Adipo-mimetic motion-control hydration system pack

Abstract

An improved hydration system for runners that provides superior motion control. Fluid is contained within a flexible bladder and pack, and attached to the waist. The pack is constructed of comfortable, elastic, and thermally insulating fabric. When attached to the waist, tension in the fabric compresses the bladder against the user and dampens motion. Along with reduced thickness of the fluid-filled bladder, uniform distribution of fluid in the bladder contributes to motion control and is provided by placement of the zipper in a horizontal orientation across the lower portion of the pack. Additional stability is achieved by attachment of waist straps at angles above horizontal, thereby increasing tension across the top portion of the pack, preventing it from flopping away from the user's body.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of Provisional Patent Application Ser. No. 60/478,419, filed Jun. 16, 2003.

FEDERALLY SPONSORED RESEARCH

Not Applicable

SEQUENCE LISTING OR PROGRAM

Not Applicable

BACKGROUND

1. Field of Invention

This invention relates to the field of personal hydration systems used by runners or joggers.

2. Discussion of Prior Art

Running, cycling, and other forms of exercise produce an increased need for water intake to compensate for that lost by respiration, perspiration, and renal output. This need, if not met, may become life threatening during prolonged high-intensity activity in hot weather. It is therefore desirable to be able to carry on one's person an adequate supply of water or other hydrating fluid.

Although hydration systems are in common use by cyclists, prior art hydration systems for runners have not met one essential design criterion: The device must utilize a stable, non-irritating waist-mounted system with sufficient motion control to minimize bounce and sway. Manufacturers of back-mounted hydration packs have attempted to adapt these devices for runners so that they may be worn about the waist. These waist-mounted packs are essentially back-mounted designs retrofitted with a waistband, and are constructed without consideration of the unique needs of runners.

Because a cyclist has little oscillatory body motion compared to a runner, a back-mounted pack can be attached with loose shoulder straps. Furthermore, since there is little motion of the pack relative to the user's back, the pack can be constructed of inelastic woven nylon or polyester fabric. However, running produces substantial running-related movement of the muscles about the waist and hip area. To achieve sufficient motion control, the waistband must be cinched tight to prevent motion of the pack. However, as the tension of the waistband increases, so does the pressure on the user's muscles, tendons, and other tissues. As a result, the user of such packs is faced with a dilemma: if too loose, the pack will have too much motion, and if too tight, the result is discomfort and possible injury. Since the tissue of the waist area is in motion, the pack itself must be sufficiently pliant so that it can move with the runner. Inelastic fabric does not allow for this, and may represent a potential source of injury to runners who use such systems.

Another problem that arises with the use of inelastic cloth relates to the ability of the fabric to prevent motion of the bladder within the fabric pack. The basic design of all hydration packs is a bladder within a fabric bag or pack. When the pack is constructed of inelastic fabric, the maximum tension against the bladder is achieved only when the bladder is filled to the point where its volume is equal to the volume of the fabric compartment. As fluid is drained from the bladder, the volume of the bladder decreases, but the volume of the fabric bag does not. The bladder is thus free to bounce around, producing excessive motion of the system. Some systems utilize additional straps to take up the slack created by decreasing bladder volume; however, these must be continually tightened as the bladder is drained, and this is inconvenient.

Prior art hydration systems suffer from additional problems. Because of gravity and the flexible nature of the bladder, fluid pools in the bottom of the bladder. This produces an uneven distribution of the fluid within the bladder, producing sloshing as a result of the increased moment of inertia of the fluid within the bottom portion of the pack.

Given that hydration systems are most useful in hot weather, thermal insulation is essential to prevent fluid warming. However, prior art packs employ a design in which additional thermal insulation is sewn into the fabric pack, and this increases both the complexity and cost of construction. Ideally, the fabric used in construction of the pack would have a combination of the desired mechanical and thermal properties so as to provide both motion control and thermal insulation.

OBJECTS AND ADVANTAGES

It can be seen that prior-art hydration systems for runners suffer from a number of problems, including:

• • a) insufficient motion control resulting from inefficient immobilization and attachment of the bladder and pack;
  • b) discomfort due to inelastic fabric;
  • c) inefficient incorporation of thermal insulation leading to complexity of construction resulting in increased production costs.

Accordingly, several objects and advantages of the present invention include:

• • a) to provide a means for attaching a flexible fluid-filled bladder to the waist such that motion of the bladder is dampened and minimized as a result of compression against the runner's body;
  • b) to prevent pooling of liquid in the lower portion of the bladder while maintaining ease of cleaning and air drying of the bladder;
  • c) to provide a means for attaching the flexible fluid-filled bladder to the waist such that the pack is comfortable and does not irritate sensitive underlying tissue;
  • d) to provide efficient incorporation of thermal insulation to the hydration system;

Other objects and advantages will become apparent from a consideration of the following description and drawings.

SUMMARY

The following invention is a personal hydration system designed for runners and joggers, and consists of a flexible bladder to contain potable fluid. The bladder is enclosed in a flexible, elastic fabric pack and fastened about the waist of the user. The flexible fluid-filled bladder is restrained by compression against the user's body by the tensioned outer fabric layer of the pack. Because tension in the elastic outer fabric layer is maintained automatically as the bladder volume decreases with fluid consumption, compression of the bladder against the user's body is maintained at all times, providing constant motion control. In the present design, the zipper, in addition to allowing insertion of the bladder into the pack, also functions as a structural element. By placing the zipper in a horizontal orientation across the lower portion of the pack, the pack is unable to stretch in the region of zipper attachment. As a result, the zipper acts as a baffle, constricting the lower portion of the bladder and preventing excessive pooling of fluid within this region. This reduces the moment of inertia of the bladder within the lower portion, resulting in significant motion control. An additional structural feature involves the angle of attachment of the webbing that wraps around the waist of the user. Placement of the webbing at an angle above horizontal relative to the horizontal axis of the pack produces increased tension in the upper portion of the pack, preventing this portion of the pack from flopping away from the user's body, thereby increasing stability of the pack as a whole.

DRAWINGS

Drawing Figures

FIGS. 1A and 1B show front and rear elevation views of the bladder, respectively. FIGS. 1C, 1D, 1E, and 1F show rear elevation views of bladders with different aspect ratios and different distribution of the widest extent about the vertical axis.

FIG. 2A is a front elevation view of the pack assembly showing placement of the zipper and angle of the attached webbing. FIG. 2B is a fragmentary front elevation view of the pack assembly showing alternate means of attachment of waist straps to the pack.

FIG. 3 is a front elevation view of the pack assembly showing placement of upper pack tensioning straps.

FIG. 4 is a fragmentary front perspective view of the pack.

FIGS. 5A and 5B are cross-sectional views taken about line 5 of FIG. 4 and show the effect of the elastic pack fabric on compression of the enclosed bladder.

FIGS. 6A and 6B are cross-sectional views taken about line 6 of FIG. 4 and show the effect of zipper placement on the vertical distribution of fluid in the bladder.

FIGS. 7A and 7B are side perspective views of the pack showing the effects of both sipper placement and angle of webbing attachment on the distribution of fluid within the pack.

FIGS. 8A, 8B, and 8C show distribution of forces across the face of the pack and the enclosed bladder as a function of webbing angle and zipper placement.

REFERENCE NUMERALS IN DRAWINGS

• 11 Bladder cap 34 Right tension strap buckle
• 12 Bladder opening 42 Right waist strap
• 13 Tube outlet coupling 43 Tri-glide/ladder lock
• 20 Hydration pack 44 Right buckle element
• 21 Outer fabric layer 45 Left buckle element
• 22 Inner fabric layer 46 Left waist strap
• 25 Zipper 80 Runner
• 26 Bladder compartment stitching 90 Bladder
• 31 Left upper tensioning strap 91 Bladder—front face
• 32 Right upper tensioning strap 93 Bladder—rear face
• 33 Left tension strap buckle

DETAILED DESCRIPTION

FIG. 1A discloses a bladder 90 filled through a cap 11 and which contains fluid for drinking. The bladder is constructed of two layers of durable food- or beverage-grade plastic film such as PVC or urethane. A front layer 91 is apposed to a rear layer 93 shown in FIG. 1B and sealed around the edges using a suitable method such as ultrasonic, dielectric/RF welding, adhesive, or thermal impulse sealer. The two layers thus define an inner compartment that holds a potable fluid. Fluid exits via a tube outlet coupling 13 that attaches to the front face and which has a lumen contiguous with the interior of the bladder. A tube (not shown) attaches to the outlet coupling and can be used to deliver fluid to the mouth of the user in a number of possible ways not considered here. Prior art hydration systems generally use a bladder with a rectangular outline and rounded corners. The present design uses a bladder with an outline that has no straight edges or corners. Although there are a number of possible variations, the present design uses a shape that approximates an ovoid. The key defining features of the bladder geometry are these: the bladder is defined by vertical and horizontal axes denoted as V and H respectively, where V is the height of the bladder at its greatest vertical extent, and H is the width of the bladder at its greatest horizontal extent, where 0.5≦(V/H)≦2.0. In FIGS. 1A and 1B, V/H=1.0. FIG. 1C shows a bladder where V/H=2.0, and FIG. 1D shows a bladder where V/H=0.5. In all cases, the bladders shown here exhibit bilateral symmetry about the vertical axis V, but do not necessarily show bilateral symmetry about the horizontal axis H. Furthermore, although FIGS. 1A through 1D show that the widest extent H of the bladder is within the lower region of the bladder, this is not the only possible configuration; as seen in FIG. 1E, it is possible to configure a bladder in which the widest extent H is in the upper region of the bladder. Also, if the widest extent H is located at the midpoint of the vertical axis V, then the bladder may also exhibit bilateral symmetry about the horizontal axis H (FIG. 1F). Therefore, it can be seen that there is a wide range of possible bladder configurations subject to the constraint that there are no sharp corners, i.e., the bladder does not have a rectangular, trapezoidal, or other n-sided geometric shape, but rather, has rounded edges and approximates an ovoid.

FIG. 2A is a more detailed view of the invention. The bladder 90 (hidden here) is contained within a pack 20 which is composed of at least two layers of thermal insulating elastic fabric, with an outer layer 21 being shown here attaching to an inner layer 22 which is hidden in this view. In the preferred embodiment, 3-5 mm thick neoprene fabric is used, and is seamed about the edges. The bladder 90 is removed from and inserted into the pack 20 via a zipper 25. The pack 20 is mounted about the waist by means of a left side waist strap 46 which is attached to the left side of the pack 20 on one end and attaches on the other end to a left buckle element 45. A right side waist strap 42 is attached to the right side of the pack 20 on one end and attaches on the other end to a right buckle element 44. The left buckle 45 and the right buckle 44 snap together to constrain the pack 20 about the waist of a user 80. FIG. 2B shows an alternate means of attachment of the waist strap 42 to the pack. Rather than sewing the right webbing strap 42 directly to the right side of the pack 20, a fastening element (tri-glide or ladder-lock) 43 is attached to the pack, and the waist strap 42 threads through the fastening element 43. This method could also be employed on the left side as well (not shown). Using this method, the tri-glide/ladder-lock 43 allows adjustability of the waist strap length at the point of attachment to the pack 20, allowing for greater flexibility in waist strap adjustment if desired by the user.

Two key features of the pack design contribute to motion control of the enclosed fluid-filled bladder. Because of the elastic nature of the fabric, the pack is comfortable to wear, as it flexes to move with the movements of the runner. However, the elastic nature of the fabric can allow fluid to pool in the bottom of the bladder as a result of gravity. To counteract this while still maintaining comfort, placement of the zipper in a horizontal orientation across the lower portion of the pack restrains the fluid in this region. The mechanism for this is apparent: given that the zipper is inelastic, it prevents stretching of the pack material and distension of the bladder at this region. As a result, a portion of the fluid within the bladder is forced upwards, resulting in a more even vertical distribution of fluid within the bladder. In testing, it was found that the ideal distance of the zipper from the bottom of the pack, shown by the arrow z, was approximately one fourth the length of the vertical axis, shown here by the arrow V. However, depending on the shape of the bladder, ratios of z/V of between 0.15 and 0.5 were found to be suitable.

The fluid-filled bladder behaves very similarly to adipose tissue, and if a sports bra is used as a model for comparison, the design can be thought of as an approximation of the adipose tissue of breasts, which are restrained in a similar fashion by elastic fabric that produces a compression of the adipose tissue against the user's body. For this reason, the present design is adipo-mimetic in that the flexible fluid-filled bladder mimics the behavior of adipose tissue. Although most of the support and immobilization comes from the elastic tensioned fabric of the pack, the zipper, by functioning similarly to an under wire in a sports bra, provides an additional level of support due to its inelastic properties.

Placement of the waist straps 42 and 46 at angles relative to the horizontal axis of the pack H produces further stability. In testing it was found that placement of the straps parallel to the horizontal axis resulted in unequal distribution of tension across the pack, with the result being that the upper portion of the pack would tend to fall away from the user's back, producing an unpleasant flopping action. By placing the straps at an angle θ above the horizontal axis, greater tension is produced across the upper portion of the pack, which is then tensioned firmly against the user's back. Testing of prototypes found that an angle θ of between 15° and 60° produced the most efficient mobilization of the pack. An additional element of construction involves a row of stitching 26 through front and back layers of the pack, thus defining a compartment within which the bladder is constrained, and preventing lateral movement of the bladder within the pack. The tapered portions of the pack lateral to the stitching 26 act as transition zones between the large bladder-containing portion of the pack and the more narrow waist straps 42 and 46. These transition zones act to distribute the tension generated by the waist straps 42 and 46 more uniformly across the bladder.

An alternate embodiment to the angled strap arrangement is shown in FIG. 3. Rather than placing the waist straps at an angle, the purpose of which is to increase tension across the top portion of the pack, it is also possible to increase tension through the use of additional adjustable straps. A left upper tensioning strap 31 attaches to the left upper portion of the pack 20, and is secured to the left waist webbing strap 46 by means of a buckle 33. Similarly, a right side upper tensioning strap 32 attaches to the up right portion of the pack and is secured by means of a right buckle 34. It is also possible to omit the buckles 33 and 34 and simply sew an inelastic cord or strap onto both the left and right upper lateral portions of the pack. Functionally, the results of these different embodiments are similar, namely to increase tension across the upper portion of the pack, preventing it from flopping away from the user's back. However, because of the simplicity of construction, attaching the waist straps to the pack at an angle above horizontal is the preferred embodiment, as it results in simplified construction and reduced production costs.

FIG. 4 is a fragmentary perspective view of the pack 20. FIGS. 5A and 5B are cross-sectional views taken about the line 5 shown in FIG. 4. In FIG. 5A, no bladder is inserted, and it can be seen that the outer and inner fabric layers 21 and 22 are in direct apposition. FIG. 5B shows the pack after insertion of the fluid-filled bladder 90. The bladder is constrained within the pack by the stitching 26. Because the pack is under significant tension when placed about the user's waist, and because the user's back is relatively non-deformable, the bladder distorts only the outer layer 21. As a result, regardless of whether the bladder is empty, full, or somewhere in between, there is never any void space within the pack to allow the bladder to slosh around. This is in marked contrast to hydration packs constructed of inelastic nylon or polyester fabric. These packs have a compartment of constant volume, yet the enclosed bladder has variable volume that is a function of the amount of fluid contained within. Therefore, even if the bladder is stuffed snugly into one of these packs when it is completely full, after just a few sips of fluid, the bladder volume decreases but the pack volume does not, and the result is void space that allows the bladder to bounce around within the pack.

FIGS. 6A and 6B are cross-sectional views taken about the line 6 shown in FIG. 4. FIG. 6A shows the pooling of fluid in the bottom of the bladder 90 when the zipper is placed horizontally either at the very top or very bottom of the pack, or in a vertical orientation. As a result of gravity and the elastic outer fabric layer 21, the fluid within the bladder pools at the bottom, resulting in an uneven vertical distribution of fluid. The thickness of the bladder, defined as the greatest extent normal to the surface of the user's back, is shown by the arrow D. FIG. 6B shows the effect of zipper placement of the present invention. Because the zipper 25 is inelastic, distension of the bladder and the pack at the region of zipper placement is reduced. As a result, the bladder is pinched at this point, and a portion of the fluid is forced into the upper portion of the bladder, producing a more even vertical distribution of fluid within the bladder 90. Here, the thickness of the bladder, shown by the arrow D, is reduced relative to FIG. 6A. The zipper thus becomes not just a means for accessing the interior of the pack, it also becomes an important structural element that contributes to the motion control of the bladder and pack. Again, using a sports bra as a model for comparison, the inelastic zipper, with respect to the upper pool of fluid, functions similarly to an underwire, resulting in increased support and motion control. An additional consideration here is the minimum thickness D that can be obtained in the bladder with uniform vertical distribution. This is a function of the volume of fluid contained in the bladder, and the overall dimensions of the bladder, V and H which are shown in FIGS. 1A-1F. In the preferred embodiment shown in FIGS. 1A and 1B, V and H are approximately 25 cm; when filled with 1.4 l of fluid, the thickness D is about 4 cm. This is in marked contrast to other systems on the market, which have a much greater thickness D. For example, the CamelBak FlashFlo™, when filled with 1.4 l of fluid, has a measured thickness D of about 8 cm; other systems have comparable dimensions. The result of this large thickness D is an increased moment of inertia, resulting in greater bladder motion and resultant forces on the tissues of the user. Optimal motion control is thus provided not only by the motion control features of the pack, but also by the dimensions of the bladder. The desired shape of the filled bladder is one in which the thickness D is minimized, within the constraints of the vertical and horizontal dimensions V and H. Constraints on the upper limits V and H are determined both by the body size of the typical user, and by the increased surface area, and increased rate of warming of the fluid that results from increased bladder surface area. It would be possible to reduce D even further, but at the expense of increased surface area of the bladder and pack. Testing has shown that the dimensions specified here provide an optimum balance of reduced thickness D with minimal surface area, resulting in optimum motion control without an excessive surface area that would contribute to warming of the fluid contained within the bladder. Testing of prototypes has revealed that a thickness D significantly greater than 4 cm results in a large moment of inertia and produces excessive bouncing of the bladder and pack. Therefore, it is desirable, if different maximum volumes are required, to vary the dimensions V and H to increase or decrease the maximum volume while still maintaining a thickness D of less than about 4 cm.

FIGS. 7A and 7B show the effect of the webbing attachment angle and zipper placement on fluid distribution and pack placement on the user 80. In FIG. 7A, the zipper is placed either at the very bottom or at the very top, or it is oriented vertically. Here it can be seen that the fluid tends to pool at the bottom of the pack 20. Furthermore, the pack tends to fall away from the user's back at the top as a result of unequal distribution of tension from the webbing 42 on the right side and the webbing 46 on the left side (hidden in this view). FIG. 7B shows the results of zipper placement and webbing angle described in the present invention. Placement of the zipper 25 at the lower portion of the pack 20 results in displacement of a portion of the fluid within the pack in an upwards direction resulting in a more equal vertical distribution of fluid within the pack. The zipper thus acts not only as a compressive member to force fluid upwards, but also as a partial baffle. By partially isolating the bottom pool of fluid from the top pool of fluid, the bladder behaves not as one large pool, but as two semi-autonomous smaller pools. As a result, the two partially separated pools produce far less net motion than one large pool of fluid. Furthermore, placement of both the right and left webbing straps 42 and 46 at a positive angle relative to the horizontal axis of the pack results in greater tension across the top of the pack, preventing the upper portion of the pack from flopping away from the user's body.

FIGS. 8A, 8B, and 8C show the effect of webbing angle on distribution of tension across the pack surface. In FIG. 8A, the straps 42 and 46 are oriented parallel to the horizontal axis of the pack. When the pack is mounted about the user's waist, tension is developed in the straps 42 and 46 in opposing directions and parallel to the long axis of the pack shown in FIG. 2. Here the greatest tension is directly across the pack in a horizontal direction. As a result, relative to the middle portion of the pack, tension across the bottom and top is significantly less. As a result of gravity, fluid tends to pool in the bottom of the pack, and the top portion of the pack flops away from the user's back, as shown in FIG. 7A. FIG. 8B shows the present design prior to tensioning of the straps. Because the straps 42 and 46 are placed at an angle relative to the horizontal axis of the pack, the distribution of tension across the pack is more efficient than that seen in FIG. 8A. Furthermore, placement of the inelastic zipper 25, which prevents stretching of the fabric in this region, also alters the distribution of forces across the pack. As a result of both the webbing angle attachment and zipper placement, upon tensioning of the waist straps 42 and 46, there is a more even distribution of tension across the pack as seen in FIG. 8C.

Description and Operation of Alternative Embodiments

Although the above description contains many specifics, these should not be construed as limiting the scope of the invention, but as merely providing illustrations of some of the preferred embodiments of this invention. For example, although the zipper placement is chosen for its motion-damping qualities, it would be possible, although more complicated, to place the zipper elsewhere on the pack, and sew an additional inelastic ribbon, cord, or adjustable strap in the lower portion of the pack. Similarly, placement of the straps at an angle above horizontal produces an increase in tension across the top of the pack, preventing it from flopping away from the user's body. In addition to the adjustable straps shown in FIG. 3, this effect could also be achieved simply by sewing inelastic ribbon or cord into the top lateral portions of the pack; like the zipper, these would increase tension by decreasing fabric stretch in this region. Many possible variations in the shape of the bladder are also possible within the constraints described.

Conclusion, Ramifications, and Scope of Invention

Accordingly, the reader will see that the hydration system for runners described herein represents a significant improvement over previous designs, and solves a long-felt need for runners, particularly those who reside in hot climates. The flexible bladder can be filled with several liters of cold liquid and ice to ensure that the fluid will remain cold during long hot runs. The flexible, elastic, and thermally-insulating fabric pack attaches securely about the waist, provides superior motion control without restricting movement of the runner's musculature or other soft tissue, and is unobtrusive due to its low profile. The pack is pre-stressed and self-adjusting to provide tension as the bladder volume changes.

Claims

1. A hydration system for runners comprising:

a) a waist pack formed by joining at least two sheets of elastic fabric about the perimeter, said sheets forming an outer layer and an inner layer of fabric, said layers defining an internal compartment;

b) a flexible bladder for containment of fluid, said bladder having a fluid holding capacity of between about 1 and 3 liters, and contained within the inner compartment of said waist pack;

c) said waist pack having an inelastic member attached to the front sheet, said inelastic member being placed in a horizontal orientation within the lower front portion of the pack, said lower portion being defined as being between 0.15 and 0.5 times the greatest vertical extent of said pack from the lowest vertical extent of said pack, resulting in motion control as a result of the inelastic nature of said member constricting said flexible bladder within the region of the inelastic member, resulting in a partial baffle effect and more even distribution of fluid in the vertical direction;

d) means for attaching said pack about the waist of the user, said means comprising straps attaching at their proximal ends to left and right side of said pack and being secured at their distal ends by buckles about the user's waist;

2. The hydration system of claim 1 where said sheets of elastic fabric are thermally insulating;

3. The hydration system of claim 1 where said inelastic member is a zipper;

4. The hydration system of claim 1 where said waist straps are attached to the lateral edges of the pack, said straps being oriented at an angle between 15° and 60° above the horizontal axis of said pack;

5. The hydration system of claim 1 where said bladder, when filled to capacity, has a maximum thickness, measured normal to the surface of the bladder to the surface of the user's back, of about 4 cm or less;

6. The hydration system of claim 1 and further including means for increasing tension about the upper portion of the pack, said means including inelastic elements sewn about the upper lateral portions of the pack, thereby reducing stretch and increasing tension in this area;

7. A hydration system comprising a waist pack formed by joining apposed front and back layers of elastic thermally-insulating fabric, said fabric layers being joined about the perimeter and thus defining an inner compartment for containment of a flexible bladder for containing between about 1 and 3 liters; said bladder having a shape approximating that of an ovoid; means for attaching pack about the waist of the user, said means comprising straps or webbing attached to the lateral edges of said pack, said straps being oriented at an angle of between 15° and 60° above the horizontal axis of said pack, said orientation providing increased tension across the upper portion of said pack, said increased tension acting to draw upper portion of said pack and bladder firmly against the body of the user; an inelastic member sewn in a horizontal orientation across the lower front portion of said pack, said lower portion being defined as being between 0.15 and 0.5 times the greatest vertical extent of said pack from the lowest vertical extent of said pack.

8. The hydration system of claim 7 where said inelastic member is a zipper.

9. The hydration system of claim 7 where said bladder, when filled to capacity, has a maximum thickness, measured normal to the surface of the bladder to the surface of the user's back, of about 4 cm or less;