Abstract:
A buckle device is provided with a lock plate that engages with a tongue plate that is inserted into the device body and that holds the tongue plate inside the device body, and a lock member that engages with the lock plate and prevents the lock plate from moving to a released position, and the lock member has a body portion and a shaft that supports the body portion within the device body. The body portion of the lock member is formed from a sintered metal, and the shaft is formed from a metal and is integrally press fit into the body portion. The strength of the shaft, which receives the load of the body portion, is secured and at the same time it is possible to achieve miniaturization and weight securement of the body portion.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   This application claims priority under 35 USC 119 from Japanese Patent Application No. 2005-304552, the disclosure of which is incorporated by reference herein. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a buckle device that structures a vehicle seat belt device and holds a tongue plate attached to webbing. 
   2. Description of the Related Art 
   Buckle devices currently known include, for example, a buckle device provided with a lock plate that is rotatably supported at the device body and that holds a tongue plate at the device body by approaching and engaging with a tongue plate inserted into the device body, and a lock member that engages with the lock plate in the above-described state of engagement and prevents separation of the lock plate from the tongue plate (see, for example, Japanese Patent Application Laid-Open (JP-A) No. 2003-125811). 
   In this kind of buckle device, when a release button mounted at the device body is operated by pressing, the lock member oscillates, allowing the separation of the lock plate from the tongue plate, and the holding of the tongue plate is thus released. 
   Incidentally, in buckle devices similar to that described above, the lock member is manufactured by fixing together with rivets two parts (a body portion and a counter-mass) formed by press working, and by having the lock member supported at the device body by a spindle part that is formed to project from one press worked part (the body portion), the lock member can oscillate around the spindle part. Further, in this kind of lock member, the two press worked parts are provided with a specified weight so as to achieve the so-called “counter effect”. 
   However, while there is a demand for miniaturization of buckle devices, limitations to the width dimensions of the lock member have made it difficult to secure the weight of the lock member. 
   SUMMARY OF THE INVENTION 
   The present invention takes the above factors into consideration and aims to attain a buckle device that can secure required strength and achieve both miniaturization and weight securement of the lock member. 
   In order to address the above problems, the buckle device of a first aspect of the invention includes a lock plate provided so as to be movable between an engagement position, at which the lock plate engages with a tongue plate inserted into a body of the device and holds the tongue plate within the body of the device, and a released position, at which the lock plate has been released from holding the tongue plate, and a lock member having a body portion provided so as to be able to oscillate between a locking position, at which the body portion engages with the lock plate positioned at the engagement position and prevents the lock plate from moving toward the released position, and an unlocked position, at which the body portion has been released from preventing movement of the lock plate, and a shaft that supports the body portion at the body of the device, with the body portion being formed from a sintered metal and the shaft being formed from a metal and integrally press fit into the body portion. 
   In the buckle device of the above aspect, when the tongue plate is inserted into the device body, the lock plate moves toward the engagement position and engages with the tongue plate, and the tongue plate is held inside the device body. In addition, the body portion of the lock member oscillates toward the locking position, engages with the lock plate and prevents the lock plate from moving toward the released position. As a result, an attached state of the tongue plate with respect to the present buckle device is achieved. 
   On the other hand, in the buckle device of the above aspect, when a release button provided at the device body is operated, the body portion of the lock member oscillates toward the unlocked position and the lock member is released from preventing the lock plate from moving. As a result, the lock plate moves to the released position and the lock plate is released from holding the tongue plate. 
   In the present buckle device, the body portion of the lock member is formed from a sintered metal, and the shaft that supports the body portion at the device body is formed from a metallic material (for example, stainless steel) and is integrally press fit into the body portion. Accordingly, the strength of the shaft, on which the load of the body portion acts, can be secured and it is also possible to achieve both miniaturization and weight securement of the body portion. 
   In the buckle device according to the above first aspect, a release button that is provided at the body of the device and that causes the body portion of the lock member to oscillate toward the unlocked position when the release button is operated by being pressed, a lock spring that is provided between the release button and the body portion of the lock member and that urges the body portion of the lock member toward the locking position, and a holder, formed from a resin, that is provided between the body portion of the lock member and the lock spring and is engaged with one end of the lock spring, may also be provided. 
   In the above structure, the lock spring provided between the release button and the body portion of the lock member urges the body portion of the lock member toward the locking position. One end of the lock spring is engaged with a holder that is formed from a resin and provided between the body portion of the lock member and the lock spring. Accordingly, even if the one end of the lock spring and the holder are in friction with each other when the body portion of the lock member oscillates, wear of the lock spring can be prevented and the durability of the lock spring is improved. 
   As explained above, in the buckle device according to the present invention, required strength is secured and it is also possible to achieve both miniaturization and weight securement of the lock member. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is an exploded perspective view showing the structure of a lock member, a holder and a lock spring of a buckle device according to an embodiment of the present invention. 
       FIG. 2  is a sectional view showing the overall configuration of a buckle device according to an embodiment of the present invention. 
       FIG. 3  is a sectional view showing the overall configuration of a buckle device according to an embodiment of the present invention. 
       FIG. 4  is an exploded perspective view showing the overall structure of a buckle device according to an embodiment of the present invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   In  FIG. 4 , the structure of a buckle device  10  according to an embodiment of the present invention is illustrated in exploded perspective view. Further, in  FIG. 3 , the structure of the buckle device  10  is illustrated in sectional view. 
   As shown in  FIG. 3 , the buckle device  10  is provided with a case  12 . The case  12  is formed as a box-shaped cylinder having an opening at either end in a length direction, with the opening at one end in a length direction being a tongue insertion opening  14  and the opening at the other end length direction being an anchor insertion opening  16 . Further, a buckle body  18  that structures the device body is accommodated at an inner side of the case  12 . 
   The buckle body  18  has a bottom plate part  20  formed in a long flat plate shape along the length direction of the case  12  and a pair of side wall parts  22  extending integrally from both sides in a width direction of the bottom plate part  20  toward one side in a plate-thickness direction of the bottom plate part  20  (the side in the direction of Arrow C), and as a whole is formed with an open-top box-shaped cross section. At the buckle body  18 , an insertion plate part  26  of a tongue plate  24  that is inserted from the tongue opening  14  of the case  12 , is inserted between the pair of side wall parts  22  from one end side in a length direction of the bottom plate part  20  (the side in the direction of Arrow B). 
   Further, the front edge part of an anchor plate  28  that is inserted from the anchor opening  16  of the case  12  is overlaid at the other end side in a length direction of the bottom plate part  20  (the side in the direction of Arrow A), and the bottom plate part  20  and the anchor plate  28  are coupled together and fixed by a rivet  30  that passes through the bottom plate part  20  and the anchor plate  28 . The anchor end side of the anchor plate  28  is fixed at the vehicle body at the seat side of the vehicle (both omitted from the drawings) and, in this way, the present buckle device  10  is attached to the vehicle. 
   In addition, an ejector  32  is disposed between the pair of side wall parts  22 . A part of the ejector  32  is engaged with a substantially rectangular through hole  34  formed at the bottom plate part  20 . The through hole  34  is formed to be long in the length direction of the bottom plate part  20  and the ejector  32  is able to slide within a predetermined range in the length direction of the bottom plate part  20  along the through hole  34 . 
   At an inner peripheral part of one end side in a length direction of the through hole  34  (the side in the direction of Arrow A), an engagement projection  36  is formed so as to protrude, and is engaged with one end of an ejector spring  38 , which is a compression coil spring. The other end of the ejector spring  38  is engaged with the ejector  32  and the ejector  32  is urged toward one end side in a length direction of the bottom plate part  20  (the side in the direction of Arrow B) by the urging force of the ejector spring  38 . 
   The ejector  32  is slid toward the other end side in a length direction of the bottom plate part  20  against the urging force of the ejector spring  38  when it is pushed by the insertion plate part  26  of the tongue plate  24  inserted between the pair of side wall parts  22  (the state shown in  FIG. 2 ). 
   On the other hand, the present buckle device  10  is provided with a lock plate  40 . The lock plate  40  is provided with a base part  42  formed in a long plate-shape along the length direction of the bottom plate part  20 . A pair of support parts  44  are formed so as to project toward either side in a width direction at the anchor end of the base part  42  (the end part at the side in the direction of Arrow A). The pair of support parts  44  penetrate support holes  46  formed at the respective side wall parts  22  of the buckle body  18 , and the lock plate  40  is supported by the pair of side wall parts  22  so as to be rotatable around the pair of support parts  44  (the support holes  46 ) to a predetermined angle. 
   Further, at the anchor end side of the base part  42 , a pair of arm parts  48  extend from either edge in a width direction toward the bottom plate part  20  side (the side in the direction of Arrow D). The pair of arm parts  48  are formed such that the respective leading end sides are positioned above the slide trajectory of the ejector  32 , and when the ejector  32  slides toward the other end side in a length direction of the bottom plate part  20  (the Arrow A direction side), the pair of arm parts  48  are pushed toward the other end side in a length direction of the bottom plate part  20  and the base part  42  (the lock plate  40 ) rotates toward the bottom plate part  20  side (the Arrow D direction side; engagement position). 
   An engagement piece  50  extends from the front edge of the base part  42  (the edge part at the Arrow B direction side) toward one side in a plate thickness direction of the base part  42  (the bottom plate part side; Arrow D direction side). The engagement piece  50  is formed such that the leading edge side thereof (the Arrow D direction side) is slightly inclined toward the one end side in a length direction of the bottom plate part  20  (the Arrow B direction side). Further, the leading edge part of the engagement piece  50  corresponds to the through hole  34  formed at the bottom plate part  20 , and when the lock plate  40  is rotated toward the bottom plate part  20  side (the engagement position) the engagement piece  50  passes through the through hole  34  and an engagement hole  26 A in the insertion plate part  26  inserted between the pair of side wall parts  22 , and restricts removal of the tongue plate  24  (supports the tongue plate  24 ) (the state shown in  FIG. 2 ). 
   A mounting part  32 A is formed at a surface at one side in a thickness direction (the Arrow C direction side) of the ejector  32  so as to correspond to the engagement piece  50  of the lock plate  40 . In a state in which the tongue plate  24  is not inserted between the pair of side wall parts  22 , i.e., in a state in which the ejector  32  is supported by the urging force of the ejector spring  38  at the other side in a length direction (the Arrow B direction side) of the through hole  34 , the mounting part  32 A intervenes with the leading edge part of the engagement piece  50  and restricts rotation of the lock plate  40  toward the bottom plate part  20  side (the engagement position) (supports the lock plate  40  in a released position) (the state shown in  FIG. 3 ). 
   In addition, a pair of contact pieces  52  are provided at either side in a width direction of the engagement piece  50  so as to extend from the front edge of the base part  42  toward the one end side (the Arrow B direction side) in a length direction of the bottom plate part  20 . The pair of contact pieces  52  correspond to a lock member  54 . 
   The lock member  54  is disposed at an opposite side to the bottom plate part  20  via the pair of contact pieces  52  and, as shown in  FIG. 1 , is provided with a body portion  56 . The body portion  56  is a sintered metal manufactured by the powder metallurgy method and is formed in a substantially triangular cylindrical shape having a length direction along a direction opposed to the pair of side wall parts  22 . 
   Further, the lock member  54  is provided with a shaft  58  that passes through the upper edge part (the edge part at the Arrow C direction side) of the body portion  56  along a length direction thereof. The shaft  58  is formed in a rod shape having a substantially rectangular cross section (a double D-cut shape) from a metallic material (stainless steel in the present embodiment). The shaft  58  is provided so as to be integrally press fit into a press fit hole  59  having a substantially rectangular cross section (a double D-cut shape) formed at the upper edge part of the body  56 . The respective end parts in an axial direction of the shaft  58  project from either end in a length direction of the body  56  and penetrate engagement holes  60  formed at the pair of side wall parts  22  such that the body  56  is supported at the pair of side wall parts  22  so that it can oscillate integrally with the shaft  58 . 
   A substantially plate-shaped pressed part  62  is integrally formed at the upper edge side of the body portion  56  (the opposite side to the bottom plate part; the Arrow C direction side) so as to extend toward the side opposite to the bottom plate part  20  (the Arrow C direction side). The pressed part  62  corresponds to a release button  70  described in the following. 
   Further, a lock surface  56 A is formed at the lower edge side (the bottom plate part  20  side; the Arrow D direction side) of the body portion  56 , which is formed in a circular arc shape concentric with the shaft  58 . In a state in which the lock plate  40  is disposed in the engagement position and the lock member  54  is disposed in the locking position (the state shown in  FIG. 2 ), the lock surface  56 A contacts against the upper surfaces (the surfaces at the Arrow C direction side) of the contact pieces  52  of the lock plate  40 . 
   In addition, a contact surface  56 B is formed at the side of one edge in a thickness direction (the Arrow A direction side) of the body portion  56 . In a state in which the lock plate  40  is disposed in the released position and the lock member  54  is disposed in the unlocked position (the state shown in  FIG. 3 ), the contact surface  56 B contacts against the front edges of the contact pieces  52  of the lock plate  40 . 
   Further, as shown in  FIG. 1 , a holder  64  is mounted at the other side in a thickness direction (the Arrow B direction side) of the body portion  56 . The holder  64  is formed from a resin material and is provided with a base  65 . The base  65  is formed lengthwise along the length direction of the body portion  56  and is inserted into a mounting groove  67  formed at the body portion  56 . 
   A pair of latch parts  69  extend from either side in a length direction of the base  65  toward one edge side in a width direction (the Arrow A direction side) of the body portion  56 . Claw parts  71  are formed to extend from the respective leading ends of the pair of latch parts  69  toward an inner side (the body portion  56  side) and the claw parts  71  are inserted into latch holes  73  formed at both end portions in a length direction of the body portion  56  (the latch parts  69  and the claw parts  71  are structured in the manner of a so-called “snap fit”). In this way, the holder  64  is mounted at the body portion  56 . 
   A spring hold part  75  is formed at a central portion in a length direction of the base  65  so as to extend toward the side opposite to the body portion  56  (the Arrow B direction side). The spring hold part  75  corresponds to a lock spring  86  described in the following. 
   On the other hand, the present buckle device  10  is provided with a release button  70  provided at one end side in a length direction of the buckle body  18 . The release button  70  has an operation part  72  that is operated by a passenger pressing it, and the operation part  72  is formed in a box shape that opens toward the other end side in a length direction (the Arrow A direction side) of the buckle body  18 . 
   A pair of arm parts  74  extend from either end in a width direction of the operation part  72  toward the other end side in a length direction (the Arrow A direction side) of the bottom plate part  20 . Projecting parts  76  are provided at the respective extremities of the pair of arm parts  74  so as to respectively extend toward the bottom plate part  20  side (the Arrow D direction side). Claw parts  78  are formed at the respective extremities of the pair of projecting parts  76  so as to respectively project toward the side of the respective side wall parts  22  (the inner side) and the claw parts  78  are inserted into long holes  80  respectively formed in the pair of side wall parts  22 . Each long hole  80  is formed lengthwise along the direction of insertion of the tongue plate  24  (the Arrow A direction) and each claw part  78  is able to move within a predetermined range along a length direction of the bottom plate part  20  in accordance with an inner peripheral portion of the long holes  80 . In this way, the direction of movement (operation direction) of the release button  70  is restricted by the long holes  80  to the length direction of the bottom plate part  20 . 
   Further, a connecting part  82  formed lengthwise along a direction opposing the pair of arm parts  74  in a substantially rod shape bridges across between the respective extremities of the pair of arm parts  74  such that the respective extremities of the pair of arm parts  74  are connected by the connecting part  82 . 
   In addition, at the release button  70 , a pressing part  84  is formed at the upper end side (the Arrow C direction side) of the operation part  72  so as to project toward the other end side (the Arrow A direction side) in a length direction of the bottom plate part  20 . The pressing part  84  is disposed so as to face the pressed part  62  of the lock member  54  described above, and when the release button  70  is operated by pressing, the pressed part  62  is pushed by the pressing part  84  toward the other end side (the Arrow A direction side) in a length direction of the bottom plate part  20  and the body portion  56  of the lock member  54  oscillates around the shaft  58  toward the one end side (the Arrow B direction side; the unlocked position) in a length direction of the bottom plate part  20 . 
   Further, a lock spring  86 , which is a compression coil spring, is disposed between the operation part  72  of the release button  70  and the lock member  54 . The holder  64  described above is disposed between one end of the lock spring  86  and the lock member  54 , and the spring hold part  75  of the holder  64  is engaged with the one end of the lock spring  86 . The other end of the lock spring  86  is press contacted against a lower wall portion of the operation part  72  of the release button  70 , and the lock member  54  is urged toward the locking position (the Arrow A direction side; the side opposite to the release button  70 ) by the urging force of the lock spring  86  via the holder  64 . 
   Next, the mechanism of the present embodiment is explained. 
   In the buckle device structured as described above, when the insertion plate part  26  of the tongue plate  24  is inserted into the case  12  from the tongue insertion opening  14  from the non-attached state shown in  FIG. 3 , the leading end of the insertion plate part  26  contacts against and pushes the end of the ejector  32 , causing the ejector  32  to slide to one end side in a length direction (the Arrow A direction side) of the through hole  34  against the urging force of the ejector spring  38 , as shown in  FIG. 2 . 
   When the ejector  32  slides a predetermined amount toward the one end side in a length direction of the through hole  34 , the mounting part  32 A of the ejector  32  and the engagement piece  50  of the lock plate  40  are released from a state of opposition and the ejector  32  pushes the pair of arm parts  48  of the lock plate  40 , causing the lock plate  40  to rotate toward the bottom plate part  20  side (the engagement position). 
   As a result, the leading edge part of the engagement piece  50  moves into the proximity of the bottom plate part  20 . Further, in this state, the engagement hole  26 A of the insertion plate part  26  and the through hole  34  formed at the bottom plate part  20  overlap each other. Accordingly, in this state, as shown in  FIG. 2 , the rotated engagement piece  50  passes through the engagement hole  26 A of the insertion plate part  26  and the through hole  34  of the bottom plate part  20 . 
   Further, by rotating the lock plate  40  to the engagement position, the state of contact between the contact pieces  52  of the lock plate  40  and the contact surface  56 B of the lock member  54  is released. Then, since the lock member is receiving the urging force of the lock spring  86  via the holder  64 , the body portion  56  of the lock member  54  oscillates toward the other end side (the Arrow A direction side; locking position) in a length direction of the bottom plate portion  20  due to the urging force of the lock spring  86  so as to engage with the rotation of the lock plate  40 , and the lock surface  56 A of the body portion  56  contacts the upper surfaces (the Arrow C direction side surface) of the contact pieces  52  (the state shown in  FIG. 2 ). As a result, rotation of the lock plate  40  toward the released position (rotation of the engagement piece in a direction away from the bottom plate part  20 ) is restricted and, as a result, an attached state (held state) of the tongue plate  24  with respect to the buckle device is achieved. 
   On the other hand, when the operation part  72  of the release button  70  is pressed and operated in the above attached state of the tongue plate  24 , the pressed portion  62  of the lock member  54  is pushed toward the other end side (the Arrow A direction side) in a length direction of the bottom plate part  20  by the pressing part  84  of the release button  70  and the body portion  56  of the lock member  54  oscillates toward the one end side (the Arrow B direction side; the unlocked position) in a length direction of the bottom plate part  20  against the urging force of the lock spring  86 . 
   As a result, the state of contact between the lock surface  56 A of the body portion  56  and the contact pieces  52  of the lock plate  40  is released and the rotation restriction (movement prevention) of the lock plate  40  by the lock member  54  is released. Moreover, since the urging force of the ejector spring  38  is acting on the engagement piece  50  of the lock plate  40  via the ejector  32  and the insertion plate part  26  of the tongue plate  24 , a component force acts on the engagement piece  50  in a direction away from the bottom plate part  20 . As a result, the lock plate  40  rotates away from the bottom plate part  20  toward the released position due to the component force acting on the engagement piece  50  and the holding of the tongue plate  24  by the engagement piece  50  is released. As a result, the ejector  32  is slid toward the other end side (the Arrow B direction side) in a length direction of the through hole  34  by the urging force of the ejector spring  38  and the insertion plate part  26  of the lock plate  40  is discharged from the insertion opening  14  of the case  12  by the sliding of the ejector  32 . 
   In the buckle device  10  according to the present embodiment the body portion  56  of the lock member  54  is formed from a sintered metal, and the shaft  58  that supports the body portion  56  at the buckle body  18  is formed from a metallic material (stainless steel in the present embodiment) and is press fit integrally into the body portion  56 . Accordingly, the strength of the shaft  58 , which receives the load of the body portion  56 , is sufficiently secured and miniaturization and weight securement of the body portion  56  can both be achieved. 
   Moreover, since, as described above, the body portion  56  is formed from a sintered metal, the degree of part precision of the body portion  56  is greatly improved over a case where the lock member is formed from pressed parts. As a result, even when, for example, a low-cost coating is applied to the body portion  56 , it is possible to secure the function (quality) of the lock member  54  and value engineering (VE) can be achieved. 
   Further, since conventional buckle devices have been structured such that one end of a lock spring urging a lock member to a locking position is directly engaged with a pressed part lock member (made of iron), the problem existed that the one end (the engaging portion described above) of the lock spring suffered wear due to friction between the one end of the lock spring and the lock member when the lock member oscillates. 
   In this regard, in the buckle device  10  according to the present embodiment, the holder  64  formed from a resin is mounted at the body portion of the lock member  54  and one end of the lock spring  86  is engaged with the spring hold part  75  of the holder  64 . As a result, it is possible to prevent wear of the one end of the lock spring  86  caused by oscillation of the body portion  56  and the durability of the lock spring  86  is greatly improved. As a result, it is possible, for example, to configure a smaller wire diameter for the lock spring  86 , to reduce the urging force and to improve the operationality of the release button  70 , and the function (quality) of the lock spring  86  can be secured while also achieving a reduction in the cost thereof. 
   As explained above, in the buckle device  10  according to the present embodiment, miniaturization and weight securement of the lock member  54  can both be achieved while also securing the necessary strength thereof.