EP4735278A1

EP4735278A1 - Chassis for a personal mobility vehicle or a recreational vehicle

Info

Publication number: EP4735278A1
Application number: EP24829645.1A
Authority: EP
Inventors: Ashley Campbell Daff; Rhys Dean MAIN
Original assignee: Red Milawa Pty Ltd
Current assignee: Red Milawa Pty Ltd
Priority date: 2023-06-30
Filing date: 2024-06-28
Publication date: 2026-05-06
Also published as: AU2024309323A1; WO2025000052A1

Abstract

The present disclosure provides a chassis for a personal mobility vehicle, such as a wheelchair, for an individual with a disability The chassis comprises: a base frame for supporting a seat of the personal mobility vehicle thereon; a front subframe with at least one ground-engaging front wheel, the front subframe being connected to the base frame via a front suspension for resilient movement relative to the base frame; and a rear subframe having at least one ground-engaging rear wheel, the rear subframe being connected to the base frame via a rear suspension for resilient movement relative to the base frame. The front subframe and the rear subframe are separately and independently pivotally connected to the base frame for pivoting movement relative to the base. To this end, the front subframe is pivotally connected to the base frame via a first pivot joint and the rear subframe is pivotally connected to the base frame via a second pivot joint.

Description

CHASSIS FOR A PERSONAL MOBILITY VEHICLE OR A RECREATIONAL VEHICLE

Technical Field

[0001] The present disclosure relates generally to a chassis for a vehicle, such as a personal mobility vehicle or a recreational vehicle. In this context, it will be noted that personal mobility vehicles include wheelchairs, such as motorised wheelchairs, for individuals with a disability. This disclosure particularly relates to a chassis for a personal mobility vehicle, such as a wheelchair, or a recreational vehicle, and to a personal mobility vehicle or a recreational vehicle that incorporates such a chassis.

[0002] As mentioned above, the chassis of this disclosure is especially suited for use in a personal mobility vehicle, such as a motorised wheelchair, and it will be convenient to describe the chassis in this exemplary context. It will be appreciated, however, that the chassis of the disclosure is not limited to this particular use or application, and it may also be employed in a range of other types of vehicles, such as mobility scooters, quad bikes, golf carts, and other such recreational vehicles.

Background Art

[0003] Personal mobility vehicles, such as wheelchairs, for individuals suffering a disability typically include a seat for the user mounted on a rolling chassis. Modern personal mobility vehicles are electrically powered and often have a user control interface or control system provided on or near the seat, such as in or adjacent to an armrest of the seat, for easy access and operation of the vehicle functionalities by the user. The rolling chassis will typically include a pair of front wheels and a pair of rear wheels, at least some of which wheels are designed to be driven by an electric motor. Accordingly, vehicle functionalities which are operable via the user control interface or control system provided on or near the armrest of the seat may include the driven movement, direction and/or steering of the wheels, adjustment of the seat position, adjustment of the armrest positions, adjustment of a headrest position, and adjustment of a leg rest position.

[0004] Personal mobility vehicles, such as wheelchairs, are typically configured to traverse generally smooth terrains, such as are found indoors or in paved outdoor areas. Some users, however, also require personal mobility vehicles to navigate rougher terrain, such as unsurfaced roads or tracks. Rougher terrain of this sort can create issues for conventional personal mobility vehicles that impact stability and obstacle negotiation. Personal mobility vehicles with an “all-terrain” configured chassis are specially adapted for navigating larger obstacles while maintaining the stability of the user / occupant. Such stability is a particularly important feature for a wheelchair as many users lack sufficient sensory perceptions or muscle I motor control to maintain a sense of balance or to react to movements of the wheelchair themselves. Many all-terrain wheelchairs utilize larger pneumatic tyres to maintain ground clearance and improve off road capability. These arrangements, however, typically employ a conventional wheelchair chassis. Jolts and rebound movements of the wheelchair that occur in response to obstacles encountered while navigating uneven terrain can then transfer undesired impulses and movements to the user.

[0005] In view of the above, therefore, it would be desirable to provide a new and improved chassis for a personal mobility vehicle, especially for a wheelchair, for an individual with a disability. It would also be desirable to provide a new and improved chassis for a recreational vehicle, such as a motorised scooter, a quad bike, a golf cart, or other motorised cart, as well as a vehicle incorporating such a new chassis. It would be particularly helpful to provide a chassis for a personal mobility vehicle or recreational vehicle that can accommodate large suspension movements and that can maintain stability while navigating uneven or rough terrain.

Summary

[0006] According to one aspect, the present disclosure provides a chassis for a personal mobility vehicle or a recreational vehicle, the chassis comprising: a base frame for supporting a seat and/or for supporting a user of the vehicle seated there-on; and a front subframe for supporting at least one ground-engaging front wheel of the vehicle, wherein the front subframe is connected to the base frame for resilient movement relative to the base frame via a pivot joint.

[0007] According to another aspect, the present disclosure provides a chassis for a personal mobility vehicle or a recreational vehicle, the chassis comprising: a base frame for supporting a seat and/or a user of the vehicle seated thereon; and a rear subframe for supporting at least one ground-engaging rear wheel of the vehicle, wherein the rear subframe is connected to the base frame for resilient movement relative to the base frame via a pivot joint. [0008] In this way, the chassis of the disclosure may provide for an independently acting, pivotally mounted front subframe and/or for an independently acting, pivotally mounted rear subframe. This configuration is designed to provide enhanced ground adaptation and improved traction in the vehicle, especially over uneven or rough terrain. As is clear from the above, either or both of the front subframe and the rear subframe of the chassis may be connected to the base frame for resilient movement relative to the base frame via a pivot joint. In the case of the front subframe, its pivot joint connection will be identified as a first pivot joint. For the rear subframe, its pivot joint connection will be identified as a second pivot joint.

[0009] In an embodiment of the disclosure, the front subframe is connected to the base frame for resilient pivotal movement relative to the base frame about the first pivot joint, wherein resilience is provided to the pivotal movement of the front sub-frame via a front suspension. Similarly, in an embodiment, the rear subframe is connected to the base frame for resilient pivotal movement relative to the base frame about the second pivot joint, wherein resilience is provided to the pivotal movement of the rear subframe via a rear suspension. The front suspension and the rear suspension will each typically include a spring and damper arrangement. With an appropriately selected suspension configuration, the independently acting front and rear subframes will provide for smooth travel (i.e. , a smooth Tide’) and improved traction over uneven or rough terrain.

[0010] In the present disclosure, it will be appreciated by persons skilled in the art that the term “chassis” refers to a load-bearing frame for structurally supporting the wheelchair and includes the suspension and optionally also the wheels. As such, the chassis may also be understood as a “chassis assembly”. The wheels of the chassis will preferably include pneumatic tires and, by providing good suspension and ground adaptation, the chassis may also facilitate use of higher tyre pressures and a resultant lower rolling resistance. This, in turn, can provide for an improved operational range of the vehicle. Each of the base frame, front subframe, and rear subframe of the chassis typically comprises a substantially rigid structure and these are interconnected, as noted above, by pivot connections and a suitable suspension or resilient bearing assembly to provide the desired ride comfort.

[001 1] In an embodiment of the disclosure, the first pivot joint is located on the base frame rearward of the second pivot joint and the second pivot joint is located on the base frame forward of the first pivot joint. In this context, the first pivot joint is typically provided on a rear part of the base frame and the second pivot joint is typically provided on a front part of the base frame. Preferably, the first pivot joint and the second pivot joint are provided generally centrally of the base frame; e.g., along a central plane of the base frame.

[0012] In an embodiment, the front subframe includes a transverse part adapted to support a pair of ground-engaging front wheels at its laterally opposite sides, and a longitudinal part that extends rearwardly of the transverse part. An end region of the rearwardly extending longitudinal part is pivotally connected to the base frame via the first pivot joint. In this way, the transverse part of the front subframe preferably comprises at least one transverse member for supporting one of the ground-engaging front wheels at an end thereof, and the longitudinal part of the front subframe preferably comprises an elongate member substantially rigidly connected with the transverse part that extends rearwardly, and optionally generally centrally, on the base frame. An end of the elongate longitudinal member is then pivotally connected to the base frame via the first pivot joint. The front suspension may be provided between the base frame and the transverse part of the front subframe. The front subframe, and particularly the transverse part and longitudinal part combined, is therefore preferably formed as an integral or unitary, substantially rigid structure.

[0013] In an embodiment, the rear subframe comprises a transverse part adapted to support a pair of ground-engaging rear wheels at its laterally opposite sides, and a longitudinal part that extends forwardly of the transverse part. An end region of the forwardly extending longitudinal part is pivotally connected to the base frame via the second pivot joint. In this regard, the transverse part of the rear subframe may include at least one transverse member for supporting one of the ground-engaging rear wheels at an end thereof. The longitudinal part of the rear subframe preferably comprises an elongate member substantially rigidly connected with the transverse part that extends forwardly, and desirably generally centrally, on the base frame. An end of the forwardly extending elongate member is pivotally connected to the base frame via the second pivot joint. The rear suspension may be provided between the base frame and the transverse part of the rear subframe. The rear subframe, and particularly the transverse part and the longitudinal part combined, is therefore preferably formed as an integral or unitary, substantially rigid structure. [0014] In an embodiment, the first pivot joint is configured for pivoting movement of the front subframe relative to the base frame about at least one, or both, of a transverse axis of the base frame and a longitudinal axis of the base frame. Thus, the first pivot joint is configured to pivot about a transverse axis of the base frame and/or about a longitudinal axis of the base frame. In a similar way, the second pivot joint is configured for pivoting movement of the rear subframe relative to the base frame about at least one, or both, of a transverse axis of the base frame and a longitudinal axis of the base frame. The second pivot joint is thus configured to pivot about a transverse axis of the base frame and/or about a longitudinal axis of the base frame. It will be appreciated that the term “transverse” as used herein in respect of the chassis is understood to refer to a direction or axis across a width of the chassis between the left-hand side and right-hand side of the vehicle. The term “longitudinal” as used herein in respect of the chassis is understood to refer to a direction or axis between the front and rear of the vehicle, i.e., relative to forward or rearward directions of travel.

[0015] In an embodiment of the disclosure, the rear sub-frame has an electric motor associated with each rear wheel. Each rear wheel is a driven wheel, and the rear subframe may include a pair of electric motors mounted on its transverse part, with each electric motor being connected to drive a respective rear wheel. In an optional configuration, each front wheel may also be a driven wheel. In this case, the front subframe may include a pair of electric motors mounted on its transverse part, with each electric motor connected to drive a respective one of front wheels.

[0016] In an embodiment of the disclosure, the front sub-frame includes a motor, especially an electric motor, associated or connected with each front wheel via a steering mechanism. In this regard, the steering mechanism may include linkages, such as steering tie rods, which interconnect the motor with the front wheels, such that operation of the motor may control the direction of the front wheels. To this end, the motor is preferably an electric servo motor or stepper motor.

[0017] In an embodiment of the disclosure, the base frame includes at least one recess or compartment for holding a battery for electrically powering the vehicle. In this way, the battery may be securely integrated in the frame of the chassis upon which the seat is mounted. In a preferred embodiment, the base frame includes two recesses or compartments for holding a respective battery for electrically powering the vehicle, the two recesses or compartments being provided on laterally opposite sides of the base frame. This arrangement provides for both a large battery capacity and also accommodates the relatively high mass of the two batteries in a position offering a low centre of mass for the vehicle.

[0018] According to yet another aspect, the present disclosure provides a chassis for a personal mobility vehicle or a recreational vehicle, the chassis comprising: a base frame for supporting a seat and/or user of the vehicle seated upon it; a front subframe having at least one ground-engaging front wheel, the front subframe being resiliency connected to the base frame via a suspension for movement relative to the base frame; and a rear subframe having at least one ground-engaging rear wheel, the rear subframe being resiliency connected to the base frame via a suspension for movement relative to the base frame; wherein at least one of the front subframe and the rear subframe, and desirably both of them, is/are separately and independently pivotally connected to the base frame for pivoting movement relative to the base frame.

[0019] According to a further aspect, the present disclosure provides a chassis for a personal mobility vehicle, e.g., for an individual with a disability, or a recreational vehicle, the chassis comprising: a base frame for supporting a seat and/or a user of the vehicle thereon; and a rear subframe for mounting at least one ground-engaging rear wheel of the vehicle, wherein the rear subframe is connected to the base frame for resilient movement relative to the base frame via a pivot joint. In an embodiment, the chassis further comprises a front subframe for mounting at least one ground-engaging front wheel of the vehicle. The front subframe is connected to the base frame for resilient movement relative to the base frame via a pivot joint.

[0020] In an embodiment, each of the front subframe and the rear subframe is configured for pivoting movement relative to the base frame about one, or both, of a transverse axis of the base frame and a longitudinal axis of the base frame. In this regard, the front subframe is pivotally connected to the base frame via a first pivot joint, and the rear subframe is pivotally connected to the base frame via a second pivot joint.

[0021 ] As noted above, in an embodiment of the disclosure, the front subframe includes: a transverse member on which the at least one ground-engaging front wheel is mounted, and a longitudinal member that is rigidly connected with the transverse member and extends rearwardly, and preferably generally centrally, on the base frame, wherein a rearward end of that longitudinal member is pivotally connected to the base frame via the first pivot joint.

[0022] As noted above, in an embodiment of the disclosure, the rear subframe includes: a transverse member on which the at least one ground-engaging rear wheel is mounted, and a longitudinal member that is rigidly connected with the transverse member and extends rearwardly, and preferably generally centrally, on the base frame, wherein a forward end of that longitudinal member is pivotally connected to the base frame via the second pivot joint.

[0023] According to yet a further aspect, the disclosure provides a personal mobility vehicle, such as a wheelchair, for an individual with a disability, wherein the personal mobility vehicle comprises a chassis according to any one of the embodiments of the disclosure described above.

[0024] According to still a further aspect, this disclosure provides a recreational vehicle, such as a scooter, a quad bike, or a golf cart, wherein the vehicle comprises a chassis according to any one of the embodiments of the disclosure described above.

[0025] It will be appreciated that the vehicle of the disclosure may have a typical or standard four-wheel configuration with a front subframe supporting two front wheels, and a rear subframe supporting two rear wheels. Alternatively, however, the vehicle of the disclosure may have three-wheel configuration, e.g., with the front subframe having a single front wheel and a rear subframe having two rear wheels, or with the front subframe having two front wheels and the rear subframe having a single rear wheel. Other wheel configurations may also be contemplated.

Brief Description of the Drawings

[0026] For a more complete understanding of the invention of the disclosure and the advantages thereof, exemplary embodiments are explained in more detail in the following description with reference to the accompanying drawing figures, in which like reference signs designate like parts and in which:

Fig. 1 is an upper perspective view of a chassis according to one embodiment of the present disclosure; Fig. 2 is a lower perspective view of the chassis seen in Fig. 1 with the left front wheel and its mount and drive motor removed;

Fig. 3 is a cross-sectional perspective view of the chassis shown in Fig. 1 ;

Fig. 4 is a cross-sectional perspective view of the chassis shown in Fig. 1 , with each of the front subframe and the rear subframe shaded differently, both to identify them clearly and to distinguish them from one another and from the base frame, which is unshaded;

Fig. 5 is a front perspective view of a personal mobility vehicle in the form of a motorised wheelchair incorporating the chassis shown in Fig. 1 ;

Fig. 6 is a front perspective view of the personal mobility vehicle shown in Fig. 5 with cowlings or fairings covering the chassis;

Fig. 7 is an upper perspective view of a chassis according to another exemplary embodiment of the disclosure;

Fig. 8 is a lower perspective view of the chassis seen in Fig. 7 with the left front wheel and its mount and drive motor removed;

Fig. 9 is a cross-sectional perspective view of the chassis shown in Fig. 7;

Fig. 10 is a cross-sectional perspective view of the chassis shown in Fig. 7, with each of the front subframe and the rear subframe shaded differently, both to identify them clearly and to distinguish them from one another and from the base frame, which is unshaded;

Fig. 11 is a front perspective view of a personal mobility vehicle in the form of a motorised wheelchair incorporating the chassis shown in Fig. 7; and

Fig. 12 is a front perspective view of a personal mobility vehicle shown in Fig. 1 1 with cowlings or fairings covering the chassis.

[0027] The accompanying drawings are included to provide further understanding of the present disclosure and are incorporated in and constitute a part of this specification. The drawings illustrate particular embodiments and together with the description serve to explain the principles of the present disclosure. Other embodiments and many of the attendant advantages will be readily appreciated as they become better understood with reference to the following detailed description.

[0028] It will be appreciated that common and/or well understood elements that may be useful or necessary in a commercially feasible embodiment are not necessarily depicted in order to facilitate a more abstracted view of the embodiments. The elements of the drawings are not necessarily illustrated to scale relative to each other. It will also be understood that certain actions and/or steps in an embodiment of a method may be described or depicted in a particular order of occurrences although those skilled in the art will understand that such specificity with respect to sequence is not actually required.

Detailed Description of the Embodiments

[0029] With reference firstly to Figs. 1 to 6 of the drawings, an embodiment of a chassis 1 for a personal mobility vehicle 100, especially a motorised wheelchair, is illustrated. The chassis 1 of this embodiment is designed with an “all-wheel-drive” configuration and includes wheels 2 having relatively large, pneumatic tyres 3 for improved ground clearance and better off-road, “all terrain” capability.

[0030] Referring to drawing Figs. 1 to 4, the chassis 1 comprises a base frame 10 upon which a seat 60 of the wheelchair 100 (see Fig. 5) is mounted and supported. The base frame 10 is a rigid structure and is preferably formed of steel. The base frame 10 includes a front frame member 11 that supports a front subframe 20 of the chassis 1 via a front suspension 12, and a rear frame member 13 that supports a rear subframe 40 of the chassis 1 via a rear suspension 14. The base frame 10 further includes a central frame member 15 which interconnects the front and rear frame members 11 , 12 and separates and partially defines two compartments or recesses 16 on opposites sides thereof, each configured for holding a battery B to electrically power the motorised wheelchair 100. The central frame member 15 in this embodiment forms or defines a channel or cavity 17 between the two battery compartments 16. As is apparent from drawing Figs. 3 and 4, a part of the front subframe 20 extends within the channel or cavity 17 and is pivotally connected to the central frame member 15 via a first pivot joint 18 and, likewise, part of the rear subframe 40 extends within the channel or cavity 17 and is pivotally connected to the central frame member 15 via a second pivot joint 19. Thus, it can be seen that the first pivot joint 18 of the front subframe 20 is located on the base frame 10 rearward of the second pivot joint 19, and the second pivot joint 19 of the rear subframe 40 is located on the base frame 10 forward of the first pivot joint 18. In this embodiment, each of the first pivot joint 18 and the second pivot joint 19 may be provided as a spherical bearing and may be configured for pivoting movement (i.e., rotational movement) about a respective transverse axis X, X’ as well as about a respective longitudinal axis Y, Y. The transverse axes X, X’ are substantially parallel to one another, and are typically substantially parallel to the rotational axes of the non-steered (rear) wheels. The longitudinal axes Y, Y’ extend substantially parallel to one another along a front-rear or forward-rearward axis of chassis 1 , substantially perpendicular to the transverse axes X, X’, and preferably substantially centrally of the base frame 10.

[0031] Referring further to drawing Figs. 1 to 4, the front subframe 20, like the base frame 10, has a robust and substantially rigid structure preferably formed from steel. The front subframe 20 includes a transverse part 21 adapted to support a pair of ground-engaging front wheels 2 at its laterally opposite sides. For this, a wheel mounting bracket 22 is pivotally attached via a pivot pin 23 at each of the laterally opposite sides of the transverse part 21 . As seen in Fig. 2, the wheel brackets 22 have an inverted L-shaped configuration for pivotally connecting a steering tie rod 24 to each of the brackets 22 (i.e., via a further pivot pin 25) at a position radially offset from the pivot pin 23. In this way, a steering control motor 26 (e.g., servo motor or stepper motor) located centrally on the transverse part 21 of the front sub-frame 20 can transmit steering movements via steering linkages, e.g., a pivot plate 27 and steering tie-rods 24 connected to it, to both of the wheel mounting brackets 22 to steer the direction of front wheels 2. Being an “all-wheel-drive” chassis 1 , each front wheel 2 is a driven wheel and the front subframe 20 includes an electric motor 28 that is mounted on each wheel mounting bracket 22 (e.g., via bolt holes 4) and connected to drive the respective front wheel 2. The transverse part 21 of the front subframe 20 is connected to and/or suspended from the front frame member 11 of the base frame 10 via the front suspension 12. In this regard, the front suspension 12 includes a pair of coaxially arranged spring / damper assemblies 29 spaced apart at laterally opposite sides of the front frame member 11 . This way, each of the spring/damper assemblies 29 provides for damped resilient movement of the front subframe 20 relative to the base frame 10 for both of the front wheels 2, but more predominantly for one or other of the two front wheels 2 of the chassis 1 . In this embodiment, the steering plate 27 and steering linkages 24, 25 are positioned on an upper side of transverse part 21 of front subframe 20, with the control motor 26 positioned below. This arrangement provides protection for the steering linkages, especially in off-road or rough terrain excursions, and more easily accommodates the front powertrain components (e.g., motors 28) below. This steering arrangement could be reversed, however, with the steering control motor 26 positioned above the transverse part 21 for obstacle isolation.

[0032] As is particularly clear from Figs. 3 and 4, the front subframe 20 further includes a central longitudinal part 30, in the form of a tubular elongate member, that is rigidly connected with the transverse part or member 21 and extends rearwardly thereof within the channel or cavity 17. An end 31 of that rearwardly extending central longitudinal part 30 is pivotally connected to the central frame member 15 of the base frame 10 via the first pivot joint 18. In this way, the front subframe 20 is mounted to base frame 10 for resilient pivoting movement, with the pivoting movement provided by the pivot joint 18 and the resilience provided by the two spring / damper assemblies 29 of front suspension 12. As noted above, the first pivot joint 18 may comprise a spherical bearing for pivoting movement about a transverse axis X and about a longitudinal axis Y. As an alternative to a spherical bearing, however, the first pivot joint 18 may comprise a plain pivot bearing that provides for pivoting movement about the transverse axis X only. In that case, pivoting movement about the longitudinal axis Y may still be provided, for example, by a rotatable connecting collar 32 in the end 31 of the elongate member 30.

[0033] It will also be seen that the front subframe 20 includes a Panhard rod 33 (also called a track rod or track bar) in the form of a link that provides a simple but effective lateral location of the front subframe 20 relative to the base frame 10. The front suspension 12 allows the transverse part 21 and front wheels 2 on the front subframe 20 to move vertically relative to the base frame 10 as the front subframe 20 pivots about the transverse axis X and/or the longitudinal axis Y. The Panhard rod 33 comprises a rigid rod running in a transverse or sideways direction generally parallel to the wheel axles, with one end connecting to the front subframe 20 and the opposite end to the base frame 10. The rod 33 attaches at either end via pivots that allow it to swivel upwards and downwards only, so that the subframe 20 can move in a generally vertical plane only. In this way, the Panhard rod 33 prevents movement of the transverse part 21 in the lateral or transverse direction.

[0034] With further reference to drawing Figs. 1 to 4, like the front subframe 20, the rear subframe 40 has a robust and substantially rigid structure preferably formed from steel. The rear subframe 40 includes a transverse part 41 , adjacent the rear frame member 13 of the base frame 10, which is adapted to support a pair of ground-engaging rear wheels 2 at its laterally opposite sides. The transverse part 41 comprises an elongate member which is configured to mount and/or accommodate an electric motor 48 at each of its two laterally opposite sides. In this way, a separate electric motor 48 may be provided and connected to drive each of the respective rear wheels 2. The transverse part 41 of rear subframe 40 is connected to and suspended from the rear frame member 13 of the base frame 10 via the rear suspension 14. Like the front suspension 12, the rear suspension 14 includes two coaxially arranged spring I damper assemblies 49 spaced apart at laterally opposite sides of the rear frame member 13. As before, each of the two rear spring/damper assemblies 49 provides for damped resilient movement of the rear subframe 40 relative to the base frame 10 for both of the rear wheels 2, but with each acting more predominantly for one or other of the two rear wheels 2 of the chassis 1 .

[0035] As is clear from Figs. 3 and 4, the rear subframe 40 also includes a central longitudinal part 42, again in the form of a tubular elongate member, that is rigidly connected with the transverse part or member 41 and extends forwardly thereof within the channel or cavity 17. An end 43 of the forwardly extending central longitudinal part 42 is connected to the central frame member 15 of the base frame 10 via the second pivot joint 19. In this way, like the front subframe 20, the rear subframe 40 is mounted to base frame 10 for resilient pivoting movement, with the pivoting movement provided by the pivot joint 19 and the resilience being provided by the spring I damper assemblies 49 of rear suspension 14. As noted above, the second pivot joint 19 may include a spherical bearing for pivoting movement about a transverse axis X’ and about a longitudinal axis Y’. As an alternative to a spherical bearing, however, the second pivot joint 19 may comprise a plain pivot bearing that provides for pivoting movement about the transverse axis X’ only. In such a case, pivoting movement about the longitudinal axis Y’ can still be provided, for example, by a rotatable connecting collar 44 in the end 43 of the elongate member 42. It will be seen that the longitudinal parts 30, 42 of the front and rear subframes 20, 40 are arranged one above the other centrally of the base frame 10. This arrangement reduces the overall width of the base frame 10. As an alternative, however, these longitudinal parts 30, 42 could also be arranged in a side-by-side configuration if desired. The extent of excursion / displacement of the front and rear suspensions 12, 14 that the front and rear subframes 20, 40 are able to accommodate can be varied by a corresponding positioning of the first and second pivot joints 18, 19 on the base frame 10. Other designs of the central parts 21 , 41 of the front and rear subframes 20, 40 can also be employed, as skilled persons will appreciate.

[0036] As with the front subframe 20, the rear subframe 40 includes a Panhard rod 45 (or track rod or track bar) as a link that provides lateral location of the rear subframe 40 relative to the base frame 10. The rear suspension 14 allows the rear transverse part 41 and rear wheels 2 of the rear subframe 40 to move vertically relative to the base frame 10 as the rear subframe 40 pivots about the transverse axis X’ and/or the longitudinal axis Y’. The Panhard rod 45 again comprises a rigid rod running in a transverse or sideways direction roughly parallel to the wheel axles, with one end connected to the rear subframe 40 and the opposite end to the base frame 10. The rod 45 attaches at its ends via pivots that allow it to swivel upwards and downwards only, so that rear subframe 40 can move in a generally vertical plane only. This way, the Panhard rod 45 prevents movement of the rear transverse part 41 in the lateral or transverse direction.

[0037] With reference to now drawing Figs. 5 and 6, a motorised wheelchair 100 is shown incorporating the chassis 1 of drawing Figs. 1 to 4. The wheelchair 100 includes a seat 60 for a user mounted on the base frame 10 of the chassis 1 , and specifically supported by the front frame member 11 , rear frame member 13 and central frame member 15. The seat 60 includes a cushion 61 upon which the user may sit, a backrest 62, a head rest 63, arm rests 64 and a leg rest 65, as is typical for such wheelchairs 100. The wheelchair 100 also includes fairings or cowlings 70 that are designed to cover the chassis 1 both for protective and aesthetic reasons. These fairings or cowlings 70 include a forward chassis cover 71 adjacent the leg rest 65, front wheel guards 72, side covers 73 to shield the battery compartments 16 and rear wheel guards 74. In addition, it can be seen that the wheelchair 100 includes a user control interface or control system 80 provided in or adjacent to an armrest 64 of the seat for easy operation of the vehicle functionalities by the user. The control interface 80 includes a joystick 81 and control switches / buttons 82 for operating any one of the driven movement and/or steering of the vehicle wheels 2 (typically via joystick 81 ) and/or for adjusting a position of any one or more of the cushion 61 , the backrest 62, the head rest 63, the arm rests 64 and the leg rest 65. In operation, the drive motors 28, 48 at wheels 2 may receive an input signal from the joystick 81 to drive forward or backward, for example, and/or the steering control motor 26 may receive an input signal from the joystick 81 to coordinate a turn. [0038] With reference to Figs. 7 to 10, there is illustrated another embodiment of a chassis 1 for a personal mobility vehicle 100, especially a motorised wheelchair. The chassis 1 of this embodiment is designed or configured as a two-wheel-drive chassis shown here in a front steering I rear driving layout. Alternatively, however, the chassis 1 could be configured as a front driving I rear steering layout if desired. The wheels 2 and tyres 3 of this embodiment are ‘lighter duty’ and are designed to operate on relatively flat or even paved or sealed surfaces. As for the embodiment in Figs. 1 to 4, the chassis 1 shown in Figs. 7 to 10 includes a base frame 10 having a front frame member 1 1 that supports front sub-frame 20 of the chassis 1 via a front suspension 12, and a rear frame member 13 that supports a rear subframe 40 of the chassis 1 via a rear suspension 14. The base frame 10 further includes a central frame member 15 that interconnects the front and rear frame members 11 , 13 and that separates and partially defines two compartments or recesses 16 on opposites sides thereof for holding a battery B to electrically power the motorised wheelchair 100. The central frame member 15 again defines a channel or cavity 17 between the two battery compartments 16.

[0039] As seen in drawing Figs. 9 and 10, a longitudinal part 30 of the front sub-frame 20 extends within the channel or cavity 17 and is pivotally connected to the central frame member 15 via a first pivot joint 18 and, likewise, a longitudinal part 42 of the rear subframe 40 extends within the channel or cavity 17 and is pivotally connected to the central frame member 15 via a second pivot joint 19. In this way, the first pivot joint 18 of the front subframe 20 is located on the base frame 10 rearward of the second pivot joint 19, and the second pivot joint 19 of the rear subframe 40 is located on the base frame 10 forward of the first pivot joint 18. As before, each of the first and second pivot joints 18, 19 may be a spherical bearing and may be configured for pivoting movement about a respective transverse axis X, X’ as well as about a respective longitudinal axis Y, Y’. Indeed, it will be appreciated by skilled persons reviewing the drawings that the configuration of the chassis 1 of this embodiment in Figs. 7 to 10 is very similar to, and shares many of the features of, the configuration of the chassis 1 in Figs. 1 to 4 and described in detail above. To avoid unnecessary repetition of description, and because like reference signs identify or designate like features or parts in the drawings, the configuration and the operation of the features or parts of the embodiment shown in Figs. 7 to 10 that are the basically same as in the previous embodiment will not be described here again, but will be apparent from the above description. [0040] The primary differences between this embodiment shown in Figs. 7 to 10 and the previous embodiment in Figs. 1 to 4 reside in the configuration of the front subframe 20. As is particularly apparent from Figs. 7 and 8, the transverse part 21 of the front subframe 20 comprises a pair of transverse members 2T, each having a pivot joint 23 at its free end pivotally supporting a wheel mounting bracket 22, to which a steering tie rod 24 is connected via a further pivot joint 25. As before, each of the steering tie rods 24 is connected to the steering control motor 26 via a steering plate 27. In this example, the steering plate 27 and the steering linkages 24, 25 are located on an underside of transverse part 21 I transverse members 2T of the front subframe 20 as there is more space available without the electric drive motors 28 of a front powertrain in this embodiment. As the other features of the chassis 1 of this embodiment remain substantially unchanged, they are not described again here in detail. Rather, as like reference signs identify or designate like features or parts in the drawings, the configuration and operation of those features or parts will be apparent from the above description.

[0041] With reference to drawing Figs. 11 and 12, a motorised wheelchair 100 is shown incorporating the chassis 1 of drawing Figs. 7 to 10. As before, the motorised wheelchair 100 includes a seat 60 for a user mounted on the base frame 10 of the chassis 1 , and specifically supported by the front frame member 11 , rear frame member 13 and central frame member 15. The seat 60 again includes a cushion 61 , a backrest 62, a head rest 63, arm rests 64 and a leg rest 65. The wheelchair 100 also includes fairings or cowlings 70 that cover the chassis 1 both for protective and aesthetic reasons, once again with a forward chassis cover 71 adjacent leg rest 65, front wheel guards 72, side covers 73 over the battery B in each of the two battery compartments 16, and rear wheel guards 74. A user control interface or control system 80 is also provided.

[0042] Although specific embodiments of the disclosure are illustrated and described herein, it will be appreciated by persons of ordinary skill in the art that a variety of alternative and/or equivalent implementations exist. It should be appreciated that each exemplary embodiment is an example only and is not intended to limit the scope, applicability, or configuration in any way. Rather, the foregoing summary and detailed description will provide those persons skilled in the art with a convenient road map for implementing at least one exemplary embodiment, it being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope as set forth in the appended claims and their legal equivalents.

[0043] Generally, this application is intended to cover any adaptation or variation of the particular embodiments discussed herein. By way of example, a skilled person will readily appreciate that the system of this disclosure is not limited to being made from any specific material described in the embodiments. Rather, the skilled person will appreciate that a range of suitable materials exist and the skilled person can select a material based upon the known mechanical properties of that material which make it suitable for use in the system. As the present disclosure involves engineering technology from different disciplines, it is expected that the notional ‘skilled person’ may comprise a group or a team of individuals having technical expertise and/or qualifications in one or more of the following fields: mechanical engineering, electrical engineering, and materials science. As already noted at the outset, it will be appreciated that the chassis 1 of the disclosure as described with reference to the drawings may also be employed in a recreational vehicle, such as a motorised scooter, a quad bike, a golf cart, or other motorised cart.

[0044] For example, the steering control motor 26 may be any driving element or device, whether electrically, mechanically, pneumatically, or hydraulically operated to facilitate a turning manoeuvre in response to a steering input. In an embodiment the steering control motor 26 is a servo motor or stepper motor and may include one or more of a positional and/or velocity/acceleration feedback loop. However, it will be appreciated that other motors, either using rotary or linear motion actuation, may also be employed for the steering control motor 26 in this disclosure.

[0045] It will be noted that bearings of the first and second pivot joints 18, 19 may be spherical, plain bearings or bushings, swivel bearings or bushings, rubber bushings, or other forms of bearing elements that accommodate movement within a longitudinal or central plane and permit rotational or pivoting movement about a transverse axis X, X’ and/or longitudinal axis Y, Y’ of the central parts 21 , 41. The swivelling action of the central parts 21 , 41 will, in certain instances, be the result of one wheel on a given side of the front or rear subframe 20, 40 generating a larger jolt or rebound excursion than the other side, such as when a single wheel of the vehicle encounters a hole or a raised obstruction. The swivelling movement of the front or rear subframes 20, 40 may also be characterized as a torsional movement about a longitudinal axis Y, Y’ of the central parts 21 , 41 that can act independently of the apparent linear movement of the subframes 20, 40 through a central plane of the base frame 10. This twisting movement is accommodated by the first and second pivot joints 18, 19 which also transfer thrust or drive forces generated from the drive motors 28, 48 to the base frame 10.

[0046] It will also be appreciated that, unless the context requires otherwise, the terms "comprise", "comprising", "contain", "containing", "have", "having", and any variations thereof, used in this document are intended to be understood in an inclusive (i.e. non-exclusive) sense, such that the process, method, device, apparatus, or system described herein is not limited to the features, integers, parts, elements, or steps recited but may include other features, integers, parts, elements, or steps not expressly listed and/or inherent to such process, method, device, apparatus, or system. Furthermore, the terms "a" and "an" used herein are intended to be understood as meaning one or more unless explicitly stated otherwise. In addition, reference to positional terms, such as “lower” and “upper”, used in the above description are to be taken in context of the embodiments depicted in the figures, and are not to be taken as limiting the disclosure to the literal interpretation of the term but rather as would be understood by a skilled addressee in the appropriate context. Moreover, unless indicated to the contrary, the terms "first", "second", "third", etc. are used merely as labels, and are not intended to impose numerical requirements on, or to establish a ranking of importance, of their objects.

[0047] List of reference sians

1 chassis 40 rear subframe

2 wheels 41 transverse part

3 tyres 42 central or longitudinal part

4 bolt hole 43 end of longitudinal part

10 base frame 44 rotatable connecting collar

11 front frame member 45 Panhard rod

12 front suspension 48 electric motor

13 rear frame member 49 spring/damper assembly

14 rear suspension 60 seat

15 central frame member 61 cushion

16 recess or compartment 62 backrest

17 channel or cavity 63 head rest

18 first pivot joint 64 arm rests

19 second pivot joint 65 leg rest

20 front subframe 70 fairing or cowling

21 transverse part 71 forward chassis cover

21 ’ transverse member 72 front wheel guard

22 wheel mounting bracket 73 side cover

23 pivot pin 74 rear wheel guard

24 steering tie rod 80 control system or interface

25 pivot joint 81 joystick

26 steering control motor 82 control switch or button

27 pivot plate 83 side covers

28 electric motor 100 personal mobility vehicle

29 spring/damper assembly B battery

30 central or longitudinal part X transverse axis

31 end of longitudinal part X’ transverse axis

32 connecting collar Y longitudinal axis

33 Panhard rod Y’ longitudinal axis

Claims

Claims:

1. A chassis for a personal mobility vehicle or recreational vehicle, the chassis comprising: a base frame for supporting a seat and/or for supporting a user of the vehicle thereon; a front subframe having at least one ground-engaging front wheel, the front subframe being connected to the base frame via a front suspension for resilient movement relative to the base frame; and a rear subframe having at least one ground-engaging rear wheel, the rear subframe being connected to the base frame via a rear suspension for resilient movement relative to the base frame; wherein at least one of the front subframe and the rear subframe, and preferably both of them, is/are separately and independently pivotally connected to the base frame for pivoting movement relative to the base frame.

2. The chassis according to claim 1 , wherein the front subframe is pivotally connected to the base frame via a first pivot joint and/or wherein the rear subframe is pivotally connected to the base frame via a second pivot joint.

3. A chassis for a personal mobility vehicle or recreational vehicle, the chassis comprising: a base frame for supporting a seat and/or for supporting a user of the vehicle thereon; a front subframe having a pair of ground-engaging front wheels, the front subframe being connected to the base frame via a front suspension for resilient movement relative to the base frame; and a rear subframe having a pair of ground-engaging rear wheels, the rear subframe being connected to the base frame via a rear suspension for resilient movement relative to the base frame; wherein the front subframe is pivotally connected to the base frame via a first pivot joint, and wherein the rear subframe is pivotally connected to the base frame via a second pivot joint.

4. The chassis according to any one of the preceding claims, wherein the front subframe includes: a transverse member on which each ground-engaging front wheel is mounted, and an elongate member rigidly connected with the transverse member that extends rearwardly, and preferably centrally, on the base frame, with a rearward end of that elongate member being pivotally connected to the base frame via the first pivot joint.

5. The chassis according to any one of the preceding claims, wherein the rear subframe includes: a transverse member on which each ground-engaging rear wheel is mounted, and an elongate member rigidly connected with that transverse member extending forwardly, and preferably generally centrally, on the base frame, with a forward end of that elongate member being pivotally connected to the base frame via the second pivot joint.

6. The chassis according to any one of the preceding claims, wherein the front subframe is configured for pivoting movement relative to the base frame about one, or both, of a transverse axis of the base frame and a longitudinal axis of the base frame.

7. The chassis according to any one of the preceding claims, wherein the rear subframe is configured for pivoting movement relative to the base frame about one, or both, of a transverse axis of the base frame and a longitudinal axis of the base frame.

8. The chassis according to any one of the preceding claims, wherein the front suspension is provided between the base frame and the transverse part of the front subframe, and wherein the rear suspension is provided between the base frame and the transverse part of the rear subframe.

9. A personal mobility vehicle, especially a wheelchair, for an individual with a disability, the personal mobility vehicle comprising a chassis according to any one of the preceding claims.

10. A recreational vehicle, such as a scooter, a quad bike, or a golf cart, wherein the vehicle comprises a chassis according to any one of claims 1 to 8.

11. A chassis for a recreational vehicle or for a personal mobility vehicle for an individual with a disability, the chassis comprising: a base frame for supporting a seat, or for supporting a user, of the vehicle thereon; and a front subframe for mounting at least one ground-engaging front wheel of the vehicle, the front subframe being connected to the base frame for resilient movement relative to the base frame; wherein the front subframe is connected to the base frame via a first pivot joint.

12. The chassis according to claim 1 1 , comprising a rear subframe for mounting at least one ground-engaging rear wheel of the vehicle, wherein the rear subframe is connected to the base frame for resilient movement relative to the base frame via a second pivot joint.

13. The chassis according to claim 12, wherein the first pivot joint is located on the base frame rearward of the second pivot joint, and/or wherein the second pivot joint is located on the base frame forward of the first pivot joint.

14. The chassis according to any one of claims 11 to 13, wherein the first pivot joint is provided on a rear portion of the base frame (i.e., rearward of a centre of the base frame), and/or wherein the second pivot joint is provided on a front portion of the base frame (i.e., forward of a centre of the base frame).

15. The chassis according to any one of claims 1 1 to 14, wherein the front sub-frame comprises a transverse part adapted to support a pair of ground-engaging front wheels at laterally opposite sides thereof, and a longitudinal part that extends rearwardly of the transverse part, wherein an end region of the rearwardly extending longitudinal part is pivotally connected to the base frame via the first pivot joint.

16. The chassis according to claim 15, wherein the transverse part of the front subframe comprises at least one transverse member for supporting one of the ground-engaging front wheels at an end thereof, and the longitudinal part of the front subframe includes an elongate member rigidly connected with the transverse part that extends rearwardly, and preferably generally centrally, of the base frame, wherein an end of the elongate member is pivotally connected to the base frame via the first pivot joint.

17. The chassis according to any one of claims 11 to 16, wherein the front sub-frame is connected to the base frame for resilient movement relative to the base frame about the first pivot joint, preferably via a front suspension that is provided between the base frame and the transverse part of the front subframe.

18. The chassis according to any of claims 1 1 to 17, wherein the rear subframe comprises a transverse part adapted to support a pair of ground-engaging rear wheels at laterally opposite sides thereof, and a longitudinal part that extends forwardly of that transverse part, wherein an end region of the forwardly extending longitudinal part is pivotally connected to the base frame via the second pivot joint.

19. The chassis according to claim 18, wherein the transverse part of the rear subframe comprises at least one transverse member for supporting one of the ground-engaging rear wheels at an end thereof, and the longitudinal part of the rear subframe includes an elongate member rigidly connected with the transverse part that extends forwardly, and preferably centrally, of the base frame, wherein an end of the forwardly extending elongate member is pivotally connected to the base frame via the second pivot joint.

20. The chassis according to any one of claims 11 to 19, wherein the rear sub-frame is connected to the base frame for resilient movement relative to the base frame about the second pivot joint, preferably via a rear suspension that is provided between the base frame and the transverse part of the rear subframe.

21 . The chassis according to any one of claims 11 to 20, wherein the first pivot joint is configured for pivoting movement of the front subframe relative to the base frame about at least one, or both, of a transverse axis of the base frame and a longitudinal axis of the base frame.

22. The chassis according to any one of claims 11 to 21 , wherein the second pivot joint is configured for pivoting movement of the rear subframe relative to the base frame about at least one, or both, of a transverse axis of the base frame and a longitudinal axis of the base frame.

23. The chassis according to any one of claims 11 to 22, wherein the rear sub-frame includes an electric motor associated with each rear wheel, wherein each rear wheel is a driven wheel, the rear subframe preferably including a pair of electric motors mounted on the transverse part thereof, with each electric motor being connected to drive a respective one of rear wheels.

24. The chassis according to any one of claims 11 to 23, wherein the front sub-frame includes an electric motor associated with each front wheel, wherein each front wheel is a driven wheel, the front subframe preferably including a pair of electric motors mounted on the transverse part thereof, with each electric motor being connected to drive a respective one of front wheels.

25. The chassis according to any one of claims 1 1 to 24, wherein the base frame includes at least one recess or compartment for holding a battery for electrically powering the vehicle.

26. The chassis according to claim 25, wherein the base frame includes two recesses or compartments for holding a battery for electrically powering the vehicle, wherein the two recesses or compartments are provided on laterally opposite sides of the base frame.

27. A personal mobility vehicle, especially a wheelchair, for an individual with a disability, the personal mobility vehicle comprising a chassis according to any one of the claims 1 1 to 26, and a seat mounted upon the base frame of the chassis for supporting a user of the vehicle.

28. A recreational vehicle, such as a scooter, a quad bike, or a golf cart, wherein the vehicle comprises a chassis according to any one of claims 11 to 26.