Suspension organs

Abstract

A road vehicle suspension component for converting at least a portion of the vibrations and / or mechanical stresses into electricity, 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 (1) integrated into or covering a surface of the suspension element or interface element, wherein said at least one two-dimensional sheet (1) comprises a plurality of individual piezoelectric elements (3) arranged in the two-dimensional sheet (1), and wherein said at least one two-dimensional sheet (1) further comprises an electrical circuit (4) connecting said individual piezoelectric elements (3) to each other. Fig. 5.

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 constraints into electricity. 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 set up one or more piezoelectric elements on the suspension element or on an element crushed by the latter. However, to date, known solutions using 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 constraints into electricity and which is 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 web comprises a plurality of individual piezoelectric elements arranged in the two-dimensional web 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 wherein said at least one two-dimensional sheet further comprises an electrical circuit, connecting said individual piezoelectric elements together so as to collect the electricity produced by said piezoelectric elements.

[0010] Thanks to the proposed configuration, in which several piezoelectric elements are supported and distributed in a two-dimensional sheet, it is possible to recover on average a satisfactory and usable electrical voltage. Indeed, since piezoelectric elements are distributed over the entire sheet, the probability that at any time at least some of them are stressed, and therefore generate a potential difference, increases greatly. The recoverable potential difference, and its stability over time, increases all the more when the sheet includes a large number of piezoelectric elements and the sheet covers a significant portion of the interface surface. In particular, by distributing the piezoelectric elements over a large area, the recovery of different types of constraints is encouraged, not being exerted with the same amplitude depending on the area considered.

[0011] In particular, such a configuration makes it possible to adjust, individually or in sets, the parameters of the piezoelectric elements, in particular their orientations, in order to adapt them specifically to the constraints that they will be required to undergo locally.

[0012] Furthermore, the use of such individual piezoelectric elements connected together by an electrical circuit makes it possible to capture and amplify, depending on the number of piezoelectric elements, the vibrations which are usually difficult to exploit due to their low amplitude.

[0013] 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.

[0014] 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.

[0015] 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.

[0016] In certain embodiments, the suspension member comprises a plurality of two-dimensional layers fitted to said suspension element or interface element. These two-dimensional layers may be fitted to the same interface surface or to different interface surfaces. The configuration of these layers makes it possible to easily install several, in different locations, to maximize the amount of energy recovered by particularly targeting areas where stress and / or vibrations are greatest.

[0017] In certain embodiments, said two-dimensional sheets are connected to each other in series or in parallel. A hybrid configuration combining series and parallel connections is also possible.

[0018] In some embodiments, at least one, and preferably each, two-dimensional sheet has a length at least equal to 3 cm, preferably at least equal to 5 cm, more preferably at least equal to 10 cm, in a main direction of extension. The larger the sheet, the greater the surface area it covers, which increases, on the one hand, the number of piezoelectric elements that can be put in place and, on the other hand, the spatial distribution of the piezoelectric elements and therefore the probability that at any time at least some of them produce energy.

[0019] In certain embodiments, at least one, and preferably each, two-dimensional sheet has a thickness less than or equal to 5 mm, preferably less than or equal to 2 mm, more preferably less than or equal to 1 mm. The bulk of the sheet is thus very small and practically does not alter the dimensions of the suspension element or the interface element.

[0020] In some embodiments, at least one two-dimensional sheet comprises at least 10, preferably at least 50, more preferably at least 100, individual piezoelectric elements. The more piezoelectric elements there are, the greater the average voltage generated and the greater the probability that at least some of them are well oriented to effectively convert local stresses and / or vibrations.

[0021] In some embodiments, each individual piezoelectric element has a length less than or equal to 5 mm, preferably less than or equal to 2 mm, more preferably less than or equal to 1 mm. The smaller the piezoelectric element, the less voltage it generates but the greater the piezoelectric element density can be, which promotes local recovery of the smallest stresses, including vibrations. Thus, overall, a stable, continuous and ultimately greater electrical generation is obtained.

[0022] In certain embodiments, the two-dimensional sheet comprises a density of piezoelectric elements greater than or equal to 50 / dm2, preferably greater than or equal to 300 / dm2. Indeed, the higher the density of piezoelectric elements, the more local recovery of the smallest constraints, including vibrations, is favored. Thus, overall, a stable, continuous and ultimately greater electrical generation is obtained.

[0023] In some embodiments, at least one individual piezoelectric element comprises a piezoelectric material selected from the following: lead zirconate titano (PZT), polyvinyl fluoride (PVF), polyvinylidene fluoride (PVDF), polyvinyl chloride (PVC), lead-free artificial.

[0024] In certain embodiments, all the individual piezoelectric elements of a two-dimensional sheet are oriented in the same orientation direction. Such a configuration is the simplest to design and implement. It is understood here that this orientation direction is understood to be in the curvilinear plane of the sheet. In particular, when the sheet has a sheath or ring geometry, this same orientation direction can close on itself and therefore form, for example, circles.

[0025] In some embodiments, the individual piezoelectric elements of a two-dimensional sheet are arranged in a plurality of assemblies, all the individual piezoelectric elements of an assembly being aligned in a same alignment direction. Such assemblies, each preferably comprising at least ten piezoelectric elements, make it possible to adjust the orientation of the piezoelectric elements to the stresses actually present in the area in question, which increases the average quantity of energy recovered.

[0026] In certain embodiments, said direction of orientation is parallel to the main direction of extension of the two-dimensional sheet concerned.

[0027] Suspension member according to, in which said direction of orientation is inclined relative to the main direction of extension of the two-dimensional sheet concerned. Such a configuration is particularly effective when the stresses experienced are exerted mainly in a direction different from the main direction of extension of the sheet; this is particularly the case for a helical spring.

[0028] In certain embodiments, the angle formed between said direction of orientation and the main direction of extension of the two-dimensional sheet concerned is between 20 and 70°, preferably between 40 and 50°. This angle range is particularly suitable for helical springs.

[0029] In some embodiments, the direction of orientation of the individual piezoelectric elements is variable depending on their position on the suspension element or the interface element. This makes it possible to adjust the orientation of the piezoelectric elements to the constraints actually present in the area considered, which increases the average quantity of energy recovered.

[0030] In some embodiments, the individual piezoelectric elements of at least one set, preferably all individual piezoelectric elements, of at least one two-dimensional sheet, are arranged in a two-dimensional, preferably orthorhombic, Bravais lattice. Such an arrangement is easy to design and to wire.

[0031] In some embodiments, the individual piezoelectric elements of at least one set, preferably all of the individual piezoelectric elements, of at least one two-dimensional sheet, are connected in parallel within a given row and in series from one row to another.

[0032] In some embodiments, at least one two-dimensional sheet comprises a support layer, including the electrical circuit, on which the piezoelectric elements are mounted. This support layer may in particular be a flexible printed circuit.

[0033] In certain embodiments, at least one two-dimensional sheet comprises an insulating protective layer covering the individual piezoelectric elements and the electrical circuit of said two-dimensional sheet. This protective layer makes it possible to insulate the piezoelectric elements and the electrical circuit, which reduces the risk of short circuit, and protects these same elements against possible mechanical attacks, such as wear or shocks.

[0034] In some embodiments, the protective layer comprises a material selected from the following: silicone, polyethylene terephthalate (PET), polyester (PES), polyetheretherketone (PEEK) or epoxy.

[0035] In some embodiments, the protective layer comprises reinforcing fibers. These fibers may be short or long; these fibers may in particular be glass fibers or carbon fibers.

[0036] In some embodiments, the two-dimensional sheet comprises several superimposed stages, each stage comprising a plurality of individual piezoelectric elements and an electrical circuit. The electrical circuits of the different stages can be connected together, for example in series or in parallel. Each stage can be configured in the same way or in different ways.

[0037] In certain embodiments, the main direction of extension of the two-dimensional sheet is closed on itself, forming an annular geometry.

[0038] In certain embodiments, the transverse direction of extension of the two-dimensional sheet is closed on itself, forming a tubular geometry.

[0039] In certain embodiments, the two-dimensional sheet is attached, preferably by gluing, to the suspension element or the interface element.

[0040] In some embodiments, the suspension element or the interface element is overmolded onto the two-dimensional web.

[0041] In some embodiments, the two-dimensional web is threaded around the suspension member or the interface member.

[0042] In some embodiments, the two-dimensional sheet is interposed between two components of the interface element, for example between a frame and a elastomer layer in contact with the suspension element.

[0043] 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.

[0044] In some embodiments, the interface element is a bearing configured to be mounted around a stabilizer bar of the vehicle.

[0045] In some 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.

[0046] In certain embodiments, said at least one two-dimensional ply is interposed between two components of the bearing, preferably between a frame and an elastomer layer in contact with the stabilizer bar.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] In some embodiments, said at least one two-dimensional sheet covers at least one end portion of the coil spring, preferably on at least less than 5 cm, preferably at least 10 cm. The end portion of the coil spring is in fact the portion that is subjected to the most stress, in particular because it is supported against a rigid element of the vehicle.

[0055] In certain embodiments, said at least one two-dimensional sheet surrounds said at least one portion of the external surface of the helical spring in the manner of a sheath. Such a sheath can then further play a role in protecting the helical spring.

[0056] In some embodiments, said at least one two-dimensional sheet covers the entire outer surface of the coil spring.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] The above-mentioned features and advantages, as well as others, will appear on reading the following detailed description of examples of suspension members. This detailed description refers to the attached drawings. Brief description of the drawings

[0061] The attached drawings are schematic and are intended primarily to illustrate the principles of the disclosure.

[0062] 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.

[0063] [Fig. 1] [Fig. 1] is a front diagram of a first example of a piezoelectric sheet two-dimensional electric.

[0064] [Fig.2] [Fig.2] is a cross-sectional diagram of the piezoelectric sheet of [Fig.l].

[0065] [Fig.3] [Fig.3] is a front diagram of a second example of a piezoelectric sheet two-dimensional electric.

[0066] [Fig.4] [Fig.4] is a perspective view of a first example of a body of suspension including a stabilizer bar and bearings.

[0067] [Fig.5] [Fig.5] is an exploded view of a bearing of [Fig.4].

[0068] [Fig.6] [Fig.6] is a perspective view of a second example of a body of suspension comprising a leaf spring and bearings.

[0069] [Fig.7] [Fig.7] is an exploded view of a bearing of [Fig.6].

[0070] [Fig.8] [Fig.8] is a perspective view of a third example of a body of suspension comprising a coil spring and a support element.

[0071] [Fig.9] [Fig.9] is a sectional view of the support element of [Fig.8].

[0072] [Fig. 10] [Fig. 10] is a perspective view of a fourth example of a suspension member comprising a coil spring. Description of the embodiments

[0073] In order to make the disclosure more concrete, examples of suspension members are described in detail below, with reference to the attached drawings. It is recalled that the invention is not limited to these examples.

[0074] [Fig.l] schematically represents a first example of a piezoelectric sheet 1 according to the disclosure. Such a piezoelectric sheet 1 is two-dimensional, that is to say that it extends in two orthogonal directions, the main direction P of the sheet 1, corresponding to its direction of greatest length, and the transverse direction T of the sheet 1, corresponding to its direction of shortest length, with a negligible thickness compared to these two directions of extension. The piezoelectric sheet 1 comprises a support layer 2 on which is mounted a plurality of individual piezoelectric elements 3 connected to each other by an electrical circuit 4.

[0075] The electrical circuit 4 here takes the form of conductive tracks traced on the surface of the support layer 2, the piezoelectric elements 3 then being soldered onto the connectors of the electrical circuit 4. The support layer 2 can in particular take the form of a flexible printed circuit, made for example of polyimide or polyetheretherketone (PEEK).

[0076] The piezoelectric elements 3 can take different forms having in common the ability to generate a voltage difference between their two poles when they undergo deformation. For example, the piezoelectric elements can comprise lead zirconate titanoate (PZT).

[0077] The piezoelectric elements 3 are also sufficiently small to, on the one hand, allow the piezoelectric sheet 1 as a whole to be at least partially flexible and to, on the other hand, allow a significant density of piezoelectric elements 3. Thus, in the present example, the piezoelectric elements 3 measure 5 mm long, 1 mm wide and 1 mm high; the density of the piezoelectric elements 3 is 500 units per dm2.

[0078] The piezoelectric elements 3 can be arranged in different ways. In this first example, the piezoelectric elements 3 are arranged according to an or-thorhombic network, that is to say according to regular and orthogonal rows and columns.

[0079] The piezoelectric elements 3 can be oriented in different ways. In this first example, all the piezoelectric elements 3 are oriented in the same direction, which constitutes the orientation direction O of the piezoelectric sheet 1, this direction being parallel to the main extension direction P of the piezoelectric sheet 1.

[0080] However, in a second example, shown in [Fig.3], all the piezoelectric elements 103 can be oriented in the same direction but this orientation direction O can form a non-zero angle 0 with the main direction P of the sheet 1. Thus, in this second example, this angle 0 measures 20°.

[0081] In the first example, as in the second example, the piezoelectric elements 3 of the same column are connected in parallel while the different columns of the sheet 1 are connected in series. At each end of the sheet 1, the electrical circuit 4 ends at a terminal 5-, 5+, one of the terminals constituting a negative terminal 5- while the other constitutes a positive terminal 5+. Each terminal 5 can then be connected to a cable 6 making it possible to collect the electricity produced by the piezoelectric sheet 1.

[0082] Furthermore, as can be seen in [Fig.2], the piezoelectric sheet 1 further comprises an insulating protective layer 7 covering the electrical circuit 4 and each of the piezoelectric elements 3. For example, this protective layer 7 can be made of silicone and include glass fibers.

[0083] Thus, by using a large number of individual piezoelectric elements 3 of small size and distributed over the entire sheet 1, it is possible to convert into electricity the mechanical stresses undergone by the piezoelectric sheet 1 but also the vibrations passing through the latter. This electrical voltage being by construction strongly fluctuating over time, depending on the amplitude of the stresses and vibrations undergone, it is preferable to connect an electrical rectifier downstream of the piezoelectric sheet 1 in order to smooth the fluctuations in the voltage generated by the piezoelectric sheet 1.

[0084] [Fig. 4] represents a first example of a vehicle suspension member 10 including such a piezoelectric sheet 1. It is a stabilizer assembly 10 comprising a stabilizer bar 11, solid or hollow, painted or not, the central part 12 of which is equipped with two bearings 13. The bearings 13 are intended to be fixed to the chassis of the vehicle while the ends 14 of the stabilizer bar 11 each comprise an eyelet 15, the eyelets 15 being intended to be fixed to parts of the vehicle integral with each wheel of the same axle, in particular the suspension triangle of each wheel of the axle.

[0085] [Fig.5] shows such a bearing 13. The bearing 13 comprises a flange 20, a plywood 30 and an elastomeric layer 19.

[0086] The flange 20 firstly comprises a frame 20a having a general U shape and comprising two retaining tabs 21 connected by a hoop 25 so as to form a groove 26. This frame 20 is symmetrical with respect to its main axis A which more broadly constitutes the main axis of the bearing 13.

[0087] Each retaining tab 21 extends laterally from the base of the hoop 25, perpendicular to the main axis A. Each retaining tab 21 has a bearing surface 22, forming the bearing surface of the flange 20, and a through bore 23, with axis C perpendicular to the bearing surface 22 and therefore parallel to the main axis A. Each bore 23 is provided with a metal sleeve 24 passing through the retaining tab 21 and projecting beyond the bearing surface 22 of the flange 20 over a length substantially equal to the thickness of the plywood 30.

[0088] The groove 26, generally U-shaped, is also symmetrical with respect to the main axis A. It has a semi-cylindrical bottom portion, forming a cradle portion 27, flanked by two flat side walls 28 opening onto the bearing surface 22 of the flange 20. The semi-cylindrical cradle portion 27 is directed along an axis B orthogonal to the axis A and corresponding to the direction of extension of the stabilizer bar 11 when the bearing 13 is mounted.

[0089] The frame 20a of the flange 20 is made by molding and injection of polyamide 66 reinforced with glass fibers. These glass fibers are short fibers, the length of which is between 3 and 3.2 mm for a diameter between 0.2 and 0.25 mm. The metal sleeves 24 are for their part inserted into the mold of the frame 20a before the injection of the thermoplastic material. In certain examples, the sleeves 24 may comprise annular reliefs making it possible to lock their positions within the frame 20a once the material has solidified.

[0090] The flange 20 further comprises a first piezoelectric sheet 80, similar to the piezoelectric sheet 1 presented above, matching the geometry of the lower surface of the armature 20a: the first piezoelectric sheet 80 thus comprises two lateral tabs 81, covering the bearing surface 22 of each retaining tab 21 of the armature 20a, connected by a central hoop 85, matching the shape of the groove 26 of the armature 20a. A notch 82 is made in each lateral tab 81 so as to allow the sockets 24 of the flange 20 to pass through.

[0091] This first piezoelectric sheet 80 can be attached to the lower surface of the armature 20a after obtaining the latter, for example by gluing, or else can be installed beforehand in the mold of the armature 20a which can then be overmolded over the piezoelectric sheet 80.

[0092] The plywood 30 has the general shape of a plate. It thus comprises a frame 30a having a flat upper face 31 and a flat lower face 32 connected by a peripheral side wall 33. The frame 30a is also symmetrical with respect to the main axis A of the bearing 13. More precisely, the dimensions of the frame 30a correspond to the external dimensions of the flange 20 such that the plywood 30 can be brought into contact with the bearing surface 22 of the flange 20, or more precisely with the piezoelectric sheet 80 covering it, by exactly extending the contours of the flange 20.

[0093] In the present example, the plywood 30 is essentially planar; however, in other examples, it could have other shapes, for example a cradle shape depending on the shape of the flange and / or the chassis of the vehicle.

[0094] More particularly, the frame 30a of the plywood 30 has a closure portion 36 framed by two assembly portions 37: each assembly portion 37 is designed to coincide with a retaining tab 21 of the flange 20 while the closure portion 36 is designed to span the groove 26 of the flange 20 and thus close it.

[0095] Each assembly portion 37 comprises a bore 34 coinciding with the fixing bore 23 of the corresponding retaining tab 21 of the flange 20: its diameter corresponds substantially, that is to say, within a clearance, to the external diameter of the sleeve 24 such that the part of the sleeve 24 projecting from the bearing surface 22 of the flange 20 can engage in this bore 34.

[0096] The frame 30a of the plywood 30 is made by molding and injection of polyamide 66 reinforced with glass fibers. The glass fibers used to reinforce the polyamide of the plywood 30 are similar to those used for the flange 20.

[0097] The plywood 30 further comprises a second rectangular piezoelectric sheet 90, also similar to the piezoelectric sheet 1 presented above, covering the upper surface of the closure portion 36 of the frame 30a.

[0098] This second piezoelectric sheet 90 can be attached against the upper surface of the frame 30a of the plywood 30 after obtaining the latter, or else can be installed beforehand in the mold of the frame 30a which can then be overmolded over the piezoelectric sheet 90.

[0099] The stabilizer assembly 10 is then assembled in the following manner. After production of the flange 20 and the plywood 30, each equipped with its piezoelectric sheet 80, 90, the flange 20 is passed around the stabilizer bar 11. This assembly is then placed in a mold so that the stabilizer bar 11 extends within the flange 20 along the axis B, leaving a continuous and constant clearance between the stabilizer bar 11 and the cradle portion 27 of the flange 20.

[0100] Rubber is then injected into the mold so as to fill the space of the groove 26 left all around the stabilizer bar 11, from the cradle portion 27 of the flange 20 to the opening of the groove 26, thus forming the elastomer layer 19. The elastomer layer 19 thus obtained is then vulcanized so as to secure the stabilizer bar 11 within the flange 20.

[0101] Then, the plywood 30 is attached to the bearing surface 22 of the flange 20. On this occasion, the projecting parts of the sockets 24 make it possible to correctly position and align the plywood 30 by fitting the bores 34 of the plywood around the sockets 24 of the flange 20.

[0102] The bearing 13 is thus assembled and the same operation can be carried out for the second bearing 13. Alternatively, the two bearings can be assembled simultaneously.

[0103] The stabilizer assembly 10 thus assembled can then be mounted on the chassis of the vehicle by pressing the lower surface 32 of the bearing 13 onto the chassis and by screwing the bearing 13 onto the chassis using two screws passing through the bores 23 and 34 of the retaining tabs 21 of the flange 20 and the assembly portions 37 of the plywood 30.

[0104] In operation, the bearing 13 is stressed in six directions: three directions of movement (axial, radial and normal directions) and three directions of rotation (torsional, conical around the radial axis and conical around the normal axis directions). The position of the piezoelectric sheets 80 and 90, at the interface between the interface between the stabilizer bar 11 and the armatures of the bearing 13, allows them to capture a significant portion of the mechanical stresses and vibrations experienced by the bearing 13 and thus to produce a significant quantity of electrical energy.

[0105] More particularly, while the main direction of extension P of the first piezoelectric sheet 80 extends along the retaining tabs and the groove 26, the direction of orientation O of the piezoelectric elements forms an angle 0 of 45° with this main direction P because the flange 20 of the bearing 13 undergoes a mixed vibration mode linked to the triaxiality of the constraints (i.e. along the torsional, conical and radial directions at the same time).

[0106] On the other hand, while the main direction of extension P of the second piezoelectric sheet 90 extends along the main direction of the frame 30a of the plywood 30, the direction of orientation O of the piezoelectric elements forms an angle of 0° or 90° with this main direction P because the plywood 30 of the bearing 13 mainly undergoes a radial vibration mode in bending.

[0107] [Fig. 6] represents a second example of a vehicle suspension member 110 including a piezoelectric sheet as presented above. It is a leaf spring 110 comprising a metal leaf 111 curved at each of its ends so as to form an eyelet 115. The leaf spring 110 also comprises, for each eyelet 115, a cylindrical bearing 113 inserted in the eyelet 115.

[0108] [Fig.7] shows such a bearing 113. The bearing 113 comprises an inner frame 141 and an outer frame 142, both cylindrical and coaxial, between which an elastomer layer 143 extends. A first piezoelectric sheet 180, similar to the piezoelectric sheet 1 presented above but taking the form of a cylindrical sleeve, is provided between the inner frame 141 and the elastomer layer 143 and a second piezoelectric sheet 190, similar to the piezoelectric sheet 1 presented above but also taking the form of a cylindrical sleeve, is provided between the outer frame 142 and the elastomer layer 143.

[0109] In this example, the main direction of extension P of the first piezoelectric sheet 180 extends parallel to the central axis of the bearing 113 while its transverse direction T corresponds to the tangential direction of the bearing 113, which closes on itself. The direction of orientation O of its piezoelectric elements forms an angle of 45° with the main direction P of the piezoelectric sheet 180 so as to capture the internal vibrations of the torsional and conical modes.

[0110] The main direction of extension P of the second piezoelectric sheet 190 also extends parallel to the central axis of the bearing 113 while its transverse direction T also corresponds to the tangential direction of the bearing 13, which closes on itself. The direction of orientation O of its piezoelectric elements also forms an angle of 45° with the main direction P of the piezoelectric sheet 190 so as to capture the external vibrations of the torsional and conical modes; however, preferably, this angle of 45° does not have the same sign as for the first piezoelectric sheet 180.

[0111] [Fig. 8] represents a third example of a vehicle suspension member 210 including a piezoelectric sheet as presented above. This is an assembly 210 comprising a helical spring 211 and a support element 213 installed on a rear suspension cup 216 and against which the helical spring 211 bears.

[0112] [Fig. 9] shows this support element 213 in section. The upper face of the support element 213 has a groove 251 capable of receiving a portion of terminal turn 211A of the helical spring 211. In order to be able to receive the portion of terminal turn 211A, the groove 251 is curved. More precisely, the groove 251 is curved in the shape of a helix arc corresponding substantially to the helix arc described by the portion of terminal turn 211A.

[0113] Furthermore, the support element 213 has at least one elastic holding member configured to hold the terminal coil portion 213A in the groove 251. More precisely, the support element 213 has a plurality of elastic holding members 253 and 255.

[0114] The first elastic holding members 253 are reliefs projecting from the radially inner side wall 252 of the groove 251. The second elastic holding members 255 are integral with the radially outer side wall 254 of the groove 251.

[0115] In the example shown, the support element 213 comprises a support portion 250 and a base portion 260. The base portion 260 is integral with the support portion 250.

[0116] The support portion 250 has the groove 251 and the elastic holding members 253 and 255 already described previously.

[0117] The base portion 260 is suitable for being installed on the cup 216. Thus, the base portion 260 has a peripheral portion 265P and a central portion 265C. The central portion 265C has a substantially cylindrical shape allowing the centering device 216C of the cup 216 to be received. The support element 213 is thus kept in contact with the centering device 216C.

[0118] The peripheral portion 265P has a substantially flat lower face intended to come into contact with the portion 216P of the cup 214. The upper face of the peripheral portion 265P is intended to come into contact with the lower face of the support portion 250. The upper face of the peripheral portion 265P has a general ring shape, and the lower face of the support portion 250 has a general ring sector shape. Furthermore, the central portion 265C is received in a central portion 259 of substantially cylindrical shape that the support portion 250 has.

[0119] A piezoelectric sheet 280 similar to the piezoelectric sheet 1 described above is installed between the support portion 250 and the base portion 260. It thus comprises a peripheral portion 280P, having a general ring shape, extending along the peripheral portion 265P of the base portion 260 and a central portion 280C, having a substantially cylindrical shape, extending along the central portion 265C of the base portion 260.

[0120] In this example, the main direction of extension P of the piezoelectric sheet 280 follows the geometry of the interface between the support portion 250 and the base portion 260: it is therefore locally radial at the peripheral portion 280P and axial at the central portion 280C. The piezoelectric sheet 280 here comprises two sets of piezoelectric elements. The orientation direction O of the piezoelectric elements of the peripheral portion 280P forms an angle of 45° with the main direction P in order to capture the axial and rotational vibrations of the spring 211 on the peripheral portion 216P of the cup 216.

[0121] On the other hand, the orientation direction O of the piezoelectric elements of the central portion 280C forms an angle of 0° or 90° with the main direction P in order to capture the transverse vibrations of the spring 211 on the centering device 216C of the cup 216.

[0122] In a preferred variant, the support portion 250 is made of a first material, which is elastic, and the base portion 260 is made of a second material that is more rigid than the first material. Preferably, the first material is an elastomer, more particularly a thermoplastic elastomer, possibly expanded, which may or may not be synthetic, and / or the second material is preferably an organic matrix composite material.

[0123] The bearing portion 250, being made of the first material, tends to absorb noise due to the elasticity of the first material, like the previously mentioned known bearing element. On the other hand, the base portion 260 provides the mechanical connection between the bearing element 213 and the cup 216, and is made of the second material which is more rigid than the first material, and therefore less vulnerable to wear linked to contact with the cup 216. As a result, the bearing element 213 has an increased service life, while having the same noise damping and spring coating protection functions as the previously mentioned known bearing element.

[0124] It will be noted that the support element 213 can be manufactured by two-material injection molding of the first material and the second material mentioned above. More concretely, the support element 213 can be manufactured by first injection molding the base portion 260, and then injection molding the support portion 250 on the base portion 260. These two injection molding steps can be carried out within the same injection mold, by installing the piezoelectric sheet 280 in the mold between these two molding steps. Alternatively, the injection molding of the base portion 260 can be carried out in a first mold, then the molded base portion 260 can be moved into a second mold, the piezoelectric sheet 280 is then installed in this second mold, and then finally the injection molding of the support portion 250 is carried out.

[0125] In a particularly preferred example, the support portion 250 is made of an expanded thermoplastic polyurethane (TPU), and / or the base portion 260 is made of a polyamide reinforced with glass fibers.

[0126] [Fig. 10] shows a fourth example of a vehicle suspension member 310 including a piezoelectric sheet as presented above. This is an assembly 310 comprising a helical spring 311 and a piezoelectric sheet 380 taking the form of a sheath threaded around at least a portion of the helical spring 311.

[0127] The piezoelectric sheet 380 is similar to the piezoelectric sheet 1 presented above except that its transverse direction T is closed on itself so as to form a tubular sheath; its main direction P extends in a helix along the spring 311. The diameter of this sheath formed by the piezoelectric sheet 380 is adjusted to correspond substantially to the diameter of the turns of the spring 311. As is the case in this example, the piezoelectric sheet 380 extends over the entire length of the spring 311. However, in other examples, the piezoelectric sheet could be provided only at one and / or the other of the ends of the spring 311: in fact, the terminal turns of the spring 311 are the turns which accumulate the most mechanical stresses, in particular compression.

[0128] In the present example, the piezoelectric sheet 380 comprises three different portions, each comprising a set of differently configured piezoelectric elements. In the central portion 380C, the orientation direction O forms an angle of 45° with the main direction P of the sheet 380 and therefore with the helical direction of the spring 311, which makes it possible to capture the torsional deformations stored in the spring wire and the associated vibrations.

[0129] In each end portion 380E, analogously, the orientation direction O forms an angle of 0° or 90° with the main direction P of the sheet 380, which makes it possible to be more sensitive to the bending forces of the terminal turns and to the associated axial vibrations.

[0130] 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.

[0131] 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, having an elastic behavior so as to act as a suspension spring during operation of the vehicle, or at least one interface element (13), configured to participate in the fixing of at least one suspension element of the vehicle (11) having an elastic behavior so as to act as a suspension spring during operation of the vehicle, and at least one two-dimensional sheet (1, 80, 90), continuous, integrated in the suspension element or the interface element (13) 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 member of the vehicle during operation of the vehicle, in which said at least one two-dimensional sheet (1, 80,90) comprises a plurality of individual piezoelectric elements (3) arranged in the two-dimensional sheet (1, 80, 90) so as to convert into electricity at least part of the vibrations and / or mechanical stresses undergone by the suspension element (11) during operation of the vehicle, and wherein said at least one two-dimensional sheet (1, 80, 90) further comprises an electrical circuit (4), connecting said individual piezoelectric elements (3) together so as to collect the electricity produced by said piezoelectric elements (3).,

2. Suspension member according to claim 1, in which at least one, and preferably each, two-dimensional sheet (1) has a length at least equal to 3 cm, preferably at least equal to 5 cm, more preferably at least equal to 10 cm, in a main direction of extension (P), and in which at least one, and preferably each, two-dimensional sheet (1) has a thickness less than or equal to 5 mm, preferably less than or equal to 2 mm, more preferably less than or equal to 1 mm.

3. A suspension member according to claim 1 or 2, wherein each individual piezoelectric element (3) has a length of less than or equal to 5 mm, preferably less than or equal to 2 mm, preferably less than or equal to 1 mm.

4. Suspension member according to any one of claims 1 to 3, in which the two-dimensional sheet (1) comprises a density of piezoelectric elements (3) greater than or equal to 50 / dm2, preferably greater than or equal to 300 / dm2.

5. Suspension member according to any one of claims 1 to 4, in which all the individual piezoelectric elements (3) of a two-dimensional sheet (1) are oriented in the same orientation direction (0).

6. Suspension member according to claim 5, wherein said direction of orientation (0) is inclined relative to the main direction of extension (P) of the two-dimensional sheet (101) concerned, and wherein the angle (0) formed between said direction of orientation (0) and the main direction of extension (P) of the two-dimensional sheet (101) concerned is between 20 and 70°, preferably between 40 and 50°.

7. A suspension member according to any one of claims 1 to 4, wherein the direction of orientation (O) of the individual piezoelectric elements (1) is variable depending on their position on the suspension element (11) or the interface element (13).

8. Suspension member according to any one of claims 1 to 7, in which at least one two-dimensional sheet (1) comprises an insulating protective layer (7) covering the individual piezoelectric elements (3) and the electrical circuit (4) of said two-dimensional sheet (1).

9. Suspension member according to any one of claims 1 to 8, in which the transverse direction of extension (T) of the two-dimensional sheet (380) is closed on itself, forming a tubular geometry, and in which the two-dimensional sheet (380) is threaded around the suspension element (311) or the interface element.

10. Suspension member according to any one of claims 1 to 8, wherein the interface element is a bearing (13) configured to be mounted around a stabilizer bar (11) of the vehicle, and wherein said at least one two-dimensional ply (80, 90) is interposed between two components of the bearing (13), preferably between a frame (20a, 30a) and an elastomer layer (19) in contact with the stabilizer bar (11).

11. Suspension member according to any one of claims 1 to 8, wherein the interface element is a bearing (113) configured to be mounted in an eyelet (115) of a suspension element (111) of the vehicle, and wherein said at least one two-dimensional ply (180, 190) is interposed between two components of the bearing (113), preferably between a frame (141, 142) and an elastomer layer (143).

12. A suspension member according to any one of claims 1 to 9, wherein the suspension element is a coil spring (311), and wherein said at least one two-dimensional web (380) covers at least a portion of the outer surface of the coil spring (311).

13. Suspension member according to any one of claims 1 to 8, wherein the interface element is a support element (213) for a helical spring configured to be mounted at one end (21 IA) of a helical spring (211) and to be locked on a cup (216), and wherein said at least one two-dimensional sheet (280) is interposed between two components of the support element (213), preferably between a support portion (250) in contact with the helical spring (211) and a base portion (260) in contact with the cup (216).

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