TONGUE-AND-BUCKLE FASTENERS FOR SAFETY HARNESSES

Abstract: A tongue-and-buckle fastener, particularly for use with a child's safety harness, comprises a primary tongue (34), a buckle (32) having an opening adapted to receive the primary tongue (34) and having a latching formation adapted to engage with a complementary formation on the primary tongue (34) to retain the primary tongue (34) in engagement therewith, and three additional tongues (36, 38, 40) each having an opening through which the primary tongue (34) can be inserted. A blocker (52) on the buckle (32) is resiliently biased into a first position in which the blocker (52) obstructs insertion of the primary tongue (34) into latching engagement with the buckle (32). In use, the primary tongue (34) is inserted through the openings in the additional tongues (36, 38, 40) before being inserted into the buckle (32). Provided that all the additional tongues (36, 38, 40) are in place, engagement of a formation on the blocker (52) with the additional tongue (36) nearest to the buckle (32) causes displacement of the blocker (52) into a second position in which it does not obstruct insertion of the primary tongue (34) into the buckle (32).

Description: This invention relates to a tongue-and-buckle fastener which is adapted to detachably interconnect at least three straps of a safety harness. It has particular, but not exclusive, application to the provision of a buckle for a child safety harness for use in a motor vehicle. Fasteners of this type have to meet three potentially conflicting requirements. Firstly, in order to facilitate removal of the harness, particularly in an emergency, it is desirable for each strap to be detachable from all of the other straps. Secondly, in order to prevent use of the harness with some of the straps unfastened, it should not be possible for the fastener to secure any of the straps to each other unless all the straps are properly interconnected. Thirdly, it must be possible to retain some of the straps in a temporarily interconnected condition while the other straps are attached thereto during fastening of the buckle. The present invention aims to provide a fastener meeting these three requirements. According to the invention, a tongue-and-buckle fastener for a safety harness comprises a primary tongue having a formation at one end adapted to be connected to a strap, a buckle having an opening adapted to receive the primary tongue and having a latching formation adapted to engage with a complementary formation on the primary tongue to retain the primary tongue in engagement therewith, at least one additional tongue, means for retaining the or each additional tongue in a position of alignment between the buckle and the primary tongue as the primary tongue is inserted into the opening in the buckle, and a blocker on a resilient mounting secured to either the primary tongue or the buckle so as to be biased into a first position in which the blocker obstructs insertion of the primary tongue into latching engagement with the buckle, the blocker having a formation adapted to engage with a surface of one additional tongue when said one additional tongue is in said position of alignment, whereby, if said surface is positioned at a predetermined distance from said resilient mounting, the blocker is displaced into a second position in which it does not obstruct insertion of the primary tongue into the buckle. When only one additional tongue is provided, said predetermined distance is chosen to be equal to the thickness of such additional tongue. Thus, in use, the additional tongue engages between the buckle and the formation on the blocker to displace the latter into its second position. When more than one additional tongue is used, the predetermined distance is chosen to be equal to the combined thickness of all the tongues, with the result that the blocker is not displaced to its second position unless the primary tongue has been inserted through all the additional tongues. The means for retaining the or each additional tongue in said position of alignment may comprise an opening in the additional tongue through which the primary tongue is insertable. In one form of the invention, the blocker comprises a pawl pivotally mounted on the primary tongue so that its tip engages in a notch in the buckle when the pawl is in its first position. The width of the notch is such that the tip of the pawl is displaced beyond the edges thereof only if the primary tongue has been inserted through all the additional tongues before it is inserted into the buckle. Preferably the primary tongue has formations arranged to engage with complimentary formations on the additional tongues so as to inhibit them from being fitted to the primary tongue at an oblique angle in order to simulate the presence of a greater number of primary tongues than are actually fitted and thus prematurely displace the blocker to its second position. An embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a front view of a child vehicle safety seat having a harness provided with a fastener in accordance with the invention; Figure 2 is a fragmentary perspective view of the fastener shown in Figure 1 prior to insertion of the primary tongue into the buckle; Figure 3 is a front view of the buckle shown in Figure 2 in the fastened position and with the cover of the primary tongue removed so as to show the blocker; Figure 4 is a perspective view of the primary tongue of the buckle shown in Figures 2 and 3, with the cover removed, together with one additional tongue; Figure 5 is a scrap view, similar to Figure 3 showing the primary tongue inserted through the additional tongues and partially inserted into the buckle; and Figure 6 is a view, similar to Figure 5, showing the operation of the blocker when an attempt is made to insert the primary tongue into the buckle without first inserting it through the additional tongues. Figure 1 shows a child's vehicle safety seat 10 fitted with a harness comprising a pair of lap straps 12 and 14, a pair of shoulder straps 16 and 18 and a crutch strap 20. The lap straps 12 and 14 and the crutch strap 20 are connected to respective belt adjusters 22, 24 and 26 which allows their length to be varied. The shoulder straps 16 and 18 project through slots 28 and 30 in the seat 10, behind which suitable belt adjusters are located. The harness is provided with a fastener with the invention, comprising a buckle 32, connected to the lap strap 12, a primary tongue 34 connected to the lap strap 14 and three additional tongues 36, 38 and 40 connected to the shoulder straps 16 and 18 and the lap strap 20 respectively. As can be seen from Figures 2, 3 and 4, the primary tongue 34 comprises a plate 42 having a transverse opening 44 at one end, for receiving the lap belt 14, and a V-shaped opening 46 at the other end communicating with a rectangular slot 48 which is adapted to be engaged by a latch member (not shown) within the buckle part 32. Latching arrangements of this type are well known. At an intermediate position along its length, the plate 42 carries a pivot pin 50 on which is mounted a pawl 52 which is biased by a spring 54 in the clockwise direction as viewed in Figure 3. The pawl 52 has a pawl tip 56 which is spaced from the adjacent surface of the plate 42 by a shoulder 58. As can best be seen in Figure 4, the auxiliary tongue 38 comprises a strip-like member having an elongate slot 60 dimensioned to be a sliding fit on the plate 42 of the tongue 42, and a ring formation 62 at one end for receiving the crutch strap 20. The auxiliary tongues 36 and 40 are identical with the tongue 38. However, the straps 16, 18 and 20 are attached to their respective additional tongues 36, 38 and 40 so that the ring formation on the tongue 36 faces towards the buckle 32 when the fastening is secured, while the ring formations on the other two additional tongues 38 and 40 face in the opposite direction (unless any of the straps 16, 18 and 20 is twisted). Reverting to Figure 2, the primary tongue 34 has an enclosing housing 64 which covers the pawl 52 and has two limbs 66 and 68 extending one on each side of the plate 42 and spaced therefrom so as to permit the auxiliary tongues 36, 38 and 40 to be accommodated therebetween. The cover 64 also has two side projections 70 and 72 which engage with the ring formations of the tongues 38 and 40 so as to tend to keep them perpendicular to the longitudinal axis of the primary tongue 34 when fitted thereon. The primary tongue 34 can be inserted through the additional tongue 38 either before or after being inserted through the additional tongue 40. However, interference between their respective ring formations would frustrate any attempt to insert the primary tongue 34 through the additional tongue 38 after it had been inserted through the additional tongue 36, thereby preventing the fastener from being secured with the shoulderstraps 16 and 18 crossed. The buckle 32 has a housing with an opening (not shown) to receive the plate 42 of the primary tongue 34. The housing of the buckle 32 has recessed portions 76 and 78 to receive the projecting limbs 66 and 68 of the cover 64 of the primary tongue 34. The limbs 66 and 68 are of different lengths, as are the recessed portions 76 and 78, so as to prevent insertion of the primary tongue 34 when turned through 180 degrees relative to the buckle 32. The housing of the buckle 32 also has a notch 80 aligned with the pawl tip 56. In use, when the buckle is to be fastened, the three auxiliary tongues 36, 38 and 40 are first assembled on the primary tongue 34 as illustrated in Figure 2. Next, the primary tongue 34 is inserted into the opening in the buckle 32 as illustrated in Figure 5. When the foremost auxiliary tongue 36 engages with the housing of the buckle 32, the pawl tip 56 is in direct alignment with the notch 80. However, as insertion continues, the housing of the buckle 32 presses the auxiliary tongues 36, 38 and 40 against the shoulder 58, displacing the pawl 52 so that its tip 56 is clear of the notch 80 as illustrated in Figure 3. The buckle is then fully fastened. If an attempt is made to insert the primary tongue 34 into the buckle 32 before any of the auxiliary tongues 36, 38 and 40 have been fitted thereon, the pawl tip 56 engages fully in the notch 80, as shown in Figure 6, thus preventing full insertion of the tongue 34. If only one or two of the three additional tongues are fitted to the primary tongue 34, the pawl 50 will be partially displaced but not sufficiently for its tip to clear the edge of the notch 80 and once again, full insertion is blocked. When the buckle is released from its fastened position, as illustrated in Figure 3, the pawl 52 performs the additional function of ejecting the auxiliary tongues 36, 38 and 40 from the primary tongue 34.

Claims: 1. A tongue-and-buckle fastener for a safety harness comprising a primary tongue (34) having a formation at one end adapted to be connected to a strap, a buckle (32) having an opening adapted to receive the primary tongue (34) and having a latching formation adapted to engage with a complementary formation (48) on the primary tongue (34) to retain the primary tongue (34) in engagement therewith, at least one additional tongue (36, 38, 40), means for retaining the or each additional tongue (36, 38, 40) in a position of alignment between the buckle (32) and the primary tongue (34) as the primary tongue (34) is inserted into the opening in the buckle (32), and a blocker (52) on a resilient mounting(50, 54) secured to either the primary tongue (34) or the buckle (32) so as to be biased into a first position in which the blocker (52) obstructs insertion of the primary tongue (34) into latching engagement with the buckle (32), the blocker (52) having a formation adapted to engage with a surface of one additional tongue (36, 38, 40) when said one additional tongue (36, 38, 40) is in said position of alignment, whereby, if said surface is positioned at a predetermined distance from said resilient mounting (50, 54), the blocker (52) is displaced into a second position in which it does not obstruct insertion of the primary tongue (34) into the buckle (32). 2. A fastener according to claim 1 having a single additional tongue (36), wherein the blocker (52) comprises a pawl (52) pivotally mounted on the primary tongue (34) so that its tip (56) engages in a notch (80) in the buckle (32) when the pawl (52) is in its first position, the width of the notch (80) being such that the tip (56) of the pawl (52) is displaced beyond the edges thereof only if the primary tongue (34) has been inserted through the additional tongue (36) before it is inserted into the buckle (32). 3. A fastener according to claim 1 having a single additional tongue, wherein the primary tongue (34) has formations arranged to engage with complimentary formations on the additional tongue (36) so as to inhibit it from being fitted to the primary tongue (34) at an oblique angle. 4. A fastener according to claim 1 having at least two additional tongues (36, 38, 40), wherein the blocker (52) comprises a pawl (52) pivotally mounted on the primary tongue (34) so that its tip (56) engages in a notch (80) in the buckle (32) when the pawl (52) is in its first position, the width of the notch (80) being such that the tip (56) of the pawl (52) is displaced beyond the edges thereof only if the primary tongue (34) has been inserted through all the additional tongues (36, 38, 40) before it is inserted into the buckle (32). 5. A fastener according to claim 1 or 4 having at least two additional tongues (36, 38, 40), wherein the primary tongue (34) has formations arranged to engage with complimentary formations on the additional tongues (36, 38, 40) so as to inhibit them from being fitted to the primary tongue (34) at an oblique angle. 6. A fastener according to any preceding claim, wherein the means for retaining the or each additional tongue (36, 38, 40) in said position of alignment comprises an opening (60) in such additional tongue (36, 38, 40) through which the primary tongue (34) is insertable. 7. A fastener according to any preceding claim, wherein the buckle (32)and the primary tongue (34) have mutually interengaging projections (66, 68, 76, 78) adapted to inhibit insertion of the primary tongue (34) into the opening in the buckle (32) except at a predetermined orientation relative to the buckle (32).

Inventors: CUNNINGHAM, DOUGLAS JAMES, MCKERNON,  DAVID ALLAN, PARRY-WILLIAMS, DANIEL, McKernon, David Allan
Applicants: BRITAX-EXCELSIOR LIMITED
Application year: 1986
Main classification: A44B11
IPC codes: B60R22, A44B11, F16B2