EP0255804A2 - Lightweight wheelchair with adjustable specific balance - Google Patents

Abstract

By adjusting two telescoping-type interengaging shiftable parts for each of two frame bars (3,4) of a support frame (2) of a lightweight wheelchair (1), the sitting position of the same can be adjusted with respect to the seat surface (5) and with it the adjustment of the center of gravity can be dynamically adjusted with respect to the user. Additional adjustment possibilities by means of each support element (17) at the right and left sides of the seat surface (5) with respect to the rear axle as well as corresponding clamping devices for the front wheels (9,10) on the frame (2) allow a very precise user-compatibility in this lightweight wheel chair. Additionally a backrest (6) can be collapsed with respect to the seat surface (5) by means of handles (20) pivotally connected with the frame bars, to thereby permit the lightweight wheelchair (1) to be compactly folded up for transportation purposes.

Description

With the upcoming use of sport in wheelchairs, the balance and general maneuverability of a wheelchair are subject to considerable demands. In this context, the turning speed has become of crucial importance for the so-called sports chairs - especially the basketball wheelchairs.

The change in the center of gravity of a chair increases or decreases the turning speed of the chair, but on the other hand it should not be forgotten that any change in the center of gravity naturally changes and impairs the stability and / or tiltability of the device to a considerable extent.

Furthermore, of course, the general knowledge applies that the more the axles of the two supporting rear wheels are moved to the rear, i.e. in the opposite direction to the two front wheels of a wheelchair, the more stability the wheelchair as such gains. On the other hand, however, the front part of the chair is becoming increasingly difficult - seen from its own weight - and thus of course more difficult to maneuver.

In addition to the actual shift of the center of gravity, the state of the art today also includes the various adjustment options for the seat angle, the backrest angle with respect to the seat surface, and the adjustment options for the camber of the rear wheels in order to shift the center of gravity with respect to the height.

The prior art essentially uses two adjustment criteria to adjust the center of gravity with regard to the seat surface (see, for example, SPORTS AND SPOKES, The Magazine for Wheel Chair Sports and Recreation, March / April 1986, Vol. 11, No. 6, "Adjustability in Light Weight Wheel Chairs "). To constructively solve the shift of the center of gravity under the seat of a wheelchair user, one can use the two rear large drive wheels of a wheelchair. These two drive wheels can usually be adjusted in and against the direction of movement via their axles in cross-country guides by so-called axle support plates, so that the wheels themselves can be adjusted in the direction of the smaller front wheels or away from them.

To adjust the angle of the backrest of a wheelchair with respect to the seat surface, so-called positioning angles are mainly used in the prior art, by means of which the backrest is adjusted depending on the use and then the adjustment via this positioning angle is firmly blocked.

Incidentally, the two front wheels are not directly connected to the frame tube of the seat surface in the prior art, but they are hinged to this frame in such a way that they act on support tubes which run parallel to the seat frame tube. With regard to these, they can then be adjusted again, as is shown, for example, on page 15 of the publication specified above.

It has proven to be very disadvantageous in the prior art that, firstly, an exact setting of the three interacting setting variables: position of the axles of the rear wheels, position of the axles of the front wheels and angle between the seat surface and the backrest are difficult to match. In addition, the two rear wheels are always set individually in such constructions, ie the axles of each individual rear wheel are separated and adjusted separately. It is therefore easy to imagine how easily a small offset from one wheel axle to the other wheel axle can be installed. However, this leads to a transverse position of the actual wheel axis to the seat of the wheelchair user and thus to a (disadvantageous) change in the ability to balance and - very essentially - the directional stability of the wheelchair. Even harder However, it is also possible to control displacements that occur as a result of the fact that the fixing means of one wheel loosen in relation to the other wheel and the possibility of a completely unintentional displacement of one wheel axle with respect to the opposite wheel axle occurs.

The rigid backrest fixation in a selected position results in a maximum of stability, but is very often not necessary at all and is perceived as disadvantageous with regard to rapid adjustment. In addition, the transportability of a wheelchair with a fixed (rigidly attached) backrest is considerably more difficult.

The modularly constructed and articulated suspension of the two front wheels in wheelchair systems according to the prior art has the disadvantage that it is not easy to inspect (use of smaller or larger front wheels often also requires the entire suspension to be replaced), and millimeter-precise adjustment does not appear to be possible.

The camber adjustment of the two rear (carrying) wheels of a wheelchair is realized according to the prior art (see publication mentioned above, page 13, right column) in that the aforementioned guide rail for the axle of the rear wheels with the corresponding longitudinal slot or the support plate is inclined towards the horizontal by placing washers over the lower fastening bolts so that the longitudinal guide experiences a certain inclination. This has various disadvantages, namely that an exact adjustment with such washers is hardly possible, and that practice has also shown that the same inclination of both rear wheels can only be achieved with great effort using washers.

In the known wheelchairs, it is further assumed that, as an additional means of height adjustment, the corresponding axle support plates of the holders of the rear wheels can be attached to the frame of the wheelchair in different positions.

All of these previously mentioned adjustment and positioning options, both the front and the rear wheels of a wheelchair, or their axes have the disadvantage in principle that they can only be changed by so-called static changes to the respective settings and that in addition to the considerable effort to drive is an absolutely millimeter-precise adjustment of the individual settings to be coordinated is not possible.

It is therefore an object of the present invention to provide a lightweight wheelchair, the center of gravity of which can be changed quickly and which is extremely functional.

This is achieved by the characterizing features of claims 1 to 11. Through the telescopic cooperation of the two parts of the frame tubes - to extend or shorten the seat in connection with the backrest telescopically as required and on the other hand to shift the center of gravity of the body to the drive wheels, a very quickly achievable serious influence on the balance point of the Wheelchair reached and the maneuverability and flexibility of the lightweight wheelchair according to the invention represents a balance regulation that eliminates the usual forward or backward movement of the rear wheels on the frame - as is customary in the prior art.

An advantageous further development is also the steplessly height-adjustable front wheel suspension on the front frame tube. This means that on the one hand the level difference of the different front wheel sizes can be recorded and precisely adjusted and on the other hand a stepless lowering or raising of the front frame body can be achieved. Here too, millimeter-precise adjustment for the frame, floor seat height, front wheel dimensions and front wheel track can be achieved on one and the same component (frame tube).

An additional development is the stepless height adjustment of the rear wheel axle with respect to the frame or the seat, which can be adjusted with a clamping block At any time, even if the seat angle has been changed, to be able to adjust the track again with millimeter accuracy, a spirit level is provided in the center of the rigid, continuous axle guide. The angled bores of the rear wheel axle for introducing the actual wheel axles in turn result in the advantage that the actual - common - axle runs completely straight and thus any spring effect - in the course of this axle - is avoided.

• Fig. 1 eine perspektivische Darstellung eines ersten Ausführungsbeispieles des erfindungsgemässen Leichtgewichtsrollstuhles,
• Fig. 2 den Leichtgewichtsrollstuhl von Fig. 1 von hinten gesehen,
• Fig. 3 den Leichtgewichtsrollstuhl von Fig. 1 mit im Sturz geneigten Hinterrädern,
• Fig. 4 eine Prinzipdarstellung von Fig. 1 mit dem Bewegungsmechanismus der umklappbaren Rücken­lehne,
• Fig. 5 der Leichtgewichtsrollstuhl von Fig. 1 mit nach hinten vergrösserter Sitzfläche,
• Fig. 6 der Leichtgewichtsrollstuhl von Fig. 1 mit nach hinten verlagertem Schwerpunkt.
• Fig. 7
  • a) eine Detailvergrösserung aus Fig. 3 in teilwei­ser Schnittdarstellung;
  • b) eine Seitenansicht aus Fig. 7 a)

Embodiments of the invention are described below with reference to the drawings. Show it:

• 1 is a perspective view of a first embodiment of the lightweight wheelchair according to the invention,
• 2 seen the lightweight wheelchair of FIG. 1 from behind,
• 3 shows the lightweight wheelchair of FIG. 1 with rear wheels inclined in the camber,
• 4 shows a schematic diagram of FIG. 1 with the movement mechanism of the foldable backrest,
• 5 shows the lightweight wheelchair of FIG. 1 with the seat enlarged to the rear,
• Fig. 6, the lightweight wheelchair of Fig. 1 with the center of gravity shifted to the rear.
• Fig. 7
  • a) an enlarged detail from FIG. 3 in a partial sectional view;
  • b) a side view from FIG. 7 a)

The lightweight wheelchair 1 shown in Figures 1 to 6 consists in a conventional manner of a support frame 2 and two rear wheels 7 and 8 and two front wheels 9 and 10. Between the two frame tubes 3 and 4, a covering 5A of the seat 5 is drawn on the one hand and on the other a covering 22A of a leg rest 22 is provided. The connection of the two frame tubes 3 and 4 represents the footrest 19. The two tubes 20 are connected to the frame tubes 3 and 4 and provided with a backrest covering 6A of the backrest 6. The two rear wheels 7 and 8 are connected to one another via a rigid rear wheel axle 14. The frame tubes 3 and 4 are each supported on the rear wheel axle via a support element 17 and a holding device 18. If the rear wheels must have a camber adjustment, the rear wheel axle 14 contains a spirit level 16A, via which, depending on the setting of the two front wheels 9 and 10, the axis in the clamping device 18 is rotated until the spirit level is at zero, i.e. until the two rear wheels are exactly parallel with respect to the direction of movement and therefore no so-called 'digging of the chair', i.e. unusually strong increase in frictional resistance.

Fig. 2 shows an embodiment of a rear wheel axle 14 without the possibility of camber adjustment of the two rear wheels 7 and 8, and thus in this embodiment there is also no water level, by means of which the axle position must be able to be centered exactly.

Fig. 3 shows exactly the example with cambered rear wheels. In this embodiment, angularly drilled wheel axle receiving devices 15 are provided, which in turn means that different wheel axles can be used in such a lightweight wheelchair for each different camber adjustment and, as said, if the camber adjustable wheel bearing bores 15 have a spirit level 16A around the centering ensure.

The lightweight wheelchair with the completely telescopically retracted frame tube pieces 3A and 3B (FIG. 4), that is to say the sitting position is shifted farthest forward in this drawn position. Otherwise, these frame tube parts 3A and 3B are connected to the rear axle 14 via a support element 17 and a corresponding holding device 18. The holding device 18 is designed as a clamping device, for example made of plastic or metal, and the support element 17 is infinitely adjustable in this holding device 18, so that the actual seat height, which is represented by the frame tube sections 3A and 3B, can be set as desired. 4 is an infinitely adjustable suspension 11 for the two front wheels 9 and 10. This stepless suspension 11 consists of two parts, namely a clamping tab 12 and a torsionally elastic wheel bearing 13 in which one or the other of the two front wheels 9 and 10 is guided. 4 also shows the locking joint 23, which represents the connection point between the second part of the telescopic frame tube 3 and the spars 20. About this locking joint 23rd the entire backrest can be brought into the 20ʹ and 20ʹʹ position using spars 20.

FIG. 5 shows the counterpart of FIG. 4, namely a fully extended telescopic second section of the frame tube 3B and a light-weight wheelchair which has been lowered considerably in height with respect to FIG. 4. In fact, in FIG. 5 the support element 17 in the holding device 18 is very strong moved below and the same also applies to the clamping tab 12. Here too, the frame piece 3A and thus the footrest 19 is lowered to the maximum to the floor to be driven on. In Fig. 5, the rear wheel 7 is drawn in an extended and in a dashed position. The extended position shows the principle of the pre-sketched structure. The dashed position 7ʹ belongs to the holding device position 18ʹ. It is namely a further advantage of the constructive solution that the holding device 18 only has to be released on the support element 17 and with respect to the holder relative to the axle 14, and can simply be rotated through 180 °, which then leads to a new position of the rear wheel axle 14, and thus enabling a completely new course of focus.

6 shows a further possibility of adjusting the center of gravity, in which the seat 5A between the two frame tubes 3 and 4 is inclined slightly to the rear. This is achieved by lowering the support element 17 in the holding device 18 as far as possible, so that the disproportionate increase in the front seat surface can be achieved via the clamping tab 12 of the front wheel 9.

In Fig. 7 a) an enlarged detail representation - partly in section - of an end piece 26 of the rear wheel axle 14 is shown. In this case, a thru axle 25 of one of the rear wheels 7 or 8 is clamped between the corresponding wheel hub 24 and a plurality of balls 27 which can be spread into a groove 28 in such a way that a faultless bearing, both axially and radially free of play, is ensured.
(FIG. 7 b) only shows the side view of the illustration shown in FIG. 7 a).)

Claims (13)

1. Balance-specifically adjustable lightweight wheelchair (1), in particular a basketball wheelchair, with a seat (5) arranged on a support frame (2) and on its two frame tubes (3, 4), an angle-adjustable backrest connected to the support frame (2) ( 6), two camber-adjustable rear wheels (7, 8) articulated on the support frame (2) and two front wheels (9, 10) adjustable with respect to the rear wheels (7, 8),
characterized in that the frame tubes (3, 4) of the seat surface (5) are at least two parts (3A; 3B) and telescopically adjustable against each other. 2. Balance-specific adjustable lightweight wheelchair, according to claim 1,
characterized in that the front wheels (9, 10) are articulated to the respective frame tube (3B; 4) via a continuously adjustable suspension (11). 3. Balance-specific adjustable lightweight wheelchair, according to one of the preceding claims,
characterized in that the seat (5) has a covering (5A) which can be connected to a backrest covering (6A). 4. Balance-specifically adjustable lightweight wheelchair, according to one of the preceding claims,
characterized in that the backrest (6) can be folded down onto the seat surface (5) (FIG. 4). 5. Balance-specifically adjustable lightweight wheelchair, according to one of claims 1 to 4,
characterized in that the continuously adjustable suspension (11) is formed by a clamping tab (12) to which a wheel bearing (13) is attached in a torsionally elastic manner. 6. Balance-specifically adjustable lightweight wheelchair, according to one of claims 1 to 5,
characterized in that the two rear wheels (7, 8) are connected via a common, angled wheel axle mounting holes (15) having rear wheel axle (14). 7. Balance-specifically adjustable lightweight wheelchair, according to claim 6,
characterized in that the rear axle (14) has a centering device (16) for adjusting the wheel axle mounting bores (15). 8. Balance-specifically adjustable lightweight wheelchair, according to claim 7,
characterized in that the rear wheel axle contains a shaping device (15A), via which the wheel axle mounting bores (15) can be adjusted according to the centering device (16). 9. Balance-specifically adjustable lightweight wheelchair, according to claim 8,
characterized in that the centering device (16) comprises a spirit level (16A). 10. Balance-specific adjustable lightweight wheelchair, according to one of claims 1 to 9,
characterized in that the support frame (2) or its two frame tubes (3, 4) are connected to the rear wheel axle (14) via support elements (17) and a holding device and clamping device (18). 11. Balance-specific adjustable lightweight wheelchair, according to claim 10,
characterized in that the holding device (18) comprises a continuously adjustable clamping device (18A). 12. Balance-specifically adjustable lightweight wheelchair, according to one of the preceding claims,
characterized in that the rear wheels (7, 8) are connected to the rear wheel axle (25) via an axially and radially free play in an end piece (26) of the rear wheel axle (14). 13.Balance-specific adjustable lightweight wheelchair, according to claim 12, characterized in that the thru-axle (25) is guided via expandable balls (27) in a groove (28) of the end piece (26).

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