Seat element, seat back and seat cushion

Abstract

The present invention relates to a seat element comprising a cushion attached to a support frame, the cushion comprising a piece (16) of an entanglement of thermoplastic fibers forming loops welded together, the fibers being made of a polymer material, characterized in that the piece of fiber entanglement comprises at least one hole (18) and the support frame comprises at least one male fastener (26) disposed in the hole for attaching the piece of fiber entanglement to the support frame. Abstract figure: Figure 4

Description

Title of the invention: Seat element, seat back and seat cushion. Scope of the invention

[0001] This disclosure relates to a seating element comprising a support frame and a cushion attached to the support frame, the cushion being made from an entanglement of fibers forming a unit mesh without foam. Background

[0002] Seat cushions were traditionally made of polyurethane polymer foam and molded into profiles. Polyurethane foam cushions are satisfactory but can retain moisture in humid conditions. This can lead to discomfort for a vehicle seat occupant. Furthermore, polyurethane foam is not recyclable. It therefore seems desirable to limit the use of polyurethane in vehicle seat cushions. French patent application FR 3,139,025 relates to a cushion formed from a 3D entanglement of continuous fibers, arranged irregularly and forming loops welded together. This cushion is breathable and its manufacture requires less CO2. This entanglement of continuous fibers cannot be attached to a support frame using the same fastening system as foam.The purpose of this disclosure is therefore to propose a system for attaching a piece of fiber entanglement to a support frame. Summary

[0003] One object of this disclosure is to propose a seat element comprising a cushion subjected to a support frame, the cushion comprising a piece of an entanglement of thermoplastic fibers forming loops welded together, the fibers being made of a material comprising a polymer, characterized in that the piece of fiber entanglement comprises at least one hole and the support frame comprises at least one male fastener disposed in the hole for attaching the piece of fiber entanglement to the support frame.

[0004] Optionally, the fiber entanglement piece includes at least one plastic reinforcing frame surrounding at least one hole, the plastic reinforcing frame being obtained by compressing a portion of the fiber entanglement piece surrounding at least one hole.

[0005] Optionally, at least one plastic reinforcement frame includes a central convex part and a peripheral flat part.

[0006] Optionally, the male fastening element comprises at least two elastic branches extending apart towards the ends of the elastic branches, and two retaining blocks, each attached to one end of an elastic branch. Optionally, each retaining block comprises a first face attached to the elastic branch and a second face parallel and opposite to the first face; the first face having a larger surface area than the second face, the surface area of ​​the first face of the two retaining blocks being smaller than the surface area of ​​the hole.

[0007] Optionally, the male fastening element comprises a rod fixed to the support frame and a retaining block integral with one end of the rod, and in which the fiber entanglement piece comprises at least one radial slot opening into at least one hole.

[0008] Optionally, the retaining block has a first face integral with the elastic branching and a second face parallel and opposite to the first face; the first face having a larger surface area than the second face, the surface area of ​​the first face of the retaining block being smaller than the surface area of ​​the hole.

[0009] Optionally, the plastic reinforcement frame has a profile among a circular profile, an ovoid profile, a polygonal profile and a rectangular profile.

[0010] Optionally, at least one element among the hole and the portion of compressed fibers was made by compressing a part of the fiber entanglement piece by an ultrasonic sonotrode, the sonotrode vibrating at a frequency between 20 kHz and 70 kHz.

[0011] Optionally, the plastic reinforcement frame has a fiber density at least 20 times greater than the fiber density of the other part of the fiber entanglement.

[0012] The invention also relates to a seat back comprising a seat element designed according to any of the aforementioned characteristics, in which the support frame comprises a back frame having two opposing longitudinal edges, an upper edge and a lower edge, and in which each longitudinal edge of the back frame comprises at least one male fastening element.

[0013] Optionally, the backrest frame includes a support plate and an upper support structure, and wherein the upper support structure includes a central element and two lateral elements attached to the support plate, the central element and / or the lateral element including a rearward curved edge, and wherein the rearward curved edge of the central element and / or the rearward curved edge of the lateral element includes at least one male fastening element.

[0014] The invention also relates to a seat comprising a seat element designed according to any one of the aforementioned characteristics, wherein the support frame comprises a seat frame having an underside, the underside comprising an edge front, two opposing longitudinal edges and a rear edge, and in which each longitudinal edge of the seat frame includes at least one male fastening element.

[0015] Advantageously, the rear edge of the seat frame includes at least one male fastening element. Also advantageously, the front edge of the seat frame includes at least one male fastening element.

[0016] Optionally, at least a front part of the longitudinal edges of the seat frame are provided with a peripheral rim extending downwards, the peripheral rim comprising at least one male fastening element.

[0017] Advantageously, the front edge of the seat frame has a peripheral rim extending downwards, the peripheral rim comprising at least one male fastening element. Brief description of the figures

[0018] [Fig.1] is a perspective view of a seat comprising two seat elements according to this disclosure.

[0019] Fig. 1A is a perspective view of part of a folder frame;

[0020] [Fig.1B] is an enlargement of a part of [Fig.1]; the enlarged part is shown in [Fig.1].

[0021] Figure [Fig. 2] is a perspective view of an upper support structure of a element of the seat according to this disclosure.

[0022] Fig. 3 is a perspective view of a lateral part of the upper support structure illustrated in Fig. 2.

[0023] Figure 4 is a perspective view of an edge of an interlocking piece of fibers and a male fastening element according to a first embodiment of the disclosure, when the male fastening element is not attached to the fiber entanglement.

[0024] Fig. 5 is a cross-sectional view of a fiber entanglement piece and a male fastening element according to the first embodiment, when the male fastening element is attached to the fiber entanglement.

[0025] Fig. 6 is a perspective view of an edge of a fiber entanglement piece and a male fastening element according to a second embodiment of the disclosure, when the male fastening element is not attached to the fiber entanglement.

[0026] Figure 7 is a cross-sectional view of a piece of fiber entanglement and a male fastening element according to the second embodiment, when the male fastening element is attached to the fiber entanglement.

[0027] Fig. 8 is a perspective view of a first tooling element mounted on the ultrasonic sonotrode.

[0028] Fig. 9 is a cross-sectional view of the fiber entanglement, the first tooling element and the support during the pressing step.

[0029] Fig. 10 is a cross-sectional view of the fiber entanglement after the pressing step. Detailed description

[0030] In the various figures, the same reference numerals designate identical or similar elements. For the sake of simplicity, only the elements that are useful for understanding the described embodiment are illustrated in the figures and are described in detail below.

[0031] In the following description, when reference is made to terms qualifying an absolute position, such as the terms "front", "rear", "top", "bottom", "left", "right", etc., or to relative terms, such as the terms "above", "below", "superior", "lower", etc., or to orienting qualifiers, such as "horizontal", "vertical", etc., reference is made, unless otherwise indicated, to the orientation of the figures or of a vehicle seat in its normal position of use.

[0032] Figure 1 illustrates a motor vehicle seat 2. The motor vehicle seat 2 comprises a seat 4 on which a backrest 6 is mounted. The backrest pivots about a transverse axis relative to the seat. The backrest 6 comprises a backrest frame 8 and a backrest cushion 10 attached to the backrest frame. The seat 4 comprises a seat frame 12 and a seat cushion 14 attached to the seat frame.

[0033] This disclosure relates to a seat element 15, 17. The seat element 15, 17 comprises a cushion, of the type back cushion 10 and seat cushion 14, subjected to a support frame of the type back frame 8 and seat frame 12.

[0034] In the present patent application, a seat element 15 according to a first embodiment comprises the assembly of the backrest frame 8 and the backrest cushion 10.

[0035] Similarly, a seat element 17 according to a second embodiment comprises the assembly of the seat frame 12 and the seat cushion 14.

[0036] By cushion, we mean here a filling or padding.

[0037] With reference to [Fig. 4], the backrest cushion 10 and / or the seat cushion 14 comprise a piece 16 of a three-dimensional tangle of randomly arranged thermoplastic fibers. The fiber tangle forms loops that are heat-sealed and welded together. The fibers are made of a material comprising a thermoplastic polymer. The fiber tangle is a foam-free mesh. This fiber tangle and its manufacturing process are described in patent application FR 3 139. 025. The composition of the fiber entanglement and a typical density of the fiber entanglement are specified at the end of this description.

[0038] The back cushion 10 and / or the seat cushion 14 may be covered with a fabric or plastic lining not shown in the figures.

[0039] According to a first variant of the first embodiment illustrated in Figures 4 and 5, to attach the fiber entanglement piece 16 to the backrest frame 8 or the seat frame 12, the fiber entanglement piece 16 comprises at least one hole 18, and preferably a plurality of holes located along at least one edge of the fiber entanglement piece 16.

[0040] Preferably, at least one hole 18 is made by compressing a portion of the fiber tangle piece. This compression can, for example, be performed with an ultrasonic sonotrode as explained at the end of the specification. Preferably, to cut each hole in the fiber tangle piece 16, the sonotrode vibrates at a frequency between 20 kHz and 70 kHz.

[0041] The fiber entanglement piece 16 may include at least one plastic reinforcing frame 20 surrounding at least one hole. Advantageously, the plastic reinforcing frame is made by compressing a portion of the fiber entanglement piece 16. This compression causes heating and a change in the state of the fiber entanglement from a solid to a viscous state.

[0042] This compression can be performed with a sonotrode in the same way as for cutting the hole. An example of a method for cutting the hole and producing the plastic reinforcing frame is detailed at the end of the description. During compression, the fibers of the fiber entanglement melt and aggregate to form the plastic reinforcing frame that surrounds the hole.

[0043] The plastic reinforcement frame made by compression of a portion of the fiber entanglement has, for example, a fiber density at least 20 times greater than the fiber density of the other part of the fiber entanglement.

[0044] Alternatively, the fiber entanglement part 16 may include a reinforcing frame surrounding the hole, made of fabric, plastic, or leather. In this case, the reinforcing frame may be welded to the fiber entanglement by applying a sonotrode and a support between the fiber entanglement and the reinforcing frame.

[0045] Preferably, considering a radial direction with respect to the hole, the plastic reinforcing frame 20 comprises a convex central portion 22 and a flat peripheral portion 24. The flat peripheral portion 24 may be horizontal, as shown in Figures 4 and 5, or inclined. In these figures, both the flat peripheral portion 24 and the convex central portion 22 are annular. Alternatively, the portion The peripheral flat part 24 and / or the central convex part 22 may have another type profile, for example ovoid profile, polygonal profile or rectangular profile.

[0046] Alternatively, the central part 22 is flat and the peripheral part 24 is convex or rounded.

[0047] Alternatively, the plastic reinforcing frame 20 may have only one inclined portion. Preferably, the upper portion of the inclined portion is close to the hole 18.

[0048] The backrest frame 8 comprises at least one male fastener 26 and preferably a plurality of male fasteners. The male fasteners are arranged in holes to attach the thermoplastic fiber entanglement piece 16 to the backrest frame. To facilitate understanding of the specification, Figures 4 to 7 schematically represent only the male fastener without the backrest frame 8. In reality, the male fasteners are attached to the backrest frame, as shown in Figures 1, IA, and IB.

[0049] The male fastening element 26 comprises a barrel 28, at least two elastic branches 30, 32 extending in the continuation of the barrel 28 and two retaining blocks 34, 36 each integral with one end of an elastic branch.

[0050] The retaining blocks 34, 36 extend only along the peripheral face of the elastic branching to allow contact between the two elastic branches when they are constrained laterally.

[0051] Each retaining block 34, 36 comprises a first face 38 subjected to the elastic branching 30, 32 and a second face 40 parallel and opposite to the first face. Advantageously, the first face 38 has a larger surface area than the second face. The surface area of ​​the first face of both retaining blocks 34, 36 is less than the surface area other than the hole 18.

[0052] In the illustrated embodiment, the retaining blocks 34, 36 have the profile of a truncated half-cone. The truncated half-cone was obtained by sectioning a truncated cone along a plane passing through its central axis. The plane is perpendicular to the base of the truncated cone.

[0053] When a male fastener element is inserted into a hole 18, the elastic branches 30, 32 are brought into contact with each other to allow the peripheral retaining blocks 34, 36 to pass through the hole 18 of the thermoplastic fiber entanglement.

[0054] Once the male fastening element is in the hole 18, the two elastic branches move apart from each other, from the barrel towards the end of the branches. The two elastic branches extend to form a flared profile. The fiber entanglement piece 16 abuts against the first face 38 of the retaining blocks 34, 36.

[0055] Alternatively, the male fastening element 26 does not include a barrel. The male fastening element 26 only has the two elastic branches 30, 32 which move apart from each other, from the backrest frame towards the end of the elastic branches, and the two retaining blocks each attached to one end of an elastic branch.

[0056] According to a second variant of the first embodiment illustrated in figures 6 and 7, the male fixing element 42 comprises a rod 44 having one end fixed to the backrest frame 8 and a retaining block 46 integral with the other end of the rod.

[0057] The retaining block 46 has a first face 45 integral with the elastic branching and a second face 47 parallel and opposite to the first face 45. The first face 45 has a larger surface area than the second face 47. The surface area of ​​the first face 45 is smaller than the surface area of ​​the hole 18. In the illustrated example, the retaining block 46 has, for example, the profile of a truncated cone. It can have another profile, for example, a pyramidal profile.

[0058] In this embodiment, the fiber entanglement piece 16 comprises a hole 18 and two radial slots 50, 52. The radial slots 50, 52 open into the hole 18. The radial slots 50, 52 are located on either side of the hole 18. In particular, the radial slots 50, 52 extend here along a straight line passing through the center of the hole.

[0059] The hole 18 and the radial slots 50, 52 are made in the same way as the hole 18 illustrated in figures 4 and 5.

[0060] The fiber entanglement piece 16 also includes a plastic reinforcing frame 48. The two radial slots 50, 52 extend into the plastic reinforcing frame 48. The plastic reinforcing frame 48 is similar to the plastic reinforcing frame 20 illustrated in Figures 4 and 5. In particular, the plastic reinforcing frame 20 includes a convex central portion 22 and a flat peripheral portion 24.

[0061] The plastic reinforcement frame 48 is made in the same way as the plastic reinforcement frame 20 illustrated in Figures 4 and 5.

[0062] In Figures 4 to 7, the plastic reinforcing frames 20 and 48 are shown as being formed in the middle of the thickness of the part 16 of the thermoplastic fiber entanglement. Alternatively, the plastic reinforcing frame 20, 48 can be formed so as to be flush with the upper surface 49 or the lower surface 51 of the part 16 of the thermoplastic fiber entanglement.

[0063] The file frame 8 can be any kind of file frame, such as for example a file frame described in patent published under number EP 3128911.

[0064] The backrest frame 8 comprises two opposing longitudinal edges 53, an upper edge 55 and a lower edge 57.

[0065] The two opposite longitudinal edges 53 of the backrest frame include male fastening elements 26. Preferably, the upper edge 55 of the backrest frame includes additional male fastening elements 26. Preferably, the lower edge 57 of the backrest frame also includes male fastening elements 26.

[0066] In what follows, with reference to figures 1, IA and IB, a particular example of a backrest frame 8 comprising male fixing elements 26 is described in more detail.

[0067] With reference to [Fig. 1], the seat back 2 comprises a frame 54. The frame 54 essentially comprises two vertical uprights rigidly connected to a lower cross member and an upper cross member. The frame 54 supports a headrest and the backrest frame 8.

[0068] The backrest frame 8 includes a support plate 56 and an upper support structure 58 fixed to the upper part of the support plate 56. The support plate 56 generally carries comfort equipment such as vibration equipment or pneumatic equipment to perform a massage function, an actuator to perform a ventilation function and heating equipment.

[0069] The upper support structure 58 has a U-shaped profile. This U-shaped profile is contained in a vertical and transverse plane (y, z). Referring to [Fig. 1A], the upper support structure 58 comprises a central element 60 which is extended by two lateral elements 62 fixed to the support plate. The male fasteners 26 are fixed to the central element 60 and to the two lateral elements 62.

[0070] Preferably, the central element 60 and / or the lateral element 62 comprise a rearward curved edge 64. The rearward curved edge 64 is supported by and attached to the upper cross member of the frame 54. According to this embodiment, the inner face 65 of the rearward curved edge 64 comprises male fastening elements 26. The fiber entanglement piece 16 covers the outer face of the rearward curved edge 64 and is attached to the inner face 65 by one hand of the male fastening elements.

[0071] In the example illustrated in [Fig.1A], several male fastening elements 26 are regularly spaced on the inner face 65 of the rearward curved edge 64 of the central element 60. In the example illustrated in [Fig.1B], the inner face of the rearward curved edge 64 of the lateral element 62 includes male fastening elements 26.

[0072] Alternatively, a male fastening element may be located on the external face of the rearward curved edge 64.

[0073] The seat frame 12 can be any kind of seat frame.

[0074] In what follows, with reference to figures 2 and 3, an example of a seat frame 12 comprising male fixing elements 26 is described in more detail.

[0075] According to this example, the seat frame 12 may include a shell. The shell may be a molded part or a thermoformed part. For example, the seat frame is made of ABS (acrylonitrile butadiene styrene) and / or PC (polycarbonate) and / or P / E (polypropylene / polyethylene copolymer). The underside 67 of the seat frame 12 is shown in [Fig. 2]. The underside 67 of the seat frame includes a front edge 66, two longitudinal edges 68, and a rear edge 70.

[0076] At least one male fastener 26 is located on each longitudinal edge 68 of the hull. At least one male fastener 26 is located on the rear edge 70 of the hull.

[0077] In the illustrated example, the front edge 66 and a front portion of the longitudinal edges 68 are provided with a downward-sloping peripheral rim 72. The male fasteners 26 are attached to the inner face 74 of the peripheral rim. The male fasteners 26 are evenly spaced along the peripheral rim. The male fasteners 26 extend perpendicularly to the inner face of the peripheral rim. The male fasteners 26 can also be attached to the outer face of the peripheral rim.

[0078] For example, two male fastening elements 26 are arranged on the peripheral rim 72 of each longitudinal edge. For example, between two and four male fastening elements 26 are arranged on the peripheral rim 72 of the front edge 66 of the shell.

[0079] According to an unrepresented variant, the inclined peripheral rim extends along the longitudinal edges and the male fastening elements are regularly distributed along the longitudinal edges of the peripheral rim.

[0080] According to an unrepresented variant, the rear edge 70 of the shell also includes an inclined peripheral rim and the male fastening elements are regularly distributed along the inclined peripheral rim of the rear edge.

[0081] The method for preparing the hole and optionally the plastic reinforcing frame includes pressing the fiber tangle in one or more local areas using a sonotrode. The fiber tangle is also pressed to obtain the plastic reinforcing frame. Thus, the plastic reinforcing frame 20, 48 is made from a portion of the densified and stiffened fiber tangle.

[0082] With reference to Figures 8 to 10, during pressing, a tooling element 100 mounted on the sonotrode and a support 102 come from either side of the part 16 of the fiber entanglement to compress and weld the fibers, and as schematically illustrated in [Fig.9].

[0083] In particular, as illustrated in [Fig. 8], the first tooling element or support 102 comprises:

[0084] - opposing surfaces forming, by complementary profile, an annular groove 104 ensuring the cutting of the hole 18 and the molding of the convex central part 22,

[0085] - a peripheral edge 106, extending around the annular groove 104, for prepare the flat peripheral part 24.

[0086] The process may include a step of removing the remaining material on the hole 18, if there is still a veil of material.

[0087] During the pressing step, the sonotrode and the support are positioned on either side of the fiber entanglement. The sonotrode is vibrated at a frequency typically between 20 kHz and 40 kHz to weld the thermoplastic fibers together and form the plastic reinforcement frame 20, 48.

[0088] The pressing step is intended to form the hole and the plastic reinforcement frame in the thermoplastic material of the fibers. After compression, the fibers are fully compressed and welded together.

[0089] The central convex part 22 of the reinforcing frame, in particular when circular, may have the following dimensions:

[0090] - an outer diameter Dext between 10 mm and 18 mm,

[0091] - an inner diameter Dint between 3 mm and 6 mm,

[0092] - a height h between 3 mm and 8 mm.

[0093] The hole 18 of the reinforcing frame can have the same profile as the convex central part, namely a circular profile, an ovoid profile or a polygonal profile.

[0094] According to one embodiment, the process may include an initial thermoforming step of part 16 of the fiber entanglement.

[0095] Specifically, the thermoplastic polymer is chosen from the group consisting of a polyester, such as PET (polyethylene terephthalate), PTT (polytrimethylene terephthalate), or PBT (polybutylene terephthalate). For example, the fiber composition includes:

[0096] - 95% to 99% by weight of a first polymer from the polyester family, such as PBT (polybutylene terephthalate),

[0097] - 1% to 5% by weight of a second polymer from the polyester family, such as PTT (polytrimethylene terephthalate) or another polyester.

[0098] Outside the plastic reinforcement frame, the fiber entanglement can have an apparent density of between 20 kg / m3 and 70 kg / m3, in particular between 45 kg / m3 and 60 kg / m3, preferably between 35 and 55 kg / m3.

Claims

Demands

1. Seating element (15, 17) comprising a cushion (10, 14) attached to a support frame (8, 12), the cushion (10, 14) comprising a piece (16) of an entanglement of thermoplastic fibers forming loops welded together, the fibers being made of a material comprising a polymer, characterized in that the piece of fiber entanglement comprises at least one hole (18) and the support frame (8, 12) comprises at least one male fastener (26, 42) disposed in the hole for attaching the piece of fiber entanglement to the support frame.

2. Seat element (15, 17) according to claim 1, wherein the fiber entanglement piece (16) comprises at least one plastic reinforcing frame (20, 48) surrounding at least one hole (18), the plastic reinforcing frame being obtained by compressing a portion of the fiber entanglement piece surrounding at least one hole (18).

3. Seat element (15, 17) according to claim 2, wherein at least one plastic reinforcement frame (20, 48) comprises a convex central part (22) and a flat peripheral part (24).

4. Seat element (15, 17) according to any one of claims 2 and 3, wherein the male fixing element (26, 42) comprises at least two elastic branches (30, 32) moving apart from each other, towards the end of the elastic branches, and two retaining blocks (34, 36) each integral with one end of an elastic branch.

5. Seat element (15, 17) according to claim 4, wherein each retaining block (34, 36) comprises a first face (38) subjected to the elastic branching (30, 32) and a second face (40) parallel and opposite to the first face; the first face (38) having a larger surface area than the second face (40), the surface area of ​​the first face (38) of the two retaining blocks being smaller than the surface area of ​​the hole (18).

6. Seat element (15, 17) according to any one of claims 2 and 3, wherein the male fastening element (42) comprises a rod (44) fixed to the support frame (8, 12) and a retaining block (46) integral with one end of the rod, and wherein the part (16) the entanglement of fibers includes at least one radial slit (50, 52) opening into at least one hole (18).

7. Seat element (15, 17) according to claim 6, wherein the retaining block (46) has a first face (45) integral with the stem and a second face (47) parallel and opposite to the first face; the first face having a larger surface area than the second face, the surface area of ​​the first face of the retaining block (46) being smaller than the surface area of ​​the hole (18).

8. Seat element (15, 17) according to any one of claims 2 to 7, wherein the plastic reinforcement frame (20, 48) has a profile among a circular profile, an ovoid profile, a polygonal profile and a rectangular profile.

9. Seating element (15, 17) according to claim 2 to 8, wherein at least one element among the hole and the portion of compressed fibers was made by compressing a portion of the fiber entanglement piece (16) by an ultrasonic sonotrode, the sonotrode vibrating at a frequency between 20 kHz and 70 kHz.

10. Seat element (15, 17) according to any one of claims 2 to 9, wherein the plastic reinforcement frame (20, 48) has a fiber density at least 20 times greater than the fiber density of the other part of the fiber entanglement.

11. Seat back (6) comprising a seat element (15) designed according to any one of claims 1 to 10, wherein the support frame comprises a back frame (8) having two opposing longitudinal edges (53), an upper edge (55) and a lower edge (57) and wherein each longitudinal edge (53) of the back frame comprises at least one male fastening element (26, 42).

12. Seat backrest (6) according to claim 11, wherein the backrest frame (8) comprises a support plate (56) and an upper support structure (58), and wherein the upper support structure (58) comprises a central element (60) and two side elements (62) attached to the support plate, the central element (60) and / or the side element (62) comprising a rearward curved edge (64), and wherein the rearward curved edge (64) of the central element (60) and / or the rearward curved edge (64) of the side element (62) comprises at least one male fastening element (26).

13. Seat (4) comprising a seat element (17) designed according to any one of claims 1 to 10, wherein the

14. support frame (12) includes a seat frame having an underside (67), the underside (67) comprising a front edge (66), two opposing longitudinal edges (68) and a rear edge (70), and in which each longitudinal edge (68) of the seat frame includes at least one male fastening element (26, 42). Seat (4) according to claim 13, wherein at least a front part of the longitudinal edges (68) of the seat frame are provided with a peripheral rim (72) extending downwards, the peripheral rim (72) comprising at least one male fastening element (26, 42).

Images