Buckle Device

Abstract: A buckle device (10) for use in a vehicle seat belt system having a tongue plate (12) and a buckle body (17) into which the tongue plate (12) is inserted for engagement therewith includes a lock member (22) which is swung to engage the inserted tongue plate (12) and is adapted to lock the tongue plate (12), a release button (28) moved by the operation of a vehicle occupant to swing the lock member (22) in an opposite direction, thereby cancelling engagement between the lock member (22) and the tongue plate (12), and an emergency lock mechanism for holding the lock member (22) in a state of engagement with the tongue plate (12) when an inertial force acts in an operating direction of the release button (28). Accordingly, the disengagement between the tongue plate (12) and the lock member (22) due to the inertial force is prevented, and the state of engagement between the two members is maintained.

Description: The present invention relates to a buckle device for use in a vehicle seat belt system according to the preamble of claim 1. Among buckle devices used in seat belt systems, a buckle device having a so-called direct locking mechanism is known in which a lock member is held in a locked state by a release button disposed slidably in the direction of insertion and withdrawal of the tongue plate. The locked state of the tongue plate is released by operating the release button by pressing the same. With this buckle device, however, when inertial force has acts in the direction in which the release button is operated, there is a possibility that the release button moves due to this inertial force, thereby releasing the locked state of the tongue plate. That is, there are two cases where the inertial force acts in the direction in which the release button is operated: (1) those attributable to vehicle vibrations when running on a rough road and (2) those in which a support member for supporting the buckle device on the chassis absorbes energy caused by plastic deformation. In the latter case, the support member undergoes plastic deformation due to a large load acting on the support member, with the result that the overall buckle device moves suddenly in the direction in which the tongue plate is pulled, and the release button moves in the direction in which it is operated for release, by the inertia of the release button. Specifically in cases where the support member is constituted by material such as a webbing and is secured by being wound around an anchor provided on the chassis, and a portion of the webbing adjacent to the wound portion has been sewn in a folded state, the sewn portion is adapted to be cut off so as to absorb the energy when a large load occurs. In this case, there is a possibility that when the webbing is drawn out suddenly due to the cutting off of the sewn portion upon absorbing the energy, the release button moves in the direction in which it is operated for release, owing to the inertial force. In addition, among buckle devices used in seat belt systems, one having a so called indirect locking mechanism is known in which the lock member is held in a locking state by means of a lock assisting member such as a pin. When the release button is operated by being pressed, this lock assisting member is adapted to move so as to release the locked state of the tongue plate. With this type of buckle device as well, an inertial force acts in the direction in which the release button is operated, so that when the release button moves due to this inertial force, there is a possibility that the locked state of the tongue plate is released. EP-A-212 507 discloses a buckle device with an emergency lock means according to the preamble of the main claim. This buckle device shows an element acting due to an inertial force and preventing the release of the tongue plate inopportunely. The earlier filed EP-A-384 703 and EP-A-368 277 also disclose buckle devices with emergency lock means. These applications are comprised in the state of the art according to Article 54(3) and (4)EPC. Accordingly, an object of the present invention is to provide a buckle device which makes it possible to maintain the locked state of a tongue plate even when an inertial force acts in a lock releasing direction of a lock releasing means, thereby overcoming the above-described drawbacks of the conventional art. To this end, in accordance with the present invention, the buckle device shows the features of the characterizing part of claim 1. In accordance with another aspect of the present invention, the buckle device includes releasing force transmitting means allowing the lock member and the releasing means to interlock with each other. In accordance with still another aspect of the present invention, the buckle device includes a lock assisting means disposed movably between a locking position for holding the lock member in a state in which it is engaged with the tongue plate and a releasing position in which the lock member can be disengaged from the tongue plate. In accordance with the first aspect of the present invention, in the event that an inertial force has acted in a predetermined direction in a state in which the lock member is holding the tongue plate in the locked state, the additional locking device holds the lock member in a state of engagement with the tongue plate by preventing the lock member from moving from the locking position to its unlocked position. Accordingly, it is possible to maintain the locked state of the tongue plate even when an inertial force has acted on the releasing means in a predetermined direction. Meanwhile, when the occupant operates the releasing means in a predetermined direction, the locking state of the lock member is released, so that the tongue plate can be removed. It suffices if the additional locking device is adapted to maintain the locked state of the tongue plate when an inertial force has acted in a predetermined direction, so that the additional locking device may be disposed in any part of the buckle device. Meanwhile, when the occupant operates the releasing means in a predetermined direction, the locking state of the lock member is released via the releasing force transmitting means, so that the tongue plate can be removed. Meanwhile, when the occupant operates the releasing means in a predetermined direction, the locking state of the lock member is released as the lock assisting means moves to the releasing position, so that the tongue plate can be removed. The above and other objects, features and advantages of the present invention will become more apparent from the subclaims and the following detailed description of the invention when read in conjunction with the accompanying drawings. Fig. 1 is a cross-sectional view schematically illustrating a state in which a tongue plate of a buckle device in accordance with a first embodiment of the present invention is drawn out; Fig. 2 is a cross-sectional view schematically illustrating a state of engagement of a tongue plate of a buckle device in accordance with the first embodiment of the present invention; Fig. 3 is an exploded perspective view of the buckle device in accordance with the first embodiment of the present invention; Fig. 4 is a cross-sectional view schematically illustrating a state of engagement of a tongue plate of a buckle device in accordance with a second embodiment of the present invention; Fig. 5 is an exploded perspective view of the buckle device in accordance with the second embodiment of the present invention; Fig. 6 is a cross-sectional view schematically illustrating a state of engagement of a tongue plate of a buckle device in accordance with a third embodiment of the present invention; Fig. 7 is a cross-sectional view schematically illustrating a state in which the tongue plate of the buckle device in accordance with the third embodiment of the present invention is drawn out; Fig. 8 is an exploded perspective view of the buckle device in accordance with the third embodiment of the present invention; Fig. 9 is a cross-sectional view schematically illustrating a state when acceleration has acted on the buckle device in accordance with the third embodiment of the present invention; Fig. 10 is a cross-sectional view schematically illustrating a state of engagement of the tongue plate of the buckle device in another example of the third embodiment of the present invention; Fig. 11 is a cross-sectional view schematically illustrating a state when acceleration has acted on the buckle device in the other example of the third embodiment of the present invention; Fig. 12 is an exploded perspective view of the buckle device in the other example of the third embodiment of the present invention; Fig. 13 is an exploded perspective view illustrating a tongue plate engaging portion of the buckle device in still another example of the third embodiment of the present invention; Fig. 14 is a cross-sectional view taken along the line 24 - 24 of Fig. 13; Fig. 15 is an exploded perspective view illustrating a tongue plate engaging portion of the buckle device in a further example of the third embodiment of the present invention; and Fig. 16 is a cross-sectional view taken along the line 26 - 26 of Fig. 15. Referring to Figs. 1 to 3, a description will be given of a first embodiment of the present invention. As shown in Fig. 1, a buckle device 110 has a buckle body 118 interposed between an upper cover 114 and a lower cover 116. In this buckle body 118, as shown in Fig. 3, a pair of leg plate portions 124 are formed integrally on transversely opposite sides of a flat plate portion 122 by bending. The arrangement is such that a tongue plate 112 is inserted between the pair of leg plate portions 124 through an opening 125 formed between the upper cover 114 and the lower cover 116. As shown in Fig. 1, an ejector 126 and a lock plate 128 which is a lock member are provided between the pair of leg plate portions 124 of the buckle body 118. The ejector 126 is inserted and disposed in a guide hole 130 formed in the flat plate portion 122 of the buckle body 118, and is movable in the direction of insertion and withdrawal of the tongue plate (in the direction of arrow A or B in Figs. 1 and 2). One end of a coil spring 132 (shown in Fig. 3) is fitted to a right-hand end, as viewed in the ejector 126, in the direction where the tongue plate 112 is inserted, while the other end is retained by the buckle body 118. The ejector 126 is thus urged in the direction of withdrawal of the tongue plate 112 (in the direction of arrow B in Figs. 1 and 2) by the force of this coil spring 132. At the time of the insertion of the tongue plate 112, the distal end of the tongue plate 112 is brought into contact with the ejector 126. Thus, the tongue plate 112 is inserted as shown in Fig. 2, while moving the ejector 126 in the tongue plate inserting direction (in the direction of arrow A in Fig. 1) from the state of withdrawal of the tongue plate shown in Fig. 1. The lock plate 128 is elongated in the direction of insertion and withdrawal of the tongue plate (in the direction of arrow A or B in Figs. 1 and 2). A U-shaped portion 134 whose end is bent substantially perpendicularly downward is formed at a left end, as viewed in Figs. 1 and 2, of the lock plate 128. A distal end portion of this U-shaped portion 134 is formed as an engaging portion 138 for engaging with an engaging hole 136 of the tongue plate 112. This engaging portion 138 is fitted in the engaging hole 136 of the tongue plate 112, as shown in Fig. 2, thereby engaging the lock plate 128 with the tongue plate 112. An upwardly rising portion 140 is formed at the other end (the right side in Figs. 1 and 2) of the lock plate 128 located away from its U-shaped portion 134. As shown in Fig. 3, the rising portion 140 is elongated in the transverse direction of the lock plate, and the lock plate 128 is trained between the pair of leg plate portions 124 of the buckle body 118 with its transversely opposite ends of the rising portion 140 supported by the leg plate portions 124. A substantially triangular notch 142 is formed in a right end, as viewed in Figs. 1 and 2, of each of the leg plate portions 124. Transversely opposite ends of the rising portion 140 are inserted into the notches 142, thereby rendering the lock plate 128 swingable in the direction of disengagement from the tongue plate (in the direction of arrow C or D in Figs. 1 and 2) with each bottom 142A as a center. In addition, the bottom 142A of each of the notches 142 is wider than the thickness of the rising portion 140 of the lock plate 128, so that the lock plate 128 is adapted to move by a small amount in the direction of arrow A or B in Fig. 1. With the tongue plate withdrawn, the lock plate 128 is set in a state in which it is swung in the direction of disengagement from the tongue plate (in the direction of arrow C in Fig. 1) as the end of the engaging portion 138 is brought into contact with an upper surface of the ejector 126, as shown in Fig. 1. As shown in Fig. 3, the lock plate 128 has a pair of downwardly bent portions 144 formed on transversely opposite sides thereof at a longitudinally intermediate position between the U-shaped portion 134 and the rising portion 140. When the bent portions 144, in the tongue plate-withdrawn state shown in Fig. 1, are pressed in the tongue plate inserting direction (in the direction of arrow A in Fig. 1), the lock plate 128 is swung in the direction of engagement with the tongue plate (in the direction of arrow D in Fig. 1). These bent portions 144 correspond to right ends, as viewed in Figs. 1 and 2, of a block 146 which is integrally provided on an upper surface of the ejector 126. The arrangement is such that when the tongue plate 112 in the tongue plate-withdrawn state shown in Fig. 1 is inserted, the ejector 126 presses the bent portions 144 in the tongue plate inserting direction (in the direction of arrow A in Fig. 1), and is moved in the tongue plate inserting direction, as shown in Fig. 2, while swinging the lock plate 128 in the direction of engagement with the tongue plate (in the direction of arrow D in Fig. 1). The lock plate 128 is engaged with the tongue plate 112 as the tip of the engaging portion 138 is inserted in the engaging hole 136 of the tongue plate 112, as shown in Fig. 2, due to its swinging motion at that time. A spring holder 148 retained by the rising portion 140 is fixed to the lock plate 128. One ends of two coil springs 150, 152 (shown in Fig. 3) are retained by the spring holder 148. The other ends of these two coil springs 150, 152 are respectively disposed more towards the tongue plate 112, as viewed in Figs. 1 and 2, than the spring holder 148, and are retained by a release button 154 which is a releasing means and a lock pin holder 156. Thus, the release button 154 and the lock pin holder 156 are respectively urged in the tongue plate withdrawing direction (in the direction of arrow B in Figs. 1 and 2) by means of the coil springs 150, 152. The release button 154 is disposed more towards the tongue plate 112, as viewed in Figs. 1 and 2, than the lock pin holder 156, and are movable in the direction of insertion and withdrawal of the tongue plate (in the direction of arrow A or B in Figs. 1 and 2). In addition, the release button 154 is movable in the tongue plate inserting direction (in the direction of arrow A in Figs. 1 and 2) against the urging force of the coil spring 150 (shown in Fig. 3). A pair of blocks 158 are provided at a right-hand end, as viewed in Figs. 1 and 2, of the release button 154 in such a manner as to project in the tongue plate inserting direction (in the direction of arrow A in Figs. 1 and 2). The blocks 158 are inserted into rectangular holes 160 (shown in Fig. 3) provided in an upper end portion of the lock pin holder 156 in such a manner as to be axially movable, and correspond to an upper end of the rising portion 140 of the lock plate 128. These blocks 158 are arranged such that when the release button 154 in the state of engagement with the tongue plate is moved in the tongue plate inserting direction (in the direction of arrow A in Fig. 2) against the urging force of the coil spring 150 (shown in Fig. 3), the blocks 158 are brought into contact with the upper end of the rising portion 140 of the lock plate 128 midway during their movement, and press the rising portion 140 of the lock plate 128, thereby moving the lock plate 128 in the tongue plate inserting direction while swinging the same in the direction of disengagement with the tongue plate (in the direction of arrow C in Fig. 2). Due to this swinging, the lock plate 128 is adapted to cause the engaging portion 138 to be withdrawn from the engaging hole 136 of the tongue plate 112 from the state of its engagement with the tongue plate shown in Fig. 2. The lock pin holder 156, which is urged by the coil spring 152 (shown in Fig. 3), is adapted to clamp a lock pin 162 (serving as a lock assisting means) between the same and the release button 154, as shown in Fig. 2, on the outer sides of the leg plate portions 124 of the buckle body 118 in the state of engagement of the tongue plate. The lock pin 162 is supported by the buckle body 118 with its axially opposite ends inserted in bearing holes 164 respectively provided in the leg plate portions 124 of the buckle body 118. The bearing holes 164 are elongated in the direction of insertion and withdrawal of the tongue plate (in the direction of arrow A or B in Figs. 1 and 2) so as to support the lock pin 162 movably in the direction of insertion and release of the tongue plate. The lock pin 162 corresponds to a pair of positioning plate portions 166 provided in the lock plate 128. As shown in Fig. 3, the positioning plate portions 166 extend in the transverse direction of the lock plate from its intermediate portion substantially orthogonal to the engaging portion 138 of the U-shaped portion 134. In the state of engagement of the tongue plate, the lock pin 162 abuts against the upper surfaces of the positioning plate portions 166, as shown in Fig. 2. In the state in which the tongue plate is withdrawn, the lock pin 162 abuts against the right end faces, as viewed in Figs. 1 and 2, of the positioning plate portions 166, as shown in Fig. 2. More specifically, the lock pin in the state of engagement of the tongue plate is clamped by the lock pin holder 156 and the release button 154 and corresponds to the upper surfaces of the positioning plate portions 166. In the state in which the lock pin 162 corresponds to the upper surfaces of the positioning plate portions 166 (in the locking position), the lock plate 128 is prevented from swinging in the direction of disengagement from the tongue plate (in the direction of arrow C in Fig. 2) by means of the lock pin 162. When the lock pin 162 in this tongue plate engaging state is moved in the tongue plate inserting direction (in the direction of arrow A in Fig. 2) and is hence positioned more towards the tongue plate inserting direction as viewed in Figs. 1 and 2, (i.e., the released position) than the right end faces, as viewed in Figs. 1 and 2, of the positioning plate portions 166, the lock plate 128 becomes swingable in the direction of disengagement from the tongue plate (in the direction of arrow C in Fig. 2). In addition, a protrusion 168 serving as an engagement assisting means is provided projectingly on a bottom 116A of the lower cover 116. A distal end portion of this protrusion 168 is bent orthogonally in the direction of withdrawal of the tongue plate 112 (in the direction of arrow B) so as to constitute a retaining claw 168A which is an additional locking device. Meanwhile, a retaining hole 170 is provided in a distal end portion of the engaging portion 138 of the lock plate 128. In the event that the lock plate 128 moves in the direction of arrow A by means of an inertial force or the like, the retaining claw 168A of the protrusion 168 of the lower cover 116 fits into and engages with the retaining hole 170. A description will now be given of the operation of this embodiment. Fig. 1 illustrates a state in which the tongue plate 112 is not engaged with the buckle device 110. If the tongue plate 112 is inserted in the buckle device 110 in this state, the tip of the tongue plate 112 is brought into contact with the ejector 126 and presses the ejector 126 in the tongue plate inserting direction (in the direction of arrow A in Fig. 1) against the urging force of the coil spring 132. The tongue plate 112 is thus moved in the tongue plate inserting direction while the ejector 126 is being moved in the tongue plate inserting direction (in the direction of arrow A in Fig. 1). During its movement, the ejector 126 is brought into contact with the bent portions 144 of the lock plate 128 and press the bent portions 144 of the lock plate 128 in the tongue plate inserting direction (in the direction of arrow A in Fig. 1). The ejector 126 is moved in the tongue plate inserting direction (in the direction of arrow A in Fig. 1) while swinging the lock plate 128 in the tongue plate engaging direction (in the direction of arrow D in Fig. 1). While the tongue plate 112 is being moved in the tongue plate inserting direction, the engaging portion 138 of the lock plate 128 is inserted into the engaging hole 136. At this juncture, the lock pin 162 is movable in the tongue plate withdrawing direction (in the direction of arrow B in Fig. 1) by the swinging of the lock plate 128. The lock pin 162 moves in the tongue plate withdrawing direction through the urging of the coil spring 152 via the lock pin holder 156. For this reason, in the state in which the engaging portion of the lock plate 128 is fitted in the engaging hole 136 of the tongue plate 112, the lock pin is clamped by the lock pin holder 156 and the release button 154, and corresponds to the upper surfaces of the positioning plate portions 166 (locked position). This state is the tongue plate engaged position shown in Fig. 2. Accordingly, in the tongue plate engaging state shown in Fig. 2, the lock plate 128 is prevented from swinging in the tongue plate disengaging direction (in the direction of arrow C in Fig. 2) by means of the lock pin 162, and the engaging portion 138 of the lock plate 128 is prevented from coming out of the engaging hole 136 of the tongue plate 112, so that the tongue plate 112 is not inadvertently removed from the buckle device 110. In addition, when the inertial force acts in the direction of arrow A in the tongue plate engaging state shown in Fig. 2, the lock pin 162 moves in the direction of arrow A (in the direction of the releasing position) against the urging force of the coil spring 152. In this case, since the lock plate 128 also moves in the direction of arrow A by means of the inertial force, the retaining claw 168A of the protrusion 168 provided uprightly on the lower cover 116 fits in and engages with the retaining hole 170 provided in the engaging portion 138 of the lock plate 128. For this reason, the lock plate 128 is held in the tongue plate engaging state, and the state of engagement between the lock plate 128 and the tongue plate 112 is not released by the inertial force. Meanwhile, the arrangement provided is such that the lock plate 128 is impossible to move in the direction of arrow B, C, or D, nor can it move in the axial direction thereof. Accordingly, with the buckle device of this embodiment, no matter from which direction the inertial force comes, the lock plate 128 is held in the tongue plate engaging state. When the tongue plate 112 is to be released from the buckle device 110, the release button 154 is moved by the occupant in the tongue plate inserting direction (in the direction of arrow A in Fig. 2) against the urging force of the coil spring 150. With the lock pin 162 clamped by the release button 154 and the lock pin holder 156, the release button 154 is moved in the tongue plate inserting direction while moving the lock pin 162 and the lock pin holder 156 in the tongue plate inserting direction (in the direction of arrow A in Fig. 2) against the urging force of the coil spring 152 (shown in Fig. 3). After the lock pin 162 is situated more towards the tongue inserting direction, as viewed in Fig. 2, than the positioning plate portions 166 of the lock plate 128 due to the aforementioned movement, the block 158 of the release button 154 is brought into contact with the upper end portion of the rising portion 140 of the lock plate 128. As a result, the release button 154 presses the rising portion 140 of the lock plate 128 in the tongue plate inserting direction, and is further moved in the tongue plate inserting direction while swinging the lock plate 128 in the tongue plate releasing direction (in the direction of arrow C in Fig. 2). The engaging portion 138 of the lock plate 128 disengages from the engaging hole 136 of the tongue plate 112 owing to the swinging motion at that time. At the same time, the ejector 126 is urged by the coil spring 132 and moved in the tongue plate withdrawing direction (in the direction of arrow B in Fig. 2), and the tongue plate 112 springs out of the buckle device 110 by being pressed by the ejector 126, thereby returning to the state shown in Fig. 2. Referring now to Figs. 4 and 5, a description will be given of a second embodiment of the present invention. Members that are identical with those of the first embodiment will be denoted by the same reference numerals, and a description thereof will be omitted. As shown in Figs. 4 and 5, a pair of retaining projections 172 serving as one part of an emergency lock means are formed between the U-shaped portion 134 and the bent portions 144 of the lock plate 128, respectively. A pair of retaining projections 174 serving as another part of the emergency lock means are respectively formed on the inner sides of the leg plate portions 124 of the buckle device 118 corresponding to the retaining projections 172 at positions located on the right side, as viewed in Fig. 4, of the leg plate portions 124. The arrangement is such that when the lock plate 128 moves in the direction of arrow A by an inertial force or the like, the retaining projections 172 of the lock plate 128 move and are caught at the left sides, as viewed in Fig. 4, of the retaining projections 174 of the buckle body 118, thereby holding the lock plate 128 in the tongue plate engaging state. Accordingly, in this second embodiment as well, it is possible to obtain the same effect as in the first embodiment. Referring now to Figs. 6 to 8, a description will be given of a third embodiment of the present invention. As shown in Fig. 8, main component parts of a buckle device 220 are accommodated in a buckle body 222. The buckle body 222 is formed by processing a plate material having a predetermined strength. A connecting portion 226 is formed at one end thereof. An opening 228 is formed in the connecting portion 226, and one end of a strap 232 (see Figs. 6 and 7) is connected to this opening 228 via a protector 230. The other end of the strap 232 is secured to the chassis via an anchor plate or the like. In the buckle body 222, an opening 236 is formed in a base plate portion 234 serving as a base bottom for connection with the connecting portion 226. Also, in the buckle body 222, a pair of substantially rectangular notches 242 are formed in upper intermediate portions of a pair of leg plate portions 240 provided uprightly from transversely opposite sides of the base plate portion 234 and are in parallel with each other. In addition, a pair of guide flanges 244 projecting outwardly from the leg plate portions 240 are formed on front sides, i.e., left sides as viewed in Fig. 6, of the leg plate portions 240 adjacent to the aforementioned notches 242. A pair of projections 245 for positioning a tongue plate 296 (see Fig. 6) by restricting its upward movement are formed below the guide flanges by being stamped out inwardly of the leg plate portions 240. Furthermore, notches 246 are formed on front sides, i.e., right sides as viewed in Fig. 6, of the leg plate portions 240. Formed in a lock plate 248 is a hook 252 bent downwardly at a central portion of a front end of a central flat plate portion 250 as well as a hinge 254 bent downwardly at a rear end of the central flat plate portion 250. A pair of projections 256 are formed at a forward position of the central flat plate portion 250 in such a manner as to project outwardly from transversely opposite sides of the central flat plate portion 250. A slot 250A extending longitudinally and reaching the hinge 254 is formed in a central portion of the central flat plate portion 250. This slot 250A is formed into a tapered configuration having a diminished width at the hinge 254 side. A pair of notches 260 are formed on opposite sides of an intermediate portion of the hinge 254. The side surface of the hook 252 is formed into an arcuate configuration with the notches 260 as the center, as shown in Fig. 6. In addition, a projection 238 is formed at a distal end of the hinge 254 in such a manner as to project toward the hook 252. As for the lock plate 248, the hinge 254 is inserted into the opening 228 formed in the connecting portion 226, and the notches 260 formed in the hinge 254 are retained by the connecting portion 226, thereby rendering the lock plate 248 swingable with respect to the buckle body 222. The aforementioned protector 230 is fitted in the opening 228 after the lock plate 248 is inserted, as described above, and also functions as a stopper for preventing the lock plate 248 from coming out. In addition, a rear surface of the lock plate 248 on the front side thereof, including the projections 256, is capable of abutting against bottom surfaces 242A of the notches 242, 242 formed in the buckle body leg plate portions 240. With the lock plate 248 abutting against the bottom surfaces 242A, the end of the hook 252 is situated in the opening 236 formed in the buckle body base plate portion 234. One end of a compression coil spring 276 having the other end supported by an ejector 270 is retained to the projection 238 of the lock plate 248. The lock plate 248 is urged by the compression coil spring 276 and counterclockwise torque, as viewed in Fig. 6, (in the direction of arrow D) is imparted to the lock plate 248 with the notches 260 formed in the hinge 254 serving as a fulcrum. In addition, a pair of projections 257 serving as a part of an emergency lock means is formed rearwardly of the projections 256 of the central flat plate portion 250 in parallel with the projections 256. Front end portions of these projections 257 are bent downwardly, and are then further bent forwardly, thereby forming L-shaped hooks 257A. An upper portion of the ejector 270 is formed into a flat rectangular shape having a width greater than the width of the opening 236 formed in the flat plate portion of the buckle body 222. A guide portion 272 fitting slidably into the opening 236 is formed in a lower rear portion of the ejector 270. A spring support 274 is formed projectingly at the rear of the ejector 270. A compression coil spring 276 is disposed between the spring support 274 and the projection 238 of the hinge 254 of the lock plate 248 so as to urge the ejector 270 leftwards as viewed in Fig. 6 (in the direction of arrow B in Fig. 6). In addition, a pair of hooks 273 serving as another part of the emergency lock means are formed at transversely opposite ends of the ejector 270 in such a manner as to project upward. Distal ends 273A of the hooks 273 are bent rearwardly, and when the ejector 270 moves rightward as viewed in Fig. 6 (in the direction of arrow A in Fig. 6), the distal ends 273A engage the hooks 257A of the lock plate 248 (the state shown in Fig. 9). A holder 262 is retained by the buckle body 222 with its notches 266 fitted to the notches 246 formed in the buckle body leg plate portions 240. As shown in Fig. 6, a release button 278 has a pair of wedge-shaped inclined guide portions 282 (only one is shown in the drawing) formed at the inner side of an operating portion 280. These inclined guide portions 282 are brought into contact with a rear surface of the lock plate 248. The release button 278 is movable in the direction of arrow A in Fig. 6 by being guided by the guide flanges 244 with rail grooves (not illustrated) fitted to the guide flanges 244 formed in the buckle body leg plate portions 240. A spring support 285 is formed on the release button 278, and a compression coil spring 288 is interposed between the support 285 and a spring support 286 formed on the holder 262. As a result, the release button 278 is urged in the direction of arrow B in Fig. 6. A pair of holding arms 289 (serving as lock assisting means) with their ends bent into the configuration of hooks are formed on opposite sides of the release button 278, and these holding arms 289 are positioned in such a manner as to clamp the buckle body leg plate portions 240 from opposite sides thereof. A buckle cover 290 is composed of an upper cover 292 and a lower cover 294, and is secured to the buckle body 222, covering the base plate portion 234 and leg plate portions 240. As shown in Fig. 6, the tongue plate 296 has a rectangular opening 298 formed on end tip side, and the horizontal length, as viewed in Fig. 6, of this opening 298 is set to be longer than the thickness of the hook 252, so that the tongue plate 296 is movable in the direction of arrow A or B in Fig. 6. In addition, one end of an unillustrated webbing is attached to the rear end side (left side in Fig. 6) of the tongue plate 296. The other end of the webbing is secured to the chassis via an anchor plate or the like. The operation of this embodiment will be described hereinunder. Fig. 7 illustrates a state before the tongue plate 296 is engaged with the buckle device 220. In this state, the ejector 270 is situated at its forward limit by being urged by the compression coil spring 276. Its guide portion 272 abuts against an end face of the opening 236 formed in the buckle body base plate portion 234. The hook 252 of the lock plate 248 abuts against the upper surface of the ejector 270. The lock plate 248 is urged by the compression coil spring 276 and the counterclockwise torque in Fig. 17 (in the direction of arrow D in Fig. 7) is hence imparted to the lock plate 248, so that the hook 252 presses the upper surface of the ejector 270. Although the release button 278 is urged in the direction of arrow B in Fig. 1 by means of the compression coil spring 288, the tips of the holding arms 289 are retained by the projections 256 of the lock plate 248, so that the release button 278 has not reached its forward limit. In this state, if the tongue plate 296 is inserted from the left side, as viewed in the drawing, between the base plate portion 234 and the projections 245 of the buckle device 220, the end of the tongue plate 296 presses the ejector 270 in the direction of arrow A in Fig. 7. When the ejector 270 is moved in the direction of arrow A in Fig. 7 against the urging force of the compression coil spring 276, the end of the tongue plate 296 is situated below the distal end of the hook 252. When the tongue plate 296 is further pressed in the direction of arrow A in Fig. 7, the distal end of the hook 252 of the lock plate 248 is situated above the opening 298 of the tongue plate 296, so that the distal end of the hook 252 is instantly rotated and enters the opening 298 since the lock plate 248 is urged in the direction of arrow D in Fig. 7. The lock plate 248 rotates, and the distal end of the hook 252 passes through the opening 298 of the tongue plate 296 and is situated in the opening 236 formed in the buckle base plate portion 234. The lock plate 248 stops rotating as the front-side rear surface thereof, including the projections 256, is brought into contact with the bottom surfaces 242A formed in the buckle body leg plate portions 240. When the lock plate 248 rotates, the release button 278 is urged by the compression coil spring 288 and reaches its leftward forward limit since the holding arms 289 are disengaged from the projections 256 of the lock plate 248. In the state shown in Fig. 6, the tongue plate 296 is pressed by the ejector 270 which is urged by the compression coil spring 276, so that no rattling occurs between the tongue plate 296 and the lock plate 248. In addition, when the occupant presses the operating portion 280 to move the release button 278 in the direction of arrow A in Fig. 6 against the urging force of the compression coil spring 288, the inclined guide portions 282 of the release button 278 are pressed against the lock plate 248. The distal ends of the holding arms 289 move from the upper surfaces of the projections 256 of the lock plate 248 due to the movement of the release button 278, and the lock plate 248 concurrently moves upwardly along the inclined guide portions 282. As a result, the lock plate 248 swings in the direction of arrow C in Fig. 6 by using as an axis the portion of the hinge 254 contacting the buckle body 222. At the same time as the lock plate 248 swings and the end of the hook 252 is released from the opening 298 of the tongue plate 296, the ejector 270 instantly moves in the direction of arrow B in Fig. 6 by being urged by the compression coil spring 276, thereby ejecting the tongue plate 296 outside the buckle device 220. When the lock plate 248 is disengaged from the tongue plate 296 and the release button 278 is released, the release button 278 moves in the direction of arrow B in Fig. 6 by being urged by the compression coil spring 288. Meanwhile, in the state in which the tongue plate 296 is engaged, as shown in Fig. 6, in the event that sudden acceleration acts in the direction of arrow A in Fig. 6, the ejector 270 moves integrally with the tongue plate 296 in the direction of arrow A in Fig. 6, so that the distal ends 273A of the hooks 273, 273 engage the hooks 257A of the lock plate 248 (the state shown in Fig. 9). Consequently, the lock plate 248 is prevented from swinging in the direction of arrow C in Fig. 6 by using as an axis the portion of the hinge 254 contacting the buckle body 222. Accordingly, when sudden acceleration acts in the direction of arrow A in Fig. 6, it is possible to maintain the locked state of the tongue plate 296. In addition, this embodiment is superior to the first to sixth embodiments in that the arrangement for holding the locked state of the tongue plate 296 when sudden acceleration occurs is simple to make, so that productivity is better. It should be noted that in the above-described embodiment the arrangement provided is such that the hooks 273 are formed on transversely opposite ends of the ejector 270 in such a manner as to project upward. When the ejector 270 moves rightwards as viewed in Fig. 6 (in the direction of arrow A in Fig. 6), the distal ends 273A of the hooks 273 engage the hooks 257A formed in the rear portions of the projections 256 of the central flat plate portion 250 of the lock plate 248 (the state shown in Fig. 9). Alternatively, it is possible to provide an arrangement in which, as shown in Figs. 10 - 12, the distal end of the hinge 254 is bent toward the hook 252 side so as to form a hook 254A which also serves as a spring support for supporting one end of a compression coil spring 277. A distal end 275A of a hook 275 also serves as a support for the other end of the compression coil spring 277 and engages the hook 254A (the state shown in Fig. 11) when acceleration is effected. In this case, the structure of the ejector 270 and the lock plate 248 are further simplified. It should be noted that although the ejector 270 engages the lock plate 248 in the arrangement provided in the foregoing embodiment, an arrangement may be alternatively provided such that, as shown in Figs. 13 and 14, a projection 298A is formed on the rear end side, i.e., the left side in Fig. 14, of the opening 298 of the tongue plate 296, and when sudden acceleration acts in the rightward direction as viewed in Fig. 14 (in the direction of arrow A in Fig. 14), this projection 298A is made to engage an elongated hole 252A provided in the hook 252 of the lock plate 248. In addition, as shown in Figs. 15 and 16, the width (L2) of a rear end side 298B of the opening 298 of the tongue plate 296 is formed to be smaller than the width (L4) of a front end side 298C of the opening, and a large-width portion 252B is provided at a lower end of the hook 252 of the lock plate 248. Furthermore, the relationship between the width (L3) of this large-width portion 252B and the width (L1) of an upper portion of the hook 252 is set to be L1 < L2 < L3 < L4, whereby when sudden acceleration acts in the rightward direction as viewed in Fig. 15 (in the direction of arrow A in Fig. 15), the tongue plate 296 moves in the direction of arrow A and assumes a position indicated by the two-dotted dash line. The large-width portion 252B of the lock plate 248 engages the rear end side 298B of the opening 298 of the tongue plate 296. In this case, it is possible to increase the strength of the lock plate 248. By virtue of the above-described arrangements, the present invention offers an outstanding advantage in that it is possible to maintain the locked state of the tongue plate even when an inertial force acts on the lock canceling means in the lock canceling direction.

Claims: A buckle device (110,220) for use in a seat belt system, comprising: a buckle body (118,222); a tongue plate (112,296) insertable into said buckle body (118,222); a swingable lock member (128,248) supported by said buckle body (118,222), engaging said insertable tongue plate (112,296) for locking; releasing means (154,278) supported by said buckle body (118,222) being movable in a predetermined direction and adapted to swing said lock member (128,248) from its locking position to its unlocked position; and a lock assisting means (162,289) holding said lock member (128,248) by moving along a direction of insertion of said tongue plate (112,296) into said buckle body (118,222); characterized in that an additional locking device (168A,170,257A,273,275A, 254A,252A,298A,252B,298B,172,174) is provided for locking said swingable lock member (128,248), said additional locking device is movable in the direction of insertion of said tongue plate (112,296) into said buckle body (118,222) or in the direction of release of the tongue plate (112,296) from the buckle body (118,222) due to an inertial force acting in one of these directions; and said additional locking device blocks the swingable lock member (128,248) when said initial force acts on said additional locking device so that the swingable lock member (128,248) holds its state of engagement in the tongue plate (112,296). A buckle device according to claim 1, wherein said releasing means (154,278) is movable in a direction substantially along the direction of insertion of said tongue plate (112,296) into said buckle body (118,222) and which is adapted to move said lock assisting means (162,289) from its holding position to a position in which said lock member (128,248) can swing from its locking position to its unlocked position; and said additional locking device prevents the swinging of said lock member (128, 248) from its locking position to its unlocked position when an inertial force acts substantially along said direction of insertion of said tongue plate (112,296) into said buckle body (118,222). A buckle device according to claim 1 or 2, wherein said lock member (128) is movable in said direction of insertion of said tongue plate into said buckle body (118), and wherein said additional locking device (174) is constituted by a swinging preventing portion which is disposed on said buckle body (118) or interposed between said buckle body (118) and said lock member (128) and engages said lock member (128) or causes said buckle body (118) to engage said lock member (128) moved in said direction of insertion of said tongue plate (112) into said buckle body (118) when said inertial force acts in said direction of insertion of said tongue plate (112) into said buckle body (118), thereby preventing the swinging of said lock member (128) from said first position to said second position. A buckle device according to claim 1 or 2, where said lock member (128) is movable in said direction of insertion of said tongue plate (112) into said buckle body, and wherein said additional locking device (172) is constituted by a projection which is provided on said lock member (128) and projects in a direction perpendicular to a plane of a path of the swinging of said lock member (128), and a swinging preventing member (174) which is disposed on said buckle body (118), corresponds to said projection (172) of said lock member (128) moved in said direction of insertion of said tongue plate into said buckle body (118) by said inertial force acting in said direction of insertion of said tongue plate (112) into said buckle body (118), and is adapted to prevent the swinging of said lock member (128) from said first position to said second position. A buckle device according to claim 1 or 2, further comprising an ejector (270) for pressing said tongue plate (296) inserted into said buckle body (222) by means of an urging force acting in an opposite direction to the inserting direction (A) of said tongue plate (296), said additional locking device (257A,273A) including a first projection (273,275) provided on said ejector (270) and a second projection (257A,254A) provided on said lock member (248), which engages said first projection (273) of said ejector (270) moved in said direction of insertion of said tongue plate (296) into said buckle body (222) when said inertial force acts in said direction of insertion of said tongue plate (296) into said buckle body (222), thereby preventing the swinging of said lock member (248) from said first position to said second position. A buckle device according to claim 1 or 2, wherein said tongue plate (296) is provided with an opening (298) into which a part (252) of said lock member (248) is inserted to effect engagement of said lock member (248) therewith, and wherein said additional locking device (252A,298A,252B,298B) is interposed between said opening (298) of said tongue plate (296) and said part (252) of said lock member (248), and said part (252) of said lock member (248) engages said tongue plate (296) moved in said direction of insertion of said tongue plate (296) into said buckle body (222) when said inertial force acts in said direction of insertion of said tongue plate (296) into said buckle body (222), thereby preventing the swinging of said lock member (248) form said first position to said second position. A buckle device according to claim 6, wherein said additional locking device (252A, 298A) includes a projection (298A) projecting form a peripheral portion of said opening (298) of said tongue plate (296) and a hole (252A) which is provided in said part (252) of said lock member (248) and into which said projection (298A) is inserted. A buckle device according to claim 6, wherein said additional locking device (252B, 298B) includes a small-diameter portion (298B) provided in said opening (298) of said tongue plate (296) and a large-width portion (252B) which is provided in said part (252) of said lock member (248) and engages with a peripheral portion of said small-diameter portion (298B).

Inventors: TANAKA KOHBUN C O K K TOKAI-RI, TANAKA, KOHBUN C/O K.K.TOKAI-RIKA-DENKI-SEISAKUSHO
Applicants: TOKAI RIKA CO LTD, KABUSHIKI KAISHA TOKAI-RIKA-DENKI-SEISAKUSHO
Application year: 1990
Main classification: B60R22
IPC codes: A44B11