US2336827A - Electrical relay - Google Patents

Description

Dec.- 14, 1943. H. a. WlTMER ELECTRICAL RELAY Filed June 11, 1941 INVENTOR a m m G m m H 5&

HIS ATTO RN EY Patented Dec. 14, 1943 UNITED STATES PATENT OFFICE ELECTRICAL RELAY Harold G. Witmer, Edgewood, Pa., assignor to The Union Switch & Signal Company, Swissvale, Pa., a corporation of Pennsylvania Application June 11, 1941, Serial No. 397,587

6 Claims.

My invention relates to electrical relays, and it has particular reference to tractive armature type electrical relays of the class employed as track relays in railway signal systems.

An electrical relay having a pivoted tractive armature, when employed as a track relay in a railway track circuit where it is controlled by the application of a train shunt of low resistance across its winding, is relatively quick in picking up but is comparatively slow in releasing. These characteristics are in a large measure due to the fact that the energy required to pick up the armature of the relay is considerably in excess of the energy required to hold such armature in its attracted positioned after it has picked up. Such a relay must, of course, bedesigned to create its pick-up energy level, at least, in order to insure that the relay armature will be picked up properly, and as a result once this armature has reached its attracted position, the energy level in the relay then exceeds by a considerable de gree that necessary to maintain the armature in its picked-up position. In order for a train shunt to be effective to release such a relay, the shunt must be sufficiently low in resistance to shunt away from the relay winding the increment of energy above the drop-away energy level of the relay. Such shunt, however, provides a low resistance or short-circuit path across the relay winding which maintains the flux in the relay for an appreciable interval of time, so that a correspondingly long time interval is required for a low resistance train shunt to lower the energy level of the relay below its drop-away value. Various means have been proposed heretofore to accelerate the release of tractive armature type relays when shunted, and to provide relays having quick release, slow pick-up characteristics. My invention is directed to the provision of novel and improved means for obtaining quick release characteristics in relays having a pivoted tractive armature.

Another object is to provide novel and improved forms of electrical relays particularly suitable for use as track relays in railway track circuits.

A further object is the provision of novel and improved means for obtaining quick release, slow pick-up characteristics in a relay having a pivoted tractive armature.

An additional object is the provision of a relay of the pivoted tractive armature type, having a drop-away level only slightly less than its pick-up energy level.

The above-mentioned and other important objects and characteristic features of my invention which will become readily apparent from the following description, are attained in accordance with my invention by providing means for at times shifting the center of mass of the armature means of the relay about the pivot of the armature. The arrangement is such as to vary the moment arm of the center of mass of the arma ture means, by shifting its mass center further away from the axis or pivot of the armature when it is picked up than when the armature is released, thereby to vary the torque required for operation of the armature means.

I shall describe one form of an electrical relay embodying my invention, and shall then point out the novel features thereof in claims.

In the accompanying drawing, Fig. 1 is a diagrammatic view of an electrical relay embodying my invention. Fig. 2 is a top plan view showing a portion of the apparatus represented in Fig. 1. Figs. 3 and 4 are sectional views, each taken on the line IIIIII of Fig. 2, showing in more detail certain portions of the apparatus represented in Figs. 1 and 2. In each of the several views, similar reference characters have been employed to designate corresponding parts.

Referring to the drawing, the reference characters l and la designate the track rails of a stretch of railway track divided by insulated joints 2 into a track section DE. Section D-E is provided with a track circuit comprising a suitable source of current, such as a battery 3, connected in series with a resistor 4 across the track rails at one end D of the section, and the operating winding 6 of a track relay TR connected across the track rails at the opposite end of the section. Relay TR comprises a magnetizable core 5 on which is mounted operating winding 5, and a tractive type armature l pivoted at 8. The relay, as shown, preferably includes also an auxiliary core 9 provided with an auxiliary winding [0 connected to a secondary winding H disposed on core 5, and an auxiliary armature 52 connected to armature l by a rigid member i3 preferably of non-magnetic material.

The relay further includes means operated by the armature for at times shifting the center of mass of the armature means to alter its moment arm and thus vary the torque required to cause operation of the armature means. These means comprise a movable weight which, as shown, preferably consists of an envelope or container I4 in which is disposed a relatively heavy movable mass which may, for example, comprise a relaatively dense liquid, such as mercury, partially filling the container. The container is carried by armature i and is arranged to cause the heavy mass or liquid to move toward or away from pivot 8 according as armature l is in its released or its picked-up position, respectively. As shown in Fig. 2, container is is supported by pivots l journaled in the legs of a bifurcated portion of member 53. A bifurcated or forked operating member it (see Figs. 3 and 4) secured to armature l, and fixed stops ill and it, are provided for causing container i l to tilt, in a manner to be made clear presently.

When winding t is energized, as when section DE is unoccupied, armature 'l is attracted to its upper position as shown in Fig. l, and container id is caused to engage both front stop I? and leg 59 of operating member iii, as can be seen in Fig. 3. In this position of the container, the liquid therein is at the left-hand end of the container (as viewed in Fig. 3), or the end remote from pivot 8.

If, now, the relay is deenergized, as by a low resistance shunt placed across winding 6 due to a train entering the section, armature l is released and drops to its back position. During the travel of the armatur, container id remains in engagement with leg id of member it until the container engages back stop it. Further movement oi the armature causes the container to rotate about its pivots it until the container rests on the lower leg 26 of operating member it. his tilting of the container of course causes the mercury therein to flow toward the right-hand end (as viewed in Fig. l), or to the end of the container nearest pivot 8 of armature i. Means, such as a baffle 25, may be provided in the container to restrict the flow of the mercury to a relatively low rate.

In the released position of armature l, auxiliary armature i2 is disposed adjacent auxiliary core 8, and when winding t again becomes enthe voltage induced in secondary winding H due to the growth of flux in core 5, causes a current to how in winding 3. The flux due to this current in winding t threads armature i2 and opposes the tractive effect on armature l of flux due to current in winding 6. Armature accordingly is retained in its released position til winding it becomes deenergized when the nun in core assumes substantially a constant state condition, which condition substantially corresponds to the pick-up energy level of the relay. When this happens, armature l is caused to operate to its upper position, as represented in Fig. l. Durin the upward movement of the armature, container it remains tilted against lower leg 23 of member it until the container upper stop l'i and is rotated about its pivots into engagement with upper leg l9. rotation or tilting causes the mercury to how back toward the left-hand or remote end or the container.

From the foregoing, it is readily apparent that have provided a movable weight on the armature of a relay and have provided means for shifting the resultant center of mass of the armature and weight, thereby varying the moment arm of such mass center to vary the torque to operate the armature. When the sure is released and container M is tilted to d in the drawing), the merthe ri cury therein is at the end or" the container nearest pivot 3, The resultant center or" mass of the armature and weight in this position of the armature; is, therefore, different from the resultant center of .mass of the armature and weight when the armature is picked up and container id is tilted to the left so that the mercury therein is at the end of the container remote from pivot 8. This shifting of the center of mass of the armature and weight of course varies the moment arm of the mass center about pivot t. The arrangement is such that the moment arm is greatest when the armature is picked up, hence, by shifting the mass center and varying its moment arm, the torque required to hold up the armature may be adjusted to reach a value only slightly less than the torque required to pick up the armature when its mass center is shifted in toward the armature pivot. Under such conditions, it is apparent that even a low resistance shunt will cause the relay to release quickly, due to the fact that only a very small increment of energy above the hold-up level is available in the relay, and the flux accordingly will decay quickly to reach a value below the hold-up level, whereupon the armature drops away.

The use of retaining winding it makes the armature slow to pick up, hence the combination of the retaining winding and movable weight provides a relay having the slow pick-up, quick release characteristics sought in a track relay. It is, of course, obvious that if slow pick-up characteristics are not desired, the etaining winding E9, secondary winding ii and auxiliary armature it; may be dispensed with, in which event there will be provided a relay having ordinary pick-up and relatively quick release characteristics when shunted.

In addition, it is readily apparent that if desired, the tiltable container partially filled with mercury may be utilized also as a contacting device to close and open circuit connections in accordance with the position of the mercury column. For example, the container may be provided at either or both ends with contact ele ments (not shown) disposed to be immersed in and bridged by the mercury when the container is tilted to cause the mercury to flow toward the elements. By properly pro-portioning the contact elements in such manner that they are immersed only when the container assumes its position corresponding to the picked-up or the released position of the armature, as the case may be, slow acting contact arrangements may be provided in that the bridging (or closing) of the contact elements is delayed for the interval required to operate the armature from one position to the other.

Although I have herein shown and described only one form of an electrical relay embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In a tractive armature type relay, an electromagnet, a pivoted armature biased by gravity away from said electromagnet, a movable weight carried by said armature, and means operable upon movement of said armature for controlling said weight to shift the resultant mass center of said armature and weight toward or away from said pivot according as said armature is released or picked up, respectively.

2. In a tractive armature type relay, an electromagnet, a pivoted armature biased by gravity away from said electromagnet, a container carried by said armature and partially filled with a relatively dense l quid, and means operable upon movement of said armature for causing said liquid to flow toward or away from said pivot according as said armature is released or picked up, respectively, whereby to increase the torque required to be exerted on the armature to maintain it picked up.

3. In a tractive armature type relay, an electromagnet, a pivoted armature biased by gravity away from said electromagnet, a container pivoted on said armature and partially filled with a relatively heavy liquid such as mercury, and means operable upon movement of said armature for tilting said container to cause said mercury to flow toward or away from said pivot according as said armature is released or picked up, respectively, whereby to cause the pick-up and dropaway energy levels of the relay to be substantially equal in value.

4. A track relay having an electromagnet and an armature biased by gravity away from said electromagnet and pivoted for movement toward and away from said electromagnet, an envelope pivoted intermediate its ends on said armature for rotation in a plane perpendicular to the axis of the armature pivot and containing a relatively heavy mass movable toward one end or the other of said envelope, and means engaged during movement of said armature for rotating said envelope to shift said movable mass toward or away from said armature pivot according as said armature is swung away from or toward said electromagnet.

5. In a relay, an electromagnet, a pivoted armature biased by gravity away from said elec= tromagnet, a container pivotally secured intermediate its ends to said armature and partially filled with a relatively heavy movable mass, two stops provided on said armature one for engaging one end of said container when said container is tilted in one direction about said container pivot and the other stop disposed for engaging said one container end when said container is tilted in the opposite direction about said container pivot, and two fixed stops one disposed for engaging the other end of said container during upward travel of said armature and the other of said fixed stops disposed for engaging said other container end during downward travel of said armature, said fixed stops being efiective to cause said container to tilt toward or away from said armature pivot to cause said mass to move toward or away from said armature pivot according as said armature is released or picked up, respectively.

6. A relay of the class controlled by the application of a low resistance shunt placed across a pair of shuntable conductors which connect a source to the winding of the relay, comprising the combination of, a relay winding, an armature means biased by gravity away from said winding and pivoted for swinging movement to- Ward and away from said Winding, means carried by said armature means for shifting its center of mass toward or away from the armature pivot according as said armature is swung away from or toward said winding, respectively.

HAROLD G. WITIER.

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