FR2756798A1 - Cable grip for use on aerial cable car system - Google Patents

Abstract

The device consists of a pair of grips (1), with an operating lever (11) acting on the mobile jaw (7), which is articulated to a fixed jaw (6). such that the operating lever is designed to open and close the grip. A spring (17), with one end anchored to the end of the operating lever, opposite the mobile jaw, and the other end anchored near the fixed jaw, provides the locking force to keep the grip closed on the cable (3). The control mechanism (14), for the locking mechanism, consists of a means of weighing (32), which is guided by the primary rail (36), and supported by a weighing lever (29), which is able to pivot around an axis (D2), which is solid with the extremity (12) of the operating lever. The control mechanism exerts a force on the primary end of the closing spring, which is proportional to the weight carried.

Description

The invention relates to a transport installation using an overhead cable carrying a tractor running continuously and in a loop between two stations, in particular a gondola or a chairlift, comprising disengageable clamps for coupling loads to the cable, each clamp having
- a pair of jaws, enclosing the cable when the clamp is in the closed position
- a control lever for opening and closing the clamp, one of the end parts of this lever forming a movable jaw
- an elastic device for actuating the control lever of the clamp from the open position to the closed position of the clamp.

 Such installations are known in the prior art.

Reference may be made, for example, to the following documents: FR-2,724,357, FR-2,697,056, EP-582,528,
EP-150 701, FR-2 449 011.

An installation according to the invention also comprises
- A control ramp which extends along the path of travel of the clamp and cooperates with said control lever in the passage of the clamp to control the opening of the clamp, the elastic device then being kept under stress; the relaxation of this constraint when the clamp has exceeded the control ramp, causing the clamp to return to the cable clamping position
- a means of measuring the cable tightness by the clamp.

 The effective clamping of the cable by the clamps is one of the essential factors of safety and proper functioning of an overhead cable transport installation, in particular of a gondola and chairlift with detachable clamp, in which the clamps are open at each station entrance and closed at the exit.

 In a first known type of installation of the kind mentioned above, the elastic clamping force is controlled by exerting on the control lever an opposing force, just less than the normal force of opening of the clamp.

 A movement of the control lever, under the action of this lower force, indicates insufficient tightening of the cable by the clamp.

 This first type of installation has the drawback of not ensuring a direct measurement of the clamping force exerted by the jaw on the cable.

 A second type of installation known from the prior art comprises a standard for simulating a cable, on which the clamp is closed to measure the clamping force by sensors incorporated into the standard.

 The implementation of such a device is complex.

 Another known type of installation comprises clamps incorporating a control spring which acts on the clamping spring and causes displacement when the force of this clamping spring drops excessively.

The assembly is incorporated into the clamp and the information must be transmitted to a fixed station.

 Another type of known installation includes optical, inductive or magnetic proximity detectors or even infrared or laser beam detectors enabling the position of one or more reference points of the control lever of the disengageable clamp to be detected.

 The position of these reference points of the control lever of the disengageable clamp makes it possible to deduce the level of deformation of this lever, and therefore the value of the force, of the torque or of the moment of tightening of the disengageable clamp on the cable.

 The level of deformation is compared with threshold values, and the installation is possibly stopped when a crossing of one of said thresholds is detected.

In such a device
- the signal delivered by the detector is a valid indication of deformation of the control lever when the position of the clamp and the section of the cable are perfectly constant and that all the clamps are identical. As these conditions are rarely achieved, it may prove necessary to carry out a second measurement to correct the first and to eliminate parasites, in particular variations in the position of the clamp.
- the presence of snow or grease can disturb the detection of the reference points on the control lever.

 The object of the invention is to provide a simple, direct and reliable device for measuring the force, the torque or the tightening moment of a clamp.

Other objects and advantages of the initiation will appear during the following description of an embodiment given by way of non-limiting example, description made with reference to the accompanying drawings in which
- Figure 1 is a view showing the means of controlling the cable tightening by the clamp, according to an embodiment of the invention
- Figure 2 is a sectional view along the line
Figure 1 AA
- Figure 3 is a detail view of part of the clamp shown in Figure 1;
- Figure 4 is a partial side view of an installation according to the invention.

 In the figures, a disengageable clamp 1 has an elongated body 2 which extends in position coupled to the cable 3 at least, transversely to it.

 The body 2 has an articulation 4 of a hanger 5 directed downwards and itself supporting a load such as a cabin or a seat, for example.

 The body 2 is extended on one side by a pair of jaws 6, 7 together forming a clamping jaw 8 of the cable 3.

 In the embodiment shown, one of the jaws 6 is fixed and the other mobile, the fixed jaw 6 being located inside and the other jaw 7 being turned towards the outside of the clamp 1, the jaws 6, 7 taking the cable 3 over it.

 The jaw 7 is articulated on a longitudinal axis 9 carried by the body 2.

 The clamp 1 can have a structure other than that shown: several cable clamping jaws can be arranged on the same clamp body, on the same side of the body or on opposite sides of the body.

 In the cable clamping position 3 by the jaws 6, 7, the axis 9 extends parallel and above the cable 3.

 The movable jaw 7 is rigidly secured to an end portion 10 of a control lever 11.

 The control lever 11 is rigid, monobloc, of a certain length. It extends and can be struggled during a pivoting on the axis 9, parallel to a plane P substantially perpendicular to the cable 3 and corresponding to the plane of FIGS. 1 and 3.

 At the end portion 12 of the control lever 11, opposite the movable jaw 7, is fixed an axis 13 of rotation of a control roller 14 of the lever 11 and therefore of the movable jaw 7, of general transverse direction, capable of cooperating with a control ramp forming part of the installation.

 The control roller 14 or clutch release roller can be made, for example, of reinforced polyamide.

 The body 2 of the clamp 1 carries rollers 15 for rolling and a cross member 16 for frictionally positioning with which complementary means of the installation can cooperate.

 The rollers 15 and the crosspiece 16 allow the movement of the clamp 1, disengaged from the cable 3 on and along transfer rails forming part of the installation, not shown.

 The control lever 11 is permanently biased in the cable clamping position 3 by at least one compression spring, or more generally an elastic biasing member.

 In the embodiment shown, a pair of springs 17, 17 ', inclined with respect to each other, arranged symmetrically on either side of the plane P ensure, that after the passage of the clutch roller 14 against the control ramp, the control lever 11 returns to the cable 3 tightening position.

 During the passage of the release roller 14 against the control ramp, the control lever 11 is positioned so that the clamp 1 is disengaged, the jaws 6, 7 being separated.

 In the embodiment shown, one end of the springs 17, 17 'or of the adjoining supports is articulated to the body 2 of the clamp on the side of the jaws 6, 7.

 The other end 18, 18 'of the springs 17, 17' is articulated on the control lever 11 near the clutch release roller 14.

 In FIG. 1, the declutching roller 14 has left the control rail and the cable 3 is clamped between the jaws 6, 7 under the action of the springs 17, 17 '.

 The clamp 1 is guided by transfer rails during the passage of the seats of a chairlift, of a cabin of a gondola, at the embarkation or disembarkation stations.

 A description will now be given of the means for measuring and controlling the cable clamping force 3 by the disengageable clamp 1.

 Each end 18, 18 'of the springs 17, 17', opposite the clamping jaw 8 is supported on a part 19, 19 'in the form of a cup comprising a lower ball joint 20, 20'.

 Each end 18, 18 'of the springs 17, 17' opposite the clamping jaw 8 bears on an external annular projection 21, 21 'of the part 19, 19', this projection 21, 21 'forming the edge of a cavity 22, 22 'containing the lower ball joint 20, 20'.

 We will now describe only the arrangement on the side of one of the springs 17, 17 ', which will be said for the side of the spring 17 applied symmetrically for the part of the device located on the side of the spring 17' ( see figure 2).

 The clamp 1 comprises a part 23 ball joint support comprising an upper ball 24 cooperating with the lower ball 20.

 The ball joint support part 23 also comprises, opposite the upper ball joint 24, a piston 25.

 The piston 25 forms a bearing surface for a ball 26.

 The control lever 11 supports the control or declutching roller 14, mounted so that it can rotate about an axis 13 at the end 12 of the lever 11 opposite the clamping jaw 8.

 A part 29 forming a weighing lever is mounted so as to be able to rotate about an axis D2.

 In the embodiment shown, two parts 29 are provided, on either side of the clutch release lever 14.

 These two parts 29 are connected by a weighing cross member 30 comprising a central through hole 31.

 This through hole has an axis 28, axis of rotation of a weighing roller 32.

 The weighing roller 32 can be made of reinforced polyamide, for example.

 The weighing roller 32, its axis and its sheath are integral with the weighing levers 29, the assembly thus formed being movable in rotation about the axis D2.

 During this rotation, anticlockwise in FIG. 1, the weighing levers 29 compress the springs 17, 17 ′ by means of the balls 26, of the piston 25, of the ball joint 24, of the ball joint 20 and the cup 19.

 A corresponding position of the weighing roller 32 is shown in dotted lines in FIG. 3.

 The weighing levers 29 comprise a cylindrical stop 33 coming into contact with the end part 12 of the lever 11 when the weighing levers 29 are not rotated along the axis D2.

 The articulation support 27 has a through hole with an axis 13.

 This articulation support 27 carries the articulation of axis D2 and is oscillating with respect to axis 13.

 We will now describe the means allowing the rotational movement around the axis D2 of the assembly formed by the parts 29, 30 and 32.

 The rollers 14 and 32 pass through a gutter defined by a control rail 35 and a counter rail 36.

 The counter rail 36 comprises a part 37 substantially parallel to the control rail 35 and disposed opposite and above the latter.

 The declutching roller 14 rolls on the part 37 of the counter rail 36 while the weighing roller 32 rolls on the control rail 35.

 The assembly formed by the control rail 35 and the counter rail 36 may include two zones.

 In a first zone, the spacing of the control rail 35 and of the counter rail 36 is constant so that the weighing roller 32 is not substantially stressed in rotation about the axis D2.

 This first zone is in continuity with the control ramp of the clutch release roller 14.

 The diameter of the cable 3 can vary over the length of the cable 3, for example under the effect of the tension exerted on this cable 3.

 So that the position of the control lever 11, at the outlet of the control ramp, the clamp tightening the cable 3, is not perfectly fixed.

 Depending on the diameter of the cable 3, the lever 11 will rotate more or less anticlockwise according to FIG. 1.

 So that at the output of the control ramp, the position of the clutch release roller 14 and the weighing roller 32 is not perfectly fixed and may vary from clamp to clamp.

 The first part of the control rail 35 corresponding to the end of the control ramp, the clamping force measurement system can overcome variations in the position of the rollers 14, 32 as a result, for example, of variations in diameter cable 3.

 In a second zone, the spacing of the control rail 35 and the part 37 of the counter rail 36 is variable, the control rail being for example articulated or flexible.

 The means for measuring the reaction force to the force exerted by the weighing means are coupled at the output of the control ramp.

 In a first embodiment, the control rail 35 is articulated and a calibrated force means exerts a force tending to decrease the distance between the control rail 35 and the part 37 of the counter rail 36.

 So that during the passage of the clamp in the rail 35 against rail 36 assembly, the weighing roller 32 rotates around the axis D2, which urges the springs 17, 17 in compression, that is to say in a direction corresponding to the opening of the clamp.

 The clamp 1 is however still in the cable clamping position 3.

 The control can be all or nothing.

 In other words, it is possible to detect the appearance or not of a displacement of the weighing roller 32 under the influence of the force exerted by the force means on the control rail 35.

 The control can also incorporate a measurement of the displacement of the weighing roller 32.

 In all cases, the force applied to the weighing roller 32 is correlated to the force applied to the springs 17, 17 '.

 In one embodiment, the measurement means comprise at least one strain gauge applied to the lower control rail coupled to a device measuring the deformation of the rail.

 The compression resistance of the springs 17, 17 ′ is thus measured when the clamp 1 is in the cable clamping position 3.

 In a second embodiment, the control rail 35 is articulated or flexible and is placed at a distance from the counter rail 36 such that the rollers 14 and 32 must pass through a narrowing.

 Weighing means make it possible to measure the force exerted on the weighing roller 32 when the latter is rotated around D2, in the anticlockwise direction in FIG. 1, due to the narrowing of the passage existing between the control rail 35 and the counter rail 36.

 Here again, the control can be of the all or nothing type.

 In other words, the spacing between the control rail 35 and the counter rail 36 can be chosen such that the appearance or not of the rotation of the weighing roller 32 around the axis D2 is detected.

 The control can also incorporate a measurement of the force applied to the roller 32, that is to say a measurement of the compressive strength of the springs 17, 17 ′ in the cable clamping position 3.

 In one embodiment, the measuring means comprise at least one calibrated spring applying a determined force on the lower rail, corresponding substantially to the force exerted by the weighing means, coupled to a device for validating the measurement.

 The device can overcome the progressive wear of the rollers 14 and 32.

 The control rail 35 and the counter rail 36 are brought into position by the rollers 14 and 32 of the clamp 1, so that account is taken of the differences in position of the rollers 14 and 32 at the output of the control ramp 39, differences in position linked for example to cable cross-section differences.

 For example, in the case where the mobile part of the control rail 35 defines a constriction on the passage of the rollers 14, 32, a device can apply a constant force to this mobile part, a displacement sensor making it possible to measure the force applied roller 32.

 FIG. 4 illustrates the means allowing the rotational movement around the axis D2 of the assembly formed by the parts 29, 30 and 32.

 In this partial side view of an installation according to the invention, a clamp 1 is shown in a position for passage of the roller 14 against the declutching ramp 39.

 The dotted circles correspond to the positions of the rollers 14 and 32 in three successive locations of the clamp 1, movable in the direction A, the rolling rollers 15 cooperating with the rolling rail 40.

 The assembly formed by the counter rail 36 and the control rail 35 is mounted mobile around a ball joint R.

 The control rail 35 is articulated and a calibrated force means 41 exerts a force tending to decrease the distance between the control rail 35 and the part 37 of the counter rail 36.

 The rollers 14 and 32 must pass through the constriction 42 during the passage of the clamp 1.

 Weighing means 43 make it possible to measure the resistance force of the springs 17, 17 ′, expressed during the rotation around D2 of the weighing roller 32.

 The device can incorporate means for signaling and / or stopping the movement of the clamps 1 if a predetermined value of the position of the weighing roller 32 and / or of the force exerted by this roller 32 on the rail 35 is reached. A safety factor may be provided, if necessary.

 The description which has just been made relates to a clamp provided with two compression springs 17, 17 '.

 It is understood, however, that the invention also relates to the case where the clamp is provided with a single spring or with more than two springs.

 The great symmetry of the embodiment shown in the case of a clamp with two springs, arranged symmetrically with respect to the plane P of FIG. 1 allows easy transposition in the case where the clamp has only one spring.

Claims (6)

CLAIM8  1. Installation of tansport with aerial cable carrying tractor continuously scrolling, in particular a cable car or chairlift comprising:  - at least one clamp (1) of the type comprising a disengageable device for coupling a load to the cable (3), the clamp (1) having an actuating lever (11) of a movable jaw (7) articulated around a fixed jaw (6) for opening and closing the clamp (1), at least one spring (17, 17 '), a first end of which is anchored to the end of the lever (11) opposite the movable jaw (7) and a second end of which is anchored in the vicinity of the fixed jaw (6), providing the clamping force of the clamp (1) on the cable (3), and a control member carried by the lever (11 ),  a control ramp extending along the path of travel of the clamp (1) and cooperating with the control member (14) in the passage of the clamp (1), and  means for controlling the clamping of the clamp,  characterized in that the control ramp comprises:  - a first upper rail (36) constituting a raceway and guide for the control member (14) and a second lower control rail (35),  the means for controlling the clamping of the clamp (1) comprising:  - a weighing means (32) guided by the first rail and supported by a weighing lever (29) pivoting about an axis D2 secured to the end (12) of the lever (11) opposite the movable jaw (7) , and exerting a force on the first spring end (17, 17 ');  - Means for measuring the reaction force to the force exerted by the weighing means (32) during its passage inside the control ramp, coupled to the second lower control rail (35).  2. Installation according to claim 1, characterized in that the control member comprises at least one declutching roller (14) movable in rotation about its axis, and fixed to the lever (11) by its end opposite the movable jaw ( 7), and in that the weighing means comprises at least one weighing roller (32) movable in rotation about its axis; the axis of rotation (28) of the weighing roller (32) being offset relative to the axis (13) of the declutching roller (14) so that only the declutching roller (14) rests on the first rail ( 36) and that only the weighing roller (32) rests on the second rail (35).  3. Installation according to any one of claims 1 and 2, characterized in that the measuring means comprise at least one strain gauge applied to the lower rail (35) control coupled to a device measuring the deformation of the rail.  4. Installation according to any one of claims 1 to 3, characterized in that the measuring means comprise at least one calibrated spring applying a determined force on the lower rail (35) corresponding substantially to the force exerted by the weighing means (32), coupled to a measurement validation device.  5. Installation according to any one of claims 1 to 4, characterized in that the weighing means (32) further comprises a ball (26) disposed between the free end of the weighing lever, opposite the axis of rotation (28) of the weighing roller (32), and a piston (25) arranged inside a cup (19) whose upper part in the form of a collar holding the spring (17, 17 ') compressed, is mechanically coupled to the end (12) of the lever (11) opposite the movable jaw (7).  6. Installation according to any one of claims 1 to 5, characterized in that the measurement means are coupled at the output of the control ramp.