Hammock With Adjustable Curvature
This invention relates to a hammock for use by people for leisure or sleeping. It provides adjustable features that allow the users longitudinal curvature to be flat, or curved upward, or curved downward, or both with the head and feet raised to different and opposing levels with respect to the flat configuration. This adjustable longitudinal curvature control enhances user comfort during leisure and enhances the ability to sleep in this hammock.
Not applicable.
REFERENCE TO SEQUENCE LISTING, A TABLE, OR A COMPUTER PROGRAM LISTING COMPACT DISC APPENDIXNot applicable.
BACKGROUND OF THE INVENTIONThis invention relates to a hammock for use by people who wish to lay down in a prone and essentially flat position for leisure or sleeping.
Hammocks provide a user with a bed like surface for body support that can be connected between upright structures (e.g. trees, posts, fixed walls, etc.) on which a person may lie suspended above the ground. Traditional hammocks are typically constructed of a sheet of material, often flexible fabric (e.g. canvas, nylon fabric, netting, ropes, etc.) gathered at the ends and suspended from upright structures by ropes, straps or like means.
One drawback of traditional hammocks is known as hammock sag, whereby the middle of the hammock sags below the ends creating a longitudinally curved supporting surface. Such a curve along the users' longitudinal surface may be uncomfortable for the occupant as it does not follow the natural profile that the person's body will take when lying down on a typical flat bed, and the upward curvature often bothers a users knees because the users legs are straight and do not get adequate support from the longitudinal curved hammock surface in the middle so the knees tend to hyperextend and become stressed and uncomfortable. Furthermore, traditional hammocks are unstable and prone to tipping, and are not user adjustable adequately, other than tensioning the hammock, for slight control of the users' body longitudinal curvature.
PRIOR ART IN THIS AREA INCLUDESThere have been a number of attempts to provide so-called self-leveling hammocks in an effort to reduce the aforementioned problems. For example, Brazilian hammocks provide an extra wide sleeping surface so that a person may lie diagonally. Such hammocks require extra material and an occupant must be careful not to move into a non-diagonal position. U.S. Pat. No. 6,701,549, U.S. Pat. No. 645,805, U.S. Pat. No. 249,403, U.S. Pat. No. 202,814, U.S. 2002/0042951 and 30 U.S. 2004/0006820 all describe various ways of compensating for hammock sag.
U.S. Pat. No. 7,020,915 also uses a suspension type hammock design, but it attempts to preplan a manufactured in location for knee and lumbar support for a user that are not adjustable and therefore cannot meet the geometry requirements of a 5th percentile to 95th percentile user. Further it incorporates closed ends with storage areas that add weight, cost, and added installed length requirements for the design. Further the closed end designs are not ideal for use in hot and humid environments due to the closed ends blocking of cooling wind and breezes.
None of these prior art designs have been wholly successful at providing a comfortable, stable, substantially flat sleeping surface in a portable, easy to set-up hammock, and adjustments are limited, cumbersome, complex or nonexistent.
This invention overcomes all of these aforementioned limitations in the prior art. It allows a user to adjust the hammock for a flat prone sleeping position based on their own body geometry and weight and installation location variations. This invention also allows adjustments to provide a longitudinal body curvature upward, downward, or both varying from head to foot. This adjustability in longitudinal body curvature combined with the natural compliance of a suspension type hammock using slightly compliant materials like nylon webbing for the main tensile suspension member and nylon fabric (or similar high strength sheet materials) for the support surface provides ideal and adjustable support for lumbar and knees as well as head and feet position with respect to body position. This invention also has an open geometry with no extra flaps or storage areas to block a breeze allowing good open-air exposure suitable for added comfort in hot and humid environments.
This invention also has two attachment variations, first a long set of mounting straps built into the hammock for general purpose attachment using these longitudinal oriented straps between vertical supports like trees when the longitudinal length of the installation is not constrained in dimension, and second a short set of loops built in allowing connection to rigid mounting points oriented laterally directly at the end of the hammock when a fixed site installation is desired and the longitudinal dimension is limited. This invention is also a practical and efficient minimalist design that is light weight, and lowers the cost of manufacture making it more suitable to campers and backpackers and other larger market segments, and due to its light weight, simplicity and potential for lower cost.
BRIEF SUMMARY OF THE INVENTIONThis invention relates to a hammock for use by people for leisure or sleeping. It provides adjustable features that allow the users longitudinal curvature to be adjusted to be more flat, or curved upward, or curved downward, or both with the head and feet raised to different and opposing levels with respect to the flat configuration. This adjustable longitudinal curvature control enhances user comfort during leisure and enhances the ability to sleep in this hammock.
This invention carries the horizontal tensile loads due to the weight of the user in the hammock by using a suspension means composed of two flexible tensile suspension member on either side of the hammock, like a suspension bridges main suspension cable, with the user supporting fabric or sheet surface blank draped between and below the suspension member. The fabric or sheet user support surface, also called a blank or bed surface, uses smoothly curved side profiles that are symmetrical side to side and are narrower in the center of the hammock and wider at each end.
The profile of the curved sides may use a partial section of a parabola, catenary curve, circle, ellipse, hyperbola or similar suitable transcendental function, where said fabric blank sides are supported in tension laterally from side to side only and drape down laterally along the full length of each side. The fabric blank can use a continuous attachment loop of excess side material to wrap around the suspension member, or a sewn seam or similar means of attaching it to the main suspension members routed longitudinally on either side.
Adjustment of a user's longitudinal curvature is possible for a given range of load conditions during manufacture by adjusting the ratio of the hammock support fabric width in the center of the hammock to the width at each end. Adjustment of the hammock by a user to adjust the users longitudinal curvature is also possible by an end user after the time of manufacture and during set-up prior to use with two approaches, first by adjusting the tension in the hammock between the supporting attachment points, and second by providing for a user adjustment of the side to side dimension between the two high-tension flexible suspension load bearing members (nylon webbing), by using adjustable width cross brace or cross brace or lateral support members with one at each end of the hammock.
The adjustable width cross brace or lateral support member may be made using a discrete number of tubes attached end-to-end, or a telescoping pole with clamps to hold a given dimension, or telescoping tubes with pins or attached spring loaded pins to allow cross brace or lateral support member length adjustment. However, for the lowest weight and cost and reliability the preferred embodiment of the adjustable width cross brace or lateral support member is a discrete number of tube sections that can be user adjusted to allow control of the members length, and therefore the width when installed at the hammock ends.
In the preferred embodiment this adjustable width cross brace or lateral support member consists of a multitude of tubes connected together with connecting cylinders, such that the user can use fewer or more of said cylinders to achieve control over the extended length of the cross brace or lateral support member (corresponding to the lateral width of one end of the hammock between the suspension members) and thereby the width of the hammock on each end. By increasing the separation between each sides flexible suspension load bearing members with the adjustable width cross brace or lateral support members, a user can control how much to raise the respective end area of the hammock with respect to the nominal flat configuration, and conversely by bringing the flexible suspension load bearing members closer together using the adjustable width cross brace or lateral support members, a user can control how much to lower the respective end area of the hammock with respect to the nominal flat configuration.
At both ends of each adjustable width cross brace or lateral support member is a retaining feature, designed to allow one end loop and strap segment of the high-tension flexible suspension load bearing member (webbing) to be routed through a hole or slot and also attach to or constrain the cross brace or lateral support member end, thus retaining the webbing at a controlled width at the end of the hammock based on the users control of the cross brace or lateral support member length.
Attachment points for the flexible suspension load bearing members on the end of the hammock can be done either using short loops, formed integrally with the end straps, for applications where the longitudinal dimension allowed by installation site constraints is an issue, or full-length straps terminating in loops where ample longitudinal length is available and lower overall weight is a priority. These are two alternate configurations, or they can be merged into a single strap design with both short loops and long loops on the same strap, as a variation of this invention. Further, the long straps can be tied with a knot near the hammocks end to also implement the short strap variation. These two alternatives are shown as variations in this invention disclosure, but it is to be understood that all variations of short and long straps with looped ends or other high-tension flexible suspension load bearing members end attachment provisions are incorporated in this invention.
In addition to suspending the hammock from a typical vertical support like a pair of trees or poles, the shorter loop configuration is also suitable for installations that can provide four rigid supports for all four attachment points, and preferably also two or more lateral distances between support points in place of the cross brace lateral support members, so that applications to marine, submarine and specialty automotive and similar applications can be accomplished in a compact and comfortable fashion.
Aside from the preferred embodiment or embodiments disclosed below, this invention is capable of other embodiments and of being practiced or being carried out in various ways. Thus, it is to be understood that the invention is not limited in its application to the details of construction and the arrangements of components set forth in the following description or illustrated in the drawings. If only one embodiment is described herein, the claims hereof are not to be limited to that embodiment. Moreover, the claims hereof are not to be read restrictively unless there is clear and convincing evidence manifesting a certain exclusion, restriction, or disclaimer.
This improved hammock design utilizes a dual high-tension suspension element type design approach. This approach is analogous to a roadway suspension bridge that uses two top cables on either side of the road supported below, with high-tension top cable strength and support capability, and a plurality of smaller cables draped down to support the road surface.
However, due to this inventions use of slightly compliant materials for the fabric blank support sheet that are common for making hammocks, like nylon webbing for high tension suspension cable application and nylon or polyester (for instance) sheet fabrics for flat fabric blank material, compliance of the supporting surface is accomplished as the load is applied by a users body when laying in the hammock. Therefore, in order to end up with a flat, or nearly flat user support surface once loaded, the sheet fabric width is necked down in the center using a smooth continuous curve toward the center of the hammock, and it widens as it approaches each end.
The shape of the side profile of the blank is relevant to the flatness and amount of compliance and final longitudinal curvature of the hammock, and the resulting support surface of the hammock upon which the user will lay. Since the support for the fabric blank is purely vertical applied by the tension of the sheet fabric blank vertically draped between the two high-tension flexible suspension load bearing members on either side, this application is similar to the suspension bridge design.
It is generally understood that a suspension bridge high tension support cable takes a shape of a catenary curve or possibly a parabolic curve when under load. These two shapes are extremely close to each other, to the point that it is difficult to visually differentiate the two. Further these shapes are known to be optimal or nearly optimal for supporting a load with an essentially equal and homogeneous load along the length of the cable. Therefore, these two curves are ideal candidate for the shape of the side profile of the hammock sheet fabric blank.
The shape of the ends of the blank are not critical to the function of this hammock, and the simplest form of a straight line is used here for example. Other variations in the head and feet end shape (flat, curved, scalloped, etc.) are also obviously possible and are incorporated into the invention described herein.
While a parabola side shape is used in the example of
A comparison of different curves is shown in
For this invention, whatever smooth circular curve is selected for the hammock side profile based on the application (general user weight, height, density distribution, etc.) the desired curve is then formed into the actual hammock by cutting out the blank to the desired hourglass like shape (100), then looping excess side material around the suspension member or machine sewing, bonding, gluing or otherwise fastening the sheet fabric blank to two side mounted high-tension flexible suspension load bearing members (101), typically a continuous length of nylon webbing or similar material. Typically, this is done by looping excess side material around the suspension member then machine sewing the sheet fabric to the webbing continuously along the side profile, and providing for an extra length of webbing at each end for either a short loop for attachment, or a long strap and then a loop for attachment, or a combination of both of these loop options on the same strap. The loop at the end of these straps is typically connected to a carabiner and then to another long extension strap to attach it to a vertical support tree or post or similar support point of the users selection. These two main construction options are shown in
In addition, the two ends of the hammock sheet fabric blank may be flat or any shape desired, and hemmed only, or reinforced in a similar way to the sides by using additional webbing and stitching or similar means, although the ends are not a high-tension load carrying seam under normal use and it is less important reinforce them from a mechanical strength properties perspective. This hem or webbing reinforcement is shown as item 116.
For a typical user that wants to adjust the hammock flatness, this invention requires an adjustable width cross brace or lateral support member at each end of the hammock, such that the high-tension suspension webbing member loops or straps are constrained to remain at a preset dimension, but also a user adjustable dimension. In the simplest form, with minimal adjustment, this can be done using two cylinders (106) like the ones shown in
In order to make the hammock smaller when packaged and transported it is desirable to make this adjustable width cross brace or lateral support member as compact, lightweight, and low cost as possible. Therefore, as a preferred embodiment, shown in
The advantage of more segments is that one end of the hammock can use a different number of these cross brace or lateral support members to change the distance of separation of the high-tension suspension members, typically webbing, and thereby the height of the user support surface, or blank. By a user removing the number of cross brace or lateral support member tubes so the overall length is shorter than the nominal flat configuration, as user can control the resulting effect of lowering that end of the hammock support surface. An example of a reconfigured shorter cross brace or lateral support member, as configured by a user based on preference, is shown in
Conversely, adding additional cross brace or lateral support member tube segments will have the effect of increasing that end of the hammocks cross brace or lateral support member width, thereby raising that end of the hammock support surface fabric blank (100). An example of a longer cross brace or lateral support member is shown in
When designing the cross brace or lateral support member tubing segments and couplers and end caps, buckling calculations must be performed on the worst-case configuration possible to assure buckling failure does not occur to the adjustable width cross brace or lateral support member when loaded by a user occupying the hammock. Limiting the minimum length of each extension segment is one way to be sure the permutations of separator lengths are calculatable, and buckling loads can be calculated, and a safe design with a margin of safety that will not buckle in all cases can be assured.
There is no minimum limit on the shortest cross brace or lateral support member length, and even a single unit may be used or none at all. The maximum number of tube segments and the corresponding cross brace or lateral support member width can be limited by providing user directions given to the users in an instruction booklet, and placing warnings on the tubes, and additionally by providing a product with a limited number of tube segments. From a practical perspective the maximum cross brace or lateral support member width is also limited by the end width of the flexible fabric blank as a maximum width.
This user adjustment capability of their laying position longitudinal curvature in the vertical plane by modifying the number of tubes installed allows a user to control their specific preference for their bodies longitudinal curvature in the vertical plane, thus allowing them to obtain the most comfortable position for relaxing or sleeping depending upon their comfort preferences.
Since there is a substantial interaction of the designed shape of the hammock fabric blank side curve, the ratio of the sheet fabric blanks center minimum width to the sheet fabric ends maximum width, and the mounting geometry and tension and user geometry and density, and the number of tube sections and their length, an empirical approach was used to determine the most general and adjustable case and the curve and width parameters were determined. The images shown in this invention disclosure use a minimum blank width of 29 inches in the center of the hammock, and a maximum width at each end of 57 inches, and use a parabolic side profile with 14 inch maximum side curve inset as disclosed in
One result of this construction is the shape of the hammock is unusual when unloaded.
Claims
1. A hammock comprising:
- a bed formed from a blank of strong flexible fabric, the blank defined by opposed ends and opposed sides, the ends and sides of the sheet of fabric coinciding with opposed ends and opposed side edges of the hammock respectively, each side of the sheet of fabric having a smoothly curved shape that is narrower in the middle between the ends, and wider at each end, and each side having a curve that can be measured as an inset dimension along an axis Y, called the lateral axis, that is parallel to the two parallel ends, and an axis X, called the longitudinal axis, that goes from the corner of one end and side of the blank to the corner of the other end and that same side of the blank, so that the side curve can be described by a function Y(X), and where the first derivative of Y(X), called dY(X) has a single point where it is zero, and where the second derivative of Y(X), called d2Y(X) is unipolar (either always positive or always negative for all X along the side curve), where the polarity of d2Y(X) is determined by the choice of direction of Y as toward or away from the hammocks other side), and where d2Y(X) is not bipolar (both positive and negative values for all X along the longitudinal axis).
2. The hammock of claim 1, wherein the connecting means comprises a loop of material formed by an excess length of the side edges.
3. The hammock of claim 2, wherein the connecting means on each side of the hammock is connected to the suspending means on each side of the hammock by routing one suspending means on each side of the hammock through the loop of material along each side of the hammock, and the connecting means may or may not be attached to the suspending means.
4. The hammock of claim 3, wherein the suspending means comprises a high-tension flexible suspension load bearing member like a strap, webbing, rope or cable, with at least one high tension loop in the suspending means located outward from each end of the hammock, to allow the high-tension flexible suspension load bearing member to be affixed to an attachment point directly at each end, or to be attached to a carabiner at each end to connect to another extension high tension suspension load bearing member like a strap, webbing, rope or cable with an end loop to attach to each ends carabiner, and a buckle located towards the other end, to allow the extension high tension suspension load bearing member to be wrapped around an elevated vertical support point and adjusted in length to controllably shorten the extension and thereby tighten the longitudinal tension of the hammock between two elevated vertical support points.
5. The hammock of claim 4, wherein it includes cross-braces proximal each end of the hammock, each cross brace capable of constraining the distance to the second suspension member on the opposing side of the hammock to a fixed dimension.
6. The hammock of claim 5, wherein the cross brace has an adjustable length capable of constraining the distance to the second suspension member on the opposing side of the hammock to an adjustable dimension.
7. The hammock of claim 6, wherein the cross brace has a hole or slot at both ends of the cross brace to allow the suspension member on one side and one end of the hammock to be routed through the hole or slot on one end of the cross-brace, and the suspension member on the opposing side and same end of the hammock to be routed through the hole or slot on the other end of the cross-brace.
8. The hammock of claim 7 whereby tensioning the suspension members on both sides of the hammock while constrained in their lateral dimension by the cross-braces, causes the fabric support surface to drape between and below the suspension members so that an occupant may rest essentially level on the hammock bed surface in an essentially flat laying position.
9. The hammock of claim 8, wherein both sides and both ends of the hammock have velcro, zippers, snaps or similar add-on accessory provisions attached either in discrete locations or intermittently along their lengths, or continuously along their lengths, to allow attaching accessories like netting, tenting, packing bags, cup or water bottle holders, and similar items.
10. A kit comprising a hammock according to claim 9, and extension suspending means for attaching and suspending the hammock between upright support structures with different separation distances.
Type: Application
Filed: Aug 27, 2018
Publication Date: Feb 27, 2020
Inventors: David Warren Parish, SR. (Castle Rock, CO), Bennett Riley Steward (Boeme, TX), Sophia Mary Parish (Castle Rock, CO)
Application Number: 16/113,001