US2700145A - Traffic signal - Google Patents

Description

Jan. 18, 1955 R. F. STEHLIK 2,700,145

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Filed April 21, 1951 N RED [R J'I I02 A [RETURN 1 u i s INVENTOR. RUDOLPH F STEHLIK ATTORNEY United States Patent TRAFFIC SIGNAL Rudolph Frank Stehlik, Antwerp, Belgium, assignor to Automatic Electric Laboratories, Inc., Chicago, III., a corporation of Delaware Application April 21, 1951, Serial No. 222,173

9 Claims. (Cl. 340-46) This invention relates to traffic signal systems in general, and more particularly to protective systems controlling the operation of the various signals.

In such signalling systems heretofore used, upon failure of one signal lamp in a group of signal lamps, a false indication might be given to the controlled traffic during the critical period of changing the signals. This indication then would deceive one direction of traifie while indicating properly to the cross directional traflic. Vehicle operators in the one direction relying upon the usual dependability of traiiic signals are then subjected to the possibility of collision with the cross directional trafiic. The best interests of safety and municipal tratli c regulation require that such dangers be reduced to a Tllllllmum.

Prior systems have been utilized including flashing signals, sound warnings or complete disabling of the entire control system. These systems do not solve the problem, but merely warn against it, or indicate a malfunctioning in some manner. The operator is apt to become confused by this type of warning and the usual result is a control system as unsafe as or more unsafe than continued operation of the system with the faulty lamp might be.

The present invention overcomes the disadvantages mentioned and provides safe control of traffic under circumstances of failure.

The object of my invention therefore is to provide for vehicle control at a given trafiic intersection whereby a failure of one signal lamp in a signal unit will disable the other lamp in the same unit to prevent a false indication during the critical signal change period for that signal unit.

This invention is applied to a system which provides only two lamps in the traffic signal system. Both of the lamps are simultaneously illuminated to indicate the can-- tion period. In case the red lamp becomes defective. means are operative to partially disable the signal system by giving a dark signal during the caution period. Thus the green lamp, under such circumstances, does not lllllmlnate during the caution period in order to avo1d a false indication, and yet it operates as usual during the go period.

One feature of my invention whereby the desired re sults are obtained is a novel relay combination for con trolling the signal circuits upon failure of one circuit therein.

A further feature is the novel interlocking arrangement used in the relay assembly to achieve the desired result.

Referring now to the illustration of my invention, which in the preferred embodiment involves a Z-lamp signal unit, although the invention may be adapted easily to a 3-larnp system; i

Figure 1 shows the schematic circuit arrangement for a given signal unit showing two separate relays.

Figure 2 is a plan view of a modified form of relay structure showing an interlocking arrangement for the two relays of Fig. 1.

Figure 3 is a front view of Figure 2 showing the armature interlocking arrangement.

Figure 4 is a view along line AA of Figure 2 showing the spring arrangement.

Figure 5 is a side view of Figure 2 showing the spring arrangement and the structure suitably enclosed.

Figure 6 is a circuit arrangement showing the circuit of Fig. 1 adapted for use with the modified relay of Fig. 2.

In general the system operates in the following manner. In normal operating conditions at a usual traific intersection of two streets four sets of signal lamps are visible, one to each of the four directions of traffic. However, operation is similar at any number of intersecting streets or any number of signal units. The controller, not shown, associated with the intersection controls the sequence and timing of the signals. This controller is any well known means for controlling trafiic signal systems of the Z-lamp type as herein described. In a twolight system, only red and green signals are used, and will indicate those colors to the intersecting traflic. The period of change from green to red and red to green requires a caution signal to slow the moving traffic and alert the stationary trafiic. In such a system illumination of the red and green lamps simultaneously in all directions is the usual caution signal. However, such a signal to the moving traffic only may also be used. It is then apparent that failure of the red lamp would be critical, for then the simultaneous signal of both lamps would not appear in the defective unit. In this situation a relay operates to remove the green lamp from the circuit during the warning or caution period and a darkened signal appears to the moving traffic. This will indicate malfunctioning of the signal and slow the moving traffic which, upon observing the cross-directional traffic alert signal and subsequently the go signal to that traflic, will stop. At the next change period the darkened signal will remain so during the change or caution period and at the proper time, the green lamp will indicate as though the signal were in proper working order.

The green lamp in the above description is removed from the circuit in the defective signal unit in a manner hereinafter described in detail with reference to the figures illustrating the preferred embodiment of my invention.

Figure 1 shows schematically the structure desired to perform in the required manner. Relay A is connected in series with the red lamp R so that its operation will be dependent upon a complete circuit through that lamp. Armature A2 is placed to operate responsive to the encr gization and deenergization of coil A and when operated completes a circuit from battery at the controller, over lead 101, through contact A, armature A2, green lamp G, to ground at the controller. Thus the green and red lamps may operate simultaneously with battery potential placed upon the incoming leads 101 and 102 by the controller.

Another coil B, is connected in parallel with the red lamp and an armature B2 is provided therefor which will open a circuit to the green lamp G when this coil is energized.

The sequence of operation in detail is as follows. Bat tery potential is received over lead 102 from the controller (not shown), through relay A, through lamp R, to common ground lead 100. A energizes, closing A2 and A1, and lamp R illuminates. Relay B also energizes at the same time since it is directly across leads 102 and 100, but is slow to operate armature B2, hence A2 operates first. After a predetermined interval battery potential is placed on lead 101, through Al, and A2 to lamp G, to common ground lead 100. Lamp G now illuminates. Simultaneous lighting of both lamps gives the caution signal. Battery potential is then removed from 102 after a timed interval, relay A and B dcenergize and lamp R darkens. Armature A2 is slower to release than 132. and when B2 falls back, lamp G remains illuminated over a path from battery at the controller, lead 101, contact B1, armature B2 through lamp G to ground at 100. The signal now indicates go to the traffic it controls.

This period ends at a predetermined interval and the change back to the stop condition commences by battery potential being received over lead 102 again, from the controller through the winding of series relay A through the filament of lamp R to ground over lead 100. Both lamps are now illuminated, as a caution" signal to slow the traflic. Relays A and B are energized, A again operating first. Battery is removed from 101 by the controller and the lamp G darkens.

Assuming now that the lamp R is defective the following is the sequence of operation.

Battery is applied upon lead 102 by the controller, but since lamp R is open, relay A does not energize, but relay B does energize since it is directly across the pair of leads 102 and common ground 100. Armature B2 operates opening the circuit 101 to ground through lamp G at contact B1. When battery is placed on 101 simultaneously with battery on 102 by the next operation of the controller, lamp G will not illuminate due to the open circuit at B1. When battery is removed from 102 only, relay B deenergizes, B2 falls back and a circuit is now completed from battery on 101 through contact B1, armature B2 through lamp G to ground on 100. Lamp G now illuminates and functions as at normal. When battery is again placed on 102 during the normal caution period, relay B reoperates and opens the circuit to lamp G. Thus lamp G never illuminates during the caution period if lamp R is defective.

Referring now to Figures 2, 3, 4 and 5 the detail structure of the preferred interlocking relay combination used to control the above described circuit is as follows, although any suitable interlocking structure can be used.

A base 3 is suitably insulated by insulation 2 and is suitably enclosed by a casing 1 which has mounted thereon suitable terminal blocks for electrical connections. mounted by means of heel pieces and 16 respectively to base member 3 and suitably insulated therefrom. Armatures 13 and 14 are pivotally mounted upon heel pieces 15 and 16 respectively in opposing directions. Armatures 14 and 13 have attached thereto lever arms and 22, respectively. Lever arm 20 has mounted therein, at the lower extreme end, a pin 21, which engages a suitable groove or notch existing in lever arm 22. Individual to armature 13 is armature arm 17 which extends into an operative position with respect to springs 9 and 6 suitably mounted upon base 3 and insulated therefrom, by suitable material 4 and 5. In the present embodiment springs 9 and 6 are shown as twin contact springs with the contacts 7 and 8 normally closed. Spring 9 has a suitable opening therein to allow extension of a buffer 12 fastened to spring 6 there through into an operative position with respect to the armature arm 17.

The normal operation of the relay structure in association with the circuit described above is as follows. Battery received by the relay from the controller will energize series coil 18 and parallel coil 19 simultaneously but 18 is so arranged to operate armature 14 before 19 operates armature 13. When series coil 18 is energized, armature 14 is attracted into engagement with armature adjusting stop 15 which may be any suitable adjusting device. Lever arm 20 moves in association with armature 14 causing pin 21 to pivot about bearing 26. Since pin 21 is in engagement with notch 25, lever arm 22 will then pivot about bearing 23 thus raising armature 13 away from parallel coil 19. The simultaneous energization of coil 19 as described will have no effect upon armature 13, since it is physically impossible for coil 19 to overcome the influence of coil 18 on armature 14. Since armature arm 17 is associated only with armature 13, the operation of armature 14 will not affect the movement thereof or of bufier arm 12 and springs 6 and 9, and will have no effect upon the circuit associated therewith. Therefore energization of parallel coil 19 while coil 18 is also energized, will not affect the movement of armature arm 17 and buffer 12 for the reason mentioned above. Deenergization of the series coil 18 while parallel coil 19 remains energized, will result in the release of armature 14. This permits armature 13 to return within the efiective field of coil 19, and it may now be attracted thereto. The operation of the armature 13 in the above described manner will result in the engagement of armature arm 17 and buffer arm 12, thereby opening twin contacts 7 and 8. The above described operation of armature 13 will occur only when the safety feature of this relay is required.

Referring now to Figure 6, the operation above described of the relay combined in association with the circuit shown in Figure 1 is as follows. Battery is received from the controller (not shown), over lead 102 through lamp R to terminal block 203 through series relay 18 to another terminal 200 to common ground lead 100. Since relay 18 is arranged to operate before relay 19, lamp R illuminates and series relay 18 energizes. Parallel relay 19 is also energized at this time Series coil 18 and parallel coil 19 are suitably tit) over a path from battery at 102, terminal 202, parallel coil 19, terminal 200 andaground at 100, but does not cause operation of armature 13 because of the prior energization of relay 18 and the interlock structure. Battery is now received simultaneously over leads 102 and 101 during the caution period of the signal. These paths can be traced as follows: lead 101 through lamp G to terminal 201 to spring 6, contacts 7 and 8, spring 9 to terminal 200 to common ground lead 100, and lead 102 over the prior path described above for lamp R alone. Lamps G and R are both illuminated during this period. Battery is now removed from lead 102 by the controller which opens the circuit to lamp R and coils 18 and 19. Lamp 6 remains operated over the previously described path.

Assuming now lamp R is defective, the safety feature operation of the relay is as follows. Battery is placed on lead 102 by the controller to indicate the caution period, but since lamp R is open the path may be traced to the terminal block 202, through coil 19 to terminal 200 to common ground lead 100. Coil 19 is now energized while coil 18 is deenergized due to the open circuit. Armature 13 will operate in this condition due to release armature 14, by relay 18 and opens contacts 7 and 8 of springs 6 and 9, respectively. This opens the circuit to G and lamp G goes out thus avoiding a false signal to the viewer of the signal, both lamps are now darkened. Battery is now removed from lead 101, yet remaining on 102. This is the normal stop period but since R is defective the signal remains darkened as during the caution period described above. Battery is now replaced on lead 101 by the controller but since relay 19 remains energized, and armature 13 is operated, contacts 7 and 8 remain open as before described and G does not illuminate. The controller now removes battery from lead 102, relay 19 deenergizes, 13 falls back and makes springs 7 and 8, and since battery remains on lead 101, the lamp G will now illuminate over its former path. The outward appearance of the signal with lamp G illuminated is the same as it would be to the observer at this time in the cycle as it would he were lamp R not defective.

What I claim and desire to be protected by Letters Patent is:

1. In a traffic signal system, a signal unit comprising a single red lamp and a single green lamp, a first circuit for said red lamp, a second circuit for said green lamp, controller means including a source of current and said two circuits for simultaneously operating said two lamps to indicate a caution period and for sequentially and periodically controlling said red lamp and said green lamp over their respective circuits to indicate stop and start periods respectively, the combination of a safety relay individual to said unit, relay means controlled by a defective red lamp for enabling said relay for operation, circuit means effective by said enabling means for operating said relay in response to an attempt to operate a defective red lamp, and means operated in response to the operation of said relay disabling said green lamp by opening said green lamp circuit to prevent its illumination during the controlled caution period when said red and green lamps would normally illuminate simultaneously.

2. In a traffic signal system, a signal unit comprising a single red lamp and a single green lamp, a circuit for said red lamp, a circuit for said green lamp, controller means including a source of current and said two circuits for simultaneously operating said two lamps to indicate a caution period and for sequentially and periodically controlling said red lamp and said green lamp over their respective circuits to indicate stop and start periods respectively, a safety relay individual to said signal unit, means for operating said relay in response to a failure of said red lamp during said caution period, and means operated in response to the operation of said relay to extinguish said green lamp by opening said green lamp circuit during said caution period to provide a darkened signal unit during said caution period to warn said traific of the defective condition of said signal.

3. In a traffic signal system, a signal unit comprising a single red lamp and a single green lamp, a circuit for said red lamp, a circuit for said green lamp, controller means including a source of current and said two circuits for simultaneously operating said two lamps to indicate a caution period and for sequentially and periodically controlling said red lamp and said green lamp over their respective circuits to indicate stop and start periods respectively, the combination therewith of a safety relay individual to said signal unit, means for operating said relay in connection with the illumination of said red lamp over said red lamp circuit during said stop and caution periods, interlocking means in said relay operated in response to the operation of said relay to prevent further operation of said relay during said stop and caution periods, means in said relay for disabling said interlocking means in case said red lamp fails during said stop and caution periods, and means operated in response to the disabling of said interlocking means to disable said green lamp circuit to prevent operation of said green lamp during the normal caution period.

4. In a traflic signal system, a signal unit comprising a single red lamp and a single green lamp, a first circuit for said red lamp, a second circuit for said green lamp, controller means including a source of current and said two circuits for simultaneously operating said two lamps to indicate a caution period and for sequentially and periodically controlling said red lamp and said green lamp over their respective circuits to indicate stop and start periods respectively, the combination therewith of a safety relay individual to said signal unit, interlocking means in said relay for controlling the sequence of operation of said green lamp over said green lamp circuit, relay means operated rendering said interlocking means inefiective in case said red lamp is defective during said stop and caution periods, and means operated in response to the operation of said relay means disabling said green lamp circuit to prevent operation of said green lamp during said caution period.

5. In a traffic signal system, a signal unit comprising a single red lamp and a single green lamp, a first circuit for said red lamp, a second circuit for said green lamp, controller means including a source of current and said two circuits for simultaneously operating said two lamps to indicate a caution period and for sequentially and periodically controlling said red lamp and said green lamp over their respective circuits to indicate stop and start period respectively, the combination therewith of two relays, means for operatively interconnecting said two relays to prevent complete operation of one when the other is operated, means for energizing both of said relays in connection with said red lamp and for operating only said other relay, means for releasing the other and completely operating the one of said relays upon failure of said red lamp, said interconnecting means being rendered inetfective upon said release of said other relay to permit complete operation of the one of said two relays, and means operated in response to the complete operation of the one of said two relays for preventing the operation of said green lamp while said one relay remains operated to prevent a false signal showing during the caution period.

6. In a traffic signal system, a signal unit comprising a single red lamp and a single green lamp, a first circuit for said red lamp, a second circuit for said green lamp, controller means including a source of current and said two circuits for simultaneously operating said two lamps to indicate a caution period and for sequentially and periodically controlling said red lamp and said green lamp over their respective circuits to indicate stop and start periods respectively, the combination of a safety relay included in said red lamp circuit, said red lamp circuit rendering said relay inoperative in case said red lamp becomes defective during its caution and stop periods, means for opening said second circuit to prevent illumination of said green lamp during the caution period, and means for controlling said last mentioned means only in case said relay is rendered inoperative.

7. In a tralfic signal system, a signal unit comprising a single red lamp and a single green lamp, a red lamp circuit for said red lamp, a green lamp circuit for said green lamp, controller means including a source of current and said two circuits for simultaneously operating said two lamps to indicate a caution period and for sequentially and periodically controlling said red lamp and said green lamp over their respective circuits to indicate stop and start periods respectively, the combination of a safety relay individual to said unit, means for operating said relay over said red lamp circuit in connection with the controlled illumination of said red lamp during said stop and caution periods, means operated in response to the operation of said relay for preparing said green lamp circuit for the controlled illumination of said green lamp, means including said red lamp circuit for rendering said relay inoperative in case said red lamp becomes defective, and means operative during sai caution period in case said relay is rendered inoperative by a defective red lamp for disabling said green lamp circuit to prevent illumination of said green lamp during the caution period.

8. In a tratfic signal system, a signal unit comprising a single red lamp and a single green lamp, a circuit for said red lamp, a circuit for said green lamp, controller terms including a source of current and said two circuits for simultaneously operating said two lamps to indicate a caution period and for sequentially and periodically controlling said red lamp and said green lamp over their respective circuits to indicate stop and start periods respectively, the combination therewith of two interlocking relays, one of said relay series connected in said red lamp circuit to said red lamp, the other said relay connected to said red lamp circuit and connected in shunt of said red lamp, means for operating said shunt relay in case said red lamp is defective during said caution and stop periods, means controlled by said shunt relay for disabling said green lamp circuit upon failure of said red lamp during said caution period, and said green lamp being operated over said green lamp circuit only during said start period.

9. In a trafiic system having stop, go, and caution periods, a first relay, a second relay, a stop circuit, a go circuit, means for completing said stop circuit during said stop period, for completing said go circuit during said go period, and for completing both said circuits during said caution period, means for operating said first relay over said stop circuit during said stop and caution periods, means for energizing said second relay over one portion of said stop circuit during said stop and caution periods, mechanical means operated in response to the operation of said first relay for physically preventing said second relay from operating while said first relay is operated and said second relay is energized, said mechanical means being inetfective in case said first relay releases, means for releasing said first relay during said caution period in case another portion of said stop circuit becomes defective, means for completely operating said second relay over said one portion of said stop circuit in case said first relay is released during said caution period, and circuit means operated by the complete operation of said second relay for disabling said go circuit only during said caution period.

References Cited in the file of this patent UNITED STATES PATENTS 1,900,723 Miller Mar. 7, 1933 2,065,815 Levy Dec. 29, 1936 2,100,313 FitzGerald Nov. 30, 1937 2,166,721 Jetfers July 18, 1939 2,407,355 Wells Sept. 10, 1946 2,491,891 Hopkinson, Ir Dec. 20, 1949 2,505,849 Bevis et al. May 2, 1950

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