}°t may be made such tnat the keeper can be longitudinally positioned by merely in ^ln™ 5^{earwardly until the} “d of the slot hits the screw r κ I “ ^{sucb an ari-}angement, mounting and removal of the keeper and armature may be effected without complete removal of the screw 30, and both parts may be mounted on the return plate without the need for special lateral or longitudinal aligning procedures.

In its deenergized state, the normal or back-stop position of the armature is regulated by the setting of the screw 33 m the keeper-member 23, while a locknut 34 associated therewith locks the screw 33 in a desired position.. A U-shaped residual plate 35, shown in Fig 2 is applied to the armature and then crimped in place’ to appear as shown. Such plate, when employed, lies between tne core and the armature. By striking the core it holds the armature out of contact therewith to insure that a desired amount of operating air gap remains unclosed with the armature in fully operated position. This is commonly referred to as the residual gap which has a length determined by the thickness of plate 35, and controls the release characteristic of the relay, as is commonly known.

2,811,681

The twin-stack switch assembly of Figs. 1 and 2 includes a cap-plate 37, base plate 38, and parts clamped between them by screws 40 which pass through openings in the cap-plate and intervening parts to the base plate, wherein they are threadedly received. Two opposed columns 42 and 43 of the contact sets are included in the same unitary assembly 12. This construction enhances rigidity and reduces the number of assembly and clamping screws required. The switch assembly is readily installed in position on return plate 13 and are simply secured by two mounting screws 41 which pass through the assembly for threaded engagement with apertures 41α in the upper surface of the return plate· The switch assembly lies flatly upon the return plate with the protruding ends of clamping screws 40 thereof being received in provided clearance openings 40α in the return plate.

The traveling blades of both columns are moved by a pair of similar actuating ladders 58, as shown in Figs. 1 and 2, which move the blades into and out of electrical contact with the fixed blades of their respective contact sets in response to movement of the associated armature. The ladder 58 which is provided for column 42 is actuated simultaneously with the ladder 58 of column 43 by the armature 11. Each of the contact blades of columns 42 and 43 has a terminal portion 60 for the attachment of circuit wires. The terminals are staggered as shown in Fig. 1 for wiring convenience.

Upon energization of the electromagnet 10, the associated armature 11, turns about its axis to bring its lower attracted portion 27 into contact with the dome end of the core 16 which provides an adjustable front stop for the armature.

Upon deenergization of the electromagnet, the downward tension, of the associated traveling blades of the switch assembly serve to return the armature to its normal position, and as indicated, the normal or back stop position of the armature is regulated by the setting of screw

33. Turning the screw in the opposite direction permits a more expanded return movement of the armature. Locknut 34, when tightened, locks screw 33 in the desired position which in many instances will be dependent upon the residual gap which will provide the operating timing desired.