Foldable Stroller Frame

Abstract

A foldable stroller frame includes a connection unit interconnecting two opposite foldable side frame units, each of which includes a front leg and a handle rod connected pivotally to each other, and a rear leg connected pivotally to the handle rod. The connection unit includes four bottom rods each having a first end connected pivotally to a connecting seat, and a second end connected pivotally to a respective one of the front and rear legs of the side frame units. When the connecting seat is pulled upwardly from a lower used position, the second ends of the bottom rods move radially toward each other, whereby the side frame units are folded and move toward each other.

What is claimed is: 
     
         1 . A foldable stroller frame comprising:
 two opposite foldable side frame units spaced apart from each other in a widthwise direction of said stroller frame, each of said side frame units including
 a front leg, 
 a handle rod having a pivot end that is connected pivotally to said front leg, and a handle end that is opposite to said pivot end, and 
 a rear leg having an upper end that is connected pivotally to said handle rod; and 
   a foldable connection unit interconnecting said side frame units and including
 a connecting seat, and 
 two hollow front bottom rods and two hollow rear bottom rods arranged radially around said connecting seat, each of said front and rear bottom rods having a first end that extends into and is connected pivotally to said connecting seat, and a second end that is opposite to said first end, said second end of each of said front bottom rods being connected pivotally to said front leg of a respective one of said side frame units, said second end of each of said rear bottom rods being connected pivotally to said rear leg of a respective one of said side frame units; 
   wherein, to unfold said stroller frame, said connecting seat is pushed downwardly to a used position so as to drive said second ends of said front and rear bottom rods to move radially away from each other such that said side frame units are driven by said front and rear bottom rods to move away from each other in the widthwise direction, such that said front leg and said handle rod of each of said side frame units pivot away from each other and such that said rear leg and said handle rod of each of said side frame units pivot away from each other; and   wherein, to fold said stroller frame, said connecting seat is pulled upwardly from the used position so as to drive said second ends of said front and rear bottom rods to move radially toward each other such that said side frame units are driven by said front and rear bottom rods to move toward each other in the widthwise direction, such that said front leg and said handle rod of each of said side frame units pivot toward each other and such that said rear leg and said handle rod of each of said side frame units pivot toward each other.   
     
     
         2 . The foldable stroller frame as claimed in  claim 1 , wherein each of said side frame units further includes a connecting rod that has opposite upper and lower ends connected pivotally and respectively to said front and rear legs. 
     
     
         3 . The foldable stroller frame as claimed in  claim 2 , wherein said connection unit further includes:
 two front joint pieces each for pivotally jointing together said second end of a respective one of said front bottom rods to said front leg of a respective one of said side frame units; and   two rear joint pieces each for pivotally jointing said second end of a respective one of said rear bottom rods and said lower end of said connecting rod of a respective one of said side frame units to said rear leg of the respective one of said side frame units.   
     
     
         4 . The foldable stroller frame as claimed in  claim 3 , wherein:
 each of said front and rear joint pieces includes a first pivot plate portion, and a second pivot plate portion extending from a lateral end of said first pivot plate portion;   for each of said front joint pieces, said first pivot plate portion is pivoted to said front leg of the respective one of said side frame units, and said second pivot plate portion is pivoted to said second end of the respective one of said front bottom rods; and   for each of said rear joint pieces, said first pivot plate portion and said lower end of said connecting rod of the respective one of said side frame units are pivoted to said rear leg of the respective one of said side frame units, and said second pivot plate portion is pivoted to said second end of the respective one of said rear bottom rods.   
     
     
         5 . The foldable stroller frame as claimed in  claim 4 , wherein:
 each of said front and rear joint pieces further includes a base plate portion extending horizontally from the bottom of said second pivot plate portion; and   when said stroller frame is fully unfolded, said base plate portion of each of said front joint pieces is configured to support the respective one of said front bottom rods, and said base plate portion of each of said rear joint pieces is configured to support the respective one of said rear bottom rods thereon.   
     
     
         6 . The foldable stroller frame as claimed in  claim 5 , wherein, for each of said front and rear jointing pieces, an obtuse angle is formed between said first and second pivot plate portions, and said second pivot plate portion is perpendicular to said base plate portion. 
     
     
         7 . The foldable stroller frame as claimed in  claim 1 , further comprising a foldable rear rod assembly that interconnects said rear legs of said side frame units, said rear rod assembly having opposite upper and lower sides, at least one of which is connected slidably to said rear legs of said side frame units. 
     
     
         8 . The foldable stroller frame as claimed in  claim 7 , wherein said rear rod assembly includes two rear rods that are pivoted to and cross each other, each of said rear rods having opposite upper and lower ends that are connected pivotally and respectively to said rear legs of said side frame units, said upper ends of said rear rods constituting said upper side of said rear rod assembly, said lower ends of said rear rods constituting said lower side of said rear rod assembly. 
     
     
         9 . The foldable stroller frame as claimed in  claim 8 , wherein:
 each of said side frame units further includes at least one joint seat that is provided slidably on said rear leg and that has a pivot portion; and   said upper ends or said lower ends of said rear rods are pivoted respectively to said pivot portions of said joint seats of said side frame units.   
     
     
         10 . The foldable stroller frame as claimed in  claim 8 , wherein:
 each of said side frame units further includes a lower joint seat and an upper joint seat provided on said rear leg in a manner that said upper joint seat is disposed above said lower joint seat;   for each of said side frame units, each of said lower and upper joint seats has a pivot portion, and at least one of said lower and upper joint seats is slidable along said rear leg; and   for said rear rod assembly, said upper ends of said rear rods are pivoted respectively to said pivot portions of said upper joint seats of said side frame units, and said lower ends of said rear rods are pivoted respectively to said pivot portions of said lower joint seats.   
     
     
         11 . The foldable stroller frame as claimed in  claim 10 , wherein, for each of said side frame units, said lower joint seat is sleeved fixedly on a lower end of said rear leg, and said upper joint seat is sleeved slidably on said rear leg. 
     
     
         12 . The foldable stroller frame as claimed in  claim 1 , wherein, for each of said side frame units:
 said front leg has a first pivot piece provided on an upper end thereof, said first pivot piece being configured with a receiving space and having a tongue that extends into said receiving space;   said handle rod has a second pivot piece provided on said pivot end thereof and pivoted to said first pivot piece, said second pivot piece being formed with a slot; and   to unfold said stroller frame, said second pivot piece pivots with respect to said first pivot piece so as to come into said receiving space until said tongue of said first pivot piece is fully inserted into and restricted in said slot in said second pivot piece.   
     
     
         13 . The foldable stroller frame as claimed in  claim 1 , wherein:
 said connecting seat of said connection unit has a plurality of spaced apart and radially extending insertion grooves that are formed in an outer surrounding side thereof and that are arranged in a centrally symmetric manner, each of said insertion grooves having an open bottom side; and   when said stroller frame is fully unfolded, said first end of each of said front and rear bottom rods extends into and is restricted in a corresponding one of said insertion grooves.   
     
     
         14 . The foldable stroller frame as claimed in  claim 13 , wherein:
 said connecting seat of said connection unit further has a plurality of openings that are formed in a top surface thereof and that are in spatial communication with said insertion grooves, respectively; and   to fold said stroller frame, said first end of each of said front and rear bottom rods moves partially away from the corresponding one of said insertion grooves of said connecting seat through said open bottom side of the corresponding one of said insertion grooves of said connecting seat, and is permitted to extend partially into a corresponding one of said openings of said connecting seat.   
     
     
         15 . The foldable stroller frame as claimed in  claim 13 , wherein:
 said connecting seat further has a central recess that is formed in a top side thereof and that is in spatial communication with said insertion grooves, and two opposite partition walls that are provided in said central recess to define, within said central recess, an accommodating space therebetween, said accommodating space being in spatial communication with two corresponding ones of said insertion grooves that are opposite to each other in a first direction;   one of said front bottom rods and one of said rear bottom rods that extend respectively into said two corresponding ones of said insertion grooves each have a spring-loaded plug that is provided in said first end thereof and that is movable between a normally projecting position and a retracted position;   said connection unit further includes a lock mechanism that is disposed in said accommodating space in said connecting seat; and   when said stroller frame is fully unfolded, said lock mechanism is operable in one of a locking state, where said spring-loaded plug of each of said one of said front bottom rods and said one of said rear bottom rods is at the projecting position and is engaged with said lock mechanism such that said first ends of said one of said front bottom rods and said one of said rear bottom rods are locked in said connecting seat, and an unlocking state, where said spring-loaded plug of each of said one of said front bottom rods and said one of said rear bottom rods is urged by said lock mechanism to move from the projecting position to the retracted position, thereby disengaging from said lock mechanism such that each of said one of said front bottom rods and said one of said rear bottom rods is able to pivot with respect to said connecting seat.   
     
     
         16 . The foldable stroller frame as claimed in  claim 15 , wherein said lock mechanism includes:
 a hollow locking seat fixed to said partition walls, said locking seat engaging said spring-loaded plug of each of said one of said front bottom rods and said one of said rear bottom rods at the projecting position when said stroller frame is fully unfolded while said lock mechanism is in the locking state; and   an unlocking member disposed in and connected movably to said locking seat for driving said springing-loaded plug of each of said one of said front bottom rods and said one of said rear bottom rods to move from the projecting position to the retracted position when said stroller frame is fully unfolded while said lock mechanism is in the unlocking state.   
     
     
         17 . The foldable stroller frame as claimed in  claim 16 , wherein:
 said locking seat has
 two upright plate portions that are opposite to each other in a second direction perpendicular to the first direction and that are connected respectively to said partition walls, each of said plate portions having a central slot that extends vertically and downwardly from a top side thereof, and two inclined guide grooves that are symmetric with respect to and inclined downwardly toward said central slot, and 
 two opposite top blocks that are connected integrally between said top sides of said plate portions and that are spaced apart from each other in the first direction, said spring-loaded plug of each of said one of said front bottom rods and said one of said rear bottom rods abutting against a bottom side of a respective one of said top blocks when said stroller frame is fully unfolded and when said lock mechanism is in the locking state; 
   said unlocking member includes two inverted U-shaped arms that are pivoted to each other through a first pivot bolt, which passes through and engages slidably said central slots of said plate portions of said locking seat, each of said arms having an intermediate arm section pivoted to a respective second pivot bolt that passes through and engages slidably a respective one of said guide grooves in each of said plate portions of said locking seat, said unlocking member being movable along said central slots of said locking seat between a lower limit position and an upper limit position; and   when said unlocking member moves from the lower limit position to the upper limit position, said intermediate arm sections of said arms are guided by said inclined guide grooves of said locking seat to move away from each other such that said spring-loaded plug of each of said one of said front bottom rods and said one of said rear bottom rods is pushed by said intermediate arm section of a respective one of said arms to move to the retracted position.   
     
     
         18 . The foldable stroller frame as claimed in  claim 17 , wherein said lock mechanism further includes an operation piece that is connected to said first pivot bolt and that has an operating end that is exposed out of said connecting seat and that is manually operable to move said unlocking member to the upper limit position. 
     
     
         19 . The foldable stroller frame as claimed in  claim 1 , wherein said connecting seat has a flat top surface, which is substantially horizontal when said stroller frame is fully unfolded.