Abstract:
A retractable frame structure for baby trailer includes a rigid base frame, a bottom frame bar horizontally movable in and out of a front side of the rigid bottom, a first locking device for selectively locking the bottom frame bar to the base frame in the extended or received position, a backrest, a top frame bar vertically movable in and out of a top side of the backrest, and a second locking device for selectively locking the top frame bar to the backrest in the extended or received position.

Description:
BACKGROUND AND SUMMARY OF THE INVENTION 
     The present invention relates to a baby trailer and more specifically, to a retractable frame structure for baby trailer, which comprises a rigid base frame, a bottom frame bar horizontally slidably mounted in the base frame and selectively lockable in the extended or received position, a backrest, and a top frame bar vertically slidably mounted in the backrest and selectively lockable in the extended or received position. 
     U.S. Pat. Nos. 7,341,265 and 8,444,173 disclose a baby trailer that allows adjustment of the bottom frame bar between an extended position and a received position. However, because the seat supported on the bottom frame bar is a flexible fabric material, it will be forced to curve downwards when a baby or child sits thereof, causing the baby or child to feel uncomfortable. When the baby trailer is moved over a large stone or any other external object on the road, the downwardly curved seat can hit the external object, leading to an injury accident. In order to assure a high level of stability and sitting comfort, the seat is preferably made of a rigid or hard material and attached with a soft or flexible pad or covering. Further, the frame structures of conventional baby trailers are not highly retractable or collapsible to save the storage space. In consequence, conventional baby trailers are not conveniently for packaging, delivery or storage. 
     The present invention has been accomplished under the circumstances in view. It is therefore the main object of the present invention to provide a retractable frame structure for baby trailer, which is highly retractable to reduce the storage space, saving the packaging and delivery costs. It is another object of the present invention to provide a retractable frame structure for baby trailer, which assures a high level of sitting comfort and moving safety and operational convenience. 
     To achieve these and other objects of the present invention, a retractable frame structure for baby trailer comprises a rigid base frame, a bottom frame bar horizontally movable in and out of a front side of the rigid bottom, first lock means for selectively locking the bottom frame bar to the base frame in the extended or received position, a backrest, a top frame bar vertically movable in and out of a top side of the backrest, and a second lock means for selectively locking the top frame bar to the backrest in the extended or received position. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         FIG. 1  is an elevational view of a retractable frame structure for foldable baby trailer in accordance with the present invention. 
         FIG. 2  is a schematic sectional view of the present invention, illustrating the bottom frame bar extended out of the base frame. 
         FIG. 3  is a schematic sectional view of the present invention, illustrating the top frame bar extended out of the backrest. 
         FIG. 4  is a schematic sectional view of the present invention, illustrating the finger knobs of the first lock means pressed and the respective spring members compressed. 
         FIG. 5  is a schematic sectional view of the present invention, illustrating the bottom frame bar received in the base frame. 
         FIG. 6  is a schematic sectional view of the present invention, illustrating the top frame bar received in the backrest. 
         FIG. 7  is an elevational view of the present invention, illustrating the bottom frame bar received in the base frame and the top frame bar received in the backrest. 
         FIG. 8  is an elevational view of an alternate form of the present invention, illustrating safety lock pins used for the first and second lock means. 
         FIG. 9  is a schematic sectional view of the alternate form of the present invention, illustrating safety lock pins used for the first and second lock means. 
         FIG. 10  is another schematic sectional view of the alternate form of the present invention, illustrating safety lock pins used for the first and second lock means. 
         FIG. 11  is an elevational view of another alternate form of the present invention, illustrating safety lock pins used for the first and second lock means. 
         FIG. 12  is a schematic sectional view of the retractable frame structure shown in  FIG. 11 , illustrating safety lock pins used for the first and second lock means. 
         FIG. 13  is another schematic sectional view of the retractable frame structure shown in  FIG. 11 , illustrating safety lock pins used for the first and second lock means. 
         FIG. 14  is an elevational view of still another alternate form of the present invention, illustrating safety lock pins used for the first and second lock means. 
         FIG. 15  is a schematic sectional view of the retractable frame structure shown in  FIG. 14 , illustrating safety lock pins used for the first and second lock means. 
         FIG. 16  is another schematic sectional view of the retractable frame structure shown in  FIG. 14 , illustrating safety lock pins used for the first and second lock means. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to  FIGS. 1-7 , a retractable frame structure for baby trailer is shown. The retractable frame structure comprises: 
     a bottom frame bar  1  comprising opposing left and right frame bar portions  11 , a plurality of positioning holes  111  located in each of the left and right frame bar portions  11  and spaced along the length thereof (see  FIG. 2 ), a pivot holder  112  located at one of the left and right frame bar portions  11  for the connection of one end of a tow bar  9  that has an opposite end thereof connected to a bicycle (not shown); 
     a base frame  2  made of a rigid material and pivotally connected between two wheels  10 , comprising two sliding holes  21  arranged in parallel at opposing left and right sides thereof (see  FIG. 1 ,  FIG. 2 ,  FIG. 4  and  FIG. 5 ) for receiving the left and right frame bar portions  11  of the bottom frame bar  1  respectively in such a manner that the bottom frame bar  1  can be moved in and out of the sliding holes  21  of the base frame  2  between a received position and an extended position, and first lock means for locking the bottom frame bar  1  to the base frame  2 ; 
     a top frame bar  3  comprising opposing left and right frame bar portions  31 , a plurality of second positioning holes  311  located in each of the left and right frame bar portions  31  and spaced along the length thereof (see  FIG. 3 ); and 
     a backrest  4  made of a hard material and pivotally connected with a bottom side thereof to a rear side of the base frame  2  and turnable relative to the base frame  2  between a non-operative horizontal position and an operative vertical position, comprising two second sliding holes  41  arranged in parallel at opposing left and right sides thereof (see  FIG. 1 ,  FIG. 3  and  FIG. 6 ) for receiving the left and right frame bar portions  31  of the top frame bar  3  respectively in such a manner that the top frame bar  3  can be moved in and out of the second sliding holes  41  of the backrest  4  between a received position and an extended position, and second lock means for locking the top frame bar  3  to the backrest  4 . 
     The aforesaid first lock means comprises two lock pins  51  (see  FIG. 2 ,  FIG. 4  and  FIG. 5 ) having respective one ends  511  thereof respectively insertable through respective locating holes  20  in the base frame  2  (see  FIG. 2 ) into the positioning holes  111  of the opposing left and right frame bar portions  11  of the bottom frame bar  1  to lock the base frame  2  and the bottom frame bar  1  together. 
     Further, the lock pins  51  have respective opposite ends  512  thereof respectively connected with a respective finger knob  52  (see  FIG. 2 ,  FIG. 4  and  FIG. 5 ) that is movably mounted in a respective sliding groove  22  in the base frame  2  and supported on a respective spring member  53  in a respective spring hole  23  in the base frame  2 . When the user presses the finger knobs  52  against the respective spring members  53 , the lock pins  51  are moved inwardly toward each other to disengage their respective one ends  511  from the corresponding positioning holes  111  in the frame bar portions  11  of the bottom frame bar  1  (see  FIG. 4 ). When the user releases the fingers from the finger knobs  52 , the spring members  53  are released from the constraint to return the finger knobs  52 , moving the respective lock pins  51  outwardly away from each other, and thus the lock pins  51  are returned to the locking position. 
     The aforesaid second lock means comprises two lock pins  61  (see  FIG. 3  and  FIG. 6 ) having respective one ends  611  thereof respectively insertable through respective second locating holes  40  in the backrest  4  (see  FIG. 3  and  FIG. 6 ) into the second positioning holes  311  of the opposing left and right frame bar portions  31  of the top frame bar  3  to lock the backrest  4  and the top frame bar  3  together. 
     Further, the second lock pins  61  have respective opposite ends  612  thereof respectively connected with a respective second finger knob  62  (see  FIG. 3  and  FIG. 6 ) that is movably mounted in a respective second sliding groove  42  in the backrest  4  and supported on a respective second spring member  63  in a respective second spring hole  43  in the backrest  4 . When the user presses the second finger knobs  62  against the respective second spring members  63 , the second lock pins  61  are moved inwardly toward each other to disengage their respective one ends  611  from the corresponding second positioning holes  311  in the frame bar portions  31  of the top frame bar  3 . When the user releases the fingers from the second finger knobs  62 , the second spring members  63  are released from the constraint to return the second finger knobs  62 , moving the respective second lock pins  61  outwardly away from each other, and thus the second lock pins  61  are returned to the locking position. 
     Based on the composition of the aforesaid component parts, the user simply needs to press the two finger knobs  52  inwardly toward each other to compress the respective spring members  53 , forcing the two lock pins  51  to disengage their respective one ends  511  from the positioning holes  111  of the frame bar portions  11  of the bottom frame bar  1  (see  FIG. 4 ). At this time, the user can move the bottom frame bar  1  to force the frame bar portions  11  backwardly into the inside of the two sliding holes  21  of the base frame  2  (see  FIG. 5 ), and thus the bottom frame bar  1  is received in the base frame  2 . Similarly, the user can press the two second finger knobs  62  inwardly toward each other to compress the second spring member  63 , forcing the second lock pins  61  to disengage their respective one ends  611  from the second positioning holes  311  in the frame bar portion  31  of the top frame bar  3 . At this time, the user can move the top frame bar  3  to force the two frame bar portions  31  downwardly into the inside of the two sliding holes  41  of the backrest  4  (see  FIG. 6 ). Thus, the bottom frame bar  1  and the top frame bar  3  are respectively set in the received condition, saving further the space. Further, because the base frame  2  and the backrest  4  are pivotally connected together, the user can receive the base frame  2  and the backrest  4  in a stacked condition, saving storage space. When wishing to extend out of the retractable frame structure, the operation is also very convenient. At this time, directly pull the bottom frame  1  outward, enabling the two lock pins  51  to be forced by the respective spring members  53  into the positioning holes  111  in the two frame bar portions  11  of the bottom frame bar  1  (see  FIG. 2 ). Similarly, the user can directly upwardly pull the top frame bar  3 , enabling the two second lock pins  61  to be forced by the respective second spring members  63  into the second positioning holes  311  in the two frame bar portions  31  of the top frame bar  3  (see  FIG. 3 ). 
     Referring to  FIGS. 8-11 , in an alternate form of the present invention, the aforesaid first lock means comprises two first safety lock pins  54  respectively inserted through respective third locating holes  20 ′ in the base frame  2  (see  FIG. 9 ) into selected positioning holes  111  in the frame bar portions  11  of the bottom frame bar  1  to lock the base frame  2  and the bottom frame bar  1  together; the second lock means comprises two second safety lock pins  64  (see  FIG. 10 ) respectively inserted through respective fourth locating holes  40 ′ in the backrest  4  (see  FIG. 10 ) into selected second positioning holes  311  in the two frame bar portions  31  of the top frame bar  3  to lock the backrest  4  and the top frame bar  3  together. 
     Referring to  FIGS. 11-13 , in another alternate form of the present invention, the aforesaid first lock means comprises two spring pins  55  respectively mounted in the two frame bar portions  11  of the bottom frame bar  1  (see  FIG. 12 ). The spring pins  55  each comprise a protruding portion  551  normally engaged in a respective fifth locating hole  20 ″ in the base frame  2  to lock the bottom frame bar  1  and the base frame  2  together. When pressing the protruding portions  551  of the spring pins  55  in direction away from the respective fifth locating hole  20 ″ in the base frame  2 , the bottom frame bar  1  is unlocked from the base frame  2  and can be moved relative to the base frame  2 . Further, in this embodiment, the aforesaid second lock means also comprises two second spring pins  66  respectively mounted in the two frame bar portions  31  of the top frame bar  3  (see  FIG. 13 ). The second spring pins  66  each comprise a protruding portion  661  normally engaged in a respective sixth locating hole  40 ″ in the backrest  4  to lock the top frame bar  3  and the backrest  4  together. When pressing the protruding portions  661  of the second spring pins  66  in direction away from the respective sixth locating hole  40 ″ in the backrest  4 , the top frame bar  3  is unlocked from the backrest  4  and can be moved relative to the backrest  4 . 
     Referring to  FIGS. 14-16 , in still another alternate form of the present invention, the aforesaid first lock means comprises two screw bolts  57  and two screw nuts  58  (see  FIG. 15 ). The threaded shanks  571  of the screw bolts  57  are respectively inserted through respective seventh locating holes  20 ′″ in the two frame bar portions  11  of the bottom frame bar  1 , and then the two screw nuts  58  are respectively threaded onto the threaded shanks  571  of the screw bolts  57  to lock the bottom frame bar  1  and the base frame  2  together. When removed the screw nuts  58  from the respective screw bolts  57 , the bottom frame bar  1  is unlocked from the base frame  2  and can be moved relative to the base frame  2 . Further, in this embodiment, the aforesaid second lock means also comprises two second screw bolts  67  and two second screw nuts  68 . The threaded shanks  671  of the second screw bolts  67  are respectively inserted through respective eighth locating holes  40 ′″ in the backrest  4  and respective second positioning holes  311  in the two frame bar portions  31  of the top frame bar  3 , and then the second screw nuts  68  are respectively threaded onto the threaded shanks  671  of the second screw bolts  67  to lock the top frame bar  3  and the backrest  4  together. When removed the second screw nuts  68  from the respective second screw bolts  67 , the top frame bar  3  is unlocked from the backrest  4  and can be moved relative to the backrest  4 . 
     In conclusion, the invention provides a retractable frame structure for baby trailer, which has the advantages and features as follows:
     1. The base frame  2  is a rigid frame strong enough to bear the baby thereon and will not be deformed to strike against a large stone or other external objects when moving, assuring a high level of safety; the base frame  2  has sliding holes  21  in the front-back direction for receiving the two frame bar portions  11  of the bottom frame bar  1  between an extended operative position and a received non-operative position to reduce the storage space; the backrest  4  has sliding holes  41  for receiving the two frame bar portions  31  of the top frame bar  3  between an extended operative position and a received non-operative position to reduce the storage space; thus, the base frame  2  and the top frame bar  3  can be respectively moved relative to the bottom frame bar  1  and the backrest  4  between an extended operated position and a received non-operative position to reduce the storage space, saving the packaging and delivery costs of the baby trailer; further, the base frame  2  and the backrest  4  can be folded up to reduce the storage space, further saving the packaging and delivery costs of the baby trailer.   2. The user can press the two finger knob  52  to disengage the lock pins  51  from the positioning holes  111  in the two frame bar portions  11  of the bottom frame bar  1  and to let the two frame bar portions  11  of the bottom frame bar  1  be received in the base frame  2 ; in the same manner, the user can press the two second finger knob  62  to disengage the second lock pins  61  from the second positioning holes  311  in the frame bar portions  31  of the top frame bar  3  and to let the two frame bar portions  31  of the top frame bar  3  be received in the backrest  4 ; when wishing to extend out of the retractable frame structure of the baby trailer, the user can directly pull the bottom frame bar  1  outwardly from the received non-operative position to the extended position and directly pull the top frame bar  3  upwardly from the received non-operative position to the extended position.