WO2025003442A1

WO2025003442A1 - Stand-up wheelchair

Info

Publication number: WO2025003442A1
Application number: PCT/EP2024/068315
Authority: WO
Inventors: Gabriel COSTA EUFRASIO; Roy Martinus Fransiscus VAN POPPEL
Original assignee: J58 Holding BV
Current assignee: J58 Holding BV
Priority date: 2023-06-30
Filing date: 2024-06-28
Publication date: 2025-01-02
Anticipated expiration: 2025-12-30
Also published as: NL2035234B1

Abstract

Stand-up wheelchair, comprising: - a seat assembly for seating a user therein, wherein the seat assembly is movable between a sitting position, wherein the user is supported in a sitting posture, and a standing position, wherein the user is supported in a standing posture; - a pair of primary wheels for movably supporting the seat assembly on a supporting surface, wherein said primary wheels are arranged on a rear section of the stand-up wheelchair on opposite sides of said wheelchair; - at least one secondary wheel unit for movably supporting the seat assembly on the supporting surface, wherein the secondary wheel unit comprises a secondary wheel, in particular a swivel wheel, and wherein the secondary wheel unit is arranged at a frontal section of the stand-up wheelchair; characterized in that: - the secondary wheel unit is movable between a first position, wherein the secondary wheel unit, in particular the swivel axis of said swivel wheel, is arranged at a first distance from a primary wheel, and a second position, wherein the secondary wheel unit is arranged at a second distance from the respective primary wheel, wherein the second distance is greater than the first distance.

Description

Stand-up wheelchair

Stand-up wheelchairs, also known as standing wheelchairs or standers, are mobility devices designed to allow individuals who use wheelchairs to transition from a seated position to a standing position. These wheelchairs typically have a combination of features that enable the user to elevate themselves to a standing position, providing various health and functional benefits.

Stand-up wheelchairs can be manually operated or powered, depending on the model. They usually have adjustable seating and leg support components that assist the user in achieving a standing posture. These wheelchairs are beneficial for individuals with limited mobility who wish to maintain an upright position, as standing offers advantages such as improved circulation, enhanced bone density, and increased social interaction. Stand-up wheelchairs have become increasingly recognized as valuable mobility aids that provide individuals with the ability to transition from a seated to a standing position. These wheelchairs offer a range of benefits, including improved posture, enhanced social interaction, and various physiological advantages associated with standing. However, the existing stand-up wheelchair designs suffer from certain disadvantages, which limit their usability and overall effectiveness in addressing the needs of users.

Stand-up wheelchairs can be manually operated or powered, depending on the model. They usually have adjustable seating and leg support components that assist the user in achieving a standing posture. The current generation of stand-up wheelchairs, while serving their purpose, often exhibit certain drawbacks that hinder their widespread adoption and usage.

While electrically powered stand-up wheelchairs offer convenience and ease of use, they are not without their limitations. One significant disadvantage is the reliance on battery power, which necessitates frequent recharging and may lead to unexpected interruptions in mobility. The limited battery life restricts the duration of continuous use, potentially causing inconvenience and reliance on charging infrastructure. Moreover, the weight of the batteries adds to the overall bulkiness of the wheelchair, making it less maneuverable and potentially challenging to transport. Additionally, the complexity of electrical components increases the risk of malfunctions, requiring regular maintenance and potentially leading to extended downtime for repairs.

While manually operated stand-up wheelchairs offer certain advantages, they also come with their own set of limitations. One significant disadvantage is the physical exertion required from the user to operate and transition between seated and standing positions. This can be challenging for individuals with limited upper body strength or mobility impairments, potentially restricting their ability to independently use the wheelchair. Moreover, the process of manually adjusting the seating and leg support components may be cumbersome and time-consuming, leading to inconvenience and potential discomfort for the user. Additionally, the lack of powered assistance limits the overall ease of use and may result in limitations in terms of the range and frequency of standing transitions.

Additionally, in the standing position, the center of gravity is shifted significantly upwards, thereby leading to a decreased stability, or at least a decreased perception of stability, of the wheelchair. The stability can be increased by providing for a larger wheelchair and/or by providing additional mass in the lower section of the wheelchair, this however, leads to a decrease in the maneuverability and useability of the wheelchair.

The goal of the invention is to solve, or at least alleviate, some of the disadvantages of current stand-up wheelchairs, in particular aims to provide for a compact, easily operable and maneuverable stand-up wheelchair having an improved stability in the standing position.

The invention therefore provides for a stand-up wheelchair, comprising: a seat assembly for seating a user therein, wherein the seat assembly is movable between a sitting position, wherein the user is supported in a sitting posture, and a standing position, wherein the user is supported in a standing posture; a pair of primary wheels for movably supporting the seat assembly on a supporting surface, wherein said primary wheels are arranged on a rear section of the stand-up wheelchair on opposite sides of said wheelchair; at least one secondary wheel unit for movably supporting the seat assembly on the supporting surface, wherein the secondary wheel unit comprises a secondary wheel, in particular a swivel wheel, and wherein the secondary wheel unit is arranged at a frontal section of the stand-up wheelchair; characterized in that: the secondary wheel unit is movable between a first position, wherein the secondary wheel unit, in particular the swivel axis of said swivel wheel, is arranged at a first distance from a primary wheel, and a second position, wherein the secondary wheel unit is arranged at a second distance from the respective primary wheel, wherein the second distance is greater than the first distance.

By moving, for instance when the stand-up wheelchair is in the standing position, the secondary wheel unit to the second position, the distance between the secondary wheel unit and the primary wheels (i.e. the wheelbase of the wheelchair) increases, such that the stability of the stand-up wheelchair increases, leading to an increased safety, or at least a by the user perceived sense of safety. By moving the secondary wheel unit to the first position, the wheelbase decreases, which leads to an increased maneuverability of the stand-up wheelchair, which is, in particular when in the sitting position, beneficial for the user. The secondary wheel unit is therefore movable in at least a forward-backward direction that is substantially parallel to the forward moving direction of the wheelchair (i.e. the direction that user in a normal sitting or standing position faces and/or the direction of travel of the wheelchair when both primary wheels are rotating at equal speed and equal rotational direction around there respective rotational axes).

In stand-up wheelchairs according to the prior art, the secondary wheel unit is not able to move in at least the forward-backward direction, thereby the wheelbase cannot be adapted when moving between the sitting an standing position, such that a compromise between stability and maneuverability has to be made. It is further noted that, in case the secondary wheel, that is comprised in the secondary wheel unit itself is freely movable, and/or pivotable, with respect to the secondary wheel unit itself, the first and second distances are determined when the second wheel is oriented in its natural forward moving position. As an example, assuming the secondary wheel unit comprises a swivel wheel that is pivotable along an axis that is at an angle, in particular perpendicular to, the supporting surface, then the first and second distances are determined in both cases where the swivel wheel is swiveled backwards, such that the secondary wheel is oriented in its forward moving position.

The stand-up wheelchair according to the current disclosure thereby enables an improved stability in the standing position, by positioning the secondary wheel unit in the second position, while also being highly maneuverable and more compact in the sitting position, by positioning the secondary wheel unit in the first position.

Preferably, the secondary wheel unit is arranged to be movable between the first and second position when the seat assembly is moved between the sitting and standing position. This enables to move the secondary wheel unit between the first and the second position while moving the seat assembly from the first to the second position, such that any period of decreased stability when moving to the standing position, or vice versa, is prevented, or at least made shorter.

In a preferred embodiment, the secondary wheel unit is operatively coupled to the seat assembly using a transfer mechanism, such that, upon moving the seat assembly from the sitting to the standing position, the secondary wheel unit is moved, by means of the transfer mechanism, from the first position to the second position and vice versa. Hereby, an automatic operative coupling between the moving mechanism of the secondary wheel unit and the seat assembly is obtained, such that the secondary wheel unit moves with the seat assembly. In addition to the above noted advantages, it is noted that as the secondary wheel unit moves by default with the seat assembly, the seat assembly cannot be brought to the standing position without moving the secondary wheel unit, such that the safety of the wheelchair is further improved.

In an alternative embodiment, the secondary wheel unit is manually operable for moving the secondary wheel unit from the first to the second position, preferably wherein a handle is provided that is operable by a user in the wheelchair for moving the secondary wheel unit from the first to the second position. Hereby, the user retains control over the position of the secondary wheel unit, irrespective of whether the seat assembly is in the standing or sitting position. This enables to, for instance, temporarily move the secondary wheel unit to the first position, such that the maneuverability of the wheelchair in the standing position can temporarily be improved.

In a preferred embodiment, the wheelchair comprises a pivoting arm member whereon the secondary wheel unit is arranged, preferably at a distal section thereof, wherein the pivoting arm member is arranged to pivot around a hinge axis that is arranged at a non-zero angle with, in particular perpendicular to, the axis of rotation of the secondary wheel, such that, upon rotating the pivoting arm member around the hinge axis, the secondary wheel unit can be moved from the first to the second position and vice versa. The pivoting movement enables a simple and robust mechanism for moving the secondary wheel unit from the first to the second position. In particular in the case that the hinge axis is perpendicular to the support surface, the movement from the first to the second position does not require much force (in fact torque) to actuate. Also, as the secondary wheel remains in contact with the supporting surface during such a movement, the stability of the wheelchair is not, or at least hardly, affected during the motion. This enables that the transition from the sitting to the standing position (or vice versa) can be performed while the user remains in the wheelchair.

Preferably, the stand-up wheelchair further comprises a frame member, wherein said primary wheels and said secondary wheel unit are arranged on the frame member and wherein the seat assembly is connected to the frame member. The frame member thereby allows to mount the different components for forming the wheelchair and provides for a robust support. It is then further preferred that said secondary wheel unit is movably connected to the frame member, in particular wherein a proximal section of the pivoting arm member is pivotally arranged to the frame, in particular at a frontal section of the frame. A robust and stabile stand-up wheelchair is thereby enabled.

In a preferred embodiment, said seat assembly comprises at least a seat base, wherein a frontal section of the seat base of the seat assembly is pivotally arranged, in particular pivotally connected to the frame member, such that, upon moving the seat assembly from the sitting to the standing positing, the seat base is pivoted with respect to the supporting surface, such that an angle between the seat base and supporting surface is varied. A smooth transition of the seat base between the standing and sitting is thereby enabled, wherein the user can remain in the wheelchair during the transition.

Preferably, said seat assembly comprises a seat base and a back rest, wherein a rear section of said seat base is pivotally connected to a lower section of said back rest and wherein, upon moving the seat assembly from the sitting to the standing positing, the seat base is pivoted with respect to the back rest, such that an angle between the seat base and back rest is increased. A smooth transition between the standing and sitting of the orientation of the seat base with respect to the backrest is thereby enabled, wherein the user can remain in the wheelchair during the transition. Preferably, the angle between the backrest and the supporting surface is substantially equal in the standing and sitting positions.

This can be enabled in a preferred embodiment, wherein the seat assembly comprises a four-bar mechanism, wherein a first bar of the four-bar mechanism is comprised in the seat base and an adjacent second bar is comprised in the back rest.

It is preferred that the transfer mechanism comprises a plurality of operative coupled push-pull rods, wherein the first outer end of the transfer mechanism, in particular the first push-pull thereof, is operatively coupled to the seat assembly and the second, opposite, outer end of the transfer mechanism, in particular the final push-pull rod thereof, is operatively coupled to the secondary wheel unit. The movement of the seat assembly is thereby operatively coupled to the movement of the secondary wheel unit, such that upon moving the seat assembly to the standing position, the transfer mechanism, using the plurality of operatively coupled push-pull rods, pushes the second wheel unit to the second position. As described above, this enables a stand-up wheelchair having an improved stability, and thereby improved safety. In particular, the first push-pull rod is connected to one of the bars of the four-bar mechanism, in particular to the third bar that is arranged opposite to the first bar, and wherein the final push-pull rod is connected to the pivoting arm member, such that, upon pivoting the seat base towards the standing position, the secondary wheel unit is automatically and simultaneously pushed, by the final push-pull rod, to the second position and vice versa, thereby enabling the earlier mentioned advantages.

Preferably, the stand-up wheelchair comprises a pair of secondary wheel units that are each movable from a respective first to a respective second position and vice versa, wherein one of said secondary wheel units is arranged on a first side of the wheelchair and the other of said secondary wheel units is arranged on the opposite side of said wheelchair. Such a pair of secondary wheel units further improves the stability, in particular the side-way stability, of the stand-up wheelchair. It is then preferred that said secondary wheel units are operatively coupled in such a way that they are only allowed to move simultaneously from the first to the second position, and vice versa. Any user-induced mistakes (e.g. moving only one of the secondary wheel units from the first to the second position) can thereby be reduced, adding to the overall safety of the wheelchair.

In a preferred embodiment, the wheelchair further comprises at least one actuator, preferably two actuators, for at least aiding to move the seat assembly towards the standing position, wherein an actuator is preferably a linear actuator, such as a pre-loaded linear gas spring, electric, hydraulic or pneumatic linear actuator that, preferably, extends when moving to the standing position. Such an actuator is able to deliver a large portion of the force (e.g. more than 50%, preferably more than 70%, even more preferable more than 90%) of the force required for moving the stand-up wheelchair from the sitting to the standing position while the user is in the wheelchair. This enables that the wheelchair requires little additional force to be transit from one position to the other, enabling to obtain an easily operable and stable stand-up wheelchair.

In an embodiment, said stand-up wheelchair is an electrically driving stand-up wheelchair comprising a drive mechanism for driving the primary wheels and, preferably, comprises an electrical actuator for moving the seat assembly from the sitting to the standing position and vice versa. Such an electrically driven stand-up wheelchairs offer a stable, and easily operable solution of uses with severely reduced mobility. Alternatively, said stand-up wheelchair can be a non-powered wheelchair that is arranged to be manually driven by the user and/or arranged to be manually pushed, preferably, comprising a pre-loaded linear gas spring for aiding to move the seat assembly towards the standing position. Such a manually operable stand-up wheelchair is a stable, easily operable and compact solution for users that have a less severe reduced mobility. Due to the compactness and reduced weight, when compared to the electrical variants, it is easier to transport and use in everyday situations, while still offering the increased stability in the standing position and high maneuverability in the sitting position.

Preferably, an embodiment stand-up wheelchair comprises at least one auxiliary manual drive system for driving a respective primary wheel, comprising a rotatable auxiliary drive handle that is to move with seat assembly between the sitting and standing positions and is arranged to be rotated by the user, wherein a respective rotatable auxiliary drive handle is operatively coupled to the respective primary wheel by a drive transfer mechanisms, preferably comprising a series of drive belts and/or chains, such that a user is able to manually rotate the respective primary wheel in both the sitting and standing positions by rotating the respective rotatable auxiliary drive handle. The user is thereby able to manually rotate the primary wheels even in the stand-up position, whereby the user is no longer able to directly operate the primary wheels for maneuvering the wheelchair. This is particularly useful for non-powered wheelchairs.

Preferably, each side of the wheelchair is provided with a respective actuator, a respective transfer mechanism, a respective drive system and/or a respective auxiliary manual drive system, wherein the stand-up wheelchair is preferably arranged to be substantially mirror-symmetric over a mirror plane that is substantially perpendicular to the seat base and/or axis of rotation of the primary wheels. This, for instance, leads to an even distribution of the weight, thereby improving the stability of the wheelchair. The present invention is further illustrated by the following figures, which show preferred embodiments of the stand-up wheelchair according to the present disclosure, and are not intended to limit the scope of the invention in any way, wherein:

- Figure 1 schematically shows, in a three dimensional perspective view, a first embodiment of the stand-up wheelchair according to the current disclosure in a sitting position.

- Figure 2 schematically shows, in a top-down view, the first embodiment in the sitting position.

- Figure 3 schematically shows, in a frontal view, the first embodiment in the sitting position. - Figures 4, 5A and 5B show, in a cross-sectional view, the stand-up wheelchair according to the first embodiment in the sitting position (figure 4), an intermediate position (figure 5A) and a standing position (figure 5B).

- Figure 6 schematically shows, in a three dimensional perspective view, the first embodiment in the standing position.

- Figures 7A and 7B schematically show, in a three dimensional and cross-sectional view, a second embodiment of the stand-up wheelchair according to the current disclosure in a sitting position.

- Figures 8A and 8B schematically show, in a three dimensional and cross-sectional view, a third embodiment of the stand-up wheelchair according to the current disclosure in a sitting position.

- Figures 9A and 9B schematically show, in a three dimensional and cross-sectional view, a fourth embodiment of the stand-up wheelchair according to the current disclosure in a sitting position.

Figures 1 - 3 schematically show, in various views, a first embodiment of the stand-up wheelchair 1000 according to the current disclosure in a sitting position. The wheelchair 1000 comprises a seat assembly 100 for seating a user (not shown) therein. The seat assembly 100 is movable between a sitting position (as shown in figure 1), wherein the user is supported in a sitting posture, and a standing position (as shown in figure 6), wherein the user is supported in a standing posture. The seat assembly 100 comprises a seat base 110 and a back rest 120, wherein a frontal section 111 of the seat base 110 of the seat assembly 100 is pivotally arranged on the frame 200, respectively on an upper section 201 thereof, in the current example by means of a hinging connection 112. Upon moving the seat assembly 100 from the sitting to the standing positing, the seat base 110 is pivoted with respect to the supporting surface, such that an angle between the seat base 110 and supporting surface S is varied.

The rear section 113 of the seat base 110 is pivotally connected, in the current example by means of a hinging connection 122, to a lower section 121 of the back rest 120. Upon moving the seat assembly 100 from the sitting to the standing positing, the seat base 110 is pivoted with respect to the back rest 120, such that an angle between the seat base 110 and back rest 120 is increased. In the current example, the seat base 110 and back rest 120 respectively comprise suspended, flexible fabric members 114, 124 that are respectively suspended between seat base subframe members 115 and back seat subframe members 125.

The pair of primary wheels 300 are mounted at a lower rear section 202 of the frame 200 and movably supporting the wheelchair 1000 on the supporting surface S. The primary wheels 300 are arranged opposite sides of the wheelchair 1000, in particular of the frame 200. The primary wheels 300 are, in the current examples, spoke wheels 301 having a relatively large diameter (i.e. a diameter of more than 40% of the height of the wheelchair 1000 in the sitting position). They can be fitted with inflatable tubes 302 for providing increased comfort. The wheels 300 can further comprise a co-axially arranged ring-shaped handles 302 extending outwardly. The ring-shaped handles 302 can be gripped by the user for manually maneuvering the wheelchair 1000. As the primary wheels 1000 are arranged rotationally-independent of each other, the user can, by manipulating the rotations of the respective wheels, move forward (i.e. parallel to forward direction I), backward and/ rotate around a axis of rotation R that is substantially perpendicular to the supporting surface S.

A pair of secondary wheel units 400 for movably supporting the seat assembly on the supporting surface S is provided at a frontal section of the stand-up wheelchair 1000, in particular onto a lower frontal section 203 of the frame 200. The secondary wheel units 400 each comprise a secondary wheel, in particular a swivel wheel (i.e. swivel caster) 401 that is arranged to rotate around a swivel wheel axis Rn, such that the wheel 401 will automatically align itself to the current direction of travel. The secondary wheel unit 400 is movable between a first position, wherein the swivel axis Rn of the swivel wheel 401 is arranged at a first distance dl from the rotation axis of the primary wheel 300, and a second position, wherein the swivel axis Rn of the swivel wheel 401 is arranged at a second distance d2 from the rotation axis of the primary wheel 300 (see figure 5B) , wherein the second distance d2 is greater than the first distance dl.

This movement is enabled by providing a pivoting arm member 402 whereon the secondary wheel unit 401 is arranged at the distal section 403 thereof. The opposite proximal section 404 of the pivoting arm member 402 is pivotally arranged to the frontal lower section 203 of the frame 200. The pivoting arm member 402 is arranged to pivot around a hinge axis Rm that is arranged at a non-zero angle with, in particular perpendicular to the supporting surface S. Upon rotating the pivoting arm member 402 around the hinge axis Rm, the secondary wheel unit 401 can be moved from the first to the second position and vice versa. The frontal lower section 203 of the frame 200 is further provide with a footrest 204 whereon the user can rest his, or her, feet.

Figure 4 shows a cross-sectional view of the wheelchair 1000, as taken along the A-A section as shown in figure 3, and thereby gives a more detailed view of the various mechanisms of wheelchair 1000. Firstly, the seat assembly 100 comprises a four-bar mechanism 130, wherein a first bar 131 of the four-bar mechanism 130 is comprised in the seat base 110 and is, in the current example formed by the seat base subframe member 115. The adjacent second bar 132 (as seen counter-clockwise) is comprised in, i.e. at least rigidly connected to, the back rest 120. The third bar 133 runs below, and substantially parallel to the first bar 131 and the fourth bar 134 is formed by a section of the frame 200. The four-bar mechanism 130 thereby enables to transition the seat assembly 100 from the sitting to the standing position (and vice versa) in a single movement, as the respective angles between the seat base 110 and the supporting surface S, the seat base 110 and back rest 120 and the back rest 120 and supporting surface S, are all coupled through the four-bar mechanism 130, such that by a single movement, the seat base 110 and back rest 120 are moved to the correct position and orientation. The wheelchair 1000 further comprises a transfer mechanism 410 that operatively couples the seat assembly 100 to the secondary wheel unit 400, such that, upon moving the seat assembly 100 from the sitting to the standing position, the secondary wheel unit 400 is automatically moved, by means of the transfer mechanism 410, from the first position to the second position and vice versa. The transfer mechanism 410 comprises a plurality of operative coupled push-pull rods and/or pivoting members 411- 416. The first outer end of the transfer mechanism 410 is formed by a linking element 411 that is rigidly connected to the third bar 133 of the four-bar mechanism 130. The first push-pull bar 412 is pivotally connected to said linking element 411 at a first end and pivotally connected to a transfer mechanism pivoting member 413 at the opposite second end thereof. The transfer mechanism pivoting member 413 is pivotally connected, at hinge section 414, to the frame 200 at a central section thereof and pivotally connected to a first outer section of the first push-pull bar 412 and to the second push-pull bar 415 at an opposite second outer section of the transfer mechanism pivoting member 413. The second push-pull bar 415 is pivotally connected at the opposite end section thereof to the pivoting member 402 that holds the secondary wheel unit 400.

Upon moving the seat assembly 100 to the standing position (as is seen in figures 5 A - 5B), the coupling point 417, wherein linking element 411 is connect to the first push-pull bar 412, moves in at least a backward direction II thereby pushing the first push-pull bar 412 in at last the backward direction, where after the transfer mechanism pivoting member 413 changes the direction of movement, such that the second push-pull rod 415 is pushed in at least the forward direction I. The second push-pull rod 415 is connected to the pivoting arm member 402, in the current embodiment using a ball joint 416, such that the pivoting arm member 402 is urged to pivot and force the secondary wheel unit 400 to the second position. The transfer mechanism 410 thereby ensures that the secondary wheel units 400 are always in the right position with respect to the position of the seat assembly 100. For a smooth operation of the transfer mechanism 400, it is preferred that some, or all, of the respective bars and pivoting members thereof are interconnected by means of ball-joints.

In figure 5A, showing an intermediate position between the sitting and standing positions, an intermediate distance di between the secondary and primary wheels is obtained, that is larger than the first distance di, but smaller than the second distance d2.

The movement from the sitting to the standing position is supported by a pair of actuators 500 that are arranged at opposite sides of the wheelchair 1000. The actuator 500 of the current example are a pair of gas-spring actuators, that provide for an outward pushing force. A first outer end 501 of the actuator is connected to the seat assembly 100, in particular the seat base subframe member 115 (that also forms the first bar 131 of the four-bar mechanism), and the second opposite outer end 502 is connect to the frame 200. Upon activating the actuators 500, using a switch (e.g. button) 504 that is operatively connected through cable 505 with the actuators 500, the actuators 500 provide for an outwardly oriented force and thereby urge the seat base subframe member 115 in an upwardly pivoting direction towards the standing position thereof. The amount of external force required by a user and/or operator to move the stand-up wheelchair 1000 to the standing position can be greatly reduced.

The wheelchair 1000 further comprises an auxiliary manual drive system 600 for driving a respective primary wheel 300, comprising a rotatable auxiliary drive handle 601 that is to move with seat assembly between the sitting and standing positions and is arranged to be rotated by the user. The rotatable auxiliary drive handle 601 is operatively coupled to the respective primary wheel 300 by a drive transfer mechanism 610. The drive transfer mechanism 610 comprises a first pully 611 that is operatively coupled with the rotatable auxiliary drive handle 601 whereby a first drive belt 612 is driven. The first drive belt drives a pair of coaxially arranged second pullies 613, which are arranged substantially coaxially with the hinge axis between the third and fourth bars 133, 134 of the four-bar mechanism. Thereby, the length of the first drive belt 612 (and also the later introduced second drive belt 614) remains constant even if the stand-up wheelchair 1000 is moved from the sitting to the standing position (and vice versa). The secondary pully of the pair of second pullies 613 drives the second drive belt 614, which drives a third pully 615 that is operatively coupled to the primary wheel 300. Thereby, the primary wheels 300 can still be driven by the user in the standing position of the wheelchair 1000.

As can be seen in, for instance, figures 1 and 3, both sides of the wheelchair 1000 are provided with a respective four-bar mechanism 130, transfer mechanism 410, actuator 500 and auxiliary manual drive system 600 such that precise and stable movements are obtained.

Figures 7A and 7B schematically show a second embodiment 2000 of the stand-up wheelchair in a sitting position. The second embodiment 2000 is substantially equal to the first embodiment 1000, with the difference that the gas-spring actuators 500 of the first embodiment 1000 are replaced by electric linear actuators 2500, such that the movement from the sitting to the standing position, and vice versa, can be fully operated by the electric linear actuators 2500, thereby enabling the user to be fully self-sufficient.

Figures 8A and 8B schematically show a third embodiment 3000 of the stand-up wheelchair in a sitting position. The third embodiment 3000 is substantially equal to the first embodiment 1000, with the difference that wheelchair 3000 is not equipped with the transfer mechanism 410 that operatively couples the seat assembly 100 to the secondary wheel units 400. Rather, the secondary wheel units are manually operable using a manual operating mechanism 3410 comprising a handle (e.g. lever) 3411. The lever 3411 is pivotally arranged to the frame 200 and a connecting bar 3412 is arranged for operatively coupling the movement of the pair secondary wheel units 400. Push-pull rods 415 interconnect the lever with the pivoting arm member 402, such that an induced movement of the handle forces the secondary wheel units 400 to the respective first and second position. Moving the secondary wheel units 400 to the respective first and second position is thereby no longer automatically dictated by the sitting or standing position of the seat assembly 100. This can be beneficial when maneuvering the wheelchair 3000 in a standing position through relatively tight spaces.

Figures 9A and 9B schematically show a fourth embodiment 4000 of the stand-up wheelchair in a sitting position. The fourth embodiment 4000 is substantially equal to the third embodiment 3000, with the difference that wheelchair 4000 allows to modify the position of the secondary wheel units 400 independently of each other, as they are both equipped with their individual handles 4401, 4402 that directly allow to move one of said secondary wheel units 400 to a respective first or second position, in the current example by rotating the respective handle 4401, 4402 around the respective axis of rotation Rm, without having to move the other of the secondary wheel units 400. This can also be beneficial when maneuvering the wheelchair 3000 in a standing position through relatively tight spaces.

All the hereabove presented embodiments can be combined for forming further embodiments.

Additionally, the present invention is not limited to the embodiments shown, but also extends to other embodiments falling within the scope of the appended claims.

Claims

1. Stand-up wheelchair, comprising: a seat assembly for seating a user therein, wherein the seat assembly is movable between a sitting position, wherein the user is supported in a sitting posture, and a standing position, wherein the user is supported in a standing posture; a pair of primary wheels for movably supporting the seat assembly on a supporting surface, wherein said primary wheels are arranged on a rear section of the stand-up wheelchair on opposite sides of said wheelchair; at least one secondary wheel unit for movably supporting the seat assembly on the supporting surface, wherein the secondary wheel unit comprises a secondary wheel, in particular a swivel wheel, and wherein the secondary wheel unit is arranged at a frontal section of the stand-up wheelchair; wherein the secondary wheel unit is movable between a first position, wherein the secondary wheel unit, in particular the swivel axis of said swivel wheel, is arranged at a first distance from a primary wheel, and a second position, wherein the secondary wheel unit is arranged at a second distance from the respective primary wheel, wherein the second distance is greater than the first distance; characterized in that: said wheelchair comprises a pivoting arm member whereon the secondary wheel unit is arranged, preferably at a distal section thereof, wherein the pivoting arm member is arranged to pivot around a hinge axis that is arranged perpendicular to the axis of rotation of the secondary wheel, such that, upon rotating the pivoting arm member around the hinge axis, the secondary wheel unit can be moved from the first to the second position and vice versa.

2. Stand-up wheelchair according to claim 1, wherein the secondary wheel unit is arranged to be movable between the first and second position when the seat assembly is moved between the sitting and standing position.

3. Stand-up wheelchair according to claim 1 or 2, wherein the secondary wheel unit is operatively coupled to the seat assembly using a transfer mechanism, such that, upon moving the seat assembly from the sitting to the standing position, the secondary wheel unit is moved, by means of the transfer mechanism, from the first position to the second position and vice versa.

4. Stand-up wheelchair according to claim 1 or 2, wherein the secondary wheel unit is manually operable for moving the secondary wheel unit from the first to the second position, preferably wherein a handle is provided that is operable by a user in the wheelchair for moving the secondary wheel unit from the first to the second position.

5. Stand-up wheelchair according to any of the preceding claims, wherein the stand-up wheelchair further comprises a frame member, wherein said primary wheels and said secondary wheel unit are arranged on the frame member and wherein the seat assembly is connected to the frame member.

6. Stand-up wheelchair according to any of the preceding claims, wherein said secondary wheel unit is movably connected to the frame member, in particular wherein a proximal section of the pivoting arm member is pivotally arranged to the frame, in particular at a frontal section of the frame.

7. Stand-up wheelchair according to any of the preceding claims, wherein said seat assembly at least comprises a seat base, wherein a frontal section of the seat base of the seat assembly is pivotally arranged, in particular pivotally connected to the frame member, such that, upon moving the seat assembly from the sitting to the standing positing, the seat base is pivoted with respect to the supporting surface, such that an angle between the seat base and supporting surface is varied.

8. Stand-up wheelchair according to any of the preceding claims, wherein said seat assembly comprises a seat base and a back rest, wherein a rear section of said seat base is pivotally connected to a lower section of said back rest and wherein, upon moving the seat assembly from the sitting to the standing positing, the seat base is pivoted with respect to the back rest, such that an angle between the seat base and back rest is increased.

9. Stand-up wheelchair according to claim 8, wherein the seat assembly comprises a four-bar mechanism, wherein a first bar of the four-bar mechanism is comprised in the seat base and an adjacent second bar is comprised in the back rest.

10. Stand-up wheelchair according to at least claim 3, wherein the transfer mechanism comprises a plurality of operative coupled push-pull rods, wherein the first outer end of the transfer mechanism, in particular the first push-pull thereof, is operatively coupled to the seat assembly and the second, opposite, outer end of the transfer mechanism, in particular the final push-pull rod thereof, is operatively coupled to the secondary wheel unit.

11. Stand-up wheelchair according to at least claims 5, 10 and 11, wherein the first push-pull rod is connected to one of the bars of the four-bar mechanism, in particular to the third bar that is arranged opposite to the first bar, and wherein the final push-pull rod is connected to the pivoting arm member, such that, upon pivoting the seat base towards the standing position, the secondary wheel unit is automatically and simultaneously pushed, by the final push-pull rod, to the second position and vice versa.

12. Stand-up wheelchair according to any of the preceding claims, wherein the stand-up wheelchair comprises a pair of secondary wheel units that are each movable from a respective first to a respective second position and vice versa, wherein one of said secondary wheel units is arranged on a first side of the wheelchair and the other of said secondary wheel units is arranged on the opposite side of said wheelchair.

13. Stand-up wheelchair according to claim 12, wherein said secondary wheel units are operatively coupled in such a way that they are only allowed to move simultaneously from the first to the second position, and vice versa.

14. Stand-up wheelchair according to any of the preceding claims, further comprising at least one actuator, preferably two actuators, for at least aiding to move the seat assembly towards the standing position, wherein an actuator is preferably a linear actuator, such as a pre-loaded linear gas spring, electric, hydraulic or pneumatic linear actuator that, preferably, extends when moving to the standing position.

15. Stand-up wheelchair according to any of the preceding claims, wherein said stand-up wheelchair is an electrically driving stand-up wheelchair comprising a drive mechanism for driving the primary wheels and, preferably, comprises an electrical actuator for moving the seat assembly from the sitting to the standing position and vice versa.

16. Stand-up wheelchair according to any of the preceding claims 1 - 14, wherein said stand-up wheelchair is a non-powered wheelchair that is arranged to be manually driven by the user and/or arranged to be manually pushed, preferably, comprising a pre-loaded linear gas spring for aiding to move the seat assembly towards the standing position.

17. Stand-up wheelchair according to any of the preceding claims, further comprising at least one auxiliary manual drive system for driving a respective primary wheel, comprising a rotatable auxiliary drive handle that is to move with seat assembly between the sitting and standing positions and is arranged to be rotated by the user, wherein a respective rotatable auxiliary drive handle is operatively coupled to the respective primary wheel by a drive transfer mechanisms, preferably comprising a series of drive bels and/or chains, such that a user is able to manually rotate the respective primary wheel in both the sitting and standing positions by rotating the respective rotatable auxiliary drive handle.

18. Stand-up wheelchair according to any of the preceding claims, wherein each side of the wheelchair is provided with a respective actuator, a respective transfer mechanism, a respective drive system and/or a respective auxiliary manual drive system, wherein the stand-up wheelchair is preferably arranged to be substantially mirror-symmetric over a mirror plane that is substantially perpendicular to the seat base and/or axis of rotation of the primary wheels.