EP3375316B1

EP3375316B1 - Connection buckle for seats belts

Info

Publication number: EP3375316B1
Application number: EP18161667.3A
Authority: EP
Inventors: Federico Bonomelli
Original assignee: Mako Shark SRL
Current assignee: Mako Shark SRL
Priority date: 2017-03-14
Filing date: 2018-03-14
Publication date: 2020-05-13
Anticipated expiration: 2038-03-14
Also published as: IT201700028256A1; EP3375316A1

Description

The present invention relates to a connection buckle for seat belts.
The buckle of the present invention comprises a base having one or more insertion seats of corresponding free ends of seat belts, a locking system that allows the ends to be releasably retained inside the insertion seats and is operated by an operating element, and a cover.
The invention relates in particular to buckles for seat belts used in the field of sports, preferably in the automobile and aeronautical sectors.
These belts differ from seat belts commonly used in vehicles as they must comply with much stricter safety requirements.
Moreover, these belts have a plurality of free ends that engage in a single buckle. For safety reasons, the buckle must be produced so as to allow rapid and simultaneous release of all the ends, following a manual operation by the user.
The fact of having to comply with safety requirements means that the buckles currently known in the art are made of different components, so as to obtain kinematic mechanisms capable of ensuring an effective release of the ends.
The button, as operating element for release of the ends inserted in the buckle, cannot be used on these types of buckles as it is not sufficiently safe. For this reason, in the sector in question, namely sports or competition vehicles, lever systems are generally used to be able to simultaneously release of all the free ends of the belts.
As stated above, the mechanisms of these lever systems involve the use of different components, which make prior art the buckles rather heavy. In fact, as these prior art buckles must be relatively strong, they are generally entirely made of metal materials, such as steel or, only for some parts, aluminum or its alloys. However, it is known that, especially in recent years, one of the main aims of competition vehicle manufacturers is to reduce the weight of the vehicle and of all the accessories installed on it.
The document CN201911425U discloses a buckle with the features of the preamble of claim 1.
This search for the lowest possible weight is currently so extreme that reducing the weight of single components a reduction by a few tens of grams can be prove crucial for the overall performance of the vehicle.
Therefore, there is the need, not met by currently available prior art devices, for a buckle for seat belts that complies with the applicable safety requirements, therefore allowing immediate and simultaneous release of the free ends of the belts, but which at the same time has a limited weight.
The present invention achieves the aforesaid objects by proposing a connection buckle for seat belts, comprising:

a base (1) having one or more insertion seats (11) for housing corresponding free ends (4) of seat belts;
a locking system (2) for releasably retaining said ends (4) inside said insertion seats (11), said locking system comprising at least one lock tab (21) housed slidingly in an engaging seat (22) obtained in the base (1);
an operating element (23) that operates said locking system (2); and
a cover (3) connected rotatably to said base (1);

According to the invention, said cover is connected rotatably to the base. Moreover, said operating element, which controls the release of the ends of the belts, is integrated inside said cover.
More in detail, the operating element comprises at least a part integral with the cover.
Unlike prior art systems, the buckle of the present invention has no linkages or other jointed mechanisms that act on the locking means.
Moreover, unlike the aforesaid prior art devices, in which the cover only performs the function of covering the various kinematic mechanisms and of supporting the release lever of the ends, in the buckle of the present invention the cover also has an active function, both as grip and as part of the operating element.
As will be apparent from the description below, with reference to some examples of embodiment, the structure of the buckle of the present invention allows a considerable reduction in weight to be obtained, also limiting the number of components.
In fact, the shape and the arrangement of the various parts that actively operate in the locking system make it possible to produce a simpler mechanism, with fewer parts, while maintaining the same level of safety as prior art systems.
According to the invention, the locking system comprises a lock tab movable in the aforesaid insertion seat of the end of the belt.
Each insertion seat also has an engaging seat, obtained in the base, in which the lock tab can slide.
In an active condition of the locking system, each lock tab is inserted slidingly in the aforesaid engaging seat and, when the free end of the belt is inserted in the buckle, it engages an eyelet of this latter.
The cover is generally and preferably bell shaped with a substantially cylindrical or circular shaped lateral surface.
According to an aspect of the invention, the operating element comprises at least a rotatable part obtained on the inner surface of said lateral wall of the cover and integral therewith.
In this way, rotation of the cover activates or deactivates the locking system of the ends.
According to an aspect of the invention, the rotatable part of the operating element comprises a first annular element. The annular element is, for example, a cam element, i.e. is provided with contact surfaces comprising a cam profile.
The annular shape of the operating element makes it possible to obtain greater compactness of the buckle of the present invention, as it allows other parts of the locking system to be positioned inside it, as will be described hereinafter.
The annular element can be fixed to the inner walls of the cover in any known way that makes it integral with the movement of the cover, in particular with rotation.
According to a preferred variant, the annular element is glued to the cover or, alternatively, can be fixed with screws.
In another alternative, as a function of the material with which the cover is made, the annular element could be produced in one piece with said cover by machining the inner walls, or by molding.
According to a variant of the invention, the rotatable part cooperates directly with a projecting part of each lock tab. More in detail, the contact surface of the rotatable part, and more precisely the cam profile of the annular element, cooperates directly with the projecting part to control translation of the lock tabs.
Following rotation of the cover, the surface of the cam profile cooperates sliding with the projecting part of the lock tab, causing it to translate in the engaging seat, for example taking it toward the release position.
Preferably, the projecting part projects laterally from the lock tab. The projecting part can have the shape of a widening of the section, of a tab or other shapes of equivalent function.
According to another variant of the invention, the operating element also comprises a translatable part that cooperates with the aforesaid rotatable part.
The aforesaid rotatable and translatable parts are at least partially in contact through corresponding contact surfaces. The contact surfaces are structured so that by sliding in relation to one another following a rotation of the cover, and therefore of the rotatable part of the operating system, they cause translation of the translatable part away from the engaging seats.
The translatable part in turn engages the lock tabs so that, by translating, it takes them toward the release position.
From the illustration of some examples of embodiment, it will be clear how rotation of the rotatable part allows the lock tabs to disengage from the eyelets of the free ends of the seat belts.
According to another aspect of the invention, the translatable part comprises a second annular element provided with housing seats of the lock tabs.
Within the scope of the present invention, the term annular means a shape extending in a partial or complete circle. Therefore, the rotatable part and the translatable part can have a closed or open circular shape. Said elements can also be in one piece or in several adjacent sections.
In particular, the housing seats have abutment walls for the widenings of the upper ends of the lock tabs.
Advantageously, each lock tab comprises both an elongated element with a lateral surface and a widening at the upper end. The lateral surface of the lock tab also has a narrowing positioned in proximity of the widening.
The surface of the lock tab, at the narrowing, cooperates with the lateral walls of the seat of the lock tab in the translatable part. This allows the lock tab to slide with respect to the translatable part even when this is stopped. This occurs, for example, when the ends of the belt are inserted into the buckle to be locked.
Preferably, this narrowing has at least one and preferably a pair of flat surfaces, which cooperate with at least a respective surface of the housing seat.
This or these flat surfaces prevent rotation of the lock tab in the engaging seat. This is necessary to keep the lock tab aligned according to a given angular position in which the free end can be inserted into the insertion seat when the lock tab is in the locked position. For this purpose, the lock tab is preferably provided with a tapered lower end that allows the free end to lift the lock tab toward the release position when it is inserted in the related housing seat.
Preferably, said narrowing has a longitudinal extension equal to or greater than the thickness of the free ends of the seat belt.
As will be more apparent from the illustration of some examples of embodiment, the locking system comprises an abutment element integral with the base.
An elastic element can be positioned between the lock tab and said abutment element to hold said lock tab thrust toward the insertion seat.
As well as ensuring noteworthy ease of construction, the arrangement of the different parts in the manner described also allows the number of components to be reduced and their shapes to be simplified.
Ease of construction is also the purpose for which a variant of embodiment of the locking system is produced.
According to this variant of embodiment, the locking system comprises an elastic element that can be stressed rotatably and stressing means of said elastic element.
Advantageously, the elastic element consists of a torsion spring, while the stressing means comprise a pin interposed between the free ends of the torsion spring and at least a driving element that cooperates with a corresponding free end of the spring.
The use of simple shapes, for example of the cover and of the operating mechanism, allows one or more parts thereof to be produced with non metallic materials, so as to reduce the weight of the buckle with respect to those of the prior art.
For example, according to a possible embodiment, some parts of the buckle are made of composite material, such as carbon fiber or the like. Preferably, these parts are at least one or more of the following: parts of the locking system, the cover, the operating element, the base.
It is therefore clear that the reduction of weight of the buckle of the present invention is obtained through two different aspects.
In fact, through integration of the operating element with the cover, it is possible to reduce the number of parts, resulting in a decrease in weight.
Moreover, the shape of the parts and their arrangement allow the use of composite materials to produce them, without affecting the strength of the buckle.
In combination, the characteristics described above contribute to obtaining a buckle that complies with the applicable safety requirements in the sector of competition vehicles and the like and also a considerable reduction in weight, to the benefit of performance.
Advantageously, according to the invention it is possible to provide a limit stop element at release positions of the free ends of the belts.
More in detail, said limit stop element comprises an engaging tab, integral in rotation with the cover, sliding inside a slot obtained on the base.
In practice, the limit stop limits rotation of the cover between the locking position of the ends and at least a release position. Preferably, said limit stop allows the cover to rotate in both directions starting from the locking position toward two respective release positions.
Finally, according to a further embodiment, each engaging seat of the lock tab has a bushing element.
This configuration helps to further reduce the weight of the buckle of the present invention.
As the engaging seats are the parts to which the stress that the end of the belt transmits to the lock tab is transferred, they must be made of a sufficiently strong material.
The fact that these parts are integrated inside the base means that the base must be made of the same material.
According to the invention, the bushing elements that define the engaging seats are instead preferably made of a stronger material, such as steel, and can be integrated in the base, which can instead be made of lighter materials, for example aluminum or its alloys, such as Ergal or the like.
These and other characteristics and advantages of the present invention will be more apparent from the description provided below with reference to some non-limiting examples of embodiments illustrated in the accompanying drawings, wherein:

Fig. 1 is an exploded view of the buckle according to an embodiment of the present invention;
Fig. 2 is a sectional view of the buckle of Fig. 1 in two respective conditions of use;
Fig. 3 is an exploded view of the buckle according to a further embodiment of the present invention;
Fig. 4 is a sectional view of the buckle of Fig. 3 in two respective conditions of use;
Figs. 5a and 5b are respectively a lateral view and a perspective view of the buckle of the present invention, in assembled condition.

It is specified that the embodiments attached to this patent application are provided to give a better understanding of the advantages and the characteristics of the buckle of the present invention.
These embodiments are therefore intended purely for explanatory purposes and do not limit the inventive concept of the present invention, namely to produce a buckle for seat belts that allows the simultaneous and rapid release of several ends, while limiting the weight of the buckle.
With particular reference to Figs. 1 and 3, the buckle for seat belts of the present invention comprises a base 1 having one or more insertion seats 11 of corresponding free ends 4 of seat belts, visible in Fig. 3.
The buckle further comprises a locking system 2 for releasably retaining the ends 4 inside the insertion seats 11. The locking system 2 is operated by an operating element 23. Finally, the buckle comprises an upper cover 3 connected rotatably to the base 1. The cover 3 is preferably bell shaped with a cylindrical or circular lateral wall 3a. The cover 3 preferably also comprises a central part 3b that connects the lateral wall 3a to the base 1. The central part is preferably flat or substantially flat.
Figs. 2 and 4 illustrate the pin 5 that rotatably fixes the cover 3 to the base 1.
Again in Figs. 2 and 4, it can be noted that the operating element 23 is at least partially integrated inside the upper cover 3, so that rotation of the upper cover 3 activates or deactivates the locking system 2, as will be described in more detail hereinafter.
It is specified that the embodiments of Figs. 1-2 and 3-4 differ in the particular configuration of the operating element 23 and of the locking system 2, which will be described hereinafter.
With reference to Figs. 1 and 3, the base 1 comprises two parts, namely a lower part 12 and an upper part 13.
The lower part 12 has a central area of greater thickness, so that, when the lower part 12 and the upper part 13 are superimposed and mutually coupled, a space remains in which the insertion seats 11 are obtained. These latter have a height slightly greater than the thickness of the free ends 4 to allow them to be inserted easily but also without excessive play.
In the example of the figures, the base 1 comprises five insertion seats 11, for the insertion of at least a part of the same number of free ends 4 of seat belts.
The free ends 4, produced in the ways known in the state of the art, have a slot 41 for fixing the seat belt and an eyelet 42, which cooperates, as will be described subsequently, with the locking system 2.
With reference to Figs. 1 and 3, the locking system 2 comprises a lock tab 21 for each insertion seat 11.
At each insertion seat 11, the base also has an engaging seat 22 for the lock tab 21. More precisely, the tab slides in the aforesaid engaging seat 22.
In an active condition of the locking system 2, visible on the left side of Figs. 2 and 4, each lock tab 21 is inserted inside the corresponding engaging seat 22 and occupies the insertion seat 11. When the end 4 of the belt is inserted in the insertion seat, the lock tab is also inserted inside the eyelet 42 of the free end 4 (not shown in Figs. 2 and 4).
The engaging seat 22 is provided on the upper part 13 of the base 1 and preferably also on the lower part 12. In fact, more precisely, a portion of the engaging seat is obtained also on the lower part 12 of the base 1, so that the lock tab 21, passing through the eyelet 42, abuts with its lower end against the aforesaid portion of the engaging seat 22 of the lower part 12.
In accordance with the variant illustrated in Fig. 2, the operating element 23 comprises an annular cam element that cooperates with a widening 211 of the upper end of each lock tab 21.
More in detail, the operating element 23 consists of a rotatable part 232 that cooperates with a translatable part 233.
The rotatable part 232 and the translatable part 233 are at least partially in contact through two corresponding contact surfaces shaped so that a rotation of the rotatable part 232 causes a translation of the translatable part 233 in the opposite direction to the engaging seats 22.
With particular reference to Fig. 1, the contact surfaces of the rotatable part 232 and of the translatable part 233 have complementary profiles, so that when the two parts are coupled they determine a continuous lateral surface.
The rotatable part 232 consists of a first annular element with a cam profile. Therefore, rotation of the rotatable part 232 causes a thrust of the translatable part 233 toward the cover 3.
According to the invention, said rotatable part 232 is obtained or attached on the inner surface of the lateral wall 3a of the cover 3.
In particular, the rotatable part 232 is integral with the cover, while the translatable part is free to move inside the cover 3, so that a rotation of the cover 3 causes an upward translation of the rotatable part 232.
According to the variant illustrated in Fig. 1, the rotatable part 232 has two ridges 234 and two depressions 235. Rotations of the rotatable part 232 in one direction or the other move the translatable part 233 from a position of maximum height, closer to the cover 3, to a position of minimum height.
The translatable part 233 in turn consists of a second annular element having housing seats 236 of the lock tabs 21.
Due to the presence of the widening 211 at the upper end of the lock tabs 21, each lock tab 21 can be inserted inside a corresponding seat 236, so that the widening 211 abuts against the abutment walls of the seats 236.
In this way an upward translation of the translatable part 233 thrusts the lock tabs upward, until reaching a position of maximum height corresponding to the release condition, illustrated on the right side of Fig. 2.
The position of maximum height of the lock tabs 21 corresponds to the release condition, while the position of minimum height corresponds to the locking condition.
The two conditions described above are represented in Fig. 2. The locking condition is shown on the left of the axis A, while the release condition is shown on the right of the axis A.
When an end 4, such as the one in Fig. 3, is present, the lock tab 21 is engaged inside the eyelet 42 of the end 4.
According to the invention, the locking system 2 comprises an abutment element 25 integral with the base 1 and an elastic element 24, typically a spring, positioned between the lock tabs 21 and said abutment element 25. In the variant illustrated a spring is associated with each lock tab so that the lock tab 21 is held thrust in the locked position, together with the translatable part 233, which is thrust in the direction of the rotatable part 232.
Advantageously, each lock tab 21 consists of an elongated element having a lateral surface and a widening of the upper end 211.
Moreover, the lateral surface has a narrowing 222 positioned in proximity of said widening 211, having a longitudinal extension equal to or greater than the thickness of the free ends 4.
This narrowing cooperates slidingly with the walls of the seats 236 in the translatable part 233. More in detail, this narrowing determines the movement that the tab can carry out between the locking position and the release position.
Moreover, this narrowing prevents rotation of the lock tab in the engaging seat. For this purpose, said narrowing has at least one and preferably at least two flat surfaces, which cooperate with corresponding flat surfaces of the housing seat 236 in the translatable part 233.
With this configuration, the lock tab can be raised in the locking position by the end 4 when this latter is inserted in the insertion seat 11.
As shown on the right side of Fig. 2, rotation of the rotatable part 232 causes compression of the spring 24 and the lock tab 21 is raised to release the insertion seat 11.
In the variant illustrated in the figures, the abutment element 25 consists of a cylindrical element with a horizontally bent lip.
Figs. 2 and 4 illustrate how the horizontally bent lip has a boss 251 for positioning of the springs 24.
Therefore, the springs 24 are held stably in position, as a result of the boss 251 and of a seat provided on the lock tab 21.
With reference to Figs. 1 and 3, it can be noted how the cover 3 and the operating element 23 are integral with each other and both fixed rotatably to the base 1.
The abutment element 25 is instead integral with the base 1, both fixed.
Instead, the lock tabs 21 do not rotate, but translate vertically as a result of rotation of the cover 3, passing from the locking condition, to the release condition and vice versa.
With reference to Fig. 2, according to a preferred embodiment, the rotatable part 232 of the operating element 23 is inserted inside the cover 3, so that its outer walls are connected, and preferably in contact, with the inner walls of the cover 3.
According to an alternative embodiment, the rotatable part 232 is made in one piece with the cover 3.
With particular reference to Figs. 1 and 2, the locking system 2 comprises an elastic element 29 that can be stressed rotatably and stressing means of said elastic element 29.
With particular reference to Figs. 1 and 2, the elastic element 29 consists of a torsion spring.
The stressing means comprise a pin 291, a first driving element 292 and a second driving element 293.
As can be deduced from Fig. 2, the pin 291 is interposed between the free ends of the spring 29.
The right side of Fig. 2 clearly illustrates this solution, the upper end is in fact visible, while the lower end is concealed, at least partially, by the pin 291.
The pin 291 is fixed, integral with the base 1, while the driving elements 292 and 293 are integral with the cover 3, so that they rotate with respect to the base 1.
The driving elements 292 and 293 cooperate with the free ends of the spring 29 so that a rotation of the cover 3, in one direction or in the other, causes the expansion, or compression, of the spring 29.
Starting from an idle condition, i.e., with the spring not compressed, rotation of the cover 3 in one direction causes one of the two driving elements to thrust one of the two free ends of the spring 92 in the direction of rotation, while the other free end remains abutting against the pin 291.
The same thing occurs in the case of rotation in the opposite direction, involving the other end of the spring and the other driving element.
As already mentioned, rotation of the cover in one direction or in the other allows passage from the locking condition to the release condition, so that once the release condition has been reached the system tends to return to the locking condition, once the force applied to the cover 3, responsible for rotation, ceases.
According to the variant illustrated in Figs. 1 and 2, the buckle comprises a limit stop element 295 configured to slide in a sliding seat 294 obtained in the upper part 13 of the base 1.
More in detail, the limit stop element 295 allows the user to identify the end of the rotation movement of the cover 3, i.e., that the condition of maximum height of the lock tabs 21, corresponding to the condition of maximum height of the translatable part 233, has been reached.
Finally, according to the variant illustrated in Figs. 1 and 2, the base 1 is coupled to the cover 3 through the use of the pin 5 and of the bushing 61, which allow rotation of the cover 3 with respect to the base 1.
The upper part 13 is instead coupled to the lower part 12, by means of screws of pins 6, illustrated in Fig. 1.
Figs. 3 and 4 illustrate a possible embodiment, alternative to the one described above.
According to this embodiment, the rotatable part 230 of the operating element 23 comprises a cam element that cooperates with a pin 211 present on each lock tab 21.
As in the preceding variant, the cam element 230 is obtained on the inner surface of the lateral wall 3a of the cover 3.
More in detail, the cam element 230 comprises an annular body having a plurality of ridges 231 oriented in the opposite direction to the base 1.
The ridges 231 cooperate slidingly with the pins 211 of the lock tabs 21, so that a rotation of the annular element 23 causes a translation of the lock tabs 21 in the opposite direction to the engaging seats 22. Following this translation, the lock tab is withdrawn from the insertion seat 11, as can be seen on the right side of Fig. 4.
As the cam element 230 is integral with the cover 3, it is evident that rotation of the cover 3 causes it to rotate.
During rotation of the cam element 230, the lock tabs 21 slide along the ridges 231, so as to pass from a position of maximum height, at the top of each ridge, to a position of minimum height, at the depression between two ridges 231, and vice versa.
The position of maximum height of the lock tabs 21 corresponds to the release condition, while the position of minimum height corresponds to the locking condition.
The two conditions described above are represented in Fig. 4, in which the locking condition is shown on the left of the axis A, while the release condition is shown on the right of the axis A.
In the locking condition, the pin 211 is positioned at a depression of the cam element and the tab 21 is in lowered condition and occupies the insertion seat.
In the presence of an end 4, such as the one in Fig. 3, the lock tab 21 would also be engaged inside the eyelet 42 of the end 4.
According to the invention, the locking system 2 comprises an abutment element 25 integral with the base 1 and an elastic element 24, typically a spring, positioned between the lock tabs 21 and said abutment element 25. In the variant illustrated, a spring 24 is associated with each lock tab so that the lock tab 21 is held thrust in the locked position.
As occurs in prior art devices, the shape of the lock tab 21 allows insertion of the end 4 when this latter is in the locking condition.
Instead, the right side of Fig. 4 shows the pin 211 thrust upward by the ridge 231 of the cam element 230. In this condition the spring 24 is compressed and the lock tab 21 is raised to release the insertion seat 11.
In the variant illustrated in the figures, the abutment element 25 consists of a cylindrical element with a horizontally bent lip.
As already mentioned, one or more parts of the locking system 2, of the cover 3, of the operating element 23 and of the base 1 can be made of a non-metallic material, typically a composite material.
Advantageously, according to the variant illustrated in Figs. 3 and 4, the buckle comprises a limit stop element 26 integral with the cover 3.
In the example illustrated in these figures, said limit stop element 26 comprises a pin that slides inside a slot 261 obtained on the upper part 13 of the base 1.
The variant of embodiment illustrated shows a slot 261 that allows three different positions to be obtained: two limit stop positions, in which the pin 26 is in proximity of the end of the slot 261 and an intermediate position, in which the pin 26 is substantially at the center of the slot 261.
For example, the intermediate position can correspond to the locking condition, while the two limit stop positions can correspond to the release condition, or vice versa.
According to a possible variant of the invention, the buckle also comprises a temporary locking element integral in rotation with the cover 3.
Said temporary locking element comprises a spring 27 having one end fixed to the cover 3 and the other opposite end resting on a ball 28.
The ball 28 can releasably engage in corresponding housing seats 281 provided on the upper part 13 of the base 1.
With particular reference to Fig. 3, the housing seats 281 are three and the ball 28 engages in said housing seats each time the pin 26 is in one of the limit stop or intermediate positions described previously.
Starting from a limit stop position, with the pin 26 in contact with the end walls of the slot 261 and the ball 28 engaged in the seat 281 closest to the part of the slot 261 in which the pin 26 is located, rotation of the cover 3 causes compression of the spring 27 and sliding of the ball 28 on the upper surface of the base 1.
As soon as the pin 26 reaches the intermediate position, the ball 28 engages in the seat 281 immediately subsequent to the one occupied previously and so forth, for all the subsequent rotations, in one or other direction, of the cover 3.
Insertion of the ball 28 in the seats 281 produces a slight tactile and auditory sensation, which informs the user that the cover has reached the locking position or one of the release positions.
Moreover, the force required to compress the spring 27 holds the cover stably in one of the aforesaid locking or release conditions.
In this variant, the buckle can still be equipped also, or alternatively, with the elastic element that can be subject to rotation, as illustrated in the previous variant.
Finally, according to the variant illustrated in Fig. 3, each engaging seat 22 has a bushing element 221, inserted in the thickness of the upper part 13 of the base 1. Said bushing elements have the function of distributing the force over a larger surface, if the upper part 13 of the base 1 is made of a composite or light material, or in any case with a mechanical strength lower than that of metallic materials such as steel or aluminum.
Said bushing elements can also equip the buckle according to the variant of Figs. 1 and 2.
The invention has been described purely for illustrative and non-limiting purposes, according to some preferred embodiments. Those skilled in the art may find numerous other embodiments and variants, all falling within the scope of protection of the claims below.

Claims

A connection buckle for seat belts, comprising:
- a base (1) having one or more insertion seats (11) for housing corresponding free ends (4) of seat belts;

- a locking system (2) for releasably retaining said ends (4) inside said insertion seats (11), said locking system comprising at least one lock tab (21) housed slidingly in an engaging seat (22) obtained in the base (1);

- an operating element (23) that operates said locking system (2); and

- a cover (3) connected rotatably to said base (1);
characterized in that the operating element (23) comprises at least one rotatable part (230, 232) on the inner surface of a lateral wall (3a) of said cover (3), the rotation of the cover (3) and of the rotatable part (230, 232) being able to activate or deactivate the locking system (2).
The buckle according to claim 1, wherein the rotatable part (230, 232) of the operating element (23) comprises a first annular element, integral in rotation with the cover (3), provided with a cam profile.
The buckle according to claim 1 or 2, wherein the rotatable part (230) cooperates with a projecting part (211) of each lock tab (21) so that a rotation of the rotatable part (232) causes a translation of the lock tabs (21) toward a release position.
The buckle according to claim 1 or 2, wherein the operating element (23) comprises a translatable part (233), the aforesaid rotatable (232) and translatable (233) parts being at least partially in contact through corresponding contact surfaces shaped so that a rotation of the rotatable part (232) causes a translation of the translatable part (233) away from the engaging seats (22), the translatable part (233) in turn engaging the lock tabs (21) to move them toward a release position.
The buckle according to claim 4, wherein said translatable part (233) comprises a second annular element, the second annular element comprising housing seats (236) of the lock tabs (21) having abutment walls for a projecting part (211) of the upper end of the lock tabs (21).
The buckle according to any one of the preceding claims, wherein the locking system (2) comprises an abutment element (25) integral with said base (1), each lock tab (21) being thrust toward the insertion seat (11) by an elastic element (24) positioned between the lock tab (21) and the abutment element (25).
The buckle according to any one of the preceding claims 4 to 6, wherein each lock tab (21) comprises both an elongated element having a lateral surface and a widening (211) of the upper end, the lateral surface having a narrowing positioned in proximity of said widening (211), said narrowing having at least a flat surface adapted to slide on a respective flat surface of the housing seat (236) of the translatable part (233).
The buckle according to any one of the preceding claims, wherein said locking system comprises an elastic element (29) that can be stressed rotatably, there being providing stressing means of the elastic element (29).
The buckle according to claim 8, wherein the elastic element consists of a torsion spring (29), said stressing means comprising a pin (291), integral with the base (1), interposed between the free ends of said torsion spring (29), and at least a driving element (292, 293) that cooperates with a corresponding free end of the torsion spring (29).
The buckle according to any one of the preceding claims, wherein one or more of the parts forming the locking system (2), the cover (3), the operating element (23) and the base (1) are made of composite material.