Abstract:
A hinge assembly includes a main shaft, a fixing seat, a follower, a cam and a first elastic element. The fixing seat is fixed with the main shaft. The follower is placed around the shaft, and the fixing seat selectively locks with the follower. The cam is placed around the shaft, and engages with the follower. The first elastic element provides an elastic force to make the cam and the follower resist each other and provides a force to make the cam and the follower rotate together.

Description:
BACKGROUND 
     1. Technical Field 
     The present disclosure relates to hinge assemblies and, particularly, to an automatically opening hinge assembly for foldable devices such as portable telephones, portable computers. 
     2. Description of Related Art 
     Traditional automatic hinge assemblies can automatically open a foldable mobile phone, which generally includes a cover section and a body section. This kind of hinge assembly usually includes a cam and a control member. The cam has a tendency to rotate. However, the control member limits the cam to rotate. Thus, the control member has to be under a large shearing force. Accordingly, the control member needs to be made of hard and high strength material, which increases the cost. In addition, the control member easily produces noise during movement. 
     Therefore, there is room for improvement within the art. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Many aspects of the embodiments can be better understood with references 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. 
         FIG. 1  is an exploded, isometric view of the exemplary embodiment of the hinge assembly shown in  FIG. 1 . 
         FIG. 2  is similar to  FIG. 1 , but viewed from another aspect. 
         FIG. 3  is an enlarged view of the button. 
         FIG. 4  is an enlarged view of the receiving seat. 
         FIG. 5  is similar to  FIG. 4 , but viewed from another aspect. 
         FIG. 6  is an enlarged view of the cam in  FIG. 2 . 
         FIG. 7  is an enlarged view of the follower in  FIG. 2 . 
         FIG. 8  is a partially assembled view showing the hinge assembly in  FIG. 2 . 
         FIG. 9  is an assembled view showing the hinge assembly in  FIG. 2  without the sleeve. 
         FIG. 10  is an assembled view showing the hinge assembly. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to the drawings in detail,  FIGS. 1 and 2  show a hinge assembly  100 , applied to a foldable electronic device such as a flip type mobile phone. The hinge assembly  100  could be used in other environments (e.g. cabinet doors). Although proving particularly advantageous when used in foldable electronic devices, the hinge assembly  100  should not be considered limited in scope solely to foldable electronic devices. 
     The hinge assembly  100 , in the embodiment illustrated, includes a button  10 , a first elastic member  20 , a receiving seat  22 , a control member  30 , a second elastic member  40 , a cam  42 , a follower  50 , two cushions  56 , a shaft  60 , a main elastic member  68 , a sleeve  70 , a washer  80  and a ring  82 . 
     Referring to  FIG. 3 , the button  10  is substantially cylindrical, and includes a pressed end  110  and an opposite open end  120 . Two symmetric arms  122  and two symmetric clasps  124  are formed on the open end  120 . The arms  122  press the control member  30 , and the clasps  124  latch with the receiving seat  22 . 
     The first elastic member  20  is a cylindrical helical spring (i.e., occupying a cylindrical volume). The first elastic member  20  is disposed between the button  10  and the receiving seat  22 . 
     Referring to  FIGS. 4 and 5 , the receiving seat  22  includes a seat portion  24  and a latching portion  26  connected to one end of the seat portion  24 . The seat portion  24  is substantially a hollow cylinder, and includes an outer surface  241  and an inner surface  242 . The outer surface  241  defines a plurality of seat grooves  244  engaging with a body section of the mobile phone so that the receiving seat  22  and the body section cannot rotate relative to each other. One end of the inner surface  242  away from the latching portion  26  defines two limiting grooves  246 . The latching portion  26  includes two opposite arcuate walls  262  and a column  264 . The arcuate walls  262  extend from one end of the inner surface  242  of the seat portion  24 . Two guide grooves  266  are defined between the arcuate walls  262  for receiving the arms  122 . Each arcuate wall  262  defines a notch  263  for receiving a corresponding clasp  124  of the button  10 . The column  264  extends from an inside of the arcuate walls  262 , and is coaxially disposed with the seat portion  24 . A receiving groove  265  is defined between the column  264  and the arcuate walls  262 . One end of the first elastic member  20  is placed around the column  264 , and is received in the receiving groove  265 . The column  264  defines a through hole  267  for fixedly connecting to the main shaft  60 . 
     The control member  30  includes a body  32  and two extensions  34  integrally formed together. The control member  30  can be received in the seat portion  24  of the receiving seat  22 . The body  32  abuts against the column  264 , and is exposed from the guide grooves  266 . The extensions  34  can be received in a corresponding limiting groove  246 . A block  342  radially extends from a distal end of each extension  34 . The blocks  342  allow the extensions  34  to resist a large shearing force so that the control member  30  can made of a relatively soft material. In addition, the control member  30  can produce less noise due to being made from soft material. 
     The second elastic member  40  is substantially cylindrical, and may be received in the control member  30  for returning the control member  30 . 
     Referring to  FIG. 6 , the cam  42  includes a cam portion  420  defining a through passage  421 . The cam portion  420  includes a first cam surface  422  at one end thereof. Two extending walls  423  extending from an opposite end of the cam portion  420  can be received in the seat portion  24 . Two slots  424  are defined between the extending walls  423 . The extensions  34  are received in the slots  424 . 
     Referring also to  FIG. 7 , the follower  50  includes a cylindrical circumferential wall  510  and an inner circumferential wall  512 . Two symmetric projections  52  are formed on the outer circumferential wall  510 . Two cushions  54  are formed adjacent to a corresponding projection  52 . One end of the follower  50  has a second cam surface  522  for engaging with the first cam surface  422  of the cam  42 . The follower  50  defines a through hole  51  defined by the inner circumferential wall  512 . An inner thread  511  is formed on the inner circumferential wall  512 . 
     The cushions  54  are made of soft material relative to the material of follower  50 , for example, polyoxymethylene (POM). Each cushion  54  defines a cutout  562  for engaging with the projections  52  so that the cushions  54  can be latched to the follower  50 . The projections  52  and the ribs  54  are engaged together with the sleeve  70 . The soft cushions  54  can reduce noises with the sleeve  70 . 
     The shaft  60  includes a first shaft portion  62  and a second shaft portion  64 . The first shaft portion  62  defines an outer thread  622  engaging with the inner thread  511  of the follower  50 . One end of the shaft  60  forms a locking end  66 . The other end of the shaft  60  forms a latching portion  67 . The main elastic member  68  is a helical spring, and may be fitted over the first shaft portion  62 . 
     The sleeve  70  is a substantially hollow cylinder, and includes an open end  72  and a partially-closed end  74 . The partially-closed end of the sleeve  74  defines a central hole  742 . Two long troughs  78  are defined in an inner wall of the sleeve  70  and two sleeve blocks  76  are formed corresponding to the long troughs  78 . The sleeve blocks  76  engage with a cover section of a mobile phone. 
     The washer  80  is substantially disk-shaped, and rotatably connects to the locking end  66  reducing energy loss with the sleeve  70 . The ring  82  defines a hole  822  in a central area thereof. The ring  82  fixes with the locking end  66  of the shaft  60 . 
     In assembly, referring to  FIGS. 8 to 10 , the cam  42 , the second elastic member  40 , the control member  30 , the receiving seat  22  are fitted over the shaft  60  from the latching end  67 . The control member  30  is received in the receiving seat  22 . The body  32  abuts against the column  264 , and is exposed from the guide grooves  266 . The extension arms  34  with the blocks  342  are received in the limiting grooves  246 . The first elastic member  20  is placed around the column  264  and is received in the receiving groove  265 . The arms  122  are received in the guide grooves  266  and abut against the control member  30 . The clasps  124  are slidably received in the notches  263  for preventing the button  10  from separating from the receiving seat  22 . The second elastic member  40  is disposed between the control member  30  and the receiving seat  22 . The extension arms  34  of the control member  130  are slidably engaged in the slots  424  of the cam  42  so that the control member  30  is locked with the cam  42 . 
     Next, the follower  50  is placed around the shaft  60 , with the first cam surface  422  of the cam  42  engaging with the second cam surface  522  of the follower  50 . The main elastic element  68  is placed around the shaft  60  from the locking end  66 . After the above elements are assembled, the sleeve  70  is placed around the shaft  60 . The open end  72  of the sleeve  70  is adjacent to the receiving seat  22 . The partially-closed end  74  of the sleeve  70  resists the main elastic element  68 . The cushions  56  of the follower  50  are engaged in the trough  78  of the sleeve  70  to limit the rotation therebetween. Accordingly, the hinge assembly  100  is assembled. Because the control member  30  is locked with the receiving seat  22 , the control member  30  cannot rotate relative to the receiving seat  22 . 
     When a user wants to automatically open the mobile phone  200 , he/she may press the button  10 . In this process, the button  10  moves along an axial direction of the shaft  60 , the arms  122  of the button  10  then push the control member  30  to move away from the button  10  in the axial direction of the shaft  60 . The control member  30  moves along the axis until the extension arms  34  of the control member  30  break away from the limitation of the receiving seat  22 , compressing the second elastic member  40  toward the cam  42 . At that time, the button  10  is released. The control member  30 , the cam  42 , with the follower  50  automatically rotates relative to the shaft  60 . The elastic potential energy of the second elastic spring  40  then pushes the control member  30  to move toward the button  10 . Furthermore, the follower  50  brings the sleeve  70  to rotate so that the cover section of the mobile phone is opened. Since the soft cushions  54  engage with the sleeve  70 , noises are greatly reduced when the sleeve  70  rotates relative to the follower  50 . Additionally, the blocks  342  of the control member  30  allow the extensions  34  to be made of soft material. Thus, noises are also reduced when the control member  30  moves. 
     As described above, the present embodiment provides a hinge assembly  100  for use with various portable devices, beyond the mobile phone illustrated, and/or with other devices needing a hinge assembly that facilitates the achievement of fully open and fully closed positions. 
     It is believed that the present embodiments and their advantages will be understood from the foregoing description, and it will be apparent that different changes may be made thereto without departing from the spirit and scope of the disclosure or sacrificing all of its material advantages, the examples hereinbefore described merely being preferred or exemplary embodiments of the disclosure.