MXPA96006484A - Precise regulation of a macpherson suspension strip, means of regulating the puntal and banco de med - Google Patents

Abstract

The present invention relates to a strut for a MacPherson type wheel suspension in which a shock absorber is provided with a body and a shank, the strut comprises a helical spring that surrounds the shank, a lower retainer supported by the shock absorber body, the lower retainer has a lower seat which receives one end of the spring, an upper retainer designed to rest on the body of the vehicle, the upper retainer has a seat receiving the other end of the spring, the upper retainer is pierced by the stem, The body of the shock absorber has a surface adapted to be connected to a hub carrier by a coupling means, the hub carrier of a shaft of rotation of a vehicle wheel, the coupling means imposes a predetermined azimuth position between the body and the hub carrier, the The strut further comprises a means for adjusting the position of the spring axis with respect to the surface of the body. of the shock absorber and maintain the adjusted position during the operation of the

Description

PRECISE REGULATION OF A SUSPENSION POINT MAC PHERSON: MEANS OF REGULATING THE SPOT AND BANK OF MEASURE Field and Background of the invention The present invention relates to suspensions of the Mac Pherson type. Figure 1 represents a suspension of this type. It is known that this type of suspension comprises a strut 1 constituted, essentially, by a shock absorber that participates at the same time in guiding the wheel. The shock absorber comprises a body 2 and a rod 3. The upper end 30 of the rod rests on the vehicle body at a point of articulation 31 materialized, in general, by an elastic joint. A coil spring 4 is mounted between an upper cup 40 and a lower cup 41. The lower cup 41 rests on the body 2 of the shock absorber and the upper cup 40 rests on the body of the vehicle, also, in general, by means of a filtering carried out by said elastic, filtered articulation which, in REF: 23710 certain embodiments, may be the same for the spring and for the shock absorber. On the other hand, the body 2 is made integral with a hub carrier 5. Thus, there is no degree of freedom between the body 2 and the hub carrier 5. A lower arm 6 is articulated, on the one hand, to the vehicle body and , on the other, to the hub holder 5 by the articulation 65. The hub holder 5 supports a hub 50, on which a wheel 51 equipped with its tire 52 is mounted. In the area of attachment to the box, the strut 1 exerts on the box efforts that come, at the same time, from the spring and the shock absorber. Although the exact location of the point of application of these efforts is difficult, and depends especially on the exact construction of the prop 1, it is known that the control of the shear stress to which the rod 3 of the shock absorber is subjected is determinant for the proper functioning of the suspensions of this type. To simulate a Mac Pherson suspension, the reaction 5 of the vehicle's box on the prop can be considered. Its direction passes through point C, this being defined by the intersection of the force B exerted by the lower arm 6 on the articulation 65 and the resultant of the forces S that the floor exerts on the tire 52. In first approximation, the immobile vehicle, said resultant S is oriented vertically and passes through the center of the contact area of the tire (the value of this stress during rolling in a straight line and at a stabilized speed depends on the characteristics of the tire and the adjustments of the geometry of the tire. front train). The intersection of B and S gives the point C. The reaction R is distributed between the thrust P of the spring and a shear stress T applied to the rod 3 of the damper in a direction perpendicular to said rod 3, in such a way that the following relationship: R = T + P (vector sum). To obtain a good functioning of the strut (without friction in dry or with few frictions, minimum wear, ...), it is known to control very closely the shear stress f applied to the rod 3. For this purpose, it has already been proposed to tilt the axis of the spring 4 with respect to the axis of the rod 3, as shown in the drawing. Thus, almost all Mac Pherson suspensions currently used comprise a spring whose axis is not confused with that of the damper rod. The inclination of this spring 4 has been calculated to minimize the shear stress on the rod 3. On the other hand, the researches of the applicant have led him to observe that the resultant of the efforts exerted by the spring is capable of exercising a torque Cp around the pivot axis, defined by the point of articulation 31 and the center 66 of the joint 65. This torque acts on the balance of the steering system. In order to obtain a good operation of the steering system, it is necessary to control well (for example to minimize) the combined effect of the Cp pairs coming from the right and left struts. UnfortunatelyToday, many cars still suffer from poor suspension and / or steering characteristics. The dynamic behavior of a vehicle depends on a considerable number of parameters, some of which have an influence that is still poorly known, but which, nevertheless, may well be preponderant. It turns out that, even when the designer has respected all the rules of the technique to conceive the suspension, the result is not always up to the care provided in the conception.

Description of the invention The present invention proposes means that allow the practical optimization of each of the vehicles manufactured in series. Indeed, it has been considered that the inevitable dispersions of the characteristics of all the components of the suspension, and more precisely of the prop, could cause quite significant variations in behavior from one vehicle to another. The invention proposes the elements necessary for the optimization and a method of optimizing the distribution of the reaction R between the thrust P of the spring 4 and the shear stress T in the rod 3, as well as the torque Cp exerted by the spring about the axis of pivot. The invention proposes to introduce a strut, comprising a spring whose inclination has been previously calculated so that the residual shear stress T is optimized, for example, is made as small as possible, elements that allow to more accurately adjust the value of this residual shear stress T or of the torque Cp. In this way, it is possible to take into account the dispersions of the characteristics, especially of the springs, which seem to be responsible for very significant dispersions of the shear stress T and the torque Cp actually obtained in the series vehicles. The object of the invention is to be able to act on the location of the spring centers of the spring on the upper cup and on the lower cup, as well as on the orientation of said thrusts, without acting on the usual geometry parameters of a suspension, which are the angle of convergence, the angle of inclination of the pivot, and the angle of advance of the pivot, which remain unchanged. The invention proposes a strut for wheel suspension type Mac Pherson, comprising a shock absorber provided with a body and a rod, said strut comprising a helical spring surrounding the said rod, a lower support cup supported by the body of the damper, said lower cup comprising a lower seat receiving one of the ends of said spring, and a top supporting cup intended to rest on the vehicle body, by means, where appropriate, of a connecting member, comprising the said upper cup is an upper seat that receives the other from the ends of said spring, said upper cup being traversed by said rod, the body of the shock absorber comprising a fixation seat to a hub carrier that cooperates with fixation means, the aforementioned being defined the hub supports an axis of rotation of said wheel, said fixing means imposing a predetermined azimuthal position in the body and the hub carrier, characterized in that said strut comprises means for adjusting the relative position of the axis of the spring relative to said fixing seat. The invention will be better understood with the description that follows of a given example as non-limiting, referring to the accompanying drawings, in which: Figure 1 shows a Mac Pherson suspension, Figures 2 to 4 and 8 to 12 illustrate a adjustment by eccentric acting by displacement of the lower cup relative to the axis of the damper rod, figures 5 to 7 and 13 to 15 illustrate a regulation by variation of the inclination of the lower cup relative to the orientation of the damper rod , figures 16 and 17 illustrate a regulation by geometrical variation of the spring support on the cup, figures 18 to 21 illustrate a regulation that acts by translating the lower cup relative to the axis of the damper shaft, figures 22, 23 and 24 illustrate three banks of measurement according to the invention, figure 25 illustrates a double measuring bank, specific to one aspect of the invention, the figures 26 and 27 show, front and side, a McPherson suspension for steering wheel, figures 28 and 29 outline the main axes in presence and the main forces, figures 30, 31 and 32 illustrate a possibility of regulation, figures 33 and 34 illustrate a device for regulation by electric control. In FIGS. 2 to 7, struts are described for which adjustment is made by relative rotation of the body 2 of the shock absorber relative to the hub carrier 5. In this case, the attachment means to a hub carrier comprise reference means (i.e. marked) of the relative orientation of the body of the shock absorber relative to the hub carrier, said reference means being disposed on or in the vicinity of the fastening seat. These are, for example, a graduated sector that allows the relative position of the body 2 to be marked and evolved relative to the hub holder 5. The relative angular position and / or the offset of the lower cup is thus actuated. Before describing the regulating means explained above, let us remember that, in the case of the guide wheels, the strut comprises an axial ball bearing 42, visible in figures 2, 5, 6, 8 to 14, 22, 23 and 26 to 30, whose function is that the rotation of the wheels is not hindered by the spring 4. In the case of a strut in which the axial ball bearing 42 is located below the lower support cup 41 of the spring 4, the The axial ball bearing 42 is centered on an eccentric collar 27, for displacing the center of the axial ball bearing 42 by a distance e relative to the axis of the damper 2 (Figs 2 to 4). Comparing Figures 3 and 4, it is seen that a rotation € between the body 2 of the shock absorber and the hub holder 5 displaces the center of the axial ball bearing 42, which correspondingly displaces the lower cup 41. Figure 5 illustrates a strut whose axial ball bearing 42, also located below the lower cup 41, is inclined in such a way that the normal to the bearing surface of the lower cup forms an angle a with respect to the axis of the rod 3. Figure 6 shows that By relative rotation of the body 2 relative to the hub holder 5, the orientation of the axis of the axial ball bearing 42 and the position of the spring 4 on the lower cup 41 are varied. A combination of the offset and the inclination a can also be used. In the case of a rear rail strut, or a front strut strut in which the axial ball bearing is located above the upper spring support cup (FIG. 7), the lower ball cup 41 of the spring 4 is integral with the body 2 of the shock absorber. The axis of the lower cup is inclined by an angle β with respect to the axis of the body of the shock absorber 2 and / or offset by a distance e with respect to the axis of the body of the shock absorber 2. Here again, the adjustment consists of angularly orienting the body 2 of the damper relative to the hub 5. The modification of said orientation allows changing the position of the lower cup 41 relative to the upper cup and, thus, adjust the thrust direction of the spring 4. Figures 8 to 12 illustrate a regulation by rotation of an eccentric: the lower cup 41 is mounted on the body 2 of the shock absorber by means of a cam 420 adjustable in rotation. The eccentric can form part of the axial ball bearing 42 (figures 10 and 12), or be independent of it (figures 8, 9 and 11). The rotation of the eccentric 420 relative to the body 2 (figures 8 and 9), or the rotation of the eccentric 420 relative to the cup 41 (figure 11) displaces the cup 41 relative to the body 2. It could, too, mount the upper cup on the box through a connecting member provided with an eccentric. Figures 13 and 14 show the regulation using a wedge 71 comprising a section of maximum thickness and a section of minimum thickness diametrically opposite to the preceding one, the thickness varying continuously between said sections, said wedge 71 supporting said lower cup by one of its faces, said wedge 71 being adjustable by relative rotation. This arrangement finds application, for example, in the case of a front strut strut, in which the axial ball bearing 42 is located below the lower strut 41. Naturally, the use, as has been explained, of such a wedge as the wedge 71 supporting the upper cup, it also allows to act on the upper cup. The wedge 71, whose faces are inclined relative to each other by an angle?, Is interposed between the lower cup 41 and the axial ball bearing 42 (FIG. 13), or between the axial ball bearing 42 and the bearing collar 25. solidary of the body 2 of the shock absorber (Fig. 14). As a variant, the axis of the bearing face of the collar 26 can be inclined at an angle a with respect to the axis of the body 2 of the shock absorber (Figure 15) and could also support a wedge. The regulation consists in angularly orienting the wedge 71 in relation to said cup 41 (figure 13), or in relation to said body 2 (figure 14). The modification of said orientation makes it possible to change the inclination of the lower cup 41 with respect to the axis of the shock absorber 2, and thus adjust the thrust direction of the spring 4. After adjustment, the wedge 71 will be made integral, preferably with the lower cup 41. { fig. 13), or with the support collar 25 (Fig. 14) by means of a mechanical retention device, or by gluing. The same regulating principle applies equally to struts without axial ball bearings, or to struts in which the axial ball bearing 42 is located above the upper supporting cup of the spring.

Figure 16 illustrates a ring 78 that forms a brace interspersed between the spring 4 and the cup, in this case the lower cup 41. The seat of one of the cups is materialized by said ring 78 arranged on the contour of said cup 41, movable in rotation on said contour, said ring forming a strut between the spring and said cup, the supporting surface of said ring on the cup being a surface of revolution, forming said ring having a section of thickness maximum and a section of minimum thickness, said ring being adjustable by relative rotation with respect to said cup. In figure 17, a variant is seen in which the ring 79, in addition to a variable thickness, has an offset seat relative to the resting surface on the cup 41, which is of revolution. In both cases, the adjustment is made by relative rotation of the ring 78 or 79 relative to the cup 41, the spring 4 resting on the ring without relative movement. The eccentric character of the ring can be used, also, independently of the property of variation of thickness, if the shape of the spring allows it.

In the case of a non-directing or main train strut in which the axial ball bearing is located below the upper spring support cup (figures 18 to 21), a strut can also be made in which cited adjustment means comprise, essentially, the following arrangement: the lower cup 41 is placed on a collar 22 secured to the body 2 of the shock absorber, said collar forming a slide that guides in translation the said cup in a plane that cuts the axis of the damper, said strut comprising means for selecting a chosen relative position of said lower cup relative to said collar and for immobilizing said lower cup and said collar in the chosen position. In the example described, the relative translation between lower cup 41 and collar 21 is done in a direction perpendicular to the plane of FIGS. 19 and 21. A toothing 22 is made on two parallel and opposite edges of the collar 21 that forms a slide (FIGS. and 20). This toothing ensures, at the same time, the guiding in translation (by the said parallel edges) of the lower cup 41, and allows the immobilization in the relative position, by the own toothing. The lower cup 41 can be constructed by drawing a metal sheet (figures 18 and 19). In this case, the lower cup comprises two folded parallel edges. A rib 23, visible in Figure 18, is made in the center of each of the folded edges. This rib 23 engages in the teeth 22 of the collar 21 to immobilize the chosen relative Position. The lower cup 41 can also be constructed by molding (Figures 20 and 21). This lower cup then has two lugs 24 (FIG. 20) which have on their lower face a complementary fingerprint of the teeth 22. This finger is engaged in the teeth 22 of the collar 21 to immobilize the chosen relative Position. Naturally, the regulatory elements described above can be useful for providing corrections, whatever the method of detecting disturbances of vehicle behavior. They can be used separately or, some of them, combined together. The invention allows to respect rather narrow tolerances in the real characteristics of the props mounted on the vehicles. The regulating elements can be used in conjunction with a measurement, for example, of the shear stress applied to the rod, for example by decoupling the upper part of the rod from the upper cup or, more generally, from the connecting member to the box, and measuring the effort necessary to maintain the upper part of the rod in your initial configuration, or by any convenient method. If it is desired to act on the combined effect of the Cp pairs, the measurement of the characteristics of the steering system, for example the torque exerted on the steering wheel to keep the vehicle in straight line during rolling on a given slope, is equally relevant for act on the elements of regulation. Thus, there are several parameters that can be measured, such as the shear stress on the rod, the torque of rotation around the pivot axis, or the torque on the flywheel, or other parameters more if these are representative, directly or indirectly, of the operation of the props in actual use in the vehicle for which they are designed.

One can think, thus, to fine-tune the regulation of vehicles at the end of the manufacturing chain. They can also be used more experimentally, observing the influence of regulation, thanks, for example, to an experience plan for each equipped vehicle. with struts according to the invention, and thus establishing correction rules for use by specialists in rolling trains. They can thus be used, mainly, to effect a regulation on the vehicle, in the course of maintenance operations. According to another aspect of the invention, it has been proposed to act on the struts during their manufacture, before mounting on the vehicle. A measurement of the shear stress T and / or the torque Cp is made as they will appear in each strut when it is mounted on a vehicle. This average can be done during the assembly of the prop. This measure can be carried out in good industrial conditions by means of a robust device, such as the one described below, the configuration of which is regulated according to the characteristics of the vehicle that the said prop should receive. Depending on the result of the measurement, the means for adjusting the orientation of the force of the spring on the upper cup are actuated and, subsequently, the adjustment element is immobilized. Figures 22, 23 and 24 illustrate a bench measuring a strut of a suspension type Mac Pherson, said strut comprising: - a shock absorber comprising a body and a rod, said body comprising a fixing seat intended to be mounted on a hub carrier, a connecting member, intended to be mounted on the vehicle body, which receives the said rod and forms an elastic joint for it, - a helical spring that surrounds the said rod, - a lower supporting cup mounted on the body of the shock absorber and a top supporting cup mounted on said connecting member, said spring being inserted between said cups, said bench comprising, arranged in a frame: - a plate, of which one face is provided of fixing means of the connecting member, - a mandrel intended to receive said body, - means ensuring an approximation and / or a relative distancing of the mandrel with regard to n to the plate, means for configuring the bank as a function of the vehicle intended to receive the said strut, - means for measuring at least one magnitude representative of the tensions on the connecting member. In a particular embodiment (Fig. 22), the plate 90 is mounted on the frame 92 by means of a first group of three connecting rods Bl, B2, B3, mounted by ball joint or by equivalent elastic decoupling, which it presents in the measurement the advantage of not introducing friction (localized thinning of the connecting rod), on the one hand, on the face of said plate 90 opposite the face receiving the said joining member and, on the other hand, on configurable housings arranged on the frame 92 in front of said plate 90, essentially constituting the precise position of said housings said configuration means and, by means of a second group of three coplanar connecting rods B4, B5, B6 mounted by ball joint, on the one hand, on the said opposite plate and, on the other hand, on said frame, so that its plane is perpendicular to the axis of the rod, at least one of the tensile force sensors comprising at least one of said connecting rods. and compression. Preferably, at least two of said cranks of the second group B4, B5, B6, or all three, comprise such a sensor I. A bench of this type makes it possible to simulate the real stress of the prop in conditions extremely close to reality. With this object, it is convenient that the three connecting rods Bl, B2, B3 concur in the point E. If it is desired to measure the shear stress T, the best location of E is that it corresponds to the place of space in relation to the strut in which it is located. located at point C when the strut is mounted on the vehicle for which it is designed. If you want to measure the Cp torque, the best location of E is that it corresponds to the place of the space in relation to the prop where the point 66 is located when the prop is mounted on the vehicle for which it is designed. In both cases, a good approximation of the measurements is obtained without changing the regulations of the bank, that is, proceeding to the two measurements with a single configuration of the measuring bank, if this is adjusted so that point E is located in the segment that joins 66 with C In any case, the point E results from the complete geometric characteristics of the vehicle in question. The reader is referred to the introductory part of this report, in which it is reminded, with the help of figure 1, in which places the points C and 66 are located, according to the exact shape of the cube holder, of the position of the articulation 65 and the size of the tires. The regulation of the bank is done by a mechanism that allows to move the housings, or the bank is associated to a certain number of cassettes regulated in advance, of quick installation on bank, for example by interlocking, each cassette corresponding to a vehicle. The strut has been previously assembled. However, measuring in bench requires that the damper rod is not attached to the upper cup. For all struts intended to be mounted in the box by means of the upper cup, it is sufficient not to mount (or dismantle) the end of the rod, and push it towards the body. In the case where the upper cup is mounted on the end of the rod, it is advisable to provide an adaptation piece having the same configuration as the upper part of the rod, in order to be able to mount the strut on the measuring bench, while leaving the shock absorber rod unstressed and pushed towards the shock absorber body. The strut is mounted on the plate 90 by its upper cup 40 (or by means of an adaptation piece) exactly as it would be mounted on the vehicle body, ie, so that the elastic hinge of the shock absorber rod (point 31) is located in the convenient place. The body 2 of the shock absorber is mounted on the mandrel 91, by snapping. The bench makes it possible to compress the spring 4 to the position it will have under the effect of the weight of the vehicle, by relative approximation of the mandrel 91 relative to the plate 90, by translation parallel to the axis of the shock absorber.The measurement is then carried out, in particular the shear stress. By an appropriate treatment of the signal supplied by the sensor or the sensors, a direct reading of the force acting on the point 31 in the plane of the plate 90 can be obtained. This is the shear stress that the rod would experience if it were solidary. upper anchor of the prop. The sensor I of the connecting rod B5, if it is provided with it, also makes it possible to measure the torque exerted by the thrust of the spring 4 around the axis that goes from E to 31. The result of these measurements allows to adjust in a precise way the direction of spring thrust, that is, regulate the vector P, acting on a regulating element incorporated in the strut. This makes it possible to correct the shear stress on the rod, or any other component of the torque moment of the force exerted by the connecting member on the plate 90. When the desired value is obtained, the regulating element is blocked, and the strut can be used in the vehicle with the assurance that its elasticity and guiding characteristics correspond, effectively, to the optimum values.

Figure 23 shows a variant embodiment of the measuring bench, in which the plate 90 is mounted on the frame 92 by means of a plate P3 mounted on an axis, on the one hand, on the face of said plate 90 opposite the face receiving the aforementioned connecting member and, on the other hand, in the frame 92 (configurable axis) in front of said plate 90 (axes or equivalent elastic blades), and by means of a connecting rod B3 whose axis intersects the plane defined by the plate P3 in C, mounted by ball-and-socket joints, on the one hand, on the face of said plate opposite to the face receiving said joining member and, on the other hand, in a configurable housing arranged on the frame 92 facing said plate 90 essentially constituting the determination of the position of said housing and said configurable axis said configuration means and, by means of a second connecting rod B4 mounted by ball joint, on the one hand, in said plate 90 and, on the other hand , In b 92, so that the second rod is perpendicular to the axis of the rod, said second rod comprising a traction and compression force sensor I. The configuration of this bank is similar to that which has been explained above, and its use is guided by the same rules. Figure 24 shows another variant embodiment of the measuring bench, in which the plate 90 comprises a column 900 arranged substantially parallel to the strut. It is mounted on the frame 92 by means of two connecting rods Bl and B2 which are arranged, relative to the strut to be measured, in the plane of the lower suspension triangle (see arm 6 in figure 1). The connecting rods Bl and B2 converge at a point D that coincides with the locus of point 66 (center of ball joint 65 of arm 6, see figure 1). The plate 90 is mounted on the frame 92 also by means of a connecting rod B3 arranged in the plane of the wheel, in the direction of the load S. The axis of the connecting rod B3 passes through the point C. The plate 90 is mounted in the frame 92 also by means of the connecting rods B4 and B6 located in a plane perpendicular to the axis of the shock absorber, which are perpendicular to each other and converge at the point 31. The plate 90 is mounted on the frame 92 likewise by means of a connecting rod B5. parallel to the B6 connecting rod. The plane defined by the connecting rods B5 and B6 is perpendicular to the pivot axis 80 and cuts it at point 31. The connecting rods B3, B4, B5 and B6 are provided with sensors I. When the rod of the shock absorber is not coupled to the cup. 40, the spring is compressed as would occur under the rated load of the vehicle. This measuring bench shows the following values: B4 directly measures the transverse shear stress of the shock absorber, B5 and B6 measure the longitudinal shear stress to the shock absorber axisB5 measures the torque Cp generated by the spring about the pivot axis 80, and B3 measures the vertical load experienced by the vehicle wheel in the same compression state of the spring. The configuration of the bench is analogous to that which has been explained above, acting on the anchors of the different connecting rods on the frame. Thus, a bank of this type comprises a first group of two coplaconnecting rods Bl and B2 and of axes concurrent with the pivot axis 80, substantially at the center of the lower link ball joint, a second group of two connecting rods B4 and B6 coplaand arranged so that its plane is perpendicular to the axis of the rod at the height of the said elastic joint that receives the said rod, and comprises, in addition, a connecting rod B5 coplawith B6, so that the plane formed by the cranks B5 and B6 are perpendicular to the pivot axis 80 and cut the said pivot axis at the height of said elastic joint, and a connecting rod B3 located in the middle plane of the wheel. It is also possible to use a bank that has two measurement systems such as those described and which allows simultaneously receiving a right strut and a left strut intended for the same vehicle. Such a bank has the advantage of being able to obtain, in conditions extremely close to reality, a direct reading of the combined effect that these two props will exert on the vehicle's steering system, by an appropriate treatment of the signal supplied by the sensors of the two measurement systems. The result of these measurements allows to adjust in a precise way the combined effect of the two struts on the steering system, acting on a regulating element of each of these two struts. An example of a regulation bank of this type is shown in FIG. 25. After adjustment, these two struts are matched and mounted on the same vehicle. Two posts are seen that are identical to what has just been explained, each one having a plate 90 and a mandrel 91. The connecting rods Bl, B2, B3 are regulated so that they concur in point E, chosen according to the geometrical characteristics of the vehicle that must be equipped with the pair of struts. Some of these connecting rods comprise a traction / compression stress sensor I as explained above. The two mandrels 91 are mounted on a cross member 94 that slides on the frame 92. The cross member 94 slides along the frame 92 under the action of the jack 93. In this way, the bank allows the springs of each of the coils to be simultaneously compressed. struts. The invention also proposes a specific adaptation to the steering trains, illustrated in figures 26 to 34. In the course of a turning movement, driven by the steering system attached to the hub carrier 5 by a connecting rod 53 by means of a ball joint, the the strut assembly, hub carrier, hub and wheel pivots about the pivot axis 80, defined by points 31 and 66.

The strut 1 comprises an axial ball bearing 42 which makes it possible to rotate without requesting the spring 4 to twist. In effect, the thrust of the spring 4 is exerted between the vehicle body and the body 2 of the shock absorber. The mentioned body of the shock absorber makes a rotation about the pivot axis 80. This axial ball bearing 42 can be located between the box and the elastic joint, either between the elastic joint and the upper cup 40 of the spring, as shown in figures 26 and 27, or, finally, between the lower cup 41 and the body 2 of the shock absorber. As seen in each of these cases, the axis of rotation 70 of the axial ball bearing is, in general, different from the pivot axis 80. In all known embodiments, these two axes are cut. In effect, the axis of the axial ball bearing is generally confused with the common axis of the rod 3 and the body 2 of the damper. This configuration makes it possible to limit the effects of the torque Cp that the thrust of the spring can exert around the pivot axis 80, and that they act on the balance of the steering system by means of the connecting rod 53. Despite all the design efforts always present to improve the behavior perceived by the drivers, in order, not only, to build very safe vehicles, but also pleasant vehicles to drive, many vehicles still suffer today from a bad behavior of the management. In effect, this behavior of the direction depends on a considerable amount of parameters, some of which have a badly known influence, but which, without a doubt, can sometimes be preponderant. It is thus, even when the designer has respected all the rules of the technique to size the steering system, that the result is not always up to the care provided in the conception. The present invention proposes an evolution of the design of struts that allows to control and even precisely adjust the effects of the torque Cp that the thrust of the spring causes to appear around the pivot axis 80, thus allowing to better control the part of the struts of suspension in the behavior of the steering system, without, on the other hand, being modified the geometry (angles and characteristic displacements) of the front train. Thus, this invention proposes to the suspension designers a degree of freedom of supplementary design totally independent of the parameters usually taken into account in the definition of a front axle. This additional parameter of conception also offers a possibility of regulation that allows an easier tuning of the prop and shorten, thus, the development time of the suspension of a future vehicle. The strut of a wheel suspension type Mac Pherson according to the invention, comprising a damper provided with a body and a rod, said strut comprising a coil spring surrounding said rod, a lower support cup supported by the body of the shock absorber, said lower cup comprising a lower seat receiving one end of said spring, and a top support cup intended to rest on the vehicle body, said upper cup comprising an upper seat receiving the other end of said spring, the aforementioned spring being traversed upper cup by said rod, the body of the damper comprising a fixation seat to a hub carrier cooperating with fixing means, said hub carrier defining a rotation axis of said wheel, one of the upper and lower cups containing a bearing balls that allows the rotation of the hub carrier, is characterized in that the axis of the aforementioned ball bearing and the e of pivot are not concurrent. The invention thus proposes a strut for steering wheel suspension type Mac Pherson, in which the axis of rotation 70 of the axial ball bearing 42 is positioned in such a way that it does not cut the pivot axis 80. This axis of rotation will be, thus, parallel to the pivot axis, or non-coplanar with the pivot axis. In these cases, it is then possible to define a distance d between these two axes. This distance d is the smallest measurable distance between two respective points of these axes. This is manifested in a direction perpendicular to each of these axes, as shown in figures 27 or 29 in the particular case of a bearing 42 located above the upper cup 40. Thanks to said construction, it is possible to control the torque Cp exerted by the thrust P of the spring about the pivot axis 80, as described in the following lines and is illustrated by figures 28 and 29. The combination of the two pairs Cp exerted by the right and left struts acts, thus, on the steering system in a perfectly controlled manner. The spring exerts a pushing force P on the lower cup 41. This thrust P transits the axial ball bearing 42. By presenting this axial ball bearing 42 with a very small internal friction, the thrust P of the spring exerts a moment in these conditions of zero rotation according to axis 70 of the bearing. This null moment results in the fact that the thrust direction P of the spring cuts the axis 70 of the axial ball bearing 42 at a point B, as shown in FIGS. 28 and 29. If, by reason of the arrangement of the Strut, the direction of thrust P from the point B does not cut the pivot axis 80, it turns out that the thrust P of the spring exerts around the pivot axis 80 a pair Cp proportional to the component of said thrust P of the spring perpendicular to the axis of pivot and at the distance d previously described. The perfect control of the distance d and its orientation allows to give the pair Cp a very precise value. This distance d can be defined in the design of the strut, so that the effects of the pairs Cp of the right and left struts on the steering system 5 are better controlled. According to another aspect of the invention, this distance d can be adjusted. In the latter case, it becomes possible to regulate the combined action of the pairs Cp of the two props, in order to correct any possible behavior defect of the steering system found in the vehicle, whatever the detection method may be. It is also possible to carry out said regulation at the end of the production line or, more experimentally, by observing the influence of said regulation, for example, by means of an experience plan for each vehicle equipped with struts according to the invention, and thus establishing correction rules for use by the specialists of the rolling trains. Thus, this regulation can be used, mainly, to provide an eventual correction of the behavior of the address, in the course of maintenance operations of the vehicle. It is also possible to carry out the regulation in the course of the assembly operation of the strut, thanks to a bank capable of measuring the torque Cp. You can use, for example, a bank like one of the ones exposed above. Figures 27, 30 to 32 illustrate an offset axial ball bearing 42. The adjustment is made by relative rotation between a wedge 72 mounted centrally on the support directly in contact with the vehicle body, said wedge 72 having an offset housing for receiving the axial ball bearing 42. It is seen, for example, that the bearing axis is farther from the pivot axis 80 in FIG. 31 than in FIG. 30. In this example, the regulation is an operation performed in the vehicle maintenance workshop, or during the mounting of the prop in a bank of measure. The means for adjusting the distance d can act by translation of the bearing, without changing the orientation of its axis, for example by orienting the upper ring 74 of the bearing 42 that is offset relative to the rod 3 of the shock absorber (figures 30 to 34). This regulation will be defined in such a way that it will modify the spring thrust characteristics as little as possible, and especially its rigidity. Thus, the translation of the bearing will preferably be carried out according to a plane perpendicular to the axis of the spring, and its tilting will be carried out around an axis that cuts, preferably, the axis of the spring. The distance d can also be adjusted in the course of rolling the vehicle to correct a defect in steering behavior as soon as it is detected. The defect can be verified by the driver of the vehicle. In this case, the correction made by the adjustment of the distance d will be made by an actuator governed by the driver of the vehicle itself. The detection of the defect can be equally automatic, for example, by measuring the torque that must be exerted on the steering wheel to keep the vehicle in a straight line. In this case, the adjustment of the distance d can be governed by an active, fully automatic correction system. Figures 33 and 34 represent an example of embodiment that includes a motorized system that allows to vary the distance d. The upper ring 74 of the axial ball bearing 42 is supported on a low friction coating. This ring 74 is guided in rotation about an axis 73 perpendicular to the plane of said ring and is located at a point of its periphery, and comprises on the opposite side of this axis a rack 75 driven by a pinion 76 attached to the axis of a electric motorization system 77. This motorization 77 has a characteristic of irreversibility, that is to say that a torque exerted on the axis of the pinion 76 can not cause its rotation in the absence of electrical supply voltage. This motorization can be carried out, for example, by means of an electric motor coupled to an irreversible reducer, for example an endless screw system, or it can be realized by means of a piezoelectric motor that directly drives the pinion 75.

It is noted that in relation to this date, the best method known by the applicant to carry out the present invention is that which is clear from the present description of the invention.

Having described the invention as above, the content of the following is claimed as property:

Claims (18)

1. Strut of a wheel suspension type Mac Pherson, comprising a shock absorber provided with a body and a rod, the strut comprising a helical spring that surrounds the rod, a lower support cup supported by the body of the shock absorber, comprising the cup lower a lower seat that receives one end of the spring, and a top support cup intended to rest on the vehicle body, the upper cup comprising an upper seat that receives the other end of the spring, with the upper cup being traversed by the rod, the body of the shock absorber comprising a fixation seat to a hub carrier cooperating with fixing means, the hub holder defining a rotation axis of the wheel, the fixing means imposing a predetermined azimuthal position between the body and the hub holder, characterized in that the strut comprises means for adjusting the relative position of the axis of the spring relative to the as fixation

2. Strut according to claim 1, characterized in that the regulation means comprise, essentially, the following arrangement: the lower cup is mounted on the body of the shock absorber by means of a cam that can be adjusted in rotation.

3. Strut according to claim 1, characterized in that the regulation means comprise, essentially, the following arrangement: one of the cups rests on a wedge comprising a section of maximum thickness and a section of minimum thickness diametrically opposite to the preceding one, the thickness varying continuously between the sections, the wedge supporting the cup on one of its faces, the wedge being adjustable by relative rotation.

4. Strut according to claim 3, characterized in that the cup is the lower cup, the wedge receiving on one of its faces the lower cup, the other of the faces of the wedge being mounted on a bearing flange integral with the body of the shock absorber.

5. Strut according to claim 1, characterized in that the regulation means comprise, essentially, the following arrangement: the seat of one of the cups is materialized by a ring arranged on the contour of the cup, movable in rotation on the contour, forming the ring a strut between the spring and the cup, the bearing surface of the ring on the cup being a surface of revolution, the ring having a section of maximum thickness and a section of minimum thickness, the ring being adjustable by relative rotation with respect to to the cup.

6. Strut according to claim 1, characterized in that the regulation means comprise, essentially, the following arrangement: the seat of one of the cups is materialized by a ring forming an eccentric, comprising a mounting face on the cup, being the ring adjustable by relative rotation in relation to the cup.

7. Strut according to claim 1, characterized in that the means for adjusting the orientation of the strut relative to the axis of the rod comprise, essentially, the following arrangement: the means of attachment to a hub carrier comprise means of reference of the relative orientation of the body of the shock absorber relative to the hub carrier, the reference means being arranged in or near the fixing seat, the adjustment being obtained by relative rotation of the body of the shock absorber relative to the hub carrier.

8. Strut according to claim 1, characterized in that the adjustment means comprise, essentially, the following arrangement: the lower cup is placed on a collar integral with the body of the shock absorber, the collar forming a slide that guides the cup in translation in a plane which cuts the shock absorber shaft, the strut comprising means for selecting a relative position chosen from the lower cup relative to the collar and for immobilizing the lower cup and the collar at the chosen position.

9. Measuring bench of a strut of a Mac Pherson type suspension, the strut comprising: - a shock absorber comprising a body and a rod, the body comprising a fixing seat intended to be mounted on a hub carrier, - a connecting member intended for to be mounted on the vehicle body, which receives the rod and forms an elastic joint for it, a helical spring that surrounds the rod, - a lower support cup mounted on the body of the shock absorber and a top support cup mounted on the connecting member, the spring being inserted between the cups, the bank is characterized in that it comprises, arranged on a frame: - a plate of which one face is provided with fixing means of the connecting member, - a mandrel intended to receive the body, - means that ensure a relative approach and / or a distancing of the mandrel relative to the plate, means of configuration of the bench depending on the vehicle intended to receive the strut, - means for measuring at least one parameter representative of the tensions on the connecting member.

10. Bench according to claim 9, characterized in that the plate is mounted on the frame by means of a first group of three rods whose axes are concurrent, mounted by ball joint, on the one hand, on the face of the plate opposite the face receiving the connecting member and, on the other hand, in configurable housings arranged in the frame facing the plate, essentially constituting the positioning of the housings the configuration means and, by means of a second group of three coplanar connecting rods mounted by ball joint, by a part, on the plate and, on the other hand, on the frame, so that its plane is perpendicular to the axis of the rod, at least one of the rods comprising a traction and compression force sensor.

11. Bench according to claim 10, characterized in that at least two of the rods of the second group comprise a stress sensor, so as to measure the shear stress on the damper rod.

12. Bench according to claim 9, characterized in that the plate is mounted on the frame by means of a plate mounted, on the one hand, by a configurable axis on the face of the plate opposite the face receiving the joining member and, for another part, in the frame in front of the plate, and by means of a rod mounted by ball joints, on the one hand, on the face of the plate opposite the face receiving the upper cup and, on the other hand, in a configurable housing arranged in the frame in front of the plate, essentially constituting the regulation of the housing means of configuration, and by means of a second rod mounted by ball joint, on the one hand, on the plate and, on the other hand, on the frame, so that the second The connecting rod is perpendicular to the axis of the rod, the second connecting rod comprising a tensile and compression force sensor.

13. Bench according to claim 9, characterized in that the assembly of plate and solid column is mounted on the frame by means of six rods mounted by ball joint, on the one hand, in the assembly and, on the other hand, in the configurable housings arranged in the frame in front of the assembly, and in which a first group of two connecting rods are coplanar and of axes concurrent with the pivot axis, substantially at the center of the lower arm's ball joint, in which a second group of connecting rods are coplanar and are arranged so that its plane is perpendicular to the axis of the rod at the height of the elastic joint that receives the rod, in which a rod is coplanar with, so that the plane formed by the rods is perpendicular to the axis of Pivot and cut the Pivot axis at the height of the elastic joint, and in which a connecting rod is located in the middle plane of the wheel.

14. Measurement installation of struts, characterized in that it comprises two identical banks, each built according to one of claims 9 to 13.

15. Adjustment method for a strut according to claim 1, which uses a bench according to one of claims 9 to 13, characterized in that it comprises the following operations: regulating the configuration of the bank based on the geometrical characteristics of the vehicle intended to receive the strut, - act on the regulation means to reach a predetermined optimal value of the observed parameter.

16. Strut of a Mac Pherson type wheel suspension, comprising a shock absorber provided with a body and a rod, the strut comprising a helical spring surrounding the rod, a lower support cup supported by the body of the shock absorber, the cup comprising lower a lower seat that receives one end of the spring, and a top support cup intended to rest on the vehicle body, the upper cup comprising an upper seat that receives the other end of the spring, with the upper cup being traversed by the rod, the body of the damper comprising a fastening seat to a hub carrier cooperating with fixing means, the hub holder defining a rotation axis of the wheel, one of the upper and lower cups containing an axial ball bearing which allows the rotation of the hub carrier, characterized in that the axis of the axial ball bearing and the pivot axis are non-concurrent.

17. Strut according to claim 16, characterized in that it comprises means for regulating the distance between the axis of the axial ball bearing and the pivot axis.

18. Strut according to claim 17, characterized in that the means comprise an upper ring of the axial ball bearing that rests on a small friction lining, the ring being guided in rotation about an axis perpendicular to the plane of the ring and being located in a point of its periphery, and comprising, on the opposite side of this axis, a rack (76) driven by a pinion attached to the shaft of an irreversible electric motorization system.