Shock absorber and spring assembly for vehicle suspension and method for adjusting the vertical position of the spring

Abstract

A shock absorber and spring assembly for a vehicle suspension comprises a shock absorber (10) provided with a spring plate (18) and a spring (12), the bottom of the spring resting on the spring plate, the shock absorber assembly also comprising an electromechanical adjustment device for varying the vertical position of the lower end of the spring (12) in a continuous and controllable manner, the adjustment device comprising a screw and nut motion conversion mechanism (24, 26) and a mechanism for blocking rotation of the screw (24), the blocking mechanism comprising a main disc (50) connected to the screw (24) for co-rotation therewith and an auxiliary disc (52) fixed non-rotatably relative to the screw (24), the discs respectively having mutually engaging profiles (50', 52') such that rotation of the screw (24) is prevented when the profiles engage with each other.

Description

Technical Field

[0001] The present invention generally relates to a shock absorber and spring assembly for a vehicle suspension, the assembly being provided with an adjustment mechanism for adjusting the vertical position of the spring to control vehicle ground clearance. Background Art

[0002] In a vehicle suspension comprising a shock absorber and a spring assembly, wherein the shock absorber is connected at its lower end to the wheel carrier or suspension arm and at its upper end to the vehicle body, and wherein a spring is arranged around the shock absorber and rests at its lower end against a spring plate and at its upper end against the vehicle body, it is known to use an adjustment device arranged between the cylinder of the shock absorber and the spring plate to vary the vertical position of the spring, thereby allowing adjustment of the vehicle body to ground clearance.

[0003] The regulating devices used for this purpose can be of different types, such as hydraulic, pneumatic, hydro-pneumatic and electromechanical. Among them, electromechanical regulating devices are gaining more and more attention and interest due to their high reliability, relatively low cost and compactness compared to other types of regulating devices.

[0004] More specifically, a shock absorber and spring assembly for a vehicle suspension using an electromechanical adjustment device includes a motor adapted to generate rotational motion and a screw and nut motion conversion mechanism adapted to convert the rotational motion generated by the motor into translational motion of a spring plate.

[0005] The motion conversion mechanism in turn comprises a screw adapted to be rotated about its axis by the electric motor, and a nut meshing with the screw and connected to the spring plate for translation therewith, so that by activating the electric motor, the rotational motion transmitted by the electric motor to the screw is converted into a translational motion of the nut and thus into a translational motion of the spring plate.

[0006] A solution of the above-mentioned type is known, for example, from PCT / IB2018 / 059025, which discloses a spring and shock absorber assembly for a vehicle suspension, which is designed to prevent a spring plate from rotating relative to the shock absorber without the use of suitable anti-rotation devices.

[0007] In this known solution, the screw and nut of the motion conversion mechanism are arranged eccentrically with respect to the axis of the shock absorber, and the kinematic mechanism formed by the worm and nut is designed with low efficiency (ie high friction level), making it an irreversible mechanism.

[0008] In doing so, the screw is permitted to rotate relative to the nut only when the motor rotates the screw, while preventing rotation caused solely by the downward force transmitted to the spring support plate by the spring.

[0009] Ultimately, this solution ensures that the mechanism cannot be moved from a certain acquired position solely due to the weight of the vehicle and other elastic forces caused by deformation of the spring when the vehicle is in use.

[0010] However, this solution has some disadvantages caused by the high friction of the screw / nut kinematics, such as high electrical energy consumption of the electric motor (because a lot of energy is needed to counteract the friction forces), long activation times (because a considerable part of the power input to the electric motor is used to counteract the friction and is therefore not used to move the spring support plate vertically), and high wear of the screw and nut threads (the tangential force component on the threads is higher, resulting in a shorter service life of the device). Summary of the Invention

[0011] The object of the present invention is to overcome the above-mentioned problems.

[0012] To achieve this object, the spring and shock absorber assembly for a vehicle suspension according to the invention comprises an additional mechanism for blocking the relative rotation between the screw and the nut, which is necessary in order to be able to maintain the desired position of the spring support plate under the action of the force transmitted by the spring support plate to the spring, without having to continue to supply power to the electric motor, even when using a highly efficient (i.e. reversible) screw / nut kinematic mechanism.

[0013] The electromechanical adjustment device according to the present invention comprises: an electric motor adapted to generate a rotational motion; a motion conversion mechanism extending along an axis parallel to, but not coinciding with, the axis of the shock absorber, and comprising a nut meshing with a screw rotated by the electric motor, the nut being connected to a spring support plate for translation therewith; and a mechanism for blocking the rotation of the screw relative to the nut, comprising a clutch, the opening of which is controlled by an electromagnet energized with an electric current. The screw / nut kinematic mechanism is preferably highly efficient, for example by using a ball screw.

[0014] The mechanism for blocking the rotation of the screw relative to the nut comprises an electrically actuated clutch comprising two discs having profiles that mesh with each other, a lower disc that rotates with the screw and an upper disc that is non-rotatably fixed but can translate axially along the axis of the screw.

[0015] According to one embodiment, the two discs have a series of teeth on the two faces facing each other that can engage with each other. These teeth can have profiles that form different angles on their right and left sides relative to the plane containing the screw axis, that is, depending on the flank that engages.

[0016] In particular, when the screw tends to rotate in a first direction, the two engaged teeth contact each other on a first side, advantageously characterized in that the profile of the teeth is at a small angle relative to a plane containing the axis of the screw, and thus prevents the teeth of the upper disc from sliding relative to the teeth of the lower disc, thereby also preventing the screw from rotating relative to the nut and preventing the upper disc from translating upwards.

[0017] On the contrary, when the screw tends to rotate in a second direction opposite to the first, the two engaged teeth come into contact with each other on a second side, advantageously characterized in that the profile of the teeth is at a large angle relative to the plane containing the axis of the screw, and thus makes it possible to slide the teeth of the upper disc relative to the teeth of the lower disc, thereby making it possible to rotate the screw relative to the nut and thus translate the upper disc upwards.

[0018] The first direction of rotation corresponds to the direction of rotation of the screw during the downward movement of the spring support plate. This downward movement is triggered by the downward force transmitted to the spring support plate by the spring.

[0019] In contrast, the second direction of rotation corresponds to the direction of rotation of the screw during the upward movement of the spring-supported plate. This upward movement is only possible when the motor activates the screw.

[0020] The upper disc is preferably urged downward by an elastic return mechanism, ensuring that its profile engages with that of the lower disc. The upper disc can also be moved upward by applying an electric current to an electromagnet positioned above it. By energizing the electromagnet, the upper disc is attracted and translated upward until its teeth no longer engage with those of the lower disc. In this latter case, the mechanism is unlocked, either by the torque transmitted by the electric motor, or by the downward force transmitted by the spring through the spring-supported plate, or by a combination of both, and the screw can rotate freely in one direction of rotation or the other.

[0021] According to one aspect of the invention, the above and other objects and advantages are achieved by a spring and shock absorber assembly for a vehicle suspension and a method for moving a spring plate of a shock absorber having the characteristics defined in the accompanying claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The functions and structural features of some preferred embodiments of the spring and shock absorber assembly for vehicle suspension according to the present invention will now be described. With reference to the accompanying drawings, in which:

[0023] Figure 1 is a schematic perspective view of a spring and shock absorber assembly for a vehicle suspension according to one embodiment of the present invention;

[0024] Figure 2 yes Figure 1A schematic axial cross-section of a spring and shock absorber assembly for a vehicle suspension;

[0025] Figure 3 yes Figure 2 A schematic axial cross-section of a detail, particularly the mechanism for preventing the screw from rotating;

[0026] FIG4A and FIG4B are Figure 3 Two schematic perspective views of a mechanical clutch associated with a mechanism for blocking rotation, in accordance with one embodiment of the present invention, in a state in which the respective profiles are engaged and in a state in which the respective profiles are disengaged; and

[0027] Figure 5A and Figure 5B 4A and 4B are schematic side views of the mechanical clutch shown in respective states with profiles engaged on opposite sides of the teeth, according to one embodiment of the present invention. DETAILED DESCRIPTION

[0028] Before describing in detail various embodiments of the present invention, it should be clarified that the present invention is not limited to the design details and configurations of components shown in the following description of the present invention or in the accompanying drawings. The present invention is capable of other embodiments and can be implemented or constructed in practice in various ways. It should also be understood that the phraseology and terminology are for descriptive purposes only and should not be interpreted as limiting.

[0029] refer to Figures 1 to 3 The shock absorber and spring assembly for a vehicle suspension according to the present invention includes a shock absorber 10 and a spring plate 18. The shock absorber 10 has a cylinder 14 and a rod 16 extending along a first axis z. The spring plate 18 is arranged around the cylinder 14 of the shock absorber 10 and can slide relative to the cylinder along the first axis z.

[0030] The following components are also present: a spring 12, the bottom of which rests on a spring plate 18; and an electromechanical adjustment device arranged between the cylinder 14 of the shock absorber 10 and the spring plate 18, for varying the vertical position of the lower end of the spring 12 in a continuous and controllable manner, thus allowing the clearance between the vehicle and the ground to be adjusted.

[0031] The adjusting device includes an electric motor 22 suitable for generating a rotational motion, and a screw and nut motion conversion mechanism 24, 26 suitable for converting the rotational motion generated by the electric motor 22 into a translational motion of the spring plate 18, wherein the motion conversion mechanism includes a single screw 24 extending along a second axis z' parallel to the first axis z and suitable for being rotated about the second axis z' by the electric motor 22, and a single nut 26 meshing with the screw 24 and connected to the spring plate 18 for common translation therewith, so that after the electric motor 22 is started, the rotational motion transmitted to the screw 24 by the electric motor 22 is converted into a translational motion of the nut 26 along the second axis z', and thus converted into a translational motion of the spring plate 18 relative to the cylinder 14 of the shock absorber 10 along the first axis z.

[0032] The second axis z′ is spaced apart from the first axis z, so that the unit formed by the screw 24 and the nut 26 is arranged eccentrically relative to the cylinder 14 and the spring plate 18 of the shock absorber 10 .

[0033] The motion conversion mechanism also includes a mechanism for blocking the rotation of the screw 24, which includes a main disc 50 connected to the screw 24 so as to rotate therewith, and an auxiliary disc 52 fixed non-rotatably relative to the screw 24, the main disc and the auxiliary disc respectively having mutually meshing profiles 50', 52'.

[0034] The auxiliary disc 52 is movable along the axis z′ from a blocking position (in the example shown, a lower position), in which the profiles 50 ′, 52 ′ of the two main discs 50 and the auxiliary disc 52 engage with each other and prevent the screw 24 from rotating, and an unlocking position (in the example shown, an upper position), in which the profiles 50 ′, 52 ′ of the two main discs 50 and the auxiliary disc 52 prevent mutual engagement and allow the screw 24 to rotate.

[0035] According to one embodiment, the shock absorber and spring assembly for a vehicle suspension further comprises a first support arm 28 carrying the electric motor 22 and the screw 24 and rigidly connected to the cylinder 14 of the shock absorber 10, a second support arm 34 carrying the nut 26 and rigidly connected to the spring plate 18, and a guide sleeve 38 rigidly connected at one end to the second support arm 34 and at the other end to the spring plate 18 and arranged around the cylinder 14 of the shock absorber 10 so as to be able to slide along the first axis z.

[0036] The mechanism for blocking the rotation of the screw 24 can advantageously be housed in a seat provided in the first support arm 28 .

[0037] According to a preferred embodiment, the mechanism for blocking the rotation of the screw 24 comprises an electromagnet 58 and an elastic device 56, wherein the electromagnet 58 is adapted to attract the auxiliary disc 52 toward the unlocking position by means of electrical excitation, and the elastic device 56 is adapted to push the auxiliary disc 52 toward the blocking position.

[0038] According to one embodiment, the intermeshing profiles 50 ′, 52 ′ comprise respective teeth having a first side and a second side, the first side having a first angle relative to a plane containing the z′ axis, which comes into engagement when the screw 24 rotates or tends to rotate in a first rotational direction (advantageously, when the spring plate 18 tends to move downward along the first z axis), and the second side having a second angle relative to the plane containing the z′ axis, which is greater than the first angle, and comes into engagement when the screw 24 rotates or tends to rotate in the opposite rotational direction (advantageously, when the spring plate 18 tends to move upward along the first z axis). For example, the first and second rotational directions may be, respectively, a counterclockwise and a clockwise direction of rotation of the disc, as shown in FIGS. 4A and 4B .

[0039] The first angle is preferably between 5° and 15°, thereby preventing the profile of the auxiliary disk 52 from sliding relative to the profile of the main disk 50, and the second angle is between 65° and 75°, thereby enabling the profile of the auxiliary disk 52 to slide relative to the profile of the main disk 50. This configuration allows the auxiliary disk 52 to have an initial path along the second axis z' by virtue of the mutual sliding of the profiles at the second angle. In this way, for example, the auxiliary disk 52 can be moved closer to a possible electromagnet 58, thereby reducing the excitation energy required to attract the auxiliary disk 52 towards a position of disengagement from the main disk 50.

[0040] Preferably, when the screw 24 rotates or tends to rotate, the first side comes into engagement, causing the nut 26 to move downward along the axis z', and when the screw 24 rotates or tends to rotate, the second side comes into engagement, causing the nut 26 to move upward along the axis z'.

[0041] According to a preferred embodiment, the screw 24 is a ball screw. Thus, an efficient kinematic mechanism is obtained, friction is reduced and the energy efficiency of the assembly is increased.

[0042] The adjustment device may also advantageously comprise a reduction gear mechanism, which is arranged between the electric motor 22 and the screw 24 .

[0043] According to one aspect of the present invention, a method for moving a spring plate 18 of a shock absorber 10 includes the steps of providing a shock absorber and spring assembly for a vehicle suspension according to one or more of the above-described embodiments.

[0044] The mechanism can be activated downwards by means of the following steps. Starting from a state in which the mechanism for blocking the rotation of the screw 24 is in a blocking position in which the profiles 50 ′, 52 ′ of the two main discs 50 and the auxiliary disc 52 engage with one another (advantageously on a first side, which does not allow relative sliding between the engaged teeth or on their first angled sides), the motor 22 is activated in the second direction of rotation until the teeth come into contact with one another on the second side (on their second angled side), which in turn allows relative sliding between the two engaged profiles.

[0045] The motor 22 is then rotated further in the second rotational direction, causing the main disc 50 to rotate further relative to the auxiliary disc 52 by means of relative sliding of the engaged teeth, thereby triggering a translation of the auxiliary disc 52 away from the main disc 50 along the axis z′.

[0046] The electromagnet 58 is then energized in order to further attract the auxiliary disc 52 along the axis z′ until the profiles of the main and auxiliary discs 50 , 52 disengage from each other and the mechanism for blocking the rotation of the screw 24 is unlocked and the rotation of the motor 22 in the second rotational direction stops, so that, for example, under the action of the downward force transmitted by the spring 12 via the spring plate 18 , the screw 24 rotates in the first rotational direction, and the spring plate 18 moves downward along the first axis z, thereby keeping the electromagnet 58 energized.

[0047] Once the spring plate 18 has reached the desired position along the axis z, the electromagnet 58 is de-energized and the profiles of the two primary and secondary discs 50, 52 re-engage under the action of the downward force transmitted by the spring 12 (advantageously due to the action of the elastic means 56) and come into contact with each other on their first sides, thereby blocking the rotation of the device. From this moment on, the vertical position of the spring plate 18 remains unchanged.

[0048] If the electromagnet 58 is preferably configured to operate according to the reluctance principle, the position of the auxiliary disc 52 relative to the main disc 50 can be estimated by means of measuring the inductance of the magnetic circuit.

[0049] Similarly, the mechanism can be activated upwards using the following steps. Starting from a state where the blocking mechanism is engaged and the teeth of the two discs 50, 52 are therefore in contact on the first side, preventing relative sliding between the engaged teeth, the motor 22 is activated in the second rotational direction until the teeth contact on the opposite (second) side, allowing relative sliding between the two engaged profiles. The motor 22 continues to rotate in the second rotational direction, and due to the relative sliding of the engaged teeth, the primary disc 50 can also rotate relative to the secondary disc 52, and the secondary disc 52 begins to translate upwards. At this point, the blocking mechanism's electromagnet 58 is energized, exerting further force on the secondary disc 52, which also translates it upwards until its teeth no longer engage with those of the primary disc 50, and the mechanism unlocks. From this state, the motor 22 continues to be controlled in the second rotational direction, causing the spring plate 18 to rise. The electromagnet 58 remains energized throughout the entire ascending phase. Once the desired position is reached, the electric motor 22 is de-energized, the electromagnet 58 is de-energized, and the profiles of the two primary and secondary discs 50, 52 re-engage under the action of the downward force transmitted by the spring 12 (advantageously due to the action of the elastic means 56) and come into contact on their first sides, thereby blocking the rotation of the device. From this moment on, the vertical position of the spring plate 18 remains unchanged.

[0050] In the present description and claims, terms and expressions indicating position and direction, such as "axial" or "transverse", refer to the first axis z and the second axis z'.

[0051] Various aspects and embodiments of a spring and shock absorber assembly for a vehicle suspension and a method for moving a spring plate of a shock absorber according to the present invention have been described. It should be understood that each embodiment can be combined with any other embodiment. Furthermore, the present invention is not limited to the described embodiments but may be varied within the scope of the appended claims.

Claims

1. A shock absorber and spring assembly for a vehicle suspension, comprising: - a shock absorber (10) having a cylinder (14) and a rod (16) extending along a first axis (z), - a spring plate (18) arranged around the cylinder (14) of the shock absorber (10) and slidable relative to the cylinder along said first axis (z), - a spring (12), the bottom of which rests on a spring plate (18), and - an electromechanical adjustment device, arranged between the cylinder (14) of the shock absorber (10) and the spring plate (18), for varying the vertical position of the lower end of the spring (12) in a continuous and controlled manner, thereby allowing the vehicle's ground clearance to be adjusted, The adjusting device includes a motor (22) adapted to generate a rotational motion and a screw and nut motion conversion mechanism (24, 26) adapted to convert the rotational motion generated by the motor (22) into a translational motion of the spring plate (18). wherein the motion conversion mechanism comprises a single screw (24) extending along a second axis (z') parallel to the first axis (z) and adapted to be rotated about the second axis (z') by the motor (22), and a single nut (26) meshing with the screw (24) and connected to the spring plate (18) for translation therewith, so that after activation of the motor (22), the rotational motion transmitted by the motor (22) to the screw (24) is converted into a translational motion of the nut (26) along the second axis (z'), and thereby into a translational motion of the spring plate (18) relative to the cylinder (14) of the shock absorber (10) along the first axis (z), the second axis (z') being spaced apart from the first axis (z), so that the unit formed by the screw (24) and the nut (26) is arranged eccentrically relative to the cylinder (14) of the shock absorber (10) and the spring plate (18); The motion conversion mechanism also includes a mechanism for blocking the rotation of the screw (24), the blocking mechanism including a main disc (50) and an auxiliary disc (52), the main disc (50) being connected to the screw (24) so ​​as to rotate therewith, the auxiliary disc (52) being fixed non-rotatably relative to the screw (24), the main disc (50) and the auxiliary disc (52) respectively having mutually meshing profiles (50', 52'), the auxiliary disc (52) being translatable along the axis (z') from a blocking position and an unlocking position, in which the profiles (50', 52') of the two main discs (50) and the auxiliary disc (52) engage with each other and prevent the rotation of the screw (24), and in the unlocking position, the profiles (50', 52') of the two main discs (50) and the auxiliary disc (52) prevent mutual engagement and allow the rotation of the screw (24).

2. The shock absorber and spring assembly according to claim 1 , further comprising a first support arm (28), a second support arm (34), and a guide sleeve (38), wherein the first support arm (28) carries the electric motor (22) and the screw (24) and is rigidly connected to the cylinder (14) of the shock absorber (10), the second support arm (34) carries the nut (26) and is rigidly connected to the spring plate (18), and the guide sleeve (38) is rigidly connected at one end to the second support arm (34) and at the other end to the spring plate (18) and is arranged around the cylinder (14) of the shock absorber (10) so as to be able to slide along the first axis (z).

3. The shock absorber and spring assembly of claim 2, wherein: The mechanism for blocking the rotation of the screw (24) is housed in a seat provided in the first support arm (28).

4. A shock absorber and spring assembly according to any one of the preceding claims, wherein: The mechanism for blocking the rotation of the screw (24) comprises an electromagnet (58) adapted to attract the auxiliary disc (52) towards the unlocked position by means of electrical excitation and an elastic device (56) adapted to push the auxiliary disc (52) towards the unlocked position.

5. A shock absorber and spring assembly according to any one of the preceding claims, wherein: The intermeshing profiles (50', 52') include respective teeth having a first side and a second side, the first side having a first angle relative to a plane containing the axis (z') and coming into engagement when the screw (24) rotates or tends to rotate in a first rotational direction, and the second side having a second angle relative to the plane containing the axis (z') that is greater than the first angle and coming into engagement when the screw (24) rotates or tends to rotate in an opposite rotational direction.

6. The shock absorber and spring assembly of claim 5, wherein: The first angle is between 5° and 15°, thereby preventing the profile of the auxiliary disc (52) from sliding relative to the profile of the main disc (50), and the second angle is between 65° and 75°, allowing the profile of the auxiliary disc (52) to slide relative to the profile of the main disc (50).

7. A shock absorber and spring assembly according to claim 5 or 6, wherein: The first side comes into engagement when the screw (24) rotates or tends to rotate, thereby causing a downward movement of the nut (26) along the axis (z'), and the second side comes into engagement when the screw (24) rotates or tends to rotate, thereby causing an upward movement of the nut (26) along the axis (z').

8. A shock absorber and spring assembly according to any one of the preceding claims, wherein: The screw (24) is a ball screw.

9. A shock absorber and spring assembly according to any one of the preceding claims, wherein: The adjusting device further comprises a reduction gear mechanism, which is arranged between the motor (22) and the screw (24).

10. A method for moving a spring plate (18) of a shock absorber (10), comprising the following steps: a) providing a shock absorber and spring assembly for a vehicle suspension according to any one of claims 4 to 9; b) starting from a state in which the mechanism for blocking the rotation of the screw (24) is in a blocking position in which the profiles (50', 52') of the two main discs (50) and the auxiliary disc (52) engage with each other on their first angular sides, activating the electric motor (22) in a second direction of rotation until the teeth come into contact with each other on their second angular sides, which allows relative sliding of the two profiles (50', 52'); c) continuing to rotate the motor (22) in the second rotational direction so that the primary disc (50) further rotates relative to the secondary disc (52) by means of relative sliding of the engaged teeth, thereby triggering translation of the secondary disc (52) along the axis (z') away from the primary disc (50); d) energizing the electromagnet (58) in order to further attract the auxiliary disc (52) along the axis (z') until the profiles of the main and auxiliary discs (50, 52) and the mechanism for blocking the rotation of the screw (24) are unlocked; e) to obtain downward movement of the spring plate (18): stopping the rotation of the motor (22) in the second rotational direction so that the screw (24) rotates in the first rotational direction and the spring plate (18) moves downward along the first axis (z), keeping the electromagnet (58) energized; or f) to obtain an upward movement of the spring plate (18): continuing to rotate the motor (22) in the second rotational direction, so that the screw (24) continues to rotate in the second rotational direction and the spring plate (18) moves upward along the first axis (z), keeping the electromagnet (58) energized; and g) once the spring plate (18) has reached the desired position, and only in the case of an upward movement, the rotation of the motor (22) in the second direction of rotation is stopped, the electromagnet (58) is de-energized, and the profiles of the two primary and secondary discs (50, 52) are re-engaged by the action of the downward force transmitted by the spring (12), with the same profiles in contact on their first sides, so that the rotation of the device is blocked.

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