US2124392A - Traffic-signaling system - Google Patents

Description

July 19; 1938. H. H. BELL 2,124,392

TRAFFIC SIGNALING SYSTEM Filed July 19, 1933 Fig. l. I A

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Patented Julypl9, 1938 L PATENT OFFlCE 2,124,292 TRAFFIC-SIGNALING SYSTEM Howard H. Bell, Schenectady, N. Y., assignor to General Electric Company, a corporation of New York Application July 19, 1933, Serial No. 681,125

Claims.

My present invention relates to traffic signaling systems. and more particularly tosystems in which continuously-operated intersection-signals and normally-inactive traffic-actuated sig-' 5'; nals are used to control trafiic along a main highway. i

The principal object of my-invention is to provide an improved system of control wherein the traffic-actuated signals normally indicate the right of way to the main highway trafiic and upon'approach of vehicles on the cross streets will give the right of way to such vehicles only during a pote'ntialstop period on-themain high-' way. a 15,: Another object of my invention is to provide a trafiic-actuated intersection-signal which will operate to givethe right of way to the cross. street only during potential stop periods on-the main highway in a system in which successive continuously-operated intersection-signals are timed in progression. I I

For a consideration of what I believe to be novel and my' invention, attention is directed to the following specification, the accompanying 25. drawing and the appended claims.

Fig. '1 of the drawing illustrates diagrammati cally a system of traflic control embodying my invention; Fig. 2 is a diagrammatic illustration of the arrangement of the continuously-operated 30; and traffic-actuated signals along a main highway, and Fig. 3 is a timing'chart illustrating the arrangement'of the green periods. in a progressively timed system and the relative arrangement of the synchronizing cams for carrying out my 35: invention.

A set of continuously-operated intersectionsignals is indicated at A and a set .of normally inactive traffic-actuated signals is indicated at B. Each of the sets of signals comprises two series 40 of three lamps each, one series for the main high-.

way and one for the cross street. The lamps are marked G, A? and R, respectively indicat-- ing-green, amberand red, which are the signalsused to indicate'go, caution and stop. v The num-- 45- ber of signal lamps in a group mayvary in accordance with city, regulations and the require.- ments of each intersection. The three-lamp arrangementis, however, generally used;

.The'group of lights indicated as A are continu- I ously operated in a predetermined sequence by a through conductors Ill and l I connected to terminals on the controller 3; and a disk armature l2 which drives the controller 3 through a clutch l3 and ashaft IA. The clutch i3 is indicated as a normally closed disk clutch which may 5 be opened by energizing a clutch magnet I5. The controller 3 may be any suitable controller for operating the signals in a predetermined sequence. .Iprefer to use, however, a controller such as is described in U. S. Patent No. 2,050,039, 10

issued August 4, 1936, to Campbell and Byer and assigned to the same assignee as the present application. These controllers, briefly, comprise a multiple switch operable to energize in a predetermined sequence, the signal circuits for a group l5; of trailic signals, and a timer for controlling the operation of' the multiple switch and thereby controlling the relative lengths of the time periods for each signal within a sequence or cycle. The speed of the driving motor 4, which iscon- 20 nectedthroughaconnecting'means, viz. the clutch I3 in the present arrangement, determines the length of a total cycle, and thereby the actual length of the signal periods within the cycle or sequence. Q 7

The continuously-operated signals are placedunder the control of a master controller l6; This controller receives energy from lines 5 and. 6 through conductors I! and I8 and is driven by a motor I!) through a shaft 20. The motor come prises a stator 2| which is continuously energized through conductors-22 and. 23, and" a disk armature 24 which is connected to the shaft 20. For the purpose of controllingthe operation of the signal controllers, a cam 25 provided with a projection 26 is mounted on shaft 20 and is arranged-to rotate therewith at the rate of one rev-- olution for each cycle of operation of the signals l The cam 25 is arranged to separate normallyengaging contacts 21 and Y28 once during each revolution. This is accomplished by mounting the contact 28 on a'contact spring 29, the end of which rides on the cam surface 25. The separation of the contacts takes place when the end of the spring 29 rides over the projection 26. Contact 21 is connected toline conductor 6- through conductor 30 and contact 28 is connected to a synchronizing conductor 32 through a con-e ductor 3|. Although I have shown a separate master controller it is to be understoodthat this controller may be one of the intersection .controllers equipped with a cam 25 and the contacts 21 and 28 connected as above described.

The shaft 14 of the controller 3 is provided with-a cam 33 corresponding to the cam 25. This cam is, arranged to rotate with the shaft at the rate of one revolution for every cycle of operation of the signals A. The cam 33 is provided with an indent 34 and is arranged to close normally- open contacts 35 and 36 once during each revolution. The contact 36 is mounted on a contact spring 31, the end of which rides on the cam surface 36 and causes an engagement, or closing, of the contacts 35 and 36 when it rides into the indent 34. The contact 35 is connected to the synchronizing conductor 32 by conductor 38 and the contact 36 is connected in series with clutch coil l5 and by conductor 39 to. the line conductor 5.

In operation the contacts 21 and 28 of the master controller normally engage each other and therefore connect the synchronizing conductor 32 to line conductor 6, this circuit being from conductor 32 to conductor 3|, contact spring 29, contacts 28 and 21, conductor 36 to line conductor 6. The contacts 35 and 36 of the continuously-operated controllerare normally opened but are closed once during every'cycle of operation of the intersectionsignals At the instant that these contacts 35 and 36 engage each other a circuit is completed through the clutch coil |5. This circuit may be traced from line conductor 5, conductor 39, clutch coil l5, contact spring 31, contacts 36 and 35, conductor 38, synchronizing conductor 32, conductor 3|, contact spring 29, contacts 28 and 21, conductor 30 and line conductor 6. The clutch coil l5 thereupon opens clutch l3 against the bias of a spring 46 and thereby disconnects the drive motor 4 from the shaft l4 and stops the operation of the controller 3 and the signals A. The master controller l6 in the meantime continues to operate and rotates the cam 25- so that the spring 29 rides onto the projection 26. At this instant the circuit through the clutch coil is broken by the separation of contacts 21 and 28 and the clutch l3 closes. The cam 33 thereby rotates and separates contacts 35 and by the time the cam 25 is rotated 'far enough to allow the contacts 21 and 28 to again engage each other. The circuit through the clutch coil |5 therefore remains broken. Under normal conditions, that is, when the controller 3 is in synchronism with the master controller l6, the contacts 35 and'36 are closed at the instant that contacts 21 and 28 are opened, whereby the bitrary arrangement, since it is entirely possible that between automatically-operated intersections there will be more than one small street crossing over which few vehicles travel, and at which it is unnecessary to have a continuouslyoperated signal. It is also desirable, however, to restrict the crossing of vehicles at these intersections to such times as will not interfere with the progression of the stream of traflic along the main highway. Such times are necessarily the periods of times that would be allowedto this trafiic if continuously-operatedsignals were used.

The timing of signals along any particular highway may be such that the cycles willfbe in unison and the green and stop periods will be of common duration, or they may be so arranged that the go periods will be offset with respect to each; other in such a manner that a vehicle traveling along the highway at a predetermined speed will always have the right of way. This latter arrangement has become known as progressive timing of the signals. My invention is applicable to both arrangements of signals and is particularly useful in the progressivearrangement of the signals. a a

The traffic-actuated signals B are similar to the signals A comprising the two series of three lamps, each indicating-respectivelyas 'G, A and R. Of these signals the G signal on the main street and the R on the cross street are normally energized. The whole group of signals is controlled by a circuit controller 4|, which is normally at rest. When a vehicle approaches on the cross street, however, it operates a treadle and the controller is caused to operate the signals B through a cycle of operation and this cycle is properly timed in relation to the signaling cycles of the adjacent intersections on the highway as will be presently explainedJ To accomplish this operation the controller 4|, which is a duplicate of the controller3, isconnected to lines 5 and 6 by conductors 4'2 and 43 and is arranged to. be driven by a continuously energized motor 44 comprising a. stator 45' receiving energy a through conductors 46 and 41, and a disc armature 48. The discarmature isconnected to the controller 4| through a clutch 50 and a shaft 5|.

The clutch 56 in the'trafiic-actuated signals is normally open and the controller 4| is, therefore, normally at a standstill. This is accomplished by'providing on the shaft 5| a cam 52 having an indent 53 and a lug 54. A pair of contacts 55 and 56 are controlled by this cam. The contact 56 is mounted on a contact spring 51, the end of which rides on the cam surface 52. Whilethe spring rides on this'cam' surface the contacts 55 and 56 are separated, but when the spring 51 rides into the indent 53'the contacts engage each other. The contact 56 is'connected in series with clutch coil 58, and conductor 59 to line 5. The contact 55 is connected in series with a switch 60 through conductor 6|. The switch 66 also controls the energization of the clutch .coil 58 and is under the control of'thecam' 52 and trailic-actuated switches 62 and 63'. These switches are located in the path of the vehicles approaching the intersection from either direction on the cross street. They may be closed bythe weight of the vehicle or by any other suitable device or means which detects-the presence of a vehicle.

The switch 60 comprises two blades 64 and 65 which are maintained at an angle to each other in one or the other of two positions by a spring 66. In one position, that is, the position indicated by solid lines in the drawing, the switch blade 65 engages a contact 61 which is connected by a conductor 68 to line 6. .In this position of the switch therefore a" circuit is completed through the clutch coil 58 which may be traced as follows: line 5, conductor 59, clutch coil 58, contact spring 51, contacts 56 and 55, conductor 6|, switch blade 65 contact 61, conductor 68 and line 6. a This is a complete circuit across the line conductors'5 and 6 and the coil 58 is energized, thereby maintaining the clutch 50 in the open position. a a

When either'switch 62 or 63 is closed by a vehicle-passing over them, a circuit is closed from line 6 through conductor 10, switch 62 or 63, conductor 1|, coil 12 and conductor 13 to line 5. The coil 12 is thereby energized and pulls down its armature 14 against the pull of spring 15 and the hook 16 engages the switch blade 65 and pulls-it down to the position indicated by dotted lines intoengagement with contact 11. The contact 11 is connected to the synchronizing conductor 32 by a conductor 18. In this position therefore the clutch coil 56 is in circuit with the synchronizing conductor 32 and remains energized until the master controller separates its.

contacts 21- and 28. The circuit in this case may be traced from line 5, conductor 59, coil 58, con-' tact spring '8, contacts 56 and 55, conductor 6|,

I ductor 38 and line '6.

tive at this time to start the motor.

switch blade 65, contact 11, conductors 18, 32 and 3|, contact spring 29, contacts 28 and 21, con- When the switch arm 65 is moved from contact 6'! to contact 11, the circuit to the clutch coil 58 is momentarily broken. This momentary interruption is of such short duration, however, that the cam 52 does not move sufiiciently to separate the contacts 56, and consequently, this change of connections is ineffec- In the drawing the contacts 61 and 11 are shown as widely separated. It is clear to those skilled in the art, however, that the drawing is merely diagrammatic, and that the two contacts beingat the same potential may actually be brought sufficiently close to each other so that when the switch arm 65 passes from one to the other, it may at one point of its travel, touch both contacts, and thereby maintain the circuit to the coil 58 during the change of connections.

In operating a system of this type, the green periods of the successive intersections are adjusted with respect to each other, as indicated by the blocks 86, 6! and 82 in Fig. 3. In this figure I have represented a series of shaded rectangular blocks to represent the green periods of several consecutive intersections. As stated above, the master controller may be embodied in an intersection circuit controller. Block 88 therefore represents a green period at the master control intersection. Block 8| represents the green period at a continuously-operated intersection A. This block is slightly ofiset from the block 88 and the reference line RR to indicate that this green period starts slightly later than the green periodat the master intersection. The

blocks 82 and 83 are similarly offset. The amount of ofiset is, of course, dependent upon the distances between the intersections and the speed at which it is desired that cars should travel along the highway. At an instant at which all the signals are green on the main highway, as indicated by a line .r--.r for example, the master cam 25 is arranged to break the circuit across the contacts 21-28. The cams 33 and 52, together with the cams corresponding thereto, are arranged to close their respective contacts 3536 and 55-56 at the same instant. With this arrangement of the cams the clutch 58 will be energized and the controller 4| will remain at a standstill with a green main street indication if the switch 66 is in. the position shown in full lines in Fig. '1. If the switch 60 is then moved by the treadle switches 62 or 63 and magnet 14 to the dotted line position shown in Fig. 1, the clutch coil 58 will become deenergized when the cams assume the position, shown inFig. 3 at the next cycle of operatiomand the cam 62 will begin to rotate counter-clockwise. The contact spring 5! will ride on the cam surface 52 and separate the contacts 55 and 56. The projection 54 will thereafter engage the blade 64 and move it upwards until the switch blade 65 is pulled upward into engagement with contact 61. This will then permit the cam 52 to make a complete revolution or until the spring 51 moves into the indent 53. The contacts 55 and 56 then engage each other and complete the circuit through clutch coil 58 from line 5 to line 6. If the switch blade 65 has been pulled down into engagement with contact 71 by another actuation of treadle 62 or 63, the controller 4| will, of course, continue to operate in synchronism with the master controller, if not, the controller stops on the green main highway indication until the approach of a vehicle on the cross street has caused the switch 60 to be moved into engagement with contact 11.

The method of obtaining the adjustment of the cams is a relatively simple matter since, as

- pointed out above, all the controllers are alike.

Each of the cams make one revolution per cycle and its relative position to the signal periods of its own controller can be adjusted. The adjustments for the master cam and for the intersection controller cams are determined from a chart which is made up for each set-up of the signals, that is desired. For a progressive arrangement the starting points of they green periods are indicated as being displaced with respect to each other a certain. amount as, for example, indicated in Fig. 3. Since it is desired to maintain a green or go signal on the main highway at the normally-inactive intersection, a line :L':c is chosen which intersects each one of the green periods to indicate at what point in the green periods of each controller the clutch circuit or synchronizing circuit is. to be closed. Forthe master cam this'circuit is, of course, opened at the corresponding instance. It is evi dent from Fig. 3 that the last intersection cam will have to be set to close the synchronizing circuit in illustrated example nearer to the beginning of the green period than the cam preceding and that the master cam will separate the contacts later than. any of the others close their respective contacts. Assuming then that all controllers are set to start at the main street green indication and they are simultaneously started, the last controller will be stopped by the closing of its contacts and the energization of its clutch coil until the master cam opens its-contacts as above explained. The intermediate controllers will, of course, line up correspondingly and they will all start up at the moment the master cam opens the synchronizing circuit. Since the cycles of operation are the same, the start of the'green period of each controller will retain its relation to the start of the green periods of the other controllers as long as thesynchronizing cams and circuit are used, If then the normally-inactive controllers are placed under the control of the synchronizing cam and circuit, by the vehicleactuated switches, their respective signal periods will automatically assume the positions indicated by the Figure 3 and therefore will permit the crossing of the main highway without interfering with the progression of trafl'ic on the main highway.

What I claim as new and desire to secure by Letters Patent of the United States, is: a

1. Ina trafiic-signaling system, the combination of a plurality of groups of traflic signals, circuit controllers arranged to operate said groups of signals respectively, continuously-operating motors and connecting means for connecting said motors to drive said controllers respectively, a normally-inactive controller connected to one of .said groups of signals, a continuously-operated motor for driving said controller, connecting means for effecting operation or stoppage of said controller, a cam operated by said controller for controlling said last-mentioned means and 'for effecting a stoppage of said controller when said controller has operated its traffic signals to indicate the right of way to traffic on the main highway, means for controlling said connecting means for synchronizing the operation of said controllers, trafiic actuated means and means responsive to said traific actuated means for transferring control of said stopping and operating means to said synchronizing means for starting operation of said controller in a predetermined time relationgwith respect to said other controller for at least one operating cycle.

2. In a traffic-signaling system, the combination of a plurality of groups of trafiic signals, a

plurality of circuit controllers arranged to operatesaid groups of signals in a predetermined cycle respectively, a motorand connecting means between said motor and controller, means for continuously operating said controllers, a master controller and a synchronizing circuit controlled thereby connected 'to each of said connecting means for maintaining said controllers in synchronism, a normally inactive controller and a group of signals operated thereby, a continuouslyoperating motor for driving said controller, means for disconnecting said motor from said controller when the signals operated thereby indicate the right of way to said main highway, a cam operated by said controller for controlling said last-mentioned means, traffic-actuated means, means responsive to said traffic actuated means for trans ferring control of said disconnecting means to said synchronizing circuit, and means operated by said mastercontroller for delaying the operation of, said connecting means so asto start said controller in proper time relation relatively to said continuously-operated controllers.

3. In a traffic signaling system, the combination of a plurality of groups of signals arranged at intersections along a highway respectively, controllers connected to several of said groups of signals respectively and arranged when driven to operate said signals in a predetermined cycle and to operate corresponding signals in the several groups in a predetermined progressive relation, means for continuously driving said controllers, means for connecting said driving means to said controllers, controllers connected to others of said groups of signals arranged when driven to operate said signals through the same'sequence as said first mentioned signals are operated, said last mentioned groups of signals being arranged to normally indicate the right of way to the main highway, means for driving said last mentioned controllers, means for connecting said last mentioned controllers to said last mentioned driving means, vehicleactuated'means responsive to an' approaching vehicle on the cross street arranged to prepare said last mentioned connecting means respectively for connecting said controllers to said driving means, and synchronizing means for controlling all of said connecting means so as to synchronize theoperation of all of said controllers,,and thereby maintain the established relation between corresponding signals in the several groups of traffic signals.

4. In a traffic signaling system, a plurality of groups of traffic signals arranged at intersections of a main highway and cross streets respectively, controllers connected to several of said groups of signals and arranged when driven to operate said signals in a predetermined cycle respectively, continuously operating motors, clutch means normally connecting said motors to said controllers, controllers connected to the remaining groups of signals and arrangedrespectively when driven to operate said signals at the same sequence as said first-mentioned groups of signals are operated, clutch means between said' last mentioned controllers and their respective motors, means for opening said last-mentioned clutches when the respective groups of signals indicate right of way to the main highway, vehicle actuated means responsive to an approach of vehicles at the respective last-mentioned intersections for preparing said last-mentioned clutches to close, and

synchronizing means for closing all the clutches of the system at a common instant in each operating cycle.

5. In a trafiic signaling system, the combination of a plurality of continuously'operated groups of traffic signals, circuit controllers connected to'said groups of signals, motors for driving saidcontrollers and clutch means for connecting said motors to said controllers, a master controller and synchronizing circuit controlled thereby connected to control said clutch means for maintaining said controllers in synchronism, a normallyinactive controller, a continuously operating motor for driving said controller, clutch means for connecting and disconnectingsaid motor from said controller, a cam operated by said controller for controlling said clutch to disconnect said motor from said controller when the signals operated thereby indicate the right of way to traiiic on the main highway, and traffic-actuated means for making said clutch responsive to said master controller and synchronizing circuit in response to actuation by a vehicle approaching on the cross street, whereby said last-mentioned controller operates for at least one cycle in synchronism with said first-mentioned controllers.

HOWARD H. BELL.

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