Patent Publication Number: US-2019169002-A1

Title: Pulley for high-efficiency winch

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present Application is a national stage of International Patent Application No. PCT/IT2014/000081, titled “Improved Pulley for High-Efficiency Winch,” filed 26 Mar. 2014, which claims priority from Italian Patent Application No. TO2013A000322 filed 22 Apr. 2013, and U.S. patent application Ser. No. 14/786,135, filed 21 Oct. 2015, the contents of which are incorporated in this disclosure by reference in their entirety. 
    
    
     FIELD OF THE INVENTION 
     The present invention deals with an improved pulley for high-efficiency winch, of the type used for transmitting mechanical energy by means of traction forces applied to ropes connected to a moving load. 
     A high-efficiency winch is used in several applications, for lifting or moving a load, dragging a rope and transmitting energy by means of a rope adapted to be wound. 
     BACKGROUND 
     Recently, the application of winches for transmitting energy has become important in the sector of managing wind energy, wherein the winches, connected to alternators and electronic power apparatuses, are used for extracting kinetic energy from “wind and for converting the produced mechanical energy into electric energy. 
     An important aspect in recovering mechanical energy from ropes connected to a moving load is given by the efficiency of the driving winch, for which: small percentages of energy imply a high heating of the driving pulleys and of the rope. 
     A process for extracting energy from wind implies the use of high-resistance ropes. The rope tension is generated by the lift of a kite flying with transverse wind. The pulley or the drum, on which the rope is wound, rotates due to the unwinding force induced by the rope itself. The mechanical power is generated by the combination of the mechanical tension in the rope and the speed with which the rope is stretched, being unwound from the pulley. 
     The pulley or the drum., on which the rope is wound, rotates due to the unwinding force induced by the rope itself. During this process, the wind kinetic energy is firstly converted into mechanical energy, due to the friction between rope and contact surface of the pulley or the arum; it is then converted into electric energy through alternators connected to the winch. 
     During the conversion, energy losses occur as heat which heats the contact surface of the pulley and increases the internal temperature of the rope compromising the mechanical properties due to overheating. 
     Conventional winches are not suitable for transmitting a great amount of energy due to their low efficiency. When there is a high-power winch equipped with high-resistance ropes, even a relatively small part of lost power could be critical. For example, a winch with a 97% efficiency, used for manipulating a power of 1.5 MW, generates a 45 kW thermal flow which must be suitably dissipated to prevent the rope from overheating. Together with the losses generated by the bearings of the rotary elements, the heat flow is mainly generated by the friction forces between rope and pulley. 
     Friction inside the rope is generated by relative displacements and distortions of different wires and braids, composing the rope and geometrically arranged in order to mutually scrape. On the other hand, friction between rope and pulley is the necessary ingredient to allow the winch to extract energy from the rope, while friction depending on any relative displacement between rope and pulley must be reduced to a minimum. 
     The architecture of a high-efficiency winch must comply with two concepts: the rope moving along the winch is subjected to a tension gradient associated with a distortion gradient depending on the nature of the material composing the rope; the rope wound on a pulley for more than one revolution, assuming that the pulley rotates with respect to its own longitudinal axis, must necessarily translate perpendicular to the direction of the main transmission force, for example along the longitudinal axis of the pulley, in order to prevent rope sections with different curvatures trom overlapping. 
     WO2011121272 discloses an application dealing with the first concept, aimed to make more uniform the distortion gradient, making the rope less stressed and subjected to degrade effects. This problem is solved with two co-penetrating pulleys, each one of which defines a discontinuous surface of the contact between rope and drum. 
     FR1105165 discloses a layout of a winch dealing with the second concept, comprising pulleys with cylindrical grooves whose diameter gradually decreases or increases being adapted to the different distortion status along the rope, so that the groove with bigger diameter is in contact with the rope section subjected to a high tension status and vice versa. 
     SUMMARY 
     Object of the present invention is solving the above prior art problems, by providing an improved pulley for high-efficiency winch, in favor of a higher energy productivity and a reduction of the power losses due to friction phenomena, and in favor of a reduced rope wear. 
     The above and other objects and advantages of the invention, as will result from the following description, are obtained with an improved pulley as claimed in claim  1  in contact with a section of rope included between two terminals, one of which is connected to a working load, the other being of minimum or null tension, characterized in that it comprises a kinematic chain formed of peripheral supports. Preferred embodiments and non-trivial variations of the present invention are the subject matter of the dependent claims. 
     It is intended that all enclosed claims are an integral part of the present description. 
     It will be immediately obvious that numerous variations and modifications (for example related to shape, sizes, arrangements and parts with equivalent functionality) could be made to what is described, without departing from the scope of the invention as appears from the enclosed claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will be better described by some preferred embodiments thereof, provided as a non-limiting example, with reference to the enclosed drawings, in which: 
         FIG. 1  shows a perspective view of a pulley according to the present invention connected to a rope; 
         FIGS. 2 and 3  show perspective views of components belonging to each peripheral support connected to the pulley of  FIG. 1 ; 
         FIG. 4  shows a front view of the pulley of  FIG. 1 ; 
         FIG. 5  shows a sectional view, along a plane passing for line V-V in  FIG. 4 ; 
         FIG. 6  shows an enlarged part VI belonging to  FIG. 4 ; 
         FIG. 7  shows an enlarged part VII belonging to  FIG. 5 ; 
         FIG. 8  shows different configurations a, b, c, along a plane X-Z of  FIG. 5 , of a connection between element belonging to each peripheral support connected to the pulley of  FIG. 1 ; 
         FIG. 9  shows a diagram of configurations a, b, c of  FIG. 8 ; 
         FIG. 10  shows a combined system of several pulleys of the type shown in  FIG. 1 ; 
         FIG. 11  shows a perspective view of a peripheral support belonging to a second embodiment of the present invention; 
         FIG. 12  shows a front view of the peripheral support of the previous Figure; 
         FIG. 13  shows a sectional view along line XIII-XIII of  FIG. 12 ; 
         FIG. 14  shows a side view of an operating diagram of the peripheral support of  FIG. 11 ; 
         FIG. 15  shows a perspective view of a prismatic insert belonging to the peripheral support of  FIG. 11 ; 
         FIG. 16  shows a side view of the insert of  FIG. 15 ; 
         FIG. 17  shows a perspective view of a peripheral support belonging to a third embodiment of the present invention; 
         FIG. 18  shows a perspective view of a part of the previous Figure; 
         FIG. 19  shows a front view of the peripheral support of  FIG. 17 ; 
         FIG. 20  shows a sectional view along line XX-XX of  FIG. 19 ; 
         FIG. 21  shows a perspective view of a variation of the peripheral support of  FIG. 17 ; and 
         FIG. 22  shows a perspective view of a part of  FIG. 21 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention overcomes the limitations of the prior art by providing a 
     All dimensions specified in this disclosure are by way of example only and are not intended to be limiting. Further, the proportions shown in these Figures are not necessarily to scale. As will be understood by those with skill in the art with reference to this disclosure, the actual dimensions and proportions of any system, any device or part of a system or device disclosed in this disclosure will be determined by its intended use. 
     Methods and devices that implement the embodiments of the various features of the invention will now be described with reference to the drawings. The drawings and the associated descriptions are provided to illustrate embodiments of the invention and not to limit the scope of the invention. Reference in the specification to “one embodiment” or “an embodiment” is intended to indicate that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least an embodiment of the invention. The appearances of the phrase “in one embodiment” or “an embodiment” in various places in the specification are not necessarily all referring to the same embodiment. 
     Throughout the drawings, reference numbers are re-used to indicate correspondence between referenced elements. In addition, the first digit of each reference number indicates the figure where the element first appears. 
     As used in this disclosure, except where the context requires otherwise, the term “comprise” and variations of the term, such as “comprising”, “comprises” and “comprised” are not intended to exclude other additives, components, integers or steps. 
     In the following description, specific details are given to provide a thorough understanding of the embodiments. However, it will be understood by one of ordinary skill in the art that the embodiments may be practiced without these specific details. 
     With reference to  FIG. 1 , at least one section of a rope  1 , included between an inlet section  11  and an outlet section  12 , is wound by three revolutions on a pulley  2 . 
     The pulley  2  is composed of at least one disk  21  equipped with a central hole  22  used for centering and joining with a shaft (not shown) connected to a high-efficiency winch (not shown). 
     The inlet  11  and outlet  12  sections of the rope  1  are respectively connected to a working load (not shown) and to a storage device (not shown) according to a tension gradient which established a maximum tension value at the inlet section  11  and a minimum or null tension value at the outlet section  12 . 
     The disk  21  supports the coils of the rope  1  by means of a kinematic chain formed of peripheral supports  3  uniformly connected and distributed along a circumference. 
     With reference to  FIGS. 3 to 7 , each peripheral support  3  is composed of: 
     at least one frame  31 , obtained from an extruded material with U-shaped cross section, in which at least two pair of bushed holes  311  and  312  are housed; 
     at least one crank  32 , formed of a collar-type eccentric  321 , whose internal axis is occupied by a pin  322  at whose ends forks  323  and  324  are placed; 
     at least one rocker-type rod  33 , wherein two bushed hoes  331  and  332  are housed; and 
     at least one connecting rod  34 , obtained from an extruded material with a T-shaped cross section, equipped with at least two bushed holes  341  and  342 . 
     With reference to  FIGS. 8 to 11 , each peripheral support  3  is integral with the periphery of the disk  21  through the frame  31 . The crank  32  is connected to the frame  31  through the pin  322 , this one being keyed-in in the pair of coaxial holes  311 . The rocker-type rod  33  is connected to the frame  31  through a pin  35 , this latter one being keyed-in respectively in the pair of coaxial holes  312  and in the hole  331 . The connecting rod  34  is respectively connected to the crank  32  and to the rocker-type rod  33  through the eccentric  321  keyed-in in the hole  341 , and through a pin  36  keyed-in in the hole  342  and in the hole  332 . 
     The forks  323  and  324 , belonging to the crank  32 , are geometrically configured with a certain offset T (as can be noted, for example, in  FIG. 5 ) with respect to a plane perpendicular to the pin  322  axis. 
     The rope  1  is wound by three revolutions on the pulley  2  through the contact with the back surface of each connecting rod  34 . 
     Each peripheral support  3  is kinematically connected to the two adjacent supports through the union of forks  323  and  324  integral with a crank  32 , respectively with a first fork  324   a  integral with a first adjacent crank  32   a,  and with a second fork  323   b  integral with a second adjacent crank  32   b  (as can be noted, for example, in  FIG. 10 ). 
     Each peripheral support  3  is an articulated mechanism, kinematically equivalent to an articulated quadrilateral, comprising a collar-type eccentric  321 , a rocker-type rod  33  and a connecting rod  34 , this latter one being in contact with the sections of the rope  1 . 
     The kinematic chain composed of the peripheral supports  3 , connected through the forks  323  and  324  integral with each eccentric  321 , makes a discontinuous contact between the rope  1  and the pulley  2  able to make the tension gradient discrete along the section of rope  1  included between the ends  11  and  12 . 
     The kinematic chain composed of the peripheral supports  3 , connected through the forks  323  and  324 , in addition to make a discontinuous contact between rope  1  and pulley  2 , allows making a mobile contact actuated through suitable actuators (not shown) according to an reciprocal motion law. 
     The reciprocal motion of each peripheral support  3  is offset with respect to the reciprocal motion of the adjacent peripheral supports  3 . 
     The offset between the forks  323  and  324  of each peripheral support  3  has an arbitrary value included between 0 degrees and 360 degrees. 
     The pulley  2 , coupled with the kinematic chain formed of the peripheral supports  3 , reaches the object of the invention having made discrete the tension gradient of the rope  1  wound on the periphery of the pulley  2  by several revolutions. 
     In particular, the adopted solution allows: 
     nullifying the tension gradient along each section of rope lacking contact with the peripheral support  3 ; 
     making an helical winding of the rope  1  along a generatrix formed by the contact surface of each connecting rod  34 ; and 
     obtaining a reciprocal and offset motion of each peripheral support  3  by means of a mechanism kinematically equivalent to an articulated quadrilateral, as preferred embodiment obtained with an eccentric rotor and a connecting rod ( FIGS. 2 a , 2 b  and 2 c   ). 
     Further arrangements which are deemed variations of the solution of the present invention are described below. 
     Said reciprocal and offset motion of each peripheral support  3  is made by means of a mechanism kinematically equivalent to an articulated pentalateral device, wherein an additional rod (not shown) allows performing an approximately square-shaped trajectory, by overlapping a further armonic motion. 
     The mechanism kinematically equivalent to an articulated pentalateral device is of the type in which two of the five rods (not shown) are mechanically made through eccentrical rotors equipped with bearings, said eccentrical rotors having independent rotation speeds and predetermined phases, one of said independent rotation speeds being preferably three times the other. 
     The radial profile of each peripheral support  3 , measured in a plane X-Z ( FIG. 9 ), is subjected to an exponential function to be adapted to the tension gradient variable along the rope  1 . 
     The back surface of each connecting rod  34 , in contact with a section of rope  1 , has a profile, measured in a plane X-Y ( FIG. 8 ), with a circumferentially rounded shape (not shown). 
     The kinematic chain formed of the peripheral supports  3  is connected by means of cardan joints or equivalent. 
     Said reciprocal motion can be actuated by cams or mechanical actuators. 
     Said reciprocal motion can also be actuated by electric motors or electromagnetic actuators. 
     Said reciprocal motion is exploited in a winch comprising a device (not shown) capable of storing and quickly releasing, during its tensioning, a certain amount of the rope  1  from the part  11  with high tension, or the part  12  with low tension. 
     Said reciprocal motion is exploited in a winch comprising a device (not shown) capable of adjusting and limiting the tension of the rope  1  from the part  11  with high tension, or the part  12  with low tension. 
     A winch, composed of at least one pulley  2  equipped with peripheral supports  3 , supports and guide a rope  1  wound by one revolution, preferably by three revolutions, said rope  1  being stored in a low tension state  12 . 
     A winch is composed of n pulleys  2  equipped with peripheral supports  3 , at least two of which pulleys are motored. 
     A winch is composed of four motored pulleys  2 , equipped with peripheral supports  3 , said pulleys  2  being arranged on the vertexes of an ideal rectangle. 
     A winch is composed of four motored pulleys  2 , equipped with peripheral supports  3 , said pulleys  2  being arranged along non-mutually parallel rotation axes. 
     Although the present invention has been described with a degree of particularity, it is understood that the present disclosure has been made by way of example and that other versions are possible. As various changes could be made in the above description without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be illustrative and not used in a limiting sense. The spirit and scope of the appended claims should not be limited to the description of the preferred versions contained in this disclosure. 
     All features disclosed in the specification, including the claims, abstracts, and drawings, and all the steps in any method or process disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. Each feature disclosed in the specification, including the claims, abstract, and drawings, can be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features. 
     Any element in a claim that does not explicitly state “means” for performing a specified function or “step” for performing a specified function should not be interpreted as a “means” or “step” clause as specified in 35 U.S.C. § 112.