US2162356A - Relay - Google Patents

Description

June 13, 1939. 1 PEEK JR 2,162,356

RELAY Filed Sept. 1, 1937 2 Sheets-Sheet l ATTORNEY Patented June 13, 1939 UNITED STATES PATENT OFFICE RELAY Application September 1, 1937, Serial No. 161,915

3 Claims.

This invention relates to electromagnetic switching devices and has for its object to provide more satisfactory operation of such devices, and in particular to eliminate contact chatter or the false operation of contacts in such devices.

A major cause of false contact motion is armature rebound, or return motion of the armature after reaching its normal unoperated position when it is released. In operation, the electromagnetic pull causes the armature to move into the operated position, thus bending the springs on which the contacts are mounted. In release, the springs return to their non-operated position and force the armature into its correspond- .ing position, where it strikes a stop fastened to the core structure. For fast operating circuits this return motion must be rapid, and the impact of the armature on the stop causes it to rebound. If this rebound returns the springs to the point where the contacts touch each other, false operation or chatter results.

It is the object of this invention to provide electromagnetic relays in which chatter caused by armature rebound is materially reduced. To this end a flat type relay is provided with an armature in the form of a rectangular loop, pivotally mounted near its mid-point in a U-shaped frame, which in turn is spring mounted at the rear of the relay. As a modification of this arrangement, the U-shaped frame extends along the armature and carries the contact operating studs. This type of mounting permits the armature to move either with the frame, or relative to the frame in rotation about the pivots in which it is mounted. It can, therefore, have any combination of these two types of motion. The kinetic energy possessed by the armature when it strikes the stop nut on release may therefore be dissipated in oscillatory motion in which the operating studs remain approximately stationary, thus avoiding return motion of the studs and of the contact springs on which they act.

These and other features of the invention which contribute to the greater efficiency of the relay will be readily understood from the following detailed description read with reference to the accompanying drawings in which:

Figs. 1 and 2 are respectively a top plan view and a side elevation of a relay embodying the features of the invention;

Figs. 3, 4 and 5 are schematic representations of the armature and the forces acting thereon when the relay is unoperated, fully operated and at the moment of release, respectively;

Figs. 6 and 7 are respectively a top plan view and a side elevation of a relay embodying a modification of Figs. 1 and 2;

Fig. 8 is a sectional view of the relay of Fig. 6 taken along the section line 88; and 5 Figs. 9, 10 and 11 are schematic representations of the relay of Figs. 6 and 7, corresponding to Figs. 3, 4 and 5.

Referring first to the embodiment of the invention shown in Figs. 1 and 2, the relay core 10 I0 is substantially cylindrical throughout its length, and on an intermediate portion thereof supports a relay coil II. The front portion of the core [0 is flattened to provide a pole-piece of suitable area. A back-stop for the armature 15 utilized in this construction comprises an L- shaped pin 24, having one end thereof protruding from the front end of the core II! and the other portion extending at right angles thereto and threaded to accommodate a nut 25. The core ll], back-stop nut and armature [8 are arranged to reduce the leakage flux to a minimum.

An L-shaped bracket comprising arms I6 and I1 is welded to the rear portion of core H1. The 25 depending portion ll of the bracket serves as a means for mounting the relay on a relay rack, while the portion l6 which extends the entire width of the relay constitutes a support for the spring assemblies which are located on either side of the relay and secured to the bracket l6 by means of screws I4. The spring assemblies comprise the usual contact spring combinations. The passive or stationary contact springs, such at 8 and 9, which are relatively thick, carry one or more contact elements disposed preferably at right angles to the longitudinal axes of the springs. The companion active or movable springs, such as spring 4, are relatively thin, carrying the required number of contact points and disposed in accordance with the contact elements of the stationary springs.

Mounted above the bracket portion l6 and held in place by screws l4 and clamping plate 28, are a pair of L-shaped reed springs 29. To the projecting legs of the springs 29 is clamped a U- shaped frame l2 by means of bolts 30 passing through ears 3| on the frame. The springs 29 are so biased as to normally hold the frame l2 in the position shown in Fig. 2.

The armature I8 is formed as a rectangular loop surrounding the coil II and has an elongated projection 23 at its forward end to engage the back-stop nut 25. It is mounted in the frame l2 by means of pins 26 projecting from the centers of the sides of the armature and entering holes in the frame I2. The mounting is such that the armature is free to rotate about the pins 26 and because of the projection 23 would have a tendency to move'downward at that end. However, the armature acts on the movable springs, such as spring 4 by means of studs 2'! and 39, which pass through the passive springs, such as spring 8, and the reaction of the movable springs on the studs 21 and 39 holds the projection 23 against the back-stop 25. The studs I9 and 29 hold the armature out of magnetic contact with the pole-pieces of core I9.

This mounting of the armature minimizes chatter due to the motion of the armature since the armature has two degrees of freedom, rotary movement about the pins 26, and angular motion about either end when that end is in engagement with a fixed part of the relay. When coil II is energized, the armature is drawn toward the core I9, there being a slight rotation of the armature about the pin 26 until the traction brings the armature to rest at each end against the core I9. When the coil is deenergized, both motions return the projection 23 on the armature into engagement with the back-stop nut 25. The tendency for the armature to rebound results in rotation by the end bearing the stud 29 about the point of contact between the armature and the nut 25, transmitting some of the motion to the frame I2 through pins 26 whose spring suspension helps to absorb the stored energy. Therefore, the contact springs close and open smoothly, no rebound being transmitted to them.

Figs. 3, 4 and 5 show steps in the functioning of the relay of Figs. 1 and 2. In Fig. 3, in which the armature is at rest with the relay coil deenergized, the upward pressure by the contact springs, represented by the arrow at B, is equalized by the downward forces exerted by the backstop nut 25 at A and the frame I2 at C. Any inequality of these forces is taken up by the pressure of the rear cross-piece of the armature I8 on the core I9 at D. In Fig. 4 the armature is shown at rest with the relay coil energized. In this case, the downward attractive force of the coil as indicated at A and D is acted against by the upward force of the contact springs at B, and of the spring 29 transmitted through the frame I2 and the pins 26 at the point C. When the coil is deenergized the armature moves toward the release position, the motion initially being predominantly a rotation about its rear crosspiece. When the projection 23 strikes the nut 25, the rebound tends to reverse the direction of motion at the projection 23, while the central portion of the armature tends to continue in its prior motion. The resulting motion is then predominantly a rotation about an axis close to the studs 39, the restraint imposed by the frame I2 causing this motion to assume an oscillatory characteristic. This motion may then continue until the kinetic energy of the armature is dissipated without further motion of the studs 39, thus avoiding any return motion of the springs and consequent chatter.

Referring now to Figs. 6 to 11, the relay shown in these figures has the same type of core, coil, mounting bracket, spring pile-ups and back-stop as that shown in Figs. 1 to 5. The armature difiers from that of Fig. 1 only in that no studs are mounted on the armature.

The frame I2 is mounted as above by means of bolts 39 which clamp ears 3| on the frame to the springs 29. The armature is mounted in the frame by means of pins 26 fixed near the centers of the longsides of the rectangular armature. In this case, the frame is approximately of the same length as the main body of the armature. At the free end of the frame are lateral projections 32 which are bent inward. To the under side of these projections are fastened the studs 39 by which the movable springs are operated. Small studs 33 are provided on the upper surface of the projections 32. The arrangement of these elements ismore clearly shown in Fig. 8.

When the coil is energized, the armature I8 is drawn toward the core I 0, transmitting its motion through the studs 33 and projections 32 to the studs 39 and to the movable springs 4. When the coil is deenergized, the pull on the armature ceases, and the upward thrust of the contact springs moves both the frame and the armature. Due to its greater weight, the armature acquires greater momentum, which it dissipates by rotation around the back-stop nut 25, exerting a retarding effect on the frame I2 at pins 26 and permitting the frame to come to rest smoothly. Figs. 9 to 11 illustrate this action, Fig. 9 showing the armature and frame at rest with the coil deenergized, Fig. 10 showing these parts at rest with the coil energized, and Fig. 11 showing a transient stage in the deenergization of the relay. As shown in Fig. 11, restoring movement of the frame I2 acting through the pins 26 in combination with the unbalance of the armature has moved the forward end of the armature against the back stop nut 25. Subsequent thereto the frame I2 continues its upward movement and, since the forward end of the armature can no longer move upwardly, the armature pivots at its point of engagement with the back stop nut and the rear end of the armature moves upwardly away from the rear end of the core until the studs 33 engage the underside of the armature at which time the armature and frame will assume the positions shown in Fig. 9.

What is claimed is:

1. The combination with an electromagnet having a fixed core, of a U-shaped armature bracket hinged at the rear of said core, an armature rotatably mounted midway between its front and rear to the arms of said bracket and along an axis intermediate the ends thereof and contact operating studs carried by the free ends of said bracket.

2. The combination with an electromagnet having a fixed core, of a U-shaped armature bracket hirged at the rear of said core, an armature rotatably mounted midway between its front and rear to the arms of said bracket and along an axis intermediate the ends thereof, inwardly projecting extensions on said bracket and contact operating studs carried by said extensions.

3. The combination with an electromagnet having a fixed core, of a U-shaped armature bracket spring-mounted at the rear of said core, an armature pivoted midway between its front and rear to the arms of said bracket and along an axis intermediate the ends thereof, inwardly projecting extensions on the outer extremities of said bracket and contact operating studs carried by said extensions.

ROBERT L. PEEK, JR.

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