WO2014122404A1

WO2014122404A1 - System for mounting a wheel on a wheelchair

Info

Publication number: WO2014122404A1
Application number: PCT/FR2014/050230
Authority: WO
Inventors: Olivier Le Berre
Original assignee: Institution Nationale Des Invalides - Centre D' Etudes Et De Recherche Sur L'appareillage Des Handicapés
Priority date: 2013-02-08
Filing date: 2014-02-07
Publication date: 2014-08-14
Also published as: FR3001887A1; FR3001887B1

Abstract

The invention relates to a system for mounting a rear wheel on a wheelchair, comprising: a shaft (3, 103, 203) fixedly mounted on the frame (1) or arranged such as to be fixed on the frame by a first end, and acting as a shaft for the bearings (22, 23) of the wheel (2); a device (4, 104, 204) for manual tightening using a cam lever (5, 105, 205), arranged on the second end of the shaft; and a compressible spacer (6) mounted on the shaft and axially located between the bearings and the manual tightening device. The system is particularly for the wheelchairs of disabled athletes.

Description

Wheel mounting system on a wheelchair.

The present invention relates to wheelchairs particularly for the disabled sports. It relates more precisely the mounting system of the large wheels, that is to say the rear wheels, on the chassis of the chair.

In the context of sports performance, any improvement of the manual wheelchair, even a small one, is sought after by the athlete.

In sports such as tennis or wheelchair basketball, wheelchair maneuverability is a key determinant of performance. In fact, the wheelchair must ensure rapid and precise changes of direction from the efforts applied by the athlete on the handrails. Also, any play between the rear wheels and the chassis should be avoided to maximize the maneuverability of the chair.

Moreover, these chairs, whose rear wheels have a large camber angle, have a large size, requiring the disassembly of the rear wheels to be transported or even to pass the doors to access the sports field. Also, the ability to quickly disassemble the wheels is a practical aspect of these chairs.

It is therefore desired to have an optimal axial clamping mechanism, fast and controlled. In addition, this device should preferably be installed without modification of the frame on most existing wheelchairs.

Already known, to ensure easy handling of the chair, fastening devices of the large rear wheels called "quick disassembly". These devices are very common on the market and typically consist of a wheel shaft placed on the wheel by axial sliding in the rings. wheel bearing housings, mounted in the hub of the wheel, and engaged in a frame bore, this shaft having a ball lock system for axially holding the shaft on the frame. Typically, in these systems, the accessible end of the shaft is terminated by a push button and the other by several balls which retract into the shaft under the effect of a press on the push button. The mounting of a wheel is therefore as follows: push button; passage of the shaft through the wheel and into the frame, release of the push button. Once the button is released, the balls come out of the shaft and prevent the removal of the shaft from the bore of the frame. But these systems lead to too much axial play for athletes. Indeed, these devices, if they allow a quick assembly and disassembly of the wheels, impose a game of axial operation between the shaft and the frame, and therefore between the wheel and the frame, sufficient so that the balls of the lock to ball can, on the one hand, out properly and provide reliable locking and, on the other hand, retract as easily, to allow easy disassembly. This axial play is felt by the athletes as affecting the maneuverability of the chair.

Systems of this type are described in particular in EP1627619, WO200484787, US4351540, FR2563993.

In the system shown in EP1627619, in Figure 12, the shaft is bonded to the wheel and rotates in bearings housed in a frame bore. This system allows only rapid disassembly and assembly by means of a ball lock pin, without possibility of adjustment of axial play of the wheel and its shaft relative to the frame. Likewise, WO200484787 discloses a ball lock system without any possibility of adjusting or eliminating the clearance of the bearings. In the device described in US4351540, an adjustable nut seems to allow to adjust the axial clearance between the wheel and the frame, but this adjustment can be made only after assembly and locking of the shaft, except to pose the problems of lock systems to previously mentioned balls. Similarly, FR2563993 discloses a device with an adjusting nut which makes it possible to make up or eliminate excessive axial play, but which requires manual adjustment after the shaft has been locked. In other words, the latter two systems only allow to adjust the useful length of the ball lock so as to ensure an axial functional clearance sufficient to allow the correct operation of the ball lock, and then allow to remove the axial clearance, after that the lock is done. These systems do not solve the problem of axial clearances inherent in the ball lock systems to allow proper operation of these locks, without adjusting intervention after mounting the wheel on the chair. It remains of course possible then to remove these sets and adjust the tightening of the bearings after the wheel is mounted. But then it is a setting operation that must be done during each wheel winding, which can lead to inaccurate adjustments and either games or excessive tightening, and is incompatible with the desired quick assembly, for that the chair is immediately operational from the wheel in place.

FR2725128 also discloses a rapid disassembly hub system in which the wheel support shaft is held in a frame bore by means of a radially expandable sleeve located at the end of the shaft, and the radial expansion causes the end of the shaft to jam in said bore. The radial expansion of the bushing is obtained by axial traction exerted on a rod arranged for this purpose, axial traction being caused in known manner by a cam lever, pressing a non-deformable support washer in axial abutment on the shaft. In this system, the clamping force results solely from the traction exerted on the rod, and does not reliably ensure adjustment and automatic adjustment of the axial play of the bearings. In fact, at the limit, this clamping by radial expansion can be obtained even though the bearings would keep the possibility of moving axially on the shaft. This system therefore allows rapid assembly and disassembly of the wheel, but does not ensure a mounting without axial play of the bearings, with axial stress ensured.

The present invention aims to solve the problems mentioned above, and aims in particular to provide a wheel mounting device for quick assembly and disassembly and ensuring a mounting without axial play of the wheel, with a slight load of the set of bearings in the axial direction, without, however, requiring adjustment after each wheel assembly.

The objectives of the invention are, in general, to:

allow the axial clearance to be canceled in the pivot connection of the large rear wheels of a manual wheelchair,

- to allow an optimal, fast and controlled axial tightening,

allow manual assembly and disassembly, without tools and fast, typically less than 2 minutes, rear wheels

- Can adapt to any chair accepting a rapid disassembly device without particular modification of the chassis.

With these objectives in view, the invention relates to a rear wheel mounting system on a wheelchair. According to the invention, this system comprises:

a shaft fixedly mounted on the chassis or arranged to be fixed to the chassis by a first end, and serving as a shaft for the wheel bearings, the shaft being linked to the chassis in a fixed position axially determined positively,

a manual cam lever clamping device arranged on the second end of the shaft,

- A compressible spacer mounted on the shaft and located axially between the bearings and the manual clamping device.

The shaft has the function of supporting the connection in rotation between the frame and the wheel, provided by ball bearings typically two in number, mounted in a conventional manner in the hub of the wheel. When dismounting the wheel, the bearings remain attached to the wheel and slide axially on the shaft.

The compressible tubular spacer constitutes a compression spring, preferably made of a polymer material, making it possible to ensure a slight substantially constant axial clamping when the cam lever is brought into its clamping position. Preferably, the compressible spacer is made in the form of a tubular element a polymeric material, such as polyurethane of hardness 90 Shore A, intended for the construction of polymer springs, such as "elastomeric springs" Ref.391 - 394 - 395 - 396 -397 marketed by the company "Rabourdin industry". The elastomeric material of such springs being practically incompressible in itself, the deformation under load of these tubular-shaped springs actually results in an elastic deformation of bulging, barrel-shaped.

The compressible spacer will for example typically, off load, and depending on the different embodiments, a length of 15 to 25 mm, for an outer diameter of about 20 mm and an internal diameter of about 8 to 15 mm, a thickness of about 3 to 6 mm, these values being given only by way of non-limiting examples.

A complementary advantage of the use of this compressible spacer is that it also allows, by compressing itself further during side impacts on the wheelchair or on the wheels, to play the role of damper.

Manual tightening is ensured in all cases by the cam lever, mounted either on the shaft when the shaft itself is assembled on the frame by screwing or by ball lock, or on a screw screwed into the shaft when the shaft is secured to the frame. The cam lever allows the user to perform wheel mounting and axial backlash compensation manually, without tools, and with a force of less than 60 N (as stipulated in standard NF EN 12183). As will be understood, the manual tightening obtained by the cam lever will ensure consistency in the stressing of the bearings, from one wheel assembly to another, without the need for adjustment at each installation. It also avoids variations in clamping from one assembly to another, which could otherwise result from the simple personal appreciation of the effort exerted by the user, in the case of a manual adjustment to each assembly.

In the case of an assembly with screw screwed into a shaft fixed to the frame, a first screwing causes the screw to abut against the spacer, then the additional tightening performed by means of the cam lever compresses the spacer without greatly increasing the axial force. In the case of an assembly with a shaft screwed on the chassis or fixed with a ball lock, the travel of the lever must be longer, because a part of this race is used to make up the game which can remain after screwing or the operating clearance of the ball lock, about 1mm. In all cases, it is on the one hand to catch the game, so to come into contact with the bearing, then to perform a slight axial loading, low enough not to significantly increase the power loss in the bearings, but important enough to limit the axial separation of the bearings during efforts on the wheels, and thus get a good responsiveness of the chair.

Thus, thanks to the invention, the attachment of the wheel on the chair can be ensured easily and quickly either by screwing or by engagement of the ball lock. The elimination of the axial clearances is carried out immediately thereafter, by means of the cam lever which compresses the spacer, ensuring minimal stressing of the bearings, allowing the clearance to be eliminated, and this with a substantially constant axial force, since this effort depends only on compression of the compressible spacer, and this compression depends only on the effective stroke of the cam lever cam, which stroke is almost constant, directly related to the pivoting stroke of the cam lever which is substantially of the order of 90 °. There is therefore no adjustment to be made when mounting the wheel since, once the wheel shaft mounted and fixed, either by screwing or by the ball lock, the catching axial clearances and the stressing of the wheels. Bearings are provided directly by one actuation of the cam lever.

According to a first embodiment, the shaft is rigidly fixed to the frame by a first end, and the clamping device comprises a screw adapted to be screwed into a threaded hole made in the second end of the shaft. In this first embodiment, the cam lever is pivotally mounted on the head of the screw and acts on a pusher in direct or indirect support on the compressible spacer. In this case, all the parts are in contact after screwing. There is no play before stressing the compressible spacer by one actuation of the cam lever.

According to a second embodiment, the connection of the shaft to the frame is ensured by screwing. The shaft comprises a threaded first end adapted to be screwed into a sleeve secured to the frame, until it abuts in the sleeve by a shoulder provided for this purpose on the shaft. The clamping device is mounted on the second end of the shaft. At the end of screwing, axial play can remain. The effect of the cam has the effect of compensating for this play before the compressible spacer is put under stress as in the previous case.

According to a third embodiment, the connection of the shaft to the frame is provided by ball lock. The shaft comprises a ball lock system, of conventional type, comprising in particular an axially sliding pusher and movable balls radially held in positions protruding from the periphery of the shaft by a spring acting on said pusher. The first end of the shaft, comprising the balls, is engaged in a sleeve secured to the frame and is then held axially by said balls. At this stage, an axial functional game must exist. The clamping device is mounted on the second end of the shaft. As in the previous case, the action of the cam has the effect of compensating for this play before the stressing of the compressible spacer In the second and third embodiments, the cam lever is pivotally mounted on the second end of the shaft and acts on a pusher in direct or indirect support on the compressible spacer.

Preferably, a spacer is placed between the inner rings of the bearings, to avoid the risk of excessive stress on the bearings when tightened by the cam lever. One or more centering rings of light material, for example foam rubber with a density lower than the rubber, surrounding the spacer, make it possible to maintain the latter substantially centered in the bore of the wheel hub and thus axially aligned with the bearings when the wheel is disassembled, to allow easy reassembly of the wheel.

It will be noted that, in all the variants, the shaft is connected to the frame in a fixed position axially positively determined either by abutment, in the case of the ball lock, or by screwing, and the bearings are then put under stress , without the axial position of the shaft being influenced. The system according to the invention ensures complete independence between, on the one hand, maintaining the shaft on the chassis, and on the other hand maintaining the wheel on the shaft, by means of the bearings whose axial clearance can be adjusted by the manual cam clamp, and further compensated automatically, at least in part, by the compressibility of the compressible spacer.

Other features and advantages will appear in the description which will be made of three embodiments of a system according to the invention. Reference is made to the accompanying drawings in which: FIG. 1 is a perspective view of a wheelchair comprising a system according to a first embodiment, with a wheel removed,

FIG. 2 is a perspective view of the detail A of FIG. 1,

FIG. 3 is a partial perspective view of the mounted wheel,

FIG. 4 is a partial plan view of the mounted wheel,

FIG. 5 is a sectional view along the line

A-A of Figure 4,

FIG. 6 is a detailed view of the clamping device,

- Figures 7 to 12 are views corresponding to Figures 1 to 6 in the case of a second embodiment,

- Figures 13 to 17 are views corresponding to Figures 1 to 5 in the case of a third embodiment,

FIG. 18 is a sectional view along the line

B-B of Figure 16.

In the first embodiment shown in FIGS. 1 to 5, the wheel shaft 3 is rigidly and permanently mounted on the chassis 1. The wheel 2 of the wheelchair comprises a hub 21 in which two bearings 22, 23 whose diameter are mounted are mounted. The inside of the inner rings is fitted just sliding with that of the shaft 3.

When the wheel is mounted on the chair, the bearings are mounted on the shaft 3 with a spacer 24 between the inner rings of the bearings, and two centering rings 241 maintain the coaxiality of the spacer 24 when the wheel is disassembled. The manual clamping device 4 comprises a screw 41 adapted to be screwed into a threaded hole 31 of the free end of the shaft 3. A cam lever 5 is pivotally mounted between two lugs 43 integral with the head 42 of the screw . A pusher 51, placed between the lugs 43 and on which the cam 52 of the lever 5 acts, is also supported on an intermediate ring 53, itself bearing against the compressible spacer 6, which rests on the ring 22 of the bearing through a centering ring 54. A protective cover 55 protects the articulation of the lever and the pusher.

For mounting the wheel on the chair, it is placed on the shaft 3 by inserting the bearings 22 and 23 on said shaft, until the stop of the bearing 23 against a shoulder 32 of the shaft. The clamping device 4 is then put in place by screwing the screw 41 into the threaded hole 31 of the shaft, the lever 5 then being oriented substantially in the direction of the axis of the screw, as shown in FIG. The device is screwed up to apply the centering ring 54 against the bearing, eliminating any gaps between the cam 52, the pusher 51, the intermediate ring 53, the compressible spacer 6, the centering ring 54 and the bearing 22. The cam lever 5 is then folded down, as shown in FIGS. 3 and 5. In doing so, the cam 52 presses on the pusher 51, which has the effect of axially compressing the compressible spacer 6 and applying pressure to the bearings against the shoulder 32. Furthermore, the spacer 24, of predetermined length, prevents the axial stress exerted on the inner rings of the bearings by the clamping of the cam lever, creates an excessive stress in all of the two bearings , who could increase the internal friction of the ball bearings, and thus increase the effort required to rotate wheels, or be detrimental to the longevity of said bearings.

In the second embodiment shown in FIGS. 7 to 12, the wheel shaft 103 engages in a sheath 11 of the frame 1 and has at one end a thread 1031 designed to be screwed into a threaded hole made at the end. The shaft comprises, at the limit of the thread, a shoulder 1033 which abuts against a corresponding shoulder formed in the sleeve when the shaft is screwed, which determines the axial position of the shaft and therefore the cam lever, in relation to the bearings.

The wheel 2 of the chair comprises a hub 21 in which are mounted two bearings 22, 23 whose inner diameter of the inner rings is adjusted sliding just with that of the shaft 103.

When the wheel is mounted on the chair, the bearings are mounted on the shaft 103 with a spacer 24 between the inner rings of the bearings.

The manual clamping device 104 includes a cam lever 105 pivotally mounted between two lugs 1032 formed at the second end of the shaft. A pusher 1051, placed between the lugs 1032 and on which the cam 1052 of the lever 105 acts, is also supported on an intermediate ring 1053, itself bearing against the compressible spacer 6, which rests on the ring inside the bearing 22 via a support ring 1054.

For mounting the wheel on the chair, the shaft 103 is inserted into the bearings 22 and 23, then into the sheath 11. The shaft 103 is then aimed as far as the stop of the shoulder 1033 in the sheath. lever 105 then being oriented substantially in the direction of the axis of the screw, as shown in FIG. 8. At this stage, an axial clearance can remain between the cam 1052, the pusher 1051, the intermediate ring 1053, the compressible spacer 6, the bearing ring 1054 and the bearing 22. The cam lever 105 is then folded down, as shown in FIGS. 10. In doing so, the cam 1052 presses on the pusher 1051, which first has the effect of eliminating the axial clearances and then axially compressing the compressible spacer 6 and applying pressure to the bearings against the end of the sleeve 11. Furthermore, as in the previous example, the spacer 24 prevents the axial stress exerted on the inner rings of the bearings by the clamping of the cam lever, creates an excessive stress in all of the two bearings.

In the third embodiment shown in FIGS. 13 to 18, the wheel shaft 203 comprises a standard ball locking pin type ball locking system comprising, in a manner known per se, a push button 2031 acting on a 2033 actuating rod for maintaining radially outwardly pushed four balls 2032 placed in radial holes of the shaft, made near a first end of the shaft. Pressing the push button 2031 slides the rod 2033, allowing the balls 2032 to retract into a groove 2034 of the rod and thus allowing the introduction of the wheel shaft in the sleeve 12, or removal. The actuating rod 2033 is biased into position by a spring 2035, which has the effect of pushing the balls outwards and ensuring the locking of the wheel shaft as soon as the balls are found outside. of the sheath.

The wheel 2 of the wheelchair comprises a hub 21 in which two bearings 22, 23 are mounted, the inner diameter of the inner rings is adjusted just sliding with that of the shaft 203.

When the wheel is mounted on the chair, the bearings are mounted on the shaft 203 with a spacer 24 between the inner rings of the bearings. The shaft 203 engages in a sleeve 12 of the frame 1 and is locked there by the balls 2032, as explained above and as can be seen in FIGS. 17 and 18.

The manual clamping device 204 comprises a cam lever 205 pivotally mounted along an axis transverse to the axis of the shaft 203, on a bearing 2041 integral with the second end of the shaft. The cam lever 205 comprises two cams 2051 which press on a push washer 2052 placed on the shaft 203 resting on an intermediate ring 2053, itself bearing against the compressible spacer 6, which is supported on the inner ring of the bearing 22 by means of a bearing ring 2054.

For mounting the wheel, after pressing the push button 2031 to allow the balls 2032 to be withdrawn into the shaft 203 and the lever 205 then being oriented substantially in the direction of the axis of the screw, as shown in FIG. 14, the shaft 203 is inserted into the bearings 22 and 23, then into the sleeve 12. The pusher is then released, which causes the balls to emerge and the shaft to lock in the sleeve 12. The cam lever 205 is then folded down, as shown in FIGS. 15 to 17. In doing so, the cams 2051 press on the pusher washer 2052, which has the effect first of eliminating the axial clearances and then of axially compressing the compressible spacer 6 and to apply pressure against the bearings against the end of the sleeve 12. Furthermore, as in the previous examples, the spacer 24 prevents the axial stress exerted on the inner rings of the bearings by tightening the cam lever, creates an excessive stress in all of the two bearings.

Claims

1. Rear wheel mounting system on a wheelchair, comprising:

- a shaft (3, 103, 203) fixedly mounted on the frame (1) or arranged to be fixed to the frame by a first end, and serving as a shaft for the bearings (22, 23) of the wheel (2), the shaft being connected to the frame in a fixed position axially determined positively,

- a manual lever clamping device (4, 104, 204) with a cam lever (5, 105, 205), arranged on the second end of the shaft,

a compressible spacer (6) mounted on the shaft and located axially between the bearings and the manual clamping device.

2. System according to claim 1, characterized in that the compressible spacer (6) is in the form of a tubular element a polymeric material.

3. System according to claim 2, characterized in that the compressible spacer (6) is made of polyurethane hardness 90 shore A.

4. System according to claim 1, characterized in that the shaft (3) is rigidly fixed to the frame (1) by a first end, and the clamping device (4) comprises a screw (41) adapted to be screwed into a threaded hole (31) formed in the second end of the shaft.

5. System according to claim 1, characterized in that the shaft (103) has a first threaded end (1031) adapted to be screwed into a sheath. (11) secured to the frame, and the clamping device (104) is mounted on the second end of the shaft.

6. System according to claim 1, characterized in that the shaft comprises a ball lock system (2032), the first end of the shaft, comprising the balls, is engaged in a sleeve (12) integral with the frame and there is held axially by said balls, and the clamping device (204) is mounted on the second end of the shaft.

7. System according to claim 1, characterized in that a spacer (24) is placed between the inner rings of the bearings (22, 23).

8. System according to claim 4, characterized in that the cam lever (5) is pivotally mounted on the head (42) of the screw and acts on a pusher (51) resting on the compressible spacer (6).

9. System according to claim 5 or 6, characterized in that the manual clamping device (104, 204) comprises a cam lever (105, 205) pivotally mounted on the second end of the shaft and acting on a pusher ( 1051, 2052) resting on the compressible spacer.