Patent Publication Number: US-9410353-B2

Title: Door closer

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is the United States National Stage of and claims priority to International Application No. PCT/KR2013/011083, which was filed Dec. 3, 2013, that claims priority to Korean Application No. 10-2012-0139177 filed Dec. 3, 2012, titled “DOOR CLOSER”, both of which are incorporated herein by reference in their entirety. 
     TECHNICAL FIELD 
     The present invention relates to a door closer which automatically closes a hinged door by elastic force when the hinged door is opened. 
     BACKGROUND ART 
     A door closer is typically attached to a hinged door such as a front door, fire door, etc. of a house, apartment, officetel, etc. so as to automatically close the door by elastic force when it is opened.  FIG. 1  is a cross-sectional view showing an example of a conventional door closer. Referring to  FIG. 1 , the conventional door closer comprises a housing  2 , a pinion gear  4  which is fixed to a link shaft (also called a gear shaft) penetrating approximately the middle of the housing  2  and coaxially rotates with the link shaft, a coil spring  9  which is disposed on one side of the inside of the housing  2 , and a spring pusher  6  which comprises a rack gear portion  7  engaged with the pinion gear  4  and pressurizes the coil spring  9  to accumulate elastic energy for closing a door (not shown) when the door is opened. The housing  2  is attached to the door, one end of a link (also called a connecting rod) is connected to the link shaft (not shown), and the other end of the link is connected to a door frame. 
     In the conventional door closer  1  shown in  FIG. 1 , the housing  2  has a space for accommodating the pinion gear  4  approximately in the middle thereof, a space for accommodating the coil spring  9  on one side thereof, and a space for accommodating the spring pusher  6  on the other side thereof. Therefore, the housing  2  cannot be easily configured compactly and reduced in size. 
     Meanwhile, a longer coil spring  9  having large elastic force is needed to close a heavy and large door such as a steel fire door. One side of the housing  2  is closer to a rotation axis (not shown) of the door than the other side of the housing  2 , and thus it is difficult to provide a space for accommodating the large coil spring  9  by extending one side of the housing  2  in the positive (+) direction of the X axis. Moreover, the position of the pinion gear  4 , i.e. the link shaft (not shown), is associated with the length of the link, which restricts the movement in the negative (−) direction of the X axis, and thus it is difficult to provide a space for accommodating the large coil spring  9  by extending the other side of the housing  2  in the negative (−) direction of the X axis. In other words, when a longer coil spring  9  is used to increase the door-closing force or efficiency in the conventional door closer  1 , the link shaft (not shown) structurally needs to be more far away from the rotation axis of the door such that the door can be fully opened to 180° or the link needs to be configured longer, which is problematic. 
     DISCLOSURE 
     Technical Problem 
     An object of the invention is to provide a door closer which comprises a housing that is configured compactly and reduced in size. 
     Moreover, another object of the invention is to provide a door closer which can easily extend a large spring to be disposed in the housing and, at the same time, can be mounted to a door without the occurrence of an operation error such as poor opening of the door. 
     Furthermore, still another object of the invention is to provide a door closer which can be mounted to a door such that the door can be opened 180° without having to extend the length of a link even when a large spring is mounted to the inside of a housing to increase the elastic force. 
     Technical Solution 
     The present invention provides a door closer comprising: a housing which is fixed to a door; a link of which one end is connected to a door frame; a link shaft which is rotatably inserted into the housing and of which an upper end projecting to the outside of the housing is connected to the other end of the link; a pinion gear which coaxially rotates with the link shaft; a piston which is inserted into the housing to reciprocate in the longitudinal direction of the housing and comprises a rack gear portion which is formed on one end thereof and engaged with the pinion gear, a piston base portion which is formed on the other end thereof, and a piston body portion which connects the piston base portion and the rack gear portion; and a coil spring which is put on the piston body portion and is compressed and accumulates elastic energy when the link shaft rotates in a direction that closes the door, in which one end of the coil spring, which is relatively close to the link shaft, is restricted to move toward the link shaft in the housing and the other end of the coil spring, which is relatively far from the link shaft, is pushed by the piston base portion and moves toward the link shaft such that the coil spring is compressed. 
     Moreover, the present invention provides a door closer which comprises a coil spring which is put on the piston body portion and is compressed and accumulates elastic energy when the link shaft rotates in a direction that closes the door. 
     The link shaft and the pinion gear may be located on one side in the longitudinal direction of the housing and the coil spring and the piston base portion may be located on the other side in the longitudinal direction of the housing. 
     A spring hole, into which the coil spring is inserted, and a rack gear hole, through which the rack gear portion reciprocates and which has an inner diameter smaller than the inner diameter of the spring hole, may be connected to each other in a line in the housing, and the door closer may further comprise a damping oil which is filled in the spring hole and a sealing unit which prevents the damping oil from leaking to the rack gear hole. 
     A receiving groove, which has an inner diameter smaller than the inner diameter of the spring hole and greater than the inner diameter of the rack gear hole, may be formed at the connection between the spring hole and the rack gear hole in the housing, the sealing unit may comprise a ring-shaped sealing member which is tightly put on the outer circumferential surface of the piston body portion and a washer which has an outer diameter greater than the inner diameter of the rack gear hole, is put on the piston body portion to be located between the sealing member and the coil spring, and is pressurized toward the rack gear hole by the coil spring, and the sealing member may be pressurized toward the rack gear hole by the washer and received in the receiving groove. 
     Advantageous Effects 
     According to the door closer of the present invention, the link shaft is biased to one side of the housing, and the coil spring which provides elastic force to close the door and the piston which compresses the coil spring are located on the other side of the housing. Thus, the housing of the door closer can be easily reduced in size. 
     Moreover, when a large coil spring is disposed inside the housing, the other side of the housing can be extended in the longitudinal direction, and thus the extended housing can be mounted to the door without having to changing the position of the link shaft with respect to the door. Thus, the occurrence of an operation error such as poor opening of the door can be reduced. 
     Furthermore, even when a large spring is mounted to the inside of the housing to increase the elastic force, the door closer can be attached to the door such that the position of the link shaft is maintained a constant distance from the rotation axis of the door. Thus, the door can be opened 180° without having to extend the length of the link. 
     In addition, when the door closer is mounted to the door, the link shaft which is biased to one side of the housing can be located closer to the rotation axis of the door, thereby increasing the efficiency of the door closer. 
    
    
     
       DESCRIPTION OF DRAWINGS 
         FIG. 1  is a cross-sectional view showing an example of a conventional door closer. 
         FIG. 2  is a perspective view showing a door to which a door closer in accordance with an embodiment of the present invention is mounted. 
         FIGS. 3 and 4  are cross-sectional views showing the inside of a housing of the door closer in  FIG. 2 , in which  FIG. 3  shows the state where the door is closed, and  FIG. 4  shows the state where the door is opened. 
         FIG. 5  is a cross-sectional view along the line V-V of  FIG. 3 . 
     
    
    
     MODE FOR INVENTION 
     Hereinafter, a door closer in accordance with an embodiment of the present invention will be described with reference to the accompanying drawings. The terminology used herein is for the purpose of properly describing preferred embodiments only and may be changed according to the intention or usage of a user or operator. Therefore, the terminology should be defined on the basis of the overall contents of this specification. 
       FIG. 2  is a perspective view showing a door to which a door closer in accordance with an embodiment of the present invention is mounted. Referring to  FIG. 2 , a door closer  20  in accordance with an embodiment of the present invention is attached to an upper surface of a hinged door  14  which is opened and closed by rotating with respect to a vertical rotation axis  17 . Specifically, a pair of flanges  22  are fixedly attached to a housing  21  of the door closer  20  by means of screws. One end of a link  25 , to which a pair of sticks are connected, is connected to an upper side of a door frame  2 , and the other end of the link  25  is connected to an upper end of a link shaft  30  which penetrates the housing  21 . 
       FIGS. 3 and 4  are cross-sectional views showing the inside of the housing of the door closer in  FIG. 2 , in which  FIG. 3  shows the state where the door is closed, and  FIG. 4  shows the state where the door is opened.  FIG. 5  is a cross-sectional view along the line V-V of  FIG. 3 . Referring to  FIGS. 3 to 5 , the door closer  20  in accordance with an embodiment of the present invention comprises a pinion gear  32 , a piston  35 , and a coil spring  43 , which are provided in the housing  21 . 
     The pinion gear  32  is formed on the outer circumferential surface of the link shaft  30  and coaxially rotates with the link shaft  30  with respect to the rotation axis of the link shaft  30  which is in parallel to the Z axis. The link shaft  30  is inserted and mounted into a link shaft hole  26  which formed in a direction parallel to the Z axis in the housing  21 . The piston  35  extends in the longitudinal direction of the housing  21 , i.e. in a direction parallel to the X axis, and is inserted into the housing  21  to reciprocate in the longitudinal direction of the housing  21 . The piston  35  comprises a rack gear portion  40  which is formed on one end thereof and engaged with the pinion gear  32 , a piston base portion  36  which is formed on the other end thereof, and a piston body portion  38  which connects the piston base portion  36  and the rack gear portion  40 . 
     The coil spring  43  is a compression spring which accumulates elastic energy upon compression and is put on the piston  35 , specifically, on the piston body portion  38 . When the piston base portion  36  moves towards the link shaft  30 , i.e., when the piston  35  in which the rack gear portion  40  is engaged with the pinion gear  32  moves in the positive (+) direction of the X axis, the coil spring  43  is compressed and accumulates elastic energy. At this time, the coil spring  43  elastically pressurizes the piston  35  such that the link shaft  30  rotates in a direction that closes the door  14  (see  FIG. 2 ). 
     The link shaft  30  and the pinion gear  32  are located on one side in the longitudinal direction of the housing  21  (in  FIG. 3 , the right side of the housing  21 ), and the coil spring  43  and the piston base portion  36  are located on the other side in the longitudinal direction of the housing  21  (in  FIG. 3 , the left side of the housing  21 ). The coil spring  43  and the piston  35  can be arranged to overlap each other in the housing  21 , and thus the inside of the housing  21  can be configured compactly and can be reduced in size. 
     In the housing  21 , a spring hole  23 , into which the coil spring  43  is inserted, and a rack gear hole  24 , through which the rack gear portion  40  reciprocates and which has an inner diameter smaller than the inner diameter of the spring hole  23 , are connected to each other in a line. The coil spring  43  is inserted into the spring hole  23 , and then the piston  35  is inserted into the inside of the housing  21  through the spring hole  23 . The rack gear portion  40  passes through the spring hole  23  and enters the rack gear hole  24 . One end of the coil spring  43  has an inner diameter that decreases at the boundary between the spring hole  23  and the rack gear hole  24 , and thus the movement of the coil spring  43  in the positive (+) direction of the X axis is restricted. When the piston base portion  36  moves in the positive (+) direction of the X axis, the other end of the coil spring  43  is pushed by the piston base portion  36  and moves in the same direction. Therefore, when the piston  35  moves in the positive (+) direction of the X axis, the coil spring  43  is compressed, and when the piston  35  moves in the negative (−) direction of the X axis, the coil spring  43  is expanded and restored. 
     According to the door closer  20  of the present invention, even when a large spring  43  is mounted in the housing  21  to increase the door-closing force, the door closer  20  can be attached to the door  14  such that the position of the link shaft  30  (see  FIG. 5 ) is maintained a constant distance from the rotation axis  17  of the door. Therefore, it is possible to fully open the door  14  to 180° without having to extend the length of the link  25 . Moreover, when the door closer  20  is mounted to the door  14 , the link shaft  30 , which is biased to one side of the housing  21 , can be located closer to the rotation axis  17  of the door, thereby increasing the efficiency of the door closer  20 . 
     The door closer  20  comprises a damping oil which is filled in the spring hole  23  and a sealing unit which prevents the damping oil from leaking to the rack gear hole  24 . The sealing unit comprises a sealing member  63  and a washer  60 . The sealing member  63  is typically made of rubber and has a ring shape that is tightly put on the outer circumferential surface of the piston body portion  38 . A U-packing having a U-shaped cross section may be used as the sealing member  63 . 
     The washer  60  is made of metal, has an outer diameter greater than the inner diameter of the rack gear hole  24 , and is put on the piston body portion  38  to be located between the sealing member  63  and the coil spring  43 . The washer  60  is located in the spring hole  23  and pressurized toward the rack gear hole  24  by the coil spring  43 . In the housing  21 , a receiving groove  18  having an inner diameter smaller than the inner diameter of the spring hole  23  and greater than the inner diameter of the rack gear hole  24  is formed at the connection between the spring hole  23  and the rack gear hole  24 , and the sealing member  63  is pressurized toward the rack gear hole  24  by the washer  60  and received in the receiving groove  18 . The washer  60  comprises an inner circumferential projection  61  which projects so as to push the sealing member  63  to the inside of the receiving groove  18 . Even when the piston  35  moves in the negative (−) direction of the X axis as well as in the positive (+) direction of the X axis, the washer  60  pressurized by the coil spring  43  pressurizes the sealing member  63  toward the rack gear hole  24 , and thus the sealing member  63  is not separated from the receiving groove  18 , thereby preventing the leakage of the damping oil. 
     Specifically, the entrance of the spring hole  23  formed on the other side of the housing  21  is sealed and closed by a cap  46 , and the boundary between the rack gear hole  24  and the spring hole  23  is sealed by a ring-shaped sealing member  63  made of rubber such that the only the piston body portion  38  can move. 
     Moreover, an oil passage hole  37  is provided in the piston base portion  36 . When the piston  35  moves in the positive (+) direction of the X axis, i.e., when the door  14  (see  FIG. 2 ) is opened, the damping oil present at the coil spring  43  in the spring hole  23  moves toward the cap  46  through the oil passage hole  37  to delay the movement speed of the piston  35 , thereby reducing the impact due to sudden opening of the door  14 . Meanwhile, when the piston  35  moves in the negative (−) direction of the X axis, i.e., when the door  14  is closed, the damping oil present at the cap  46  in the spring hole  23  moves toward the coil spring  43  through the oil passage hole  37  to delay the movement speed of the piston  35 , thereby reducing the impact due to sudden closing of the door  14 . 
     In the following, the door opening and closing operation by the door closer  20  will be described by sequentially referring to  FIGS. 3 and 4 . First, the door  14  (see  FIG. 2 ) is closed in  FIG. 3 , and when the door  14  starts to be opened, the pinion gear  32  formed in the link shaft  30  (see  FIG. 5 ) rotates in the counterclockwise direction, and as shown in  FIG. 4 , the piston  35  moves in the positive (+) direction of the X axis to the maximum, and the coil spring  43  is compressed to its maximum. 
     When the power to open the door  14  (see  FIG. 2 ) is cancelled in the state shown in  FIG. 4 , the coil spring  43  expands and elastically pressurizes the piston base portion  36  in the negative (−) direction of the X axis such that the piston  35  moves in the negative (−) direction of the X axis. Accordingly, the pinion gear  32  and the link shaft  30  (see  FIG. 5 ) rotate in the clockwise direction that the door  14  is closed. The piston  35  and the coil spring  43  are restored to the state shown in  FIG. 3 . 
     The invention has been described in detail with reference to preferred embodiments thereof. However, it will be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents. 
     INDUSTRIAL APPLICABILITY 
     The door closer of the present invention can be applied to a hinged door such as a front door, fire door, etc. of a house, apartment, officetel, etc.