Suspension organs

Abstract

A suspension component for a road vehicle enabling the conversion of at least a portion of the vibrations and / or mechanical stresses into electricity, and a method for manufacturing such a suspension component, the suspension component comprising at least one suspension element or at least one interface element, configured to participate in the attachment of at least one suspension element of the vehicle, and at least one continuous two-dimensional sheet (10), integrated into or covering a surface of the suspension element or the interface element, in which said at least one two-dimensional sheet (10) comprises at least one piezoelectric layer (20), comprising piezoelectric fibers collectively oriented in a common direction so as to convert into electricity at least a portion of the vibrations and / or mechanical stresses experienced by the suspension element (1) during the operation of the vehicle, and a collector layer (30),electrically conductive, covering the piezoelectric layer (20) so as to collect the electricity produced by the piezoelectric fibers. Fig. 2.

Description

Title of the invention: Suspension member Technical field

[0001] The present disclosure relates to a suspension member for a road vehicle making it possible to convert at least part of the vibrations and / or mechanical stresses into electricity, as well as a method of manufacturing such a suspension member. Prior art

[0002] Vehicle suspension elements, including in particular suspension coil springs and anti-roll stabilizer bars, are designed to exhibit elastic behavior to reduce the jolts and vibrations felt within the vehicle cabin. These suspension elements therefore undergo significant deformations and vibrations during operation. This is also the case for the interface elements used to attach these suspension elements to the chassis or running gear of the vehicle.

[0003] Naturally, these deformations and vibrations normally cause significant energy losses which are dissipated mainly by friction. It is estimated that, for a thermal vehicle, 3 to 15% of the energy developed in the engine is thus dissipated in the vehicle's suspension, with losses even rising to 8 to 39% if we only count the mechanical energy actually produced by the engine, i.e. if we exclude losses linked to the exhaust (33%) and engine cooling (29%).

[0004] It would therefore be desirable to be able to recover at least part of this energy dissipated in the suspension. To this end, several solutions have already been proposed in the past but they are not fully satisfactory.

[0005] For example, some solutions aim to install an electric generator at the level of the suspension coil spring or its shock absorber, for example by converting the hydraulic pressure of the shock absorber into torque in a hydraulic motor or by converting the linear displacement of the spring or shock absorber into rotation using a rack and pinion. However, these solutions require the addition of heavy and bulky elements, which ultimately penalizes the expected gain from energy recovery.

[0006] Other solutions propose to recover this displacement energy by induction, for example by installing a coil, secured to one end of the spring, around a magnet, secured to the other end of the spring. However, these solutions are also bulky and difficult to implement in practice.

[0007] Finally, other solutions still propose to install one or more piezoelectric elements on the suspension element or on an element crushed by the latter. However, to date, the known solutions implementing piezoelectric elements do not allow a truly usable current to be produced. Indeed, in most known configurations, the piezoelectric element is installed punctually and therefore only generates a small potential difference, and only when it is stressed in the right direction. These piezoelectric elements are therefore generally relegated to compression sensor functions without any real energy recovery potential.

[0008] There is therefore a real need for a suspension member making it possible to convert at least part of the vibrations and / or mechanical stresses into electricity, as well as a method for manufacturing such a suspension member, and which are free, at least in part, from the drawbacks inherent in the aforementioned configurations. Statement of the invention

[0009] The present disclosure relates to a suspension member for a road vehicle, comprising at least one suspension element, exhibiting elastic behavior so as to act as a suspension spring during operation of the vehicle, or at least one interface element, configured to participate in the attachment of at least one suspension element of the vehicle exhibiting elastic behavior so as to act as a suspension spring during operation of the vehicle, and at least one two-dimensional, continuous sheet, integrated into the suspension element or the interface element or covering at least one interface surface of the suspension element or the interface element, said interface surface being intended to be in contact with another component of the vehicle during operation of the vehicle, wherein said at least one two-dimensional sheet comprises at least: - a piezoelectric layer, comprising piezoelectric fibers collectively oriented in a common direction so as to convert into electricity at least part of the vibrations and / or mechanical stresses experienced by the suspension element during operation of the vehicle, and - an electrically conductive collecting layer covering the piezoelectric layer so as to collect the electricity produced by the piezoelectric fibers.

[0010] Thanks to the proposed configuration, in which piezoelectric fibers are distributed and oriented uniformly within a layer of a two-dimensional sheet, it is possible to recover on average a satisfactory electrical voltage and recoverable. Indeed, since piezoelectric fibers are distributed throughout the sheet, the probability that at any time a significant number of fibers are stressed in the right direction, and therefore generate a potential difference, increases greatly. The recoverable potential difference, and its stability over time, increases even more with the surface covered by the sheet, and therefore with the number of piezoelectric fibers present. In particular, by placing such a sheet continuously enclosing piezoelectric fibers over a large surface, the recovery of different types of stresses is encouraged, not being exerted with the same amplitude depending on the area considered.

[0011] In particular, since the collector layer is electrically connected to all of the piezoelectric fibers of the piezoelectric layer, thus forming an upper electrode, it is possible to capture and amplify, depending on the surface area of ​​the sheet and therefore the number of piezoelectric fibers, the vibrations which are usually difficult to exploit due to their low amplitude.

[0012] Furthermore, such a piezoelectric sheet is easy to implement and can cover a large surface area without increased difficulty. Indeed, the piezoelectric sheet can be prepared upstream and simply installed during assembly of the suspension member; it can also be directly integrated into the suspension element or the interface element during its manufacture.

[0013] In particular, such a configuration adds very little mass and benefits from minimal bulk: it is thus possible to install such a piezoelectric sheet in an already existing suspension member design without particularly significant adaptation. Such a sheet can even play a role in protecting the suspension element or the interface element and then replace a protective coating usually provided on this element.

[0014] In the present disclosure, it is understood that a two-dimensional sheet is a sheet extending in two orthogonal directions, a main direction and a transverse direction, the thickness of the two-dimensional sheet being negligible compared to each of these two directions. It is further understood that, since the sheet can be flexible, these two directions of extension can be curvilinear. In particular, it is understood that one of these two directions can close on itself and thus form a loop: this is notably the case when the sheet forms a tubular sheath, the transverse direction of the sheet closing on itself, or when the sheet forms a ring, the main direction of the sheet closing on itself.

[0015] In this disclosure, it is understood that the piezoelectric fibers are collectively oriented in a given direction when, on average, the fibers are oriented in that direction and no more than 10% of the fibers individually deviate more than 10° from that direction.

[0016] In certain embodiments, the piezoelectric fibers have a length of less than 500 pm, possibly less than 70 pm. In particular, these length ranges make it possible to reduce the risk of delamination of the layers of the two-dimensional sheet, such delamination being able to occur when the piezoelectric fibers are too long.

[0017] In some embodiments, the piezoelectric fibers have a diameter less than 100 nm, possibly less than 700 nm.

[0018] In some embodiments, the piezoelectric fibers comprise lead zirconate titanate (PZT), polyvinyl fluoride (PVF), polyvinylidene fluoride (PVDF), polyvinyl chloride (PVC), or barium titanate fibers. For example, the piezoelectric layer may comprise arrays of barium titanate nanowires. Optionally, all of the piezoelectric fibers are made of the same material.

[0019] In some embodiments, the orientation of the piezoelectric fibers is orthogonal to the collector layer. This orientation may also be orthogonal to the substrate.

[0020] In some embodiments, the thickness of the piezoelectric layer is greater than 70 pm, possibly greater than 500 pm.

[0021] In the present disclosure, unless otherwise specified, when it is indicated that a parameter is greater than, or less than, a given value, this is understood to include the case where said parameter is equal to the given value.

[0022] In some embodiments, the thickness of the piezoelectric layer is less than 500 pm, possibly less than 70 pm.

[0023] In some embodiments, the collector layer comprises phosphate crystals. Such phosphate crystals greatly improve the adhesion of an optional polymer layer to the collector layer.

[0024] In some embodiments, the collector layer comprises at least one metallic element among zinc (Zn), manganese (Mn), copper (Cu) and nickel (Ni). Such a metallic element makes it possible to promote the electrical conduction of the electrical layer.

[0025] In some embodiments, the thickness of the collector layer is greater than 5 μm, possibly greater than 20 μm.

[0026] In some embodiments, the thickness of the collector layer is less than 50 μm, possibly less than 25 μm.

[0027] In certain embodiments, the suspension member comprises a first electrically conductive connection cable, electrically connected to the collector layer. It may in particular be glued to the collector layer.

[0028] In some embodiments, the suspension member comprises a plurality of piezoelectric layers, each comprising piezoelectric fibers collectively oriented in a common direction, an electrically conductive interface layer being interposed between each piezoelectric layer. In particular, all the piezoelectric layers may be identical and oriented in the same direction. In such a case, the collector layer covers the uppermost piezoelectric layer and the substrate, or a possible base layer, forms the base of the lowest piezoelectric layer. Superimposing several piezoelectric layers in series in this way makes it possible to increase the voltage produced by the two-dimensional sheet.

[0029] In some embodiments, a piezoelectric layer extends directly from the substrate formed by the suspension element or the interface element, this substrate being electrically conductive. Such a configuration makes it possible to use the substrate itself as a lower electrode connected to the set of piezoelectric fibers of the lowest piezoelectric layer.

[0030] In certain embodiments, the suspension member comprises a second electrically conductive connection cable electrically connected to the substrate. It may in particular be welded or brazed to the substrate.

[0031] In some embodiments, the suspension member comprises an electrically conductive base layer, a piezoelectric layer extending from the base layer. Such a configuration makes it possible to form a lower electrode connected to all of the piezoelectric fibers of the lowest piezoelectric layer, in particular when the substrate is not conductive.

[0032] In some embodiments, the suspension member comprises a second electrically conductive connection cable electrically connected to the base layer. It may in particular be glued, welded or brazed to the base layer.

[0033] In certain embodiments, the suspension member comprises an electrically insulating protective layer covering the collector layer. Such a protective layer makes it possible to electrically insulate the assembly in order to reduce the risk of short circuit. This protective layer can also protect the suspension element or the interface element against mechanical, physical and / or chemical attacks from its environment. In particular, this protective layer can play a role in protecting against corrosion and / or against impacts such as impacts from gravel when the vehicle is moving.

[0034] In certain embodiments, the protective layer is made of polymeric material, for example epoxy.

[0035] In some embodiments, the thickness of the protective layer is greater than 120 μm.

[0036] In some embodiments, the two-dimensional web takes the form of a sheath surrounding the suspension element or the interface element. Such a sheath can then also play a role in protecting the suspension element or the interface element.

[0037] In some embodiments, the two-dimensional web is deposited, layer by layer, directly onto the suspension element or the interface element.

[0038] In certain embodiments, the two-dimensional sheet is attached, preferably by gluing, to the suspension element or the interface element.

[0039] In some embodiments, the suspension element or the interface element is overmolded onto the two-dimensional web.

[0040] In certain embodiments, the two-dimensional sheet is interposed between two components of the interface element, for example between a frame and an elastomeric layer in contact with the suspension element.

[0041] In some embodiments, the suspension element is a coil spring, and the at least one two-dimensional web covers at least a portion of the outer surface of the coil spring.

[0042] In certain embodiments, said at least one two-dimensional sheet covers at least one end portion of the helical spring, preferably over at least 5 cm, more preferably over at least 10 cm. The end portion of the helical spring is in fact the portion which undergoes the most stress, in particular because it bears against a rigid element of the vehicle.

[0043] In certain embodiments, said at least one two-dimensional sheet covers at least a middle portion of the helical spring, preferably over at least 5 cm, more preferably over at least 10 cm. The active turns of the spring, located at a distance from the ends and therefore benefiting from greater freedom of movement, are in fact the turns which undergo the most vibrations.

[0044] In some embodiments, said at least one two-dimensional sheet covers the entire external surface of the coil spring.

[0045] In some embodiments, the suspension element is a stabilizer bar, and said at least one two-dimensional web covers at least a portion of the surface of the stabilizer bar intended to be held by a bearing of the vehicle.

[0046] In some embodiments, the interface element is a bearing configured to be mounted around a stabilizer bar of the vehicle.

[0047] In certain embodiments, said at least one two-dimensional sheet covers at least a portion of the internal surface of the bearing, intended to hold the stabilizer bar.

[0048] In certain embodiments, said at least one two-dimensional sheet is interposed between two components of the bearing, preferably between a frame and an elastomer layer in contact with the stabilizer bar.

[0049] In some embodiments, the bearing comprises at least one flange having a cradle portion and two fixing lugs, and said at least one two-dimensional sheet covers at least the cradle portion, and preferably also the inner surface of the fixing lugs.

[0050] In some embodiments, the bearing comprises at least one plywood, separate from the flange and configured to be attached against the bracket, and at least one second two-dimensional sheet covers at least a portion of the inner surface of the plywood.

[0051] In some embodiments, the suspension element comprises at least one attachment eyelet, and said at least one two-dimensional web covers at least a portion of the inner surface of the attachment eyelet. In such a case, the suspension element may, for example, be a stabilizer bar or a leaf spring.

[0052] In some embodiments, the interface element is a bearing configured to be mounted in an eyelet of a suspension element of the vehicle, for example a leaf spring or a stabilizer bar.

[0053] In some embodiments, said at least one two-dimensional sheet covers at least a portion of the inner surface or the outer surface of the bearing.

[0054] In certain embodiments, said at least one two-dimensional sheet is interposed between two components of the bearing, preferably between a frame and an elastomer layer.

[0055] In some embodiments, the interface member is a coil spring support member configured to be mounted to one end of a coil spring and locked to a cup.

[0056] In certain embodiments, said at least one two-dimensional sheet covers at least a portion of the external surface of the support element, intended to be in contact with the cup.

[0057] In certain embodiments, said at least one two-dimensional sheet is interposed between two components of the support element, preferably between a support portion in contact with the helical spring and a base portion in contact with the cup.

[0058] The present disclosure also relates to a method of manufacturing a suspension member for a road vehicle, comprising the following steps: providing a substrate, intended to form a suspension element, exhibiting elastic behavior so as to act as a suspension spring during operation of the vehicle, or an interface element, configured to participate in the fixing of at least one suspension element of the vehicle exhibiting elastic behavior so as to act as a suspension spring during operation of the vehicle, depositing a piezoelectric layer, comprising piezoelectric fibers, on the substrate or on a base layer extending over the substrate, polarizing the piezoelectric fibers so that they collectively orient in a common direction, depositing an electrically conductive collector layer on the piezoelectric layer.

[0059] Such a method then makes it possible to obtain a suspension member as presented above, with all the advantages offered by the latter.

[0060] In certain embodiments, the deposition of the piezoelectric fiber layer is carried out by powdering, spraying or dipping in a fluidized bath.

[0061] In certain embodiments, the method comprises a step of shot blasting the substrate or the base layer. This shot blasting step can take place before and / or after the step of depositing the piezoelectric layer. Carried out before the deposition of the piezoelectric fibers, the reliefs formed by the shot blasting make it possible to promote the adhesion of the fibers during their deposition; carried out after the deposition of the piezoelectric fibers, the impacts caused by the shot blasting reinforce the fixing of the fibers on the substrate or the base layer.

[0062] In certain embodiments, the substrate has, after the shot peening step, a roughness Rt of between 5 and 30 pm, preferably between 10 and 20 pm.

[0063] In certain embodiments, the deposition of the collector layer is carried out by phosphating, for example in a bath. Such a step also makes it possible to include phosphate crystals in the collector layer, which will promote the adhesion of a possible polymer layer on the collector layer.

[0064] In certain embodiments, the method comprises a step of depositing a protective, electrically insulating layer on the piezoelectric layer. Such a protective layer makes it possible to electrically insulate the assembly in order to reduce the risk of short circuit. This protective layer can also protect the suspension element or the interface element against mechanical, physical and / or chemical attacks from its environment. In particular, this protective layer can play a role in protecting against corrosion and / or against impacts such as impacts from gravel when the vehicle is moving.

[0065] In certain embodiments, the deposition of the protective layer is carried out by powder coating. During such a powder coating step, the piezoelectric fibers are polarized between the substrate and the protective layer: this powder coating step can then constitute the step of polarization of the piezoelectric fibers without a separate polarization step being necessary.

[0066] In some embodiments, the method comprises a connection step during which a first electrically conductive connection cable is connected to the collector layer and a second electrically conductive connection cable is connected to the substrate or base layer. In particular, this connection step can be carried out before the protective layer deposition step: in this way, the protective layer can also protect these electrical connections.

[0067] In some embodiments, the method includes a step of exposing the substrate or base layer before the connecting step. For example, the piezoelectric layer and the collector layer may be scratched to expose the substrate or base layer. This then facilitates the connecting step.

[0068] The above-mentioned features and advantages, as well as others, will become apparent from the following detailed description of examples of suspension members and methods of manufacturing such a suspension member. This detailed description refers to the accompanying drawings. Brief description of the drawings

[0069] The attached drawings are schematic and are intended primarily to illustrate the principles of the disclosure.

[0070] In these drawings, from one figure to another, identical elements (or parts of elements) are identified by the same reference signs. In addition, elements (or parts of elements) belonging to different embodiments but having a similar function are identified in the figures by numerical references incremented by 100, 200, etc.

[0071] [Fig.l] [Fig.l] is a side view of a first example of a suspension member comprising a coil spring.

[0072] [Fig.2] [Fig.2] is a sectional diagram of this first example of a suspension member.

[0073] [Fig.3] [Fig.3] is a microphotograph of a layer of piezoelectric fibers.

[0074] [Fig.4] [Fig.4] is a sectional diagram of a second example of a suspension member.

[0075] [Fig.5] [Fig.5] is a sectional diagram of a third example of a suspension member. Description of the embodiments

[0076] In order to make the disclosure more concrete, examples of suspension members and manufacturing methods are described in detail below, with reference to the accompanying drawings. It is recalled that the invention is not limited to these examples.

[0077] [Fig.l] represents an example of a suspension member for a vehicle 1 comprising a helical spring 2 and a piezoelectric sheet 10 taking the form of a sheath surrounding the helical spring 2.

[0078] [Fig.2] schematically represents in section this same suspension member 1. The helical spring 2 forms the substrate. The piezoelectric sheet 10 then comprises a piezoelectric layer 20, deposited on the substrate 2, a collector layer 30, covering the piezoelectric layer 20, and a protective layer 40, covering the collector layer 30. A first connection cable 51 is connected to the collector layer 30 while a second connection cable 52 is connected to the substrate 2.

[0079] The helical spring 2 is here made of metal, more precisely of steel.

[0080] The piezoelectric layer 20 is formed of piezoelectric fibers 21, for example lead zirconate titano (PZT) fibers, the average length of which is here equal to 50 pm and the average diameter of which is here equal to 500 nm. The piezoelectric layer 20 then has a thickness equal to 70 pm.

[0081] The collecting layer 30 comprises phosphate crystals as well as metallic elements, in particular zinc, manganese and nickel. The collecting layer 30 is therefore electrically conductive. In this example, the thickness of the collecting layer 30 is equal to 15 μm.

[0082] The protective layer 40 is made of electrically insulating polymer material, for example epoxy. In this example, the thickness of the protective layer 40 is equal to 120 μm.

[0083] An example of a method for manufacturing this suspension member 1 will now be described.

[0084] A helical spring 2 is first provided or manufactured according to a known method, the latter forming the substrate.

[0085] The substrate 2 is then shot-peened in order to induce internal residual stresses to increase the life of the helical spring. At the same time, a roughness Rt of 15 pm on average is imprinted on the surface.

[0086] Piezoelectric fibers 21 are then deposited on the substrate 2 by powder coating so as to form the piezoelectric layer 20. [Fig. 3] illustrates such piezoelectric fibers 21 deposited on a substrate 2.

[0087] The assembly formed by the substrate 2 and the piezoelectric layer 20 then undergoes a chemical surface treatment step for anti-corrosion protection of the phosphating type so as to form the conductive collector layer 30. In other examples, this step can also be carried out by a chemical conversion operation in an Oxsilan (registered trademark) bath which generates a very thin and very adherent layer to the piezoelectric layer 20.

[0088] The first connection cable 51 is then glued to a first portion of the collector layer 30 in order to electrically connect the first connection cable 51 with the collector layer 30. Furthermore, a second portion of the collector layer 30 is scraped, as well as the portion of the piezoelectric layer 20 located just below, in order to locally expose the substrate 2. The second connection cable 52 can then be soldered onto the substrate 2 in the area that has been exposed in order to electrically connect the second connection cable 52 with the substrate 2.

[0089] A precursor powder is then deposited on the collector layer 30 by powdering. During this powdering step, the precursor powder is positively charged while the substrate 2 is maintained at a negative potential. This potential difference results in the polarization of the piezoelectric fibers 21 of the piezoelectric layer 20 which are collectively oriented according to the potential gradient, therefore orthogonally to the substrate 2 and to the collector layer 30. The assembly is then baked in order to crosslink the precursor powder, thus resulting in the protective layer 40.

[0090] The suspension member 1 is thus finally obtained. Therefore, when the suspension member 1 undergoes deformations or vibrations, these deformations or vibrations lead to modification of the orientation and / or the length of the piezoelectric fibers 21, which generates an electrical potential difference between the collector layer 30, which constitutes a first electrode, and the substrate 2, which constitutes a second electrode. The piezoelectric fibers 21 being all connected in parallel between the collector layer 30 and the substrate 2, the potential difference generated between these two electrodes is significant and can therefore be recovered in an exploitable manner by the connection cables 51 and 52.However, since this electrical voltage is by construction highly fluctuating over time, depending on the amplitude of the stresses and vibrations experienced, it is preferable to connect an electrical rectifier downstream of the piezoelectric sheet 10 in order to smooth out the fluctuations in the voltage generated by the piezoelectric sheet 10.

[0091] [Fig.4] schematically represents in section a second example of suspension member 101. In this second example, the substrate 102 is no longer conductive and can therefore no longer form an electrode connecting the lower ends of the piezoelectric fibers of the piezoelectric layer 120.

[0092] The piezoelectric sheet 110 then comprises, in addition to a piezoelectric layer 120, a collector layer 130 and a protective layer 140, all similar to those of the first example, a base layer 160, electrically conductive, deposited on the substrate 102 and on which the piezoelectric layer 120 is deposited. Thus, this base layer 160 can form a lower electrode connecting the lower ends of the piezoelectric fibers of the piezoelectric layer 120. The second connection cable 152 is then connected to this base layer 160.

[0093] [Fig.5] schematically represents in section a third example of suspension member 201. This third example is similar to the first example except that the piezoelectric sheet 210 here comprises two piezoelectric layers 221, 222.

[0094] Each piezoelectric layer 221, 222 is completely analogous to the piezoelectric layer 20 of the first example. An intermediate layer 229, conductive electric, is interposed between the two piezoelectric layers 221, 222: the intermediate layer 229 is therefore connected, on the one hand, to the upper ends of the piezoelectric fibers of the lower piezoelectric layer 221 and to the lower ends of the piezoelectric fibers of the second upper piezoelectric layer 222. The substrate 202, the collector layer 230 and the protective layer 240 are for their parts analogous to those of the first example.

[0095] In this way, the piezoelectric sheet 210 has two piezoelectric layers 221, 222 connected in series, which increases the recoverable voltage between the substrate 202, forming the lower electrode, and the collector layer 230, forming the upper electrode. In this third example, two piezoelectric layers 221, 222 are provided but a larger number of piezoelectric layers could be provided, by inserting an intermediate layer between each piezoelectric layer.

[0096] Although the present invention has been described with reference to specific exemplary embodiments, it is obvious that modifications and changes may be made to these examples without departing from the general scope of the invention as defined by the claims. In particular, individual features of the various illustrated / mentioned embodiments may be combined in additional embodiments. Therefore, the description and drawings should be considered in an illustrative rather than restrictive sense.

[0097] It is also obvious that all the characteristics described with reference to a method are transposable, alone or in combination, to a device, and conversely, all the characteristics described with reference to a device are transposable, alone or in combination, to a method.

Claims

Claims

1. Suspension member for a road vehicle, comprising at least one suspension element (2), having an elastic behavior so as to act as a suspension spring during operation of the vehicle, or at least one interface element, configured to participate in the fixing of at least one suspension element of the vehicle having an elastic behavior so as to act as a suspension spring during operation of the vehicle, and at least one two-dimensional sheet (10), continuous, integrated in the suspension element (2) or the interface element or covering at least one interface surface of the suspension element (2) or the interface element, said interface surface being intended to be in contact with another member of the vehicle during operation of the vehicle, in which said at least one two-dimensional sheet (10) comprises at least: - a piezoelectric layer (20),comprising piezoelectric fibers (21) collectively oriented in a common direction so as to convert into electricity at least part of the vibrations and / or mechanical stresses undergone by the suspension element (1) during operation of the vehicle, and - an electrically conductive collector layer (30) covering the piezoelectric layer (20) so as to collect the electricity produced by the piezoelectric fibers (21).,

2. A suspension member according to claim 1, wherein the orientation of the piezoelectric fibers (21) is orthogonal to the collector layer (30).

3. The suspension member of claim 1 or 2, wherein the collecting layer (30) comprises phosphate crystals.

4. A suspension member according to any one of claims 1 to 3, comprising a plurality of piezoelectric layers (221, 222), each comprising piezoelectric fibers collectively oriented in a common direction, an electrically conductive interface layer (229) being interposed between each piezoelectric layer (221, 222).

5. Suspension member according to any one of claims 1 to 4, wherein a piezoelectric layer (20) extends directly from the substrate (2) formed by the suspension element or the interface element, this substrate (2) being electrically conductive.

6. Suspension member according to any one of claims 1 to 5, comprising an electrically insulating protective layer (40) covering the collector layer (30).

7. A suspension member according to any one of claims 1 to 6, wherein the two-dimensional sheet (10) takes the form of a sheath surrounding the suspension element (2) or the interface element.

8. A method of manufacturing a suspension member for a road vehicle, comprising the following steps: providing a substrate (2), intended to form a suspension element, having an elastic behavior so as to act as a suspension spring during operation of the vehicle, or an interface element, configured to participate in the fixing of at least one suspension element of the vehicle having an elastic behavior so as to act as a suspension spring during operation of the vehicle, depositing a piezoelectric layer (20), comprising piezoelectric fibers (21), on the substrate (2) or on a base layer extending over the substrate, polarizing the piezoelectric fibers (21) so that they are collectively oriented in a common direction, depositing an electrically conductive collector layer (30) on the piezoelectric layer (20).

9. Method according to claim 8, in which the deposition of the piezoelectric layer (20) is carried out by powdering, spraying or quenching in a fluidized bath.

10. A method according to claim 8 or 9, comprising a step of shot blasting the substrate (2) or the base layer.

11. Method according to any one of claims 8 to 10, in which the deposition of the collecting layer (30) is carried out by phosphating, for example in a bath.

12. Method according to any one of claims 1 to 11, comprising a step of depositing a protective layer (40), electrically insulating, on the piezoelectric layer (20), in which the deposition of the protective layer (40) is carried out by powder coating.

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