Patent Publication Number: US-2021163115-A1

Title: Connecting device comprising a bolted clevis and a deformable ring in the clevis

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to French patent application FR 1913410 filed Nov. 28, 2019, the entire disclosure of which is incorporated by reference herein. 
     TECHNICAL FIELD 
     The subject of the disclosure herein is a connecting device comprising a bolted clevis and a deformable ring in the clevis. 
     Such devices can be used in the aeronautical field notably to fix the end of a strutting spacer or another slender component to another component such as a support structure, in order to transmit a load in the direction of extension of the spacer. Nonlimiting applications can be the attachment or support of floors, equipment, ventral fairings, or the like, to the structure of an aircraft, and, generally, all the couplings where there are plays to be eliminated. 
     BACKGROUND 
     A known device illustrated in  FIG. 1  comprises a clevis  1 , forming a female coupling, at the end of a first component  2  out of the two components to be assembled, for example the slender spacer. The clevis  1  is provided with two flat and parallel cheeks  3 , each of which is passed through by a piercing  4 , the piercings  4  being aligned and of the same radius. The first component  2  is assembled to a second component  5  of the assembly, which can be a plate  6  or another support structure, here at right angles to the first component  2  when the mounting is done, and which comprises a protruding coupling  7  comprising a piercing  8  and forming a male coupling with the clevis  1 . The assembly is accomplished primarily by a bolt  9  with a head  10  and a tightening nut  11  that bear on the outer faces of the cheeks  3 . A rod  12  of the bolt  9  passes through the piercings  4  and  8 , which are then aligned. The assembly is completed by two bushings  13  and  14 , both surrounding the rod  12  and of which the first  13  is disposed in the piercing  4  of one of the cheeks  3 , and the other  14  is disposed in the piercing  4  of the other of the cheeks  3 ; the latter comprises, at one edge, a flange ring  15  protruding around its periphery. 
     A rigid mounting is obtained in the axial direction (X-X) of the rod  12  and of the alignment of the piercings of the bolt  9 , the first bushing  13  being compressed between the coupling  7  and the head  10 , and the second bushing  14  being compressed being the coupling  7  and the nut  9 ; furthermore, the flange ring  15  is compressed between the coupling  7  and the adjacent cheek  3 , which ensures the position of the coupling  7  in that direction. It will also be noted that a ball joint  38  is incorporated in the coupling  7  to allow small adjustments of orientation of the first component  2  relative to the latter. 
     The compressed bushings  13  and  14  help to take up the axial plays in the assembly, but radial plays (in the radial direction R-R at right angles to the axial direction X-X) remain between the rod  12  of the bolt  9  on the one hand, and the ball joint  38  of the coupling  7  and possibly the bushings  13  and  14  on the other hand, even if the latter are compressed. 
     SUMMARY 
     One object of the disclosure herein is a connecting device of the kind mentioned, which is enhanced in this aspect: it is based primarily on the replacement of the bushings of the device described above with a seal that can better fill the gaps that can appear between the main components of the assembly. A better damping of vibrations and noise while the aircraft is in service can be expected. This seal is, moreover, of simpler construction, and it allows a simple and rapid mounting of the assembly, and some flexibility of adjustment of position or of orientation between the two components. 
     A general aspect of the disclosure herein is thus a connecting device between a first component, bearing a clevis with two cheeks provided with aligned piercings, and a second component with an end provided with a piercing, the device comprising, in a state of mounting of the connection, a bolt with a rod that passes through the piercings of the cheeks and the piercing of the end aligned between the piercings of the cheeks in an axial direction, the bolt being tightened on either side of the cheeks; and the device being characterized in that: a washer, bearing on the bolt, penetrates into the piercing of the first of the cheeks; and the device also comprises a seal which, in the connection state, is fixed in the piercing of the coupling, the seal comprises a deformable ring provided with a hole that is passed through by the rod of the bolt, the ring being tightened radially against the rod of the bolt and tightened axially between the washer and the second of the cheeks around the piercing of the second of the cheeks in the mounting state. 
     One important effect obtained in the mounting of the device is a compression of the deformable ring in its axial direction, which then produces an expansion in the radial direction, that can fill the radial gaps in the assembly, above all with the surface of the rod of the bolt. The seal provides a direct and firm link between the two components, by bearing with pressure on at least one of the cheeks and being tightly fitted into the piercing of the male coupling. It further tightens the rod of the bolt. The bushings in the piercings of the cheeks become unnecessary and are eliminated. Small relative movements between the two components remain possible to accept adjustments of position or of orientation, by virtue of the flexibility of the elastomer. The dynamic forces are not accompanied by significant noises or vibrations because of the damping obtained by the elastomer. The ball joint  38  becomes unnecessary. If the material of the ring is not very or not at all compressible (made of elastomer for example, incompressible), a moderate axial compression is sufficient to produce an adequate radial expansion. 
     Another aspect of the disclosure herein is a connecting assembly, capable of giving the above device in the mounted state, and comprising a spacer with two opposing ends, in which the spacer comprises, at at least one of the ends, a clevis with two parallel cheeks provided with piercings that are aligned in an axial direction; wherein the assembly also comprises: an annular seal which comprises a deformable ring provided with a hole; a bolt with a rod that can pass through the hole of the ring and the piercings of the cheeks; a washer that can penetrate into the piercing of the first of the cheeks and on which the bolt can bear; the ring having a first axial end of smaller radius than the piercing of the first of the cheeks, and a second axial end of greater radius than the piercing of the second of the cheeks. 
     According to various optional aspects of the disclosure herein:
         the ring comprises axial ends in alignment with an intermediate part of the ring in the axial direction, which protrude out of the coupling of the second component in the axial direction and which have cross-sections progressively flaring towards the intermediate part of the ring;   the cross-sections of the axial ends of the ring are rounded;   the ring has an approximately elliptical section in which the intermediate part is delimited by a radially inner cylindrical side that is rectilinear in the axial direction of the ring and a radially outer cylindrical side that is rectilinear in the axial direction of the ring, and the axial ends of the ring have apex circular lines which are nearer, in a radial direction, to the radially inner cylindrical side than the radially outer cylindrical side;   the ring has, in a free state, a length, in the axial direction, greater than a distance between the cheeks of the clevis;   the rod of the bolt has a smaller radius than a radius of the hole of the ring in a state of dismantling of the connection, in which the ring is not tightened against the washer;   the ring is made of an essentially incompressible material, particularly rubber or an elastomer;   the seal comprises a bushing surrounding the ring, to which the ring is fixed, and which is fitted without play in the piercing ( 18 ) of the coupling in the state of mounting of the device;   the bushing is provided with a flange ring protruding outward from an edge of the bushing;   the washer has a tapered outer edge, and the piercing of the first of the cheeks has a tapered edge of the same taper angle;   the piercing of a first of the cheeks has a greater radius than the piercing of a second of the cheeks;   the washer is separate from the bolt;   a head of the bolt bears/can come to bear on the washer.       

     Another aspect of the disclosure herein is an aircraft structure comprising the connecting device or assembly, according to the above. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The disclosure herein will now be described in detail by a preferred embodiment thereof, in conjunction with the following figures: 
         FIG. 1 , already described, represents a known clevis connecting device, in cross section through the clevis; 
         FIG. 2  represents an embodiment of the disclosure herein in the dismantled state, in cross section through the clevis; 
         FIG. 3  represents an intermediate state of mounting of this embodiment in the same cross section; 
         FIG. 4  represents the mounted state of this embodiment in the same cross section; 
         FIG. 5  represents a spacer according to the disclosure herein, in a partial cross section of an aircraft; 
         FIG. 6  is a view similar to that of  FIG. 2 , but in perspective. 
     
    
    
     DETAILED DESCRIPTION 
     The device of the disclosure herein is represented ( FIGS. 2 and 6 ) for the same possible application as that of  FIG. 1 , by linking the components  2  and  5 ; the latter is, likewise, provided with a protruding coupling  7 , but in which the piercing  18  is, here, straight and cylindrical and has no ball joint; and the clevis  1  with which the first component  2  is equipped is now replaced by a somewhat different clevis  19 , in which a first cheek  20  bears a first piercing  21 , and a second cheek  22 , parallel to the preceding one, bears a second piercing  23 , of smaller radius than the preceding one. Furthermore, the first piercing  21  has a tapered edge diminishing towards the interior of the clevis  19 . 
     The assembly is then made by a bolt  16  comprising a rod  17 , a head  24  at one end of the rod  17 , and, at the other end thereof, which is threaded, a nut  25 . The nut  25  is intended to bear on the outer face of the second cheek  22  via a washer  26 ; the head  24  is not however intended to bear on the first cheek  20 , but on a washer  27  inserted into the first piercing  21 , and the outer edge of which has a taper identical to the latter. 
     Also, the assembly further comprises a seal  28  comprising a main part which is a deformable ring  29 , here made of elastomer, of a section here that is approximately elliptical and comprises an intermediate part  44 , defined by a cylindrical radially inner side  30  and a cylindrical radially outer side  31  shorter than the preceding one, and two axial ends  32  and  33  at the ends of the intermediate part  44  and protruding in the axial direction of the seal  28 , which coincides with the axial direction X-X already introduced and which is that of the rod (here  17 ) and of the alignment of the piercings (here  21  and  23 ). The axial ends  32  and  33  have rounded, approximatively half-circular cross-sections, and their contour is connected to the ends of the cylindrical sides  30  and  31 . Other forms of the deformable ring would be possible, rounded sections at the longitudinal ends possibly being however preferred to facilitate a gradual tightening and an easier insertion into the clevis  19 . Elastomer is a material that is appreciated here since it is not only deformable but incompressible, very elastic and offers good mechanical resistance to flattening, but other deformable materials, such as polymers and in particular thermoplastics, could be appropriate, depending on the mechanical or thermal stresses that the ring might have to withstand. The seal  28  also comprises an outer bushing  34  to which the ring  29  is fixed by the outer cylindrical side  31 , and which is provided with a flange ring  35  at one end. The radially inner side  30  remains bare in order to contact the rod  17  directly. A central hole of the ring  29 , which is surrounded by the radially inner side  30 , bears the reference  36  and its length extends also in the axial direction X-X. 
     In a completely dismantled state of the device, which is not represented here, the seal  28  is free. A first mounting step consists in or comprises inserting it into the piercing  18  of the coupling  7 . Since the bushing  34  has no play, or has a slight negative play, with the piercing  18 , the fitting is done by press or by a similar means. The seal  28  is then fixed to the coupling  7 , at an axial position determined by the abutment of the flange ring  35  against a flat lateral face of the coupling  7 , and this position remains invariable. 
     The next mounting step consists in or comprises pushing the coupling  7  bearing the seal  28  into the clevis  19  to produce the alignment of the piercings  21 ,  23  and  18  and of the hole  36  at the centre of the ring  29  of the seal  28 , to give the state represented in  FIG. 3 . The distance between the axial ends  32  and  33  in the axial direction X-X of the seal  28  is a little greater than the separation between the inner faces of the cheeks  20  and  22 , which has not prevented the introduction of the seal  28 , by virtue of the flexibility of the elastomer and the rounded form of the axial ends  32  and  33 , by exerting a little force. 
     The final mounting step, giving the state of  FIG. 4 , consists in or comprises installing the bolt  16  and in tightening it. The rod  17  is threaded into the piercings  21 ,  23  and the hole  36  that are aligned, and also through a piercing  37  at the centre of the washer  27 . The fitting has little clearance with the second piercing  23  and the piercing  37 , and a slightly greater clearance with the hole  36  in the loosened state of the bolt  16 . When the nut  25  is screwed, it bears via the washer  27  on the outer face of the second cheek  20  while the head  24  bears on the outer face of the washer  27  and presses it into the first piercing  21  until the tapered faces abut. The ring  29  of the seal  28  has then been compressed in the axial direction X-X between the washer  27  and the first cheek  20  by pushing back its axial ends  32  and  33 , causing it to be expanded in the radial direction R-R. The radial expansion is exerted inward since it is prevented in the opposite direction by the present bearing, since the initial state, of the radially outer side  31  on the outer bushing  34 . The ring  29  is therefore deformed to tighten the rod  17 . It also produces a link that is firm and without clearance, but has some flexibility, between the clevis  19  and the coupling  7  via the tapered washer  27  and the outer bushing  34 , which are respectively fixedly linked to them. The abutment of the tapered faces limits the tightening of the ring  29 . 
       FIG. 4  shows that the axial compression of the elastomer between the second cheek  19  and the washer  27 , combined with the compression of the elastomer tightening the rod  17 , in the absence of clearance between the seal  28  and the piercing of the coupling  7 , and with the modest amount of the clearances between the rod  17  and the piercings  23  and  37 , gives a mounting without clearance and therefore that is particularly unlikely to allow dynamic vibration forces and shocks between the support  6  and the spacer  2 , all the more so since elastomer has good damping properties, since it adapts to the tolerances of form or of dimension of the components of the assembly and since it also will absorb possible small movements of position or of orientation between the two components  2  and  5 . Since the ring  29  is preferably incompressible (if, for example, it is made of elastomer) or almost incompressible, a moderate axial compression is sufficient to produce the sufficient radial expansion to tighten the rod  17 . 
     It is now fitting to describe the mechanical phenomenon exploited by the disclosure herein more at length, that is a conversion of the axial compressive strains in the ring  29  into expanding, especially inwardly expanding, radial strains so that the rod  17  is tightened. A convenient degree of this conversion depends heavily on favorable factors of shape in the arrangement and particularly in the ring  29 . We recommend that the ring  29  has an overall regular shape, without discontinuities of direction or thickness. The edges of the axial ends  32  and  33  join the intermediate part  44  at smooth junctions without sharp angles, like by progressively flaring thereto with a rounded shape. The intermediate part  44  extending between the axial ends  32  and  33  is cylindrical with a constant thickness and constant radius. This allows an alignment in the axial direction of the intermediate part  44  and the axial ends  32  and  33 , thus in the tightening direction, and this also allows a transmission of uniform compressive efforts in the intermediate part  44  which has a uniform thickness. The axial ends  32  and  33  diffuse compressive strains at any thickness of the intermediate part  44 , owing to the regular, almost half-circular, contour of their cross-section, and to the fact they do not abut on nor contact with neighbour parts, particularly the outer bushing  34  and the coupling  7 , because the intermediate part  44  is longer than the outer bushing  34  and than the piercing  18  of the coupling  7 . Let us also remark that the axial ends  32  and  33  have circular apex lines  45  and  46  with a radius closer to the radius of the radially inner side  30  than to the radially outer side  31 , which enhances the inward radial expansion of the ring  29  when it is compressed. 
     All these characteristics contribute to obtaining a sufficient inward radial deformation of the ring  29  when it is compressed, guaranteeing a firm tight of the rod  17  for assemblies having current shapes and dimensions. This result would not be certain with any other elastic ring, especially those, frequently used in industry, having ends provided with flat collars abutting parts of the assemblies. 
     Another beneficial factor is related to incompressibility of the material, that is the capability to be compressed without volume change: rubber and generally elastomers, being perfectly or essentially incompressible, have the property of better converting the axial compressive strains into radial expanding strains, and they are therefore preferred for the making of the ring  29 . 
       FIG. 5  more comprehensively illustrates another aspect of the disclosure herein: a spacer  39  composed, in addition to the first component  2 , which is slender and straight, of two opposing ends  40 ,  41 , of which at least one is equipped with the connecting device already described, notably comprising a clevis  19  equipped with a bolt  16 . The parts linked by one or more spacers  39  and bearing male couplings  7  can be, for example, a stiffened structure  42  of an aircraft at the bottom and a floor  43  at the top; many other applications are possible, the duly constituted spacers  39  at their two ends being therefore able to be considered as link rods, that can transmit a possibly significant force in their direction of extension. The flexibility of the ring  29  notably allows a small misalignment between the hole  36  and the piercings  21  and  23  of the cheeks  20  and  22  of the clevis  19 , by therefore taking up tolerances of position of the elements of the assembly and notably of length of the spacers  39 . A mounting strain on the ring  29  is accepted, but is in principle low compared to the strains experienced in operation. Having to ensure the assembly through complicated measures such as counter-drilling of the clevis  19 , or lengthwise adjustment of the spacer  39 , will be much less commonplace than with the known designs. 
     The washer  27  could be incorporated in the bolt  16  by being made of a piece with the head  24 . The ring  29  could be fixed to the coupling  7  by structure other than the bushing  34 . It could have a section other than elliptical. The construction represented here is considered advantageous for the simplicity of production of the elements and of mounting of the device. Many variant designs or embodiments of the disclosure herein remain possible. 
     While at least one example embodiment of the present invention(s) is disclosed herein, it should be understood that modifications, substitutions and alternatives may be apparent to one of ordinary skill in the art and can be made without departing from the scope of this disclosure. This disclosure is intended to cover any adaptations or variations of the exemplary embodiment(s). In addition, in this disclosure, the terms “comprise” or “comprising” do not exclude other elements or steps, the terms “a”, “an” or “one” do not exclude a plural number, and the term “or” means either or both. Furthermore, characteristics or steps which have been described may also be used in combination with other characteristics or steps and in any order unless the disclosure or context suggests otherwise. This disclosure hereby incorporates by reference the complete disclosure of any patent or application from which it claims benefit or priority.