US2293933A - Vehicle counting circuit - Google Patents

Description

Aug. 25, 1942.

Filed March 31, 1959 B. COOPER VEHICLE COUNTING CIRCUITS as; g

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Q-rll INVENTOR Patented 'Aug. 25, 1942 UNITED STATES PATENT OFFICE 2,293,933 VEHICLE COUNTING CIRCUIT Benjamin Cooper, Jersey City, N. J.

Application March 31, 1939, Serial No. 265,289

2 Claims.

This invention relates to vehicle counting circuits. It is particularly directed to the means, influenced by the passage of vehicles, which control the counting circuit for registering and counting said vehicles.

It has been found that in vehicle counting systems controlled by switch treadles on the roadway, adapted to be actuated by the wheels of vehicles, wrong counts are obtained because the switches can be actuated by pedestrians or weights. In vehicle counting systems utilizing electromagnetic detectors, adapted to be influenced by the iron in a vehicle as the vehicle moves past said detector, to operate a counter, wrong counts have often resulted because large vehicles influence not only the electromagnetic detectors in the lane of the vehicle but also the detector in adjacent lanes. It is, therefore, an object of this invention to provide a vehicle counting system which will respond only to the passage of a vehicle in a lane, and in which a count cannot be made by pedestrians, or by the passage of a vehicle in an adjacent lane.

It is a further object of this invention to provide an improved simple vehicle counting system which shall comprise a combination of the magnetic treadle and contact treadle, and require the simultaneous passage of both an iron mass and the pressure of vehicle wheels, to operate the counting circuit.

A further object of this invention is to provide a vehicle counting circuit of the character described adapted to count vehicles directly, irrespective of the number of axles thereon, and yet depends on the pressure of vehicles wheels to operate the counter.

Yet another object of this invention is to provide a vehicle counting circuit of the character described so constructed that only a single count will be produced even if the vehicle stops after the front wheels have passed over the contacts and actuated the same, and after pausing, the vehicle continues moving so that the rear wheels thereof again actuate the contacts.

In some automatic traffic supervisory systems, such as are used for controlling vehicular trafiic at street intersections, the traffic signals are operated by switch treadles, imbedded in the roadway and actuated by the vehicles approaching and leaving the intersection. It has been found that, in installations of this nature, the traflic signals may be operated by casual or mischievous actuations of the vehicle treadles by pedestrians. It is therefore a still further object of this invention to provide a simple means for detecting the passage of vehicles for controlling traflic supervisory apparatus, which is responsive only to the passage of a Vehicle and cannot be actuated by pedestrians.

Still another object of this invention is to provide a circuit of the character described which shall be relatively inexpensive to manufacture, positive in operation, and yet practical and efficient to a high degree of use.

Other objects of this invention will in part be.

obvious, and in 'part hereinafter be pointed out.

The invention accordingly consists in the features of construction, combinations of elements, and arrangement of parts which will be exemplifled in the construction hereinafter described, and of which the scope of application will be indicated in the following claims.

In the accompanying drawing,

Fig. 1 is a wiring diagram of a counting circuit embodying the invention and adapted to count vehicles;

Fig. 2 is a wiring diagram of a counting circuit embodying the invention, and illustrating a modified form of the invention, in which the counting means will produce a single count even if the vehicle stops while over the treadle, and then continues moving;

l ig. 3 is a wiring diagram of a counting circuit embodying the invention and adapted to count vehicle axles; and

Fig. 4 is a cross-sectional view of a highway showing a magnetic treadle and a treadle switch disposed thereon.

Referring to detail to Fig. 1, there is represented a vehicle counting circuit comprising a rlragnetic detector 10 and a single switch treadle The magnetic detector [0 may be of any well known suitable type comprising a permanent bar magnet II and a pickup coil l2 surrounding said magnet. The detector 10 is disposed in a lane of a highway, preferably imbedded beneath the road surface, so that it is influenced by the iron in a vehicle as it passes over the magnet.

The single switch treadle l3 may also be of any suitable type comprising a pair of top and bottom contacts, l4 and I5, which are disposed in a lane of a roadway and actuated by the pressure of wheels of a vehicle. The contacts of said treadle may be long metallic strips disposed traversely of the lane, perpendicular to the normal direction of vehicular travel, so that a vehicle wheel passing over said treadle will press the two contacts together and close the switch.

The magnetic detector l0 may be disposed directly beneath the switch I 3. Thus, the magnetic treadle is so arranged with respect to the treadle switch that a vehicle approaching in either direction will enter within range of and influence said magnetic detector before the front wheels actuate the treadle switch, and said detector remains influenced until all of the wheels have passed over the treadle switch and the vehicle is beyond said detector.

Means is provided to produce a single count on an electromagnetic counter 28 when a vehicle passes along the lane infiuencingthe magnetic detector and closing the treadle switch. To this end, the pickup coil I2 of magnetic detector I is connected in series to the coil ll of a relay I6 adapted to move a normally openswitch arm 23 into engagement with a fixed contact 22. Said switch arm 23 is connected by wire 3! to a negative power source.

Connected to the counter coil 2! in parallel circuit by wires 28 and 29 is the coil IQ of a relay. It. Said relay, when energized, is adapted to move a normally open switch arm 25 into engagement with the fixed contact 2d. One side of the coils I 9 and El is connected by wire M to the fixed contact 22, the other side of said coils I9 and 2! is connected by wire 2? to the treadle contact I 3 and by wire 33 to the fixed contact 2%. The other treadle contact I5 is connected by wire 2% to the positive power supply and switch arm 25 is also connected to the positive power supply by wire 32.

The operation of the counting system will now be described as a vehicle approaches within the range of the magnetic detector It. The magnetic field surrounding the permanent magnet II is distorted, changing the magnetic flux in member II and changing the flux linkages in the coil I 2, inducing therein a current of sufficient voltage to energize coil H of relay I B. This voltage will continue to exist as long as a vehicle is moving in the range of said permanent magnet. Upon excitation of relay I6, arm 23 is brought into engagement with contact 22.

As the front wheels of the vehicle close treadle switch IS, a circuit through coils I9 and M of relay I8 and counter 20, respectively, is completed. Said circuit is traceable from the positive power source, wire 26, treadle switch it, wire 2?, coils I9 and 2!, wire 30, contact 22, and switch arm 23, to the negative power supply. As relay I8 is excited, arm 25 closes and completes a holding circuit for both coil i9 and coil 28, traceable from the negative power source, arm 23, contact22, wire 30, coils I9 and El, wire 2?, wire 33, contact 26, arm 25, and wire 32, to the positive power source. As the front wheels pass over and release treadle switch I3, relay in and counter remain energized under the influence of said holding circuit.

As the vehicle continues along the roadway, the wheels of the second axle again actuate treadle switch I3. However, since both relay I8 and the counter 20 are held energized by their holding circuit, and relay I6 also remains energized, due to the continued influence of the moving vehicle on the magnetic detector, the second actuation of treadle switch I3 produces no effect on the circuit. The same is true for a third axle if the vehicle has three axles.

As the vehicle progresses, it passes outside the range .of the magnetic detector. The induced voltage in coil I2 disappears and relay I6 is released, opening switch arm 23 and breaking the holding circuit for coils I9 and 2|. Thus, both the counter 20 and relay were released and the circuit is restored to normal for reactuation by another vehicle. I

It will be noted that the counter coil'2I cannot be energized by the closing of treadle switch I3 unless switch arm 23 is also closed. Therefore, in order to operate the counter for registering the passage of a vehicle, the magnetic detector It must be actuated concurrently with the treadle switch I3 and that the actuation of either of said instrumentalities alone will not actuate the counter. It will also be seen that the counter is energized only once for each vehicle which passes over the treadle, irrespective of the number of axles thereon.

It will be noted that the operation of the circuit shown in Fig. 1 depends upon continued movement of the vehicle from before the actuation of the switch I3 by the front wheels of the vehicle until after the rear wheels of the vehicle have actuated said switch. Should the vehicle stop after the front wheels have closed switch I3, relay I i will be de-energized to open switch arm 23, and if the wheel thereafter continues moving again, the switch arm 23 closes, and when the next wheels of the vehicle closes switch I 3 another count is produced.

In Fig. 2, however, there is shown a count ing system which will produce a single count for each vehicle even if the vehicle stops over the magnetic detector. To this end, there is provide a magnetic detector IDA comprising an iron core IIA, preferably having upwardly extending pole portions MB, each provided with magnetizing coils 3 3 connected in series to an alternating current power supply. On the central portion of the core HA is a pickup coil I2A, connected to the coil I? of relay I6. The remainder of the circuit is similar to the circuit shown in Fig. 1.

As the vehicle approaches the detector IIlA, the presence of iron in the vehicle decreases the magnetic reluctance of the iron core IIA, thereby increasing the magnetic fiux in said core, and inducing a voltage in coil I2A sufficient to energize coil I? of relay I 6. This voltage does not depend upon movement of the vehicle, and hence, the relay It will remain energized until the vehicle passes beyond the magnetic detector, even should the vehicle stop while over the detector. In this circuit, therefore, only a single count will be produced on the counter 20, even if the vehicle stops between actuations of the switch I3 by the wheels of difierent axles of the vehicle.

Fig. 3 illustrates a system for counting the axles of vehicles passing along a lane, instead of counting vehicles directly as in Figs. 1 and 2. The circuit comprises a magnetic detector I0 and a treadle switch I 3 similar to those shown in Fig.

The detector I0 likewise comprises a permanent magnet I I carrying a pickup coil I2, connected in series to the coil II of a relay I6. The relay I6, when energized, is also adapted to move a normally open switch arm 23, connected to a minus power supply by wire 3i, into engagement with a fixed contact 22.

In the circuit of Fig. 3 there is also provided a counter 20 comprising a coil 2| connected in parallel to the coil IQ of relay Hi. The coils I9 and 2i are likewise connected on one side by wire 30 to a fixed contact 22, and on the other side by wire 2'! to the switch contact Id. The relay I8, when excited, is likewise adapted to move a normally open switch arm 25, connected by wire 32 to the positive power supply, into engagement with a fixed contact 24. The treadle contact i is likewise connected by wire 25 to the plus power supply.

Counter 20, when energized, is adapted to open a switch arm 83c, normally engaging a fixed contact 33b. Switch arm 330 is connected by wire 83d to the fixed contact 24. The fixed contact 33b is connected by wire 33a to the wire 21, and hence,'to one side of the coils I9 and 2|.

The operation of the axle counting circuit of Fig. 3 will now be described. As a vehicle enters the range of the magnetic detector Hi, the induced-voltage of coil l2 energizes coil ll of relay l6. As the vehicle continues along the highway the front wheels close treadle switch l3, completing a circuit which energizes relay l3 and counter 20, as heretofore described.

The closing of relay l8 closes switch arm 25 and completes a holding circuit for both coils I! and 2|, said circuit being traceable from positive power source, wire 32, arm 25, contact 24, wire 33d, arm 33c, contact 33b, wire 33a, coils l9 and 2] in parallel, wire 30, contact 22, arm 23, to negative power supply. Since counters are usually relatively slow acting mechanisms due to their mechanical inertia, the purpose of the above mentioned holding circuit is to insure the operation of the counter if the vehicle is moving so rapidly that the counter does not have sufilcient time to become completely energized before the treadle switch I3 is released, after having been closed. As soon as counter 20 is energized, contact arm 330 is opened, thereby breaking the holding circuit and releasing relay l8 and counter 20.

If the counter becomes completely energized before the front wheels release treadle switch i3,

the counter will not be de-energized until said treadle switch is opened, thereby preventing the registration of more than one count for the passage of one axle.

As the vehicle continues along the highway, the wheels on the second axle again close switch l3. Since relay I5 is maintained energized, due to the continued influence of the moving vehicle on the magnetic detector, switch arm 23 is still closed. Therefore,'the second closure of treadle switch will again energize relay l8 and counter 20 in a manner identical with the passage of the first axle, and the counter will again register a count and be released. Similarly, if the vehicle has three axles, the third axle will register a third count.

After the'last axle has passed over the treadle switch, the vehicle continues along the highway and moves out of the range of the magnetic detector, releasing relay [6, and restoring the circuit to normal for reactuation by another vehicle.

It will be understood that, although the magnetic detector In and IDA of Figs. 1, 2, 3, and 4 are illustrated as comprising a bar magnet ll, HA, and a pickup coil l2, IZA, any type of detector may be utilized which is influenced by the proximity of an iron mass, and which will actuate a switch, such as 22, 23 of Figs. 1, 2, and 3 when so influenced.-

It will thus be seen that there is provided a device in which several objects of this invention are achieved and which is well adapted to meet the conditions oi! practical use.

As various possible embodiments might be made of the above invention, and as various changes might be made in the embodiment above set forth, it is to be understood that all matter herein set forth or shown in the accompanying drawing is to be interpreted as illustrative and not in a limiting sense.

Having thus described my invention, I claim as new and desire to secure by Letters Patent:

1. A system for counting vehicles in a lane,

comprising, a magnetic detector adapted to be influenced by magnetic mass in vehicles in said lane, a treadle switch in said lane adapted to be actuated by the wheels of said vehicles, a pair of electro-magnets, an operating electro-magn'et, means to energize one of said pair of electromagnets when said magnetic detector is influenced by a vehicle in said lane, means, controlled by the first of said pair of electro-magnets, to energize the other of said pair of electro-magnets, when said treadle switch is thereafter actuated by the wheels of said vehicle, said last means being inoperative to energize said other of said pair of electro-magnets unless said detector is influenced, and means to energize said operating electro-magnet when both of said pair of electro-magnets are energized.

2. A system for counting vehicles in a lane, comprising, a magnetic detector adapted to be influenced by magnetic mass in vehicles in said lane, a treadle switch in said lane adapted to be actuated by the wheels of said vehicles, a pair of electro-magnets, an operating electro-magnet, means to energize one of said pair of electromagnets when said magnetic detector is influenced by a vehicle in said lane, means, controlled by the'first of said pair of electro-magnets, to energize the other of said pair of electro-magnets, when said treadle switch is thereafter actuated by the wheels of said vehicle, said last means being inoperative to energize said other of said pair of electro-magnets unless said detector is influenced, and means to energize said operating electro-magnet when both of said pair of electro-magnets are energized, and including means to retain said operating electro-magnet energized as long as said first of said pair of electro-magnets remains energized.

BENJAm COOPER.

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