There is described a wheelchair comprising a wheelchair frame, a pair of drive wheels configured to contact a ground surface when the wheelchair is in use, each drive wheel rotating about an axis of rotation, at least one front wheel mounted to a front-end portion of the wheelchair frame, and an anti-tip assembly mounted to a rear-end portion of the wheelchair frame, which anti-tip assembly includes at least one pivot arm that is supported onto the rear-end portion of the wheelchair frame so as to be pivotable with respect to the wheelchair frame about a pivot axis. The pivot arm includes a drive wheel attachment point coinciding with the axis of rotation and providing attachment of at least one of the drive wheels and a wheelchair frame attachment point coinciding with the pivot axis and providing attachment of the pivot arm to the rear-end portion of the wheelchair frame. The anti-tip assembly further comprises a rear wheel that is provided at a distal end of the pivot arm, rearward of the drive wheels, and that is configured to contact the ground surface when the wheelchair is in use. The anti-tip assembly is configured to allow the wheelchair frame to tilt backwards into a predetermined stable titled position with the at least one front wheel in a raised position above the ground surface, while the drive wheels and the rear wheel remain in contact with the ground surface. In one embodiment, the pivot arm is attached, via the wheelchair frame attachment point, to a bracket of the wheelchair frame, which bracket is provided with an arcuate opening configured to allow passage of a drive wheel axis of the drive wheel, which drive wheel axis is coupled to the pivot arm, via the drive wheel attachment point, the arcuate opening defining a predetermined range of pivoting movement of the pivot arm with respect to the wheelchair frame.

TECHNICAL FIELD

The present invention generally relates to a wheelchair of the type comprising an anti-tip assembly intended to increase maneuverability while preventing the wheelchair from tipping backwards.

BACKGROUND OF THE INVENTION

Anti-tip wheelchairs are known as such in the art.

U.S. Pat. No. 7,694,990 B2, which is incorporated herein by reference in its entirety, discloses an anti-tip wheelchair comprising a wheelchair frame, a pair of drive wheels configured to contact a ground surface when the wheelchair is in use, each drive wheel rotating about an axis of rotation, at least one front wheel mounted to a front-end portion of the wheelchair frame, and an anti-tip assembly mounted to a rear-end portion of the wheelchair frame, which anti-tip assembly includes at least one pivot arm that is supported onto the rear-end portion of the wheelchair frame so as to be pivotable with respect to the wheelchair frame about a pivot axis. The pivot arm includes a drive wheel attachment point configured to provide attachment of at least one of the drive wheels, which drive wheel attachment point coincides with the axis of rotation of the drive wheel, and a wheelchair frame attachment point configured to provide attachment of the pivot arm to the rear-end portion of the wheelchair frame, which wheelchair frame attachment point coincides with the pivot axis of the pivot arm. A rear wheel is further provided at a distal end of the pivot arm, rearward of the drive wheels, which rear wheel is configured to contact the ground surface when the wheelchair is in use. A stop device is further mounted on the pivot arm or the wheelchair frame to limit pivoting movement of the pivot arm with respect to the wheelchair frame. The anti-tip assembly is configured to allow the wheelchair frame to tilt backwards into a predetermined stable titled position with the at least one front wheel in a raised position above the ground surface, while the drive wheels and the rear wheel remain in contact with the ground surface.

U.S. Pat. No. 7,694,990 B2 further discloses a drive wheel lock assembly mounted on the front-end portion of the wheelchair frame, on both sides of the wheelchair frame, and configured to apply a wheel lock to each of the drive wheels. In one embodiment, the drive wheel lock assembly includes a wheel engaging element (e.g. a brake shoe) mounted on the front of the wheelchair frame, which wheel engaging element is configured to be selectively engageable with a portion of the outer circumference of the drive wheel. Application of the wheel lock is achieved by selective actuation of a user-operable handle that is mechanically coupled to the wheel engaging element via an articulated linkage. In another embodiment, the user-operable handle is mechanically coupled to the wheel engaging element via a cable. In both embodiments, the wheel engaging element is mounted on the wheelchair frame frontward of the drive wheel and below the axis of rotation of the drive wheel in order to provide increased locking force to the drive wheel upon tilting the wheelchair backwards and prevent inadvertent release of the wheel lock.

European Patent Publication No. EP 2 243 453 A1 discloses a wheelchair of the type comprising a drive wheel lock assembly that is configured to apply a wheel lock to the wheelchair's drive wheels, which drive wheel lock assembly comprises a wheel engaging element mounted on a pivot arm and configured to be selectively engageable with the associated drive wheel rearward thereof, namely by pivotal movement of the wheel engaging element. A control assembly is coupled to the relevant drive wheel lock assembly via a connection line to control pneumatic operation of the wheel engaging element. No particular cable-operated drive wheel lock assembly is contemplated.

According to U.S. Pat. No. 7,694,990 B2, a tilt prevention device may optionally be mounted on the wheelchair frame, pivot arm or another portion of the wheelchair to prevent any pivoting movement of the pivot arm with respect to the wheelchair frame, and thereby prevent any tilting movement of the wheelchair. No particular embodiment of such a tilt prevention device is however specifically disclosed in U.S. Pat. No. 7,694,990 B2.

Japanese Patent Publication No. JP H04-158864 A discloses an anti-tip wheelchair likewise comprising a support member configured as a pivot arm that is provided, at a distal end thereof, with a rear wheel and including a drive wheel attachment point configured to provide attachment of at least one of the drive wheels.

U.S. Pat. No. 6,530,598 B1 discloses another type of anti-tip wheelchair, which differs from the anti-tip wheelchair of U.S. Pat. No. 7,694,990 B2 in that the drive wheels are supported directly onto the wheelchair frame, and not on the anti-tip assembly, and in that the rear wheel provided at the distal end of the pivot arm only comes into contact with the ground surface upon tilting the wheelchair backwards, which is less desirable from the point of view of wheelchair stability and maneuverability. The anti-tip wheelchair of U.S. Pat. No. 7,694,990 B2 therefore remains a more adequate solution from a practical perspective.

This being said further improvements of the anti-tip wheelchair concept disclosed e.g. in U.S. Pat. No. 7,694,990 B2 are desirable in order to make it more robust and easier to operate and handle for the user.

SUMMARY OF THE INVENTION

A general aim of the invention is to provide an improved anti-tip wheelchair of the type disclosed in U.S. Pat. No. 7,694,990 B2.

Yet another aim of the invention is to provide such a wheelchair having an anti-tip assembly of simpler and more robust and reliable construction.

A further aim of the invention is to provide such a wheelchair where a range of pivoting movement of the pivot arm can be selectively limited by the user.

Still another aim of the invention is to provide such a wheelchair which ensures a correct positioning of the rear wheel that is provided at the distal end of the pivot arm with respect to the ground surface with which it is designed to come into contact.

A further aim of the invention is to provide such a wheelchair which includes a more robust drive wheel lock assembly to apply a wheel lock to at least one of the drive wheels.

These aims are achieved thanks to the solutions defined in the claims.

In accordance with a first aspect of the invention, there is provided a wheelchair as defined in claim1, namely a wheelchair comprising a wheelchair frame, a pair of drive wheels configured to contact a ground surface when the wheelchair is in use, each drive wheel rotating about an axis of rotation, at least one front wheel mounted to a front-end portion of the wheelchair frame, and an anti-tip assembly mounted to a rear-end portion of the wheelchair frame, which anti-tip assembly includes at least one pivot arm that is supported onto the rear-end portion of the wheelchair frame so as to be pivotable with respect to the wheelchair frame about a pivot axis. The pivot arm includes a drive wheel attachment point configured to provide attachment of at least one of the drive wheels, which drive wheel attachment point coincides with the axis of rotation of the drive wheel, and a wheelchair frame attachment point configured to provide attachment of the pivot arm to the rear-end portion of the wheelchair frame, which wheelchair frame attachment point coincides with the pivot axis of the pivot arm. The anti-tip assembly further comprises a rear wheel that is provided at a distal end of the pivot arm, rearward of the drive wheels, which rear wheel is configured to contact the ground surface when the wheelchair is in use. The anti-tip assembly is configured to allow the wheelchair frame to tilt backwards into a predetermined stable titled position with the at least one front wheel in a raised position above the ground surface, while the drive wheels and the rear wheel remain in contact with the ground surface. According to this first aspect of the invention, the pivot arm is attached, via the wheelchair frame attachment point, to a bracket of the wheelchair frame, which bracket is provided with an arcuate opening configured to allow passage of a drive wheel axis of the drive wheel. The drive wheel axis is coupled to the pivot arm, via the drive wheel attachment point, the arcuate opening defining a predetermined range of pivoting movement of the pivot arm with respect to the wheelchair frame.

By way of preference, a front portion of the pivot arm, which is coupled to the bracket and to the drive wheel, is configured as a fork member laterally surrounding the bracket.

According to a preferred variant of the wheelchair, the anti-tip assembly further comprises a tilt angle limiting device that is configured to be movable between a first position in which the pivot arm is allowed to pivot with respect to the wheelchair frame over the predetermined range of pivoting movement and at least a second position in which the pivot arm is not allowed to pivot with respect to the wheelchair frame over the full predetermined range of pivoting movement.

The provision of this tilt angle limiting device constitutes a second aspect of the present invention, which is applicable independently of the first aspect of the invention. In that regard, in accordance with a second aspect of the invention, there is provided a wheelchair as defined in independent claim4, namely a wheelchair comprising a wheelchair frame, a pair of drive wheels configured to contact a ground surface when the wheelchair is in use, each drive wheel rotating about an axis of rotation, at least one front wheel mounted to a front-end portion of the wheelchair frame, and an anti-tip assembly mounted to a rear-end portion of the wheelchair frame, which anti-tip assembly includes at least one pivot arm that is supported onto the rear-end portion of the wheelchair frame so as to be pivotable with respect to the wheelchair frame about a pivot axis. The pivot arm includes a drive wheel attachment point configured to provide attachment of at least one of the drive wheels, which drive wheel attachment point coincides with the axis of rotation of the drive wheel, and a wheelchair frame attachment point configured to provide attachment of the pivot arm to the rear-end portion of the wheelchair frame, which wheelchair frame attachment point coincides with the pivot axis of the pivot arm. The anti-tip assembly further comprises a rear wheel that is provided at a distal end of the pivot arm, rearward of the drive wheels, which rear wheel is configured to contact the ground surface when the wheelchair is in use. The anti-tip assembly is configured to allow the wheelchair frame to tilt backwards into a predetermined stable titled position with the at least one front wheel in a raised position above the ground surface, while the drive wheels and the rear wheel remain in contact with the ground surface. According to this second aspect of the invention, the anti-tip assembly further comprises a tilt angle limiting device that is configured to be movable between a first position in which the pivot arm is allowed to pivot with respect to the wheelchair frame over a predetermined range of pivoting movement and at least a second position in which the pivot arm is not allowed to pivot with respect to the wheelchair frame over the full predetermined range of pivoting movement.

Advantageously, the first position may be a position in which the tilt angle limiting device is disengaged and allows the pivot arm to pivot with respect to the wheelchair frame over a predetermined range of pivoting movement and the second position is a position in which the tilt angle limiting device is engaged and prevents the pivot arm from pivoting with respect to the wheelchair frame over the full predetermined range of pivoting movement. In this context, the aforementioned tilt angle limiting device preferably comprises a lever mounted onto the pivot arm and adapted to pivot with respect to the pivot arm between the first and second positions. This lever may in particular comprise a portion configured to limit pivoting movement of the pivot arm with respect to the wheelchair frame when the lever is pivoted to the second position.

According to a variant of the aforementioned wheelchairs, a position of a swivel member of the rear wheel with respect to the pivot arm is adjustable so that a swivel axis of the swivel member can be adjusted to be substantially perpendicular to the ground surface. By way of preference, the swivel member is repositionable with respect to the pivot arm by translation along the swivel axis.

This adjustability of the swivel member of the rear wheel constitutes another aspect of the present invention, which is applicable independently of the first and second aspects of the invention. In that regard, in accordance with a third aspect of the invention, there is provided a wheelchair as defined in independent claim10, namely a wheelchair comprising a wheelchair frame, a pair of drive wheels configured to contact a ground surface when the wheelchair is in use, each drive wheel rotating about an axis of rotation, at least one front wheel mounted to a front-end portion of the wheelchair frame, and an anti-tip assembly mounted to a rear-end portion of the wheelchair frame, which anti-tip assembly includes at least one pivot arm that is supported onto the rear-end portion of the wheelchair frame so as to be pivotable with respect to the wheelchair frame about a pivot axis. The pivot arm includes a drive wheel attachment point configured to provide attachment of at least one of the drive wheels, which drive wheel attachment point coincides with the axis of rotation of the drive wheel, and a wheelchair frame attachment point configured to provide attachment of the pivot arm to the rear-end portion of the wheelchair frame, which wheelchair frame attachment point coincides with the pivot axis of the pivot arm. The anti-tip assembly further comprises a rear wheel that is provided at a distal end of the pivot arm, rearward of the drive wheels, which rear wheel is configured to contact the ground surface when the wheelchair is in use. The anti-tip assembly is configured to allow the wheelchair frame to tilt backwards into a predetermined stable titled position with the at least one front wheel in a raised position above the ground surface, while the drive wheels and the rear wheel remain in contact with the ground surface. According to this third aspect of the invention, a position of a swivel member of the rear wheel with respect to the pivot arm is adjustable so that a swivel axis of the swivel member can be adjusted to be substantially perpendicular to the ground surface, and the swivel member is repositionable with respect to the pivot arm by translation along the swivel axis.

In this context, the swivel member may in particular be held onto the pivot arm by means of a releasable clamping element.

According to yet another variant of the aforementioned wheelchairs, the anti-tip assembly further comprises at least one drive wheel lock assembly configured to apply a wheel lock to at least one of the drive wheels, which drive wheel lock assembly comprises a wheel engaging element that is mounted on the pivot arm and configured to be selectively engageable with the drive wheel rearward of the drive wheel.

By way of preference, the drive wheel lock assembly is a cable-operated drive wheel lock assembly comprising a user-operable handle coupled to the wheel engaging element via a cable. In this context, a position of the wheel engaging element along the pivot arm may advantageously be adjustable.

This cable-operated drive wheel lock assembly constitutes yet another aspect of the present invention, which is applicable independently of the first to third aspects of the invention. In that regard, in accordance with a fourth aspect of the invention, there is provided a wheelchair as defined in independent claim15, namely a wheelchair comprising a wheelchair frame, a pair of drive wheels configured to contact a ground surface when the wheelchair is in use, each drive wheel rotating about an axis of rotation, at least one front wheel mounted to a front-end portion of the wheelchair frame, and an anti-tip assembly mounted to a rear-end portion of the wheelchair frame, which anti-tip assembly includes at least one pivot arm that is supported onto the rear-end portion of the wheelchair frame so as to be pivotable with respect to the wheelchair frame about a pivot axis. The pivot arm includes a drive wheel attachment point configured to provide attachment of at least one of the drive wheels, which drive wheel attachment point coincides with the axis of rotation of the drive wheel, and a wheelchair frame attachment point configured to provide attachment of the pivot arm to the rear-end portion of the wheelchair frame, which wheelchair frame attachment point coincides with the pivot axis of the pivot arm. The anti-tip assembly further comprises a rear wheel that is provided at a distal end of the pivot arm, rearward of the drive wheels, which rear wheel is configured to contact the ground surface when the wheelchair is in use. The anti-tip assembly is configured to allow the wheelchair frame to tilt backwards into a predetermined stable titled position with the at least one front wheel in a raised position above the ground surface, while the drive wheels and the rear wheel remain in contact with the ground surface. In addition, the anti-tip assembly further comprises at least one drive wheel lock assembly configured to apply a wheel lock to at least one of the drive wheels, which drive wheel lock assembly comprises a wheel engaging element that is mounted on the pivot arm and configured to be selectively engageable with the drive wheel rearward of the drive wheel. According to this fourth aspect of the invention, the drive wheel lock assembly is a cable-operated drive wheel lock assembly comprising a user-operable handle coupled to the wheel engaging element via a cable, and a position of the wheel engaging element along the pivot arm is adjustable.

By way of preference, the wheel engaging element may be configured to pivot with respect to the pivot arm upon being operated.

With regard to the adjustability of the position of the wheel engaging element along the pivot arm, the pivot arm may in particular be provided with a mounting groove extending longitudinally along a lateral side of the pivot arm, the wheel engaging element being releasably mounted in the mounting groove and repositionable along the mounting groove. The mounting groove may further be exploited so that part of the cable is guide inside a portion of the mounting groove.

Further advantageous embodiments of the invention are discussed below.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

The present invention will be described in relation to various illustrative embodiments. It shall be understood that the scope of the invention encompasses all combinations and sub-combinations of the features of the embodiments disclosed herein.

As described herein, when two or more parts or components are described as being connected, secured or coupled to one another, they can be so connected, secured or coupled directly to each other or through one or more intermediary parts.

The invention will be described in relation to various embodiments of an anti-tip wheelchair as shown inFIGS. 1 to 5A-D.

FIG. 1is a schematic side view of a wheelchair, designated generally by reference numeral1, in accordance with a preferred embodiment of the invention. The wheelchair1comprises a wheelchair frame10supporting a seat portion5and a pair of drive wheels20configured to contact a ground surface S when the wheelchair1is in use, as shown inFIG. 1. In the illustrated example, each drive wheel20includes a hand rim21allowing the user to wheel the wheelchair1. At least one front wheel30is mounted to a front-end portion10A of the wheelchair frame10. In the illustrated example a pair of front wheels30is provided at the front-end portion10A of the wheelchair frame10on either side. The front wheels30are designed as pivotable caster wheels, as is known in the art, each front wheel30being carried by a corresponding fork element30cconfigured to be pivotable about a substantially vertical swivel axis.

The wheelchair1further comprises an anti-tip assembly50mounted to a rear-end portion10B of the wheelchair frame10, the general configuration of which is similar to the anti-tip assembly taught in U.S. Pat. No. 7,694,990 B2, but incorporates a number of improvements.

FIG. 1Ais a schematic side view of the wheelchair1ofFIG. 1where the drive wheels20have been omitted to reveal the structure of the anti-tip assembly50. As shown inFIG. 1A, the anti-tip assembly50includes at least one pivot arm51that is supported on the rear-end portion10B of the wheelchair frame10so as to be pivotable with respect to the wheelchair frame10about a pivot axis PA. A single pivot arm could be provided. In the illustrated example, the anti-tip assembly50comprises a pair of pivot arms51located on the left-hand and right-hand sides of the wheelchair1next to and inward from the drive wheels20. More specifically, each pivot arm51is pivotably supported, at a front portion51.1, onto a bracket100of the wheelchair frame10, which bracket100is here secured between upper and lower longitudinal frame members10.1,10.2.

Each pivot arm51includes a drive wheel attachment point520configured to provide attachment of a respective one of the drive wheels20, which drive wheel attachment point520coincides with an axis of rotation RA of the drive wheel20. Each pivot arm51further includes a wheelchair frame attachment point510configured to provide attachment of the pivot arm51to the rear-end portion10B of the wheelchair frame10, namely to a corresponding portion of the bracket100. The wheelchair frame attachment point510coincides with the pivot axis PA of the pivot arm51.

The anti-tip assembly50further comprises a rear wheel55that is provided at a distal end51A of the pivot arm51, rearward of the drive wheels20, which rear wheel55is configured to contact the ground surface S when the wheelchair1is in use as shown inFIGS. 1 and 1A. The rear wheel55is designed as a pivotable caster wheel, much like the front wheels30, and is likewise carried by a fork element55cconfigured to pivot about a swivel axis SA. Reference sign55ainFIGS. 1 and 1Adesignates a swivel member to which the fork element55cis pivotably attached, while reference sign55bdesignates a clamping element configured to hold the swivel member55aat the distal end51A of the pivot arm51.

In the illustrated embodiment, one will appreciate that the wheelchair1includes a total of six wheels, namely two drive wheels20, two front wheels30and two rear wheels55.

In a manner similar to the known anti-tip assembly disclosed in U.S. Pat. No. 7,694,990 B2, the anti-tip assembly50is configured to allow the wheelchair frame10to tilt backwards into a predetermined stable tilted position, as illustrated inFIG. 1B, with the front wheels30in a raised position above the ground surface S, while the drive wheels20and the rear wheels55remain in contact with the ground surface S, allowing the user e.g. to climb over curbs or the like. One major advantage of the wheelchair concept of the present invention, like the wheelchair concept of U.S. Pat. No. 7,694,990 B2, resides in the improved stability and maneuverability, as well as the guarantee that the wheelchair1cannot inadvertently tip backwards beyond the position shown inFIG. 1B.

A first improvement of the wheelchair concept over the known solution disclosed U.S. Pat. No. 7,694,990 B2 resides in the manner in which a predetermined range of pivoting movement of the pivot arm(s) of the anti-tip assembly is achieved, and will be discussed with reference toFIGS. 5A-C.

According to U.S. Pat. No. 7,694,990 B2, a dedicated stop device is provided on the pivot arm or the wheelchair frame to limit the amplitude of pivoting movement of the pivot arm, which therefore necessitates the provision of additional wheelchair parts and components. According to the present invention, no such additional parts and components are required.

As shown inFIGS. 5A-C, the bracket100is advantageously provided with an arcuate opening100A (see in particularFIGS. 5B and 5Cwhere the front portion51.1of the pivot arm51is shown in transparency) configured to allow passage of a drive wheel axis25of the drive wheel20, which drive wheel axis25is coupled to the pivot arm51, via the drive wheel attachment point520. This arcuate opening100A defines a predetermined range of pivoting movement of the pivot arm51with respect to the wheelchair frame10.

InFIGS. 5A and 5B, the pivot arm51is shown in an intermediate position relative to the bracket100, with the drive wheel axis25sitting in a position where it does not come into abutment with either one of the two ends of the arcuate opening100A. InFIG. 5C, the pivot arm51is shown pivoted to an extreme position (corresponding to the tilted position of the wheelchair1shown inFIG. 1B), with the drive wheel axis25coming in abutment with the lower end of the arcuate opening100A.

One will thus appreciate that the arcuate opening100A provided in the bracket100and the drive wheel axis25jointly fulfil the function of limiting the amplitude of pivoting movement of the pivot arm51with respect to the wheelchair frame10.

By way of preference, the front portion51.1of the pivot arm51, which is coupled to the bracket100and to the drive wheel20, is configured as a fork member laterally surrounding the bracket100. In other words, a pair of wheelchair attachment points510and a pair of drive wheel attachment points520are provided on the front portion51.1of the pivot arm51, on both sides of the bracket100, ensuring optimal mechanical stability of the coupling between the pivot arm51, the bracket100and the drive wheel20. Robust and reliable pivoting movement of the pivot arm51with respect to the bracket100is advantageously ensured by the provision of ball bearings at the pivot joint between the bracket100and the pivot arm51.

A second improvement of the wheelchair concept over the known solution disclosed U.S. Pat. No. 7,694,990 B2 will be discussed with reference toFIGS. 3B to 5A-D. The second improvement resides in the provision of a tilt angle limiting device, designated by reference numeral70, that is configured to be movable between a first position in which the pivot arm51is allowed to pivot with respect to the wheelchair frame10over the predetermined range of pivoting movement and at least a second position in which the pivot arm51is not allowed to pivot with respect to the wheelchair frame10over the full predetermined range of pivoting movement.

By way of preference, the first position of the tilt angle limiting device70is a position in which the tilt angle limiting device70is disengaged and allows the pivot arm51to pivot with respect to the wheelchair frame10over a predetermined range of pivoting movement. Conversely, the second position of the tilt angle limiting device70is a position in which the tilt angle limiting device70is engaged and prevents the pivot arm51from pivoting with respect to the wheelchair frame10over the full predetermined range of pivoting movement.

More specifically, in accordance with a particularly preferred embodiment, as illustrated, the tilt angle limiting device70comprises a lever75mounted onto the pivot arm51and adapted to pivot with respect to the pivot arm51, about a pivot axis PA3, between the first and second positions.FIGS. 5A-C(see alsoFIGS. 1-4) show the lever75in a first, inactive (or disengaged) position. In this first position, the pivot arm51is free to move with respect to the bracket100within the predetermined range of pivoting movement.FIG. 5Dshows the lever pivoted in a second, active (or engaged) position, toward a rear side of the bracket100. In this second position, the range of pivoting movement of the pivot arm51is greatly restricted.

A stop element may be secured to the lever75in such a way as to come in abutment with a portion of the bracket100(or another portion of the wheelchair frame10), when the lever75is moved to the second position, to prevent the pivot arm51from moving over the full predetermined range of pivoting movement.

A particularly simple and robust solution may consist in designing the lever75in such a way as to directly act as the stop element. For instance, as illustrated inFIGS. 3B to 5A-D, the lever75may exhibit a substantially U-shaped configuration, with a portion75A that is configured to limit pivoting movement of the pivot arm51with respect to the wheelchair frame. Upon pivoting the lever75from the first position to the second position, the portion75A is brought in close proximity to the rear end of the bracket100, thereby substantially reducing the amplitude of pivoting movement of the pivot arm51.

The aforementioned lever75constitutes a particularly simple and robust solution to limit the amplitude of pivoting movement of the pivot arm51, and thereby the tilt angle of the wheelchair1.

A further improvement of the wheelchair concept over the known solution disclosed U.S. Pat. No. 7,694,990 B2 resides in the positioning of the rear wheel55at the distal end51A of the pivot arm51. Indeed, considering that the drive wheel20is carried at one end of the pivot arm51and that the rear wheel55is positioned at the other, distal end51A of the pivot arm51, the actual diameters of the drive wheel20and rear wheel55, which may vary, will directly impact the orientation of the pivot arm51and therefore the angle formed by the swivel axis SA of the rear wheel55with respect to the ground surface S. It may in particular be desirable to allow mounting of rear wheels55of different dimensions, such as e.g. 5″ or 6″ wheels, which will directly impact the geometry of the anti-tip assembly50. In order to ensure optimal drivability and avoid fluttering of the rear wheel55, the swivel axis SA should be set to be substantially perpendicular to the ground surface S. To this end, a position of the swivel member55awith respect to the pivot arm51is advantageously adjustable.

One solution may consist in positioning the rear wheel55at the distal end51A of the pivot arm51in such a way that the swivel member55acan be rotated with respect to the pivot arm51and thereby adjust the angle of the swivel member55a,similar to the type of adjustment mechanisms used to adjust the angle of front caster wheels (see e.g. German Utility Model No. DE 298 17 702 U1). A simpler and more advantageous solution may however consist, as shown inFIGS. 2, 3B and 4, in designing the swivel member55aso as to be repositionable with respect to the pivot arm51by translation along the swivel axis SA. Indeed, translation of the swivel member55awith respect to the pivot arm51will cause the pivot arm51to be correspondingly raised or lowered at the distal end51A and pivot about the pivot axis PA, achieving the desired adjustment of the angle of the swivel member55aand swivel axis SA. By way of preference, the clamping element55bis designed to be releasable so as to selectively allow the swivel member55ato be moved along its axis SA and be repositioned at the desired location. Adjustment of the angle of the swivel axis SA of the rear wheel55can therefore be performed very easily.

Yet another improvement of the wheelchair concept over the known solution disclosed U.S. Pat. No. 7,694,990 B2 will now be discussed with reference toFIGS. 2 to 3A-B, which illustrate the provision of a drive wheel lock assembly60configured to apply a wheel lock to the drive wheel20. In contrast to the solutions disclosed in U.S. Pat. No. 7,694,990 B2, the drive wheel lock assembly60comprises a wheel engaging element62that is mounted directly on the pivot arm51, namely on a lateral side thereof, and that is configured to be selectively engageable with the drive wheel20rearward of the drive wheel20. This configuration has the advantage that tilting of the wheelchair1will not have any impact on the applied wheel lock as the wheel engaging element62does not move relative to the drive wheel20during the tilting movement.

By way of preference, the drive wheel lock assembly60is cable-operated and comprises a user-operable handle61, located at the front-end portion10A of the wheelchair frame10, coupled to the wheel engaging element62via a cable65(seeFIGS. 1, 1A-B and3A). As shown inFIGS. 1A, 3A and 3B, the cable65runs from the user-operable handle61under a portion of the upper longitudinal frame member10.1, along the bracket100and pivot arm51, to the wheel engaging element62. The wheel engaging element62is preferably configured so as to pivot with respect to the pivot arm51upon being operated, reference sign PA2designating a pivot axis of the wheel engaging element62. Reference sign65binFIG. 3Adesignates a cable-tension adjustment element secured to a lower side of the upper longitudinal frame element10.1and used to adjust tension of the cable65, while reference sign65cinFIG. 3Bdesignates a cable guide element secured to a lateral side of the pivot arm51, upstream of the position of the wheel engaging element62. Reference sign65adesignates a cable guide guiding the cable65along the upper longitudinal frame member10.1, the bracket100and the pivot arm51, which cable guide65aruns from the cable-tension adjustment element65bto the cable guide element65c.

By way of preference, a position of the wheel engaging element62along the pivot arm51is adjustable to cope with varying drive wheel sizes. In that respect, the pivot arm51is preferably provided with a mounting groove560extending longitudinally along a lateral side of the pivot arm51, the wheel engaging element62being releasably mounted in the mounting groove560and repositionable along the mounting groove560. As shown inFIG. 3B, the cable guide65amay be routed through a portion of the mounting groove560to guide part of the cable65to the inner section of the front portion51.1of the pivot arm51where the pivot arm51is coupled to the bracket100.

Various modifications and/or improvements may be made to the above-described embodiments without departing from the scope of the invention as defined by the appended claims. In particular, the anti-tip assembly50can include a pair of pivot arms51, as discussed above, or a single pivot arm provided along a median plane of the wheelchair.

In addition, a drive lock assembly could be provided on both lateral sides of the wheelchair1to apply a wheel lock on each drive wheel.

LIST OF REFERENCE NUMERALS AND SIGNS USED THEREIN

1wheelchair5seat portion10wheelchair frame10.1upper longitudinal frame member10.2lower longitudinal frame member10A front-end portion of wheelchair frame1010B rear-end portion of wheelchair frame1020pair of drive wheels21hand rim25drive wheel axis of drive wheel2030front wheel (pivotable caster wheel)30cfork element carrying front wheel3050anti-tip assembly51pivot arm51.1front portion of pivot arm51coupled to wheelchair frame10and drive wheel2051A distal end of pivot arm51, rearward of drive wheel2055rear wheel (pivotable caster wheel) provided at distal end51A of pivot arm5155aswivel member of rear wheel5555breleasable clamping element holding swivel member55aof rear wheel5555cfork element carrying rear wheel5560(cable-operated) drive wheel lock assembly configured to apply a wheel lock to drive wheel2061user-operable handle62wheel engaging element65cable connecting user-operable handle61to wheel engaging element6265acable guide65bcable-tension adjustment element65ccable guide element70tilt angle limiting device75pivotable lever of tilt angle limiting device70/pivotable between an inactive position (FIGS. 1-5A-C) and an active position (FIG. 5D)75A portion of pivotable lever75configured to limit pivoting movement of pivot arm51with respect to wheelchair frame10when pivotable lever75is pivoted to an active position (FIG. 5D)100(rear) bracket of wheelchair frame10supporting anti-tip assembly50100A arcuate opening formed in bracket100510wheelchair frame attachment point (coincides with pivot axis PA of pivot arm51)520drive wheel attachment point (coincide with axis of rotation RA of drive wheel20)560mounting groove extending longitudinally along a lateral side of pivot arm51for releasable mounting of wheel engaging element62S ground surfacePA pivot axis of pivot arm51PA2pivot axis of wheel engaging element62PA3pivot axis of pivotable lever75RA axis of rotation of drive wheel20SA swivel axis of swivel member55a