Abstract:
A carrier frame is for a back load having an extended resilient element that extends in a closed loop and crosses itself in such a way that it forms a shoulder element, an anchor element and a hip element between the crossings. Segments of the element can be moved in relation to each other. The shoulder element has a shoulder fastening for shoulder straps, the anchor element is adapted for support of the back load, and the hip element has a hip fastening for a hip belt. The load is resiliently suspended in the carrier frame, which gives possibility of damping. The back load may be a pack bag in a rucksack, a child seat or another pack.

Description:
BACKGROUND 
       [0001]    1. Technical Field 
         [0002]    The invention regards a carrier frame for back load, e.g. a rucksack, a child seat or another pack. 
         [0003]    2. Background Art 
         [0004]    Traditionally, a rigid frame provided with shoulder straps has been used to fasten and distribute load on a user&#39;s back. A first example is a traditional rucksack where the load is located in a pack bag which is fastened to the frame and turned away from the back of the user. In this case, the frame also reinforces the pack bag in which the load is to be placed. It is known to fasten other load in addition to or instead of a sack to such a frame, e.g. skis, gas cylinders for breathing, a child seat or other rigid objects. Such carrier frames may be provided with a hip belt to distribute a load better between shoulders and hips. The frame is then fastened as close as possible to the user&#39;s back to distribute the load in the best possible manner. Thereby, the user&#39;s movements are at the same time hindered by the rigid frame, and the user gets reduced comfort and efficiency. 
         [0005]    More advanced carrier frames have links and flexible elements. These provide an improved comfort, but with an associated larger complexity and cost. Further, the number of degrees of freedom often limited due to the material, so that sections may be bent in one direction but not lateral to this direction. 
         [0006]    U.S. Pat. No. 5,503,314 discloses a carrier device that moves the load towards the user&#39;s center of gravity to make it possible to carry heavier loads more comfortable with less power consumption. In use, the carrier device transmit load to the user through a breast strap and a hip strap over a helically shaped frame element, where two elements run along the user&#39;s back and cross each other one or several times. This provides a built-in shock damping and flexibility. Additionally, the carrier device has its own adjustable shock absorbing mechanism. The carrier device gives the user better freedom of motion and eliminates compression forces under shoulders, because the shoulder straps are missing or are merely used to hold the load close to the user&#39;s back without transmitting the weight from the load. The device is adjustable to fit different breast sizes and may be used for different purposes, e.g. as a tour sack, for a child seat, a military pack, a fireman&#39;s pack, etc. 
         [0007]    US 2010/0176171 A1 discloses a utility pack with a flexible frame system wherein several flexible frame members engage guides in the pack body to provide the pack with an extended and resilient structure. The frame members may form one or several crossings. In some embodiments there is a floating coupling between the shoulder harness and the pack body to enhance freedom of motion of the wearer. Embodiments may also include flexible frame members directly coupled to a waist harness to shift pack loads to the wearer&#39;s waist and hips. The document also describes a flexible rod having an outer and inner element which gives items structure, durability, flexibility and resiliency. 
         [0008]    The problem to be solved by the invention is to provide a carrier frame that gives improved load capacity and carrying comfort compared to the prior art, while retaining the benefits from prior art. 
       SUMMARY OF THE INVENTION 
       [0009]    According to the invention the problem is solved with a carrier frame for a back load, where the carrier frame is composed of at least one extended and resilient element and comprises at least one crossing where the elements in the carrier frame are moveable in relation to each other. The carrier frame is characterized in that the at least one resilient element is one continuous element that extends in a closed loop and crosses itself in such a way that it forms a shoulder element between an upper frame end and a first crossing, an anchor element between the first crossing and a second crossing, and a hip element between the second crossing and a lower frame end. The shoulder element has a fastener for shoulder straps, the anchor element is adapted for support of the back load, and the hip element has fastening for a hip belt. 
         [0010]    In other words, the resilient element defines a carrier frame formed as a series of loops where each loop is defined such that the resilient element crosses itself. The loops are forming a shoulder element which in use transmits forces from the carrier frame to the user&#39;s shoulders and upper back portion by means of shoulder straps, an anchor element for anchoring of load where the forces are transmitted from the load to the carrier frame and a hip element which transmits load to the user&#39;s hips and/or lower back portion by means of a hip belt. 
         [0011]    The solution enables the hips and shoulders to move freely and independently of each other and also independent of the load, which may be e.g. a pack bag. Additionally, the structure allows an axial twisting of the backbone. This enhances freedom of motion while the pack load is kept stable on the back of the wearer during use. The load is resiliently suspended in the carrier frame, and the solution also gives possibility of damping. 
         [0012]    The resilient element may be a hollow pipe to save weight, and the ends of the element may be connected by inserting them into separate ends of a sleeve at the upper frame end. 
         [0013]    Alternatively, the resilient element may be assembled from a plurality of shorter elements that can be released from each other so that the carrier frame can be disassembled when not in use. 
         [0014]    If desired, the frame may be divided in several loops to further enhance the carrying comfort and/or the loading capacity. 
         [0015]    In a further aspect the invention relates to a carrier system having such a carrier frame. In the carrier system the shoulder element is located in an upper fastening firmly connected to the shoulder straps, the hip element is located in a lower fastening firmly connected to the hip belt, and an anchor fastening is firmly connected to the back load and adapted to transmit forces from the load to the anchor element. 
         [0016]    The upper fastening, the lower fastening and the anchor fastening are preferably pockets of textile, and brackets may be instead of or additionally to the pockets for storing the back load on the anchor element. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]    The invention will be further described in the following by means of exemplary embodiments with reference to the accompanying drawings, wherein: 
           [0018]      FIG. 1  shows the carrier frame enclosed and divided into the elements shoulder element, anchor element (support of load), and hip element. 
           [0019]      FIG. 2  shows the carrier frame in  FIG. 1  provided with a depicted pack bag. 
           [0020]      FIG. 3  shows the carrier frame in  FIG. 2  provided with a carrier system depicted on one side. 
           [0021]      FIG. 4  shows the carrier frame in  FIG. 3  with a complete carrier system. 
           [0022]      FIG. 5  shows the carrier frame in a side view. 
           [0023]      FIG. 6  shows the carrier frame in a perspective view where the crossing points are set out. 
           [0024]      FIG. 7  shows a carrier frame in a front view. 
           [0025]      FIG. 8  shows an exemplary fastening system for a removable/replaceable load in perspective. 
           [0026]      FIG. 9  shows, in front view, an example of a fastening system for a removable/replaceable load. 
           [0027]      FIG. 10  is an overview over the motion possibilities of the system. 
           [0028]      FIG. 11  is an overview of variants of the system. 
           [0029]      FIG. 12  shows the overview in  FIG. 10  with anchor fastening set out (framing of anchor element). 
           [0030]      FIG. 13  shows the overview in  FIG. 11  with anchor fastening set out (framing of anchor element). 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0031]      FIG. 1  shows schematic a carrier frame  10  according to the invention, where one resilient elongated element  12  is bent such that it crosses itself and thereby divide the carrier frame into a shoulder element  20  with an upper fastening  60  for shoulder straps, an anchor element  30  with anchor fastening  70  for supporting a load, and a hip element  40  with a lower fastening  80  for a hip belt. In  FIG. 1  the upper  60  and lower  80  fastenings are shown as pockets of textile. These pockets may alternatively be replaced by straps of cordura or other suitable pliable material that enables attaching shoulder straps  21  to the shoulder element  20  and/or the hip belt  41  to the hip element  40 . In the latter case, the resilient element  12  may itself form the upper and lower fastenings  60  and  80 .  FIG. 7  shows a carrier frame  10  where the elements are not inserted in their respective fastenings. 
         [0032]      FIG. 1  further shows an anchor fastening  70  configured as two pockets  72  and  74 . These pockets may be attached to the load, e.g. to a pack bag  101  as shown in the  FIGS. 2-4 , and disposed around the anchor element  30  as shown in  FIG. 1 . Alternatively, the load may be fastened to the anchor element  30  with brackets. This is further described with reference to the  FIGS. 8 and 9  below. 
         [0033]    The common principle of the embodiments is that a continuous elongated resilient element  12  is configured as a series of loops, where the loops are separated from each other by the resilient element crossing over in the manner of the crossing in the digit 8. A loop defines the shoulder element  20  between an upper frame end and a first crossing. A second loop defines the anchor element  30 , and a third loop defines the hip element  40  in a similar manner. Further crossings may form a fourth and subsequent loops, e.g. one or more comfort elements  50  as shown in the  FIGS. 11E and 13E . 
         [0034]    Preferably, the resilient element  12  is a hollow pipe or a solid metal string, e.g. a steel string. Weight, strength and price decide the specific choice. Plastic or fibre composites may also be used, but many such non-metallic materials break easily when overloaded, and then form sharp edges that can wear unnecessarily on a textile pocket or harm the user. The carrier frame also loses much of its function if the resilient element breaks. 
         [0035]      FIGS. 2-4  show an example of a carrier system  100  using the carrier frame  10 . In this example, the carrier system is a rucksack where the load is located in a pack bag  101 . In use, the shoulder element  20  and the hip element  40  are attached to the user by means of the shoulder straps  21  and the hip belt  41 . The weight of the load is thereby transmitted to the user from the carrier frame  10  through the shoulder element  20  and the hip element  40 . 
         [0036]    The back load is mainly supported on the anchor element  30  through pockets  72  and  74  affixed to the pack bag  101  and disposed around the anchor element  30 . This means that most of the weight from the load is transmitted to the carrier frame through the anchor element  30 . The carrier frame  10  is resilient and damps relative motion between the anchor element  30 , the shoulder element  20  and the hip element  40 . The three elements  20 ,  30  and  40  can further be twisted in relation to each other about a vertical axis which runs substantially along the user&#39;s backbone and separately laterally about horisontal axes as described in greater detail below. The earner frame also enables the user to move hips and shoulders freely and independently of each other and also independently of the back load, which in this example is the pack bag  101 . Additionally, the structure allows an axial twisting of the backbone. This gives a better freedom of motion than other known structures. 
         [0037]      FIG. 5  is a side view of a carrier frame  10 . In this embodiment, the shoulder element  20  and anchor element  30  form a first plane, whereas the hip element  40  lies in a second plane parallel to and displaced from the first plane. The example on  FIG. 5  is intended to illustrate that the carrier frame need not to be flat, but can to some extent be shaped as the back of the user. 
         [0038]      FIG. 6  shows a carrier frame where a first section  92  of the resilient element  12  has an arc  94  disposed over and around a second section  98  of the element  12 . Thereby, the two elements  92  and  98  do not engage each other at the crossing. This may reduce friction and wear at the crossings. 
         [0039]      FIG. 7  shows a carrier frame without fastening means. The resilient element  12  can be bent as described above with reference to  FIG. 1 . Alternatively, the resilient element  12  may comprise several short elements  12   a,    12   b  etc. as shown in  FIG. 7 . The ends of the short elements  12   a  etc. may be connected with sleeves whereby the carrier frame  10  can be assembled before use and disassembled after use. 
         [0040]      FIGS. 8 and 9  show a carrier frame having brackets  31  and  32  on the anchor element  30 . Such brackets may be used to increase the contact surface against a textile pocket ( 72 ,  74  on  FIG. 1 ) which transmits forces from the back load to the carrier frame  10 . This may be appropriate if the resilient element  12  is a relative thin string. Alternatively, corresponding brackets  31  and  32  may be used to fasten other objects than the pack bag  101 . 
         [0041]      FIGS. 10A-F  show several freedoms of motion provided by the design. 
         [0042]      FIG. 10A  shows how the shoulder element may be stretched and compressed in the longitudinal direction independently of the anchor element  30  and the hip element  40 . Correspondingly,  FIG. 10B  shows how the hip element  40  may be stretched and compressed in the longitudinal direction independently of the anchor element  30  and the shoulder element  20 . Thereby the anchor element  30  can be displaced in the longitudinal direction in relation to both the shoulder element  20  and the hip element  40 , so that the user to some extent may bend forward and backward without the load following to the same extent. The resilient element also absorbs shock in the longitudinal direction of the carrier frame, so that the load moves slower in relation to the user and thereby is easier to handle. The load forces are distributed in an advantageous manner between the shoulder element  20  and hip element  40  in that the shoulder element  20  and hip element  40  lie against the user&#39;s back also when the user bows, jumps or is walking such that the carrier frame is compressed and/or stretched as shown in the  FIGS. 10A and 10B . 
         [0043]      FIG. 10C  shows how the shoulder element  20  may be bent laterally relative to the longitudinal axis of the carrier frame, independent of the anchor element  30  and hip element  40 . Correspondingly,  FIG. 10D  shows how the hip element  40  may be bent laterally in relation to the longitudinal axis of the carrier frame, independent of the anchor element  30  and shoulder element  20 . From this follows that the user may move shoulders and hips laterally, independent of each other without the load which is stored in the anchor element  30 , displaced essentially in relation to the user&#39;s center of gravity. This increases the carrier comfort by damping torsional forces between the load and the user&#39;s back, simultaneously as the load is distributed on a advantageous way between the shoulder element and the hip element. 
         [0044]      FIG. 10E  shows how the shoulder element  20  may be twisted around the longitudinal axis of the carrier frame, i.e. substantially along the user&#39;s backbone, independent of the anchor element and the hip element. Correspondingly,  FIG. 10F  shows how the hip element may be twisted along the longitudinal axis of the carrier frame, independent of the anchor element and the shoulder element. Thereby, the structure allows a twisting along the user&#39;s backbone without the load being turned correspondingly around the longitudinal axis. Such a twisting occurs when the user walks normally, i.e. moves the right foot and left arm forward simultaneously, and thereafter the left foot and right arm forward simultaneously. The carrying comfort increases in that the carrier frame  10  is well fastened to the user through the shoulder element  20  and hip element  40 , and thereby a good weight distribution is secured between the user&#39;s shoulders and hips, simultaneously as the load is not turning that much. Thereby the user is spared from compensating for a mass on the back that turns unnecessarily much about the longitudinal axis of the carrier frame. 
         [0045]    The freedoms of motion are to a great extent provided in that sections of the resilient element  12  are slipping over each other in a crossing. In a preferred embodiment the sections of the resilient element  12  are slipping against each other when the frame is twisted, compressed or stretched. In the alternative embodiment in  FIG. 6  the overlying section  92  has an arc  94  that gives extra distance from the underlying section  98 . Alternatively, an underlying section may be provided with a corresponding arc. 
         [0046]      FIG. 12A-F  are corresponding to the  FIGS. 10A-F  with the anchor fastening shown around the anchor element  30 . The  FIGS. 12A-F  are illustrating that the forces are distributed from the load to the carrier frame  10  through the anchor element  30 , and that the anchor fastening  70  holds the anchor element  30  so that most of the motion of the carrier frame occurs in the shoulder and hip elements and also in the crossings between the elements. The freedom of s described with reference to the  FIGS. 10A-F , and thereby the user&#39;s freedom of motion, is therefore largely maintained also when a load is stored on the carrier frame. 
         [0047]    If the load, e.g. a pack bag, is fastened tight to the shoulder element  20 , anchor element  30  and hip element  40 , the elements are connected through the load so that it is no longer possible to move shoulders and hips without the load being drawn with. To achieve the requested freedom of motion the load therefore must substantially be absorbed by the anchor element, whereas the connection between load and the shoulder and hip elements is made looser, e.g. in that a strap or a piece of textile holds the load near the shoulder element without absorbing load. Simultaneously, the shoulder straps and the hip belt hold the shoulder and hip elements, respectively, near the user&#39;s body so that the load is absorbed by the anchor element and distributed on the user&#39;s shoulders and hips through the carrier frame. Thereby any combination of the freedoms of motion described above is maintained. 
         [0048]    Comfort depends of resilience and damping, and without any form of damping the load could start a vibration. An anchor fastening in the form of a textile pocket  70 ,  72 ,  74  as described in connection with  FIG. 12A-F  in many situations gives sufficient damping. The pocket surrounds partly or completely the anchor element  30 . The forces from the anchor element are absorbed in the textile pocket, and the pocket limits how much the anchor element  30  can be deformed by ordinary use, cf. the  FIGS. 12A-F . 
         [0049]    Corresponding textile pockets  60  and  80  may be located correspondingly tight around the shoulders and hip elements and thereby restrict how much the shoulder and hip elements may be deformed by ordinary use. The textile pockets  60  and  80  may still give the desired freedoms of motion in that the resilient element  12  is moveable in the crossings. The pockets  60  and  80  are preferably fastened in the load to stabilize it and give the user a feeling of stability. The fastenings between the pockets  60 ,  80  and the load are not absorbing load and may therefore allow wanted deflections up and down, lateral etc., as shown in the  FIGS. 10 and 12 . 
         [0050]    Damping may also be obtained by alternative damping elements, such as a shock absorber cylinder  33 , for example disposed lateral to the longitudinal direction of the carrier frame as shown in  FIG. 11D . Damping means may alternatively be mounted in the longitudinal direction of the carrier frame or in other elements of the carrier frame. 
         [0051]    The carrier frame also provides a possibility of attachment to the rucksack in that the anchor element is attached to an anchor fastening performed as a first  72  and a second  74  anchor fastening pockets located in the openings, facing each other and with an opening sufficiently wide to let the carrier frame slip into the pockets, cf.  FIG. 2 . In  FIG. 2  the first  72  and the second  74  anchor fastening pockets are attached close to the load (the pack bag  101 ) for precise transmission of forces from the load to the carrier frame. 
         [0052]      FIG. 11A  shows an embodiment where the shoulder straps  21  and hip belt  41  are attached directly to the carrier frame. 
         [0053]      FIG. 11B  shows an embodiment with arcs as an alternative to sharp bends otherwise indicated in the drawings. Sharp bending hardens some materials and thereby give other mechanical properties. Other materials such as composites, glass fibre and carbon fibre are not suited for sharp bending and must therefore be manufactured in a shape typically having more rounded arcs. 
         [0054]      FIG. 11C  shows an embodiment where the anchor element  30  is a double loop  30   a,    30   b.    
         [0055]      FIG. 11D  shows an embodiment where the damping occurs in a damping element  33 , as an example an absorber cylinder as an alternative or additionally to use of the anchor fastening  70  as damping element. 
         [0056]      FIG. 11E  shows an additional comfort loop  50  that provides a further crossing which again may improve the freedom of rotation. 
         [0057]      FIG. 13A-E  show the variants from  FIG. 11A-E  having an anchor fastening  70  located around the anchor element  30 . In  FIG. 13C  the anchor fastening  70  lies around the two loops  30   a  and  30   b.    
         [0058]    The invention is described with a rucksack as example. It may also be used as a general fastening frame for child seat, a military pack etc., as described in the introduction. 
         [0059]    Even if the invention is mainly described for use on human beings, the same principles also apply to animals for pack and as saddle, especially where the back is vulnerable or in another way must be protected against overloading.