Device for adjusting the bumper gap in a vehicle suspension and vehicle suspension comprising the device

Abstract

A device (9) for adjusting the bumper clearance and / or the spring pre-tightening force in a vehicle suspension, comprising an internally hollow cylindrical body (12); a main flange (14) adapted to be connected to the upper end of the shock absorber rod (18) of the suspended mass of the vehicle; a secondary flange (16) adapted to form the upper seat of the main spring of the vehicle suspension; a main actuator (20) coaxial with the cylindrical body (12) and slidably received inside the cylindrical body (12); a bumper (24) adapted to form a limit stop for the oscillations of the suspended mass of the vehicle by abutting against the shock absorber cylinder of the vehicle suspension; wherein the main actuator assembly (20) and the bumper (24) are configured to be axially crossed by the shock absorber rod (18) and to slide with respect to the shock absorber rod (18).

Description

TECHNICAL FIELD

[0001] The present invention belongs to the field of automotive components; in particular, it relates to a device for adjusting the bumper gap and / or the spring pre-tightening force of a vehicle suspension, a suspension comprising said device and a method for adjusting said suspension. SUMMARY

[0002] The wheel suspensions of known type comprise a spring (for example a helical spring or a similar elastic element) interposed between the wheel and the bodywork, and a shock absorber also interposed between the wheel and the bodywork, parallel to the spring.

[0003] In designing a wheel suspension of the type described above, the designer must each time find the best compromise between two conflicting requirements, i.e. the grip performance (and therefore the safety) and the comfort, according to the specific application. In particular, the two parameters involved in defining the characteristics of the suspension so as to determine the best compromise between grip performance and comfort are the stiffness of the spring and the damping of the shock absorber. The design choice usually depends on the type of use for which the vehicle is designed. For sports vehicles, naturally more attention is paid to the grip performance, thus impairing the comfort; for compact cars, for example, more attention is paid to the comfort, thus impairing the grip performance.

[0004] Since the operating conditions suitable for giving priority to the grip performance are usually different from those suitable for giving priority to the comfort, it is known to use active suspension control systems which allow to actively adjust in real time the characteristics of the suspension according to the driving conditions of the vehicle.

[0005] For example, it is known to allow the variation of the force-velocity characteristic curve of the shock absorber, so as to vary the force between the sprung mass and the unsprung mass of the vehicle during transient phases of the vehicle dynamics.

[0006] It is also known to allow a controlled variation of the spring stiffness, so as to vary the force exerted between the sprung mass and the unsprung mass of the vehicle not only during transient phases of the vehicle dynamics, but also in steady state conditions (for example when cornering). These control systems are able to vary the overall stiffness of the suspension, also allowing to vary the attitude of the vehicle in static conditions, to achieve different objectives of comfort or grip performance, and to adapt the attitude of the vehicle to possible load variations.

[0007] An example of a solution belonging to this second category of active suspension control systems is known from WO 2018092110A1, which describes a suspension for a wheel provided with an active control system to continuously adjust the overall stiffness of the suspension at said wheel, i.e. the relationship of the force exerted between the sprung mass and the unsprung mass of the vehicle and the relative position of the sprung mass of the vehicle with respect to the unsprung mass.

[0008] Additional examples of control systems are known from JP S62 27809 U, JP S6448307 U, JP H1095217 A, US2009 / 302559 A1 and JP 2003 205722 A.

[0009] It is an object of the present application to provide a different device which allows to adjust the distance between the elastic damper and the unsprung mass of a vehicle, so as to reduce or increase the vertical travel of the suspension mass with respect to the unsprung mass (for example by creating a limit stop for the cylindrical body of the damper in the compression phase of the damper), and / or to adjust the pre-tightening of the main spring of the suspension (acting in parallel with respect to the damper), preferably while allowing to adjust the distance between the spring plate (connected to the unsprung mass, for example to a structure integral with the wheel hub, or to the cylindrical body of the damper of the car) and the suspension mass of the vehicle (to change the height of the suspension mass from the ground in static conditions).

[0010] It is a further object of the present application to provide an adjustment device with a reduced radial footprint.

[0011] To achieve this result, a device for adjusting the damper clearance and / or the spring pre-tightening in a vehicle suspension comprises a hydraulic actuator adapted to apply a stroke to the damper along the axis of the suspension (either approaching or distancing from the damper cylinder connected to the unsprung mass of the vehicle), said actuator being independent from the adjustment of the vehicle attitude (i.e. from the length of the main spring acting in parallel with the damper).

[0012] The above and other objects and advantages are achieved, according to one aspect of the present application, by a device for adjusting the damper clearance and / or the spring pre-tightening of a vehicle suspension, having the characteristics defined in the appended claims, by a suspension comprising said device and by a method for adjusting said suspension. Preferred embodiments of the present application are defined in the dependent claims.

[0013] BRIEF DESCRIPTION OF DRAWINGS

[0014] The function and structural features of some preferred embodiments of the device for adjusting the damper clearance in a vehicle suspension according to the present application and of the vehicle suspension comprising said device will now be described. Reference is made to the attached drawings, wherein:

[0015] - Figure 1 is a schematic axial cross-section of a device for adjusting the damper clearance in a vehicle suspension according to an embodiment of the present application;

[0016] - Figures 2 and 3 are schematic axial cross-sections of the device in Figure 1 , shown in two operating configurations, a first attitude optimized for track use and a second attitude optimized for normal road use, respectively; and

[0017] - Figures 4A and 4B are axial cross-sectional views of the device in Figure 1 , in which the axial stroke of the abutment flanges of the bumper and of the main spring is shown in the two operating configurations shown in Figures 3 and 2, respectively. DETAILED DESCRIPTION

[0018] Before describing several embodiments of the application in detail, it is to be understood that the application is not limited in its application to the details of design and construction presented in the following description or illustrated in the drawings. The application is capable of other embodiments and of being practiced or being carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein are for the purpose of description and should in no way be regarded as limiting.

[0019] For example, see Figure 1 , the device 9 for adjusting the bumper gap and / or the spring pre-tension in a vehicle suspension comprises a head element 10 comprising a cylindrical body 12 comprising an internal cavity and extending along a main axis x, and a main flange 14 integral with the cylindrical body 12 and adapted to be connected to the suspended mass of the vehicle, said main flange 14 being configured to be attached to the upper end of a conventional shock absorber rod 18, which is integral at its lower end with a shock absorber piston slidable inside a shock absorber cylinder.

[0020] The device 9 further comprises a secondary flange 16 located radially external to the cylindrical body 12 and adapted to form an upper seat for the main spring of the vehicle suspension.

[0021] A main actuator 20 is also provided, which is coaxial with the cylindrical body 12 and is slidably received inside said cylindrical body 12. The main actuator 20 comprises a third flange 20a having a surface extending on a plane perpendicular to the main axis x and facing the main flange 14. Said third flange surface 20a defines a lower portion of a main chamber 13a, which forms a volumetric portion of the cylindrical body 12 internal cavity, said main chamber 13a being in fluid communication with the outside of the cylindrical body 12. The third flange 20a is configured to slide inside the cylindrical body 12 along the main axis x in response to the pressure of the fluid entering the main chamber 13a.

[0022] Device 9 includes a damper 24, which is adapted to act as a limiting stop for suspension mass oscillations of the vehicle when the vehicle's suspension mass approaches the vehicle's unsprung mass, by abutting against a shock absorber cylinder of the vehicle suspension. The damper 24 is integrally movable along the main axis x with the main actuator 20 (conveniently, it is at least partially received within the third flange 20a). The damper 24 (typically made of a microporous elastomer based on polyurethane) is of a type typically disposed in the wheel suspension to elastically counteract shock absorber compression when the element abuts against the upper end of the shock absorber cylinder.

[0023] The main actuator assembly 20 and the damper 24 are configured to pass axially through and slide relative to the shock absorber rod 18. Therefore, in the assembled state of the vehicle suspension, the main actuator assembly 20 and the damper 24 are slidably movable relative to the shock absorber rod 18 along its outer surface (and thus along the main axis x). This allows the adjustment of the damper clearance 24 to be independent of the main spring of the suspension.

[0024] The inner cavity of the cylindrical body 12 includes a secondary chamber 13b, which is axially stacked on top of the main chamber 13a and separated from the main chamber 13a by a separation partition extending radially from the cylindrical body 12 toward the main axis x. The main actuator includes a cylindrical portion 20b integral with a third flange 20a and slidably passing through the separation partition, thereby fluidly separating the main chamber 13a from the secondary chamber 13b. The secondary chamber 13b is in fluid communication with the outside of the cylindrical body 12, and the main chamber 13a is defined below by the third flange 20a and above by the separation partition.

[0025] The cylindrical body 12 includes an annular shoulder that extends radially toward the main axis x and is axially positioned below the main actuator 20. The device 9 may include a secondary spring 26, one end of which engages the annular shoulder, and the opposite end engages a third flange 20a. The secondary spring 26 is configured to push the third flange 20a toward the separation partition.

[0026] According to an alternative (not shown), the elastomeric buffer 24 is replaced by a spring (which may be a secondary spring 26, in which case the buffer 24 will not exist, or it will be a spring support against the cylindrical body of the shock absorber).

[0027] According to one embodiment (not shown), the secondary flange 16 is translated relative to the head element 10 (and conveniently, can coincide with or be rigidly connected to the main flange 14).

[0028] According to an alternative embodiment, the main flange 14 has an annular groove located radially outside the cylindrical body 12 and fluidly communicating with the exterior of the head element 10, and the secondary flange 16 is slidable relative to the cylindrical body 12 of the head element 10 along the main axis x. The secondary flange 16 is integrally movable with a secondary actuator 28 having an upper edge slidably received in the annular groove and configured to slide along the main axis x in response to the pressure of fluid entering the annular groove, the annular groove being fluidly separated from the main chamber 13a.

[0029] The device 9 having the above-described features can be configured to allow for dual adjustment of the vehicle suspension (attitude and damper clearance), for example, as shown in Figures 2 to 4B.

[0030] Specifically, Figure 2 illustrates the configuration of the adjustment device 9 optimized for track use, where vehicle driving performance is prioritized at the expense of comfort. In this configuration, the attitude (i.e., the vehicle's ground clearance) is minimized because the secondary actuator 28 is retracted to its maximum extent into the annular groove of the main flange 14, bringing the secondary flange 16 closer to the main flange 14, thereby reducing the distance between the lower spring plate (on which the main spring of the suspension rests at the bottom) and the main flange 14 (which represents the attachment point of the suspension to the vehicle's suspended mass). Simultaneously, the main actuator 20 is positioned at its lower end relative to the cylindrical body 12 (the main chamber 13a is filled with fluid), thereby reducing the compression stroke of the damper 24 relative to the cylinder (not shown) of the shock absorber.

[0031] On the other hand, Figure 3 shows a configuration of the adjustment device 9 optimized for road use, where comfort is prioritized at the expense of vehicle driving performance. In this configuration, the attitude (i.e., the vehicle's ground clearance) is raised relative to the configuration in Figure 2 because the secondary actuator 28 partially disengages from the annular groove of the main flange 14 (which occurs, in the state of the adjustment device assembled with the suspension, by lifting the head element 10 relative to the point of unsprung mass constrained to the vehicle by the suspension), bringing the secondary flange 16 away from the main flange 14, thereby increasing the distance between the lower spring plate and the main flange 14. Simultaneously, the main actuator 20 is positioned at its upper end relative to the cylindrical body 12 (the main chamber 13a is emptied of fluid), thereby increasing the compression stroke of the damper 24 relative to the shock absorber cylinder (not shown).

[0032] As illustrated in Figures 4A and 4B, when the adjustment device 9 is switched from a configuration optimized for use on the road to a configuration optimized for use on the track, the main actuator 20 decreases by an amount “a” relative to its upper end travel (in the illustrated example, this upper end travel corresponds to the condition of the minimum distance between the third flange 20a and the separation partition protruding from the cylindrical body 12), while the sub-flange 16 increases by an amount “c” relative to its lower end travel (in the illustrated example, this lower end travel corresponds to the support state of the annular edge of the sub-actuator 28 on the protrusion integral with the main flange 14).

[0033] According to another aspect of the invention, a vehicle suspension includes a device 9 for adjusting the damper clearance in the vehicle suspension as described in any of the above embodiments, a shock absorber cylinder (not shown) adapted to connect to the unsprung mass of the vehicle and suppress the oscillating motion of the vehicle's suspended mass, and a shock absorber rod 18 disposed along a main axis x and having a lower end integral with a shock absorber piston sliding within the shock absorber cylinder and an upper end integral with a main flange 14 of a head element 10. The suspension also includes a main spring that acts parallel to the shock absorber cylinder, with one end engaging the secondary flange 16 and the opposite end engaging another radial flange integral with the shock absorber cylinder.

[0034] According to another aspect of the invention, a method for adjusting the damper clearance and / or spring preload of a vehicle suspension includes the steps of: preparing a vehicle suspension according to the above and introducing pressurized fluid into the main chamber 13a, thereby generating a reaction force on the walls of the main actuator 20 and the cylindrical body 12, which may cause the main actuator 20 and the damper 24 to slide relative to the cylindrical body 12 along the main axis x, and / or cause a change in the preload of the main spring of the suspension.

[0035] According to one embodiment, the above steps cause a change in the distance between the third flange 20a and the main flange 14 by relative sliding between the third flange 20a and the cylindrical body 12 of the head element 10 (e.g., causing the main actuator 20 to drop to a predetermined distance from the shock absorber cylinder 24, which may be greater than or equal to zero).

[0036] According to one embodiment, the step of placing the buffer 24 into contact with the shock absorber cylinder is performed before or after the step of introducing pressurized fluid into the main chamber 13a. Therefore, the preload of the main spring can be adjusted by regulating the fluid pressure in the main chamber 13a (by applying an upward thrust to the head element 10, possibly until it slides relative to the main actuator 20).

[0037] Various aspects and embodiments of the adjusting device according to the invention, the suspension including the device, and the method for adjusting the suspension have been described. It should be understood that each embodiment can be combined with any other embodiment. Furthermore, the invention is not limited to the described embodiments but can be varied within the scope defined by the appended claims.

Claims

1. A device (9) for adjusting the damper clearance and / or spring preload in a vehicle suspension, the device comprising: - Head element (10), which includes a cylindrical body (12) and a main flange (14), the cylindrical body (12) including an inner cavity and extending along a main axis (x), the main flange (14) being integral with the cylindrical body (12) and adapted to be connected to the suspension mass of the vehicle, the main flange (14) being configured to be fixed to the upper end of a shock absorber rod (18), the shock absorber rod being integral at the lower end with a shock absorber piston that can slide within a shock absorber cylinder; - A secondary flange (16), which is located radially outside the cylindrical body (12) and is adapted to form the upper support of the main spring of the vehicle suspension; - A main actuator (20) is coaxial with and slidably received inside the cylindrical body (12), the main actuator (20) including a third flange (20a) having a surface extending in a plane perpendicular to the main axis (x) and facing the main flange (14), the surface of the third flange (20a) defining a lower portion of a main chamber (13a) forming a volume portion of the inner cavity of the cylindrical body (12), the main chamber (13a) being fluidly in communication with the outside of the cylindrical body (12), the third flange (20a) being configured to slide along the main axis (x) inside the cylindrical body (12) in response to the pressure of the fluid entering the main chamber (13a); and - A buffer (24), adapted to be formed by abutting the shock absorber cylinder of the vehicle suspension as a limiting stop for oscillations of the vehicle's suspension mass when the vehicle's suspension mass approaches the vehicle's unsprung mass, the buffer (24) being received inside the main actuator (20) and being integrally movable with the main actuator (20) along the main axis (x) relative to the cylindrical body (12); The main actuator (20) and the buffer (24) assembly are configured to be axially passed through and slide relative to the damper rod (18), and The cylindrical body (12) has an inner cavity including a secondary chamber (13b) axially stacked on top of the main chamber (13a) and separated from the main chamber (13a) by a separation partition extending radially from the cylindrical body (12) toward the main axis (x). The main actuator includes a cylindrical portion (20b) integral with a third flange (20a) and slidably passing through the separation partition, thereby fluidly separating the main chamber (13a) from the secondary chamber (13b). The secondary chamber (13b) is fluidly connected to the outside of the cylindrical body (12), and the main chamber (13a) is defined below by the third flange (20a) and above by the partition. The cylindrical body (12) includes an annular shoulder that extends radially toward the main axis (x) and is axially positioned below the main actuator (20) such that the buffer (24) can slide through the annular shoulder. The device includes a secondary spring (26) having one end engaging the annular shoulder and the opposite end engaging a third flange (20a). The secondary spring (26) is configured to push the third flange (20a) toward the separation partition.

2. The apparatus according to claim 1, wherein, The main flange (14) has an annular groove located radially outside the cylindrical body (12) and fluidly communicating with the outside of the head element (10), and wherein a secondary flange (16) is slidable relative to the cylindrical body (12) of the head element (10) along the main axis (x), the secondary flange being integrally movable with a secondary actuator (28) having an upper edge slidably received in the annular groove and configured to slide relative to the main flange (14) along the main axis (x) in response to the pressure of fluid entering the annular groove, the annular groove being fluidly separated from the main chamber (13a).

3. A vehicle suspension comprising: - A device (9) for adjusting the damper clearance in a vehicle suspension according to any one of the preceding claims; - A shock absorber cylinder adapted to be connected to the unsprung mass of the vehicle and to suppress the oscillating motion of the suspended mass of the vehicle; - A shock absorber rod (18), which is arranged along the main axis (x) and has a lower end integral with a shock absorber piston that can slide within the shock absorber cylinder and an upper end integral with the main flange (14) of the head element (10); and - A main spring having one end engaging the secondary flange (16) and the opposite end engaging another radial flange integral with the shock absorber cylinder.

4. A method for adjusting the damper clearance and / or spring preload of a vehicle suspension, the method comprising the following steps: a) Provide a vehicle suspension as claimed in claim 3; and b) Introducing pressurized fluid into the main chamber (13a) to generate reaction forces on the walls of the main actuator (20) and the cylindrical body (12), the reaction forces being capable of causing a predetermined sliding of the main actuator (20) and the buffer (24) relative to the cylindrical body (12) along the main axis (x), and / or causing a predetermined change in the preload of the main spring of the suspension.

5. The method according to claim 4, wherein, Step b) causes a change in the distance between the third flange (20a) and the main flange (14) by relative sliding between the third flange (20a) and the cylindrical body (12) of the head element (10).

6. The method according to claim 4 or 5, wherein, The step before or after step b) is to place the buffer (24) into contact with the shock absorber cylinder.

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