Motor-vehicle suspension system, with transversal leaf spring and active elastic blocks

Abstract

Motor-vehicle suspension system (1), comprising a transversal leaf spring (2) arranged transversely with respect to the longitudinal direction of the motor-vehicle, connected to the motor-vehicle structure by means of two elastic blocks (5) symmetrically arranged at respective intermediate portions (2''') between the center of the leaf spring (2) and its end portions (2''), said transversal leaf spring (2) being configured as a foil spring adapted to oppose the vertical movements of the two wheel supports (4), wherein each elastic block (5) comprises: - an outer reinforcement (10), - at least two elastomeric components (11) included inside the outer reinforcement (10), mutually placed side by side along the longitudinal direction of the leaf spring (2) and surrounding the leaf spring (2) along all its sides at said intermediate portion (2'''), wherein said at least two elastomeric components (11) respectively shape an internal chamber fillable with a pressurized fluid, - a valve body (17) having an inlet port (17') connectable to a pressurized fluid supply system and at least two outlet ports (17'') respectively in communication with said at least two elastomeric components (11), - wherein said at least two elastomeric components (11) are selectively activated by filling the internal chamber, to pass from an inactive configuration in which the outer surface of the leaf spring (2) is not in contact with the elastomeric component (11), to an active configuration in which the elastomeric component (11) has an enlarged volume for creating a grip effect on the leaf spring (2) at said intermediate portion (2''').

Description

[0001] “Motor-vehicle suspension system, with transversal leaf spring and active elastic blocks”

[0002] ****

[0003] TEXT OF THE DESCRIPTION

[0004] Field of the invention

[0005] The present invention relates to motor-vehicle suspension systems, of the type comprising,

[0006] - a pair of wheel supports,

[0007] - a transversal leaf spring arranged transversely to the longitudinal direction of the motor-vehicle, comprising two elastic blocks arranged symmetrically at respective intermediate portions between the center of the leaf spring and its end portions,

[0008] - each elastic block comprising at least one seat for receiving a respective fastening element which can be connected to the motor-vehicle structure,

[0009] - said end portions of the leaf spring being connected to the wheel supports by means of respective attachment elements connected to each end of the leaf spring.

[0010] Prior art

[0011] A suspension system of the type indicated above is, for example, described and illustrated in documents CN 104 057 795 and WO 2022 034 757. The solution described in CN 104 057 795 refers to a suspension system of the double quadrilateral type, in which the transversal leaf spring has a thickness gradually decreasing in the direction of the wheel supports.

[0012] The suspension described in document CN 104 057 795, however, has some drawbacks of any kind, including having the leaf spring subject to unwanted excursions along its longitudinal direction. In this perspective, the solution described in WO 2022 034 757 includes adjustable elastic support blocks.

[0013] However, the present invention therefore starts from the desire to provide a suspension system of the type indicated at the beginning of this description, which is improved from several points of view. Object of the invention

[0014] The object of the present invention is to provide a suspension system of the type indicated above that is particularly effective, as well as suitable for performing the typical functions of transversal arm, spring and stabilizer bar, with an extremely small number of components.

[0015] A further object of the invention is to propose a suspension system of the type indicated above, easily adaptable for assembly on different vehicle models, depending on the weight and overall performance.

[0016] A further object of the invention is to provide a suspension system that offers the driver the possibility of customizing the heights and stiffnesses of the wheel assemblies connected to the transversal leaf spring.

[0017] Summary of the invention

[0018] According to the invention, one or more of said objects are achieved thanks to a suspension having the features indicated in the attached claims.

[0019] Thanks to these features, it is possible to achieve a series of important advantages compared to the prior art, including:

[0020] - reducing the number of components that generally make up the suspension system;

[0021] - reducing the related production costs;

[0022] - obtaining multiple variations of suspension performance with the same leaf spring;

[0023] - easily diversifying the suspension according to the vehicle model and the overall suspension archetype.

[0024] Brief description of the drawings

[0025] The invention will now be described in detail with reference to the attached drawings, provided purely by way of non-limiting example, in which:

[0026] - figures 1 , 2 are perspective views of a suspension system including a transversal leaf spring, according to different embodiments,

[0027] - figures 3A, 3B, 3C illustrate different leaf springs that can be associated with the suspension system of the invention,

[0028] - figure 4 is a perspective view of a suspension system according to a further embodiment, including active elastic blocks, - figure 5 is an enlarged scale view of the leaf spring and one of the active elastic blocks,

[0029] - figure 6 is a perspective view of one of the active blocks, which highlights a plurality of elastomeric components included within an outer reinforcement of the block,

[0030] - figure 7 is a sectional view highlighting one of the elastomeric components in an active configuration, and

[0031] - figure 8 is a further perspective view of the transversal leaf spring highlighting certain advantages of the invention.

[0032] Detailed description of the invention

[0033] In the following description, various specific details are illustrated to aid in a thorough understanding of examples of one or more embodiments. Embodiments may be implemented without one or more of the specific details, or with other methods, components, materials, etc.

[0034] In other cases, known structures, materials, or operations are not shown or described in detail to avoid obscuring various aspects of the embodiments.

[0035] Reference to “an / one embodiment” in this specification means that a particular configuration, structure, or feature described in connection with the embodiment is included in at least one embodiment.

[0036] Thus, phrases such as “in an / one embodiment,” which may appear in multiple places in this specification, do not necessarily refer to the same embodiment. Furthermore, particular conformations, structures or features may be combined in an appropriate manner in one or more embodiments and / or associated with the embodiments in a manner other than as illustrated herein, so that for example a feature exemplified herein in relation to a figure may be applied to one or more embodiments exemplified in a different figure.

[0037] The references illustrated herein are for convenience only and therefore do not delimit the extent of protection or the scope of the embodiments.

[0038] In figures 1 , 2, 4, the reference number 1 indicates, as a whole, embodiments of a suspension system comprising a transversal leaf spring More specifically, the suspension system 1 illustrated in figure 1 represents an example of a rear vehicle suspension, while the suspension system 1 illustrated in figure 2 represents an example of a MacPherson type front suspension, both incorporating the principles underlying the invention. Therefore, the present invention is similarly applicable to different archetypes of motor-vehicle suspension, for front axle or rear axle.

[0039] The suspension system 1 comprises for each wheel, in a way known per se, a shock absorber unit 3 connected to a related wheel support 4.

[0040] According to an essential feature of the invention, each of the wheel supports 4 is connected to a leaf spring 2 that extends along a transversal axis with respect to the longitudinal direction of the vehicle, below the body.

[0041] The leaf spring 2 comprises a central portion 2’ and two end portions 2” respectively connected to the wheel supports 4. The leaf spring 2 is also connected to the motor-vehicle structure (not illustrated) by means of two elastic blocks 5 symmetrically arranged at intermediate portions 2”’ of the leaf spring 2, between the central portion 2’ and the end portions 2”. According to different embodiments, the elastic blocks 5 can be connected directly to the floor of the motor-vehicle or to a mechanical frame 1 ’ (partially illustrated in figures 5-8) rigidly connected to the floor.

[0042] The opposite ends of the leaf spring 2 are connected to the wheel supports 4 by means of respective attachment elements 6, 7 rigidly secured to each end of the leaf spring 2. According to the embodiment illustrated in figure 1 , said attachment elements are cylindrical hinges 6 with hinge axis directed parallel to the longitudinal direction of the vehicle, arranged to interface with a lower portion 4' of the respective wheel support 4. According to the embodiment illustrated in figures 2, 4, said attachment elements are spherical heads 7 with vertical axis, arranged for interfacing with a lower portion 4' of the respective wheel support 4. Of course, said attachment elements can also be configured differently than illustrated, so as to interface effectively with the adjacent components of the suspension.

[0043] According to a further feature of the invention, the transversal leaf spring 2 is configured as a foil spring that oppose the vertical movements of the two wheel supports 4. The foil spring therefore has two opposing main faces, in particular an upper face facing the vehicle floor and an opposite lower face, and a considerably thin thickness. The width of the foil spring - i.e. the distance along the longitudinal direction of the vehicle between a front edge and a rear edge of the foil spring - is variable along the longitudinal extension of the foil spring, according to the features described below.

[0044] Preferably, the foil spring consists of a single piece made of steel. In other embodiments, the foil spring consists of a single piece made of composite material, including a matrix made of plastic material reinforced with fibers, for example carbon fibers.

[0045] Figures 3A-3C are elevation views illustrating different embodiments of the foil spring. In all embodiments, note that the foil spring has a maximum width at the intermediate portions 2”’, while the end portions 2” of the foil spring have a tapered shape with a width in the longitudinal direction of the motor-vehicle that decreases towards the wheel supports 4. In other words, the end portions 2” of the foil spring - which extend beyond said intermediate portions 2”’ - have a substantially triangular configuration, with a base constrained to the vehicle structure by means of the elastic blocks 5 and a vertex at the end of the foil spring, pivotally connected to the wheel support 4.

[0046] The configuration of the leaf spring 2 described above allows it to effectively perform the functions of both kinematic guide and elastic element for vertical control of the wheels in the vertical shaking stroke.

[0047] It will therefore be appreciated that the suspension system comprises a transversal leaf spring 2 configured as a foil spring designed to perform various functions in a single component, such as the functions typically performed by a transversal suspension arm, the stabilizer bar and elastic elements designed to dampen vertical stresses.

[0048] Furthermore, by specifically varying the profile and / or shape and / or thickness in the central area of the leaf spring 2, it is possible to obtain different stabilization effects depending on the weight and performance of the vehicle on which the previously described suspension system is to be applied. In this regard, still with reference to figures 3A-3C, note that the central portion 2' of the foil spring has an overall reduced width compared to the width provided at said intermediate portions 2"'. Preferably, said central portion 2' has a minimum width at the center of the foil spring and an increasing width from the center of the foil spring towards the blocks 5, with a curvilinear profile symmetrical with respect to the center of the foil spring. In other words, proceeding from a first elastic block 5 towards the center of the foil spring, the width progressively decreases until a minimum value along the center of the foil spring, and proceeding from the center of the foil spring towards the second elastic block 5, the width progressively increases, with a curvilinear profile. In alternative embodiments not illustrated, the central portion 2’ of the foil spring has a substantially constant width so as to create an overall more rigid body than that illustrated in figures 3A-3C.

[0049] According to a further feature illustrated in figure 3C, the foil spring may have at least one lightening opening 12, provided substantially along the central portion 2’ between the two elastic blocks 5. This lightening opening 12 is useful not only to obtain a suspension system with a lower weight, but also to allow the assembly of any adjacent motor-vehicle components, avoiding the bulk of the central portion 2’ of the foil spring.

[0050] As previously indicated, the leaf spring 2 is connected to the motorvehicle structure (not illustrated) by means of two elastic blocks 5 symmetrically arranged at intermediate portions 2”’ of the leaf spring 2, between the central portion 2’ and the respective end portion 2”. Each elastic block 5 comprises an outer reinforcement 10, preferably made of metal material, surrounding the leaf spring 2 at one of the intermediate portions 2”’.

[0051] According to a further feature of the invention, each elastic block 5 comprises two seats 8 for receiving a respective fastening element 9 which can be connected to the motor-vehicle structure. Said seats 8 are spaced apart from each other and aligned in the longitudinal direction of the motorvehicle. By observing the embodiment of figures 1 , 2, it should be noted that the fastening elements 9 - for example made in the form of bushings - and the respective seats 8 can have a vertical main axis perpendicular to the upper and lower faces of the foil spring. The seats 8 can be obtained along an upper portion of the respective block 5 above the upper face of the foil spring. By observing the embodiment of figures 4-8, note that the fastening elements 9 - for example made in the form of fastening screws - and the respective seats 8 can have a horizontal axis parallel to the longitudinal direction of the foil spring. In all the embodiments described and illustrated, it will therefore be appreciated that the blocks 5 provide the locking of the foil spring under the body, so as to effectively distribute the weight of the foil spring and the related stresses.

[0052] According to a further feature of the invention, the foil spring comprises at least one further constraint element 13, additional to the fastening elements 9, to effectively oppose the translations of the foil spring during vehicle dynamics, mainly along its longitudinal direction (i.e. along the transversal direction of the vehicle), but also along its transversal direction (i.e. along the longitudinal direction of the vehicle). In other words, said further constraint element 13 allows to effectively obtain an anti-slip function of the foil spring along said directions with respect to the elastic blocks 5 which remain locked to the vehicle structure. In one or more embodiments, the constraint elements 13 have a vertical main axis perpendicular to the upper and lower faces of the foil spring. In one or more embodiments, the foil spring comprises two constraint elements 13, made in the form of pins 13’ mounted at a respective elastic block 5. By observing figure 7, note that each pin 13’ is rigidly connected to the foil spring, within a seat 14 vertically obtained along the body of the foil spring at the elastic block 5, in an intermediate position between the two fastening elements 9. The seat 14 comprises a through hole obtained along the body of the foil spring and along the elastic block. In one or more embodiments, the outer reinforcement 10 has a through hole with upper and lower ends 15, 16 for the assembly of said constraint element 13 and an anti-rotation bushing 13”.

[0053] According to a peculiar feature of the present invention, illustrated in figures 4-8, each elastic block 5 comprises a plurality of elastomeric components 11 included inside the outer reinforcement 10 and mutually placed side by side along the longitudinal direction of the leaf spring 2, each surrounding the surface of the leaf spring 2 at said intermediate portion 2"'. The elastomeric components 11 respectively form an internal chamber that can be filled with a pressurized fluid (oil, compressed air, etc.). According to a preferred embodiment, each elastic block 5 comprises three elastomeric components 11 mutually placed side by side along the longitudinal direction of the leaf spring 2. It should also be noted that the presence of elastomeric material 11 inside the reinforcement 10 is necessary to achieve an adequate damping function of the shocks of the foil spring, in particular along the vertical direction of the vehicle. Still referring to figures 4-8, each elastic block 5 comprises a valve body 17 having an inlet port 17’ connectable to a supply system (not shown) on-board to vehicle, to supply the pressurized fluid to the elastomeric components 11 , and a plurality of outlet ports 17” respectively in communication with the chamber of each elastomeric component 11.

[0054] According to a further feature, the elastomeric components 11 are selectively activated by filling the respective internal chamber, to pass from an inactive configuration in which the outer surface of the leaf spring 2 is not in contact with the elastomeric component 11 (or otherwise in contact, but without exerting a locking effect on the body of the leaf spring), to an active configuration in which the elastomeric component 11 has an enlarged volume for creating a grip effect on the leaf spring 2 at said intermediate portion 2”’. In this regard, in figure 7, the elastomeric component 11 adjacent to the frame T is illustrated in an active configuration gripping the surface of the leaf spring 2, while the other two are illustrated in an inactive configuration without contact with the surface of the leaf spring 2. It will therefore be appreciated that, in operation, for each block 5, at least one elastomeric component 11 must be in an active configuration.

[0055] According to the features described above, the elastic blocks 5 are configured as “active blocks” designed to customize the stiffness / flexibility of the wheel assemblies connected to the opposite ends of the leaf spring, and consequently obtain the variation of the height from the ground of the vehicle, depending on the locking condition of the leaf spring carried out with the selection of determined elastomeric components 11. In fact, as illustrated in figure 8, with the same block 5 it is possible to obtain three different arm lengths L1 , L2, L3 - distance along the longitudinal axis of the leaf spring 2 between the end connected to the wheel assembly and the activated elastomeric component 11 -, thus varying the stiffness of the suspension; with the length L3 indicated in figure 8, a stiffer suspension will be obtained compared to a configuration with length L1 , given that, with the same stress, in the latter case the oscillation of the leaf spring and the wheel shaking are increased.

[0056] According to a further feature of the invention, the motor-vehicle comprises an electronic controller configured and programmed for implementing a control logic for the selective inflation of the elastomeric components 11 of each block 5, to automatically obtain a variation in the stiffness / flexibility of the suspension. Preferably, the electronic controller is arranged for automatically activating an inflation of the elastomeric components 11 , simultaneously and correspondingly on the two elastic blocks 5. The selection of which elastomeric components 11 to activate can be carried out automatically in vehicle dynamics, depending on some operative parameters, such as the vehicle speed and / or the steering angle of the wheels. For example, the electronic control can be programmed for activating the elastomeric components 11 spaced at a larger distance from the respective end of the leaf spring, to obtain a more flexible suspension, whenever the vehicle has a speed lower than 10 km / h.

[0057] According to a further feature, the electronic controller is designed for automatically activating an inflation of the elastomeric components 11 , in a diversified manner on the two elastic blocks 5, for example by further stiffening a first block corresponding to the wheel most stressed when taking a bend at high speed.

[0058] According to a further feature, the selective inflation of the elastomeric components 11 of each block 5 is carried out according to the driver’s manual selection of a selector device that allows the selection of different vehicle performance modes (for example, comfort or sporty driving). In this case, the selection made will correspond to the activation of the elastomeric components 11 to obtain a more rigid or more flexible suspension.

[0059] Of course, notwithstanding the principle of the invention, the construction details and the embodiments may vary widely with respect to what is described and illustrated purely by way of example, without thereby departing from the scope of the present invention.

Claims

CLAIMS1. A motor-vehicle suspension system (1 ), comprising:- a pair of wheel supports (4),- a transversal leaf spring (2) configured to be arranged transversely with respect to the longitudinal direction of the motor-vehicle, comprising two elastic blocks (5) symmetrically arranged at respective intermediate portions (2”’) between the center of the leaf spring (2) and its end portions (2”),- each elastic block (5) comprising at least one seat (8) for receiving a respective fastening element (9) which can be connected to the motorvehicle structure,- said end portions (2”) of the leaf spring (2) being connected to the wheel supports (4) by means of respective attachment elements (6, 7) connected to each end of the leaf spring (2),- said transversal leaf spring (2) being configured as a foil spring adapted to oppose the vertical movements of the two wheel supports (4),- wherein each elastic block (5) comprises:- an outer reinforcement (10),- at least two elastomeric components (11 ) included inside the outer reinforcement (10), mutually placed side by side along the longitudinal direction of the leaf spring (2) and surrounding the leaf spring (2) along all its sides at said intermediate portion (2”’), wherein said at least two elastomeric components (11 ) are selectively inflatable with a pressurized fluid,- a valve body (17) having an inlet port (17’) connectable to a pressurized fluid supply system and at least two outlet ports (17”) respectively in communication with said at least two elastomeric components (11 ),- said at least two elastomeric components (11 ) being selectively activated by their filling with a pressurized fluid, to pass from an inactive configuration in which the outer surface of the leaf spring (2) is not in contact with the elastomeric component (11 ), to an active configuration in which the elastomeric component (11 ) has an enlarged volume for creating a grip effect on the leaf spring (2) at said intermediate portion (2”’), wherein, inoperation, at least one elastomeric component (11 ) is in the active configuration,- in such a way as to customize the stiffness of the wheel assemblies connected to the opposite ends of the foil spring, depending on the locking condition of the foil spring carried out with the activation of determined elastomeric components (11 ).

2. The suspension system (1 ) according to claim 1 , wherein each elastic block (5) comprises three elastomeric components (11 ) mutually placed side by side along the longitudinal direction of the leaf spring (2).

3. The suspension system (1 ) according to claim 1 or 2, wherein said foil spring comprises at least one further constraint element (13), additional to the fastening elements (9), to oppose a translation of the foil spring along the transversal and longitudinal direction.

4. The suspension system (1 ) according to any of the preceding claims, wherein said end portions (2”) have a substantially triangular configuration, with a base configured to be constrained to the vehicle structure by means of said elastic blocks (5) and a vertex at the end of the foil spring configured to be pivotally connected to the wheel support (4),5. The motor-vehicle comprising a suspension system (1 ) according to any of the preceding claims, wherein the motor-vehicle further comprises an electronic controller configured and programmed for implementing a control logic for the selective inflation of the elastomeric components (11 ) of each block (5), to obtain a variation in the stiffness or flexibility of the suspension.

6. The motor-vehicle according to claim 5, wherein the electronic controller is arranged for automatically activating an inflation of the elastomeric components (11 ), simultaneously and correspondingly on the two elastic blocks (5), depending on some operative parameters, such as the vehicle speed and / or the steering angle of the wheels.

7. The motor-vehicle according to claim 6, wherein the electronic controller is arranged for activating the elastomeric components (11 ) spaced at a larger distance from the respective attachment element (6, 7), if the vehicle has a speed lower than 10 km / h.

8. The motor-vehicle according to claim 5, wherein the electronic controller is arranged for controlling the selective inflation of the elastomeric components (11 ) according to the driver’s manual selection of a selector device configured for providing different vehicle dynamic performance modes.

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