Patent Publication Number: US-11039666-B2

Title: Plug for buckle, and buckle

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based on Japanese Patent Application (No. 2018-229761) filed on Dec. 7, 2018, the contents of which are incorporated herein by way of reference. 
     BACKGROUND 
     The present disclosure relates to a plug used for a buckle including the plug and a socket that detachably connect separate parts of a tape, a belt, and other members, and a buckle using the plug. 
     In a related art, for example, there is a buckle disclosed in Patent Document 1 as a buckle that detachably connects two objects to be connected. The buckle includes a plug and a socket, and the plug includes a pair of leg portions extending in one direction from both end portions in a width direction and locking portions protruding away from each other at distal end portions of the pair of leg portions. The socket includes a main body portion that houses the leg portion of the plug, and the main body portion is formed by an upper flat plate portion, a right side wall portion, a left side wall portion, and a lower flat plate portion. At rear end portions of the right wall portion and the left side wall portion, engaged portions are provided. The locking portions of the leg portions of the plug are locked to the engaged portions. And the locking portions of the plug abut on the engaged portions of the locking holes of the socket so as not to be drawn out. 
     Patent Document 1: Japanese Utility Model Registration No. 3207690 
     In the background art, when an impact is applied to the plug and the socket of the buckle in a pulling direction, a large force may be applied to a base of the leg portion of the plug, so that the leg portion may be damaged. When the leg portion is damaged, connection with the socket is inadvertently released, so that the buckle is disabled. 
     SUMMARY 
     At least one aspect of the present disclosure is to provide a plug which absorbs an impact applied to the buckle and prevents a leg portion of the plug from being damaged, and a buckle using the plug. 
     The present disclosure provides a plug for a buckle including the plug and a socket which are capable of being connected to and disconnected from each other and which are each attached to a predetermined member. The plug includes an attachment portion which is attached to the predetermined member; and a pair of leg portions which extend in the same direction from the attachment portion. An engagement portion is formed at the leg portion. The leg portion is bent at a plurality of bending points between the attachment portion and the engagement portion in an extending direction of the leg portion. Therefore, the leg portion has a meandering curve line shape, so that the leg portion has elasticity and can absorb an impact. 
     The leg portion is provided with the plurality of bending points in a meandering manner in a left-right direction in which the pair of the leg portions face each other. The pair of leg portions are bent in directions approaching each other or in directions separating from each other in the left-right direction until a first bending point, from a base end portion of the leg portion to the distal end portion. 
     Each of the leg portions is provided with two bending points, and the pair of leg portions are bent twice in the left-right direction and are formed in an S shape. Each of the leg portions may be provided with three or more bending points. 
     A total length of the leg portion when being straightened by stretching is approximately from 110% to 130% of a length from the attachment portion to the distal end portion. The leg portion is bent at the bending points with an absolute value from 10° to 15° with respect to the extending direction of the leg portion. 
     Further, the present disclosure also provides a buckle including the plug and a socket which is connectable to the plug. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a perspective view illustrating a plug and a socket of a buckle that are not engaged with each other according to an embodiment of the present invention. 
         FIG. 2  is a perspective view illustrating the plug and the socket of the buckle that are connected with each other according to the embodiment. 
         FIGS. 3A to 3D  are a top view ( 3 A), a front view ( 3 B), a right side view ( 3 C), and a bottom view ( 3 D) of the plug of the buckle according to the embodiment. 
         FIGS. 4A to 4D  are a top view ( 4 A), a front view ( 4 B), a back side view ( 4 C), and a bottom view ( 4 D) of the socket of the buckle according to the embodiment. 
         FIGS. 5A to 5D  are a top view ( 5 A), a front view ( 5 B), a right side view ( 5 C), and a bottom view ( 5 D) illustrating a modification of the plug of the buckle according to the embodiment. 
     
    
    
     DETAILED DESCRIPTION OF EXEMPLIFIED EMBODIMENTS 
     A buckle  10  according to an embodiment of the present invention will be described below with reference to  FIGS. 1 to 4D . The buckle  10  includes a plug  12  and a socket  14  into which the plug  12  is fitted and engaged, and each of the plug  12  and the socket  14  is attached to a member such as a belt, a tape, or the like that is arbitrarily connected to and disconnected from each of the plug  12  and the socket  14 . In the following description, an extending direction of a pair of leg portions  20 , which will be described below, of the plug  12  is referred to as a lower direction, and a reverse direction of the lower direction is referred to as an upper direction. A direction which is orthogonal to an upper-lower direction and in which the pair of leg portions  20  face each other, is referred to as a left-right direction. A direction orthogonal to the left-right direction and the upper-lower direction is referred to as a front-back direction or a thickness direction. 
     The plug  12  is formed by integral molding with a synthetic resin which is polyacetal, polyamide, polypropylene, or the like. As illustrated in  FIGS. 3A to 3D , the plug  12  includes a tape threading portion  24  which is an attachment portion to which a member such as a belt, a tape, or the like is attached, the pair of leg portions  20  which extend in the same direction from the tape threading portion  24  and which are inserted into the socket  14 , and engagement portions  22  which are integrally provided at the leg portions  20 . For example, the engagement portions  22  are provided at positions close to distal end portions  20   a  of the leg portions  20 . In this case, a distance between the distal end portion  20   a  of the leg portion  20  and the engagement portion  22  is shorter than a distance between the tape threading portion  24  and the engagement portion  22 . However, the engagement portions  22  may be provided at the other positions of the leg portions  20 . 
     The pair of leg portions  20  extend with the same length in a mutually symmetrical shape, and extending directions from base end portions  20   b  continuous from the tape threading portion  24  toward the distal end portions  20   a  are parallel to each other. Each of the leg portions  20  is provided with first bending points  26  and second bending points  28  at predetermined intervals along the extending direction, and is formed in a curve meandering in an S shape. All of the predetermined intervals may be the same or different. The pair of leg portions  20  are first inclined with respect to the upper-lower direction so as to approach each other in a vicinity of the base end portions  20   b  continuous from the tape threading portion  24 , as a distance from the tape threading portion  24  increases. The first bending points  26  are at positions slightly away from the base end portions  20   b , and the pair of leg portions  20  are bent in directions away from each other in the left-right direction at the first bending points  26 . 
     As illustrated in  FIG. 3B , with respect to the upper-lower direction, an angle of the leg portion  20  in a vicinity of the first bending point  26  at a side of approaching the first bending point  26  is an angle α 1 , and an angle of the leg portion  20  in the vicinity of the first bending point  26  at a side of separating from the first bending point  26  is an angle α 2 . The second bending points  28  are between the first bending points  26  and the distal end portions  20   a , and the pair of leg portions  20  are bent in directions approaching each other in the left-right direction at the second bending points  28 . With respect to the upper-lower direction, an angle of the leg portion  20  in a vicinity of the second bending point  28  at a side of approaching the second bending point  28  is an angle ( 31 , and an angle of the leg portion  20  in the vicinity of the second bending point  28  at a side of separating from the second bending point  28  is an angle β 2 . Outer side surfaces of the pair of leg portions  20  that do not face each other between the first bending point  26  and the distal end portion  20   a  form operation portions  30  that swell outward. Here, the angle α 1 , the angle α 2 , the angle β 1 , and the angle β 2  are arbitrary angles having an absolute value in a range from 10° to 15°. In other words, an angle of a line between the continuous bending points with respect to the extending direction of the leg portion  20  has an absolute value from 10° to 15°. All of the angles may be the same or different, or α 1  and α 2  or β 1  and β 2  may be the same while α and β may be different. A total length of the leg portion  20  when being straightened by stretching is approximately from 110% to 130% of the length L from the tape threading portion  24  to the distal end portion  20   a  illustrated in  FIG. 3B , for example, 120%. 
     The engagement portions  22  are provided so as to protrude in both front and back directions from the leg portions  20 . For example, the engagement portions  22  are provided so as to protrude from the positions close to the distal end portions  20   a  of the leg portions  20 . However, the engagement portions  22  may be provided so as to protrude from the other positions of the leg portions  20  The engagement portions  22  include locking step portions  22   a  each facing a base end portion  20   b  side of each of the leg portions  20 . The locking step portions  22   a  are formed to be engageable with engaged portions  50  or housing recess portions  62 , which will be described below, of the socket  14 . 
     A U-shaped bridge  32  which connects vicinities of the distal end portions  20   a  is integrally provided on inner side surfaces of the pair of leg portions  20  that face each other near the distal end portions  20   a . Both end portions of the bridge  32  are continuous from the inner side surfaces near the distal end portions  20   a . A central part of the bridge  32  extends toward the base end portions  20   b , and is curved in a U-shape near a lateral side of the first bending points  26  of the pair of leg portions  20 . 
     A V-shaped bridge  33  which connects vicinities of the base end portions  20   b  of the pair of leg portions  20  is integrally provided on inner side surfaces of the pair of leg portions  20  that face each other near the base end portions  20   b . The bridge  33  is formed slightly thicker than the bridge  32 . Both end portions of the bridge  33  are continuous from inner side surfaces near the base end portions  20   b . A central part of the bridge  33  extends toward a distal end portion  20   a  side, and is bent into a V shape at a position which does not reach the first bending points  26  of the pair of legs  20 . A central part of the bridge  33  has a slight gap from the bridge  32 . 
     In the tape threading portion  24 , a first bar  34  and a second bar  36  are provided in parallel to each other in the left-right direction. The first bar  34  extends from both end portions thereof, and connects to the base end portions  20   b  of the leg portions  20 . A second bar  36  is located on an opposite side of the leg portion  20  in the first bar  34 . And both end portions of each of the first bar  34  and the second bar  36  are connected by side surface portions  38 . A tape insertion hole  24   a  is formed between the first bar  34  and the second bar  36 . A space is also formed in a part surrounded by the first bar  34  and the bridge  33  of the pair of leg portions  20  to form a tape insertion hole  24   b.    
     A thickness of each portion of the plug  12  is formed such that the leg portion  20  is thinner than the side surface portion  38  of the tape threading portion  24 , and a thickness of the vicinity of the base end portion  20   b  of the leg portion  20  is a thickness between the side surface portion  38  and the leg portion  20 . The bridge  33  is formed with substantially the same thickness as the base end portion  20   b , and a V-shaped distal end part of the bridge  33  is formed with slightly thin thickness and is a groove portion  33   a  into which a guide protrusion  58  of the socket  14  is fitted. The guide protrusion  58  will be described below. The engagement portions  22  protrude from the leg portions  20  to both sides in the front-back direction, and protruding surfaces are flat and are slightly thinner than the thicknesses of the base end portion  20   b  and the bridge  33 . The bridge  32  is thinnest and thinner than the leg portions  20 . 
     The socket  14  is also formed by integral molding with a synthetic resin which is polyacetal, polyamide, polypropylene, or the like. As illustrated in  FIGS. 4A to 4D , the socket  14  includes a fitting portion  40  into which the leg portions  20  of the plug  12  are inserted, and a tape threading portion  42  to which a member such as a belt, a tape, or the like is attached. The tape threading portion  42  is formed with a tape insertion hole  42   a  through which a tape member or the like is inserted and a connection bar  44  which is configured to connect the tape member or the like. Both end portions of the connection bar  44  are connected to a pair of side surface portions  45  which are long in the upper-lower direction. 
     At an end portion of the side surface portion  45  located on an opposite side of the connection bar  44 , a front surface portion  46  and a back surface portion  48  are provided and face each other with a predetermined interval therebetween to form the fitting portion  40  into which the plug  12  is inserted. The front surface portion  46  has a substantially H shape, and is formed by a pair of plate-shaped long plate portions  46   a  and a short horizontal plate portion  46   b . The pair of plate-shaped long plate portions  46   a  are located in an extending direction of the side surface portion  45 , and extend toward an opposite side of the tape threading portion  42 . The short horizontal plate portion  46   b  intersects the long plate portion  46   a  at a substantially right angle. The horizontal plate portion  46   b  is provided at a position close to an end portion of the long plate portion  46   a  away from the tape threading portion  42 . The back surface portion  48  has substantially the same H shape as the front surface portion  46 , and is formed by a pair of plate-shaped long plate portions  48   a  and a short horizontal plate portion  48   b . The pair of plate-shaped long plate portions  48   a  are located in the extending direction of the side surface portion  45  and extend toward the opposite side of the tape threading portion  42 . The short horizontal plate portion  48   b  intersects the long plate portion  48   a  at a substantially right angle. The horizontal plate portion  48   b  is provided at a position close to an end portion of the long plate portion  48   a  away from the tape threading portion  42 . The back surface portion  48  is provided with the engaged portions  50  by cutting corner portions of the pair of long plate portions  48   a  located on a tape insertion hole  42   a  side into a rectangular shape. 
     The front surface portion  46  and the back surface portion  48  face each other at a predetermined interval, and cantilever-shaped side surface portions  52  are provided at end portions on the opposite side of the tape threading portion  42 . The cantilever-shaped side surface portions  52  connect end portions outside the long plate portions  46   a  of the front surface portion  46  and end portions outside the long plate portions  48   a  of the back surface portion  48 . A pair of the side surface portions  52  are provided on left and right sides, and the fitting portion  40  is formed in a cylindrical shape, so that operation spaces are formed between the side surface portions  52  and the fitting portion  40 . A housing space  40   b  into which the plug  12  is inserted, is formed between the front surface portion  46  and the back surface portion  48 , and an opposite side of the tape threading portion  42  in the housing space  40   b  is an insertion opening  40   a  into which the plug  12  is inserted. 
     The side surface portions  52  are elongated plate bodies each extending from the insertion opening  40   a  to a vicinity of each of the side surface portions  45  of the tape threading portion  42 . End portions of the side surface portions  52  on an insertion opening  40   a  side are connected to the front surface portion  46  and the back surface portion  48  and are a part of the insertion opening  40   a . The end portions of the side surface portions  52  on an insertion opening  40   a  side serve as fixed ends. End portions near the side surface portions  45  on an opposite side of the end portions of the side surface portions  52  on the insertion opening  40   a  side are cantilevers which serve as free ends, and swing in the left-right direction. The swinging free ends serve as operation portions  54 , which is configured to release engagement of the plug  12  engaged with the socket  14 . An outer side surface of each of the operation portions  54  has a shape which extends slightly outward, so that the outer side surface of each of the operation portions  54  is easy to push from outside. A small protrusion on an inner side surface of each of the operation portions  54  protrudes toward the housing space  40   b  and is shaped such that the thin operation portion  30  of the engaged plug  12  is reliably pressed. The front surface portion  46  and the back surface portion  48  are formed such that only short parts of the end portions on the insertion opening  40   a  side is continuous from the side surface portion  52  to form the insertion opening  40   a  in a cylindrical shape, and space from the insertion opening  40   a  to the side surface portions  45  defines opened slits  56 . 
     Outer side surfaces of the front surface portion  46  and the back surface portion  48 , which do not face each other, are formed flat. On an inner side surface of the front surface portion  46 , a pair of linear guide protrusions  58  and a pair of guide protrusions  60  are provided on the left and right sides. The pair of linear guide protrusions  58  run through the horizontal plate portion  46   b  in the upper-lower direction, and the pair of guide protrusions  60  are formed so as to be curved along the slits  56 . The pair of guide protrusions  60  are located such that a width in the left-right direction decreases from the insertion opening  40   a  toward the tape insertion hole  42   a  of the tape threading portion  42 . That is, both side walls of the pair of guide protrusions  60 , which face each other, serve as guide surfaces which are configured to elastically deform the leg portions  20 . Therefore the pair of leg portions  20  inserted into the insertion opening  40   a  are elastically deformed so as to approach each other along the guide protrusions  60  when an insertion amount increases. The guide protrusions  60  are formed continuously from the insertion opening  40   a  to the tape insertion hole  42   a , and housing recess portions  62 , in which the engagement portions  22  of the leg portions  20  are housed, are formed in a part continuous from the tape insertion hole  42   a.    
     Each of the housing recess portions  62  is formed by cutting a guide surface of the protrusion  60  into a rectangular shape and includes inner wall facing the tape threading portion  42 . Each of the inner walls faces the locking step portion  22   a  of the engagement portion  22  of the plug  12  so as not to be drawn out. The housing recess portions  62  are located at positions facing the engaged portions  50  and have substantially the same shape as the engaged portions  50 . 
     On an inner side surface of the back surface portion  48 , similarly to the front surface portion  46 , the pair of linear guide protrusions  58  and the pair of guide protrusions  60  are provided on the left and right sides. The pair of linear guide protrusions  58  run through the horizontal plate portion  48   b  in the upper-lower direction. The pair of guide protrusions  60  are formed so to be curved along the slits  56 . The pair of guide protrusions  60  are located such that the width in the left-right direction decreases from the insertion opening  40   a  toward the tape insertion hole  42   a  of the tape threading portion  42 , and reach the engaged portions  50 . 
     Next, engagement operation of the buckle  10  and a method of using the buckle  10  according to the embodiment will be described below. First, a method of attaching a tape member or the like to the plug  12  of the buckle  10  will be briefly described. The tape threading portion  24  of the plug  12  includes the first bar  34  and the second bar  36 . A tape member (not illustrated) for connection is inserted into the tape insertion hole  24   b  from a back surface side of the plug  12 . Then the tape member is inserted into a back surface side from a front surface side of the tape insertion hole  24   a  after passing through an outer periphery of the first bar  34 . And the tape member is superposed on the tape member itself and pulled out so as to be adjustable in length. On the other hand, a tape member or the like (not illustrated) attached to the socket  14  is connected to the one connection bar  44  so as not to be adjustable. 
     In the engagement operation of the plug  12  and the socket  14 , the leg portions  20  of the plug  12  is caused to face the insertion opening  40   a  of the socket  14 , and the plug  12  is pushed into the socket  14 . When the leg portions  20  are inserted into the housing space  40   b , the leg portions  20  are surrounded by four guide protrusions  60  on upper, lower, left, and right sides. And the leg portions  20  are elastically deformed so as to approach each other since an interval between the guide protrusions  60  decreases as the plug  12  is inserted. When the engagement portions  22  of the leg portions  20  reach the housing recess portions  62  of the front surface portion  46  or the engaged portions  50  of the back surface portion  48 , the elastic deformation is restored. And the engagement portions  22  are fitted into the housing recess portions  62  or the engaged portions  50 . The locking step portions  22   a  of the engagement portions  22 , which intersect and face a tape threading portion  24  side, abut against and engage with the inner walls of the engaged portions  50  or the housing recess portions  62 , which intersect and face a tape threading portion  42  side, so as not to be drawn out. Accordingly, the plug  12  and the socket  14  are connected reliably to each other and engaged with each other as illustrated in  FIG. 2 . At this time, the bridge  33  of the plug  12  is fitted into the insertion opening  40   a  of the socket  14  and closes the insertion opening  40   a . The guide protrusion  58  of the socket  14  is fitted into the groove portion  33   a  of the bridge  33  of the plug  12 , so that the socket  14  and the plug  12  are not shifted from each other in the left-right direction. The operation portions  30  of the plug  12  protrude outward from the slits  56  of the socket  14 , and the operation portions  54  of the socket  14  face the operation portions  30  with a slight gap therebetween. 
     Next, a case where an impact force is applied to the buckle  10  in the state where the plug  12  and the socket  14  are engaged with each other will be described. When an impact force is applied in a direction in which the plug  12  and the socket  14  of the buckle  10  are pulled apart, a strong pulling force is applied to the leg portions  20 . However, the angles α and β of lines between the continuous bending points with respect to the extending direction of the leg portion  20 , are changed. And the leg portions  20  itself are elastically deformed such that the bending of the leg portions  20  extends, thereby the impact is absorbed. Accordingly, the leg portions  20  are prevented from being damaged. 
     In order to release the connection between the plug  12  and the socket  14 , the pair of operation portions  54  are pressed from the outside to push the operation portions  30  of the plug  12 . And the leg portions  20  of the plug  12  is elastically deformed to positions where the engagement portions  22  do not face the engaged portions  50  of the socket  14  or the inner walls of the housing recess portions  62 . In this state, when the plug  12  and the socket  14  are slightly moved in directions away from each other, the engagement is easily released. 
     According to the buckle  10  in the embodiment, the leg portions  20  of the plug  12  are gently bent at the first bending point  26  and the second bending point  28  to be formed in the meandering curve. And the leg portions  20  are elastically deformed such that the bending extends when a shocking and strong tensile force is applied to the leg portions  20 , thereby a damper effect like a spring is exerted so as to absorb the impact. Therefore, even if a shocking and strong tensile force is applied to the buckle  10  in the state where the plug  12  and the socket  14  are engaged with each other, the impact can be absorbed reliably, and the leg portions  20  of the plug  12  can be prevented from being damaged. The leg portions  20  of the plug  12  are not damaged and the connection of the plug  12  and the socket  14  are not inadvertently released, so that safety can be secured. The leg portions  20  are prevented from being unusable due to breakage, and durability is improved since the leg portions  20  are not easily damaged. The engagement portions  22  protrude from the leg portions  20  in the front-back direction and are locked to the front surface portion  46  and the back surface portion  48  of the socket  14 . Therefore, a moment does not occur in the left-right direction when a pulling force is applied, the engagement portions  22  are stably locked, and an engagement force is high. 
     The first bending points  26  and the second bending points  28  are provided at a predetermined interval on the leg portions  20  in a longitudinal direction. Therefore, not only left and right elastic deformation but also elastic deformation in the upper-lower direction can be withstood. The leg portions  20  have appropriate elasticity. Therefore, releasing operation is easy and a release force is light. Meandering widths of the leg portions  20  are not excessively large, so that the elasticity is not excessively large and is appropriate, and the leg portions  20  have a high engagement force. 
     The plug for the buckle according to the present disclosure may be provided with three or more bending points. For example, in the leg portions  20  of a plug  64  illustrated in  FIG. 5B , first bending points  66 , second bending points  68 , third bending points  70 , and fourth bending points  72  are provided at predetermined intervals in order in a curve meandering in the left-right direction along the extending direction from the base end portions  20   b  toward the distal end portions  20   a . The pair of leg portions  20  are first inclined with respect to the upper-lower direction so as to approach each other in the vicinity of the base end portions  20   b  continuous from the tape threading portion  24  as a distance from the tape threading portion  24  increases. The first bending points  66  are at positions slightly away from the base end portions  20   b , and the pair of leg portions  20  are bent in directions away from each other in the left-right direction at the first bending points  66 . The pair of leg portions  20  are bent in directions approaching each other in the left-right direction at the second bending points  28 . The pair of leg portions  20  are bent again in the directions away from each other at the third bending points  70  and are bent again in the directions approaching each other at the fourth bending points  72 . Angles of the leg portions  20  near each of the bending points are arbitrary angles having an absolute value in the range from 10° to 15° with respect to the upper-lower direction. All of the angles may be the same or different. 
     The leg portion  20  of the plug  64  is also formed in a curve which is gently bent and meandering, so that even if a shocking and strong force is applied to the buckle  10  in the state where the plug  64  and the socket  14  are engaged with each other, the impact can be absorbed reliably and the leg portions  20  of the plug  64  can be prevented from being damaged. 
     The buckle and the plug for the buckle according to the present invention are not limited to the above-described embodiments, and a shape of each member such as the engagement portion, the bridge, the tape threading portion or the like can be changed freely.