Patent Publication Number: US-10329003-B2

Title: Integral sail and corresponding method of production

Description:
FIELD OF THE INVENTION 
     The present invention concerns a sail, in particular an integral sail, used both for nautical activities and for other activities that use the energy of air currents as a driving force. 
     The present invention also concerns the method to produce the sail and the means that are needed to execute the method. 
     BACKGROUND OF THE INVENTION 
     Sails for vessels are known, in particular but not exclusively cruise sails and regatta sails, which use the kinetic energy of the wind or canalizations thereof to confer a propulsive thrust to said vessels. 
     Sails are normally bent to a mast and cooperate with a boom at the base, or are bent or cooperate with a mainstay. They are normally obtained by putting together sailcloths according to various theories or practical embodiments. 
     Sails that are known and seen in nautical activities, unless they are small size sails for windsurfing, all have at least an overlap line, in which two parts or sailcloths of a sail are stably joined together. 
     The overlap line, especially where the nautical activity has to exploit to the utmost the thrusting action of the wind, entails poorer performance, although limited. 
     It is therefore a disadvantage of this type of known sail, as used in cruise and regatta vessels, that the overlap lines contradict the content of the patents that should protect said sails, but in practice give valid results only on paper. 
     Furthermore, one problem of known sails as used in cruise and regatta vessels that arises in nautical activity is the continuity of the surface. This is a performance factor, and even small discontinuities, creating small vortexes, create an overall drop in performance of the sail. Such discontinuities can be created, for example, by the conformation of the material used, or by air bubbles trapped in the resin or glue that makes up the surface on which the wind flows. In order to eliminate the loss in performance that these discontinuities entail, it is therefore necessary, for example in a regatta, to try, obsessively and painstakingly, to recover each and every feature that can give even a minimally better performance. 
     Another disadvantage of known sails as used in cruise and regatta vessels is the construction of the sail in terms of strength and cost, especially where complex machines have to be used to make the sail and where, apart from the complex machines, the sail then has to be completed manually (for example by overlapping segments of sail). 
     Apart from the uncertainties of the auxiliary human intervention, the costs of such a sail increase, reducing the possibility of access to such high performance sails. 
     There is also the factor of strength (and conformation) of the sails: it is well known that sails are studied and made according to precise ranges of specific winds. 
     Document EP-A-1.114.771 describes a composite material for making a sail, comprising a pair of thin polymer films, suitable to obtain a sandwich inside which a layer is inserted, consisting of a two- or three-dimensional mesh. The known composite material also provides two layers of individual fibers, not parallel and mutually intersecting, disposed on each face of the mesh, each in direct contact with a respective flexible polymer film. The layers are bound to the mesh and the respective flexible films by means of a glue, and by carrying out a calendering operation. 
     Document U.S. Pat. No. 6,302,045 (US&#39;045) describes a molded three-layer sail, obtained by rolling together three reinforced triangular layers of film in a mold. Each triangular layer is designed for a respective corner of the sail, that is, tack corner, head corner and clew corner. Each layer consists of a plurality of triangular parts that start from a respective one of the three corners of the sail, so that the parts in each layer overlap in the body of the sail. Each triangular layer includes a plurality of primary reinforcement elements in the form of threads, attached to one side of a film by means of a layer of adhesive applied to the film. These reinforcement elements in the form of threads run parallel to and distanced from each other, parallel to a long side, from the peak of the triangle. Possibly, additional transverse reinforcement threads or elements may also be present. With the construction proposed in US&#39;045, the parallel reinforcement threads of each triangular layer are transverse and intersect with the threads of the other triangular layers, because the threads run from a respective peak of the triangular layer, which for the three triangular layers will be respectively the tack corner, the head corner and the clew corner, which cannot overlap. 
     The present invention therefore has a plurality of aims and purposes, all suitable to overcome the limits of the state of the art as identified above, and also to give other advantages as will be evident in the following description. 
     It is therefore one purpose of the present invention to obtain a truly integral sail, that is, without external overlapping of two or more important parts of the sail. 
     It is also a purpose of the present invention to obtain a sail having a smooth surface on both sides and hence without discontinuities, even small ones, created by possible air bubbles or other in the material (resin or glue) that makes up the surface on which the wind flows. 
     It is also a purpose of the invention to obtain sails suitable to be used in a range of winds, also comprising very fast winds. 
     Another purpose of the present invention is to perfect a method that allows to obtain sails with operative continuity, simply and fast. 
     It is also a purpose to obtain sails having a profile suitable both for the type of sailing for which they are designed, and also for the type of wind for which they are made. 
     The Applicant has devised, tested and embodied the present invention to overcome the shortcomings of the state of the art and to obtain these and other purposes and advantages. 
     SUMMARY OF THE INVENTION 
     The purposes and advantages which will be made clear hereafter, and also others, are obtained by a sail and a respective method for obtaining said sail according to the main claims. The connected dependent claims protect variants of or improvements to the main idea. 
     In accordance with the above purposes, a sail according to the present invention is created so as to have on each of its two faces on which the wind flows a smooth or substantially smooth layer, with a film or consisting of a thin continuous film of flexible material, for example polymer, in particular plastic polymer, which can be rolled or extruded, or spread or sprayed, which constitutes the interface in contact with the wind. 
     According to some forms of embodiment of the present invention, the layer of thin and continuous film of flexible material can weigh from 15 g/m2 to 50 g/m2, advantageously between 18 g/m2 and 35 g/m2. 
     Applicant has found that this selection in the specified range of weight of the thin and continuous film of flexible material can determine an advantageous and surprising technical effect in terms of strength and resistance to atmospheric agents, indeformability and containing the weight of the integral sail described here. 
     Between the two layers of continuous film thus provided, which make up the more external layers of the layered structure which makes up the sail, two or more layers of fibers are provided, parallel and adjacent, of resistant material, such as for example aramid fibers, for example Kevlar®, or polyethylene fibers, for example UHMWPE, modified polyethylene, glass, polyester or carbon fibers, or mixed fibers, for example of those listed here, to compensate for the deficiencies of one material or the other. 
     According to some forms of embodiment described here, at least one of the first layers of parallel fibers cooperating with a first external layer of film provides its fibers disposed parallel also to the fibers of at least another layer of parallel fibers cooperating with said first external layer of film or with a second external layer of film. 
     In one form of embodiment, the fibers are disposed parallel to the base, so as to contain horizontal tensions. 
     According to a variant, the fibers are disposed parallel to the leech or luff, in order to contain the vertical tensions. 
     According to another variant the fibers are positioned oriented toward the center of load of the sail, so as to contain the tensions due to radial thrusts that start from said center. 
     According to a variant, the fibers are disposed according to the two variants indicated above in order to contain the tensions in a compound form. 
     In an intermediate position reinforcement fibers are disposed, individually or in adjacent groups, which serve to reinforce the sail according to the composite lines of force that are generated on the surface of the sail. 
     In the case of split fibers, the invention provides that the structural continuity is obtained by partial overlapping thereof. 
     According to the invention, in cooperation with the respective external layer and the parallel fibers that cooperate with it, at least one layer of thermofusible glue is provided. 
     The thermofusible material can be put between external layer and layer/layers of parallel fibers, or put in cooperation only with the layer/layers of parallel fibers, or again a combination of these positions. 
     In this way two stratified semi-components are obtained, each comprising an external layer, at least one layer of thermofusible glue and a layer, or several layers, of parallel adjacent fibers. By combining the stratified semi-components, between which the reinforcement fibers are interposed, a semi-worked piece of the layered structure is obtained, which takes the name of multilayer sandwich. 
     The integral sail according to the present invention is obtained by subjecting the multilayer sandwich to pressure and heating. The heating operation is intended to melt the layer or layers of thermofusible glue, so as to bind together the components comprised between the two external sheets or layers. 
     In order to confer on the integral sail the desired wing shape, the method according to the invention provides to generate to one side a mother sail, having the desired internal profile, onto which the multilayer sandwich is positioned before it is subjected to pressure and heating. 
     The mother sail can have any shape whatsoever, for example flat and planar or shaped according to the specific requirements of use. 
     To facilitate obtaining the wing profile, the bundles of parallel fibers can be positioned according to the individual curves that they must possess when the sail is complete. 
     In order to subject the sail to the desired pressure and heating, the mother sail is inserted, after the multilayer sandwich has been positioned on top of it, inside a watertight sack. 
     Then, a vacuum is created inside the watertight sack and subsequently the whole thing is heated. 
     In this way an integral sail is obtained, in a single body, flexible and light, which achieves all the intended purposes and others again. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other characteristics of the present invention will become apparent from the following description of some forms of embodiment, given as a non-restrictive example with reference to the attached drawings wherein: 
         FIG. 1  shows an example, in section, of the layered structure of an integral sail made according to the present invention; 
         FIG. 2  shows an example of how to dispose reinforcement fibers that are used to contain composite lines of force; 
         FIG. 3  shows the pre-disposition of the semi-components to obtain a multilayer sandwich from which the layered structure in  FIG. 1  is obtained; 
         FIG. 4  shows the sandwich in  FIG. 3  after the pressure and heating operations; 
         FIG. 5  shows how the pressure is applied and how the sail in  FIG. 1  is shaped; 
         FIG. 6  shows an example, in section, of a variant form of embodiment of the layered structure of an integral sail made according to the present invention; 
         FIG. 7  shows the sandwich after the pressure and heating operations according to the variant form of embodiment in  FIG. 6 ; 
         FIG. 8  shows an example, in section, of another variant form of embodiment of the layered structure of an integral sail made according to the present invention. 
     
    
    
     DETAILED DESCRIPTION OF SOME FORMS OF EMBODIMENT 
     We shall now refer in detail to the various forms of embodiment of the present invention, of which one or more examples are shown in the attached drawing. Each example is supplied by way of illustration of the invention and shall not be understood as a limitation thereof. For example, the characteristics shown or described insomuch as they are part of one form of embodiment can be adopted on, or in association with, other forms of embodiment to produce another form of embodiment. It is understood that the present invention shall include all such modifications and variants. 
     With reference to the attached drawings, a sail  10  according to the present invention has a layered structure comprising two external layers, first  11  and second  111 , comprising a thin film that includes polymer material, in particular polymer plastic, for example polypropylene or polycarbonate or other material suitable for the specific purpose required on each occasion. 
     In possible forms of embodiment, which can be combined with all the forms of embodiment described here, the two external layers, first  11  and second  111 , can be formed by fibers, or by rolled material or net reinforced with nonwoven fabric, for example spread or sprayed. For example, the fibers can be chosen from a group comprising fibers of: carbon, aramid, for example Kevlar®, polyethylene, for example UHMWPE, modified polyethylene, glass, polyester or mixes thereof. 
     The base material of the external layers, first  11  and second  111 , can be protected by lining them with a polymer material, in particular polymer plastic, which can for example be spread or sprayed, such as, as mentioned above, polypropylene or polycarbonate or other material suitable for the specific purpose required on each occasion. In particular, the material that is used for protection is provided to guarantee strength against abrasion and to protect against atmospheric factors harmful to the preservation of the sail. 
     The layered structure is obtained from a multilayer semi-worked piece or sandwich  20 , which is subjected to pressing and heating. 
     In the case shown here, the sandwich  20  is defined, by way of example, by two semi-components  21 ,  121 , which in this case are reciprocally symmetrical and specular with respect to a median line M of the sandwich  20  ( FIG. 3 ). 
     It must be remembered that if it is necessary to contrast behaviors of the vessel, or in the case of particular regattas, the two semi-components  21 ,  121  may not have the same composition. 
     In this case, on the surface of each external layer  11 ,  111  which, when the sail  10  is complete, will face toward the inside of the sandwich  20 , a first layer of thermofusible glue  14 ,  114  is applied, by depositing a film of material or by spraying. 
     On each first layer of thermofusible glue  14 ,  114  a first layer of parallel fibers  12 ,  112  is put. The fibers of each of the first layers of parallel fibers  12 ,  112  are disposed parallel with respect to each other, that is, one-directional, without crossing, and are disposed adjacent to each other according to a predetermined orientation on the basis of the direction of the tensions or thrusts or loads that they have to support. In particular, each first layer of parallel fibers  12 ,  112  can be considered a panel of one-directional fabric formed by the parallel and adjacent fibers. In possible implementations, the fibers of each first layer of parallel fibers  12 ,  112  are not only parallel but are also adjacent directly in contact with each other, therefore essentially without providing reciprocal interspaces. 
     According to some forms of embodiment, which can be combined with all the forms of embodiment described here, at least a first layer of parallel fibers  12  cooperating with the first external layer  11  provides its fibers not only parallel with respect to each other as described above, but also disposed parallel to the fibers of another first layer of parallel fibers  112  cooperating with the second external layer  111 . 
     According to a variant, on each first layer of parallel fibers  12 ,  112  a second layer of thermofusible glue  214 ,  314  can be deposited. 
     Several layers of parallel fibers, also differently oriented, can also be provided. 
     It also comes within the spirit of the invention to provide only the second layers of thermofusible glue  214 ,  314 , without the first layers of thermofusible glue  14 ,  114  disposed between corresponding pairs comprising an external layer  11 ,  111  and the contiguous first layer of parallel fibers  12 ,  112 . 
     In this way two semi-components  21 ,  121  are created, each defined by an external layer ( 11  or  111 ), by at least one layer of parallel fibers ( 12 ,  112 ,  212 ,  312 ) and by at least one layer of thermofusible glue ( 14 ,  114 ,  214 ,  314 ). 
     In correspondence with the median zone of the sandwich  20  ( FIGS. 3 and 4 ), reinforcement fibers  13  are positioned, suitable to contain the lines of force and tensions which, in use, are generated on the surface of the sail  10  under the thrusting action of the wind. 
     In this case, the shape of the sandwich  20  is defined by the two semi-components  21 ,  121  and by the reinforcement fibers  13 , interposed between them. 
     The reinforcement fibers  13  can be organized in continuous bands or strips, and can define a whole layer of the sandwich  20 , or only parts of it. 
     For example, the reinforcement fibers  13  can be provided distributed in reinforcement layers, at intervals with respect to the layer of parallel fibers  12 ,  112 ,  212 ,  312 . 
     Furthermore, reinforcement fibers  13  of one specific reinforcement layer can be all parallel to each other. Moreover, reinforcement fibers  13  of one reinforcement layer can be parallel to reinforcement fibers of another reinforcement layer. 
     Furthermore, in possible alternative implementations, the reinforcement fibers  13  can be configured crossed, in a reinforcement mesh or grid. 
     The reinforcement fibers  13  can be uninterrupted, or formed by segments. 
     If segments of reinforcement fibers  13  are used ( FIG. 2 ), they will be provided overlapped in their incident terminations  19 . 
     If one semi-component  21 ,  121  comprises other layers of parallel fibers apart from the first layer of parallel fibers  12 ,  112 , such layers (that is, second layers of parallel fibers  212 ,  312 , shown by dashes in  FIG. 3 , and others, not shown in the drawings) can all be oriented in the same direction, or at least one of the other layers of parallel fibers can be oriented in a different direction, so as to contain tensions different from those contained by the first layer of parallel fibers  12 ,  112  of the respective semi-component  21 ,  121 . 
     To give the desired shape to the sail  10 , as required by its size and by the range of winds that it must support, it is possible to deposit the layers of parallel fibers  12 ,  112  on corresponding first  11  and second  111  external layers, taking this into account. 
     When the sandwich  20 , which in  FIG. 3  is shown in an intermediate condition during the production of the sail  10 , is subjected to pressure and heating, a single element is obtained in which the glue material of each layer of thermofusible glue  14 ,  114 ,  214 ,  314 , as it melts, invades all the interstices of the layers of the sandwich  20 , binding the latter in a structure with a single integral body ( FIG. 4  and enlarged detail of  FIG. 4 , considering, to ensure a better comprehension, that the proportions might not be respected), that is, without external discontinuities. 
     To apply the desired pressure on the sandwich  20 , which together with said heating produces the integral body cited above, the method to make the sail  10  provides to use a mother sail  15  having a profile and shaping mating with those of the finished sail  10 . 
     After the sandwich  20  as described above has been prepared, during which time the final or almost final shape of the sail  10  is conferred upon it, the sandwich  20  itself is deposited on the mother sail  15 . 
     The latter can be a flattened plane shape or shaped and have shaping lines  16  ( FIG. 5 ), which create the desired spatial conformation that the sail  10  will have once completed. 
     At this point, the mother sail  15  on which the sandwich  20  is positioned, still in a state where its components are in practice disposed in the desired manner but substantially not subject to reciprocal constraints, or subject to weak constraints, is inserted inside a watertight sack  17 . 
     By means of a pump  18 , the air inside the watertight sack  17  is aspirated, to create inside it a depression and subject it to a vacuum condition. 
     The depression thus determined creates a desired and intense pressure, in practice distributed uniformly on the surfaces that make up the sandwich  20 , which adheres to the mother sail  15  to assume the desired conformation thereof. 
     At the same time, the watertight sack  17  is hit with hot air, or heated steam, at a temperature such as to determine a substantially uniform heating of the sandwich  20  and sufficient to melt the glue of the layers of thermofusible glue  14 ,  114 ,  214 ,  314  and make it migrate. 
     As well as with hot air hitting the watertight sack  17 , heating can be carried out in other ways too: for example it may be provided that the watertight sack  17  has electric resistances which when activated give heat to the content of the watertight sack  17 . 
     The melted glue material, once everything has cooled, allows to generate an integral body as described above. 
     Furthermore, the integral body that makes up the sail  10  has smooth external surfaces, without even the slightest imperfection, discontinuity of material or depressions at any point. 
       FIGS. 6 and 7 , in which the proportions of the components might not be respected, to ensure a better comprehension, are used to describe forms of embodiment where the fibers of each layer of parallel fibers  12 ,  112 ,  212 ,  312  are organized and grouped together in threads that define a plurality of strips or bands according to a desired, repeatable and modular conformation. In particular, according to some forms of embodiment described here, each layer of parallel fibers  12 ,  112 ,  212 ,  312 , instead of consisting of a panel of one-directional fabric formed by said parallel fibers, can be formed by a plurality of strips or bands of one-directional and parallel fibers  22  disposed parallel and adjacent to each other, which in particular can be for example at intervals or reciprocally distanced by a predefined interspace, or separation, which can be constant or different between the different strips  22 . 
     In particular, the strips of one-directional and parallel fibers  22  can be laid or deposited above the two external layers, first  11  or second  111 , and subsequently the integral sail  10  can be made as described above. 
     In some forms of embodiment described here, the strips of one-directional and parallel fibers  22  can be disposed adjacent to an interspace or separation, which can be chosen between 0 mm and 20 mm. It is not excluded that some strips of one-directional and parallel fibers  22  can also be adjacent to and in contact with each other during the depositing and laying process. 
     In some possible implementations, the strips of one-directional and parallel fibers  22  can extend uninterrupted from one side of the sail to the other, from one end to the other and from one corner to the other. 
     In possible implementations, the strips of one-directional and parallel fibers  22  can be formed of a synthetic material, in particular chosen from a group comprising: carbon, aramid, for example Kevlar®, polyethylene, for example UHMWPE, modified polyethylene, glass, polyester 
     In particular, the strips of one-directional and parallel fibers  22  can be formed in turn of one-directional and parallel threads  23  consisting of fibers of the material as above (see for example the enlarged detail in  FIG. 6 , considering that, to ensure a better comprehension, the proportions might not be respected), said threads  23  having a much smaller diameter than that of the one-directional fibers of the layers of parallel fibers  12 ,  112 ,  212 ,  312  described using for example  FIGS. 1-5 . 
     In possible forms of embodiment, the threads  23  that make up the cited strips of one-directional and parallel fibers  22  can be disposed adjacent directly in contact with each other, without interspaces or intervals. 
     In some forms of embodiment described here, the strips of one-directional and parallel fibers  22  can have a width that can be chosen between 5 mm and 50 mm, for example from 9 mm to 16 mm as explained by way of example hereafter. For example, each of the strips of one-directional and parallel fibers  22  can be obtained from individual yarns, each consisting of said threads  23 . For example, it is possible to use individual yarns, for example each from 1000 to 5000 dtex (decitex), for example 4000 dtex. In particular, each of the individual yarns that can be used can have a diameter or width for example from 3 mm to 7 mm. 
     As an example of a possible spread ratio, it may be indicated that, starting from a carbon filament of 4000 dtex and 3 mm wide, this can be spread to obtain a strip with a width in a range for example from 9 mm to 16 mm. 
     To obtain the strips of one-directional and parallel fibers  22 , each individual yarn as above is opened, that is, singularized in the threads that make it up, and widened or spread, so as to give the desired width of the strips of one-directional and parallel fibers  22  as above. 
     In possible forms of embodiment, the threads  23 , once the yarn has been opened and spread, can be provided on several overlapping planes, for example 2 or 3 planes of overlapping threads, one-directional and parallel, as described for example with reference to the enlarged detail in  FIG. 6 . This can be obtained by properly carrying out the process of singularizing and spreading the individual yarn as above. As another possibility, it may also be provided that the threads of the yarn opened to define the strips of one-directional and parallel fibers  22  are all on the same plane, always one-directional and parallel. 
     We maintain that the strips of one-directional and parallel fibers  22  described here essentially obtain the bearing structure of the sail in question, reinforcing the body of the sail, and can be positioned three-dimensionally above one of the two external layers, first  11  or second  111 . The other of the two layers  111 ,  11  will in turn be positioned above the strips of one-directional and parallel fibers  22 , oriented according to the needs of each individual sail. 
     Also in the forms of embodiment described using  FIGS. 6 and 7  it can be provided to use one or more layers of thermofusible glue  14 ,  114 ,  214 ,  314  which, when they melt, bind the various components described above, defining a structure in a single and integral body, as already described for example with reference to  FIG. 4  and the respective enlarged detail. 
     In possible forms of embodiment, the strips of one-directional and parallel fibers  22  have a limited thickness, that is, they are very thin. In particular, the strips of one-directional and parallel fibers  22  are so thin that they allow the glue of the layers of thermofusible glue  14 ,  114 ,  214 ,  314  to penetrate through them, passing through the interstices between the threads and fibers that make them up, advantageously filling them, so as to obtain the desired sandwich structure in a single body. 
     The forms of embodiment described in particular using  FIGS. 6 and 7  make the sail even more indeformable, at the same time considerably limiting the weight, to the greater advantage, for example, of performance. 
     In possible forms of embodiment described using for example  FIG. 8 , which can be combined with all the forms of embodiment described here, the internal structure of the sail can be integrated with one or more meshes or nets  24 , advantageously reinforced with nonwoven fabric, for example spread, or other fibers, woven, overlapped or distributed in a directioned or statistical manner. This possible form of embodiment with one or more meshes or nets  24  can be combined both with forms of embodiment described using  FIGS. 1-5 , and therefore with layers of parallel fibers  12 ,  112 ,  212 ,  312  formed by adjacent and parallel fibers, and also with forms of embodiment described using  FIGS. 6 and 7 , and therefore with layers of parallel fibers  12 ,  112 ,  212 ,  312  formed by strips  22 , providing in combination the presence of reinforcement fibers  13 , and also one or more layers of thermofusible glue  14 ,  114 ,  214 ,  314 . 
     In some forms of embodiment, which can be combined with all the forms of embodiment described here, a mesh or net  24  as described above can be provided to function as the mother sail  15  in the method of production as described above. Essentially, therefore, the mesh or net  24  can be used as a mold or form to construct the sail according to the present description and, at the end, remains an integrating part of the body of the sail. 
     It is clear that modifications and/or additions of parts may be made to the sail  10  and the corresponding production method as described heretofore, without departing from the field and scope of the present invention. 
     It is also clear that, although the present invention has been described with reference to some specific examples, a person of skill in the art shall certainly be able to achieve many other equivalent forms of integral sail, having the characteristics as set forth in the claims and hence all coming within the field of protection defined thereby.