WO2023199247A1

WO2023199247A1 - Saddle for a bicycle

Info

Publication number: WO2023199247A1
Application number: PCT/IB2023/053750
Authority: WO
Inventors: Giovanni TRABACCHIN; Davide MARCON
Original assignee: Lgg Lighting Srl
Priority date: 2022-04-12
Filing date: 2023-04-12
Publication date: 2023-10-19

Abstract

A saddle (1) for a bicycle comprises a seat member (2) in which there are defined a rear portion (3), which is widened, for supporting the buttocks, and a front portion (4), which is narrowed and elongate, for supporting the perineum, a support frame (5) for the seat member which is shaped to define two rear ends (6) and an opposite front end (7) which are inserted in fixing seats (8, 9) which are defined in the rear and front portions of the seat member, respectively, a housing (10) which is formed in the seat member for inserting an accessory and retention means (11) which are mounted on the housing so as to interfere with the accessory, when it is inserted in the housing, in order to retain it therein.

Description

A saddle for a bicycle

DESCRIPTION

Technical scope

The present invention concerns a saddle for a bicycle and a kit comprising said saddle and at least one accessory.

Technological background

One drawback of the known cycling saddles is the limited ability to carry accessories.

From EP1796954 a guick coupling system for removably coupling an accessory such as in particular a tool-holding bag to the saddle is known. The system provides for an extension piece associated with the bag and which can be inserted into a seat with complementary shape defined in the saddle. The extension piece has snap retention means comprising a tooth which is engageable in a corresponding slot which is in the seat.

Thanks to this particular configuration it should be possible to firmly bind the accessory to the saddle while minimizing the risks of accidental loss. However, the solution described in EP1796954 is not free from disadvantages since the modes of integration of the snap retention means in the extension piece makes the extension piece itself and therefore also the saddle when it is associated with the accessory rather cumbersome.

Moreover, the solution described in EP1796954 does not provide for the possibility of replacing parts of the saddle itself other than the accessory. This entails an increase in the costs that must be incurred in order to produce technical and/or aesthetic variants of the saddle.

In addition, in the event that a part of the saddle gets damaged, such as the seat of the accessory, the entire saddle must be replaced in order to restore it. Of course the same problem arises in relation to the replacement of any other part of the saddle. This problem is particularly felt when it is desired to renew the seat member surface, the latter being generally subject to a rapid deterioration due in particular to rubbing wear or to the detachment of the material with which the seat member is covered. To renew the seat member surface it is known to replace the entire saddle although, structurally, it is still suitable to support the load and therefore has a residual useful life.

It would therefore be desirable to supply a structurally simple and compact saddle that is provided for the reversible assembly of replaceable or interchangeable parts including in particular an accessory.

Another example of a saddle for a bicycle is described in EP3060460.

Description of the invention

The problem underlying the present invention is that of realizing a saddle and a kit comprising said saddle that are structurally and functionally designed to overcome, at least in part, one or more of the drawbacks complained about above with reference to the cited known art.

Within this problem, a particular aim is that of realizing a saddle whose structure allows easy and safe anchoring of accessories. Another aim of the invention is that of realizing a saddle that is easy to disassemble and reassemble.

Such problem is solved and such objects are at least in part achieved by the present invention by means of a saddle for a bicycle and a kit comprising said saddle which are realized according to one or more of the features of the attached claims.

The saddle comprises a seat member and a frame (also known as a "fork") for supporting the seat member. There are also preferably provided a housing which is formed in the seat member for the insertion of an accessory and retention means, preferably snap retention means, including in particular a tooth and a resilient element. The retention means are mounted on the housing so as to interfere with the accessory, when it is inserted in the housing, in order to retain it therein.

In the seat member, there are generally defined a rear portion, which is in particular widened, for supporting the buttocks, and a front portion, which is in particular narrowed and elongate, for supporting the perineum.

It is preferred that the support frame for the seat member is shaped to define two rear ends and an opposite front end. It is further preferred that the rear and front ends are inserted into fixing seats which are defined in the rear and front portions of the seat member, respectively.

Based on one aspect of the invention, the seat member comprises a first hull defining in particular a seat member surface, and a second hull having in particular the housing for inserting the accessory.

Preferably, the first and second hulls extend from the rear portion to the front portion.

Still preferentially, the first and second hulls are at least partially superimposed and removably fixed to each other.

It will therefore be possible to combine different versions of the first and second hulls to produce a range of saddles that takes into account the different needs of the market as well as the availability of production, without however affecting the complexity of construction and production costs. For example, it will be possible to produce a range of saddles each characterized by different finishes of the first hull but all having in common the use of the same component for the second hull, so as to reduce the costs necessary to diversify one saddle from the other. In addition, thanks to this particular configuration, the user can easily remove the first hull for maintenance or customization interventions of the saddle, for example to replace the seat member surface at will.

Advantageously, the first and second hulls comprise respective portions which face each other and which are formed so as to define in the mutually facing zone at least one recess configured to define at least one of the fixing seats for the ends of the frame and/or at least one receiving seat for the retention means.

This particular configuration makes it possible to realize a saddle having a simple and compact dismountable structure in which the first and second hulls, the frame and the retention means constitute individually replaceable parts that are perfectly integrated with each other in order to minimize the overall dimensions and the number of additional components and to simplify the saddle assembly operations as much as possible.

In a further aspect, the invention concerns a kit comprising the saddle described above and an accessory comprising an extension piece configured to be inserted into the housing. In particular, the extension piece of the accessory and the retention of the saddle means are formed so as to urge the tooth out of the housing counter to the resilient element by interference between the tooth and extension piece when the extension piece is inserted into the housing and to allow the tooth to engage with a recess of the extension piece in order to retain the extension piece in the housing when the tooth and recess are located in a position of mutual alignment.

Brief description of the drawings

The characteristics and advantages of the invention will become clearer from the detailed description of an embodiment shown, by way of nonlimiting example, with reference to the appended drawings wherein :

- figure 1 is a bottom perspective view of the saddle in accordance with a first embodiment of the invention;

- figures 2 and 3 are exploded views respectively from the top and from the bottom of the saddle of figure 1;

- figure 4 is a perspective view from above of the saddle of figure 1 from which some components have been removed in order to illustrate others that are normally not visible;

- figure 5 is an exploded view of a detail of figure 4;

- figures 6 and 7 are plan and longitudinal sectional views respectively of a kit comprising the saddle in accordance with a second embodiment of the invention and a relative accessory;

- figure 8 is a perspective view of a detail of the accessory of figures 6 and 7.

Preferred embodiment of the invention

In the figures, a saddle for racing bikes, mountain bikes, city bikes or similar is indicated as a whole with 1.

In the following, the concepts relating to the saddle 1 are therefore mainly exposed with reference to a saddle for a bicycle, but they are not limited to the cycling field. The saddle according to the invention is in fact suitable for several saddle-type vehicles such as for example tricycles or motorcycles.

The saddle 1 comprises a seat member 2 in which there are defined a rear portion 3, which is widened, for supporting the buttocks, and a front portion 4, which is narrowed and elongate, for supporting the perineum.

The saddle 1 further comprises a support frame 5 for the seat member including a tube 50 which is shaped to define two rear ends 6 and an opposite front end 7 of the frame itself as well as preferably a pair of rails 51 for fixing the saddle to a seatpost (not shown). Of course the tube 50 can be replaced by a bar. Tube or bar are preferably made of metallic material.

The rear 6 and front 7 ends of the frame are inserted in fixing seats 8, 9 which are defined in the rear 3 and front 4 portions of the seat member, respectively. In particular, the rear portion 3 of the seat member has two rear fixing seats 8 for the rear ends of the frame, while the front portion 4 of the seat member has a front fixing seat 9 for the front end of the frame. The fixing seats 8, 9 are preferably arranged symmetrically with respect to a centre plane of the saddle.

In an aspect highlighted in the examples of figures 2 and 3, the seat member 2 comprises a first hull 12 and a second hull 13 which extend from the rear portion 3 to the front portion 4. The first and second hulls 12, 13 are removably fixed to each other and at least partially superimposed. The first hull 12 in particular defines a seat member surface 14 and an opposite shaped surface 14' with concavity facing the second hull 13 to receive a corresponding portion thereof. First and second hulls 12, 13 are preferably made of plastic material.

The fixing seats 8, 9 of the ends of the frame are defined between the first and second hulls 12, 13 in the zone of superposition between the first and second hulls. In particular, first and second hulls 12, 13 comprise respective shaped portions 15 which face each other and are formed so as to define, in the mutually facing zone, respective recesses 17 configured to define the fixing seats 8, 9 for the ends of the frame. In particular, the shaped portions 15 comprise concave portions 15a which are made integrally in the second hull 13 and are formed with concavity facing the first hull 12 to receive, with interposition of the ends of the frame, corresponding convex portions 15b which are made integrally in the first hull 12 and are formed with convexity facing the second hull 13. Of course in some embodiments concavity and convexity can be reversed, i.e. the concave portions 15a can be made integrally in the first hull 12 and the corresponding convex portions 15b can be made integrally in the second hull 13.

According to a further advantageous aspect, the ends 6, 7 of the frame are retained in their fixing seats 8, 9 by fastening the hulls 12, 13 and in particular the respective shaped portions 15 against opposite surfaces of the frame ends 6, 7 themselves. For this purpose, there are preferably provided threaded connection means 20 which are configured to couple by fastening the first and second hulls 12, 13 in an adjacent manner or at the fixing seats 8, 9. In some embodiments, the rear fixing seats 8 are each defined by at least one cradle 52 and one clamp 53 which face each other. It is preferred that clamp 53 and cradle 52 are made integrally respectively in the first and in the second hull 12, 13 but the inverse solution in which clamp and cradle are made integrally respectively in the second and in the first hull is also contemplated.

The rear fixing seats 8 each have an opening 54, preferably defined through the second hull 13 and in particular through the cradle 52, to allow the insertion of the respective rear end 8 of the frame according to a frontrear direction and sense Y. When the first hull 12 is applied on the second hull 13, the clamp 53 advantageously presses the respective rear end 8 of the frame against the cradle 52 in which the end itself is received in order to retain it therein.

For better retention, it is preferred that threaded connection means 20 between the first and second hulls 12, 13 are provided in an intermediate position between the rear fixing seats 8.

In some embodiments, the front fixing seat 9 is defined at least by an upper wall 55 and a lower wall 56 which face each other and which are preferably made integrally respectively in the first and in the second hull 12, 13.

Still in some embodiments, the front fixing seat 9 has an opening 57, preferably defined through the second hull 13, to allow the insertion of the front end 7 of the frame into the front fixing seat 9 according to a frontrear direction and sense X. When the first hull 12 is applied on the second hull 13, the upper wall 55 advantageously presses the front end 7 of the frame against the lower wall 56 so as to retain the end itself in the respective seat 9.

For better retention, it is preferred that threaded connection means 20 between the first and second hulls 12, 13 are provided in the region of the front fixing seat 9, as highlighted in the example of figure 4. It is further preferred that the front end 7 of the frame has an opening 58 through which the threaded connection means 20 are inserted so as to prevent a front-rear removal of the frame 5 from the front fixing seat 9. It is of course preferred that the opening 58 and the threaded connection means 20 that engage it extend transversely to the direction of front-rear removal.

In some embodiments, the rear ends 6 of the frame are inserted into the respective fixing seats 8 according to the front-rear direction and sense Y, while the front end 7 of the frame is inserted into the respective fixing seat 9 according to the front-rear direction and sense X. Of course it is preferred that the first hull 12 is applied on the second hull 13 only after insertion of the ends 6, 7 of the frame into the openings 54, 57 of the respective fixing seats. It is further preferred that, during assembly, the front end 7 is first inserted into the opening 57 of the front fixing seat and then the rear ends 8 are inserted into the openings 54 of the respective rear fixing seats.

As highlighted in the example of figure 4, the rear ends 6 of the frame extend longitudinally in the rear fixing seats 8 over a first length LI. To facilitate the insertion of the rear ends 6 into the openings 54 of the respective rear fixing seats during assembly, the frame 5 and the second hull 13 are advantageously formed so that, without the first hull 12, the front end 7 of the frame can be inserted into the opening 57 of the front fixing seat over a second length L2 which is greater than or at least equal to the first length LI. As highlighted in the example of Fig. 2, the first and second lengths LI, L2 are preferably measured in the rear-front direction

X.

In some embodiments, the saddle 1 comprises a covering 26 which is applied to the seat member surface 14 of the first hull. The covering 26 is preferably made of leather, microfibre or other similar and equivalent technical fabric. A padding (not shown) may be interposed between the covering 26 and the seat member surface 14 of the first hull to improve seating comfort. Advantageously, the covering 26 extends from the seat member surface 14 until it interferes with an opposite peripheral edge 27 of the first hull in the region of which the first hull is at least partially superimposed on the second hull. In this way the covering 26 is retained peripherally in the zone of superposition between the first and second hulls 12, 13 so as to minimize the risk of accidental detachment of the covering. In any case, to renew the covering 26, it is sufficient to replace the first hull 12.

In an aspect highlighted in the example of figure 7, the invention also concerns a kit 30 comprising the saddle 1 and an accessory 100 such as for example a headlamp, a camera of the type known in particular under the brand GoPro, an object-holding bag, a fender or other.

A saddle 1 and accessory 100 can be coupled removably to each other. In particular, the saddle 1 is provided for the quick-release anchoring of the accessory. For this purpose the saddle comprises a housing 10 which is formed in the second hull 13 for inserting the accessory 100 and snap retention means 11 which are mounted on the housing so as to interfere with the accessory, when it is inserted in the housing, in order to retain it therein.

As highlighted in the example of figure 3, the housing 10 is arranged in the region of the rear portion 3 of the seat member and preferably comprises a guide 25 which extends longitudinally in particular in the rear-front direction X. The guide 25 is arranged to receive, with an ability to slide in its longitudinal direction, an extension piece 101 of the accessory. The extension piece 101 is shown in the example of figure 8.

It is preferred that the guide 25 has a section provided with at least one and in particular two mutually facing or opposite undercuts 59 that extend in the longitudinal direction of the guide. It is further preferred that the extension piece 101 has a prismatic shape which is complementary to that of the section of the guide 25.

The retention means 11 preferably comprise a tooth 21 which is provided with a resilient element 22 such as a spring.

According to embodiments, the tooth 21 is tilting about an axis of oscillation T which in particular is transverse to the direction of insertion of the accessory into the housing (in the present embodiment, the rear-front direction X).

Advantageously, the tooth 21 is formed like a latch, i.e. shaped such as to move out of the housing 10 counter to the resilient element 22 when a surface thereof interferes with a corresponding surface of the extension piece 101 when inserting the extension piece into its housing and then snap into engagement with a recess 102 of the extension piece when the extension piece is correctly inserted into the housing. This facilitates the insertion of the accessory into the housing and ensures its correct retention.

In one aspect, the retention means 11 are applied between the first and second hulls 12, 13 in the zone of respective superposition. In particular, the first and second hulls 12, 13 comprise special shaped portions 16 which face each other and which are formed so as to define in the mutually facing zone a special recess 17 configured to define a seat 19 for at least partially receiving the holding means 11. In particular, the special shaped portions 16 comprise at least one concave portion 16a which is made integrally in the second hull 13 and formed with concavity facing the first hull 12 to receive, with interposition of the retention means 11, at least one corresponding convex portion 16b which is made integrally in the first hull 12 and formed with convexity facing the second hull 13. Of course in some embodiments concavity and convexity may be reversed, i.e. the at least one concave portion 16a may be made integrally in the first hull 12 and the corresponding convex portion 16b may be made integrally in the second hull 13.

According to a further advantageous aspect, the retention means 11 are retained in the receiving seat 19 by fastening the hulls 12, 13 and in particular the special shaped portions 16 against opposite surfaces of the same retention means 11. Of course it is preferred that the first hull 12 is applied on the second hull 13 only after insertion of the retention means 11 in the receiving seat 19. For better fastening the receiving seat 19 is preferably interposed between threaded connection means 20 that join the hulls 12, 13 in the region the rear portion 3 of the seat member. More particularly, the receiving seat 19 is interposed between the fixing seats 6 of the rear ends of the frame, advantageously the threaded connection means 20 extending from the second hull 13 to the first hull 12 in an intermediate position between the receiving seat 19 and the fixing seats 6 of the rear ends of the frame. Thanks to this configuration it is possible to use the same threaded connection means 20 to retain both the rear ends 6 of the frame and the retention means 11 in the respective seats by fastening the hulls.

As shown in the examples of figures 5 and 7, in the present embodiment the receiving seat 19 is defined by at least a first wall 60 and a pair of mutually facing flanks 61 extending transversely to the first wall 60. In some cases there is also provided a second wall 62 opposite the first wall 60. The first wall 60 is preferably made integrally in the first hull 12, while the flanks 61 and any second wall 62 are preferably made integrally in the second hull 13.

Advantageously, the receiving seat 19 is arranged to receive the axis of ascillation T of the tooth so that the tooth 21 is hinged between the opposite shaped portions 16 of the hulls. For this purpose, in particular, the flanks 61 have respective niches 63 which face each other to receive the opposite longitudinal ends 64 of the axis of oscillation. The niches 63 and the first wall 60 are formed so as to allow insertion of the ends 64 of the axis of oscillation into the respective niches 63 without the first hull 12 and bind the ends 64 of the axis of oscillation between niches 63 and the first wall 60 when the first hull 12 is applied on the second hull 13. Preferably, the receiving seat 19 also has an opening 65 facing the housing, through which the tooth 21 can protrude to interfere with the extension piece of the accessory. The opening 65 is defined in particular through the second wall 62 in a preferably intermediate position between any undercuts 59 of the guide. Preferably, the receiving seat 19 further comprises an abutment portion 66 which is configured to limit the maximum protrusion of the tooth from the opening 65. The abutment portion 66 can be identified on the second wall 62.

In one aspect, the receiving seat 19 is also provided to receive the resilient element 22 so that it is interposed, preferably with compression, between the tooth 21 and the first wall 60 of the first hull. It is preferred that the resilient element 22, in particular a compression spring, acts on the tooth 21 at a certain radial distance from the axis of oscillation T. Thanks to this configuration the resilient element 22 urges the tooth to protrude through the opening 65 facing the housing 10 so as to interfere with the extension piece 101, when it is inserted in the housing, in order to retain it therein.

To exert the retaining action, the tooth 21 comprises a projecting portion 67 configured to project into the housing 10. According to an embodiment, the projecting portion 67 has an essentially triangular wedge-shaped profile whose vertex is pointed towards the housing 10. In particular, the profile is a rectangular triangle with oblique side which forms a sliding plane for an inclined or otherwise formed (e.g. rounded) plane surface of the extension piece 101 so as to press the projecting portion 67 counter to the resilient element 22 out of the housing when the extension piece is inserted into the housing. The resilient element 22 is preferably interposed between the projecting portion 67 and the first wall 60 of the first hull. In order to be able to manoeuvre the projecting portion 67 out of the housing 10 counter to the resilient element 22, the tooth 21 preferably comprises a lever portion 23. The axis of oscillation T of the tooth is preferably interposed between the projecting portion 67 and the lever portion 23. In this way the tooth 21 with its lever portion 23 and the resilient element 22 form a lever of the first order.

According to embodiments, the lever portion 23 extends away from the axis of oscillation T towards the outside of the receiving seat 19.

In the example of figures 1 to 5, the lever portion 23 extends essentially in the rear-front direction and sense X.

In the example of figures 6 and 7, the lever portion 23 comprises a manoeuvring end 24 extending transversely to the direction of insertion of the accessory into the housing (in the example, the rear-front direction). Advantageously, the manoeuvring end 24 is configured to be pressed according to the front-rear direction and sense Y so as to manoeuvre the tooth 21 out of the housing 10 counter to the resilient element 22. The manoeuvring end 24 preferably corresponds to the free end of the lever portion 23 which, for the remainder of its extension, extends from the axis of oscillation T mainly according to the rear-front direction and sense X. Thanks to this configuration the manoeuvring end 24 can be positioned in a protected manner behind the accessory (with respect to the rear-front direction and sense X) when the accessory is inserted into the housing. Furthermore, this configuration facilitates the operation of removing the accessory from the housing as it allows to press the manoeuvring end 24 to release the tooth and then remove the accessory from the guide 25 in a single gesture with one hand.

In some embodiments, the seat member 2 comprises a through channel 40 which is defined in an intermediate position between the rear 3 and front 4 portions. Preferably, the possible through channel 40 faces the lever portion 24 so as to allow access and manoeuvring of the lever portion through the through channel.

The invention thus solves the proposed problem and achieves numerous advantages including : ease of replacement of components for the repair or customization of the saddle; fast and safe anchoring of accessories of all kind; structural simplicity; minimum weight and footprint.

Claims

CLAIMS A saddle (1) for a bicycle comprising:

- a seat member (2) in which there are defined a rear portion (3), which is widened, for supporting the buttocks, and a front portion (4), which is narrowed and elongate, for supporting the perineum,

- a support frame (5) for the seat member which is shaped to define two rear ends (6) and an opposite front end (7) which are inserted in fixing seats (8, 9) which are defined in the rear and front portions of the seat member, respectively,

- a housing (10) which is formed in the seat member for inserting an accessory and retention means (11) which are mounted on the housing so as to interfere with the accessory, when it is inserted in the housing, in order to retain it therein, wherein the seat member comprises a first hull (12) and a second hull

(13) which extend from the rear portion to the front portion, the first and second hulls being removably fixed to each other and being at least partially superimposed, the first hull defining a seat member surface

(14), the second hull having the housing (10), the first and second hulls comprising respective shaped portions (15, 16) which face each other and which are formed so as to define in the mutually facing zone at least one recess (17, 18) configured to define at least one of the fixing seats (8, 9) and/or at least one receiving seat (19) for the retention means. A saddle (1) according to claim 1, wherein the ends (6, 7) and/or the retention means (11) are retained in the respective seats (8, 9, 19) by fastening the respective shaped portions (15, 16) against opposite surfaces of the same ends (6, 7) and/or the same retention means (11). A saddle (1) according to claim 1 or 2, comprising threaded connection means (20) which extend from the second hull (13) to the first hull (12) in an intermediate position between the fixing seats (8) of the rear ends of the frame and/or in the region of the fixing seat (9) of the front end of the frame. A saddle (1) according to claim 3, wherein the receiving seat (19) of the retention means is interposed between the fixing seats (6) of the rear ends of the frame, the threaded connection means (20) extending from the second hull (13) to the first hull (12) in an intermediate position between the receiving seat (19) and the fixing seats (6) of the rear ends of the frame. A saddle (1) according to any one of the preceding claims, wherein the retention means (11) comprise a tooth (21) and a resilient element (22). A saddle (1) according to claim 5, wherein the tooth (21) is hinged between the first hull and the second hull (12, 13). A saddle (1) according to claim 5 or 6, wherein the resilient element (22) is interposed between the tooth (21) and the first hull (12). A saddle (1) according to claim 5, 6 or 7, wherein the tooth (21) comprises a lever portion (23) for manoeuvring the tooth out of the housing (10) counter to the resilient element. A saddle (1) according to claim 8, wherein the tooth (21) is hinged in an intermediate position between the resilient element (22) and the lever portion (23) so as to form a lever of the first order.

10. A saddle (1) according to claim 8 or 9, wherein the lever portion (23) comprises a manoeuvring end (24) which extends transversely to a rear-front direction (X) for inserting the accessory into the housing (10).

11. A saddle (1) according to any one of the preceding claims, wherein the housing (10) comprises a guide (25) which extends longitudinally in a rear-front direction (X), the guide (25) being provided to receive, with an ability to slide in the rear-front direction (X), an extension piece of the accessory.

12. A saddle (1) according to any one of the preceding claims, comprising a covering (26) which is applied to the seat member surface (14), the first hull (12) comprising a peripheral edge (27) which is opposite the seat member surface, the covering (26) extending from the seat member surface (14) until it interferes with the peripheral edge (27), the first hull (12) being at least partially superimposed on the second hull (13) at the peripheral edge.

13. A saddle (1) according to any one of the preceding claims, wherein the rear ends (6) of the frame extend longitudinally into the rear fixing seats (8) over a first length (LI), the frame (5) and the second hull (13) being formed in such a manner that, without the first hull (12), the front end (7) of the frame can be inserted into the front fixing seat (9) over a second length (L2) which is greater than or at least equal to the first length (LI).

14. A kit (30) comprising the saddle (1) according to any one of the preceding claims and at least one accessory (100) comprising an extension piece (101) which is configured to be inserted into the housing (10) of the saddle. A kit (30) according to claim 14, wherein the saddle (1) is according to any one of claims 5 to 10 or according to any one of claims 11 to 13 when dependent on any one of claims 5 to 10, wherein the retention means (11) which are mounted on the housing comprise the tooth (21) and the resilient element (22), the retention means (11) and the extension piece (101) being formed so as to urge the tooth (21) out of the housing (10) counter to the resilient element (22) by interference between the tooth (21) and extension piece (101) when the extension piece is inserted into the housing (10) and to allow the tooth to engage with a recess (102) of the extension piece in order to retain the extension piece in the housing when the tooth (21) and recess (102) are located in a position of mutual alignment.