US2407633A - Retarded relay - Google Patents

Description

S 1946- L. w. DROEL. I 2,407,633

RETARDED RELAY Filed July 15, 1943 INVENTOR. LOUIS W. DROEL ATTORNEY Patented Sept. 17, 1946 UNITED RETARDED RELAY Louis W. Droel, Qak Park, Ill., assignor to Automatic Electric Laboratories, Inc., Chicago, 111., a

corporation of Delaware Application July 15, 1943, Serial No. 494,769

Claims. 1

Thi invention, relates in general to electromagnetic relays and more particularly to relays of the retarded type having pivotally mounted armatures which are retarded. in both their operating and releasing operations.

An electromagnetic relay of the conventional type comprises a field structure, a core provided with an operating winding, a pivotal armature mounted. on the field structure, and contact springs. operatively associated with the operating arm of the armature.

It is the object of the present invention to provide an improved retarding means for the relay armature which both frictionally retards the movements of the armature and which also eliminates vibration of the armature mass from an external cause, such as is encountered when the relay is mounted in a tank, airplane, or other vibratory machinery.

Relays having armatures of the pivot pin type have been extensively used in telephone systems and have proved very satisfactory. However, due to manufacturing tolerances between the pivot pin and the bearing holes for the pivot pin, it has been found that relays of this type, when subjected to constant vibration from an external source, are subject to. stresses not present in the normal use of these relays. Tests. have shown that the vibration caused excessive wear on either the bearing surfaces for the pivot pin or upon the pivot pin itself, thereby interfering with the nor-- mal operating characteristics. of the relay. The analysis of this excessive wear shows that it results from at least two difierent typesv of motions.

The armature exerts a turnim proportional to its mass and the rate and the directions of the vibrations. This tends to produce oscillations of the armature transverse to the axis of the pivot pin at a rate corresponding to the vibration rate.

If the vibration are in a plane which includes a pivot pin and the center of mass of the armature, a force is exerted which tends to make the pivot pin chatter in the bearing surface at a rate proportional to the vibration rate.

A feature of the invention is to retard the op erating and releasing movement of the armature and to eliminate the above mentioned motions of the armature produced by external vibrations of a relay by tensioning a spring against the operating arm of the armature at right angles to its movement. The tension applied by the spring to the operating arm has two effects: one is to frictionally retard the operating and releasing movements of the armature in accordance with the amount of tension in the spring; and the other is to exert a twisting action or torque on the armature bearing pin at its associated bearing holes in the relay yoke. This twisting action maintains the pivot pin in constant engagement with the bearing surfaces of the bearing hole and elimihates the objectionable vibratory motions of the armature from external causes.

In addition, the retarding spring has an inclined surface, or offset, over which the operating arm of the armature must move to thereby increase the frictional pressure to retard the operation of the armature in its operating stroke in its initial movement.

Other objects and features of the present invention will be apparent by reference to the fol lowing specificationtaken in connection with the accompanying drawing in which:

Fig. 1 is a partially perspective view of the relay;

Fig. 2 is aside view of the relay;

Fig. 3 is another side view of the relay; and

Fig. 4 is a cross-section of the relay taken on the lines AA in Fig. 3.

Referring now to the drawing, the electromagnetic relay shown comprises a field structure including a core 6 provided with a winding 4, a substantially L-shaped magnetic heel piece I 9 secured to the core 55 by means of a screw 35 and a movable magnetic armature I 5 having an operat ing, arm 35 and a bushing The armature I5 is pivotally mounted upon the outer end of the heel piece IQ for cooperation with the core 6.

The armature it carries a pair of upwardly extending ears 35 provided with aligned holes therein in which the pivot pin it is rigidly secured to the cars 36 of the armature it.

A relay yoke 2% has upturned ears 372 and is provided with bearing holes 38 to provide the bearing surfaces for the pivot pin it. The yoke 25! is provided with a slot and by mean of the clamping washer and the maclnne screw 25 is adjustably secured to the heel piece iii. It is the customary procedure to assemble the armature and yoke together and to mount the armature in operating relation to the core of the relay by means of the clamping washer i3 and the machine screw 26. The spring assembly comprises an armature backstop l3 which is placed against the heel piece I9, the insulators 88, the spring contacts I, 2, 5, and 5, the metal plate 3, all of which are provided with holes through which the ma chine screws 2'5 extend through to threaded holes (not shown) in the heel piece for securing this spring assembly to the heel piece in the position shown in Fig. 3.

A retarding spring assembly is mounted on the heel piece 19 between the relay yoke 20 and the spring assembly. This assembly comprises a spring mounting bracket 2! secured to the heel piece by means of the screw 29 and the shakeproof Washer 3!. The retarding spring I1, is mounted on the upper portion of the bracket 2| by means of the screw 28, the washer l and the shake-proof lockwasher H. The spring I! is mounted at right angles to the movement of the armature arm 35, and the spring IT is tensioned against the operating arm for two purposes; one is .to cause a twisting action, of the pivot pin in the bearing holes of the relay yoke to prevent chattering or motion of the armature from external vibratory causes; the other is to provide frictional resistances to the operating arm so as to retard the operating movement of the arm 35. It will be noted in Fig. 4 that the spring I! has an offset 34 which is positioned adjacent to the operating arm so that on the initial movement of the arm 35 the inclined portion of this offset is encountered thereby increasing the frictional resistance on the initial movement of the arm when the arm begins to move over this inclined surface. Due to this inclined surface and the movement of the arm the tension against the arm 35 is gradually increased to have a retardin effect on the operating stroke of the armature. Once the armature is operated, however, and the armature arm has moved over this inclined surface (or form) the force of this spring (l1) tending to maintain the armature in its original position is removed. But with the relay armature in its operated position the friction of this spring against the armature, then tends to retard its release.

The relay is of the well-known horizontal type which has been used extensively in telephone systems and the improvement consists of the addition of the spring H which retards the operating and restoring strokes of the armature during controlled operations, due to the frictional pressure, and which also prevents the armature from oscillating or chattering due to external vibratory causes.

It is well-known that in mass production of a large number of parts which are to be assembled together, manufacturing tolerances within certain limits are resorted to in order to speed up production to allow interchangeable assembly and to reduce the cost of manufacturing such parts. For example, since relay parts are manu" factured in large numbers, manufacturing tolerances are allowed on both the pivot pin is and the pivot pin bearing holes 38 in the ears 3?. It has been found that in manufacturing the pivot pin l4 it may be oversized or undersized from the desired diameter and that the bearing holes 38 may be also oversized or undersized from the desired diameter. seen that a minimum diameter pivot pin may be assembled in a maximum diameter bearing hole of the relay yoke. Consequently, there may be considerable play between the pivot pin and the bearing hole. sembled with a pivot pin of minimum diameter mounted in a bearing hole having a maximum diameter, and the relay is mounted on an object subject .to vibrations, such as may be encountered in an airplane, tank, automobile, or other vibratory machinery, the vibration of the armature will cause a gradual wearing of the pivot pin or peening of the bearing hole or both, and thereby gradually increasing the play between these parts to such an extent that the operating characteristics of the relay will be materially affected.

According to the present invention the pressure applied at right angles to the operating stroke of the operating arm 35; as indicated by the arrow C, causes the armature to take up the play between the right-hand ear 35 of the armature, the washer l0, and the right-hand ear 3'! of the yoke as shown in Fig. 1. After this play is taken up the pressure of the spring I! against arm causes the armature I 5 to be twisted in the direc- In view of the above, it can be In the event that a relay is astions indicated by arrows D and E with the righthand portion of the pivot pin l4 pressing against the back surface of the bearing hole 38 in the right-hand ear 3! while the left-hand portion of the pivot pin presses against the front surface of the bearing hole in the left-hand ear 3! of the yoke 20. When this latter play is taken up due to the tension of the spring I! against arm 35 there is an additional twisting action of the armature as indicated by arrows F-F due to the location at which the pressure is applied to the arm 35. This cumulative twisting action, although insufiicient to materially affect the normal operation of the relay is sumcient to take up the play which may occur as a result of manufacturing tolerances and is sufficient to prevent undesired movements of the armature when such a relay is mounted on an object subject to vibration.

It will also be noted that the arm 35 is engaged by spring I! and is moved across the surfaces of spring I! during its operating and releasing strokes. The movement of the arm 35 across the surface of the spring I! is retarded by frictional pressure in accordance with the amount of tension in spring l1. As seen in Fig. 4, the arm 35 is normally engaged by spring I! at the lowermost part, or the beginning, of the inclined surface, or offset 35. The purpose of the offset 34 is to increase the frictional resistance on the initial movement of arm 35 so as to retard the initial movement of the armature to make it somewhat slow-to-operate and to assist in preventing it from operating accidentally when the relay is subjected to vibration or shock. It is therefore necessary for the relay to build up enough magnetic flux to overcome the increased frictional resistance offered by the offset 34 before the armature is initially moved from its normal position, thereby effecting a delay in the operation of said armature. As the arm 35 moves upward, as viewed in Fig. 4, the spring I! is gradually depressed thereby increasing the frictional resistance between arm 35 and spring I1. After the arm 35 has moved over the top of the offset 34, the armature has by this time moved closer to the core, thereby increasing the magnetic pull so that the frictional pressure, which has decreased as the arm moved over the offset, has very little effect on the further movement of the armature.

It should also be noted that the tension of spring I! also has a retarding effect on the armature during its release stroke to normal position, thereby rendering the relay somewhat slow-torelease. When the magnetic flux gradually dies down, the frictional pressure of spring I! against arm 35 delays, somewhat, the time at which the armature starts its restoring stroke. In addition, as the armature of arm 35 starts the slide down the offset 34 during its release stroke, the frictional pressure rapidly decreases and a restoring component force is introduced by the upward tension of the sloping surface of the offset 34 at this critical point with the result that the releasing movement of the armature is speeded up. It is at this critical point and during the speeded up release of armature l5 that the make springs I and 3 are quickly separated. This quick separation of springs I and 3 is desirable to prevent arcing or burning of the spring contacts. Thus, in addition to initially retarding the restoring stroke of the armature I5, the spring 11 with its offset 34 speeds up the release stroke at the critical point in the armature movement where certain of the springs control circuits.

Having described the invention, what is considered new and as desired to have protected by new Letters Patent is specifically pointed out in the following claims.

What is claimed is:

1. In a non-locking relay, an L-shaped heelpiece, a magnet mounted on said heel-piece, an L-shaped armature comprising an operating arm and a pivot pin, a yoke having bearing holes thru which said pivot pin extends, means for securing said yoke tosaid heel-piece thereby pivotally securing said armature to said heel-piece to complete the magnetic circuit including the core of said magnet, said heel-piece and said armature, a spring mounted on said heel-piece and normally tensioned against said operating arm to create a torque or twisting action between said armature bearing pin and the bearing holes in said yoke thereby preventing vibration of said armature from external causes while in normal position, and said spring also friotionally retarding the operating and releasing movements of said armature without maintaining or looking said armature in any operated position to make said armature somewhat slower to operate and to release.

2. In a non-locking relay, an L-shaped heelpiece, a magnet mounted on said heel-piece, an L-shaped armature comprising an operating arm and a pivot pin, a yoke having bearing holes thru which said pivot pin extends, means for securing said yoke to said heel-piece thereby pivotally securing said armature to said heel-piece to complete the magnetic circuit including the core of said magnet, said heel-piece and said armature,

a spring mounted on said heel-piece and normally tensioned against said operating arm to create a torque, or twisting action, between said armature bearing pin and the bearing holes in said yoke thereby preventing vibration of said arma ture from external causes while in normal position, the force exerted on said arm by said spring causing rotation of said armature in two planes at right angles to each other until all play between said pivot pin and bearing holes is taken up and said pivot pin is tensionally held against the bearing surfaces of said bearing holes as a result of the force applied, said spring having sufiicient tension to frictionally retard the operation of said armature during its operating stroke to thereby make said armature somewhat slower to operate, the shape of said spring and the tension thereof being insuiiicient to maintain or lock said armature in operated position, and said spring tension being sufiicient to retard the releasing movement of said armature during its release stroke to thereby make said armature somewhat slower to release.

3. In a non-locking relay, an L-shaped heelpiece, a magnet mounted on said heel-piece, an L-shaped armature comprising an operating arm and a pivot pin, a yoke having bearing holes thru which said pivot pin extends, means for securing said yoke to said heel-piece thereby pivotally securing said armature to said heel-piece to com- If plete the magnetic circuit including the core of said magnet, said heel-piece and said armature, a spring mounted on said heel-piece and normally tensioned against said operating arm to create a torque or twisting action between said armature bearing pin and the bearing holes in said yoke thereby preventing vibration of said armature from external causes while in normal position, the force exerted on said arm by said spring causing rotation of said armature in two planes at right angles to each other until all play between said pivot pin and bearing holes is taken up and said pivot pin is tensionally held against the bearing surfaces of said bearing holes as a result of the force applied, and said spring also frictionally retarding the operating and releasing movements of said armature without maintaining said armature locked in any operated position to make said armature somewhat slower to operate and to release.

4. In a non-locking relay, an L-shaped heelpiece, a magnet mounted on said heel-piece, an

L-shaped armature comprising an operating arm and a pivot pin, a yoke having bearing holes thru which said pivot pin extends, means for securing said yoke to said heel-piece thereby pivotally securing said armature to said heel-piece to complete the magnetic circuit including the core of said magnet, said heel-piece and said armature, a spring mounted on said heel-piece and normally tensioned against said operating arm, the spring pressure applied by said spring to said arm being in a plane parallel to the plane of the pivot pin and causes, first, the endwise movement of armature in a plane parallel to pivot pin until stopped by the yoke, and second, the twisting of said armature in two planes at right angles to each other until all play between said pivot pin and bearing holes is taken up and whereby said pivot pin is tensionally held against the bearing surfaces of said bearing holes as a result of the cumulating twisting force applied in said two planes to prevent vibration of said armature while in normal position, said spring having sufficient tension to frictionally retard the operation of said armature during its operating stroke to thereby make said armature somewhat slower to operate, the shape of said spring and the tension thereof being insufiicient to maintain or look said armature in operated position, and said spring tension being sufilcient to retard the releasing movement of said armature during its release stroke to thereby make said armature somewhat slower to release.

5. In a non-locking relay, an L-shaped heelpiece, a magnet mounted on said heel-piece, an L-shaped armature comprising an operating arm and a pivot pin, a yoke having bearing holes thru which said pivot pin extends, means for securing said yoke to said heel-piece thereby pivotally securing said armature to said heel-piece to complete the magnetic circuit including the core of said magnet, said heel-piece and said armature, a spring mounted on said heel-piece and normally tensioned against said operating arm, the spring pressure applied by said spring to said arm being in a plane parallel to the plane of the pivot pin and causes, first, the endwise movement of armature in a plane parallel to pivot pin until stopped by the yoke, and second, the twisting of said armature in two planes at right angles to each other until all play between said pivot pin and bearing holes is taken up and whereby said pivot pin is tensionally held against the bearing surfaces of said bearing holes as a result of the oumulating twisting force applied in said two planes to prevent vibration of said armature while in normal position, and said spring also frictionally retarding the operating and releasing movements of said armature without looking said armature in any operated position to make said armature somewhat slower to operate and to release.

LOUIS W. DROEL.

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