Patent Publication Number: US-2021172235-A1

Title: Vehicle Door Opening and Closing Apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of Korean Patent Application No. 10-2019-0160947, filed on Dec. 5, 2019, in the Korean Intellectual Property Office, which application is hereby incorporated herein by reference. 
     TECHNICAL FIELD 
     The present disclosure relates to a vehicle door opening and closing apparatus. 
     BACKGROUND 
     Vehicles have door apertures for ingress and egress of vehicle passengers into and out of a passenger compartment in the vehicle. A vehicle door is closed to block the door aperture and is opened to enable ingress and egress of passengers into and out of the passenger compartment through the door aperture. Vehicle doors are divided into swing doors and sliding doors. The swing door is opened and closed by swinging around a hinge mounted between the swing door and the vehicle body. The sliding door is opened and closed by sliding a roller mounted on the sliding door along a rail mounted on the vehicle body. 
     The swing door is very easy to open and close, thereby enabling quick ingress and egress of passengers. However, when the swing door is opened, a space for ingress and egress is relatively small. When the vehicle is located in a narrow space, a swing trajectory of the door is not secured, which makes the opening and closing operation thereof difficult. 
     The sliding door is very easy to open and close even when the vehicle is located in a narrow space. When the sliding door is opened, a space for ingress and egress is relatively large. However, the sliding door requires relatively more force and time to open and close, which hinders quick ingress and egress of passengers. 
     According to the related art, as a vehicle door is operated by a single opening and closing method, it may be difficult to adequately respond to the needs of customers seeking ease of use, diversity, and novelty. 
     The above information described in this background section is provided to assist in understanding the background of the inventive concept, and may include any technical concept which is not considered as the prior art that is already known to those skilled in the art. 
     SUMMARY 
     The present disclosure solves problems occurring in the prior art while advantages achieved by the prior art are maintained intact. 
     The present disclosure relates to a vehicle door opening and closing apparatus. Particular embodiments relate to a vehicle door opening and closing apparatus that allows a vehicle door to open and close in one mode selected from a swing mode and a sliding mode. Further embodiments relate to a vehicle door opening and closing apparatus capable of preventing a center roller unit from being separated from a center rail in a sliding mode and allowing the center roller unit to be released from the center rail in a swing mode. 
     An aspect of the present disclosure provides a vehicle door opening and closing apparatus allowing a vehicle door to open and close in one mode selected from a swing mode and a sliding mode, thereby satisfying the needs of customers, and capable of preventing a center roller unit from being separated from a center rail in the sliding mode and allowing the center roller unit to be released from the center rail in the swing mode. 
     According to an aspect of the present disclosure, a vehicle door opening and closing apparatus may include a vehicle door, a rail mounted on a vehicle body, a roller unit mounted on the vehicle door, moving along the rail, and allowing the vehicle door to open and close in one mode selected from a sliding mode and a swing mode, a center rail extending from a rear edge of a door aperture of the vehicle body, a center roller unit guided along the center rail, and a flap mechanism preventing the center roller unit from being separated from the center rail in the sliding mode, and allowing the center roller unit to be released from the center rail in the swing mode. 
     The flap mechanism may include a flap which is rotatably mounted on the center rail, and a locking lever which releasably engages with the flap. 
     The locking lever may move between an engaging position, in which the locking lever engages with the flap, and a release position, in which the locking lever releases the flap. 
     The locking lever may be movable to the release position by a release lever. 
     The release lever may move between a lock position, in which the release lever holds the locking lever in the engaging position, and an unlock position, in which the release lever moves the locking lever to the release position. 
     The flap may include a first flap portion and a second flap portion which is orthogonal to the first flap portion, and the first flap portion may have a first free end releasably engaging with the locking lever. 
     The flap may further include a first extension portion extending from the first flap portion, a second extension portion extending from the second flap portion, a first projection protruding from an end of the first extension portion, and a second projection protruding from an end of the second extension portion. 
     The flap mechanism may further include a stopper having a recess in which one of the first projection and the second projection is releasably received. 
     The stopper may be mounted on the center rail. 
     The locking lever may include a locking recess which receives at least a portion of the flap and a release shoulder which is located below the locking recess, and the release lever may have a tip pressing the release shoulder. 
     The flap mechanism may include a flap which is rotatably mounted on the center rail, and a driving motor which rotates the flap. 
     The flap mechanism may include a flap which is linearly movable on the center rail, and a driving motor which drives the flap. 
     The flap may include a first flap portion and a second flap portion which is pivotally connected to the first flap portion, and the first flap portion may be rotatable by the driving motor. 
     The flap may include a flap portion and a guide which is connected to the flap portion, and the guide may be linearly movable by the driving motor. 
     The guide may have rack teeth, and a pinion meshing with the rack teeth may be connected to the driving motor. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other objects, features and advantages of embodiments of the present disclosure will be more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  illustrates a vehicle door opening and closing apparatus according to an exemplary embodiment of the present disclosure, which is mounted on a rear door of a vehicle; 
         FIG. 2  illustrates a selector adjacent to an outside handle of a vehicle, an actuator connected to the selector, and hold locks; 
         FIG. 3  illustrates a state in which the door of  FIG. 1  is opened in a sliding mode; 
         FIG. 4  illustrates a state in which the door of  FIG. 1  is opened in a swing mode; 
         FIG. 5  illustrates an operation in which an upper roller unit and a lower roller unit move along an upper rail and a lower rail in a vehicle door opening and closing apparatus according to an exemplary embodiment of the present disclosure; 
         FIG. 6  illustrates an upper roller unit and a lower roller unit in a vehicle door opening and closing apparatus according to an exemplary embodiment of the present disclosure; 
         FIG. 7  illustrates an operation in which a vehicle door is opened and closed in a swing mode by an upper roller unit and a lower roller unit of a vehicle door opening and closing apparatus according to an exemplary embodiment of the present disclosure; 
         FIG. 8  illustrates an upper roller unit and a lower roller unit in a vehicle door opening and closing apparatus according to another exemplary embodiment of the present disclosure; 
         FIG. 9  illustrates an operation in which a vehicle door is opened and closed in a swing mode by an upper roller unit and a lower roller unit of a vehicle door opening and closing apparatus according to another exemplary embodiment of the present disclosure; 
         FIG. 10A  illustrates a perspective view of an upper hold lock and a lower hold lock; 
         FIG. 10B  illustrates a state in which an upper hold lock and a lower hold lock hold corresponding strikers; 
         FIG. 10C  illustrates a state in which an upper hold lock and a lower hold lock release corresponding strikers; 
         FIG. 10D  illustrates a state in which an upper hold lock and a lower hold lock are enabled to receive corresponding strikers; 
         FIG. 11  illustrates a main latch mounted on a vehicle door and a main striker; 
         FIG. 12  illustrates a perspective view of a center rail in a vehicle door opening and closing apparatus according to an exemplary embodiment of the present disclosure; 
         FIG. 13  illustrates a cross-sectional view of a swing guide of a center rail; 
         FIG. 14  illustrates a cross-sectional view of a sliding guide of a center rail; 
         FIG. 15  illustrates a structure in which a center roller unit is held in a swing guide of a center rail; 
         FIG. 16  illustrates an operation in which a center roller unit is released from a swing guide of a center rail; 
         FIG. 17  illustrates a flap mechanism according to an exemplary embodiment of the present disclosure; 
         FIG. 18  illustrates a perspective view of a flap illustrated in  FIG. 17 , which is rotatably mounted on a swing guide; 
         FIG. 19  illustrates a perspective view of a release lever in the flap mechanism illustrated in  FIG. 17 ; 
         FIG. 20  illustrates a state in which the flap of the flap mechanism illustrated in  FIG. 17  closes the swing guide; 
         FIG. 21  illustrates a state in which the flap of the flap mechanism illustrated in  FIG. 17  is freely rotatable on the swing guide; 
         FIG. 22  illustrates a state in which a center roller unit is received in the swing guide as the flap of the flap mechanism illustrated in  FIG. 17  closes the swing guide; 
         FIG. 23  illustrates a state in which the center roller unit is releasable from the swing guide as the flap of the flap mechanism illustrated in  FIG. 17  is freely rotatable on the swing guide; 
         FIG. 24  illustrates a flap mechanism according to another exemplary embodiment of the present disclosure; 
         FIG. 25  illustrates a state in which a center roller unit is received in a swing guide as a flap of the flap mechanism illustrated in  FIG. 24  closes the swing guide; 
         FIG. 26  illustrates a state in which the center roller unit is released from the swing guide as the flap of the flap mechanism illustrated in  FIG. 24  opens the swing guide; 
         FIG. 27  illustrates a flap mechanism according to another exemplary embodiment of the present disclosure in a state in which a center roller unit is received in a swing guide as a flap closes the swing guide; 
         FIG. 28  illustrates a state in which the center roller unit is releasable from the swing guide as the flap of the flap mechanism illustrated in  FIG. 27  opens the swing guide; 
         FIG. 29  illustrates a flap mechanism according to another exemplary embodiment of the present disclosure; 
         FIG. 30  illustrates a state in which a center roller unit is released from a swing guide as the flap of the flap mechanism illustrated in  FIG. 29  opens the swing guide; 
         FIG. 31  illustrates a vehicle door opening and closing apparatus according to an exemplary embodiment of the present disclosure, which is applied to a front door of a vehicle, in a state in which the front door is opened in a sliding mode; 
         FIG. 32  illustrates a state in which the front door of  FIG. 31  is opened in a swing mode; 
         FIG. 33  illustrates a vehicle door opening and closing apparatus according to an exemplary embodiment of the present disclosure, which is applied to a front door and a rear door of a vehicle, in a state in which the front door and the rear door are opened in a sliding mode; and 
         FIG. 34  illustrates a state in which the front door and the rear door of  FIG. 33  are opened in a swing mode. 
     
    
    
     DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS 
     Hereinafter, exemplary embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In the drawings, the same reference numerals will be used throughout to designate the same or equivalent elements. In addition, a detailed description of well-known techniques associated with the present disclosure will be omitted in order not to unnecessarily obscure the gist of the present disclosure. 
     Terms such as first, second, A, B, (a), and (b) may be used to describe the elements in exemplary embodiments of the present disclosure. These terms are only used to distinguish one element from another element, and the intrinsic features, sequence or order, and the like of the corresponding elements are not limited by the terms. Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meanings as those generally understood by those with ordinary knowledge in the field of art to which the present disclosure belongs. Such terms as those defined in a generally used dictionary are to be interpreted as having meanings equal to the contextual meanings in the relevant field of art, and are not to be interpreted as having ideal or excessively formal meanings unless clearly defined as having such in the present application. 
     A vehicle door opening and closing apparatus, according to exemplary embodiments of the present disclosure, may allow a vehicle door to open and close selectively in any one mode of a sliding mode and a swing mode. In other words, the vehicle door opening and closing apparatus, according to exemplary embodiments of the present disclosure, may be a transform-type door opening and closing apparatus. The sliding mode may allow the vehicle door to open and close by sliding in a longitudinal direction of a vehicle, and the swing mode may allow the vehicle door to open and close by swinging inwards and outwards. 
     Referring to  FIG. 1 , a vehicle body  1  may have a plurality of door apertures  2  and  3 , and the plurality of door apertures  2  and  3  may be divided into a front aperture  2  and a rear aperture  3 . A plurality of vehicle doors  4  and  5  may include a front door  4  covering and uncovering the front aperture  2 , and a rear door  5  covering and uncovering the rear aperture  3 . As the front door  4  is opened, the front door  4  may uncover the front aperture  2 , and as the front door  4  is closed, the front door  4  may cover the front aperture  2 . As the rear door  5  is opened, the rear door  5  may uncover the rear aperture  3 , and as the rear door  5  is closed, the rear door  5  may cover the rear aperture  3 . 
     The vehicle door opening and closing apparatus, according to exemplary embodiments of the present disclosure, may be applied to the front door  4 , the rear door  5 , and the like.  FIGS. 1 to 16  illustrate a vehicle door opening and closing apparatus according to exemplary embodiments of the present disclosure, which is applied to the rear door  5 . Hereinafter, the rear door  5  will be referred to as the vehicle door  5 , and the rear aperture  3  will be referred to as the door aperture  3 . 
     The vehicle door opening and closing apparatus, according to exemplary embodiments of the present disclosure, may include one or more rails  11  and  12  mounted on the vehicle body  1 , and the rails  11  and  12  may extend in the longitudinal direction of the vehicle. Referring to  FIG. 1 , an upper rail  11  may be mounted on an upper edge of the vehicle body  1 , and a lower rail  12  may be mounted on a lower edge of the vehicle body  1 . The upper rail  11  and the lower rail  12  may extend in the longitudinal direction of the vehicle. The upper rail  11  may be disposed on an upper edge of the door aperture  3 , and the lower rail  12  may be disposed on a lower edge of the door aperture  3 . 
     The vehicle door opening and closing apparatus, according to exemplary embodiments of the present disclosure, may include roller units  21  and  22  guided along the rails  11  and  12 . The roller units  21  and  22  may allow the vehicle door  5  to open and close in one mode selected from the sliding mode and the swing mode. In particular, the roller units  21  and  22  may be releasably held in predetermined positions of the rails  11  and  12  by hold locks  31  and  32 . Specifically, when the roller units  21  and  22  are held in the predetermined positions of the rails  11  and  12  by the hold locks  31  and  32 , the vehicle door  5  may be opened and closed in the swing mode in which the vehicle door swings in the predetermined positions of the rails  11  and  12 . When the roller units  21  and  22  are released by the hold locks  31  and  32 , the vehicle door  5  may be opened and closed in the sliding mode in which the vehicle door slides along the rails  11  and  12 . 
     Referring to  FIGS. 1 and 3 , an upper roller unit  21  may be mounted on an upper end of the vehicle door  5 , and the upper roller unit  21  may slide along the upper rail  11 . A lower roller unit  22  may be mounted on a lower end of the vehicle door  5 , and the lower roller unit  22  may slide along the lower rail  12 . 
     Referring to  FIG. 2 , the vehicle door  5  may include an outside handle  6 , and a selector  40  for selecting the sliding mode and the swing mode may be adjacent to the outside handle  6 . The selector  40  may have a first switch  41  selecting the sliding mode, and a second switch  42  selecting the swing mode. 
     When a user presses the first switch  41  and the sliding mode is selected, the vehicle door  5  may slide along the upper rail  11 , the lower rail  12 , and a center rail  13  as illustrated in  FIG. 3  as the user pushes the outside handle  6  toward the front of the vehicle or pulls the outside handle  6  toward the rear of the vehicle. In the sliding mode, the vehicle door  5  may move between a first open position OP 1  and a first closed position CP 1 , as illustrated in  FIGS. 1 and 3 . The first open position OP 1  refers to a position in which the vehicle door  5  is fully opened, and the first closed position CP 1  refers to a position in which the vehicle door  5  is fully closed. 
     When the user presses the second switch  42  and the swing mode is selected, the vehicle door  5  may swing as illustrated in  FIG. 4  as the user pushes or pulls the outside handle  6  toward a passenger compartment of the vehicle or toward the exterior side of the vehicle. In the swing mode, the vehicle door  5  may move between a second open position OP 2  in which the vehicle door  5  is fully opened and a second closed position CP 2  in which the vehicle door  5  is fully closed, as illustrated in  FIGS. 7 and 9 . In particular, when the vehicle door  5  is held in the first closed position CP 1 , it may be operated in the swing mode. 
     The upper roller unit  21  may have an upper hold lock  31 , and the vehicle body  1  may have a first upper striker  31   a  and a second upper striker  31   b  protruding downwardly from a roof of the vehicle body  1 . The first upper striker  31   a  may be aligned with or adjacent to a virtual axis of the first closed position CP 1 , and the second upper striker  31   b may be aligned with or adjacent to a virtual axis of the first open position OP 1 . 
     According to an exemplary embodiment, as illustrated in  FIGS. 1 and 3 , the upper hold lock  31  may releasably hold the first upper striker  31   a  in the first closed position CP 1 , and releasably hold the second upper striker  31   b in the first open position OP 1 . That is, one upper hold lock  31  may selectively hold the first upper striker  31   a  and the second upper striker  31   b . As the upper hold lock  31  holds the first upper striker  31   a , the upper roller unit  21  may be firmly held in the first closed position CP 1 , so that the vehicle door  5  may be kept in the first closed position CP 1 . As the upper hold lock  31  holds the second upper striker  31   b , the upper roller unit  21  may be firmly held in the first open position OP 1 , so that the vehicle door  5  may be kept in the first open position OP 1 . 
     According to another exemplary embodiment, the upper hold lock  31  may releasably hold the first upper striker  31   a  in the first closed position CP 1  so that the vehicle door  5  may be kept in the first closed position CP 1 . That is, the upper hold lock  31  may be an upper closed hold lock which keeps the closed state of the vehicle door  5  in the first closed position CP 1 . An upper open hold lock (not shown) may be mounted on the upper roller unit  21 , and may releasably hold the second upper striker  31   b in the first open position OP 1 . That is, the upper closed hold lock, which releasably holds the first upper striker  31   a  in the first closed position CP 1 , and the upper open hold lock, which releasably holds the second upper striker  31   b in the first open position OP 1 , may be individually mounted on the upper roller unit  21 . 
     Referring to  FIGS. 4 and 9 , the upper roller unit  21  may have an upper rotation axis CX 1 , and the vehicle door  5  may rotate around the upper rotation axis CX 1 . When the upper roller unit  21  is firmly held in the first closed position CP 1  by the upper hold lock  31  and the first upper striker  31   a , the vehicle door  5  may rotate around the upper rotation axis CX 1 . 
     The lower roller unit  22  may have a lower hold lock  32 , and the vehicle body  1  may have a first lower striker  32   a  and a second lower striker  32   b  protruding upwardly from the bottom of the vehicle body  1 . The first lower striker  32   a  may be aligned with or adjacent to the virtual axis of the first closed position CP 1 , and the second lower striker  32   b  may be aligned with or adjacent to the virtual axis of the first open position OP 1 . 
     According to an exemplary embodiment, as illustrated in  FIGS. 1 and 3 , the lower hold lock  32  may releasably hold the first lower striker  32   a  in the first closed position CP 1 , and releasably hold the second lower striker  32   b  in the first open position OP 1 . That is, one lower hold lock  32  may selectively hold the first lower striker  32   a  and the second lower striker  32   b . As the lower hold lock  32  holds the first lower striker  32   a , the lower roller unit  22  may be firmly held in the first closed position CP 1 , so that the vehicle door  5  may be kept in the first closed position CP 1 . As the lower hold lock  32  holds the second lower striker  32   b , the lower roller unit  22  may be firmly held in the first open position OP 1 , so that the vehicle door  5  may be kept in the first open position OP 1 . 
     According to another exemplary embodiment, the lower hold lock  32  may releasably hold the first lower striker  32   a  in the first closed position CP 1  so that the vehicle door  5  may be kept in the first closed position CP 1 . That is, the lower hold lock  32  may be a lower closed hold lock which keeps the closed state of the vehicle door  5  in the first closed position CP 1 . A lower open hold lock (not shown) may be mounted on the lower roller unit  22 , and may releasably hold the second lower striker  32   b  in the first open position OP 1 . That is, the lower closed hold lock, which releasably holds the first lower striker  32   a  in the first closed position CP 1 , and the lower open hold lock, which releasably holds the second lower striker  32   b  in the first open position OP 1 , may be individually mounted on the lower roller unit  22 . 
     According to an exemplary embodiment, the vehicle door  5  may be releasably held in the first closed position CP 1  by the upper hold lock  31  and the lower hold lock  32 , so that the vehicle door  5  may be kept in the first closed position CP 1  by the upper hold lock  31  and the lower hold lock  32 . That is, the upper hold lock  31  and the lower hold lock  32  may function as the closed hold lock which holds the vehicle door  5  in the first closed position CP 1 . 
     Referring to  FIGS. 4 and 9 , the lower roller unit  22  may have a lower rotation axis CX 2 , and the vehicle door  5  may rotate around the lower rotation axis CX 2 . When the lower roller unit  22  is firmly held in the first closed position CP 1  by the lower hold lock  32  and the first lower striker  32   a , the vehicle door  5  may rotate around the lower rotation axis CX 2 . 
     As illustrated in  FIG. 4 , the upper rotation axis CX 1  and the lower rotation axis CX 2  may be vertically aligned, and the vehicle door  5  may rotate around the vertically aligned upper and lower rotation axes CX 1  and CX 2 . 
     Referring to  FIG. 2 , the selector  40  may be electrically connected to an actuator  43 , and the actuator  43  may be configured to operate the upper hold lock  31  and the lower hold lock  32 . 
     As the user selects the selector  40 , the actuator  43  may selectively perform a hold operation in which the upper hold lock  31  holds the first upper striker  31   a  and the lower hold lock  32  holds the first lower striker  32   a , and a release operation in which the upper hold lock  31  releases the first upper striker  31   a  and the lower hold lock  32  releases the first lower striker  32   a.    
     When the user presses the first switch  41  of the selector  40  in a state in which the vehicle door  5  is closed, the upper hold lock  31  may release the first upper striker  31   a  and the lower hold lock  32  may release the first lower striker  32   a  simultaneously by the release operation of the actuator  43 . Thus, the user may slide the vehicle door  5  in the longitudinal direction of the vehicle body  1  so that the vehicle door  5  may be opened and closed in the sliding mode. 
     When the user presses the second switch  42  of the selector  40  in a state in which the vehicle door  5  is closed, the upper hold lock  31  may hold the first upper striker  31   a  and the lower hold lock  32  may hold the first lower striker  32   a  simultaneously by the hold operation of the actuator  43 , and the upper roller unit  21  and the lower roller unit  22  may be firmly held in the first closed position CP 1 . Thus, the user may swing the vehicle door  5  toward an interior space and an exterior space of the vehicle so that the vehicle door  5  may be opened and closed in the swing mode. 
     According to an exemplary embodiment, as illustrated in  FIG. 2 , one actuator  43  may operate the upper hold lock  31  and the lower hold lock  32  simultaneously. 
     According to another exemplary embodiment, an actuator operating the upper hold lock  31  and another actuator operating the lower hold lock  32  may be individually connected to the selector  40 . 
       FIGS. 10A to 10D  illustrate the upper hold lock  31  and the lower hold lock  32  according to an exemplary embodiment of the present disclosure. Referring to  FIGS. 10A to 10D , each of the upper hold lock  31  and the lower hold lock  32  may include a catch  71 , a pawl  72  releasably engaging with the catch  71 , and a lever  73  operatively connected to the pawl  72 . The lever  73  may be connected to the actuator  43  through a cable  75 . As the cable  75  is reversed (pulled) by the actuator  43 , the catch  71  may release the strikers  31   a  and  32   a . A portion of the catch  71 , the pawl  72 , and the lever  73  may be covered by a cover plate  76 , and the cover plate  76  may be attached to a mounting plate  74 . The strikers  31   a  and  32   a  may be fixed to the vehicle body  1  by a mounting plate  78 . 
     Referring to  FIGS. 10A to 10D , the upper hold lock  31  may releasably hold the first upper striker  31   a , and the lower hold lock  32  may releasably hold the first lower striker  32   a.    
     The catch  71  may be pivotally mounted on the mounting plate  74  through a first pivot shaft  71   a . The catch  71  may have a slot  71   b receiving the strikers  31   a  and  32   a , and the catch  71  may engage with or release the strikers  31   a  and  32   a . The catch  71  may move between an engaging position (see  FIG. 10B ) and a release position (see  FIG. 10C ). The engaging position refers to a position in which the catch  71  engages with the strikers  31   a  and  32   a  as illustrated in  FIG. 10B , and the release position refers to a position in which the catch  71  releases the strikers  31   a  and  32   a  as illustrated in  FIG. 10C . When the catch  71  is in the engaging position as illustrated in  FIG. 10B , the catch  71  may engage with the strikers  31   a  and  32   a  so that the catch  71  may hold the strikers  31   a  and  32   a . When the catch  71  is in the release position as illustrated in  FIG. 10C , the catch  71  may release the strikers  31   a  and  32   a . Thus, the strikers  31   a  and  32   a  may be released from the slot  71   b of the catch  71  or be received in the slot  71   b of the catch  71 . The catch  71  may be biased toward the release position by a first biasing element  71   c  such as a torsion spring. The first biasing element  71   c  may be disposed around the first pivot shaft  71   a . The catch  71  may have a locking shoulder  71   d.    
     The pawl  72  may be pivotally mounted on the mounting plate  74  through a second pivot shaft  72   a , and the pawl  72  may move between a pawl locking position (see  FIG. 10B ) and a pawl release position (see  FIGS. 10C and 10D ). The pawl locking position refers to a position in which the pawl  72  engages with the catch  71  and the catch  71  is kept in the engaging position, and the pawl release position refers to a position in which the pawl  72  releases the catch  71  and the catch  71  is allowed to move from the engaging position to the release position. As illustrated in  FIG. 10B , when the pawl  72  is in the pawl locking position, the movement (rotation) of the catch  71  may be restricted by the pawl  72  so that the catch  71  may be kept in the engaging position. As illustrated in  FIGS. 10C and 10D , when the pawl  72  is in the pawl release position, the movement (rotation) of the catch  71  may not be restricted by the pawl  72  so that the catch  71  may move from the engaging position to the release position. The pawl  72  may be biased toward the pawl locking position (see  FIG. 10B ) by a second biasing element  72   c  such as a torsion spring. The second biasing element  72   c  may be disposed around the second pivot shaft  72   a.    
     The pawl  72  may have a locking projection  72   d  locked to the locking shoulder  71   d  of the catch  71 . As illustrated in  FIG. 10B , as the pawl  72  is moved to the pawl locking position by the second biasing element  72   c , the locking projection  72   d  of the pawl  72  may be locked to the locking shoulder  71   d  of the catch  71  and the movement (rotation) of the catch  71  may be restricted, so that the catch  71  may be kept in the engaging position. As illustrated in  FIG. 10C , as the pawl  72  is moved to the pawl release position by the lever  73 , the locking projection  72   d  of the pawl  72  may be released from the locking shoulder  71   d  of the catch  71  and the movement (rotation) of the catch  71  may be allowed, so that the catch  71  may be moved to the release position by the first biasing element  71   c.    
     The lever  73  may be pivotally mounted on the mounting plate  74  through a third pivot shaft  73   a . The lever  73  may be connected to the actuator  43  through the cable  75 . An end of the cable  75  may be fixed to the lever  73 , and the cable  75  may be advanced or reversed by the actuator  43 . As the actuator  43  moves the cable  75 , the lever  73  may pivot around the third pivot shaft  73   a . The lever  73  may move the pawl  72  to the pawl release position (see  FIG. 10C ) by reversing the cable  75 . 
     The lever  73  may be operatively connected to the pawl  72  through a pin  72   b  and an opening  73   b . The pin  72   b  may be provided on the pawl  72 , and the opening  73   b  may be provided in the lever  73 . The pin  72   b  may be movably received in the opening  73   b . As the lever  73  pivots around the third pivot shaft  73   a , the pin  72   b  may move in the opening  73   b , allowing the pawl  72  to move. 
     As illustrated in  FIG. 10B , when the cable  75  is advanced by the actuator  43 , the locking projection  72   d  of the pawl  72  may be locked to the locking shoulder  71   d  of the catch  71  and the movement (rotation) of the catch  71  may be restricted so that the catch  71  may be kept in the engaging position. The strikers  31   a  and  32   a  may be held in the slot  71   b of the catch  71 . That is, the upper hold lock  31  and the lower hold lock  32  may hold the corresponding strikers  31   a  and  32   a.    
     As illustrated in  FIG. 10C , when the cable  75  is reversed by the actuator  43 , the lever  73  may move the pawl  72  to the pawl release position. The locking projection  72   d  of the pawl  72  may be released from the locking shoulder  71   d  of the catch  71  and the movement (rotation) of the catch  71  may be allowed, so that the catch  71  may be moved to the release position by the first biasing element  71   c , and the strikers  31   a  and  32   a  may be released from the slot  71   b of the catch  71 . Thus, the upper hold lock  31  and the lower hold lock  32  may release the corresponding strikers  31   a  and  32   a , and the upper roller unit  21  and the lower roller unit  22  may slide along the upper rail  11  and the lower rail  12 . 
     As illustrated in  FIG. 10D , even though the cable  75  is advanced by the actuator  43  in a state in which the locking projection  72   d  of the pawl  72  is released from the locking shoulder  71   d  of the catch  71 , the catch  71  may be kept in the release position by the first biasing element  71   c  so that the movement (rotation) of the catch  71  may be allowed. In this state, the strikers  31   a  and  32   a  may be allowed to be received in the slot  71   b of the catch  71 . That is, in a state in which the movement (rotation) of the catch  71  is allowed as the locking projection  72   d  of the pawl  72  is released from the locking shoulder  71   d  of the catch  71 , when the upper roller unit  21  and the lower roller unit  22  slide between the first closed position CP 1  and the first open position OP 1 , the strikers  31   a  and  32   a  may be allowed to be received in the slot  71   b of the catch  71 . When a force applied by the upper hold lock  31  and the lower hold lock  32  in a state in which the strikers  31   a  and  32   a  are received in the slot  71   b of the catch  71  is greater than a spring force of the first biasing element  71   c , the catch  71  may be moved to the engaging position. As illustrated in  FIG. 10B , as the locking projection  72   d  of the pawl  72  is locked to the locking shoulder  71   d  of the catch  71 , the catch  71  may hold the strikers  31   a  and  32   a.    
     Referring to  FIG. 5 , each of the upper rail  11  and the lower rail  12  may be mounted on the vehicle body  1  through a mounting bracket  15 , and the mounting bracket  15  may have a shape corresponding to that of the upper rail  11  and the lower rail  12 . Each of the upper rail  11  and the lower rail  12  may have a first extension portion  51  extending straightly in the longitudinal direction of the vehicle, and a second extension portion  52  extending from the first extension portion  51  toward the interior space of the vehicle. The second extension portion  52  may be bent with respect to the first extension portion  51  at a predetermined angle. 
     Referring to  FIG. 6 , each of the upper roller unit  21  and the lower roller unit  22  may include a roller bracket  64  having rollers  65  and  66  rolling along the rails  11  and  12 , and a body  60  connecting the roller bracket  64  and the vehicle door  5 . 
     The body  60  may extend diagonally so as not to contact the first extension portion  51  and the second extension portion  52 . The body  60  may have a first end portion  61  facing the interior side of the vehicle, and a second end portion  62  facing the exterior side of the vehicle. The first end portion  61  of the body  60  may be attached to the roller bracket  64 , and the second end portion  62  of the body  60  may be attached to the vehicle door  5 . 
     The roller bracket  64  may rotatably support the rollers  65  and  66 , and the rollers  65  and  66  may roll along the upper rail  11  and the lower rail  12 . As illustrated in  FIG. 6 , a middle roller  65  and two side rollers  66  disposed on both sides of the middle roller  65  may be rotatably mounted on the roller bracket  64 . A rotation axis of the middle roller  65  may be orthogonal to a rotation axis of the side roller  66 . 
     According to an exemplary embodiment, as illustrated in  FIG. 6 , the first end portion  61  of the body  60  may be pivotally connected to the roller bracket  64  through a pivot pin  68 , and the second end portion  62  of the body  60  may be fixed to the vehicle door  5 . Thus, the vehicle door  5  may swing around the pivot pin  68  adjacent to the roller bracket  64 . The body  60  may have a pivot lug  63  protruding from the first end portion  61  toward the roller bracket  64 , and the roller bracket  64  may be connected to the pivot lug  63  through the pivot pin  68 . The roller bracket  64  may be shaped so as not to interfere with the body  60  when the vehicle door  5  swings. The upper rotation axis CX 1  and the lower rotation axis CX 2  may be defined by the pivot pin  68 . For example, the upper rotation axis CX 1  and the lower rotation axis CX 2  may be a virtual axis extending vertically along a center point of the pivot pin  68 , and the upper rotation axis CX 1  and the lower rotation axis CX 2  may be vertically aligned, so that the vehicle door  5  may swing around the vertical rotation axis that virtually connects the upper rotation axis CX 1  and the lower rotation axis CX 2 . The upper hold lock  31  may be fixed to the roller bracket  64  of the upper roller unit  21 , and the lower hold lock  32  may be fixed to the roller bracket  64  of the lower roller unit  22 . 
     When, by the hold operation of the actuator  43 , the upper hold lock  31  firmly holds the roller bracket  64  of the upper roller unit  21  in the first closed position CP 1  and the lower hold lock  32  firmly holds the roller bracket  64  of the lower roller unit  22  in the first closed position CP 1 , the vehicle door  5  may swing around the upper rotation axis CX 1  of the upper roller unit  21  and the lower rotation axis CX 2  of the lower roller unit  22  as illustrated in  FIG. 7 . The vehicle door  5  may move between the second closed position CP 2  in which the vehicle door  5  is closed and the second open position OP 2  in which the vehicle door  5  is opened. When the vehicle door  5  swings, another adjacent door  4  or other components may be spaced apart from the vehicle door  5  by a predetermined gap S 1  so as not to interfere with the adjacent door  4  or the other components. For example, the vehicle door  5  may be a rear door, and another adjacent door  4  may be a front door. 
     According to the exemplary embodiment illustrated in  FIGS. 6 and 7 , as the pivot pin  68  is located between the roller bracket  64  and the first end portion  61  of the body  60 , the rotation axes CX 1  and CX 2  of the vehicle door  5  may be relatively far from the vehicle door  5 . Since a swing trajectory T 1  and a rotation radius R 1  of the vehicle door  5  are relatively increased, the gap S 1  between the vehicle door  5  and the adjacent door  4  may be relatively increased. If the gap S 1  between the vehicle door  5  and the adjacent door  4  is reduced, the vehicle door  5  may interfere with the adjacent door  4  when the vehicle door  5  moves toward the second open position OP 2 , and an open space created by the swing of the vehicle door  5  may be relatively narrowed since the swing trajectory T 1  of the vehicle door  5  is relatively reduced. 
     According to another exemplary embodiment, as illustrated in  FIGS. 8 and 9 , the first end portion  61  of the body  60  may be fixed to the roller bracket  64 , and the second end portion  62  of the body  60  may be pivotally connected to the vehicle door  5  through a pivot pin  68   a . Thus, the vehicle door  5  may swing around the pivot pin  68   a  adjacent to the second end portion  62  of the body  60 . 
     Referring to  FIGS. 8 and 9 , the roller bracket  64  may be fixed to the first end portion  61  of the body  60  by welding, using fasteners, and/or the like. The second end portion  62  of the body  60  may be pivotally connected to the vehicle door  5  through the pivot pin  68   a . The vehicle door  5  may have a pivot lug  69  protruding toward the body  60 , and the pivot lug  69  may be pivotally connected to the second end portion  62  of the body  60  through the pivot pin  68   a . The second end portion  62  of the body  60  may be shaped so as not to interfere with the vehicle door  5  when the vehicle door  5  swings. The upper rotation axis CX 1  and the lower rotation axis CX 2  may be defined by the pivot pin  68   a . For example, the upper rotation axis CX 1  and the lower rotation axis CX 2  may be a virtual axis extending vertically along a center point of the pivot pin  68   a , and the upper rotation axis CX 1  and the lower rotation axis CX 2  may be vertically aligned, so that the vehicle door  5  may swing around the vertical rotation axis that virtually connects the upper rotation axis CX 1  and the lower rotation axis CX 2 . The upper hold lock  31  may be fixed to the body  60  of the upper roller unit  21 , and the lower hold lock  32  may be fixed to the body  60  of the lower roller unit  22 . 
     Referring to  FIG. 9 , when the upper hold lock  31  firmly holds the roller bracket  64  of the upper roller unit  21  in the first closed position CP 1 , and the lower hold lock  32  firmly holds the roller bracket  64  of the lower roller unit  22  in the first closed position CP 1 , the vehicle door  5  may swing around the upper rotation axis CX 1  of the upper roller unit  21  and the lower rotation axis CX 2  of the lower roller unit  22 . Thus, the vehicle door  5  may move between the second closed position CP 2  in which the vehicle door  5  is closed and the second open position OP 2  in which the vehicle door  5  is opened. 
     According to the exemplary embodiment illustrated in  FIGS. 8 and 9 , as the pivot pin  68   a  is located between the second end portion  62  of the body  60  and the vehicle door  5 , the rotation axes CX 1  and CX 2  of the vehicle door  5  may be relatively close to the vehicle door  5 . Since a rotation radius R 2  of the vehicle door  5  is relatively shortened, a gap S 2  between the vehicle door  5  and another adjacent door  4  may be relatively reduced, resulting in improved exterior styling. Even though the rotation axes CX 1  and CX 2  of the vehicle door  5  are close to the vehicle door  5 , a swing trajectory T 2  of the vehicle door  5  is not reduced, and thus an open space created by the swing of the vehicle door  5  may not be narrowed. 
     Referring to  FIG. 11 , a main latch  80  may be mounted on a rear end of the vehicle door  5 , and a main striker  81  may be fixed to the vehicle body  1 . The main latch  80  may releasably engage with the main striker  81 . When the vehicle door  5  is in the first closed position CP 1  or the second closed position CP 2 , the main latch  80  may engage with the main striker  81  by an engaging operation of the outside handle  6  so that the vehicle door  5  may be locked in the first closed position CP 1  or the second closed position CP 2 . When the vehicle door  5  is in the first closed position CP 1  or the second closed position CP 2 , the main latch  80  may release the main striker  81  by a release operation of the outside handle  6  so that the vehicle door  5  may be allowed to move in the sliding mode or the swing mode. When the vehicle door  5  is held in the first closed position CP 1  and the main latch  80  releases the main striker  81 , a center roller unit  23  may be released from the center rail  13 , and thus the vehicle door  5  may be opened and closed in the swing mode. 
     The vehicle door opening and closing apparatus, according to exemplary embodiments of the present disclosure, may further include the center rail  13  mounted at a central portion of the vehicle body  1 , and the center roller unit  23  guided along the center rail  13 . 
     Referring to  FIGS. 1 and 3 , the center rail  13  may extend from a rear edge of the door aperture  3  along the longitudinal direction of the vehicle. The center roller unit  23  may be pivotally mounted at a central portion of the vehicle door  5 . In particular, the center roller unit  23  may be mounted in a position adjacent to the rear end of the vehicle door  5 . The center roller unit  23  may be guided along the center rail  13 . 
     Referring to  FIG. 12 , the center rail  13  may include a sliding guide  91  extending straightly in the longitudinal direction of the vehicle, and a swing guide  92  extending from the sliding guide  91  toward the interior side of the vehicle. The swing guide  92  may be bent at a predetermined angle with respect to the sliding guide  91  through a bending portion  93 , and the bending portion  93  may be curved at a predetermined radius. 
     Referring to  FIGS. 13 to 15 , the center roller unit  23  may include a roller bracket  101  and rollers  105  and  106  rotatably mounted on the roller bracket  101 . The roller bracket  101  may be pivotally mounted at the central portion of the vehicle door  5 . The rollers  105  and  106  may roll along the center rail  13 . As illustrated in  FIG. 15 , a middle roller  105  and two side rollers  106  disposed on opposite sides of the middle roller  105  may be rotatably mounted on the roller bracket  101 . A rotation axis of the middle roller  105  may be orthogonal to a rotation axis of the side roller  106 . 
     When the vehicle door  5  slides in the longitudinal direction of the vehicle as the sliding mode is selected, the sliding guide  91  may guide the rollers  105  and  106  of the center roller unit  23 . 
     Referring to  FIGS. 12 and 14 , the sliding guide  91  may include a stopper wall  95  preventing the rollers  105  and  106  of the center roller unit  23  from being separated from the sliding guide  91 . The stopper wall  95  may extend along a length of the sliding guide  91  and a length of the bending portion  93 . The stopper wall  95  may protrude vertically downward from the top of the sliding guide  91 . As the stopper wall  95  closes an upper area of the sliding guide  91  and an upper area of the bending portion  93 , the center roller unit  23  may be prevented from moving away from the sliding guide  91  toward the exterior side of the vehicle as illustrated in  FIG. 14 . 
     When the vehicle door  5  is opened and closed in the swing mode as the swing mode is selected, the swing guide  92  may guide the rollers  105  and  106  of the center roller unit  23  to be released from the center rail  13 . 
     An exterior side of the swing guide  92  may be entirely opened toward the exterior space of the vehicle. A guide projection  94  may protrude upwardly from the bottom of the swing guide  92 , and the guide projection  94  may extend along a length of the swing guide  92 . When the vehicle door  5  swings from the second closed position CP 2  to the second open position OP 2  along the swing trajectory T 1  or T 2 , the middle roller  105  of the center roller unit  23  may be guided along the guide projection  94  as illustrated in  FIG. 13 . 
     A front end  95   a  of the stopper wall  95  of the sliding guide  91  and a rear end  94   a  of the guide projection  94  may be located so as not to interfere with the swing trajectories T 1  and T 2  of the vehicle door  5 . In addition, as illustrated in  FIG. 16 , an axis X 1  of the sliding guide  91  and an axis X 2  of the swing guide  92  may intersect at a predetermined angle a. In particular, the angle a of intersection between the axis X 1  of the sliding guide  91  and the axis X 2  of the swing guide  92  may be an obtuse angle, so that the center roller unit  23  may easily be released from the swing guide  92  of the center rail  13  or may easily be received in the swing guide  92  of the center rail  13 . The center rail  13  may include a space  98  allowing the rollers  105  and  106  of the center roller unit  23  to be released from the center rail  13  or to be received in the center rail  13  when the vehicle door  5  swings in the swing mode. The space  98  may be defined between the front end  95   a  of the stopper wall  95  and the rear end  94   a  of the guide projection  94  as the front end  95   a  of the stopper wall  95  and the rear end  94   a  of the guide projection  94  are spaced apart from each other. Due to the space  98 , there is no interference when the rollers  105  and  106  of the center roller unit  23  are released from the center rail  13  or are received in the center rail  13  in the swing mode. 
     Meanwhile, when the main latch  80  malfunctions in the sliding mode or the vehicle door  5  or the swing guide  92  is deformed due to an external impact, the rollers  105  and  106  of the center roller unit  23  may be separated from the swing guide  92  of the center rail  13 , and thus the vehicle door  5  may not be easily opened and closed in the sliding mode. In order to deal with this problem, the vehicle door opening and closing apparatus, according to exemplary embodiments of the present disclosure, may further include a flap mechanism  110  preventing the rollers  105  and  106  of the center roller unit  23  from being separated from the center rail  13  in the sliding mode. In particular, the flap mechanism  110  may be mounted on the swing guide  92  of the center rail  13 , thereby preventing the rollers  105  and  106  of the center roller unit  23  from being separated from the swing guide  92  of the center rail  13  in the sliding mode. 
     Referring to  FIGS. 17 to 23 , the flap mechanism  110  according to an exemplary embodiment may allow the rollers  105  and  106  of the center roller unit  23  to be released from or received in the swing guide  92  in the swing mode, and prevent the rollers  105  and  106  of the center roller unit  23  from being separated from the swing guide  92  in the sliding mode. 
     The flap mechanism  110  may include a flap  120  rotatably mounted on the swing guide  92  of the center rail  13 , and a locking lever  130  releasably engaging with the flap  120 . 
     The swing guide  92  may include a top wall  92   a , an inboard side wall  92   b  facing the interior space of the vehicle, a bottom wall  92   c , an opening  92   d  opened toward the exterior space of the vehicle, and a cavity  92   e . The cavity  92   e  may be defined by the top wall  92   a , the inboard side wall  92   b , and the bottom wall  92   c  and the cavity  92   e  may receive the rollers  105  and  106  of the center roller unit  23 . 
     Referring to  FIG. 17 , the flap  120  may block or close at least a portion of the opening  92   d  of the swing guide  92 , especially an upper portion of the swing guide  92  facing the side rollers  106  mounted on the roller bracket  101 . The flap  120  may be rotatably mounted on the top wall  92   a  of the swing guide  92  through a hinge pin  129 . The flap  120  may include a first flap portion  121  and a second flap portion  122  orthogonal to the first flap portion  121 . The first flap portion  121  may have a first free end  127 , and the first free end  127  of the first flap portion  121  may releasably engage with the locking lever  130 . An axis of the second flap portion  122  may be orthogonal to an axis of the first flap portion  121 , and the second flap portion  122  may have a second free end  128 . In addition, the flap  120  may include a first extension portion  123  bent at a predetermined angle with respect to the axis of the first flap portion  121 , a first projection  125  protruding from an end of the first extension portion  123 , a second extension portion  124  bent at a predetermined angle with respect to the axis of the second flap portion  122 , and a second projection  126  protruding from an end of the second extension portion  124 . The first flap portion  121  and the second flap portion  122  may have an area sufficient to cover the upper portion of the opening  92   d  of the swing guide  92 . 
     When the first flap portion  121  engages with the locking lever  13 o, the second flap portion  122  may block at least a portion of the opening  92   d  of the swing guide  92  to keep the portion of the opening  92   d  in a closed state, and thus the rollers  105  and  106  of the center roller unit  23  may be prevented from being separated from the swing guide  92 . 
     When the first flap portion  121  is released from the locking lever  13 o, the flap  120  may freely rotate, and thus the rollers  105  and  106  of the center roller unit  23  may be released from the swing guide  92  or may be received in the cavity  92 e of the swing guide  92 . 
     Referring to  FIG. 18 , the swing guide  92  may have a hinge lug  195  protruding from the top wall  92   a  toward the flap  120 , and the flap  120  may have an opening  120   a  in which the hinge lug  195  is received. The opening  120   a  may be formed in the first extension portion  123  and the second extension portion  124 . Thus, the flap  120  may be rotatably mounted with respect to the hinge lug  195  of the swing guide  92  through the hinge pin  129 . 
     Referring to  FIGS. 20 and 21 , the locking lever  130  may be rotatably mounted on the top wall  92   a  of the swing guide  92  through a first hinge pin  133 . The locking lever  130  may have a locking recess  131  in which the first free end  127  of the first flap portion  121  of the flap  120  is received. 
     The locking lever  130  may move between an engaging position (see the solid line in  FIG. 20 ) in which it engages with the first free end  127  of the first flap portion  121  and a release position (see the dotted line in  FIG. 20 ) in which it releases the first free end  127  of the first flap portion  121 . 
     The locking lever  130  may be biased toward the engaging position by a first biasing element  134 . For example, the first biasing element  134  may be a torsion spring disposed around the first hinge pin  133 . 
     In addition, the locking lever  130  may include a release shoulder  132  located below the locking recess  131 . As a release lever  140  pushes the release shoulder  132 , the locking lever  130  may move to the release position (see the dotted line in  FIG. 20 ). 
     An inclined surface  135  may be formed between the locking recess  131  and the release shoulder  132 , and the first free end  127  of the first flap portion  121  of the flap  120  may be easily inserted into the locking recess  131  by moving on the inclined surface  135 . 
     Referring to  FIGS. 20 and 21 , the flap mechanism no may further include a stopper  150  restricting the position of the flap  120 . The stopper  150  may be attached to the top wall  92   a  of the swing guide  92  of the center rail  13 , and the stopper  150  may have a recess  151  in which one of the first projection  125  and the second projection  126  is releasably received. 
     As illustrated in  FIGS. 20 and 22 , when the locking lever  130  engages with the first free end  127  of the first flap portion  121 , the second projection  126  of the second flap portion  122  may be received in the recess  151  of the stopper  150 , and the first free end  127  of the first flap portion  121  may be received in the locking recess  131  of the locking lever  130  so that the flap  120  may keep at least the portion of the opening  92   d  of the swing guide  92  in the closed state. 
     As illustrated in  FIG. 21 , when the locking lever  130  releases the first free end  127  of the first flap portion  121 , the first free end  127  of the first flap portion  121  may be released from the locking recess  131  of the locking lever  130 , and the first projection  125  of the first flap portion  121  may be received in the recess  151  of the stopper  150  so that the first free end  127  of the first flap portion  121  or the second free end  128  of the second flap portion  122  may be kept in a released state from the locking lever  130 . When the center roller unit  23  moves toward the interior or exterior of the vehicle, the center roller unit  23  may push the flap  120  toward the interior or exterior of the vehicle so that the flap  120  may rotate freely. That is, the rollers  105  and  106  of the center roller unit  23  may push the first flap portion  121  or the second flap portion  122  of the flap  120  toward the interior or exterior of the vehicle so that the center roller unit  23  may be released from or be received in the swing guide  92 . 
     The locking lever  130  may move toward the release position by the release lever  140  as illustrated in  FIG. 23 . Referring to  FIGS. 17 and 19 , the release lever  140  may be rotatably mounted on the roller bracket  101  of the center roller unit  23  through a second hinge pin  143 . The release lever  140  may include a first end portion  141  operatively connected to the locking lever  130  and a second end portion  142  connected to a cable  148 . 
     The first end portion  141  may push the release shoulder  132  of the locking lever  130  so that the locking lever  130  may move to the release position. In particular, the release lever  140  may include a tip  145  extending from the first end portion  141  toward the locking lever  130 , and the tip  145  may press the release shoulder  132  of the locking lever  130  so that the locking lever  130  may move to the release position. The cable  148  may be fixed to the second end portion  142  through an end fitting  149 , and the cable  148  may be mechanically connected to the outside handle  6 . As the outside handle  6  is pulled, the cable may be pulled, and thus the release lever  140  may rotate. 
     The release lever  140  may move between a lock position (see the solid line in  FIGS. 22 and 23 ) and an unlock position (see the dotted line in  FIG. 23 ). The lock position refers to a position in which the release lever  140  holds the locking lever  130  in the engaging position, and the unlock position refers to a position in which the release lever  140  moves the locking lever  130  to the release position. In particular, the release lever  140  may be biased toward the lock position by a second biasing element  144 , and the second biasing element  144  may be a torsion spring disposed around the second hinge pin  143 . 
     Referring to  FIG. 22 , the locking lever  130  may engage with the first flap portion  121  of the flap  120  so that the second flap portion  122  may keep the portion of the opening  92   d  of the swing guide  92  in the closed state. Thus, in the sliding mode, the center roller unit  23  may not be separated from the swing guide  92  of the center rail  13 , and the center roller unit  23  may move along the center rail  13 . 
     Referring to  FIG. 23 , the locking lever  130  may release the first flap portion  121  of the flap  120  so that the first flap portion  121  of the flap  120  may be kept in the released state from the locking lever  130 . Thus, the flap  120  may freely rotate on the swing guide  92 , and in the swing mode, the center roller unit  23  may be released from or be received in the swing guide  92  of the center rail  13 . 
       FIGS. 24 to 26  illustrate a flap mechanism  210  according to another exemplary embodiment of the present disclosure. 
     Referring to  FIGS. 24 to 26 , the flap mechanism  210  according to another exemplary embodiment of the present disclosure may include a flap  220  which is mounted to open and close the opening  92   d  of the swing guide  92 , and a driving motor  250  which rotates the flap  220 . 
     Referring to  FIG. 24 , the swing guide  92  may have a hinge lug  295  protruding from the top wall  92   a , and the flap  220  may have a pair of hinge lugs  221  and  222 . The pair of hinge lugs  221  and  222  may be connected to the hinge lug  295  of the swing guide  92  through a hinge pin so that the flap  220  may be rotatably mounted on the top wall  92   a  of the swing guide  92 . The flap  220  may have an area sufficient to cover the upper portion of the opening  92   d  of the swing guide  92 . 
     The driving motor  250  may be mounted on the top wall  92   a  of the swing guide  92 , and a shaft  251  of the driving motor  250  may be connected to one of the pair of hinge lugs  221  and  222 . By the rotation of the driving motor  250 , the flap  220  may open and close at least a portion of the opening  92   d  of the swing guide  92 . 
     The driving motor  250  may be electrically connected to the selector  4 o of the outside handle  6 , and its operation may be switched as the sliding mode or the swing mode is selected by the selector  4 o. For example, when the sliding mode is selected by the first switch  41 , the driving motor  250  may operate the flap  220  to close the opening  92   d  of the swing guide  92 , and when the swing mode is selected by the second switch  42 , the driving motor  250  may operate the flap  220  to open the opening  92   d  of the swing guide  92 . 
     Referring to  FIG. 25 , the driving motor  250  may operate to allow the flap  220  to close the opening  92   d  of the swing guide  92  so that the flap  220  may keep the opening  92   d  of the swing guide  92  in a closed state. Thus, in the sliding mode, the center roller unit  23  may not be separated from the swing guide  92  of the center rail  13 , and the center roller unit  23  may move along the center rail  13 . 
     Referring to  FIG. 26 , the driving motor  250  may operate to allow the flap  220  to open the opening  92   d  of the swing guide  92  so that the flap  220  may keep the opening  92   d  of the swing guide  92  in an open state. Thus, in the swing mode, the center roller unit  23  may be released from or be received in the swing guide  92  of the center rail  13 . 
       FIGS. 27 and 28  illustrate a flap mechanism  310  according to another exemplary embodiment of the present disclosure. 
     Referring to  FIGS. 27 and 28 , the flap mechanism  310  according to another exemplary embodiment of the present disclosure may include a flap  320  which is movable to open and close the opening  92   d  of the swing guide  92 , and a driving motor  350  which drives the flap  320 . 
     The flap  320  may include a first flap portion  321  and a second flap portion  322  rotatably connected to the first flap portion  321 , and the first flap portion  321  may be rotated by the driving motor  350 . A shaft  351  of the driving motor  350  may be connected to a first end portion of the first flap portion  321 , so that the first flap portion  321  may be rotated by the driving motor  350 . A first end portion of the second flap portion  322  may be rotatably connected to a second end portion of the first flap portion  321  through a hinge pin  324 . The second flap portion  322  may have an area sufficient to cover the upper portion of the opening  92   d  of the swing guide  92 . 
     The driving motor  3500  may be mounted on the top wall  92   a  of the swing guide  92 , and the shaft  351  of the driving motor  350  may be connected to the first flap portion  321  so that the first flap portion  321  may rotate. As the first flap portion  321  rotates, the second flap portion  322  may move upwardly and downwardly, and thus the second flap portion  322  may open and close the opening  92   d  of the swing guide  92 . 
     The driving motor  350  may be electrically connected to the selector  4 o of the outside handle  6 , and its operation may be switched as the sliding mode or the swing mode is selected by the selector  40 . For example, when the sliding mode is selected by the first switch  41 , the driving motor  350  may operate the flap  320  to close the opening  92   d  of the swing guide  92 , and when the swing mode is selected by the second switch  42 , the driving motor  350  may operate the flap  320  to open the opening  92   d  of the swing guide  92 . 
     Referring to  FIG. 27 , the driving motor  250  may operate to allow the second flap portion  322  of the flap  320  to close the opening  92   d  of the swing guide  92  so that the flap  320  may keep the opening  92   d  of the swing guide  92  in a closed state. Thus, in the sliding mode, the center roller unit  23  may not be separated from the swing guide  92  of the center rail  13 , and the center roller unit  23  may move along the center rail  13 . 
     Referring to  FIG. 28 , the driving motor  250  may operate to allow the second flap portion  322  of the flap  320  to open the opening  92   d  of the swing guide  92  so that the flap  320  may keep the opening  92   d  of the swing guide  92  in an open state. Thus, in the swing mode, the center roller unit  23  may be released from or be received in the swing guide  92  of the center rail  13 . 
       FIGS. 29 and 30  illustrate a flap mechanism  410  according to another exemplary embodiment of the present disclosure. 
     Referring to  FIGS. 29 and 30 , the flap mechanism  410  according to another exemplary embodiment of the present disclosure may include a flap  420  which is linearly movable to open and close the opening  92   d  of the swing guide  92 , and a driving motor  450  which drives the flap  420 . 
     The flap  420  may include a flap portion  421  linearly movable to open and close the opening  92   d  of the swing guide  92 , an extension portion  422  extending from a top end of the flap portion  421  toward the inboard side wall  92   b  of the swing guide  92 , and a guide  423  extending from the extension portion  422  toward the bottom wall  92   c  of the swing guide  92 . 
     The guide  423  may be connected to the driving motor  450  through a rack and pinion. The guide  423  may have rack teeth  462 , and a pinion  461  meshing with the rack teeth  462  may be connected to a shaft of the driving motor  450 . As a rotation force of the driving motor  450  may be transmitted to the guide  423  through the pinion  461  and the rack teeth  462 , the flap portion  421  may linearly move to open and close the opening  92   d  of the swing guide  92 . 
     The driving motor  450  may be electrically connected to the selector  40  of the outside handle  6 , and its operation may be switched as the sliding mode or the swing mode is selected by the selector  40 . For example, when the sliding mode is selected by the first switch  41 , the driving motor  450  may operate the flap  420  to close the opening  92   d  of the swing guide  92 , and when the swing mode is selected by the second switch  42 , the driving motor  450  may operate the flap  420  to open the opening  92   d  of the swing guide  92 . 
     Referring to  FIG. 29 , the driving motor  450  may operate to allow the flap portion  421  of the flap  420  to close the opening  92   d  of the swing guide  92  so that the flap  420  may keep the opening  92   d  of the swing guide  92  in a closed state. Thus, in the sliding mode, the center roller unit  23  may not be separated from the swing guide  92  of the center rail  13 , and the center roller unit  23  may move along the center rail  13 . 
     Referring to  FIG. 30 , the driving motor  450  may operate to allow the flap portion  421  of the flap  420  to open the opening  92   d  of the swing guide  92  so that the flap  420  may keep the opening  92   d  of the swing guide  92  in an open state. Thus, in the swing mode, the center roller unit  23  may be released from or be received in the swing guide  92  of the center rail  13 . 
       FIGS. 1 to 30  illustrate the vehicle door opening and closing apparatus according to exemplary embodiments of the present disclosure applied to the rear door  5 . However, the vehicle door opening and closing apparatus according to exemplary embodiments of the present disclosure may be applied to various vehicle doors, such as front doors, in addition to rear doors. 
       FIGS. 31 and 32  illustrate the vehicle door opening and closing apparatus according to exemplary embodiments of the present disclosure applied to the front door  4 .  FIG. 31  illustrates a state in which the front door  4  is opened in the sliding mode, and  FIG. 32  illustrates a state in which the front door  4  is opened in the swing mode. 
       FIGS. 33 and 34  illustrate the vehicle door opening and closing apparatus according to exemplary embodiments of the present disclosure applied to both the front door  4  and the rear door  5 .  FIG. 33  illustrates a state in which the front door  4  and the rear door  5  are opened in the sliding mode, and  FIG. 34  illustrates a state in which the front door  4  and the rear door  5  are opened in the swing mode. 
     As set forth above, the vehicle door opening and closing apparatus according to exemplary embodiments of the present disclosure may perform the opening and closing operations of the vehicle door by selectively switching the sliding mode and the swing mode, thereby meeting the needs of customers such as convenience and diversity. In addition, it may select the opening and closing operations of the vehicle door by taking the customer&#39;s situation and environment into consideration, thereby improving convenience and quality. 
     In particular, it may prevent the center roller unit from being separated from the center rail in the sliding mode, and allow the center roller unit to be released from the center rail in the swing mode, and thus the vehicle door may be reliably opened and closed in either the sliding mode or the swing mode. 
     In terms of vehicle specifications, the vehicle door opening and closing structure may be standardized, regardless of vehicle models. Thus, the manufacturing cost and investment cost may be significantly reduced. 
     Hereinabove, although the present disclosure has been described with reference to exemplary embodiments and the accompanying drawings, the present disclosure is not limited thereto, but may be variously modified and altered by those skilled in the art to which the present disclosure pertains without departing from the spirit and scope of the present disclosure claimed in the following claims.