Foldable seat frame

Abstract

A foldable seat frame includes a plurality of supporting bars and a plurality of crossing-bar pairs. Each crossing-bar pair is disposed between and pivotally connected to two adjacent supporting bars. Each crossing-bar pair includes first and second crossing bars pivotally coupled to each other at their middle portions. Each of the first and second crossing bars of one or more crossing-bar pairs includes a substantially flat surface for enhancing stability, enhancing ease of use and installation, improving durability, or reducing folded size of the foldable seat frame.

What is claimed is: 
     
         1 . A foldable seat frame comprising:
 a plurality of supporting bars comprising:
 a pair of front supporting bars disposed at a front side of the foldable seat frame when the foldable seat frame is unfolded, wherein each front supporting bar in the pair of front supporting bars has a first length adjustable between an expanded length and a contracted length; and 
 a pair of rear supporting bars disposed at a rear side of the foldable seat frame when the foldable seat frame is unfolded, wherein each rear supporting bar in the pair of rear supporting bars has a second length equal to or greater than the first length; 
   a plurality of lower connectors, each disposed at a lower end portion of a supporting bar in the plurality of supporting bars;   a plurality of upper connectors, each disposed at a supporting bar in the plurality of supporting bars above the lower end portion thereof, wherein the plurality of upper connectors comprises:
 a pair of front upper connectors, each disposed at an upper end portion of a front supporting bar in the pair of front supporting bars; and 
 a pair of rear upper connectors, each disposed at a rear supporting bar in the pair of rear supporting bars and movable along the rear supporting bar; and 
   a plurality of pairs of crossing bars, each comprising a first crossing bar and a second crossing bar pivotally coupled to each other at middle portions thereof and disposed between two adjacent supporting bars in the plurality of supporting bars, wherein:
 for each pair in the plurality of pairs of crossing bars, each of the first and second crossing bars has a lower end portion pivotally connected to the lower connector disposed at one of the two adjacent supporting bars and an upper end portion pivotally connected to the upper connector disposed at the other of the two adjacent supporting bars; and 
 for each of one or more pairs in the plurality of pairs of crossing bars, each of the first and second crossing bars has a substantially flat bar surface, and the substantially flat bar surfaces of the first and second crossing bars face each other, thereby enhancing stability, enhancing ease of use and installation, improving durability, or reducing folded size of the foldable seat frame. 
   
     
     
         2 . The foldable seat frame of  claim 1 , wherein:
 a first pair in the plurality of pairs of crossing bars is disposed between the pair of front supporting bars;   a first bar extension is connected to or integrally formed with the upper end portion of the first crossing bar of the first pair, the first bar extension extending upward, outward, or upward and outward beyond the upper connector disposed at a first front supporting bar in the pair of front supporting bars when the foldable seat frame is unfolded; and   a second bar extension is connected to or integrally formed with the upper end portion of the second crossing bar of the first pair, extending upward, outward, or upward and outward, beyond the upper connector disposed at a second front supporting bar in the pair of front supporting bars when the foldable seat frame is unfolded.   
     
     
         3 . The foldable seat frame of  claim 1 , wherein for each of the one or more pairs in the plurality of pairs of crossing bars, the substantially flat bar surface of each of the first and second crossing bars extends across substantially an entire length of the first or second crossing bar. 
     
     
         4 . The foldable seat frame of  claim 1 , wherein for each of the one or more pairs in the plurality of pairs of crossing bars, each of the first and second crossing bars has a substantially D-shaped cross section. 
     
     
         5 . The foldable seat frame of  claim 1 , wherein corresponding to each of the one or more pairs in the plurality of pairs of crossing bars:
 the lower connector disposed at a first supporting bar in the two adjacent supporting bars comprises a first lower connecting surface facing the substantially flat bar surface of the first crossing bar;   the lower connector disposed at a second supporting bar in the two adjacent supporting bars comprises a second lower connecting surface facing the substantially flat bar surface of the second crossing bar;   the upper connector disposed at the first supporting bar in the two adjacent supporting bars comprises a first upper connecting surface facing the substantially flat bar surface of the second crossing bar;   the upper connector disposed at the second supporting bar in the two adjacent supporting bars comprises a second upper connecting surface facing the substantially flat bar surface of the second crossing bar; and   each of the first lower connecting surface, the second lower connecting surface, the first upper connecting surface and the second upper connecting surface are substantially flat, thereby further enhancing stability, enhancing ease of use and installation, improving durability, or reducing folded size of the foldable seat frame.   
     
     
         6 . The foldable seat frame of  claim 1 , wherein the one or more pairs in the plurality of pairs of crossing bars comprise each of the plurality of pairs of crossing bars. 
     
     
         7 . The foldable seat frame of  claim 1 , wherein a respective lower connector in the plurality of lower connectors comprises:
 a first connecting member connected to the lower end portion of a corresponding supporting bar in the plurality of supporting bars;   a second connecting member pivotally connected to the lower end portion of a crossing bar in a pair of crossing bars that is disposed at a first side of the corresponding supporting bar; and   a third connecting member pivotally connected to the lower end portion of a crossing bar in another pair of crossing bars that is disposed at a second side of the corresponding supporting bar.   
     
     
         8 . The foldable seat frame of  claim 7 , wherein the first connecting member of the respective lower connector and the lower end portion of the corresponding supporting bar are connected to each other by snap-fitting or interference-fitting. 
     
     
         9 . The foldable seat frame of  claim 7 , wherein the first connecting member of the respective lower connector is in a form of a socket for receiving the lower end portion of the corresponding supporting bar. 
     
     
         10 . The foldable seat frame of  claim 9 , wherein a first coupling member is disposed in the socket and configured to couple with a second coupling member disposed at the lower end portion of the corresponding supporting bar. 
     
     
         11 . The foldable seat frame of  claim 7 , wherein the first connecting member of the respective lower connector and the lower end portion of the corresponding supporting bar have matching non-circular cross sections to prevent rotation of the respective lower connector relative to the corresponding supporting bar. 
     
     
         12 . The foldable seat frame of  claim 11 , wherein the matching non-circular cross sections are substantially D-shaped. 
     
     
         13 . The foldable seat frame of  claim 7 , wherein the respective lower connector further comprises a base member, wherein the first, second and third connecting members extend from the base member in a direction substantially perpendicular to the base member. 
     
     
         14 . A foldable seat frame comprising:
 a plurality of supporting bars;   a plurality of lower connectors, each disposed at a lower end portion of a supporting bar in the plurality of supporting bars;   a plurality of upper connectors, each disposed at a supporting bar in the plurality of supporting bars above a lower end portion thereof; and   a plurality of pairs of crossing bars, each comprising a first crossing bar and a second crossing bar pivotally coupled to each other at middle portions thereof and disposed between two adjacent supporting bars in the plurality of supporting bars,   wherein:   for each pair in the plurality of pairs of crossing bars, each of the first and second crossing bars has a lower end portion pivotally connected to the lower connector disposed at one of the two adjacent supporting bars and an upper end portion pivotally connected to the upper connector disposed at the other of the two adjacent supporting bars;   for each of one or more pairs in the plurality of pairs of crossing bars, each of the first and second crossing bars has a substantially flat bar surface, and the substantially flat bar surfaces of the first and second crossing bars face each other, thereby enhancing stability, enhancing ease of use and installation, improving durability, or reducing folded size of the foldable seat frame; and   corresponding to each of the one or more pairs in the plurality of pairs of crossing bars:
 the lower connector disposed at a first supporting bar in the two adjacent supporting bars comprises a first lower connecting surface facing the substantially flat bar surface of the first crossing bar; 
 the lower connector disposed at a second supporting bar in the two adjacent supporting bars comprises a second lower connecting surface facing the substantially flat bar surface of the second crossing bar; 
 the upper connector disposed at the first supporting bar in the two adjacent supporting bars comprises a first upper connecting surface facing the substantially flat bar surface of the second crossing bar; 
 the upper connector disposed at the second supporting bar in the two adjacent supporting bars comprises a second upper connecting surface facing the substantially flat bar surface of the second crossing bar; and 
 each of the first lower connecting surface, the second lower connecting surface, the first upper connecting surface and the second upper connecting surface are substantially flat, thereby further enhancing stability, enhancing ease of use and installation, improving durability, or reducing folded size of the foldable seat frame. 
   
     
     
         15 . The foldable seat frame of  claim 14 , wherein for each of the one or more pairs in the plurality of pairs of crossing bars, the substantially flat bar surface of each of the first and second crossing bars extends across substantially an entire length of the first or second crossing bar. 
     
     
         16 . The foldable seat frame of  claim 14 , wherein for each of the one or more pairs in the plurality of pairs of crossing bars, each of the first and second crossing bars has a substantially D-shaped cross section. 
     
     
         17 . The foldable seat frame of  claim 14 , wherein the one or more pairs in the plurality of pairs of crossing bars comprise each of the plurality of pairs of crossing bars. 
     
     
         18 . The foldable seat frame of  claim 14 , wherein:
 the plurality of supporting bars comprises two front supporting bars and two rear supporting bars;   the plurality of pairs of crossing bars comprises four pairs; and   when the foldable seat frame is unfolded, the two front supporting bars are disposed at a front side of the foldable seat frame and the two rear supporting bars are disposed at a rear side of the foldable seat frame.   
     
     
         19 . The foldable seat frame of  claim 14 , wherein:
 the plurality of supporting bars comprises three front supporting bars and three rear supporting bars;   the plurality of pairs of crossing bars comprises seven pairs; and   when the foldable seat frame is unfolded, the three front supporting bars are disposed at a front side of the foldable seat frame and the three rear supporting bars are disposed at a rear side of the foldable seat frame.   
     
     
         20 . The foldable seat frame of  claim 14 , wherein:
 the plurality of supporting bars comprises four front supporting bars and four rear supporting bars;   the plurality of pairs of crossing bars comprises ten pairs; and   when the foldable seat frame is unfolded, the four front supporting bars are disposed at a front side of the foldable seat frame and the four rear supporting bars are disposed at a rear side of the foldable seat frame.