A TONGUE AND BUCKLE FASTENER FOR A SAFETY BELT

Abstract: A tongue and buckle fastener for a safety belt has a tongue with a latching formation which is engaged by a latch plate (48). A push button (22) moves the latch plate (48) into the release position in which the tongue can be ejected by a spring-loaded ejector (36). Prior to insertion of the tongue, the latch plate (48) is held in its fully released position by the push button (22) which is held fully depressed by a catch lever (72). A projection (70) on the ejector (36) holds the catch lever (72) in its engaged position to retain the push button (22) until the ejector (36) has been moved inwards by the tongue by a sufficient distance for the latching formation on the tongue to have passed the latching plate (48).

Description: "A Tongue and Buckle Fastener for a Safety Belt" This invention relates to a fastener for a safety belt comprising a tongue and a buckle having a passageway for receiving the tongue with a latching member movable transversely of the passgeway between a latching position in which it retains the tongue in the passageway and a release position in which the tongue is removable from the passageway. In known fasteners of this type, the latching member is spring-biased into its latched position and a spring-loaded push button, which is displaceable longitudinally of the passageway,is operative when depressed to move the latching member to its release position. Such a fastener is disclosed in our U.K. Specification No.2 030 205. This type of fastener suffers from the disadvantage that the latch member rests on the side of the tongue during insertion of the latter until it can clear the formation of the tongue with which it is to engage and move into its fully latched position. If the tongue is not fully inserted and particii]arly if it is inserted crookedly, there is a risk that the lateral member will remain in a so-called "half latched" position in which it has not fully moved into its latched position bt is merely in edge-to-edge engagement with the tongue. In this condition, although the tongue may resist a limited force tending to remove it fro the buckle, the connection will have insufficient strength to resist the forces likely to arise during an accident. It is an object of the present invention to provide a tongue and buckle fastener of the foregoing type in which the latch member is held out of engagement with the tongue until the latter has been inserted into the buckle to a sufficient extent for the latch member to move into its fully latched position without obstruction. According to the invention, a tongue and buckle fastener for a safety belt comprises a tongue having a latching formation thereon, a buckle in which a passageway is provided for receiving the tongue, a spring-loaded tongue ejector which is slidable in the passageway, a latch member movable transversely of the passageway between a latching position in which it engages with the latching formation to retain the tongue in the passageway and a release position in which the tongue is displaceable by the ejector outwardly along the passageway from its retained position, the latch member being springbiased into its latching position, a push button displacevble longitudinally of the passageway and operative when depressed to move the latch member to its release position, catch means for retaining the push button in its depressed position and release means movable with the ejector for releasing the catch means when the tongue has been inserted into the passageway to such an extent that the latching formation thereon has passed the latch member. Preferably the latch member and push button are coupled desmodromically so that the latter is held in its depressed position when the latch member is in its latching position. This has the advantage that the push button takes up its fully non-depressed position only when the latch member has fully engaged with the tongue and consequently provides a visual indication that complete latching has taken place. In one form of the invention, the catch means comprises a lever which is pivotable between a first position in which it holds the push button in its depressed position and a second position in which it holds the tongue ejector in its depressed position. A protuberance on the ejector prevents the lever from moving into its second position to release the push button when the ejector is in its non-depressed position. Similarly, a protuberance on the push button prevents the lever from moving into its first position to release the ejector when the push button is in its non-depressed position. In another form of the invention, the catch means comprises a spring-loaded catch member attached to the push button so that a detent thereon is urged into engagement with a wall member bounding one side of the passageway so as to be received in.a recess in the wall member when the push button is in its depressed position. The release means comprises a release member mounted on the ejector and having an end projecting through a slot in said wall member into the path of said catch member so as to co-operate therewith to move the detent out of the recess. The projecting end of the release member is capable of limited longitudinal movement relative to the ejector so that the position of the ejector at which the release member frees the push button during insertion of the tongue is further from the end of the buckle from which the tongue is inserted than the position in which the release member allows the detent to enter the recess during ejection of the tongue. Thus, during insertion, release of the push button is delayed until the latching formation of the tongue has passed the latch member. During release, the push button is not retained in its depressed position until the tongue has been ejected sufficiently for the latch member to be unable to re-engage therewith. Embodiments of the invention will now be described by way of example, with reference to the accompanying drawings, in which: Figures 1 and -2 are longitudinal sectional views of a buckle in accordance with one embodiment of the invention, with the tongue ejected and inserted respectively, Figure 3 is a front elevation of the latch member of the buckle shown in Figures 1 and 2, Figure 4 is a scrap plan view of the head of the tongue for use with the buckle shown in Figures 1 and 2, Figures 5 and 6 are scrap sectional views, corresponding to Figure 2, showing modified embodiments of the invention, Figures 7, 8 and 9 are longitudinal sectional views of a buckle in accordance with a further embodiment of the invention, prior to insertion of the tongue, at the intermediate stage during insertion and after insertion has been completed, respectively, Figure 10 is a plan view of a wall member or plate of the buckle shown in Figures 7 to 9, and Figure 11 is a front elevation of the release member of the buckle shown in Figures 7 to 9. Referring to Figures 1 to 4, the fastener comprises a tongue 10 and a buckle 12. As can be seen in Figure 4, the tongue 10 has a head portion 14 with shoulders 16 and 18. Turning to Figures 1 and 2, the buckle 12 comprises a housing 20 in which a push button 22 is slidably mounted for movement between the position shown in Figure 1 and the position shown in Figure 2, a spring 24 biasing it into the latter position. The housing 20 also contains a pair of spaced parallel plates 26 and 28 which define a passageway 30 for receiving the tongue 10. One or both of the plates 26 and 28 may have turned-down edge formations (not shown) to hold the two plates spaced apart at the required distance, as described in our above mentioned U.K. specification. The two plates 26 and 28 are attached by a rivet 32 to a member 34 by which the buckle 12 is secured to the vehicle in which the safety belt is to be used. An ejector 36 has a front portion 38 which extends between the plates 26 and 28 for engagement with the head 14 of the tongue, and a rear portion 40 which has formations projecting. through slots 42 and 44 in the plates 26 and 28-respectively so as to guide the ejector 36 to move longitudinally of the passageway 30 when the tongue 10 is inserted. The rear portion 40 also has a formation serving to locate one end of a coil spring 46 which urges the ejector 36 towards the left, as viewed in Figures 1 and 2, so as to tend to eject the tongue 10. A latch member 48 is mpvable transversely of the passageway through slots in the plates 26 and 28 to the left of the slots 42 and 44 as viewed in Figures 1 and 2. Turning to Figure 3, the latch member 48 is a bridge-like member having a pair of oppositely directed lateral shoulders 50 and 52 and a pair of downwardly directed feet 54 and 56. Each of the feet 54 and 56 is provided with a respective inwardly directed shoulder 58 and 60. The distance between the shoulders 58 and 60 is less than the width of the head 14 while the distance between the lower ends of the feet 54 and 56 is greater than this width. Thus, when the lptch zember 48 is positioned so that the shoulders 58 and 60 are clear of the passageway 30, the tongue 10 can be freely inserted and removed while, when the latch member 48 is moved into a position such that the shoulders 58 and 60 are aligned at the passageway 30, the tongue 10, if previously inserted, is retained in the buckle 20. The push button 22 has a respective pair of ramps 62 and 64 for engagement' lift the lateral shoulders 50 and 52 on the latch member 48. Thus, depression of the push button causes the ramps 62 to engage under the shoulders 50 and 52 to lift the latch member 48 while the ramps 64 force the latch member 48 into its latching position when the push button 22 is released. In accordance with the invention, the rear portion 48 of the ejector 36 carries a limb 70 which extends outside the plate 26 in the opposite direction to the forward portion 38 of the ejector. A lever 72 is pivotally attached to the rivet 32 by a hook formation 74 and has a projection 76 which; when the buckle is in the release position shown in Figure 1, rests on the limb 70 of the ejector. The lever 72 also has an inclined step formation 78 opposite to the projection 76 which engages with a correspondingly inclined formation 80 on the inner end of the push button 22 so as to hold the latter in its depressed position. The upper surface of the lever 72 extends behind the step 78 so that, when the buckle is in the engaged position shown in Figure 2, the free end of the lever 72 is located under the formation 80 on the push button 22. In this position an inclined face 82 on the projection 76 is in engagement with a correspondingly inclined face 84 on the inner end of the limb 70. The operation of the buckle is as follows. When it is in its released position shown in Figure 1, the limb-70 of the ejector 36 holds the lever 72 in its upper position and the resulting engagement between the step 78 thereon and the formation 80 on the push button 22 holds the latter in its depressed position which,in turn, holds the latch member 48 in its released position. When the tongue 10 is inserted, the head 14 thereof engages with the front portinn 38 of the ejector 36, displacing the latter against the spring 46. During insertion of the tongue the lever 72 holds back the push button 22, causing the latch member 48 to be held in its release position until the inclined surface 84 on the ejector 36 has moved into alignment with the inclined surface 82 on the projection 76. This does not happen until after- the shoulders 16 and 18 on the tongue 10 have moved past the latch member 48 to the position shown in Figure 2. The lever 72 then releases the push button 22 so that the spring 24 urges it into its non-depressed position and consequently moves the latch member 48 into its latched position When the fastener is to be released, the push button 22 is depressed. Since the free end of the lever 72 is retained under the formation 80, there is no possibility of this lever being moved clockwise into a position in which depression of the push button 22 could be blocked. Depression of the push button 22 lifts the latch member 48 to its release position so that the tongue 10 is ejected by the ejector 36. The engagement between the inclined surfaces 82 and 84 on the lever 72 and the ejector 36 causes the former to pivot in the clockwise direction back to the position shown in Figure 1 so as to retain the push button 22 in its depressed position ready for the next tongue insertion. As can be seen from Figure 2, when the tongue 10 is secured in the buckle, it is free to move in the passageway 30 by a distance equal to the spacing between the shoulders 16 and 18 thereon and the adjacent face of the latch member AS. This can result in the fastener rattling in use. Figure 5 illustrates a modification which enables the ejector spring 46 to take up this free movement after the latch has engaged. The buckle shown in Figure 5, has an ejector 90 which is similar to the ejector 36 in that it has a front portion 38, but the limb 70 is replaced by a collar 92 which is held in abutment with the rear portion 94 of the ejector 90 by a separate spring 96. The inclined surface 84 is formed on this collar 92 instead of on the ejector 90. The operation of the buckle shown in Figure 5 is as follows. Before the tongue is inserted, the projection 76 on on the lever 72 rests on the collar 92 which is held against a stop 98 bs the spring 96. When the tongue 10 is inserted, the ejector 90 moves inwardly until it abuts against the collar 92 and thereafter both move together until the lever 72 moves into the position shown in Figure 5; allowing the latch member 48 to move into its latching position. When the insertion force is removed from the tongue 10, the ejector 90 moves outwardly to press the shoulders 16 and 18 firmly against the latch member 48, while the collar 92 remains in the position shown, with the surfaces 82 and 84 in abutment with one another. When the push button22 is depressed to move the latch member 48 to its release position, the spring 96 causes the collar 92 to lift the lever 72 as soon as the formation 80 on the push button 22 has cleared the step 78 on the lever 72. Otherwise the operation is similar to that described with reference to Figures 1 and 2. Figure¯6 illustrates a modification of the, buckle shown in Figure 5 which avoids need to provide the additional spring 96. In this case, the ejector 100 has a limb 102 extending in the opposite direction to the front portion 38 of the ejector and on the opposite side of t e plates 26 and 28 to the lever 72. The limb 102 has a protuberance, 104 which engages with the collar 92 to move it to the left, as viewed in the drawing, during the final stages of the ejecting movement of the ejector 100, thereby to cause the inclined surfaces 82 and 84 to lift the lever 72 so that the step 78 thereof engages behind the formation 80 on the push button. If desired, the ramps 64 can be omitted and an additional spring used to bias the latch member 48 into its latching position. The buckle 110 shown in Figures 7 to 11 differs from the previously described buckle in a number of respects. The principal difference is that the buckle 110 has an ejector 112 which includes a transversely extending slot 113 in which is mounted a release member in the form of a rocker 114. Referring particularly to Figure 11, the rocker 114 is of generally cruciform shape with a long limb 116 projecting through the slot 44 in a plate ll8 which, together with the plate 26, defines the passageway 30 for the tongue. The differences between the plate 118 and the corresponding plate 28 of the previously described embodiment will be explained hereinafter. Opposite to the limb 116, the rocker 114 has a limb 120.which projects into the slot 42 in the plate 26. Side limbs 122 and 124 of the rocker 114 engage between the two plates 26 and 118 to retain the rocker in position. The width of the slot 113 is substantially greater than the thickness of the rocker 114 so as to permit pivotal movement of the latter on its limbs 112 and 124. Referring to Figure 10, in addition to the longitudinal slot 44 and the transverse slots 128 and 129 which accommodate the latch plate 44, the plate 118 has two further slots 130 and 131, one on each side of the slot 44. Mounted on a transverse member 132, which forms an integral part of the push button 22, -is a leaf spring 134 having an end portion 136 aligned to form a cam surface to co-operate with the limb 116 of the rocker 114, and two detents 138 aligned to be received in the slots 128 and 130 so as to retain the push button 22 in its depressed position, as shown in Figure 7. The upper ramps 64 on the push button 22 of the buckles illustrated in Figures 1 to 6, is replaced, in Figures 7 to 9, by a curved ramp 140 which is shaped to allow a limited amount of lost motion between the push button 22 and the latch plate 48 when the push button 22 is in an intermediate position, while minimising this lost motion when the push button 22 is in its fully released position with the latch plate 48 engaged. The operation of the buckle 110 is as follows. When the tongue 10 has been ejected, the buckle is as shown in Figure 7 with the detents 138 received in the slots 128 and 130 so as to hold the push button 22 in its depressed position. The latch plate 48 is held clear of the passageway 30 by the ramps 62 of the push button 22. The leaf spring 134 causes the rocker 114 to tilt as illustrated. When the tongue 10 is inserted, the head thereof engages with the ejector 112, displacing the latter against the spring 46 so that it moves into the position shown in Figure 8, the limb 116 of the rocker 114 having passed between the two detents 138 to engage with the end portion 136 of the leaf spring 134. The shoulders 16 and 18 of the tongue are now past the line of action of the latch plate 48 but the push button 22 is still held in its depressed position as the tilted orientation of the rocker 114 has not quite lifted the detents 138 out of the slots 130 and 131. Slight further insertion of the tongue 10 causes corresponding further movement of the ejector 112, the result of which is the complete disengagement of the' detents 138 from the slots 130 and 131 to release the push button 22 whereupon it is urged by the spring 24 into the position shown in Figure 9, the detents 138 resting on the outer surface of the plate 118. When the buckle is to be released, the push button 22 is depressed. When the end portion 136 engages with the rocker 114, it pushes the latter in the opposite direction to that illustrated in Figure 8. The effect of this is that the detents 138 are prevented from engaging in the slots 128 and 130 until after the shoulders 16 and 18 of the tongue 10 have moved to the left of the right hand edge of the latch plate 48, as viewed in Figures 7 to 9, thereby preventing partial re-engagement of the latch plate with the push button in its depressed position.

Claims: CLAIMS 1. A tongue and buckle fastener for a safety belt comprises a tongue (10) having a latching formation (18) thereon, a buckle (12, 110) in which a passageway (30) is provided for receiving the tongue (10), a spring-loaded tongue ejector (36, 90, 100, 112) which is slidable in the passageway (30), a latch member (48) movable transversely of the passageway (30) between a latching position in which it engages with the latching formation (18) to retain the tongue (10) in the passageway (30) and a release position in which the tongue (10) is displaceable by the ejector (36, 90, 100, 112) outwardly along the passageway (30) from its retained position, the latch member (48) being spring-biased into its latching position, and a push button (22) displaceable longitudinally of the passageway (30) and operative when depressed to move the latch member (48) to its release position, characterised by catch means (72, 134) for retaining the push button (22) in its depressed position and release means (184, 114) movable by the ejector (36, 90, 100, 112) for releasing the catch means (72, 134) when the tongue (10) has been inserted into the passageway (30) to such an extent that the latching formation (18) thereon has passed the latch member (48). 2. A fastener according to claim 1, characterised in that the latch member (48) and the push button (22) are coupled desmodromically so that the latter is held in its depressed position when the latch member (48) is in its latching position. 3. A fastener according to claim 1 or 2, characterised in that the catch means comprises a lever (72) which is pivotable between a first position in which it holds the push button (22) in its depressed position and a second position in which it holds the ejector (36) in its depressed position. 4. A fastener according to claim 3, characterised by a protuberance (80) on the push button (22) which prevents the lever (72) from moving into its first position to release the ejector (36) when the push button (22) is in its non-depressed position. 5. A fastener according to claim 3 or 4, characterised by a protuberance (70) on the ejector (36) which prevents the lever (72) from moving into its second position to release the push button (22) when the ejector (36) is in its non-depressed position. 6. A fastener according to claim 3 or 4, characterised in that a slider (92) is located in the passageway (30) on the opposite side of the ejector (36) to that from which the tongue (10) is inserted and has a formation which prevents the lever (72) from moving into its second position to release the push button (2: ) when the ejector (36) is in its non-depressed position, the slider (92) being displaceable longitudinally of the passageway (30) by the ejector (36) on insertion of the tongue (10). 7. -A fastener according to claim 6, characterised in that the slider (92) is resilientiy biased in the direction of the withdrawal of the tongue (10). 8. A fastener according to claim 6, characterised in that the ejector (38) has an extension (104) for moving the slider (92) in the direction of the tongue withdrawal while allowing a predetermined amount of lost motion between the slider (92) and the ejector (38). 9. A fastener according to laim 1 or 2, characterised in that the catch means comprises a spring-loaded catch member (134) attached to the push button (22) so that a detent (138) thereon is urged into engagement with a wall member (118) bounding one side of the passageway (30) so as to be received in a recess (130, 131) in the wall member (118) when the push button is in its depressed position and the release means comprises a release member (114) mounted on the ejector (112) and having an end (116) projecting through a slot (44) in said wall member (118) into the path of said catch member (134) so as to co-operate therewith to move the detent (138) out of the recess (130, 131), said projecting end (116) of the release member (114) being capable of limited longitudinal movement relative to the ejector (112) so that the position of the ejector (112) at which the release member (114) frees the push button (22) during insertion of the tongue (10) is further from the end of the buckle from which the tongue (10) is inserted than the position in which the release member (114) allows the detent (138) to enter the recess (130, 131) during ejection of the tongue (10). 10. A fastener according to claim 9, characterised in that the release member (114) is pivotable relative to the ejector (112).

Inventors: CUNNINGHAM, DOUGLAS JAMES, MACK, JOHN EDWARD
Applicants: BRITAX (WINGARD) LIMITED
Application year: 1981
Main classification: A44B11
IPC codes: A44B11