WO2018092111A1 - Vehicle wheel suspension provided with active adjustment system for adjusting in a controlled manner the overall stiffness of the suspension - Google Patents

Vehicle wheel suspension provided with active adjustment system for adjusting in a controlled manner the overall stiffness of the suspension Download PDF

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Publication number
WO2018092111A1
WO2018092111A1 PCT/IB2017/057287 IB2017057287W WO2018092111A1 WO 2018092111 A1 WO2018092111 A1 WO 2018092111A1 IB 2017057287 W IB2017057287 W IB 2017057287W WO 2018092111 A1 WO2018092111 A1 WO 2018092111A1
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WO
WIPO (PCT)
Prior art keywords
damper
piston
extension
chamber
reaction element
Prior art date
Application number
PCT/IB2017/057287
Other languages
French (fr)
Inventor
Massimo Seminara
Matteo VERGANI
Original Assignee
Sistemi Sospensioni S.P.A.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Sistemi Sospensioni S.P.A. filed Critical Sistemi Sospensioni S.P.A.
Publication of WO2018092111A1 publication Critical patent/WO2018092111A1/en

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60G—VEHICLE SUSPENSION ARRANGEMENTS
    • B60G15/00—Resilient suspensions characterised by arrangement, location or type of combined spring and vibration damper, e.g. telescopic type
    • B60G15/02—Resilient suspensions characterised by arrangement, location or type of combined spring and vibration damper, e.g. telescopic type having mechanical spring
    • B60G15/06—Resilient suspensions characterised by arrangement, location or type of combined spring and vibration damper, e.g. telescopic type having mechanical spring and fluid damper
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60G—VEHICLE SUSPENSION ARRANGEMENTS
    • B60G15/00—Resilient suspensions characterised by arrangement, location or type of combined spring and vibration damper, e.g. telescopic type
    • B60G15/02—Resilient suspensions characterised by arrangement, location or type of combined spring and vibration damper, e.g. telescopic type having mechanical spring
    • B60G15/06—Resilient suspensions characterised by arrangement, location or type of combined spring and vibration damper, e.g. telescopic type having mechanical spring and fluid damper
    • B60G15/061—Resilient suspensions characterised by arrangement, location or type of combined spring and vibration damper, e.g. telescopic type having mechanical spring and fluid damper with a coil spring being mounted inside the damper
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60G—VEHICLE SUSPENSION ARRANGEMENTS
    • B60G17/00—Resilient suspensions having means for adjusting the spring or vibration-damper characteristics, for regulating the distance between a supporting surface and a sprung part of vehicle or for locking suspension during use to meet varying vehicular or surface conditions, e.g. due to speed or load
    • B60G17/06—Characteristics of dampers, e.g. mechanical dampers
    • B60G17/08—Characteristics of fluid dampers
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
    • F16F9/00—Springs, vibration-dampers, shock-absorbers, or similarly-constructed movement-dampers using a fluid or the equivalent as damping medium
    • F16F9/32—Details
    • F16F9/48—Arrangements for providing different damping effects at different parts of the stroke
    • F16F9/49—Stops limiting fluid passage, e.g. hydraulic stops or elastomeric elements inside the cylinder which contribute to changes in fluid damping
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
    • F16F9/00—Springs, vibration-dampers, shock-absorbers, or similarly-constructed movement-dampers using a fluid or the equivalent as damping medium
    • F16F9/32—Details
    • F16F9/58—Stroke limiting stops, e.g. arranged on the piston rod outside the cylinder
    • F16F9/585—Stroke limiting stops, e.g. arranged on the piston rod outside the cylinder within the cylinder, in contact with working fluid
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60G—VEHICLE SUSPENSION ARRANGEMENTS
    • B60G2204/00—Indexing codes related to suspensions per se or to auxiliary parts
    • B60G2204/40—Auxiliary suspension parts; Adjustment of suspensions
    • B60G2204/45—Stops limiting travel
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60G—VEHICLE SUSPENSION ARRANGEMENTS
    • B60G2500/00—Indexing codes relating to the regulated action or device
    • B60G2500/10—Damping action or damper
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60G—VEHICLE SUSPENSION ARRANGEMENTS
    • B60G2500/00—Indexing codes relating to the regulated action or device
    • B60G2500/20—Spring action or springs

Definitions

  • Vehicle wheel suspension provided with active adjustment system for adjustinfi in a controlled manner the overall stiffness of the suspension
  • the present invention relates to a vehicle wheel suspension, of the type comprising a spring, such as for example a helical spring or a similar elastic element, interposed between the wheel and the body of the vehicle, and a damper, also interposed between the wheel and the body of the vehicle, in parallel with the spring.
  • a spring such as for example a helical spring or a similar elastic element
  • the designer shall find each time the best compromise, depending on the specific application, between two contrasting requirements, that is road-holding (and thus safety) and comfort.
  • the two parameters involved in the definition of the characteristics of the suspension, and thus in the determination of the optimal compromise between road-holding and comfort are the stiffness of the spring and the damping of the damper.
  • the design choice is general- ly determined by the kind of use for which the vehicle has been designed. In sport vehicles, road-holding is naturally preferred, to the detriment of comfort, while for example in city- cars comfort is preferred, to the detriment of road-holding.
  • suspension active adjustment systems allowing to actively adjust, in real time, the characteristics of the suspensions depending on the vehicle driving conditions.
  • Suspension active adjustment systems which allow for example to change the force-speed characteristic of the damper to change the force between the sprung mass and the unsprung mass of the vehicle during the transient phase of the dynamics of the vehicle.
  • Suspension active adjustment systems are also known, which allow to change in a controlled manner the stiffness of the spring to change the force exerted between the sprung mass and the unsprung mass of the vehicle, not only during the transient phase of the dynamics of the vehicle, but also at steady state, for example during cornering. As they are able to vary the overall stiffness of the suspension, these adjustment systems further allow, in steady conditions, to change the attitude of the vehicle both to accomplish several comfort or road-holding targets and to adapt the attitude of the vehicle to any load variations.
  • the present inventions relates to this second category of suspension active adjustment systems and aims at providing a vehicle wheel suspension that is provided with an active adjustment system, improved with respect to the prior art, for continuously adjusting, in a controlled manner, the overall stiffness of the suspension, that is the ratio of the force exerted between the sprung mass and the unsprung mass of the vehicle to the relative position of the sprung mass with respect to the unsprung mass of the vehicle, at that wheel.
  • a further object of the present invention is to provide a vehicle wheel suspension provided with an active stiffness adjustment system that is structurally simple and not expensive.
  • the invention is based on the idea of providing a suspension of the type mentioned above comprising, in addition to the main spring and the damper:
  • reaction element which is accommodated in the extension chamber of the damper and is arranged to oppose the extension movement of the damper starting from a given travel value of the damper in the extension phase
  • adjustment means associated to the reaction element to adjust the axial position of said element inside the extension chamber of the damper and thus adjust the travel value, in the extension phase, starting from which the reaction element intervenes to oppose the extension movement of the damper,
  • the adjustment means comprise an adjustment piston that is mounted axially slida- ble in the extension chamber of the damper and is drivingly connected for axial sliding movement with the reaction element, and a hydraulic control circuit which communicates with the extension chamber of the damper and is arranged to control the axial position of the adjustment piston in the extension chamber of the damper.
  • a suspension according to the invention allows to adjust, in a controlled manner, the point of intervention of the reaction element in the extension phase of the damper and thus to adjust, in a controlled manner, the overall stiffness of the suspension.
  • it is thus pos- sible to adjust the overall stiffness of every single corner of the vehicle in order to adjust the overall roll stiffness of each of the two axles of the vehicle or to adjust the attitude of the vehicle.
  • the reaction element is formed by an elastic element, prefer- ably a mechanical spring.
  • the reaction element is formed by a cup-shaped hollow body arranged to work as a hydraulic bump stop cooperating with an auxiliary piston drivingly connected to the main piston of the damper.
  • the adjustment piston comprises an annular piston body, that is mounted axially slidable on the rod of the damper and seals tightly with the cylinder of the damper so as to split the extension chamber of the damper into an upper compartment, facing towards the opposite side with respect to the main piston of the damper, and a lower compartment, fac- ing towards the main piston of the damper, the reaction element being placed in said lower compartment.
  • the adjustment piston further comprises a tubular portion rigidly connected to the annular piston body, said tubular portion being mounted axially slidable on the rod of the damper and extending through an upper cap of the damper.
  • the damper has a three-tube architecture comprising:
  • first intermediate tube radially interposed between the inner tube and the outer tube, the first intermediate tube enclosing, together with the inner tube, an intermediate compartment that is in fluid communication with the hydraulic control circuit, on one side, and with the upper compartment defined by the adjustment piston inside the extension chamber, on the other side.
  • the damper further comprises:
  • a second intermediate tube radially interposed between the inner tube and the outer tube, underneath the first intermediate tube, so as to enclose, together with the inner tube, a by-pass chamber that is in fluid communication with the lower compartment of the extension chamber through one or more communications holes provided in the inner tube, and a control valve connected to the second intermediate tube and arranged to control the flow of the working fluid of the damper between the lower compartment of the extension chamber and the by-pass chamber, so as to allow to adjust the damping of the damper.
  • Figure 1 is a schematic representation of a vehicle wheel suspension architecture according to an embodiment of the present invention
  • Figure 2 is a schematic representation of a vehicle wheel suspension architecture according to a further embodiment of the present invention.
  • Figure 3 is a section view of an example of a damper suitable for use in the suspension architecture of Figure 1 ;
  • Figure 4 is a section view of an example of a damper suitable for use in the suspension architecture of Figure 2;
  • Figure 5 is a section view of a further example of a damper suitable for use in the suspension architecture of Figure 2.
  • a main spring 10 (hereinafter simply referred to as spring), which is preferably, even though not necessarily, made as a mechanical spring, in particular as a cylindrical hel- ical spring, and is interposed between the body of the vehicle (or more generally the sprung mass of the vehicle) and the wheel of the vehicle (or more generally the unsprung mass of the vehicle);
  • a damper 12 that is made as a hydraulic damper and comprises, in a per-se-known manner, a cylinder 14, a main piston 16 slidably accommodated in the cylinder 14 so as to divide the inner volume of the cylinder 14 into a compression chamber 18 and an extension chamber 20, and a rod 22, rigidly connected to the main piston 16 and protruding from the top of the cylinder 14 to be connected to the body of the vehicle, the damper 12 being also interposed between the body and the wheel of the vehicle, in parallel with the spring 10; and
  • the reaction element may be formed by an elastic element 24, such as a mechanical spring (in particular a cylindrical helical spring), as in the embodiment of Figure 1 , or, alternatively, by a cup-shaped hollow body 26 arranged to work as a hydraulic bump stop cooperating with an auxiliary piston 28 drivingly connected to the main piston 16 of the damper 12, as in the embodiment of Figure 2. Regardless of how the reaction element is made, it opposes the extension movement of the damper 12 starting from a given travel value of the damper in the extension phase.
  • an elastic element 24 such as a mechanical spring (in particular a cylindrical helical spring), as in the embodiment of Figure 1
  • a cup-shaped hollow body 26 arranged to work as a hydraulic bump stop cooperating with an auxiliary piston 28 drivingly connected to the main piston 16 of the damper 12, as in the embodiment of Figure 2.
  • reaction element is formed by the elastic element 24, it opposes the extension movement of the damper 12 by exerting an elastic force on the main piston 16 of the damper as soon as the main piston 16, or another mechanical member drivingly connected to the main piston 16, comes into abutment with the bottom end of the elastic element 24.
  • the reaction element is formed by the cup-shaped body 26 of a hydraulic bump stop, it opposes the extension movement of the damper 12 by exerting a viscous reaction force on the main piston 16 of the damper as soon as the auxil- iary piston 28 enters into the cup-shaped body 26.
  • the point of intervention of the reaction element corresponds then, in this case, to the auxiliary piston 28 entering into the cup- shaped body 26, which occurs at a given travel value of the damper in the extension phase, depending on the relative axial position of the auxiliary piston 28 with respect to the cup- shaped body 26 in rest condition.
  • the suspension further comprises adjustment means associated to the reaction element to adjust the axial position of said element in the extension chamber 20 of the damper, and hence the relative axial position of said element with respect to the main piston 16 or the auxiliary piston 28, and thus adjust the travel value, in the extension phase, starting from which the reaction element 24 or 26 intervenes to oppose the extension movement of the damper.
  • Said adjustment means comprise an adjustment piston 30, that is mounted axially slidable in the extension chamber 20 of the damper 12 and is drivingly connected for axial sliding movement with the reaction element 24 or 26, as well as a hydraulic control circuit 32, that communicates with the extension chamber 20 of the damper 12 and is arranged to control the axial position of the adjustment piston 30 in the extension chamber 20.
  • the adjustment piston 30 comprises an annular piston body 34, that is mounted axially slidable on the rod 18 of the damper 12 and seals tightly with the cylinder 14 of the damper 12 so as to split the extension chamber 20 into an upper compartment 20a, which faces to- wards the opposite side with respect to the main piston 16, and a lower compartment 20b, which faces towards the main piston 16 and in which the reaction element 24 or 26 is placed.
  • the hydraulic control circuit 32 comprises a reservoir T, a hydraulic pump P, a hydraulic line L in fluid communication with the upper compartment 20a of the extension chamber 20 of the damper 12, and a control valve V, for example a three-way two-position solenoid valve, arranged to control the connection of the hydraulic line L with the reservoir T and the hydraulic pump P.
  • a control valve V for example a three-way two-position solenoid valve, arranged to control the connection of the hydraulic line L with the reservoir T and the hydraulic pump P.
  • the hydraulic valve V of the hydraulic control circuit 32 is connected, in a per-se-known manner, to an electronic control unit (not shown) that is arranged to manage the operation of the suspension, in particular to adjustthe overall stiffness of the suspension by adjusting the position of the adjustment piston 30 in the way illustrated above, depending on certain parameters representative of the driving conditions of the vehicle.
  • the suspension further comprises an elastomeric bump stop 36, of a per-se- known type, that is carried by the sprung mass and acts on the damper 12 in proximity of the extension end-of-travel position to oppose the extension movement of the damper 12 in the last portion of travel before the end-of-travel position is reached.
  • FIGS 3 to 5 show three possible embodiments of a damper for a suspension according to the invention, where the damper is of the so-called three-tube type.
  • the damper 10 comprises:
  • the adjustment piston 30, or more precisely the piston body 34 of the adjustment piston 30, is mounted axially slidable in the extension chamber 20 and divides the latter into the upper compartment 20a and the lower compartment 20b.
  • the piston body 34 is provided with a sealing gasket 46 that seals tightly with the internal surface of the inner tube 38.
  • the piston body 34 is made as an annular body, through which the rod 22 of the damper 12 extends.
  • the elastic element 24, which is made in this case as a cylindrical heli- cal spring, is secured to the piston body 34. The elastic element 24 is placed in the lower compartment 20b of the extension chamber 20.
  • an abutment member 48 intended to go into abutment against the bottom end of the elastic element 24 (that is, as in the embodiment shown in Figure 3, against a spring plate 50 against which the bottom end of the elastic element 24 rests) in the extension phase of the damper 12, thus causing an elastic deformation (compression) of the elastic element 24.
  • the intermediate compartment 44 is in fluid communication on one side with the hydraulic line L of the hydraulic control circuit 32, through a joint member 52 that protrudes from the damper 12 passing through the outer tube 40, and on the other with the upper compartment 20a, through one or more holes 54 provided in the inner tube 38.
  • the working fluid of the hydraulic control circuit 32 flows into the upper compartment 20a through the intermediate compartment 44, thus causing the displacement of the piston body 34 of the adjustment piston 30, and hence of the elastic element 24 connected thereto, towards the main piston 16, and hence towards the abutment member 48. Therefore, the distance between the bottom end of the elastic element 24 and the abutment member 48 is reduced, with the result that the intervention of the elastic element 24 during the extension stroke of the damper 12 is anticipated.
  • the adjustment piston 30 further comprises a tubular portion 56 rigidly connected to the piston body 34.
  • the rod 22 of the damper 12 passes not only through the pis- ton body 34, but also through the tubular portion 56.
  • two or more bushings 58, or similar sliding bearing members, are mounted on the internal cylindrical surface of the tubular portion 56 to support the tubular portion 56 of the adjustment piston 30 on the rod 22 of the damper 12.
  • the tubular portion 56 of the adjustment piston 30 extends, like the rod 22, through an upper cap 60 of the cylinder 14 of the damper 12.
  • the damper shown in Figure 4 has a configuration like that of the damper described above with reference to Figure 3.
  • the only difference is basically that in this case, instead of the elastic element 24, a cup-shaped body 26 is used as reaction element, which cup-shaped body is secured to the piston body 34 of the adjustment piston 30 and cooperates with an auxiliary piston 28 fixed to the rod 22 of the damper 12 to exert on the auxiliary piston 28, and hence to the rod 22, a viscous reaction force opposing the extension movement when the auxiliary piston 28 enters in the cup-shaped body 26 in the extension phase of the damper 12.
  • a cup-shaped body 26 is used as reaction element, which cup-shaped body is secured to the piston body 34 of the adjustment piston 30 and cooperates with an auxiliary piston 28 fixed to the rod 22 of the damper 12 to exert on the auxiliary piston 28, and hence to the rod 22, a viscous reaction force opposing the extension movement when the auxiliary piston 28 enters in the cup-shaped body 26 in the extension phase of the damper 12.
  • Figure 5 of the attached drawings shows a further embodiment of the damper 12 that, compared with the embodiment of Figure 4, further comprises a second intermediate tube 62 radially interposed between the inner tube 38 and the outer tube 40, underneath the first intermediate tube 42, so as to enclose with the inner tube 38 a by-pass chamber 64 that is in communication with the lower compartment 20b of the extension chamber 20 through one or more communication holes 66 provided in the inner tube 38, as well as a control valve 68 (of a per-se-known type) connected to the second intermediate tube 62 and arranged to control the flow of the working fluid of the damper 12 between the lower compartment 20b of the extension chamber 20 and the by-pass chamber 64 so as to allow to adjust the damping of the damper.
  • a control valve 68 of a per-se-known type
  • a suspension according to the present invention it is possible to actively adjust the overall stiffness of the suspension in the extension phase of the damper by suitably adjusting the axial position of the reaction element in the extension chamber of the damper.

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  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Vehicle Body Suspensions (AREA)

Abstract

The suspension comprises: a main spring (10) interposed between the wheel and the body of the vehicle; a damper (12) interposed between the wheel and the body of the vehicle, in parallel with the main spring (10), the damper (12) comprising a cylinder (14), a main piston (16) which is slidably accommodated in the cylinder (14) and divides the internal volume of the cylinder (14) into a compression chamber (18) and an extension chamber (20), and a rod (22) which is rigidly connected to the main piston (16) and protrudes from the top of the cylinder (14); a reaction element (24, 26) which is accommodated in the extension chamber (20) of the damper (12) and is arranged to oppose the extension movement of the damper (12); and adjustment means (30, 32) associated to the reaction element (24, 26) to adjust the axial position of said element in the extension chamber (20) of the damper (12) and thus adjust the travel value starting from which, during the extension phase, the reaction element (24, 26) intervenes to oppose the extension movement of the damper (12). The adjustment means (30, 32) comprise an adjustment piston (30) which is slidably mounted in the extension chamber (20) of the damper (12) and to which the reaction element (24, 26) is drivingly connected, and a hydraulic control circuit (32) which communicates with the extension chamber (20) of the damper (12) and is arranged to control the axial position of the adjustment piston (30) in the extension chamber (20) of the damper (12).

Description

Vehicle wheel suspension provided with active adjustment system for adjustinfi in a controlled manner the overall stiffness of the suspension
The present invention relates to a vehicle wheel suspension, of the type comprising a spring, such as for example a helical spring or a similar elastic element, interposed between the wheel and the body of the vehicle, and a damper, also interposed between the wheel and the body of the vehicle, in parallel with the spring.
While designing a vehicle wheel suspension of the kind identified above, the designer shall find each time the best compromise, depending on the specific application, between two contrasting requirements, that is road-holding (and thus safety) and comfort. In particular, the two parameters involved in the definition of the characteristics of the suspension, and thus in the determination of the optimal compromise between road-holding and comfort, are the stiffness of the spring and the damping of the damper. The design choice is general- ly determined by the kind of use for which the vehicle has been designed. In sport vehicles, road-holding is naturally preferred, to the detriment of comfort, while for example in city- cars comfort is preferred, to the detriment of road-holding.
Since the operating conditions for which road-holding shall be preferred are generally dis- cemible from the conditions for which comfort shall be preferred, it is known to use suspension active adjustment systems allowing to actively adjust, in real time, the characteristics of the suspensions depending on the vehicle driving conditions.
Suspension active adjustment systems are known, which allow for example to change the force-speed characteristic of the damper to change the force between the sprung mass and the unsprung mass of the vehicle during the transient phase of the dynamics of the vehicle.
Suspension active adjustment systems are also known, which allow to change in a controlled manner the stiffness of the spring to change the force exerted between the sprung mass and the unsprung mass of the vehicle, not only during the transient phase of the dynamics of the vehicle, but also at steady state, for example during cornering. As they are able to vary the overall stiffness of the suspension, these adjustment systems further allow, in steady conditions, to change the attitude of the vehicle both to accomplish several comfort or road-holding targets and to adapt the attitude of the vehicle to any load variations. The present inventions relates to this second category of suspension active adjustment systems and aims at providing a vehicle wheel suspension that is provided with an active adjustment system, improved with respect to the prior art, for continuously adjusting, in a controlled manner, the overall stiffness of the suspension, that is the ratio of the force exerted between the sprung mass and the unsprung mass of the vehicle to the relative position of the sprung mass with respect to the unsprung mass of the vehicle, at that wheel.
A further object of the present invention is to provide a vehicle wheel suspension provided with an active stiffness adjustment system that is structurally simple and not expensive. These and other objects are fully achieved according to the invention by virtue of a vehicle wheel suspension having the features set forth in the attached independent claim 1 .
Advantageous embodiments of the invention are defined in the dependent claims, the subject-matter of which shall be considered as forming an integral part of the following de- scription.
In short, the invention is based on the idea of providing a suspension of the type mentioned above comprising, in addition to the main spring and the damper:
a reaction element which is accommodated in the extension chamber of the damper and is arranged to oppose the extension movement of the damper starting from a given travel value of the damper in the extension phase, and
adjustment means associated to the reaction element to adjust the axial position of said element inside the extension chamber of the damper and thus adjust the travel value, in the extension phase, starting from which the reaction element intervenes to oppose the extension movement of the damper,
wherein the adjustment means comprise an adjustment piston that is mounted axially slida- ble in the extension chamber of the damper and is drivingly connected for axial sliding movement with the reaction element, and a hydraulic control circuit which communicates with the extension chamber of the damper and is arranged to control the axial position of the adjustment piston in the extension chamber of the damper.
By virtue of such a configuration, a suspension according to the invention allows to adjust, in a controlled manner, the point of intervention of the reaction element in the extension phase of the damper and thus to adjust, in a controlled manner, the overall stiffness of the suspension. By providing all the wheels of a vehicle with such a suspension, it is thus pos- sible to adjust the overall stiffness of every single corner of the vehicle in order to adjust the overall roll stiffness of each of the two axles of the vehicle or to adjust the attitude of the vehicle.
According to an embodiment, the reaction element is formed by an elastic element, prefer- ably a mechanical spring.
According to a further embodiment, the reaction element is formed by a cup-shaped hollow body arranged to work as a hydraulic bump stop cooperating with an auxiliary piston drivingly connected to the main piston of the damper.
Preferably, the adjustment piston comprises an annular piston body, that is mounted axially slidable on the rod of the damper and seals tightly with the cylinder of the damper so as to split the extension chamber of the damper into an upper compartment, facing towards the opposite side with respect to the main piston of the damper, and a lower compartment, fac- ing towards the main piston of the damper, the reaction element being placed in said lower compartment.
According to a preferred embodiment, the adjustment piston further comprises a tubular portion rigidly connected to the annular piston body, said tubular portion being mounted axially slidable on the rod of the damper and extending through an upper cap of the damper. Conveniently, the damper has a three-tube architecture comprising:
an inner tube, or pressure tube, where the main piston of the damper is mounted so as to divide the inner volume of the inner tube into the extension chamber and the compression chamber, and where the adjustment piston is also mounted, namely inside the ex- tension chamber,
an outer tube, and
a first intermediate tube, radially interposed between the inner tube and the outer tube, the first intermediate tube enclosing, together with the inner tube, an intermediate compartment that is in fluid communication with the hydraulic control circuit, on one side, and with the upper compartment defined by the adjustment piston inside the extension chamber, on the other side.
In case of a damper having a three-tube architecture as specified above, preferably the damper further comprises:
a second intermediate tube, radially interposed between the inner tube and the outer tube, underneath the first intermediate tube, so as to enclose, together with the inner tube, a by-pass chamber that is in fluid communication with the lower compartment of the extension chamber through one or more communications holes provided in the inner tube, and a control valve connected to the second intermediate tube and arranged to control the flow of the working fluid of the damper between the lower compartment of the extension chamber and the by-pass chamber, so as to allow to adjust the damping of the damper.
Further features and advantages of the present invention will become apparent from the following detailed description, given purely by way of non-limiting example, with refer- ence to the appended drawings, where:
Figure 1 is a schematic representation of a vehicle wheel suspension architecture according to an embodiment of the present invention;
Figure 2 is a schematic representation of a vehicle wheel suspension architecture according to a further embodiment of the present invention;
Figure 3 is a section view of an example of a damper suitable for use in the suspension architecture of Figure 1 ; Figure 4 is a section view of an example of a damper suitable for use in the suspension architecture of Figure 2; and
Figure 5 is a section view of a further example of a damper suitable for use in the suspension architecture of Figure 2.
With reference initially to Figures 1 and 2, a vehicle wheel suspension according to an embodiment of the present invention comprises:
a main spring 10 (hereinafter simply referred to as spring), which is preferably, even though not necessarily, made as a mechanical spring, in particular as a cylindrical hel- ical spring, and is interposed between the body of the vehicle (or more generally the sprung mass of the vehicle) and the wheel of the vehicle (or more generally the unsprung mass of the vehicle);
a damper 12 that is made as a hydraulic damper and comprises, in a per-se-known manner, a cylinder 14, a main piston 16 slidably accommodated in the cylinder 14 so as to divide the inner volume of the cylinder 14 into a compression chamber 18 and an extension chamber 20, and a rod 22, rigidly connected to the main piston 16 and protruding from the top of the cylinder 14 to be connected to the body of the vehicle, the damper 12 being also interposed between the body and the wheel of the vehicle, in parallel with the spring 10; and
a reaction element accommodated in the damper 12, namely in the extension chamber 20, to oppose the extension movement of the damper 12 starting from a given travel value of the damper in the extension phase.
The reaction element may be formed by an elastic element 24, such as a mechanical spring (in particular a cylindrical helical spring), as in the embodiment of Figure 1 , or, alternatively, by a cup-shaped hollow body 26 arranged to work as a hydraulic bump stop cooperating with an auxiliary piston 28 drivingly connected to the main piston 16 of the damper 12, as in the embodiment of Figure 2. Regardless of how the reaction element is made, it opposes the extension movement of the damper 12 starting from a given travel value of the damper in the extension phase. In the embodiment of Figure 1 , where the reaction element is formed by the elastic element 24, it opposes the extension movement of the damper 12 by exerting an elastic force on the main piston 16 of the damper as soon as the main piston 16, or another mechanical member drivingly connected to the main piston 16, comes into abutment with the bottom end of the elastic element 24. The point of intervention of the reaction element corresponds then, in this case, to the abutment of the main piston 16, or of the mechanical member drivingly connected wherewith, against the elastic element 24, which will occur at a given travel span of the damper in the extension phase depending on the relative axial position (where the term ''axial" refers to the longitudinal axis of the damper 12, indicated with z in Figures 3 to 5) of the main piston 16 with respect to the elastic element 24 in rest condition.
In the embodiment of Figure 2, where the reaction element is formed by the cup-shaped body 26 of a hydraulic bump stop, it opposes the extension movement of the damper 12 by exerting a viscous reaction force on the main piston 16 of the damper as soon as the auxil- iary piston 28 enters into the cup-shaped body 26. The point of intervention of the reaction element corresponds then, in this case, to the auxiliary piston 28 entering into the cup- shaped body 26, which occurs at a given travel value of the damper in the extension phase, depending on the relative axial position of the auxiliary piston 28 with respect to the cup- shaped body 26 in rest condition.
According to the invention, the suspension further comprises adjustment means associated to the reaction element to adjust the axial position of said element in the extension chamber 20 of the damper, and hence the relative axial position of said element with respect to the main piston 16 or the auxiliary piston 28, and thus adjust the travel value, in the extension phase, starting from which the reaction element 24 or 26 intervenes to oppose the extension movement of the damper.
Said adjustment means comprise an adjustment piston 30, that is mounted axially slidable in the extension chamber 20 of the damper 12 and is drivingly connected for axial sliding movement with the reaction element 24 or 26, as well as a hydraulic control circuit 32, that communicates with the extension chamber 20 of the damper 12 and is arranged to control the axial position of the adjustment piston 30 in the extension chamber 20. By adjusting the axial position of the adjustment piston 30 in the extension chamber 20 through the hydraulic control circuit 32 it is thus possible to adjust the axial position of the reaction element 24 or 26 in the extension chamber 20 and thus adjust the point of intervention of said ele- ment during the extension movement of the damper 12.
The adjustment piston 30 comprises an annular piston body 34, that is mounted axially slidable on the rod 18 of the damper 12 and seals tightly with the cylinder 14 of the damper 12 so as to split the extension chamber 20 into an upper compartment 20a, which faces to- wards the opposite side with respect to the main piston 16, and a lower compartment 20b, which faces towards the main piston 16 and in which the reaction element 24 or 26 is placed.
The hydraulic control circuit 32 comprises a reservoir T, a hydraulic pump P, a hydraulic line L in fluid communication with the upper compartment 20a of the extension chamber 20 of the damper 12, and a control valve V, for example a three-way two-position solenoid valve, arranged to control the connection of the hydraulic line L with the reservoir T and the hydraulic pump P. By connecting the line L with the pump P, the upper compartment 20a is supplied and thus the adjustment piston 30 is moved downwards, and therefore the intervention of the reaction element 24 or 26 is anticipated, that is, the travel value, during the extension movement of the damper 12, at which the reaction element 24 or 26 starts exerting its reaction force against the extension movement of the damper is reduced. On the contrary, by connecting the line L with the reservoir T, the adjustment piston 30 is moved upwards, and therefore the intervention of the reaction element 24 or 26 is delayed, that is, the travel value, during the extension movement of the damper 12, at which the reaction element 24 or 26 starts exerting its reaction force against the extension movement of the damper is increased.
Furthermore, by adjusting the axial position of the adjustment piston 30 in the extension chamber 20 of the damper 12, it is possible to pressurize or depressurize the damper itself, thus providing a sort of gas spring that works in parallel with the main spring 10. By pres- surizing or depressurizing the damper 12 in the way described above, it is also possible to adjust the working point of the suspension depending on the static load of the vehicle.
The hydraulic valve V of the hydraulic control circuit 32 is connected, in a per-se-known manner, to an electronic control unit (not shown) that is arranged to manage the operation of the suspension, in particular to adjustthe overall stiffness of the suspension by adjusting the position of the adjustment piston 30 in the way illustrated above, depending on certain parameters representative of the driving conditions of the vehicle. Preferably, the suspension further comprises an elastomeric bump stop 36, of a per-se- known type, that is carried by the sprung mass and acts on the damper 12 in proximity of the extension end-of-travel position to oppose the extension movement of the damper 12 in the last portion of travel before the end-of-travel position is reached. Figures 3 to 5 (where parts and elements identical or corresponding to those of Figures 4 and 2 have been given the same reference numbers) show three possible embodiments of a damper for a suspension according to the invention, where the damper is of the so-called three-tube type. With initial reference to Figure 3, the damper 10 comprises:
an inner tube 38, or pressure tube, where the main piston 16 is slidably mounted along the longitudinal axis z (coinciding with the axis of the inner tube 38) and divides the inner volume of the inner tube 38 into the compression chamber 18 and the extension chamber 20,
an outer tube 40, and
a first intermediate tube 42, radially interposed between the inner tube 38 and the outer tube 40 so as to enclose, together with the inner tube 38, an intermediate compartment 44. The adjustment piston 30, or more precisely the piston body 34 of the adjustment piston 30, is mounted axially slidable in the extension chamber 20 and divides the latter into the upper compartment 20a and the lower compartment 20b. To this end, the piston body 34 is provided with a sealing gasket 46 that seals tightly with the internal surface of the inner tube 38. The piston body 34 is made as an annular body, through which the rod 22 of the damper 12 extends. The elastic element 24, which is made in this case as a cylindrical heli- cal spring, is secured to the piston body 34. The elastic element 24 is placed in the lower compartment 20b of the extension chamber 20. On the rod 22, more specifically on a portion of the rod 22 placed in the lower compartment 20b of the extension chamber 20, there is fixed an abutment member 48 intended to go into abutment against the bottom end of the elastic element 24 (that is, as in the embodiment shown in Figure 3, against a spring plate 50 against which the bottom end of the elastic element 24 rests) in the extension phase of the damper 12, thus causing an elastic deformation (compression) of the elastic element 24.
The intermediate compartment 44 is in fluid communication on one side with the hydraulic line L of the hydraulic control circuit 32, through a joint member 52 that protrudes from the damper 12 passing through the outer tube 40, and on the other with the upper compartment 20a, through one or more holes 54 provided in the inner tube 38. In this way, when the hydraulic line L is connected to the hydraulic pump P, the working fluid of the hydraulic control circuit 32 flows into the upper compartment 20a through the intermediate compartment 44, thus causing the displacement of the piston body 34 of the adjustment piston 30, and hence of the elastic element 24 connected thereto, towards the main piston 16, and hence towards the abutment member 48. Therefore, the distance between the bottom end of the elastic element 24 and the abutment member 48 is reduced, with the result that the intervention of the elastic element 24 during the extension stroke of the damper 12 is anticipated.
On the contrary, when the hydraulic line L is connected to the reservoir T, the piston body 34 of the adjustment piston 30 moves in the opposite direction, i.e. upwards, because of the pressure gradient at its ends. The distance between the bottom end of the elastic element 24 and the abutment member 48 thus increases, with the result that the intervention of the elastic element 24 during the extension stroke of the damper 12 is delayed. Accordingly, by conveniently adjusting the axial position of the piston body 34 of the adjustment piston 30, and hence the distance between the bottom end of the elastic element 24 and the abutment member 48, it is possible to adjust the point of intervention of the elastic element 24 in the extension phase of the damper 12, i.e. the travel value starting from which the elastic element 24 exerts an elastic force, opposing the extension movement, on the assembly formed by the main piston 16 and the rod 22.
Preferably, the adjustment piston 30 further comprises a tubular portion 56 rigidly connected to the piston body 34. The rod 22 of the damper 12 passes not only through the pis- ton body 34, but also through the tubular portion 56. Advantageously, two or more bushings 58, or similar sliding bearing members, are mounted on the internal cylindrical surface of the tubular portion 56 to support the tubular portion 56 of the adjustment piston 30 on the rod 22 of the damper 12. Preferably, the tubular portion 56 of the adjustment piston 30 extends, like the rod 22, through an upper cap 60 of the cylinder 14 of the damper 12.
The damper shown in Figure 4 has a configuration like that of the damper described above with reference to Figure 3. The only difference is basically that in this case, instead of the elastic element 24, a cup-shaped body 26 is used as reaction element, which cup-shaped body is secured to the piston body 34 of the adjustment piston 30 and cooperates with an auxiliary piston 28 fixed to the rod 22 of the damper 12 to exert on the auxiliary piston 28, and hence to the rod 22, a viscous reaction force opposing the extension movement when the auxiliary piston 28 enters in the cup-shaped body 26 in the extension phase of the damper 12. For the rest, what has already been said above with reference to the embodiment of Figure 3 still applies.
Finally, Figure 5 of the attached drawings shows a further embodiment of the damper 12 that, compared with the embodiment of Figure 4, further comprises a second intermediate tube 62 radially interposed between the inner tube 38 and the outer tube 40, underneath the first intermediate tube 42, so as to enclose with the inner tube 38 a by-pass chamber 64 that is in communication with the lower compartment 20b of the extension chamber 20 through one or more communication holes 66 provided in the inner tube 38, as well as a control valve 68 (of a per-se-known type) connected to the second intermediate tube 62 and arranged to control the flow of the working fluid of the damper 12 between the lower compartment 20b of the extension chamber 20 and the by-pass chamber 64 so as to allow to adjust the damping of the damper. For the rest, what has already been said above with refer- ence to the embodiments shown in Figures 3 and 4 still applies.
As it is clear from the description given above, by virtue of a suspension according to the present invention it is possible to actively adjust the overall stiffness of the suspension in the extension phase of the damper by suitably adjusting the axial position of the reaction element in the extension chamber of the damper.
FurtheiTnore. by virtue of the fact that the reaction element and the associated adjustment means (except for the hydraulic control circuit) for adjusting the axial position of the reaction element are placed inside the damper, a much more structurally compact arrangement is obtained.
Naturally, the principle of the invention remaining unchanged, the embodiments and constructional details may vary widely from those described and illustrated purely by way of non-limiting example, without thereby departing from the scope of the invention as defined in the enclosed claims.

Claims

1. Vehicle wheel suspension, comprising
a main spring ( 10) interposed between a wheel and a body of a vehicle,
a damper ( 12) interposed between the wheel and the body of the vehicle, in parallel with the main spring ( 10), the damper ( 12) comprising a cylinder ( 14), a main piston ( 16) which is slidably accommodated in the cylinder ( 14) for sliding along a longitudinal axis (z) of the damper ( 12) and divides the internal volume of the cylinder ( 14) into a compression chamber ( 18) and an extension chamber (20), and a rod (22) which is rigidly connect- ed to the main piston ( 16) and protrudes from the top of the cylinder (14) to be connected to the body of the vehicle,
a reaction element (24, 26) which is accommodated in the extension chamber (20) of the damper ( 12) and is arranged to oppose the extension movement of the damper ( 12) starting from a given travel value of the damper ( 12) during the extension phase, and
adjustment means (30, 32) associated to the reaction element (24, 26) to adjust the axial position of said element in the extension chamber (20) of the damper ( 12) and thus adjust the travel value, during the extension phase, starting from which the reaction element (24, 26) intervenes to oppose the extension movement of the damper ( 12), wherein said adjustment means (30, 32) comprise an adjustment piston (30) which is mounted axially slidable in the extension chamber (20) of the damper (12) and with which the reaction element (24, 26) is drivingly connected for sliding along the longitudinal axis (z), and a hydraulic control circuit (32) which communicates with the extension chamber (20) of the damper ( 12) and is arranged to control the axial position of the adjustment piston (30) in the extension chamber (20) of the damper ( 12).
2. Suspension according to claim 1 , wherein the reaction element (24, 26) is an elastic element (24).
3. Suspension according to claim 2, wherein the reaction element (24, 26) is a me- chanical spring (24), such as a cylindrical helical spring, and wherein the damper ( 12) further comprises an abutment member (48) which is fixed to the rod (22) and is arranged to abut against a piston-side end of the mechanical spring (24), during the extension phase of the damper ( 12), so as to cause, as a result of a further extension of the damper ( 12), an elastic deformation of the mechanical spring (24).
4. Suspension according to claim 1 , wherein the damper ( 12) further comprises an auxiliary piston (28) drivingly connected to the main piston ( 16), that is to the rod (22), and wherein the reaction element (24, 26) is a cup-shaped hollow body (26) arranged to work as a hydraulic bump stop cooperating with the auxiliary piston (28).
5. Suspension according to any of the preceding claims, wherein the adjustment piston (30) comprises an annular piston body (34), which is mounted axially slidable on the rod (22) of the damper ( 12) and seals tightly with the cylinder ( 14) of the damper ( 12) so as to split the extension chamber (20) into an upper compartment (20a), which faces towards the opposite side with respect to the main piston ( 16), and a lower compartment (20b), which faces towards the main piston ( 16) and in which the reaction element (24, 26) is placed.
6. Suspension according to claim 5, wherein the adjustment piston (30) further comprises a tubular portion (56) rigidly connected to the piston body (34), said tubular portion (56) being mounted axially slidable on the rod (22) of the damper ( 12).
7. Suspension according to claim 6, wherein the tubular portion (56) of the adjustment piston (30) extends through an upper cap (60) of the cylinder (14) of the damper (12).
8. Suspension according to any of claims 5 to 7, wherein the damper ( 12) has a three- tube architecture, with an inner tube (38). where the main piston ( 16) is mounted, an outer tube (40) and a first intermediate tube (42), radially interposed between the inner tube (38) and the outer tube (40) so as to enclose, together with the inner tube (38), an intermediate compartment (44) which is in fluid communication on one side with the hydraulic control circuit (32) and on the other with the upper compartment (20a) defined by the adjustment piston (30) in the extension chamber (20).
9. Suspension according to claim 8, wherein the damper ( 12) further comprises a second intermediate tube (62). radially interposed between the inner tube (38) and the outer tube (40), underneath the first intermediate tube (42), so as to enclose with the inner tube (38) a by-pass chamber (64) which is in fluid communication with the lower compartment (20b) of the extension chamber (20), and a control valve (68) which is connected to the second intermediate tube (62) and is arranged to control the flow of a working fluid of the damper ( 12) between the lower compartment (20b) of the extension chamber (20) and the by-pass chamber (64).
PCT/IB2017/057287 2016-11-21 2017-11-21 Vehicle wheel suspension provided with active adjustment system for adjusting in a controlled manner the overall stiffness of the suspension WO2018092111A1 (en)

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IT102016000117315 2016-11-21
IT102016000117315A IT201600117315A1 (en) 2016-11-21 2016-11-21 Suspension for vehicle wheel with active control system to regulate in a controlled way the overall stiffness of the suspension.

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Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0466628A1 (en) * 1990-07-06 1992-01-15 Mauro Bianchi S.A. Procedure for a suspension of the type having a stiffness which is greater during rebound than during shock, incorporating means for softening the change from one stiffness to the other and means for implementing the procedure
US5996978A (en) * 1996-08-27 1999-12-07 Honda Giken Kogyo Kabushiki Kaisha Hydraulic damper for vehicle
US20010025753A1 (en) * 2000-04-04 2001-10-04 Wolfgang Pfundstein Vibration damper having a rebound
DE10121918A1 (en) * 2001-05-05 2002-11-28 Daimler Chrysler Ag Spring/shock absorber system for a vehicle comprises a spring element and a shock absorber element arranged between the vehicle construction and a pull rod guiding or supporting a wheel
WO2013007572A1 (en) * 2011-07-11 2013-01-17 Mauro Bianchi Suspension method and shock-absorbing device for an automobile
WO2013050205A1 (en) * 2011-10-06 2013-04-11 Bayerische Motoren Werke Aktiengesellschaft Vehicle wheel suspension with a hydraulic vibration damper
FR2988033A1 (en) * 2012-03-13 2013-09-20 Peugeot Citroen Automobiles Sa Hydraulic shock absorber for car, has drive abutment connected to interior cylindrical body by axially elastic element, where actuating cylinder with slow dynamics is axially positioned between drive abutment and bottom of external body

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0466628A1 (en) * 1990-07-06 1992-01-15 Mauro Bianchi S.A. Procedure for a suspension of the type having a stiffness which is greater during rebound than during shock, incorporating means for softening the change from one stiffness to the other and means for implementing the procedure
US5996978A (en) * 1996-08-27 1999-12-07 Honda Giken Kogyo Kabushiki Kaisha Hydraulic damper for vehicle
US20010025753A1 (en) * 2000-04-04 2001-10-04 Wolfgang Pfundstein Vibration damper having a rebound
DE10121918A1 (en) * 2001-05-05 2002-11-28 Daimler Chrysler Ag Spring/shock absorber system for a vehicle comprises a spring element and a shock absorber element arranged between the vehicle construction and a pull rod guiding or supporting a wheel
WO2013007572A1 (en) * 2011-07-11 2013-01-17 Mauro Bianchi Suspension method and shock-absorbing device for an automobile
WO2013050205A1 (en) * 2011-10-06 2013-04-11 Bayerische Motoren Werke Aktiengesellschaft Vehicle wheel suspension with a hydraulic vibration damper
FR2988033A1 (en) * 2012-03-13 2013-09-20 Peugeot Citroen Automobiles Sa Hydraulic shock absorber for car, has drive abutment connected to interior cylindrical body by axially elastic element, where actuating cylinder with slow dynamics is axially positioned between drive abutment and bottom of external body

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