BACKGROUND
Fall protection system can be used on or around various structures such as buildings, equipment, industrial or manufacturing plants, pits, shafts, mines, and the like. However, many existing fall protection system are designed for use with fixed structures, and often are not adjustable and thus are able to be used in certain situations, such as with structures or equipment that are movable or adjustable.
In order to provide movable or adjustable fall protection systems, a flexible net or the like can be coupled to a rotatable spool, such that the net can be expanded/protracted and retracted to the desired length. The spool may include a spring to add tension to the extended net. However existing spring systems may not be sufficiently compact, robust and/or may not provide a sufficient tensioning force.
SUMMARY
In one embodiment the current disclosure is directed to a system including a spool mechanism having a set of a plurality of circumferentially-spaced springs and a plurality of circumferentially-spaced planetary gears, wherein each planetary gear is rotationally coupled to an associated spring. The system further includes a sun gear positioned inside of and gearingly coupled the plurality of the planetary gears, and a ring gear positioned outside of and gearingly coupled the plurality of the planetary gears.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is an upper perspective view of a spring loaded spool mechanism, shown in conjunction with a net, in a retracted position;
FIG. 2 shows the spool mechanism and net of FIG. 1, in a protracted position;
FIG. 3 is an upper perspective view of the spool mechanism of FIGS. 1 and 2, shown without the net;
FIG. 4 is an upper perspective view of the spool mechanism of FIG. 3, with the outer casing removed;
FIG. 5 shows the spool mechanism of FIG. 3, with a middle section of plates and springs removed;
FIG. 6 is a detail view of the upper portion of the spool mechanism of FIG. 4, with the end cap removed;
FIG. 7 is an upper perspective view of a plate and springs of the mechanism of FIG. 5;
FIG. 8 is a detail view of a spring of FIG. 7; and
FIG. 9 is an upper perspective view of two spring loaded spool mechanisms, shown in conjunction with a net, in an extended position, and shown in conjunction with a person.
DETAILED DESCRIPTION
With reference to FIGS. 1 and 2, the system 10 can include a spring loaded spool or spool mechanism, generally designated 12, in one case used in conjunction with a flexible net or netting, generally designated 14. The spool mechanism 12 is coupled to the net 14, in one case at or adjacent to an end of the net 14. The spool mechanism 12 is cylindrical or generally cylindrical in the illustrated embodiment and is rotatable about its central axis A. In this manner, when the spool mechanism 12 is rotated, the net 14 is wrappable about the spool mechanism 12, or unwrappable about the spool mechanism 12, depending upon the direction of rotation. Thus the system 10/net 14 is movable to a retracted position, as shown in FIG. 1 wherein more (or all) of the net 14 is wrapped around the spool mechanism 12 and a relatively shorter length (if any) of the net 14 is free and not wrapped around the spool mechanism 12. The system 10/net 14 is movable to an extended position, as shown in FIG. 2 wherein less (or none) of the net 14 is wrapped around the spool mechanism 12 and a relatively longer length (or all) of the net 14 is free and not wrapped around the spool mechanism 12.
The net 14 can take any of a wide variety of forms and be made of various materials. In one case the net 14 is made of or includes a set of parallel, spaced apart, longitudinally-extending ropes, bars, wire, chain or the like 16. The net 14 can also include a set of parallel, spaced apart transversely-extending ropes, bars, wire, chain or the like 18 to provide structural stability to the net 14. The net 14 can be made of various materials such as steel or other metals (including strands, wires, cables, etc.), plastic or polymers, composites, natural fibers, synthetic fibers such as polypropylene, nylon, polyester, polyethylene, aramids or the like, and combinations thereof. The net 14 can also be made of a screen or screen-like material, or even solid sheets of material, but in any case the net 14 may be sufficiently flexible to be wound about and conform or generally conform about the spool mechanism 12.
With reference to FIG. 3, the spool mechanism 12 can include an outer casing 20 which receives and encapsulates the inner components of the spool mechanism 12, and provides a surface about which the netting 14 can be wound. The outer casing 20, in the illustrated embodiment, takes the form of a plurality of outer casing portions 20a with notches 22 on the upper edges and corresponding protrusions 24 or the lower edge that fit in to the notches 22 thereof such that the casing portions 20a can fit together to form a generally continuous, generally cylindrical outer casing 20.
FIG. 4 shows the spool mechanism 12 with the outer casing 20 removed. As can be seen the spool mechanism 12 can include a plurality of generally flat, planar plates 26 that are circular in top view in the illustrated embodiment, with each plate 26 aligned in a radial plane. In one case only a single plate 26 is utilized, but in the illustrated embodiment the spool mechanism 12 includes a plurality of plates 26 aligned with each other about their axes and/or outer perimeters, and spaced apart in the axial direction, to thereby form a generally cylindrical stack of plates 26.
With reference to FIGS. 5, 7 and 8, each plate 26 can carry thereon a plurality of circumferentially spaced springs 28. Each spring 28 can include or take the form of a power spring. Thus, in one case each spring 28 can include a length of tape made of a resilient spring material, such as steel or other metal, that is wound about itself in the (local) circumferential direction. Each spring 28 can be positioned in a spring retainer 30, which in the illustrated embodiment is a generally cylindrical wall extending about the associated spring 28 and capturing the spring 28 therein, with a circumferentially extending gap 32 (FIG. 7) positioned in each spring retainer 30. Each plate 26 can include a set of springs 28 thereon (six springs 28 in the illustrated embodiment), such that the spool mechanism 12 includes more than one/multiple sets of springs 28 that are aligned in a first radial plane on a first plate 26, and another set of springs 28 aligned in a second radial plane on a second plate 26 that is axially spaced apart from the first radial plane, etc.
With reference to FIG. 7, each spring 28/spring tape can have a radially outer hook end 34 that extends through the gap 32 in the associated spring retainer 30, and includes/extends in a 180 degree bend, to couple the hook end 34 to the spring retainer 30. Each spring 28/spring tape can also have a radially inner end 36 that is fixedly received in a slot 38 of a central arbor 40 of the spring 28. Each arbor 40 is rotatable about its central axis B (FIG. 7). Each spring 28 is configured such that when the arbor 40/inner end 36 is rotated in the (local) circumferential direction, such as in the direction of arrow C of FIG. 7, the associated spring 28 is wound up and thereby exerts or experiences a biasing force that tends to cause the spring 28 to rotate in the opposite direction (e.g. to where the spring 28 is in a neutral position).
Each spring 28 can be rotationally coupled to an axially-adjacent (e.g. upper and/or lower) axially-aligned spring 28 to form a plurality of spring columns 42 (FIG. 6) (six spring columns 42 in the illustrated embodiment). In particular, each arbor 40 can include a set of protrusions 44 on an upper side thereof, and each arbor 40 can also include a set of correspondingly-sized and shaped recesses (not shown) on a lower side thereof to closely receive a set of protrusions 44 therein. In this manner each arbor 40 can be rotationally coupled to an axially-adjacent (e.g. upper and/or lower) arbor 40 in a modular manner, to thereby rotationally couple the axially-adjacent springs 28 in a spring column 42. It should be understood that each spring 28/arbor 40 can be rotationally coupled to an axially-adjacent spring 28/arbor 40 by any of a wide variety of means or mechanisms beyond the protrusions 44/recesses described and shown herein, such as other forms of interengaging shapes/geometry, or by mechanical couplings such fasteners, or via welding or other joining methods.
With reference to FIG. 6, the spool mechanism 12 can include a planetary gear system/epicyclic gear arrangement 46 at one (or both) axial end thereof. The planetary gear system 46 can include a fixed sun gear 48 located at a geometric center of the spool mechanism 12/gear system 46, and a plurality of planetary gears 50 (six planetary gears 50 in the illustrated embodiment) that are circumferentially spaced about the sun gear 48 and that are gearingly coupled to the sun gear 48. The planetary gear system 46 can also include an outer ring gear 52 extending entirely circumferentially about the sun gear 48 and each planetary gear 50. The sun gear 48 can be rotationally fixed relative to the ring gear 52/outer casing 20, and/or relative to the planetary gears 50. The ring gear 52 can be gearingly coupled to each planetary gear 50 and be rotationally coupled to the outer casing 20. The term “gearingly coupled,” as used herein, can mean that the teeth of a gear intermesh with the teeth of another gear, or the gears are otherwise rotationally coupled, such that rotation of one gear causes relative rotation/movement of the other gear(s) in a well known manner.
In one case each planetary gear 50 is positioned on a gear support 54 taking the form of a flat plate in one case, and can be rotationally coupled to an axially-adjacent (e.g. uppermost, in the case of FIG. 6) spring 28/spring column 42 of the adjacent (e.g. uppermost) plate 26. In particular, in one case each planetary gear 50 has a center shaft 56 that extends through the gear support 54, and is rotationally coupled to the arbor 40 of the axially-adjacent spring 28/spring column 42. In one case, each center shaft 56 has a set of recesses (not shown) that closely receive/engage an associated set of protrusions 44 of the arbor 40. Since each spring 28 in a spring column 42 is axially coupled together, in this manner each planetary gear 50 is rotationally coupled to an associated spring column 42 and/or rotationally coupled to each individual spring 28 in the associated spring column 42.
With reference to FIGS. 3-5, the spool mechanism 12 can include a first (upper) end cap 58 configured to cover and protect the planetary gear system 46. The spool mechanism 12 can include a bearing plate 60 at or near the bottom thereof that supports the weight of the spool mechanism 12, and is in one case fixedly coupled to the outer casing 20 and the lower ring gear (if utilized). The bearing plate 60 is supported on a fixed mounting plate 62. With reference to FIG. 5 the spool mechanism can include an axially oriented/extending central post 64 that is non-rotationally mounted and can be fixedly coupled to the sun gear 48, and extends axially the entire or generally entire height of the spool mechanism 12. The central post 64 can be coupled to the end cap 58 and/or the mounting plate 62, and can provide structural stability and stiffness to the spool mechanism 12. In one case an entire axial dimension (height) of the outer casing 20 is filled with springs 28 and/or plates 62.
During operation of system 10, the spool mechanism 12/net 14 can begin in the retracted position as shown in FIG. 1, wherein the net 14 is generally wound about the outer casing 20 of the spool mechanism 12. The spool mechanism 12 can, in one case, be configured such that the springs 28 are pretensioned and exert a biasing force to retain the spool mechanism 12/net 14 in the retracted position. In another embodiment, the springs 28 are in a neutral position, and do not exert any biasing force when the spool mechanism 12/net 14 is in the retracted position.
In order to operate move the system 10 to its extended position. Force/torque can be applied to the net 14 which causes the spool mechanism 12 to rotate about its center axis A in the direction of arrow D (FIG. 1). When the spool mechanism 12 is rotated in the direction of arrow D the outer casing 20 is also moved in the direction of arrow D, which in turn causes the ring gear 52 to rotate in the direction of arrow D in FIG. 6. This rotation of the ring gear 52 in turn causes each planetary gear 50 to rotate locally in the direction of arrow E and also orbit the sun gear 48 in the direction of arrow D. The rotation of the ring gear 52 in turn causes each spring 28/spring column 42 to rotate (locally) in the direction of arrow C (FIG. 7), and also rotate in the direction of arrow D of FIG. 6.
The rotation of the planetary gears 50/springs 28 thereby causes the springs 28 to wind up and exert a biasing force onto the ring gear 52/outer casing 20/net 14 to bias the system 10 to the retracted position and tension the net 14. In one case, the more the net 14 is extended and/or the more the outer casing 20 is rotated, the greater the biasing force applied by the springs 28 and the biasing force is a function of the number/extent of rotations of the outer casing 20. In other cases however the system 10 can be configured such that the biasing force of the springs 28 is fixed, and is independent of the amount of extension of the net 14/rotation of the outer casing 20. In either case the system 10 can be configured such that when the outer casing 20 and ring gear 52 are rotated in a first direction, the springs 28 exert a force on the outer casing 20 and ring gear 52 to bias the outer casing 20 and ring gear 52 in a second direction opposite to the first direction.
When it is desired to retract/spool the system 10/net 14, the force applied to the net 14 and/or the spool mechanism 12 is lessened or removed. This causes the spool mechanism 12 to rotate in the opposite to direction of arrow D, and the gear system 46, outer casing 20 and springs 28 move in the opposite direction to that explained above. The net 14 is then automatically wound/spooled about the spool mechanism 12 until the net 14 is at the desired length.
If desired, a second/supplemental planetary gear system (not shown) can be located on and/or inside the bearing plate 60 at the opposite (bottom) end of the spool mechanism 12, or alternatively the spool mechanism 12 may include only a single planetary gear system 46 on and/or inside the bearing plate 60. In addition, in one case, as shown in FIG. 9, the system 10′ can include two spool mechanisms 12 (e.g. a spool mechanism 12 at one end, and a second/supplemental spool mechanism 12′ at another end, with a corresponding second/supplemental ring gear 52, planetary gears 50, sun gear 48, etc.), thereby providing a spool mechanism 12. 12′ located at opposite ends of the net 14. In this manner, one or each spool mechanism 12 can be moved in the direction of arrow F to spool/unspool the net 14 thereon, while maintaining sufficient tension in the net 14. In particular, the use of two spool mechanisms 12, 12′ can increase the length of the net 14 that can be protracted since a tension force is applied to each opposite end of the net 14, thereby increasing the tension force. The use of two spool mechanisms 12, 12′ can also provide greater flexibility in the positioning of the net 14. However, in other cases only a single spool mechanism 12 is needed, which can reduce complexity and cost.
The distal end of the net 14 and/or the spool mechanism(s) 12, in the embodiments of FIGS. 1, 2 and 9, can be coupled to a fixed structure such as a floor wall, post, pillar, or the like, or coupled to a movable structure such as a vehicle, forklift, movable partition, expandable structure or the like. The net 14 can be oriented horizontally when extended, or vertically, or at various angles.
The biasing force applied by the springs 28 induces a tension into the net 14, to help pull the net 14 taut and to ensure the net 14 does not sag, and to ensure the net 14 retains its shape. This in turn can help to ensure the net 14 retains persons/items on the desired side of the net 14 when forces in the lateral direction are applied to the net 14. The tension of the net 14 should be sufficiently high to avoid undesired amounts of sag in the net 14, and to ensure falls are sufficiently arrested, but should not be so tight as to apply undue forces and damage the components of the system 10. In one case, the tension in the net 14 is maintained between about 100 lbs. and about 1000 lbs. force, and more particularly between about 600 lbs. and about 800 lbs. force in one case. The net 14 in one case has a height/dimension in the axial direction of at least about three feet in one case, or at least about four feet in another case, and less than about ten feet in another case. In addition, when it is desired to move the system 10/net 14 to the retracted position, the biasing force applied by the springs 28 makes the retraction relatively quick and easy.
The arrangement of springs 28/spring columns 42, in conjunction with the gear system 46, provides a compact and reliable method for applying a relatively strong and predictable tension force to the net 14 and reliably/moving the net 14 to a retracted position. In particular, by coupling each spring 28 together in spring columns 42, a large spring force can be generated by using a number of individual springs 28 that may not have a high spring force when used alone. In addition, should an individual spring 28 or a small number of springs 28 fail, the system 10 can continue to operate with relatively little loss of tension/biasing force. Moreover, should a spring 28 fail for some reason, the failed spring can be contained by the casing 20 and/or plates 26 and/or spring retainer 30 and/or end cap 58 and/or bearing plate 60 and thereby not damage any surrounding equipment. In addition, by positioning the springs 28 inside the casing 20, the springs 28 take advantage of the space inside the casing 20, which also serves as a spool about which the net 14 is wound. Finally, by positioning the springs 28 inside the casing 20 (and inside the net 14 when the net 14 is at least partially retracted) the springs 28, plates 26, gear system 46 and other components are protected from external forces and environmental effects.
Having described the invention in detail and by reference to certain embodiments, it will be apparent that modifications and variations thereof are possible without departing from the scope of the invention.
Patent Application
20250034890
