Abstract:
A hinge assembly includes a shaft, a seat made of plastic, a follower, a cam, a latching member and a resilient member. The follower includes a cam surface. The seat is fixed to the follower, and the seat and the follower are placed around the shaft. The cam has a latching cam surface, the cam surface being engaged with the cam latching surface. The latching member is fixed to the cam, and the cam and the latching member are placed around the shaft. The resilient member is placed around the shaft and provides an elastic force to make the cam surface abut against the latching cam surface.

Description:
BACKGROUND 
       [0001]    1. Technical Field 
         [0002]    The present disclosure relates to hinge assemblies and, particularly, to a hinge assembly for foldable electronic devices such as mobile phones, portable computers, and so on. 
         [0003]    2. Description of Related Art 
         [0004]    At present, perhaps the most popular portable electronic device in the marketplace is the foldable mobile phone, which generally includes a cover section and a body section. The cover section and the body section are rotatably interconnected through a hinge assembly, for switching the telephone between an in-use position and a closed position. 
         [0005]    One kind of hinge assembly employs a cam and a follower made of metal. Although the hinge assembly may achieve the opening and closing of the foldable electronic device, the hinge assembly may be noisy during rotation. If the cam and the follower are made of plastic, although volume of the noise may be reduced, the cam and the follower will more easily break. 
         [0006]    Therefore, there is room for improvement within the art. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    Many aspects of the present hinge assembly can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present hinge assembly. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views. 
           [0008]      FIG. 1  is an exploded, isometric view of a hinge assembly. 
           [0009]      FIG. 2  is similar to  FIG. 1 , but shown from another aspect. 
           [0010]      FIG. 3  is an enlarged, isometric view of a cam and a follower in  FIG. 1 . 
           [0011]      FIG. 4  is an assembled view of the hinge assembly shown in  FIG. 1 . 
           [0012]      FIG. 5  is a cross-sectional view of  FIG. 4  taken along line V-V. 
       
    
    
     DETAILED DESCRIPTION 
       [0013]      FIGS. 1 and 2  show a hinge assembly  100  according to an exemplary embodiment of the present hinge system. The hinge assembly  100  includes a main shaft  10 , a seat  20 , a follower  30 , a cam  40 , a latching member  50 , a sleeve  60 , a resilient member  70 , and a washer  80 . 
         [0014]    The main shaft  10  coaxially includes a head portion  12  and a shaft portion  14 . The shaft portion  14  extends from one end of the head portion  12  and has a smaller diameter than the diameter of the head portion  12 . A free end of the shaft portion  14  defines a ring groove  142 . 
         [0015]    The seat  20  is made of plastic, and is substantially a rectangular parallelepiped. A circular hole  22  is defined at one side of the seat  20 , and a square latching hole  23  is defined at another side thereof. The hole  22  communicates with the latching hole  23 . A block  24  extends into the latching hole  23  from each of four sidewalls. Two arcuate surfaces  25  are respectively formed on opposite sides of two of the blocks  24  toward a center of the seat  20 . The seat  20  is configured for engaging with a body section of a foldable electronic device. 
         [0016]    Referring to  FIG. 3 , the follower  30  is made of metal, and includes a main portion  31 , and a fixing portion  32  and a cam portion  33  integrally formed together. The main portion  31  has a shape corresponding to the seat  20 . The fixing portion  32  is formed at one side of the main portion  31 . The cam portion  33  is formed at another side of the main portion  31 . The follower  30  defines a through hole  311 . The through hole  311  communicates the fixing portion  32  with the cam portion  33 . The shaft portion  14  may be received in the circular hole  22 , the latching hole  23  and the through hole  311 , and the head portion  12  may abut against the seat  20 . The fixing portion  32  includes two opposite ribs  320 . Each rib  320  is substantially I-shaped, and each of opposite outside sides of the ribs  320  defines a groove  321 . Each of opposite inside sides of the ribs  320  defines an arcuate recess  322 . When the seat  20  is latched to the cam  30 , two opposite blocks  24  are latched into the grooves  321 . Another two blocks  24  are disposed between the ribs  320 . The arcuate surface  25  and an inside surface of the arcuate recess  322  surround a space to receive the shaft portion  14 . The cam portion  33  includes at least one, e.g. two symmetric first cam surfaces  34 . Each first cam surface  34  includes a peak  342  and a valley  346 . A plurality of sub-surfaces is formed between the peak  342  and the valley  346 . The peak  342  is formed at a highest position of the first cam surface  34 . The valley  346  is formed at a lowest position of the first cam surface  34 . 
         [0017]    The cam  40  is made of metal, and includes a latching cam portion  41  and an end portion  43  extending from the latching cam portion  41 . A longitudinal passage  45  is defined in the cam  40  for receiving the shaft portion  14 . The latching cam portion  41  includes second cam surfaces  42  for engaging with the first cam surfaces  34  of the follower  30 . There is one second cam surface  42  for each first cam surface  34 . Each second cam surface  42  includes a peak  422  and a valley  426 . A plurality of sub-surfaces is formed between the peak  422  and the valley  426 . The end portion  43  is smaller radially than the latching cam portion  41 . At least one, e.g. two latching grooves  431  are symmetrically formed on an outer periphery of the end portion  43 . 
         [0018]    The latching member  50  includes a hollow polygonal can  51 , a partially closed end  52  and an open end  53 . The partially closed end  52  is opposite to the open end  53 . Two extending portions  55  are formed on the open end  53  for being received in the latching grooves  431  to latch the latching member  50  to the cam  40 . The partially-closed end  52  has a central hole  54 . 
         [0019]    The sleeve  60  is substantially a hollow cylinder, and includes a cylindrical body  61  and a positioning portion  63  integrally formed together. The sleeve  60  includes a first open end  62  and a second open end  64  opposite to each other. The positioning portion  63  extends from the second open end  64 . At least one flattened surface  65  is formed on an outer peripheral wall of the positioning portion  63 . The flat surface portions  63  are configure for engaging with a cover section of the foldable electronic device. In this exemplary embodiment, the sleeve  60  is formed by a punch stretch process. The cylindrical body  61  is fully circular, and has a larger cross-section compared to the cross section of the positioning portion  63  owing to the flat surfaces  65 . The number of flat surfaces  65  corresponds to the number of planar surfaces of the polygonal can  51 . 
         [0020]    The resilient member  70  is preferably made of metal and is spiral-shaped (i.e. a coil spring). The resilient member  70  is just large enough to be placed around the main shaft  10 . The resilient member  70  is smaller than the cylindrical portion  61 , and is larger than the positioning portion  63 . 
         [0021]    The washer  80  is made of made of a strong material, such as metal. In the present embodiment, the washer  80  is substantially C-shaped and is clasped in the ring groove  142 , thereby mounted with the main shaft  10 . 
         [0022]    Referring to  FIG. 4 , the fixing portion  32  is inserted into the latching hole  23  of the seat  20 . Two opposite blocks  24  are latched into the grooves  321 . Another two blocks  24  are disposed between the ribs  320 . Accordingly, the seat  20  is latched to the follower  30  in any manner that will not allow them to rotate relative to one another. The extending portions  55  of the latching member  50  are latched into the latching grooves  431  to latch the latching member  50  to the cam  40 . Then, the follower  30  with the seat  20 , and the cam  40  with the latching member  50  are mounted on the shaft  10 . The head portion  12  abuts against the seat  20 . The second cam surface  42  of the cam  40  engages with the first cam surface  34  of the follower  30 . After that, the shaft  10  with the above elements is received in the sleeve  60  from the second end  64 . The polygonal can  51  engages with the positioning portion  63 . The resilient member  70  is assembled into the sleeve  60  from the first open end  62 , and is placed around the shaft portion  14 . One free end the main shaft  10  passes through the first open end  62 , and the washer  80  is mounted in the ring groove  142 . One end of the resilient member  70  abuts against the washer  80 , and the other end of the resilient member  70  abuts against the latching member  50 . Thus, the hinge assembly  100  is integrated into a complete unit. 
         [0023]    The hinge assembly  100  is used to interconnect a main body and a cover of the foldable electronic device. The seat  20  non-rotatably engages the main body, and the sleeve  60  non-rotatably engages with the cover. 
         [0024]    When the cover is closed relative to the main body, the peaks  422  of the second cam surface  42  abut against the first cam surface  34 . The resilient member  70  is compressed to enable the cover and the main body to be in an original closed, stable state. 
         [0025]    To open the foldable electronic device, the cover is manually rotated away from the main body, hence the sleeve  60  and the cam  40  rotate relative to the follower  30 . The peaks  422  of the second cam surface  42  slide along the first cam surface  34 , and the resilient member  70  is compressed further. When the cover is opened to a predetermined angle, the peaks  422  slide over the peaks  342  of the first cam surfaces  34 . At the same time, the resilient member  70  is almost completely compressed. Then, when the cover is released, the follower  30  automatically rotates relative to the cam  40  due to the expansion of the resilient member  70  as the peaks  342  slide down along the second cam surface  42 . Thus, the cover is automatically rotated to a fully and stable open state. The process of closing the cover is reverse to the process of opening the cover. Since the seat  20  and the latching member  50  are made of plastic, the hinge assembly  100  makes relatively little noise. In addition, only one part of the sleeve  60  forms flattened surfaces, thus the cylindrical body  61  may be made larger to receive the resilient member  70  without adding to the overall bulk of the hinge assembly  100 . 
         [0026]    It should be understood that the cam portions of follower  30  and the cam  30  may have other shapes. The shape of the cam portion may be changed according to the desired open angle of the cover. The washer  80  may be soldered to the shaft  10 . The head portion  12  may be integrally attached with the main shaft  10 . 
         [0027]    The seat  20  and the follower  30 , the cam  40  and the latching member  50  may be formed in any manner that does not allow them to rotate relative to one another. For example, they can be integrally formed together by insert molding. 
         [0028]    It is to be understood, however, that even though numerous characteristics and advantages of the present embodiments have been set forth in the foregoing description, together with details of the structures and functions of the embodiments, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the disclosure to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.