EP1305176A1 - Elastic articulation for vehicle suspension - Google Patents

Elastic articulation for vehicle suspension

Info

Publication number
EP1305176A1
EP1305176A1 EP01960840A EP01960840A EP1305176A1 EP 1305176 A1 EP1305176 A1 EP 1305176A1 EP 01960840 A EP01960840 A EP 01960840A EP 01960840 A EP01960840 A EP 01960840A EP 1305176 A1 EP1305176 A1 EP 1305176A1
Authority
EP
European Patent Office
Prior art keywords
elastic
sleeve
elastic joint
vehicle
articulation
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP01960840A
Other languages
German (de)
French (fr)
Inventor
Serge Lefebvre
Michel Gautheron
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Michelin Recherche et Technique SA Switzerland
Michelin Recherche et Technique SA France
Societe de Technologie Michelin SAS
Original Assignee
Michelin Recherche et Technique SA Switzerland
Michelin Recherche et Technique SA France
Societe de Technologie Michelin SAS
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Michelin Recherche et Technique SA Switzerland, Michelin Recherche et Technique SA France, Societe de Technologie Michelin SAS filed Critical Michelin Recherche et Technique SA Switzerland
Publication of EP1305176A1 publication Critical patent/EP1305176A1/en
Withdrawn legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60G—VEHICLE SUSPENSION ARRANGEMENTS
    • B60G11/00—Resilient suspensions characterised by arrangement, location or kind of springs
    • B60G11/22—Resilient suspensions characterised by arrangement, location or kind of springs having rubber springs only
    • B60G11/23—Resilient suspensions characterised by arrangement, location or kind of springs having rubber springs only of the torsional-energy-absorption type
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60G—VEHICLE SUSPENSION ARRANGEMENTS
    • B60G7/00—Pivoted suspension arms; Accessories thereof
    • B60G7/02—Attaching arms to sprung part of vehicle
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
    • F16F1/00—Springs
    • F16F1/36—Springs made of rubber or other material having high internal friction, e.g. thermoplastic elastomers
    • F16F1/38—Springs made of rubber or other material having high internal friction, e.g. thermoplastic elastomers with a sleeve of elastic material between a rigid outer sleeve and a rigid inner sleeve or pin, i.e. bushing-type
    • F16F1/387—Springs made of rubber or other material having high internal friction, e.g. thermoplastic elastomers with a sleeve of elastic material between a rigid outer sleeve and a rigid inner sleeve or pin, i.e. bushing-type comprising means for modifying the rigidity in particular directions
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60G—VEHICLE SUSPENSION ARRANGEMENTS
    • B60G2200/00—Indexing codes relating to suspension types
    • B60G2200/10—Independent suspensions
    • B60G2200/13—Independent suspensions with longitudinal arms only
    • B60G2200/132—Independent suspensions with longitudinal arms only with a single trailing arm
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60G—VEHICLE SUSPENSION ARRANGEMENTS
    • B60G2202/00—Indexing codes relating to the type of spring, damper or actuator
    • B60G2202/10—Type of spring
    • B60G2202/14—Plastic spring, e.g. rubber
    • B60G2202/142—Plastic spring, e.g. rubber subjected to shear, e.g. Neidhart type
    • B60G2202/1424—Torsional
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60G—VEHICLE SUSPENSION ARRANGEMENTS
    • B60G2204/00—Indexing codes related to suspensions per se or to auxiliary parts
    • B60G2204/10—Mounting of suspension elements
    • B60G2204/14—Mounting of suspension arms
    • B60G2204/143—Mounting of suspension arms on the vehicle body or chassis
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60G—VEHICLE SUSPENSION ARRANGEMENTS
    • B60G2204/00—Indexing codes related to suspensions per se or to auxiliary parts
    • B60G2204/10—Mounting of suspension elements
    • B60G2204/14—Mounting of suspension arms
    • B60G2204/143—Mounting of suspension arms on the vehicle body or chassis
    • B60G2204/1434—Mounting of suspension arms on the vehicle body or chassis in twist-beam axles arrangement
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60G—VEHICLE SUSPENSION ARRANGEMENTS
    • B60G2204/00—Indexing codes related to suspensions per se or to auxiliary parts
    • B60G2204/40—Auxiliary suspension parts; Adjustment of suspensions
    • B60G2204/41—Elastic mounts, e.g. bushings
    • B60G2204/4104—Bushings having modified rigidity in particular directions
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60G—VEHICLE SUSPENSION ARRANGEMENTS
    • B60G2204/00—Indexing codes related to suspensions per se or to auxiliary parts
    • B60G2204/40—Auxiliary suspension parts; Adjustment of suspensions
    • B60G2204/41—Elastic mounts, e.g. bushings
    • B60G2204/4104—Bushings having modified rigidity in particular directions
    • B60G2204/41042—Bushings having modified rigidity in particular directions by using internal cam surfaces

Definitions

  • the present invention relates generally to elastic joints and more particularly to an elastic joint intended to connect a suspension arm to a vehicle body and capable of working in torsion and of carrying a substantial part of the weight. from the cash register.
  • the expression “elastic articulation capable of working in torsion and of carrying a substantial part of the weight of the vehicle body” means an articulation having a torsional stiffness, around the axis of the articulation, such that the latter is capable of supporting a substantial part of the weight of the vehicle body without the need to add to the suspension arms of the vehicle wheels strong metal springs or other elastic elements to support the weight of the checkout.
  • automobile manufacturers usually require a vertical stiffness, at the level of each wheel, which varies according to passenger vehicles in a range of the order of 8 to 20 N / mm.
  • the elastic joints proposed have, depending on the lengths of the wheel suspension arms, a torsional stiffness of between 10 and 40 mN / degree.
  • a conventional elastic joint placed in the same place on the same vehicle and designed to work essentially in compression, which does not bear the weight of the vehicle body, generally has a torsional rigidity of less than 1 mN / degree.
  • the present invention is applicable in particular, but not exclusively, to an elastic joint with variable radial stiffness, the radial stiffness of which has a minimum value along a first reference axis of a system of three reference axes, including a second reference axis coincides with the axis of rotation of the elastic joint.
  • first reference axis is oriented pe endicularly or substantially perpendicular to a horizontal reference plane linked to the vehicle body.
  • horizontal reference plane linked to the body is meant here a plane which moves parallel to the ground while the vehicle is running under normal conditions.
  • Elastic joints with variable radial stiffness are already well known, in particular by European patent EP 0 956 984 of the applicant.
  • the elastic articulation described in this document comprises an internal cylindrical reinforcement, an external cylindrical reinforcement concentrically surrounding the internal reinforcement, and a sleeve of elastomeric material, which is disposed between the internal and external reinforcement and whose inner and outer peripheral surfaces are linked without possibility of sliding to said interior and exterior frames.
  • the sleeve of elastomeric material comprises at least one cell, preferably two diametrically opposite cells, which are positioned in such a way that the articulation has a minimum radial stiffness along the first above-mentioned reference axis.
  • one of the reinforcements of the elastic articulation for example the external reinforcement
  • the other reinforcement for example internal reinforcement is rigidly linked to the suspension arms.
  • the fixing of the external reinforcement to the support part is usually carried out by a press fit or fitting operation of the external reinforcement in a bore of the support part.
  • This fitting technique by fitting is relatively complicated. Indeed, it involves controlling the fitting force and, prior to the fitting operation proper, treatments of the external frame and / or the bore of the support part. These treatments may consist, for example, of a lubrication operation to facilitate the insertion of the external frame into the bore of the support piece, and / or of calibration operations of the external peripheral surface of the external frame or of the inner surface of the bore of the support part. These latter calibration operations may be necessary in order to eliminate any surface defect, for example possible ovalization of the external frame and / or of the bore of the support piece, and in order to thus ensure uniform contact, therefore a uniform tightening or shrinking of the external reinforcement in the bore of the support piece, over the entire circumference and over the entire length of the fitting.
  • the support piece Since the support piece maintains the external reinforcement by clamping or shrinking, it must therefore be able to withstand the stresses of shrinking in service. This implies that the wall (fabric) of the support piece, which surrounds the outer frame of the elastic joint, has a high thickness.
  • the sleeve of elastomeric material of the elastic joint does not have an axisymmetric shape
  • an elastic joint with variable radial stiffness such as that described in the application for European patent cited above
  • the elastic joint has a minimum radial stiffness along a reference axis
  • the external reinforcement of the elastic joint is introduced into the bore of the support part with a precise orientation or azimuth, so that, in service, after fixing the support piece to the body of a vehicle, the reference axis along which the elastic articulation has its minimum radial stiffness is correctly oriented relative to a system of reference axes linked to the vehicle body.
  • the present invention therefore aims to remedy the aforementioned problems posed by previously known elastic joints, in which the outer frame of the elastic joint is force fitted into the bore of a support piece.
  • the present invention also aims to provide an elastic joint with variable radial stiffness, having improved resistance to fatigue both under compression / traction stresses and under torsional stresses.
  • the invention provides an elastic articulation intended to connect a suspension arm to a vehicle body and capable of carrying a substantial part of the weight of the body, comprising an internal frame, an external frame surrounding the internal frame, and a sleeve made of elastomeric material, which is disposed between the interior and exterior reinforcements and the interior and exterior peripheral surfaces of which are linked without the possibility of sliding to said interior and exterior reinforcements.
  • the first object of the invention is achieved by the fact that the external frame is shaped so that it can be fixed directly to the body of a vehicle.
  • fixed directly is meant here that the external frame is fixed to the body of the vehicle without a rigid intermediate support piece, but it should not be excluded that one or more blocks of rubber or other similar material can be interposed between the external frame and the body.
  • said external reinforcement plays both the role of an external reinforcement of a known elastic articulation and the role of the support part in which the external reinforcement of the known elastic joint had previously to be force-fitted to then allow the elastic joint to be fixed to the vehicle body.
  • the external reinforcement of the elastic joint can be constituted by a cast or spun piece, in the form of a spar comprising a housing, in which the sleeve made of elastomeric material is formed by molding and adhered directly to the surface of the housing.
  • the invention make it possible to remove a mass of material corresponding to that of the 'external reinforcement of the known elastic joint, but in addition the part (fabric) of the spar which surrounds the sleeve of elastomeric material may have a wall thickness less than that of the spar associated with the known elastic joint. Indeed, due to the absence of tight fitting, it suffices that the thickness of the fabric of the beam is dimensioned in relation to the resistance to injection molding pressures and no longer in relation to the resistance to stresses hooping which lead to significant thicknesses of fabric.
  • the thickness of the fabric must also be dimensioned to withstand the service constraints.
  • the present invention is applicable both to an elastic joint having a constant radial stiffness, and to an elastic joint having a variable stiffness, in particular a minimum stiffness along a radial direction which, after fixing the elastic joint to the body of a vehicle, must have a desired orientation with respect to a system of reference axes linked to the body of the vehicle.
  • the azimuth necessary to orient the minimum radial stiffness of the sleeve of elastomeric material relative to the spar constituting the outer frame, therefore relative to the vehicle body can be carried out easily and directly by an appropriate positioning of the impression of the injection mold relative to the spar in the housing of which the elastomeric sleeve is molded.
  • the elastic joint according to the invention due to the absence of a fitting connection in the elastic joint according to the invention, the operations of calibration treatment and / or lubrication, which were necessary with the known elastic joints, are eliminated. In particular, the surface of the beam member housing no longer requires specific preparation for fitting. In addition, the problems of resistance to sliding in the axial direction as in the circumferential direction, which arise with known elastic joints comprising a fitting connection between the external reinforcement and the beam, are also completely eliminated. In the elastic joint according to the invention, the resistance to axial and / or torsional stresses to which the joint is subjected in service, is managed by the bonded interface between the sleeve of elastomeric material and the beam.
  • the bonded bond between the sleeve of elastomeric material and the beam is provided by adhesives whose resistance to shearing and tearing provides a sufficient margin of safety compared to the maximum values of the stresses seen, in service, by the articulation at the level of the outer diameter of the sleeve of elastomeric material.
  • the adhesives used for this purpose can be the same as those which are usually used in the elastic joints known for bonding the sleeve of elastomeric material to the external frame and to the internal frame of the joint.
  • the sleeve of elastomeric material may comprise in a manner known per se, in at least one of its end faces, at least one recess which is positioned so that the joint has a minimum radial stiffness along a first reference axis of a system of three reference axes, a second reference axis of which coincides with the axis of rotation of the elastic joint.
  • the second object of the invention is achieved by the fact that at least one of the two end faces of the sleeve has a profile which evolves continuously in the circumferential direction of the sleeve of elastomeric material between at least one minimum and at least a maximum.
  • the two end faces of the sleeve have a corrugated profile.
  • the profile has a substantially sinusoidal or pseudo-sinusoidal shape.
  • the profile, in the inner peripheral region of said end face has at least a minimum and at least a maximum which are offset by a predefined angle respectively with respect to at least a minimum and at least a maximum of the profile in the outer peripheral region of said end face when no load is applied to the joint.
  • said predefined angle is preferably chosen in such a way that, when the articulation is subjected to a reference load causing a relative rotation of said predefined angle of the internal and external reinforcements with respect to each other, the geometric places of the minima and the geometric places of the maxima of the profile between said inner and outer peripheral regions are oriented substantially radially respectively along the first reference axis and along a third reference axis of the system of three reference axes.
  • the beam forming the external reinforcement comprises at least one bearing face, preferably two bearing faces, capable of cooperating with at least one corresponding bearing face on the body of the vehicle, so that, after fixing the beam to said body, the three reference axes of the elastic joint have predefined orientations with respect to a system of reference axes linked to the vehicle body.
  • the first reference axis is substantially perpendicular to a horizontal plane linked to the vehicle body.
  • FIG. 2 is a perspective view of one of the two elastic joints incorporated in the axle of Figure 1;
  • Figure 3 is a horizontal sectional view of the elastic joint of Figure 2;
  • FIG. 4 is an elevational view, in the free state, of the sleeve of elastomeric material of the elastic joint of Figures 2 and 3;
  • FIG. 5 is a view of the sleeve of elastomeric material along arrow F of Figure 4;
  • - Figure 6 is a view similar to Figure 4 and shows the shape of the sleeve of elastomeric material when subjected to a reference torsional load;
  • Figure 7 is a view similar to Figure 5, the sleeve of elastomeric material being subjected to the reference torsional load;
  • FIG. 8 is a sectional view along the broken line VIII-VIII of Figure 7;
  • FIG. 9 is a graph showing the corrugated profile of one of the end faces of the sleeve of elastomeric material in the inner peripheral region and in the outer peripheral region of said sleeve, when the latter is in the free state;
  • FIG. 10 is a graph showing the corrugated profile of the end face of the sleeve of elastomeric material in the inner peripheral region and in the outer peripheral region of said sleeve, when the latter is subjected to the reference torsional load.
  • an axle 1 more precisely a rear axle, intended to be mounted on the body 2 of a vehicle by means of elastic joints 3, an advantageous embodiment of which will be described in detail later.
  • the X axis is the longitudinal median axis of the vehicle
  • the Y axis is a transverse axis, which defines with the X axis the horizontal reference plane mentioned above
  • the Z axis is vertical.
  • the axle 1 essentially comprises two drawn suspension arms 4 which are connected to the body 2 by elastic articulations 3 capable of working in compression / traction and in torsion so that the two suspension arms 4 can independently have the one from the other, a limited angular movement relative to the body 2 around the axis 6 of the joints 3, which coincides with the axis Y.
  • joints 3 which are similar (symmetrical, in general).
  • the joint 3 is essentially constituted by a sleeve 7 of elastomeric material, which is disposed between an inner cylindrical frame 8 and an outer frame 9 and which is rigidly fixed to these two frames, without possibility sliding, by the known technique of adhesion.
  • each suspension arm 4 carries, on the side of the corresponding elastic articulation 3, a shaft 11 and, on the side opposite to said articulation, a rocket 12 intended to receive a wheel 13, more precisely a rear wheel of the vehicle.
  • Each of the two shafts 11, the axes of which are aligned with the axis 6 of the elastic joints 3 and with the axis Y, is rigidly fixed, that is to say without possible relative rotation, to the internal reinforcement 8 of the corresponding elastic joint.
  • the fixing of the shaft 11 with internal reinforcement 8 can be carried out by force fitting, by gluing or by any other technique known in this field of the technique.
  • a cross-member (not shown) can be provided which connects the two shafts 11 in a U-shaped configuration, or the two arms 4 in a H-shaped configuration.
  • the cross-member can have a structure similar to that described in the request for Patent EP 0 956 984 or in patent application WO 97/47 486.
  • the outer frame 9 of the elastic joint 3 is here constituted by a beam, made for example in the form of a cast or spun piece of aluminum or aluminum alloy.
  • the beam 9 has a housing 14 in which the sleeve 7, made of elastomeric material, of the elastic joint 3 is rigidly fixed.
  • the spar 9 has at least one flat support face, preferably two flat support faces 9a and 9b, which are perpendicular to each other and which are intended to serve as a reference surface for mounting the spar 9 on the vehicle body 2.
  • the flat face 9b is perpendicular to the axis of the housing 14, therefore also to the axis Y of the elastic joint 3, and is intended to be applied against a vertical support surface of the body 2, which is parallel to the plane 0 defined by the X and Z axes of the reference system linked to the vehicle body.
  • the flat support face 9a of the beam 9 is intended to be applied against another flat support surface which is provided on the body 2 of the vehicle and which is parallel to the horizontal plane defined by the two axes X and Y of the system of reference linked to the vehicle body.
  • the spar 9 further comprises two holes 15 and 16 whose axes are perpendicular respectively to the flat bearing faces 9a and 9b.
  • the holes 15 and 16 are intended to receive screws or bolts (not shown) and constitute, in combination with said screws or bolts, anchoring means for fixing the beam 9 on the abovementioned bearing surfaces of the vehicle body.
  • each of the two elastic joints 3 is designed to have a variable radial stiffness in the circumferential direction, that is to say that the stiffness of the joint varies as a function of the polar angle of the radial direction around the Y axis.
  • the sleeve 7 can have any known structure or geometry capable of giving it a variable radial stiffness.
  • the sleeve 7 may include cells like those of the sleeve of elastomeric material of the elastic joint described in patent application EP 0 956 984.
  • the variation in the radial stiffness is obtained preferably by giving at least one of the two end faces 7a and 7b of the sleeve 7 of elastomeric material, preferably at its two end faces, a profile which evolves continuously in the circumferential direction of the sleeve 7 between 5 at least a minimum and at least a maximum, as is particularly visible in Figure 4.
  • the corrugated profile has, for example, a sinusoidal or pseudo-sinusoidal shape with two minima and two maxima on the circumference of the sleeve 7.
  • the elastic joint is intended to work not only in compression / traction, but also in torsion to carry a substantial part of the weight of the body and to ensure a spring suspension function, it is preferable that the two minima mj and the two maxima Mj corrugated profile Pj in the inner peripheral region of the end face 7a or 7b are angularly shifted by a predetermined angle ⁇ respectively with respect to both minimum e m and two maxima m e corrugated profile P e in the outer peripheral region of the end face 7a or 7b when the sleeve 7 is not subjected to any load, as shown in FIGS. 5 and 9.
  • the geometrical locations 17 of the minima of the corrugated profile of the end face 7a or 7b of the sleeve 7 extend obliquely with respect to a radial direction, as shown in FIG. 5.
  • the li them geometric 18 of the maxima of the corrugated profile of the end face 7a or 7b extend obliquely with respect to another radial direction, as is also shown in FIG. 5.
  • the value of the predefined angle ⁇ is chosen from such that, when the elastic joint 3 is subjected to a reference load causing a relative rotation of this angle ⁇ , for example of the internal reinforcement 8 relative to the external reinforcement 9 (spar), the sleeve 7 undergoes a torsion and deforms in such a way that the minima m. ⁇ and the maxima Mj of the corrugated profile P; in the inner peripheral region of the end face 7a or 7b are aligned radially respectively with the minima m e and the maxima M e of the corrugated profile P e in the outer peripheral region of the end face 7a or 7b, as shown in FIGS. 7 and 10.
  • the geometric locations 17 of the minima and the geometric locations 18 of the maxima of the corrugated profile on each of the two end faces 7a and 7b of the sleeve 7 are then oriented substantially radially respectively along the two reference axes X 'and Z' of a system of three reference axes X ', Y, Z' linked to each elastic joint 3.
  • the two axes X 'and Z' are perpendicular to the Y axis of the two elastic joints 3, which is also designated by reference 6 in FIG. 1.
  • the aforementioned reference load which determines the value of the angle ⁇ as well as a reference attitude of the vehicle comprising the axle 1 of FIG.
  • the reference load can be defined for example as being the load applied to each of the two wheels 13 of the axle 1 for a vehicle in running order in current use.
  • This reference load will naturally vary from one vehicle model to another and its definition may itself vary from one vehicle manufacturer to another.
  • the reference load can be defined as being a quarter of the sum of the empty weight of the vehicle, the weight of two mannequins of 75 kg each, and a weight of fuel corresponding to a half full fuel tank.
  • the axial length of the sleeve 7 of elastomeric material has a minimum value £ corresponding to the geometrical locations 17 of the minima of the corrugated profile of the two end faces 7a and 7b, that is to say in the plane defined by the two axes Y and Z ', and a maximum value L corresponding to the geometrical locations 18 of the maxima of the corrugated profile of the two end faces 7a and 7b, that is ie in the plane defined by the two axes Y and X ′, as shown respectively in the left and right halves of FIG. 8.
  • the elastic joint 3 described above will therefore have a minimum radial stiffness along the axis Z 'and a maximum radial stiffness along the axis X', when the sleeve is subjected at the expense of the ref in this.
  • the axes X 'and Z' of each articulation 3 are oriented, by virtue of the abovementioned bearing surfaces 9a and 9b of the side members 9 and of the body 2, so as to be respectively parallel to the axes X and Z of the system of axes X, Y, Z linked to the body 2 of the vehicle. That is to say that the axis X 'is horizontal and the axis Z' vertical. It is in this position that the performances of the two elastic joints 3 in acoustic filtering prove to be the best.
  • each articulation 3 is oriented strictly vertically and its orientation may be between the limits of + 45 ° and - 45 ° with respect to a perpendicular to the horizontal plane defined by the X and Y axes of the reference system linked to the vehicle body.
  • the minima and maxima of the corrugated profile of each of the two end faces 7a and 7b of the sleeve 7 are angularly equidistant along the circumference.
  • the maximum radial stiffness (longitudinal stiffness along X) of each articulation 3 can be approximately 3,500 N / mm, and the minimum radial stiffness (vertical stiffness along Z) of around 2,200 N / mm.
  • the elastic joint 3 with variable radial stiffness according to the invention has, with respect to the elastic joints with variable radial stiffness previously known, better resistance to fatigue both when the joint works in compression / traction than when it works in torsion. We can think that this is due to the continuous and regular evolution of the corrugated profile of its two end faces 7a and 7b, which means that, in service, the compressive / tensile stresses and the torsional stresses do not remain concentrated. in localized areas of the sleeve 7, but can be more easily distributed in the heart of said sleeve, over its entire circumference.
  • the sleeve 7 made of elastomeric material has been shown with a longitudinal section which preferably has substantially the shape of a trapezoid, the large base of which is situated on the side of the internal frame 8 and the small base on the side of the outer frame 9, and with inner peripheral lips 7c and 7d and outer peripheral lips 7e and 7f on the end faces 7a and 7b, as shown in particular in FIG. 2, the longitudinal section of the sleeve 7 could for example have a rectangular shape.
  • the number of minima and the number of maxima in the profile along the circumference of the or each of the faces end of the sleeve of elastomeric material is not necessarily equal to two. This number can be equal to one or greater than two depending on the number of radial directions along which it is desired that the sleeve of elastomeric material have respectively a minimum radial stiffness and a maximum radial stiffness.
  • the peak-to-peak amplitude of the ripple (difference in amplitude between the minima and the maxima) of the profile Pi in the inner peripheral region of a face of end 7a or 7b of the sleeve 7 is equal to or substantially equal to the peak-to-peak amplitude of the undulation of the profile P e in the outer peripheral region of said end face 7a or 7b
  • the two profiles Pi and P e can have different peak-to-peak amplitudes and, in a borderline case, one of the two profiles Pj and P e may have a peak to peak amplitude zero or almost zero.
  • the profile of the end face or faces of the sleeve which evolves continuously in the circumferential direction of the sleeve, can be combined with a continuous variation of the thickness.
  • radial of said sleeve along the circumference of the latter, so that the cross section of the housing 14 of the beam 9 and / or the cross section of the frame 8 are not necessarily circular, but may for example have an elliptical shape or oval, or a shape with one or more flats.
  • Such non-circular shapes can also be made necessary for various other reasons, such as for example the type of connection between the frame 8 and the arm 4.
  • the circular or cylindrical configuration of the housing 14 and of the inner frame 8 remains the most favorable in terms of fatigue, because the constraints prevailing in service in the sleeve 7 are the most homogeneous there.
  • connection of the external reinforcement or spar 9 to the body 2 by two bearing surfaces and two perpendicular screws represents only a very particular case of mounting. More generally, it is possible to anchor or embed the beam on the body in various ways. Screw connection is a possibility (in this case, the minimum is a screw, therefore a through hole, by joint). Mention may also be made of welding or bonding as other fixing possibilities.

Abstract

The invention concerns an elastic articulation designed to be linked to a vehicle body suspension arm and capable of operating in torsion and of carrying a substantial part of the body weight, comprising an inner reinforcement (8), an outer reinforcement (9) enclosing the inner reinforcement, and an elastomeric sleeve (7), arranged between the inner and outer reinforcements and whereof the inner and outer peripheral surfaces are linked without any possibility of sliding to said inner and outer reinforcements. The invention is characterised in that the outer reinforcement (9) is configured so as to be able to be fixed directly to the body of a vehicle, without any intermediate rigid support part.

Description

ARTICULATION ÉLASTIQUE POUR SUSPENSION DE VÉHICULE La présente invention concerne d'une manière générale les articulations élastiques et plus spécialement une articulation élastique destinée à relier un bras de suspension à une caisse de véhicule et capable de travailler en torsion et de porter une partie substantielle du poids de la caisse.The present invention relates generally to elastic joints and more particularly to an elastic joint intended to connect a suspension arm to a vehicle body and capable of working in torsion and of carrying a substantial part of the weight. from the cash register.
Dans le présent texte, on entend par "articulation élastique capable de travailler en torsion et de porter une partie substantielle du poids de la caisse du véhicule", une articulation ayant une raideur torsionnelle, autour de l'axe de l'articulation, telle que celle-ci soit capable de supporter une partie substantielle du poids de la caisse du véhicule sans qu'il soit nécessaire d'adjoindre aux bras de suspension des roues du véhicule de forts ressorts métalliques ou d'autres éléments élastiques pour supporter le poids de la caisse. Pour fixer les idées, les constructeurs d'automobiles exigent usuellement une raideur verticale, au niveau de chaque roue, qui varie selon les véhicules de tourisme dans une plage de l'ordre de 8 à 20 N/mm. Pour obtenir ce résultat, les articulations élastiques proposées ont, selon les longueurs des bras de suspension de roue, une rigidité torsionnelle comprise entre 10 et 40 m.N/degré. A titre de comparaison, une articulation élastique classique, placée au même endroit sur le même véhicule et conçue pour travailler essentiellement en compression, qui ne porte pas le poids de la caisse du véhicule, a généralement une rigidité torsionnelle inférieure à 1 m.N/degré. La présente invention est applicable notamment, mais non exclusivement, à une articulation élastique à raideur radiale variable, dont la raideur radiale a une valeur minimale le long d'un premier axe de référence d'un système de trois axes de référence, dont un second axe de référence est confondu avec l'axe de rotation de l'articulation élastique. On entend ici par "raideur radiale" la raideur de l'articulation dans n'importe quelle direction perpendiculaire à l'axe de rotation de l'articulation. Usuellement, dans le cas d'une articulation élastique pour suspension de véhicule, le "premier axe de référence" susmentionné est orienté pe endiculairement ou sensiblement perpendiculairement à un plan horizontal de repère lié à la caisse du véhicule. Par "plan horizontal de repère lié à la caisse", on entend ici un plan qui se déplace parallèlement au sol pendant le roulage du véhicule dans des conditions normales.In the present text, the expression “elastic articulation capable of working in torsion and of carrying a substantial part of the weight of the vehicle body” means an articulation having a torsional stiffness, around the axis of the articulation, such that the latter is capable of supporting a substantial part of the weight of the vehicle body without the need to add to the suspension arms of the vehicle wheels strong metal springs or other elastic elements to support the weight of the checkout. To fix ideas, automobile manufacturers usually require a vertical stiffness, at the level of each wheel, which varies according to passenger vehicles in a range of the order of 8 to 20 N / mm. To obtain this result, the elastic joints proposed have, depending on the lengths of the wheel suspension arms, a torsional stiffness of between 10 and 40 mN / degree. For comparison, a conventional elastic joint, placed in the same place on the same vehicle and designed to work essentially in compression, which does not bear the weight of the vehicle body, generally has a torsional rigidity of less than 1 mN / degree. The present invention is applicable in particular, but not exclusively, to an elastic joint with variable radial stiffness, the radial stiffness of which has a minimum value along a first reference axis of a system of three reference axes, including a second reference axis coincides with the axis of rotation of the elastic joint. The term "radial stiffness" is understood here to mean the stiffness of the joint in any direction perpendicular to the axis of rotation of the joint. Usually, in the case of an elastic articulation for vehicle suspension, the aforementioned "first reference axis" is oriented pe endicularly or substantially perpendicular to a horizontal reference plane linked to the vehicle body. By "horizontal reference plane linked to the body" is meant here a plane which moves parallel to the ground while the vehicle is running under normal conditions.
Des articulations élastiques à raideur radiale variable sont déjà bien connues, notamment par le brevet européen EP 0 956 984 de la demanderesse. L'articulation élastique décrite dans ce document comprend une armature cylindrique intérieure, une armature cylindrique extérieure entourant concentriquement l'armature intérieure, et un manchon en matériau élastomérique, qui est disposé entre les armatures intérieure et extérieure et dont les surfaces périphériques intérieure et extérieure sont liées sans possibilité de glissement auxdites armatures intérieure et extérieure. Le manchon en matériau élastomérique comporte au moins une alvéole, de préférence deux alvéoles diamétralement opposées, qui sont positionnées de telle façon que l'articulation présente une raideur radiale minimale le long du premier axe de référence susmentionné.Elastic joints with variable radial stiffness are already well known, in particular by European patent EP 0 956 984 of the applicant. The elastic articulation described in this document comprises an internal cylindrical reinforcement, an external cylindrical reinforcement concentrically surrounding the internal reinforcement, and a sleeve of elastomeric material, which is disposed between the internal and external reinforcement and whose inner and outer peripheral surfaces are linked without possibility of sliding to said interior and exterior frames. The sleeve of elastomeric material comprises at least one cell, preferably two diametrically opposite cells, which are positioned in such a way that the articulation has a minimum radial stiffness along the first above-mentioned reference axis.
En service, l'une des armatures de l'articulation élastique, par exemple l'armature extérieure, est fixée rigidement à une pièce de support solidaire de la caisse du véhicule tandis que l'autre armature, par exemple rarmature intérieure est liée rigidement au bras de suspension. La fixation de rarmature extérieure à la pièce de support est usuellement effectuée par une opération d'emmanchement ou emboîtement à force de l'armature extérieure dans un alésage de la pièce de support.In service, one of the reinforcements of the elastic articulation, for example the external reinforcement, is rigidly fixed to a support piece integral with the body of the vehicle while the other reinforcement, for example internal reinforcement is rigidly linked to the suspension arms. The fixing of the external reinforcement to the support part is usually carried out by a press fit or fitting operation of the external reinforcement in a bore of the support part.
Cette technique de fixation par emmanchement est relativement compliquée. En effet, elle implique une maîtrise de l'effort d'emmanchement et, préalablement à l'opération d'emmanchement proprement dite, des traitements de l'armature extérieure et/ou de l'alésage de la pièce de support. Ces traitements peuvent consister par exemple en une opération de lubrification pour faciliter l'insertion de l'armature extérieure dans l'alésage de la pièce de support, et/ou en des opérations de calibrage de la surface périphérique extérieure de l'armature extérieure ou de la surface intérieure de l'alésage de la pièce de support. Ces dernières opérations de calibrage peuvent être nécessaires afin d'éliminer tout défaut de surface, par exemple une éventuelle ovalisation de l'armature extérieure et/ou de l'alésage de la pièce de support, et afin d'assurer ainsi un contact uniforme, donc un serrage ou frettage uniforme de rarmature extérieure dans l'alésage de la pièce de support, sur toute la circonférence et sur toute la longueur de l'emmanchement.This fitting technique by fitting is relatively complicated. Indeed, it involves controlling the fitting force and, prior to the fitting operation proper, treatments of the external frame and / or the bore of the support part. These treatments may consist, for example, of a lubrication operation to facilitate the insertion of the external frame into the bore of the support piece, and / or of calibration operations of the external peripheral surface of the external frame or of the inner surface of the bore of the support part. These latter calibration operations may be necessary in order to eliminate any surface defect, for example possible ovalization of the external frame and / or of the bore of the support piece, and in order to thus ensure uniform contact, therefore a uniform tightening or shrinking of the external reinforcement in the bore of the support piece, over the entire circumference and over the entire length of the fitting.
Etant donné que la pièce de support maintient l'armature extérieure par serrage ou frettage, elle doit donc être capable de résister aux contraintes de frettage en service. Ceci implique que la paroi (toile) de la pièce de support, qui entoure l'armature extérieure de l'articulation élastique, ait une forte épaisseur.Since the support piece maintains the external reinforcement by clamping or shrinking, it must therefore be able to withstand the stresses of shrinking in service. This implies that the wall (fabric) of the support piece, which surrounds the outer frame of the elastic joint, has a high thickness.
En outre, dans le cas où le manchon en matériau élastomérique de l'articulation élastique n'a pas une forme axisymétrique, comme cela est par exemple le cas avec une articulation élastique à raideur radiale variable telle que celle qui est décrite dans la demande de brevet européen précitée, dans laquelle l'articulation élastique a une raideur radiale minimale le long d'un axe de référence, il est nécessaire que l'armature extérieure de l'articulation élastique soit introduite dans l'alésage de la pièce de support avec une orientation ou azimut précis, de telle façon que, en service, après fixation de la pièce de support à la caisse d'un véhicule, l'axe de référence le long duquel l'articulation élastique présente sa raideur radiale minimale soit correctement orienté par rapport à un système d'axes de référence lié à la caisse du véhicule. Avec la technique d'emmanchement ou emboîtement à force susmentionnée, si l'armature extérieure n'a pas été introduite dans l'alésage de la pièce de support avec l'orientation précise requise, il est très difficile, voire impossible, de rectifier ensuite l'orientation ou azimutage de l'armature extérieure dans l'alésage de la pièce de support. En outre, il est nécessaire de garantir un certain degré de serrage entre l'armature extérieure de l'articulation élastique et la pièce de support. En effet, il faut assurer entre ces deux éléments un niveau de pression de frettage tel que, en service, l'assemblage emmanché entre l'armature extérieure et la pièce de support présente une bonne résistance au glissement de ces deux éléments l'un dans l'autre, aussi bien dans le sens axial que dans le sens circonférentiel, et cela avec un certain coefficient de sécurité par rapport à un effort axial maximal et/ou un couple maximal subi par l'articulation élastique pour une sollicitation maximale de choc. Cela impose un choix approprié des matériaux constituant l'armature extérieure et la pièce de support, éventuellement des traitements de ces éléments, afin d'obtenir un frottement approprié à la résistance désirée au glissement. A cet égard, on notera que pour faciliter l'emmanchement de l'armature extérieure de l'articulation élastique dans l'alésage de la pièce de support, on a intérêt à ce que les frottements entre ces deux pièces soient les plus faibles possibles. D'un autre côté, pour assurer la résistance désirée au glissement, avec le coefficient désiré de sécurité, on a intérêt à ce que les f ottements soient les plus grands possibles. Ces deux exigences sont donc en totale contradiction, de sorte qu'il est difficile de les satisfaire toutes les deux en même temps. La présente invention a donc pour but de remédier aux problèmes susmentionnés posés par les articulations élastiques antérieurement connues, dans lesquelles l'armature extérieure de l'articulation élastique est emmanchée à force dans l'alésage d'une pièce de support. La présente invention a également pour but de fournir une articulation élastique à raideur radiale variable, présentant une tenue améliorée à la fatigue aussi bien sous des sollicitations de compression/traction que sous des sollicitations torsionnelles.In addition, in the case where the sleeve of elastomeric material of the elastic joint does not have an axisymmetric shape, as is for example the case with an elastic joint with variable radial stiffness such as that described in the application for European patent cited above, in which the elastic joint has a minimum radial stiffness along a reference axis, it is necessary that the external reinforcement of the elastic joint is introduced into the bore of the support part with a precise orientation or azimuth, so that, in service, after fixing the support piece to the body of a vehicle, the reference axis along which the elastic articulation has its minimum radial stiffness is correctly oriented relative to a system of reference axes linked to the vehicle body. With the above-mentioned force fitting or interlocking technique, if the external reinforcement has not been introduced into the bore of the support part with the precise orientation required, it is very difficult, if not impossible, to then rectify the orientation or azimuth of the external reinforcement in the bore of the support part. In addition, it is necessary to guarantee a certain degree of tightness between the external reinforcement of the elastic joint and the support piece. Indeed, it is necessary to ensure between these two elements a level of hooping pressure such that, in service, the assembly fitted between the outer frame and the support part has good resistance to sliding of these two elements, one in the other, both in the axial direction and in the circumferential direction, and this with a certain coefficient of safety with respect to a maximum axial force and / or a maximum torque undergone by the elastic joint for a maximum impact stress. This requires an appropriate choice of materials constituting the external reinforcement and the support part, possibly treatments of these elements, in order to obtain an appropriate friction for the desired slip resistance. In this regard, it will be noted that in order to facilitate fitting of the external frame of the elastic articulation in the bore of the support piece, it is advantageous for the friction between these two pieces to be as low as possible. On the other hand, to ensure the desired resistance to sliding, with the desired coefficient of safety, it is advantageous for the friction to be as large as possible. These two requirements are therefore in total contradiction, so that it is difficult to meet them both at the same time. The present invention therefore aims to remedy the aforementioned problems posed by previously known elastic joints, in which the outer frame of the elastic joint is force fitted into the bore of a support piece. The present invention also aims to provide an elastic joint with variable radial stiffness, having improved resistance to fatigue both under compression / traction stresses and under torsional stresses.
A cet effet, l'invention fournit une articulation élastique destinée à relier un bras de suspension à une caisse de véhicule et capable de porter une partie substantielle du poids de la caisse, comprenant une armature intérieure, une armature extérieure entourant rarmature intérieure, et un manchon en matériau élastomérique, qui est disposé entre les armatures intérieure et extérieure et dont les surfaces périphériques intérieure et extérieure sont liées sans possibilité de glissement auxdites armatures intérieure et extérieure. Le premier but de l'invention est atteint par le fait que l'armature extérieure est conformée de façon à pouvoir être fixée directement à la caisse d'un véhicule.To this end, the invention provides an elastic articulation intended to connect a suspension arm to a vehicle body and capable of carrying a substantial part of the weight of the body, comprising an internal frame, an external frame surrounding the internal frame, and a sleeve made of elastomeric material, which is disposed between the interior and exterior reinforcements and the interior and exterior peripheral surfaces of which are linked without the possibility of sliding to said interior and exterior reinforcements. The first object of the invention is achieved by the fact that the external frame is shaped so that it can be fixed directly to the body of a vehicle.
Par l'expression "fixée directement", on entend ici que l'armature extérieure est fixée à la caisse du véhicule sans pièce intermédiaire rigide de support, mais il ne doit pas être exclus qu'un ou plusieurs blocs de caoutchouc ou autre matériau similaire peuvent être interposés entre l'armature extérieure et la caisse.By the expression "fixed directly" is meant here that the external frame is fixed to the body of the vehicle without a rigid intermediate support piece, but it should not be excluded that one or more blocks of rubber or other similar material can be interposed between the external frame and the body.
Ainsi, dans l'articulation élastique selon l'invention, ladite armature extérieure joue à la fois le rôle d'une armature extérieure d'une articulation élastique connue et le rôle de la pièce de support dans laquelle l'armature extérieure de l'articulation élastique connue devait auparavant être emmanchée à force pour permettre ensuite la fixation de l'articulation élastique à la caisse du véhicule.Thus, in the elastic articulation according to the invention, said external reinforcement plays both the role of an external reinforcement of a known elastic articulation and the role of the support part in which the external reinforcement of the known elastic joint had previously to be force-fitted to then allow the elastic joint to be fixed to the vehicle body.
En conséquence, grâce à la présente invention, il est possible de supprimer complètement l'opération d'emmanchement qui était nécessaire avec l'articulation élastique connue, d'où un gain en coût industriel au niveau de l'assemblage des éléments de la suspension du véhicule (gain de temps de production et gain d'outillage de production, puisque le poste d'emmanchement peut être supprimé). L'invention permet également d'obtenir une économie de matière et une réduction de poids. En effet, dans un mode de réalisation de l'invention, l'armature extérieure de l'articulation élastique peut être constituée par une pièce coulée ou filée, sous la forme d'un longeronnet comportant un logement, dans lequel le manchon en matériau élastomérique est formé par moulage et adhérisé directement à la surface du logement. Avec un tel mode de réalisation, par rapport à une articulation élastique connue dans laquelle l'armature extérieure est emmanchée à force dans l'alésage d'un longeronnet, non seulement l'invention permet de supprimer une masse de matière correspondant à celle de l'armature extérieure de l'articulation élastique connue, mais en outre la partie (toile) du longeronnet qui entoure le manchon en matériau élastomérique peut avoir une épaisseur de paroi plus petite que celle du longeronnet associé à l'articulation élastique connue. En effet, du fait de l'absence d'emmanchement serré, il suffit que l'épaisseur de la toile du longeronnet soit dimensionnée par rapport à la tenue aux pressions d'injection de moulage et non plus par rapport à la tenue à des contraintes de frettage qui conduisent à des épaisseurs importantes de toile. Bien entendu, l'épaisseur de la toile doit aussi être dimensionnée pour supporter les contraintes de service. La présente invention est applicable aussi bien à une articulation élastique ayant une raideur radiale constante, qu'à une articulation élastique ayant une raideur variable, en particulier une raideur minimale le long d'une direction radiale qui, après fixation de l'articulation élastique à la caisse d'un véhicule, doit avoir une orientation désirée par rapport à un système d'axes de référence lié à la caisse du véhicule. Dans le second cas, l'azimutage nécessaire pour orienter la raideur radiale minimale du manchon en matériau élastomérique par rapport au longeronnet constituant l'armature extérieure, donc par rapport à la caisse du véhicule, peut être effectué facilement et directement par un positionnement approprié de l'empreinte du moule d'injection par rapport au longeronnet dans le logement duquel le manchon élastomère est moulé. Par exemple, on peut prévoir sur le longeronnet et sur les deux empreintes du moule destinées à être placées aux extrémités du logement du longeronnet, des repères, encoches, détrompeurs ou autres moyens d'indexation coopérant les uns avec les autres pour assurer un positionnement correct des deux empreintes du moule par rapport au longeronnet.Consequently, thanks to the present invention, it is possible to completely eliminate the fitting operation which was necessary with the known elastic joint, hence a gain in industrial cost in terms of the assembly of the elements of the suspension. of the vehicle (saving production time and saving production tools, since the fitting position can be eliminated). The invention also makes it possible to obtain a saving of material and a reduction in weight. In fact, in one embodiment of the invention, the external reinforcement of the elastic joint can be constituted by a cast or spun piece, in the form of a spar comprising a housing, in which the sleeve made of elastomeric material is formed by molding and adhered directly to the surface of the housing. With such an embodiment, with respect to a known elastic articulation in which the external reinforcement is force-fitted into the bore of a beam, not only does the invention make it possible to remove a mass of material corresponding to that of the 'external reinforcement of the known elastic joint, but in addition the part (fabric) of the spar which surrounds the sleeve of elastomeric material may have a wall thickness less than that of the spar associated with the known elastic joint. Indeed, due to the absence of tight fitting, it suffices that the thickness of the fabric of the beam is dimensioned in relation to the resistance to injection molding pressures and no longer in relation to the resistance to stresses hooping which lead to significant thicknesses of fabric. Of course, the thickness of the fabric must also be dimensioned to withstand the service constraints. The present invention is applicable both to an elastic joint having a constant radial stiffness, and to an elastic joint having a variable stiffness, in particular a minimum stiffness along a radial direction which, after fixing the elastic joint to the body of a vehicle, must have a desired orientation with respect to a system of reference axes linked to the body of the vehicle. In the second case, the azimuth necessary to orient the minimum radial stiffness of the sleeve of elastomeric material relative to the spar constituting the outer frame, therefore relative to the vehicle body, can be carried out easily and directly by an appropriate positioning of the impression of the injection mold relative to the spar in the housing of which the elastomeric sleeve is molded. For example, one can provide on the spar and on the two mold cavities intended to be placed at the ends of the spar housing, marks, notches, polarizing or other indexing means cooperating with each other to ensure correct positioning of the two mold cavities relative to the beam.
En outre, du fait de l'absence de liaison par emmanchement dans l'articulation élastique selon l'invention, les opérations de traitement de calibrage et/ou de lubrification, qui étaient nécessaires avec les articulations élastiques connues, sont supprimées. En particulier, la surface du logement du longeronnet ne nécessite plus de préparation spécifique à un emmanchement. De plus, les problèmes de tenue au glissement dans le sens axial comme dans le sens circonférientiel, qui se posent avec les articulations élastiques connues comportant une liaison par emmanchement entre rarmature extérieure et le longeronnet, sont aussi complètement supprimés. Dans l'articulation élastique selon l'invention, la tenue aux sollicitations axiales et/ou torsionnelles auxquelles l'articulation est soumise en service, est gérée par l'interface collée entre le manchon en matériau élastomérique et le longeronnet. La liaison collée entre le manchon en matériau élastomérique et le longeronnet est assurée par des colles dont la résistance au cisaillement et au déchirement apporte une marge de sécurité suffisante par rapport aux valeurs maximales des contraintes vues, en service, par l'articulation au niveau du diamètre extérieur du manchon en matériau élastomérique. Les colles utilisées à cet effet peuvent être les mêmes que celles qui sont usuellement utilisées dans les articulations élastiques connues pour lier le manchon en matériau élastomérique à l'armature extérieure et à l'armature intérieure de l'articulation.In addition, due to the absence of a fitting connection in the elastic joint according to the invention, the operations of calibration treatment and / or lubrication, which were necessary with the known elastic joints, are eliminated. In particular, the surface of the beam member housing no longer requires specific preparation for fitting. In addition, the problems of resistance to sliding in the axial direction as in the circumferential direction, which arise with known elastic joints comprising a fitting connection between the external reinforcement and the beam, are also completely eliminated. In the elastic joint according to the invention, the resistance to axial and / or torsional stresses to which the joint is subjected in service, is managed by the bonded interface between the sleeve of elastomeric material and the beam. The bonded bond between the sleeve of elastomeric material and the beam is provided by adhesives whose resistance to shearing and tearing provides a sufficient margin of safety compared to the maximum values of the stresses seen, in service, by the articulation at the level of the outer diameter of the sleeve of elastomeric material. The adhesives used for this purpose can be the same as those which are usually used in the elastic joints known for bonding the sleeve of elastomeric material to the external frame and to the internal frame of the joint.
Le manchon en matériau élastomérique peut comporter de façon connue en soi, dans au moins une de ses faces d'extrémité, au moins un creux qui est positionné de telle façon que l'articulation ait une raideur radiale minimale le long d'un premier axe de référence d'un système de trois axes de référence, dont un second axe de référence est confondu avec l'axe de rotation de l'articulation élastique. Dans ce cas, le second but de l'invention est atteint par le fait qu'au moins une des deux faces d'extrémité du manchon a un profil qui évolue de façon continue dans le sens circonférentiel du manchon en matériau élastomérique entre au moins un minimum et au moins un maximum.The sleeve of elastomeric material may comprise in a manner known per se, in at least one of its end faces, at least one recess which is positioned so that the joint has a minimum radial stiffness along a first reference axis of a system of three reference axes, a second reference axis of which coincides with the axis of rotation of the elastic joint. In this case, the second object of the invention is achieved by the fact that at least one of the two end faces of the sleeve has a profile which evolves continuously in the circumferential direction of the sleeve of elastomeric material between at least one minimum and at least a maximum.
De préférence, les deux faces d'extrémité du manchon ont un profil ondulé. De préférence, le profil a une forme sensiblement sinusoïdale ou pseudo-sinusoïdale.Preferably, the two end faces of the sleeve have a corrugated profile. Preferably, the profile has a substantially sinusoidal or pseudo-sinusoidal shape.
De préférence, le profil, dans la région périphérique intérieure de ladite face d'extrémité, a au moins un minimum et au moins un maximum qui sont décalés d'un angle prédéfini respectivement par rapport à au moins un minimum et au moins un maximum du profil dans la région périphérique extérieure de ladite face d'extrémité lorsqu'aucune charge n'est appliquée à l'articulation.Preferably, the profile, in the inner peripheral region of said end face, has at least a minimum and at least a maximum which are offset by a predefined angle respectively with respect to at least a minimum and at least a maximum of the profile in the outer peripheral region of said end face when no load is applied to the joint.
Dans ce cas, ledit angle prédéfini est de préférence choisi de telle façon que, lorsque l'articulation est soumise à une charge de référence provoquant une rotation relative dudit angle prédéfini des armatures intérieure et extérieure l'une par rapport à l'autre, les lieux géométriques des minima et les lieux géométriques des maxima du profil entre lesdites régions périphériques intérieure et extérieure sont orientés sensiblement radialement respectivement le long du premier axe de référence et le long d'un troisième axe de référence du système de trois axes de référence.In this case, said predefined angle is preferably chosen in such a way that, when the articulation is subjected to a reference load causing a relative rotation of said predefined angle of the internal and external reinforcements with respect to each other, the geometric places of the minima and the geometric places of the maxima of the profile between said inner and outer peripheral regions are oriented substantially radially respectively along the first reference axis and along a third reference axis of the system of three reference axes.
De préférence, le longeronnet formant l'armature extérieure comporte au moins une face d'appui, de préférence deux faces d'appui, apte à coopérer avec au moins une face correspondante d'appui sur la caisse du véhicule, de telle sorte que, après fixation du longeronnet à ladite caisse, les trois axes de référence de l'articulation élastique aient des orientations prédéfinies par rapport à un système d'axes de référence lié à la caisse du véhicule.Preferably, the beam forming the external reinforcement comprises at least one bearing face, preferably two bearing faces, capable of cooperating with at least one corresponding bearing face on the body of the vehicle, so that, after fixing the beam to said body, the three reference axes of the elastic joint have predefined orientations with respect to a system of reference axes linked to the vehicle body.
De préférence, le premier axe de référence est sensiblement perpendiculaire à un plan horizontal lié à la caisse du véhicule. D'autres caractéristiques et avantages de l'invention apparaîtront dans la description suivante d'un mode de réalisation de l'invention donné à titre d'exemple en référence aux dessins annexés, sur lesquels : - la figure 1 représente de manière très schématique un essieu de véhicule incorporant deux articulations élastiques selon l'invention ;Preferably, the first reference axis is substantially perpendicular to a horizontal plane linked to the vehicle body. Other characteristics and advantages of the invention will appear in the following description of an embodiment of the invention given by way of example with reference to the appended drawings, in which: - Figure 1 very schematically shows a vehicle axle incorporating two elastic joints according to the invention;
- la figure 2 est une vue en perspective de l'une des deux articulations élastiques incorporées dans l'essieu de la figure 1 ;- Figure 2 is a perspective view of one of the two elastic joints incorporated in the axle of Figure 1;
- la figure 3 est une vue en coupe horizontale de l'articulation élastique de la figure 2 ;- Figure 3 is a horizontal sectional view of the elastic joint of Figure 2;
- la figure 4 est une vue en élévation, à l'état libre, du manchon en matériau élastomérique de l'articulation élastique des figures 2 et 3 ;- Figure 4 is an elevational view, in the free state, of the sleeve of elastomeric material of the elastic joint of Figures 2 and 3;
- la figure 5 est une vue du manchon en matériau élastomérique suivant la flèche F de la figure 4 ; - la figure 6 est une vue semblable à la figure 4 et montre la forme du manchon en matériau élastomérique lorsqu'il est soumis à une charge torsionnelle de référence ;- Figure 5 is a view of the sleeve of elastomeric material along arrow F of Figure 4; - Figure 6 is a view similar to Figure 4 and shows the shape of the sleeve of elastomeric material when subjected to a reference torsional load;
- la figure 7 est une vue semblable à la figure 5, le manchon en matériau élastomérique étant soumis à la charge torsionnelle de référence ;- Figure 7 is a view similar to Figure 5, the sleeve of elastomeric material being subjected to the reference torsional load;
- la figure 8 est une vue en coupe suivant la ligne brisée VIII- VIII de la figure 7 ;- Figure 8 is a sectional view along the broken line VIII-VIII of Figure 7;
- la figure 9 est un graphique montrant le profil ondulé de l'une des faces d'extrémité du manchon en matériau élastomérique dans la région périphérique intérieure et dans la région périphérique extérieure dudit manchon, lorsque celui-ci est à l'état libre ;- Figure 9 is a graph showing the corrugated profile of one of the end faces of the sleeve of elastomeric material in the inner peripheral region and in the outer peripheral region of said sleeve, when the latter is in the free state;
- la figure 10 est un graphique montrant le profil ondulé de la face d'extrémité du manchon en matériau élastomérique dans la région périphérique intérieure et dans la région périphérique extérieure dudit manchon, lorsque celui-ci est soumis à la charge torsionnelle de référence.- Figure 10 is a graph showing the corrugated profile of the end face of the sleeve of elastomeric material in the inner peripheral region and in the outer peripheral region of said sleeve, when the latter is subjected to the reference torsional load.
En se reportant à la figure 1, on peut voir un essieu 1, plus précisément un essieu arrière, destiné à être monté sur la caisse 2 d'un véhicule par l'intermédiaire d'articulations élastiques 3, dont une forme de réalisation avantageuse sera décrite en détail plus loin. Sur la figure 1, on a également représentée un système de trois axes de référence X, Y et Z lié à la caisse du véhicule. L'axe X est l'axe médian longitudinal du véhicule, l'axe Y est un axe transversal, qui définit avec l'axe X le plan horizontal de repère mentionné plus haut, et l'axe Z est vertical.Referring to FIG. 1, one can see an axle 1, more precisely a rear axle, intended to be mounted on the body 2 of a vehicle by means of elastic joints 3, an advantageous embodiment of which will be described in detail later. In FIG. 1, a system of three reference axes X, Y and Z linked to the vehicle body. The X axis is the longitudinal median axis of the vehicle, the Y axis is a transverse axis, which defines with the X axis the horizontal reference plane mentioned above, and the Z axis is vertical.
L'essieu 1 comporte essentiellement deux bras tirés de suspension 4 qui sont reliés à la caisse 2 par des articulations élastiques 3 capables de travailler en compression/traction et en torsion de telle façon que les deux bras de suspension 4 puissent avoir, indépendamment l'un de l'autre, un débattement angulaire limité par rapport à la caisse 2 autour de l'axe 6 des articulations 3, qui est confondu avec l'axe Y. Dans les figures 2 et 3, on a représenté l'une des deux articulations 3, qui sont similaires (symétriques, en général). Comme montré dans les figures 2 et 3, l'articulation 3 est essentiellement constituée par un manchon 7 en matériau élastomérique, qui est disposé entre une armature cylindrique intérieure 8 et une armature extérieure 9 et qui est fixé rigidement à ces deux armatures, sans possibilité de glissement, par la technique connue d'adhérisation.The axle 1 essentially comprises two drawn suspension arms 4 which are connected to the body 2 by elastic articulations 3 capable of working in compression / traction and in torsion so that the two suspension arms 4 can independently have the one from the other, a limited angular movement relative to the body 2 around the axis 6 of the joints 3, which coincides with the axis Y. In Figures 2 and 3, one of the two has been shown joints 3, which are similar (symmetrical, in general). As shown in Figures 2 and 3, the joint 3 is essentially constituted by a sleeve 7 of elastomeric material, which is disposed between an inner cylindrical frame 8 and an outer frame 9 and which is rigidly fixed to these two frames, without possibility sliding, by the known technique of adhesion.
En revenant à la figure 1, on peut voir que chaque bras de suspension 4 porte, du côté de l'articulation élastique 3 correspondante, un arbre 11 et, du côté opposé à ladite articulation, une fusée 12 destinée à recevoir une roue 13, plus précisément une roue arrière du véhicule. Chacun des deux arbres 11, dont les axes sont alignés avec l'axe 6 des articulations élastiques 3 et avec l'axe Y, est fixé rigidement, c'est-à-dire sans rotation relative possible, à l'armature intérieure 8 de l'articulation élastique correspondante. Par exemple, la fixation de l'arbre 11 à rarmature intérieure 8 peut être effectuée par emboîtement à force, par collage ou par toute autre technique connue dans ce domaine de la technique. En outre, il peut être prévu une traverse (non montrée) qui relie les deux arbres 11 selon une configuration en U, ou les deux bras 4 selon une configuration en H. La traverse peut avoir une structure semblable à celle décrite dans la demande de brevet EP 0 956 984 ou dans la demande de brevet WO 97/47 486.Returning to FIG. 1, it can be seen that each suspension arm 4 carries, on the side of the corresponding elastic articulation 3, a shaft 11 and, on the side opposite to said articulation, a rocket 12 intended to receive a wheel 13, more precisely a rear wheel of the vehicle. Each of the two shafts 11, the axes of which are aligned with the axis 6 of the elastic joints 3 and with the axis Y, is rigidly fixed, that is to say without possible relative rotation, to the internal reinforcement 8 of the corresponding elastic joint. For example, the fixing of the shaft 11 with internal reinforcement 8 can be carried out by force fitting, by gluing or by any other technique known in this field of the technique. In addition, a cross-member (not shown) can be provided which connects the two shafts 11 in a U-shaped configuration, or the two arms 4 in a H-shaped configuration. The cross-member can have a structure similar to that described in the request for Patent EP 0 956 984 or in patent application WO 97/47 486.
En se reportant à nouveau aux figures 2 et 3, on peut voir que l'armature extérieure 9 de l'articulation élastique 3 est ici constituée par un longeronnet, réalisé par exemple sous la forme d'une pièce coulée ou filée en aluminium ou en alliage d'aluminium. Le longeronnet 9 présente un logement 14 dans lequel le manchon 7, en matériau élastomérique, de l'articulation élastique 3 est fixé rigidement.Referring again to Figures 2 and 3, we can see that the outer frame 9 of the elastic joint 3 is here constituted by a beam, made for example in the form of a cast or spun piece of aluminum or aluminum alloy. The beam 9 has a housing 14 in which the sleeve 7, made of elastomeric material, of the elastic joint 3 is rigidly fixed.
Le longeronnet 9 comporte au moins une face plane d'appui, de préférence deux faces planes d'appui 9a et 9b, qui sont 5 perpendiculaires l'une à l'autre et qui sont destinées à servir de surface de référence pour le montage du longeronnet 9 sur la caisse 2 du véhicule. La face plane 9b est perpendiculaire à l'axe du logement 14, donc aussi à l'axe Y de l'articulation élastique 3, et est destinée à être appliquée contre une surface verticale d'appui de la caisse 2, qui est parallèle au plan 0 défini par les axes X et Z du système de référence lié à la caisse du véhicule. La face plane d'appui 9a du longeronnet 9 est destinée à être appliquée contre une autre surface plane d'appui qui est prévue sur la caisse 2 du véhicule et qui est parallèle au plan horizontal défini par les deux axes X et Y du système de référence lié à la caisse du véhicule. 5 Le longeronnet 9 comporte en outre deux trous 15 et 16 dont les axes sont perpendiculaires respectivement aux faces planes d'appui 9a et 9b. Les trous 15 et 16 sont destinés à recevoir des vis ou des boulons (non montrés) et constituent, en combinaison avec lesdites vis ou boulons, des moyens d'ancrage pour la fixation du longeronnet 9 sur o les surfaces d'appui précitées de la caisse du véhicule.The spar 9 has at least one flat support face, preferably two flat support faces 9a and 9b, which are perpendicular to each other and which are intended to serve as a reference surface for mounting the spar 9 on the vehicle body 2. The flat face 9b is perpendicular to the axis of the housing 14, therefore also to the axis Y of the elastic joint 3, and is intended to be applied against a vertical support surface of the body 2, which is parallel to the plane 0 defined by the X and Z axes of the reference system linked to the vehicle body. The flat support face 9a of the beam 9 is intended to be applied against another flat support surface which is provided on the body 2 of the vehicle and which is parallel to the horizontal plane defined by the two axes X and Y of the system of reference linked to the vehicle body. 5 The spar 9 further comprises two holes 15 and 16 whose axes are perpendicular respectively to the flat bearing faces 9a and 9b. The holes 15 and 16 are intended to receive screws or bolts (not shown) and constitute, in combination with said screws or bolts, anchoring means for fixing the beam 9 on the abovementioned bearing surfaces of the vehicle body.
De préférence, chacune des deux articulations élastiques 3 est conçue pour présenter une raideur radiale variable dans le sens circonférentiel, c'est-à-dire que la raideur de l'articulation varie en fonction de l'angle polaire de la direction radiale autour de l'axe Y. 5 A cet effet, le manchon 7 peut avoir n'importe quelle structure ou géométrie connue propre à lui conférer une raideur radiale variable. Par exemple, le manchon 7 peut comporter des alvéoles comme ceux du manchon en matériau élastomérique de l'articulation élastique décrite dans la demande de brevet EP 0 956 984. o Toutefois, conformément à la présente invention, la variation de la raideur radiale est obtenue de préférence en donnant à au moins une des deux faces d'extrémité 7a et 7b du manchon 7 en matériau élastomérique, de préférence à ses deux faces d'extrémité, un profil qui évolue de façon continue dans le sens circonférentiel du manchon 7 entre 5 au moins un minimum et au moins un maximum, comme cela est notamment visible dans la figure 4. Le profil ondulé a, par exemple, une forme sinusoïdale ou pseudo-sinusoïdale avec deux minima et deux maxima sur la circonférence du manchon 7.Preferably, each of the two elastic joints 3 is designed to have a variable radial stiffness in the circumferential direction, that is to say that the stiffness of the joint varies as a function of the polar angle of the radial direction around the Y axis. 5 For this purpose, the sleeve 7 can have any known structure or geometry capable of giving it a variable radial stiffness. For example, the sleeve 7 may include cells like those of the sleeve of elastomeric material of the elastic joint described in patent application EP 0 956 984. However, in accordance with the present invention, the variation in the radial stiffness is obtained preferably by giving at least one of the two end faces 7a and 7b of the sleeve 7 of elastomeric material, preferably at its two end faces, a profile which evolves continuously in the circumferential direction of the sleeve 7 between 5 at least a minimum and at least a maximum, as is particularly visible in Figure 4. The corrugated profile has, for example, a sinusoidal or pseudo-sinusoidal shape with two minima and two maxima on the circumference of the sleeve 7.
Etant donné que l'articulation élastique est destinée à travailler non seulement en compression/traction, mais également en torsion pour porter une partie substantielle du poids de la caisse et pour assurer une fonction ressort de suspension, il est préférable que les deux minima mj et les deux maxima Mj du profil ondulé Pj dans la région périphérique intérieure de la face d'extrémité 7a ou 7b soient décalés angulairement d'un angle prédéfini α respectivement par rapport aux deux minima me et aux deux maxima Me du profil ondulé Pe dans la région périphérique extérieure de la face d'extrémité 7a ou 7b lorsque le manchon 7 n'est soumis à aucune charge, comme montré dans les figures 5 et 9. Entre les minima mj et me, les lieux géométriques 17 des minima du profil ondulé de la face d'extrémité 7a ou 7b du manchon 7 s'étendent obliquement par rapport à une direction radiale, comme montré dans la figure 5. De même, entre les maxima Mi et Me, les lieux géométriques 18 des maxima du profil ondulé de la face d'extrémité 7a ou 7b s'étendent obliquement par rapport à une autre direction radiale, comme cela est également montré dans la figure 5. La valeur de l'angle prédéfini α est choisie de telle façon que, lorsque l'articulation élastique 3 est soumise à une charge de référence provoquant une rotation relative de cet angle α, par exemple de l'armature intérieure 8 par rapport à l'armature extérieure 9 (longeronnet), le manchon 7 subit une torsion et se déforme de telle façon que les minima m.{ et les maxima Mj du profil ondulé P; dans la région périphérique intérieure de la face d'extrémité 7a ou 7b sont alignés radialement respectivement avec les minima me et les maxima Me du profil ondulé Pe dans la région périphérique extérieure de la face d'extrémité 7a ou 7b, comme montré dans les figures 7 et 10. Les lieux géométriques 17 des minima et les lieux géométriques 18 des maxima du profil ondulé sur chacune des deux faces d'extrémité 7a et 7b du manchon 7 sont alors orientés sensiblement radialement respectivement le long des deux axes de référence X' et Z' d'un système de trois axes de référence X', Y, Z' lié à chaque articulation élastique 3. Les deux axes X' et Z' sont perpendiculaires à l'axe Y des deux articulations élastiques 3, qui est aussi désigné par la référence 6 dans la figure 1. La charge de référence susmentionnée, qui détermine la valeur de l'angle α ainsi qu'une assiette de référence du véhicule comportant l'essieu 1 de la figure 1, équipé des deux articulations élastiques 3 selon l'invention, peut être définie par exemple comme étant la charge appliquée à chacune des deux roues 13 de l'essieu 1 pour un véhicule en ordre de marche en usage courant. Cette charge de référence va naturellement varier d'un modèle de véhicule à un autre et sa définition peut elle-même varier d'un constructeur de véhicules à un autre. Par exemple, pour un véhicule à quatre roues, la charge de référence peut être définie comme étant le quart de la somme du poids à vide du véhicule, du poids de deux mannequins de 75 kg chacun, et d'un poids de carburant correspondant à un réservoir de carburant à moitié plein.Since the elastic joint is intended to work not only in compression / traction, but also in torsion to carry a substantial part of the weight of the body and to ensure a spring suspension function, it is preferable that the two minima mj and the two maxima Mj corrugated profile Pj in the inner peripheral region of the end face 7a or 7b are angularly shifted by a predetermined angle α respectively with respect to both minimum e m and two maxima m e corrugated profile P e in the outer peripheral region of the end face 7a or 7b when the sleeve 7 is not subjected to any load, as shown in FIGS. 5 and 9. Between the minima mj and m e , the geometrical locations 17 of the minima of the corrugated profile of the end face 7a or 7b of the sleeve 7 extend obliquely with respect to a radial direction, as shown in FIG. 5. Likewise, between the maxima Mi and M e , the li them geometric 18 of the maxima of the corrugated profile of the end face 7a or 7b extend obliquely with respect to another radial direction, as is also shown in FIG. 5. The value of the predefined angle α is chosen from such that, when the elastic joint 3 is subjected to a reference load causing a relative rotation of this angle α, for example of the internal reinforcement 8 relative to the external reinforcement 9 (spar), the sleeve 7 undergoes a torsion and deforms in such a way that the minima m. {and the maxima Mj of the corrugated profile P; in the inner peripheral region of the end face 7a or 7b are aligned radially respectively with the minima m e and the maxima M e of the corrugated profile P e in the outer peripheral region of the end face 7a or 7b, as shown in FIGS. 7 and 10. The geometric locations 17 of the minima and the geometric locations 18 of the maxima of the corrugated profile on each of the two end faces 7a and 7b of the sleeve 7 are then oriented substantially radially respectively along the two reference axes X 'and Z' of a system of three reference axes X ', Y, Z' linked to each elastic joint 3. The two axes X 'and Z' are perpendicular to the Y axis of the two elastic joints 3, which is also designated by reference 6 in FIG. 1. The aforementioned reference load, which determines the value of the angle α as well as a reference attitude of the vehicle comprising the axle 1 of FIG. 1, equipped with the two elastic articulations 3 according to the invention, can be defined for example as being the load applied to each of the two wheels 13 of the axle 1 for a vehicle in running order in current use. This reference load will naturally vary from one vehicle model to another and its definition may itself vary from one vehicle manufacturer to another. For example, for a four-wheeled vehicle, the reference load can be defined as being a quarter of the sum of the empty weight of the vehicle, the weight of two mannequins of 75 kg each, and a weight of fuel corresponding to a half full fuel tank.
Avec la construction de l'articulation élastique 3 décrite ci- dessus, la longueur axiale du manchon 7 en matériau élastomérique a une valeur minimale £ en correspondance avec les lieux géométriques 17 des minima du profil ondulé des deux faces d'extrémité 7a et 7b, c'est-à- dire dans le plan défini par les deux axes Y et Z', et une valeur maximale L en correspondance avec les lieux géométriques 18 des maxima du profil ondulé des deux faces d'extrémité 7a et 7b, c'est-à-dire dans le plan défini par les deux axes Y et X', comme montré respectivement dans les moitiés gauche et droite de la figure 8. Etant donné que la raideur radiale d'un manchon en matériau élastomérique est, en première approximation, proportionnelle à la longueur axiale du manchon, l'articulation élastique 3 décrite ci-dessus aura donc une raideur radiale minimale le long de l'axe Z' et une raideur radiale maximale le long de l'axe X', lorsque le manchon est soumis à la charge de référence.With the construction of the elastic joint 3 described above, the axial length of the sleeve 7 of elastomeric material has a minimum value £ corresponding to the geometrical locations 17 of the minima of the corrugated profile of the two end faces 7a and 7b, that is to say in the plane defined by the two axes Y and Z ', and a maximum value L corresponding to the geometrical locations 18 of the maxima of the corrugated profile of the two end faces 7a and 7b, that is ie in the plane defined by the two axes Y and X ′, as shown respectively in the left and right halves of FIG. 8. Given that the radial stiffness of a sleeve made of elastomeric material is, as a first approximation, proportional to the axial length of the sleeve, the elastic joint 3 described above will therefore have a minimum radial stiffness along the axis Z 'and a maximum radial stiffness along the axis X', when the sleeve is subjected at the expense of the ref in this.
Lors du montage des deux articulations élastiques 3 sur la caisse 2, les axes X' et Z' de chaque articulation 3 sont orientés, grâce aux surfaces d'appui susmentionnées 9a et 9b des longeronnets 9 et de la caisse 2, de façon à être respectivement parallèles aux axes X et Z du système d'axes X, Y, Z lié à la caisse 2 du véhicule. C'est-à-dire que l'axe X' est horizontal et l'axe Z' vertical. C'est dans cette position que les performances des deux articulations élastiques 3 en filtrage acoustique s'avèrent les meilleures. Toutefois, il n'est pas absolument indispensable que l'axe Z' de chaque articulation 3 soit orienté rigoureusement verticalement et son orientation pourra être comprise entre des limites de + 45° et - 45° par rapport à une perpendiculaire au plan horizontal défini par les axes X et Y du système de référence lié à la caisse du véhicule. De même, il n'est pas non plus absolument indispensable que les minima et maxima du profil ondulé de chacune des deux faces d'extrémité 7a et 7b du manchon 7 soient angulairement équidistants le long de la circonférence.During the mounting of the two elastic articulations 3 on the body 2, the axes X 'and Z' of each articulation 3 are oriented, by virtue of the abovementioned bearing surfaces 9a and 9b of the side members 9 and of the body 2, so as to be respectively parallel to the axes X and Z of the system of axes X, Y, Z linked to the body 2 of the vehicle. That is to say that the axis X 'is horizontal and the axis Z' vertical. It is in this position that the performances of the two elastic joints 3 in acoustic filtering prove to be the best. However, it is not absolutely essential that the axis Z ′ of each articulation 3 is oriented strictly vertically and its orientation may be between the limits of + 45 ° and - 45 ° with respect to a perpendicular to the horizontal plane defined by the X and Y axes of the reference system linked to the vehicle body. Similarly, it is also not absolutely essential that the minima and maxima of the corrugated profile of each of the two end faces 7a and 7b of the sleeve 7 are angularly equidistant along the circumference.
A titre d'exemple, lorsque les axes X' et Z' des articulations 3 sont orientés respectivement selon les axes X et Z du véhicule, la raideur radiale maximale (raideur longitudinale selon X) de chaque articulation 3 peut être d'environ 3 500 N/mm, et la raideur radiale minimale (raideur verticale selon Z) d'environ 2 200 N/mm.By way of example, when the axes X ′ and Z ′ of the articulations 3 are oriented respectively along the axes X and Z of the vehicle, the maximum radial stiffness (longitudinal stiffness along X) of each articulation 3 can be approximately 3,500 N / mm, and the minimum radial stiffness (vertical stiffness along Z) of around 2,200 N / mm.
L'articulation élastique 3 à raideur radiale variable selon l'invention a, par rapport aux articulations élastiques à raideur radiale variable antérieurement connues, une meilleure tenue à la fatigue aussi bien lorsque l'articulation travaille en compression/traction que lorsqu'elle travaille en torsion. On peut penser que cela est dû à l'évolution continue et régulière du profil ondulé de ses deux faces d'extrémité 7a et 7b, qui font que, en service, les contraintes de compression/traction et les contraintes de torsion ne restent pas concentrées dans des zones localisées du manchon 7, mais peuvent se répartir plus facilement dans le cœur dudit manchon, sur toute sa circonférence.The elastic joint 3 with variable radial stiffness according to the invention has, with respect to the elastic joints with variable radial stiffness previously known, better resistance to fatigue both when the joint works in compression / traction than when it works in torsion. We can think that this is due to the continuous and regular evolution of the corrugated profile of its two end faces 7a and 7b, which means that, in service, the compressive / tensile stresses and the torsional stresses do not remain concentrated. in localized areas of the sleeve 7, but can be more easily distributed in the heart of said sleeve, over its entire circumference.
Il va de soi que le mode de réalisation de l'invention qui a été décrit ci-dessus a été donné à titre d'exemple purement indicatif et nullement limitatif, et que de nombreuses modifications peuvent être apportées par l'homme de l'art sans sortir du cadre de l'invention. C'est ainsi notamment que, bien que le manchon 7 en matériau élastomérique ait été représenté avec une section longitudinale qui a de préférence sensiblement la forme d'un trapèze, dont la grande base est située du côté de l'armature intérieure 8 et la petite base du côté de l'armature extérieure 9, et avec des lèvres périphériques intérieures 7c et 7d et des lèvres périphériques extérieures 7e et 7f sur les faces d'extrémité 7a et 7b, comme montré notamment dans la figure 2, la section longitudinale du manchon 7 pourrait avoir par exemple une forme rectangulaire. En outre, le nombre des minima et le nombre des maxima du profil le long de la circonférence de la ou de chacune des faces d'extrémité du manchon en matériau élastomérique n'est pas nécessairement égal à deux. Ce nombre peut être égal à un ou plus grand que deux selon le nombre des directions radiales le long desquelles il est désiré que le manchon en matériau élastomérique ait respectivement une raideur radiale minimale et une raideur radiale maximale.It goes without saying that the embodiment of the invention which has been described above has been given by way of purely indicative and in no way limitative example, and that numerous modifications can be made by those skilled in the art. without departing from the scope of the invention. Thus, in particular, although the sleeve 7 made of elastomeric material has been shown with a longitudinal section which preferably has substantially the shape of a trapezoid, the large base of which is situated on the side of the internal frame 8 and the small base on the side of the outer frame 9, and with inner peripheral lips 7c and 7d and outer peripheral lips 7e and 7f on the end faces 7a and 7b, as shown in particular in FIG. 2, the longitudinal section of the sleeve 7 could for example have a rectangular shape. In addition, the number of minima and the number of maxima in the profile along the circumference of the or each of the faces end of the sleeve of elastomeric material is not necessarily equal to two. This number can be equal to one or greater than two depending on the number of radial directions along which it is desired that the sleeve of elastomeric material have respectively a minimum radial stiffness and a maximum radial stiffness.
En outre, bien que dans la représentation des figures 9 et 10, l'amplitude crête à crête de l'ondulation (différence d'amplitude entre les minima et les maxima) du profil Pi dans la région périphérique intérieure d'une face d'extrémité 7a ou 7b du manchon 7 soit égale ou sensiblement égale à l'amplitude crête à crête de l'ondulation du profil Pe dans la région périphérique extérieure de ladite face d'extrémité 7a ou 7b, les deux profils Pi et Pe peuvent avoir des amplitudes crête à crête différentes et, dans un cas limite, l'un des deux profils Pj et Pe peut avoir une amplitude crête à crête nulle ou quasiment nulle. En outre, pour l'obtention d'une raideur radiale variable, le profil de la ou des faces d'extrémité du manchon, qui évolue de façon continue dans le sens circonférentiel du manchon, peut être combiné avec une variation continue de l'épaisseur radiale dudit manchon le long de la circonférence de ce dernier, de sorte que la section transversale du logement 14 du longeronnet 9 et/ou la section transversale de l'armature 8 ne sont pas nécessairement circulaires, mais peuvent avoir par exemple une forme elliptique ou ovale, ou une forme présentant un ou plusieurs méplats. De telles formes non circulaires peuvent également être rendues nécessaires pour diverses autres raisons, comme par exemple le type de liaison entre l'armature 8 et le bras 4. Toutefois, la configuration circulaire ou cylindrique du logement 14 et de l'armature intérieure 8 reste la plus favorable en terme de fatigue, car les contraintes régnant en service dans le manchon 7 y sont les plus homogènes.In addition, although in the representation of FIGS. 9 and 10, the peak-to-peak amplitude of the ripple (difference in amplitude between the minima and the maxima) of the profile Pi in the inner peripheral region of a face of end 7a or 7b of the sleeve 7 is equal to or substantially equal to the peak-to-peak amplitude of the undulation of the profile P e in the outer peripheral region of said end face 7a or 7b, the two profiles Pi and P e can have different peak-to-peak amplitudes and, in a borderline case, one of the two profiles Pj and P e may have a peak to peak amplitude zero or almost zero. In addition, to obtain a variable radial stiffness, the profile of the end face or faces of the sleeve, which evolves continuously in the circumferential direction of the sleeve, can be combined with a continuous variation of the thickness. radial of said sleeve along the circumference of the latter, so that the cross section of the housing 14 of the beam 9 and / or the cross section of the frame 8 are not necessarily circular, but may for example have an elliptical shape or oval, or a shape with one or more flats. Such non-circular shapes can also be made necessary for various other reasons, such as for example the type of connection between the frame 8 and the arm 4. However, the circular or cylindrical configuration of the housing 14 and of the inner frame 8 remains the most favorable in terms of fatigue, because the constraints prevailing in service in the sleeve 7 are the most homogeneous there.
Enfin, la liaison de l'armature extérieure ou longeronnet 9 à la caisse 2 par deux surfaces d'appui et deux vis perpendiculaires ne représente qu'un cas de montage tout à fait particulier. Plus généralement, on peut réaliser l'ancrage ou encastrement du longeronnet sur la caisse de diverses manières. La liaison par vis est une possibilité (dans ce cas, le minimum est une vis, donc un trou de passage, par articulation). On peut également citer le soudage ou le collage comme autres possibilités de fixation. Finally, the connection of the external reinforcement or spar 9 to the body 2 by two bearing surfaces and two perpendicular screws represents only a very particular case of mounting. More generally, it is possible to anchor or embed the beam on the body in various ways. Screw connection is a possibility (in this case, the minimum is a screw, therefore a through hole, by joint). Mention may also be made of welding or bonding as other fixing possibilities.

Claims

REVENDICATIONS
1 - Articulation élastique destinée à relier un bras de suspension à une caisse de véhicule et capable de travailler en torsion et de porter une partie substantielle du poids de la caisse, comprenant une armature intérieure (8), une armature extérieure (9) entourant l'armature intérieure, et un manchon (7) en matériau élastomérique, qui est disposé entre les armatures intérieure et extérieure et dont les surfaces périphériques intérieure et extérieure sont liées sans possibilité de glissement auxdites armatures intérieure et extérieure, caractérisée en ce que l'armature extérieure (9) est conformée de façon à pouvoir être fixée directement à la caisse (2) d'un véhicule.1 - Elastic articulation intended to connect a suspension arm to a vehicle body and capable of working in torsion and of carrying a substantial part of the weight of the body, comprising an internal frame (8), an external frame (9) surrounding the 'inner frame, and a sleeve (7) of elastomeric material, which is disposed between the inner and outer frames and whose inner and outer peripheral surfaces are linked without the possibility of sliding to said inner and outer frames, characterized in that the frame outer (9) is shaped so that it can be fixed directly to the body (2) of a vehicle.
2 - Articulation élastique selon la revendication 1, caractérisée en ce que rarmature extérieure (9) est constituée par une pièce coulée ou filée, sous la forme d'un longeronnet comportant un logement (14), dans lequel le manchon (7) en matériau élastomérique est formé par moulage et adhérisé directement à la surface du logement (14).2 - Elastic articulation according to claim 1, characterized in that the external reinforcement (9) consists of a cast or spun piece, in the form of a spar comprising a housing (14), in which the sleeve (7) of material elastomeric is formed by molding and adhered directly to the surface of the housing (14).
3 - Articulation élastique selon la revendication 1 ou 2, caractérisée en ce que ledit manchon (7) comporte, dans au moins une de ses faces d'extrémité (7a et 7b), au moins un creux qui est positionné de telle façon que l'articulation ait une raideur radiale minimale le long d'un premier axe de référence (Z') d'un système de trois axes de référence (X', Y, Z'), dont un second axe de référence (Y) est confondu avec l'axe de rotation (6) de l'articulation élastique (5).3 - elastic joint according to claim 1 or 2, characterized in that said sleeve (7) comprises, in at least one of its end faces (7a and 7b), at least one recess which is positioned so that the 'articulation has a minimum radial stiffness along a first reference axis (Z') of a system of three reference axes (X ', Y, Z'), of which a second reference axis (Y) is combined with the axis of rotation (6) of the elastic joint (5).
4 - Articulation élastique selon la revendication 3, caractérisée en ce qu'au moins une des deux faces d'extrémité (7a et 7b) du manchon4 - Elastic articulation according to claim 3, characterized in that at least one of the two end faces (7a and 7b) of the sleeve
(7) a un profil qui évolue de façon continue dans le sens circonférentiel du manchon entre au moins un minimum et au moins un maximum.(7) has a profile which evolves continuously in the circumferential direction of the sleeve between at least a minimum and at least a maximum.
5 - Articulation élastique selon la revendication 4, caractérisée en ce que les deux faces d'extrémité (7a et 7b) du manchon (7) ont un profil ondulé.5 - elastic joint according to claim 4, characterized in that the two end faces (7a and 7b) of the sleeve (7) have a corrugated profile.
6 - Articulation élastique selon la revendication 4 ou 5, caractérisée en ce que le profil a une forme sensiblement sinusoïdale ou pseudo-sinusoïdale.6 - Elastic joint according to claim 4 or 5, characterized in that the profile has a substantially sinusoidal or pseudo-sinusoidal shape.
7 - Articulation élastique selon l'une quelconque des revendications 4 à 6, caractérisée en ce que le profil (Pi), dans la région périphérique intérieure de ladite face d'extrémité, a au moins un minimum (mj) et au moins un maximum (Mi) qui sont décalés d'un angle prédéfini (α) respectivement par rapport à au moins un minimum (n e) et au moins un maximum (Me) du profil (Pe) dans la région périphérique extérieure de ladite face d'extrémité (7a ou 7b) lorsqu'aucune charge n'est appliquée à l'articulation.7 - Elastic articulation according to any one of claims 4 to 6, characterized in that the profile (Pi), in the inner peripheral region of said end face, has at least one minimum (mj) and at least a maximum (Mi) which are offset by a predefined angle (α) respectively with respect to at least a minimum (n e ) and at least a maximum (M e ) of the profile (P e ) in the outer peripheral region of said end face (7a or 7b) when no load is applied to the joint.
8 - Articulation élastique selon la revendication 7, caractérisée en ce que ledit angle prédéfini (α) est choisi de telle façon que, lorsque l'articulation (3) est soumise à une charge de référence provoquant une rotation relative dudit angle prédéfini des armatures intérieure (8) et extérieure (9) l'une par rapport à l'autre, les lieux géométriques (17) des minima et les lieux géométriques (18) des maxima du profil entre lesdites régions périphériques intérieure et extérieure sont orientés sensiblement radialement respectivement le long du premier axe de référence (Z') et le long d'un troisième axe de référence (X') du système de trois axes de référence.8 - Elastic joint according to claim 7, characterized in that said predefined angle (α) is chosen so that, when the articulation (3) is subjected to a reference load causing a relative rotation of said predefined angle of the internal reinforcements (8) and exterior (9) with respect to each other, the geometric locations (17) of the minima and the geometric locations (18) of the maxima of the profile between said interior and exterior peripheral regions are oriented substantially radially respectively. along the first reference axis (Z ') and along a third reference axis (X') of the system of three reference axes.
9 - Articulation élastique selon les revendications 2 et 8, caractérisée en ce que le longeronnet (9) comporte au moins une face d'appui, de préférence deux faces d'appui (9a, 9b), apte à coopérer avec au moins une face correspondante d'appui sur la caisse (2) du véhicule, de telle sorte que, après fixation du longeronnet à ladite caisse, les trois axes de référence (X', Y, Z') de l'articulation élastique (3) aient des orientations prédéfinies par rapport à un système d'axes de référence (X, Y, Z) lié à la caisse du véhicule.9 - elastic joint according to claims 2 and 8, characterized in that the beam (9) has at least one bearing face, preferably two bearing faces (9a, 9b), capable of cooperating with at least one face corresponding support on the body (2) of the vehicle, so that, after fixing the beam to said body, the three reference axes (X ', Y, Z') of the elastic joint (3) have predefined orientations in relation to a system of reference axes (X, Y, Z) linked to the vehicle body.
10 - Articulation élastique selon la revendication 8 ou 9, caractérisée en ce que le premier axe de référence (Z') est sensiblement perpendiculaire à un plan horizontal lié à la caisse du véhicule.10 - Elastic joint according to claim 8 or 9, characterized in that the first reference axis (Z ') is substantially perpendicular to a horizontal plane linked to the vehicle body.
11 - Suspension de véhicule comportant deux articulations élastiques porteuses travaillant en torsion, caractérisée en ce que chaque articulation élastique est une articulation selon l'une quelconque des revendications 1 à 10. 11 - Vehicle suspension comprising two elastic load-bearing articulations working in torsion, characterized in that each elastic joint is a joint according to any one of claims 1 to 10.
EP01960840A 2000-07-28 2001-07-27 Elastic articulation for vehicle suspension Withdrawn EP1305176A1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
FR0009906 2000-07-28
FR0009906 2000-07-28
PCT/FR2001/002468 WO2002009960A1 (en) 2000-07-28 2001-07-27 Elastic articulation for vehicle suspension

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EP1305176A1 true EP1305176A1 (en) 2003-05-02

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US (1) US20030155698A1 (en)
EP (1) EP1305176A1 (en)
JP (1) JP2004505214A (en)
CN (1) CN1392842A (en)
AU (1) AU2001282237A1 (en)
WO (1) WO2002009960A1 (en)

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CN1392842A (en) 2003-01-22
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AU2001282237A1 (en) 2002-02-13
US20030155698A1 (en) 2003-08-21

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