US2575812A - Electric relay - Google Patents

Description

Nov. 20, 1951 HUFNAGEL 2,575,312

ELECTRIC RELAY Filed Aug. 19, 1949 "if? 5 q :2 I9 21 lnsaladalz. 50a 50 52 I0 20 2 Fyi.

IN VEN TOR.

H15 ATTORAZ'Y Patented Nov. 20, 1951 UNITED STATES PATENT OFFICE ELECTRIC RELAY Andrew Hufnagei, Penn Township, llegheny County, Pa., assigncr to Westinghouse Air Brake Company, a corporation of Pennsylvania Application August 19, 1949, Serial No. 111,209

4 Claims. 1

My invention relates to electric relays, and particularly to relays of a type commonly employed in certain railway signaling systems and termed code detecting relays.

it is common in certainr'ailwa'y signaling sys tems to use electric circuits which are periodically interrupted or coded. This coding action may take place at one of several different freduencies, depending upon the intelligence to be transmittedoiier the circuits. Such circuits commonly supply current to a code following relay which picks up its contacts when each current impulse received and drops its contacts between the current impulses. It is desirable for safety reasons to check the operation of such code following relays to ascertain that the relay is following code and that its front and back contacts are opening and closing properly. Several such code detecting arrangements have been proposed in the past. See, for example, Letters Patent or the United States No. 2,320,748, issued to George R. Pfla'sterer on June 1 1943, entitled Railway Signaling Apparatus.

It is an object of my invention to provide an improved and simplied code detecting relay of the type described. 7

' I carry out the foregoing and other objects of my invention by providing a closed magnetic circuit and a magnetic circuit with air gaps having a common element with the closed circuit for my code detecting relay. The closed magnetic circuit comprises a closed loop of magnetic material having two electric windings so connected respectively to the front and back contacts of the code following relay that they are effective when energized to create opposing magnetic fluxes in the loop. A shading coil is placed on a portion of the loop to delay the building up and decaying of magnetic flux through that loop portion. The second magnetic circuit provided forms a magnetic shunt around the shading coil porti'or i of "the loop. This branch magnetic circ'uit includes an armature and at least one pole structure toward which the armature is at times attracted. The branch circuit includes air gaps between its ends and the closed loop so that its reluctance is much greater than that of theloop during steady magnetic conditions in the loop. The pole structure includes two magnetically parallel portions and a second shading coil on one of said portions. The second shading coil is efiective to retain the armature in its attracted in its attracted position when and only when the windings are alternately energized at a frequency within a predetermined range. In other words, the armature is attracted only when the code following relay is following code and its contacts are functioning properly.

I shall describe two forms of electric relays embodying my invention, and shall then point out the novel features thereof in claims.

In the accompanying drawings, Fig. 1 is a schematic view of an electric relay embodying my invention and an energizing circuit for that relay. Fig. 2 is a side elevational view of the relay shown schematically in Fig. 1. Fig. 3 is a schematic view of another form of relay embodying my invention.

FIG. 1

There is shown in this figure a code transmitter relay CT having a contact which controls the energizing circuit of a code following relay Relay CF is in turn provided with a contact which controls energizing circuits for a code detecting relay embodying my invention and generally indicated by the reference numeral I.

The code detecting relay l is provided with a magnetic circuit which includes a loop 2, which in the example shown takes the form of a hollow rectangle. A pair of electric windings 3 and 4 is provided on opposite sides of the loop 2. Wind ing 3 may be energized over an obvious circuit controlled by the back contact of relay and winding 4 may be energized by another obvious circuit controlled by the front contact of relay CF. The windings 3 and 4 are shunted by are suppressing resistances 5 and 6, respectively.

One side 2a of the loop 2 carries a heavy shading coil or ring I, which is effective to delay the building up or decay of magnetic flux through the part of the magnetic circuit which it en'- circles.

A branch magnetic circuit is provided, which is magnetically in parallel with the loop portion 2a encircled by the shading coil 1. This branch magnetic circuit includes two pole structures 8 and 9 and an armature Ill. The pole structures 8 and 9 are separated from the opposite ends of the loop portion 20. by air gaps II and 12. The reluctance of the branch magnetic circuit, including the air gaps H and I2, is so related to the reluctance of the loop portion 20. that very little flux flows through the branch magnetic circuit during steady magnetic conditions in the loop 2. However, during transient magnetic .con ditions in the loop 2, such as occur during alter- -.nate energization of the windings 3 and '4 when Each of the pole structures 8 and 9 is provided with two magnetically parallel portions, such as M and 8b, and the corresponding portions 9a and 9b. The portions 8a and 9a of the pole structures 8 and 9 are provided with shading rings or coils I4, which are efiective to delay the building up and decay of magnetic flux in their respective pole portion.

The shading coils I4 are effective to maintain the magnetic flux during the time when both coils 3 and 4'are deenergized, due to the passage of the contacts of code following relay CF between its front and back contacts, and are thuseifective to retain the armature I in its attracted position at such times.

Operation The operation of the relay I when the relay CF is following code is believed to be suificiently described above. We will now proceed to consider the operation of relay I when the relay CF is not following code, and then its operation during various types of malfunctioning of the contacts of relay CF.

First let it be assumed that relay CF is not following code, but is continuously deenergized or continuously energized. In either event, the front or the back contact of relay CF is continuously closed, and one of the windings 3 and 4 is continuously energized. This produces a steady magnetic condition in the loop 2. After this condition has persisted for a short time, the flux delaying effect of the shading coil 7 is overcome.

and the portion 2a of the loop 2 then effectively shunts the magnetic flux away from the branch magnetic circuit including the pole structures 8 and 9 and armature I0. Armature Ill is then no longer attracted to the pole pieces 8 and 9 and therefore drops to its deenergized position.

Let it now be considered that relay CF is following code, but that one of the stationary contacts sticks against the movable contacts so-that onelof the windings 3 or 4 is continuously energized while the other is intermittently energized. When both windings 3 and 4 are energized, they tend to buck each other in the loop 2 and in the branch magnetic circuit and are hence then effective to prevent attraction of the armature Ill. During the intervening period, the one winding which is energized continuously is eilective to send flux through the loop 2. Although this flux may be intermittently bucked down by the other winding, the direction of flow of flux through the loop is never reverse under these conditions, and hence the continuously energized winding is gradually effective to build up a flow of fiux through the loop portion 2a. This flux is shunted through that loop portion, away from the branch magnetic circuit including armature I0, and is hence not eifective to attract the armature.

- Let us now consider the conditions which exist when the two front and back contacts of relay CF are permanently bridged, so that both windings 3 and 4 are continuously energized. These windings then buck each other in sending flux through the loop 2 and through the branch magnetic circuit including armature I0. Hence the flow of magnetic flux is reduced to a minimum and is not sufilcient to attract the armature I0.

From the foregoing, it may be seen that the relay I picks up the armature I0 when and only when the code following relay CF is following code and its contacts are operating properly.

FIG. 2

This figure represents a side elevational view of the-relay I, which was shown diagrammatically in Fig. 1. Most of the parts illustrated in Fig. 2 are also illustrated in Fig. 1, and have been given the same reference characters.

Those parts will not be further described.

Referring to Fig. 2, it may be seen that the magnetic loop 2 is mounted on an insulated base plate I5, and that the pole structures 8 and 9 are also mounted on the base plate I5 so as to project downwardly through it. The armature I0 is hinged on nonmagnetic extensions of the portions 8a and 9a of the pole structures. The base plate I5 carries three terminal posts I6, I! and I8 which extend upwardly from its upper surface and project downwardly through the base plate. Terminal post I6 is connected by means of a detail connection IS with a movable contact 2:! carried by the armature I0. Terminal post I! carries at its lower end a front contact 2I which cooperates with the movable contact 28. Terminal I8 carries at its lower end a back contact 22 which cooperates with the movable contact 20.

FIG3

There is shown in this figures. relay 23 which corresponds functionally to the relay I of Figs. 1 and 2, but is somewhat different in form. Relay 23 includes a magnetic loop circuit 24 carrying two windings 25 and 26 which correspond generally to the windings 3 and 4 of Fig. 1. The energizing circuits for windings 25 and 26 are not shown, and may be identical with those shown for the windings 3 and 4 of Fig. 1.

One side 24a of the magnetic :loop 24 carries a shading coil or ring 21, which corresponds to the shading coil I of Fig.

The magnetic loop 24 is provided with a downward extension 24?) connected to the portion 24a at its upper end. The lower end of extension 2 b is separated from a pole structure 28 .by an air gap 29. An armature 30 is pivotally mounted at one end near the lower end of the portion 24a of the magnetic loop 24, as on hinge 39a made of brass. The free end .of armature 3o extends adjacent the pole structure 28. The pole structure 23 corresponds to the pole structures 8 and 9 of Fig. 1, and is provided with magnetically parallel portions 28a and 28b. A shading ring 3|, corresponding to the shading ring is of Fig. 1, is carried on the portion 28a of the pole structure 28. A nonmagnetic core pin 32 is provided to prevent direct engagement of armature 3G with the pole structure 28.

- The extension 2422, pole structure 28, and armature 35 form a branch magnetic circuit which corresponds to the branch mag'netic circuit of Fig. 1, including pole structures 8 and 9 and armature I0. 1

The operation of the relay- 23 of Fig. 3 is analogous in every way to that of the relay I of Figs. 1 and 2, and it is believed unnecessary to describe it in detail. I a l Although I have herein shown and described only two forms of electric relays 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. A code detecting relay comprising a magnetic circuit including a close-d loop of magnetic material, two electric windings on said loop, means for alternately energizing said windings to create opposing magnetic fluxes in said loop, a shading coil on said loop, and a branch magnetic circuit forming a magnetic shunt around said shading coil during transient magnetic conditions in said loop; said branch circuit including an armature and at least one pole structure toward which said armature is at times attracted; said branch circuit having an air gap between each pole structure and the closed loop so that its reluctance is greater than that of the loop during steady magnetic conditions in the loop; said shading coil and air gaps cooperating to retain said armature in its attracted position when and only when said windings are alternately energized at a frequency within a predetermined range.

2. A code detecting relay comprising a magnetic circuit including a closed loop of magnetic material, two electric windings on said loop, means for alternately energizing said windings to create opposing magnetic fluxes in said loop, a shading coil on said loop, and a branch magnetic circuit forming a magnetic shunt around said shading coil during transient magnetic conditions in said loop; said branch circuit including an armature and at least one pole structure toward which said armature is at times attracted; said branch circuit having an air gap between each pole structure and the closed loop so that its reluctance is greater than that of the loop during steady magnetic conditions in the loop; said pole structure comprising magnetically parallel portions and a second shading coil on one of said portions, said second shading coil being effective to retain said armature in its attracted position during transient magnetic conditions in said branch magnetic circuit, said shading coils and said air gaps cooperating to retain said armature in its attracted position when and only when said windings are alternately energized at a frequency Within a predetermined range.

3. A code detectin relay comprising a ma netic circuit including a hollow rectangular loop of magnetic material, two electric windings on opposite sides of said loop, means for alternately energizing said windings to create opposing magnetic fluxes in said loop, a shading coil on a third side of said loop, and a branch magnetic circuit forming a magnetic shunt around said shadin coil during transient magnetic conditions in said loop, said branch circuit including an armature and two pole structures extending from the ends of said third side toward said armature and toward which said armature is at times attracted; said branch circuit having air gaps between said pole structures and the ends of said third side so that its reluctance is greater than that of the loop during steady magnetic conditions in the loop; each said pole structure comprising magnetically parallel portions and a second shading coil on one of said portions, said second shading coil being effective to retain said armature in its attracted position during transient magnetic conditions in said branch magnetic circuit, said first shading coil and air gaps cooperating to retain said armature in its attracted position when and only when said windings are alternately energized at a frequency within a predetermined range.

4. A code detecting relay comprising a magnetic circuit including a hollow rectangular loop of magnetic material, two electric windings on said loop, means for alternately energizing said windings to create opposing magnetic fluxes in said loop, a shading coil on one side of said loop, and a branch magnetic circuit forming a magnetic shunt around said shading coil during transient magnetic conditions in said loop; said branch circuit including an armature pivotally mounted adjacent one end of said one side and a pole structure extending from the other end of said one side toward said armature and toward which said armature is at times attracted; said branch circuit having an air gap between each pole structure and the closed loop so that its reluctance is greater than that of the loop during steady magnetic conditions in the loop; said pole structure comprising magnetically parallel portions and a second shading coil on one of said portions, said second shading coil being effective to retain said armature in its. attracted position during transient magnetic conditions in said branch magnetic circuit, said first shadin coil and air gaps cooperating to retain said armature in its attracted position when and only when said windings are alternately energized at a frequency within a predetermined range.

ANDREW HUFNAGEL.

REFERENCES CITED The following references are of record in the

Images