Abstract:
An electrical door-locking device includes screws which are rotatable in a forwards and backwards direction, and are placed in line on one side of a door frame in the direction in which the electrical door main body slides; locking hooks located adjacent to the screws; and a sliding unit equipped with a rotatably-provided locking lever having a latch for latching onto the locking hooks when the electrical door main body is closed and is equipped with a locking-lever-pressing part for pressing the locking lever such that the latch of the locking lever unlatches from the locking hooks, and one end of which is rotatably linked to the screws and the other end of which is linked to the electrical door main body.

Description:
FIELD OF THE INVENTION  
       [0001]    The present invention relates, in general, to an electric door lock and an electric door having the same and, more particularly, to an electric door lock which has a simple structure, ensures the reliability of a locking function, reduces a danger of a failure and an operation error, and is easy to fabricate and maintain, saving the cost for the fabrication and maintenance relative to the cost taken in the related art, and an electric door having the same. 
       DESCRIPTION OF THE RELATED ART 
       [0002]    In case of a railway train, a currently available electric door (auto door) is operated such that when a train arrives at a station, the door is opened and closed for boarding or alighting of passengers following the driver&#39;s manipulation of an actuation switch, which is performed by the driver who is seeing the passengers boarding on or alighting from the railway train. 
         [0003]    Here, if a passenger or an object gets caught in the door during the closing of the electric door, the electric door cannot be completely closed. In this case, the driver is informed of such situation or information through a display or an alarm means, and the driver who recognized the state of the door being not completely closed repeatedly manipulates the actuation switch to open and close the electric door until the electric door is completely closed. 
         [0004]    In the meantime, if the railway train is stopped to run owing to a fire, a failure, etc. of the train, or passengers should escape from the train because an emergency situation occurs in the train, the driver should directly manipulate the actuation switch to open the door after checking the state of the railway tracks, or otherwise the passengers should directly manually manipulate a manual opening/closing means, which was mounted in the proximity of the electric door, to open the door. 
         [0005]    However, if the situation is that the railway train is running, or the state of the railway tracks is dangerous, or otherwise if nevertheless the situation is not an emergency state, the passengers can open the electric door even with their less effort, a very dangerous situation can be caused. Thus, there is a need for an electric door lock 
         [0006]    In order to provide a reliable locking function, a conventional electric door lock, which was disclosed in U.S. Pat. No. 5,077,938, includes a locking roller, a locking finger member, a guide finger member, a locking roller slide channel, a roller keeper, a carriage, and the like. 
         [0007]    However, the conventional electric door lock having the above-mentioned configuration has a problem of increased cost of fabrication and maintenance because of numerous, complex parts. 
       DISCLOSURE OF INVENTION 
     Technical Problem 
       [0008]    Accordingly, the present invention has been made keeping in mind the above problems occurring in the related art, and the present invention is intended to propose to an electric door lock which has a simple structure, ensures the reliability of a locking function, reduces a danger of a failure and an operation error, and is easy to fabricate and maintain, saving the cost for the fabrication and maintenance relative to the cost taken in the related art, and an electric door having the same. 
       Solution to Problem 
       [0009]    In order to achieve the above object, according to one aspect of the present invention, there is provided an electric door lock adapted to at least one electric door body that is able to slide, the electric door lock including: a pair of screws capable of rotating forwards and rearwards and disposed parallel with each other in one side of a door frame in the direction in which the door body slides; a locking hook each provided in the proximity of the screws; and a sliding unit wherein one end thereof is rotatably connected to the screws and the other end thereof is connected to the door body, the sliding unit including a locking lever rotatably provided therein and having a latch for latching onto the locking hooks when the electric door is closed, and a locking lever-pressing part actuated to press the locking lever such that the latch of the locking lever unlatches from the locking hooks. 
         [0010]    The locking lever may be elastically biased towards the direction against which the locking lever approaches the locking hook by means of e.g. a pressing spring member. 
         [0011]    In addition, the locking lever may further include a locking lever roller that will come into contact with the locking lever-pressing part. The locking lever further comprises locking roller formed of a latch latching onto the locking hook That is, the latch of the locking lever that will latch onto the locking hook may preferably be formed of a locking roller. 
         [0012]    The locking hook may be provided in the proximity of the door frame or a screw-fixing housing adjacent to the screw. 
         [0013]    According to the present invention, the electric door lock may further include a locking switch provided in the door frame for checking the locked state of the door body when the door body is closed, and a locking switch-pressing part actuated to operate a locking switch such that a locking signal is generated by the locking switch. 
         [0014]    The sliding unit may include: a transfer nut rotatably screwed-coupled to the screw such that it is rotatable in the longitudinal direction of the screw; a transfer nut lump including the transfer nut, a support for the transfer nut, and the locking lever-pressing part; a transfer nut lump housing partially surrounding and supporting the transfer nut lump such that the transfer nut lump is rotatable at a certain angle; and a locking lever hinge rotating the locking lever at a certain angle in the direction perpendicular to the advancing-direction of the sliding unit 
         [0015]    The transfer nut lump housing may include: a housing body; and an opening that is formed to one side of the housing body such that the locking lever-pressing part is open towards the locking lever roller 
         [0016]    The locking hook may include: an inclined section provided in the outside thereof at a certain angle in the direction in which the electric door body is closed, such that a locking roller of the locking lever is smoothly coupled to the locking hook; and a vertical end formed at the utmost position of the inclined section such that the vertical end extends in the direction that intersects the direction in which the door body slides. 
         [0017]    The sliding unit may further include: a hanger connected with the door body; a hanger roller connected to one side of the hanger and coupled to a hanger rail formed on the door frame such that it is able to roll along the hanger rail; and a link that connects and supports the other side of the hanger and the transfer nut lump housing. 
         [0018]    The electric door lock of the present invention may include an emergency release mechanism having an emergency release roller and an emergency release roller plate to which the emergency release roller is mounted. 
         [0019]    The door body, the screws, the locking hooks, the emergency release roller, the emergency release roller plate, and the sliding unit may be respectively provided in a single unit or a pair unit, in which both elements are symmetric with each other, on the door frame. Here, the opposite screws may respectively have threads extending opposite to each other, i.e., the pair of screws respectively have threads extending opposite to each other. 
         [0020]    In addition, the electric door lock may further include a closing switch provided in the door body so as to generate a signal indicative of the closed state of the door body when the door body was closed. 
         [0021]    A space in which the screw nut lump can move in the sliding direction of the door body or in the direction that intersects the sliding direction in connection with the screw nut lump housing may be further provided between the screw nut lump and the screw nut lump housing. 
         [0022]    In another aspect of the present invention, there is provided an electric door having the electrical door lock having the above-mentioned configuration. 
         [0023]    As set forth before, the electric door lock has a simple structure, ensures the reliability of a locking function, reduces a danger of a failure and an operation error, and is easy to fabricate and maintain, saving the cost for the fabrication and maintenance relative to the cost taken in the related art. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0024]    The above and other objects, features and advantages of the present invention will be more clearly understood from the following detailed description when taken in conjunction with the accompanying drawings, in which: 
           [0025]      FIG. 1  is a perspective view showing an electric door lock according to an embodiment of the present invention when it is being closed. 
           [0026]      FIG. 2  is a perspective view showing the electric door lock according to an embodiment of the present invention when it was completely closed. 
           [0027]      FIG. 3  is a plan view showing the electric door lock of  FIG. 2  which was closed. 
           [0028]      FIG. 4  is a front view showing the electric door lock of  FIG. 2  which was closed. 
           [0029]      FIG. 5  is a perspective view showing an electric door lock according to an embodiment of the present invention when it starts opening. 
           [0030]      FIG. 6  is a perspective view showing an electric door lock according to an embodiment of the present invention when it is being opened. 
           [0031]      FIG. 7  is a plan view showing the electric door lock of  FIG. 6  which was opened. 
           [0032]      FIG. 8  is a front view showing the electric door lock of  FIG. 6  which was opened. 
           [0033]      FIG. 9  is a perspective view showing an electric door lock according to an embodiment of the present invention when it is being released from its emergency-locked state. 
           [0034]      FIG. 10  is a plan view showing the electric door lock of  FIG. 9  when it is being released from its emergency-locked state. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0035]    Reference will now be made in greater detail to a preferred embodiment of the invention, an example of which is illustrated in the accompanying drawings. Wherever possible, the same reference numerals will be used throughout the drawings and the description to refer to the same or like parts. 
         [0036]      FIG. 1  is a perspective view showing an electric door lock according to an embodiment of the present invention when it is being closed,  FIG. 2  is a perspective view showing the electric door lock according to an embodiment of the present invention when it was completely closed,  FIG. 3  is a plan view showing the electric door lock of  FIG. 2  which was closed, and  FIG. 4  is a front view showing the electric door lock of  FIG. 2  which was closed. 
         [0037]      FIG. 5  is a perspective view showing an electric door lock according to an embodiment of the present invention when it starts opening,  FIG. 6  is a perspective view showing an electric door lock according to an embodiment of the present invention when it is being opened,  FIG. 7  is a plan view showing the electric door lock of  FIG. 6  which was opened, and  FIG. 8  is a front view showing the electric door lock of  FIG. 6  which was opened. 
         [0038]      FIG. 9  is a perspective view showing an electric door lock according to an embodiment of the present invention when it is being released from its emergency-locked state, and  FIG. 10  is a plan view showing the electric door lock of  FIG. 9  when it is being released from its emergency-locked state. 
         [0039]    As shown in  FIGS. 1 to 10 , the electric door lock which is adapted to at least one electric door body (not shown) that is slidably movable includes: a locking switch  27  provided in the door body for checking the locked state of the door body when the door body is closed; a pair of screws  10  capable of rotating forwards and rearwards and disposed parallel with each other in one side of the door frame (not shown) in the direction towards which the door body slides; a pair of locking hooks  20  provided in a door frame  2  or a screw-fixing housing  21  in the proximity of the screws; and a sliding unit  30  including a locking lever  17  having a locking roller  16  coupled to the locking hook  20  when the door body is closed, and rotatably mounted therein, a locking lever-pressing part  13  pressing down a roller  18  of the locking lever  17  such that the locking roller  16  of the locking lever is released from the locking hook  20 , and a locking switch-pressing part  28  actuated to operate the locking switch  27  such that a locking signal is generated by the locking switch, wherein one end thereof is rotatably connected to the screw and the other end thereof is connected to the door body. The locking lever  17  is elastically biased towards the direction against which the locking lever approaches the locking hook  20  by means of e.g. a locking lever-pressing spring  19 . The locking hook  20  includes an inclined section provided in the outside thereof at a certain angle in the direction in which the electric door body is closed, such that a locking roller  16  of the locking lever  17  is smoothly coupled to the locking hook  20 , and a vertical end formed at the utmost position of the inclined section such that the vertical end extends in the direction that intersects the direction in which the door body slides. In order to allow the locking roller  16  of the locking lever  17  to smoothly latch onto and unlatch from the locking hook  20 , the boundary between the inclined section and the vertical end of the locking hook may preferably be formed into a round. 
         [0040]    According to the electric door lock of the present invention, as shown in  FIG. 1 , when the sliding unit  30  moves in the direction in which it is closed so that the locking roller  16  of the locking lever  17  meets the locking hook  20 , the locking roller  16  moves at an inclined angle of the locking hook  20  in the reverse of the direction of the locking lever-pressing spring  19  so that it rolls upwards along the inclined section of the locking hook  20  and vertically rolls off from the utmost position of the inclined section of the locking hook  20 , i.e. to the locked position shown in  FIG. 2 . Here, the locking switch-pressing part  28  actuates the locking switch  27  to operate so as to generate a locking signal, which in turn is transmitted to a user, finally completing the locking stroke of a door. 
         [0041]    As shown in  FIG. 1 , the locking switch  27  may be coupled to the upper portion of the door frame or a screw-fixing housing  21 . Since the locking switch  27  is adapted to a pressure-sensitive sensor that is actuated by the operation, i.e. the pressing of the locking switch-pressing part  28 , thereby generating the locking signal, it may preferably be coupled to the locking lever  17 . Naturally, this is only one embodiment. That is, while the present embodiment has illustrated the configuration in which when the door body is closed, the locking switch-pressing part  28  is concurrently rotated at a certain angle to actuate the locking switch  27 , alternative embodiment is possible in which the locking switch  270  is disposed as e.g. a proximity sensor at the position closer to the door frame  2  than the position of  FIG. 1 , so that when the locking switch-pressing part  28  rotates and approaches the locking switch  27 , the locking switch can then only generate a locking signal. However, so long as when the door body is closed, the reliability of the locking function can be secured, any method may be adapted. 
         [0042]    The screw  10  is an element that transmits a practical driving force from a motor (not shown) to the electric door body in order to open or close the electric door body. 
         [0043]    In the present embodiment, since a pair (set) of electric door bodies  1  is provided, a pair of screws  15  is also provided. Here, sine the pair of electric door bodies  1  is opened or closed in opposite directions to each other, the pair of screws  15  has threads that extend in opposite directions to each other. That is, in  FIGS. 2 and 3 , the left side screw  15  has the right-side thread, whereas the right side screw  15  has the left-side thread. Since such screws  15  transmit a practical driving force to the electric door body  1 , they are connected to a drive shaft (not shown) of the motor in order to rotate forwards or rearwards. For reference, opening/closing of the door may be manually controlled by a user, or otherwise may be automatically controlled. 
         [0044]    The sliding unit  30  is a unit wherein one end thereof is rotatably screwed to the screw  10  and the other end thereof is connected to the door body, serving to open/close the door body following the transmission of the rotating power of the screw  10  that is rotating to the door body. 
         [0045]    The sliding unit  30  of the present embodiment advantageously has a very simple configuration because in addition to detailed elements described below, the locking switch-pressing part  28  that actuates the locking switch  27  and the locking lever  17  having the locking roller  16  that interacts with the locking hook  20  are formed into a single piece. 
         [0046]    More specifically, according to the present embodiment, since most parts other than the screw-fixing housing  21  are integrated with the sliding unit  30 , the door lock may have a simple structure, ensure the reliability of a locking function, reduce a danger of a failure and an operation error, and be easy to fabricate and maintain, saving the cost for the fabrication and maintenance relative to the cost taken in the related art. 
         [0047]    The sliding unit  30  may include a transfer nut lump rotatably screwed to the screw  10  such that it is movable in the longitudinal direction of the screw  10 , a transfer nut lump housing  12  that partially surrounds and supports the transfer nut lump such that the transfer nut lump is able to rotate at a certain angle, while surrounding and supporting a transfer nut  11 , a locking lever  17  that has the locking lever roller  18  and the locking roller  16  and is connected to one side of the transfer nut lump housing  12  by means of a locking lever hinge  26 , a link that connects the transfer nut lump housing  12  and a hanger (not shown), and the hanger that connects the link and the door body. 
         [0048]    The transfer nut lump includes a screw hole through which the screw  10  is directly screw-coupled and which has a thread that is formed to correspond to that of the screw  10 , the transfer nut  11  that converts a rotating motion of the screw into a linear motion of the sliding unit, the locking lever-pressing part  13  that moves the locking lever  17  including the locking lever roller  18  to the locked position, and a transfer nut support  14  that is integrated with or attached to the transfer nut so as to support the transfer nut lump such that it is rotatable at only a certain angle. The locking lever-pressing part  13  may have the shape of a disc with a certain thickness, with a protrusion formed in one side. Here, the disc of a certain thickness may be eccentrically mounted to the center of an axis of the screw  10 . In addition, the locking lever may preferably further include the locking lever roller that is brought into contact with the locking lever-pressing part so that the locking lever-pressing part and the locking lever roller roll over relative to each other. 
         [0049]    The transfer nut  11  is an element that is screw-coupled to the screw  10 . Thus, as the screw  10  rotates, the transfer nut lump housing  12  connected to the side of the door body can be moved along the longitudinal direction of the screw  10 . As such, the transfer nut  11  provided in the transfer nut lump housing  12  can be moved along the longitudinal direction of the screw  10 , so that the door body connected to the transfer nut lump housing  12  can also be actuated. 
         [0050]    The transfer nut lump housing  12  is an element that partially surrounds and supports the transfer nut lump. Since the transfer nut  11  and the locking lever-pressing part  13  should interact with the locking lever roller  18  while being operated, i.e. being rotated in the state of being connected to the transfer nut lump, the transfer nut lump housing  12  is provided without interfering with the operation of the transfer nut  11  and the locking lever-pressing part  13 . The transfer nut lump housing  12  has an opening in one side of a body of the transfer nut lump housing  12  such that it allows the locking lever-pressing part  13  to move towards the locking lever roller  18 . 
         [0051]    The locking lever-pressing part  13  is actuated such that when the transfer nut lump is transferred in the direction in which the sliding door is opened, it is rotated together with the transfer nut lump so as to force the locking lever roller  18  to move, thereby allowing the locking roller  16  to unlatched from the locking hook  20 . 
         [0052]    The transfer nut support  14  has the shape of a right angled section in one side of the transfer nut lump, thereby serving to support the transfer nut lump such that the transfer nut lump cannot rotate at a certain angle or more when the transfer nut lump is in the locked or opened state. 
         [0053]    The locking lever  17  is connected with the transfer nut lump housing  12  by means of the locking lever hinge  26  so that it can be moved by a certain distance in the direction perpendicular from the advancing-direction of the sliding door while rotating about the locking lever hinge. Specifically, the locking lever may include the locking lever roller  18  and the locking roller  16 . Here, the locking lever roller is designed such that when the transfer nut including the locking lever-pressing part  13  is rotated, it is brought into contact with the locking lever-pressing part  13  to allow the locking lever  17  to be moved by a certain distance while being rotated about the locking lever hinge  26 . The locking roller  16  serves to perform an actual locking operation in association with the operation of the locking switch-pressing part  28  and the locking hook  20 . 
         [0054]    The locking lever  17  may be provided such that it is elastically biased towards the direction in which the locking roller  16  is coupled with the locking hook in the direction in which the door is closed. 
         [0055]    The transfer nut lump housing  12  may be designed to surround and support the transfer nut, to be connected, in one side thereof, with the locking lever  17  including the locking lever roller  18  and the locking roller  16 , and to partially surround and support the transfer nut lump such that the transfer nut lump is rotatable at a certain angle. 
         [0056]    The locking hook  20  serves to perform the locking operation in association with the operation of the locking roller  16 . The locking hook  20  is attached to or integrated with a locking hook-fixing plate  24 , or otherwise may be attached to the screw-fixing housing  21  or other proper site (if there is spatial restriction). 
         [0057]    The electric door lock according to an embodiment of the present invention may include an emergency release mechanism that can release the locked state of the door lock in an emergency. The emergency release mechanism includes an emergency release roller  25  and a mounting plate for the emergency release roller  23 . The mounting plate  23  for the emergency release roller is attached to the screw-fixing housing  21  such that it is rotatable at a certain angle relative to the screw-fixing housing. In addition, the mounting plate is coupled with the emergency release roller  25 , so that in an emergency release situation, it is rotated at the same angle as the rotated emergency release roller  25  so as to allow the emergency release roller  25  to come into contact with the inner protrusion  41  of the locking lever  17  and move the inner protrusion  41  forwards. Thus, the locking roller  16  can be moved by a certain distance in the direction in which the locking roller  16  is separated away from the locking hook  20 , even though the locking lever-pressing part  13  does not move the locking lever roller  18  of the locking lever  17  in the forward direction. A connecting pin  23  connects the left, right mounting plates  23  for the emergency release roller together, so that it allows the left, right mounting plates  23  to be rotated at the same angle. 
         [0058]    In an embodiment of the present invention, the door frame (not shown) is a plate to which the door body is attached such that the door body is slidably moved along the plate. The door frame may be made from a metal frame for securing sufficient hardness. 
         [0059]    Subsequently, a description will be made of the operation of the electric door lock while exemplifying a railway train. 
         [0060]    First, the closing operation of the electric door lock will be described with reference to  FIGS. 1 to 4 . 
         [0061]      FIG. 1  is a perspective view showing an electric door lock according to an embodiment of the present invention when it is being closed,  FIG. 2  is a perspective view showing the electric door lock according to an embodiment of the present invention when it was completely closed,  FIG. 3  is a plan view showing the electric door lock of  FIG. 2  which was closed, and  FIG. 4  is a front view showing the electric door lock of  FIG. 2  which was closed. 
         [0062]    When the screw  10  rotates in the forward or reverse direction by the operation of a motor, the door body is opened or closed following the forward or reverse rotation of the screw  10 . 
         [0063]    In order to close the door body, as shown in  FIGS. 1 and 2 , the screw  10  is manipulated to be rotated in the reverse direction. Here, the locking lever  17  is applied with the force in the direction opposite to the direction in which the door body is opened, such that locking lever-pressing part  13  does not push the locking lever roller  18 , but the locking lever-pressing spring  19  performs the locking operation such that the locking roller  16  of the locking lever  17  is operated in association with the locking hook  20 . 
         [0064]    That is, as shown in  FIG. 1 , when the sliding unit moves in the closed direction so that the locking roller  16  of the locking lever  17  meets the locking hook  20 , the locking roller  16 , the locking roller  16  is rotated at a certain angle along the inclined section of the locking hook  20  while moving in the reverse direction of the force exerted by the locking lever-pressing spring  19 , such that it climbs over along the inclined section of the locking hook  20  and rolls off vertically from the utmost position of the inclined section of the locking hook  20 , i.e. to the locked position shown in  FIG. 2 . Here, the locking switch-pressing part  28  actuates the locking switch  27  to operate so as to generate a locking signal, which in turn is transmitted to a user, finally completing the locking stroke of a door. Of course, since this state is obtained in the process of finally checking the locked state, it is the state in which the closing signal was already transmitted from the closing switch before the locking signal is not generated. 
         [0065]    like this, when the closing signal from the closing switch (not shown) and the locking signal from the locking switch  27  are transmitted to the user&#39;s control system, the closing stroke of the door is then only completed. Here, since the locking roller  16  was already disposed inside the locking hook  20 , even though the passengers intend to open the door body, the door body is still held in the locked state so that the door body cannot be opened. 
         [0066]    Next, the opening operation of the electric door lock of the present invention will be described with reference to  FIGS. 5 to 8 . 
         [0067]      FIG. 5  is a perspective view showing the electric door lock when it starts opening,  FIG. 6  is a perspective view showing the electric door lock when it is being opened,  FIG. 7  is a plan view showing the electric door lock of  FIG. 6  which was opened, and  FIG. 8  is a front view showing the electric door lock of  FIG. 6  which was opened. 
         [0068]    In order to allow the locking lever-pressing part  13  to actuate the locking lever roller  18  when the door body is opened, the transfer nut  11  should be rotated at a certain angle inside the transfer nut lump housing  12 . 
         [0069]    Accordingly, for example, when the door body is being opened in response to the forward rotation of the screw  10 , the screw  10  is operated as shown in  FIGS. 5 and 6 . When the screw  10  is operated as such, due to the initial strong rotation torque, the locking lever-pressing part  13  of the transfer nut lump is rotated at a certain angle in the locked position, causing the locking lever roller  18  of the locking lever  17  to be pushed forwards (in the direction “F” shown in  FIGS. 5 and 6 ). Then, the locking roller  16  of the locking lever  17  unlatched from the locking hook  20 , being released from its locked state and performing the opening operation, thereby allowing the door body to be normally opened. 
         [0070]    When the door body is opened and closed, the door body is moved along an axis of the screw  10  while the hanger roller rolls along the hanger rail (not shown) formed on the door frame, so that the door body can be smoothly opened and closed. 
         [0071]    Next, the operation of the emergency release mechanism of the electric door lock will be described with reference to  FIGS. 9 and 10 . 
         [0072]      FIG. 9  is a perspective view showing the electric door lock when it is being released from its emergency-locked state, and  FIG. 10  is a plan view showing the electric door lock of  FIG. 9  when it is being released from its emergency-locked state. 
         [0073]    As shown in  FIGS. 9 and 10 , when the door lock is intended to be released from its locked state in an emergency, the mounting plate  23  to which the emergency release roller  25  is attached is rotated so that the emergency release roller  25  comes into contact with the inner protrusion  41  of the locking lever  17 , pushing the inner protrusion  41  in the forward direction. Accordingly, even though the locking lever-pressing part  13  does not push the locking lever roller  18  in the forward direction, the locking lever  17  is rotated about the locking lever hinge  26 , so that the locking roller  16  of the locking lever  17  can unlatch from the locking hook  20 , thereby releasing the locked state of the door body. 
         [0074]    As set forth before, according to the present embodiment, the electric door lock can have a simple structure, ensure the reliability of a locking function, reduce a danger of a failure and an operation error, and be easy to fabricate and maintain, saving the cost for the fabrication and maintenance relative to the cost taken in the related art. 
         [0075]    Like this, according to an embodiment of the present invention, the screws  10 , the screw-fixing housings  21 , and the sliding units  30  may be respectively provided in a pair unit, in which both elements are symmetric with each other, on the door frame (not shown). This is because the door body is provided in a pair unit such that both elements are opened/closed by being moved apart from or close to each other. 
         [0076]    However, the scope of the present invention is not limited thereto, so a single door body can be provided in the door frame. In the case that the single door body is provided, it may suffice if the screw  10 , the screw-fixing housing  21 , and the sliding unit  30  respectively are concurrently provided in a single piece. Of course, even through the single door body is provided on the door frame, the embodiment can also implement the same performance as the present embodiment 
         [0077]    The electric door lock according to the above embodiments of the present invention may be adapted to electric doors of railway trains, screen doors of subway stations, etc. 
         [0078]    Although a preferred embodiment of the present invention has been described for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.