LOCKING TONGUE FOR RETRACTOR TYPE SAFETY BELTS

Abstract: A locking tongue for a retractor type safety belt and a safety belt provided with such locking tongue, wherein the locking tongue has a first slot (12) for the passage of the belt strap (21) transversely through the locking tongue, and a second slot (17) parallel to said first slot, for the passage of the belt strap in contact with a web (16) arranged between the slots and having a curved contact surface. Said second slot is arranged at one side of the web for the passage of the belt strap substantially along the plane of the locking tongue, and this slot has a width (a) perpendicularly to the curved contact surface of the web, which is at least equal to the thickness of the belt strap (21), while the width (b) as measured between two planes parallel to the plane of the locking tongue are less than the thickness of the belt strap.

Description: LOCKING TONGUE FOR RETRACTOR TYPE SAFETY BELTS The invention relates to a locking tongue for retractor type safety belts having a first slot for the passage of the belt strap transversely through the locking tongue and a second slot parallel to the first slot, for the passage of the belt strap contact¬ ing a web provided between the slots and forming a curved contact surface. Locking tongues of this type are used in such vehicle safety belts of the three-point type wherein the belt strap in the operative position of the safety belt extends as a hip strap from a mounting point at one side of the seat to the locking tongue and, after having passed through the two slots of the locking tongue, continues as a chest strap upwards to a " loop fitting mounted at shoulder level to the vehicle wall at said one side of the seat. After having passed through the loop fitting the belt strap then extends substan- tially vertically downwards to a roller-type strap retractor. In order that such a retractor type safety belt shall be comfortable in use the strap must be able to slide easily through the locking tongue when the belt is to be brought into use and the locking tongue accordingly is gripped and the belt strap is withdrawn from the strap retractor, the locking tongue then being engaged with the lock; the position of the locking tongue on the strap will be dependent on the size of the individual using the retractor type safety belt. However, it is at the same time required that the lock¬ ing tongue when the belt is no longer to be used, should be carried along by the belt strap while it is being rolled onto the retractor in order that the locking tongue shall be parked in a position close to the loop fitting where it is easily accessible to be used next time-, and shall not slide downwards along the belt strap to a position on or close to the floor. When the parking position has been attained the belt strap should again 5 be able to slide easily in relation to the parked lock¬ ing tongue, because the retraction of the belt strap otherwise can be stopped if the retractor' is not able to overcome the friction between the belt strap and the locking tongue. If the retraction of the belt strap by 10 . the retpactόr-'is stopped it follows that the belt strap will not be stretched close to the vehicle wall as desired but will hang down in a loop which is in one's way arid if the worst comes to the worst may be an obstacle when one is getting out from the vehicle. 15 Efforts have been made in order to satisfy these mutually contradictory requ rements, viz. that the belt strap in some situations should be able to slide easily in relation to the locking tongue, and in other situations should carry along the locking tongue to 20 the parking position thereof at the loop fitting by friction between the belt strap and the locking tongue. These efforts have included slot arrangements of dif¬ ferent types, but so far no arrangement has been presented which is completely satisfactory in all -25 respects, because such arrangements are compromise solutions, which means that the operation if satisfactory in one respect is less satisfactory in another respect. The primary object of the present inventfon is to arrange a locking tongue of the type referred to above 30 n such a way that there is obtained a change of the strap direction through the locking tongue at different operational stages of the retractor belt by the friction between the belt strap and the locking tongue being adapted to the actual operational stage, 35 To achieve said object as well as additional objects and advantages there is provided in accordance with the invention a locking tongue of the type referred to above wherein said second slot is arranged at one side of the web for the passage of the belt strap substan- 5 tially along the plane of the locking tongue and wherein this slot has a width perpendicularly to the curved con¬ tact surface of the web, which is at leas't equal to the thickness of the belt strap to be used with the locking tongue, while the width of said second slot as measured 10. between two planes parallel to the plane of the locking tongue, is less than the thickness of the belt strap. The invention also comprises a safety belt of the retractor type wherein the belt strap passes through a loop fitting and wherein said locking tongue is 15 mounted to the belt strap which extends through the first and second slots in contact with the curved con¬ tact surface of the web, said second slot being dimensioned as defined above in relation to the belt strap. 20 In order to illustrate the invention an embodiment thereof will be described below with reference to the accompanying drawings in which FIG. 1 is a plan view of a locking tongue according to the invention; ' 25 FIG. 2 is a longitudinal cross-sectional view of the locking tongue in FIG. 1; FIG. 3 is an enlarged fragmentary longitudinal cross-sectional view of the slot portion of the locking tongue; 30 FIG, 4 is a longitudinal cross-sectional view of the locking tongue mounted to a belt strap and showing the locking tongue when engaged with a lock; FIG. 5 is a view corresponding to that of FIG, 4 5 hut showing the locking tongue when carried along OMH. by the belt strap when the belt strap is being retracted by the retractor; and FIG. 6 is a view corresponding to that of FIG, 4 but showing the locking tongue in the parked position thereof close to the loop fitting. Referring to FIGS. 1 to 3, the locking tongue disclosed therein comprises a stamp piece ' of steel sheet which forms a portion 11 to be engaged with a belt lock. This portion can be shaped in different manners for operative co-operation with the lock, depending on the actual lock: type. The locking tongue forms a first slot 12 for the passage of a belt strap transversely through the locking tongue, i.e. from one side of the tongue to the other, and this slot has along all the edges thereof an edge lining 13 of a suitable plastfc material which is molded onto the stamp piece 10. A suitable plastic material is e.g. polypropylene. The edge lining 13 forms two projecting bracket portions 14 which are integral with a bar 15. This bar defines together with a web 16 formed by the stamp piece--and bounding the slot 12, a second slot 17 which is arranged laterally of the web 16 at one flat side of the locking tongue and extends substantially along the plane of the locking tongue in parallel to the slot 12. The edge lining 13 forms around the web 16 a curved contact surface 18 which forms a continuous transition extending from the slot 12 to the slot 17. This surface has a number of ridges or ribs 19 which provide a reduced friction and in a manner known per se guide laterally, i.e. in the longitudinal direction of the web 16, a belt strap in contact with the surfaces of the ribs 19., Said surfaces have a htgh-grade finish as has the surface of the bar 15 bounding the slot 17 so as to reduce the frtction against a belt strap slid- ing on said surface, and this is true also for the edge surface 20 also bounding the slot 12. The width of the slot 17 should be dimensioned in relation to the belt strap used together with the locking tongue, in such a way that the distance a_, 5 FIG. 3, perpendicularly to the curved surface 18 of the web 16 is at least equal to or larger than the thickness of the belt strap used together with the 'locking tongue, while the width _b of the slot 17 as measured between two planes wlitch are parallel to the plane of the locking Q tongue and are tangential to the two bounding lines of the slot 17, as indicated by dot and dash lines in FIG. 3, is smaller than the thickness of the belt strap. As will be noted from FIG. 3 distances ji and b_ are measured between the surface of the bar 15 and the sur- face of the rths 19. When a belt strap 21, FIGS. 4 to 6, is passed through the two slots 12 and 17 of the locking tongue, different operational stages are possible and three stages are shown one in each of FIGS. 4 to 6. When the belt is n^t used, the locking tongue 10 is held in a parked position against a loop fitting 22 which is mounted in a manner known per se to a side wall 23 of the vehicle wherein the safety belt is arranged, and in this parked position the locking tongue is easily accessible so as to be gripped when the belt is to be used. The projecting bracket portions 14 are wide and provide a satisfactory hand grip, and preferably these portions have a rough surface so as to facilitate further the gripping of the locking tongue when the helt strap is to be withdrawn from the retractor. When the belt is to be used and the locking tongue is gripped and pulled out from the parked position, the belt strap 21 will embrace the web 16 substantially in the manner shown in FIG. 4 arid 6 and slide against the surface of the web 16, i.e. the ribs 19, which have a high-grade finish and thus cause a low friction such that the strap can slide easily through the locking tongue. This is facilitated further due to the fact that the surface 18 and the ribs 19, respectively, 5 form a large * radius of curvature. The locking tongue is pulled out and is engaged with the belt lock which is indicated in FIG, 4 at 24, the belt strap forming in this operational position a hip strap portion 25 extending to a fixed mounting point at one side of the 10. seat, and a chest strap portion 26 extending upwards to the loop fitting 22, through " the fitting and along the side wall 23 downwards to a strap retractor. The strap portions adapt themselves as to the length thereof to the individual who is using the safety belt, because 15 the belt strap in thts operational position slides easily through the slots of the locking tongue. Due to the large radius of curvature of the surface 18 and the ribs 19, respectively, the pressure against the strap when loaded is distributed such that the risk of strap 20 breakage at this plac is reduced. The wide slot 12 moreover allows a larger angling of thl belt strap than that normally allowed by locking tongues of conventional design. Finally, it should be noted that the bar 15 in this operational position of the locking tongue does not -25 contact the belt strap, a careful treatment ot the strap accordingly being obtained. When the safety belt should no longer be used and the locking tongue accordingly is disengaged from the lock 24, the belt strap will be retracted by the strap 3 Q retractor via the loop fitting 22 and then the locking tongue will take the position on the belt strap as shown in FIG. 5. In this position, the belt strap while being deformed to some extent from a straight condition engages the web 16 at one side and the bar 15 and the surface 20 35 at the other side of the strap. Under the weight of the locking tongue there is thus obtained an increased friction between the belt strap and the locking tongue by which the locking tongue frictionally engages the belt strap 21 so as to be carried along by the belt strap when pulled in an upward direction towards the loop fitting 22. In this connection it should be noted that the belt strap is also to some extent clamped in the slot 17 due to the dimensioning of the slot 17 in relation to the thickness of the belt strap which is specific for the invention. Eventually, the locking tongue will engage the loop fitting 22 as shown in FIG. 6 and now it is no longer suitable that the friction between the locking tongue and the belt strap is so great that the retractor will not be able to retract the belt strap through the slots 12 and 17. As will- be seen from FIG. 6, the helt strap will again in this position follow the surface of the web 16 (the ribs 191 having a high- -grade finish and will lose the contact with the bar 15. Accordingly, the clamping of the belt strap in the slot 17 previously obtained will be raised and thus the belt strap can again at low friction si ide. through the slots while the locking tongue is retained in the parked position against the loop fitting 22. Therefore, the retractor can retract the belt strap with the locking tongue in the parked position such that the two portions of the strap will be stretched along the side wall 23 hetween the loop fitting 22 at the top arid ' the' retractor and the mounting point, respectively, at the bottom. Thus, It will be seen that the locking tongue according to the invention by taking different positions in relation to the belt strap when the belt is manipu¬ lated in order to be put into use or to be put out of use effects an adjustment of the friction b_etween the locking tongue and the belt strap, the friction being adapted to the different operational stages OMPI

Claims: CLAIMS 1. Locking tongue for retractor type safety belts having a first slot (12) for the passage of the belt strap (21) transversely through the locking tongue and a second slot (17) parallel to the first slot, for the passage of the belt strap contacting a web (16) provided between the slots and forming a curved contact surface, c h a r a c t e r i z e d in that said second slot (17) is arranged at one side of the web (16) for the passage of the belt strap substantially along the plane of the locking tongue and that this slot (17) has a width (a) perpendicularly to the curved contact surface (18) of the web (16), which is at least equal to the thickness of the belt strap (21 to .be used with the locking tongue, while the width (b) of said second slot as measured between two planes parallel to the plane of the locking tongue, is less than the thickness of the belt strap. 2. Locking tongue as claimed in claim 1, c h a r a c t e r i z e d in that said first slot (12) has an edge lining (13) of a plastic material , which encloses completely the web (16} . , and that said second slot (17) is bounded by a bar (15) ^ along one longitudinal side of the slot, which is integral with the edge lining and is supported by portions (14) thereof. 3. Locking tongue as claimed in claim 2, c h a r a c t e r i z e d in that the web (16) forms a curved contact surface (18) for the belt strap (21) extended through the slots (12, 17), said contact surface bounding both slots (12, 17) along one longitudinal side thereof with a continuous transition from one slot to the other. 4. Locking tongue as claimed in claim 2 or 3, c h a r a c t e r i z e d in that the bounding surface of said second slot (17) along the other longitudinal side thereof is curved. 5. Locking tongue as claimed in any of claims 2 to 4, c h a r a c t e r i z e d in that the curved bounding surfaces have a high-grade finish for reduction 5 of the friction against the belt strap (21). 6. Locking tongue as claimed in any of claims 2 to 5, c h a r a c t e r i z e d in that the contact surface of the web (16) is formed with ribs (19) extend¬ ing in the transverse direction of the web to guide Q . laterally the belt strap passed therethrough. 7. Safety belt of the retractor type comprising a belt strap (21) with a locking tongue (10) provided on the strap, said locking tongue having a first slot (12) for the passage of the belt strap transversely through 5 the locking tongue and a second slot (17) parallel to the first slot for the passage of the belt strap contact¬ ing a web (16) provided between the slots and forming a curved contact surface, c h a r a c t e r i z e d in that said second slot (17) of the locking tongue is arranged at one side of the web (16) for the passage of the belt strap substantially along the plane of the locking tongue and that this slot. (17) has a width (a) perpendicularly to the curved contact surface (18) of the web (16), which is at least equal to the thickness of the belt strap (21), while the width (b) of said second slot as measured between two planes parallel to the plane of the locking tongue, is less than the thickness of the belt strap.

Inventors: BERG LARS-EIJE, SYLVEN HANS, BERG, LARS-EIJE, SYLVEN, HANS
Applicants: STIL IND AB, AB STIL-INDUSTRI
Application year: 1983
Main classification: A62B35
IPC codes: A44B11, A62B35