EP0040132B1 - Safety belt buckle - Google Patents

Description

The present invention relates to a safety strap loop intended to attach a strand thereof to a retaining means by means of a tongue forming a bolt fixed to the strand to be attached to the strap. The mechanism of this buckle is arranged in a housing and comprises a support intended to be fixed to the retaining means and in which can pivot a locking member which retains the bolt in the locked position of the buckle. This locking member also comprises a second abutment surface which can rest on a stop member mounted movably in the support and erasable by means of a control key. When the bolt engaged in such a loop is subjected to a tensile force tending to extract it, the locking member undergoes a tilting torque around its pivot axis in the support which, in the locked position of the loop, is prevented from occurring by the stop member.

Such a loop is described in FR-A _No. 2379995 and FR-A _No. 2,349,296.

One of the improvements described in FR-A No 2349296 consists in providing on the latch, a third abutment surface which is intended to cooperate with a complementary abutment surface formed in the support, the locking member being able to move slightly. in translation in the support in the direction of movement of the bolt. However, this movement is thwarted by an elastic member which acts mainly on which the locking member pivots in the support.

This arrangement has the advantage of providing an additional retaining force when, during an impact, a force exceeding a certain threshold is exerted in the direction of extraction on the bolt, the part of the locking member having the third abutment surface then being subjected to shearing forces which make the loop much more effective at the very moment when its action is essential. Furthermore, during normal use of the loop and more particularly during its opening, the third abutment surface is not active since, under these conditions, the elastic means urge the latch in its normal rear position, thus eliminating this third abutment surface of the complementary abutment surface provided on the support.

If from the point of view of the functioning of the loop, this arrangement is particularly advantageous, it should however be observed that the presence of elastic means complicates the construction of the loop and makes its assembly longer. The cost price of this loop is therefore not as low as one might wish.

The object of the present invention is to provide a loop which, while having the advantages of the presence of an auxiliary abutment surface acting, in the event of an impact, on the support, does not have any particular elastic means, so that this loop is simpler and can be manufactured at a better cost price.

The subject of the invention is therefore a safety strap loop intended to attach a strand of the strap to a retaining means, by means of a tongue forming a bolt, said loop comprising a housing in which a support is arranged. to be fixed by the retaining means, a bolt locking member which is mounted articulated on the support about an axis defined by at least one articulation element, the locking member having a first abutment surface against which is retained the bolt in the locked position, a second abutment surface intended to come to rest against a stop member mounted mobile in the support and erasable by means of a control key to release the locking member and a third surface stop intended to be applied, in the locked position of the buckle, against a complementary stop surface formed on the support, when a traction exceeding a predetermined value is exerted on the bolt in the direction of extraction, this loop being characterized in that the articulation element or elements, by means of which the locking member is articulated on the support, protrude on either side of this member from a distance predetermined, and in that it is further provided bracing means to maintain the lateral position of the locking member relative to its axis of articulation.

It follows from these characteristics, that when a tensile force exceeding a predetermined value is exerted on the strap and the bolt in a direction which tends to get the latter out of the loop, the third abutment surface abuts against the surface complementary stop of the support against the return action created by the elastic deformation of certain zones of the locking member and also of the articulation element or elements by means of which this member is mounted articulated on the support. Such an arrangement makes it possible to considerably simplify the construction of the loop, since the elastic plate which was provided in the loop described in FR-A No 2379995 can be omitted.

• la fig. 1 est une vue en coupe et en élévation d'une boucle pour sangle de sécurité suivant l'invention;
• la fig. 2 est une vue en coupe de la boucle prise selon la ligne 2-2 de la fig. 1;
• la fig. 3 est une vue en perspective, avec arrachement partiel, de la boucle suivant l'invention, son boîtier étant enlevé, et
• la fig. 4 est une vue en perspective éclatée de la boucle suivant l'invention.

Other characteristics and advantages of the invention will become apparent during the description which follows, given solely by way of example and made with reference to the appended drawings in which:

• fig. 1 is a sectional and elevation view of a buckle for a safety strap according to the invention;
• fig. 2 is a sectional view of the loop taken along line 2-2 of FIG. 1;
• fig. 3 is a perspective view, with partial cutaway, of the loop according to the invention, its casing being removed, and
• fig. 4 is an exploded perspective view of the loop according to the invention.

In accordance with the embodiment shown felt in the figures, the loop according to the invention is housed in a housing 1 made in two parts 1 a and 1 b, in molded plastic for example, and joined by welding according to their joint plane. This box is intended only to enclose the mechanical assembly of the loop and it therefore does not participate in the actual operation thereof.

A support 2 having the shape of a stirrup is composed of a core 2a and two wings 2b and 2c, the core extending rearward to form a fixing part 3 crossed by a rivet 4 which is intended to making the loop integral with a retaining means 5. In the embodiment shown, this retaining means comprises in particular a loop in which a strand (not shown) of the safety strap is sewn.

The support 2 defines a sliding passage 6 which extends parallel to the core 2a from front to rear of the loop and which is delimited in particular by two punctures 7 made in the wings 2b and 2c. It can be noted that these punctures extend over a relatively large length for a purpose which will appear later.

A slide 8 preferably made of plastic is placed in the slide 6 so as to be able to move in translation against the action of a spring 9 called ejection bearing on the fixing part 3 of the support 2, the slide 8 being guided by a projecting part 10 in a longitudinal hole 11 made in the core of the support.

The front edge of the slide 8 is profiled so as to adapt to the front edge of a bolt P which is attached to another strand of the safety strap and which therefore has to be made integral with the retaining means 5 when using the buckle in the locked position. As can be seen in particular in FIGS. 1 and 4, the bolt P has a tongue intended to be inserted into the loop and having a rectangular hole T, its width corresponding, apart from play, to the spacing of the wings 2b, 2c of the support 2.

These wings 2b and 2c are crossed through holes 12 by an articulation pin 13, the latter being an element ensuring the articulation on the support of a locking member 14 around an axis XX which extends parallel sliding 6 and transversely to the direction of insertion into the loop of the bolt P (direction indicated by the arrow Y).

The locking member 14 is preferably a piece of cut and folded sheet metal and it has substantially the shape of a U whose core 14a is located at the front and whose wings 14b and 14c extend towards the rear while being provided with holes 15 through which the spindle 13 passes. The core 14a of this locking member comprises a tongue 16 which extends in the direction of sliding 6 and which defines a first abutment surface 17 opposite the fixing part 3 of the support 2. In the connecting portions of the core 14a and the respective wings 14b and 14c, the locking member 14 also has a second abutment surface 18 (two surface portions thus being provided) , while the tongue 16 defines on its face turned towards the front a third abutment surface 19.

The first abutment surface 17 is intended to cooperate with the active edge Ta of the hole T provided in the bolt P; the second abutment surface 18 is intended to cooperate with a stop pin 20 which is arranged transversely in the support and which passes through oblong slots 21 formed in the wings 2b and 2c of the support 2; the third abutment surface 19 is intended to cooperate with the front edge 11a of the hole 11 made in the core 2a of this support.

The wings 14b and 14c have, at their respective ends remote from the core 14a, retaining tabs 22 extending respectively upwards and downwards.

Fig. 2 clearly shows that the pin 13 which constitutes the articulation element of the locking member 14 on the support 2 extends on either side of this member over a predetermined distance before passing through the holes 12 made in the wings of the support 2. The two gaps thus formed between the locking member and this support are filled by spacers 23 of a mounting piece 24 preferably made of plastic and placed between the rear parts of the wings 2c and 2b . The mounting part 24 overlaps the rear part of the wings 14b and 14c of the locking member, these wings penetrating into notches 25, 26 formed on either side of this mounting part. The spacers 23 also have notches with a rounded bottom and intended to be placed by elastic engagement on the spindle 13, it being understood that when the mounting part is placed in the loop, it comes to rest by its rear face against the retaining tabs 22 of the locking member 14.

The mounting piece 24 also has a transverse hole which extends in the longitudinal direction of the support (direction Y) and which is stepped so as to be able to constitute a shoulder 27 for a return spring 28 of the stop pin 20. The spring 28 is mounted on a rod 29 terminated at the front by a button 30 in which is formed a groove 31 so that this button can be placed by elastic engagement on the stop pin 20, to become integral with this last. The rod 29 extends in the direction Y when the loop is assembled.

An actuating button 32 is slidably mounted on the support 2. This button, which is preferably made of plastic material, projects from the housing 1 through a hole 33 made in the upper part 1 a of this housing. It comprises a body 34 from which project lateral tabs 35. Each of these tabs 35 has, on the face turned inward, two grooves 36 and 37 in which are respectively engaged the ends of the pin 13 protruding from the wings 2b and 2c and the ends of the stop pin 20 also projecting from these wings.

Two return springs 38 are engaged respectively on retaining lugs 39 provided on the front edge of the wings 2b and 2c and these springs are also received in blind holes 40 made inside in the front wall 41 of the button 32.

The grooves 37 of the latter have at their front ends stops 42 which are intended to come into contact with the ends of the pin 20, so that when the button 32 is pushed backwards, the pin 20 is also moved backwards to be brought into its erased position corresponding to the opening of the loop.

The operation is as follows.

Figs. 1 and 2 show the closed loop while fig. 3 shows the buckle in the open position, that is to say when the bolt P is removed from it. By first looking at fig. 3 we see that, when the bolt is inserted into the loop, the latter pushes the slider 8 backwards by compressing the ejection spring 9. When the active edge Ta of the hole T made in the bolt P reaches the height of the tongue 16 of the locking member 14, the latter can start its rotational movement around the axis XX while being brought to effect this movement by the action which is exerted by the slide 8 on the spacers 23 of the mounting part 24, the presence of these spacers therefore being advantageously exploited for this purpose.

When the locking member has completed its rotational movement, the abutment surfaces 18 are placed below the stop pin 20, so that the latter can move in translation forward by being pushed into this direction by the spring 28. The spindle having arrived in its extreme front position, the buckle is locked and the bolt can no longer be extracted. It should be noted that during the closing of the loop, the actuation button 32 has remained in place and therefore does not have to be operated.

If the assembly is subjected to a traction exceeding a certain value, traction which is exerted in the direction of the arrow F (fig. 1) and which can occur when a passenger retained by the strap is thrown forward during '' a shock on the vehicle equipped with the loop, the force F is transmitted on the tongue 16 of the locking member by the edge Ta of the bolt P. Under these conditions, the lock is therefore urged forward while being retained by pin 13 which transmits the force via the support 2 on the retaining means 5.

The wings 14b and 14c of the locking member being articulated on the spindle 13 at a certain distance from the wings 2b and 2c of the support 2 and the bearings formed by the holes 12, each of these wings exerts a deformation torque on the portions of the pin 13 protruding on either side of the locking member, so that this pin can deform elastically. It is the same for the tongue 16 so that if the force F is sufficient the front face of the tongue 16 (third abutment surface 19) comes into contact with the edge 11a of the hole 11 made in the core 2a of the support 2. It follows that the locking member is, in a complementary manner, also retained by the core of the support, which very significantly reinforces the effectiveness of the locking of the bolt P. This has the effect that ultimately the elements of the loop can be dimensioned so as to have thicknesses and diameters smaller than in the past. It should be noted that the interval normally separating, in the locked position of the loop, the third abutment surface 19 from the front edge 11a of the hole 11 is very small and that the elastic deformation mentioned above is just sufficient to catch up with this Game.

For example, in a loop made by the holder, we chose for pin 13, a diameter of 4 mm and it was made of steel, having undergone quenching and tempering for a resistance of 120 to 150 daN / mm ² . The locking member 13 was made of steel, the thickness of the metal being 2 mm and the assembly having undergone after quenching and tempering to obtain a resistance of 120 to 150 daN / mm ² . Under these conditions, a force greater than 50 kg exerted on the bolt P was sufficient to make up for the above-mentioned play.

To open the loop, the button 32 is pushed backwards to bring the stop pin 20 backwards against the action of the spring 28. The rod 29 slides in the hole made in the workpiece. mounting 24. The spindle having arrived at the end of its travel in the slots 21, the locking member is released and can tilt upwards to unlock the bolt, the tongue 16 being withdrawn from the sliding passage 6. Naturally, the arrangement which has been described above provides the same advantages as those resulting from the construction of the loops described in FR-A No 2349296 and in Fr-A No 2379995, namely that the force to be exerted by the user on the button 32 is comparatively very small compared to that which is necessary in conventional loops.

A variant of the mechanism described above consists in providing a locking member comprising, integrally formed, articulation elements extending on either side towards the outside and mounted for rotation in the wings of the support.

It will be noted that the guide of the bolt P in the sliding 6 is particularly effective taking into account the arrangement and the large width of the punctures 7. Thanks to this particularity of the buckle, the latter can be opened easily, even if, during actuation of the button 32, the strap exerts on the bolt a considerable oblique force with respect to the orientation of the sliding 6 in the longitudinal plane of symmetry of the buckle, an obliquity going up to 30 ° not interfering with this opening .

Claims (5)

1. A buckle for a safety belt and adapted to attach a belt portion to retaining means (5) through a tongue member (P) constituting a latch, said buckle comprising a case (1) in which is disposed a support (2) for fixing to the retaining means, locking means (14) for the latch (P) which are pivotally mounted on the support (2) to pivot about an axis (X-X) defined by at least one articulation element (13), the locking means (14) having a first abutment surface (17) against which the latch (P) is retained in the locked position, a second abutment surface (18) adapted to bear against a stop means (20) which is movably mounted in the support (2) and retractable by means of a control knob (32) so as to release the locking means (14), and a third abutment surface (19) adapted to be applied in the locked position of the buckle against a complementary abutment surface (11 a) formed on the support (2) when a tensile force exceeding a predetermined value is exerced on the latch (P) in the extracting direction, this buckle being characterised in that the articulation element or elements (13) by means of which the locking means (14) are pivotally mounted on the support (2) project from each side of these means (14) by a predetermined distance and spacer means (23, 24) are provided for maintaining the lateral position of the locking means (14) relative to its pivot axis (X-X) so that, when said tensile force is exerted, the third abutment surface (19) and the complementary abutment surface (11 a) come into contact with each other by flexible deformation of said articulation element or elements (13).

2. A buckle according to claim 1, wherein said support (2) is in the form of a U-shaped element between the branches of which the looking means (14) are disposed which are pivotally mounted on the support by a pivot pin (13) which extends through these branches, characterised in that said spacer means are formed on a mounting element (24) having two spacer members (23) disposed respectively on each side of the locking means (14) and against the branches (2b, 2c) of the support (2).

3. A buckle according to claim 2, characterised in that each spacer member (23) has a notch (26) into which said pivot pin (13) passes and by means of which the pivot pin is rendered connected to the mounting element (24) by a resilient clipping.

4. A buckle according to claim 2 or 3, wherein the locking means (14) are in the form of a U-shaped element whose branches are pivotally mounted on the pivot pin (13) and whose web definis said first and third abutment surfaces, characterised in that said mounting element (23) is disposed in a straddling manner on the free ends of the branches (14b, 14c) of the locking means (14).

5. A buckle according to any one of the claims 2 to 4, wherein said support (2) defines a guiding passage in which the latch (P) is engaged when locking, characterised in that said guiding passage (6) is defined by elongated projections (7) formed in the lateral branches (2b, 2c) of the support (2).

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