Patent Publication Number: US-10787835-B2

Title: Play structure tube connector and system

Description:
BACKGROUND 
     1. Field of the Invention 
     The invention is in the area of play structures and the connectors used therein. 
     2. Description of the Related Art 
     Play structures and connectors used to assemble such structures are known in the art, as discussed below. However, the prior art does not disclose or suggest the advantageous features of the present invention, as discussed below. 
     U.S. Pat. Nos. 4,352,255 and 5,318,470, to Warehime and Denny respectively, disclose modular construction sets with tubes that are assembled together using various connectors. However, the connectors in these patents lack the physical structure of the inventive connector, including the flexing arms that lock into the tube. While the Warehime patent does show a slot in the tube, the slot does not engage with any element on the connector. Instead, it merely helps the tube end expand as the connector is inserted—i.e., it helps to maintain a good friction fit between the tube and the connector. 
     U.S. Pat. Nos. 8,708,765 and 9,283,491, both to Pope-Gusev, disclose various tube connectors. However, in U.S. Pat. No. 8,708,765, the connectors are garden-variety, friction fit connectors that differ significantly from the invention. In U.S. Pat. No. 9,283,491, the connectors are more complex, but still lack flexing arms which lock into apertures in the tube as in the invention. 
     U.S. Pat. No. 5,049,105 to Glickman discloses a hub connector for tubes in a toy construction set. In this connector, the male member flexes as it goes into the tube, and then locks against the internal structure of the tube. This connector has key differences versus the invention: first, the flexing here occurs at the leading edge of the male member, and the two sides of the male member are fixed toward the hub/center part of the connector. This is the exact opposite of the inventive connector&#39;s flexing structure, wherein the leading edge of the flexing tabs are fixed and the flexing ends of the tabs are toward the hub/center part of the connector. In other words, in the invention the tabs flex at the trailing edge and not the leading edge, as the tube is inserted over the male member. Moreover, in this patent the flexing elements do not lock into holes or apertures in the tube, as in the invention. Further, while the center of this patent&#39;s hub has a circular opening for a tube, the structure around the circular opening is very different from the structure in the inventive connector. 
     U.S. Pat. Nos. 5,199,919 and 5,350,331, also to Glickman, disclose construction toy systems wherein tubes of various lengths are used with connectors to build a structure. The connector in these systems has flexing arms with protrusions that lock into a circular groove on the tube, but its flexing arms lock onto the outside of the tube and not the inside as in the invention. In addition, as with the other Glickman patent discussed above, the flexing here occurs at the leading edge of the connector, and the two sides of the connector are fixed toward the hub/center part—which is the exact opposite of the inventive connector&#39;s flexing structure. 
     U.S. Pat. No. 3,648,404 to Ogsbury discloses a connector used in a toy building set. This connector has a radial, ball-shaped male member that is slotted, so the sides of the ball can flex toward each other when the male member is inserted into the tube. However, the radial member merely has a friction fit with the tube, and does not lock into holes or apertures in the tube as in the invention. And again, the flexing here occurs at the leading edge of the connector, and the two sides of the connector are fixed toward the hub/center part—which is the exact opposite of the inventive connector&#39;s flexing orientation. 
     U.S. Pat. No. 4,078,328 to Rayment discloses a connector similar to that in the Ogsbury patent discussed above, except that the base of the ball-shaped male member has a shoulder which engages the inside of the tube to restrict pivotal movement of the tube. Also, the end of the tube can have a slot therein, and the slot in the tube engages the base of the ball-shaped male member to lock the tube into a perpendicular orientation with the connector rather than a straight-on orientation. However, neither the shoulder engagement nor the slot engagement involves a flexing arm that locks into the tube as in the invention. 
     U.S. Pat. No. 3,469,339 to Thomas discloses interconnecting tubes, and the connectors have flexing arms that lock into apertures in the tubes. However, the flexing here occurs at the leading edge of the connector, and the two sides of the connector are fixed at the trailing edge. This is the exact opposite of the inventive connector&#39;s flexing structure, wherein the leading edge of the flexing tabs are fixed and the flexing ends of the tabs are at the trailing edge. Moreover, while the center of this patent&#39;s connector has a circular opening for a tube, the structure around the circular opening is different from the structure in the inventive connector. 
     U.S. Pat. No. 7,419,325 to Rantrua discloses a tube assembling device. While the connectors in this patent have flexing arms, those flexing arms do not lock into apertures in the tubes as in the inventive connector. As with the other patents discussed above, the flexing orientation here is also different than in the inventive connector, and other aspects of the physical structure differ as well. 
     SUMMARY OF THE INVENTION 
     The invention is a tube connector for a play structure, and a play structure system that uses such tube connectors to connect a plurality of tubes together. The tube connector has a center portion and at least one projecting member extending from the center portion. To construct a play structure, tubes are fitted over the projecting members in the tube connectors. Flexing tabs on the projecting members, which are fixed at the end of the projecting member and extend back toward the center portion, lock into openings in the tubes to secure the tubes to the projecting members and connect the tubes together into a play structure. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a tube connector of the invention. 
         FIG. 2  is a top view of the tube connector shown in  FIG. 1 . 
         FIG. 3  is a perspective view of a tube of the invention. 
         FIG. 4  is a top view of the tube in position for placement over the projecting member. 
         FIG. 5  is a top view of the tube fully pushed over the projecting member, before the tube openings are engaged with the flexing tab buttons. 
         FIG. 6  is a top view of the tube fully locked in place on the projecting member, wherein the tube openings are engaged with the flexing tab buttons. 
         FIG. 7  is a top view of the tube in position for “straight-on” placement over the projecting member, wherein the tube openings are pre-aligned with the flexing tab buttons. 
         FIG. 8  is a perspective view of the tube connector shown in  FIG. 1 , with a tube inserted through the center opening in the tube connector. 
         FIG. 9  is a perspective view of the tube connector shown in  FIG. 1 , with a tube inserted into the center opening of the tube connector and the tube openings engaged with the tube connector center buttons. 
         FIG. 10  is a perspective view of a second tube connector embodiment of the invention. 
         FIG. 11  is a top view of a second tube connector embodiment of the invention. 
         FIG. 12  is a perspective view of a third tube connector embodiment of the invention. 
         FIG. 13  is a top view of a third tube connector embodiment of the invention. 
         FIG. 14  is a perspective view of a fourth tube connector embodiment of the invention. 
         FIG. 15  is a top view of a fourth tube connector embodiment of the invention. 
         FIG. 16  is a perspective view of a fifth tube connector embodiment of the invention. 
         FIG. 17  is a top view of a fifth tube connector embodiment of the invention. 
         FIG. 18  is a perspective view of a sixth tube connector embodiment of the invention. 
         FIG. 19  is a top view of a sixth tube connector embodiment of the invention. 
         FIG. 20  is a perspective view of a seventh tube connector embodiment of the invention. 
         FIG. 21  is a top view of a seventh tube connector embodiment of the invention. 
         FIG. 22  is a perspective view of an eighth tube connector embodiment of the invention. 
         FIG. 23  is a top view of an eighth tube connector embodiment of the invention. 
         FIG. 24  is a perspective view of a ninth tube connector embodiment of the invention. 
         FIG. 25  is a top view of a ninth tube connector embodiment of the invention. 
         FIG. 26  is a perspective view of a tenth tube connector embodiment of the invention. 
         FIG. 27  is a top view of a tenth tube connector embodiment of the invention. 
         FIG. 28  is a perspective view of an eleventh tube connector embodiment of the invention. 
         FIG. 29  is a top view of an eleventh tube connector embodiment of the invention. 
         FIG. 30  is a perspective view of a twelfth tube connector embodiment of the invention. 
         FIG. 31  is a top view of a twelfth tube connector embodiment of the invention. 
         FIG. 32  is a perspective view of a thirteenth tube connector embodiment of the invention. 
         FIG. 33  is a top view of a thirteenth tube connector embodiment of the invention. 
         FIG. 34  is a perspective view of a fourteenth tube connector embodiment of the invention. 
         FIG. 35  is a top view of a fourteenth tube connector embodiment of the invention. 
         FIG. 36  is a perspective view of a fifteenth tube connector embodiment of the invention. 
         FIG. 37  is a top view of a fifteenth tube connector embodiment of the invention. 
         FIG. 38  is a perspective view of a play structure assembled using various tube connectors and tubes of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The following provides a list of the reference characters used in the drawings:
           10 . Tube connector     11 . Center portion     12 . Projecting member     13 . Center opening     14 . Center flexing member     15 . Center button     16 . Knurl     17 . Tip     18 . Bevel     19 . Flexing tab     20 . Tab button     21 . Tab stop     22 . Abutment     23 . Center tab     24 . Open space     25 . Tube     26 . Tube opening     27 . Second tube connector     28 . Third tube connector     29 . Fourth tube connector     30 . Fifth tube connector     31 . Sixth tube connector     32 . Seventh tube connector     33 . Eighth tube connector     34 . Ninth tube connector     35 . Tenth tube connector     36 . Eleventh tube connector     37 . Twelfth tube connector     38 . Thirteenth tube connector     39 . Fourteenth tube connector     40 . Fifteenth tube connector     41 . Straight center portion     42 . Play structure     43 . Center portion proximate end     44 . Non-center portion proximate end     45 . Flexing end       

     As seen in  FIG. 1 , a particular tube connector  10  of the invention comprises a center portion  11  and one projecting member  12  which is attached to center portion  11 . A center opening  13 , suitably sized to admit a tube, extends through center portion  11 . Said another way, the center opening and the outer part of the tube should be suitably sized such that the tube slides into the center opening in a free and easy manner, but the tube should also fit snugly in the center opening without excessive clearance. 
     Two center flexing members  14  are located opposite each other on the periphery of center opening  13 . Center flexing members  14  serve to maintain tension on an inserted tube, and prevent inadvertent movement of the tube after it has been inserted into center opening  13 . A center button  15 , having a beveled circular shape, is located on each center flexing member  14  and extends inward into center opening  13 . Center button  15  can engage with an opening on an inserted tube, to further secure the tube within center opening  13 . 
     Center portion  11  has a knurled outer circumference—that is, knurls  16  or indentations are present at regularly-spaced intervals on the outer circumference. The knurls  16  or indentations, which are semi-circular or arcuatein nature, allow a user to more easily grip center portion  11  when adding tubes to tube connector  10 , or when assembling tubes and tube connectors together into a play structure. 
     Projecting member  12  is attached to and projects outward from center portion  11 . In this particular tube connector, projecting member  12  lies in the same plane as center portion  11 , and is not angled up or down versus the center portion. Projecting member  12  has a circular tip  17  located at its non-center portion-proximate end  44 . The circumference of tip  17  is substantially the same as the inner circumference of a tube which fits over projecting member  12 , thus providing a snug fit for projecting member  12  inside the tube. 
     Said another way, the projecting member and the inner part of the tube should be suitably sized such that the tube slides over the projecting member in a free and easy manner, but the tube and projecting member should also fit together snugly without excessive clearance. Tip  17  also has a bevel  18  on its leading edge, in order to facilitate the placing of a tube over the end of projecting member  12 . The end of projecting member  12  close to center portion  11  is generally cylindrical, apart from two cut-outs at the top and bottom, and has substantially the same circumference as the inner part of the tube. 
     Two flexing tabs  19  are also located on opposing sides of projecting member  12 . Flexing tabs  19  are fixed at their non-center portion-proximate ends, and are free to flex inward and outward—i.e., toward and away from the main body of projecting member  12 —at their center portion-proximate ends. In other words, the flexing tabs of the invention are fixed at their leading edge and flex in and out at their trailing edge, when a tube is placed over the projecting member. This configuration allows for the flexing tabs to flex outward against the tube at a location significantly back from the non-center portion-proximate end  44  of the projecting member, after the tube is placed over the projecting member. Said another way, this configuration provides more consistent support for the tube along the length of the projecting member and better holds the tube in place. 
     A tab button  20 , having a beveled circular shape, is located on the flexing end  45  of flexing tab  19 . As further discussed with regard to  FIGS. 4-7 , tab button  20  fits into a corresponding circular through-opening on a tube placed over projecting member  12 . A tab stop  21  is located on the main body of projecting member  12 , and serves to limit the inward movement of flexing tab  19  toward the main body of projecting member  12 . Abutments  22  are located on opposite sides of the center portion-proximate end  43  of projecting member  12 , and these abutments provide stable resting surfaces for the tube end when the tube is fully in position over projecting member  12 . 
     In sum, and as further shown in  FIGS. 4-7 , a tube fully in position over projecting member  12  is well supported at the non-center portion-proximate end  44  of the projecting member by tip  17  pressing against the inner part of the tube; is also well supported between the center portion-proximate end  43  and non-center portion-proximate end  44  of projecting member  12  by the flexing tabs  19  pressing against the inner part of the tube; and is also well supported by the cylindrical nature of the projecting member at its center portion-proximate end  43 . 
     Tube connector  10  is further shown in  FIG. 2 , in a top view. The ability of flexing tabs  19  to move toward and away from the main body of projecting member  12  is indicated by the arrows shown between the flexing tabs and the main body of the projecting member. The ability of center flexing members  14  to move toward and away from center opening  13  is indicated by the arrows shown in that area. A center tab  23  is attached to center flexing member  14  on the side that is opposite center button  15 . A void or open space  24  surrounds center tab  23 , and this open space between the back wall of center flexing member  14  and the main body of center portion  11  allows center flexing member  14  to move toward and away from center opening  13  when a tube is inserted or removed from the center opening. Put another way, center flexing member  14  is attached only at its ends to the main body of center portion  11 , and this allows center flexing member  14  to flex back and forth. 
       FIG. 3  illustrates the tube  25  of the invention, which connects in various ways to the various tube connectors described herein in order to form play structures. Tube  25  is substantially round and hollow, and as indicated in  FIG. 3 , comes in any suitable length from short to long. Four substantially circular tube openings  26  are located around the circumference of each end of tube  25 . Tube openings  26  are spaced 90 degrees from each other around the circumference of tube  25 , such that there are openings through the wall of tube  25  at the top, bottom, and sides thereof. Tube openings  26  correspond with center buttons  15  or tab buttons  20 , depending on whether tube  25  is inserted into center opening  13  or placed over projecting member  12 , as further discussed below with regard to  FIGS. 4-9 .  
       FIG. 4  shows tube  25  in position for placement over projecting member  12 . Tube  25  is first positioned lengthwise with its hollow end next to tip  17  of projecting member  12 , and then tube  25  is pushed inward over projecting member  12  towards center portion  11 , as indicated by the directional arrow. It should be noted that in this figure, tube openings  26  in tube  25  are not yet aligned with tab buttons  20  of projecting member  12 . Thus, when tube  25  is pushed over projecting member  12 , flexing tabs  19  are pushed inward toward tab stops  21  and are held there by the inner wall of tube  25 .  
       FIG. 5  shows tube  25  fully pushed over projecting member  12 , with the end of tube  25  butting up against abutments  22 . Tab buttons  20  on flexing tabs  19  do not yet extend through tube openings  26 , because tube openings  26  and tab buttons  20  are not yet aligned with each other. To align tube openings with tab buttons  20 , tube  25  is twisted or rotated about projecting member  12   as indicated by the directional arrow, until tube openings  26  are brought in line with tab buttons  20 . When the tube openings are aligned over the tab buttons, flexing tabs  19  move outward from the main body of projecting member  12 , and tab buttons  20  extend through tube openings  26  and thereby lock tube  25  in place on projecting member  12 . The fully locked-in position of tube  25  on projecting member  12  is shown in  FIG. 6 .  
       FIG. 7  shows tube  25  in position for “straight-on” placement over projecting member  12 . In this figure, tube openings  26  at the sides of tube  25  are pre-aligned with tab buttons  20  which are also at the sides of projecting member  12 . Thus, when tube  25  is pushed straight onto projecting member  12  as indicated by the directional arrow, tab buttons  20  will extend into tube openings  26  and lock the tube onto the projecting member without any twisting required. When the tube is fully seated on the projecting member in this situation, the tube and tube connector are as shown in  FIG. 6 .  
     Removal of tube  25  from projection member  12  is basically the opposite of installation. With sufficient force, tube  25  can be pulled straight off projecting member  12 , as the beveled nature of tab buttons  20  allow tube openings  26  to ride back over them. During the removal process, each flexing tab  19  will be forced inward towards tab stop  21 , and tube  25  can then be easily pulled off projecting member  12 .    
     Alternatively, tube  25  can first be twisted or rotated about projecting member  12  until tube openings  26  are no longer aligned with tab buttons  20 . Flexing tabs  19  will be forced inward towards tab stops  21 , thus allowing tube  25  to be easily pulled off projecting member  12 . 
       FIG. 8  illustrates a tube  25  inserted into center opening  13 . In this figure, tube openings  26  are not engaged with center buttons  15 . Instead, center flexing members  14  located on opposite sides of center opening  13 , and center buttons  15  on the center flexing members, move back as tube  25  is inserted and then press against the outer wall of tube  25  to hold the tube in place in the center opening. Thereafter, a reasonable amount of force can move tube connector  10  along the length of tube  25 , but the tube connector will not move inadvertently in relation to the tube. 
       FIG. 9  also depicts a tube  25  inserted into center opening  13 . In this figure, tube openings  26  on opposite sides of tube  25  are engaged with center buttons  15  on opposite sides of center opening  13 . Similar to when tube  25  is pushed onto a projecting member, in order to engage the tube openings with the center buttons, tube  25  can be pushed into center opening  13  with the tube openings and center buttons not pre-aligned. In this case, a simple twist or rotation of tube  25  in center opening  13  (or, said another way, a twist or rotation of tube connector  10  about tube  25 ) is used to align the tube openings with the center buttons. Once center buttons  15  are aligned over tube openings  26 , center flexing members  14  flex back toward the tube and the center buttons extend into the tube openings, thus locking the tube in place in the tube connector. 
     Removal of tube  25  from center opening  13  is basically the opposite of installation. With sufficient force, tube  25  can be pulled straight out of center opening  13 , as the beveled nature of center buttons  15  allow tube openings  26  to ride back over them. During the removal process, center flexing members  14  will be forced slightly outward, and tube  25  can then be easily pulled out of center opening  13 . 
     Alternatively, tube  25  can first be twisted or rotated inside center opening  13  until tube openings  26  are no longer aligned with center buttons  15 . Center flexing members  14  will be forced outward, thus allowing tube  25  to be easily pulled out of center opening  13 . 
       FIGS. 10 to 35  illustrate other tube connectors of the invention. These other tube connectors have multiple projecting members attached to a center portion at various angles to each other. In some of these tube connectors, the projecting members lie in the same plane as each other and in the same plane as the center portion. In other tube connectors, the projecting members lie in different planes from each other (i.e., a projecting member may be tilted up from the plane of another connector); and/or the projecting members lie in a different plane from the center portion (i.e., a projecting member may be tilted up from the plane of the center portion). 
     These other tube connectors allow tubes to be connected together at various angles and in many different configurations to form a play structure. Other than having multiple projecting members at various angles and in various planes, the structures of these other tube connectors (i.e., the components of the projecting members and the components of the center portion) are the same as the structure of tube connector  10 . Operationally, the manner in which a tube is connected to and disconnected from the projecting members, and the manner in which a tube is connected to and disconnected from the center portion, is the same as with tube connector  10 . 
       FIGS. 10 and 11  show a second tube connector  27 , wherein two projecting members  12  are attached to a center portion  11  at substantially 180 degrees to each other. In this particular tube connector, projecting members  12  lie in the same plane as center portion  11 , and are not angled up or down versus the center portion. 
       FIGS. 12 and 13  show a third tube connector  28 , wherein two projecting members  12  are attached to a center portion  11  at substantially 90 degrees to each other. In this particular tube connector, projecting members  12  lie in the same plane as center portion  11 , and are not angled up or down versus the center portion. 
       FIGS. 14 and 15  show a fourth tube connector  29 , wherein four projecting members  12  are attached to a center portion  11  at substantially 90 degrees to each other. In this particular tube connector, projecting members  12  lie in the same plane as center portion  11 , and are not angled up or down versus the center portion. 
       FIGS. 16 and 17  show a fifth tube connector  30 , wherein three projecting members  12  are attached to a center portion  11  at substantially 90 degrees to each other. In other word, three “sides” of the center portion have projecting members attached, and one “side” has no projecting member. In this particular tube connector, projecting members  12  lie in the same plane as center portion  11 , and are not angled up or down versus the center portion. 
       FIGS. 18 and 19  show a sixth tube connector  31 , wherein two projecting members  12  are attached to a center portion  11  at substantially 90 degrees to each other. Another projecting member  12  is located between the two projecting members, substantially 45 degrees from each of them. The two projecting members  12  lie in the same plane as center portion  11 , and the other projecting member  12  is tilted up from the plane of center portion  11  at substantially a 45 degree angle. 
       FIGS. 20 and 21  show a seventh tube connector  32 , wherein four projecting members  12  are attached to a center portion  11  at substantially 90 degrees from each other. In addition, each of the projecting members  12  is tilted up from the plane of center portion  11  at substantially a 45 degree angle. 
       FIGS. 22 and 23  show an eighth tube connector  33 , wherein two projecting members  12  are attached to a center portion  11  at substantially 90 degrees to each other. Another projecting member  12  is located not between the two projecting members, but instead is substantially 45 degrees from one of them. All the projecting members  12  lie in the same plane as center portion  11 . 
       FIGS. 24 and 25  show a ninth tube connector  34 , wherein two projecting members  12  are attached to a center portion  11  at substantially 60 degrees to each other. The projecting members  12  lie in the same plane as center portion  11 . 
       FIGS. 26 and 27  show a tenth tube connector  35 , wherein four projecting members  12  are attached around a center portion  11  at substantially 90 degrees from each other. In addition, each of the projecting members  12  is tilted up from the plane of center portion  11  at substantially a 75 degree angle. 
       FIGS. 28 and 29  show an eleventh tube connector  36 , wherein two projecting members  12  are attached to a center portion  11  at substantially 90 degrees to each other. Another projecting member  12  is located between the two projecting members, substantially 45 degrees from each of them. The two projecting members  12  lie in the same plane as center portion  11 , and the other projecting member  12  is tilted up from the plane of center portion  11  at substantially a 75 degree angle. 
       FIGS. 30 and 31  show a twelfth tube connector  37 , wherein two projecting members  12  are attached to a center portion  11  at substantially 45 degrees from each other. One projecting member  12  lies in the same plane as center portion  11 , and the other projecting member  12  is tilted up from the plane of center portion  11  at substantially a 75 degree angle. 
       FIGS. 32 and 33  show a thirteenth tube connector  38 , wherein two projecting members  12  are attached to a center portion  11  at substantially 45 degrees from each other. One projecting member  12  lies in the same plane as center portion  11 , and the other projecting member  12  is tilted up from the plane of center portion  11  at substantially a 75 degree angle. This tube connector is similar to twelfth tube connector  37 , except that the tilted-up projecting member is on the other side of the non-tilted-up projecting member. Said another way, when the non-tilted-up projecting member is at “zero degrees” as seen in  FIGS. 31 and 33 , the tilted-up projecting member is 45 degrees to the right in thirteenth tube connector  38 , rather than 45 degrees to the left as in twelfth tube connector  37 . 
       FIGS. 34 and 35  show a fourteenth tube connector  39 , wherein two projecting members  12  are attached to a center portion  11  at substantially 45 degrees to each other. The projecting members  12  lie in the same plane as center portion  11 . 
       FIGS. 36 and 37  show a fifteenth tube connector  40 , wherein two projecting members  12  are attached to a straight center portion  41  at substantially 180 degrees to each other. Fifteenth tube connector  40  is used to attach two tubes together end-to-end, such that the attached tubes lie in the same plane. Except for having a straight center portion rather than a center portion through which a tube can be inserted, the projecting member components of fifteenth tube connector  40  are the same as the projecting member components of tube connector  10  and the other tube connectors discussed above. Operationally, the manner in which a tube is connected to and disconnected from the projecting member is the same as with tube connector  10  and the other tube connectors. 
       FIG. 38  illustrates the play structure system of the invention, wherein multiple tubes are connected together using multiple tube connectors, to form a play fort. Tubes  25  of various lengths form the frame of a play structure  42 . For simplicity, tube openings  26  are not shown in this figure—but it can be appreciated that the tube openings are the same as those already shown in  FIG. 3 ,  FIG. 6 , et al. The tubes in this particular play structure are connected together using third tube connectors  28  and eighth tube connectors  33 , as discussed below: 
     Third tube connectors  28  are used at the bottom corners of play structure  42 . One tube  25  is inserted into center opening  13 , and a tube  25  fits over each of the two projecting members  12  that are spaced substantially 90 degrees apart. It should be noted that the orientation of third tube connector  28  can be different than the orientation shown in  FIG. 37 —i.e., any one of the three tubes which 
     meet at the bottom corner can be inserted into the center opening of the tube connector, with the other two tubes fitting over the two projecting members that are spaced substantially 90 degrees apart. 
     An eighth tube connector  33  is used at each top corner of play structure  42 . One tube  25  is inserted into center opening  13 ; a tube  25  fits over each of the two projecting members  12  that are spaced substantially 90 degrees apart; and a tube  25  also fits over the projecting member  12  that is spaced substantially 45 degrees apart from one of the other two projecting members  12 . 
     A third tube connector  28  is used at each end of the roof peak of play structure  42 . One tube  25  is inserted into center opening  13 , and a tube  25  fits over each of the two projecting members  12  that are spaced substantially 90 degrees apart. And as with the connectors at the bottom corner, the orientation of third tube connector  28  at the roof peak can be different than the orientation shown—i.e., any one of the three tubes which meet at the roof peak can be inserted into the center opening of the tube connector, with the other two tubes fitting over the two projecting members that are spaced substantially 90 degrees apart. 
     It should be understood that various different tube connectors of the invention and tubes of various lengths can be used to build any number of different play structures. In addition, solid or flexible panels or other coverings can be attached to the tubes and tube connectors of the invention, in order to entirely or partially cover the frame of play structure  42 . 
     While the above descriptions contain many specificities, these shall not be construed as limitations on the scope of the invention, but rather as exemplifications of embodiments thereof. Many other variations are possible without departing from the spirit of the invention. 
     Accordingly, the scope of the invention should be determined not by the embodiments illustrated, but by the appended claims and their legal equivalents.