The present invention relates to a buckle used in a seat belt device, more particularly, to a buckle of a compact construction for engaging with a tongue of the seat belt device.
A seat belt device used in a vehicle or the like comprises a tongue and a buckle for engaging with the tongue to fit a webbing, withdrawn from a retractor, with the body of an occupant. The buckle is generally fixed to a floor of the vehicle through a mounting plate or stalk. Thereby, the webbing can securely be supported by the buckle through the tongue even when a large tensile force is applied in the webbing when the vehicle comes into collision.
To raise the rate of wearing seat belt, the seat belt device is designed so that the tongue can be easily engaged to the buckle. Generally, the buckle is located on a side of a seat to reach easily. Because, in the case of a front seat, the position where the buckle is disposed is limited to a space between a driver's seat and a passenger seat. The buckle is designed to be miniaturized.
In manufacturing a buckle, the decrease of the number of parts constituting the buckle allows a lower manufacturing cost for the buckle.
In consideration of such points, some buckles have been proposed and developed. In Published Unexamined Japanese Patent Application No. (58)1983-27504, a small-sized buckle is proposed. The engagement and release of the buckle can be securely performed with a small number of moving elements. (See FIG. 1).
In the buckle, an L-like shaped rocker 108 biased in the initial state by a compression spring 109 mounted in a case tilts by a predetermined angle. Thereby, a retaining element 107 moves along the configuration of an L-shaped cutout 126. Moving of the retaining element 107 causes a latch (engaging element) 105 to pivot for locking and releasing operation of a tongue by a latch pawl 106. An ejector 104 is pushed by the end of a tongue plate 102 inserted along a tongue insertion path 139. Thereby the ejector 104 slides in the direction of the arrow X. The rocker 108 is then applied with the tilting force by the latch ejector 104. With the tilting of the rocker 108 in the direction of the arrow Y, an upper arm 124 of the rocker 108 moves the retaining element 107 downward along a front edge of the L-shaped cutout 126. The retaining element 107 pushes an upper surface of the latch 105 near the latch pawl 106 to pivot the latch 105. Thereby the latch 105 is inserted and engaged to an opening 103 of the tongue plate 102.
As described above, a series of locking and releasing operations comprise movements relating to a plurality of moving elements. Therefore, this requires precise manufacturing of the moving elements. In addition, this requires precise manufacturing of a base plate where each member is assembled. Furthermore, this increases the manufacturing cost of each member.