Brake mechanism for device for hauling up/down by rope

A brake mechanism for a device for hauling up/down by rope, in particular one for the safe hauling up and down by rope of persons and loads. The device has a pulley which preferably has a back stop that prevents the pulley from turning during the roping down. The rope brake mechanism has a rope speed measuring device that cooperate with a rope brake, which acts upon the rope to exert a braking force onto the rope when the rope speed increases above a maximum predetermined speed.

CROSS-REFERENCE TO RELATED APPLICATION
 This application claims the priority of European Patent Application No.
 97810359.6 filed Jun. 9, 1997, the subject matter of which is incorporated
 herein by reference.
 BACKGROUND OF THE INVENTION
 The present invention relates to a brake mechanism for a device for hauling
 up/down by rope, in particular one for the safe hauling up and down by
 rope of persons and loads. The device has a pulley which preferably has a
 back stop that prevents the pulley from turning during the roping down.
 In accordance with the European published patent EP-A-0 480 117 by the
 applicant, such devices for hauling up/down by rope are preferably used
 for hauling persons or loads up and down on a rope. The preferred area of
 application is for rescue services or in general as mobile equipment. The
 devices for hauling up/down by rope essentially function to reduce the
 retaining force during the roping down in connection with a safety to
 prevent an uncontrolled dropping of the person or load attached to the
 rope.
 These known devices for hauling up/down by rope have a large-volume pulley
 equipped with a back stop. In most cases, a rope is placed with 2.5
 windings around this pulley. The device is operated such that when pulling
 up, the pulley is running freely and represents only a low resistance.
 During the roping down, on the other hand, the pulley is blocked by the
 back stop and the rope slides over the surface of the pulley. The
 resulting friction takes over a large portion of the load attached to the
 rope.
 As a safeguard during the roping down, the International Patent Application
 WO-A-9 717 107 suggests providing a self-activating rope stop on the pull
 side of the device for hauling up/down by rope. The advantage of this
 arrangement is that the rope stop only needs to take over a portion of the
 load since the device for roping up/down accepts the largest portion of
 the pull.
 However, the disadvantage of this solution is that upon reaching the
 critical roping down speed, the roping down operation is stopped
 completely. In particular if a roping down speed near the permissible
 limit, e.g. 2 m/s, is required, a brief exceeding of this speed limit can
 trigger the stopping of the rope.
 SUMMARY OF THE INVENTION
 It is the object of the present invention to specify a device, which
 prevents an increase in the roping down speed above a predetermined limit
 value during the roping down operation.
 In accordance with the present invention, the rope brake mechanism
 comprises rope speed measuring means that cooperates with a rope brake,
 which acts upon the rope to exert a braking force onto the rope when the
 rope speed increases above a maximum predetermined speed.
 A brake mechanism is installed on the pull side of a device for hauling
 up/down by rope, which mechanism forces the engagement of a frictional
 brake on the rope, preferably only during the roping down, if a
 predetermined rope speed is exceeded. In particular, the brake mechanism
 increases the braking effect of the frictional brake with increasing rope
 speed, so that the roping down speed does not reach an unacceptable,
 uncontrollable speed, even for heavy loads.
 The present invention relates to a device for raising and lowering a load,
 and the device includes a pulley and a brake mechanism. A rope is wound
 about the pulley, and the brake mechanism acts upon the rope to exert a
 braking force on the rope when the rope speed increases above a maximum
 predetermined speed. The break mechanism includes at least two flyweights
 and at least one bearing surface. The rotatable arrangement of flyweights
 is operatively connected to the pulley and rotates about an axis in
 response to rotation of the pulley. The bearing surface is operatively
 connected to the flyweights and is movable against the rope in response to
 rotation of the flyweights. When the pulley is rotated, the centrifugal
 force exerted on the flyweights is transferred axially to the bearing
 surface, which causes an increased braking effect on the rope. The braking
 effect increases with increasing rotational speed.
 The flyweights surround a rotatable core in a symmetrical arrangement, and
 from the core originates a radial guide means. The radial guide means
 holds the flyweights such that they can be moved radially. The arrangement
 of flyweights is surrounded peripherally by a spring-elastic element,
 which biases the flyweights toward the core. In addition, a frictional
 wheel bears against the rope and is linked to the flyweights, and a gear
 is arranged between the frictional wheel and the flyweights in order to
 establish a gear ratio, as well as a rotational link.
 The rope moves through an essentially tube-shaped rope guide proximate the
 pulley, and the width of the rope guide can be changed. The rope guide
 includes convexities and concavities to force the rope into an
 increasingly S-shaped course during the reduction of the width so as to
 increase the braking effect on the rope. At least a section of the rope
 guide is movable so as to allow the change in width for the rope guide,
 and the movable section can be moved by a coupling means. The coupling
 means include contact zones that are angled relative to the rotational
 axis of the flyweights to convert radial movement of the flyweights to a
 movement of the coupling means directed along the rotational axis.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
 The design of the actual device for hauling up/down by rope corresponds to
 the design described in the WO-A-9 717 107, the subject matter of which is
 incorporated into the description by reference.
 FIG. 1 shows a rope brake mechanism 1 according to the invention on a
 device 2 for hauling up/down by rope, e.g. a device according to the
 WO-A-9 717 107. The rope brake mechanism 1 comprises a frictional wheel 3
 with knurled running surface, which is pressed against a rope 4. The
 frictional wheel 3 moves in roping up 5 direction as well as roping down 6
 direction. The pull end 7 of the rope passes through a rope guide 8 (see
 FIG. 2), which consists of two jaws 9, 10, having an essentially
 mirror-inverted design (FIG. 3). The stationary jaw 9 in this case is
 fixedly connected to the housing 11, while the other jaw 10 can be moved.
 In the position shown here, the two jaws 9, 10 are pushed by a spring 12
 into the opened resting position. In this position, the guide 8 is opened
 to the maximum and has the largest cross section, so that the rope 7
 essentially glides without resistance through the guide.
 The jaws 9, 10 are held on the one hand by a fixed cone 13 or a cone 15
 that can be displaced along the axis 14 and is coupled with the
 centrifugal unit 16 while, on the other hand, the jaws are secured against
 turning by a screw 17. A bolt 18 with internal thread is screwed onto the
 screw 17, which bolt extends through the bore at the back end of the brake
 jaws 9, 10, near the plateaus 19, and has a slightly conical shape to
 allow a movement of the brake jaw 10. During the braking operation, the
 movable jaw 10 tilts slightly over the front edges of the plateau if the
 movable cone 15 is moved by the centrifugal unit in the direction of the
 fixed cone 13.
 The centrifugal unit 16 consists of the frictional wheel 3, inside of which
 a shaft 20 is positioned such that it can rotate. A planet pinion 21 fits
 on the outer end of shaft 20 and meshes with a fixed toothed ring 22 with
 internal toothing. An additional, inside planet pinion 23 fits on the
 other end of the shaft 20 and meshes with the central gear 24. This planet
 pinion 23 is attached to the shaft 20 by means of a freewheel mechanism
 25. The freewheel mechanism blocks during the roping down, so that the
 center gear 24 is put in motion via the frictional wheel 3 and the planet
 gear, consisting of toothed ring 22 and the toothed gears 21 and 23.
 In roping up direction, the freewheel mechanism 25 uncouples the two
 toothed gears 21 and 23, so that the center gear 24 is not driven and the
 frictional wheel can move freely, without problems and at any speed
 without causing a braking of the rope.
 As a rule and to prevent the parts 26 that react to the centrifugal force
 from being too heavy or too large, it is advantageous to have a
 transmission, so that the speed of the center gear, for example, is 8
 times higher than that of the frictional wheel 3.
 The center gear 24 is fixedly connected to the core 27, into which core
 radially outward-pointing pins 28 are inserted. A sector-shaped flyweight
 26 is positioned on each pin 28, in such a way that it can glide. The
 flyweights have respectively one bore 29 for one pin 28 for this.
 The 4 flyweights 26 surround the core 27 in a symmetrical arrangement (FIG.
 4), wherein each covers a 90.degree. sector. A spiral spring 31,
 positioned inside groove 30 on the outside, keeps the flyweights pushed
 against the core 27 and forms the antagonistic force to the centrifugal
 force.
 Respectively two pins 32 are inserted at an angle into the flyweights 26
 and project from the flyweights 26 in the direction of axis 14. The pins
 32 glide inside bores 33 in the thrust collar 34. Finally, the movable
 cone 15, positioned rotatably on a rolling bearing 35, sits on the thrust
 collar.
 All rotating parts of the centrifugal unit are positioned with little
 friction in suitable bearings 36 on the axis 14. Shaft 20 is positioned in
 the same way inside frictional wheel 3. Pins 32 and pins 28 are composed
 of steel, which ensures good gliding qualities in the flyweights 26 of
 brass and the thrust ring 34 that is also made of brass.
 During the roping down, the rope 4 puts into motion the frictional wheel 3
 and, via the planet gear, also the core 27 and the surrounding flyweights
 26 since the freewheel mechanism 25 blocks in this direction. Starting
 with a certain speed, the flyweights 26 start to move toward the outside,
 against the force of spiral spring 31, or to exert a net force directed
 toward the outside onto the pins 32. The pins 32 convert this movement and
 force, directed toward the outside, into an axially directed force onto
 the pressure disk and thus the cone 15. The cone 15 pushes the movable jaw
 10 in the direction of the fixed jaw 9 and thus narrows the cross section
 of guide 8, as a result of which an increasingly stronger frictional
 braking force is exerted onto the pull end 7 that is positioned inside the
 guide 8. In addition, convexities 38 are located inside grooves 37 in jaws
 9, 10, which jaws together form the guide 8, so that the rope 7 is forced
 into an increasingly S-shaped course inside the guide 8 (FIG. 5), which
 further increases the friction.
 It is a common design criteria for the brake mechanism to avoid roping down
 speeds exceeding 2 m/s for a load of 150 kg. The operating threshold and
 strength of the brake is achieved through a suitable selection of the
 various component parts, such as transmission of the planet gear 21-24,
 weight of the flyweights 26, strength and characteristic of the spiral
 spring 31, form of the brake jaws 9, 10 and the guide 8, etc.
 It will be understood that the above description of the present invention
 is susceptible to various modifications, changes and adaptions, and the
 same are intended to be comprehended within the meaning and range of
 equivalents of the appended claims.
 For example, it is conceivable to use a combination of conical and tapered
 surfaces in place of the angled pins 32, possibly by also using roll
 bodies. With higher requirements, e.g. for higher loads, the blocking
 effect of the freewheel mechanism 25 can be overtaxed. However, it is
 possible to provide more than one planetary shaft 20 with, respectively,
 one freewheel mechanism 25, as a result of which the load will be
 distributed over the existing freewheel mechanisms. It is furthermore
 conceivable to have a different number of flyweights with a different form
 or different angle. Also, a different material can be selected for
 producing the flyweights and pins 32 and pins 28, as long as displacement
 on the latter is ensured.