Patent Publication Number: US-7712261-B2

Title: Collapsible structure with self-locking mechanism and method of erecting a collapsible structure

Description:
BACKGROUND AND SUMMARY 
     The present invention relates to collapsible structures and, more particularly, to collapsible structures with self-locking mechanism and methods of erecting a collapsible structure. 
     My prior U.S. Pat. Nos. 6,141,934, 5,651,228, 5,444,946, 5,274,980, 5,230,196, RE33,710, 4,970,841, 4,838,003, 4,800,663, 4,761,929, 4,747,239, 4,689,932, 4,666,102, 4,637,180, 4,579,066, 4,561,618, 4,522,008, 4,512,097, 4,473,986, 4,437,275, 4,334,660, 4,290,244, 4,280,521, 4,026,313, and 3,968,808 are incorporated by reference and show various collapsible structures and components therefor. In many collapsible structures of the general type described in these patents, in the course of erecting the structures, the structures must extend beyond the dimensions of the erected shelter. For example, in my U.S. Pat. Nos. 5,444,946 and 5,274,980, in the course of erecting the shelters, they are typically expanded laterally outward significantly past the lateral dimensions of the finished structure. This makes it difficult to provide the structures with a cover as is typically provided on portable shelter type devices. Ordinarily, the covers are attached after erection of the frame of the structure. 
     Also, because the structures during erection are typically expanded beyond the footprint of the structures in their erected condition, they are generally only secured to the ground or a base after they are finally erected. This can make erection of the structures difficult. For example, in windy conditions, the structures may be blown around. This problem can be exacerbated if there is cover material on the frame because the cover material can act as a sail and make it that much more difficult to erect the structure. 
     During break down of these structures, the same problems occur as during erection. The covers are ordinarily taken off and the structures are ordinarily disconnected from any ground or base supporting structures before lowering the frame. 
     It is desirable to provide a collapsible structure that can be erected and broken down without the need to remove a cover from the structure. It is also desirable to provide a structure that can be secured to the ground or a base while the structure is being erected or broken down. 
     In accordance with one aspect of the present invention, a collapsible structure with a self-locking mechanism includes a first hub, at least two struts pivotably connected at first ends thereof to the first hub and movable relative to each another between a folded position and an expanded position, and a tension member adapted to limit pivotable movement of the at least two struts such that, when in the expanded position, the at least two struts define an angle of less than 180°. The structure further includes a locking hub and at least two locking struts pivotably connected at first ends thereof to the locking hub and, at seconds ends thereof, to connection points on respective ones of the at least two struts. 
     In accordance with another aspect of the present invention, a method of erecting a collapsible structure includes unfolding a collapsible structure from a folded condition to a collapsed condition. A plurality of base-defining ends of a plurality of end struts of the collapsible structure are fixed in the collapsed condition to points on a surface, the points generally defining a size of a base of the structure in the erected condition. After fixing the base-defining ends to the points on the surface, a center region of the collapsible structure is lifted to an erected height of the collapsible structure. The collapsible structure is locked in an erected condition after lifting the structure to its erected height using an internal locking arrangement of the collapsible structure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The features and advantages of the present invention are well understood by reading the following detailed description in conjunction with the drawings in which like numerals indicate similar elements and in which: 
         FIG. 1A  is a side view of a collapsible structure according to an embodiment of the present invention in an erected condition; 
         FIG. 1B  is a side view of a portion of the structure of  FIG. 1A ; 
         FIG. 2  is a side view of a collapsible structure according to an embodiment of the present invention in a folded condition; 
         FIG. 3  is a perspective view of a collapsible structure according to an embodiment of the present invention; 
         FIGS. 4A-4C  are perspective views of a hub according to an embodiment of the present invention; 
         FIG. 5  is a side view of a collapsible structure according to an embodiment of the present invention, showing the structure in a position between a folded condition and an erected condition. 
     
    
    
     DETAILED DESCRIPTION 
     A collapsible structure  21  according to the present invention is seen in  FIG. 1A . The structure  21  includes what is referred to for purposes of the present application as a self-locking mechanism  23 , seen in isolated in  FIG. 1B , for locking the structure in an erected condition. The structure  21  has a self-locking mechanism  23  in the sense that the self-locking mechanism  23  can maintain the structure in an erected condition by itself, without the need for additional locking structures. However, additional locking structures may be used with the structure  21 , such as to provide additional strength. 
     The structure  21  includes a first hub  25  and at least two struts  27   a  and  27   b  pivotably connected at first ends  27   a ′ and  27   b ′ thereof to the first hub. The structure  21  includes at least two struts but will ordinarily include three or four struts ( FIG. 3 ). Structures with more than four struts may also be provided, depending upon, for example, the shape of the structure desired. The struts  27   a  and  27   b  are preferably light weight rods, such as aluminum tubes. The hubs  25  may take a variety of suitable forms such as, for example, the form of the hubs described in U.S. Pat. No. 4,280,521, which is incorporated by reference, and permit pivotal attachment of the struts. 
     The struts  27   a  and  27   b  are movable relative to each another between a folded position ( FIG. 2 ) and an expanded position ( FIG. 1A ). The structure  21  also includes a tension member  29  adapted to limit pivotable movement of the struts  27   a  and  27   b  such that, when in the expanded position, the struts define an angle of less than 180° when viewed from the side, i.e., they are not coplanar. Of course, when viewed from the top, two struts  27   a  and  27   b  may be arranged at 180° relative to one another. 
     The tension member  29  may take a number of different forms. The tension member  29  may, for example, be a wire  29   w  that is attached to the struts  27   a  and  27   b , a cover  29   c  of the collapsible structure  21 , such as a fabric cover, or a base  29   b  to which the collapsible structure is attached. Ordinarily, multiple different tension members will be used simultaneously. 
     The self-locking mechanism  23  also includes a locking hub  31  and at least two locking struts  33   a  and  33   b  pivotably connected at first ends  33   a ′ and  33   b ′ thereof to the locking hub. The locking struts  33   a  and  33   b  are connected at seconds ends  33   a ″ and  33   b ″ thereof to connection points  35   a  and  35   b  on respective ones of the at least two struts  27   a  and  27   b . The locking hub  31  is structured to limit the angle through which struts attached to the locking hub can pivot. More particularly, the locking hub  31  permits the struts to pivot through an angle greater than 180° when the struts are viewed from the side. Stated differently, the locking hub  31  permits the struts to move from a first position, such as a folded position in which the struts are all substantially parallel to one another, to a locked position that is reached after the struts pass through a position in which they lie in the same plane, i.e., are at an angle of 180° to one another when viewed from the side. 
     As seen in  FIG. 1B , a distance D between a connection point  35   a  or  35   b  and the first hub  25  for any one the struts  27   a  and  27   b  is greater than a length L of a respective one of the locking struts  33   a  or  33   b . However, the distance between the connection point  35   a  or  35   b  and the first hub  25  for the one of the at least two struts  27   a  or  27   b  multiplied by a cosine of an angle Θ defined by a plane P in which the connection points and of all of the struts lie and one of the struts  27   a  or  27   b  is less than the length L of the respective one of the at least two locking struts  33   a  or  33   b.    
     When erecting the structure  21 , the structure is locked in place with the self locking mechanism  23  by causing the locking struts  33   a  and  33   b  to pivot through an angle greater than 90° relative to the locking hub when the locking struts are moved between a folded position ( FIG. 2 ) and a locked position ( FIGS. 1A and 1B ). In other words, the locking struts  33   a  and  33   b  pass through the plane defined by the connection points  35   a  and  35   b , even though the combined length of the locking struts is greater than the distance between the connection points. This is ordinarily permitted to occur due to the flexibility of the components of the structure  21  such as the struts  27   a  and  27   b , the locking struts  33   a  and  33   b , and the tension member  29 . 
     In order to cause the locking struts  33   a  and  33   b  to pass through the plane P, a user erecting the structure applies a force, which will ordinarily be applied upwardly to the locking hub  31 , sufficient to overcome the force with which the tension member  29  resists moving the locking struts through the plane by resisting movement of the struts  27   a  and  27   b  past the predetermined degree of maximum separation. Once the locking struts  33   a  and  33   b  have passed upwardly through the plane P, the locking struts will only move downwardly through the plane by applying a downwardly directed force and, as a result, the structure  21  will remain in an erected condition. If desired, an additional locking mechanism can be provided to assist the locking struts  33   a  and  33   b  to keep the structure  21  in an erected condition. Also, as seen in  FIG. 1B , it is desirable to provide a stop to prevent the locking hub  31  from extending too far upwardly and to provide support for the locking hub. The stop may take a variety of suitable forms. A stop in the form of a hub  125  pivotably attached to first and second struts  127   a  and  127   b  that are, in turn, pivotably attached to struts  27   a  and  27   b , respectively, is shown. 
     As seen in  FIGS. 1A and 1B , the collapsible structure  21  preferably also includes at least two second struts  37   a  and  37   b  pivotably connected at first ends thereof  37   a ′ and  37   b ′ to respective ones of the at least two struts  27   a  and  27   b . The at least two second struts  37   a  and  37   b  can be pivotably connected to the at least two struts  27   a  and  27   b  at the connection points  35   a  and  35   b  on respective ones of the at least two struts or, as seen in  FIG. 1B  in phantom, at points  39   a  and  39   b  between the connection points and the second ends  27   a ″ and  27   b ″ of respective ones of the at least two struts  27   a  and  27   b . The lengths of the various struts and the position of pivot or connection points of the various struts will ordinarily be selected such that, when the structure  21  is in a folded condition, all of the struts will be substantially parallel to one another, as seen in  FIG. 2 . 
     As seen in  FIG. 1A , the structure  21  includes at least two second hubs  43   a  and  43   b . Second ends  37   a ″ and  37   b ″ of the at least two second struts  37   a  and  37   b  are pivotably connected to respective ones of the at least two second hubs  43   a  and  43   b.    
     The structure  21  further includes at least two third struts  45   a  and  45   b . First ends  45   a ′ and  45   b ′ of the at least two third struts  45   a  and  45   b  are pivotably connected to respective ones of the at least two second hubs  43   a  and  43   b.    
     The structure  21  further includes at least two third hubs  47   a  and  47   b . Second ends  27   a ″ and  27   b ″ of the at least two first struts  27   a  and  27   b  are pivotably connected to respective ones of the at least two third hubs  47   a  and  47   b.    
     The structure  21  further includes at least two fourth struts  49   a  and  49   b . First ends  49   a ′ and  49   b ′ of the at least two fourth struts  49   a  and  49   b  are pivotably connected to respective ones of the at least two third hubs  47   a  and  47   b  and are pivotably connected at connection points  51   a  and  51   b  to respective ones of the at least two third struts  45   a  and  45   b.    
     Similar to the pivoting of the locking struts  33   a  and  33   b  relative to the locking hub  31 , the first struts  27   a  and  27   b  and the fourth struts  49   a  and  49   b  are each ordinarily adapted to pivot through an angle greater than 90° when the first struts and fourth struts pivot relative to respective ones of the third hubs  47   a  and  47   b  between a folded position and a locked position. The third hubs  47   a  and  47   b  are ordinarily arranged to permit the pairs of struts  27   a  and  49   a  and  27   b  and  49   b  to pivot through an angle greater than 180°, when the struts are viewed from the side. Stated differently, the third hubs  47   a  and  47   b  permit the struts  27   a  and  49   a  and  27   b  and  49   b  to move from a first position, such as a folded position in which the struts are all substantially parallel to one another, to a locked position that is reached after the struts pass through a position in which they lie in the same plane, i.e., are at an angle of 180° to one another when viewed from the side. 
     The collapsible structure  21  seen in  FIG. 1A  also includes at least two fourth hubs  53   a  and  53   b . Second ends  49   a ″ and  49   b ″ of the at least two fourth struts  49   a  and  49   b  are pivotably connected to respective ones of the at least two fourth hubs  53   a  and  53   b.    
     The collapsible structure  21  seen in  FIG. 1A  also includes at least two fifth struts  55   a  and  55   b . First ends  55   a ′ and  55   b ′ of the at least two fifth struts  55   a  and  55   b  are pivotably connected to respective ones of the at least two fourth hubs  53   a  and  53   b.    
     The collapsible structure  21  seen in  FIG. 1A  also includes at least two fifth hubs  57   a  and  57   b . Second ends  45   a ″ and  45   b ″ of the at least two third struts  45   a  and  45   b  are pivotably connected to respective ones of the at least two fifth hubs  57   a  and  57   b.    
     The collapsible structure  21  seen in  FIG. 1A  also includes at least two sixth struts  59   a  and  59   b . First ends  59   a ′ and  59   b ′ of the at least two sixth struts  59   a  and  59   b  are pivotably connected to respective ones of the at least two fifth hubs  57   a  and  57   b . The at least two sixth struts  59   a  and  59   b  are pivotably connected to respective ones of the at least two fifth struts  55   a  and  55   b  at connection points  60   a  and  60   b.    
     Similar to the pivoting of the locking struts  33   a  and  33   b  relative to the locking hub  31 , and the pivoting of the first struts  27   a  and  27   b  and the fourth struts  49   a  and  49   b  relative to the third hubs  47   a  and  47   b , the third struts  45   a  and  45   b  and the sixth struts  59   a  and  59   b  are ordinarily each adapted to pivot through an angle greater than 90° when the third struts and sixth struts pivot relative to respective ones of the fifth hubs  57   a  and  57   b  between a folded position and a locked position. The fifth hubs  57   a  and  57   b  are ordinarily arranged to permit the pairs of struts  45   a  and  59   a  and  45   b  and  59   b  to pivot through an angle greater than 180°, when the struts are viewed from the side. Stated differently, the fifth hubs  57   a  and  57   b  permit the struts  45   a  and  59   a  and  45   b  and  59   b  to move from a first position, such as a folded position in which the struts are all substantially parallel to one another, to a locked position that is reached after the struts pass through a position in which they lie in the same plane, i.e., are at an angle of 180° to one another when viewed from the side. 
     A collapsible structure  21  having four strut and hub arrangements extending radially from a centerpoint is shown in  FIG. 3 . Here, the collapsible structure includes four struts  27   a ,  27   b ,  27   c , and  27   d  pivotably connected at first ends thereof to the first hub  25 . The struts  27   a ,  27   b ,  27   c , and  27   d  are spaced relative to one another about the first hub  25  at 90° and are movable relative to each another between a folded position and an expanded position. A tension member such as a wire  29   w  attached to the first struts  27   a ,  27   b ,  27   c , and  27   d  is provided that is adapted to limit pivotable movement of the struts such that, when in the expanded position, the four struts define an angle of less than 180°. 
     Four locking struts  33   a ,  33   b ,  33   c ,  33   d  are pivotably connected at first ends thereof to the locking hub  31 . The locking struts  33   a ,  33   b ,  33   c ,  33   d  are connected at seconds ends thereof, to connection points  35   a ,  35   b ,  35   c ,  35   d  on respective ones of the four struts  27   a ,  27   b ,  27   c , and  27   d . Four second struts  37   a ,  37   b ,  37   c , and  37   d  are pivotably connected at first ends thereof to respective ones of the four struts  27   a ,  27   b ,  27   c , and  27   d . Four second hubs  43   a ,  43   b ,  43   c ,  43   d  are provided. Second ends of the four second struts  37   a ,  37   b ,  37   c , and  37   d  are pivotably connected to respective ones of the four second hubs. Four third hubs  47   a ,  47   b ,  47   c ,  47   d  are provided. Second ends of the four first struts  27   a ,  27   b ,  27   c , and  27   d  are pivotably connected to respective ones of the four third hubs  47   a ,  47   b ,  47   c ,  47   d.    
     The four strut and hub arrangements may be tied together by extension arrangements including four extension hubs  61   a ,  61   b ,  61   c ,  61   d , eight extension struts,  63   a   1 ,  63   b   1 ,  63   c   1 ,  63   d   1 ,  63   a   2 ,  63   b   2 ,  63   c   2 ,  63   d   2 , and eight extension arms  65   a   1 ,  65   b   1 ,  65   c   1 ,  65   d   1 ,  65   a   2 ,  65   b   2 ,  65   c   2 ,  65   d   2 . Four pairs  63   a   1  and  63   a   2 ,  63   b   1  and  63   b   2 ,  63   c   1  and  63   c   2 , and  63   d   1  and  63   d   2  of the eight extension struts are pivotably connected at first ends thereof to respective ones of the four second hubs  43   a ,  43   b ,  43   c ,  43   d  at right angles to the second struts  37   a ,  37   b ,  37   c ,  37   d  and are pivotably connected at second ends thereof to respective ones of the four extension hubs  61   a ,  61   b ,  61   c ,  61   d . Four pairs  65   a   1  and  65   a   2 ,  65   b   1  and  65   b   2 ,  65   c   1  and  65   c   2 , and  65   d   1  and  65   d   2  of the eight extension arms are pivotably connected at first ends thereof to respective ones of the four third hubs  47   a ,  47   b ,  47   c ,  47   d  at right angles to the first struts  27   a ,  27   b ,  27   c ,  27   d  and each of the eight extension arms are pivotably connected at second ends thereof to respective ones of the eight extension struts  63   a   1  and  63   a   2 ,  63   b   1  and  63   b   2 ,  63   c   1  and  63   c   2 , and  63   d   1  and  63   d   2 . In addition to tying together the four strut and hub arrangements, the extension arrangements can provide a collapsible structure  21  with sides that are more vertical, thus providing more usable space within the structure. Instead of or in addition to the extension arrangements described, however, additional strength and suitable side verticality can be obtained by providing a self-locking mechanism substantially like the mechanism  23  and having at least two scissors instead of the single scissor formed by the struts  55   a  and  59   a ,  55   b  and  59   b ,  55   c  and  59   c , and  55   d  and  59   d.    
     Turning to the embodiment shown in  FIG. 1A , the locking hub  31 , the third hubs  47   a ,  47   b , and the fifth hubs  57   a ,  57   b  may be in the form of U-shaped channel structures  67  as shown in  FIGS. 4A-4C . The type of hub shown in  FIGS. 4A-4C  limits the amount that the struts can pivot and is particularly well-suited for use as the locking hub  31 , the third hubs  47   a ,  47   b , and the fifth hubs  57   a ,  57   b . The first hub  25 , the second hubs  43   a ,  43   b , and the fourth hubs  53   a ,  53   b  may also be of the form shown in  FIGS. 4A-4C . Struts  69  are pivotably attached to the channel structure  67  by pivot pins  71 . The struts  69  can be folded so that they are substantially parallel to one another as seen in  FIG. 4A . The struts  69  can be unfolded past a position in which they are substantially coaxial and lie in a common plane, i.e., they are disposed at 180° to one another and have each pivoted 90° from their initial, folded position as seen in  FIG. 4B . The struts  69  can be pivoted to a point where they are blocked from pivoting further by the channel structure  67 , as shown in  FIG. 4C . As shown in  FIG. 4C  in phantom, additional channels  67 ′ can be attached to a main channel  67  to permit additional struts  69  to be attached. In the embodiment of the collapsible structure  21  shown in  FIG. 3 , the locking hub  31 , the first hub  25 , the second hubs  43   a ,  43   b ,  43   c ,  43   d , and the third hubs  47   a ,  47   b ,  47   c , and  47   d  can be arranged to have four struts attached to them. 
     A method of erecting a collapsible structure  21  is seen in  FIGS. 2 ,  5 , and  1 A. In the method, a collapsible structure  21  is unfolded from a folded condition as seen in  FIG. 2  to a collapsed condition as seen in  FIG. 5 . While in the collapsed condition, a plurality of base-defining ends  73   a  and  73   b  of a plurality of end struts such as the fifth struts  55   a  and  55   b  or the sixth struts  59   a  and  59   b  or both are fixed to points  75   a  and  75   b  on a surface such as the ground or a base structure  29   b . The points  75   a  and  75   b  generally define a size of a base of the structure  21  in the erected condition. After fixing the base-defining ends  73   a  and  73   b  to the points  75   a  and  75   b  on the surface, a center region of the collapsible structure  21  is lifted to an erected height as seen in  FIG. 1A . The collapsible structure  21  is locked in an erected condition after lifting the structure to its erected height using an internal locking arrangement  23  of the collapsible structure. 
     The internal locking arrangement  23  includes the first hub  25 . At least two struts  27   a  and  27   b  are pivotably connected at first ends  27   a ′ and  27   b ′ thereof to the first hub  25  movable relative to each another between a folded position ( FIG. 2 ) and an expanded or erected position  FIG. 1A . A tension member such as a wire, a cover, or a base limits pivotable movement of the at least two struts  27   a  and  27   b  such that, when in the erected position, the at least two struts define an angle of less than 180°. A locking hub  31  is provided. At least two locking struts  33   a  and  33   b  are pivotably connected at first ends  33   a ′ and  33   b ′ thereof to the locking hub  31  and, at seconds ends thereof, to connection points  35   a  and  35   b  on respective ones of the at least two struts  27   a  and  27   b . Each of the locking struts  33   a  and  33   b  is pivoted relative to the locking hub  31  through an angle greater than 90° between a folded position of the locking struts when the collapsible structure is in the folded condition ( FIG. 2 ) and a locked position of the locking struts ( FIG. 1A ) when the collapsible structure is in the erected condition. 
     The structure  21  shown in  FIGS. 2 ,  5 , and  1 A is simple to erect particularly in view of the fact that the base-defining ends  69   a  and  69   b  of the structure can be fixed in place before erecting the structure. Also, the structure  21  can be provided with a cover that can remain on the structure at all times and need not be detached during erection or during break down. A user can then stand inside of the structure  21  and lift the locking hub  31  upwardly to lock the locking mechanism  23 . The structure  21  need not be splayed across the ground prior to erection and can be set up in minimal space. 
     The structure  21  will remain in the erected condition shown in  FIG. 1A  until the locking arrangement  23  is moved to an unlocked position by pulling downwardly on the locking hub  31  and the locking struts  31  so that the locking struts again pass through a plane in which they are coplanar. When collapsing the structure  21 , it can be collapsed by “imploding” it, without the need for expanding the structure outwardly beyond the confines of the outline of the base of the structure. 
     If desired, the structure  21  can be further supported in the erected condition by additional structures, such as structures designed to prevent unlocking of the locking arrangement  23  such as cords, chains, clips, and the like. As seen in  FIG. 1 , a cover  29   c  is ordinarily provided on the outside of the structure  21 . If desired, a cover (not shown) can also be provided on the inside of the structure. 
     While this invention had been illustrated and described in accordance with a preferred embodiment, it is recognized that variations and changes may be made therein without departing from the invention as set forth in the claims.