Abstract:
A pitman-style foldable frame structure has an innovative and unique assembled design. The frame structure includes foldable panels, a central spindle, lateral frames, oblique connecting rods, a control device, and a central connecting frame. The frame structure offers improvement over the prior art in lowering the material cost and increasing structural support strength and rigidity of the pitman-style foldable frame and achieves practical advancement and better industrial utilization effect.

Description:
CROSS-REFERENCE TO RELATED U.S. APPLICATIONS 
       [0001]    Not applicable. 
       STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    Not applicable. 
       NAMES OF PARTIES TO A JOINT RESEARCH AGREEMENT 
       [0003]    Not applicable. 
       REFERENCE TO AN APPENDIX SUBMITTED ON COMPACT DISC 
       [0004]    Not applicable. 
       BACKGROUND OF THE INVENTION 
       [0005]    1. Field of the Invention 
         [0006]    The present invention relates generally to a foldable frame, and more particularly to an innovative design of a pitman-style foldable frame. 
         [0007]    2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98. 
         [0008]    Foldable frames are widely used in products like chairs, tables, sleds, etc, so that the products can be folded to a smaller overall size to save storage space when they are not used. 
         [0009]    In the structural design of prior-art foldable frames, it is common to use cross connecting rods for folding and moving. However, in actual applications, it is found that such a structural design has the disadvantage of high material cost because the length of each cross connecting rod has to be considerably longer than half of the length of the foldable frame area. Moreover, the longer the cross connecting rods are, there will be more deformation and less support in the middle section of the rods, causing problems and disadvantages of insufficient support strength and lower rigidity. 
         [0010]    Thus, to overcome the aforementioned problems of the prior art, it would be an advancement if the art to provide an improved structure that can significantly improve the efficacy. 
         [0011]    Therefore, the inventor has provided the present invention of practicability after deliberate design and evaluation based on years of experience in the production, development and design of related products. 
       BRIEF SUMMARY OF THE INVENTION 
       [0012]    The facts of efficacy advancement of the present invention are as follows: 
         [0013]    The pitman-style foldable frame structure of the present invention offers an innovative and unique assembled design mainly through said foldable panels, a central spindle, lateral frames, oblique connecting rods, a control device, and a central connecting frame, so that the present invention can improve the structure known from prior art in lowering the material cost and increasing structural support strength and rigidity of the pitman-style foldable frame and achieve practical advancement and better industrial utilization effect. 
         [0014]    Although the invention has been explained in relation to its preferred embodiment, it is to be understood that many other possible modifications and variations can be made without departing from the spirit and scope of the invention as hereinafter claimed. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0015]      FIG. 1  is an assembled perspective view of a preferred embodiment of the structure of the present invention. 
           [0016]      FIG. 2  is an exploded perspective view of a preferred embodiment of the structure of the present invention. 
           [0017]      FIG. 3  is an assembled elevation of a preferred embodiment of the structure of the present invention. 
           [0018]      FIG. 4  is an exploded and enlarged perspective view of part of the components of the present invention. 
           [0019]      FIG. 5  is a sectional view of the pin-joint part between the lateral frames and the first and second panels of the present invention. 
           [0020]      FIG. 6  is a sectional view of the pin-joint part between the lateral frames and the oblique connecting rods of the present invention. 
           [0021]      FIG. 7  is a schematic view of the action shift states of the control device of the present invention. 
           [0022]      FIG. 8  is a schematic view of the folded state of the pitman-style foldable frame of the present invention. 
           [0023]      FIG. 9  depicts an example of the pitman-style foldable frame of the present invention implemented in a sled. 
           [0024]      FIG. 10  depicts an example of the pitman-style foldable frame of the present invention implemented in a chair. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0025]      FIGS. 1 ,  2 ,  3  and  4  depict a preferred embodiment of the pitman-style foldable frame structure of the present invention. However, it is to be understood that such an embodiment is illustrative only and is not intending to limit the scope of the invention in any manner. 
         [0026]    Said pitman-style foldable frame structure has a foldable panel  10 , including a first panel  11  and a second panel  12 , wherein the relative inside ends of the first panel  11  and second panel  12  have contacting surfaces  110 ,  120  to contact against each other when the first and second panels  11 ,  12  are unfolded. On the lower sides of the contacting surfaces of the first and second panels  11 ,  12 , pin connecting ears  13 ,  14  with inter-aligned and inter-communicating spindle holes  130 ,  140  are configured. The relative outside ends of the first panel  11  and second panel  12  are configured with a frame pin connecting part  15 . 
         [0027]    A central spindle  20  goes through the spindle holes  130 ,  140  in the pin connecting ears  13 ,  14  configured on the first and second panels  11 ,  12  of the foldable panel  10 , to form a revolving spindle when the first and second panels  11 ,  12  of the foldable panel  10  are folded. 
         [0028]    Two lateral frames  30  are attached to the relative outside ends of the first and second panels  11 ,  12  of the foldable panel  10 . Each lateral frame  30  has a pin connecting end  31  and a landing end  32 , wherein the pin connecting end  31  is to be attached to the frame pin connecting part  15  configured on the relative outside end of the first and second panels  11 ,  12 . Further, a pitman pin connecting part  33  is configured on the inner side and at a certain height of each lateral frame  30  between the pin connecting end  31  and the landing end  32 . 
         [0029]    Two oblique connecting rods  40  are attached between the two lateral frames  30 , wherein the relative outside ends of the two oblique connecting rods  40  are relatively attached through pin-joint to the pitman pin connecting parts  33  configured on the two lateral frames  30 . The relative inside ends of the two oblique connecting rods  40  form an upper-pointed angle and extend to the spacing position under the central spindle  20 . The relative inside end of the two oblique connecting rods  40  are configured with a pin sleeving part  41  to be attached to each other through the pin-joint. 
         [0030]    A control device  50  is attached to the corresponding position on the pin sleeving part  41  configured on the relative inside end of the two oblique connecting rods  40 . The control device  50  comprises a control part  51  and a locking member  52 , wherein, when the locking member  52  is positioned on the preset first position, the pin-joint state of the relative inside ends of the two oblique connecting rods  40  will be locked, and, when the locking member  52  is positioned on the preset second position, the pin-joint state of the relative inside ends of the two oblique connecting rods  40  will be released and can rotate around the spindle. The control part  51  is used to control and shift the position of the locking member. 
         [0031]    A central connecting frame  60  is attached between the central spindle  20  and the relative inside ends of the two oblique connecting rods  40 , wherein the top end of the central connecting frame  60  is configured with a through hole  61  for the central spindle  20  to go through, and the bottom end of the central connecting frame  60  is configured with an attaching seat  62  to be attached between the pin sleeving parts  41  configured on the inside ends of the two oblique connecting rods  40 . 
         [0032]    Two contacting parts  63  are formed through protrusion on the two relative sides on top of the attaching seat  62  of the central connecting frame  60 , and correspondingly, a receiving part  42  is configured on the relative inside end of the two oblique connecting rods  40  for the contacting part  63  to contact against, so that the central connecting frame  60  can be linked between the central spindle  20  and the relative inside ends of the two oblique connecting rods  40  in a rigid vertical angle. 
         [0033]    Further, the pin sleeving parts  41  configured on the relative inside ends of the two oblique connecting rods  40  comprise two inter-communicating concave spaces  410  with stopping parts  418  (only marked in  FIG. 4 ), and there are two inter-contacting projecting columns  411  in the center of the concave space  410 . The two projecting columns  411  are configured respectively with a through hole  412  and a screw hole  413 , so that they can be fixed through a screw  414  (or a screwing member with a screw matching a nut). Further, the corresponding ends of the two pin sleeving part  41  are configured with reducing projecting pipes  415  to contact against each other, and the attaching seat  62  configured on the bottom end of the central connecting frame  60  is shaped like a ring and sleeves the peripheral of the reducing projecting pipe  415 . The pin sleeving part  41  configured on the oblique connecting rods  40  is further configured with a receiving groove  416 , and on part of the inside wall of the receiving groove  416 , a through hole  417  is configured to inter-communicate with the concave space  410  of the pin sleeving part. The locking member  52  of the control device  50  is configured in the shape of a block with a stopping edge  521  (only marked in  FIG. 4 ) (note: this embodiment is configured in an S-shaped block), and is housed inside the two concave spaces  410  in a movable manner. When the locking member  52  is on the intersecting position of the two concave spaces  410  (the state shown in the upper drawing of  FIG. 7 ), the relative inside ends of the two oblique connecting rods  40  are locked. The center of the locking member  52  has a through hole  520  loosely shielding the projecting columns, and the control part  51  of the control device  50  includes a push button  511  and a return spring  512 . The push button  511  is attached in the receiving groove  416  configured on the outside of the pin sleeving part  41 , and the outside end of the push button  511  projects out of the receiving groove  416 , and the inside end of the push button  511  has a projecting elastic clasping pin  513  to go into and be locked inside the through hole  417  configured on the inner wall of the receiving groove  416 , and the return spring  512  is supported between the locking member  52  and the end wall of a concave space  410 , so as to push the locking member  52  to the intersecting position of the two concave spaces  410  to reach the locked state. In this way, when the push button  511  shrinks under pressure (the state shown in the lower drawing of  FIG. 7 ), the elastic clasping pin  513  will simultaneously extend inside and push the locking member  52  to shift to the inside of one concave space  410 , so that the relative inside ends of the two oblique connecting rods  40  are released and become rotatable, and meanwhile press the return spring  512  to accumulate the elastic force for returning. 
         [0034]    As disclosed in  FIGS. 2 and 5 , the frame pin connecting part  15  configured on the relative outside end of the first and second panels  11 ,  12  can be composed of two spaced projecting columns  151 , and at the corresponding position of the pin connecting end  31  of the two lateral frames  30 , two oblique angle attaching slots  310  can be configured. Said oblique angle attaching slot  310  must have a preset opening angle to join with the projecting column  151 . Such a design provides an easy structure for connection through pin-joint between the lateral frames  30  and the first and second panels  11 ,  12  without the need of any other auxiliary positioning parts. 
         [0035]    As disclosed in  FIGS. 2 and 6 , the pitman pin connecting part  33  configured on the lateral frames  30  can be composed of two spaced projecting axles  331 , and on the corresponding positions on the relative outside ends of the two oblique connecting rods  40 , two single opening attaching slot  43  are configured. Said single opening attaching slot  43  must have a preset opening angle to join with the projecting axle  331 ; Such a design provides an easy structure for connection through pin-joint between the lateral frames  30  and the oblique connecting rods  40  without the need of any other auxiliary positioning parts. 
         [0036]    As disclosed in  FIG. 3 , the top surface of the first and second panels  11 ,  12  of the foldable panel  10  can be further configured with spaced and parallel distributed concave attaching surface  16 . 
         [0037]    The above-described structure constitutes the construction of the present invention.  FIGS. 1 and 3  depicts the unfolded state of the pitman-style foldable frame structure disclosed in the present invention. At this time, the first and second panels  11 ,  12  are positioned in a plane through the contacting surfaces  110 ,  120  on their relative inside ends contacting against each other, and the two oblique connecting rods  40  are positioned in a V-shape and supported between the two lateral frames  30 . Further, the pin sleeving part  41  configured on the relative inside ends of the two oblique connecting rods  40  are connected to the first and second panels  11 ,  12  through the central connecting frame  60  connected with the central spindle  20 , forming a I-shaped structure. As the two contacting parts  63  extended from the central connecting frame  60  can go into and contact against the receiving parts  42  configured on the relative inside ends of two oblique connecting rods  40 , the central connecting frame  60  can be linked firmly in a vertical angle between the central spindle  20  and the two oblique connecting rods  40 . Hence, from the central spindle  20  downward to the central connecting frame  60 , till the pin sleeving parts  41  configured on the inside ends of the two oblique connecting rods  40 , under this unfolded state, a stable central positioning and supporting point is formed. Therefore, for half of the pitman-style foldable frame structure, the linking points form a roughly triangular supporting structure (as shown in the virtual block line L 1  in  FIG. 3 ), and in this way, the gaps and errors in the linking positions of the foldable frame are minimized, resulting in an optimum stable supporting effect. 
         [0038]      FIG. 9  discloses an implementation example of the present invention. In this example, the pitman-style foldable frame structure is used as the folding structure of a sled  70 . The sled  70  comprises a top frame  71  and a sliding frame  72 , and the front end of the sliding frame  72  is configured with a upper curving section  73  connecting with the top frame  71 . There shall be at least two pitman-style foldable frame configured in the front and back between the top frame  71  and the sliding frame  72  in parallel, so that the top frame  71  is attached and fixed on the top of the first and second panels  11 ,  12  of the foldable panel  10  of the pitman-style foldable frame, and the sliding frame  72  is attached and fixed on the landing end  32  of the two lateral frames  30  of the pitman-style foldable frame. 
         [0039]      FIG. 10  discloses another implementation example of the present invention. In this example, the pitman-style foldable frame structure is used as the folding structure of a chair  80 . The foldable panel  10  of the pitman-style foldable frame can be designed to be the panel part or panel attaching part of the chair  80 , and the two lateral frames  30  of the pitman-style foldable frame can act directly as the legs of the chair  80 . Certainly, it shall be easily understood from this example that the pitman-style foldable frame structure can also be used as the folding structure of tables. Such other implements shall be readily apparent to those of ordinary skill in the art upon a reading of this patent description and are therefore not further detailed.