Abstract:
Springs or other elastic connectors used to support a bed within the frame of a trampoline or the like are attached using methods that permit the adjustment and/or a systematic variation of the tension (or the travel distance required to reach limit of elasticity) between adjacent (or sets of adjacent) springs. These spring attachment methods adjust the energy absorption capacity of the tramnpoline bed, as well as increase the time it takes a given trampoline to absorb a given amount of energy, increasing the shock absorption time and thereby reducing the likelihood of an injury.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     The present application claims priority to the U.S. provisional application for a “Trampoline with adjustable spring tension” filed on Nov. 19, 2004, having serial number 60/629,652, which is incorporated herein by reference. 
     
    
     BACKGROUND OF INVENTION  
       [0002]     The present invention relates to improvements in trampoline, and in particular, the present invention concerns jumping surfaces used with trampolines to protect trampoline users from injury, and to provide new uses for trampolines.  
         [0003]     In the past, trampolines have been used for a variety of athletic and recreational purposes. However, thousands of injuries have resulted when persons jumping on a trampoline have landed on the rebounding surface while in an awkward or incorrect body position. These “on-bed” injuries, according to some medical studies, represent the majority of trapoline-related emergency room visits. The U.S. Consumer Products Safety Commission (CPSC) reports that in 1999 approximately 110,000 people were treated in emergency rooms for trampoline related injuries. Even though this number is half that of play structure/swing set injuries, some in the medical community have called for a ban on the sale of backyard trampolines. The CPSC and the AAOS have taken a more responsible and measured approach to problem. Recognizing that other outdoor activities that are more injurious, like bicycling, would fill the void left by backyard trampoline play, these organizations have instead called for safety improvements to help reduce the large number of trampoline injuries.  
         [0004]     One approach to reducing trampoline injuries has been to form a wall around the perimeter of a trampoline bed so that when a jumper lands too near the edge, the wall prevents the jumper from falling off. Examples are shown in U.S. Pat. Nos. 5,399,132 and 6,053,845. However, these devices do not directly address injuries that result when users impact the rebounding surface incorrectly or while in an awkward position. A second approach, the use of a harness (worn by the jumper) suspended by elastic cords above the rebounding surface, is an effective way to reduce on-bed, or rebound surface impact injuries. However, such harnesses are designed for safely teaching users advanced acrobatics on high-performance competition trampolines by trained professionals, making them largely inappropriate for low-performance backyard trampolines that are used almost entirely for basic jumping activities and not for advanced acrobatics.  
         [0005]     All things being equal, a bed with less tension is more forgiving when a jumper first contacts its surface, it absorbs the impact more slowly and will thus reduce the severity and quantity of on-bed injuries. Nevertheless, injuries suffered during an impact with the rebounding surface are still occurring in large numbers on backyard trampoline beds even though these beds are designed to be less responsive and to have less initial surface tension than gymnastic grade, competition trampoline beds. Reducing bed-impact injuries, especially those that occur on backyard trampolines, was the purpose of the present invention, though the art can be used with all trampolines.  
         [0006]     Low performance backyard trampolines are used very differently than high performance trampolines used by skilled competitors for training and competition. For instance, many on-bed backyard trampoline injuries occur when multiple jumpers are using the trampoline at the same time as reported in the NEISS data compiled by the CPSC. Because children enjoy playing together most families allow more than one child to jump at the same time even though this practice is strongly discouraged by trampoline manufacturers, the CPSC, and others experts. Competition trampolines are used almost exclusively in disciplined environments for the structured teaching of specific skills. In contrast, backyard trampolines are largely used for fun, unstructured, imaginative play activities that are relished by kids and recommended by child development experts who understand that daily physical activity significantly enhances learning ability and that kids need activities to counterbalance today&#39;s over-structured and sedentary lifestyles.  
         [0007]     Unfortunately, these unstructured trampoline activities generate numerous on-bed injuries when jumpers land on the rebounding surface in an awkward body position or when a jumper lands on a trampoline bed that has been preloaded with the energy from other jumper impacts.  
         [0008]     There thus remains a need to significantly reduce the quantity and severity of on-bed injuries that result from such playful activities. Prior trampolines used a rebounding matt that is attached to a frame by a plurality of springs that have a fixed tension. The fixed tension is not suitable for all users as they very in body weight, age and strength.  
         [0009]     It is therefore a first object of the present invention to provide an improved trampoline with adjustable springs.  
       SUMMARY OF INVENTION  
       [0010]     In the present invention, the first object is achieved by proving a trampoline wherein the springs attach to the frame via an intermediate member whose length can be varied to modify the spring tension.  
         [0011]     The above and other objects, effects, features, and advantages of the present invention will become more apparent from the following description of the embodiments thereof taken in conjunction with the accompanying drawings.  
     
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0012]      FIG. 1  is a plan view showing the trampoline rebounding matt and attachment to the trampoline frame.  
         [0013]      FIG. 2  is a perspective view of a trampoline rebounding matt, frame and springs showing where the spring tension is adjusted along the edge of the frame.  
         [0014]      FIG. 3  is a cross sectional elevation showing the rotating pin and related structure as disposed within the bore trampoline frame.  
         [0015]      FIG. 4  is a cross sectional elevation showing the detailed construction of a first embodiment of the pin in  FIG. 3 .  
         [0016]      FIG. 5  is a cross sectional elevation showing the detailed construction of a second embodiment of the pin in  FIG. 3 .  
         [0017]      FIG. 6  is an elevation of the pin of  FIG. 5  from a viewpoint outside the trampoline frame, corresponding to section A-A in  FIG. 5 .  
         [0018]      FIG. 7  is an external plan view of an alternative embodiment of the pin.  
         [0019]      FIG. 8  is a cross-sectional elevation of the pin of  FIG. 7 .  
         [0020]     It should be understood that  FIG. 1-8  are not intended to be drawn to the same relative or absolute scale, but rather each figure is drawn at a scale to properly display and describe the interrelationship between the elements thereof It being understood that one of ordinary skill in the art, can readily make adjustments thereto depending on the same and scale of the desired trampoline.  
     
    
     DETAILED DESCRIPTION  
       [0021]     Referring to  FIGS. 1 through 8 , wherein like reference numerals refer to like components in the various views, there is illustrated therein a new and improved trampoline with adjustable springs, generally denominated 100 herein.  
         [0022]     Every potential player on a trampoline has a different strength-to-weight ratio. Thus, the ability to adjust or tune the system rebounding response for each player benefits their health and safety. In the instant invention the rebounding response it adjusted by varying the spring tension as shown and described below.  
         [0023]     The basic operation and configuration of attaching a trampoline mat to a trampoline frame are taught in United States patents and Published application Ser. No. 6,261,207 (for a Trampoline or the like with enclosure); 6,053,845 (for a Trampoline or the like with enclosure); U.S. patent application Ser. No. 20040121883 (for a Trampoline system); U.S. patent application Ser. No. 2003/0104905 A 1  for a Trampoline system with plural beds; U.S. patent application Ser. No. 2003/0036460 A 1  (for a Trampoline system with adjustable spring elements) and U.S, patent application Ser. No. 2002/0137598 A 1  (for a Trampoline or the like with enclosure), all of which are incorporated herein by reference.  
         [0024]     In a preferred embodiment of the invention the tension in the adjacent or nearby spring alternate as taught in U.S. patent application Ser. No. 2003/0036460 A 1  (for a Trampoline system with adjustable spring elements) such that the springs engage in “stages,” instead of all a once, making for a softer initial impact. The instant invention provides for the tension of each spring to be individually adjusted providing a functionality that allows users to customize the bounce by tightening or loosening the spring connections at the external side of the spring frame. This inventive system gives the user control over the feel and performance during rebounding on the trampoline.  
         [0025]     Accordingly,  FIG. 1  illustrates in a perspective view a portion of a trampoline system that comprises a circular frame  12  held above the ground by a plurality of laterally downward extending legs  60 . The rebounding matt or bed  14  is held in tension and suspected within frame  12  by coupling to the proximal ends of a plurality of spring, which are in turn coupled to the inside of the circular frame  12  at their distal ends. Coupling means a direct or indirect mechanical connection of two members.  
         [0026]     As shown in more detail in the plan view of  FIG. 2 , springs  10  and  10 ′ attach to the rebounding matt  14  at a plurality of locations around the perimeter via an intermediate plate  40 . Intermediate plate  40  has central hole  41  and aperture  45  and  46  on opposite sides of the central hole  41  that receive fabric loops  51  and  52  sewn, stitched or otherwise adhered to the rebounding matt  14  at  54  and  53 . The hooks like ends of one or more springs are inserted into central hole  41  to couple the springs  10  to the rebounding bed  14 .  
         [0027]     Referring to  FIG. 3  it can be seen that the distal ends of the springs  10  and  10 ′ are coupled to the circular frame  12  via pins  20  and  20 ′ respectively. Each of the pins  20  and  20 ′ have at least one hole or bore  21  for receiving the hook like distal end of the spring  10 . The pins  20  extend through a bore  25  in the circular frame  12 . Each pin has a head  28  that extends beyond the diameter of bore  25  coupling the pin  20  to the frame  12 , fixing the lateral position of pin  20  with respect to frame  12 .  
         [0028]     In the preferred embodiment shown in  FIG. 3 , each pin  20  has a plurality  24  of holes  21 ,  22  and  23  for receiving the hook like distal end of spring  10 . By attaching the distal end of each spring  10  to one of the plurality of holes  24 , the spring tension is tunable between two, and preferably three or more discrete levels. As shown in  FIG. 1  the trampoline frame  12  is supported above the ground by a plurality of legs  60 .  
         [0029]     It is generally desirable to locate and space holes  24  taking into account the stiffness of the springs  10  to be used, such that the middle setting, hole  22 , is the optimal setting for users of average height and weight. Thus, a firmer bounce will be obtained by connecting all springs to the holes  23  most proximal to the trampoline frame  12 . Conversely, a softer bounce will be obtained by connecting all springs to the holes  21  most distal from the trampoline frame  12   
         [0030]     Adjusting the position of the end of springs in a hole selected from plurality  24  requires the user to pull back a protective pad (not shown) to expose the top ring  12  of the trampoline frame and the periphery of rebounding matt  14 . The user then replaces the protective pad after selecting a different hole from plurality  24  after tightening or loosening spring connectors before use.  
         [0031]     However, in the more preferred embodiments of  FIG. 4-6  the spring tension can be adjusted while the pad is left in place. In such embodiments, the tension in each spring  10  is optionally varied continuously by adjusting the effective length of pin  20  while it is seated in bore  25 .  FIG. 4-6  illustrate further details of such pin and related mechanisms that permit the continuous adjustment of rebounding characteristics of mat  14 . The adjustment range of each pin is preferably at least separation between holes in plurality  24 .  
         [0032]     In  FIG. 4 , the pin mechanism  20  is again disposed within a bore  25  through frame  12 . However, pin  20  has in effect two portions  26  and  27  that can be translated relative to each other to shorten or length the pin, that is the distance between head  28  at the distal end of portion  26  and hole  21 , disposed toward the proximal end of portion  27 . Portion  26  includes head  28 , whereas portion  27  includes the plurality of holes  24 . Portion  27  has an internal bore  27   a  with internal threads  27   b.  The shaft of portion  26  opposite head  28  has exterior threads  26   b  that rotationally engage with threads  27   b  of portion  27 . Head  28  includes a tool receiver opening  29  (for example a slot for a screw driver or hexagonal hole for an allen wrench) such that the corresponding tool can be used to rotate portion  26  while portion  27  is prevented from rotation by the resistance of spring  10 .  
         [0033]      FIG. 5  illustrates an alternative embodiment of the invention, shown in cross-sectional elevation, in which a spin lock mechanism  30  prevents the rotation of pin  20  by coupling the head  28  thereof to the frame  12 . The spin lock mechanism  30  is a means for preventing the gradually loosening or movement of the threaded portion of the pin  20  from vibration. The spin lock mechanism  30  comprises relatively flat plate  38  having an inverted “L” shape connected by the narrower edge to the end of circular shaft  35 . Note that a portion  38   a  of flat plate  38  is connected to the upper portion of circular shaft  35 . The cooperative engagement of the flat plate  38  within slot  29  of head  28  is also illustrated in  FIG. 6 , which is an orthogonal elevational taken at section line A-A in  FIG. 5 . A spring  33  is attached to the other end of the circular shaft  35 , both of which are in turn disposed with a second mating bore  34  formed within frame  12 . The opposite end of spring  30 , which is proximal to the interior of the trampoline, is fixed outside of bore  34  by end washer  36 . Thus, spring  33  urges flat plate  38  inward toward frame  12  as it engages the slot  29  in head  28 . It is also desirable that the upper portion  38   a  of flat plate  38  engage the vertical slot  12   a  in frame  12 . Having flat plate  38  engage both slot  29  and slot  12   a  securely fixes the relative position of head  28  with respect to frame  12 , thus preventing the unwanted rotation of pin  20  (and in particular portion  26  with respect to portion  27 ) However, when the user wishes to adjust the tension of spring  10 , flat head  38  is readily disengaged from slots  29  and  12   a  by pulling it forward and rotating it 90 degrees. This alternative position for flat plate  38  (shown in dashed lines in  FIG. 6  and labeled  38 ′) clears the front of pin head  38  for receiving a screwdriver tip in slot  29  for rotating portion  26 .  
         [0034]     It will be apparent to one of ordinary skill in the art that alternative cooperative structures in frame  12  and pin  20  may be deployed to enable the lateral translation of holes in plurality  24  to vary the tension in spring  10  continuously. For example, pin  20  need not be formed of two portions, but may be externally threaded to engage female threads in bore  25 . As it is desirable that the portion of pin  20  with the plurality of holes  24  not rotate about the axis of bore  25  when the head  28  is rotated to translate pin  20  with bore  25 . One embodiment of such a pin  20  is illustrated  FIG. 7  and  8 .  
         [0035]     Accordingly, pin  20  has a freely rotating or bearing coupling  70  disposed between the portion  77  that includes the proximal end with holes  24  and the portion  76  that includes the distal end having head  28  and slot  29 . Portion  76  has external thread  72  for engage a threaded coupling, insert or bore and the like that may be forming in or associated with frame  12 . It will also be apparent that alternative methods of locking the head  28  of pin  20  are possible.  
         [0036]     Further, referring back to  FIG. 2 , it should be appreciated that it is not essential to couple a pair of spring  10  and  10 ′ to a common connection on the perimeter of mat  14  using intermediate plate  40 . In alternative embodiments, each of the adjustable springs  10  may be connected or coupled to a discrete position on the perimeter of the mat  14  with a common connection of an adjacent spring. However, it should be appreciated that the embodiment shown and described with respect to  FIG. 2  is preferred.  
         [0037]     While the invention has been described in connection with a preferred embodiment, it is not intended to limit the scope of the invention to the particular form set forth, but on the contrary, it is intended to cover such alternatives, modifications, and equivalents as may be within the spirit and scope of the invention as defined by the appended claims.