AU2019410026A1 - Fall-prevention device for motor-driven rack and pinion elevator - Google Patents

Abstract

The invention concerns a fall-prevention device for an elevator capable of being moved along a rack of an elevator mast, the fall-prevention device being characterised in that it comprises a frame (30), a lever (31), a roller (32) pivotally connected with the lever and attached to a first end of the lever, the roller being capable of rolling on a smooth side of the rack, a stop (33) attached to a second end of the lever, the stop comprising a toothed portion (334) capable of cooperating with a toothed face (221) of the rack and being connected to the frame by means of a compression spring (330), and at least one damper (34) arranged on a top portion of the fall-prevention device, the fall-prevention device being moreover characterised in that it is slidingly connected with the elevator.

Description

FALL-PREVENTION DEVICE FOR MOTOR-DRIVEN RACK AND PINION ELEVATOR

Technical field The invention relates to the field of elevators. More particularly, the invention relates to a safety device for preventing the fall of an elevator during negative, i.e. downwards, telescoping and detelescoping operations of the elevator mast. The invention can be applied in particular to the field of elevators used for descents.

Prior art The telescoping of an elevator mast is performed by placing mast modules on top of one another or below one another. Depending on the configuration, the mast may be assembled from top to bottom, i.e. from a top end of the mast to a bottom end of said mast, in which case this is referred to as negative telescoping, or downwards telescoping, or conversely from bottom to top, in which case this is referred to as positive telescoping, or upwards telescoping. The downwards travel of the car is limited by a mechanical stop fitted onto the mast. This stop is removed for the telescoping or detelescoping of the mast and remounted before use. Detelescoping is defined as a disassembly of the mast. Thus, during negative telescoping, the downwards travel of the car is not limited. There is therefore a risk that the car will fall, in the event for example of a malfunction of the existing safety systems, such as a parachute for example which is designed to activate on the detection of an excessive speed of the car, or an electrical mast end detector designed to electrically stop the elevator when said detector, placed at the bottom part of the elevator, no longer detects the mast supporting the elevator. Braking systems for slowing down an elevator in the event of excessive speed are known from the prior art. For example, American patent US 7 849 972 discloses an emergency braking device comprising two wedges which can each be brought into contact with a guide rail of the elevator by means of two pivoting members. When the speed of the elevator exceeds a first threshold greater than a nominal speed, an elevator braking device is engaged; when the speed of the elevator exceeds a second threshold greater than the first - i.e. the braking device is not capable of braking the elevator - the emergency device is engaged and the wedges are moved into contact with the rails to brake the elevator car by friction. The movement of the pivoting members, and therefore the contact of the wedges with the guide rails, are controlled by an electromagnetic actuator according to the speed of the elevator. A disadvantage of such braking devices is that they can slow down the elevator but not stop it, so that it is still possible that the elevator may fall. Chinese patent application CN 103523630 discloses a safety device for an elevator designed for assembling a crane pillar assembled by placing mast elements on top of one another by means of lifting equipment. When a certain number of mast elements are installed from the ground, thus forming a base, the car is installed along this base by means of guide elements. Further mast elements are then installed by the lifting equipment. In the absence of such equipment, or when the size of the mast becomes greater than the maximum lifting height of the equipment, lifting is carried out by means of a hook arranged above the elevator car, which ascends along the mast elements already in place. The safety device described in this prior art prevents the car from moving out of the guide elements which could occur if the car travels too far. The device comprises a switch formed essentially by a rod positioned and maintained at a given distance above the car, and in contact with the mast, so that the contact between the switch and the mast is interrupted before the coach leaves the guide elements. The switch is electrically connected to a drive unit of the elevator, so that before the car reaches the top of the mast, the contact between the switch and the mast is interrupted and the drive unit is de-energised, causing the car to stop its ascent, preventing the car from leaving the guide elements. Such a safety device makes it possible to stop the car to prevent it from leaving the guide elements, but it is suitable for cars traveling in an upwards direction and not in a downwards direction.

Description of the invention The invention relates to a fall-prevention device capable of shifting from an disengaged configuration to an engaged configuration for preventing the fall of an elevator capable of being moved along a rack of an elevator mast. According to the invention, the fall-prevention device comprise a frame, a lever, a roller in pivot connection with said lever and fixed to a first end of said lever, said roller being capable of rolling on a smooth face of the rack, a cleat fixed to a second end of said lever, said cleat comprising a toothed part capable of cooperating with a toothed face of the rack and being connected to the frame by means of a compression spring, and at least one shock absorber arranged on an upper part of said fall-prevention device. The fall-prevention device according to the invention is also in sliding connection with the elevator.

In one embodiment, the fall-prevention device according to the invention comprises a counter-rack roller capable of rolling along the smooth face in a disengaged configuration and capable of bearing on said smooth face in an engaged configuration. In one embodiment, a toothing of the toothed part of the cleat and a toothing of the toothed face of the rack have the same pressure angle, which pressure angle is equal to a guide angle of the cleat formed by a direction of extension of the cleat with a direction of extension of the teeth of said cleat. In one embodiment, the fall-prevention device comprises at least one unlocking means to enable the shift of said fall-prevention device from the engaged configuration to the disengaged configuration. In one embodiment, the at least one unlocking means comprises an unlocking screw, an unlocking nut and a guiding body of said screw. In one embodiment, the at least one unlocking means comprises an actuator. The invention also relates to an elevator comprising a fall-prevention device according to the invention. The invention also relates to an assembly composed of an elevator according to the invention and an elevator mast comprising a rack, the elevator further comprising at least one pinion designed to cooperate with said rack to enable a movement of said elevator along said rack, the fall-prevention device of the elevator being capable of cooperating with the rack.

Brief description of the drawings

[Fig. 1A] represents an elevator installed on a mast in a configuration in which the car of the elevator is fully placed on the mast.

[Fig. 1B] represents an elevator installed on an elevator mast in a configuration in which the car is fully descended below an altitude of the lower end of the mast.

[Fig. 2A] represents the drive unit of the elevator in a front view.

[Fig. 2B] represents the drive unit of the elevator in a rear view.

[Fig. 3A] represents a front view of the fall-prevention device according to the invention, installed on the elevator, in a disengaged configuration with cover.

[Fig. 3B] represents a front view of the fall-prevention device according to the invention, installed on the elevator, in a transitory engaged configuration, without cover.

[Fig. 3C] represents a front view of the fall-prevention device according to the invention, installed on the elevator, in an engaged configuration, with cover.

[Fig. 4] represents a rear view of the fall-prevention device according to the invention, in an engaged configuration.

[Fig. 5] represents a perspective view of the fall-prevention device according to the invention.

[Fig. 6] represents a detailed view of the toothings of the rack and the fall-prevention device according to the invention. Detailed description With reference to figures 1A and 1B, an elevator 1 comprising a car 10 and a drive unit 11 is installed on a mast 2 in the process of negative telescoping. The mast 2 is composed of an assembly of mast modules 20 of substantially square cross-section and assembled from top to bottom. The installation of one mast module 20 underneath another mast module is performed by placing the elevator in a low position in which a low floor 100 of the car 10 is moved down to an altitude lower than a lower end 21 of the mast while being assembled, or telescoped. The lower end 21 is suspended, i.e. it is not in contact with the ground, a distance between the ground and the lower end 21 being generally greater than a height of the elevator. An elevator is defined as a device for transporting people or loads in a vertical direction corresponding to a direction of travel of the elevator along the mast. An elevator may be for example a lift or a hoist. The elevator 1 is able to move along the mast 2 in an ascending direction or in a descending direction, by means of a rack and pinion system comprising at least one pinion 114 associated with the elevator 1 and a rack 22 associated with the mast 20. The elevator 1 is set in motion along the mast 2 by the drive unit 11 which comprises in particular a motor assembly 110 driving at least one pinion 114, and a parachute 111 designed to brake the elevator in the event of excessive speed. "Excessive speed" is defined as a speed of descent which is greater than a maximum nominal operating descent speed of the elevator. With reference to figures 2A and 2B, the drive unit 11 also comprises two mechanical stops 112 capable of coming into contact with a low mechanical stop placed a few tens of centimetres from the lower end 21 of the mast 2, thus making it possible to prevent the elevator 1 from descending too low, thus preventing the removal of the at least one pinion from the rack and a fall of the elevator. However, in the absence of the bottom stop, the travel of the elevator is not limited and there is therefore a risk of the elevator falling. This is the case for example when the bottom stop is removed to install an additional mast module 20. A fall-prevention device 3 according to the invention makes it possible to limit or even prevent the risks of falling in the absence of a bottom mechanical stop. The fall-prevention device 3 is placed in a rectangular recessed portion 115 of a lower part of the drive unit 11.

With reference to figures 3A, 3B, 3C and 5, the fall-prevention device 3 according to the invention comprises a frame 30, a lever 31, a roller 32, a cleat 33 and two shock absorbers 34. The lever 31 is pivotably connected 310 to the frame 30 about a connecting axis substantially perpendicular to a face of the mast 2 along which the elevator is displaced. The roller 32 is integral with a lower end of the lever 31 and in pivotal connection with said lever, along a connecting axis substantially parallel to the connecting axis of the pivotal connection 310 between the lever 31 and the frame 310. The roller 32 is placed on an inner face of the lever 31, said inner face corresponding to a face oriented towards the mast, such that said roller is able to roll on a smooth face 220 of the rack 22 opposite a toothed face 221 of said rack. The cleat 33 is integral with a top end of the lever 31 and connected to said lever by a shaft 333, and is fixed relative to said lever. The cleat 33 is placed on the inner face of the lever 31, such that a toothed portion 334 of said cleat is able to cooperate with a toothed face 221 of the rack 22. A compression spring 330 connecting the frame 30 to the cleat 33 exerts a force for moving said cleat towards the rack. A cover 331 is fixed to the frame 30, for example by means of screws. The cover 331 has a substantially oblong guide hole 332 for guiding the shaft 333 connecting the cleat 33 to the lever 31 and allowing a rotation of this assembly about the pivot connection 310. The cover 331 contributes together with the frame 30 to ensuring the guiding of the cleat 33 when said cleat is driven by the lever 31. In particular, the cover 331 provides lateral guiding of the cleat 33. With reference to figure 5, a guide track 335 of the frame 30 ensures with the cover 331 the guiding of the cleat 33. The guide track 335 is welded to the rest of the frame 30, and has a U-shaped cross-section. The guide track 335 extends in the same direction of extension as the direction of extension of the cleat 33. The fall-prevention device 3 is in sliding connection with the drive unit 11 of the elevator. The sliding connection between said device and said drive unit allows a relative translational movement of one of these two elements along a vertical axis with respect to the other element. With reference to the figures, the sliding connection is ensured by the presence on the frame 310 of four oblong holes 300, in each of which a pin 113 of the drive unit 11 is inserted. The shock absorbers 34 are fixed to an upper part of the frame 30 of the fall prevention device, by fixing means, for example of the screw/nut type. In the example illustrated in the figures, the shock absorbers 34 have a substantially cylindrical form. The operation of the fall-prevention device is described in detail in the following.

In a disengaged configuration of the fall-prevention device 3, illustrated in figure 3A, the roller 32 is in contact with the smooth face 220 of the rack 22 and is capable of rolling along said smooth face during the movement of the elevator. The moment created by the force exerted by the spring 330 on the cleat 33, around the linkage axis of the pivot connection 310, is compensated by the moment created by the reaction force of the rack on the roller 32 around this same axis. Thus, the lever 31 is substantially immobile and the cleat 33 does not cooperate with the rack 22, such that the fall-prevention device 3 does not oppose a movement of the elevator 1 and accompanies the movement of the elevator as a result of the roller 32 rolling along the rack. If the elevator descends sufficiently, the roller 32 is caused to leave the rack, as illustrated in figure 3B showing a transitory engagement configuration of the fall-prevention device. As soon as the contact between the roller and the rack is interrupted, the moment created by the force exerted by the spring 330 on the cleat 33, about the linking axis of the pivot connection 310, brings said cleat into contact with the rack, such that the teeth of the toothed portion of said cleat cooperate with the toothed face 221 of said rack, thus immobilising the fall-prevention device with respect to the rack 22. The fall-prevention device 3 is then in an engaged configuration. Therefore, the descent of the elevator is limited. Indeed, the elevator can continue to descend, due to the sliding connection between the drive unit and fall prevention device, until the drive unit 11 comes into contact with the shock absorbers 34 placed on an upper part of the fall prevention device, which shock absorbers are then compressed such that they brake the descent of the elevator until the elevator comes to a complete stop. A length of the oblong holes 300 is advantageously equal to a length of a shock absorber, so that the stroke of the pins 113 is not limited during the braking phase of the elevator, or compression of the shock absorbers, leading to the complete stop of the elevator. The teeth of the rack 22 and the teeth of the cleat 33 have the same pressure angle. With reference to figure 6, a pressure angle a is defined as the angle formed by the slope of the teeth relative to a direction of extension of said teeth, horizontal in this case. A guide angle o of the cleat 33, which angle is formed by the direction of extension of the cleat 33 with the horizontal direction of extension of the cleat teeth, is substantially equal to this pressure angle, which allows on the one hand an optimal engagement between the teeth of the rack 22 and the teeth of the cleat 33, the directions of extension of the teeth remaining parallel during the displacement of said cleat, and on the other hand compensation for the horizontal force exerted by the rack on the cleat due to the weight of the elevator and the pressure of the teeth of the rack on the cleat, thus preventing the cleat from being moved away from the rack.

A counter-rack roller 35, illustrated in figure 2B as well as figure 4, takes up a thrust force exerted by the cleat 33 on the rack 22 due to the weight of the elevator 1 resting on the fall prevention device, in order to prevent damage to the rack. The counter-rack roller 35 is a roller in pivotal connection with the frame 30 of the fall-prevention device, capable of rolling on the smooth face of the rack in the disengaged configuration, and coming to bear against the smooth face of the rack in the engaged configuration, in which it is substantially immobilised with respect to said frame. In order to return the device to the disengaged configuration, it is first necessary to raise the elevator 1 slightly in order to decompress the shock absorbers 34. The fall-prevention device 3 is then no longer supporting the weight of the elevator 1. The fall-prevention device 3 is then unlocked by means at least one unlocking means comprising a guiding body 36, an unlocking screw 37 and an unlocking nut 38. Once the shock absorbers 34 are decompressed, the unlocking screw 37 is inserted into the guiding body 36 in the form of an L projecting from the frame 30. The locking nut 38 is typically placed on a threaded portion of the unlocking screw. The unlocking screw abuts against the lever 31, such that screwing in the unlocking screw counteracts the action of the spring 330 on the cleat 33 by exerting a force on the lever opposing the action of said spring. The cleat 33 is thus disengaged from the rack 22 and the lever 31 is caused to pivot so as to set the roller 32 back from the rack. Thus the fall-prevention device 3 is no longer immobilised relative to the rack, and said device and the elevator can be raised until the roller 32 reaches an altitude at least equal to that of the lower end 21 of the mast 2. The unlocking screw is then unscrewed, possibly removed, in order to allow the roller 32 to return into contact with the rack, by the action of the spring 330 on the cleat, and therefore on the lever. Such a method of returning to the disengaged configuration is carried out manually. With reference to figure 4, in an alternative embodiment, the return to the disengaged configuration is performed automatically. When the elevator 1 is raised by the motors of the drive unit, the shock absorbers 34 decompress and under the effect of the vertical force directed upwards and combined with the pressure angle and the guide angle of the cleat, the cleat 33 disengages from the rack 22. When the roller 32 comes into contact with the lower end of the rack, corresponding substantially in altitude to that of the lower end 21 of the mast 2, the teeth of the rack 22 and the cleat 33 are in contact at their apexes. The release of the cleat from the rack has allowed the lever 31 to pivot such that an axis of rotation of the roller 32, corresponding to its pivot connecting axis, is set back from the smooth face, as illustrated in figure 4. In this way, when the elevator is ascending, a force is applied by the rack on the roller allowing the lever to pivot slightly to enable said roller to engage with the smooth face of the rack, to return the fall-prevention device 3 to its disengaged configuration. It should be noted that a length of the lever 31 and a diameter of the roller 32 have to be adapted so that said roller is in contact with the lower end of the rack at the moment when the cleat and said rack are almost entirely disengaged from one another and in contact only at the apexes of their teeth. The length of the lever 31 determines the horizontal and vertical position of the rotational axis of the roller 32. This axis has to be horizontally remote from the plane passing through the smooth face of the rack 22, towards the outside of the rack 22. In the example shown, the rotational axis is at a distance of 11 mm, in a horizontal plane, from the smooth face of the rack 22. The vertical position vertical is related to the diameter of the roller which must be sufficient to come into contact with a low edge of the smooth face of the rack during the ascent, and allow a clearance between the roller and said low edge when the teeth of the rack 22 and the cleat 33 are in contact at their apexes, such a clearance making it possible to avoid damage to the fall-prevention device or the elevator when returning to the disengaged configuration. In the example shown, the diameter of the roller 32 is 70 mm. Of course, the invention is not limited only to the embodiments described here. For example, the number of shock absorbers 34 as well as their mechanical features may vary, in particular these shock absorbers are dimensioned as a function of the weight to be damped and the impact speed. In the same way, other means of unlocking are possible, for example a actuator.

The invention has a particular application in the field of elevators used for descending underground. A gallery or vertical shaft which allows access for mining operations is referred to as a "descent".

Claims (8)

1. Fall-prevention device (3) capable of shifting from a disengaged to an engaged configuration to prevent the fall of an elevator (1) which is capable of being moved along a rack (22) of an elevator mast (2), said fall-prevention device being characterised in that it comprises a frame (30), a lever (31), a roller (32) pivotably connected to said lever and fixed to a first end of said lever, said roller being capable of rolling on a smooth face (220) of the rack (22), a cleat (33) fixed to a second end of said lever, said cleat comprising a toothed portion (334) able to cooperate with a toothed face (221) of the rack (22) and being connected to the frame by means of a compression spring (330), and at least one shock absorber (34) arranged on an upper part of said fall-prevention device, said fall prevention device also being characterised in that it is in sliding connection with said elevator.

2. Fall-prevention device (3) according to claim 1 characterised in that it comprises a counter rack roller (35), said counter-rack roller being capable of rolling along the smooth face in a disengaged configuration and being capable of bearing on said smooth face in an engaged configuration.

3. Fall-prevention device (3) according to claim 1 or claim 2, characterised in that a toothing of the toothed part (334) of the cleat (33) and a toothing of the toothed face (221) of the rack (22) have the same pressure angle (a), which pressure angle is equal to a guide angle (o) of the cleat (33) formed by a direction of extension of the cleat (33) and a direction of extension of the teeth of said cleat.

4. Fall-prevention device (3) according to any of the preceding claims, characterised in that it comprises at least one unlocking means for enabling the shift of said fall-prevention device from the engaged configuration to the disengaged configuration.

5. Fall-prevention device (3) according to claim 4, characterised in that the at least one unlocking means comprises an unlocking screw (37), an unlocking nut (38) and a guiding body (36) for said screw.

6. Fall-prevention device (3) according to claim 4, characterised in that the at least one unlocking means comprises an actuator.

7. Elevator (1) comprising a fall-prevention device (3) according to any of the preceding claims.

8. Assembly composed of an elevator (1) according to claim 7 and an elevator mast (2) comprising a rack (22), the elevator (1) also comprising at least one pinion (114) designed to cooperate with said rack to enable movement of said elevator along said rack, the fall prevention device (3) of the elevator (1) being able to cooperate with the rack (22).