Abstract:
A foldable frame includes two tubes, a rectangular tube and two base parts. The two tubes are pivotably or fixedly connected to the base parts. Two ends of the rectangular tube are connected to two respective extension portions of the two base parts by two pins so that the two tubes are pivotable about the two pins. The frame can also be structured as one tube directly connected to the rectangular tube and the other tube is pivotably connected to the base part. The extension of the base part is pivotably connected of the rectangular tube by a pin to form single-point folding feature. An outer tube is rotatably movable between one of the tubes and the rectangular tube, the outer tube hides the rectangular tube when the two tubes are arranged linearly.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to a frame, and more particularly, to a foldable frame which can be folded easily. 
       BACKGROUND OF THE INVENTION 
       [0002]    A conventional stretcher, recliner or even desk may include folding mechanisms in order to fold the article to a small size which is convenient for transportation and storage purposes. There are some shortcomings for the conventional foldable articles, the first one is that the conventional folding mechanism is composed of multiple tubes of different diameters so that the smaller tubes can be received in the tubes of larger diameters to form the folded status. However, before the tubes are organized and connected to each other, they occupy space and can be easily lost one of the tubes. Once one tube is lost, the rest of the tubes cannot be connected to each other. The second shortcoming is that there is a lack of pivoting mechanism to further reduce the space that the folded status occupies. Even if there is a pivoting mechanism available, the conventional pivoting mechanism includes complicated structure. 
         [0003]    The present invention intends to provide a foldable frame that includes at least one single-point folding unit and at least one two-point folding unit, and an outer tube is used to hide the folding unit when the two tubes are aligned to each other. 
       SUMMARY OF THE INVENTION 
       [0004]    The present invention relates to a foldable frame and includes two tubes, a rectangular tube and two base parts. The two tubes are pivotably or fixedly connected to the base parts. Two ends of the rectangular tube are connected two respective extension portions of the two base parts by two pins so that the two tubes are pivotable about the two pins. The frame can also be structured as one tube directly connected to the rectangular tube and the other tube is pivotably connected to the base part. The extension portion of the base part is pivotably connected to the rectangular tube by a pin to form single-point folding feature. An outer tube is rotatably movable between one of the tubes and the rectangular tube, the outer tube hides the rectangular tube when the two tubes are arranged linearly. The foldable frame can be used for stretchers, recliners, foldable bicycles, crutches, or desks. 
         [0005]    The present invention will become more obvious from the following description when taken in connection with the accompanying drawings which show, for purposes of illustration only, a preferred embodiment in accordance with the present invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]      FIG. 1  is a partly cross sectional view to show the first embodiment of the foldable frame of the present invention; 
           [0007]      FIG. 2  is a plane view to show the first embodiment of the foldable frame of the present invention; 
           [0008]      FIG. 3  is a partly cross sectional view to show the second embodiment of the foldable frame of the present invention; 
           [0009]      FIG. 4  is a plane view to show the second embodiment of the foldable frame of the present invention; 
           [0010]      FIG. 5  shows that the foldable frame of the present invention is applied to the frame of a stretcher; 
           [0011]      FIG. 6  shows the stretcher that the foldable frame of the present invention is applied to; 
           [0012]      FIG. 7  shows that the stretcher is folded by operation of the foldable frame of the present invention; 
           [0013]      FIG. 8  shows the recliner that the foldable frame of the present invention is applied to; 
           [0014]      FIG. 9  shows that the recliner is folded by operation of the foldable frame of the present invention; 
           [0015]      FIG. 10  shows the desk that the foldable frame of the present invention is applied to; 
           [0016]      FIG. 11  shows that the desk is folded by operation of the foldable frame of the present invention; 
           [0017]      FIG. 12  shows the bicycle that the foldable frame of the present invention is applied to; 
           [0018]      FIG. 13  shows that the bicycle is folded by operation of the foldable frame of the present invention; 
           [0019]      FIG. 14  shows the crutch that the foldable frame of the present invention is applied to; 
           [0020]      FIG. 15  shows that the crutch is folded by operation of the foldable frame of the present invention; 
           [0021]      FIG. 16   a  shows a cross sectional view of the rectangular tube of the foldable frame of the present invention; 
           [0022]      FIG. 16   b  shows another cross sectional view of the rectangular tube of the foldable frame of the present invention; 
           [0023]      FIG. 17  is a partial cross sectional view to show the user of a connector between the base part and the tube. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0024]    Referring to  FIGS. 1 and 2 , the foldable frame of the present invention comprises a first tube  11 , a second tube  12 , a rectangular tube  21  and at least one base part  30 , wherein the second tube  12  is connected to a first end of the rectangular tube  21  and a second end of the rectangular tube  21  is pivotably connected to an extension portion  31  of the at least one base part  30  by a pin  32 . Therefore, the first tube  11  is pivotable about the pin  32  to form the single-point folding unit  50 . An outer tube  40  is movable between the second tube  12  and the rectangular tube  21 , and a securing bolt  41  secures the outer tube  40  when the outer tube  40  is moved to a desired position. 
         [0025]    Referring to  FIGS. 3 and 4 , which show the two-point folding unit  60  of the present invention and includes a first tube  11   a , a second tube  12   a , a rectangular tube  21   a  and two base parts  30   a ,  30   b . The first and second tubes  11   a ,  12   a  are pivotably or fixedly connected to the two base parts  30   a ,  30   b  by two pins  32   a , so that the first and second tubes  11   a ,  12   a  are pivotable about the two pins  32   a  to form the two-point folding unit  60 . An outer tube  40   a  is movable between the second tube  12   a  and the rectangular tube  21   a , an inner diameter of the outer tube  40   a  is the same length as the length of two rod  91 ,  92  connected to the rectangular tube  21   a  vertically. The outer tube  40   a  can be connected to the first and second tubes  11   a ,  12   a  and is reinforced when connected between the first and second tubes  11   a ,  12   a . The rectangular tube  21   a  is rotatable so as to change the folding direction. 
         [0026]      FIGS. 5 to 7  show a stretcher which comprises two two-point folding units  60 , four single-point folding units  50 , two links  70  and a fabric sheet  71 . The two two-point folding units  60  form the two side rails of the stretcher and the two links  70  are connected between the two side rails. The fabric sheet  71  is mounted to the two side rails and the two links  70 . The four single-point folding units  50  are connected to two respective undersides of the two side rails to function as four legs of the stretcher. 
         [0027]    The two-point folding unit  60  includes a first tube  11   a , a second tube  12   a , a rectangular tube  21   a  and two base parts  30   a ,  30   b . The first and second tubes  11   a ,  12   a  are pivotably or fixedly connected to the two base parts  30   a ,  30   b  by two pins  32   a , so that the first and second tubes  11   a ,  12   a  are pivotable about the two pins  32   a  to form the two-point folding unit  60 . The rectangular tube  21   a  has two ends thereof pivotably connected to two respective extension portions  31   a ,  31   b  of the two base parts  30   a ,  30   b  by two pins  32   a  as shown in  FIGS. 3 and 4 . An outer tube  40   a  is movable between the second tube  12   a  and the rectangular tube  21   a.    
         [0028]    The single folding unit  50  as shown in  FIGS. 1 and 2  comprises a first tube  11 , a second tube  12 , a rectangular tube  21  and at least one base part  30 , wherein the second tube  12  is connected to a first end of the rectangular tube  21  and a second end of the rectangular tube  21  is pivotably connected to an extension portion  31  of the at least one base part  30  by a pin  32 . Therefore, the first tube  11  is pivotable about the pin  32  to form the single-point folding unit  50 . An outer tube  40  is movable between the second tube  12  and the rectangular tube  21 , and a securing bolt  41  secures the outer tube  40  when the outer tube  40  is moved to a desired position. 
         [0029]      FIGS. 8 and 9  show a recliner using the foldable frame of the present invention and the recliner comprises four two-point folding units  60 , four single-point folding units  50  and a pad  72 . The four two-point folding units  60  form a rectangular frame and the pad  72  is mounted onto the rectangular frame. The four single-point folding units  50  are connected to an underside of the rectangular frame. 
         [0030]    The two-point folding unit  60  as shown in  FIGS. 3 and 4  includes a first tube  11   a , a second tube  12   a , a rectangular tube  21   a  and two base parts  30   a ,  30   b . The first and second tubes  11   a ,  12   a  are pivotably or fixedly connected to the two base parts  30   a ,  30   b  by two pins  32   a , so that the first and second tubes  11   a ,  12   a  are pivotable about the two pins  32   a  to form the two-point folding unit  60 . The rectangular tube  21   a  has two ends thereof pivotably connected to two respective extension portions  31   a ,  31   b  of the two base parts  30   a ,  30   b  by two pins  32   a  as shown in  FIGS. 3 and 4 . An outer tube  40   a  is movable between the second tube  12   a  and the rectangular tube  21   a.    
         [0031]    The single folding unit  50  as shown in  FIGS. 1 and 2  comprises a first tube  11 , a second tube  12 , a rectangular tube  21  and at least one base part  30 , wherein the second tube  12  is connected to a first end of the rectangular tube  21  and a second end of the rectangular tube  21  is pivotably connected to an extension portion  31  of the at least one base part  30  by a pin  32 . Therefore, the first tube  11  is pivotable about the pin  32  to form the single-point folding unit  50 . An outer tube  40  is movable between the second tube  12  and the rectangular tube  21 , and a securing bolt  41  secures the outer tube  40  when the outer tube  40  is moved to a desired position. 
         [0032]      FIGS. 10 and 11  show the desk using the foldable frame of the present invention and comprises at least four two-point folding units  60 , at least four single-point folding units  50  and a desk top  73 . The at least four two-point folding units  60  form a rectangular frame and the desk top  73  is mounted onto the rectangular frame. The at least four single-point folding units  50  are connected to an underside of the rectangular frame so as to form the four legs of the desk. 
         [0033]    The two-point folding unit  60  as shown in  FIGS. 3 and 4  includes a first tube  11   a , a second tube  12   a , a rectangular tube  21   a  and two base parts  30   a ,  30   b . The first and second tubes  11   a ,  12   a  are pivotably or fixedly connected to the two base parts  30   a ,  30   b  by two pins  32   a , so that the first and second tubes  11   a ,  12   a  are pivotable about the two pins  32   a  to form the two-point folding unit  60 . The rectangular tube  21   a  has two ends thereof pivotably connected to two respective extension portions  31   a ,  31   b  of the two base parts  30   a ,  30   b  by two pins  32   a  as shown in  FIGS. 3 and 4 . An outer tube  40   a  is movable between the second tube  12   a  and the rectangular tube  21   a.    
         [0034]    The single folding unit  50  as shown in  FIGS. 1 and 2  comprises a first tube  11 , a second tube  12 , a rectangular tube  21  and at least one base part  30 , wherein the second tube  12  is connected to a first end of the rectangular tube  21  and a second end of the rectangular tube  21  is pivotably connected to an extension portion  31  of the at least one base part  30  by a pin  32 . Therefore, the first tube  11  is pivotable about the pin  32  to form the single-point folding unit  50 . An outer tube  40  is movable between the second tube  12  and the rectangular tube  21 , and a securing bolt  41  secures the outer tube  40  when the outer tube  40  is moved to a desired position. 
         [0035]      FIGS. 12 and 13  show that the foldable frame is used on a foldable bicycle and includes at least two two-point folding units  60 , wherein the two-point folding unit  60  as shown in  FIGS. 3 and 4  includes a first tube  11   a , a second tube  12   a , a rectangular tube  21   a  and two base parts  30   a ,  30   b . The first and second tubes  11   a ,  12   a  are pivotably or fixedly connected to the two base parts  30   a ,  30   b  by two pins  32   a , so that the first and second tubes  11   a ,  12   a  are pivotable about the two pins  32   a  to forth the two-point folding unit  60 . The rectangular tube  21   a  has two ends thereof pivotably connected to two respective extension portions  31   a ,  31   b  of the two base parts  30   a ,  30   b  by two pins  32   a  as shown in  FIGS. 3 and 4 . An outer tube  40   a  is movable between the second tube  12   a  and the rectangular tube  21   a.    
         [0036]      FIGS. 14 and 15  show that the foldable frame is used on a crutch and comprises at least one two-point folding unit  60 . The two-point folding unit  60  as shown in  FIGS. 3 and 4  includes a first tube  11   a , a second tube  12   a , a rectangular tube  21   a  and two base parts  30   a ,  30   b . The first and second tubes  11   a ,  12   a  are pivotably or fixedly connected to the two base parts  30   a ,  30   b  by two pins  32   a , so that the first and second tubes  11   a ,  12   a  are pivotable about the two pins  32   a  to form the two-point folding unit  60 . The rectangular tube  21   a  has two ends thereof pivotably connected to two respective extension portions  31   a ,  31   b  of the two base parts  30   a ,  30   b  by two pins  32   a  as shown in  FIGS. 3 and 4 . An outer tube  40   a  is movable between the second tube  12   a  and the rectangular tube  21   a.    
         [0037]    It is noted that the each of the first and second tubes  11 ,  11   a ,  12 ,  12   a  and the outer tubes  40 ,  40   a  has a collar mounted to each end  93  thereof so as to avoid the user being injured by the sharp edges and reinforce the structural strength of the tubes. 
         [0038]    The outer tubes  40 ,  40   a  can be different shapes such as oval tubes, elongate tubes, and triangular tubes. 
         [0039]      FIGS. 16   a  and  16   b  show that the rectangular tube  21  includes three walls and an open side, or the rectangular tube  21  includes two flanges extending inward from two parallel sides walls of the rectangular tube  21 . 
         [0040]      FIG. 17  shows that the base part  30 ,  30   a  is connected to the connector  80  first and the connector  80  is connected to the first tube  11 ,  11   a.    
         [0041]    While we have shown and described the embodiment in accordance with the present invention, 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.