US2168785A - Light signal - Google Patents

Description

N. F. AGNEW Aug. 8, 1939 LIGHT S IGNAL Cl oyezi only when F1 andF2aPe intact. fi-

Original Filed Dec. 24, 1935 n M m w M m 0 w w P. Wu a n S o INVENTOR [lg/man FA gnew 15 13 ATTORNEY Patented Aug. 8, 1939 PATENT OFFICE LIGHT SIGNAL Norman F. Agnew, Wilkinsburg, Pa., assignor to The Union Switch & Signal Company, Swissvale, Pa., a corporation of Pennsylvania Continuation of application Serial No. 56,043, December 24, 1935. This application January 31, 1936, Serial No. 61,785

Claims.

My invention relates to apparatus for the control of railway light signals, and has for an object the provision of novel means for causing a lamp having two filaments to continue to give a 5 non-restrictive indication after one of its filaments has failed and for causing the signal to give a restrictive indication when trafiic conditions warrant a non-restrictive indication provided both filaments of the lamp which should give a non-restrictive indication have failed.

I will describe two forms of apparatus embodying my invention, and will then point ou the novel features thereof in claims.

In so far as subject matter common to the two cases is concerned, the present application is a continuation of an earlier application Serial No.

56,043, filed December 24, 1935, for Light signals,

and abandoned August 28, 1936, in favor of the present application.

grammatic view showing .one form of apparatus embodying my invention. Fig. 2 is a view similar to Fig. 1, showing a modification of certain parts of the apparatus and also embodying my invention. Fig. 3 is a view showing further details of one of the relays of Fig. 1.

Similar reference characters refer to similar parts in each of the views.

Referring to Fig. 1, the reference characters H and D designate the usual home and distant relays, respectively, of a railway signaling system, while the reference character LO designates a light-out relay. The reference character S designates a light signal ordinarily controlled exclusively by relays H and D, but at times controlled by relay L0 as will be brought out hereinafter. The signal S comprises three lamps G, Y, and R, which lamps when lighted indicate proceed, caution, and stop, respectively. In accordance with the usual practice, the beam projected from lamp G may be green, the beam projected by lamp Y may be yellow, and the beam projected from lamp R may be red.

The lamp G has a high wattage filament Fl and a low wattage filament F2 connected in multiple, and is provided with a circuit which passes from terminal B of a suitable source of current, not shown, through front contacts l and 2 of relays H and D, respectively, the winding Wl of relay LO, winding W2 of this relay, wire 5, and through the filaments Fl and F2 in multiple, to terminal C of the same current source. With both filaments Fl and F2 intact, the current flowing in windings Wl and W2 of relay L0 is sufficient to pick up and close a front contact 3 In the accompanying drawing, Fig. l is a dia-.

of this relay; As shown. in Fig. 3, relay L0 is provided with a movable armature l3 which is biased by gravity away from the magnetizable core upon which the windings Wl and W2 are carried. As long as both of these windings are deenergized this armature occupies a lowermost position in which a member l5 carried by a flexible strip 4 engages a back contact l4. When, however, the windings pass current corresponding to that drawn by the low-wattage filament F2 only of lamp G, they exert sufficient attractive force upon the armature to raise it to a mid position in which member l5 is separated from the back contact l4 and the end of flexible strip 4 is in engagement with a stop member or front contact l6. Under this condition the front contact 3 of the relay remains unclosed. Finally, when the relay windings pass energizing current corresponding to that drawn by both of the lamp filaments Fl and F2, the armature l3 flexes the strip 4 and raises itself into an uppermost position in which a movable member ll engages the front contact 3.

As long as both of the filaments of lamp G draw current (even through winding Wl only of therelay) the armature continues in this uppermost position and front contact 3 remains closed. Should, however, the winding current be reduced to that drawn by filament F2 only, then the armature drops as far as its mid position under the biasing action of spring strip 4. Only in the event that the relay windings become completely deenergized does the armature further drop to its lowermost position. Therefore, in picking up relay LO opens its back contact l4 before closing its front contact 3; in releasing it opens its front contact before closing its back contact; and under certain conditions it maintains both of these contacts opened.

It will thus be seen that in the system of Fig. 1 both of the filaments Fl and F2 of signal lamp G must be intact to cause the relay to close its front contact 3. With the front contact 3 closed, a low resistance path including wire 5 around winding W2 of relay L0 is provided, and this causes the lamp G to be lighted at normal brilliancy. The lamp Y is provided with two circuits, one of which includes front point of contact l of relay H and the back point of contact 2 of relay D, and the other of which includes front point of contact I and the back point ll of contact strip 4 of relay LO. Lamp R is pro- I vided with a circuit which includes the back point of contact I of relay E. It follows that when both relays H and D are energized and both filaments Fl and F2 are intact, front contact 3 of relay L will be closed and the lamp G will be lighted at normal brilliancy. When relay H is energized and either relay D or relay L0 is deenergized, lamp Y will be lighted; and when relay H is deenergized, lamp R will be lighted. By providing the above two circuits for lamp Y, the change from the green to the yellow indication occurs quickly, the moment that relay D releases. Also, the yellow indication is maintained until relay LO picks up and in so doing first causes the lamp Y to go out and then causes the lamp G to attain full brilliancy.

The beam projected by lamp G when filament Fl is lighted provides the usual proceed indication of the signal, while the beam projected from lamp G after filament Fl burns out enables the signal to continue to display a proceed indication, visible from a somewhat limited distance, until the lamp can later be replaced. As explainedpreviously, the winding WI of relay LO develops sufiicient ampere turns to maintain front contact 3 closed when this winding is receiving the normal amount of current as, for example, the current received when both filaments Fl and F2 of lamp G are intact. The winding Wl, however, does not develop enough ampere turns to hold front contact 3 closed when this winding is receiving current through the filament F2 only, but does, as has been stated, develop enough ampere turns to hold back contact l5 open at such time. Also, the resistance value of winding W2 is such that the inclusion of this winding in series with filament F2 prevents a potential rise across this filament, resulting from the failure of filament Fl, which might otherwise cause filament F2 to burn out prematurely.

As previously mentioned, when both relays H and D are energized and both filaments Fl and F2 are intact, front contact 8 of relay L0 is closed and the lamp Gis lighted to provide the usual proceed indication. If now filament Fl fails, the front contact 3 of relay LO will open the low resistance path around winding W2 and filament F2 of lamp G will, therefore, remain lighted at normal potential so that a proceed indication will continue to be given by lamp G. The filament F2 is so designed that its normal life is much greater than that of filament Fl and, therefore, the lamp G will ordinarily be replaced before filament F2 has failed. In case, however, that filament F2 should fail, the relay LO will no longer receive energy and will accordingly close its back contact [4. The back contact M of relay L0 is included in the auxiliary circuit for lamp Y, previously traced. It follows that if relay His energizedat a time when both filaments of lamp G are burned out, lamp Y will be lighted and the signal S will display the caution indicat on.

Referring now to Fig. 2, the light-out relay, which is here designated as L0, is provided with mercury contacts 3 and i operated by a Z-type armature Hi. In this type of structure, the angular movement of the armature 10 against the tension of its restoring spring H is substantially proportional to the applied energy. In this embodiment of the invention, the relay L0 is normally intended to receive sufficient energy to hold its armature III in its fully operated position in which it is shown by full lines. The relay is also at times intended to be energized by a reduced amount of energy. under wh ch. condition the armature l0 assumes the position represented by the dotted outline designated b. When the relay is deenergized, armature l0 assumes the position represented by the dotted outline designated a. As illustrated, a large angular 5 movement of the armature I0 is obtained when both filaments Fl and F2 are intact, resulting in the mercury contact 3 being closed. When either of the filaments Fl or F2 burns out, the reduction in energy flowing through the relay winding WI permits the spring ll torestore armature il) sufiiciently to open the mercury contact 3 thereby including winding W2 in series with the intact filament of lamp G and preventing a potential rise across its terminals. With both windings Wl and W2 included in series with one filament, the armature i9 is retained in its intermediate position so that contact 4 is not closed. In case, however, that both filaments fail, relay LO will no longer receive energy, and spring II will then restore the armature ill to its fully deenergized position. The contact 13 will accordingly close the auxiliary circuit for lamp Y, and this lamp will accordingly become lighted.

The filaments Fl and F2 of lamp G in Fig. 2 may be of equal rating, and it should be understood that when a lamp of this type is used instead of the type illustrated in Fig. 1, the winding W2 will usually comprise fewer turns and will be of a suitable resistance for preventing a potential rise across the intact filament of lamp G when the other filament fails.

It will be apparent that the lamp G of Fig. 1 may be substituted for the lamp G of Fig. 2 and 5 the resistance value and number of turns in winding W2 suitably chosen as for relay LO of Fig. 1. Similarly, in Fig. l, a lamp such as G of Fig. 2 may be substituted for lamp G and the winding W2 suitably modified to obtain the prop- -er operation of the light-out relay and desired illumination of the signal.

It will be seen from the foregoing that my invention covers alternative forms of apparatus for the control of a railway signal, whereby a nonrestrictive indication will continue to be given by the signal after one filament of the lamp used in giving such indication has failed, and that during such time I provide protection against a rise in potential across the terminals of the intact filament. Furthermore, my invention provides means for causing the signal to give a restrictive indication when both filaments of the non-restrictive lamp have failed provided conditions are such that a non-restrictive indication should be given.

Although I have herein shown and described only two forms of apparatus 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 combination, a lamp having two filaments connected in multiple, means effective to ener-'- gize both of said filaments simultaneously when both are intact, a relay having a winding and a contact, an energizing circuit for said two fila- 70 ments which includes said winding, and means under the control of said contact for preventing a rise in the potential across one filament of said lamp when the other filament burns out.

2. In combination, a source of current, a dou- 15 ble filament lamp having its two filaments con nected in multiple, a circuit for energizing said lamp from said source including a relay having two windings connected in series, and a low resistance path around one winding of said relay including a contact thereof closed when the relay is energized by current supplied to said relay through both filaments of said lamp and open when one filament of said lamp burns out, whereby the current supplied to said lamp is restricted by the resistance of one of said windings only when both filaments of said lamp are intact and is restricted by the resistance of both of said windings when one filament of said lamp has burned out.

3. In combination, a circuit including a relay having two windings connected in series and including a lamp having two multiple filaments connected in series with said two windings, a source of current for energizing said circuit, and a low resistance path around one of said windings including a normally closed front contact of said relay which becomes opened in response to a decrease of current through said relay such as results from an interruption of the flow of energy through one filament of said lamp.

4. In combination, a source of current, a lamp having two filaments, a relay having two aiding windings, an initial circuit for energizing said lamp from said source including said two filaments in multiple and both of said windings in series therewith, a normal circuit for energizing said lamp from said source including said two filaments in multiple and one of said windings in series therewith, and a shunt path around the other of said windings controlled by said relay and efiective when and only when both of said filaments are intact.

5 In combination, a lamp having two filaments connected in multiple, a source of current, a relay, means including said source and a winding of said relay for normally energizing both of said filaments, and means controlled by said relay and including a second winding thereof for preventing a rise in potential across one of said filaments when the other filament burns out.

NORMAN F. AGNEW.

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