Adjustable compound torsion bar assemblies

Abstract

A torsion-member assembly for a suspension system comprises a primary torsion member, a secondary torsion member comprising a tubular portion that surrounds a first section of the primary torsion member, and a torsion bridge surrounding a lengthwise portion of the first section of the primary torsion member and surrounded in turn by the tubular portion of the secondary torsion member. The torsion bridge is in displaceable communication with, and longitudinally displaceable relative to, both the tubular portion of the secondary torsion member and the first section of the primary torsion member. A longitudinal displacement of the torsion bridge is effective to adjust a length of a torsion path of the assembly, thereby changing a torsion rate of the assembly.

Description

[0001] ADJUSTABLE COMPOUND TORSION BAR ASSEMBLIES

[0002] FIELD OF THE INVENTION

[0003] The present invention relates to torsion-bar assemblies, and particularly to systems and methods for setting and adjusting operational parameters of torsion bar assemblies.

[0004] BACKGROUND

[0005] In a torsion-bar suspension, a torsion bar is employed as the main weightbearing spring of a vehicle suspension system. In current systems, one end of a long metal bar is attached to the vehicle chassis; the opposite end is often attached, directly or indirectly, to a suspension control arm. Vertical motion of the wheel causes the bar to twist around its axis, which is resisted by the bar's torsion resistance. The effective torsion rate, i.e., spring rate, of the torsion bar, is determined by its length, cross section, shape, material, and manufacturing process. Ride height can be set by selection of a torsion bar of or a connecting element.

[0006] Compound torsion-bar assemblies have been suggested, but none have provided a capability to dynamically change a torsion rate or a vehicle height without replacing or modifying hardware elements. Nor have they been effective to reduce the footprint of torsion bars without compromising performance.

[0007] SUMMARY

[0008] According to embodiments, a torsion-member assembly for a suspension system comprises: (a) a primary torsion member; (b) a secondary torsion member comprising a tubular portion, the tubular portion surrounding a first section of the primary torsion member; and (c) a torsion bridge surrounding a lengthwise portion of the first section of the primary torsion member and surrounded by the tubular portion of the secondary torsion member, the torsion bridge being in displaceable communication with, and longitudinally displaceable relative to, both the tubular portion of the secondary torsion member and the first section of the primary torsion member. A longitudinal displacement of the torsion bridge is effective to adjust a length of a torsion path of the assembly, thereby changing a torsion rate of the assembly.

[0009] In some embodiments, the primary torsion member can be configured for fixed attachment of a second section thereof to a control arm of the suspension system.

[0010] In some embodiments, the secondary torsion member can be configured for fixed attachment to a rigid frame of a vehicle platform. In some such embodiments, In some embodiments, the secondary torsion member is configured for fixed attachment to the rigid frame at multiple attachment points.

[0011] In some embodiments, the primary torsion member can be configured to extend from a control arm of the suspension system in a first direction, and the secondary torsion member can be configured to extend from a rigid frame of a vehicle platform in the same first direction.

[0012] In some embodiments, the length of the torsion path of the assembly can be adjustable to an extent that the adjusted length is longer than the primary torsion member. In some embodiments, it can be that the length of the torsion path of the assembly is adjustable only to an extent that the adjusted length is longer than the primary torsion member.

[0013] In some embodiments, the longitudinal displacement can include sliding longitudinally. In some such embodiments, the sliding longitudinally can be along a splined path. In some embodiments, the longitudinal displacement can be along a threaded path.

[0014] In some embodiments, the longitudinal displacement can employ one or more gears. In some embodiments, the torsion-member assembly can be configured such that the longitudinal displacement is effected using one or more of electric actuation, hydraulic actuation, and pneumatic actuation.

[0015] In some embodiments, the secondary torsion member and the control arm can be attached to the same rigid frame. In some embodiments, the rigid frame can be a subframe of a vehicle corner module (VCM) that is mountable to and dismountable from the vehicle platform, the VCM comprising a wheel-hub assembly and a plurality of systems mediating between the sub-frame and the wheel-hub assembly, the plurality of systems comprising a suspension system and at least one of a drive system, a steering system, and a braking system. In some embodiments, the rigid frame can be a chassis of the vehicle platform or a part thereof.

[0016] In some embodiments, a suspension system for a vehicle platform can comprises a torsion-member assembly according to any one or more of the embodiments disclosed hereinabove. In some such embodiments, the suspension system can additionally comprise a force-transfer system configured to apply, to the secondary torsion member of the torsion-member assembly, a torque that causes the suspension system to kneel the vehicle platform. In some embodiments, it can be that a vehicle corner module (VCM) that is mountable to and non-destructively dismountable from a vehicle platform comprises a sub-frame including a rigid frame, a wheel-hub assembly, and a plurality of systems mediating between the sub-frame and the wheel-hub assembly, the plurality of systems comprising a suspension system as disclosed hereinabove, and at least one of a drive system, a steering system, and a braking system. In some such embodiments, the VCM can additionally comprise a force-transfer system operative to apply a force to longitudinally displace the torsion bridge.

[0017] In some embodiments, a vehicle platform can comprise a plurality of VCMs according to any of the embodiments disclosed hereinabove. In some embodiments, a vehicle platform can comprise a plurality of torsion-member assemblies according to any of the embodiments disclosed hereinabove. In some of the foregoing embodiments, the vehicle platform can additionally comprise a force-transfer system operative to apply a force to longitudinally displace at least one of the plurality of torsion-member assemblies. In some of the foregoing embodiments, the vehicle platform can comprise a controller configured to regulate the longitudinal displacement.

[0018] In some embodiments, a suspension system for kneeling a vehicle can comprise a torsion-member assembly according to any of the embodiments disclosed hereinabove, and a force-transfer system can be configured to apply, to the secondary torsion member of the torsion-member assembly, a torque that causes the suspension system to kneel the vehicle.

[0019] In some embodiments, a method of operating a vehicle, in which the vehicle comprises any of the vehicle platforms disclosed hereinabove, can comprise: at a first time, applying a force to longitudinally displace a torsion bridge so as to change a torsion rate of a respective torsion-member assembly; and / or, at a second time, applying a torque to a secondary torsion member to kneel the vehicle at a respective wheel.

[0020] According to embodiments, a suspension system for a wheel assembly of a vehicle comprises: (a) a telescopic damper configured to mediate between respective sprung and unsprung portions of the wheel assembly; (b) a torsion-member assembly comprising (i) a primary torsion member, (ii) a secondary torsion member comprising a tubular portion, the tubular portion surrounding a first section of the primary torsion member, and (iii) a torsion bridge surrounding a lengthwise portion of the first section of the primary torsion member and surrounded by the tubular portion of the secondary torsion member, the torsion bridge being in displaceable communication with, and longitudinally displaceable relative to, both the tubular portion of the secondary torsion member and the first section of the primary torsion member; and (c) a forcetransfer system operative to apply a force to change one or more parameters of the suspension system. In a first mode of operation, the application of the force by the force-transfer system is effective to change a torsion rate of the assembly. In a second mode of operation, the application of the force by the force-transfer system is effective to cause the suspension system to kneel the vehicle platform at the wheel assembly.

[0021] In some embodiments, the changing of the torsion rate in the first mode of operation can be by adjusting a length of a torsion path of the torsion-member assembly. In some embodiments, the kneeling of the vehicle platform in the second mode of operation can be by applying a torque to the secondary torsion member.

[0022] In some embodiments, the secondary torsion member can be fixedly attached to a rigid frame of the vehicle. In some embodiments, it can be that the primary torsion member extends from a control arm of the suspension system in a first direction, and the secondary torsion member extends from the rigid frame in the same first direction. In some such embodiments, the secondary torsion member and the control arm can be attached to the same rigid frame.

[0023] In some embodiments, the rigid frame can be a subframe of a vehicle corner module (VCM) that is mountable to and dismountable from the vehicle, wherein the VCM comprises a wheel-hub assembly and a plurality of systems mediating between the sub-frame and the wheel-hub assembly, the plurality of systems comprising the suspension system and at least one of a drive system, a steering system, and a braking system. In some embodiments, the rigid frame can be a chassis of the vehicle or a part thereof.

[0024] A method is disclosed, according to embodiments, for operating a vehicle. According to the method, the vehicle comprises, for at least one wheel thereof, a suspension system that includes a respective torsion-member assembly comprising a primary torsion member, a secondary torsion member comprising a tubular portion that surrounds a first section of the primary torsion member, and a torsion bridge surrounding a lengthwise portion of the first section of the primary torsion member and surrounded by the tubular portion of the secondary torsion member. The method comprises: (a) at a first time, applying a force to longitudinally displace the torsion bridge so as to change a torsion rate of the respective torsion-member assembly; and (b) at a second time, applying a torque to the secondary torsion member to kneel the vehicle at the respective wheel.

[0025] According to embodiments, a torsion-member assembly for a suspension system comprises: (a) a primary torsion member; (b) a secondary torsion member comprising a tubular portion, the tubular portion surrounding a first section of the primary torsion member; and (c) a torsion bridge surrounding a lengthwise portion of the first section of the primary torsion member and surrounded by the tubular portion of the secondary torsion member, the torsion bridge being in displaceable communication with, and longitudinally displaceable relative to, both the tubular portion of the secondary torsion member and the first section of the primary torsion member. An application of a torque to the secondary torsion member is effective to set a torsion rate.

[0026] In some embodiments, the torsion rate can be an initial torsion rate set at or proximate to an installation of the torsion-member assembly. In some embodiments, the torsion rate can be a journey torsion rate set at or proximate to a beginning of a journey. In some embodiments, the torsion rate can be a driver torsion rate set by or for a specific driver.

[0027] In some embodiments, the primary torsion member can be configured for fixed attachment of a second section thereof to a control arm of the suspension system; the secondary torsion member can be configured for fixed attachment to a rigid frame of a vehicle platform.

[0028] In some embodiments, the primary torsion member can be configured to extend from a control arm of the suspension system in a first direction; the secondary torsion member can be configured to extend from a rigid frame of a vehicle platform in the same first direction.

[0029] In some embodiments, the longitudinal displacement can include sliding longitudinally along a splined path.

[0030] In some embodiments, the torsion-member assembly can be configured such that the longitudinal displacement is effected using one or more of electric actuation, hydraulic actuation, and pneumatic actuation.

[0031] In some embodiments, the rigid frame can be a subframe of a vehicle corner module (VCM) mountable to and dismountable from the vehicle platform, wherein the VCM comprises a wheel-hub assembly and a plurality of systems mediating between the sub-frame and the wheel-hub assembly, said plurality of systems comprising a suspension system and at least one of a drive system, a steering system, and a braking system. In some embodiments, the rigid frame can be a chassis of the vehicle platform or a part thereof.

[0032] In some embodiments, a suspension system for a vehicle platform can comprise the torsion-member assembly of any one of embodiments disclosed hereinabove. In some such embodiments, the suspension system can additionally comprise a force-transfer system configured to apply the torque, i.e., the torque that is effective to set the torsion rate.

[0033] In some embodiments, a vehicle corner module (VCM) mountable to and non- destructively dismountable from a vehicle platform, comprising a sub-frame including a rigid frame, a wheel-hub assembly, and a plurality of systems mediating between the sub-frame and the wheel-hub assembly, wherein the plurality of systems comprises the suspension system and at least one of a drive system, a steering system, and a braking system. In some embodiments, the VCM can additionally comprise a force-transfer system operative to apply a force to longitudinally displace the torsion bridge.

[0034] In some embodiments, a vehicle platform comprises a plurality of VCMs according to the embodiments disclosed hereinabove. In some such embodiments, the torque effective to set a torsion rate is a first torque, and application of a second torque having a larger absolute value than the first torque is effective to change a height of the vehicle platform. In some embodiments, changing the height can be effective to kneel the vehicle.

[0035] In some embodiments, a method of setting a torsion rate of the suspension system of any of the embodiments disclosed hereinabove can comprise applying a torque to the secondary torsion member so as to set a torsion rate.

[0036] A method is disclosed, according to embodiments, for operating a vehicle. According to the method, the vehicle comprises a plurality of torsion-member assemblies each comprising (i) a respective primary torsion member and a respective secondary torsion member, each respective secondary torsion member comprising a tubular portion surrounding a first section of the respective primary torsion member, and (ii) a respective longitudinally displaceable, annular torsion bridge mediating between a lengthwise portion of said first section and said tubular portion. The method comprises: applying a force to longitudinally displace a respective torsion bridge of one of the torsion-member assemblies so as to change a torsion rate of said one of the torsion-member assemblies.

[0037] In some embodiments, the longitudinally displacing of the respective torsion bridge can include causing the torsion bridge to slide longitudinally along a splined path. In some embodiments, the longitudinally displacing of the respective torsion bridge can be effected using one or more of electric actuation, hydraulic actuation, and pneumatic actuation.

[0038] A method is disclosed, according to embodiments, for operating a vehicle. According to the method, the vehicle comprises a plurality of torsion-member assemblies each comprising (i) a respective primary torsion member and a respective secondary torsion member, the respective secondary torsion member comprising a tubular portion surrounding a first section of the respective primary torsion member, and (ii) a respective longitudinally displaceable, annular torsion bridge mediating between a lengthwise portion of said first section and said tubular portion. The method comprises: applying a torque to the respective secondary torsion members of one or more torsion-member assemblies to change a height of the vehicle.

[0039] In some embodiments, the applying of the torque to the respective secondary torsion members can be effective to kneel the vehicle.

[0040] BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The invention will now be described further, by way of example, with reference to the accompanying drawings, in which the dimensions of components and features shown in the figures are chosen for convenience and clarity of presentation and not necessarily to scale. In the drawings:

[0042] Figs. 1A, IB and 1C are schematic illustrations, respectively, of a primary torsion member, a secondary torsion member, and a torsion bridge, according to embodiments of the present invention.

[0043] Figs. 2A, 2B and 2C are schematic illustrations of a torsion-bar assembly, showing various positions and movement of the torsion bridge member, according to embodiments of the present invention.

[0044] Fig. 2D is a schematic cross-sectional illustration of the torsion-bar assembly of Fig. 2A.

[0045] Fig. 3 is a schematic plan- view drawing of parts of a suspension system comprising a torsion-bar assembly, according to embodiments of the present invention.

[0046] Fig. 4 is a schematic partial perspective-view drawing of a suspension system comprising a torsion-bar assembly, according to embodiments of the present invention.

[0047] Fig. 5 is a schematic illustration showing a compound torsion bar. Figs. 6A, 6B, 6C and 6D are schematic illustrations of a torsion-bar assembly annotated to show various respective features and / or functionalities, according to embodiments of the present invention.

[0048] Figs. 7A, 7B and 7C show examples of various respective primary torsion members, according to embodiments of the present invention.

[0049] Figs. 8A, 8B and 8C show examples of various respective secondary torsion members, according to embodiments of the present invention.

[0050] Figs. 9A and 9B show examples of various respective torsion bridges, according to embodiments of the present invention.

[0051] Figs. 10A and 10B are schematic illustrations of respective vehicle platforms each comprising a rigid frame, according to embodiments of the present invention.

[0052] Fig. 11 is a schematic illustration of a vehicle corner module comprising a rigid frame, according to embodiments of the present invention.

[0053] Figs. 12, 13, 15 and 16 show flowcharts of methods and method steps for operating a vehicle.

[0054] Fig. 14 shows a flowchart of a method for setting a torsion rate of a suspension system.

[0055] It will be appreciated that for simplicity and clarity of illustration, elements shown in the figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity. Further, where considered appropriate, reference numbers may be repeated among the figures to indicate corresponding or analogous elements.

[0056] DETAILED DESCRIPTION OF THE PRESENT INVENTION

[0057] The invention is herein described, by way of example only, with reference to the accompanying drawings. With specific reference now to the drawings in detail, it is stressed that the particulars shown are by way of example and for purposes of illustrative discussion of the preferred embodiments of the present invention only, and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the invention. In this regard, no attempt is made to show structural details of the invention in more detail than is necessary for a fundamental understanding of the invention, the description taken with the drawings making apparent to those skilled in the art how the several forms of the invention may be embodied in practice. Throughout the drawings, like-referenced characters are generally used to designate like elements.

[0058] Note: Throughout this disclosure, subscripted reference numbers (e.g., 10i or 10A) may be used to designate multiple separate appearances of elements of a single species, whether in a drawing or not; for example: 101 is a single appearance (out of a plurality of appearances) of element 10. The same elements can alternatively be referred to without subscript (e.g., 10 and not 10i) when not referring to a specific one of the multiple separate appearances, i.e., to the species in general.

[0059] For convenience, in the context of the description herein, various terms are presented here. To the extent that definitions are provided, explicitly or implicitly, here or elsewhere in this application, such definitions are understood to be consistent with the usage of the defined terms by those of skill in the pertinent art(s). Furthermore, such definitions are to be construed in the broadest possible sense consistent with such usage.

[0060] Unless otherwise indicated, a “vehicle corner module” or “VCM” as used herein means an assembly for supporting a wheel of a vehicle and regulating the motion of a vehicle according to any of the embodiments disclosed herein. The VCM assembly includes components such as (and not exhaustively): steering systems, suspension systems, braking systems including hydraulic sub-systems, gearing assemblies, drive motors, driveshafts, wheel hub assemblies, controllers, communications arrangements, and electrical wiring. In some embodiments, a VCM can include a wheel and tire. A VCM can be mounted to a ‘reference frame’ of a vehicle, e.g., a chassis or similar vehicle frame or a platform, although the mounting need not necessarily be done ‘as a unit’. When a VCM is described as being installed in / on a vehicle, then the VCM is mounted to the reference frame. A VCM may include a ‘sub-frame’ to which some or all of the VCM components are mounted or otherwise attached such that the sub-frame mediates between the reference frame and the various VCM components. The term ‘sub-frame’ should be understood to mean any rigid frame or one or more structural elements in fixed combination. The ‘sub’ prefix is intended to distinguish the sub-frame from a main frame or reference frame of the vehicle, which can include, in some examples, a vehicle chassis or a portion thereof. A VCM may or may not include one or more electric motors and / or the wheel itself (and tire).

[0061] When used in this specification and in the claims appended hereto, the word “vehicle” is to be understood as referring to a motorized vehicle having one or more wheels. Non-limiting examples of a vehicle, according to this definition, are a vehicle with motive power provided by an onboard engine, and an ‘electric vehicle’ powered, when in motion, by one or more electric motors and a battery or other energy storage device onboard. The battery need not be provided with the vehicle, or installed in the vehicle, unless and until the vehicle is in motion. The word ‘vehicle’ should also be understood as encompassing a “vehicle platform” comprising at least a chassis (or other ‘reference frame’ to which VCMs can be mounted) and one or more wheels. A ‘vehicle platform’ need not necessarily comprise, at the time of providing the vehicle platform, all of the accoutrements required for transport of passengers and / or cargo such as vehicle-body components or interior furnishings.

[0062] Embodiments of the invention relate to torsion-member assemblies and vehicle suspension systems incorporating torsion-member assemblies, as well as vehicles, vehicle platforms, and VCMs incorporating torsion-member assemblies and suspension systems incorporating torsion-member assemblies. The torsion-member assembly serves as a compound torsion bar and can be employed to substitute torsion bar springing for a vertical spring suspension but with a smaller footprint than that of a conventional torsion bar. A torsion-member assembly according to embodiments includes three mechanical components: a primary and secondary torsion members, and a torsion bridge mediating therebetween. A primary torsion member is an elongated rod typically mounted to the control arm of a suspension system. When the suspension arm moves vertically, the primary torsion member twists as with a conventional torsion bar. Unlike a conventional torsion bar which has its opposite end solidly fixed to the vehicle chassis, the opposite end of the primary torsion bar, i.e., the end opposite the wheel and control arm, is disposed within the body of a secondary torsion member. The secondary torsion member is a rigid tube, open-ended at one or both ends, installed coaxially with the primary torsion member and overlapping the length of the primary torsion member. A torsion bridge mediates between the primary and secondary torsion members, and is movable to modify a length of the torsion path between the suspension arm and the rigid frame. In some embodiments, the torsion bridge

[0063] Referring now to the figures, and in particular to Figs. 1A-C, components of an exemplary torsion-member assembly are schematically illustrated. Fig. 1A shows a primary torsion member 40 in the form of a rigid elongated cylinder. The primary torsion member 40 can be formed of any suitable material such as, without limitation and not exhaustively, a metal, e.g., spring steel, or a composite material, as can the other components of the torsion-member assembly. Fig. IB illustrates an exemplary secondary torsion member 50, which in the illustrated example includes a rigid tube section 55 and a flange section 57 surrounding an opening 53 at an open end. While shown as a complete circumferential flange in Fig. IB, in some applications (not shown in Fig. IB), the flange 57 is implemented as less than a complete circumferential flange (see, e.g., Fig. 8C), and in some examples can include multiple continuous or discontinuous sections. Fig. 1C illustrates an exemplary torsion bridge 60. In embodiments, a primary torsion member 40 is sized and shaped to fit in and at least partly through an interior 63 of the torsion bridge 60, and the outer surface 62 of the torsion bridge 60 is sized and shaped to fit within the interior 53 of the secondary torsion member 50. While shown respectively in Figs. 1A, IB and 1C as cylindrical, the primary torsion member 40, secondary torsion member 50 and torsion bridge 60 can have polygonal cross-sections or have any other suitable regular or irregular cross-sectional shape.

[0064] Figs. 2A-2D illustrate a torsion-member assembly 100 comprising the primary torsion member 40, secondary torsion member 50, and torsion bridge 60 of Figs. 1 A, IB and 1C, respectively, in an assembled configuration. Arrow 1500 in Fig. 2A indicates the proximal-distal convention used in this disclosure: the proximal direction is the direction towards an end of the torsion-member assembly 100 (or any of its components) closer to the wheel and the suspension arm, while the distal direction is the opposite direction to the proximal direction. Thus, Fig. 2A shows a distal section of the primary torsion member 40 surrounded by the rigid tube section 55 of the secondary torsion member 50, while the proximal end of the primary torsion member 40 is not disposed within the secondary torsion member 50. We note that, according to some embodiments (not shown), the distal end of the rigid tube 55 can be open- ended, and the distal end of the primary torsion member 40 can extend beyond the distal end of the rigid tube 55. The torsion bridge 60 surrounds a portion of the distal section of the primary torsion member 40 that is surrounded by the rigid tube 55, and is itself surrounded by the rigid tube 55. The components are shaped such that the torsion bridge 60 can be displaced longitudinally by a force applied to the torsion bridge 60. For example, the proximal-direction force indicated by arrow 1000 in Fig. 2B is effective to displace the torsion bridge 60 proximally, and the distal-direction force indicated by arrow 1001 in Fig. 2C is effective to displace the torsion bridge 60 distally. Fig. 2D schematically illustrates a cross-section (section A-A in Fig. 2A) of the torsion-member assembly 100.

[0065] Referring now to Figs. 3 and 4, exemplary installations of a torsion-member assembly 100, e.g., the torsion-member assembly 100 of Figs. 2A-D, is schematically illustrated according to embodiments. In both Figs. 3 and 4, a proximal section of the primary torsion member 40 is installed to be fixedly connected to a control arm 80 of suspension system 240 associated with wheel 75. The flange 57 is fixedly connected to a rigid frame 110 at one or more attachment points. The rigid frame 110 can be a rigid frame of a respective VCM, or of the vehicle platform, e.g. the chassis, or the vehicle body). Additionally or alternatively, in some embodiments, the rigid tube section 57 of the secondary torsion member 50 is fixedly attached to a rigid frame 110 of the respective VCM or of the vehicle platform at one or more attachment points. In some embodiments, there is no flange, and the tube section 57 is connected to the rigid frame 110 either directly or via another mechanical connector (not shown). In some embodiments, rigid frame 105 and rigid frame 110 are the same rigid frame.

[0066] The flange is illustrated in Figs. 3 and 4 as being installed on a specific surface of the rigid frame 110 but this is merely for convenience, and the flange 57 can be installed at any suitable point on the rigid frame 110. The control arm 80 is shown as a lower control arm in Fig. 4, but in other examples the control arm can be an upper control arm. In addition to its connection to the primary torsion member 40, a control arm 80 can also be connected via bushings 82 to a rigid frame 105, which can be a rigid frame of a VCM, e.g., a sub-frame, or of a vehicle platform, e.g., a chassis. The bushings 82 tend to somewhat constrain the rotational motion of the control arm 80 relative to the frame 105 and / or influence the stiffness or softness of the ride, and thus can complement the damping function of the torsion-member assembly 100 and of a wheel damper 85. As with conventional torsion bars, the torsion-member assembly 100 provides a damping function similar to that of a vertical ride spring (coil spring). The wheel damper 85 can be provided without a ride spring when used in combination with the torsion-member assembly 100, as shown in Fig. 4. As can be seen in Figs. 3 and 4, the primary torsion member 40 is installed with a proximal end at the wheel 75, e.g., connected to a control arm 80, and from there the primary torsion member 40 extends in a distal direction towards attachment point(s) on the rigid frame 110. The secondary torsion member 50 extends further distally from the attachment point(s) on the rigid frame 110 and continues distally in the same distal direction as the primary torsion member 40.

[0067] According to embodiments, the torsion-member assembly 100 of Figs. 2A-D can ‘bend’ the torsion path of a longer torsion bar into a smaller, e.g., shorter, footprint by placing torsion members 40, 50 in parallel with each other so as to overlap. Torsion is transferred between the torsion members 40, 50 via the torsion bridge 60. A first torsion path, i.e., the path along which the torsion force is propagated, can be understood from Fig. 5, a schematic cross-sectional plan view showing the torsion path 1100 of a compound torsion bar 98 comprising primary and secondary torsion members 40, 50 fixedly attached to each other, i.e., without a slidable torsion bridge. The torsion force, indicated by arrow 1200 in Fig. 5, is typically generated by an up- or down-movement between a wheel 75 relative to a rigid frame 110 of a vehicle, and the resulting rotation of the control arm, e.g., the control arm 80 of Fig. 3 or 4. The torsion is propagated along torsion path 1100, which includes the length of the primary torsion member 40, marked in Fig. 5 as L40, and the length of the secondary torsion member 50, indicated in Fig. 5 as L50. The total length of the torsion path is therefore L40 + L50. In other words, the torsionmember assembly can have the same effective length, for purposes of torsion, as a conventional (single-member) torsion bar having the length L40 + L50. The foregoing ignores, for purposes of illustrating the concept, the fact that the total length of the torsion path could be slightly more or slightly less than L40 + L50. depending on how the torsion members 40, 50 are attached to each other in Fig. 5; moreover, the length and shape of the flange 57 could also affect the derivation of the torsion path 1100. Figures 6A and 6B are respective schematic cross-sectional plan views showing a torsion-member assembly 100 comprising primary and secondary torsion members 40, 50, and a torsion bridge 60, assembled according to embodiments, and schematically illustrate further application of the torsion path concept. In Fig. 6A, the torsion bridge 60 is disposed at the distal end of the torsion-member assembly 100, and the net effect is that the torsion path 1100 is substantially that of fixed-attachment compound torsion bar 98 of Fig. 5, i.e., L40 + L50. The position of the torsion bridge 60 in Fig. 6A represents the longest torsion path attainable by the torsion-member assembly 100 and accordingly the lowest torsion rate, i.e., spring rate. Fig. 6B shows the same torsion-member assembly 100, with the torsion bridge 60 displaced proximally to shorten the torsion path 1100, which increases the torsion rate of the torsion-member assembly 100. As indicated in Fig. 6B, the effective length of the primary torsion member 40 is shortened by the proximal displacement of the torsion bridge 60 from L40 to L40', where L40' = L40 - L10, the length of the torsion bridge displacement. At the same time, the effective length of the secondary torsion member 50 is shortened by the proximal displacement of the torsion bridge 60 from L50 to L50', where L50' = L50 - L10, the length of the torsion bridge displacement. Thus, the effective length of the shortened torsion path 1100 is reduced to L40' + L50', or L40 + L50 - (2 x L10). In other words, the displacement of the torsion bridge 60 has a multiplied (doubled) effect on the length of the torsion path 1100, and similarly is leveraged to have a multiplied effect on the torsion rate of the torsion-member assembly 100. Torsion rate can be understood to change as a function of the length of the torsion path, and thus a displacement of the torsion bridge by a given distance has the same effect on torsion rate as reducing (or extending) the length of a conventional torsion bar or compound torsion bar by twice that distance.

[0068] In embodiments, the torsion bridge 60 can be displaced longitudinally at any time, including before, during and after vehicle journeys, so as to adjust the torsion rate and affect the ride stiffness or softness of ride at any time. As shown schematically in Fig. 6C, longitudinal displacement of the torsion bridge 60 can be accomplished by applying a force, e.g., by a force-transfer system 90 in electrical and / or mechanical communication with the torsion bridge 60, e.g., via connection 92. In one non-limiting example, the force-transfer system 90 includes an electric motor, and the connection 92 includes electrical and / or hydraulic actuators, and any necessary wiring. In another non-limiting example, the force-transfer system 90 includes a hydraulic system and the connection 92 includes hydraulic piping or fittings. In another non-limiting example, the force-transfer system 90 includes a pneumatic system and the connection 92 includes a pneumatic hose. As indicated in Fig. 6C by arrow 900, the displacement of the torsion bridge 60 is effected in both the proximal and distal directions, i.e., so as to adjust the length of the torsion path by increasing it and decreasing it at different times, and thus to decrease or increase the torsion rate at different times. In some embodiments a control system 95 is provided to control the function of the force-transfer system 90, e.g., automatically in response to, e.g., road conditions, environmental conditions, vehicle speed, e.g., or in response to a driver input, or to set or reset a standard setting at a factory, garage, or fleet facility. The control system 95 can be a separate control system dedicated to management of one or more torsion-member assemblies or can be a module or program code within another control system of a VCM or of a vehicle platform.

[0069] In some embodiments, an initial position of the torsion bridge 60 is as shown in Fig. 6A wherein the total length of the torsion path 1100 cannot be extended by longitudinally displacing the torsion bridge 60 distally. In some embodiments, an initial position of the torsion bridge 60 enables extending the total length of the torsion path 1100. In some embodiments, the torsion path is 1100 adjustable to an extent that the adjusted length L40 + L50 - (2 x L10) is longer than the primary torsion member 40 (which has length L40). albeit with a reduced longitudinal footprint. In some the length of the torsion path 1100 is adjustable only to an extent that the adjusted length L40 + L50 - (2 x L10) is longer than the primary torsion member 40.

[0070] As is known in the art, a torsion bar helps define the softness or stiffness of a vehicle suspension system during regular operation of the vehicle, and can be useful in adjusting ride height. As described hereinabove, a torsion-member assembly 100 according to embodiments is effective to dynamically adjust the torsion rate (spring rate) of the suspension, by longitudinally displacing the torsion bridge 60 of the assembly, e.g., to adjust the stiffness or softness of a ride. Additionally or alternative, the torsion-member assembly 100 according to embodiments is actuatable to raise or lower the height of a vehicle at one or more corners, including to kneel the vehicle at one or more wheels. When ‘kneeling’ a vehicle, the vehicle height is lowered, e.g., to curb height, at some or all of its wheels so as to provide a level or at least lower-angle path for entry to and exit from the vehicle. In embodiments, a force-transfer system is adaptable to apply a force, e.g., a torsion, to the secondary torsion member 50 of a torsion-member assembly 100. The torsion is transferred from the secondary torsion member 50 via the torsion bridge 60 to the primary torsion member 40. The twisting force acting on the primary torsion member 40 is effective to adjust the height of the vehicle. In some embodiments, adjusting the height of the vehicle in this manner can include kneeling the vehicle. Referring now to Fig. 6D, a force-transfer system 90 is disposed to apply a torsion force, indicated by arrow 1205, to the secondary torsion member 50 via mechanical and / or electrical connection 92. In some embodiments, a force-transfer system 90 is adapted to longitudinally displace the torsion bridge 60 at a first time as illustrated in Fig. 6C, and to apply a torsion to the secondary torsion member 50, as illustrated in Fig. 6D, at a second time. In an example, the forcetransfer system 90 is configured to control ride stiffness or any other suspension system parameter by dynamically adjusting the torsion rate during operation of the vehicle, and to cause the vehicle to kneel at one or more wheels when the vehicle slows or stops. In some embodiments, a force-transfer system is provided at an individual wheel, as is illustrated in Figs. 6C and 6D, and a separate force-transfer system can be provided at each one of multiple wheels. In some embodiments, a single force-transfer system is provided for a vehicle platform, and various connections, e.g., connections 92, are provided for propagating the longitudinal displacement force 900 and / or the twisting force 1205 to the individual torsionmember assemblies 100 at each wheel. In some embodiments, the torsion-member assembly 100, and / or a suspension system 240 comprising the torsion-member assembly 100, and / or a vehicle platform 150 or vehicle) comprising a plurality of torsion-member assemblies 100 or a plurality of VCMs 120 or suspension systems 240 that respectively comprise the plurality of torsion-member assemblies 100, are configured to be operated in a first mode of operation at a first time and in a second mode of operation at a second time. In embodiments, the first mode of operation includes longitudinally displacing the respective torsion bridge(s) 60 to adjust a length of a torsion path 1100 and thereby change a torsion rate. In embodiments, the second mode of operation includes applying a torsion to the secondary torsion member 50 in order to change a height of the vehicle 150 (or vehicle), including kneeling the vehicle platform 150 at one or more respective wheels. In some embodiments, a torque applied to the secondary torsion member 50, is effective to set or change a torsion rate of the suspension system 240. In a first example, the torsion rate set in this way is an initial torsion rate that is set at, or proximate to, an installation of the torsion-member assembly. In a second example, the torsion rate set in this way is a ‘journey’ torsion rate which is set at, or proximate to, a beginning of a journey. In a third example, the torsion rate set in this way is a “driver” torsion rate set by or for a specific driver. In a non-limiting example, setting the torsion rate in this way is carried out at the second time, or at a third time. In some embodiments, the torque (or torsion) effective to set a torsion rate is a first torque, and application of a second torque having a larger absolute value than the first torque is effective to change a height of the vehicle platform.

[0071] Figs. 7A-C illustrate various features of a primary torsion member 40 according to embodiments. As can be seen in Fig. 7A, a lengthwise segment 41 at or near the distal end of the primary torsion member 40 is adapted for enabling longitudinal displacement of the torsion bridge 60 relative to the primary torsion member 40 when assembled and actuated. In the example of Fig. 7B, the lengthwise segment 41 includes a spline. In the example of Fig. 7C, the lengthwise segment 41 includes a threaded section. Figs. 8A-C illustrate certain features of a secondary torsion member 50 according to embodiments. As can be seen in the schematic crosssection drawing of Fig. 8A, the tube portion 55 of the secondary torsion member 50 includes an internal lengthwise segment 51 adapted for enabling longitudinal displacement of the torsion bridge 60 relative to the secondary torsion member 50 when assembled and actuated. In the example of Fig. 8B, the lengthwise segment 51 includes a spline. Fig. 8C illustrates a non-limiting example of a secondary torsion member 50 including an internal lengthwise segment 51 adapted for enabling longitudinal displacement of the torsion bridge 60, in which the flange 57 is not a complete circumferential flange surrounding the open proximal end of the rigid tube section 55. Figs. 9A-B illustrate certain features of a torsion bridge 60 according to embodiments. Fig. 9A shows a schematic cross-section drawing of a torsion bridge 60. Fig. 9B illustrates a non-limiting example of a torsion bridge 60 including an internal lengthwise segment 61 and an external lengthwise segment 62, which are adapted for enabling longitudinal displacement of the torsion bridge 60 between the primary torsion member 40 and the rigid tube section 55 of the secondary torsion member 50, respectively. In the non-limiting example of Fig. 9B, each of the internal lengthwise segment 61 and the external lengthwise segment 62 includes a spline.

[0072] Figs. 10A and 10B show examples of a vehicle platform 150 comprising a rigid frame 110 corresponding to the chassis of the vehicle platform 150. Fig. 10A shows a vehicle platform 150 comprising four VCMs 120 as disclosed herein, e.g., as in Fig. 11, while Fig. 10B shows a vehicle platform 150 which does not employ VCMs. Either of the vehicle platforms 150 of Figs. 10B may include plurality of torsion-member assemblies 100, and may additionally include comprising a forcetransfer system 90 operative to apply a force to longitudinally displace at least one torsion bridge 60 of a respective torsion-member assembly 100 of the plurality of torsion-member assemblies 100. Additionally or alternatively, the force-transfer system 90 can be configured to apply, to the secondary torsion member 50 of the torsion-member assembly 100, a torque that causes the kneeling of the vehicle comprising the vehicle platform 150 at one or more wheels 75. In some embodiments, the vehicle platform 150 additionally includes comprising a controller 95 configured to regulate the longitudinal displacement and / or torsion applied by the force-transfer system 90.

[0073] Fig. 11 shows a VCM 120 comprising a plurality of subsystems mediating between a sub-frame 161 and a wheel 75, the plurality of subsystems including the suspension subsystem 240 disclosed herein and one or more (or two or more, or all three, depending on specific use cases) of a steering system 200, a drive system 180, and a braking system 176. The rigid frame 110 can comprise all or part of the subframe 161.

[0074] In some embodiments, a vehicle platform 150 includes a plurality of VCMs 120, wherein each VCM 120 is mountable to and non-destructively dismountable from a vehicle platform 150. In some embodiments, the VCM includes a forcetransfer system 90 operative to apply a force 900 to longitudinally displace the torsion bridge 60 as illustrated, e.g., in Fig. 6C, and / or to apply a torsion 1205 to the secondary torsion member 50 as illustrated, e.g., in Fig. 6D. In some embodiments, a vehicle platform 150 comprises a plurality of torsion-member assemblies 100 according to any of the embodiments disclosed herein, including embodiments that do not require implementation of VCMs. In such embodiments, the vehicle platform 150 may include a force-transfer system 90 operative to apply a respective force 900 to longitudinally displace each of one or more torsion bridges 60, and / or to apply a respective torsion 1205 to each of one or more secondary torsion members 50, of respective suspension systems 240 at the various wheels 75 of the vehicle platform 150. The vehicle platform 150 may also include a controller 95 configured to regulate the longitudinal displacement and / or torsion of any or all of the torsion bridges 60 and / or secondary torsion members 50, respectively.

[0075] Referring now to Fig. 12, a method is disclosed for operating a vehicle comprising any of the vehicle platforms 150 described herein. As illustrated by the flow chart in Fig. 12, the method comprises at least Steps SOI and S02.

[0076] Step SOI includes applying a force, e.g., the force indicated by arrow 900 in Fig. 6C, to longitudinally displace the torsion bridge 60 so as to change a torsion rate of the respective torsion-member assembly 100.

[0077] Step S02 includes applying a torque to the secondary torsion member 50 e.g., the force indicated by arrow 1205 in Fig. 6D, to kneel the vehicle 150 at a respective wheel.

[0078] According to embodiments, Step SOI is carried out at a first time, and Step S02 is carried out at a second time. The ordinal adjectives ‘first’ and ‘second’ are used only to distinguish between the two times and not to imply chronological order.

[0079] Referring now to Fig. 13, a method is disclosed for operating a vehicle, wherein the vehicle comprises, for at least one wheel thereof, a suspension system 240 that includes a respective torsion-member assembly 100 comprising a primary torsion member 40, a secondary torsion member 50 comprising a tubular portion 55 that surrounds a first section of the primary torsion member 40, and a torsion bridge 60 surrounding a lengthwise portion of the first section of the primary torsion member 40, e.g., at least a lengthwise distal segment 41 of the first section, and surrounded by the tubular portion 55 of the secondary torsion member 50. As illustrated by the flow chart in Fig. 13, the method comprises at least Steps Sil and S12.

[0080] Step Sil includes applying a force, e.g., the force indicated by arrow 900 in Fig. 6C, to longitudinally displace the torsion bridge 60 so as to change a torsion rate of the respective torsion-member assembly 100. Step S12 includes applying a torque to the secondary torsion member 50, e.g., the force indicated by arrow 1205 in Fig. 6D, to kneel the vehicle 150 at a respective wheel.

[0081] According to embodiments, Step Sil is carried out at a first time, and Step S12 is carried out at a second time. The ordinal adjectives ‘first’ and ‘second’ are used only to distinguish between the two times and not to imply chronological order.

[0082] Referring now to Fig. 14, a method is disclosed for of setting a torsion rate of a suspension system 240 comprising a torsion-member assembly 100 according to any of the embodiments disclosed herein. In some embodiments, the suspension system 240 comprises a force-transfer system 90 configured to apply the torque, e.g., the torque related to the torsion force indicated by arrow 1205 in Fig. 6D, which effective to set the torsion rate as described hereinabove. As illustrated by the flow chart in Fig. 14, the method comprises at least Step S21.

[0083] Step S21 includes applying a torque, e.g., by the force-transfer system 90, to the secondary torsion member 50 so as to set a torsion rate.

[0084] Referring now to Fig. 15, a method is disclosed for operating a vehicle.

[0085] According to the method, the vehicle 150 comprises a plurality of torsion-member assemblies 100 each comprising (i) a respective primary torsion member 40 and a respective secondary torsion member 50, each respective secondary torsion member 50 comprising a tubular portion 55 surrounding a first section of the respective primary torsion member 40, and (ii) a respective longitudinally displaceable, annular torsion bridge 60 mediating between a lengthwise portion of the first section of the respective primary torsion member 40 and the tubular portion 55. As illustrated by the flow chart in Fig. 15, the method comprises at least Step S31.

[0086] Step S31 includes applying a force, e.g., the force indicated by arrow 900 in Fig. 6C, to longitudinally displace a respective torsion bridge 60 of one of the torsionmember assemblies 50 of the vehicle so as to change a torsion rate of said one of the torsion-member assemblies 50. In some embodiments, longitudinally displacing the respective torsion bridge 60 includes causing the torsion bridge 60 to slide longitudinally along a splined path. In some embodiments, longitudinally displacing the respective torsion bridge 60 is effected using one or more of electric actuation, hydraulic actuation, and pneumatic actuation, e.g., by the force-transfer system 90. Referring now to Fig. 16, a method is disclosed for operating a vehicle. According to the method, the vehicle 150 comprises a plurality of torsion-member assemblies 100 each comprising (i) a respective primary torsion member 40 and a respective secondary torsion member 50, each respective secondary torsion member 50 comprising a tubular portion 55 surrounding a first section of the respective primary torsion member 40, and (ii) a respective longitudinally displaceable, annular torsion bridge 60 mediating between a lengthwise portion of the first section of the respective primary torsion member 40 and the tubular portion 55. As illustrated by the flow chart in Fig. 16, the method comprises at least Step S41.

[0087] Step S41 includes applying a torque to the respective secondary torsion members 50 of one or more torsion-member assemblies 100 to change a height of the vehicle 150. In some embodiments, applying of the torque to the respective secondary torsion members 50 is effective to kneel the vehicle 150.

[0088] The present invention has been described using detailed descriptions of embodiments thereof that are provided by way of example and are not intended to limit the scope of the invention. The described embodiments comprise different features, not all of which are required in all embodiments of the invention. Some embodiments of the present invention utilize only some of the features or possible combinations of the features. Variations of embodiments of the present invention that are described and embodiments of the present invention comprising different combinations of features noted in the described embodiments will occur to persons skilled in the art to which the invention pertains.

[0089] In the description and claims of the present disclosure, each of the verbs, "comprise", "include" and "have", and conjugates thereof, are used to indicate that the object or objects of the verb are not necessarily a complete listing of members, components, elements or parts of the subject or subjects of the verb. As used herein, the singular form "a", "an" and "the" include plural references unless the context clearly dictates otherwise. For example, the term "a marking" or "at least one marking" may include a plurality of markings.

Claims

CLAIMS1. A torsion-member assembly for a suspension system, the assembly comprising: a. a primary torsion member; b. a secondary torsion member comprising a tubular portion, the tubular portion surrounding a first section of the primary torsion member; and c. a torsion bridge surrounding a lengthwise portion of the first section of the primary torsion member and surrounded by the tubular portion of the secondary torsion member, the torsion bridge being in displaceable communication with, and longitudinally displaceable relative to, both the tubular portion of the secondary torsion member and the first section of the primary torsion member, wherein a longitudinal displacement of the torsion bridge is effective to adjust a length of a torsion path of the assembly, thereby changing a torsion rate of the assembly.

2. The torsion-member assembly of claim 1, wherein the primary torsion member is configured for fixed attachment of a second section thereof to a control arm of the suspension system.

3. The torsion-member assembly of either one of claims 1 or 2, wherein the secondary torsion member is configured for fixed attachment to a rigid frame of a vehicle platform.

4. The torsion-member assembly of claim 3, wherein the secondary torsion member is configured for fixed attachment to the rigid frame at multiple attachment points.

5. The torsion-member assembly of any one of claims 1 to 4, wherein the primary torsion member is configured to extend from a control arm of the suspension system in a first direction, and the secondary torsion member is configured to extend from a rigid frame of a vehicle platform in the same first direction.

6. The torsion-member assembly of any one of claims 1 to 5, wherein the length of the torsion path of the assembly is adjustable to an extent that the adjusted length is longer than the primary torsion member.

7. The torsion-member assembly of any one of claims 1 to 6, wherein the length of the torsion path of the assembly is adjustable only to an extent that the adjusted length is longer than the primary torsion member.

8. The torsion-member assembly of any one of claims 1 to 7, wherein the longitudinal displacement includes sliding longitudinally.

9. The torsion-member assembly of claim 8, wherein the sliding longitudinally is along a splined path.

10. The torsion-member assembly of any one of claims 1 to 9, wherein the torsion-member assembly is configured such that the longitudinal displacement is effected using one or more of electric actuation, hydraulic actuation, and pneumatic actuation.

11. The torsion-member assembly of any one of claims 3 to 10, wherein the secondary torsion member and the control arm are attached to the same rigid frame.

12. The torsion-member assembly of any one of claims 3 to 11, wherein the rigid frame is a subframe of a vehicle corner module (VCM) that is mountable to and dismountable from the vehicle platform, the VCM comprising a wheelhub assembly and a plurality of systems mediating between the sub-frame and the wheel-hub assembly, the plurality of systems comprising a suspension system and at least one of a drive system, a steering system, and a braking system.

13. The torsion-member assembly of any one of claims 3 to 11, wherein the rigid frame is a chassis of the vehicle platform or a part thereof.

14. A suspension system for a vehicle platform, comprising a torsion-member assembly according to any one of claims 3 to 13.

15. The suspension system of claim 14, additionally comprising a force-transfer system configured to apply, to the secondary torsion member of the torsion-member assembly, a torque that causes the suspension system to kneel the vehicle platform.

16. A vehicle corner module (VCM) that is mountable to and non-destructively dismountable from a vehicle platform, the VCM comprising a sub-frame including a rigid frame, a wheel-hub assembly, and a plurality of systems mediating between the sub-frame and the wheel-hub assembly, the plurality of systems comprising the suspension system of either one of claims 14 or 15 and at least one of a drive system, a steering system, and a braking system.

17. The VCM of claim 16, additionally comprising a force-transfer system operative to apply a force to longitudinally displace the torsion bridge.

18. A vehicle platform comprising a plurality of VCMs according to either one of claims 16 or 17.

19. A vehicle platform comprising a plurality of torsion-member assemblies according to claim 13.

20. The vehicle platform of either one of claims 18 or 19, additionally comprising a force-transfer system operative to apply a force to longitudinally displace at least one torsion bridge of a respective torsion-member assembly of the plurality of torsion-member assemblies.

21. The vehicle platform of any one of claims 18 to 20, comprising a controller configured to regulate the longitudinal displacement.

22. A suspension system for kneeling a vehicle, the suspension system comprising a torsion-member assembly according to any one of claims 1 to 13, and a force-transfer system configured to apply, to the secondary torsion member of the torsion-member assembly, a torque that causes the suspension system to kneel the vehicle.

23. A method of operating a vehicle comprising the vehicle platform of any one of claims 18 to 21, the method comprising: at a first time, applying a force to longitudinally displace a torsion bridge so as to change a torsion rate of a respective torsion-member assembly; and, at a second time, applying a torque to a secondary torsion member to kneel the vehicle at a respective wheel.

24. A suspension system for a wheel assembly of a vehicle, the suspension system comprising: a. a telescopic damper configured to mediate between respective sprung and unsprung portions of the wheel assembly; b. a torsion-member assembly comprising (i) a primary torsion member, (ii) a secondary torsion member comprising a tubular portion, the tubular portion surrounding a first section of the primary torsion member, and (iii) a torsion bridge surrounding a lengthwise portion of the first section of the primary torsion member and surrounded by the tubular portion of the secondary torsion member, the torsion bridge being in displaceable communication with, and longitudinally displaceable relative to, both the tubular portion of the secondary torsion member and the first section of the primary torsion member; and c. a force-transfer system operative to apply a force to change one or more parameters of the suspension system, wherein: i. in a first mode of operation, the application of the force by the force-transfer system is effective to change a torsion rate of the assembly, and ii. in a second mode of operation, the application of the force by the force-transfer system is effective to cause the suspension system to kneel the vehicle platform at the wheel assembly.

25. The suspension system of claim 24, wherein the changing of the torsion rate in the first mode of operation is by adjusting a length of a torsion path of the torsion-member assembly.

26. The suspension system of either one of claims 24 or 25, wherein the kneeling of the vehicle platform in the second mode of operation is by applying a torque to the secondary torsion member.

27. The suspension system of any one of claims 24 to 26, wherein the secondary torsion member is fixedly attached to a rigid frame of the vehicle.

28. The suspension system of claim 27, wherein the primary torsion member extends from a control arm of the suspension system in a first direction, and the secondary torsion member extends from the rigid frame in the same first direction.

29. The suspension system of claim 28, wherein the secondary torsion member and the control arm are attached to the same rigid frame.

30. The suspension system of any one of claims 27 to 29, wherein the rigid frame is a subframe of a vehicle corner module (VCM) that is mountable to and dismountable from the vehicle, the VCM comprising a wheel-hub assembly and a plurality of systems mediating between the sub-frame and the wheel-hub assembly, the plurality of systems comprising the suspension system and at least one of a drive system, a steering system, and a braking system.

31. The suspension system of any one of claims 27 to 29, wherein the rigid frame is a chassis of the vehicle or a part thereof.

32. A method of operating a vehicle, the vehicle comprising, for at least one wheel thereof, a suspension system that includes a respective torsion-member assembly comprising a primary torsion member, a secondary torsion member comprising a tubular portion that surrounds a first section of the primary torsion member, and a torsion bridge surrounding a lengthwise portion of the first section of the primary torsion member and surrounded by the tubular portion of the secondary torsion member, the method comprising: a. at a first time, applying a force to longitudinally displace the torsion bridge so as to change a torsion rate of the respective torsion-member assembly; and b. at a second time, applying a torque to the secondary torsion member to kneel the vehicle at the respective wheel.

33. A torsion-member assembly for a suspension system, the assembly comprising:a. a primary torsion member; b. a secondary torsion member comprising a tubular portion, the tubular portion surrounding a first section of the primary torsion member; and c. a torsion bridge surrounding a lengthwise portion of the first section of the primary torsion member and surrounded by the tubular portion of the secondary torsion member, the torsion bridge being in displaceable communication with, and longitudinally displaceable relative to, both the tubular portion of the secondary torsion member and the first section of the primary torsion member, wherein an application of a torque to the secondary torsion member is effective to set a torsion rate.

34. The torsion-member assembly of claim 33, wherein the torsion rate is an initial torsion rate set at or proximate to an installation of the torsion-member assembly.

35. The torsion-member assembly of claim 33, wherein the torsion rate is a journey torsion rate set at or proximate to a beginning of a journey.

36. The torsion-member assembly of claim 33, wherein the torsion rate is a driver torsion rate set by or for a specific driver.

37. The torsion-member assembly of any one of claims 33 to 36, wherein the primary torsion member is configured for fixed attachment of a second section thereof to a control arm of the suspension system, and the secondary torsion member is configured for fixed attachment to a rigid frame of a vehicle platform.

38. The torsion-member assembly of any one of claims 33 to 37, wherein the primary torsion member is configured to extend from a control arm of the suspension system in a first direction, and the secondary torsion member is configured to extend from a rigid frame of a vehicle platform in the same first direction.

39. The torsion-member assembly of any one of claims 33 to 38, wherein the longitudinal displacement includes sliding longitudinally along a splined path.

40. The torsion-member assembly of any one of claims 33 to 39, wherein the torsion-member assembly is configured such that the longitudinal displacement is effected using one or more of electric actuation, hydraulic actuation, and pneumatic actuation.

41. The torsion-member assembly of any one of claims 37 to 40, wherein the rigid frame is a subframe of a vehicle corner module (VCM) that is mountable to and dismountable from the vehicle platform, the VCM comprising a wheelhub assembly and a plurality of systems mediating between the sub-frame and the wheel-hub assembly, the plurality of systems comprising a suspension system and at least one of a drive system, a steering system, and a braking system.

42. The torsion-member assembly of any one of claims 37 to 40, wherein the rigid frame is a chassis of the vehicle platform or a part thereof.

43. A suspension system for a vehicle platform, comprising the torsion-member assembly of any one of claims 33 to 42.

44. The suspension system of claim 43, additionally comprising a force-transfer system configured to apply said torque effective to set the torsion rate.

45. A vehicle corner module (VCM) that is mountable to and non-destructively dismountable from a vehicle platform, the VCM comprising a sub-frame including a rigid frame, a wheel-hub assembly, and a plurality of systems mediating between the sub-frame and the wheel-hub assembly, the plurality of systems comprising the suspension system of either one of claims 43 or 43 and at least one of a drive system, a steering system, and a braking system.

46. The VCM of claim 45, additionally comprising a force-transfer system operative to apply a force to longitudinally displace the torsion bridge.

47. A vehicle platform comprising a plurality of VCMs according to either one of claims 45 or 46.

48. The vehicle platform of claim 47, wherein the torque effective to set a torsion rate is a first torque, and application of a second torque having a largerabsolute value than the first torque is effective to change a height of the vehicle platform.

49. The vehicle platform of claim 48, wherein changing the height is effective to kneel the vehicle.

50. A method of setting a torsion rate of the suspension system of either one of claims 43 or 44, the method comprising applying a torque to the secondary torsion member so as to set a torsion rate.

51. A method of operating a vehicle, the vehicle comprising a plurality of torsionmember assemblies each comprising (i) a respective primary torsion member and a respective secondary torsion member, each respective secondary torsion member comprising a tubular portion surrounding a first section of the respective primary torsion member, and (ii) a respective longitudinally displaceable, annular torsion bridge mediating between a lengthwise portion of said first section and said tubular portion, the method comprising: applying a force to longitudinally displace a respective torsion bridge of one of the torsion-member assemblies so as to change a torsion rate of said one of the torsion-member assemblies.

52. The method of claim 51, wherein the longitudinally displacing of the respective torsion bridge includes causing the torsion bridge to slide longitudinally along a splined path.

53. The method of claim 52, wherein the longitudinally displacing of the respective torsion bridge is effected using one or more of electric actuation, hydraulic actuation, and pneumatic actuation.

54. A method of operating a vehicle, the vehicle comprising a plurality of torsionmember assemblies each comprising (i) a respective primary torsion member and a respective secondary torsion member, the respective secondary torsion member comprising a tubular portion surrounding a first section of the respective primary torsion member, and (ii) a respective longitudinally displaceable, annular torsion bridge mediating between a lengthwise portion of said first section and said tubular portion, the method comprising: applying atorque to the respective secondary torsion members of one or more torsionmember assemblies to change a height of the vehicle.

55. The method of claim 54, wherein the applying of the torque to the respective secondary torsion members is effective to kneel the vehicle.

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