Abstract:
A buckle device is provided, for use with a seatbelt system of a vehicle, into which a tongue plate is inserted for engagements with a lock member, and which has in addition to the lock member with which the tongue plate engages when it is inserted into the buckle device to a predetermined depth, and which is urged at all times in the direction of engagement with the tongue plate, an ejector for urging said tongue plate in the direction of withdrawal from said buckle device, and a preventing member for preventing the lock member from moving into the insertion path of the tongue plate until the tongue plate reaches the predetermined engagement position. 
     With such an arrangement, the tongue plate undergoes no frictional force deriving from the lock member, and unless the tongue plate is inserted to the predetermined depth where it can firmly engage with the lock member, the ejector drives the tongue plate back out of the buckle device, thereby assuring reliable engagement between the tongue plate and the lock member.

Description:
BACKGROUND OF INVENTION 
     1. Field of the Invention 
     The present invention relates to a buckle device for seatbelt systems of motor vehicles and so forth. 
     2. Description of the Related Art 
     In a buckle device, it is desirable that frictional force in the insertion/withdrawal path of the tongue plate be limited as far as possible during the period following the insertion of the tongue plate until a lock plate securely engages therewith. In one arrangement devised to meet the above-mentioned requirement, failure to fully insert the tongue plate into the place where it securely engages with the lock plate causes a spring-loaded ejector to push the tongue plate back out of the buckle device, whereby it is assured that tongue plate insertion and tongue plate&#39;s firm engagement with the lock plate are promoted. 
     However, it is noted that the lock plate is at all times urged in a direction towards the path of tongue plate insertion so that the lock plate may be readily and immediately engaged with the tongue plate when the tongue plate is inserted and reaches the engagement position. Due to the urging of the lock plate towards the tongue plate the tongue plate confronts a pushing force from the lock plate while the tongue plate is being inserted into the engagement position, with some frictional resistance being generated thereby. In some cases, to lessen the frictional resistance, certain measures are taken wherein the faces of the lock and tongue plates are processed so as to be smooth, and a large ejector spring is applied to provide the ejector with larger spring force, requiring greater force for tongue plate insertion. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is an object of the present invention to provide a buckle device arranged with the above-mentioned fact in view, wherein the lock plate is kept away from the locus of tongue plate insertion until the tongue plate reaches the point where it can firmly engage with the lock plate. 
     The buckle device according to the present invention comprises: a buckle body into which a tongue plate is inserted; a lock member swingably fit in said buckle body, drivable between a first position where the tongue plate engages and is locked with said lock member, upon insertion to a predetermined depth, and a second position where the engagement between the lock member and the tongue plate is released, the lock member being at all times urged by a 1st urging member, in a direction toward said first position; an ejector urging the tongue plate, which has been put into the buckle body, in the direction of withdrawal of the tongue plate; and a preventing member for preventing said lock member from moving into the locus of tongue plate insertion in opposition to the force which said lst urging member applies to said lock member, until the tongue plate reaches said predetermined depth. Therefore, in the buckle device according to the present invention, putting the tongue plate into the buckle body causes said plate to press an ejection spring, whereby the ejection spring serves via the preventing member to keep the lock plate away from the locus of tongue plate insertion until the tongue plate reaches said predetermined depth where it can engage with the lock plate. When the tongue plate reaches the predetermined depth, where the tongue plate is fully inserted, the retention of the lock plate which has thus far been maintained is terminated, whereby the lock plate is allowed to firmly engage with the tongue plate. With the arrangement referred to above, there is no contact allowed between the lock and tongue plates until the amount of tongue plate insertion reaches the predetermined depth, so as the tongue plate undergoes no frictional force from the lock plate during the act of insertion. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a cross-sectional view taken along the line 1--1 in FIG. 3 of a buckle device,the first embodiment of the present invention. 
     FIG. 2 is a working diagram of the buckle device in FIG. 1, showing how the tongue plate engages with the lock plate, following the insertion of the former; 
     FIG. 3 is an exploded view showing the major parts of the buckle device; 
     FIG. 4 is a cross-sectional view taken along the line 4--4 and which is presented in FIG. 1; 
     FIG. 5 is a perspective view showing the second embodiment of the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     As precisely illustrated in FIG. 3, the buckle device 10 of the preferred embodiment of the present invention has a buckle body 12 formed from a thin plate, wherein both sides of the buckle body are bent approximately at right angles, so as to provide respective leg portions 14 and 16. 
     Into the space between and defined by these leg portions, the tongue plate 18 is inserted in the direction specified by arrow A, and from said space, the tongue plate is pulled out in the direction of arrow B. An opening 12A is provided at one end of the buckle body 12, on the opposite from the side of tongue plate insertion, for use in fitting a strap 22 (see FIGS. 1 and 2) which is fixed to a car body. 
     The opening 12A is provided with a recess 12B in such a manner as to expand part of the opening for swingably fitting the lock plate therein. The lock plate 24, made from a thin plate, is formed by being bent into a channel-shape with a U-shaped cross-sectional profile. The bend portion at one end 24A of the lock plate has a pair of notches 26 formed at both widthwise sides of said plate. The lock plate is fit in place so as to be swingable around the pair of notches, the peripheries of these notches 26 being engaged with said recess 12B. As a consequence, the lock plate 24 is allowed to swing in two directions--one, (C-arrow direction) the direction of insertion of a lock pawl 28 protruding downward from the widthwise central portion of the end 24B of the lock plate opposite to the end having said pair of notches, into an opening 18A which is provided within the tongue plate for engagement with the lock plate pawl, and the other, (D-arrow direction) the direction of pulling the lock pawl out of the opening 18A. 
     The buckle body has an opening 12C formed at its central part. An ejector 32 has a pair of grooves 32A which is provided at each widthwise end, and the pair of grooves is slidably engaged to the both side edge portions of said opening 12C so that the ejector may be movable in both the tongue plate insertion and withdrawal directions (A- and B-arrow directions). A compression coil spring 34 is provided between the ejector 32 and the bend 24A of the lock plate, urging not only the ejector 32 in the tongue plate ejection direction (B-arrow direction) but also the lock plate in the direction (C-arrow direction) in which the lock pawl 28 may be inserted into the opening 18A formed within the tongue plate for engagement with said lock pawl. 
     Meanwhile, as illustrated in FIGS. 1 and 2, a buckle cover 38 is furnished to house the buckle body 12. A release knob 42 is arranged to lie across the leg portions 14 and 16 of the buckle body 12. As illustrated in FIG. 4, the release knob 42 is supported against the buckle body 12 and allowed to slide in a direction orthogonal to the paper surface of FIG. 4, with L-shaped extensions 14A and 16A of the buckle body&#39;s leg portions 14 and 16 fit into respective grooves 42A and 42B which are provided in the opposite ends of the release knob 42. 
     A compression coil spring 46 is provided between a spring seat 44 which is mounted on the respective leg portions 14 and 16 and the release knob 42, and is urging the release knob 42 in the tongue plate withdrawal direction (B-arrow direction). 
     The release knob 42 has a cam protrusion 48 formed as a counterpart to a lock plate end 24B, as illustrated in FIG. 2. An inclination 48A of the cam protrusion 48 comes into engagement with the lock plate end 24B when a driver or a passenger pushes the release knob 42 into the buckle cover 38, whereby the lock plate 24 is force-awayed in the direction (D-arrow direction) of releasing the engagement with the tongue plate. 
     The ejector 32 has a pair of brackets 52 formed protruding above the ejector surface, with a pin 54 set across these brackets and supported thereupon. A pair of arms 56 extend from the pin 56, and a pin 58 limiter means is fixed across the respective tips of the pair of arms 56. The pin 58 is situated inside the lock plate 24, with the axial ends of said pin received in respective guide slits 62 formed within the leg portions 14 and 16, so as to be movable in the directions of contacting and separating from the lock plate 24. 
     Arranging the ejector 32 over the path of the lock pawl 28 when the tongue plate 18 is outside the buckle body 12 as shown in FIG. 1, brings the pin 58 into proximity with the inner surface of the lock plate 24. Inserting the tongue plate 18 into place within the buckle body, and thereby moving the ejector 32 together with the tongue plate 18 in the A-arrow direction, raises the pin 58 along inside the guide slit 62 in the upward direction shown in FIG. 1, whereby the pin 58 holds the lock pawl 28 up, so as to prevent the lock pawl 28 from getting into the travel path of the tongue plate 18, even when the ejector 32 is pushed out of the travel path of the lock pawl 28. However, reaching the predetermined depth of insertion of the tongue plate 18, by driving it into a position where said plate is allowed to engage with the lock plate, releases the pin 58 from the state wherein it has thus far been held in contact with the lock plate 24, and brings the pin 58 into a position near the lower ends of each guide slit 62 as shown in FIG. 2, whereby the lock pawl 28 of the lock plate 24 is made ready to go into the opening 18A provided in the tongue plate for engagement with the lock pawl 28. 
     The bottom of each guide slit 62 has a recess 64 formed so as to substantially expand the width of the guide slits in a direction toward the tongue plate insert area of the buckle body (horizontally crosswise direction in FIGS. 1 and 2). Thus, as shown in FIGS. 2, the locking mechanism is so devised that the pin 58 once set in the recess 64 is prevented from coming out therefrom, so as to assure that the lock plate 24 is prevented from being pushed up by the ejector 32, whereas, if the driver or the passenger thrusts in the release knob 42 while the pin 58 is held in the recess 64, the inclination 48A of causes the pin 58 to be driven out of the recess 64, allowing the pin 58 to move up toward the upper end of the guide slit 62. 
     Further, an arm 42C projects from the release knob 42, as shown in FIG. 3, and as specified in FIG. 2, and as long as the tongue plate is kept locked, said are is maintained in proximity to the periphery 24D of an opening 24C provided in the lock plate 24. The result is that under the condition referred to above, the lock plate 24 is prevented from swinging in the lock release direction D-arrow direction) even when some acceleration force 15 applied (in the upward direction of FIG. 2). However, when the release knob 42 is thrusted in the A-arrow direction, the arm 42C moves into the space of the opening 24C, so that the lock plate 42 is rendered swingable. 
     Now, how this preferred embodiment works is described hereunder. With reference to FIG. 1, it is illustrated therein that when the tongue plate 18 is outside the buckle body 18, the ejector 32 is situated at the stroke end within the rectangular opening 12C because of the urging force from the compression coil spring, and the lock pawl 28 of the lock plate is driven upon the ejector, so that, even when the lock plate 24 is urged in the direction toward engagement with the tongue plate 18, the lock plate is prevented from going the path of the tongue plate. 
     When the driver or the passenger thrusts the tongue plate 18 into the buckle body 12 to put on the seatbelt, the ejector 32 with which the tongue plate 18 has been brought into contact in its cycle of insertion, moves together with the tongue plate 18 in the A-arrow direction, against the urging, force from the compression coil spring. As a consequence, an increase in the depth of tongue plate 18 insertion entails a state where the ejector fails to keep the lock pawl retained thereon. Precisely in this state where the lock plate 24 is held in a raised position by the pin 58 which has been driven up inside the guide slit 62 by the arm 56, the lock pawl is not allowed to enter the path of the tongue plate 18, and the tongue plate undergoes no friction force stemming from the lock pawl 28. 
     Therefore, suspension of insertion of the tongue plate 18 midway in its inward-stroke causes the ejector 32 to reliably, and assuredly drive back the tongue plate 18 out of the buckle body 12 by urging force, with no chance of the tongue plate being caught inside the buckle body at a any point in its inward-stroke. 
     Reaching the predetermined depth of insertion at which the tongue plate 18 is driven into the place where it can engage with the lock plate 24 coincides with attainment by the arm 56 of an approximately horizontal position as shown in FIG. 2, resulting in the lowering of the pin 58 to the bottom of the two guide slits 62, and finally said pin is held in the recess 64. As a result, the pin 58 is no longer allowed to engage with the lock plate 24 which is permitted to swing in the C-arrow direction owing to the urging force from the compression coil spring 34, so as to enable the lock pawl 28 to be inserted into the opening 18A which is provided in the tongue plate 18 for engagement therewith. 
     In the state thus attained, there is firm engagement between the tongue plate 18 and the lock plate 24, wherein the pair of notches 26, together serving as a swing axis for the lock plate 24 are located slightly closer to one side of the buckle body 12 (underside in FIG. 2) rather than at a point where the lock pawl 28 could get caught in the opening 18A in the tongue plate, so that even when the force acting to pull out the tongue plate grows large, the lock plate 24 is not allowed to swing in the direction of withdrawal of the lock pawl from the opening 18A; instead, the lock plate receives some turning torque in the counterclockwise direction in FIG. 2, whereby firm engagement between the tongue plate 18 and the lock plate 24 is assured. 
     To release the tongue plate 18 from engagement with the lock plate 24, the release knob 42 is pushed into the buckle cover 38. When the release knob 42 is thrust into the buckle cover, the inclined edge 48A of the cam protrusion 48 is caused to work, driving the pin 58 off the two recesses 64, so that the ejector 32 presses the tongue plate 18 in the withdrawal direction, as a result of the urging force from the compression coil spring 34, and the pin 58 causes the lock plate to swing 24 in the direction (D-arrow direction) of the disengagement from the tongue plate 18, so as to pull the lock pawl 28 out of the opening 18A, thus releasing the tongue plate from engagement with the lock plate 24. As a consequence of disengagement, the tongue plate 18 receives the urging force from the compression coil spring 34 through the ejector 32, and thus is driven out of the buckle device 10. 
     In the above-described embodiment of the present invention, the arm 56 and the pin 58 serve together to keep the ejector 32 and the lock plate 24 functioning in concert with each other until the tongue plate 18 reaches the predetermined depth of insertion where it can engage with the lock plate 24. However, an alternate embodiment may include such limiting means as cam means or the like interposed between the ejector can the lock plate 24 which perform a similar function to that of the arm 56 and the pin 58. 
     Illustrated in FIG. 5 is the pin 58 associated with the second preferred embodiment of the present invention. The pin 58 has a roller 72 provided at each axial end thereof for swingably supporting the pin, whereby, in the second embodiment, the friction resistance among the two roller 72, guide slit 62 and lock plate 24 is lessened. 
     Further, either embodiment may include a spring rendering a small pressing force to said arm 56 so as to swing it in the counterclockwise direction in FIG. 1, around a center comprised of the pin 54.