Wheelchair wheel system

Abstract

Wheelchair wheel system Wheel system (14,16) comprising a wheel (34) having a hub (36) having a main axis (X), the hub comprising an inner face (37) provided with an internal conical surface (38); a tubular element (22); a main shaft (20) engaged in said tubular element; a handrail (24) comprising an extension portion having a threaded part (30); a brake pad (56) having a braking surface (59) and a first conical surface (57); a coupling member (40) movable in axial translation between a first position in which it rotationally links the handrail and the hub, and a second position for braking the hub; a free wheel (44) disposed between the tubular element and the hub; and a locking piece (74) for locking the tubular element in rotation relative to the frame Figure for the abbreviation: Fig. 1.

Description

Title of the invention: Wheelchair wheel system technical field

[0001] The present invention relates to the technical field of wheelchairs and more specifically to the field of wheel systems for such wheelchairs. Wheel systems traditionally comprise a wheel having a hub and a drive mechanism for this wheel relative to the wheelchair frame.

[0002] The present invention relates in particular to wheel systems comprising a handrail coupled to the wheel and enabling the wheel to be driven in rotation forwards and backwards, but also enabling the wheel to be braked. Prior art

[0003] A wheelchair equipped with a wheel system such as that described in document WO2019193277 is known. The wheel system of this document comprises a first shaft portion on which is mounted a handrim extension portion cooperating with a coupling member movable in axial translation. The coupling member allows the wheel and the handrim to be rotationally coupled when it is in a first position, for driving the wheel forward. The coupling member can also assume a second position in which it radially pushes a brake pad against the hub, allowing the wheel to be braked but also for driving the wheel backward.

[0004] One drawback of this wheel system is that it comprises two shaft segments that rotate relative to each other. The first shaft segment is configured to be pivotally mounted to the wheelchair frame via a freewheel having an inner ring attached to a second shaft segment fixed to the frame. The degree of freedom between the first and second shaft segments risks generating significant play, particularly in the angular travel of the handrim, but also in the axial movement of the coupling element, which is undesirable. Given this residual play, the user may have to rotate the handrim through a relatively large angular travel when unloaded before it drives the wheel forward or before the wheel brakes.This angular movement of the handrail when unloaded reduces the maneuverability of the wheel system and gives the user a feeling of insecurity, as the braking of the wheelchair is not immediate.

[0005] Furthermore, the extension portion of the handrail of this wheel system is mounted directly onto the first shaft portion via a bearing. Similarly, the inner ring of the freewheel is fixed directly to the second shaft section. Furthermore, the second shaft section is prevented from rotating relative to the frame by means of a locking piece mounted directly on the second shaft section. In other words, a separate mounting solution is used for the respective mounting of the handrail extension section, the freewheel inner ring, and the locking piece on the main shaft sections.

[0006] Mounting these different elements directly onto the first and second shaft sections can prove difficult and requires adapting these shaft sections for mounting, in particular by providing grooves, notches, flats and / or by associating mounting means specific to each of these elements.

[0007] Furthermore, the prior art wheel system makes the shaft sections difficult to access. In particular, it is necessary to substantially dismantle the entire wheel system to replace these shaft sections. Description of the invention

[0008] One object of the present invention is to propose a wheel system that remedies the aforementioned disadvantages.

[0009] To this end, the invention relates to a wheelchair wheel system having a frame, the wheel system comprising: - a wheel having a hub with a main axis, the hub comprising an inner face provided with an internal conical surface; - a main shaft configured to be mounted to the wheelchair frame; - a tubular element extending along the main axis, the main shaft being engaged in said tubular element; - a handrail mounted pivoting around the main axis relative to the tubular element and coupled to the wheel for the rotation drive and braking of the wheel, the handrail comprising a circular actuation portion and an extension portion extending into the hub, said extension portion surrounding the tubular element and having a threaded part; - at least one brake pad located in the hub and comprising a braking surface and at least one first conical surface; - a coupling member comprising a coupling surface, a ramp, and a threaded portion engaged with the threaded portion of the handrail extension portion to axially move the coupling member relative to the hub, the coupling member being movable in axial translation between at least a first position in which its coupling surface bears against the internal conical surface of the hub, so as to rotationally link the handrail and the hub, and a second position in which the ramp of the coupling member bears against the first conical surface of the brake pad to radially push the pad braking against the inner face of the hub; - a freewheel comprising an inner ring fixed relative to the tubular element and an outer ring blocked against rotation relative to the inner ring in a first direction of rotation and free to rotate relative to the inner ring in a second direction of rotation opposite to the first direction of rotation, the wheel hub being pivotally mounted relative to the outer ring of the freewheel, the brake pad being rotationally linked to the outer ring of the freewheel when the coupling member is in the second position; and - a locking piece attached to the tubular element and located opposite the handrail, the locking piece being configured to cooperate with a locking element of the frame for the rotational locking of the tubular element relative to the frame.

[0010] The wheel advantageously comprises a rim connected to the hub, for example by means of spokes. The wheel advantageously comprises a tire mounted on said rim.

[0011] The main shaft preferably extends along the main axis. The main shaft extends at least partially inside the tubular element. The main shaft is preferably cylindrical. The tubular element advantageously has the shape of a sleeve. The tubular element is hollow. Preferably, the main shaft passes through said tubular element. The main shaft is preferably formed from a single piece. The tubular element and the main shaft are preferably coaxial.

[0012] The tubular element advantageously has a length less than the length of the main shaft, preferably a length less than two-thirds of the length of the main shaft. The tubular element advantageously has a length substantially equal to the length of the hub considered along the main axis. The tubular element preferably extends essentially within the hub.

[0013] Without departing from the scope of the invention, the tubular element can be blocked from rotation relative to the main shaft.

[0014] Preferably, the tubular element is blocked in axial translation relative to the main shaft.

[0015] Preferably, the tubular element is locked in axial translation relative to the main shaft when the main shaft is mounted to the wheelchair frame.

[0016] The main shaft preferably includes a nut, fixed to the end of the main shaft, against which the tubular element butts for blocking the tubular element in axial translation relative to the main shaft in a direction of axial movement.

[0017] Preferably, the tubular element or the locking piece is configured to abut against a portion of the frame for axial translational locking of the element tubular relative to the main shaft in another direction of axial displacement.

[0018] The main shaft is preferably configured to be removably mounted to the wheelchair frame

[0019] Preferably, the wheel system includes at least one ring disposed between the main shaft and the tubular element. This ring is preferably fitted onto the main shaft and bears against a shoulder formed inside the tubular element. This ring allows the main shaft to be mounted inside the tubular element. The size of the ring is chosen according to the diameter of the main shaft.

[0020] The main shaft is advantageously configured to extend within a mounting portion, for example, an axle tube, of the wheelchair frame when mounted to said frame. Preferably, the main shaft is configured to be fixed against axial translation relative to the wheelchair frame when mounted to the latter. When mounted to the wheelchair frame, said main shaft can rotate freely about the main axis relative to said frame.

[0021] The tubular element of the wheel system according to the invention constitutes an intermediate mounting part for, in particular, the inner ring of the freewheel, the extension portion of the handrail, and the locking piece. Thanks to the invention, the inner ring of the freewheel, the extension portion of the handrail, and the locking piece are not mounted directly on the main shaft. It is therefore not necessary to modify and adapt the main shaft for the mounting of these elements. The mounting of the freewheel, the handrail, and the locking piece is thus facilitated. The invention also allows the use of a standard, commercially available main shaft that is compatible with all types of wheelchairs.

[0022] The wheel system according to the invention can therefore be mounted and assembled on numerous wheelchairs without substantial modification of the wheel system, since, within the wheel system, only the main axle needs to be selected and adapted to the wheelchair frame. A connector can also be attached to the wheelchair frame, integral with the locking mechanism, to prevent the tubular element from rotating relative to the frame. This connector is preferably fixed to the frame.

[0023] The tubular element of the wheel system according to the invention allows the main shaft to be freed from the hub by disengaging it from said tubular element. It is not necessary to disassemble the other parts and components of the wheel system to change and replace the main shaft.

[0024] Furthermore, the wheel system according to the invention allows the use of a single main shaft locked in translation relative to the frame, unlike prior art wheel systems which use two separate shaft portions. In particular, thanks to the invention, the inner ring of the freewheel is fixed relative to the wheelchair frame. One advantage is to reduce play within the wheel system by reducing the number of parts and therefore the number of degrees of freedom between the parts composing the wheel system.

[0025] The hub is preferably mounted to pivot relative to the outer ring of the freewheel about the main axis. The wheel system preferably includes an external bearing, for example a ball bearing, disposed between the outer ring of the freewheel and the inner face of the hub. Advantageously, the freewheel is a cam-type freewheel.

[0026] The free wheel is preferably located between the extension portion of the handrail and the locking piece.

[0027] Preferably, the wheel system comprises two brake pads. The brake pads preferably extend on either side of the tubular element.

[0028] In the first direction of rotation, the outer ring of the freewheel is locked against rotation relative to the inner ring, whereas in the second direction of rotation, the outer ring is free to rotate relative to the inner ring. Therefore, when the brake pad is rotationally coupled to the outer ring of the freewheel, it is consequently locked against rotation relative to the inner ring of the freewheel, and thus relative to the tubular element, in the first direction of rotation, and free to rotate relative to the inner ring, and thus to the tubular element, in the second direction of rotation.

[0029] Preferably, the brake pad is rotationally coupled with the outer ring of the freewheel around the main axis, regardless of the position of the coupling member.

[0030] According to a first non-limiting alternative, the brake pad can cooperate directly with the outer ring of the freewheel. According to another non-limiting alternative, the brake pad can cooperate with a cap integral with the outer ring of the freewheel.

[0031] Preferably, the circular actuating portion of the handrail extends radially with respect to the tubular element and the main shaft. Advantageously, the user rotates the handrail by rotating said circular actuating portion. The circular actuating portion of the handrail is advantageously equipped with handles.

[0032] Preferably, the circular actuating portion is integral with the extension portion of the handrail. Preferably, the circular actuating portion and the extension portion of the handrail are two separate parts joined together, for example by means of screws. Without departing from the scope of the invention, the circular actuating portion and the extension portion of the handrail may be a single part.

[0033] The coupling member is advantageously helically connected to the extension portion of the handrail. The threaded portion of the coupling member is advantageously a tapped portion whose tapping is configured to cooperate with the thread of the threaded portion of the extension portion. The coupling surface of the coupling member is advantageously a conical surface. It is advantageously inclined with respect to the principal axis, considered in a longitudinal section plane.

[0034] Preferably, the brake pad has the shape of a portion of a cylinder. The brake pad is advantageously arranged between the hub, the coupling member, and a cap. Advantageously, the wheel system comprises two pads arranged on either side of the tubular element and diametrically opposed.

[0035] Preferably, the locking piece is fixed to one end of the tubular element. The locking piece and the circular actuation portion of the handrail preferably extend on either side of the hub.

[0036] Without departing from the scope of the invention, the locking piece and the tubular element may form only one and the same piece.

[0037] The pivoting of the handrail in a first direction of rotation, corresponding to a direction of rotation of the wheel for the forward movement of the wheelchair, causes the axial translation of the coupling member in a first direction of movement, towards the conical surface of the inner face of the hub, until said coupling member is brought into the first position.

[0038] In this first position, the coupling surface of the coupling member abuts against the conical surface of the inner face of the hub, thus halting the axial movement of the coupling member. Consequently, the handrim and the hub are rotationally coupled around the main axis in the first direction of rotation. In this first position, the handrim drives the hub in the first direction of rotation. Pivoting the handrim in the first direction of rotation causes the wheel to move in the same first direction of rotation, corresponding to a forward movement of the wheelchair. In this first direction of rotation of the hub, the outer ring of the freewheel is prevented from rotating relative to the inner ring. Since the hub is mounted to pivot relative to the outer ring of the freewheel, the wheel can nevertheless pivot relative to the freewheel and therefore to the tubular element around the main axis.

[0039] From this initial position, when the user stops rotating the handrail, the coupling element moves slightly axially in a second direction of movement, opposite to the first direction of movement. This second direction of movement corresponds to a displacement opposite to the conical surface of the inner face of the hub, directed towards the brake pad. Given this slight axial displacement, The coupling surface of the coupling element is no longer in contact with the conical surface of the inner face of the hub, and the coupling between the handrail and the wheel is interrupted. However, the wheel continues to pivot in the first direction of rotation, allowing the wheelchair to move forward.

[0040] Preferably, when the coupling member is in the first position, the distance between the ramp of the coupling member and the first conical surface of the brake pad is less than 2 millimeters, preferably less than one millimeter.

[0041] To brake the wheel, the user rotates the handrail in a second direction of rotation opposite to the first direction of rotation. This second direction of rotation corresponds to a braking direction or a direction of backward movement for the wheelchair.

[0042] The coupling member is driven in axial translation by the extension portion of the handrail and moves axially in the second direction of travel, towards the brake pad. Preferably, in the second direction of travel, the coupling member is moved towards the freewheel.

[0043] The coupling member is moved until it reaches the second position, in which its ramp presses against the first conical surface of the brake pad. The coupling member then pushes the brake pad, which is moved radially towards the inner surface of the hub. The braking surface of the brake pad then comes into contact with the inner surface of the hub, thus braking the wheel.

[0044] In other words, pivoting the handrail in the second direction of rotation causes the wheel to brake, slowing its pivoting relative to the wheelchair frame.

[0045] During braking, during the deceleration phase and until it comes to a complete stop, the wheel continues to rotate in the first direction of rotation corresponding to a forward movement of the chair. In this first direction of rotation, and therefore during braking, the outer ring of the freewheel is prevented from rotating relative to the inner ring of the freewheel. The wheel can, however, pivot due to the pivot joint between the hub and the outer ring of the freewheel.

[0046] Preferably, the wheel system comprises a cap integral with the outer ring of the freewheel, the brake pad being free to move in translation relative to said cap. The brake pad is advantageously prevented from rotating relative to the cap. Preferably, the cap comprises a housing in which the freewheel is disposed. It is understood that the cap allows the brake pad to be coupled in rotation relative to the outer ring of the freewheel.

[0047] Preferably, the brake pad further comprises a second conical surface, inclined with respect to the first conical surface. The cap advantageously has a conical cap surface, the second conical surface of the pad The braking system is configured to bear against the conical plug surface when the coupling member is in the second position. It is understood that when the coupling member is in the second position, the brake pad is sandwiched between the plug and the locking element.

[0048] When the wheel pivots in the first direction of rotation and therefore in particular during braking, the cap and the brake pad are blocked in rotation relative to the tubular element, taking into account the blocking in rotation of the outer ring of the free wheel.

[0049] To rotate the wheel in the second direction of rotation, corresponding to a backward movement of the wheelchair, the user also rotates the handrim in this second direction. Consequently, the coupling member is brought into the second position, which is pushed by the brake pad, thus moving it radially. The braking surface of the brake pad is pressed against the inner face of the hub, thereby generating a coupling between the handrim and the hub in this second direction of rotation, via the brake pad and the coupling member. In this second direction of hub rotation, the outer ring of the freewheel is free to rotate relative to the inner ring.The pivoting of the hub in the second direction of rotation is permitted by the rotational coupling of the brake pad with the outer ring of the freewheel, which is itself free to rotate relative to the inner ring of the freewheel in this second direction of rotation.

[0050] In this second position of the coupling member, the cap is also coupled to the brake pad and the hub. The cap and the brake pad also pivot in this second direction of rotation.

[0051] A movement of the handrail in a second direction of rotation causes the wheel to move in rotation in this second direction of rotation, corresponding to a backward movement of the chair.

[0052] Preferably, between the first position and the second position, the coupling member moves axially by a distance of less than 2 millimeters, even more preferably less than one millimeter.

[0053] Preferably, when the coupling member is in the second position, the distance between the coupling surface of the coupling member and the internal conical surface of the inner face of the hub is less than 2 millimeters, preferably less than 1 millimeter. Preferably, the wheel system is configured so that the distance between the coupling surface of the coupling member and the internal conical surface of the inner face of the hub, when the coupling member is in the second position, is as short as possible without generating contact between these two surfaces.

[0054] Preferably, the main shaft is provided with an adjusting nut configured to come resting on one end of the tubular element, this adjusting nut allows for adjusting the axial position of the cap and therefore the distance between the cap and the coupling member. This allows for adjusting the distance between the ramp of the coupling member and the first conical surface of the brake pad, as well as the distance between the coupling surface of the coupling member and the internal conical surface of the inner face of the hub.

[0055] Preferably, the wheel system includes at least one first bearing located inside the hub and disposed between the threaded portion of the handrail extension and the tubular element. It is understood that the first bearing is located within an internal volume defined by the hub. One advantage is to improve the radial and lateral support of the handrail extension, particularly at the threaded portion of the handrail extension, which is subjected to significant stresses due to the interaction between the extension and the coupling member, and especially the lever arm formed by the handrail extension, which is subjected to significant stresses in all directions. The first bearing prevents the handrail and the wheel from pivoting. The first bearing preferably comprises a ball bearing.The first step allows for the centering of the extended portion of the handrail.

[0056] Advantageously, the handrail extension portion comprises a cylindrical part situated between the threaded portion and the circular actuating portion, the wheel system further comprising a second bearing disposed between said cylindrical part of the extension portion and said tubular element. One advantage is to further improve the radial and lateral support of the extension portion and to limit the articulation between the handrail and the wheel even more effectively. Another advantage is to ensure coaxiality between the extension portion and the tubular element, in addition to ensuring the rotational guidance of said extension portion.

[0057] The second bearing advantageously comprises a ball bearing.

[0058] Preferably, the wheel system further comprises an external bearing disposed between the outer ring of the freewheel and the hub. One advantage is to guide the pivoting of the hub relative to the tubular element and to improve the radial and axial support of the hub in order to maintain a constant wheel inclination and to prevent the wheel from pivoting between the handrail and the wheel.

[0059] Alternatively, and without departing from the scope of the invention, the wheel system may include an external bearing disposed between a plug integral with the outer ring of the free wheel and the hub.

[0060] The outer bearing preferably comprises a ball bearing.

[0061] Preferably, the wheel system further includes an external bearing disposed between the extension portion of the handrail and the hub.

[0062] Advantageously, the locking piece has the general shape of a disc, with a plurality of holes formed in the disc and arranged around the circumference of a circle centered on the center of the disc. One advantage is that this facilitates cooperation between the locking element and the locking piece, while reducing the weight of said locking piece.

[0063] The locking element preferably includes a locking pin configured to cooperate with any one of the holes in the locking piece.

[0064] The openings in the locking piece are preferably oblong in shape, in order to further facilitate the interaction between the locking element and the locking piece. In particular, during interaction, this oblong shape allows for a significant tolerance margin regarding the radial position of the locking element relative to the main axis, without significantly increasing the clearance between the locking element and the locking piece once assembled.

[0065] Preferably, said locking piece has a lateral face configured to abut against a portion of the frame when the main shaft is mounted on said frame. One advantage is to block the axial translation of the wheel system relative to the bicycle frame, directed towards the frame. In other words, the lateral face of the locking piece limits the movement of the wheel system when the main shaft is mounted on the frame.

[0066] The locking piece preferably comes to rest against an axle barrel of the wheelchair frame.

[0067] Preferably, the main shaft further comprises at least one stop element configured to abut against a portion of the wheelchair frame. The stop element prevents axial movement of the main shaft in a direction opposite to said frame. The stop element preferably comprises at least one ball. The stop element preferably prevents axial movement of the wheel system in a first mounting direction, while the lateral face of the stop element preferably prevents axial movement of the wheel system in a second mounting direction, opposite to the first mounting direction.

[0068] Advantageously, the distance between the side face of the locking piece and the thrust element is substantially equal to the width of the mounting portion of the frame, for example, the shaft sleeve, within which the main shaft extends. Preferably, the mounting portion of the frame is sandwiched between the side face of the locking piece and the thrust element of the main shaft.

[0069] According to a particularly advantageous aspect, the wheel system further comprises a friction piece disposed between the handrail and the wheel and configured to generate a friction torque between said handrail and the wheel when said wheel pivots. One advantage is to drive the handrail in rotation around of the main axis during the pivoting of the wheel and hub around this same main axis. Therefore, the handrail follows the rotational movement of the wheel. This prevents the handrail from remaining stationary when the wheel is rotating.

[0070] Consequently, when the wheel pivots in the first direction of rotation, corresponding to forward movement of the wheelchair, the handrail is also driven to rotate in this first direction. The coupling surface of the coupling member tends to come into contact with the internal conical surface of the inner face of the hub. Therefore, the handrail does not remain stationary during the wheel's pivot. One advantage is to reduce the amplitude of the force that the user must exert on the handrail in order to bring the coupling member into the initial position for coupling the hub and the handrail.

[0071] Similarly, when the wheel pivots in the second direction of rotation, corresponding to the wheelchair moving backward, the handrail is also driven to rotate in this second direction. The ramp of the coupling element tends to come to rest against the first conical surface of the brake pad. One advantage is to reduce the amplitude of the push that the user must exert on the handrail in order to bring the coupling element into the second position for coupling the hub and the handrail via the brake pad.

[0072] In other words, the friction element reduces the force required on the handrail, leading to coupling between the handrail and the hub and thus to the rotation of the wheel. A push on the handrail results in an almost immediate rotation of the wheel. The maneuverability of the wheelchair and the user's safety are improved.

[0073] Advantageously, the friction piece is disposed between the extension portion of the handrail and the hub. The friction piece is preferably disposed inside the hub. The friction piece can be fixed to the hub or to the handrail.

[0074] Preferably, said friction part comprises a seal, for example a lip seal, also called an oil seal. Said seal advantageously comprises a flexible lip configured to generate a frictional torque between the handrail and the hub.

[0075] Preferably, the wheel system further comprises an axial guide element pivotally mounted about the tubular element, the coupling member being translationally movable about the main axis relative to said axial guide element while being rotationally fixed about the main axis relative to said axial guide element, the axial guide element comprising a friction portion cooperating with the tubular element and configured to exert a friction torque on said tubular element.

[0076] The frictional torque exerted by the axial guide element tends to oppose the pivoting of said axial guide element, and therefore of the coupling member, about the main axis. The axial guide element is advantageously configured to prevent the pivoting of the coupling member when the latter is moved from the first position to the second position and vice versa. The axial guide element is advantageously configured to allow the pivoting of the coupling member about the main axis when the latter is in the first or second position.

[0077] One advantage is to reduce the play that can occur when the coupling member moves from the first to the second position and vice versa, by eliminating one degree of freedom, namely the degree of rotation of the coupling member around the main axis. In other words, one advantage is to prevent the coupling member from rotating when it moves axially between the first and second positions, thus limiting the unloaded angular deflection of the handrail.

[0078] Preferably, said friction portion is deformable and is configured to prevent the coupling member from pivoting relative to the tubular element when said coupling member is subjected to a torque below a predetermined threshold. The friction portion is advantageously configured to allow the coupling member to pivot relative to the tubular element when said coupling member is subjected to a torque above this predetermined threshold. The value of this predetermined threshold is preferably less than 1 Newton meter (Nm), preferably approximately equal to 0.2 Nm. In other words, when the torque exerted on the coupling member is less than the value of this predetermined threshold, the coupling member is in a sliding connection relative to the tubular element. When the torque exerted on the coupling member is greater than the value of this threshold, the coupling member is in a sliding pivot connection relative to the tubular element.The value of this predetermined threshold is advantageously chosen to be as low as possible, so that the friction torque is practically imperceptible during the pivoting of the coupling member, but high enough to prevent the pivoting of the coupling member relative to the tubular element during the axial displacement of the coupling member.

[0079] Preferably, said friction portion comprises a seal, for example a lip seal, fitted onto the tubular element. Said friction portion advantageously comprises a flexible inner lip fitted onto the tubular element.

[0080] Advantageously, said coupling member comprises at least one engagement portion and said axial guide element comprises at least one groove configured to receive said engagement portion, said engagement portion being configured to slide axially inside said groove.

[0081] Alternatively, and still advantageously, said coupling member includes at least one groove and said axial guide element includes at least one engagement portion configured to engage with said groove, said engagement portion being configured to slide axially inside said groove.

[0082] Said at least one engagement portion preferably includes a spline.

[0083] Preferably, the main shaft includes a quick-mounting device for removably mounting the wheel system to the wheelchair frame. The mounting device allows for quick mounting and dismounting of the wheel system from the frame.

[0084] The quick-mounting device advantageously comprises at least one ball disposed in a cavity formed in the main shaft and a rod configured to extend axially inside the main shaft. The rod advantageously comprises a thrust portion configured to push on the ball to move it radially when the rod is inserted into the main shaft. The ball is then brought into an extended position in which it protrudes radially from the outer surface of the main shaft. The ball then forms a stop blocking axial movement of the main shaft relative to the wheelchair frame.

[0085] The quick-mounting device advantageously allows the wheel system to be mounted to the wheelchair frame without tools.

[0086] The invention also relates to a wheelchair having a frame and comprising at least one wheel system as described above, said main shaft being mounted to the wheelchair frame for mounting the wheel system to said frame, the frame comprising at least one locking element and the locking piece cooperating with said locking element of the frame for locking the tubular element of the wheel system against rotation relative to the frame. Said wheel system is preferably removably mounted to the wheelchair frame.

[0087] Preferably, the wheelchair frame includes a connector fixed to said frame and to which the locking element is attached. The connector is chosen to be suitable for the frame.

[0088] The connector is preferably an added part fixed to the frame, for example by means of a screw.

[0089] Advantageously, the locking piece includes at least one orifice, and the locking element includes a locking pin extending radially away from the main shaft and cooperating with said orifice of the locking piece for the rotational locking of the tubular element relative to the frame.

[0090] By way of non-limitation, the locking pin may be inclined with respect to the axis main when the wheel system is mounted to the frame, especially when the wheel is inclined from the vertical at a camber angle.

[0091] Alternatively, and without departing from the scope of the invention, the frame advantageously comprises at least one orifice, and the locking piece advantageously comprises a locking pin extending radially at a distance from the main shaft and cooperating with said orifice of the frame for locking the tubular element against rotation relative to the frame.

[0092] Preferably, the locking pin comprises a spherical portion engaging with said at least one orifice of the locking piece. In other words, the locking pin is in a ball-and-socket joint with the locking piece.

[0093] One advantage is to facilitate the cooperation of the locking element with the locking piece, even if the wheel is inclined relative to the vertical at a camber angle, and therefore even if the locking element is inclined relative to the main axis.

[0094] Another advantage is to allow play-free mounting of the wheel system on the frame, despite the possible camber angle through which the wheel extends. Brief description of the drawings

[0095] The invention will be better understood upon reading the following description of embodiments of the invention given by way of non-limiting examples, with reference to the accompanying drawings, in which:

[0096] [Fig.1] [Fig.1] shows a wheelchair according to the invention;

[0097] [Fig.2] [Fig.2] is a cross-sectional view of a first embodiment of a system of the wheelchair wheel of the [Fig.1];

[0098] [Fig.3] [Fig.3] illustrates a brake pad of the wheel system of [Fig.2];

[0099] [Fig.4] [Fig.4] illustrates the wheel system of [Fig.2], the hub having been removed;

[0100] [Fig.5] [Fig.5] shows the axial guide element of the wheel system of [Fig.2];

[0101] [Fig.6] [Fig.6] shows the cooperation between the axial guiding element and the organ coupling of the wheel system of the [Fig.2];

[0102] [Fig.7] [Fig.7] is a cross-sectional view of a second embodiment of a wheel system according to the invention;

[0103] [Fig.8] [Fig.8] shows the locking piece of the wheel system of [Fig.2];

[0104] [Fig.9] [Fig.9] is a cross-sectional view illustrating the assembly of the wheel system of the [Fig.7] to the wheelchair frame;

[0105] [Fig. 10] [Fig. 10] shows the quick-mounting device for the wheel system of [Fig. 7]; and

[0106] [Fig. 1 l] [Fig. 11] shows the cooperation between the locking element and the locking part of the wheel system of [Fig.7]. Description of the implementation methods

[0107] The invention relates to a wheelchair wheel system and to a wheelchair comprising such a wheel system.

[0108] Figure 1 is a perspective view of a wheelchair 10 according to the invention, comprising a frame 12 to which are mounted a first wheel system 14 according to the invention and a second wheel system 16 according to the invention. Since the first and second wheel systems 14, 16 are substantially symmetrical, only the first wheel system 14 will be described in detail hereafter. The first wheel system 14 comprises a wheel 34, visible in Figure 1, comprising a hub 36 connected to a rim by means of spokes. A tire is mounted on the rim.

[0109] Figure 2 is a cross-sectional view of a first embodiment of the first wheel system 14 of Figure 1. As illustrated in Figure 2, the first wheel system 14 comprises a main shaft 20 extending along a main axis X. The first wheel system 14 further comprises a tubular element 22 receiving the main shaft 20 and extending along said main axis X. The tubular element 22 is sleeve-shaped. It is hollow and surrounds the main shaft 20. The main shaft 20 is engaged inside the tubular element 22 and is prevented from moving axially relative to said tubular element by means of a nut fixed to the end of the main shaft, in a direction of axial movement.

[0110] The wheel system further includes two rings 23 fitted onto the main shaft and bearing against shoulders formed inside the tubular element 22. The tubular element extends essentially inside the hub 36.

[0111] The first wheel system 14 further comprises a handrail 24 including a circular actuating portion 26 particularly visible in [Fig. 1], and an extension portion 28, visible in [Fig. 2]. The extension portion 28 is integral with the circular actuating portion 26, by means of a screw in this non-limiting example.

[0112] As can be seen in [Fig.1], the circular actuation portion 26 of the handrail 24 extends radially with respect to the main shaft 20 and the tubular element 22. The circular actuation portion 26 includes a toroidal-shaped handle 27 extending around the periphery of said circular actuation portion 26.

[0113] The extension portion 28 of the handrail 24 extends axially along the principal axis X. The extension portion 28 extends around the tubular element 22 and therefore around the main shaft 20. It is pivotally mounted about the principal axis X relative to the tubular element 22. The extension portion has a generally cylindrical shape. The extension portion 28 includes a threaded portion 30 formed at a distal end of the extension portion. The extension portion 28 includes in in addition to a cylindrical part 29 located between said threaded part 30 and the circular actuation portion 26.

[0114] The extension portion 28 of the handrail 24 is pivotally mounted relative to the tubular element 22 by means of a first bearing 31 and a second bearing 32 located inside the hub 36. In this non-limiting example, the first and second bearings 31, 32 are ball bearings. Without departing from the scope of the invention, these bearings could be needle bearings. The first bearing 31 is disposed between the tubular element 22 and the threaded portion 30 of the extension portion 28. The second bearing 32 is disposed between the tubular element 22 and the cylindrical portion 29 of the extension portion 28 of the handrail 24.

[0115] For clarity, only the hub 36 of the wheel 34 is shown in [Fig. 2]. The hub 36 has an inner face 37 having an internal conical surface 38. Viewed in the cutting plane, this internal conical surface 38 is inclined with respect to the principal axis X. The hub 36 is pivotally mounted with respect to the extension portion 28 of the handrail by means of a first external bearing 39 disposed between the hub 36 and said extension portion 28. This first external bearing 39 is here a ball bearing.

[0116] The first wheel system 14 further comprises a coupling member 40 located inside the hub 36. The coupling member is generally cylindrical in shape. The coupling member 40 has a threaded portion 43, more precisely a tapped portion, engaged with the threaded portion 30 of the extension portion 28 of the handrail 26. The coupling member 40 is helically connected to the extension portion 28 of the handrail. Thus, pivoting the handrail 24 in a first direction of rotation causes the coupling member 40 to move axially along the principal axis X in a first direction of movement, while pivoting the handrail 24 in a second direction of rotation, opposite to the first direction of rotation, causes the coupling member 40 to move axially in a second direction of movement, opposite to the first direction of movement.

[0117] The coupling member 40 further comprises a conical coupling surface 41 inclined with respect to the principal axis X considered in the cutting plane. This coupling surface 41 is positioned opposite the internal conical surface 38 of the inner face 37 of the hub 36. The coupling member 40 further comprises a ramp 42 also inclined with respect to the principal axis. The coupling member 40 comprises a plurality of engagement portions 45, here four engagement portions 45, extending axially. These engagement portions 45 are illustrated in [Fig. 6]. These engagement portions have the form of splines extending along the principal axis X.

[0118] Hereafter, the first direction of rotation will be defined as a rotation of the wheel or of the handrail in a direction corresponding to a forward movement of the wheelchair 10. The second direction of rotation will be defined as a rotation of the wheel or of the handrail in a direction corresponding to braking or a backward movement of the wheelchair 10.

[0119] The first wheel system 14 further includes a freewheel 44 located inside the hub 36, that is, within the inner volume of the hub. The freewheel 44 is a cam-operated freewheel. The freewheel 44 comprises an inner ring 46 and an outer ring 48. The inner ring 46 is fixed to the tubular element 22. The outer ring 48 is locked against rotation relative to the inner ring 46 in the first direction of rotation and free to rotate relative to the inner ring 46 in the second direction of rotation.

[0120] The hub 36 is pivotally mounted relative to the outer ring 48 of the freewheel 44 by means of a second outer bearing 50. In this non-limiting example, the second outer bearing 50 is a ball bearing.

[0121] The first wheel system 14 further includes a cap 52 extending along the main axis X, around the tubular element 22 and fixed to the outer ring 48 of the free wheel 44. The cap 52 has a housing receiving the outer ring 48 of the free wheel 44. The cap 52 is located in the hub 36. The cap further has a conical cap surface 53 inclined with respect to the main axis X.

[0122] The wheel system 14 also includes a braking device 54 comprising two brake pads 56 located in the hub 36. One brake pad 56 is illustrated in [Fig. 3]. In this non-limiting example, the brake pads 56 have the shape of a portion of a cylinder describing an arc of a circle whose perimeter is less than a quarter of a circle. Each brake pad 56 comprises a first conical surface 57 and a second conical surface 58. Viewed in a longitudinal section plane, the first and second conical surfaces 57, 58 of the brake pads are inclined with respect to the principal axis X and inclined with respect to each other. The brake pads 56 further comprise a braking surface 59 forming an outer surface of the brake pads 56.

[0123] As illustrated in the perspective view of [Fig. 4], in which the wheel 34 and its hub 36 have been removed for clarity, the brake pads 56 are arranged between the hub 36, the end cap 52, and the coupling member 40. The two brake pads 56 are arranged on either side of the tubular element 22 and diametrically opposed. The first conical surfaces 57 of the brake pads 56 are arranged opposite the ramp 42 of the coupling member 40. The second conical surfaces 58 of the brake pads 56 are arranged opposite the conical end cap surface 53 of the end cap 52.

[0124] Furthermore, the brake pads 56 are locked in rotation relative to the cap 52 and therefore with respect to the outer ring 48 of the free wheel, here regardless of the position of the locking member 40. The brake pads 56 and the outer ring of the free wheel are therefore coupled in rotation, via the cap 52. The brake pads 56 are therefore locked in rotation with respect to the inner ring 46, and therefore with respect to the tubular element 22, in the first direction of rotation and free in rotation with respect to the inner ring 46, and therefore with respect to the tubular element 22, in the second direction of rotation.

[0125] Referring again to [Fig. 2], it can be seen that the first wheel system 14 also includes an axial guide element 60. The axial guide element 60 is located in the hub 36. It has a substantially cylindrical shape and is pivotally mounted around the tubular element 22. In this non-limiting example, the axial guide element 60 is located between the extension portion 28 of the handrail 24 and the freewheel 44. The axial guide element 60 further extends inside the end cap 52.

[0126] As illustrated in the perspective view of [Fig. 5], the axial guide element 60 comprises a circular axial guide portion 62 and a friction portion 64 disposed inside the axial guide portion 62. The friction portion 64 is deformable. It includes a lip seal, also called an oil seal, comprising a flexible inner lip 65 connected to a rigid peripheral ring 66. The flexible inner lip 65 of the friction portion 64 is fitted onto the tubular element 22. The axial guide element 60, via the friction portion 64, is configured to exert a slight friction torque on said tubular element 22. This torque tends to oppose the pivoting of said axial guide element 60 relative to the tubular element 22.

[0127] The coupling member 40 is movable in translation relative to the axial guide element 60 while being blocked in rotation relative to this axial guide element. To achieve this, as illustrated in [Fig. 6], the axial guide portion 62 of the axial guide element 60 comprises a plurality of grooves 63, here four grooves 63, configured to receive engagement portions 45 of the coupling member 40.

[0128] The axial guide element 60 is configured to prevent the coupling member 40 from pivoting relative to the tubular element 22 when said coupling member 40 is subjected to a torque below a predetermined threshold. The axial guide element 60 is configured to allow the coupling member 40 to pivot relative to the tubular element 22 when said coupling member 40 is subjected to a torque above said predetermined threshold. The value of this predetermined threshold is approximately 0.2 newton meters (N·m).

[0129] The engagement of the engagement portions 45 of the coupling member 40 in the grooves 63 of the axial guide element 60 is illustrated in [Fig.6].

[0130] The first wheel system 14 also includes a friction piece 70 disposed between the extension portion 28 of the handrail 24 and the hub 36. In the non-limiting example of [Fig. 2], the friction piece 70 comprises a lip seal having a flexible lip 71 in contact with the hub 36 and a rigid ring 72 fixed to said extension portion 28 of the handrail. In this non-limiting example, the friction piece 70 is positioned between an axial end of the hub 36 and the main portion 26 of the handrail 24.

[0131] The friction piece is configured to generate a frictional torque between the hub and the extension portion 28 of the handrail, and therefore between the handrail 24 and the wheel 34. The friction piece 70 causes the handrail 24 to rotate when the hub, and thus the wheel 34, pivots, so that the handrail follows the rotational movement of the wheel. This prevents the handrail from remaining stationary when the wheel is rotated, particularly in the first direction of rotation, reducing the force required on the handrail to rotate the wheel 34.

[0132] Figure 7 illustrates a variant of the wheel system 14 according to the invention, in which the friction piece 70 is located between the first outer bearing 39 and the coupling member 40. The flexible lip 71 of the friction piece 70 is here in contact with the extension portion 28 while the rigid ring 72 is fixed to the inner face 37 of the hub 36.

[0133] Referring again to the embodiment of [Fig. 2], it can be seen that the first wheel system 14 further comprises a locking piece 74 integral with the tubular element 22. In this non-limiting example, the locking piece 74 and the tubular element 22 are two separate parts fixed together. The locking piece 74 is fixed to one end 22a of the tubular element 22, opposite the handrail 24. The locking piece is therefore located opposite the handrail. The locking piece 74 is configured to cooperate with a locking element of the frame for the rotational locking of the tubular element 22 relative to the frame. This locking piece 74 is illustrated in the perspective view of [Fig. 8].

[0134] This locking piece 74 is substantially disc-shaped, or daisy-shaped. The locking piece 74 extends radially with respect to the tubular element 22 and the main axis X. It is also traversed by the main shaft 20. The locking piece 74 and the circular actuating portion 26 of the handrail 24 are arranged on either side of the hub 36, viewed axially. Several orifices 76 are provided in the rotating locking piece 74 and arranged around the circumference of a circle centered on the main axis X, or on the center of the disc. These orifices 76 are oblong in shape.

[0135] The locking piece 74 further comprises a lateral face 74a opposite the hand current.

[0136] To mount the first wheel system 14 to the frame 12 of the wheelchair 10, the main shaft 20 is inserted into a sleeve 80 attached to the frame 12 and shaped like a sleeve, as illustrated in [Fig. 9]. In this non-limiting example, the sleeve 80 has a through hole 81 extending along a shaft axis inclined relative to the horizontal. Therefore, when the main shaft 20 is inserted into the sleeve 80, the main axis X of the main shaft coincides with the shaft axis and is also inclined relative to the horizontal. Consequently, the wheel 34 is inclined relative to the vertical at a camber angle, facilitating passage through doorways. The diameter of the through hole 81 is very slightly larger than the diameter of the main shaft 20.

[0137] In this non-limiting example, the main shaft 20 includes a quick-mounting device 82 for removably mounting the first wheel system 14 relative to the wheelchair frame 12. This quick-mounting device 82 includes an axial rod 84 mounted to slide within the main shaft 20. The axial rod extends along the main axis X.

[0138] As illustrated in [Fig. 10], the axial rod 84 has a first end provided with a thrust portion 86 whose diameter is greater than the diameter of the axial rod. The quick-mounting device 82 further comprises two balls 88 housed in cavities 87 formed at the end of the main shaft 20 and free to move radially within these cavities. The axial rod 84 also has a second end, opposite the first end, and provided with a gripping portion 89 for manipulating the axial rod.

[0139] To mount the wheel system to the frame, the main shaft 20 is inserted into the through hole 81 of the axle tube 80 until the lateral face 74a of the locking piece 74 comes to rest against the axle tube 80. The tubular element 22 is thus locked in axial translation relative to the main shaft 20, in the direction of the frame 12.

[0140] The cavities 87 are then positioned outside the axis barrel 80, as illustrated in [Fig. 10]. The gripping portion 89 and the cavities 87 then extend on either side of the axis barrel. The balls 88 then extend into the cavities inside the main shaft, without protruding radially from the outer surface of the main shaft.

[0141] In order to prevent the main shaft 20 from translating relative to the axis barrel 80, the rod 84 is inserted into the main shaft until the thrust portion 86 pushes on the balls 88, so as to move them radially within the cavities. The balls 88 then protrude radially from the outer surface of the main shaft 20 and abut against the axis barrel, preventing the main shaft from being withdrawn from the axis barrel 80. Consequently, the tubular element 22, and therefore the main shaft 20, are blocked in translation relative to the 80 axis cannon and therefore to frame 12.

[0142] In order to lock the tubular element 22 from rotation relative to the frame 12 of the wheelchair 10, the frame is provided with a locking element 90 consisting, in this non-limiting example, of a locking pin 90 illustrated in Figures 9 and 11. This locking element 90 comprises a spherical portion 92. In this non-limiting example, as illustrated in [Fig. 11], the locking element 90 is fixed to a connector 94 attached to it, itself fixed to the frame 12. The locking element 90 is radially distant from the main shaft 20 and the tubular element 22. The locking element 90 extends substantially horizontally.

[0143] The locking element cooperates with one of the oblong orifices 76 of the locking piece 74, thus blocking the rotation of the locking piece and therefore of the tubular element 22 around the main axis X. Given the oblong shape of the orifices 76 of the locking piece 74 and the spherical portion 92 of the locking element 90, the locking element can easily be brought into cooperation with one of the orifices, while limiting the play between the locking element and the locking piece and therefore between the tubular element and the frame.

[0144] We will now detail the forward drive, braking and reverse drive of a wheel 34 of the wheel system 14 of the wheelchair 10 according to the invention, with reference to [Fig.2].

[0145] To move the wheel 34 in the first direction of rotation, corresponding to the direction of rotation for the forward movement of the wheelchair 10, the user rotates the handrim 24 in this same first direction of rotation around the main axis X. The extension portion 28 of the handrim 24 pivots in this first direction of rotation around the main axis X. The coupling member 40, whose threaded portion 43 is engaged with the threaded portion 30 of the extension portion 28, is moved axially along the main axis in a first direction of movement. The coupling member 40 is moved towards the internal conical surface 38 of the inner face 37 of the hub 36, until the coupling member is brought into a first position.

[0146] In this first position, the coupling surface 41 of the coupling member 40 bears against the internal conical surface 38 of the inner face 37 of the hub 36, so that the axial movement of the coupling member is stopped. Consequently, the hub 36 and the handrail 24 are rotationally linked by means of the coupling member 40. Pivoting the handrail in the first direction of rotation then causes the wheel to move in the same first direction of rotation. In this first direction of rotation of the wheel, the outer ring 48 of the freewheel 44 is prevented from rotating relative to the inner ring 46. Since the hub 36 is pivotally mounted relative to the outer ring 48 of the freewheel, it can nevertheless pivot in this first direction of rotation, so that the wheel can pivot around the main axis X relative to the tubular element 22.

[0147] In other words, pivoting the handrail 24 in the first direction of rotation causes the wheel 34 to move in the same first direction of rotation, corresponding to a forward movement of the chair 10.

[0148] The axial guide element 60 prevents the coupling member 40 from rotating during its axial movement, for example towards the first position or towards the second position, without preventing the coupling member from pivoting when coupled to the hub 36 or the brake pad 56.

[0149] From this initial position, when the user no longer rotates the handrim 24, the coupling member 40 moves slightly axially in a second direction of movement, opposite to the first direction of movement. The coupling member 40 moves away from the internal conical surface 38 of the hub and towards the brake pad 56. Due to this slight displacement, the coupling surface 41 of the coupling member 40 no longer comes into contact with the internal conical surface 38 of the inner face 37 of the hub, and the coupling between the handrim 24 and the wheel 34 is broken. The wheel 34, however, continues to pivot freely in the first direction of rotation, and the wheelchair continues to move forward.

[0150] To brake the wheel 34, the user rotates the handrail 24 in the second direction of rotation, opposite to the first direction of rotation. This second direction of rotation corresponds to a braking direction or a direction of backward movement for the wheelchair.

[0151] The coupling member 40, whose threaded portion 43 is engaged with the threaded portion 30 of the extension portion 28 of the handrail, is driven in translation by the extension portion of the handrail 24. It moves axially in the second direction of movement, towards the brake pads 56. In this second direction of movement, the coupling member 40 is moved towards the plug 52 and the freewheel 44.

[0152] The coupling member 40 is moved until it reaches the second position, in which its ramp 42 comes into contact with the first conical surface 57 of the brake pads 56. The second conical surface 58 of the brake pads is pressed against the conical end cap surface 53 of the end cap 52. The brake pads 56 are then sandwiched between the coupling member and the end cap. The coupling member 40 then exerts a force on the brake pads 56, which spread apart and are moved radially towards the hub 36. The braking surface 59 of the brake pads then comes into contact with the hub, thus braking the wheel 34.

[0153] In other words, pivoting the handrail 24 in the second direction of rotation causes the wheel to brake.

[0154] During braking, and until it comes to a complete stop, the wheel 34 continues to rotate in the In the first direction of rotation, the outer ring 48 of the freewheel is blocked from rotating relative to the inner ring 46 of the freewheel. However, the wheel can pivot due to the pivot joint between the hub and the outer ring of the freewheel.

[0155] When the wheel pivots 34 in the first direction of rotation and therefore during braking, the cap 52 and the brake pads 56 are blocked in rotation relative to the tubular element 22, taking into account the blocking in rotation of the outer ring of the free wheel.

[0156] To rotate the wheel in the second direction of rotation, corresponding to a backward movement of the wheelchair, the user rotates the handrim 24 in this second direction. As a result, the coupling element pushes the brake pads 56 against the hub, again generating a coupling between the handrim and the hub 36. The hub 36, and therefore the wheel 34, are driven to rotate in the second direction. In this second direction of rotation, the outer ring 48 of the freewheel 44 is free to rotate relative to the inner ring 46. The pivoting of the hub in the second direction of rotation is enabled by the rotational coupling of the brake pads 56 with the outer ring of the freewheel, which is itself free to rotate relative to the inner ring of the freewheel in this second direction of rotation.

[0157] In this second position of the coupling member 40, the plug 52 is also coupled to the brake pads 56 and the hub 36. The plug and the brake pads also pivot in this second direction of rotation.

[0158] In other words, a movement of the handrail 24 in this second direction of rotation causes the wheel 34 to rotate in this second direction of rotation, corresponding to a backward movement of the wheelchair 10.

Claims

Demands

1. Wheel system (14, 16) for a wheelchair (10) having a frame (12), the wheel system comprising: - a wheel (34) having a hub (36) having a main axis (X), the hub comprising an internal face (37) provided with an internal conical surface (38); - a main shaft (20) configured to be mounted to the wheelchair frame; - a tubular element (22) extending along the main axis, the main shaft being engaged in said tubular element; - a handrail (24) mounted pivotally around the main axis relative to the tubular element and coupled to the wheel for the rotational drive and braking of the wheel, the handrail comprising a circular actuation portion (26) and an extension portion (28) extending into the hub, said extension portion surrounding the tubular element and having a threaded part (30); - at least one brake pad (56) located in the hub and comprising a braking surface (59) and at least one first conical surface (57); - a coupling member (40) comprising a coupling surface (41), a ramp (42) and a threaded portion (43) engaged with the threaded part of the extension portion of the handrail to axially move the coupling member relative to the hub, the coupling member being movable in axial translation between at least a first position in which its coupling surface is in contact with the internal conical surface of the hub, so as to link the handrail and the hub in rotation, and a second position in which the ramp of the coupling member presses against the first conical surface of the brake pad to radially push the brake pad against the internal face of the hub; - a freewheel (44) comprising an inner ring (46) fixed relative to the tubular element and an outer ring (48) blocked against rotation relative to the inner ring in a first direction of rotation and free to rotate relative to the inner ring in a second direction of rotation opposite to the first direction of rotation, the wheel hub being pivotally mounted relative to the outer ring of the freewheel, the brake pad being rotationally linked to the outer ring of the free wheel when the coupling member is in the second position; and - a locking piece (74) integral with the tubular element and located opposite the handrail, the locking piece being configured to cooperate with a locking element (90) of the frame for locking the tubular element against rotation relative to the frame.

2. Wheel system according to claim 1, comprising at least one first bearing (31) located inside the hub (36) and disposed between said threaded part (30) of the extension portion (28) of the handrail (24) and said tubular element (22).

3. Wheel system according to claim 2, wherein the extension portion (28) of the handrail (24) comprises a cylindrical part (29) situated between the threaded part (30) and the circular actuation portion (26), the wheel system (14,16) further comprising a second bearing (32) disposed between said cylindrical part of the extension portion and said tubular element (22).

4. Wheel system according to any one of claims 1 to 3, further comprising an outer bearing (50) disposed between the outer ring (48) of the free wheel (44) and the hub (36).

5. Wheel system according to any one of claims 1 to 4, wherein the locking piece (74) has the general shape of a disc, a plurality of orifices (76) being provided in the disc and arranged around the periphery of a circle centered on the center of the disc.

6. Wheel system according to any one of claims 1 to 5, wherein said locking piece (74) has a side face (74a) configured to abut against a portion (80) of the frame (12) when the main shaft (20) is mounted to said frame.

7. Wheel system according to any one of claims 1 to 6, further comprising a friction piece (70) disposed between the handrail (24) and the wheel (34) and configured to generate a friction torque between said handrail and the wheel when pivoting said wheel (34).

8. Wheel system according to claim 7, wherein the friction piece (70) is disposed between the extension portion (28) of the handrail (24) and the hub (36).

9. A wheel system according to any one of claims 1 to 8, further comprising an axial guide element (60) pivotally mounted about the tubular element (22), the coupling member (40) being mobile in translation about the main axis (X) relative to said axial guide element while being blocked in rotation about the main axis relative to said axial guide element, the axial guide element comprising a friction portion (64) cooperating with the tubular element and configured to exert a friction torque on said tubular element.

10. Wheel system according to claim 9, wherein said friction portion (64) is deformable and is configured to prevent the coupling member (40) from pivoting relative to the tubular element (22) when said coupling member is subjected to a torque below a predetermined threshold.

11. Wheel system according to claim 9 or 10, wherein said coupling member (40) comprises at least one engagement portion (45) and wherein said axial guide element (60) comprises at least one groove (63) configured to receive said engagement portion, said engagement portion being configured to slide axially inside said groove.

12. Wheel system according to any one of claims 1 to 11, wherein the main shaft (20) includes a quick-mounting device (82) for removably mounting the wheel system (14, 16) relative to said frame (12) of the wheelchair (10).

13. Wheelchair (10) having a frame (12) and comprising at least one wheel system (14,16) according to any one of claims 1 to 12, wherein said main shaft (20) is mounted to the frame of the wheelchair for mounting the wheel system to said frame, wherein the frame comprises at least one locking element (90) and wherein the locking piece (74) cooperates with said locking element of the frame for locking the tubular element (22) of the wheel system against rotation relative to the frame.

14. Wheelchair according to claim 13, wherein the locking piece (74) comprises at least one orifice (76), and wherein the locking element (90) comprises a locking pin extending radially away from the main shaft (20) and cooperating with said orifice of the locking piece for the rotational locking of the tubular element (22) relative to the frame (12).

15. Wheelchair according to claim 14, wherein the locking pin (90) comprises a spherical portion (92) engaging with said at least one orifice (76) of the locking piece (74).

Images