Abstract:
A recreational structure, such as a trampoline frame, can be quickly and reliably assembled using a sleeve-joint coupling having a “T” configuration. A first arm member and an aperture that is formed in the sleeve-joint coupling are disposed in an opposite relationship. A second arm member and a third arm member are disposed in an opposite relationship with each other. The first arm member receives one end of a vertical frame member of the recreational structure, while the aperture receives one end of a vertical pole member of, for example, a safety enclosure. The second and third arm members each receive one end of a horizontal frame member of the recreational structure. The vertical pole member extends through the sleeve-joint coupling into an inner portion of the vertical frame member received by the first arm of the sleeve-joint coupling.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present patent application claims priority to U.S. Provisional Patent Application Ser. No. 60/530,054, filed Dec. 16, 2003, entitled “Sleeve-joint Coupling For Recreational Structure,” and invented by Craig Adams, and which is incorporated by reference herein. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to recreational structures. More particularly, the present invention relates to a frame arrangement for a recreational structure, such as a trampoline, that uses a sleeve-joint coupling. 
     2. Description of the Related Art 
     Recreational structures having frames, such as trampolines, are well-known. For example, a trampoline has a horizontal frame to which a rebounding surface is attached and a plurality of vertical frame members, or legs, that support the horizontal frame and rebounding surface above the ground. While the horizontal and vertical frame portions of a trampoline could be fabricated to be one unitary structure, such a unitary structure is cumbersome when the trampoline frame is transported to a place where the trampoline is used. Accordingly, trampoline frames are typically formed from a plurality of pieces that are fastened together at the time a trampoline is assembled. 
     A desirable characteristic for all trampoline frames formed from a plurality of pieces is that the various pieces are attached or joined to each other using a technique that is simple, quick to assemble and is reliable. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention provides a technique for joining structural components of a recreational structure, such as a trampoline, that is simple, quick to assemble and is reliable. 
     The advantages of the present invention are provided by a recreational structure frame system that includes a plurality of horizontal frame members, at least one vertical frame member, at least one vertical pole member, and at least one sleeve-joint coupling. Each horizontal frame member has two ends. Similarly, each vertical frame member has two ends, and each vertical pole member has two ends. In one exemplary embodiment, at least one sleeve-joint coupling has first, second and third arm members arranged to substantially form a T configuration and an aperture that is formed in the sleeve-joint coupling. That is, the first arm member and the aperture are disposed in an opposite relationship with respect to each other, and the second arm member and the third arm member are disposed in an opposite relationship with each other. In another exemplary embodiment, at least one sleeve-joint coupling includes a side sleeve member having the aperture. The first arm member receives one end of a vertical frame member. The aperture receives one end of a vertical pole member. The second and third arm members each receive one end of a horizontal frame member. The vertical pole member received by the aperture extends through the sleeve-joint coupling into an inner portion of the vertical frame member received by the first arm of the sleeve-joint coupling. 
     The vertical pole member can be part of, for example, a safety enclosure, in which case the safety enclosure can include a plurality of vertical pole members, such that each vertical pole member is received into the aperture of a sleeve-joint coupling. A plurality of horizontal support members can be coupled to two adjacent vertical pole members, thereby forming the safety enclosure. In one exemplary embodiment, the vertical pole member is configured to substantially form an arch. 
     One exemplary embodiment of a sleeve-joint coupling according to the present invention includes a fourth arm member, in which case the aperture is disposed at an end of the fourth arm member. A tension member can be coupled between adjacent sleeve-joint couplings that applies a force to the adjacent sleeve-joint couplings and forces the adjacent sleeve-joint couplings toward each other. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention is illustrated by way of example and not by limitation in the accompanying figures in which like reference numerals indicate similar elements and in which: 
         FIG. 1  depicts a perspective view of an exemplary trampoline having an exemplary safety enclosure; 
         FIGS. 2A-2C  respectively show a side view, a top view and an end view of the first exemplary embodiment of a sleeve joint coupling for a trampoline frame according to the present invention; 
         FIG. 2D  shows a perspective view of the first exemplary embodiment of a sleeve joint coupling according to the present invention; 
         FIG. 3  shows details of a first exemplary embodiment of sleeve-joint coupling according to the present invention; 
         FIGS. 4A-4C  respectively show a side view, a top view and an end view of a second exemplary embodiment of a sleeve-joint coupling for a trampoline frame according to the present invention; 
         FIGS. 5A-5C  respectively show a side view, a top view and an end view of a third exemplary embodiment of a sleeve-joint coupling for a trampoline frame according to the present invention; 
         FIGS. 6A-6C  respectively show a side view, a top view and an end view of a fourth exemplary embodiment of a sleeve-joint coupling for a trampoline frame according to the present invention; 
         FIGS. 7A and 7B  respectively show a side view and a top view of a fifth exemplary embodiment of a sleeve-joint coupling for a trampoline frame according to the present invention; 
         FIGS. 8A-8C  respectively show a side view, a top view and an end view of a sixth exemplary embodiment of a sleeve joint coupling for a trampoline frame according to the present invention; 
         FIG. 9  depicts a top cutaway view of the first exemplary embodiment of a sleeve-joint coupling according to the present invention; and. 
         FIG. 10  depicts a perspective view of an exemplary trampoline having an exemplary alternative embodiment of a safety enclosure. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  depicts a perspective view of an exemplary trampoline  100  having an exemplary safety enclosure  101 . Trampoline  100  includes a rebounding surface  102  and a frame structure having vertical frame members  103  and a circular frame that can be formed from a plurality of circular frame members  104 . Vertical frame members  103  and circular frame members  104  are typically made from hollow metal tubing having sufficient strength to bear the stresses and loads that are associated with trampolines. Safety enclosure  101  includes a frame structure having vertical pole members  105  and horizontal support members  106 . A horizontal support member  106  is connected between adjacent vertical pole members in a substantially inflexible manner. A structural member that is suitable for both vertical pole members  105  and horizontal support members  106  is disclosed by U.S. Pat. No. 6,450,187 B1 to Lin et al., which is incorporated by reference herein. 
     Complete details of trampoline  100  and safety enclosure  101  are not shown in  FIG. 1  for simplicity. For example, safety enclosure includes a mesh- or netting-type of material that extends between adjacent vertical pole members  105  and between horizontal frame members  106  and circular frame member  104  that together with circular frame  104 , vertical pole members  105  and horizontal support members  106  operate as a fence around rebounding surface  102  in order to keep a user on trampoline  100  and reduce the risk of injury to the user. 
     According to the present invention, vertical pole members  105  of safety enclosure  101  attach to the frame structure of trampoline  100  using a plurality of sleeve-joint couplings, of which one is indicated at A in  FIG. 1 .  FIGS. 2A-2D  and  FIG. 3  show details of a first exemplary embodiment of a sleeve-joint coupling according to the present invention. In particular,  FIGS. 2A-2C  respectively show a side view, a top view and an end view of the first exemplary embodiment of a sleeve-joint coupling  200  for a trampoline frame according to the present invention.  FIG. 2D  shows a perspective view of sleeve-joint coupling  200 . Sleeve joint coupling  200  is generally shaped as a “T” and includes three arm members  201 - 203 , each having a generally square cross-sectional shape. Each arm member  201 - 203  receives a trampoline frame member (not shown in  FIGS. 2A-2C ) of similar cross-sectional shape into an opening  204  ( FIGS. 2C and 2D ). Sleeve joint coupling  200  includes an opening  205 , shown in  FIG. 2B , that receives a safety enclosure vertical pole member (not shown in  FIGS. 2A-2C ) having a generally square cross-sectional member. 
       FIG. 3  depicts View A, shown in  FIG. 1 , in greater detail. In  FIG. 3 , sleeve-joint coupling  200  couples circular frame member  104 A to circular frame member  104 B and to vertical frame member  103 . Circular frame members  104 A and  104 B are secured to sleeve-joint coupling  200  using, for example, pins  301  and cotter rings  302  (not shown in  FIGS. 2A-2D ). Alternatively, circular frame members  104 A and  104 B can be secured to sleeve-joint coupling  200  using sheet metal screws, and/or bolts and nuts. As yet another alternative, the inner surface of each arm member of sleeve-joint coupling can be threaded to engage complementary threading on each end of a circular frame member  104  and on one end of a vertical frame member  103 . Additionally, a threaded connection between sleeve-joint coupling  200  and a frame member can be secured using a pin and cotter ring arrangement, a sheet metal screw and/or a bolt and nut. 
     Vertical pole member  105  of safety enclosure  101  is inserted into opening  205  ( FIGS. 3B and 3D ) and extends through sleeve-joint coupling  200  into vertical frame member  103  a distance that is sufficient to distribute any shearing and/or torquing forces that may be imparted to vertical pole member  105  along the inside of vertical frame member  103  so that vertical frame member  103  does not fail. Vertical pole member  105  can be secured in vertical frame member  103  using, for example, a pin  301  and a cotter ring (not shown). Alternatively, vertical pole member  105  is secured in vertical frame member  103  using a sheet metal screw and/or a bolt and nut. 
       FIGS. 4A-4C  respectively show a side view, a top view and an end view of a second exemplary embodiment of a sleeve-joint coupling  400  for a trampoline frame according to the present invention. Sleeve-joint coupling  400  is generally shaped as a “T” and includes three arm members  401 - 403 , each having a generally round cross-sectional shape. Each arm member  401 - 403  receives a trampoline frame member (not shown in  FIGS. 4A-4C ) of similar cross-sectional shape into an opening  404  ( FIG. 4C ). Sleeve-joint coupling  400  includes an opening  405 , shown in  FIG. 4B , that receives a safety enclosure vertical pole member (not shown in  FIGS. 4A-4C ) having a generally round cross-sectional member. 
       FIGS. 5A-5C  respectively show a side view, a top view and an end view of a third exemplary embodiment of a sleeve-joint coupling  500  for a trampoline frame according to the present invention. Sleeve-joint coupling  500  is generally shaped as a “T” and includes three arm members  501 - 503 , each having a generally oval cross-sectional shape. Each arm member  501 - 503  receives a trampoline frame member (not shown in  FIGS. 5A-5C ) of similar cross-sectional shape into an opening  504  ( FIG. 5C ). Sleeve-joint coupling  500  includes an opening  505 , shown in  FIG. 5B , that receives a safety enclosure vertical pole member (not shown in  FIGS. 5A-5C ) having a generally oval cross-sectional member. 
       FIGS. 6A-6C  respectively show a side view, a top view and an end view of a fourth exemplary embodiment of a sleeve-joint coupling  600  for a trampoline frame according to the present invention. Sleeve-joint coupling  600  is generally shaped as a “T” and includes three arm members  601 - 603 , each having a generally triangular cross-sectional shape. Each arm member  601 - 603  receives a trampoline frame member (not shown in  FIGS. 6A-6C ) of similar cross-sectional shape into an opening  604  ( FIG. 6C ). Sleeve-joint coupling  600  includes an opening  605 , shown in  FIG. 6B , that receives a safety enclosure vertical pole member (not shown in  FIGS. 6A-6C ) having a generally triangular cross-sectional member. 
       FIGS. 7A and 7B  respectively show a side view and a top view of a fifth exemplary embodiment of a sleeve-joint coupling  700  for a trampoline frame according to the present invention. Sleeve-joint coupling  700  is generally shaped as an “X” or a “+” and includes four arm members  701 - 704 , each having a generally square cross-sectional shape. Each arm member  701 - 704  receives a trampoline frame member (not shown in  FIGS. 7A and 7B ) of similar cross-sectional shape into an opening  705 , of which only one opening  705  is shown ( FIG. 7B ). Each opening  705  receives a safety enclosure vertical frame member  103 , a circular frame member  104  or a vertical pole member  105  (none of which are shown in  FIGS. 7A and 7B ) having a generally square cross-sectional member. It should be understood that sleeve-joint coupling  700  can have an alternative cross-sectional shape, such as any of the exemplary cross-sectional shapes described herein, and a mating vertical frame member, circular frame member and vertical pole member would have a corresponding cross-sectional shape. 
       FIGS. 8A-8C  respectively show a side view, a top view and an end view of a sixth exemplary embodiment of a sleeve-joint coupling  800  for a trampoline frame according to the present invention. Sleeve-joint coupling  800  is generally shaped as a “T” and includes three arm members  801 - 803 , each having a generally round cross-sectional shape. Sleeve-joint coupling  800  also includes a side-sleeve member  804  having an aperture  805 , configured as a blind hole, that receives a safety enclosure vertical pole member (not shown in  FIGS. 8A-8C ) having a generally round cross-sectional member. Side-sleeve member  804  has sufficient length and strength to allow a safety enclosure vertical pole to extend into side sleeve member  804  so that the vertical pole would not come out during use. Each arm member  801 - 803  receives a trampoline frame member (also not shown in  FIGS. 8A-8C ) of similar cross-sectional shape into an opening  806  ( FIG. 8C ). In an alternative embodiment, aperture  805  could be configured to allow a safety enclosure vertical pole to extend through the length of the side-sleeve member  804  to the ground or to another device that fastens the vertical pole to the corresponding frame member  103 . In yet another alternative embodiment, side sleeve member  804  could have a slot that extends from at least one end of side-sleeve member  804  toward the other end of side-sleeve member  804  such that aperture  805  is not completely enclosed. It should be understood that the slot could extend part of or the entire length of side-sleeve member  804 . 
       FIG. 9  depicts a top cutaway view of the first exemplary embodiment of a sleeve-joint coupling  200  according to the present invention. Two circular frame members  104 A and  104 B are shown in  FIG. 9  respectively engaging arm members  201  and  202  of sleeve-joint coupling  200 . A vertical pole member  105  of a safety enclosure is also shown. A tension member  901 , such as a strap of webbing, a wire or a cable, is shown threaded through circular frame members  104 A and  104 B and sleeve-joint coupling  200 , in addition the other circular frame members and sleeve-joint coupling forming a trampoline frame. Tension member  901  is fastened in a well-known manner to a hook assembly  902  that engages a loop  903  of a buckle assembly  904  that is accessible through a hole (not shown) in circular frame member  104 B. Buckle assembly  904  has two positions; an open position that allows hook assembly  902  and loop  903  to be conveniently engaged, and a closed assembly that places tension member  901  under tension. When tension member  901  is under tension, each sleeve-joint coupling  200  that tension member  901  passes through is urged toward the center of the trampoline frame structure, thereby making the joints of frame structure even more reliable. Alternatively, a plurality of tension members can be used to form a line of continuous tension around a trampoline frame instead of a single tension member, as depicted in  FIG. 9 . As yet another alternative, tension member  901  could be attached to the outside of sleeve-joint coupling  200 , such as through a loop fastened to the outside of sleeve-joint coupling  200 . Still another alternative provides that a turn-buckle arrangement is used for placing tension on tension member  901 . 
     While exemplary trampoline  100  shown in  FIG. 1  is depicted as being round, it should be understood that the present invention could be used with a trampoline and safety enclosure having a different shape, such as square, rectangular or oval. Additionally, the sleeve-joint coupling of the present invention can be made from any suitable material that has sufficient strength to bear the loads and stresses that are associated with trampolines, such as metals and plastics. Further, while the sleeve-joint coupling of the present invention has been described in terms of vertical frame members and circular frame members fitting into the sleeve-joint coupling, it should be understood that the sleeve-joint coupling of the present invention can be configured so that one or all of the arm members of the sleeve-joint coupling fit into vertical frame members and circular frame members of the trampoline frame. Further still, while the sleeve-joint coupling of the present invention has been described as having several exemplary cross-sectional shapes, it should be understood that a sleeve-joint coupling according to the present invention could have any cross-sectional shape or have arm members having different cross-sectional shapes. As yet another alternative, the sleeve-joint coupling of the present invention could be formed to be part of a vertical frame member. As still another alternative, the sleeve-joint coupling of the present invention could be configured to substantially form a “T”. 
     While the vertical pole members  105  of safety enclosure  101  has been described as extending into vertical frame members  103 , it should be understood that at least one or more vertical pole member  105  of safety enclosure  101  could extend to the ground along the outside of a vertical frame member  103 , in which case such a vertical pole member would be attached to the corresponding vertical frame member at a minimum of two places, such as by using a sleeve-joint coupling similar to that shown in  FIGS. 8A-8C  and, for example, a tie-wrap device near the bottom of a vertical frame member  103 . 
     As yet another alternative embodiment, a safety enclosure vertical pole member  105  could be configured to form an arch ( 105   a  of trampoline  100   a  in  FIG. 10 ), or an arc shape, between two frame members  103 . The two frame members  103  could be adjacent or could be separated by one or more other frame members  103 . A horizontal support member would then be connected between adjacent peaks of an arch in a substantially inflexible manner. 
     Although the foregoing invention has been described in some detail for purposes of clarity of understanding, it will be apparent that certain changes and modifications may be practiced that are within the scope of the appended claims. Accordingly, the present embodiments are to be considered as illustrative and not restrictive, and the invention is not to be limited to the details given herein, but may be modified within the scope and equivalents of the appended claims.