Abstract:
A safety belt buckle which permits release of a tongue by the application of minimal pressure on a tongue release member, even under conditions of great stress, yet having strength and reliability. When the tongue is inserted in the buckle it forces a tongue ejecting member back against a biasing force, and an outwardly biased tongue release member moves forward in response to its bias, forcing a detent, such as a roller, into an opening in the tongue. The detent continues to extend into a similar coincident opening in a plate contiguous with the tongue, thus locking the tongue in the buckle. Applying slight pressure to the tongue release member, to slide it back against its bias, provides sufficient space above the opening so that the detent is free to leave the opening in the tongue. The tongue is then ejected from the buckle by the ejector which comes to rest below the opening in the plate, thus retaining the detent out of the path of an inserted tongue.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a buckle for receiving and engaging a tongue. The buckle may be used in a safety belt system in a vehicle such as an automobile or airplane, for retaining an occupant in a seated position within the vehicle. The buckle may be attached to the frame or body of the vehicle by a relatively short, rigid or semi-rigid connector. The cooperating tongue may be attached to one or two flexible passenger restraints disposed over the lap, or the lap and chest of the user, and also attached to the body or frame of the vehicle. 
     2. Description of the Prior Art 
     A large number of buckle and tongue combinations are found in the prior art, practically all of which incorporate a buckle having some type of latching means co-acting with a tongue. Safety belt buckles which differ in design from that of the present invention are disclosed in U.S. Pat. No. 3,851,360 to H. Minolla; and U.S. patent application, Ser. No. 663,942, filed Mar. 4, 1976 in the name of R. L. Stephenson. 
     It is an object of the present invention to provide a rugged and functional buckle which cannot be unlatched by the application of stress; yet a buckle wherein the tongue can be released by the application of a minimal effort by the user, even when the buckle is under stress. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to a positive-acting buckle and tongue combination which can withstand tremendous stress directed to pulling the latched tongue from the buckle, because of its novel construction. The tongue can be unlatched, however, by application of a minimum of effort to the tongue release member against a slight outward bias, even when the buckle is under great stress. In fact, such stress would actually serve, in small measure, to further reduce, rather than increase, the pressure required to release the tongue. 
     The tongue, having an opening in the forward portion, is inserted between two plates, the first having an opening therethrough, closed on one side, when the tongue is not inserted, by an outwardly biased tongue ejector, slideably positioned between the plates for motion in line with the direction of insertion and ejection of the tongue. When the tongue is inserted it displaces the tongue ejector against its bias, and when fully inserted, the tongue&#39;s opening coincides with the opening in the first plate, thus together with the plate, forming a small chamber. 
     By the term &#34;plate&#34; we refer to a buckle component having at least one flat surface. Two such plates separated, but with their flat surfaces parallel and facing each other, provide the space for receiving the tongue. Whereas these can be actual plates having parallel sides, yet in practice these plates could be integrated with other components such as guide members, by molding techniques, to lose their platelike characteristics. 
     An outwardly biased tongue release member having a flat surface in sliding contact with the first plate, has in its contacting surface an elongated cavity, which is longer, preferably about twice as long, as the opening in the first plate. This tongue release member is slideable from a first position where the forepart of the cavity is over the opening, and is at least as deep as the thickness of the tongue; and a second position where the rear part of the cavity is over the opening, but is shallow, having less depth than the thickness of the tongue. 
     A detent, such as a roller or sphere, is within the chamber formed by the opening in the plate and the cavity in the tongue release member when the tongue release member is in its first position with the deep section of the cavity over the opening in the plate. The detent is retained in this chamber when the tongue is not inserted, by the tongue ejector which rests beneath this opening. By the term &#34;detent,&#34; we mean a latching member such as a pellet, roller, or sphere, preferably a roller shaped pellet fabricated of metal which lies free in the chamber with its axis of symmetry perpendicular to the path of the tongue on insertion and ejection. When the forepart of the tongue release member forms part of this chamber, there is room within the chamber formed by the first plate and this tongue release member to fully contain the detent, consequently the tongue is ejected and the ejector moves to retain the detent in that chamber. 
     But when the tongue is inserted, the tongue ejector is moved by its bias to its second position where there is insufficient room for the detent in the chamber formed by the shallow cavity and the opening in the first plate, and the detent must extend down into the opening in the tongue, locking it in place, to be released only by sliding the tongue release against its bias, to its first position by applying slight manual pressure. 
     The diameter of the roller is preferably equal to about the combined thickness of the tongue and the first plate. It can be seen that any force applied to withdraw the tongue without first depressing the tongue release member would result in a shearing stress on the detent produced by the tongue and the first plate. The latch could not be forced without either breaking the buckle or tearing the tongue or the first plate apart. The detent could be a roller of case hardened steel. It could alternately be a steel sphere such as a ball bearing, or two or more such spheres arranged side by side. 
     Preferably, the deep section of the cavity in the surface of the tongue release member, and the shallow section, are connected by a short sloping surface. Therefore, if considerable stress is applied to the tongue and buckle; and under this circumstance the tongue release member is pressed, then when the roller reaches the sloping surface, the stress transmitted to the roller by the tongue would serve to further reduce the small amount of force required to release the tongue. This effect is not significant except to point out that the stress can in no way increase the effort required to unbuckle in an emergency. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an exploded perspective view of the buckle of the present invention. It has been drawn upside down, with respect to FIG. 3, to better present the novel features of the invention. Two inserts are also included, repeating certain features for greater clarity. 
     FIGS. 2A, 2B and 2C are perspective views illustrating the relation between the tongue release member and the latching detent when: (A) the detent is in the tongue release position; (C) the detent is in the latched or locked position; and (B) the detent is in the intermediate position between conditions shown in FIGS. 2A and 2C. FIGS. 2A, 2B and 2C also illustrate a slight variation in the preferred embodiment, from the tongue release member of FIG. 1, namely in the shape of the buckle face, and in the fact that two springs are employed rather than one to bias the tongue release member forward to its latched position. 
     FIGS. 3A and 3B are longitudinal cross sections in elevation illustrating (A) the buckle ready to receive the tongue, and (B), the same buckle with the tongue latched in place. 
     FIG. 4 is a view similar to FIG. 2A except that the detent is a sphere. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     With particular reference to FIG. 1, but also to FIGS. 2 and 3, my invention is directed to a buckle for receiving and engaging a tongue. The buckle comprises: a housing 1 having an opening at the front end 2 to provide access to a tongue release member 3; and an opening 4 through which a metal strap 5, or other passenger restraint attached to the buckle, extends. The buckle includes a first or perforated locking plate 9 and a second or slotted plate 7. 
     In the exploded view of FIG. 1, several elements are shown as separate members for clarity, whereas they can conveniently be molded or otherwise fabricated as single units. For example, cover plate 6, slotted plate 7 and tongue guides 8 can be combined as a single unit. Alternately the tongue guides 8 can be a part of perforated locking plate 9. Conversely, the guide 11 for the tongue release member 3 can, if desired, be made of several different members, including a third plate 36. 
     In the tongue release member 3 shown, the front end serves as the front face of the buckle, having a slot 40, an outer portion of which is somewhat funnel-shaped to guide the tongue 25 into the buckle. 
     To assemble, place spiral spring 12 over projection 13 which extends from the inner rear wall of the tongue release guide 11. This projection is not critical; a depression in this rear wall to receive the end of the spring would serve as well. Also, as shown in FIGS. 3A and 3B, the spring can extend inwardly from the rear of the housing 1. 
     Now slip the tongue release member 3 into guide 11, with tab 14 extending into limiting slot 15 in the third plate 36. The free end of spring 12 extends into the cylindrical opening 16 in the end of the tongue release member. The spring 12 now urges the tongue release member 3 outward until stopped as a result of the tab 14 reaching the end of slot 15 within which it rides. 
     Next, place peforate locking plate 9 over the tongue release member, then drop detent 17, which is preferably a roller fabricated of a metal such as steel, into the rectangular opening 23 of the perforate locking plate 9, so that it drops into cavity 18 in the surface of the tongue release member 3. 
     The tongue release member may slide in and out within the distance permitted by limiting slot 15, but the detent 17, which in all positions of the tongue release member extends up into the rectangular opening 23 of the perforate locking plate, is limited to a small degree of vertical movement with respect to the horizontally disposed perforate locking plate. 
     FIG. 2A illustrates the positions of the detent 17 in the cavity in the surface of the tongue release member 3. This cavity, in its forward section 21, is about as deep as the radius of the detent 17. At its rearward section 32 the depression is shallow, and the two levels are connected by a sloping surface 19. In FIG. 2A, the detent 17 is in the deep end 21 of the cavity 18, hence extends up into the opening of the perforate locking plate, but not beyond it. If the tongue release member 3 is moved outward in response to its biasing spring 12, the detent 17 is forced up the sloping surface 19 within the cavity 18 as in FIG. 2B. and onto the shallow portion 22 of the cavity as in FIG. 2C. The detent 17 now has been raised vertically well beyond the top of the rectangular opening 23 of the perforate locking plate. The longitudinal center of the detent 17 is disposed in a plane separate from the plane through which the tongue 25 slides in the buckle. 
     Returning to the exploded view of FIG. 1, and to continue the assembly, place tongue guides 8 over perforate locking plate 9 with the openings for screws or rivets 24 aligned with the corresponding openings in tongue release guide 11. Together, their forward inner surfaces now provide a guide for directing and positioning tongue 25 with its opening 26 directly over opening 23 in the perforate locking plate 9. The rear, substantially parallel inner surfaces of the tongue guides 8 also permit the passage of a tongue ejector 27. 
     Although metal strap 5 can be attached to the buckle in a variety of ways, it can conveniently be placed behind the tongue guides 8 on the surface of the perforate locking plate 9, with its two openings 28 aligned with those at the rear of said perforate plate 9. 
     Ejector spring 29 is next slipped over the projection 31 extending from the rear of tongue ejector 27, and together with the tongue ejector, it is placed within slot 32 of slotted plate 7, with the ejector forward. Tab 33 of the ejector 27 is slideably positioned in the slot with the lower portion 34 of the ejector below the slot 32 to slide along the under surface of the slotted plate 7. 
     Now place the slotted plate 7 over the tongue guides 8, with holes aligned with those in the guides 8 and the strap 5. The lower part of the tongue ejector will now be slideably positioned between the tongue guides in the path of the tongue on its insertion into the buckle. It is urged forward by ejector spring 29 as far as slot 32 will permit, and in this extended position, the lower portion 34 of ejector 27 is directly over the opening 23 in the perforate locking plate. In this position the ejector prevents detent 17 from extending up into the slot for the tongue 25 between plate 7 and 23. 
     Under the circumstances, detent 17 must be in the deeper end 21 of cavity 18 in the tongue release member 3, for there is insufficient room for it in the shallow portion 22 of the cavity, nor on the interconnecting sloping surface 19. It should be clear, therefore, that the detent 17 retains the tongue release member 3, containing cavity 18, in its &#34;pressed back&#34; position in opposition to the outward bias of spring 12. 
     Cover plate 6 has openings for alignment with those of slotted plate 7, but in the case of the cover plate, these openings are threaded to accept screws 24. 
     Finally, cover plate 6 is aligned with the openings in the slotted plate 7, and all those beneath it. Screws 24 are now inserted through the assembled parts and screwed into the openings in the cover plate. The complete assembly can now be fastened by any desired means within housing 1, with strap 5 extending from opening 4 of the housing, for attachment to the frame or body of a vehicle. Of course strap 5 may be any type of restraint such as a cable, belt, or any rigid or semi-rigid connector. 
     Actually, it is conceivable that one may choose to use the buckle without an outer housing, for with molded parts, the outer surfaces can easily be fabricated so that an outer housing is superfluous. 
     The buckle is now in the condition of FIG. 3A, ready to accept the tongue. FIGS. 3A and 3B also illustrate a slight variation in the embodiment of my invention, in that the spring 12 for exerting outward bias on the tongue release member 3, extends from a projection 13 in the back of housing 1. 
     In operation, when tongue 25 is inserted between the guides 8, it encounters the lower portion 34 of the tongue ejector, and forces it backward as permitted by slot 32, against the bias of spring 29. The forepart of the tongue 25 now takes over the function of retaining the detent 17 within the deeper portion 21 of the cavity 18 in the tongue release member, since it has replaced the ejector at this point by sliding it back. There is some upward pressure by the detent 17 against the forepart of the tongue, however, just as there was against the tongue ejector which previously prevented its upward movement. This upward pressure is occasioned by the fact that the spring 12 presses the sloping surface 19 against the detent 17. As soon as the tongue has been inserted to the point where its opening 26 is directly over opening 23 of the perforate locking plate, spring 12 forces the tongue release member forward, and the sloping surface 19 forces the detent 17 to the shallow section of cavity 18. The detent 17 now extends up into the opening 26 in the tongue and locks it securely in place. Even in its locking position, shown in FIG. 3B, the longitudinal center of the detent 17 is in a plane separate from the plane through which the tongue 25 moves in the buckle. The tongue release member now extends forward as shown in FIG. 3B. Any force applied to withdraw the tongue merely sets up a shearing force on the roller between opening 23 in the perforate locking plate, and the opening 26 in the tongue. It would therefore be impossible to remove the tongue in one piece without shearing the detent 17 in half (practically an impossibility), or breaking the buckle. The detent 17, which could be of case hardened steel, is able to withstand far greater stress than the latching members of practically all seat belt buckles of the prior art. 
     To release the tongue, the now extended face of the tongue release member which serves as a push button, is pressed in. As soon as the deeper section 21 of cavity 18 is over opening 23, the detent 17 moves upward in response to the pressure of the biased tongue, thus clearing the tongue. The tongue ejector 27, urged by spring 29, acting on the tip of the tongue, then forces it vigorously out of the slot. It is a novel feature of this buckle that no force need be applied to the tongue release member beyond that required to overcome the bias of its own spring 12, and a minimal amount of friction. There is even a slight assist. As soon as the sloping surface 19 becomes accessible to the roller 17, as the tongue release member 3 is pressed in, this upward force of the roller against the sloping surface also provides a slight force in the same direction as that required to release the tongue. This additional force being supplied by the ejector spring 29, serves to reduce the necessary force required to release the tongue, by a very small amount. 
     The detent need not necessarily be a roller, for one or two steel spheres 17a (FIG. 4) such as ball bearings could achieve the same end. 
     Most of the parts of this buckle can be made of polymeric material, thus providing a light weight buckle. Preferably the roller and the perforate locking plate are fabricated of metal. 
     While I have described preferred embodiments of my invention, it will be understood that various modifications and changes can be made in the buckle and tongue combination described without departing from the spirit of the invention or the scope of the following claims.