US2422764A - Electromagnetic relay - Google Patents

Description

June 24, 1947. F WOOD 2,422,764

- ELECTROMAGNETIC RELAY Filed May 11, 1944 FIG?) EEE a FIGS 24 1| 0 FEM INVENTOR. FREDRIC E. W000 ATTORN EY Patented June 24, 1947 ELECTROMAGNETIC RELAY Fredric E. Wood, Oak Park, 111., assignor to Alitomatic Electric Laboratories, Inc,, Chicago, 111., a corporation of Delaware Application May 11, 1944, Serial No. 535,009

4 Claims.

The present invention relates in general to improvements in electromagnetic relays and, more particularly to relays of the diminutive power type.

The principal object of the invention is to providea suitable diminutive power type relay for making and breaking circuits of high ampere inductive load.

One feature of the invention is the mounting arrangement of the movable contacts whereby the contacts are not always in the same alignment, but may make at different points at different times so that they will Wear evenly instead of pitting as is customary in contacts carryinga heavy current.

Anotherfeature of this invention is that the movable contacts are easily removable for adjustment or replacement and the design is such that extra spring tension is provided to insure a snappy break action of the contacts.

The one sheet of drawings comprising Figs. 1 to 6, inclusive, taken in connection with the following detailed description is believed suiiicient to make the invention clear.

Fig. 1 is a side view of the relay showing the general construction and placing of parts.

Fig. 2 is an end view taken from the leftof Fig. 1.

Fig. 3 is-a top View of Fig. 1.

Fig. 4 is an end view taken from the right of Fig. 1. showing only the spring contacts and the movable contact assernbly inv cross section.

Fig. 5 is a top view in detail of the leaf spring supporting the movable contact bar.

Fig. 6 is a view taken from thebottom of Fig. 5.

Referring to the drawings the electromagnetic relay will now be described in detail. As best shown in Figs. 1 and 2-the relay has asubstantially L-shaped magnetic heel-piece l to which is fastened a coil 2 by means of the mounting screw 3, and a movable magnetic armature 4 pivota1lymounted upon the free end of the heels piece I.

As best shown in- Figs. 1, 2 and 4 the armature 4' carriesa pair of spacedeapart operating arms Sand 6 each having upwardly extending ears 5.

and 5. provided with aligned holes therein. A

pivot pin 1: is inserted into the aligned holes and the outer ends of the-pivot pin 1 are flanged over in order to rigidly secure the pivot pin to the armature A. The operating arms 6 and B extend along the heelpiece on opposite sides and parallel thereto, and are. provided at the end thereof with a crossarm 8 welded or otherwise rigidly secured to the two ends of the operating arms. The

' cross-arm 8 normally rests upon a nommagnetic rivet residual l0 shown in Fig. 4 secured to and extending upwardly from the upper surface of the heelpiece I.

In order to provide a bearing surface for the pivotal armature pin 1, a nonemagnetic bearing plate [I is carried upon the upper surface of the heelpiece l adjacent to the free end thereof, and the pivot pin 1 is rotatably held against. the upper surface of the bearing plate H in a pivot pin receiving slot formed in the bottom surface of the clamping plate l2. This mounting arrangement just described is shown in detail in my pending application Serial No. 477,230., filed February 26, 1943, now Patent No. 2,397,635, issued April 2', 1946. Located directly above and fastened to the clamping plate l2 by the screws [3 and I3 are two similar spring pile-ups. Each pi1e-up consists. of an end plate such as I4, in-i sulators such as l4i", a stiff contact spring l5 with. a. heavy duty contact [5 on the free end. and a long flexible tension spring I 5. These pile,- ups are fastened to the clamping plate l2 as a unit by screws l3. and I3 and then thev units are fastened to the heelpiece l of the relay by screws llto thereby clamp the armature bearing pin 1 and bearing plate H. between the plate, 12 an heelpiece I.

The crossarm 8 fastened to the two ends of the operating arms 6 and 6", and upon which the assembly for the movable contacts is mounted as shown in thecross section view of'Fig. 4, has. two upwardly extending lugs l8. and I8. equal dis,- tances from. their respective. ends of the cross,- arm, and a threaded. hole t9 into which a screw 20, fits. The movable contact assembly consists of'first an insulating strip. 21: which has two holes, registering with the extending lugs l8 and. [8, a

clearance hole for the screw 211, and raised lugs:

22 and 212' on the upper side at each. end slightlyhigher than the thicknessofi spring 23. Second a curved leaf spring 23 made of bronze or similar material arranged. directly above insulator. 21; and. shaped as shown in Figs. Sand 6. The forks and 2.47 on each end of the leaf spring 23 slide around the insulator lugs 22 and 22', while the free ends of the tension springs 16 and 16' rest on top of lugs 22 and 22 and exert pressure to maintain the armature at normal position as shown in Fig. 4. The middle portion of the leaf spring has a center clearance hole 25 for bushing 29 and on each side of it lug receiving holes 26 and 26 to receive the lugs in the lower side of bar 21. Third a contact bar 2'! with heavy duty contacts 28 and 28 on the upper surface of each end of the bar, a center clearance hole for bushing 29 and on the underside of the bar on each side of the clearance hole, the downwardly extending lugs formed to fit into the lug receiving holes 26 and 26' of the leaf spring 23.

The parts are assembled in the same order as just described. The one screw 20 which holds the assembly together fits into a tubular bushing 29 which insulates the screw from the movable contact assembly. The tubular bushing 29 is smaller than the clearance holes in bar 21 and leaf spring 23 through which it passes, thereby allowing the contact bar 21, and the leaf spring 23 to have endwise and sidewise movement relative to the bushing. The tubular bushing 29 also has an enlarged shoulder which limits the upward movement of the contact bar 21 under pressure of spring 23 when the relay is unoperated.

Upon energization of the coil 2 the armature A is attracted and rotates about its pivot pin 1 in a counterclockwise direction, against the tension of the springs 16 and I6 as viewed in Fig. 1, from its normal position to its operated position. This action causes the crossarm 8 carried on the ends of the operating arms 8 and 6 to move upwards as seen in Fig. 4. The movable contact assembly will move upwards until the contacts 28 and 28' on the contact bar 21 hit the fixed contacts I of the stiif contact spring l5. Further upward movement of the crossarm 3 has a tendency to cause the leaf spring 23 to flatten out and build up pressure until at the end of the movement considerable tension has been stored in the leaf spring. The leaf spring 23 is thus effective to cause a snappy break of the contacts later because of the novel construction of the assembly. The leaf spring 23 is held in place by the bushing 29 and the two extending lugs 22 and 22 of the insulation strip 2| which fit into the corresponding forks 24 and 24 of the leaf spring 23.

This arrangement permits the forks at the ends of the leaf spring 23 to move inward and outward guided by the lugs 22 and 22'. This arrangement will maintain constant contact pressure.

Upon release or deenergization of the relay coil, the stored up pressure in the leaf spring 23 starts the armature moving very rapidly, but still holds the contacts closed. When the armature has gained speed and momentum, the underside of the upper portion or shoulder of the tubular insulator 29 strikes the contact bar 2? and snaps its contacts loose from the stationary contacts. The long thin tension springs IS and iii, the tensioned ends of which rest upon the lugs 22 and 22 of the insulation strip 2! completely restores the relay armature to normal. 011 the initial restoring action it is the combination of the stored up tension of the leaf spring 23 and the long thin tension springs 16 and It being applied to the operating arms that start the restoring action.

When the relay is completely restored to nor- ,mal position the crossarm 8 rests on residual Hi. This residual it) acts as a fulcrum so that the pressure applied to the crossarm by the long tension springs and I6 tends to twist the armature 4. This tends to take up any play between the pivot pin and its associated bearing surfaces and thereby prevents vibration of the armature from an external source.

While the invention has been described as embodied in a particular form, it is capable of employment in other and different forms without departing from the spirit and scope of the ap pended claims.

What is claimed is:

1. In a circuit closing arrangement, an operating member, a pair of contacts through which a circuit is to be closed, an insulating bar keyed to said member by means of a pair of holes in each end of the bar and pins on said member extending into said holes, a contact bar for engagement with said contacts, projections on said insulating bar, a flat bowed spring mounted between the contact bar'and the insulating bar having slots in each end slidable over said projections when the spring is flexed, retaining means for limiting the movement of the contact bar away from said member by means of said spring, a pair of tension springs engaging the ends of said projections and tending to move the contact bar away from said contacts, said bar moved to engage said contacts when the member is moved against the tension of said tension springs, said tension springs permitting free movement of said fiat bowed spring along said projections when the flat spring is fiexed or bowed, said tension springs and said fiat spring acting together to cause a quick movement of the contact bar away from said contacts.

2. In a circuit closer, a pair of contacts, means for closing a circuit through said contacts comprising a metallic contact bar, a metallic operating bar, a strip of insulation mounted on said operating bar between said bars, a leaf spring mounted between said strip and said bar tensioned to hold said bars apart, a bushing mounted on said operating bar limiting the movement or" the two bars caused by said spring, a pair of tension springs resting against said strip and normally biased to hold the assembly including said bars away from said contacts, means [or ill moving said operating bar against the tension of said tension springs to cause said contact bar to engage said contacts.

3. In a circuit closer, a pair of stationary contacts, an assembly comprising a movable member and a contact bar mounted in parallel relation with a leaf spring between the two normally pressing the two apart, a bushing secured to the member, having a shoulder limiting the movement of the bar away from the member, and secured to the member to hold the assembly together as a unit, a pair of leaf tension springs exerting pressure on the ends of the member under the contacts and holding the assembly in position away from the contacts, means for applying a counter force to move the member against the tension of the pair of tension springs to move said assembly bodily to cause said bar to engage said contacts and compress said leaf spring, said contact bar moved toward said member when said leaf spring is compressed, said leaf spring and said tension springs aiding in separation of the bar from the contacts when said counter force is no longer applied.

4. In a circuit closer, a pair of stationary contacts, a contact bar, means for securing said bar to said member comprising a bushing rigidly secured to the member and having a shoulder limiting movement of the bar away from the member, a leaf spring between the bar and the member normally maintaining the two spaced apart with said bar against said shoulder, a pair of tension springs exerting pressure on said member normally holding the bar away from said contacts, and means for moving said member against the tension of said pair of springs to thereby move said bar to cause engagement of the contact bar with said stationary contacts and compress said leaf spring.

FREDRIC E. WOOD.

REFERENCES CITED The following references are of record in the file of this patent:

Number UNITED STATES PATENTS Name Date Carichofi" Aug. 29, 1905 Larson Feb. 6, 1912 Pepper June 21, 1932 Field Oct. 10, 1939 Ebert Aug. 29, 1944 Hammerly Sept. 15, 1942 Rubel May 22, 1945 Greene Feb. 14, 1939

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