Patent Publication Number: US-6336234-B1

Title: Bottom frame structure for playpen

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a bottom frame structure for a playpen. 
     2. Description of the Related Art 
     A conventional bottom frame structure for a playpen in accordance with the prior art shown in FIG. 1 comprises a joint base  20  pivotally mounted between two rods  10  whereby the two rods  10  can be pivoted relative to each other so as to fold the bottom frame structure of the playpen. However, the bottom frame structure is not provided with any positioning device so that it is easily folded by an external force, thereby easily causing danger to the baby placed in the playpen. 
     SUMMARY OF THE INVENTION 
     In accordance with one aspect of the present invention, there is provided a bottom frame structure for a playpen comprising: four upright rods, a bottom frame, a positioning base, and a top frame, wherein, 
     the four upright rods are respectively located at four corners of the playpen for supporting and linking between the bottom frame and the top frame, two of the upright rods having a lower end secured with an inverted L-shaped support base, and the other two of the upright rods having a lower end secured with an inverted L-shaped wheel base having a roller; 
     the bottom frame is mounted on the lower end of the four upright rods and includes four first rods, two Y-shaped first connecting bases, four universal joints, four second rods, two T-shaped second connecting bases, and four third rods, 
     the four first rods each having a first end respectively pivoted to the horizontal section of the two support bases and the two wheel bases, 
     each of the two Y-shaped first connecting bases having three radially arranged pivot grooves and having a bottom secured with a resting post for supporting the first connecting base, two of the three pivot grooves of each of the two Y-shaped first connecting bases pivotally receiving a second end of each of the four first rods, 
     each of the four universal joints including a sleeve secured on a mediate portion of each of the four first rods, and a U-shaped pivot section which is rotatable toward any direction, 
     each of the four second rods having a first end pivoted to the pivot section of each of the four universal joints so that the four first rods and the four second rods form a rectangular frame, 
     each of the two T-shaped second connecting bases having three pivot slots and having a bottom secured with a resting rod for supporting the second connecting base, two of the pivot slots of each of the two T-shaped second connecting bases being in line with each other and each pivotally receiving a second end of each of the four second rods, 
     the four third rods being arranged between the first rods and the second rods in a cross intersecting manner, two of the four third rods having a first end pivoted to the pivot groove of each of the two first connecting bases and a second end connected to the positioning base, and the other two of the four third rods having a first end pivoted to the pivot slot of each of the two second connecting bases and a second end connected to the positioning base; 
     the positioning base is used to link the four third rods and includes a cruciform body, four fitting rod members, four U-shaped urging drive blocks, four elastic members, and a release block, 
     the body including four chambers each having an opening directed downward for receiving the second end of each of the four third rods, each of the four chambers having two side walls each defining a substantially L-shaped slide slot having an oblique upper end and a horizontal lower end and a circular hole located beside the horizontal lower end, the body having a top formed with four inclined surfaces each defining a rectangular slot connecting to each of the four chambers, and having a bottom secured with an abutting column, 
     each of the four fitting rod members having a first end provided with an insertion section secured and locked in the second end of each of the third rods by a threaded rod engaged with a nut, and a second end provided with a snap abutting section defining a transverse through hole and provided with an L-shaped snap abutting recess, a rivet pin in turn extending through the circular hole of each of the four chambers of the body and through the through hole of the snap abutting section of each of the four fitting rod members, so that each of the four fitting rod members is pivoted to each of the four chambers of the body, 
     each of the four urging drive blocks having two side walls each defining a circular hole and having a top portion provided with a rectangular bar having an upper section protruding outward from the rectangular slot of the body and defining a through hole, a lock pin in turn extending through the slide slot of the body and through the circular hole of each of the four urging drive blocks, so that the lock pin is detachably rested on the snap abutting recess of each of the four fitting rod members, 
     each of the four elastic members is mounted around the rectangular bar of each of the four urging drive blocks and having a lower end pressing the top portion of each of the four urging drive blocks and an upper end pressing an upper wall of each of the four chambers of the body, and 
     the release block movably mounted on the body and defining two spaced slot holes for allowing passage of a loop-shaped lift strap, the release block having four sides each provided with two spaced abutting plates rested on each of the four inclined surfaces of the body, the rectangular bar of each of the four urging drive blocks being received between the two abutting plates, each of the abutting plates defining a circular hole aligning with the through hole of the rectangular bar of each of the four urging drive blocks, a pivot rod in turn extending through the circular hole of each of the abutting plates and through the through hole of the rectangular bar, thereby pivoting the rectangular bar to the abutting plates of the release block. 
     The primary objective of the present invention is to provide a bottom frame structure for a playpen, wherein, the positioning function of the bottom frame can be used to control the folding and expanding actions of the skeleton of the playpen, thereby preventing the skeleton of the playpen from being easily folded due to the hit of an external force so as to protect the safety of the playpen. 
     Another objective of the present invention is to provide a bottom frame structure for a playpen, wherein, the support points and the connection points of the skeleton of the playpen have a rigid strength, thereby enhancing the loading and supporting strength of the playpen. 
     Further benefits and advantages of the present invention will become apparent after a careful reading of the detailed description with appropriate reference to the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an operational plan view of a conventional bottom frame structure for a playpen in accordance with the prior art; 
     FIG. 2 is a perspective view of a bottom frame structure for a playpen in accordance with the present invention; 
     FIG. 3 is an exploded view of a positioning base of the bottom frame structure for a playpen in accordance with the present invention; 
     FIG. 4 is a front plan cross-sectional view of the positioning base as shown in FIG. 3; 
     FIG. 5 is an operational view of the playpen as shown in FIG. 2; 
     FIG. 6 is an operational view of the positioning base as shown in FIG. 4; 
     FIG. 7 is an exploded view of a positioning base of the bottom frame structure for a playpen in accordance with another embodiment of the present invention; 
     FIG. 8 is a front plan cross-sectional view of the positioning base as shown in FIG. 7; and 
     FIG. 9 is an operational view of the positioning base as shown in FIG.  8 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to the drawings and initially to FIGS. 2-4, a bottom frame structure for a playpen in accordance with the present invention comprises four upright rods  2 , a bottom frame  3 , a positioning base  4 , and a top frame  5 . 
     The four upright rods  2  are respectively located at four corners of the playpen for supporting and linking between the bottom frame  3  and the top frame  5 , two of the upright rods  2  having a lower end secured with an inverted L-shaped support base  21 , and the other two of the upright rods  2  having a lower end secured with an inverted L-shaped wheel base  22  having a roller  221 . 
     The bottom frame  3  is mounted on the lower end of the four upright rods  2  and mainly includes four first rods  31 , two Y-shaped first connecting bases  32 , four universal joints  33 , four second rods  34 , two T-shaped second connecting bases  35 , and four third rods  36 . 
     The four first rods  31  each have a first end respectively pivoted to the horizontal section of the two support bases  21  and the two wheel bases  22 . Each of the two Y-shaped first connecting bases  32  has three radially arranged pivot grooves  321  and having a bottom secured with a resting post  322  for supporting the first connecting base  32 , two of the three pivot grooves  321  of each of the two Y-shaped first connecting bases  32  pivotally receiving a second end of each of the four first rods  31 . Each of the four universal joints  33  includes a sleeve  331  secured on a mediate portion of each of the four first rods  31 , and a U-shaped pivot section  332  which is rotatable toward any direction. Each of the four second rods  34  has a first end pivoted to the pivot section  332  of each of the four universal joints  33  so that the four first rods  31  and the four second rods  34  form a rectangular frame. Each of the two T-shaped second connecting bases  35  has three pivot slots  351  and having a bottom secured with a resting rod  352  for supporting the second connecting base  35 , two of the pivot slots  351  of each of the two T-shaped second connecting bases  35  being in line with each other and each pivotally receiving a second end of each of the four second rods  34 . The four third rods  36  are arranged between the first rods  31  and the second rods  34  in a cross intersecting manner, two of the four third rods  36  having a first end pivoted to the pivot groove  321  of each of the two first connecting bases  32  and a second end connected to the positioning base  4 , and the other two of the four third rods  36  having a first end pivoted to the pivot slot  351  of each of the two second connecting bases  35  and a second end connected to the positioning base  4 . 
     The positioning base  4  is used to link the four third rods  36  and includes a cruciform body  41 , four fitting rod members  42 , four U-shaped urging drive blocks  43 , four elastic members  44 , and a release block  45 . 
     The body  41  includes four chambers  411  each having an opening directed downward for receiving the second end of each of the four third rods  36 , each of the four chambers  411  having two side walls each defining a substantially L-shaped slide slot  412  having an oblique upper end and a horizontal lower end  4121  and a circular hole  413  located beside the horizontal lower end  4121 , the body  41  having a top formed with four inclined surfaces  414  each defining a rectangular slot  415  connecting to each of the four chambers  411 , and having a bottom secured with an abutting column  416 . Each of the four fitting rod members  42  has a first end provided with an insertion section  421  secured and locked in the second end of each of the third rods  36  by a threaded rod  422  engaged with a nut  423 , and a second end provided with a snap abutting section  424  defining a transverse through hole  4242  and provided with an L-shaped snap abutting recess  4241 , a rivet pin  4243  in turn extending through the circular hole  413  of each of the four chambers  411  of the body  41  and through the through hole  4242  of the snap abutting section  424  of each of the four fitting rod members  42 , so that each of the four fitting rod members  42  is pivoted to each of the four chambers  411  of the body  41 . Each of the four urging drive blocks  43  has two side walls each defining a circular hole  431  and having a top portion provided with a rectangular bar  432  having an upper section protruding outward from the rectangular slot  415  of the body  41  and defining a through hole  4321 , a lock pin  4311  in turn extending through the slide slot  412  of the body  41  and through the circular hole  431  of each of the four urging drive blocks  43 , so that the lock pin  4311  is detachably rested on the snap abutting recess  4241  of each of the four fitting rod members  42 . Each of the four elastic members  44  is mounted around the rectangular bar  432  of each of the four urging drive blocks  43 , and having a lower end pressing the top portion of each of the four urging drive blocks  43  and an upper end pressing an upper wall of each of the four chambers  411  of the body  41 . The release block  45  is movably mounted on the body  41  and defining two spaced slot holes  451  for allowing passage of a loop-shaped lift strap  452 , the release block  45  having four sides each provided with two spaced abutting plates  453  rested on each of the four inclined surfaces  414  of the body  41 , the rectangular bar  432  of each of the four urging drive blocks  43  being received between the two abutting plates  453 , each of the abutting plates  453  defining a circular hole  4531  aligning with the through hole  4321  of the rectangular bar  432  of each of the four urging drive blocks  43 , a pivot rod  454  in turn extending through the circular hole  4531  of each of the abutting plates  453  and through the through hole  4321  of the rectangular bar  432 , thereby pivoting the rectangular bar  432  to the abutting plates  453  of the release block  45 . 
     The top frame  5  includes four pivot bases  51  each secured on the top of each of the four upright rods  2  and each having two sides each pivotally provided with a support rod  52 , thereby forming a rectangular frame, and four joint bases  53  each pivotally mounted between two adjacent support rods  52 . Each of the joint bases  53  is provided with an elastic piece section  531  and two locking slots  532  for fixing or bending the support rods  52 . 
     In operation, referring to FIGS. 2-6, the elastic piece section  531  of the joint base  53  is pressed by the user, thereby detaching the support rods  52  from the locking slots  532  so that the support rods  52  can be pivoted toward each other. 
     The lift strap  452  of the positioning base  4  is then pulled upward to move the release block  45  upward, to move the rectangular bar  432  upward by the abutting plates  453 , to move the lock pin  4311  of the urging drive block  43  from the horizontal lower end  4121  to the oblique upper end of the slide slot  412  as shown in FIG. 6, thereby detaching the lock pin  4311  from the snap abutting recess  4241  of the fitting rod member  42 , so that the third rod  36  can be pivoted about the rivet pin  4243  to move toward the center of the bottom frame  3  while the first rods  31  and the second rods  34  are also moved toward the center of the playpen by the drawing action of the third rods  36 , thereby easily folding the skeleton of the playpen. 
     Referring now to FIGS. 7-9, in accordance with another embodiment of the present invention, the snap abutting recess  4241  of each of the fitting rod members  42  has an arcuate shape defining an opening directed upward, and the slide slot  412  of each of the chambers  411  of the body  41  is an elongated oblique slot. 
     Accordingly, the snap abutting recess  4241  of the fitting rod member  42  is locked by the lock pin  4311  of the urging drive block  43 , thereby preventing the skeleton of the playpen from being folded arbitrarily so as to protect the baby in the playpen. In addition, the support points and the connection points of the skeleton of the playpen have a rigid strength, thereby enhancing the loading and supporting strength of the playpen. Further, the bottom frame  3  can be easily folded by pulling the lift strap  452  of the positioning base  4 , thereby facilitating the folding of the playpen. 
     It should be clear to those skilled in the art that further embodiments may be made without departing from the scope of the present invention.