EP0582528B1 - Checking the clamping pressure of a detachable grip of a ropeway - Google Patents

Abstract

A chair lift or a cable car having detachable grips (11) is equipped with a device for measuring the clamping force on the cable (10) by the jaws of the grip under the action of a closing spring. The closing control ramp, which actuates the control lever of the grip, comprises a measuring portion (30) carried by load cells (31). By measuring the force or action exerted on this portion at the moment of clamping of the grip, a weighted measurement of the clamping force is obtained. <IMAGE>

Description

• des pinces débrayables d'accouplement de charges au câble, chaque pince ayant un levier d'actionnement pour l'ouverture et la fermeture de la pince, un ressort sollicitant ledit levier en position de fermeture de la pince et fournissant la force de serrage de la pince sur le câble et un organe de commande porté par ledit levier,
• une rampe de commande s'étendant le long de la trajectoire de défilement de la pince, à la sortie d'une station pour commander la fermeture de la pince et son embrayage sur le câble, ladite rampe coopérant avec ledit organe de commande au passage de la pince,
• et un moyen de contrôle du serrage de la pince.

The invention relates to a transport installation using an overhead cable-tractor traveling continuously, in particular a cable car or chairlift comprising;

• disengageable clamps for coupling loads to the cable, each clamp having an actuating lever for opening and closing the clamp, a spring urging said lever in the closed position of the clamp and providing the clamping force of the clamp on the cable and a control member carried by said lever,
• a control ramp extending along the path of travel of the clamp, at the exit of a station to control the closing of the clamp and its clutch on the cable, said ramp cooperating with said control member in the passage of the pliers,
• and a means of controlling the clamping of the clamp.

A known installation of the kind mentioned, is equipped with a control ramp which exerts on the clamp control member, closed on the cable, a predetermined elastic force just lower than the normal force of opening of the clamp. The movement of the control lever under the action of this lower force indicates a failure of the clamp closing spring, but the reverse is not ensured. Failure to move the control lever may result from seizure or any other incident and this check is not of absolute safety. This control is also of the all or nothing type and does not allow monitoring of the development of the state of the clamp.

Document EP-A-0 181 244 describes a device for measuring the force exerted by the gripper control member on a T-shaped control ramp. A notch, formed on a section of the leg of the T confers a certain flexibility in the sole of the T which cooperates with the control member. In the middle of this flexible part is placed a proximity sensor capable of measuring the deformation of the sole when passing a clamp, under the action of the control member. The maximum deformation and therefore the maximum measurement occurs when the clamp is in the middle of the flexible section opposite the proximity detector and this measurement is compared with a threshold value, to trigger a display and / or an alarm if it is less than this. threshold. When the measurement is above this threshold and taking a safety margin, it can be assumed that the clamping force of the clamp on the cable, provided by the spring, is sufficient. However, this clamping force is not measured. With the wear of the cable and the jaws of the clamp, the clamp is closed at different points on the ramp, generally separated from the measuring point in the middle of the flexible part and the force measured is therefore different from the clamping force. . The measurement is punctual, in the middle of the flexible part and a measurement at another point is necessarily distorted by the variation in the bending of the flexible part.

The installation according to the invention is characterized in that the control means comprises a device for continuous measurement of the action exerted by the control member on the ramp and a detector of the moment of closing of the clamp on the cable to carry out a measurement of said action at this instant.

The action on the ramp is generated by the force of the closing spring which keeps the lever in support of the ramp and it is understood that this action is equivalent to the force of the spring reduced by friction and possibly affected by a multiplication factor due to levers. A measurement of the action therefore constitutes a safe weighted measurement of the force of the spring.

Advantageously, the installation according to the invention can use a clamp of the type described in French patent No. 2497750, in which the movable jaw is pivotally mounted and is carried by one end of the actuation lever, the other end of which carries the control member and is directly attacked by the clamp closing spring. This direct connection by the actuating lever between the spring, the control member and the movable jaw ensures perfect equivalence between said action, just before the clamp is closed and the clamping force exerted on the cable by the jaw at closing time. As soon as this is closed, the action on the ramp is transferred to the cable and the control member leaves the ramp. In the area of coupling the clamp to the cable and measuring the clamping force, the clamp rolls on a rail, which diverges with the control ramp so as to allow the spring to relax during the advancement of the clamp and a clamp closure.

The measurement area is limited to the ramp section corresponding to the closing of the clamp and the length of this section is sufficient to take into account the wear of the clamps and of the cable and the manufacturing tolerances. The transfer of the force from the ramp to the cable can be detected by the separation of the control member and the ramp, in particular by providing a conductive track on the ramp, in electrical contact with the control member, the separation of which interrupts the circuit. The measurement adopted is that which precedes the interruption of the electrical circuit. The transfer of force can be detected by other means, for example by immobilizing the control lever or by analyzing the variation of the measurement signal. During the clamp closing stroke the action on the ramp decreases regularly, due to a progressive relaxation of the spring and this action suddenly goes to zero when the clamp is closed and the control member is separated from the ramp. A recording of the measurement of this action shows the sudden variation and the value preceding this variation is retained. This analysis can of course be automated so as to have, at each pass, a clamp with the indication of the clamping force, which is either displayed or used to control the stopping of the installation if it is insufficient.

The measurement is advantageously carried out by supporting the measurement section of the ramp by load cells or by a balance, but other means are conceivable. The device is particularly simple and is applicable to standard pliers without any adaptation. It is intrinsically safe and its simplicity gives it great reliability.

• la figure 1 est une vue schématique en élévation et en coupe d'une pince d'une installation selon l'invention;
• les figures 2 et 3 sont des vues schématiques en élévation et en plan de la zone d'embrayage et de mesure;
• la figure 4 illustre la variation de l'action sur la rampe selon la position de la pince;
• la figure 5 est une vue de détail à échelle agrandie de la figure 2;
• les figures 6,7,8 et 9 sont des vues analogues à celle de la figure 1 montrant la pince dans les positions successives repérées en 6,7,8 et 9 sur la figure 2.

Other advantages and characteristics will emerge more clearly from the description which follows of an embodiment of the invention given by way of nonlimiting example and represented in the appended drawings, in which:

• Figure 1 is a schematic elevational view in section of a clamp of an installation according to the invention;
• Figures 2 and 3 are schematic elevational and plan views of the clutch and measurement area;
• FIG. 4 illustrates the variation of the action on the ramp according to the position of the clamp;
• Figure 5 is an enlarged detail view of Figure 2;
• Figures 6,7,8 and 9 are views similar to that of Figure 1 showing the clamp in the successive positions identified in 6,7,8 and 9 in Figure 2.

In the figures, a cable 10 of a single-cable air transport installation, in particular of a chairlift or a gondola, is driven continuously. The loads, in this case the seats or the cabins, are fixed to the cable 10 in line by clamps 11 of the disengageable type to allow opening of the clamp in the stations and boarding or disembarking at a standstill or at reduced speed, passengers in seats or cabins. On leaving the station, the seats or cabins are re-accelerated and re-coupled by closing the clamp on the cable 10

The clamp 11 shown in Figure 1 has an elongated body 12 on which is articulated the end of a hanger 13 carrying the load (not shown). The body 12 also carries rollers 14 for rolling on support rails 15 in the stations. One of the ends of the body 12 is shaped as a fixed jaw 16, which cooperates with a movable jaw 17, articulated on the fixed jaw 16 and integral with the end of a control lever 18. The opposite end 19 of the lever 18 carries an axis 21 of articulation of a control roller 20 and an axis 22 of anchoring of a coil compression spring 23. The opposite end of the spring 23 bears on a cup 24 secured to the body 12 by tie rods 25. A friction plate 27 is fixed on the body 12 to cooperate with friction wheels 28, which drive the clamp 11 uncoupled from cable 10 in stations. Such pliers are well known and it suffices to recall that the spring 23 biases the lever 18 anticlockwise, in FIG. 1, in the clamping direction of the jaws 16, 17 on the cable 10. L opening of the clamp 11 is controlled by a downward movement of the roller 20 against the force of the spring 23. This control results from a passage of the clamp 11 under a control ramp 26 which engages the roller 20 The ramps 26 are arranged on the one hand at the entrance to the station. for uncoupling the clamp 11, rolling on the rail 15, from the cable 10 and on the other hand at the outlet for re-coupling the clamp 11 to the cable 10.

Referring more particularly to FIGS. 2 and 3, which illustrate a zone for clutching the clamp 11 at the outlet of the station, it can be seen that the clamp 11 rolling on the rail 15 while being driven by the friction wheels 28, engages by its roller 20 the entry of the ramp 26 in the position 6. The clamp 11 is still closed, but continuing its travel in the direction indicated by the arrow in the figure the roller 20 is moved downwards by the action of the ramp 26 which approaches the rail 15. In position 7 the clamp 11 is open and the cable 10 engages between the jaws 16,17 open. At this position 7 corresponds an inversion of slope of the ramp 26, which progressively deviates from the rail 15 allowing a rise of the roller 20 and a closing of the clamp 11 under the action of the spring 23. In position 8 the clamp 11 is closed and the roller 20 leaves the ramp 26 (position 9). The corresponding variation of the action 29 exerted by the roller 20 on the ramp 26 is shown in Figure 4 and it is understood that this action increases during the compression phase of the spring 23 to then decrease during the closing phase of the clamp 11 and cancel when the roller 20 leaves the ramp 26.

The section 30 of the ramp 26, which extends along the closing area of the clamp 11, is mechanically separated from the other fixed part of the ramp and is carried by load cells 31 measuring the force or the action exerted by the roller 20 on the section 30. It is clear that the entire ramp 26 can be arranged for such a measurement and that it can be performed by other means, in particular a simple balance. In the example illustrated in FIG. 5, the section 30 is mounted to slide upwards, other arrangements being possible.

It can be seen in FIG. 1 that the roller 20 is disposed in line with the spring 23 and that when the roller 20 is in support of the section 30 the force of the spring 20 is directly transmitted to the section 30 with the closest friction, which can be summed up moreover to those of the lever joint 18. As soon as the jaws 16.17 grip the cable 10 the lever 18 is blocked, the roller 20 leaves the section 30 and all the force of the spring 23 is transferred to the jaws 16.17, well heard multiplied in a constant ratio by the lever 18. It is understood that the clamping force of the jaws 16.17 on the cable 10 corresponds exactly to that exerted on the section 30 at the time of separation of the roller 20 from the section 30 with a given weighting factor

The instant of separation of the roller 20 and the section 30 can be deduced from the curve, represented in FIG. 4, from the action exerted on the ramp 26 and more particularly from the point 32 of abrupt variation towards the zero value. A microprocessor or any other automatic device detects this variation as well as the measurement preceding this variation to provide an exact indication of the clamping force of the clamp 11.

By having a conductive track 33 on the bearing face of the roller 20 on the section 30 and by using conductive rollers 20, the mechanical separation causes an interruption of the electrical contact easily detectable and usable to trigger the measurement and possibly an alarm and a installation stopped.

It is clear that the installation according to the invention can use other types of clamps, in particular at two stable positions, the clamp remaining open in the station. In this case, the ramp has only one closing section associated with an unlocking system, which does not affect the measuring device. Likewise, the relationship between the spring force and the cable clamping force is not affected by a more sophisticated lever system.

The measuring device is integrated into the clamp control ramp and does not increase the size of the station. It can easily be added to existing installations, without any modification of the clamps and can be improved to monitor the evolution of the spring force and therefore the state of the clamp.

Claims (8)

1. Transport installation having an aerial continuously running carrier haulage cable (10), in particular a gondola or chair lift, comprising:

   - detachable grips (11) for coupling loads on to the cable, each grip having an operating lever (18) for opening and closing the grip, a spring (23) urging said lever towards the grip (11) closing position and producing the grip clamping force on the cable (10) and a operating element (20) supported by said lever (18),

   - an operating ramp (26) extending along the movable grip (11) trajectory, at a station exit for operating the closing of the grip and its coupling to the cable, said ramp (26) cooperating with said operating element (20) at the passage of the grip,

   - and control means (30,31) of the grip clamping,
   characterized in that the control means comprises a device (31) for continuously measuring the action exerted by said operating element (20) on said ramp (26) and a detector of the moment of the closing of the grip on the cable (10) to provide a measure of said action at this moment.
2. Installation according to claim 1, characterized in that said grip (11) comprises a fixed jaw (16) and a movable jaw (17) rotatably mounted on the fixed jaw and secured to one end of the operating lever (18), the other end of which supporting the operating element (20).
3. Installation according to claim 2, characterized in that the spring (23) acts on said other extremity facing the operating element (20).
4. Installation according to claim 1, 2 or 3, characterized in that a section (30) of the ramp (26), located in the grip (11) closing zone, is independent from the other parts of the ramp and is movably supported by scales (31).
5. Installation according to claim 1, 2, 3 or 4, characterized in that in the grip (11) closing zone said ramp (26) deviates from the grip trajectory, defined by the rail (15), to allow a progressive rotation of the operating lever (18) towards the grip closing position under the spring (23) action, during the advance of the grip and that said operating element (20) separates from the ramp (26) at the grip closing moment.
6. Installation according to any of the preceding claims, characterized in that said detector (33) is devised to detect the separation of said operating element (20) from said ramp (26).
7. Installation according to claim 6, characterized in that said ramp (26) comprises an electric conductive path (33), which extends along the bearing face of the operating element (20), also conductor, to close an electric circuit when the operating element is leaned on the ramp, and to interrrupt this circuit at the moment of the separation.
8. Installation according to any of the claims 1 to 5, characterized in that said detector is devised to detect a sudden variation towards zero of said measure of the action exerted by the operating element (20) on the ramp (26).

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