Patent Publication Number: US-11384568-B2

Title: Locking device for hinged door

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a 371 National Stage Entry of PCT/KR2017/008838 filed Aug. 14, 2017, and PCT/KR2017/008838 claims priority to Korean Application 10-2016-0102999, filed Aug. 12, 2016. The contents of Korean Application 10-2016-0102999, filed Aug. 12, 2016, is incorporated by reference in its entirety. 
     TECHNICAL FIELD 
     The present invention relates to a locking device of a hinged door, and more specifically, to a locking device of a hinged door which allows a rotation-opening side of the hinged door to be pressed against a door frame at a plurality of points in a longitudinal direction by operating a rotatable lever installed on a door frame separately from a generally used main locking device for security, and more easily maintains a fixed state in a compressed-contact state, and is used as an auxiliary locking device of the hinged door. 
     BACKGROUND ART 
     Doors for a building entrance with a hinged door structure and various hinged doors installed indoor (referred to as the hinged door in the specification, including a hinged door for entrance and a hinged window) use various locking devices. As a general prior art of the locking device of a hinged door and a hinged window, locking devices with various structures, such as “Locking Device of Hinged Door” in Korean Registration Patent (B1) No. 10-1237681 (Feb. 26, 2013), “Locking Device of Hinged Door” in Korean Utility Model Registration (Y1) No. 20-0271060 (Apr. 9, 2002), and “Locking Device of Hook Direction Changing Type-Hinged Door” in Korean Utility Model Registration (Y1) No. 20-0476646 (Mar. 18, 2015), and the like, are disclosed. As shown in  FIGS. 1A to 1C , the locking devices in the prior art are in a locked state when a locking cylinder  1   s  installed on a rotation-opening side of the hinged door  1  installed on a door frame using a door hinge  1   b  installed on one side of a door frame  1   a  moves forward and is inserted into a cylinder pocket  1   sa  installed to face the door frame  1   a  (see  FIGS. 1B and 2Bb ) or are in a unlocked state when the locking cylinder  1   s  comes out of the cylinder pocket  1   sa  and moves backward toward the hinged door  1  (see  FIG. 1C ). An operation in which the locking cylinder  1   s  moves forward or backward from the cylinder pocket  1   sa  of the locking cylinder  1   s  may be performed by a manual rotation operation of a door handle  1   h  mounted on the hinged door  1  or other various electronic opening and closing devices. 
     However, since the conventional locking devices are used for security, the locking device only has a structure of maintaining a locked state in which a hinged door is locked on a door frame and performs a locking function at one point of the hinged door in a longitudinal direction of the hinged door as shown in  FIG. 1A . As shown in  FIG. 2B  which is an enlarged transverse sectional view illustrating the locked state in which the hinged door is closed, an operation gap Δg is necessary between the locking cylinder  1   s  and the cylinder pocket  1   sa  for smooth operation, and the hinged door is separated from the door frame by a gap when strong wind blows, and thus it is difficult to maintain a good airtight state, and further, it causes rattling and noise. 
     Further, use of various electronic opening and closing devices as the locking device of a hinged door has been increasing recently. In the case of the electronic opening and closing device (an electronic door lock), when the locked state is released due to external strong electric shock or password exposure, an intrusion path to go inside may be provided, and thus a separate locking device is further required. 
     Technical Problem 
     The present invention is directed to providing a locking device of a hinged door capable of being used as an auxiliary locking device that allows a gap between the hinged door and a door frame to be controlled in order to provide a better airtight condition after the hinged door is closed and locked by a general locking device. 
     The present invention is directed to providing a locking device of a hinged door capable of being locked or opened by rotating a lever only from an indoor space divided by a hinged door in order to solve a security problem of a locking device generally used for a hinged door. 
     Technical Solution 
     One aspect of the present invention provides a locking device of a hinged door installed between a rotation opening side of the hinged door, which is installed in a door frame using a door hinge installed on one side of the door frame, and a door frame, the locking device including a plurality of close contact guide plates installed on the rotation opening side of the hinged door to be separated from each other in a longitudinal direction; a plurality of pressure rolls configured to achieve a compressed locked state by pulling the rotation opening side of the hinged door toward the door frame while in contact with the close contact guide plates in a state in which the rotation opening side of the hinged door is closed on the door frame, and installed on the door frame to be separated from each other in the longitudinal direction to achieve the uncompressed locked state between the rotation opening side of the hinged door and the door frame in a noncontact state with the close contact guide plates; a driving plate installed in the sliding pocket, provided in the door frame in the longitudinal direction so that the pressure rolls  120  are slidably installed on the door frame in the longitudinal direction, and having the plurality of pressure rolls provided in the longitudinal direction; and a switching device configured to induce a longitudinal movement displacement corresponding to that of the driving plate by being engaged with at least one first pressure roll of the pressure rolls installed on the driving plate to provide the longitudinal movement displacement, configured to generate a longitudinal movement displacement of the second pressure roll induced by the longitudinal movement displacement of the driving plate, and installed on the door frame to allow the second pressure roll to be switched between a contact compressed state position with the close contact guide plates and the contact compressed state position by the longitudinal movement displacement, wherein the switching device includes a housing fixedly installed on the door frame, a rotatable lever installed in the housing by a first hinge pin to rotate on a front surface of the housing in the longitudinal direction, a conversion link bar having one end portion connected at a predetermined position between the first hinge pin of the rotatable lever and a rotation end portion, a sliding block connected to the other end portion of the conversion link bar by a third hinge pin to slide linearly in the housing in the longitudinal direction according to a longitudinal rotation operation of the rotatable lever, a cover plate configured to cover a rear surface of the housing to limit a displacement of the sliding block by a longitudinal rotation operation of the rotatable lever to a longitudinal linear sliding displacement in the housing and having a hole formed in the longitudinal direction to guide the longitudinal linear sliding displacement and having a size such as to limit the height of the longitudinal linear sliding displacement, and a slider fork integrated with the sliding block, provided to protrude to an outside of a sliding guide groove formed in the cover plate, and sliding along the sliding guide groove in the longitudinal direction while being engaged with the first pressure roll. 
     The switching device further includes a rotatable lever releasing blocking unit for blocking release of the rotatable lever before external force greater than a predetermined strength is applied to the rotatable lever to rotate the rotatable lever so as to maintain the second pressure roll to be fixed at a contact compressed state position with the close contact guide plates or a noncontact and uncompressed state position. 
     To provide a first rotatable lever releasing blocking unit which is one of the rotatable lever releasing blocking units, a neutral state in which the third hinge pin, the first hinge pin, and a second hinge pin are sequentially disposed on an upward inclined straight line is made while the rotatable lever composing the switching device rotates upward about the first hinge pin so that the second hinge pin is positioned above the first hinge pin, a sliding guide groove upper limit line U.L. is set at a position limiting a free further upward movement of the sliding block and the slider fork before the neutral state, additional upward movements of the sliding block and the slider fork are elastically received by elastic compression deformation of an upper region of the cover plate induced by an upward displacement exceeding the sliding guide groove upper limit line U.L. while the rotatable lever rotates upward to reach the neutral state, and the sliding block connected to the link bar and the slider fork are moved slightly downward by elastically pressed elastic recovery deformation of the upper region of the cover plate in a section in which the rotatable lever additionally rotates upward to reach the vertically upright state beyond the neutral state, and thus a position of a sliding guide groove upper limit line U.L. of the sliding guide groove is set to limit a reverse direction operation of the rotatable lever, the sliding block, and the slider fork integrated with the sliding block until external force strong enough to re-perform elastic compression deformation of the upper region of the cover plate is applied to the rotatable lever according to slight upward movements of the sliding block and the slider fork for recovering the slight downward movement. 
     To provide a second rotatable lever releasing blocking unit, which is another one of the rotatable lever releasing blocking units, the rotatable lever composing the switching device rotates downward about the first hinge pin to reach a vertically downward state so that the second hinge pin is positioned below the first hinge pin and a state in which the first hinge pin, the second hinge pin, and the third hinge pin are disposed downward sequentially in a triangular structure is made, a sliding guide groove lower limit line L.L. is set at a position limiting additional free downward movements of the sliding block and the slider fork before the vertically downward state, additional downward movements of the sliding block and the slider fork are elastically received through elastic compression deformation induced by a downward displacement exceeding the sliding guide groove lower limit line L.L. while the rotatable lever moves downward to reach the vertically downward state, a lever downward moving unit and a lever recovery unit are provided between the housing and the rotatable lever to induce a further slight downward movement and recovery of the rotatable lever while the rotatable lever rotates downward to reach the vertically downward state beyond the sliding guide groove lower limit line L.L. which limits free downward movements of the sliding block and the slider fork, and therefore reverse operations of the rotatable lever, the sliding block, and the slider fork integrated with the sliding block are limited until elastic compression deformation of the cover plate-lower region by forcible further slight downward movement of the rotatable lever is re-performed by the rotatable lever rotated from the lever recovery unit through the lever downward moving unit in a reverse direction. 
     The lever downward moving unit includes a catching protrusion protruding from a side wall of the housing, a catching projection provided in an entrance portion of the catching groove formed in a side surface of the rotatable lever to be concave to correspond to the catching protrusion, and a long hole portion, which is a hinge hole of the rotatable lever to which the first hinge pin is fastened to receive downward movement of the rotatable lever performed when the catching projection comes out of a lower end portion of the catching protrusion, includes a vertical hole for the first hinge, wherein the lever recovery unit includes a catching protrusion expanded mounting portion in the catching groove provided to receive elastic recovery deformation of the cover plate-lower region. 
     Advantageous Effects 
     According to the present invention, the locking device can provide a better airtight condition and does not cause noise due to rattling of a hinged door even in strong winds by providing an auxiliary locking device for controlling a gap between a hinged door and a door frame so that the hinged door is closely pressed against the door frame at a plurality of points in a longitudinal direction after the hinged door is closed and locked by a general locking device. 
     Particularly, a rotatable lever releasing blocking unit for blocking release of the rotatable lever before external force greater than a predetermined strength is applied to the rotatable lever to rotate the rotatable lever is additionally provided, and thus an effect of maintaining a second pressure roll of a switching device to be fixed at a contact compressed state position with the close contact guide plates or a noncontact and uncompressed state position can be provided. 
     Further, according to the present invention, a security problem of an electronic locking device generally used for a hinged door can be solved by an auxiliary locking device that allows locking or opening only by rotating a lever from an indoor space divided by a hinged door. 
    
    
     
       DESCRIPTION OF DRAWINGS 
         FIG. 1A  is a front view showing a hinged door installed in a door frame using a door hinge installed on one side of the door frame,  FIG. 1B  is a cross-sectional view taken along line a-a′ of  FIG. 1A  in a state of being locked by a general door handle, and  FIG. 1C  is a cross-sectional view taken along line a-a′ of  FIG. 1A  in a state of being unlocked by a door handle. 
         FIG. 2A  is a front view showing a state in which a locking device of a hinged door according to the present invention is installed between a door frame and a rotation-opening side of the hinged door installed in the door frame using a door hinged installed on one side of the door frame,  FIG. 2B  is a cross-sectional view taken along line a-a′ of  FIG. 2A  in a locked state, and  FIG. 2C  is a cross-sectional view taken along line b-b′ of  FIG. 2A  in a uncompressed/locked state, and  FIG. 2D  is a cross-sectional view taken along line b-b′ of  FIG. 2A  in a compressed/locked state. 
         FIG. 3A  is a view showing an operation state in which, when the locking device of a hinged door according to the present invention is installed on one side of the door frame, an operating plate with a pressing roll slides from a door frame side in a longitudinal direction by rotating a rotatable lever in a vertical direction so as to switch a uncompressed/locked state to a compressed/locked state, and  FIG. 3B  is a view showing an operation state in which a plurality of close contact guide plates, which are installed on a rotation opening side of the hinged door to be separated from each other in the longitudinal direction, are pulled toward the door frame side when the operation plate with the pressing roll shown in  FIG. 3A  slides from the door frame side in the longitudinal direction so as to switch from the uncompressed/locked state to the compressed/locked state. 
         FIGS. 4A to 4E  are exploded perspective views showing processes of an operation state of the switching device, which is a switching device composing the locking device of a hinged door according to the present invention, installed on the door frame to switch a pressure roll between a contact-compressed state position with the close contact guide plate and a noncontact-uncompressed state position through a longitudinal movement displacement. 
         FIGS. 5A and 5B  are views for describing necessity of a rotatable lever rotation blocking unit for blocking a reverse operation of the rotatable lever to maintain the pressure roll to be fixed at a contact compressed state (a compressed/blocked state) position with the close contact guide plate or a noncontact uncompressed state (a uncompressed/locked state) position in a switching device composing the locking device of a hinged door according to the present invention. 
         FIGS. 6A to 6E  are cross-sectional views showing processes of an operation state in which a contact compressed state (a compressed/locked state) is performed by rotating the rotatable lever upward to move the sliding block and the slider fork upward while the locking device of a hinged door according to the present invention is installed on one side of the door frame, and  FIG. 6F  is a cross-sectional view showing a state in which an upwardly fixed state of the sliding block and the slider fork is released by the reverse operation of the rotatable lever in the upwardly fixed state of the sliding block and the slider fork (a contact compressed state, a compressed/locked state). 
         FIGS. 7A to 7E  are cross-sectional views schematically showing processes of an operation state in which a contact-compressed state (a compressed/locked state) is achieved by rotating the rotatable lever upward to move the sliding block and the slider fork upward while the locking device of a hinged door according to the present invention is installed on one side of the door frame,  FIG. 7F  is a cross-sectional view schematically showing that an upwardly fixed state of the sliding block and the slider fork is released by a reverse operation of the rotatable lever in an upwardly fixed state (a contact-compressed state, a compressed/locked state) of the sliding block and the slider fork,  FIGS. 7G to 7J  are cross-sectional views schematically showing processes in which the sliding block and the slider fork reach a downwardly fixed state (a noncontact uncompressed state is maintained, a uncompressed/locked state) by rotating the rotatable lever downward, and the downwardly fixed state is maintained, and  FIG. 7K  is a cross-sectional view showing a state in which the rotatable lever is forcibly moved downward to rotate the rotatable lever in the reverse direction while the sliding block and the slider fork are in a downwardly fixed state (a noncontact uncompressed state, a uncompressed/locked state). 
     
    
    
     MODES OF THE INVENTION 
     Hereinafter, embodiments that are easily performed by those skilled in the art will be described in detail with reference to the accompanying drawings. However, the embodiments of the present invention may be achieved in several different forms and are not limited to the embodiments described herein. 
     According to the present invention, a locking device is, as shown in  FIGS. 2A and 2C , as an auxiliary locking device of a hinged door  1  installed between a rotation opening side of the hinged door  1  installed in a door frame and a door frame  1   a  using a door hinge  1   b  installed on one side of the door frame and, as shown in  FIGS. 2A  to  7 K, provided is an auxiliary locking device which includes a plurality of close contact guide plates  130  installed on a rotation opening side of the hinged door  1  to be separated from each other in a longitudinal direction, a plurality of pressure rolls  120  which achieve a compressed-locked state by pulling the rotation opening side of the hinged door  1  toward a door frame  1   a  when in contact with the close contact guide plate  130  in a state in which the rotation opening side of the hinged door  1  is closed to the door frame  1   a  and which are installed on the door frame  1   a  to be separated from each other in a longitudinal direction so that the rotation opening side of the hinged door  1  achieves a uncompressed-locked state on the door frame  1   a  in a noncontact state with the close contact guide plates  130 , a driving plate  110  installed in a sliding pocket  110   a  provided in the door frame  1   a  in the longitudinal direction so that the pressure rolls  120  slidably move toward the door frame  1   a  in the longitudinal direction and provided with the pressure rolls  120  formed on the front surface thereof to be separated from each other in the longitudinal direction, and a switching device  100  which induces a longitudinal movement displacement H corresponding to that of the driving plate  110  by being engaged with a first pressure roll  120   a  of the pressure rolls  120  installed on the driving plate  110  to provide the longitudinal movement displacement H, generates a longitudinal movement displacement H of a second pressure roll  120   b  induced by the longitudinal movement displacement H of the driving plate  110 , and is installed in the door frame  1   a  to allow the second pressure roll  120   b  to switch between a contact compressed state position with the close contact guide plates  130  and a noncontact-uncompressed state position through the longitudinal movement displacement H. 
     In this case, the switching device  100  includes a housing  10  fixedly installed on the door frame  1   a , a rotatable lever  30  installed in the housing  10  by a first hinge pin  32  to be rotated on a front surface of the housing in the longitudinal direction, a conversion link bar  40  having one end portion connected at a predetermined position between a first hinge pin  32  of the rotatable lever  30  and a rotating end portion by a second hinge pin  40   a , a sliding block  20  connected to the other end portion of the conversion link bar  40  by a third hinge pin  40   b  and sliding linearly in the housing  10  in the longitudinal direction according to a longitudinal rotation operation of the rotatable lever  30 , a cover plate  50  for covering a rear surface of the housing  10  to limit a displacement of the sliding block  20  caused by the longitudinal rotation operation of the rotatable lever  30  to a longitudinal linear sliding displacement in the housing  10  and including a sliding guide groove  52  for guiding the longitudinal linear sliding displacement and having a hole formed in the longitudinal direction in a size limiting the height of the sliding displacement, and a slider fork  25  integrated with the sliding block  20 , protruding to the outside of the sliding guide groove  52  formed in the cover plate  50 , and sliding along the sliding guide groove  52  in the longitudinal direction while being engaged with the first pressure roll  120   a.    
     In this case, unlike the second pressure roll  120   b , the first pressure roll  120   a  is an element engaged with the slider fork  25 , not an element which is in contact with the close contact guide plates  130 , and thus the name of the element may vary, but functions of the first pressure roll  120   a  and the second pressure roll  120   b  of the plurality of pressure rolls  120  may be changed when an installation position of the switching device  100  installed in the door frame  1   a  is changed, and thus a unified name is used in the present specification, and the pressure rolls  120  may be a cylindrical roller having a touched outer circumferential surface freely rotating about a central portion so that excessive frictional force or frictional noise is not generated in a process of being engaged with the slider fork  25  or in a process of moving while in contact with the close contact guide plate  130 . 
     Further, a rotatable lever releasing blocking unit for blocking a releasing operation of the rotatable lever  30  to rotate the rotatable lever  30  before external force greater than a predetermined strength is applied to the rotatable lever  30  may be additionally provided in the switching device  100  in order for the second pressure roll  120   b  to maintain a fixed state at a contact compressed state position with the close contact guide plate  130  or a noncontact-uncompressed state position. 
     In this case, to provide the rotatable lever releasing blocking unit, which is one of the rotatable lever releasing blocking unit, while the rotatable lever  30  composing the switching device  100  rotates upward about the first hinge pin  32  so that the second hinge pin  40   a  is positioned above the first hinge pin  32 , the third hinge pin  40   b , the first hinge pin  32 , and the second hinge pin  40   a  are sequentially disposed in a neutral state N.A. to be disposed in a straight line inclined upward, and a sliding guide groove upper limit line U.L. is set at a position limiting the additional free upward movements of the sliding block  20  and the slider fork  25  before the neutral state N.A. A further upward movement of the sliding block and the slider fork are elastically received by elastic compression deformation of an upper region  50   b  of the cover plate  50  induced by an upward displacement exceeding an upper line of the sliding guide groove while the rotatable lever  30  rotates upward to reach the neutral state N.A., and the sliding block  20  and the slider fork  25  connected to the link bar  40  are moved slightly downward using the third hinge pin  40   b  by elastic recovery deformation of the upper region  50   b  of the elastically pressed cover plate  50  in a section in which the rotatable lever is additionally rotated upward to a vertically upright state beyond the neutral state. A sliding guide groove upper limit line U.L. position of the sliding guide groove  52  may be set to limit a reverse operation (downward rotation and downward movement) of the rotatable lever  30 , the sliding block  20 , and the slider fork  25  integrated with the sliding block  20  until external force strong enough for elastic compression deformation of the upper region  50   b  of the cover plate  50  to be re-performed according to slight upward movement of the sliding block and the slider fork for recovering slight downward movement is applied to the rotatable lever  30 . 
     Further, to provide a second rotatable lever releasing blocking unit, which is another one of the rotatable lever releasing blocking units, while the rotatable lever  30  composing the switching device  100  rotates downward about the first hinge pin  32  to a vertically downward state so that the second hinge pin  40   a  is positioned below the first hinge pin  32 , the first hinge pin  32 , the second hinge pin  40   a , and the third hinge pin  40   b  are disposed downward sequentially in a triangular structure, and a sliding guide groove lower limit line L.L. is set at a position limiting additional free upward moving of the sliding block  20  and the slider fork  25  before the vertically downward state. A further downward movement of the sliding block  20  and the slider fork  25  are elastically received by elastic compression deformation of the lower region  50   a  of the cover plate  50  induced by an upward displacement exceeding the sliding guide groove lower limit line L.L. while the rotatable lever  30  rotates downward to reach the vertically downward state, and a lever downward moving unit and a lever recovery unit may be provided between the housing and the rotatable lever to induce forcible further slight downward movement and recovery of the rotatable lever  30  in a downward rotation section until the rotatable lever  30  reaches the vertically downward state beyond the sliding guide groove lower limit line L.L. state in which free downward movement of the sliding block  20  and the slider fork  25  is limited, and therefore, a reverse operation (upwardly rotating and upwardly moving) of the rotatable lever  30 , the sliding block  20 , and the slider fork  25  integrated with the sliding block  20  is limited until elastic compression deformation of the cover plate-lower region  50   a  is re-performed by the forcible further slight downward movement of the rotatable lever  30  by the rotatable lever  30  rotated from the lever recovery unit through the lever downward moving unit in a reverse direction. 
     In this case, the lever downward moving unit includes a catching protrusion  10   s  protruding from a side wall of the housing  10 , a catching projection  30   sa  formed on a side surface of the rotatable lever  30  to be concave to correspond to the catching protrusion  10   s , and a long hole portion  30   e  which is a hinge hole of the rotatable lever  30  to which the first hinge pin  32  is fastened to allow the rotatable lever  30  to move downward when the catching projection  30   sa  comes out of a lower end portion of the catching protrusion  10   s  and includes a vertical gap for the first hinge pin  32 , and the lever recovery unit includes a catching protrusion expanded mounting portion  30   se  formed in the catching groove  30   s  to receive elastic recovery deformation of the cover plate-lower region  50   a.    
     Hereinafter, detailed configurations and operation processes of the embodiments of the present invention will be described in more detail with reference to the accompanying drawings. 
     As shown in  FIG. 2A , the locking device of the hinged door according to the present invention is installed between a rotation opening side of the hinged door  1  and the door frame  1   a , and as shown in  FIG. 2B , which shows a cross-sectional view in a state of being locked by a door handle  1   h  in the front view of  FIG. 2A  as a cross-sectional view taken along line a-a′, in the state of being locked by the door handle  1   h , a predetermined size of an operation gap (Δg) is required between the locking cylinder  1   s  and the cylinder pocket  1   sa , and thus a gap is formed between the rotation opening side of the hinged door  1  and the door frame  1   a .  FIGS. 2C and 2D  are shown as drawings for showing an operation state by an auxiliary locking device according to the present invention in a transverse section taken along line b-b′ in the front view of  FIG. 2A .  FIG. 2C  is a cross-sectional view taken along line b-b′ of  FIG. 2A  and shows a state of being uncompressed (by the auxiliary locking device according to the present invention) and locked (by the door handle), and  FIG. 2D  is a cross-sectional view taken along line b-b′ of  FIG. 2A  and shows a cross-sectional state in a state of being pressed (by an upward rotating operation of the rotatable lever  30  of the switching device  100  composing the auxiliary locking device according to the present invention) and locked (by a door handle). 
     As shown in a perspective view for the door frame of  FIG. 3A , to achieve a conversion operation state shown in transverse sections of  FIGS. 2C and 2D , the driving plate  110  in which the first pressure roll  120   a  is installed slides in the sliding pocket  110   a , which is provided in the door frame  1   a  in the longitudinal direction, in the longitudinal direction by rotating the rotatable lever  30  upward in a state in which the locking device of the hinged door according to the present invention is installed on one side of the door frame to provide a longitudinal movement displacement H and to generate a longitudinal movement displacement H of the second pressure roll  120   b  induced by the longitudinal movement displacement H of the driving plate  110 . 
     Therefore, as shown in  FIG. 3B  showing the plurality of close contact guide plates  130 , which are installed on a rotation opening side of the hinged door  1  and the door frame  1   a  to be separated from each other in a longitudinal direction, in the longitudinal section, the plurality of close contact guide plates  130  provided on the rotation opening side of the hinged door  1  to be in contact with the second pressure roll  120   b  are pulled toward the door frame by the longitudinal movement displacement H of the second pressure roll  120   b  to switch from the noncontact-uncompressed state (a uncompressed/locked state) position to the contact compressed state (a compressed/locked state) position. 
     Hereinafter, in the switching device composing the locking device of the hinged door according to the embodiments of the present invention, an operation state of the switching device  100  for switching between the contact compressed state position with the close contact guide plates  130  and the noncontact uncompressed state position by the longitudinal movement displacement of the second pressure roll  120   b  will be described in more detail with reference to cross-sectional views of processes of the operation states shown in  FIGS. 6A to 6E  and the exploded perspective views of processes of the switching device  100  shown in  FIGS. 4A to 4E . 
       FIGS. 4A and 6A  show a state in which the rotatable lever  30  composing the switching device  100  is installed by the first hinge pin  32  to rotate from a front surface of the housing  10  in a longitudinal direction and rotates downward to be fixed to the lowermost side (−90° from a horizontal surface). In this case, when the rotatable lever  30  rotates upward about the first hinge pin  32 , the above-described state is changed to a state shown in  FIG. 4B , and when a further upward rotation is performed, as shown in  FIGS. 4C and 6B  (0° from a horizontal surface) and  FIGS. 4D, 6C, and 6D , one end portion of the conversion link bar  40  is connected with the second hinge pin  40   a  at a predetermined position between the first hinge pin  32  of the rotatable lever  30 , and the other end portion thereof is connected by the third hinge pin  40   b , and thus the sliding block  20  slides upward in the housing  10  according the upward rotation operation of the rotatable lever  30 . As shown in  FIGS. 4E and 6E , the rotatable lever  30  rotates upward from the front surface of the housing  10  to be fixed to the uppermost side (+90° from a horizontal surface). 
     Further, according to one exemplary embodiment of the present invention, a unit for maintaining the second pressure roll  120   b  to be fixed to the contact compressed state position (for example, a uppermost rotated state) with the close contact guide plates  130  or a noncontact uncompressed state position (for example, a lowermost rotated state) is required. For example, a rotatable lever releasing blocking unit for blocking release of the rotatable lever  30  before external force greater than a predetermined strength is applied to the rotatable lever  30  to rotate the rotatable lever  30  in a reverse direction while in the lowermost rotated state (−90° from a horizontal surface) and the uppermost rotated state (+90° from a horizontal surface, see  FIG. 4E ) is additionally provided for the switching device  100 . 
     In this case, according to one exemplary embodiment of the present invention, the first rotation lever releasing blocking unit, which is one of the rotatable lever releasing blocking units, is provided to maintain the uppermost rotated state (a position (b) of  FIG. 6E , a high position state). In this case, as shown in  FIGS. 4B, 4C, 6B, 7B, and 7C , while the rotatable lever  30  composing the switching device  100  rotates upward about the first hinge pin  32  so that the second hinge pin  40   a  is positioned above the first hinge pin  32  (section [A] operation of the rotatable lever shown in  FIG. 4D ; regular joint represented as regions in  FIGS. 6D, 6C, 6D, 7B, and 7C ), as shown in  FIGS. 4D, 6D, and 7D , the third hinge pin  40   b , the first hinge pin  32 , and the second hinge pin  40   a  are in a neutral state N.A. to be disposed in a sequentially upwardly inclined straight line. As shown in  FIGS. 6C and 7C , a sliding guide groove upper limit line U.L. is set at a position limiting additional free upward movement of the sliding block  20  and the slider fork  25  before the neutral state N.A., and the compression deformation of the upper region  50   b  of the cover plate  50  starts (represented as ‘deformation starting point’ in  FIG. 7C ) so that additional upward movements of the sliding block  20  and the slider fork  25  are elastically received (the sliding block  20  and the slider fork  25  move upward to a neutral position—a position (n) of  FIG. 6D ) through elastic compression deformation (maximum compression deformation of  FIG. 6D =Δt1; ‘0.619 mm’ of  FIG. 7D  showing the embodiment) of the upper region  50   b  of the cover plate  50  induced by an upward displacement exceeding the sliding guide groove upper limit line U.L. while the rotatable lever  30  moves upward to the neutral state N.A. of  FIGS. 4D, 6D , and  7 D. As shown in  FIGS. 4E, 6E, and 7E , in a section in which the rotatable lever additionally rotates upward until the vertically upright state (a uppermost rotated state; +90° from a horizontal surface) beyond the neutral state, the sliding block  20  and the slider fork  25  connected to the link bar  40  through the third hinge pin  40   b  is moved slightly downward (the third hinge pin  40   b  connected by the conversion link bar slides downward rather than upward in a section in which the second hinge pin  40   a  rotates upward about the first hinge pin  32  according to a kinematic structure of the hinge pin link, which is represented as a reverse joint, a section [B] operation of the rotatable lever shown in  FIG. 4D ; the sliding block  20  and the sliding fork  25  slightly move downward to a high position—a position (b) of  FIG. 6E ) by the elastic recovery deformation (depressure; compression deformation=Δt2&lt;Δt1; 0.1 mm of  FIG. 7E  schematically showing a device of the embodiment in which the rotation diameter a from the first hinge pin to the projection is 83 mm) of the upper region  50   b  of the elastically pressed cover plate  50 , through the elastic compression deformation (Δt1 of  FIG. 6F ; ‘0.619 mm’ of  FIG. 7F  schematically showing a device of the embodiment in which rotation diameter a from the first hinge pin to the catching projection is 83 mm) of the upper region  50   b  of the cover plate  50  caused when the sliding block  20  and the sliding fork  25  for recovering the slight downward movement (consequentially, the upper region  50   b  of the cover plate  50  is uncompressed) caused during the upward rotation process slightly move upward, until external force F strong enough to be re-performed as shown in  FIGS. 6F and 7F  is applied to the rotatable lever  30 , a reverse operation of the sliding block  20 , and the slider fork  25  integrated with the sliding block  20  (section [B] operation of the rotatable lever shown in  FIG. 4E , downward rotation of the rotatable lever shown in  FIGS. 6F and 7F , and downward movement of the sliding block and the slider fork integrated with the sliding block; that is release of the rotatable lever  30 ), is limited. 
     That is, in a state in which the sliding block  20  and the slider fork  25  are in an upwardly fixed state (a contact compressed state, a compressed/locked state), to release the state in which the sliding block  20  and the slider fork  25  are in an upwardly fixed state by a reverse operation of the rotatable lever  30 , the reverse strong external force F is applied to the rotatable lever  30  as shown in  FIGS. 6F and 7F , and thus a fixed state is stably maintained. 
     Further, a sliding guide groove upper limit line U.L. of the sliding guide groove  52  is set at a predetermined position of the upper region  50   b  of the cover plate  50  made of the elastic material, and the appropriate strength of the external force required for locking or unlocking to be applied to the rotatable lever  30  is set, and thus the first rotatable lever releasing blocking unit is provided. 
     Meanwhile, the rotatable lever releasing blocking unit is required even in a section in which the rotatable lever  30  rotates about the first hinge pin  32  downward to reach a vertically downward state, as shown in  FIG. 5A , and thus, due to a structure in which an installation axis planar surface (R.A.) of the first hinge pin  32  is disposed in front of an installation axis planar surface (V.S.) of the third hinge pin  40   b  connected with the sliding block  20 , that is, is disposed in front of a longitudinal linear sliding axis planar surface of the third hinge pin  40   b  by Δd (see  FIG. 5A ) (that is, a structure in which a neutral state in which three hinge pins are in a straight line is inclined by an angle θ), in a section in which the rotatable lever  30  rotates about the first hinge pin  32  upward to reach a vertically upright state, a neutral state N.A. is formed on a front surface of the housing  10  so as to form a reverse joint region r. On the contrary, in a section in which the rotatable lever  30  rotates about the first hinge pin  32  downward, a neutral state N.A. is not formed on a front surface of the housing to reach a vertically downward state (as shown in  FIG. 5B , a virtual downward neutral state N.A. and a virtual reverse joint region r′ are formed on a rear surface of the housing beyond the vertically downward state). Therefore, there is a need to use the rotatable lever releasing blocking unit in another structure. 
     To solve the problem, in the exemplary embodiment of the present invention, a lowermost rotated state of the second rotatable lever releasing blocking unit, which is another one of the rotatable lever releasing blocking units, is provided to maintain a lowermost rotated state (a low position state—a position (a) of  FIG. 6A ), and as the second rotatable lever releasing blocking unit, the rotatable lever  30  composing the switching device  100  rotates about the first hinge pin  32  downward to a vertically downward state from  FIG. 7G  to  FIG. 7J  so that the second hinge pin  40   a  is positioned below the first hinge pin  32 , and thus the first hinge pin  32 , the second hinge pin  40   a , and the third hinge pin  40   b  are disposed downward sequentially in a triangular structure. A sliding guide groove lower limit line L.L. is set at a position limiting additional free downward movements of the sliding block  20  and the slider fork  25  before the vertically downward state, and thus a further downward movement of the sliding block  20  and the slider fork  25  is elastically received by elastic compression deformation of the lower region  50   a  of the cover plate  50  induced by a downward displacement exceeding the sliding guide groove lower limit line L.L. while the rotatable lever  30  rotates downward to reach the vertically downward state, and the lever downward moving unit and the lever recovery unit may be provided between the housing  10  and the rotatable lever  30  to induce the rotatable lever  30  to forcibly induce additional slight downward movement and recovery of the rotatable lever  30  while the rotatable lever  30  rotates downward to the vertically downward state beyond the sliding guide groove lower limit line L.L. state in which free downward movements of the sliding block  20  and the slider fork  25  are limited. Therefore, the reverse operations (upward rotation and upward movement) of the rotatable lever  30 , the sliding block  20 , and the slider fork  25  integrated with the sliding block  20  are limited by the rotatable lever  30  rotated from the lever recovery unit to the opposite direction through the lever downward moving unit until elastic compression deformation of the cover lower region  50   a  is re-performed by forcible further slight downward movement of the rotatable lever  30 . 
     In this case, as described above, the lever downward moving unit includes a catching protrusion  10   s  protruding from a side wall of the housing  10 , a catching projection  30   sa  provided on an entrance portion of the catching groove  30   s  formed on a side surface of the rotatable lever  30  to be concave to correspond to the catching protrusion  10   s , and a long hole portion  30   e , which is a hinge hole of the rotatable lever  30  to which the first hinge pin  32  is fastened to receive downward movement of the rotatable lever  30  performed when the catching projection  30   sa  comes out of a lower end portion of the catching protrusion  10   s , including a vertical gap Δr for the first hinge pin  32 , and the lever recovery unit includes a catching protrusion expanded mounting portion  30   se  provided in the catching groove  30   s  to receive elastic recovery deformation of the cover plate-lower region  50   a.    
     In this case, the vertical gap Δr of the long hole portion  30   e  may be greater than a height Δs of the catching projection  30   sa  (see  FIGS. 4B, 6A, and 7J ). 
     Hereinafter, specific operation processes of the lever downward moving unit and the lever recovery unit will be described in more detail with reference to  FIGS. 7G to 7K . 
     As shown in  FIG. 7G , the rotatable lever  30  composing the switching device  100  rotates downward about the first hinge pin  32  so that the second hinge pin  40   a  is positioned below the first hinge pin  32 , and the first hinge pin  32 , the second hinge pin  40   a , and the third hinge pin  40   b  are disposed downward sequentially in a triangular structure. When the rotatable lever  30  reaches the sliding guide groove lower limit line L.L. (a deformation starting point), which is a position limiting additional free downward movements of the sliding block  20  and the slider fork  25  before the vertically downward state, a downward displacement exceeding the sliding guide groove lower limit line L.L. is achieved by the elastic compression deformation (‘0.5 mm’ deformation of  FIG. 7H  which schematically shows a device according to the embodiment in which a rotation diameter a from the first hinge pin to the catching projection  30   sa  is 83 mm) of the lower region  50   a  of the cover plate while the rotatable lever  30  moves downward to reach a process of  FIG. 7H , and therefore, the additional downward movements of the sliding block  20  and the slider fork  25  are elastically received. 
     While in a section in which the rotatable lever  30  rotates downward to reach the vertical lower state beyond the sliding guide groove lower limit line L.L. limiting free downward movement of the sliding block  20  and the slider fork  25  (see  FIGS. 7H, 7I, and 7J ), forcible further slight downward movement of the rotatable lever  30 , that is, the forcible further slight downward movement of the first hinge pin  32  should be induced, and thus the catching projection  30   sa  formed in an entrance portion of the catching groove  30   s  formed in a side surface of the rotatable lever  30  rotating downward to be concave is initially caught on a lower end portion of the catching protrusion  10   s  protruding from a side surface of the housing  10 , and a further downward movement of the rotatable lever  30  generated when the catching projection  30   sa  at a height of Δs forcibly and additionally comes out of a lower end portion of the catching protrusion  10   s  is received in the long hole portion  30   e  including a vertical gap (Δr&gt;Δs) for the first hinge pin  32  as a hinge hole of the rotatable lever  30  to which the first hinge pin  32  is fastened. The vertical gap shown in the long hole portion  30   e  of the hinge hole for the first hinge pin  32  is represented as an upper gap  30   e   1  and a lower gap  30   e   2  as symbols in the drawings. 
     Accordingly, the first hinge pin  32  additionally and forcibly moves downward by a height (As) of the protrusion of the catching projection  30   sa  determining a catching state with the lower end portion of the catching protrusion  10   s  protruding from a side wall of the housing  10 , and in this case, the first hinge pin  32  moves while the upper gap  30   e   1  of the long hole portion  30   e  of the hinge hole is decreased (0.4→0.208 mm), the lower gap  30   e   2  is increased (0→0.192 mm), and the additional slight downward movement of the first hinge pin  32  induces the sliding block  20  and the slider fork  25  connected through the conversion link bar  40  connected through the second hinge pin  40   a  and the third hinge pin  40   b  connected with the other end of the conversion link bar  40  to be moved slightly further downward by additional elastic compression deformation of the lower region  50   a  of the cover plate  50  (‘0.657 mm’ deformation of  FIG. 7I  schematically showing a device according to the embodiment in which a rotation diameter a from the first hinge pin  32  to the catching projection  30   sa  is 83 mm). 
     When the rotation of the rotatable lever  30  is finished in the additional elastic compression state, the state becomes a unstable state due to elastic force (elastic force causing elastic recovery deformation) of the lower region  50   a  of the cover plate  50 , and the lever recovery unit is provided to remove an unstable factor and maintain a stable fixed state. When the rotatable lever  30  moves slightly further downward from the above-described slight downward movement to be disposed in a downward fixed state of −90°, the catching protrusion  10   s  is mounted on the catching protrusion expanded mounting portion  30   se  through the an entrance portion for the catching groove  30   s  of the rotatable lever  30  to allow the catching projection  30   sa  with a height of Δs and a lower end portion of the catching protrusion  10   s  to be caught by elastic recovery deformation (0.657→0.5 mm) of the lower region  50   a  of the cover plate, and during the recovery, the first hinge pin  32  may move in the long hole portion  30   e  of the hinge hole upward (upward movement of the lever, that is, recovery movement of the lever) while the upper gap  30   e   1  of the long hole portion  30   e  of the hinge hole is re-increased (0.208→0.4 mm) and the lower gap  30   e   2  is re-decreased (0.192→0 mm). 
     Therefore, as shown in  FIG. 7K , to perform movement downward and rotation in the opposite direction of the rotatable lever  30  by a predetermined strength of external force F to re-pass through the lever recovery unit and the lever downward moving unit, reverse operations of the rotatable lever  30 , the sliding block  20 , and the slider fork  25  integrated with the sliding block  20  are limited until the elastic recompression deformation (‘0.657 mm’ deformation of  FIG. 7K  schematically showing a device according to the embodiment in which a rotation diameter a from the first hinge pin to the catching projection is 83 mm) of the cover plate-lower region  50   a  by the forcible further slight downward movement of the rotatable lever  30  is re-performed. 
     Both end portions of the conversion link bar  40  provided as an element of the switching device  100  are coupled to the rotatable lever  30  and the sliding block  20  through the second hinge pin  40   a  and the third hinge pin  40   b , and in such a case, predetermined sizes and shapes of end accommodation grooves  30   a  and  20   a  (see  FIG. 4B ) are provided in the rotatable lever  30  and the sliding block  20  so as to not cause interference with both end portions of the conversion link bar  40 , and the both end portions of the conversion link bar  40  are accommodated in the end accommodation grooves  30   a  and  20   a , and thus a compact structure requiring a minimum space when the conversion link bar  40  is folded is provided. 
     Further, a sliding guide pad  15  (see  FIGS. 3B and 6A ) made of a self-lubricative material (for example, ‘Turcite®’), which is mainly made of a material including at least one component selected from the group consisting of fluorocarbon complex, polyoxymethylene, nylon mono, monomer-cast (MC) nylon, high molecular polyethylene, and Teflon, is installed between the sliding block  20  and the housing  10  so that the sliding block  20  slides smoothly and linearly in the housing  10  in a longitudinal direction without noise. 
     When a rotation direction of the rotatable lever and an installation position of the rotatable lever releasing blocking unit have been described in a detailed description of the embodiments of the present invention, directional terms “upward” and “downward” have been used, but it is assumed that the device according to the present invention is installed in the door frame in the direction shown in the drawings. When the locking device according to the present invention is installed in a different direction, upward and downward directions may be reversed, or the direction may be leftward and rightward directions. Therefore, it should be understood that the directional terms are not to be construed as limiting the scope of the present invention, and various modifications and improvements by those skilled in the art using the basic concept of the present invention defined in the following claims are also within the scope of the present invention.