Patent Publication Number: US-2021172237-A1

Title: Vehicle Door Opening and Closing Apparatus

Description:
REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of Korean Patent Application No. 10-2019-0164177, filed on Dec. 10, 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 to and from a passenger compartment. A vehicle door is closed to block the door aperture and is opened to enable ingress and egress of passengers to and from 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 
     Embodiments of he present disclosure solve 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 openings and close apparatus allowing a vehicle door to open and close in one mode selected from a sliding mode and a swing mode, and more particularly, to a vehicle door opening and closing apparatus in which a door-side hinge element and a roller-side hinge element of a center roller unit are selectively connected to or released from each other according to a sliding mode and 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 sliding mode and a swing mode. In particular, a door-side hinge element and a roller-side hinge element of a center roller unit are selectively connected to or released from each other according to the sliding mode and the swing mode. 
     According to an aspect of the present disclosure, a vehicle door opening and closing apparatus may include a vehicle body having a door frame defining a door aperture, a vehicle door, a rail mounted on the 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 an edge of the door aperture, and a center roller unit including rollers guided along the center rail, a roller bracket having the rollers mounted thereon, a roller-side hinge element connected to the roller bracket, and a door-side hinge element rotatably connected to the roller-side hinge element, wherein the roller-side hinge element and the door-side hinge element may be releasably connected. 
     The roller-side hinge element may be releasably connected to the door frame by a grip unit. 
     The roller-side hinge element and the door-side hinge element may be releasably connected by a slide hinge, the roller-side hinge element may have a roller-side hinge hole, the door-side hinge element may have a door-side hinge hole aligned with the roller-side hinge hole, and the slide hinge may move along an axis of the roller-side hinge hole and an axis of the door-side hinge hole. 
     The slide hinge may include a base moving along the axis of the roller-side hinge hole and the axis of the door-side hinge hole, an extension portion extending from the base toward the door-side hinge element and the roller-side hinge element, and a hinge pin extending from the extension portion toward the axis of the roller-side hinge hole and the axis of the door-side hinge hole. 
     The hinge pin may be releasably inserted into the roller-side hinge hole and the door-side hinge hole by a movement of the base. 
     The base may be moved by a driving unit between a connection position in which the door-side hinge element and the roller-side hinge element are connected to each other and a release position in which the door-side hinge element and the roller-side hinge element are released from each other. 
     The driving unit may include a driving motor, a pinion coupled to a driving shaft of the driving motor, and rack teeth meshing with the pinion, and the rack teeth may be arranged in a longitudinal direction of the base. 
     The roller-side hinge element may have a hinge pin, the door-side hinge element may have a first recess receiving a portion of the hinge pin, the door-side hinge element may include a hinge lug moving along a circumference of the first recess, the hinge lug may have a second recess receiving a portion of the hinge pin, and the first recess and the second recess may selectively define a closed hinge hole or an open hinge hole by a movement of the hinge lug. 
     The hinge lug may move between a hold position in which the hinge lug holds the hinge pin and a release position in which the hinge lug allows the hinge pin to be released. 
     The first recess and the second recess may define the closed hinge hole allowing the hinge pin to be held when the hinge lug is in the hold position, and the first recess and the second recess may define the open hinge hole allowing the hinge pin to be released when the hinge lug is in the release position. 
     The grip unit may include a housing fixed to the door frame, a first grip member pivotally mounted on the housing, and a second grip member pivotally mounted on the housing. The first grip member and the second grip member may be spaced apart from each other and arranged to face each other. 
     The first grip member may be biased toward a center of the housing by a first biasing element, and the second grip member may be biased toward the center of the housing by a second biasing element. 
     The grip unit may include a housing fixed to the door frame, a first grip member slidably mounted on the housing, and a second grip member slidably mounted on the housing. The first grip member and the second grip member may be spaced apart from each other and arranged to face each other. 
     The first grip member may be biased toward a center of the housing by a first biasing element, and the second grip member may be biased toward the center of the housing by a second biasing element. 
     The grip unit may include a housing fixed to the door frame, a first grip member fixedly mounted on the housing, and a second grip member fixedly mounted on the housing. The first grip member and the second grip member may be spaced apart from each other and arranged to face each other, and the first grip member and the second grip member may elastically press the roller-side hinge element. 
     The first grip member may have a first closed cavity therein, and the second grip member may have a second closed cavity therein. 
    
    
     
       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 allowed 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 structure in which a center roller unit is disposed between a vehicle door and a center rail in a vehicle door opening and closing apparatus according to an exemplary embodiment of the present disclosure; 
         FIG. 18  illustrates a state of a center roller unit in which a door-side hinge element and a roller-side hinge element are connected by a slide hinge in a vehicle door opening and closing apparatus according to an exemplary embodiment of the present disclosure; 
         FIG. 19  illustrates a state in which the slide hinge moves with respect to the door-side hinge element and the roller-side hinge element in the center roller unit illustrated in  FIG. 18 ; 
         FIG. 20  illustrates a state in which the roller-side hinge element is released from the door-side hinge element in the center roller unit illustrated in  FIG. 19 ; 
         FIG. 21  illustrates a perspective view of a center rail in a vehicle door opening and closing apparatus according to another exemplary embodiment of the present disclosure; 
         FIG. 22  illustrates a state in which the door-side hinge element is released from the roller-side hinge element in the center roller unit illustrated in  FIG. 17 ; 
         FIG. 23  illustrates a state in which the door-side hinge element is connected to the roller-side hinge element, and the roller-side hinge element is released from a grip unit in the center roller unit illustrated in  FIG. 17 ; 
         FIG. 24  illustrates a grip unit of the center roller unit illustrated in  FIG. 17 ; 
         FIG. 25  illustrates a state of a center roller unit in which a door-side hinge element and a roller-side hinge element are connected by a hinge lug in a vehicle door opening and closing apparatus according to an exemplary embodiment of the present disclosure; 
         FIG. 26  illustrates a state in which the roller-side hinge element and the door-side hinge element are released by the hinge lug in the center roller unit illustrated in  FIG. 25 ; 
         FIG. 27  illustrates a state of a center roller unit in which a door-side hinge element and a roller-side hinge element are connected by a hinge lug in a vehicle door opening and closing apparatus according to an exemplary embodiment of the present disclosure; 
         FIG. 28  illustrates a state in which the roller-side hinge element and the door-side hinge element are released by the hinge lug in the center roller unit illustrated in  FIG. 27 ; 
         FIG. 29  illustrates a grip unit according to another exemplary embodiment of the present disclosure; 
         FIG. 30  illustrates a grip unit according to another exemplary embodiment of the present disclosure; 
         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 aft, 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 either a sliding mode or 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 or pulls the outside handle  6  toward the front or 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 or 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 held 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 held 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 , and a separate upper open hold lock (not shown) may releasably hold the second upper striker  31   b  in the first open position OP 1 . That is, the upper hold lock  31 , 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 . 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 . 
     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 , and a separate lower open hold lock (not shown) may releasably hold the second lower striker  32   b  in the first open position OP 1 . That is, the lower hold lock  32 , 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 . 
     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 the interior space or exterior 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 via. 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 via. 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 . As the cable  75  is reversed, the lever  73  may move the pawl  72  to the pawl release position (see  FIG. 10C ). 
     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 n 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, the other adjacent door  4  or other components may be spaced apart from the vehicle door  5  by a predetermined gap S 1  so that any interference with the door  4  or the other components may be prevented. For example, the vehicle door  5  may be a rear door, and the other 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 other adjacent door  4  may be relatively increased. If the gap S 1  between the vehicle door  5  and the other 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  610  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  6 i of the body  60  by welding, using fasteners, and/or the like, and 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 the other 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  in 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 both 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 rollers  105  and  106  of 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 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 Ti 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 rollers  105  and  106  of 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 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, according to the exemplary embodiment illustrated in  FIGS. 12 to 16 , when malfunction of the main latch  80  or deformation of the vehicle door  5  or the swing guide  92  due to an external impact occurs in the sliding mode, 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 fail to 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 be configured such that the rollers  105  and  106  of the center roller unit  23  may not be separated from the swing guide  92  of the center rail  13  in any mode of the sliding mode and the swing mode, and hinge elements  110  and  120  of the center roller unit  23  may be connected to or released from each other as either the sliding mode or the swing mode is selected. Thus, the vehicle door opening and closing apparatus may reliably open and close the vehicle door  5  in either the sliding mode or the swing mode. 
     Referring to  FIG. 21 , according to another exemplary embodiment, the swing guide  92  of the center rail  13  may have a stopper wall  99  extending from the stopper wall  95  of the sliding guide  91 . The swing guide  92  may use the stopper wall  99  to prevent the rollers  105  and  106  of the center roller unit  23  from being separated from the center rail  13 . Thus, the rollers  105  and  106  of the center roller unit  23  may not be separated from the center rail  13  in any mode of the swing mode and the sliding mode. 
     Referring to  FIGS. 17 to 20 , according to exemplary embodiments of the present disclosure, the center roller unit  23  may include a door-side hinge element  110  fixed to the vehicle door  5 , a roller-side hinge element  120  connected to the roller bracket  101  of the center roller unit  23 , and a slide hinge  130  releasably connecting the door-side hinge element  110  to the roller-side hinge element  120 . 
     The door-side hinge element  110  may include a door-side base  115  fixed to the vehicle door  5  by using fasteners, welding, and/or the like, and a first door-side hinge arm in and a second door-side hinge arm  112  extending from the door-side base  115 . 
     The first door-side hinge arm  111  may have a first door-side hinge hole  113 , and the second door-side hinge arm  112  may have a second door-side hinge hole  114 . The first door-side hinge arm in and the second door-side hinge arm  112  may be spaced apart from each other. 
     The roller-side hinge element  120  may be integrally connected to the roller bracket  101  of the center roller unit  23 . In particular, the roller-side hinge element  120  may be integrally formed with the roller bracket  101  so that the roller-side hinge element  120  and the roller bracket  101  may form a unitary one-piece structure. 
     The roller-side hinge element  120  may include a roller-side base  125  integrally connected to the roller bracket  101  of the center roller unit  23 , and a first roller-side hinge arm  121  and a second roller-side hinge arm  122  extending from the roller-side base  125 . The first roller-side hinge arm  121  may have a first roller-side hinge hole  123 , and the second roller-side hinge arm  122  may have a second roller-side hinge hole  124 . The first roller-side hinge arm  121  and the second roller-side hinge arm  122  may be spaced apart from each other. 
     The first door-side hinge arm in of the door-side hinge element  110  may be adjacent to or contact the first roller-side hinge arm  121  of the roller-side hinge element  120 , and an axis of the first door-side hinge hole  113  may be aligned with an axis of the first roller-side hinge hole  123 . The second door-side hinge arm  112  of the door-side hinge element  110  may be adjacent to or contact the second roller-side hinge arm  122  of the roller-side hinge element  120 , and an axis of the second door-side hinge hole  114  may be aligned with an axis of the second roller-side hinge hole  124 . A virtual axis which virtually extends along the axis of the first door-side hinge hole  113  and the axis of the first roller-side hinge hole  123  may be parallel to or be aligned with a virtual axis which virtually extends along the axis of the second door-side hinge hole  114  and the axis of the second roller-side hinge hole  124 . 
     The slide hinge  130  may include a base  135  movably mounted, a first extension portion  131  extending horizontally from a top end of the base  135  toward the first door-side hinge arm in and the first roller-side hinge arm  121 , a second extension portion  132  extending horizontally from a bottom end of the base  135  toward the second door-side hinge arm  112  and the second roller-side hinge arm  122 , a first hinge pin  133  extending vertically from the first extension portion  131 , and a second hinge pin  134  extending vertically from the second extension portion  132 . 
     The first hinge pin  133  may be releasably inserted into the first door-side hinge hole  113  and the first roller-side hinge hole  123 , and the second hinge pin  134  may be releasably inserted into the second door-side hinge hole  114  and the second roller-side hinge hole  124 . 
     The base  135  may move linearly with respect to the door-side hinge element  110  and the roller-side hinge element  120 , and the base  135  may move linearly along an axis of the base  135 . In particular, the axis of the base  135  may be parallel to the axis of the first door-side hinge hole  113 , the axis of the second door-side hinge hole  114 , the axis of the first roller-side hinge hole  123 , and the axis of the second roller-side hinge hole  124 , and thus a movement path of the base  135  may be parallel to the axis of the first door-side hinge hole  113 , the axis of the second door-side hinge hole  114 , the axis of the first roller-side hinge hole  123 , and the axis of the second roller-side hinge hole  124 . 
     The base  135  may be moved by a driving unit  150 , and the driving unit  150  may include a driving motor  151 , a pinion  152  coupled to a driving shaft of the driving motor  151 , and rack teeth  153  meshing with the pinion  152 . The rack teeth  153  may be arranged in a longitudinal direction of the base  135 . As the driving motor  151  rotates, the rotation of the pinion  152  may be delivered to the rack teeth  153 , and thus the base  135  may move linearly. 
     The slide hinge  130  may move between a connection position (see  FIG. 18 ) in which the door-side hinge element  110  and the roller-side hinge element  120  are connected to each other and a release position (see  FIGS. 19 and 20 ) in which the door-side hinge element  110  and the roller-side hinge element  120  are released from each other. 
     Referring to  FIG. 18 , when the slide hinge  130  is in the connection position, the first hinge pin  133  of the slide hinge  130  may be inserted into the first door-side hinge hole  113  of the door-side hinge element  110  and the first roller-side hinge hole  123  of the roller-side hinge element  120 , and the second hinge pin  134  of the slide hinge  130  may be inserted into the second door-side hinge hole  114  of the door-side hinge element  110  and the second roller-side hinge hole  124  of the roller-side hinge element  120 . The roller-side hinge element  120  may be pivotally connected to the door-side hinge element  110  by the slide hinge  130 . The center roller unit  23  may be configured such that the roller-side hinge element  120  may be pivotally connected to the door-side hinge element  110 , and thus the vehicle door  5  may be easily opened and closed in the sliding mode. 
     Referring to  FIG. 19 , when the slide hinge  130  is in the release position, the first hinge pin  133  of the slide hinge  130  may be released from the first roller-side hinge hole  123  of the roller-side hinge element  120 , and the second hinge pin  134  of the slide hinge  130  may be released from the second roller-side hinge hole  124  of the roller-side hinge element  120 . In this state, the roller-side hinge element  120  may be released from the door-side hinge element  110  as illustrated in  FIG. 20 . The center roller unit  23  may be configured such that the roller-side hinge element  120  may be released from the door-side hinge element  110 , and thus the vehicle door  5  may be easily opened and closed in the swing mode. 
     The vehicle body may have a door frame  3   a  defining the door aperture  3 . The center roller unit  23  according to exemplary embodiments of the present disclosure may be releasably connected to the door frame  3   a  by a grip unit  140 . 
     The roller-side hinge element  120  may be releasably connected to the door frame  3   a  by the grip unit  140 . 
     Referring to  FIG. 24 , according to an exemplary embodiment, the grip unit  140  may include a housing  149  fixed to the door frame  3   a  by welding, using fasteners, and/or the like, a first grip member  141  pivotally mounted on the housing  149 , and a second grip member  142  pivotally mounted on the housing  149 . 
     The housing  149  may receive the roller-side base  125  and at least portions of the roller-side hinge arms  121  and  122  of the roller-side hinge element  120 . The housing  149  may have a first sidewall  149   a  and a second sidewall  149   b , and the first sidewall  149   a  and the second sidewall  149   b  may be spaced apart from each other to receive the roller-side base  125  and the roller-side hinge arms  121  and  122  of the roller-side hinge element  120 . 
     The first grip member  141  and the second grip member  142  may be arranged to face each other and be spaced apart from each other by a gap corresponding to a width of the roller-side base  125  of the roller-side hinge element  120 . 
     The first grip member  141  may be pivotally mounted on the first sidewall  149   a  of the housing  149  by a first pivot pin  143 , and the first grip member  141  may be biased toward the center of the housing  149  by a first biasing element  147 . The first biasing element  147  may be spaced apart from the first pivot pin  143  in a longitudinal direction of the first sidewall  149   a , and the first biasing element  147  may be a coil spring interposed between the first sidewall  149   a  and the first grip member  141 . 
     The second grip member  142  may be pivotally mounted on the second sidewall  149   b  of the housing  149  by a second pivot pin  144 , and the second grip member  142  may be biased toward the center of the housing  149  by a second biasing element  148 . The second biasing element  148  may be spaced apart from the second pivot pin  144  in a longitudinal direction of the second sidewall  149   b , and the second biasing element  148  may be a coil spring interposed between the second sidewall  149   b  and the second grip member  142 . 
     The first grip member  141  and the second grip member  142  may grip both opposing edges of the roller-side base  125  by a biasing force of the first biasing element  147  and a biasing force of the second biasing element  148 . 
     The first grip member  141  may have a first engaging shoulder  145  with which a corresponding edge of the roller-side base  125  engages, and the second grip member  142  may have a second engaging shoulder  146  with which a corresponding edge of the roller-side base  125  engages. 
     When a force applied by the user to the roller-side base  125  of the roller-side hinge element  120  is greater than the forces of the biasing elements  147  and  148 , the roller-side base  125  of the roller-side hinge element  120  may be released from the first and second grip members  141  and  142 . That is, the grip unit  140  may release the roller-side hinge element  120 . 
     Referring to  FIG. 17 , in a state in which the door-side hinge element  110  is connected to the roller-side hinge element  120  by the slide hinge  130  moving to the connection position (see  FIG. 18 ), the roller-side hinge element  120  may be connected to the door frame  3   a  by the grip unit  140  so that the vehicle door  5  may be kept in a closed state. 
     Referring to  FIG. 22 , as the slide hinge  130  moves to the release position (see  FIG. 20 ) in a state in which the roller-side hinge element  120  is connected to the door frame  3   a  by the grip unit  140 , the door-side hinge element  110  may be released from the roller-side hinge element  120 , and thus the vehicle door  5  may be allowed to swing toward the exterior space of the vehicle. That is, the door-side hinge element  110  may be released from the roller-side hinge element  120  so that the vehicle door  5  may be opened and closed in the swing mode. 
     Referring to  FIG. 23 , as the slide hinge  130  moves to the connection position (see  FIG. 18 ), the door-side hinge element  110  may be connected to the roller-side hinge element  120 . In this state, when the user pushes the vehicle door  5  toward the rear of the vehicle, the rollers  105  and  106  of the center roller unit  23  may move toward the sliding guide  91  of the center rail  13 . Here, when the force applied by the user to the roller-side hinge element  120  is greater than the forces of the biasing elements  147  and  148 , the roller-side base  125  of the roller-side hinge element  120  may be released from the pair of grip members  141  and  142 . 
       FIGS. 25 and 26  illustrate a hinge structure of the center roller unit  23  according to another exemplary embodiment of the present disclosure. Referring to  FIGS. 25 and 26 , a hinge pin  230  may be mounted between the roller-side hinge arms  121  and  122  of the roller-side hinge element  120 , and the door-side hinge element  110  may be releasably connected to the hinge pin  230  by a pair of hinge lugs  118 . 
     The door-side hinge element  110  may have a first recess  113   a  receiving a portion of the hinge pin  230 , and the first recess  113   a  may be provided in each of the door-side hinge arms in and  112 . Each first recess  113   a  may have a radius corresponding to an outer diameter of the hinge pin  230 . In particular, the first recess  113   a  may have an arc shape allowing the hinge pin  230  to be released. The door-side hinge arms in and  112  may have a first inclined surface  119  extending obliquely from the first recess  113   a.    
     Each hinge lug  118  may have an arc shape, and the hinge lug  118  may be movably disposed on each of the door-side hinge arms in and  112  of the door-side hinge element  110 . In particular, the hinge lug  118  may be mounted to move along a circular path, which is defined by the circumference of the first recess  113   a , by a driving means (not shown) including a driving motor (not shown). The hinge lug  118  may have a second recess  118   a  receiving a portion of the hinge pin  230 . The second recess  118   a  may have a radius corresponding to the outer diameter of the hinge pin  230 , and the second recess  118   a  may have an arc shape allowing the hinge pin  230  to be released. The hinge lug  118  may have a first end surface  118   b  and a second end surface  118   c.    
     The hinge lug  118  may move between a hold position (see  FIG. 25 ) in which the hinge lug  118  holds the hinge pin  230  and a release position (see  FIG. 26 ) in which the hinge lug  118  allows the hinge pin  230  to be released. 
     As illustrated in  FIG. 25 , when the hinge lug  118  is in the hold position, the second recess  118   a  of the hinge lug  118  may be continuous with respect to the first recess  113   a  of the door-side hinge element  110  in a circumferential direction so that the first recess  113   a  and the second recess  118   a  may define a closed hinge hole. As the hinge pin  230  is held in the closed hinge hole defined by the first recess  113   a  and the second recess  118   a , the door-side hinge element  110  may be pivotally connected to the roller-side hinge element  120  by the hinge pin  230 . The closed hinge hole in this disclosure refers to a hole completely surrounded by the first recess  113   a  and the second recess  118   a.    
     As illustrated in  FIG. 26 , when the hinge lug  118  is in the release position, the first end surface  118   b  of the hinge lug  118  may be spaced apart from the first inclined surface  119  of the door-side hinge element  110  so that a space  291  allowing the movement of the hinge pin  230  may be formed between the first end surface  11813 , of the hinge lug  118  and the first inclined surface  119  of the door-side hinge element  110 . As the second recess  118   a  of the hinge lug  118  is not continuous with respect to the first recess  113   a  of the door-side hinge element  110  in the circumferential direction but is spaced apart from the first recess  113   a  of the door-side hinge element  110 , the first recess  113   a  and the second recess  118   a  may form an open hinge hole. As the hinge pin  230  is released through the space  291  of the open hinge hole, the door-side hinge element  110  may be released from the roller-side hinge element  120 . 
       FIGS. 27 and 28  illustrate a hinge structure of the center roller unit  23  according to another exemplary embodiment of the present disclosure. Referring to  FIGS. 27 and 28 , the door-side hinge element  110  may be releasably connected to the hinge pin  230  of the roller-side hinge element  120  by a pair of hinge lugs  228 . 
     Each hinge lug  228  may include a first portion  228   b  pivotally mounted on each of the door-side hinge arms in and  112  of the door-side hinge element  110  by a pivot pin  227 , and a second portion  228   c  having a second recess  228   a  receiving a portion of the hinge pin  230 . 
     Each hinge lug  228  may be biased toward the door-side hinge element  110  by a biasing element  229 . The biasing element  229  may be a torsion spring disposed around the pivot pin  227 . 
     The second recess  228   a  may have a radius corresponding to the outer diameter of the hinge pin  230 , and the second recess  228   a  may have an arc shape allowing the hinge pin  230  to be released. 
     The hinge lug  228  may have a second inclined surface  228   d  opposite to the first inclined surface  119  of the door-side hinge element  110 , and the second inclined surface  228   d  may extend obliquely at a free end of the second portion  228   c . For example, as illustrated in  FIGS. 27 and 28 , the first inclined surface  119  and the second inclined surface  228   d  may be symmetrical to each other with respect to the hinge pin  230 . 
     The hinge lug  228  may move between a hold position (see  FIG. 27 ) in which the hinge lug  228  holds the hinge pin  230  and a release position (see  FIG. 28 ) in which the hinge lug  228  allows the hinge pin  230  to be released. The hinge lug  228  may be biased toward the hold position (see  FIG. 27 ) by the biasing element  229 . When the user opens the vehicle door  5  in the swing mode, and a force applied to the door-side hinge element  110  is greater than a biasing force of the biasing element  229 , the hinge lug  228  may move to the release position (see  FIG. 28 ). 
     As illustrated in  FIG. 27 , when the hinge lug  228  is in the hold position, the second recess  228   a  of the hinge lug  228  may be continuous with respect to the first recess  113   a  of the door-side hinge element  110  in the circumferential direction so that the first recess  113   a  and the second recess  228   a  may define a closed hinge hole. The closed hinge hole in this disclosure refers to a hole completely surrounded by the first recess  113   a  and the second recess  228   a . As the hinge pin  230  is held in the closed hinge hole defined by the first recess  113   a  and the second recess  228   a , the door-side hinge element  110  may be pivotally connected to the roller-side hinge element  120  by the hinge pin  230 . 
     As illustrated in  FIG. 28 , when the hinge lug  228  is in the release position, the second inclined surface  228   d  of the hinge lug  228  may get farther away from the first inclined surface  119  of the door-side hinge element  110  so that a space  292  allowing the movement of the hinge pin  230  may be formed between the second inclined surface  228   d  of the hinge lug  228  and the first inclined surface  119  of the door-side hinge element  110 . As the second recess  228   a  of the hinge lug  228  is not continuous with respect to the first recess  113   a  of the door-side hinge element  110  in the circumferential direction but is spaced apart from the first recess  113   a  of the door-side hinge element  110 , the first recess  113   a  and the second recess  228   a  may form an open hinge hole. The open hinge hole in this disclosure refers to a C-shaped hole which is not completely surrounded by the first recess  113   a  and the second recess  228   a . As the hinge pin  230  is released through the open hinge hole, the door-side hinge element  110  may be released from the roller-side hinge element  120 . 
     When the user closes the vehicle door  5  in the swing mode in a state in which the door-side hinge element  110  is released from the roller-side hinge element  120 , and the force applied to the hinge lug  228  by the hinge pin  230  of the roller-side hinge element  120  is greater than the force of the biasing element  229 , the hinge pin  230  may push the second inclined surface  228   d  of the hinge lug  228  and the second inclined surface  228   d  of the hinge lug  228  may get farther away from the first inclined surface  119  of the door-side hinge element  110 . The hinge pin  230  may be inserted into the first recess  113   a  of the door-side hinge element  110  and the second recess  228   a  of the hinge lug  228 , and then the hinge lug  228  may hold the hinge pin  230  of the roller-side hinge element  120  by the biasing element  229 . 
       FIG. 29  illustrates a grip unit  240  according to another exemplary embodiment of the present disclosure. Referring to  FIG. 29 , the grip unit  240  may include a housing  249  fixed to the door frame  3   a  by welding, using fasteners, and/or the like, a first grip member  241  slidably mounted on a first sidewall  249   a  of the housing  249 , and a second grip member  242  slidably mounted on a second sidewall  249   b  of the housing  249 . 
     The housing  249  may receive the roller-side base  125  and at least portions of the roller-side hinge arms  121  and  122  of the roller-side hinge element  120 . The housing  249  may have the first sidewall  249   a  and the second sidewall  249   b , and the first sidewall  249   a  and the second sidewall  249   b  may be spaced apart from each other to receive the roller-side base  125  and the roller-side hinge arms  121  and  122  of the roller-side hinge element  120 . 
     The first grip member  241  and the second grip member  242  may be arranged to face each other and be spaced apart from each other by a gap corresponding to the width of the roller-side base  125  of the roller-side hinge element  120 . 
     The first grip member  241  may include a first roller  241   a  and a first roller support  241   b  supporting the first roller  241   a . The first grip member  241  may be biased toward the center of the housing  249  by a first biasing element  243 . The first sidewall  249   a  of the housing  249  may have a recess in which the first biasing element  243  is mounted, and the first biasing element  243  may push the first grip member  241  toward the center of the housing  249 . 
     The second grip member  242  may include a second roller  242   a  and a second roller support  242   b  supporting the second roller  242   a . The second grip member  242  may be biased toward the center of the housing  249  by a second biasing element  244 . The second sidewall  249   b  of the housing  249  may have a recess in which the second biasing element  244  is mounted, and the second biasing element  244  may push the second grip member  242  toward the center of the housing  249 . 
     The first grip member  241  and the second grip member  242  may grip both opposing edges of the roller-side base  125  by a biasing force of the first biasing element  243  and a biasing force of the second biasing element  244 . 
     When a force applied to the roller-side base  125  of the roller-side hinge element  120  is greater than the forces of the biasing elements  243  and  244 , the roller-side base  125  of the roller-side hinge element  120  may be released from the first and second grip members  241  and  242 . 
       FIG. 30  illustrates a grip unit  340  according to another exemplary embodiment of the present disclosure. Referring to  FIG. 30 , the grip unit  340  may include a housing  349  fixed to the door frame  3   a  by welding, using fasteners, and/or the like, a first grip member  341  fixedly mounted on a first sidewall  349   a  of the housing  349 , and a second grip member  342  fixedly mounted on a second sidewall  349   b  of the housing  349 . 
     The housing  349  may receive the roller-side base  125  and at least portions of the roller-side hinge arms  121  and  122  of the roller-side hinge element  120 . The housing  349  may have the first sidewall  349   a  and the second sidewall  349   b , and the first sidewall  349   a  and the second sidewall  349   b  may be spaced apart from each other to receive the roller-side base  125  and the roller-side hinge arms  121  and  122  of the roller-side hinge element  120 . 
     The first grip member  341  and the second grip member  342  may be arranged to face each other and be spaced apart from each other by a gap corresponding to the width of the roller-side base  125  of the roller-side hinge element  120 . 
     The first grip member  341  may be made of a synthetic resin material such as polyacetal, polyoxymethylene (POM), and may have a first closed cavity  343  therein. The first grip member  341  may elastically press the roller-side base  125  of the roller-side hinge element  120  by the first closed cavity  343 . 
     The second grip member  342  may be made of a synthetic resin material such as polyacetal, polyoxymethylene (POM), and may have a second closed cavity  344  therein. The second grip member  342  may elastically press the roller-side base  125  of the roller-side hinge element  120  by the second closed cavity  344 . 
     The first grip member  341  and the second grip member  342  may grip both opposing edges of the roller-side base  125  by an elastic force thereof. 
     When a force applied to the roller-side base  125  of the roller-side hinge element  120  is greater than the elastic force of the first and second grip members  341  and  342 , the roller-side base  125  of the roller-side hinge element  120  may be released from the first and second grip members  341  and  342 . 
       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, according to exemplary embodiments of the present disclosure, the door-side hinge element and the roller-side hinge element of the center roller unit may be released from each other when the vehicle door is opened and closed in the swing mode, and the door-side hinge element and the roller-side hinge element of the center roller unit may be connected to each other when the vehicle door is opened and closed in the sliding mode. Thus, the vehicle door may be reliably opened and closed in either the swing mode or the sliding 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.