Patent ID: 6896275

Claim:
A folding collapsible frame structure for baby trailer comprising: a bottom frame unit, said bottom frame unit comprising two wheel holders provided at two opposite lateral sides thereof and carrying a respective wheel, a transverse front bar disposed at a front side thereof, said transverse front bar having a middle section curved downwards, a bottom U-lug affixed to one lateral side thereof at a bottom side adjacent to said transverse front bar, said bottom U-lug comprising two parallel sidewalls, said parallel sidewalls each having a first locating notch and a second locating notch near two distal ends thereof, said first locating notch and said second locating notch each having a retaining portion; two upright side frames respectively formed of a substantially arch-shaped frame bar, said upright side frames each having two bottom ends respectively pivoted to said bottom frame unit and a top side respectively fixedly mounted with a female coupling member, said female coupling member comprising a coupling hole and two retaining holes in communication with said coupling hole at two sides; a transverse top bar detachably connected between said upright side frames, said transverse top bar having two male coupling members respectively located on two distal ends thereof and detachably coupled to the female coupling members of said upright side frames, said male coupling members each comprising a coupling block respectively coupled to the coupling holes of the female coupling members at said upright side frames, said coupling block having two hooked portions for hooking in the retaining holes of the corresponding female coupling member; a pivot bolt transversely fastened to the parallel sidewalls of said bottom U-lug; a trailer bar pivoted to said pivot bolt at said bottom U-lug of said bottom frame unit and selectively locked between an extended position and a received position, said trailer bar having a rear end pivoted to a channel in said bottom U-lug at one side bar of said bottom frame and a front end connectable to a vehicle, a rear end inserted into said bottom U-lug and pivoted to said pivot bolt between the two parallel sidewalls of said bottom U-lug, and a longitudinal sliding slot formed in said rear end adjacent to said pivot bolt; a locking member slidably coupled to said longitudinal sliding slot for selectively engaging in the first locating notches or second locating notches of said bottom U-lug to lock said trailer bar between said extended position and said received position; and a spring member mounted inside said trailer bar and partially suspended in said longitudinal sliding slot and stopped against said locking member to push said locking member toward one end of said longitudinal sliding slot for forcing said locking member is into engagement with the respective retaining portions when said locking member pushed into the first locating notches or second locating notches of said bottom U-lug by the user.