FR2460014A1 - Triple function traffic counter - uses magnetic and pneumatic detection to separate light and heavy vehicles and number of axles - Google Patents

Abstract

The traffic counter records simultaneously the number of heavy vehicles, the number of light vehicles and the number of vehicle axles crossing the detector, which comprises a magnetic coil (1) implanted in the road surface, and a rubber tube (6), both being placed across the roadway. An electronic circuit (2) which responds to the change in inductance of the coil (1) when a vehicle passes is set to respond only to light vehicles, and the pneumatic tube (6) is connected to an electropneumatic contactor (7) with two contacts (8,9) adjustable to respond to different pressure levels. The magnetic detector (2,4) inhibits one of the pneumatically operated counters (13) when a light vehicle passes, while the other pneumatically operated counter (12) counts the number of axles of all kinds of passing vehicles.

Description

 The present invention relates to automatic counting devices for road vehicles which use as sensors a magnetic detector associated with an elastic hose stretched across the road while simultaneously obtaining on wooden counters, on the one hand, the number of heavy vehicles, on the other hand, the number of light vehicles and finally the total number of axles crossing the pipe.

 Known devices of this kind are capable of giving, on two separate meters, only the number of heavy vehicles and that of total traffic. But in addition, given that they play for the discrimination of heavy vehicles on the length of the latter this discrimination is put in default in the case of passages of light vehicles tracking a trailer, note caravans, which are counted as heavy vehicles .

 Furthermore, these devices can only play for one direction of traffic.

The device according to the invention can operate for both directions of traffic and furthermore very significantly improves the discrimination performance of heavy vehicles while simultaneously giving the number of light vehicles as well as the total number of axles of all vehicles. including those of two-wheeled vehicles ee which allows to assess, with a satisfactory approximation the number of these.

 For {iserieination heavy vehicles - light vehicles the device plays on the height of the front of these vehicles relative to the roadway, height much greater for heavy vehicles than for others.

 The single board materializes the entire device.

 In I is a magnetic loop consisting of several turns of conductive wire, implanted in a groove made in the road, whose major axis is perpendicular to the axis of the latter.

 The ends of this loop lead to an electronic detector 2 which, when the passage of a vehicle modifies its self induction, delivers an electric pulse which, on the one hand, activates the counter 3 and on the other hand inhibits, by the means of the electronic device 4 the pulse co-sensor 13 which is discussed below.

The duration of the inhibition is set by the timer 5.

 In 6, a rubber hose, of the type used for road meters, is installed on the road along the major axis of the ragnetic loop.

 The pneumatic pulses, caused in the pipe by the passage of the axles, are applied to an electropneumatic contactor 7, with double electrical contacts 8 and 9, of hardness adjustable by the knobs 10 and 11.

 The I = electric drive from contact 9 acts directly on the counter 12 which accounts for the passage of all the axles on the pipe regardless of the nature of the vehicles.

 The electric pulse from contact 8 cannot, however, increment counter 13 as long as the latter is not inhibited by the magnetic loop by means of the electronic device 4.

 An adjustable timing device 14 makes it possible to limit the advance of the counter 13 to a single unit regardless of the number of axles of the vehicle.

The principle of operation is as follows. Firstly, it is specified that the sensitivity of the magnetic loop is adjusted to a value such that it is sensitive to light vehicles, without being at the front of heavy vehicles.

Furthermore, the hardness of the contact 8 is adjusted so that the electrical contact cannot take place when a two-wheeled vehicle passes over the pipe, but on the other hand it takes place under the passage of a heavy vehicle, adjustment easy to carry out given the great importance of the difference in power of the pneumatic pulses caused by these two categories of vehicles.

 The time delay 14 is itself adjusted in such a way that the counter 13 only registers a single unit 80US for the passage of heavy vehicles regardless of the number of axles of the latter.

 Let us examine what happens when a light vehicle crosses the loop - pipe device.

 When it approaches loop I, in any direction of flow, the metal mass of the vehicle changes its self induction which causes, via the detector 2, simultaneously the operation of the counter 3 which advances by one unit and inhibition of counter 13.

 As a result, the axles of this vehicle have no action on the latter counter, while each of them increments the counter 12.

The vehicle will therefore be counted for one unit on counter 3 and the number of its axles on counter 12.

 In the case where a heavy vehicle approaches the loop, it has no action on the latter at least until the front wheels attack the pipe. Nothing therefore stands in the way of the pneumatic impulse which results from this attack caused by the time delay 14, the incrementation of the counter 13 which advances by one unit while each of its two es advances of a unit the counter 12.

 If a two-wheeled vehicle crosses the hose loop device, its low metallic mass does not have a sufficient influence on the loop self-inducing to increase the counter 3.

 I1 will be the same for the counter 13 due to the hardness of the contact 8.

 The passage of the axles of this vehicle on the pipe 6 will on the other hand be recorded by the counter 12, the control contact 11 of which can be adjusted sufficiently soft so that it is so

Claims (1)

 I - Device for the automatic counting of road vehicles, with the possibility of simultaneously obtaining the number of heavy vehicles, the number of light vehicles as well as the total number of axles of vehicles of all kinds crossing the sensor device placed across the road .  II - Device according to claim I - Characterized by the fact that the sensor is constituted by a magnetic loop implanted across the road and by an elastic pipe implanted it mantles along the axis of the loop perpendicular to the axis of the roadway .  III - Device according to claim II - Characterized by the fact that due to the symmetry of the pipe loop sensor the device can operate for both directions of circulation.  IV - Device according to claim II - Characterized by the fact that the magnetic loop is only influenced by the passage of light vehicles. e V - Device according to claim II - Characterized by the fact that the stopper leads to an electro-paeumatic contactor comprising two contacts of adjustable hardness transmitting the electrical pulses to two separate counters.  VI - Device according to claim Y - Characterized by the fact that one of the counters is inhibited by the passage of a light vehicle over the magnetic loop.  VII - Device according to claim V - Characterized by the fact that this same counter is insensitive to the passage of two-wheeled vehicles on the pipe because of the hardness of the electrical contact which controls it and that consequently only heavy vehicles can increment this counter.  VIII - Device according to claim V - Characterized by the fact that the counter not inhibited by the magnetic loop registers all of the axles of vehicles of all kinds crossing the pipe.  II - Device according to claim VIII Characterized by the fact that the figures given by the counter not inhibited by the loop, can, taking into account the readings of the counters for heavy vehicles and light vehicles7 allow the approximate calculation of the axles of two-wheeled vehicles having crossed the pipe.