Patent Publication Number: US-2022232953-A1

Title: Shoulder strap equipped with a shaping frame

Description:
TECHNICAL FIELD 
     The invention aims for a shoulder strap equipped with a shaping frame. It also aims for a bag and load removing equipment comprising such a strap. It also aims for a method for manufacturing such a shoulder strap. 
     It relates to the general technical field of straps for backpacks or packages carried by the human body. 
     PRIOR ART 
     A load transported in a bag is transmitted on the back of the carrier by straps which go over the shoulders of said carrier. If the load is significant, the weight of the bag is mainly transferred to the level of the hips (in the case where a waist belt equips the bag) and to the level of the shoulders of the carrier, who can feel an excessive and uncomfortable pressure at this level of the body. Furthermore, carrying a load leads to postural compensations, and the continuous and regular maintaining of a bad posture can lead to musculoskeletal imbalances and pain. Numerous solutions have been proposed to reduce this uncomfortable distribution of the load on the shoulders of the carrier. 
     Patent documents EP2371232 (ADIDAS) or FR2781135 (ROSSIGNOL) describe, for example, a bag comprising a pair of straps. A portion of the upper part of each strap is constituted by an elastic part which is limited in extension. This elastic part aims to uncouple the backpack from its carrier to, on the one hand, improve comfort by allowing the carrier to feel movements less on their shoulders, generally sudden, when playing sport or while said carrier is moving. 
     Patent document EP0570193 (KARRIMOR) describes a shoulder-piece for the strap of a bag, which comprises an extended element made of synthetic foam comprising one or more sheets made of relatively rigid plastic material mounted on its face extended from the body of the carrier. The shoulder-piece contains several extended strips made of relatively rigid plastic material disposed side-by-side in the direction of the length of the foam element, by being separated by spacings. When such a shoulder-piece is used on the backpack, the transmission surface is increased, which increases the comfort of the carrier and/or the load capacity. Thanks to the extended strips, the load is spread and the shoulder-pieces become flexible. 
     Patent document EP2606763 (WOOHYUNG) describes a shoulder strap of a bag comprising a part which could be filled with air. This air cushion not only allows to reduce the effect of pressure on the shoulder of the carrier, but also, by coming into close contact with the shoulder, to prevent the bag from sliding or from moving laterally. 
     Patent document U.S. Pat. No. 5,961,019 (GLEASON) describes a shoulder strap of a bag provided with a pad allowing to dampen and to distribute the weight of the bag over the shoulders of the user. 
     Patent document EP1499212 (COMPAGNIA DEL VIAGGIO) describes a shoulder strap of a bag provided with an additional member to better distribute the weight of the bag over the shoulders of the user. This additional member is composed of articulated segments. 
     In all the above-mentioned technical solutions, the straps mainly press on the shoulders and the collarbones of the carrier such that the shoulders and the collarbones remain urged. 
     Patent document US2011/108595 (HOAG LANCE) describes an exo-skeletal structure for a backpack. This structure allows to extend all or some of the load to the hips of the carrier. Its design is however particularly complex, cumbersome and must be relatively expensive. 
     Patent document FR3052650 (ERRAFI) describes a bag comprising an adapted right shoulder strap and an adapted left shoulder strap, in use, to be installed respectively at the level of the right shoulder and of the left shoulder of a carrier. A rigidifying frame equips each of the shoulder straps, this frame having a hook-shaped curved upper portion which extends downwards through a longitudinal portion. The frame is made of a material having elastic properties, such that said frame is elastically deformed with a spring effect when the bag is installed on the shoulders of the carrier. The hook-shaped curved upper portion is located, in use, at the level of the shoulder on which is installed the shoulder strap equipped with the rigidifying frame. The longitudinal portion has a segment which is twisted about the longitudinal axis of said longitudinal portion such that, in use, the shoulder strap equipped with the rigidifying frame is flattened against a region of the torso of the carrier other than the shoulder on which said strap is installed, said strap being flattened against the lateral part of the torso, at the level of the flanks, in the region of the hypochondrium and/or the lateral flanks of the carrier such that all or some of the load of said bag is distributed at the level of this support. 
     The frame described in this patent document forms a load distribution accessory which allows to no longer carry all or some of the weight of the bag on the shoulder and the collarbone of the carrier. The weight of the bag is now moved, at least partially, to a support zone which can be further urged than the shoulders, with an acceptable degree of comfort for the carrier. The bag thus seems lighter to carry for the carrier. 
     This frame, although effective, can however lead to a certain impediment for the carrier, due to the shaping of the longitudinal portion. 
     Patent document JP3215380U describes a shoulder strap which is twisted on itself. This twisting is such that the inner surface of the strap which is in contact with the shoulder of the user becomes the outer surface after twisting. And conversely, for the outer surface of the strap which becomes the inner surface in contact with the carrier after twisting. The strap therefore does not have one same inner surface and one same outer surface. This shaping aims to modify the direction of the tension in the strap. However, with the twisting being locally located at the level of the chest of the user, it must provide a particularly uncomfortable impediment for the carrier. 
     An aim of the invention is to overcome this state of affairs. 
     Another aim of the invention is to improve the comfort of the carrier effectively and inexpensively. 
     An additional aim of the invention is to propose a shoulder strap with which the weight of the load is better distributed over the body of the carrier. 
     Also, another additional aim of the invention is to propose a solution for moving all or some of the weight of the bag from the shoulders of the carrier, which is simple, of reduced bulk and inexpensive. 
     Also, another additional aim of the invention is to propose a solution allowing to limit the musculoskeletal issues induced by carrying a load. 
     PRESENTATION OF THE INVENTION 
     The solution proposed by the invention is a shoulder strap adapted, in use, to being installed at the level of a shoulder of a carrier, wherein:
         the shoulder strap comprises a shaping frame having one same inner surface and one same outer surface,   the frame comprises:
           an upper frame portion located, in use, at the level of the shoulder on which the shoulder strap is installed,   a front frame portion which extends the upper frame portion, which front frame portion extends downwards,   the front frame portion comprises a support portion shaped such that, in use, the shoulder strap bears against a support surface of the carrier,   
           along the upper frame portion and the front frame portion, the inner surface of the frame has the shape of a Moebius strip portion, which inner surface is, in use, oriented towards the body of the carrier.       

     With this particular shaping of the frame, which can be similar to a Moebius strip portion, the inventor has observed an increased comfort during the carrying of a load and a better extension of the load towards the support surface of the carrier, compared with a conventional bag not equipped with any shoulder strap according to the invention. The inventor has been able to observe that the load was, in reality, moved towards the center of gravity of the carrier. The carrying is thus more comfortable and more effective. The inventor has also observed that with a bag equipped with such straps, the carrier was capable of walking over longer distances, while being less tired. The posture and the kinematics of walking of the carrier are significantly less altered than with one of the conventional straps, such that said strap has a real added value in terms of ergonomics and reduction of musculoskeletal issues. The shaping frame, the shape of which makes it possible to provide these advantages to the shoulder strap, is simple to manufacture, such that the proposed solution is inexpensive to implement. 
     Other advantageous characteristics of the invention are listed below. Each of these characteristics can be considered individually or in combination with the characteristics defined above regarding the technical problems that they resolve specifically, and can form the subject, if necessary, of one or more divisional patent applications:
         According to one embodiment: the upper frame portion has a first free end;—the front frame portion has a second free end;—the inner surface of the frame has the shape of a Moebius strip portion from the first free end to the second free end, such that said inner surface is twisted not only along the whole front frame portion, but also along the whole upper frame portion.   According to one embodiment, the shape of the inner surface of the frame is geometrically defined by the following characteristics:—the inner surface is caused by a continuous rotation of a segment around its middle, the length of said segment corresponding to the width of said inner surface; and said middle describes a trajectory describing a curve; and which rotation is non-zero and in the same direction along said trajectory.   According to one embodiment, the outer surface of the frame has the same shape as the inner surface of said frame.   According to one embodiment, the trajectory describes a flat curve. The trajectory can thus describe a circular portion, or an ellipsis portion, or a logarithmic curved portion, or a hyperbole portion or an arch portion or a cycloid curve.   According to one embodiment, the trajectory describes a left curve. The trajectory can thus describe a helix portion, or a rational sextic portion, or a non-rational sextic portion.   According to one embodiment, the following characteristics also geometrically define the shape of the inner surface of the frame: the angular rotation speed of the segment, when its middle is moved along the trajectory, is uniform and non-zero along the trajectory.   According to one embodiment, the angular rotation speed of the segment, when its middle is moved along the trajectory, is variable and non-zero along said trajectory.   According to one embodiment, the length of the segment is constant along the trajectory.   According to one embodiment, the length of the segment varies along the trajectory.   According to one embodiment, the front frame portion has a free end having a flared shape.   According to one embodiment, the upper frame portion has a free end curved upwards.   According to one embodiment:—a rear frame portion extends also the upper frame portion, which rear frame portion is adapted to extend, in use, downwards from the torso of the carrier, from the back face of said carrier;—the rear frame portion comprises a support portion shaped such that, in use, the shoulder strap bears against a rear support surface of the carrier located in a back region of the carrier or at the level of a lateral flank of said carrier.       

     Another aspect of the invention relates to load-removing equipment on the human body, comprising a left shoulder strap and a right shoulder strap, each of said straps according to one of the preceding characteristics. 
     Also, another aspect of the invention relates to load-removing equipment on the human body, comprising one single shoulder strap, said strap according to one of the preceding characteristics. 
     An additional aspect of the invention relates to a method for manufacturing a shoulder strap according to one of the preceding characteristics, comprising steps consisting of:—shaping the shaping frame such that the front frame portion extends downwards from the torso of a carrier from the stomach face of said carrier and that the support portion is located on a front face or on a lateral face of the thorax or of the abdomen of said carrier;—equipping the shoulder strap of the shaping frame. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       Other advantages and characteristics of the invention will appear better upon reading the description of a following preferred embodiment, in reference to the appended drawings, made as indicative and non-limiting examples and wherein: 
         FIG. 1  a view of a bag according to the invention, the bag being carried by an individual, as a front view, 
         FIG. 2 a    is a right profile view of a frame of a shoulder strap according to the invention, 
         FIG. 2 b    is a left profile view of the frame of  FIG. 2   a,    
         FIG. 2 c    is a front view of the frame of  FIGS. 2 a    and  2   b,    
         FIG. 3  represents transverse cross-sections of a frame of a shoulder strap according to the invention, according to different embodiment variants, 
         FIG. 4  is a perspective view of a part of the shoulder strap according to one embodiment of the invention, as a transverse cross-section, 
         FIG. 5  is a perspective view of a part of the shoulder strap according to another embodiment of the invention, as a transverse cross-section, 
         FIG. 6  is a perspective view of a part of the shoulder strap according to another embodiment of the invention, as a transverse cross-section, 
         FIG. 7  represents a backpack carried by an individual, as a profile view, comprising shoulder straps according to the invention, 
         FIG. 8  illustrates a way in which the inner surface of the frame is generated, 
         FIG. 9  represents trajectories from the middle of a segment generating the inner surface of the frame, according to different embodiment variants, 
         FIG. 10  represents other trajectories from the middle of a segment generating the inner surface of the frame, according to different embodiment variants, 
         FIG. 11  is a front perspective view of a frame of a shoulder strap according to the invention, in one embodiment variant, 
         FIG. 12  is a rear perspective view of a frame of a shoulder strap according to the invention, in one embodiment variant. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     The invention relates to a shoulder strap which is particularly adapted to equipping load-removing equipment on the human body. By “load-removing equipment”, this means any type of accessory, equipped with one or more shoulder straps and which is carried by the human body. This can be a travel bag, a sports bag, a golf bag, a walking bag, a military bag or firefighters&#39; bag, a schoolbag, a baby carrier, a protective jacket (body armor, minesweeper clothing), etc. Generally, this bag is intended to transport a load: clothes, exercise books, equipment including military equipment, oxygen cylinder, fire hose, books, sport or baby accessories, etc. 
       FIG. 1  represents an item of equipment  1  of the backpack type. This bag  1  is a conventional design. It comprises, in particular, an inner cavity for receiving the load to be carried. It has a rear face which, in use (i.e. when the bag  1  is carried), is in contact with the back of the carrier  2 . 
     To improve the comfort in carrying decreased from the feeling of weight of the load carried, the lower end of the rear face of the bag  1  can possibly extend from each side by an abdominal or stomach belt made of two parts  6 ,  7 , which makes it possible to fix the lower part of the bag  1  around the waist of the carrier. A buckle makes it possible to secure the two parts  6 ,  7  of this belt. The latter is well-known to a person skilled in the art. 
     In  FIG. 1 , the bag  1  comprises a pair of shoulder straps, respectively a right strap  8   a  and a left strap  8   b  which are similar. The bag  1  can however only comprise one single shoulder strap, in which case said bag is called single-strapped. In use, and as illustrated in  FIG. 1 , the right strap  8   a  passes at the level of the right shoulder  12  of the carrier  2  and the left strap  8   b  passes at the level of their left shoulder  15 . The right strap  8   a , respectively left strap  8   b , goes along the front face of the thorax  13  from top to bottom (and possibly from the abdomen  14 , along the length of the strap), then passes through the right lateral face  16 , respectively left  17 , of the thorax  13  (or possibly of the abdomen  14 ) of the individual  2 , until reaching the right side, respectively the left side of the lower part of the back face of the bag  1 . The straps  8   a ,  8   b  are generally flat. Their width is, for example, comprised between 10 mm and 100 mm. 
     Each shoulder strap  8   a ,  8   b  comprises here an adjustment strap making it possible to adjust the length of the shoulder strap  8 . The backpack  1  of  FIG. 1  also comprises a chest strap comprising a right strap part  9 , which extends from the right shoulder strap  8   a , and a left strap part  10 , which extends from the left shoulder strap  8   b . Each chest strap makes it possible for a better adjustment of the position of the bag  1  and of the position of the straps  8   a ,  8   b  according to the anatomy and the morphology of the carrier  2 . An upper end of each shoulder strap  8   a ,  8   b  is fixed (for example, by sewing) to the upper part of the back face of the bag  1 . The adjustment strap is also fixed (for example, by sewing) to the lower part of the back face of the bag  1 . 
     Without the rigidifying frames described above in the description, the straps  8   a  and  8   b  are flexible, i.e. easily deformable, manually. These frames make it possible to shape the straps, and rigidify them. Also, the straps  11   a  and  11   b  are more rigid—or less flexible—with the frames that without these frames, and/or said frames impress their shape on said straps. 
     A frame  3  is represented in  FIGS. 2 a  and 2 b   . To simplify the design, the frame equipping the right strap  8   a  is identical to the frame equipping the left strap  8   b . The right and left frames can however be separate according to the strap that it equips and/or according to the type of bag to be equipped and/or according to the anatomy and/or the morphology of the carrier  2 . 
     According to one embodiment, the frames  3  are thin, i.e. that their transverse cross-section has a width “I” which is greater than their thickness “e” ( FIG. 3 ). As an example, the width “I” is comprised between 5 mm and 80 mm and the thickness “e”, comprised between 0.5 mm and 20 mm. The thin character of the frames  3  gives them lightness, flexibility and elasticity. The unwound length of the frame  2  (length between the ends  300 - 310 ) is, for example, comprised between 100 mm and 1 m. This length depends on the anatomy and/or on the morphology of the carrier, the latter being able to be a schoolchild, a teenager, an adult, and a man or a woman. Of course, this length also depends on the size of the strap  8   a ,  8   b  which is itself adapted to the size of the bag  1 , but also on the morphology of the individual  2 . 
     In  FIGS. 2 a  and 2 b   , the frame  3  is presented in the form of a flat strip, with a rectangular transverse cross-section  23 . By referring to  FIG. 3 , the frame  3  can however have another transverse cross-section, in particular a convex flat cross-section  26 , the flat surface extending from the side of the inside of the bag  1 , i.e. closest to the front face of the thorax  13  and/or of the abdomen  14  of the individual  2  when they carry said bag, the convex surface extending from the side of the outside of said bag; a slightly slim concave or curved cross-section  27  so as to further mold the morphology of the carrier  2 ; an oval or convex-convex cross-section  29 ; a cross-section having longitudinal ridges  43  such that said cross-section has teeth  45  making it possible to rigidify said frame. A square transverse cross-section can also be considered, the frame  3  in this case not being considered as thin. 
     The frame  3  has elastic properties making it possible for it to be elastically deformed, reversibly. This elasticity makes it possible for the frames  3  to best follow the curvature of the straps  8   a ,  8   b , as well as that of the torso of the carrier  2 , with a spring effect, as explained in detail above in the description. 
     The frames  3  can be obtained by molding or machining. They are, for example, made of:—plastic such as a PVC or a urethane polymer (polyurethane);—metal such as stainless steel, aluminum alloy, copper alloy, brass alloy;—composite material such as glass fibers or carbon fibers mixed with a thermoplastic or thermosetting resin; raw timber, stratified timber, laminated timber;—etc. Any other material which suits a person skilled in the art can be used. The frame  3  can also be formed of several materials, comprising for example a core made of a metal material, which core is coated with silicone or another flexible plastic material ensuring an electric insulation in addition to an increased comfort. 
     In  FIGS. 2 a , 2 b  and 2 c   , the frame  3  has an inner surface Si—or wall—and outer surface Se—or wall. The inner surface Si is the surface of the frame  3  which, in use, is oriented towards the body of the carrier  2 . The outer surface Se is the other surface of the frame  3  which is opposite the inner surface Si. It is the same inner surface Si which is oriented towards the body of the carrier  2 , all along the frame  3 , contrary to above-mentioned document JP3215380U. Indeed, in this document JP3215380U, after the twisting of the strap, the inner surface becomes the outer surface and the outer surface becomes the inner surface. 
     The frame  3  has an upper portion  30 , which is located, in use, at the level of the shoulder  12 ,  15  on which is installed the shoulder strap  8   a ,  8   b  equipped with the respective frame  3 . This upper portion  30  is preferably curved in the shape of an arc or of a hook and the curvature of which is adapted to the morphology of the shoulders  12 ,  15  of the carrier  2 . Thus, when the carrier  2  carries the bag  1 , the shoulder strap  8   a ,  8   b  extends above their shoulder  12 ,  15 . The upper portion  30  has a free end  300  (or upper free end). 
     This upper portion  30  extends downwards through a front frame portion  31 . These two portions  30 ,  31  here form one single and same part, without discontinuity. All or some of the front frame portion  31  is installed in the shoulder strap  8   a ,  8   b . It extends, in use, downwards from the torso of the carrier  2 , from the stomach face of said carrier, whatever the anatomy and/or the morphology of said carrier. In  FIG. 1 , the front frame portion  21  extends into the length of the shoulder strap  8   a ,  8   b , to the lower end  80   a ,  80   b  of said strap. In one embodiment, the lower end  310  of the front frame portion  31  (i.e. its lower free end) does not reach the lower end  80   a ,  80   b  of the strap  8   a ,  8   b , the length of the frame  3  being shorter than the length of said strap. In another embodiment, the lower end  310  of the front frame portion  31  is not housed in the strap  8   a ,  8   b , but is located outside of it. In the latter case, an opening is provided in the strap  8   a ,  8   b  making it possible to bring out the front frame portion  31  from said strap. 
     When a frame  3  is associated with a strap  8   a ,  8   b , this takes the shape of said frame. The frame  3  therefore makes it possible to shape the strap  8   a ,  8   b . This property is used, in the scope of the invention, to create new points or zones to support said strap in a region of the torso of the carrier  2 , other than the shoulders  12 ,  15 . 
     In  FIGS. 2 a  and 2 b   , the front frame portion  31  comprises a support portion  32  shaped such that, in use, the strap  8   a ,  8   b  bears against a support surface  24  of the carrier  2  (which can be seen in  FIG. 1 ). The support portion  32  is located on the inner surface S 1  of the frame  3  and bears, flat, directly or via a protective layer of the strap  8   a ,  8   b , against the support surface  24 . The frame  3  is shaped such that the support surface  24  is located on the front face of the thorax  13  or of the abdomen  14  of the carrier  2 . The shaping of the frame  3  can therefore be adjusted, at the time of its manufacture, to take into account the anatomy and/or the morphology of the carrier  2 . In  FIG. 1 , the support surface  24  is located at the level of the chest muscles of the individual  2 , this position giving very good results in terms of comfort for the carrier  2  and in decreasing the feeling of weight from the load carried. It can also be provided to shape the frame  3  such that the support portion  32  acts on a support zone  24  located on a lateral face  16 ,  17  of the thorax  13  or of the abdomen  14 . 
     In the embodiment of  FIGS. 2 a  and 2 b   , the inner surface S 1  of the frame  3  is geometrically caused by the non-zero rotation and in the same direction, of a segment around its middle (which is the center of rotation of the segment), which middle follows a trajectory describing a curve. The inner surface Si can thus have the shape of a Moebius strip portion. 
       FIG. 8  illustrates, from a geometric standpoint, the way in which the inner surface Si is generated. The length of the segment AB corresponds to the width of the inner surface Si (and of the frame  3 ). The middle of the segment AB is referenced M. The trajectory of the middle M is referenced T and describes a curve. The trajectory T defines the longitudinal axis of the frame  3 . The trajectory T is delimited by the point T 0  (which corresponds to the upper free end  300  of the frame  3 ) and the point T 1  (which corresponds to the lower free end  310  of the frame  3 ). The segment AB is here a straight segment, but can be a curved segment, in particular to obtain a non-flat inner surface (concave, convex, etc.) such as illustrated in the variants of  FIG. 3 . 
     The trajectory T of  FIG. 8  describes a two-dimensional curve—2D curve or flat curve—contained in the plane xOy of the coordinate system (O, Ox, Oy, Oz). By referring to  FIG. 9 , the trajectory can describe a circular portion Ta, an ellipsis portion Tb, a logarithmic curved portion Tc, a hyperbole portion Td, an arch portion of a cycloid curve Te, or any other curve moving closer to these without strictly respecting their mathematical equation. This type of curve makes it possible to obtain very good results in terms of comfort and in decreasing the feeling of weight of the load carried. 
     The trajectory T can however be a curve traced in a three-dimensional space—3D curve or left curve—contained in the space (O, x, y, z). By referring to  FIG. 10 , the trajectory can describe a helix portion Tf, a rational sextic portion Tg, a non-rational sextic portion Th, or any other curve moving closer to these without strictly respecting their mathematical equation. This type of curve also makes it possible to obtain excellent results in terms of comfort and in decreasing the feeling of weight of the load carried. 
     In  FIG. 8 , the middle M moves over the trajectory T, between the point T 0  and the point T 1 . Between these two points T 0  and T 1 , the segment AB pivots continuously about its middle M. This rotation is non-zero and in the same direction along said trajectory T. The inner surface Si is thus twisted—or undergoes a twisting movement—not only along the whole front frame portion  31 , but also along the whole upper frame portion  30 . The frame  3  therefore has no straight portion. In  FIG. 8 , the angle that the segment AB makes with the horizontal direction (plane xOy) is referenced “αi”. For example, at the point T 0  of the trajectory T, α 0 =90°, and at the point T 1 , α 1 =45°. Between the points T 0  and T 1 , the angle αi can describe an angular sector of 90°, advantageously 45°, preferably 60°. 
     During its movement between the points T 0  and T 1 , and geometrically-speaking, the rotation speed of the segment AB is not zero and can be constant (uniform or equal angular rotation speed along the trajectory T) or inconstant (variable or different angular rotation speed along the trajectory T). Choosing this rotation speed makes it possible to best adapt to the morphology of the carrier  2  and/or to adjust very precisely the location of the support portion  32 . For the same reasons, the length of the segment AB (which corresponds to the width of the frame  3 ) can be constant or vary along the trajectory T, between the points T 0  and T 1 . For example, as illustrated in  FIG. 11 , the lower free end  310  of the frame  3  can have a flared shape, in the form of a bridle or spatula. This flared shape makes it possible to further maximize the surface of the support portion  32  at the level of the support zone  24 . The same flared shape can be provided at the level of the upper free end  300 . 
     In the embodiment of  FIG. 11 , the upper free end  300  of the upper frame portion  30  is curved upwards. In this configuration, the upper end of the strap  8   a ,  8   b  is raised upwards, which makes it possible to avoid it bearing on the trapezoids of the carrier  2 . The comfort of the carrier  2  is therefore increased. 
     In  FIGS. 2 a  and 2 b   , the outer surface Se of the frame  3  has the same shape as the inner surface Si, which makes it possible to simplify the design of said frame. With the outer surface Se not being intended to come directly in contact with the body of the carrier  2 , it can be considered that it is not the same shape as the inner surface Si. For example, the outer surface Se can be caused by the movement of the segment AB along the trajectory T, but without rotation about the middle M. 
     The shape of the frame  3  makes it possible to orient very precisely the support portion  32  parallel to the support zone  24  of the carrier  2 . The frame  3  will impress a twisting movement on the strap  8   a ,  8   b  such that the latter best follows the curvature of the torso of the carrier  2  and, at the same time, that the support portion  32  reaches a target support zone  24 . This support zone  24  can vary according to the type of bag or load-removing equipment and/or according to the morphology, the size, the type and/or the gender of the carrier  2 . Furthermore, the specific shape of the inner surface S 1  of the frame  3  (and more generally, the specific shape of said frame), makes it possible to offset the straps  8   a ,  8   b  frontwards and/or upwards from the collarbones and/or the shoulders  12 ,  15  of the carrier  2 . As appears in  FIG. 7 , it is provided advantageously that the curvature of the upper frame portion  30  is greater than that of the shoulders  12 ,  15  such that said portion does not bear, or barely bears, against said shoulders and/or the collarbones and/or the trapezoids. The removal of these bearings decreases the static postural compensations of the carrier and therefore the muscular activity necessary for this to be maintained. Furthermore, the freeing-up of the shoulders makes it possible for a more physiological balancing of the arms when walking. This leads to a better stability (in particular: limitation of the bending of the torso of the carrier frontwards, limitation of the winding of the shoulders, limitation of the bending of the head and its projection frontwards). This minor alteration of posture is accompanied by a decrease in muscular activity of the torso of the carrier, by a greater amplitude of rotation of the pelvis, by a decrease in the bending/extension amplitude of the hips and of the ankles, by an increase of the bending/extension amplitude of the knees, by a decrease of the frequency of sprains and by an increase of its length. 
     In traditional bags, the straps  8   a ,  8   b  pass over the shoulders  12 ,  15  and the collarbones of the carrier  2 , and descend against the chest muscles then pass under the armpits. The shoulders  12 ,  15  are therefore the main zones for supporting the straps  8   a ,  8   b , the main portion of the weight of the load being taken up at the level of said shoulders. The shape of the frame  3  makes it possible to orient very precisely the support portion  32 , towards a targeted support zone  24 , and parallel to the latter. The best results, in terms of comfort and of decreasing the feeling of weight of the load carried, are obtained when the support zone  24  is located at the level of the chest muscles of the carrier  2 , preferably in the upper or lateral part of said chest muscles. 
     The action of restricting the strap  8   a ,  8   b  being flattened against the support zone  24 , induces that said strap does not rest directly on a shoulder  12 ,  15 , nor on a collarbone, nor on a trapezoid of the carrier  2 . On the contrary, each strap  8   a ,  8   b  bears against the support surface  24  of the carrier  2 , so as to apply at least one part (even all) of the load of the bag  1  and of the item(s) transported inside, against said support surface. The load is therefore moved over the support surface  24  which can be more urged than the shoulders  12 ,  15  without this causing discomfort. The backpack  1  seems a lot lighter. It has been able to be observed that, when a bag  1  comprising shoulder straps  8   a ,  8   b  according to the invention is used, the load to be carried can be increased by 10% to 80% without significant perception for the carrier  2 . In other words, for one same load, the backpack  1  seems a lot lighter for the individual who carries it. 
     More specifically, and as illustrated in  FIG. 7 , the straps  8  equipped with frames  3 , make it possible to surround the torso of the carrier  2  at the level of two support zones: the first support zone located on a front face or on a lateral face of the thorax  13  or of the abdomen  14  of said carrier (support surface  24 ), and a second support zone  25  located in the back of the carrier  2  (contact zone(s) between the bag  1  and the back). When the carrier  2  installs the bag  1  on their shoulders  12 ,  15 , the frames  3  act as jaws by elastically deforming, with a spring effect, to surround, without injuring them, the torso of the carrier  2 . All or some of the weight of the load is thus moved and distributed at the level of these two support zones  24 ,  25 , relieving the shoulders  12 ,  15  and/or the collarbones and/or the trapezoids of the carrier  2 , of all or some of the weight that they would initially support without the use of the straps  8  equipped with frames  3 . The deformation of the frames  3  is induced by the weight of the bag  1  when this is carried by the carrier  2 . In other words, it is mainly when the bag  1  is carried by the carrier  2  that the frames  3  are deformed to be implemented and bear at the level of the support zone  24 . 
     In the present description, when it is indicated that the shoulder strap  8   a ,  8   b  extends or bears “against” the torso of the carrier  2  (support surface  24 ), this of course means against the torso or against clothing covering the torso. Likewise, when it is indicated that the shoulder strap  8   a ,  8   b  does not rest on a shoulder  12 ,  15 , this means that it could be in contact, at the level of the shoulder, with clothing of the carrier  2 . 
     Different techniques making it possible to secure the frames  3  to the straps  8   a ,  8   b  will now be explained in detail, in reference to  FIGS. 4 to 6 . 
     In the embodiment of  FIG. 4 , the strap  8  comprises a protective layer  80  comprising a quilted or padded layer  81 , for example an elastomer foam layer, covered by an outer layer  82  made, for example, of material, of plastic, of leather, etc. The shoulder strap  8  here has a substantially rectangular cross-section. Inside the protective layer  80 , a cavity  83  is defined which extends into the length of the strap  8 . The cavity  83  has a substantially rectangular cross-section (and is therefore intended to house a rectangular cross-section frame  3 ). The cavity  83  and the protective layer  80  form a sheath having an opening positioned in the proximity of an upper end or of a lower end of the strap  8 . The frame  3  is removably inserted into this sheath, at the level of an opening (or slot) arranged in the strap  8  and opening out, on the one hand, at the level of the protective layer  80  and, on the other hand, into the cavity  83 . The frame  3  can thus be inserted or removed from the strap  8 . When the frame  3  is removed, the strap  8  becomes a conventional strap and, if the frames  3  of the two straps  8   a ,  8   b  are removed, the bag  1  becomes a conventional backpack. The dimensions of the rectangular cross-section of the cavity  33  are preferably slightly greater than those of the rectangular cross-section of the frame  3  to facilitate the insertion or the removal of it. 
     In reference to  FIG. 5 , the frame  3  is disposed not inside, but on the protective layer  80 . The frame  3  is fixed on the protective layer  80  through loops  87  distributed over the length of the strap  8  and which are, for example, sewn or welded onto said strap, on either side of the frame  3 . Abutment parts  88  are formed on the strap  8  to house and hold in position each end of the frame  3 . It is noted that the frame  3  could be fixed by different fixing means: loops, looped strips, Velcro® type hooks, etc. The frame  3  here covers the strap  8 . It covers, more specifically, the outer layer  82 , and is placed on the outer face of the strap  8 , i.e. the face which is not in contact with the body of the carrier  2 . It can however be considered that the frame  3  is placed on the inner face of the strap  8 , i.e. the face which is in contact with the body of the carrier  2 . 
     In  FIG. 6 , the strap  8  has a flat convex cross-section. The strap  8  comprises a protective layer  80 , the outer shape of which also have a flat convex cross-section. Inside the protective layer  81 , a cavity of rectangular cross-section is defined which extends into the length of the strap  8 . The cavity  80  and the protective layer  8  again form a sheath having an opening positioned in the proximity of an upper end or of a lower end of the strap  8 . The frame  3  itself has a rectangular cross-section. The frame  3  is positioned inside the sheath, removably or not. The frame  3  can be glued to the protective layer  80 . The protective layer  80  can also have been molded onto the frame  3  at the time of manufacturing the strap  8 , said frame forming the core of said strap. The thickness of the protective layer  80  between the flat surface of said layer and the frame  3  is very weak. 
     In an embodiment variant, the upper frame portion  30  can be extended by a rear frame portion, which rear frame portion extends, in use, downwards from the torso of the carrier  2 , from the back face of said carrier. The frame  3  has, in this case, an arch or horseshoe shape, comprising a front branch (front frame portion  31 ), a rear branch (rear frame portion) and an upper portion  30 . The upper portion  30  includes an upper portion of the front branch and an upper part of the rear branch. The front and rear branches can be of the same length or of different lengths. 
     Like for the front frame portion  31 , this rear frame portion comprises a rear support portion shaped such that, in use, the shoulder strap  8   a ,  8   b  (or directly, said rear frame portion) bears against a rear support surface of the carrier  2  located in a back region of the carrier (back, lumbar) or at the level of a lateral flank of said carrier. The frame  3  thus has two separate support portions. 
     Along the rear frame portion, the inner surface S 1  of the frame  3  (and possible its outer surface Se) can also be caused by the continuous rotation of a segment about its middle, which center has a trajectory T describing a curve. The rear frame portion is thus twisted. Preferably, the front and rear frame portions are not twisted in the same direction, so as to optimize the supports at the front support surface level of the rear support surface. The rear frame portion can also not be twisted. 
     Such a frame  3  with two branches makes it possible to surround the torso of the carrier  2  at the level of two support zones: a first stomach region where the front frame portion supports and a second back region where the rear frame portion supports. These two support zones are located on the same side of the torso (on the right or on the left of the sagittal plane of the carrier  2 ). When the carrier  2  installs the bag  1  on their shoulders, the front frame portion and the rear frame portion of each frame is deviated at the level of the torso of the carrier  2  and act like jaws by elastically deforming, with a spring effect, to surround, without injuring them, said torso. 
     When each of the straps  8   a ,  8   b  is equipped with a frame  3  with two branches, a double clamping effect is obtained: the frame  3  engaging with the right strap  8   a  acts like a clamp in the right part of the torso and the frame  3  engaging with the left strap  8   b  acts as a clamp in the left part of said torso. All or some of the weight of the load is thus moved and distributed at the level of these two new support zones. 
     A clamping effect can also be obtained (to the right, to the left, or diagonally from the torso), with one single frame  3  with two branches, which makes it possible to equip a single-strapped bag. 
     The arrangement of the different elements and/or means and/or steps of the invention, in the embodiments described above, must not be understood as requiring such an arrangement in all the implementations. In any case, it will be understood that various modifications can be applied to these elements and/or means and/or steps, without deviating from the sense and the scope of the invention. In particular:
         The transverse cross-section of the upper frame portion  30  can be different from that of the front frame portion  31 . The transverse cross-section of the front frame portion  31  can in particular be wider than that of the upper frame portion  30  so as to increase the surface of the support portion  32 .   The frame  3  can possibly have a straight portion, the length of which is marginal with respect to the total length of said frame (≤5% of the total length).       

     Furthermore, one or more characteristics outlined only in one embodiment can be combined with one or more other characteristics outlined only in another embodiment. Likewise, one or more characteristics outlined only in one embodiment can be generalized to the other embodiments, even if this or these characteristic(s) is/are described only in combination with other characteristics.