“MOTOR VEHICLE SUSPENSION SYSTEM INCLUDING A PAIR OF TRACKING ARMS, A TRANSVERSE LEAF SPRING AND RELATED CONNECTING UNITS”

Description

DESCRIPTION of the industrial invention entitled: “Suspension system for a motor vehicle including a pair of control arms oscillating, a transverse leaf spring and related connecting units” by: Stellantis Europe SpA, Italian nationality, Corso Giovanni Agnelli, 200 – 10135 Turin TO. Designated inventors: BADINO Renato; SANDRI Silvano. filed on: September 3, 2024 **** DESCRIPTION TEXT Field of invention The present invention relates to suspension systems of motor vehicle, of the type comprising, - a pair of wheel supports, - a pair of suspension wishbones respectively connected to a lower connecting portion of the wheel support, by means of at least one attack element, - a transverse leaf spring arranged transversely to the longitudinal direction of the motor vehicle, - where each end portion of the crossbow is connected to a an outer end portion of the swing arm by a drive unit connection. Known technique Suspension systems of the type indicated above have been used for a long time now. time. Solutions adopted to date for connecting the end parts of the transverse leaf spring with the swing arms provide rigid elements associated with elastomer material elements suitable for creating a independent wheel suspension, making it necessary to use an anti-roll system roll, such as a conventional anti-roll bar or anti-roll bar systems active. These solutions are not considered completely satisfactory, both by the from the point of view of the dynamic reaction of the suspension, both from the point of view of the overall life of the material connecting elements elastomer. Purpose of the invention The purpose of the present invention is to make available a suspension system of the type indicated above which is particularly effective, both from the point of view of vehicle dynamics and from the point of view of overall lifespan, minimizing the number of components needed for meet these needs. Summary of the invention According to the invention, one or more of the above objects are achieved by to a suspension system for a motor vehicle, comprising: - a pair of wheel supports, - a pair of suspension wishbones respectively connected to a lower connecting portion of the wheel support, by means of at least one attack element, - a subframe, - a transverse leaf spring arranged transversely to the longitudinal direction of the motor vehicle, connected to the auxiliary frame by two elastic inserts arranged symmetrically in correspondence with respective portions intermediate between the center of the crossbow and its end portions, - where each end portion of the crossbow is connected to a an outer end portion of the swing arm, by means of a unit connection including: - a spherical joint comprising a spherical body and a first stem rigidly connected to the swing arm, - an auxiliary coupling body comprising a receptacle engaged on the spherical body and a second stem rigidly connected to the end portion of the crossbow. Brief description of the drawings The invention will now be described in detail with reference to the attached drawings, provided purely as a non-limiting example, in which: - Figure 1 is a perspective view of a suspension system according to one embodiment of the invention, including a crossbow transversal, - figure 2 is a further perspective view of the crossbow transversal illustrated in the previous figures, - Figure 3 is an enlarged scale sectional view of a unit of connection prepared to connect a suspension swing arm and a part of the end of the crossbow, in accordance with possible shapes of implementation of the invention, and - figure 4 is a perspective view that highlights a deformed dynamic condition of the suspension leaf spring incorporating the the aforementioned connecting units, compared to a known type of suspension. Detailed description of the invention The following description illustrates various specific details aimed at to a thorough understanding of examples of one or more embodiments. Implementation forms may be realized without one or more of the details specific, or with other methods, components, materials, etc. In other cases, known structures, materials or operations are not shown or described in detail to avoid obscuring various aspects of the forms of implementation. The reference to “a form of implementation” in this description means that a particular configuration, structure or feature described in relation to the embodiment is included in at least one form of implementation. So, phrases like “in an embodiment”, possibly present in several places in this description, are not necessarily referring to the same form of implementation. Furthermore, particular conformations, structures or features can be combined appropriately in one or more forms of implementation and / or associated with the forms of implementation in a manner other than as illustrated here, so for example a feature exemplified here in relation a figure may be applied to one or more forms of implementation exemplified in a different figure. The references illustrated here are for convenience only and do not delimit therefore the scope of protection or the extent of the forms of implementation. In figure 1, the reference number 1 indicates, as a whole, a possible form of implementation of a suspension system according to the invention, comprising a transverse leaf spring 2 extending along a transverse axis with respect to the longitudinal direction of the vehicle, below the shell. The suspension system 1 illustrated in figure 1 represents a example of a vehicle rear suspension, incorporating the principles that are at the basis of the invention. However, the present invention is similarly applicable to various leaf spring vehicle suspension archetypes transverse, for front axle or rear axle. In a manner known per se, the suspension system 1 comprises for each wheel a wheel support (not shown) and a swing arm of suspension 3. Each swing arm 3 comprises a portion of external end designed to be connected to a lower portion of connection of the wheel support, by means of at least one attachment element 4, and an internal end portion connected to an auxiliary frame 5 of the suspension rigidly connected to the vehicle floor. In accordance with the embodiment illustrated in the attached figures, the the aforementioned attachment elements 4 are connecting levers having an inner end connected to arm 3 and an outer end connected to wheel support. Of course, the above mentioned attachment elements can also be configured differently than illustrated, so as to interface effectively with neighboring suspension components. As previously stated, suspension 1 comprises a leaf spring transverse 2 extending along an axis transverse to the direction longitudinal of the vehicle, under the body. The leaf spring 2 includes then two main opposing faces, in particular an upper face facing the vehicle floor and an opposite lower face. Preferably, the crossbow 2 is made of a single piece made of steel. In other embodiments, the crossbow 2 is made of a single piece made of composite material, including a reinforced plastic material matrix with fibers, such as carbon fibers. The crossbow 2 comprises a central portion 2' and two portions of end 2''. The leaf spring 2 is connected to the auxiliary frame 5 by two bolts 6 elastic bands arranged symmetrically in correspondence with intermediate portions of the crossbow 2, between the central portion 2' and the end portions 2'' According to possible embodiments, the transverse leaf spring 2 is configured as a leaf spring that counteracts the vertical movements of the two wheel supports. The width of the leaf spring - that is, the distance along the longitudinal direction of the vehicle between a leading edge and a trailing edge of the leaf spring – may differ along the longitudinal extension of the leaf spring foil. In some embodiments, note that the 2'' end portions of the crossbow 2 have a tapered shape with width in the direction longitudinal of the vehicle which decreases towards the wheel supports. Note which purposely varies the profile and / or shape and / or thickness in the area central crossbow 2, it is possible to obtain different effects of stabilization depending on the weight and performance of the vehicle on which you want to apply the suspension system previously described. The above described configuration of the crossbow 2 allows to fulfill effectively performs both the kinematic guide and elastic element functions vertical control of the wheels in the vertical shake stroke. As previously indicated, the leaf spring 2 is connected to the subframe 5 via two elastic plugs 6 arranged symmetrically in correspondence with intermediate portions of the crossbow 2, between the central portion 2' and the respective end portion 2''. Each elastic plug 6 includes an armature external 7 preferably of metallic material and a portion of material elastomer 8 inside the armor 7 and surrounding the crossbow 2 along all its sides, corresponding to the aforementioned intermediate portion. Note also that the presence of elastomeric material 8 inside the armor 7 is necessary to achieve an adequate shock-damping function of the leaf spring 3, in particular along the vertical direction of the vehicle. According to a further feature, each elastic plug 6 comprises at least two seats 9 to receive a respective fastening element connectable to the auxiliary frame 5. Looking at figure 2, note that the aforementioned seats 9 are obtained on the external frame 7, spaced apart and aligned in the longitudinal direction of the vehicle, as well as obtained along respective end flanges 7' of the armor 7, at the sides of the crossbow 2. It will therefore be appreciated that the 6 dowels carry out the locking of the 2 leaf springs under the body, so as to distribute the weight effectively of the crossbow and the related stresses, as well as helping to counteract effectively the translations of the leaf spring during vehicle dynamics, mainly along its longitudinal direction (i.e. along the transverse direction of the vehicle), but also along its transverse direction (i.e. along the longitudinal direction of the vehicle). Note also that the elastomer material 8 inside the armature 7 can be engaged on the respective crossbow parts, allowing small movements of the crossbow 2 along its longitudinal direction (i.e. along the transverse direction of the vehicle) As previously indicated, each swing arm 3 comprises an outer end portion connected to a lower portion of connection of the wheel support, by means of at least one attachment element 4. According to a further feature, each end portion 2'' of the crossbow 2 is connected to the outer end portion of the arm oscillating 3, by means of a connection unit 10 described below. As illustrated in Figure 3, the connection unit 10 comprises: - a ball joint 11 comprising a spherical body 12 and a first stem 13 rigidly connected to swing arm 3, - an auxiliary coupling body 14 comprising a receptacle 15 engaged on the spherical body 12 and a second stem 16 rigidly connected to the 2'' end portion of the crossbow 2. It will therefore be appreciated that the connection unit 10 comprises a double rod ball joint for connection with leaf spring 2 and arm oscillating 3. According to a further feature, the first stem 13 is also connected to said attachment element 4. More specifically, in the final configuration assembled, a first portion of the first stem 13 passes through a corresponding connection point of the swing arm 3, and a second portion of the first stem 13 passes through a corresponding connection point of the attachment element 4. The the connection thus obtained is tightened through a first nut lock 17 tightened along an end portion of the first stem 13. Similarly, with reference to the auxiliary coupling body 14, the second stem 16 passes through a corresponding point of connection of the 2'' end portion of the crossbow 2. The connection thus obtained is tightened through a second locking nut 18 tightened along an end portion of the second stem 14. Referring to figure 3, note that in the final configuration assembled on the suspension vehicle, the 2'' end portions of the crossbow 2 extend along a main plane which results in a height superior to the swing arms 3. It will therefore be appreciated that each unit of connection 10 has the spherical body 12 spaced between the lower face of the leaf spring 2 and an upper face of the swing arm 3, so that where the first stem 13 extends downwards from the spherical body 12 and the second stem 16 extends upwards from the spherical body 12, to achieve the aforementioned connections. The attachment position of the linkage unit relative to the arm oscillating and crossbow - with reference to the transverse horizontal direction of the vehicle - affects the transfer of vertical loads to the opposite wheel. The suspension system with 10 connection units as above described, guarantees only three degrees of freedom (i.e. rotations around the three axles). Thanks to the adoption of such connecting units 10, the suspension can finally be made without an anti-roll bar, considering that in dynamics vehicle (especially under conditions of asymmetric shaking) you get a dynamic behavior with semi-independent wheels, as the condition of compression on one side of the leaf spring can have positive effects on the condition rebound from the opposite side, effectively implementing it in the crossbow itself including the functions of the anti-roll bar. Figure 4 illustrates a deformed condition of the leaf spring 2 (in response (with relative stresses) equipped with connection unit 10 as described above (three degrees of freedom), compared to a 2' crossbow with traditional joints (six degrees of freedom). Note that for the same amount of shaking of the outer wheel in curve, the swing arms 3 relating to the leaf spring 2 equipped with connecting unit 10 – in conditions of asymmetric shaking – have less travel rebound relative to the 3' arm, producing an anti-roll bar-like effect. Naturally, without prejudice to the principle of the invention, the details of construction and forms of implementation may vary widely from as described and illustrated purely by way of example, without thereby departing from the scope of the present invention.

Claims

CLAIMS 1. Suspension system (1) for a motor vehicle, comprising: - a pair of wheel supports, - a pair of suspension wishbones (3) respectively connected to a lower connecting portion of the wheel support, by means of at least one attachment element (4), - an auxiliary frame (5), - a transverse leaf spring (2) configured to be arranged transversely with respect to the longitudinal direction of the motor vehicle, connected to the auxiliary frame (5) by means of two elastic blocks (6) arranged symmetrically in correspondence with respective intermediate portions between the centre of the leaf spring (2) and its end portions (2''), - wherein each end portion (2'') of the leaf spring (2) is connected to an external end portion of the wishbone (3), by means of a connection unit (10) comprising: - a ball joint (11) comprising a spherical body (12) and a first stem (13) rigidly connected to the arm oscillating (3),- an auxiliary coupling body (14) comprising a receptacle (15) engaged on the spherical body (12) and a second stem (16) rigidly connected to the end portion (2'') of the leaf spring (2)., 2. Suspension system (1) according to claim 1, wherein the first stem (13) is further connected to said attachment element (4).

3. Suspension system (1) according to claim 2, wherein a first portion of the first stem (13) passes through a corresponding connection point of the swing arm (3), and a second portion of the first stem (13) passes through a corresponding connection point of the attachment element (4).

4. Suspension system (1) according to claim 3, wherein the linkage unit (10) comprises a first locking nut (17) tightened along an end portion of the first stem (13).

5. Suspension system (1) according to claim 2, wherein the spherical body (12) is spaced between the lower face of the leaf spring (2) and an upper face of the wishbone (3), such that the first stem (13) extends downwards from the spherical body (12) and the second stem (16) extends upwards from the spherical body (12), with reference to the assembled condition on the vehicle.

6. Suspension system (1) according to claim 1, wherein each attachment element (4) is a connecting lever having an inner end connected to the arm (3) and an outer end connected to the wheel carrier.

7. Suspension system (1) according to claim 1, wherein the end portions (2'') of the leaf spring (2) have a tapered shape with width in the longitudinal direction of the motor vehicle decreasing towards the wheel supports.

8. Suspension system (1) according to claim 1, wherein each elastic piece (6) comprises an external armature (7) and a portion of elastomer material (8) internal to the armature (7) and surrounding the leaf spring (2) along all its sides, in correspondence with the aforementioned intermediate portion, wherein each elastic piece (6) comprises at least two seats (9) to receive a respective fixing element connectable to the auxiliary frame (5).

9. Suspension system (1) according to claim 8, wherein said seats (9) are obtained on the external armature (7), spaced apart and aligned in the longitudinal direction of the vehicle, as well as obtained along respective end flanges (7') of the armature (7), on the sides of the leaf spring (2).

10. Motor vehicle comprising a suspension system (1) according to any of the preceding claims.