DEVICE FOR DETECTING RAILWAY TRAFFIC

Description

[0001] The invention relates to the field of rail traffic detection systems. BACKGROUND OF THE INVENTION

[0002] In the context of rail traffic management and safety, it is known to have detection systems that can detect, at a given point, the passage of a train or any other railway vehicle.

[0003] Detection systems are generally positioned in the vicinity of a rail of a railway track and typically comprise at least one sensor for activating an electrical contact. Thus, when a train passes, each wheel of the train moves the sensor from a high position to a low position and temporarily activates the electrical contact, thus constituting a train detection signal. More specifically, each wheel comprising a tread having a projecting edge from which a bead extends, it is the bead of each wheel which presses on the sensors.

[0004] Each probe is carried by a horizontal rod which can rotate about its axis between a first angular position corresponding to the high position of the probe and a second angular position corresponding to the low position of the probe in such a way that pressing on the probe causes the rod to rotate from its first angular position to its second angular position. Two diametrically opposed arms are connected to the rod: one on which a member for returning the rod to its first angular position rests and one on which the rod of a hydraulic damping cylinder extending perpendicular to the rod rests to slow down or delay the return of the rod to its first position.

[0005] However, given that such detection systems are located in isolated locations along railway tracks, it is difficult to check their operating and / or wear status in real time. It is therefore impossible to know whether or not such a system requires maintenance.

[0006] Document EP3885233A1 discloses a railway detector with a rotating arm 1 arranged to be rotated by a train wheel, establish an electrical contact and generate a control signal. A lever 2 is rotationally fixed to the arm 1, against the action of a spring blade 3. The lever 2 is arranged to move a selection rod 4 against the action of a return spring rod 41. The return of the selection rod 4 to the rest position is timed by a rotary mechanical timer with an adjustable friction brake 35. SUBJECT OF THE INVENTION

[0007] One aim of the invention is therefore to propose a solution making it possible to improve the reliability of rail traffic detection systems. SUMMARY OF THE INVENTION

[0008] It was found that one of the reasons why the reliability of these detection systems could be called into question lies in the damping cylinder being subject to wear and whose damping characteristics are modified by environmental conditions and more particularly temperature.

[0009] According to the invention, a system for detecting the presence of a railway vehicle is proposed, comprising a housing, a sensor outside the housing, at least one rod which carries the sensor and which is mounted in the housing to pivot between a high position and a low position of the sensor, a member for slowing down the rod in rotation from the low position to the high position of the sensor, a member for returning the rod to the high position of the sensor. The slowing down member comprises a shaft connected in rotation to the rod and movable in rotation relative to a braking member arranged to cooperate by friction with a part connected in rotation to the shaft to brake the latter. The braking member comprises a centrifugal friction regulator.

[0010] The slowing of the rod movement is then ensured by limiting the risks of premature wear and the braking member has a particularly simple structure.

[0011] According to a particular embodiment, the centrifugal friction governor comprises a plurality of masses connected to the shaft by elastically deformable arms to move between a position separated from and a position close to the shaft and received in a fixed skirt to limit the separation of the masses relative to the shaft, the masses having an external surface for rubbing on an internal surface of the skirt.

[0012] Preferably then, the skirt is axially adjustable in position to set a maximum spacing of the masses.

[0013] According to a particular feature, the shaft extends perpendicular to the rod and is connected to it by an angle gear.

[0014] The detection device then has an arrangement of its various elements which is close to those of the prior art, with the shaft and the braking member substantially in the same position as the damping cylinder of the prior devices. It is then possible to have housings of similar shape and size, and to keep the same frames for fixing the devices to the railway sleepers so that the habits of the operators responsible for installing the devices are not modified.

[0015] Other characteristics and advantages of the invention will emerge upon reading the following description of particular non-limiting embodiments of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The description of the invention refers to the attached drawings, among which: [ Fig. 1 ] there figure 1 represents a top view of the detection system according to the invention; [ Fig. 2 ] there figure 2 represents a side view of the detection system illustrated in figure 1 and its positioning relative to a rail of a railway track; [ Fig. 3 ] there figure 3 represents in perspective the internal mechanical architecture of the detection system illustrated in figure 1 , top view with the case cover removed; [ Fig. 4 ] there figure 4 is a view of the internal mechanical architecture of the detection system, in section along plane IV of the figure 3 . DETAILED DESCRIPTION OF THE INVENTION

[0017] In reference to the figure 1 , the detection system 1 according to the invention comprises a housing 2 as well as a first probe 3.1 and a second probe 3.2 extending outside the housing 2. The first probe 3.1 and the second probe 3.2 are generally shaped as a bar of circular section which is bent to comprise a first section and a second section substantially perpendicular to each other.

[0018] There figure 2 allows the positioning of the detection system 1 to be visualized relative to a rail R (here represented by a cross-sectional view) of a railway track. The detection system 1 is positioned in the vicinity of the rail R such that one end 3.1a of the first sensor 3.1 and one end 3.2a of the second sensor 3.2 are opposite a rail head Rc of the rail R.

[0019] In reference to the figure 3 , the contents of the housing 2 forming the internal architecture of the detection system 1 will now be described.

[0020] The detection system 1 comprises a first rod 4.1 mounted in the housing 2 to extend and pivot along an axis Y.1 here horizontal and a second rod 4.2 mounted in the housing 2 to extend and pivot along an axis Y.2 also horizontal, the axis Y.1 being parallel to the axis Y.2. In addition, the first rod 5.1 has a first end carrying, projecting from the housing 2, the first section of the probe 3.1 and the second rod 4.2 has a first end carrying, projecting from the housing 2, the first section of the second probe 3.2 in such a way that a movement from top to bottom and from bottom to top of the probe 3.1, 3.2 causes a rotation of the rod 4.1, 4.2 and vice versa. The first section of each probe 3.1, 3.2 thus extends perpendicular to the axis Y.1, Y.2 and the second section of each probe 3.1, 3.2 thus extends parallel to the axis Y.1, Y.2.

[0021] The detection system 1 further comprises a first return member 5.1 and a second return member 5.2. The first return member 5.1 is an elastic blade having an end 5.1a rigidly fixed to the housing 2 and a free end portion 5.1b which bears against an arm 6.1 which extends perpendicular to the first rod 4.1 and which is rotationally integral with the first rod 4.1. The second return member 5.2 is an elastic blade having an end 5.2a rigidly fixed to the housing 2 and a free end portion 5.2b which bears against an arm 6.2 which extends perpendicular to the second rod 4.2 and which is rotationally integral with the second rod 4.2.

[0022] A bevel gear 7.1, 7.2 is fixed to a second end of the first rod 4.1, 4.2 opposite the first end to cooperate with a bevel gear 8.1, 8.2 secured to a first shaft 9.1, 9.2 mounted in the housing 2 to pivot along an axis Z.1, Z.2 perpendicular to the axis Y.1, Y.2, i.e. the axis Z.1 is vertical. A centrifugal regulator 10.1, 10.2 is rotatably connected to the shaft 9.1, 9.2, here a friction centrifugal regulator known per se. The centrifugal friction governor 10.1, 10.2 comprises a secondary shaft 10.11, 10.21 parallel to the first shaft 9.1, 9.2 and rotationally connected to it by gears not shown, four identical masses 10.22 (the masses connected to the secondary shaft 10.11 are not visible) equally distributed angularly and connected to the shaft 9.1, 9.2 by four elastic arms 10.13, 10.23 to be movable between a position close to the secondary shaft 10.11, 10.21 and a position away from the secondary shaft 10.11, 10.21.The masses 10.22 are received in a skirt 10.14, 10.24 of truncated cone shape which is fixed in rotation and which is arranged to oppose an excessive spacing of the masses 10.22 with respect to the secondary shaft 10.11, 10.21 and to brake the rotation of these, the masses 10.22 having an external surface abutting against an internal surface of the skirt 10.14, 10.24. The external surface of the masses 10.22 and the internal surface of the skirt 10.14, 10.24 are arranged to form friction surfaces allowing braking when they are applied to each other. The skirt 10.14, 10.24 is adjustable in height: due to the truncated shape of the skirt 10.14, 10.24, when the skirt 10.14, 10.24 is in the low position (the masses 10.22 are then close to the small section of the skirt), the external surface of the masses rubs on the internal surface of the skirt 10.14, 10.24 for a rotation speed of the secondary shaft 10.11, 10.21 less than that for which the masses 10.22 rub against the skirt 10.14, 10.24 when the skirt 10.14, 10.24 is in the high position (the masses 10.22 are then close to the large section of the skirt). In other words, adjusting the height of the skirt 10.14, 10.24 makes it possible to modify the radius of the average contact circle of the masses with the skirt 10.14, 10.24, which makes it possible, for a given restoring torque, to modify the equilibrium angular speed and consequently the total duration of the rise of the probe in the high position.

[0023] We understand that: when the secondary shaft 10.11, 10.21 is stationary, the masses 10.22 are held close to the secondary shaft 10.11, 10.21 by the elastic arms 10.13, 10.23 which are in a state of rest; when the secondary shaft 10.11, 10.21 is rotated and the faster the shaft 9.1, 9.2 rotates, the more the masses are moved away from the secondary shaft 10.11, 10.21. When moving away from the shaft 10.11, 10.21, the external surface of the masses comes into contact with the internal surface of the skirt 10.14, 10.24. The normal component (in the Frenet frame of the masses) of the reaction force exerted by the skirt 10.14, 10.24 on the masses 10.22 depends on the angular velocity of the shaft 9.1, 9.2. The friction forces of the masses on the skirt 10.14, 10.24 (tangential component and opposite to the direction of movement of the masses) are proportional to the normal component.Thus, the friction between the external surface of the masses and the internal surface of the skirt generates a torque which opposes the rotation of the shaft 9.1, 9.2. When this torque is identical to the gear ratio near the torque exerted by the spring 5.1, 5.2 on the rod 4.1, 4.2, the rotational movements of the different parts of the device are carried out at constant angular speed, which makes it possible to regulate the return time to the high position of the probe 3.1, 3.2.

[0024] A freewheel device 11.1, 11.2 is placed on the rod 4.1, 4.2 to allow the arm to descend without driving the bevel gears 7.1, 8.1, 7.2, 8.2. The freewheel device has a small engagement angle. The freewheel device 11.1, 11.2 here comprises, for example, an outer ring gear having an internal toothing of 2M teeth and an inner pinion mounted coaxially in the outer ring gear and provided with 2N pawls which engage in the teeth of the outer ring gear in only one direction of rotation. The 2N pawls are diametrically opposed in pairs and are arranged such that the angle between two adjacent pawls is 180 / (M x N) degrees. The engagement angle of the freewheel thus obtained is at most 180 / (M x N) degrees. Alternatively, a ratchet freewheel can be used, for example comprising six pairs of ratchets at 31° to each other: the engagement angle of the freewheel is therefore one degree.We can also use: a roller freewheel; or a freewheel with two coaxial crowns having internal teeth with numbers of teeth that are prime to each other, with a pawl for one crown and a ratchet for the other crown.

[0025] The operation of the detection system 1 will now be described.

[0026] The operation of a first kinematic chain of the detection system 1 will be described here in particular, which comprises the first sensor 3.1, the first rod 4.1, the first return member 5.1, the arm 6.1, the angle transmission formed by the pinions 7.1 and 8.1, the first shaft 9.1 and the centrifugal regulator 10.1.

[0027] As previously described, the first feeler 3.1 is opposite the rail head Rc of the rail R. Thus, when a railway vehicle passes, the first feeler 3.1 will change position, between a high position and a low position, due to the passage of the wheels of the railway vehicle. The change of position between the high position and the low position of the first feeler 3.1 corresponds to a rotational movement of the first rod 4.1 along the axis X.1. Thus, the first rod 4.1 pivots around the axis X.1.

[0028] Consequently, the arm 6.1 will exert a force on the free end portion 5.1b of the first return member 5.1, and more precisely will cause the free end portion 5.1b to descend and thus elastically deform the first return member 5.1.

[0029] When the passage of a wheel of a railway vehicle is completed, the free end portion 5.1b of the first return member 5.1 will return, under the effect of the elasticity of the first return member 5.1, to its initial position by pressing on the arm 6.1 to make it rise. The first rod 4.1 will thus pivot around the axis Y.1 so that the first feeler 3.1 leaves its low position to go to its high position. At the same time, the free wheel 11.1 is then engaged and the bevel gears 7.1, 8.1 will rotate the first shaft 9.1 and the centrifugal regulator 10.1. The centrifugal regulator 10.1 is thus arranged to regulate the rotational movement of the first rod 4.1 (from the low position to the high position of the first feeler 3.1). The centrifugal regulator 10.1 therefore sets a duration of the rotational movement of the first rod 4.1 from the low position to the high position of the first feeler 3.1.

[0030] The operation of the second kinematic chain of the detection system 1 - which comprises the second probe 3.2, the second rod 4.2 pivoting around the axis Y.2, the second return member 8.2, the arm 6.2, the angle transmission formed by the pinions 7.2 and 8.2, the shaft 9.2 and the centrifugal regulator 10.2 - is obviously similar to what has just been described for the first kinematic chain of the detection system 1. Furthermore, the detection system 1 could obviously only comprise the first kinematic chain.

[0031] The invention is not limited to the embodiments described but encompasses any variation falling within the scope of the invention as defined by the claims.

[0032] Here and advantageously, the first rod 4.1 is a single piece with the first probe 3.1. In the same way, the second rod 4.2 is a single piece with the second probe 3.2. However, the first rod 4.1 could be a separate piece from the first probe 3.1 and / or the second rod 4.2 could be a separate piece from the second probe 3.2.

[0033] Furthermore, the first return member 5.1 and the second return member 5.2 are not necessarily elastic blades but could be, for example, vertically mounted helical springs.

[0034] Furthermore, the detection system 1 could comprise only the first kinematic chain, i.e. only the first sensor 3.1, the first rod 4.1, the first return member 5.1, the arm 6.1, the angle transmission and the damping member.1.

[0035] The angle transmission may be formed by toothed or friction gears. The shaft of the damping member may extend parallel to the rod or even coaxially with it. The shaft 9.1, 9.2 may not be perpendicular to the rod 4.1, 4.2.

[0036] The slowing member can be carried directly by the rod 4.1, 4.2, or the shaft 9.1, 9.2.

[0037] The number of masses 10.22 and elastic arms 10.13, 10.23 could be less or more than four.

[0038] The detection system 1 may comprise a monitoring device comprising an electronic measuring circuit arranged to measure the position of a first movable element with the first rod 4.1 when the latter pivots between the high position and the low position of the first probe 3.1. In the same way, the electronic measuring circuit 16 is arranged to measure the position of a second movable element with the second rod 4.2 when the latter pivots between the high position and the low position of the second probe 3.2. The monitoring device comprises for example: a first magnet positioned on the first movable element and a second magnet positioned on the second movable element. The first magnet and the second magnet are permanent magnets. the electronic measuring circuit which comprises a first magnetic sensor arranged to detect a magnetic field of the first magnet and a second magnetic sensor arranged to detect a magnetic field of the second magnet. The first magnetic sensor and the second magnetic sensor produce electrical signals which are processed by the electronic measuring circuit which is preferably associated with a transmission circuit thus recovering magnetic field intensity measurement data to transmit them, for example, to a monitoring center. It is also provided that the transmission circuit further comprises a radiofrequency reception component in order to receive any instructions from the monitoring center. Alternatively, the monitoring device could for example comprise a first eddy current sensor arranged to measure the deformation of the first return member 5.1 and a second eddy current sensor arranged to measure the deformation of the second return member 5.2. The deformation of each of the return members 5.1, 5.2 is respectively representative of the position of the probes 3.1, 3.2.The first eddy current sensor and the second eddy current sensor could for example be advantageously mounted on the PCB 21 (and connected to the processing means 16a of the electronic measuring circuit 16) such that said first eddy current sensor is positioned in the vicinity of the first return member 5.1 and said second eddy current sensor is positioned in the vicinity of the second return member 5.2. The use of an eddy current sensor does not require in particular positioning a magnet on each of the return members of the detection system. The monitoring device could also comprise a first strain gauge and a second strain gauge respectively positioned on the first return member. 5.1 and on the second return member 5.2. The deformation of each of the return members 5.1, 5.2 is respectively representative of the position of the feelers 3.1, 3.2.

[0039] The monitoring system can be used, in particular, to count the number of operations of the detection system.

[0040] In particular, it can help identify failures in the timing system or broken sensors.

[0041] It may or may not also include an accelerometer.

[0042] It may or may not also include a temperature measuring device.

[0043] The invention also applies to detection devices in which the rod carrying the probe is mounted to pivot about an axis perpendicular to the longitudinal direction of the rod. The shaft of the slowing member can serve as a pivot axis of the rod.

Claims

1. A system (1) for detecting the presence of a rail vehicle, comprising a housing (2), a feeler (3.1, 3.2) outside the housing, at least one rod (4.1, 4.2) which carries the feeler and which is mounted in the housing so as to pivot between a high position and a low position of the feeler, a member (10.1, 10.2; 20.1) for slowing the rod in rotation from the low position to the high position of the feeler, a member (5.1, 5.2) for returning the rod to the high position of the sensor, characterised in that the slowing member comprises a shaft (10.11, 10.21; 9.1) connected in rotation to the rod and movable in rotation relative to a braking member (10.12, 10.13, 10.22, 10.23; 20.11, 20.12) arranged to cooperate by friction with a portion connected in rotation to the shaft in order to brake the latter, and in that the braking member (10.1, 10.2) comprises a friction centrifugal regulator.

2. The system according to claim 1, wherein the shaft (9.1, 9.2, 10.11, 10.21) is substantially perpendicular to the rod (4.1, 4.2) and connected thereto by a bell crank (7.1, 8.1, 7.2, 8.2).

3. The system according to claim 1 or claim 2, wherein the friction centrifugal regulator comprises a plurality of masses (10.22) connected to the shaft (10.11, 10.21) by arms (10.13, 10.23) elastically deformable to move between a spaced-apart position and a position close to the shaft and received in a skirt (10.14, 10.24) fixed in rotation to limit the spacing of the masses from the shaft, the masses having an outer surface for rubbing on an inner surface of the skirt.

4. The system according to claim 3, wherein the skirt is axially adjustable in position to adjust a maximum spacing of the masses.

5. The system according to any one of the preceding claims, comprising a freewheel device between the shaft and the rod for allowing free rotation of the rod to the low position of the feeler and damping rotation of the rod to the high position of the feeler.

6. The system according to claim 2, wherein the bell crank comprises two pinions meshing with each other.

7. The system according to claim 6, wherein the pinions are arranged to frictionally mesh with each other.