WO2003100285A1

WO2003100285A1 - Vehicle suspension member and suspension equipped with same

Info

Publication number: WO2003100285A1
Application number: PCT/FR2003/050002
Authority: WO
Inventors: Mauro Bianchi
Original assignee: Mauro Bianchi S.A.
Priority date: 2002-05-28
Filing date: 2003-05-26
Publication date: 2003-12-04
Also published as: AU2003273151A1; FR2840256A1

Abstract

The invention concerns a vehicle suspension member designed to be compression-stressed during the extension of the vehicle suspension, comprising a spring element (2) elastically deformable during the compressive stress and a stop element (1) elastically deformable only during a first phase of compressive stress. The stop element (1) and the spring element (2) constitute a single component. The invention also concerns a vehicle suspension equipped with such a member. The invention is particularly applicable to motor vehicle suspensions with stiffness characteristics corresponding to a stiffness curve designed to reproduce the criteria constituting a contraction-type suspensionTM.

Description

"Suspension device for vehicle and suspension thus equipped"

The present invention relates to a vehicle suspension member and a vehicle suspension equipped with such a member.

The invention will particularly find its application in the field of the manufacture and use of suspensions for motor vehicles.

Several types of suspension are currently offered on the automotive market. In particular, conventional suspensions have linear flexibilities using stiffnesses which are the result of a compromise between vertical comfort and the vehicle body handling.

To optimize this compromise, anti-roll bars appeared which, during the transfer of the masses stiffen the suspensions when cornering in order to reduce the amplitudes of travel.

The disadvantage of these bars lies in the fact that they link the wheels of the same train (front axle and / or rear axle) making them less independent.

Another disadvantage is that this connection associated with the additional friction degrades the filtration of the vehicle as well in vertical, lateral comfort (copying) as in ascent in the whole of the direction.

In addition, mass transfers consecutive to longitudinal accelerations when diving or pitching up are always controlled by the only vertical stiffnesses of the suspensions. Variable flexibility suspensions have been proposed which attempt to overcome the drawbacks mentioned. However, all these techniques always require the adoption of anti-roll bars with the drawbacks which result therefrom.Moreover, for suspensions with variable flexibility, the compression stroke is reduced, and the rebound stroke increased, which produces a elevation of the center of gravity of the supporting vehicle, elevation detrimental to behavior

Furthermore, the state of the art is known and as presented in documents DE-A-3,826,831, US-A-4,962,916, DE-A-10026970 and FR- A-2,537,061 elements of suspension can be made of elastomeric material and constituting a stopper In certain cases, this stopper can have different stiffnesses. However, these are always elements with a stopper function to be used in the context of conventional suspensions therefore with classic stiffness characteristics. also proposed suspensions called intelligent, that is to say controlled by a central system incorporating electronic and computer means However, such suspensions are generally of high cost, and of relative reliability

So-called contractive® suspensions have also been proposed by the present applicant. In particular, document WO -A-9104876 presents a suspension provided with two distinct stiffnesses which revolve around the static position of the vehicle.

This static position is predetermined and configured, and delimits on the one hand the compression stroke, and on the other hand the rebound stroke. Furthermore, the stiffness of the suspension in the rebound stroke is greater than the stiffness of the suspension in compression stroke in a ratio of the order of 1 to 3

In other words, the stiffness in the compression stroke is relatively low and that in the rebound stroke considerably higher. The resulting stiffness curve is gradually decreasing, making the contractive® suspension a system completely opposed to suspensions with linear or progressive flexibility.

Still according to this prior technique, the point corresponding to the change between the two stiffnesses is located in the static position of the vehicle, that is to say corresponding on the travel of the suspension at the position of the vehicle when it is not subjected to any acceleration.

This point, hereinafter referred to as a self-stabilizing reference point, creates a natural stabilization position for the vehicle. At this particular point, an intermediate connection flexibility is set up between the stiffness in the compression phase and that in the expansion phase, and this to avoid too steep passage between the two.

This transition phase requiring flexibility of connection can be ensured by different technical solutions including that envisaged in WO-A-9104876 or also in document WO-A-9826193. In particular, an elastomer stop with asymptotic flexibility can be implemented and it is by means of this stop that the opposing spring will be put into action ensuring the additional stiffness necessary for the relaxation phase of this type of suspension. In current suspension arrangements according to this technique, use is made on the one hand of a stop member performing the connection function, and on the other hand of springs.

Although the various proposed solutions are technically satisfactory both in terms of vehicle behavior and industrialization, it appeared to the applicant that even more economical solutions should be sought.

The present invention falls within this framework, and aims to propose a suspension member implantable in a suspension for a vehicle, in particular of the automobile type, making it possible to reduce the manufacturing cost. Another advantage of the invention is to improve the ease of installation in the suspension, and this by reducing the number of component parts to be mounted.

Another advantage of the invention is to ensure ease of adjustment of the stiffness and damping criteria by means of the adaptation of a single piece.

Other objects and advantages will become apparent during the following description of a preferred embodiment of the suspension member according to the invention and of various embodiments of mounting in suspensions for vehicles. The present invention firstly relates to a suspension member for a vehicle capable of being subjected to compression, comprising a spring element which is elastically deformable during the compression stress and a stop element which is elastically deformable only during a first phase of compression stress. The stop element and the spring element are formed in one piece.

According to preferred variants, this suspension member is such that:

- The part is made of elastomeric material,

- The member is hollow for mounting around a rod, - It has at least one passage along the member, on its outer surface, so that it can be mounted in a hydraulic damper,

- The passage (s) consist of axial grooves. The invention also relates to a suspension for vehicles. It is equipped with a member according to the invention.

According to preferred embodiments, this suspension is such that:

- The member is mounted so as to be stressed in compression during the relaxation phases of the suspension. - It includes a hydraulic shock absorber in which the member is mounted.

- It comprises a movable floor applying to one end of the member and provided with at least one fluid passage valve, to generate additional damping during the deformation of the member.

- the organ is placed in opposition to the stiffness of the suspension

- It comprises three distinct stiffness phases formed by: o two linear stiffness segments, one of which corresponds to the desired stiffness during the compression phase of the suspension, and the other of which corresponds to the desired stiffness during the phase relaxing and is about three times steeper than the first o a connection phase with progressive stiffness so as to switch in an extremely regular manner from one linear stiffness segment to another.

The attached drawings are given by way of examples and are not limitative of the invention. They represent only one embodiment of the invention and will make it easy to understand it.

Figures 1 to 3 show schematically the formation of an organ according to the invention. FIG. 4 illustrates a first method of mounting the member according to the invention in a suspension, outside the hydraulic part of a shock absorber.

Figures 5 and 6 show two other examples of mounting the member according to the invention in opposition to one of the arms of the suspension. Figures 7 and 8 show another embodiment of the suspension assembly in which the member is positioned in a hydraulic damper.

FIG. 8 illustrates a particular arrangement of the stop with means for damping its displacement. Figure 9 shows schematically the stroke / effort curves observed according to the chosen suspension mode, namely of the linear, progressive or contractive® type.

Figure 10 shows an example of theoretical stiffness (Load in daN / Stroke in mm) of a contractive® suspension. Figure 1 1 shows an example of force / displacement curve that can reproduce an elastomeric member according to the invention.

FIG. 9 particularly illustrates the three general techniques currently envisaged for suspensions for a motor vehicle.

The curve marked L represents the stroke / force relationship produced in the context of suspension with linear flexibility.

The curve marked P presents the case of a suspension with progressive flexibility. Finally, the curve marked C is part of the contractive® technique. We observe the existence of two very distinct phases in expansion and compression with well-defined and different stiffnesses.

In the transition zone between the expansion and compression phases of the curve C, a flexibility r of connection is formed. On the ordinate axis, the initial prestressing force fp is shown, as well as the force interval corresponding to the connection phase fr.

Preferably, the connection phase corresponding to the reference r is positioned in the first part of the rebound stroke, and more precisely between the static position and the first part of the rebound stroke.

The realization of a suspension putting into practice the evolution of the stiffness shown in curve C of Figure 9, requires the use of stops and elastically deformable elements. The present invention presents a member capable of participating in such an embodiment of a suspension.

To achieve this, the member presented here by way of example comprises a stop element marked 1 in FIG. 1, as well as a spring element marked 2 in FIG. 2, the stop elements 1 and spring 2 being produced in a single part 13 visible in Figure 3.

The shape of the part 13 illustrated is only indicative. Those skilled in the art are able to envisage all embodiments producing the desired characteristics.

In this way, it is in particular possible to constitute the spring element necessary for the expansion phase, as well as the stop capable of producing the connecting arc of the contractive® suspension.

The stop element 1 is elastically deformable in compression up to a predetermined force value after which the stop element 1 is no longer deformable. The stiffness of this part of the suspension member is therefore of the asymptotic type.

The other element, the spring element 2, is elastically deformable during the compression stress of the suspension member. This elastic deformation goes beyond the pnase in which the connection stop is put into elastic work.

The part 13 thus formed by superposition of these two parts will advantageously be made of an elastomeric material easily produced in large series.

This forms a single piece 13 of low cost and capable of fulfilling the damping functions linked to the expansion and connection phases of the contractive® suspension.

As a preference, the suspension member has a substantially elongated shape as shown in FIG. 3, and is hollow in order to allow easier mounting, in particular on a rod as shown in the examples which are described below. .

According to a first mounting example illustrated in FIG. 4, the part 13 is mounted in a suspension for a vehicle comprising a shock absorber 6 of current design. As illustrated, the part 13 is mounted outside the hydraulic part of the shock absorber 6 shown, but on the rod 7 of this shock absorber. It is easy to understand the work in expansion and compression of the part 13 thus positioned.

In the example shown in FIG. 6, the part 13 is positioned in opposition to a suspension arm 8, said arm being pivotable about the axis 9.

Again, the part 13 is deformed in compression during the relaxation phases of the suspension with a preliminary deformation of the stop element 1, and a successive phase where only the spring element 2 is deformed.

Similarly, FIG. 5 illustrates another example of mounting the suspension member according to the invention at the level of a suspension arm.

According to this possibility, the part 13 will advantageously be positioned so that it does not protrude beyond the volume delimited by the suspension arm.

In general, it will be noted that the suspension member of the invention can be mounted on all types of suspension existing on the market.

In another example shown in FIGS. 7 and 8, the part 13 is mounted in the hydraulic part of a shock absorber 6. According to the figure, the part 13 is able to be compressed within the hydraulic part and also mounted on a rod 7 of the damper. In this context, it is advantageous to preserve fluid passages along the part 13 for proper operation of the hydraulic damper 6. In particular, passages in the form of axial grooves 3 in particular visible in Figure 3 can be formed.

The hydraulic operation of the damper 6 is therefore not hampered by the installation of the part 13, but can be modified by exploiting the rolling of the fluid on the periphery of the elastomer member. By adapting the diameter of the part 13, it is possible to produce a slight friction on the internal wall of the damper in the expansion phase, the part 13 swelling slightly in compression. This feature can be used to participate in depreciation by producing friction damping.

In the variant presented in FIG. 8, a movable floor 11 has been produced surmounting the part 13 and having a plurality of valves 12 for the passage of fluid in order to form the valve function. The abutment surface at the end of expansion is not systematically mechanically linked to the part 13, thanks to the movable floor 11.

Via floor 11, complementary damping means are produced during the deformation of the suspension member. Indeed, the movable floor 11 accompanies the deformation of the suspension member, but by providing additional damping.

In the decompression phase of the organ, the complementary damping function of the floor 11 persists until the suspension organ is completely relaxed, which has a beneficial effect on comfort.

It will be noted that the deformation in compression of the suspension member, particularly in elastomer will produce an increase in its diameter. The size of the member will therefore be adapted accordingly to the geometry of the suspension in which it is to be integrated, in order not to hinder the operation, in particular hydraulic, of the shock absorber.

In the preferred application to contractive® suspensions, FIGS. 10 and 11 show an example of the result capable of being obtained by the invention presented here. In this context, FIG. 10 shows the evolution of the stiffness of a suspension with, successively, a first linear segment corresponding to the relaxation of the suspension, an intermediate zone of non-linear stiffness located in the relaxation phase and producing an evolution progressive stiffness, a second linear segment corresponding to the compression phase of the suspension. The part 13 of the invention alone produces the first two phases.

To this end, a part 13 with the stiffness properties illustrated by the curve in FIG. 11 would be able to give satisfaction.

REFERENCES

1. Stop element

2. Spring element

3. Axial grooves

4. Shock absorber

5. Stem.

6. Suspension arms

7. Pivot axis

8. Stop surface

9. Movable floor

10. Valves

11. Elastomeric part

P. Progressive flexibility L. Linear flexibility C. Contractive ® system r. Flexible connection fp. Initial prestressing fr. Connection phase

Claims

1. Suspension for vehicle characterized in that

- It comprises a suspension member able to be stressed in compression, comprising a spring element (2) elastically deformable during the compression stress and a stop element (1) elastically deformable only during a first phase of compression stress, said member being such that the stop element (1) and the spring element (2) are formed in a single piece (13) - the member is placed in opposition to the stiffness of the suspension lift

- It comprises three distinct stiffness phases formed by: o two linear stiffness segments, one of which corresponds to the desired stiffness during the compression phase of the suspension, and the other of which corresponds to the desired stiffness during the phase of relaxation and is approximately three times stiffer than the first o a phase of connection with progressive stiffness so as to switch in an extremely regular way from one segment of linear stiffness to the other.

2. Suspension according to claim 1, characterized in that,

The part (13) is made of elastomeric material.

3. Suspension according to any one of claims 1 to 2, characterized in that,

That the suspension member is hollow for mounting around a rod

(7).

4. Suspension according to any one of claims 1 to 3, characterized in that the suspension member has at least one passage along the member, on its outer surface, so that it can be mounted in a hydraulic shock absorber.

5. Suspension according to claim 4, characterized in that, The passage or passages consist of axial grooves (3).

6. Suspension according to any one of claims 1 to 5, characterized in that,

That it includes a hydraulic shock absorber (6) in which the member is mounted.

7. Suspension according to claim 6, characterized by the fact,

That it comprises a movable floor (11) applying to one end of the member and provided with at least one valve (12) for passage of fluid, to generate additional damping during the deformation of the organ.