Pivotable pack frame apparatus

BACKGROUND

The following relates generally to support systems for packs and specifically to a multi-piece pivotable support frame for a backpack.

Historically, external frame pack designs have been made from tubes made of aluminum or another light, rigid material. These packs are good for bearing heavy loads and directing the loads to the hips of the wearer. Pack frames for external frame packs are typically spaced away from the wearer's body due to the rigid shapes used. Skiing, hiking, running, and other dynamic activities may be more difficult using a non-conforming pack due to swaying of the pack (even when strapped to the wearer) and the weight of the pack being spaced from the wearer's body. The spaced center of gravity of the pack from the wearer's body may throw the wearer off-balance or cause unnecessary fatigue by its swaying and other motion relative to the wearer's body.

More recently, internal frame packs have been implemented which help to keep the load of the pack closer to the wearer's body using contoured shapes. They are designed to hold less weight and their contours may limit the range of motion of the wearer. Internal frame packs are therefore designed to balance the competing interests of weight-bearing capacity and rigidity of the pack against the comfort and mobility of the wearer, but fail to optimally address both needs at once.

Some pack frames comprise pivoting portions that attempt to follow the wearer's body through movements, such as through pivoting strap connections to a rigid frame. They fail to provide sufficiently for flexion and extension of the user's spine. For this and other reasons, these frames do not feel like a natural extension of the wearer. Furthermore, adding joints between portions of these pack frames tends to overly reduce rigidity and causes wearers to have to exert more force to keep the pack properly oriented on their backs.

SUMMARY

According to at least one embodiment, a pack frame apparatus is disclosed. The pack frame apparatus may comprise a first frame portion configured to be secured to a backpack and a second frame portion configured to be secured to the backpack. These first and second frame portions may provide structural rigidity to the backpack when secured to the backpack. The first frame portion may be configured to be secured to shoulder straps of the backpack, and the second frame portion may be configured to be secured adjacent to a waist strap of the backpack. The apparatus may also include a joint joining the first and second frame portions to allow relative pivotal movement of the first and second frame portions around a first axis and to allow resilient relative pivotal movement around a second axis.

The first axis may be oriented approximately normal to a coronal plane, and the second axis may be approximately parallel to the coronal plane.

The joint may comprise a resilient member positioned between the first and second frame portions. The joint may further comprise a rigid member, wherein the resilient member is positioned between the rigid member and at least one of the first and second frame portions. In some embodiments, the joint may further comprise a rigid member positioned between the resilient member and at least one of the first and second frame portions. In yet further embodiments, the joint may be biased to orient the first and second frame portions in a default relative orientation due to resilience of the resilient member.

The joint may be removably attached to the first and second frame portions. The joint may also be biased to orient the first and second frame portions to a default relative orientation. The joint may have uneven thickness around the first axis. At least two portions of the joint may interlock in a default relative orientation of the first and second frame portions. The joint may interlock with at least one of the first and second frame portions in a default relative orientation of the first and second frame portions, and the joint may be configured to selectively tighten and loosen the joining of the first and second frame portions.

In another exemplary embodiment, a flexible pack is provided, comprising an upper frame configured to be positioned in the pack adjacent to a torso portion of a user above the user's waist; a pair of shoulder straps configured to attach to the upper frame and wrap around the shoulders of the user; a lower frame configured to be positioned in the pack adjacent to a torso portion of a user adjacent to the user's waist; a waist strap configured to attach to the backpack adjacent to the lower frame; a storage pouch portion attached to at least one of the upper and lower plates which is adapted to removably hold equipment; and a flexible joint joining the upper and lower frames, the flexible joint allowing relative motion of the upper and lower frames in a pivot direction and allowing resilient relative motion in a torsional direction.

The flexible joint may be positioned in the backpack relative or near to a lumbar area of the user. The flexible joint may comprise an elastic portion positioned between the upper and lower frames. The flexible joint may comprise a rigid portion positioned between at least one of the upper and lower frames and the elastic portion. The flexible joint may be selectively tightenable to adjust a range of relative motion of the upper and lower frames in at least the torsional direction. The flexible joint may permit relative pivotal motion of the upper and lower frames of at least about 45 degrees in the pivot direction and may permit relative torsional motion of at least about 20 degrees in the torsional direction. The flexible joint may be biased to orient the upper and lower frames in an upright position.

In some embodiments, the upper and lower frames may be shaped to conform to a rear portion of a human body.

In another exemplary embodiment, a method of providing a pack frame apparatus is disclosed, with the method comprising providing a first plate and a second plate, the plates being adapted to provide structural support to a pack frame, the first plate being positioned for support of an upper back portion of a user through attachment to a shoulder strap, the second plate being positioned for support of a lower back portion of the user through attachment to a waist strap; and pivotally joining the first plate with the second plate, the first and second plates being relatively rotatable in a first direction and being resiliently relatively rotatable in a second direction.

Joining the first plate with the second plate may comprise inserting a resilient member between the first and second plates and joining the first and second plates around the resilient member for pivotal movement along the first direction.

The method may also comprise attaching the joined first and second plates with a backpack having shoulder straps and a bag, pouch, or other type of storage compartment. The method may also comprise adjusting the range of relative rotation of the first and second plates in at least the second direction by tightening or loosening a member joining the first and second plates.

In some embodiments, the relative rotation between the first and second plates may be biased to assume a default position in at least one of the first and second directions.

The foregoing and other features, utilities and advantages of the invention will be apparent from the following more particular description of a preferred embodiment of the invention as illustrated in the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings and figures illustrate a number of exemplary embodiments and are part of the specification. Together with the present description, these drawings demonstrate and explain various principles of this disclosure. A further understanding of the nature and advantages of the present invention may be realized by reference to the following drawings. In the appended figures, similar components or features may have the same reference label.

<figref idref="DRAWINGS">FIG. 1A</figref> illustrates a rear perspective view of a pack frame according to an embodiment of the present disclosure.

<figref idref="DRAWINGS">FIG. 1B</figref> illustrates the pack frame shown in <figref idref="DRAWINGS">FIG. 1A</figref> relative to the remainder of an exemplary backpack.

<figref idref="DRAWINGS">FIG. 2A</figref> is a rear plan view of the pack frame of <figref idref="DRAWINGS">FIG. 1A</figref>.

<figref idref="DRAWINGS">FIG. 2B</figref> is a front plan view of the pack frame of <figref idref="DRAWINGS">FIG. 1A</figref>.

<figref idref="DRAWINGS">FIG. 2C</figref> is a left side plan view of the pack frame of <figref idref="DRAWINGS">FIG. 1A</figref> next to a profile of a wearer.

<figref idref="DRAWINGS">FIG. 3A</figref> is an exploded rear perspective view of a pack frame joint according to an embodiment of the present disclosure.

<figref idref="DRAWINGS">FIG. 3B</figref> is an exploded front perspective view of the joint of <figref idref="DRAWINGS">FIG. 3A</figref>.

<figref idref="DRAWINGS">FIG. 3C</figref> is an exploded bottom view of the joint of <figref idref="DRAWINGS">FIG. 3A</figref>.

<figref idref="DRAWINGS">FIG. 3D</figref> is an exploded side view of the joint of <figref idref="DRAWINGS">FIG. 3A</figref>.

<figref idref="DRAWINGS">FIG. 4A</figref> is a bottom section view of the joint of <figref idref="DRAWINGS">FIG. 2B</figref> through section lines <b>4</b>A in <figref idref="DRAWINGS">FIG. 2B</figref>.

<figref idref="DRAWINGS">FIG. 4B</figref> is a side section view of the joint of <figref idref="DRAWINGS">FIG. 2B</figref> through section lines <b>4</b>B in <figref idref="DRAWINGS">FIG. 2B</figref>.

<figref idref="DRAWINGS">FIG. 5A</figref> is an illustration of an upright user positioned relative to a pack frame apparatus according to the present disclosure.

<figref idref="DRAWINGS">FIG. 5B</figref> is an illustration of a turning user positioned relative to a pack frame apparatus according to the present disclosure.

<figref idref="DRAWINGS">FIG. 5C</figref> is an illustration of a leaning user positioned relative to a pack frame apparatus according to the present disclosure.

While the embodiments described herein are susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and will be described in detail herein. However, the exemplary embodiments described herein are not intended to be limited to the particular forms disclosed. Rather, the instant disclosure covers all modifications, equivalents, and alternatives falling within the scope of the appended claims.

DETAILED DESCRIPTION

According to some embodiments of the present disclosure, a pack frame apparatus is provided that provides rigidity to a pack while following the natural movement of wearers and helping wearers to bear loads in a normal orientation. Thus, these embodiments may reduce fatigue, increase weight bearing capacity, and provide a more natural and comfortable feel to wearers.

A pack frame apparatus may comprise two frame portions or plates that are joined to each other by a joint that allows relative pivotal movement of the frame portions around a first axis and allows resilient relative pivotal movement around a second axis. A first frame portion may be positioned adjacent to the upper torso of wearers, and the second frame portion may be positioned adjacent to the lower torso, near or below the waist. A joint between the frame portions links them together while allowing them to rotate relative to each other in multiple directions. For example, the joint may connect the frame portions while allowing relative pivotal movement around the first axis when wearers lean laterally (i.e., left or right) while also allowing relative movement of the frame portions when wearers exert torsional forces on the plates (i.e., turning, left/right or up/down at the lower back). See, e.g., <figref idref="DRAWINGS">FIGS. 5A-5C</figref>.

Thus, the pack frame apparatus can accommodate multiple degrees of freedom at the back of the user. The joint may be designed with a resilient portion that allows a limited range of motion compared to a primary direction of pivotability of the joint, thereby providing a limited amount of “give” to the frame and increasing comfort, shock absorption, and adaptability of the frame to active wearers. Because the range of motion afforded by the resilient portion is limited, the flexibility of the joint does not sacrifice an undue amount of rigidity and weight bearing capacity.

In some embodiments, the joint may be adjustable, thereby providing a varying degree of restriction to the relative movement of the frame portions. By tightening or loosening the joint, the frame portions may become more rigidly or flexibly attached to each other. This may provide adaptability to the frame, where wearers may choose the amount of rigidity desired for a particular task at hand.

The joint may be designed to assist the user in orienting the frame portions in one or more particular relative position. For example, the joint may be designed with notches and grooves that coincide with each other when the frame portions are vertically aligned, and wearers must therefore overcome extra resistance to reorient the frame portions by removing the notches from the grooves as they turn in one or more direction. Other structures, such as nubs and depressions, may alternatively be used. Similarly, the joint may be configured with materials that resiliently bias relatively rotated frame portions into a preferred default position.

While reference herein is made to a frame for a backpack, it will be appreciated that the scope of the disclosure may also include frames for other devices and equipment worn on a moving body (e.g., the human body), including, for example, rucksacks, knapsacks, messenger bags, bookbags, hydration packs, fanny packs, sling bags, duffel bags, satchels, parachutes, and other cargo-carrying wearable vessels. Application of the principles and elements of the present disclosure may find beneficial use in various outdoor activities, including military, sports, travel, and other industries. Elements of the present disclosure may be applied in other body-conforming devices, such as body armor (e.g., security vests), sports equipment (e.g., protective body pads), and harnesses.

The present description provides examples, and is not limiting of the scope, applicability, or configuration set forth in the claims. Thus, it will be understood that changes may be made in the function and arrangement of elements discussed without departing from the spirit and scope of the disclosure, and various embodiments may omit, substitute, or add other procedures or components as appropriate. For instance, the methods described may be performed in an order different from that described, and various steps may be added, omitted, or combined. Also, features described with respect to certain embodiments may be combined in other embodiments.

Turning now to the figures, <figref idref="DRAWINGS">FIG. 1</figref> A illustrates a rear perspective view of a pack frame <b>100</b> according to an embodiment of the present disclosure. The pack frame <b>100</b> may include an upper frame portion <b>102</b> and a lower frame portion <b>104</b> joined by a joint <b>106</b>. The upper frame portion <b>102</b> may correspond to a portion of a pack arranged to be adjacent to a wearer's upper torso, and the lower frame portion <b>104</b> may correspond to the wearer's lower torso. The joint <b>106</b> may be oriented to pivotably join the upper and lower frame portions <b>102</b>, <b>104</b> in or around the lumbar area of a wearer. See also <figref idref="DRAWINGS">FIGS. 5A-5C</figref>.

As used herein, the “rear” of the pack frame <b>100</b> faces the back of the wearer when worn, and the “front” of the pack frame <b>100</b> faces away from the wearer, such as toward attached backpack compartments or other cargo space.

The upper and lower frame portions <b>102</b>, <b>104</b> may comprise a generally rigid, lightweight material. In some embodiments, the frame portions <b>102</b>, <b>104</b> may comprise a composite material, such as, for example, carbon fiber or fiberglass. Plastics, metals, wood, and combinations thereof may also be used for some or all of the frame portions <b>102</b>, <b>104</b>, such as, for example, to provide additional resilience or rigidity to sections of the frame portions <b>102</b>, <b>104</b>. The frame portions <b>102</b>, <b>104</b> may be molded or otherwise formed with contours providing flexibility and easier attachment of backpack features to the frame portions <b>102</b>, <b>104</b>. In some embodiments, the contours of the frame portions <b>102</b>, <b>104</b> may be shaped to direct cargo away from the surface of the wearer's body or to take the shape of certain types of cargo. For example, upper flanges <b>108</b> may be curved away from the wearer to facilitate strapping the flanges <b>108</b> to a cylindrical element such as a bedroll.

In some embodiments (not shown), the curvature of the frame portions <b>102</b>, <b>104</b> may generally correspond to a backside of a human, with a lumbar portion (around joint <b>106</b>) following the lumbar area of a wearer, the upper frame portion <b>102</b> having an upper end (near flanges <b>108</b> and shoulder area <b>114</b>) that follows the contours of the upper back of the wearer, and the lower frame portion <b>104</b> extending from the joint <b>106</b> with a contoured area <b>118</b> following the lower back and gluteal region of the wearer's body. In this configuration, the frame portions <b>102</b>, <b>104</b> may fit more closely to the wearer, bringing the center of gravity of the backpack closer to the wearer's center of gravity. In other configurations, portions of the frame portions <b>102</b>, <b>104</b> may be contoured toward the wearer while other portions curve away.

The upper frame portion <b>102</b> may comprise upper flanges <b>108</b>. These flanges <b>108</b> may be adapted to extend vertically higher than the wearer's shoulders or shoulder blades. The upper flanges <b>108</b> may provide rigidity to the over-shoulder region of the pack while also providing limited flexibility in that area due to the thickness and materials used in their construction.

The perimeter of the upper frame portion <b>102</b> may comprise attachment slots <b>110</b> configured to attach to a pack, e.g., pouches, straps, and/or other backpack features. In some embodiments, the attachment slots <b>110</b> may be configured on the upper frame portion <b>102</b> to allow wearers to change selectively the position of straps, bags, pouches, cords, pads, cushions, and other features. The lower frame portion <b>104</b> may also comprise attachment slots <b>110</b> (not shown) to attach a waist strap, sleep roll, pouch, or other features of a pack.

A surface of the upper frame portion <b>102</b> may comprise generally horizontal strap slots <b>112</b>, such as in the shoulder area <b>114</b> of the upper frame portion <b>102</b>. The strap slots <b>112</b> may provide an attachment point for shoulder straps that extend around the wearer's shoulders. See <figref idref="DRAWINGS">FIG. 1B</figref>. Eight strap slots <b>112</b> are shown in the figures, but more or less may be used. When using multiple strap slots <b>112</b>, the shoulder straps may be repositioned to accommodate different wearer sizes or strap lengths. The strap slots <b>112</b> may also provide additional flexibility and ventilation to the shoulder area <b>114</b>, thereby providing additional comfort to wearers by permitting airflow and bending near their joints. Strap slots <b>112</b> may also be used to decrease the weight of the pack frame apparatus <b>100</b>. In some embodiments, the strap slots <b>112</b> are covered or obscured by bags or other enclosures, and thus may not provide airflow. In some embodiments, the strap slots <b>112</b> may be used to attach backpack elements and cushions, similar to the attachment slots <b>110</b> described above. Strap slots <b>112</b> may also be positioned on the upper pack frame <b>102</b> in a position other than the shoulder area <b>114</b> where ventilation, flexibility, or attachment points are desired. In some arrangements, the lower pack frame <b>104</b> may comprise strap slots <b>112</b>. Lower pack frame <b>104</b> strap slots <b>112</b> may be used to attach the lower portion of a shoulder strap or to attach waistband straps.

The lower pack frame <b>104</b> may comprise an opening <b>116</b> and a contoured area <b>118</b>. The opening <b>116</b> may reduce the weight and increase flexibility of the pack frame apparatus <b>100</b>. The opening <b>116</b> may also provide a relief opening for the lower back or sacral areas of wearers by distributing weight of the pack to the sides of the spinal column and toward the iliac crests of the pelvis. The opening <b>116</b> may also be configured to receive a pad for this area of wearer.

The contoured area <b>118</b> may provide a transition between the portion of the lower pack frame <b>104</b> attached to joint <b>106</b> and the bottom end of lower pack frame <b>104</b>. The contoured area <b>118</b> may facilitate easier attachment of curved bags and other cargo. In some embodiments, the contoured area <b>118</b> may also follow the natural curve of the lower back of a wearer to improve comfort and decrease the amount of flexure of the lower pack frame <b>104</b> needed to conform to the shape of the wearer's body.

<figref idref="DRAWINGS">FIG. 1B</figref> illustrates a pack frame <b>100</b> shown relative to the remainder of an exemplary backpack. The pack frame <b>100</b> is attached to the backpack. A main pack portion <b>120</b> may include one or more pouch or load-carrying pockets and may be secured to extend rearward from the upper pack frame <b>102</b>, and a second pouch <b>122</b> and one or more side pouch <b>124</b> may be adjacent to the lower pack frame <b>104</b>. Shoulder straps <b>126</b> may extend from the upper pack frame <b>102</b> (e.g., from strap slots <b>112</b>) and attach to another portion of the upper pack frame <b>102</b> (e.g., at attachment slots <b>110</b>), the lower pack frame <b>104</b>, or to pouches or other material on the backpack. The shoulder straps <b>126</b> may be configured to wrap around the shoulders and upper body of a wearer. Waist straps <b>128</b> may extend from the lower end of the backpack, such as from an attachment to the lower pack frame <b>104</b> or a lower portion of the upper pack frame <b>102</b>. The waist straps <b>128</b> may be configured to connect to each other after wrapping around the lower back, waist, or pelvic area of a wearer, such as by a buckle. Additional and alternative configurations of pouches, straps, cords, pads, and other backpack elements will be apparent to those skilled in the art of backpack design and having the benefit of the present disclosure.

<figref idref="DRAWINGS">FIGS. 2A-2C</figref> show alternate views of the pack frame <b>100</b> of <figref idref="DRAWINGS">FIGS. 1A-1B</figref>. <figref idref="DRAWINGS">FIG. 2A</figref> is a rear plan view, <figref idref="DRAWINGS">FIG. 2B</figref> is a front plan view, and <figref idref="DRAWINGS">FIG. 2C</figref> is a left side plan view. <figref idref="DRAWINGS">FIG. 2C</figref> also shows the profile of an exemplary wearer next to the pack frame <b>100</b>. As shown in these figures, the upper pack frame <b>102</b> overlaps the lower pack frame <b>104</b> in and around the region where the joint <b>106</b> is located. In these embodiments, the lower pack frame <b>104</b> is positioned forward relative to the upper pack frame <b>102</b> at the joint <b>106</b>, but in other embodiments, their relative positions may be reversed.

Positioning the upper pack frame <b>102</b> closer to the wearer than the lower pack frame <b>104</b> may provide more contact between the lower pack frame <b>104</b> and the cargo carried by the backpack, thereby facilitating attachment of the cargo to the lower pack frame <b>104</b>. The joint <b>106</b> may also be easily adjustable, since the adjustment cap <b>300</b> may face the wearer's body.

When their relative positions are reversed, positioning the lower pack frame <b>104</b> closer to the wearer than the upper pack frame <b>102</b> may be beneficial in improving shock absorption capability of the pack frame <b>100</b>. When the pack frame <b>100</b> is worn, contact between the lower pack frame <b>104</b> and the wearer may apply a constant force against the lower pack frame <b>104</b> that may not be present if the lower pack frame <b>104</b> is positioned behind the upper pack frame <b>102</b> at the joint <b>106</b>. Thus, adjustments to the position or movement of the wearer may more directly and granularly be responded to by relative rotation of the upper and lower pack frames <b>102</b>, <b>104</b> at the joint <b>106</b> with the lower pack frame <b>104</b> positioned closer to the wearer than the upper pack frame <b>102</b>.

With the upper pack frame <b>102</b> positioned closer than the lower pack frame <b>104</b>, the lower pack frame <b>104</b> may not be in constant contact with the lower torso of the wearer and may potentially not follow the wearer's movements as closely. <figref idref="DRAWINGS">FIG. 2C</figref> in particular shows how the curvature of the pack frame <b>100</b> relates to a curvature profile of a back of a wearer. In other embodiments, the pack frame <b>100</b> may roughly follow the curve of the spine, with the joint <b>106</b> at about the waist or upper sacral region of the body.

The rear side <b>200</b> of the upper pack frame <b>102</b> and the rear side <b>202</b> of the lower pack frame <b>104</b> may be fitted with cushions or padding to improve comfort, grip, and/or zonal flexibility of the pack frame <b>100</b> against the wearer.

<figref idref="DRAWINGS">FIGS. 3A-3D</figref> show exploded views of the joint <b>106</b> relative to the upper and lower pack frames <b>102</b>, <b>104</b>. <figref idref="DRAWINGS">FIG. 3A</figref> is a perspective rear view, <figref idref="DRAWINGS">FIG. 3B</figref> is a perspective front view, <figref idref="DRAWINGS">FIG. 3C</figref> is a bottom view, and <figref idref="DRAWINGS">FIG. 3D</figref> is a side view. Along a central axis (A), the rearward direction extends toward the end of the joint <b>106</b> having an adjustment cap <b>300</b>, and the forward direction extends toward the end of the joint <b>106</b> having an internal cap <b>308</b>. A first resilient member <b>302</b> is positioned between the adjustment cap <b>300</b> and the upper pack frame <b>102</b>. A protective ring <b>304</b> is positioned between the first resilient member <b>302</b> and the upper pack frame <b>102</b>. A second resilient member <b>306</b> is positioned between the upper pack frame <b>102</b> and the lower pack frame <b>104</b>. An internal cap <b>308</b> is attachable to the adjustment cap <b>300</b> to hold the lower pack frame <b>104</b> between the internal cap <b>308</b> and the second resilient member <b>306</b>.

The adjustment cap <b>300</b> may be comprised of a rigid material, such as, for example, a metal or polymer. The outer surface of the adjustment cap <b>300</b> may be configured with ridges <b>310</b>. The ridges <b>310</b> may facilitate hand-tightening of the adjustment cap <b>300</b> relative to the rest of the joint <b>106</b>. In some embodiments, the outer surface may have holes or other features to receive tools to tighten the cap <b>300</b>. The stem <b>312</b> of the adjustment cap <b>300</b> may be threaded. The frontal face <b>314</b> (see <figref idref="DRAWINGS">FIG. 3B</figref>) of the adjustment cap <b>300</b> may be generally flat. The adjustment cap <b>300</b> may be threadably attachable to the internal cap <b>308</b> using the stem <b>312</b> and threads on the internal cap <b>308</b>. The threaded attachment of the adjustment cap <b>300</b> and the internal cap <b>308</b> may tighten or loosen the connection between the upper and lower pack frames <b>102</b>, <b>104</b>, thereby adjusting the force required to move the upper and lower pack frames <b>102</b>, <b>104</b> relative to each other, as described in further detail below.

The first resilient member <b>302</b> may be comprised of a relatively resilient or elastic material, such as, for example, rubber or a flexible polymer or composite. If an elastomer is used, the elastomer may be chosen to provide dampening qualities, even if the member <b>302</b> is not immediately elastic. The resilient member <b>302</b> is generally annular in shape and sized to receive the stem <b>312</b> of the adjustment cap <b>300</b> through an opening in its center. Other shapes securable between the adjustment cap <b>300</b> and the upper pack frame <b>102</b> may also be implemented, such as, for example, a partial annulus (i.e., C-shape), a square having an opening in its center, and the like. The rearward surface <b>316</b> of the first resilient member <b>302</b> may be generally flat and engage the frontal face <b>314</b> of the adjustment cap <b>300</b>. The surface profiles of the rearward surface <b>316</b> and the frontal face <b>314</b> may therefore correspond to each other, and non-planar shapes may also be implemented. For example, a curved rearward surface <b>316</b> may fit with a frontal face <b>314</b> that has a correlating curved surface shape.

In some embodiments, the rearward surface <b>316</b> may comprise a circumferential lip (not shown) extending rearward from the edge of the rearward surface <b>316</b>. The circumferential lip may help keep the first resilient member <b>302</b> aligned with the adjustment cap <b>300</b> and may extend around the outside edge of the frontal face <b>314</b> of the adjustment cap when the joint <b>106</b> is assembled. The circumferential lip may prevent the adjustment cap <b>300</b> from sliding relative to the rearward surface <b>316</b> when the joint <b>106</b> is torsionally flexed (e.g., around axes B or C in <figref idref="DRAWINGS">FIG. 5B</figref>).

The thickness (t₁) of the outer perimeter or circumference of the first resilient member <b>302</b> may vary around the central axis (A) of the joint. See, e.g., <figref idref="DRAWINGS">FIGS. 3C and 3D</figref>, showing profile views of the first resilient member <b>302</b>. The thickness of the first resilient member <b>302</b> may thus follow the shape of the rear surface <b>317</b> surrounding the opening <b>318</b> in the upper pack frame <b>102</b>. <figref idref="DRAWINGS">FIG. 3C</figref> shows the convex shape of the rear surface <b>317</b> around the opening <b>318</b> and the corresponding concave of the thickness of the first resilient member <b>302</b> extending from the rearward surface <b>316</b>. As shown in <figref idref="DRAWINGS">FIG. 3D</figref>, the circular shape of the first resilient member <b>302</b> may cause the concave of the thickness of the first resilient member <b>302</b> to produce a convex curve when viewed from the side.

Varying thickness of the first resilient member <b>302</b> may affect the elastic properties of the pack frame <b>100</b>. For example, with a convex rear surface <b>317</b> around opening <b>318</b> and a concave shaped first resilient member <b>302</b> (when viewed from its bottom profile), the first resilient member <b>302</b> may interlock and engage the rear surface <b>317</b> with the thinnest thicknesses <b>319</b>-<i>a </i>of the first resilient member <b>302</b> oriented vertically relative to the wearer. In this configuration, rotation of the upper pack frame <b>102</b> relative to the first resilient member <b>302</b> may produce relative rotation of the convex and concave surfaces. For example, as the upper pack frame <b>102</b> is rotated relative to the joint <b>106</b> (and therefore also relative to the first resilient member <b>302</b>), the position of the upper pack frame <b>102</b> may change orientation between the orientations shown in <figref idref="DRAWINGS">FIGS. 5A and 5C</figref>. The relative rotation may then cause the convex thicker portions <b>319</b>-<i>b </i>of the first resilient member <b>302</b> to rotate into engagement with the convex area of the rear surface <b>317</b> and resiliently deform (i.e., compress) between the rear surface <b>317</b> of the upper pack frame <b>102</b> and the frontal face <b>314</b> of the adjustment cap <b>300</b>. This deformation may require additional force and effort from the wearer to produce the rotation of these elements. If the upper pack frame <b>102</b> is rotated back from the orientation of <figref idref="DRAWINGS">FIG. 5C</figref> to the orientation of <figref idref="DRAWINGS">FIG. 5A</figref>, the thick portions <b>319</b>-<i>b </i>of the first resilient member <b>302</b> may then deform again (i.e., expand), assisting the wearer in completing this motion. In such embodiments, the surface features of the upper and/or lower pack frames <b>102</b>, <b>104</b> that interact with (e.g., interlock with) the resilient members <b>302</b>, <b>306</b> may be referred to as portions of the joint. The first resilient member <b>302</b>, ring <b>304</b>, and second resilient member <b>306</b> may optionally include alignment indicators <b>342</b> to assist in properly aligning them when assembling the joint <b>106</b>.

The resistance and assistance provided by the first resilient member <b>302</b> when making lateral rotation of the upper pack frame <b>102</b> relative to the joint <b>106</b> may beneficially establish a “default” or “at rest” orientation of the pack frame <b>100</b>, where potential energy in the joint <b>106</b> is at its lowest. The default orientation of the pack frame <b>100</b> may be beneficially configured as an upright, weight-bearing position for the wearer. This orientation may provide the wearer with assistance in keeping the pack upright and keeping upright posture, but other orientations may be selected, as required in each individual embodiment. In some embodiments, the shape (e.g., curvature) of the first resilient member <b>302</b> may thus be configured to provide a “snap-back” position and an orientation of the pack frame <b>100</b> from which increased effort may be required to move the resilient member <b>302</b>. As the upper pack frame <b>102</b> is reoriented, the first resilient member <b>302</b> may be configured to bias the upper pack frame <b>102</b> back to a default orientation relative to the joint <b>106</b> and/or lower pack frame <b>104</b>.

The first resilient member <b>302</b> may also act as a shock absorber which dampens vibration or other forces between the adjustment cap <b>300</b> and the upper pack frame <b>102</b>. This may enhance comfort of the pack frame, decrease wear on rigid components of the frame, and allow relative pivoting or rotational movement between elements of the pack frame along an axis perpendicular to axis A. Shock absorption and dampening may be provided around three axes of rotation. See, e.g., <figref idref="DRAWINGS">FIG. 5B</figref> and related description, infra, illustrating additional rotation axes B and C.

Although the embodiments shown in the figures show a first and a second resilient member <b>302</b>, <b>306</b>, in some embodiments, only one resilient member may be present. If the first resilient member <b>302</b> is the one present, relative rotation between the upper and lower pack frames <b>102</b>, <b>104</b> may be provided since the upper pack frame <b>102</b> may compress the first resilient member <b>302</b> against the frontal face <b>314</b> of the adjustment cap <b>300</b>, and the adjustment cap <b>300</b> may be rigidly attached to the internal cap <b>308</b> and/or the lower pack frame <b>104</b>. This compression may provide clearance and relative rotation between sections of the upper and lower pack frames <b>102</b>, <b>104</b>. In embodiments where only the second resilient member <b>306</b> is present, relative rotation between the upper and lower pack frames <b>102</b>, <b>104</b> may be provided by compression of the second resilient member <b>306</b> between the front surface <b>330</b> and the surface surrounding the receiver extension <b>336</b> on the lower pack frame <b>104</b>.

In some arrangements, the rear surface <b>317</b> of the upper pack frame <b>102</b> may be concave and the positions of the thin edges <b>319</b>-<i>a </i>and thick edges <b>319</b>-<i>b </i>may be reversed accordingly to fit the concavity of the rear surface <b>317</b> similar to how their illustrated positions correspond to the convexity of the illustrated rear surface <b>317</b>. In other arrangements, the rear surface <b>317</b> may be flat, and the paired convex/concave surfaces may be the rearward surface <b>316</b> of the first resilient member <b>302</b> and the frontal face <b>314</b> of the adjustment cap <b>300</b>.

Other surface features may be implemented using the design features and guidelines described herein, as will be apparent to those skilled in the art having the benefit of the present disclosure. For example, a V-shaped surface may be used in place of a concave described and illustrated herein. Furthermore, the rear surface <b>317</b> may bear ridges, nubs, or notches that align with corresponding notches, depressions, or ridges on the first resilient member <b>302</b> or vice versa. These and other like designs would bias the upper and lower pack frames <b>102</b>, <b>104</b> into a default orientation and/or resist reorientation out of a default orientation while still allowing elastic deformation of the first resilient member <b>302</b> under sufficient forces, providing similar benefits to the illustrated embodiments described in greater detail above.

The ring <b>304</b> is an optional feature of the joint <b>106</b> that may be positioned between the upper pack frame <b>102</b> and the first resilient member <b>302</b>. The ring <b>304</b> may be comprised of a material allowing smooth sliding motion between the ring <b>304</b> and the first resilient member <b>302</b>. The ring <b>304</b> may protect the first resilient member <b>302</b> and second resilient member <b>306</b> from shear forces produced by the upper pack frame <b>102</b> as it rotates relative to the first resilient member <b>302</b> by providing a rigid surface configured to be slidable against the first resilient member <b>302</b>. See also <figref idref="DRAWINGS">FIGS. 4A-4B</figref> and their related description, infra. The ring <b>304</b> may also have a contoured shape that follows the profile (e.g., convex/concave) of the rear surface <b>317</b> of the upper pack frame <b>102</b> and a sliding surface <b>320</b> (see <figref idref="DRAWINGS">FIG. 3B</figref>) of the first resilient member <b>302</b>. See, e.g., the curved shape of the ring <b>304</b> in <figref idref="DRAWINGS">FIGS. 3C and 3D</figref>. In some embodiments, the ring <b>304</b> may be referred to as a rigid member.

In the illustrated configuration, the ring <b>304</b> may be inserted into the opening <b>318</b> in the upper pack frame <b>102</b>, with circumferential ridges <b>322</b> on the ring <b>304</b> insertable into circumferential notches <b>324</b> of the opening <b>318</b> and the circumferential notches <b>324</b> of the circular groove <b>326</b> of the second resilient member <b>306</b> (see <figref idref="DRAWINGS">FIG. 3A</figref>). Thus, the ring <b>304</b> is not rotatable relative to the upper pack frame <b>102</b> or the second resilient member <b>306</b> after insertion. The ring <b>304</b> may be comprised of a smooth, rigid material such as, for example, nylon, that allows sliding motion of the first resilient member <b>302</b> where it contacts the ring <b>304</b> at the sliding surface <b>320</b>. Thus, when the upper pack frame <b>102</b> translates laterally relative to the lower pack frame <b>104</b> and/or other portions of the joint <b>106</b> (e.g., perpendicular to axis A), the ring <b>304</b> may distribute the shear force at the opening <b>318</b> across the outside surface of the ring <b>304</b> and into the first and second resilient members <b>302</b>, <b>306</b>. This outside surface is relatively broad in comparison to to the thickness of the upper pack frame <b>102</b>. Thus, the ring <b>304</b> may allow the upper pack frame <b>102</b> to be thin and light without cutting or otherwise shearing the first and/or second resilient members <b>302</b>, <b>306</b>.

In some embodiments, the ring <b>304</b> may have ridges <b>322</b> configured to engage notches (not shown) in the first and second resilient members <b>302</b>, <b>306</b>, thereby linking rotation of the ring <b>304</b> to the resilient members instead of to the upper pack frame <b>102</b>. It may be beneficial to configure the ring <b>304</b> in this manner since the ring <b>304</b> and upper pack frame <b>102</b> are typically each more rigid than the resilient members <b>302</b>, <b>306</b> and it may thus be easier for them to slide against each other, but the ring <b>304</b> may also need to be thinner to be able to fit between the adjustment cap <b>300</b> and the lower pack frame <b>104</b> when they are not in the default orientation dictated by the shape of the resilient members <b>302</b>, <b>306</b>.

The ring <b>304</b> may also have a circumferential lip <b>402</b>. See <figref idref="DRAWINGS">FIG. 4A</figref>. This lip <b>402</b> may prevent the ring <b>304</b> from passing through the upper pack frame <b>102</b> and may provide a surface on which the first resilient member <b>302</b> may slide.

The second resilient member <b>306</b> may be comprised of a resilient, elastic material such as rubber or a flexible polymer. The second resilient member <b>306</b> may be positioned between the upper and lower pack frames <b>102</b>, <b>104</b>. The second resilient member <b>306</b> may have a general shape similar to the first resilient member <b>302</b>, such as, for example an annular shape or another shape having an opening therein. The thickness of the second resilient member <b>306</b> may vary around the central axis A, with thinner portions <b>328</b>-<i>a </i>and thicker portions <b>328</b>-<i>b </i>circumferentially spaced. While two thinner portions <b>328</b>-<i>a </i>and two thicker portions <b>328</b>-<i>b </i>are shown herein, other configurations may include three or more alternating thinner and thicker portions instead.

In an exemplary embodiment, shown in <figref idref="DRAWINGS">FIGS. 3A-3D</figref>, the front surface <b>330</b> of the upper pack frame <b>102</b> may be concave (see <figref idref="DRAWINGS">FIG. 3C</figref> particularly), so the thicker portions <b>328</b>-<i>b </i>may be oriented vertically and the thinner portions <b>328</b>-<i>a </i>may be oriented laterally when the upper pack frame <b>102</b> is in the default, upright orientation relative to the lower pack frame <b>104</b>. Similar to the description above regarding the shape of the first resilient member <b>302</b> and the rear surface <b>317</b>, the front surface <b>330</b> and the second resilient member <b>306</b> may be formed with interlocking or adjoining surfaces that may bias the upper pack frame to a default orientation. For example, the front surface <b>344</b> of the second resilient member may have resilient setoffs or bumps (not shown) extending from the front surface <b>344</b> toward the lower pack frame <b>104</b>, and the lower pack frame <b>104</b> may comprise small depressions surrounding the receiver extension <b>336</b> that receive the setoffs when the front surface <b>344</b> is in an upright orientation. Alternatively, the setoffs and depressions may be reversed, with the setoffs extending from the lower pack frame <b>104</b>. In another embodiment, the setoffs and depressions may appear on the surfaces of the upper pack frame <b>102</b> and the second resilient member <b>306</b> that come into contact. With a generally constant-thickness upper pack frame <b>102</b>, the thickness t₂of the second resilient member <b>306</b> may be analogous to the thickness t₁of the first resilient member <b>302</b>, with thicker portions of one resilient member being adjacent to thinner portions of the other.

In embodiments where the ridges <b>322</b> of the ring <b>304</b> are inserted into notches <b>324</b> in the circular groove <b>326</b> of the second resilient member <b>306</b>, the second resilient member <b>306</b> may simultaneously rotate around the central axis A with the upper pack frame <b>102</b>. Thus, the thicker portions <b>328</b>-<i>b </i>and thinner portions <b>328</b>-<i>a </i>of the second resilient member <b>306</b> may remain oriented relative to the front surface <b>330</b> and the opening <b>318</b> in the same manner as when they are in the default orientation. In other embodiments, the ring <b>304</b> may not have ridges <b>322</b> or the circular groove <b>326</b> may be wide enough to receive the ridges <b>322</b> yet allow the ring <b>304</b> to rotate within the circular groove <b>326</b>. In these embodiments, the second resilient member <b>306</b> may rotate independent of the upper pack frame <b>102</b>.

The second resilient member <b>306</b> may comprise a central post <b>332</b> between the circular groove <b>326</b> and the central opening through the second resilient member <b>306</b>. See <figref idref="DRAWINGS">FIGS. 3A</figref>, <b>3</b>C, and <b>3</b>D. The central post <b>332</b> may be an extension of the resilient material that has greater height than the thinner and thicker portions <b>328</b>-<i>a</i>, <b>328</b>-<i>b </i>of the second resilient member <b>306</b>. The extra height of the central post <b>332</b> may increase the surface area of the second resilient member <b>306</b> that contacts the ring <b>304</b>. The extra height may also allow the central post <b>332</b> of the second resilient member <b>306</b> to contact the first resilient member <b>302</b> when the joint <b>106</b> is assembled. See also <figref idref="DRAWINGS">FIGS. 4A-4B</figref>.

In some embodiments, the first resilient member <b>302</b> may also have a central post <b>334</b> that may come into contact with the central post <b>332</b> of the second resilient member <b>306</b>. See <figref idref="DRAWINGS">FIGS. 3B</figref>, <b>3</b>C, and <b>3</b>D. Upon assembly, the distance between the sliding surface <b>320</b> and the bottom of the circular groove <b>326</b> may therefore be about equal to the height of the ring <b>304</b>. In this configuration, the ring is securely held in place by the resilient members <b>302</b>, <b>306</b> and the opening <b>318</b> of the upper pack frame <b>102</b>, even during rotation around axis A or another axis perpendicular thereto. A close fit may thus keep debris and dirt out of the joint <b>106</b> and keep the joint clean and operating smoothly.

The second resilient member <b>306</b> may rotate independent of the lower pack frame <b>104</b>, such as by rotating around a receiver extension <b>336</b> coming from the lower pack frame <b>104</b>. The receiver extension <b>336</b> may receive the internal cap <b>308</b> from the front of the joint <b>106</b> and may fit within the first and/or second resilient members <b>302</b>, <b>306</b> of the joint <b>106</b> upon assembly as well. See also <figref idref="DRAWINGS">FIGS. 4A-4B</figref>. The surface of the receiver extension <b>336</b> may beneficially be at a 10-degrees-or-greater angle relative to the central axis A. In a preferable embodiment, this surface may be at about 15 degrees relative to the central axis A to facilitate molding construction of the lower pack frame <b>104</b>. In other embodiments, such as those where the lower pack frame <b>104</b> is not molded, the surface of the receiver extension <b>336</b> may be angled at less than 10 degrees relative to the central axis A. This may allow the joint <b>106</b> to be more compact and may provide more rigidity in the joint during torsional flexion.

The rear side of the lower pack frame <b>104</b> around the receiver extension <b>336</b> may be smooth and shaped to slidably receive the second resilient member <b>306</b>. In some embodiments, the second resilient member <b>306</b> may be attached to the rear side of the lower pack frame <b>104</b> around the receiver extension <b>336</b> by an adhesive, interference of parts, or another attaching means. Preferably, the ring <b>304</b> may slidably rotate within the circular groove <b>326</b> relative to the second resilient member <b>306</b> if the second resilient member <b>306</b> is attached to the lower pack frame <b>104</b>.

The inclusion of two resilient members may allow greater cumulative deformation of the resilient members <b>302</b>, <b>306</b> by the upper pack frame <b>102</b>. This may provide smoother axial rotation of the upper pack frame <b>102</b> away from the default orientation and may also provide increased biasing forces to bring the upper pack frame <b>102</b> back into the default orientation, since the resilient members may apply a force to both side surfaces <b>317</b>, <b>330</b> of the upper pack frame <b>102</b>. Additionally, having resilient members on each side of the upper pack frame <b>102</b> may allow easier movement of the upper pack frame <b>102</b> relative to the lower pack frame <b>104</b> around an axis perpendicular to central axis A. This torsional motion of the pack frames <b>102</b>, <b>104</b> may be accommodated by compression of both of the resilient members <b>302</b>, <b>306</b> on each side of the opening <b>318</b> (i.e., on opposing sides of the resilient members <b>302</b>, <b>306</b>). See also <figref idref="DRAWINGS">FIG. 5B</figref> and its related description below.

The internal cap <b>308</b> may be received by the lower pack frame <b>104</b> from the front of the receiver extension <b>336</b>. The internal cap <b>308</b> may be internally threaded to receive threads of the stem <b>312</b> of the adjustment cap <b>300</b>. Using a threaded internal cap <b>308</b> and stem <b>312</b>, the tightness joint <b>106</b> may be adjustable to allow more or less resistance to axial and/or off-axial relative rotation of the upper and lower pack frames <b>102</b>, <b>104</b>. For example, tightening the threaded connection of the internal cap <b>308</b> and adjustment cap <b>300</b> may force the first resilient member <b>302</b> to partially deform (e.g., compress) into the upper pack frame <b>102</b>, thereby decreasing the amount of potential deformation of the resilient member upon reorientation of the upper pack frame <b>102</b> and increasing frictional forces between the resilient member and the upper pack frame <b>102</b>.

The internal cap <b>308</b> may have an outer surface <b>338</b> configured to engage an inner surface <b>340</b> of the receiver extension <b>336</b>. For example, the outer surface <b>338</b> may be faceted such that it may be received by the inner surface <b>340</b> without allowing rotation of the internal cap <b>308</b> after insertion. In another embodiment, the outer surface <b>338</b> may have one or more extension that may be received by the inner surface <b>340</b> that prevents rotation of the internal cap <b>308</b>, or vice versa. The internal cap <b>308</b> may thus be restricted from rotating relative to the lower pack frame <b>104</b> due to the engagement of the outer and inner surfaces <b>338</b>, <b>340</b>. By preventing rotation of the internal cap <b>308</b>, the adjustment cap <b>300</b> may be more easily turned relative to the internal cap <b>308</b> using the ridges <b>310</b>. This may advantageously allow a user to adjust the tension in the joint <b>106</b> with access to only the rear end of the joint <b>106</b>, as may be the case if the pack frame <b>100</b> is installed in a backpack with pouches, sleeves, and other material covering the front end of the joint <b>106</b> around the internal cap <b>308</b>. The threaded connection between the adjustment cap <b>300</b> and the internal cap <b>308</b> may also be configured to prevent the internal cap <b>308</b> from being removed from the stem <b>312</b> while installed in a backpack, such as by limiting the rotation of the threads of the stem <b>312</b> at a point to prevent inadvertent removal of the internal cap <b>308</b>. In this fashion, the internal cap <b>308</b> may not be easily lost or disconnected within the backpack while the pack frame <b>100</b> is installed. In some embodiments, the internal cap <b>308</b> may rotate within the receiver extension <b>336</b>. In yet other embodiments, the stem <b>312</b> may lock into position upon being completely received by the internal cap <b>308</b>, thereby preventing removal of the adjustment cap <b>300</b> from the internal cap <b>308</b>, or the internal cap <b>308</b> may be bonded into place, such as, for example, by an adhesive between the internal cap <b>308</b> and the lower pack frame <b>104</b>. In other embodiments, the adjustment cap <b>300</b> may be removably attached to the internal cap <b>308</b>, so the rest of the joint <b>106</b> (e.g., resilient members <b>302</b>, <b>306</b>) may also be removable from the pack frame <b>100</b>.

The internal cap <b>308</b> may also be attached to the stem <b>312</b> using other means, such as, for example, glue or another adhesive, a weld, press fit, or interference of parts. In some embodiments, the role of the internal cap <b>308</b> and the adjustment cap <b>300</b> may be reversed, such that the internal cap <b>308</b> may have ridges (e.g., similar to ridges <b>310</b>) and a stem extending into threaded connection with a threaded hole in the adjustment cap <b>300</b>. The role of other parts may also be exchanged without departing from the principles and elements of the present disclosure.

<figref idref="DRAWINGS">FIG. 4A</figref> shows a bottom section view through section lines <b>4</b>A in <figref idref="DRAWINGS">FIG. 2B</figref>. <figref idref="DRAWINGS">FIG. 4B</figref> shows a left side section view through section lines <b>4</b>B in <figref idref="DRAWINGS">FIG. 2B</figref>. Thus, <figref idref="DRAWINGS">FIGS. 4A and 4B</figref> illustrate orthogonal, central section views of the assembled joint <b>106</b>. The most rearward element is the adjustment cap <b>300</b>, followed by the first resilient member <b>302</b>, ring <b>304</b> and upper pack frame <b>102</b>, second resilient member <b>306</b>, lower pack frame <b>104</b>, and internal cap <b>308</b>. As shown in these figures, the stem <b>312</b> of the adjustment cap <b>300</b> may extend through the internal cap <b>308</b> completely upon tightening.

The first resilient member <b>302</b> may be compressed between the frontal face <b>314</b> of the adjustment cap <b>300</b> and the receiver extension <b>336</b> into the shape shown. In this configuration, the opening in the receiver extension <b>336</b> may contact a portion of the stem <b>312</b> and therefore apply less shear force to one of the resilient members <b>302</b>, <b>306</b> upon lateral movement of the lower pack frame <b>104</b> relative to the resilient members <b>302</b>, <b>306</b>. The adjustment cap <b>300</b> may have a stem shaft surface <b>400</b> configured to allow slidable rotation of the receiver extension <b>336</b> around the stem <b>312</b>. In other embodiments, the lower pack frame <b>104</b> may be linked in rotation with the adjustment cap <b>300</b> due to the threads of the internal cap <b>308</b> in order to prevent the adjustment cap <b>300</b> from unthreading from the internal cap <b>308</b>.

<figref idref="DRAWINGS">FIGS. 4A-4B</figref> also show the varying thicknesses of the first first and second resilient members <b>302</b>, <b>306</b> and the ring <b>304</b>. The thickness of the ring <b>304</b> in <figref idref="DRAWINGS">FIG. 4A</figref> appears thinner than the thickness in <figref idref="DRAWINGS">FIG. 4B</figref> due to the ridges <b>322</b> of the ring <b>304</b> being within section lines <b>4</b>B. The rearward portion of the ring <b>304</b> may have a lip <b>402</b> that prevents the ring <b>304</b> from passing completely through the opening <b>318</b> in the upper pack frame <b>102</b>. The lip <b>402</b> is not visible in <figref idref="DRAWINGS">FIG. 4B</figref> due to the increased thickness of the ring <b>304</b> subsuming the lip <b>402</b> at the ridges <b>322</b>.

<figref idref="DRAWINGS">FIGS. 4A-4B</figref> also illustrate how the entire height of the ring <b>304</b> may contact the first and second resilient members <b>302</b>, <b>306</b>. The height of the ring <b>304</b> is shown to be significantly broader than the thickness of the upper pack frame <b>102</b> and is distributed across the boundary between the first and second resilient members <b>302</b>, <b>306</b>, so that the ring <b>304</b> may prevent shearing of the resilient members <b>302</b>, <b>306</b> by the upper pack frame <b>102</b> and may also prevent the upper pack frame <b>102</b> from sliding between the resilient members <b>302</b>, <b>306</b> where they come into contact with each other. For example, the ring <b>304</b> may prevent the upper pack frame <b>102</b> from coming into contact with the central posts <b>332</b>, <b>334</b>. The first resilient member <b>302</b> may therefore slide more easily relative to the upper pack frame <b>102</b>, and it may be subject to less wear than if its central post <b>334</b> was in contact with the opening <b>318</b> of the upper pack frame <b>102</b>.

The thickness of the first resilient member <b>302</b> in <figref idref="DRAWINGS">FIG. 4A</figref> corresponds with the thicker portions <b>319</b>-<i>b</i>, and the thickness of the first resilient member in <figref idref="DRAWINGS">FIG. 4B</figref> corresponds with the thinnest thicknesses <b>319</b>-<i>a</i>. These figures therefore show the approximate amount of compression required for the thicker portions <b>319</b>-<i>b </i>to rotate into the position of the thinnest thicknesses <b>319</b>-<i>a</i>. The thinner portions <b>328</b>-<i>a </i>and thicker portions <b>328</b>-<i>b </i>of the second resilient member <b>306</b> are also shown in <figref idref="DRAWINGS">FIGS. 4A and 4B</figref>, respectively, thus showing how the second resilient member <b>306</b> conforms to the front surface <b>330</b> of the upper pack frame <b>102</b>. Additionally, the thicknesses <b>328</b>-<i>a</i>, <b>328</b>-<i>b </i>of the second resilient member <b>306</b> are greater than the thicknesses <b>319</b>-<i>a</i>, <b>319</b>-<i>b </i>of the first resilient member <b>302</b>. If the second resilient member <b>306</b> is made of the same material as the first resilient member <b>302</b>, the second resilient member <b>306</b> may therefore have a greater capacity for compressive deflection than the first resilient member <b>302</b>. This may allow easier relative torsional motion of the upper and lower pack frames <b>102</b>, <b>104</b> than relative lateral pivotal motion (i.e., around central axis A of the joint <b>106</b>). In embodiments where the second resilient member <b>306</b> may rotate relative to the upper pack frame <b>102</b>, these views also show the amount of compression needed to complete a rotation (i.e., a rotation of the thicker portion <b>319</b>-<i>b </i>from <figref idref="DRAWINGS">FIG. 4B</figref> to the position of the thinnest thicknesses <b>319</b>-<i>a </i>of <figref idref="DRAWINGS">FIG. 4A</figref>).

The width W of the joint <b>106</b> may be wide to improve the stability of the joint <b>106</b>. A narrower width W may increase the pivotability of the joint <b>106</b> along an axis perpendicular to the central axis A, and a wider joint <b>106</b> may decrease pivotability. The opening <b>404</b> of the adjustment cap <b>300</b> is shown open, which may decrease weight and cost of materials, but in some embodiments the interior of the adjustment cap <b>300</b> may be narrower, walled off, or filled, which may increase strength and help prevent debris from getting to the front side of the joint <b>106</b>. In embodiments having an through-hole at the opening <b>404</b>, a user may reach to the front of the joint <b>106</b>, such as to recover an internal cap <b>308</b> that comes off of the stem <b>312</b>, to clean the front of the joint <b>106</b>, or to hold the internal cap <b>308</b> in place while the adjustment cap <b>300</b> is tightened (in appropriate embodiments). Thus, the opening <b>404</b> in the adjustment cap <b>300</b> may be large enough to receive a finger, hand, or tool of a user depending on the purposes for which the opening <b>404</b> is designed.

The outer surfaces <b>406</b>, <b>408</b> of the resilient members <b>302</b>, <b>306</b>, may be sloped or beveled. Sloped outer surfaces <b>406</b>, <b>408</b> may resist deformation less than straight (i.e., completely horizontal or vertical) outer surfaces <b>406</b>, <b>408</b>, so the profile of the outer surfaces <b>406</b>, <b>408</b> may increase flexibility of the joint <b>106</b> in both axial and off-axial rotation. Shaped (e.g., sloped) outer surfaces <b>406</b>, <b>408</b> may also have controlled deformation, such as reduced buckling or expansion in a desired direction. Other profile shapes of the outer surfaces <b>406</b>, <b>408</b> may be selected based on desired flexibility and compression characteristics of the joint <b>106</b>, such as, for example, chamfered, stepped, semicircular, and other shapes that would be apparent to those skilled in the art having the benefit of the present disclosure.

<figref idref="DRAWINGS">FIGS. 5A-5C</figref> illustrate how a pack frame apparatus <b>500</b> may be positioned and moved relative to a user U. For convenience in viewing and understanding the operation of the pack frame apparatus <b>500</b>, straps, bags, pads, and other features of a backpack that would attach to the user U or the pack frame apparatus <b>500</b> are omitted.

In <figref idref="DRAWINGS">FIG. 5A</figref>, the user U has the pack frame apparatus <b>500</b> positioned on his back with the upper pack frame <b>502</b> positioned relative to his upper torso and the lower pack frame <b>504</b> positioned relative to his lower back/sacral area. The upper pack frame <b>502</b> is connected to the lower pack frame <b>504</b> by joint <b>506</b>. The user U is standing vertically upright (i.e., in a coronal or frontal plane vertically splitting his anterior and posterior sides), and the upper and lower pack frames <b>502</b>, <b>504</b> are roughly vertically aligned at the joint <b>506</b> (i.e., also in the coronal or frontal plane). In a preferable embodiment, this upright position may be the default orientation of the pack frame apparatus <b>500</b>. In this position, the weight borne by the pack frame apparatus <b>500</b> may be evenly distributed to both shoulders and both sides of the waist and hips, so the user U may feel less fatigue while bearing a load in this position. Additionally, in this position the joint <b>506</b> may optimally absorb shock along all three axes of rotation (i.e., axes A (see <figref idref="DRAWINGS">FIG. 3A</figref>), B, and C) since the resilient portion(s) of the joint <b>506</b> are not pre-loaded. Therefore, resilient members between the upper and lower pack frames <b>502</b>, <b>504</b> (e.g., first and/or second resilient members <b>302</b>, <b>306</b> of <figref idref="DRAWINGS">FIGS. 3A-4B</figref>) and the surfaces of the upper and lower pack frames <b>502</b>, <b>504</b> near the joint <b>506</b> may be shaped to be inclined to stay in this position. In some embodiments, there may be no default orientation, and the pack frame apparatus <b>500</b> may pivot at the joint laterally (e.g., in the manner shown in <figref idref="DRAWINGS">FIG. 5C</figref>) without requiring additional resistance to reposition the upper and lower pack frames <b>502</b>, <b>504</b> relative to each other.

<figref idref="DRAWINGS">FIG. 5B</figref> is an illustration of the pack frame apparatus <b>500</b> flexing in torsion due to rotation of the upper torso of the user U. The upper and lower pack frames <b>502</b>, <b>504</b> are still positioned in approximately the same positions relative to the respective parts of the user U as in <figref idref="DRAWINGS">FIG. 5A</figref>, but now the joint <b>506</b> has flexed so that the upper pack frame <b>502</b> has rotated around axes B and/or C. Axes B and C are parallel to (or co-planar with) the coronal plane described in connection with <figref idref="DRAWINGS">FIG. 5A</figref>. The forward part of the joint <b>506</b> (e.g., its internal cap <b>308</b>) is unmoved relative to <figref idref="DRAWINGS">FIG. 5A</figref> since the lower pack frame <b>504</b> has not moved relative to <figref idref="DRAWINGS">FIG. 5A</figref>, but the upper pack frame <b>502</b> has rotated. During energetic activities, movement of the upper pack frame <b>502</b> around axes B and C allows the pack frame apparatus <b>500</b> to be secured more closely to the user U by following his natural body motions. The amount of flexure that permits rotation around axes B and C may be limited by the compressibility and thickness of the materials used as resilient members between the upper and lower pack frames <b>502</b>, <b>504</b>. In an exemplary embodiment, the pack frame apparatus <b>500</b> may allow torsional rotation of up to at least about 20 degrees around axes B and/or C. Controlling the flexibility of the joint <b>506</b> may help prevent the pack frame apparatus <b>500</b> from damaging a cover, pouches, and other equipment attached thereto. Limiting the flexibility of the joint <b>506</b> using resilient materials may also allow the joint <b>506</b> to bias the upper and lower pack frames <b>502</b>, <b>504</b> into the aligned position of <figref idref="DRAWINGS">FIG. 5A</figref> when they are in the positions of <figref idref="DRAWINGS">FIG. 5B</figref> or <b>5</b>C.

Resilient rotation around axis B would correspond with a twisting motion of the wearer (i.e., rotation around the spine), and resilient rotation around axis C would correspond with a bending motion of the wearer (i.e., bending forward toward the toes or arching the spine). The joint <b>506</b> may facilitate one or more of these resilient rotational movements. In some embodiments, the joint <b>506</b> may also provide resilient rotational movement around axis A, as depicted in <figref idref="DRAWINGS">FIG. 5C</figref>.

<figref idref="DRAWINGS">FIG. 5C</figref> illustrates the pack frame apparatus <b>500</b> pivoting laterally at the joint <b>506</b> in response to the user U leaning laterally to his right (i.e., within the coronal plane of the joint or around an axis normal to the coronal plane). In an exemplary embodiment, the pack frame apparatus <b>500</b> may allow pivotal motion in this plane of at least about 45 degrees relative to the vertical position. In some embodiments, the pivotal motion may be at least about 30 degrees in this plane. Similar to the pack frame apparatus of <figref idref="DRAWINGS">FIG. 5B</figref>, the lower pack frame <b>504</b> remains motionless relative to the user U but the upper pack frame <b>502</b> rotates with his upper torso. In the embodiment shown, the joint <b>506</b> may have very low friction and resistance. In embodiments where there is curvature to a resilient member between the upper and lower pack frames <b>502</b>, <b>504</b> or between at least one of the upper and lower pack frames <b>502</b>, <b>504</b> and the joint <b>506</b> (e.g., an adjustment cap <b>300</b> or internal cap <b>308</b>), and therefore there is resistance to relative pivoting between the upper and lower pack frames <b>502</b>, <b>504</b>, the lower pack frame <b>504</b> would likely rotate slightly at the joint <b>506</b> due to biasing forces provided by the resilient member(s) attempting to align the upper and lower pack frames <b>502</b>, <b>504</b>. The lower pack frame <b>504</b> may also be in the position shown in <figref idref="DRAWINGS">FIG. 5C</figref> due to straps attaching the lower pack frame <b>504</b> around portions of the user U that have not moved between <figref idref="DRAWINGS">FIGS. 5A</figref> and SC, such as around the pelvis of the user U.

While using the pack frame apparatus <b>500</b>, the user U may naturally move in multiple directions simultaneously. For example, the user U may pivot the joint <b>506</b> while torquing the upper and lower pack frames <b>502</b>, <b>504</b> simultaneously. Thus, the motions of <figref idref="DRAWINGS">FIGS. 5B and 5C</figref> may be enacted at once. The pack frame apparatus <b>500</b> may follow these natural movements while bearing a load and while being attached or strapped to the user U. The upper and lower pack frames <b>502</b>, <b>504</b> may therefore be beneficially constructed of rigid, weight-bearing materials since the joint <b>506</b> provides flexibility at the crucial mid-torso area. The pack frame apparatus <b>500</b> may also be beneficially positioned nearer to the torso of the user U throughout these motions than a rigid pack frame would be, providing the user U with improved balance and less shaking or other motion of the pack and/or its contents while in motion.

Another embodiment may include a method of providing a pack frame apparatus. The method may comprise providing a first plate and a second plate, wherein the first and second plates may be adapted to provide structural support to a pack frame. The first plate may be positioned for support of an upper back portion of a user through attachment to a shoulder strap, and the second plate may be positioned for support of a lower back portion of the user through attachment to a waist strap. The method may also comprise pivotally joining the first plate with the second plate such that the plates are relatively rotatable in at least a first direction and resiliently relatively rotatable in a second direction. Thus, the plates may rotate in a first direction without resilient resistance, and the plates may rotate in a second direction with resilient resistance. In another embodiment, the plates may rotate in the first direction with resilient resistance as well. The resilient resistance may cause the plates to bias to a default orientation. For example, the resilient resistance may bias the plates toward a vertical, upright position with the first and second plates about parallel where they are joined together.

The first and second plates may be broad, generally flat parts and at least semi-rigid in comparison to the resilient features that join them. In some embodiments, portions of the plates may be more flexible than others, such as, for example, by having a more flexible material where they are joined, or by having openings or relief holes in portions of the plates that allow them to resiliently deflect or deform. The plates may have openings, slots, or holes through their surfaces to reduce weight, increase zonal flexibility, or for other reasons, such as those set forth above in connection with the slots <b>110</b>, <b>112</b> and openings <b>116</b> of the upper and lower pack frames <b>102</b>, <b>104</b>.

The method may also include a step of joining the first plate with the second plate by inserting a resilient member between the first and second plates. The first and second plates may then be joined for pivotal movement along the first direction around the inserted resilient member. In another embodiment, the method may include attaching the joined first and second plates with a backpack having shoulder straps and a storage compartment. In some embodiments, the relative rotation of the first and second plates may be adjusted in at least the second direction by tightening or loosening a member joining the first and second plates. In some embodiments, this may entail adjusting part of the joint (e.g., an adjustment cap <b>300</b>) relative to the rest of the joint or the plates. The relative rotation between the first and second plates may be biased to assume a default position in at least one of the at least two directions. This may be accomplished in the manner described in connection with <figref idref="DRAWINGS">FIGS. 3A-3D</figref> above. Additional steps may include forming and arranging the parts of the joint <b>106</b> and upper and lower pack frames <b>102</b>, <b>104</b> as described above. In some embodiments, the steps of these methods may be reordered or combined.

The previous description of the disclosure is provided to enable a person skilled in the art to make or use the disclosure. Various modifications to the disclosure will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other variations without departing from the spirit or scope of the disclosure. Throughout this disclosure the term “example” or “exemplary” indicates an example or instance and does not imply or require any preference for the noted example. Thus, the disclosure is not to be limited to the examples and designs described herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.