Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16H—GEARING
  • F16H55/00—Elements with teeth or friction surfaces for conveying motion; Worms, pulleys or sheaves for gearing mechanisms
  • F16H55/32—Friction members
  • F16H55/36—Pulleys
  • F16H55/50—Features essential to rope pulleys

Definitions

• the present invention relates to an adhesion pulley for transmitting a tensile force to a cable, of the type comprising a wheel having a smooth peripheral surface, and an endless belt wound at least one turn on the peripheral surface of the wheel for supporting the cable in service, the cable being wound around the pulley, on the endless support strip, in the same direction and with the same pitch as said endless strip and bearing on it.
• Adhesion pulleys of the above-mentioned type have been known for a long time (see for example US Pat. No. 750,920).
• the endless strip interposed between the wheel and the cable on which traction is to be exerted is provided to solve the problem of wear of the cable by friction on the pulley wheel and on lateral guides, fixed or mobile, intended to force the cable to wind in a helix around the pulley, when the winding of the cable has more than one complete turn.
• the endless belt can be of any suitable material, but preferably leather. It is clear that such a continuous strip of leather is unable to withstand the significant forces prevailing in modern winches developing large tensile forces, for example greater than 5 tonnes.
• the patent US 750 920 also provides that the endless belt can be produced in the form of a metal chain linked to a continuous leather band, the latter being in contact with the peripheral surface of the pulley. In this case, in service, all of the forces applied to the cable are transmitted to the metal chain.
• the patent US 750 920 also provides that the endless belt can be made in the form of a metal chain, the links of the links of which protrude under the chain, that is to say on the side of the chain which is turned. towards the peripheral surface of the wheel, or whose links are provided with transverse ribs regularly spaced along the chain. Projecting joints or ribs transverse engage in recesses or notches provided in the peripheral surface of the pulley wheel and regularly spaced around its circumference, in order to prevent any relative sliding between the chain and the wheel in the circumferential direction (see also in this regard the patent FR 671 258, the patent US 3 116 050 and the patent DE 491 646). Not only does such an arrangement not solve the problem of relative longitudinal sliding between the cable and the chain, but it also complicates the construction of the pulley.
• the present invention therefore aims to provide an adhesion pulley of the above-mentioned type, in which the problems of wear of the cable, due to the relative longitudinal sliding between the cable and the endless belt, are greatly reduced, and the endless band has less tendency to break.
• the adhesion pulley according to the invention is characterized in that the endless belt is constituted by a succession of spaced pads, which can slide with friction on the peripheral surface of the wheel, each pad being connected to the next pad.
• an elastically extensible connecting element the longitudinal elastic modulus of which and / or the dimensions (length, transverse section) are chosen so that, for a cable having a given longitudinal elastic modulus and subjected, in service, to one predetermined maximum tension, the total elongation of the connecting elements is equal to the total elongation of the part of the cable wound on the pulley for an eitort applied to the connecting elements between 2% and 20% of said predetermined maximum tension.
• the strip without linen elastically elongates at the same time as the cable, sliding on the periphery of the pulley wheel, thus preventing the cable from being damaged by friction with the strip without linen.
• the invention makes it possible to reduce to a large extent the problems of friction between the cable and the endless belt, but it also makes it possible, as will be seen below, with certain precautions, to draw cables which undergo a high elongation, such as cables made of aramid or polyamide fiber.
• the invention also makes it possible to solve a problem arising with cables having accumulated, in service, dirt or other foreign bodies. Indeed, it is frequent that a cable having for example stayed a certain time in water is loaded with algae and / or shells which, in the long run, developed and encrusted on the cable.
• the incrustations When a cable loaded with such incrustations is subsequently released from the water, for example by means of a traction sheave winch, the incrustations tend to detach from the cable when the latter passes around a pulley, and to be introduced between the peripheral surface of the pulley wheel and the endless band of cable support when such an endless band is provided, thus causing problems of wear by abrasion.
• FIG. 1 is a side elevation view of an adhesion pulley according to a first embodiment of the invention
• FIG. 2 is a sectional view along the line II - II in FIG. 1,
• FIG. 3 shows, on a larger scale, a shoe forming part of the pulley of FIGS. 1 and 2,
• FIG. 4 is a sectional view along line IV-IV of FIG. 3,
• FIG. 5 shows two consecutive pads similar to that of FIG. 3, and makes it possible to explain how the connecting element between the pads is dimensioned
• FIGS. 6 to 8 are sectional views similar to FIG. 4, showing variants
• FIG. 9 is a side elevation view, similar to FIG. 1, showing a second embodiment of the invention.
• FIG. 10 is a sectional view along line X-X of FIG. 9,
• Figures 11 and 12 show, on a larger scale, details of the pulley of Figures 9 and 10, Figure 11 being a sectional view along the line XI-XI of Figure 12 and the latter being a sectional view along line XII-XII of FIG. 11,
• FIG. 13 is a view similar to that of FIG. 5, but in the case of the embodiment of FIGS. 9 and 10,
• FIG. 14 shows the pulley of FIG. 9 in service with a cable wound half a turn around the pulley, the latter being driven in rotation in an anticlockwise direction,
• FIG. 15 is a sectional view along line XV-XV of FIG. 14,
• FIG. 16 shows an embodiment similar to that of FIGS. 9 and 14, but in which the cable makes two complete turns around the pulley
• FIG. 17 is a sectional view along line XVII-XVII of FIG. 16,
• Figures 18 and 19 are sectional views similar to that of Figure 17, showing two variants, the variant of Figure 18 corresponding to the first embodiment of Figure 1, while the variant of Figure 19 corresponding to embodiment of FIG. 16,
• FIGS. 20 and 21 are sectional views showing, on a larger scale, details of the variants of FIGS. 18 and 19,
• FIG. 22 is a side elevation view showing a section of an endless belt which can be used in an adhesion pulley according to a third embodiment of the invention.
• FIG. 23 shows, on a larger scale and with a cutaway, part of the endless belt of FIG. 22,
• FIG. 24 is a sectional view along line XXIV-XXIV of FIG. 23,
• FIG. 25 is a view similar to FIG. 22 showing a variant of the endless belt
• FIG. 26 shows, on a larger scale, part of the endless belt of FIG. 25,
• FIG. 27 is a sectional view along the line XXVII-XXVII of FIG. 26, and
• FIG. 28 is a sectional view showing two sections of the endless belt of Figure 25 joined to one another.
• the adhesion pulley 1 shown in FIGS. 1 and 2 comprises a wheel 2 and an endless belt 3 which surrounds the wheel 2.
• the latter comprises a hub 2a and a rim 2b connected to the hub 2a by a web 2c in the form of disk.
• the rim 2b has a smooth peripheral surface, that is to say devoid of notches and / or drive teeth.
• the veil 2c shown in Figures 1 and 2 is full, it can also be perforated or produced in the form of several spokes extending radially or substantially radially between the hub 2a and the rim 2b.
• elements 2a, 2b and 2c of the wheel 2 shown in Figures 1 and 2 are shown as being made in one piece, these elements may be constituted by separate pieces suitably assembled and rigidly fixed to each other to others as is well known in the art of building pulleys.
• the peripheral surface of the wheel 2 is relatively narrow and the endless belt 3 makes only one turn around the wheel 2 and is in close contact with the surface peripheral of it all around.
• the endless belt 3 comprises several pads 4, for example sixteen pads as shown in Figure 1, which are connected to each other by connecting elements 5 capable, in service , to undergo elastic elongation in a manner which will be explained in detail below.
• the connecting elements 5 are constituted by at least one endless connecting cable, preferably two cables 5, which each have the same extent as the endless belt 3, that is that is, in the embodiment of FIGS. 1 and 2, each cable 5 makes a complete turn around the wheel 2.
• the pads 4 are anchored at regularly spaced points on each of the two cables
• each shoe can have a longitudinal groove 6 in each of its two lateral faces, and each cable 5 passes longitudinally in a respective groove 6.
• the inner face of each shoe 4 that is to say its face which, in service, is in contact with the smooth peripheral surface of the wheel 2, has a curvature corresponding to that of said peripheral surface.
• the internal side 6a of each groove 6, that is to say its side closest to said internal surface of the shoe 4 has an arcuate profile concentric with the arcuate profile of said internal face of the shoe. 4, while the outer side 6b of each groove 6 is substantially straight.
• each groove 6 has a width which increases towards the ends of the shoe from a minimum width value in the middle of the length of the groove 6.
• This minimum value of the width of the groove 6 corresponds to the diameter of the connecting cable 5 which is forced into the minimum width portion of the groove 6, thus ensuring a connection between the shoe 4 and the cable 5.
• this connection can be optionally reinforced with glue, by a partial crimping of the cable 5 in the groove 6 or by any other suitable means.
• each shoe 4 has, in its external surface, a longitudinal groove 7.
• the grooves 7 of all the shoes 4 together form a circumferential groove suitable for receiving a cable C ( Figures 4 and 5), on which a driving force of traction (or a retaining force in the case where the load attached to cable C is driving) must be exerted by means of the adhesion pulley 1.
• each shoe 4 has a part 8 which projects on its internal face, in the middle of the width of said internal face and over the entire length thereof, as shown in FIGS. 3 and 4.
• the throat protector 9 is preferably slightly larger than the amount by which the portion 8 of each pad 4 projects from the inner face of the corresponding pad as shown in Figure 6.
• each pad 4 is in contact with the peripheral surface of the rim 2b of the wheel 2 essentially by the two parts 4a and 4b (see also FIG. 4) of its internal face which are situated respectively on either side of the projecting part 8.
• the latter essentially serves to prevent each shoe 4 from moving laterally, that is to say in a direction parallel to the axis of the wheel 2.
• the wheel 2 can be made of various suitable materials, such as, for example, steel, stainless steel, aluminum.
• the peripheral surface of its rim 2b can be bare or provided with a coating 11 (FIG. 8) in a material chosen to give said peripheral surface an appropriate coefficient of friction.
• the pads 4 can be of any suitable material, for example steel or cast iron.
• the surface of the groove 7 of each shoe 4 can be bare ( Figures 4, 7 and 8) or it can be provided with a coating 12 ( Figure 6), for example a coating of polytetrafluoroethylene (PTFE) or polyurethane.
• the internal face of each shoe 4 may be bare (Liguria 4, 6 and 8) or it may be provided with a coating 13 (FIG. 7), for example a coating in polytetrafluoroethylene (PTFE) or in polyurethane.
• the cables 5 can for example be polyamide cables having a suitable cross-section and longitudinal elastic modulus as will be seen below.
• FIGS. 1 to 5 show another embodiment of the adhesion pulley 1 of the present invention.
• the adhesion pulley 1 shown in Figures 9 to 13 differs from that of Figures 1 to 5 in that each connecting element 5 is constituted by a short strip 14 of elastomeric material, for example polyurethane elastomer, which is provided a hooking heel 14a at each of its ends ( Figures 11 and 13).
• the hooking heels 14a have the shape of a cylindrical bead with a circular cross section, their cross section can have any other suitable shape, for example a dovetail shape or a T shape.
• each shoe 4 is devoid of the lateral grooves 6 of Figures 3 and 4, but it has at each of its ends a transverse groove 15 (Figure 11), which is shaped to receive and retain the hooking heel 14a of one of the connecting elements 5.
• each connecting strip 14 made of elastomeric material has a width 1 equal to that of the pads 4 as is more particularly visible in FIG. 12.
• the connecting strip 14 which also plays the role of a sealing element by preventing foreign bodies penetrating radially between the pads from reaching the peripheral surface of the wheel 2.
• Figures 14 and 15 show the adhesion pulley 1 in service with a cable C wound a half-turn around the pulley.
• the representation of FIG. 14 is made by supposing that the pulley is driven in clockwise rotation, indicated by the arrow F, and that the tension T 1 of the strand d of the cable C which starts from the pulley 1 is stronger than the tension T 2 of the cable strand C 2 which arrives on the pulley.
• the wheel 2 of the traction sheave 1 when the wheel 2 of the traction sheave 1 is rotated in the direction of the arrow F, it drives the shoes 4 by adhesion which in turn also drives the cable C in the direction indicated by the arrows in Figure 14.
• the cable C undergoes elastic elongation.
• the connecting elements 5 are determined to be able to elastically elongate. It will be assumed that the cable C used with the adhesion pulley 1 has a known longitudinal elastic modulus Ei, a cross section Si known and is subjected in service to a maximum tension T max corresponding to a maximum load of use n 1max such as :
• T max n 1 max ⁇ S 1 . (1)
• L 1 is the length of the cable C measured between the midpoints of two consecutive pads 4 ( Figures 5 and 13) and ⁇ L 1 is the elongation of the portion of cable of length L 1 under load n 1max .
• S 2 represents the cross section of the connecting element 5.
• S 2 is the sum of the cross sections of the two cables 5, while, in the case of the embodiment of Figures 9 to 13, S 2 is equal to the product of the width 1 of a connecting strip 14 by its thickness e (see Figure 12).
• the value of k may be between 2% and 20%.
• ⁇ L 1 must be equal to ⁇ L 2 .
• L 1 is also known: it is the length of cable wound on the pulley 1 divided by the number of pads 4 corresponding to the length of cable wound (in the case of Figure 14 or the cable C is wound a half-turn around the pulley 1 of radius R and is supported on eight pads 4 during its passage on the pulley 1, L 1 is equal to ⁇ R / 8).
• the length L 2 of the connecting elements 5 can be easily calculated in a manner similar to that indicated with regard to the length L 1 in the case of the connecting cables 5 of the embodiment of FIGS.
• the length L 2 can be chosen arbitrarily equal to a value less than the calculated value mentioned above in the case of the connecting strips 14 of the embodiment Figures 9 to 13.
• the formula (5) makes it possible to calculate the cross section S 2 of the connecting elements.
• Knowledge of S 2 then makes it possible to calculate the diameter of each of the two cables 5 in the case of the embodiment of FIGS. 1 to 5, therefore also the width of the grooves 6 of the pads 4.
• f denotes the coefficient of friction between the cable C and the pads 4
• oc is the winding angle of the cable C around the adhesion pulley (in the case of FIG. 14, a is equal to ⁇ )
• N is the number of pads 4 on which the cable C rests for the winding angle ⁇ (N is equal to 8 in the case of FIG. 14)
• T 1 and T 2 are the tensions of the strands C1 and C2 of the cable C at the input and at the output of the adhesion pulley 1
• the adhesion force F 1 between the internal face of the pads 4 and the peripheral surface of the wheel 2 must be less than the adhesion force F 2 between the surface outer of the cable C and the outer face of the pads 4, that is to say the surface of the groove 7 of the pads 4.
• the cables of this genre are cables comprising a core composed of one or more strands free of aramid or polyamide, surrounded by a thin layer of polytetrafluoroethylene, which is not linked to the core and which is itself surrounded by '' a protective sheath, which is not linked to the underlying polytetralluoroethylene layer
• the adhesion bar F 2 between the external surface of the sheath and the surface of the groove 7 of the pads 4 is less than the force of adhesion F 3 between the surface of the thin layer of pol ytétralluoroéthylène and the internal surface of the cable protection sheath.
• F r is the force exerted radially by the cable C on an arc of elementary length dl of the pulley 1.
• F r is given by the formula:
• p is the pressure exerted by the cable on the pulley 1 and is given by the formula:
• f 1 , f 2 and f 3 are respectively the coefficient of friction between the inner face of the pads 4 and the peripheral surface of the wheel 2, the coefficient of friction between the outer surface of the cable C or, if applicable, of its protective sheath and the surface of the groove 7 of the pads 4, and, in the case of a cable made of aramid or polyamide fiber, with protective sheath, the coefficient of friction between the thin layer of polytetrafluoroethylene and the internal surface of the protective sheath.
• the coefficients K 1 , k 2 and k 3 are form coefficients, the value of which depends on the shape of the profile of the mutually contacting surfaces viewed in cross section. For a flat contact profile between the pads 4 and the wheel 2, the coefficient k 1 is equal to 1. For a semi-circular contact profile (groove 7 and cable protection sheath) the coefficients k 2 and k 3 are approximately equal to
• Figures 16 and 17 show an embodiment in which the wheel 2 is wider than in the embodiments previously described and in which the endless belt 3 makes three turns around the wheel 2 and supports a cable C which is itself wrapped two turns around the pulley.
• the endless belt 3 has a structure similar to that of the embodiment shown in Figures 9 to 13. More specifically, each connecting element 5 between two pads 4 consecutive is made up by a short Dande 14 made of an elastomeric material, the ends of which are respectively anchored in the end faces mutually opposite the two pads 4 consecutive. It goes without saying, however, that the endless belt could have a structure similar to that of the embodiment shown in FIGS. 1 to 5.
• the peripheral surface of the wheel 2 has, seen in section, a flat profile as can be seen in FIG. 17, that is to say that the pulley 2 does not have no circumferential groove like the groove 9 in FIGS. 6, 7, 8 and 12, and that the internal face of the pads 4 has no projecting part like the part 8 in FIGS. 4, 6, 7, 8 and 12.
• suitable guiding means known in themselves, such as helical ramps, skids, rotating rollers or a combination thereof, are provided to force the endless belt to wind helically around the periphery of the wheel 2.
• These guide means are well known and will therefore not be described in detail (see for example the prior documents cited in the preamble to this memo).
• a continuous endless strip of sealing 16 can be provided, made of a flexible and elastically extensible material, for example made of polyurethane elastomer, on at least one side of the endless strip 3 which supports the cable C, of preferably on both sides of the strip 3, as shown in Figures 18 and 19.
• Des cooperating retaining means are provided on the endless support strip 3 and on the endless sealing strip 16 to attach them to each other.
• each endless sealing strip 16 may comprise, on its lateral face facing the endless support strip 3, a continuous longitudinal heel 17 which is engaged in a longitudinal groove 18 formed in at least one of the two side faces of each shoe 4, preferably in each of the two side faces of said shoes.
• each endless sealing strip 16 may advantageously comprise, at least on one side face and preferably on its two side faces, a longitudinal lip 19, which is formed integrally with the strip 16, extends continuously over the entire length thereof and projects laterally and outward from the corresponding lateral face of the strip 16.
• FIG. 20 shows, in cross section, the two strips 16 before they are assembled to a pad 4, while FIG. 21 shows two pads 4 forming part of two adjacent turns of the continuous endless strip of support 3 and each equipped with two sealing strips 16, the two strips 16 located between the two pads 4 being pressed against each other.
• FIG. 18 represents the case where the continuous strip 3 has a structure similar to that of the embodiment of the ligures 1 to 5, that is to say in which the connecting elements between the pads 4 are constituted by two cables 5
• a sealing element 21 flexible and elastically extensible, is arranged in each gap between two consecutive pads 4 and is attached to them.
• Each sealing element 21 has a width equal to that of the pads 4 as shown in FIG. 18.
• Each sealing element 21 can have, for example, a shape similar to that of the strip 14 shown in FIGS. 11 and 12 and be attached to the two pads 4 by heels similar to the heels. 14a of the strip 14.
• the elements 21 do not have a connecting function for the pads 4, but only a sealing function.
• FIG. 19 shows the case where the endless support strip 3 has a structure similar to that of the embodiment of FIGS. 9 to 13, that is to say in which the connecting elements 5 are constituted by strips 14 in an elastomeric material.
• the strips 14 have both a function of connecting the pads and a sealing function as has already been mentioned above.
• FIG. 22 shows another embodiment in which the pads 4 and the connecting elements 5 of the endless belt 3 are formed integrally from an elastomeric material, for example from polyurethane elastomer.
• the connecting elements 5 are formed by parts of the endless band having a reduced cross section with respect to the parts of the endless band forming the pads 4.
• the part of reduced section can for example be obtained by forming deep transverse grooves 22 at regular intervals in the face 3a of the endless belt 3 which is intended to come into contact with the peripheral surface of the wheel 2, as shown in FIGS. 23 and 24.
• the grooves 22 can have, views in cross section, a T-shaped profile as shown in Figure 23.
• a longitudinal groove 7 can also be formed over the entire length of the strip 3, in its external face, as shown in Figures 22 to 24.
• endless band 3 shown in these latter figures, it is not necessary to provide bands lateral sealing like the bands 16 of FIGS. 18 to 21, or sealing elements between the pads 4, like the sealing elements 21 of FIG. 18.
• the strip 3 may advantageously comprise, at least on one side face, a longitudinal lip 23, which formed integrally with the strip 3 , extends continuously over the entire length thereof and projects laterally and outward from said side face as shown in Figures 25 to 28.
• Figures 27 and 28 show a lip 23 from one side of the strip 3, it goes without saying that such a lip 23 could also be provided on both sides of the strip 3. From FIG. 28, it can be seen that when two adjacent turns of the strip 3 are glued to each other, the lip 23 of one of the turns is applied elastically against the side of the adjacent turn, thereby improving the seal between the two turns.
• each shoe 4 can be wider than what is shown in the drawings, and include a second groove or groove, parallel to the first groove or groove 7 and having a section transverse larger or smaller than that of the groove 7 to receive a cable having a larger or smaller section than that of the cable received in the groove 7.

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• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Devices For Conveying Motion By Means Of Endless Flexible Members (AREA)

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Citations (4)

• 1990
  • 1990-11-23 FR FR9014612A patent/FR2669701A1/fr active Granted
• 1991
  • 1991-11-22 WO PCT/FR1991/000929 patent/WO1992009831A1/fr active Application Filing

Patent Citations (4)

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