Patent Publication Number: US-7721388-B2

Title: Door hinge

Description:
FIELD OF THE INVENTION 
   The present invention relates to a door hinge, and more particularly, to a door hinge for allowing an opening/closing operation of a door with less force. 
   BACKGROUND OF THE INVENTION 
   As well known in the art, a door hinge refers to an apparatus designed to allow a door to be opened/closed on a door frame. The door hinge is divided as a door hinge constructed to open and close the door in a left/right opening/closing method starting from one side, and a door hinge constructed to open and close the door in an up/down opening/closing method (that is, a lying down in front and coming out method) starting from an upper end. 
   The latter door hinge is used for a door of a gas oven or microwave oven that is electric home appliances. A conventional construction of the door hinge is shown in  FIG. 1 . 
   As shown in  FIG. 1 , the conventional door hinge  150  includes a fixing mount  110  installed at a door frame  100 ; and an activating mount  112  installed at the door  200 , connecting by a hinge  126  with the fixing mount  110 , rotating about the hinge  126 , and opening and closing the door  200 . 
   A guide unit  114  is provided between the fixing mount  110  and the activating mount  112 , and guides an opening/closing operation of the door  200 . 
   The guide unit  114  includes a connection plate  116  installed at the fixing mount  110 ; a rotation plate  120  connecting by a pin  118  with the connection plate  116  and rotating about the pin  118 ; and a guide pin  124  combining to a front end of the rotation plate  120  and moving up/down along the guide hole  122  provided at both side surfaces of the activating mount  112 . 
   In the above constructed guide unit  114 , when the activating mount  112  is rotated, the guide pin  124  vertically moves down along the guide hole  122  and at the same time, the rotation plate  118  connecting to the guide pin  124  rotates about the pin  118  depending on the movement of the guide pin  124  and guides the rotation of the activating mount  112 . Thus, the door  200  can stably perform an opening operation. 
   However, the conventional door hinge  150  is expected to have drawbacks below in use. 
   First, there is a drawback in that, if the guide hole  122  is manufactured to have a straight-line shape as shown, a force is much needed in opening the door  200 . In other words, due to a characteristic that the door  200  rotates about the hinge  126  and is lain down in front and opened, the door  200  pulls the guide pin  124  in its opening. Owing to the straight-line shape of the guide hole  122 , the guide pin  124  strongly contacts with one side surface of the guide hole  122  by a pulling force of the door  200  in its movement, thereby generating a frictional force. This frictional force limits the guide pin  124  in its vertical movement, thereby causing a drawback of much needing the force in opening the door  200 . 
   Further, it is required to open and stop the door  200  at a predetermined angle so as to check food in cooking, but there is a drawback that the conventional door hinge  150  is not provided with means for stopping the door  200  at a predetermined angle. 
   SUMMARY OF THE INVENTION 
   Accordingly, the present invention is directed to a door hinge that substantially overcomes one or more of the limitations and disadvantages of the conventional art. 
   One object of the present invention is to provide a door hinge for opening a door by less force. 
   Another object of the present invention is to provide a door hinge for, after opening a door at a predetermined angle, automatically keeping a still state of the door. 
   A further another object of the present invention is to provide a door hinge for, after fully opening a door, supporting the door and preventing a collision against the ground. 
   A yet another object of the present invention is to provide a door hinge for, after closing a door, firmly compressing the door to a door frame. 
   A still another object of the present invention is to provide a door hinge for minimizing the occurrence of a noise at the time of opening/closing a door. 
   Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims as well as the appended drawings. 
   To achieve the above and other objects and advantages, and in accordance with the purpose of the invention, as embodied and broadly described herein, there is provided a door hinge including a fixing member, an activating member, a guide pin, and a guide frame. The fixing member is installed at a door frame. The activating member is installed at a door, and connects with the fixing member by a hinge, and opens and closes the door. The guide pin is fitted into guide holes provided at both sides of the activating member, and elastically moves up/down along the guide hole by a tension force of a spring installed inside the activating member. A guide frame is combined to the guide pin, and connects at its lower end with the fixing member by a pin, and rotates about the pin depending on an operation of the activating member. The guide hole is round (R) shaped at its center, and has a curved shape in entirety. 
   The guide hole may be further provided at its upper part with an inclination part inclined oppositely to a central round part. 
   A plate spring may be attached to one side surface of the activating member, and may be provided at its center with an elastic protrusion. The elastic protrusion is selectively locked by any one of first and second locking jaws provided at one side surface of the guide frame, and restricts the rotation of the guide plate. 
   The guide frame further may include, at its one side and lower end, a third locking jaw for locking a reinforcement pin provided at a lower end of the activating member. 
   The hinge may be provided at its one end with a square jaw, and any one of connection through-holes, into which the hinge is fitted, of the activating member may be square shaped corresponding to the square jaw. 
   Primary opening to be referred in the present invention refers to a state where the door is stretched by about 15° on the door frame so as to check a cooking state of food. Secondary opening refers to a state where the door is lain down and opened by about 90° on the door frame so as to take out the completely cooked food. 
   It is to be understood that both the foregoing summary and the following detailed description of the present invention are merely exemplary and intended for explanatory purposes only. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings, which are included to aid in understanding the invention and are incorporated into and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principles of the invention. In the drawings: 
       FIG. 1  is  FIG. 1  illustrates a structure of a conventional door hinge; 
       FIG. 2  is an exploded perspective view illustrating a construction of a door hinge according to the present invention; 
       FIG. 3  is a side view illustrating an assembly structure of a door hinge shown in  FIG. 2 ; 
       FIG. 4  is a front view of  FIG. 3 ; and 
       FIGS. 5 and 6  sequentially illustrate an operation of a door hinge according to the present invention. 
   

   DETAILED DESCRIPTION OF THE DRAWINGS 
   Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numerals will be used throughout the drawings to refer to the same or like parts. 
     FIGS. 2 to 4  illustrate a construction of a door hinge according to the present invention. 
   As shown, the door hinge  50  is greatly divided as a fixing member  10  and an activating member  12 . 
   The fixing member  10  is installed at a door frame  100 , and supports each constituent part of the door hinge  50 . 
   The activating member  12  is installed at a door  200 . The activating member  12  connects by a hinge  14  to the fixing member  10 , and rotates about the hinge  14 , and opens or closes the door  200 . The hinge  14  is provided at its one end with a square jaw  16 . It is desirable that any one  18   a  of connection through-holes  18   a  and  18   b , into which the hinge  14  is fitted, of the activating member  12  is square shaped corresponding to the square jaw  16 . This is to, when the activating member  12  rotates, allow the hinge  14  not to rotate by the square jaw  16  of the hinge  14  and the square-shaped connection through-hole  18   a , with the hinge  14  fitted into the connection through-holes  18   a  and  18   b , thereby preventing the occurrence of a noise caused by a friction between the connection through-holes  18   a  and  18   b  and the hinge  14 . 
   A spring  20  is installed inside the activating member  12 . The spring  20  connects at its one end to the activating member  12  and connects at the other end to a guide pin  28 , and provides a tension force based on a proper pressure such that the guide pin  28  elastically moves up/down. 
   A guide unit  22  is installed between the fixing member  10  and the activating member  12 , and guides an operation of the activating member  12 . 
   The guide unit  22  includes a guide frame  24 , the guide pin  28 , and a guide hole  30 . 
   In state where the fixing member  10  connects with the pin  26 , the guide frame  24  rotates about the pin  26  depending on a rotation operation of the activating member  12 . The guide frame  24  is combined at its front end with the guide pin  28  that moves up/down along the guide hole  30 . The guide frame  24  is provided at its one side surface with a plurality of first and second locking jaws  24   a  and  24   b  that are spaced a predetermined distance apart. The first and second locking jaws  24   a  and  24   b  are selectively locked by an elastic protrusion  34  of a plate spring  32  to be described later. The first and second locking jaws  24   a  and  24   b  restrict a rotation of the activating member  12  and thus, restrict an opening of the door  200 . The guide frame  23  is further provided at its lower end with another third locking jaw  24   c . When the door  200  is completely opened and is lain down in front, the third locking jaw  24   c  is locked by a reinforcement pin  36  provided at a lower end of the activating member  12 , thereby supporting the opened door  200  and preventing the door from colliding against the ground. 
   The guide pin  28  refers to a pin for, when the activating member  12  rotates to open the door  200 , moving up/down along the guide hole  30 , and guiding the rotation operation of the activating member  12 . The guide pin  28  is combined to a front end of the guide frame  24 , and is fitted into the guide hole  30  provided at both side surfaces of the activating member  12 , thereby connecting the guide frame  24  with the activating member  12 . 
   As described above, the guide hole  30  is provided by passing through both side surfaces of the activating member  12 , and guides the up/down movement of the guide pin  28 . The guide hole  30  is rounded at its center, and has a curve shape in entirety. This is to allow the opening and closing operation of the door  200  by less force. 
   In other words, in the guide hole  30  having the most ideal shape, preferably as shown in  FIG. 2 , a force of the spring  20  should be necessarily designed on the basis of “χ·sin θ” such that the guide hole  30  is rounded (R) and preferably has the curved shape in entirety. This Equation of “χ·sin θ” will be easily understood by a detailed description below. 
   1) A torque acting on a rotation direction of the door within an operation range (θ: 0° to 90°) of the door is expressed by a product of a component sin θ of a load and a distance (r) from a rotation center below: 
   
     
       
         
           
             
               
                 
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   2) In a conventional method, a force by a spring inside a hinge is expressed below depending on an opening angle of a door:
 
 F=k   x ×χ(θ)= k   x ×(χ 0   +k   θ ·θ)
 
   k x : spring constant, and 
   k x (χ 0 +k θ ·θ): variable. 
   Thus, the force (F) has a linear format. 
   In other words, in the conventional method, the force by the door and the force by the spring cannot be consistent, and this causes unbalance in force when the door is activated (opened and closed) and thus, is against nature. 
   When two forces are exactly consistent, the most ideal state becomes the most excellent state and thus, the force by the spring should be designed to have a “χ·sin θ” format. 
   Accordingly, in the present invention, the force by the spring is expressed by Equation below and thus, can be designed closely to an ideal state:
 
 F=k   x ×χ(θ)= k   x ×(χ 0 +χ·sin θ)
 
   χ 0 : initial position, and 
   χ: distance variation of the door depending on angle at the time of opening the door. 
   Meantime, the plate spring  32  is attached to one surface of the activating member  12  by a connection unit  33  such as a rivet. The plate spring  32  pressurizes the guide frame  24  by its tension force, restricts the rotation of the activating member  12 , and selectively stops opening the door  200 . In detail, the elastic protrusion  34  is protruded and provided at a center of the plate spring  32 . The elastic protrusion  34  is selectively locked by any one of the first and second locking jaws  24   a  and  24   b  provided at one side surface of the guide frame  24 . In other words, when the elastic protrusion  34  is locked by the first locking jaw  24   a  of the guide frame  24 , the door  200  is in a closed state. When the elastic protrusion  34  is locked by the first locking jaw  24   a , it pressurizes the guide frame  24  by the tension force of the plate spring  32 , thereby restricting the rotation of the activating member  12  and restricting the arbitrary opening of the closed door  200 . If the door  200  is pulled by a force larger than the tension force of the plate spring  32  and is primarily opened, the elastic protrusion  34  is unlocked from the first locking jaw  24   a  of the guide frame  24  and then, is locked by the second locking jaw  24   b . When the door  200  is free from pulling, the tension force of the plate spring  32  again acts, and the elastic protrusion  34  pressurizes the guide frame  24  and restricts the rotation of the activating member  12 , thereby keeping a still state of the primarily opened door  200 . 
   The activating member  12  is provided at its lower end with the reinforcement pin  36  in penetration. When the door  200  is secondarily opened, that is, when the door  200  is lain down in front and is completely opened, the reinforcement pin  36  is locked by the third locking jaw  24   c  provided at the lower end of the guide frame  24 , thereby supporting the secondarily opened door  200  and preventing a collision of the door  200  against the ground. 
   An operation of the above constructed door hinge according to the present invention will be described with reference to  FIGS. 5 and 6  below. 
   First, in the inventive door hinge  50 , its operation is divided as an operation of primarily opening the door  200  to check a cooking state of food and an operation of secondarily opening the door  200  to take out the completely cooked food. 
     FIG. 5  illustrates the operation of the door hinge  50  for primarily opening the door  200  according to the present invention. As shown, if the closed door  200  is pulled, the activating member  12  is rotated about the hinge  14 . The guide pin  28  connecting the activating member  12  with the guide frame  24  elastically moves down along the guide hole  30  by the tension force of the spring  20  depending on the rotation of the activating member  12 , and guides the rotation of the activating member  12 . 
   After that, if the door  200  is opened by about 15°, its still state is automatically kept. In other words, when the activating member  12  is rotated, the elastic protrusion  34  of the plate spring  32  is unlocked from the first locking jaw  24   a  of the guide frame  24  and then, is locked by the second locking jaw  24   b . If the door  200  is free from pulling, when the elastic protrusion  34  is locked by the second locking jaw  24   b , it pressurizes the guide frame  24  by the tension force of the plate spring  32 , thereby restricting the rotation of the activating member  12 . Thus, the door  200  is primarily opened and then, its still state is automatically kept. 
     FIG. 6  illustrates the operation of the door hinge  50  for secondarily opening the primarily opened door  200 . As shown, when the primarily opened door  200  is pulled by a force larger than the tension force of the plate spring  32 , the elastic protrusion  34  is unlocked from the second locking jaw  24   b . Thus, the activating member  12  is rotated about the hinge  14  freely from restriction. 
   At the same time of rotating the activating member  12 , the guide pin  28  elastically moves down along the guide hole  30 , and guides the rotation of the activating member  12 . The guide pin  28  can smoothly move with less friction through a round part (R) of the guide hole  30 , thereby open the door  200  by less force. 
   After that, if the door  200  is completely lain down in front and is secondarily opened, the reinforcement pin  36  provided for the activating member  12  is locked by the third locking jaw  24   c  of the guide frame  24  and thus, the door  200  is spaced a predetermined angle apart from the ground and is supported, and the door  200  is prevented from colliding against the ground. 
   As described above, the present invention achieves many effects as follows. 
   First, there is an effect in that the guide hole is rounded and curved-shaped, thereby opening the door by the less force. 
   Second, there is an effect in that after the door is primarily opened, its still state can be automatically kept, thereby providing a use convenience. 
   Third, there is an effect in that after the door is secondarily opened, the door is spaced a predetermined angle apart from the ground and is supported, and the door is prevented from colliding against the ground. 
   Fourth, there is an effect in that after the door is closed, the door can be firmly compressed to the door frame by the tension force of the plate spring. 
   Fifth, there is an effect in that the hinge does not run idle inside the connection through-hole of the activating member, thereby preventing the occurrence of the noise caused by the friction of the hinge and the connection through-hole at the time of opening and closing the door. 
   While the present invention has been described with reference to exemplary embodiments thereof, it will be apparent to those skilled in the art that various modifications can be made therein without departing from the spirit and scope of the invention as defined by the appended claims and their equivalents.