EP2893912A1 - Hospital chair with hinged foot support - Google Patents

Abstract

Wheelchair (1) comprising: a chassis (2), a seat (6) and wheels (13), - a brake, a mechanism for actuating the brake, which comprises: a cam equipped with a detent, o a return spring; - a footrest (44) independent of the seat (6) and movable relative to the frame (2), - a mechanism (45) for actuating the footrest (44); - A control lever (36) rotatably mounted relative to the frame (2), the lever (36) being integral in rotation with the cam and coupled to the mechanism (45) for actuating the footrest (44).

Description

The invention relates to the field of armchairs, and more particularly the chairs for moving people in a medical environment.

This type of chair is particularly used in hospitals or retirement homes to allow the transfer of patients by caregivers.

There are different types of chairs depending on the needs.

In a hospital environment, a medical chair must allow easy movement of patients while being both robust and easy to maintain. By way of illustration, reference may be made, for example, to the patent US 2,522,729 (TRAVIS) which presents a medical chair with a frame, a seat, a backrest, wheels and a footrest.

The furniture intended for retirement homes must also fulfill the same medical functions, without neglecting the aesthetic aspect. In fact, residents of retirement homes are looking for a living space closer to that of everyday life. As a result, the furniture manufacturers have created a range of furniture that is visually close to the usual furniture, while including medical features.

The patent GB 2,473,423 (VERNACARE) and presents a wheelchair equipped with a footrest integral with the seat of the chair, the footrest being movable between a low position and a high position by being actuable at the initiative of the patient, and more particularly by the patient's sitting or raising movements: when the patient sits on the chair, his weight raises the footrest by a return mechanism; conversely, when the patient gets up, the footrest is released, and can resume its low position. This chair is also equipped with a wheel locking system, which can however be operated by the caregiver.

This chair appears functional only in theory. In practice, however, the footrest does not facilitate the movement of the patient. Indeed, it is only in the low position that the footrest allows the patient to get up. However, to place the footrest in the low position, the patient must release the seat of his weight, which he can do only by the strength of his arms. But the elderly, who represent the majority of targeted patients, usually have no more strength in their arms. So that they can not get up alone from this chair and must therefore be assisted by caregivers who are then exposed to lumbago, tendinitis and other hernias.

A first goal is to provide a chair that contributes to the autonomy of patients.

A second goal is to make it simpler and safer to use chairs for caregivers.

A third objective is, more particularly, to provide a chair facilitating the work of the caregiver for the exit and entry of a patient in the chair.

A fourth objective is to propose a chair that is simple to manufacture and maintain.

A fifth objective is to offer a chair that is robust.

A sixth goal is to provide a chair that is lightweight to allow easy movement of patients.

• un châssis, une assise montée sur le châssis et des roues montées sur le châssis, ces roues ayant chacune une bande de roulement et définissant ensemble un plan de roulage,
• au moins un frein muni d'un patin et d'un doigt formant suiveur de came, ce frein étant déplaçable en translation par rapport au châssis entre une position de freinage dans laquelle le patin est appliqué contre la bande de roulement d'une roue, et une position de roulage dans laquelle le patin est écarté de la bande de roulement,
• un mécanisme d'actionnement du frein, qui comprend :
  • ∘ une came coopérant avec le doigt, cette came étant montée en rotation par rapport au châssis entre une position de roulage dans laquelle, via le doigt, la came laisse le frein occuper sa position de roulage, et une position de freinage dans laquelle, via le doigt, la came place le frein dans sa position de freinage, cette came étant munie d'un cran d'arrêt dans lequel, en position de roulage, le doigt du frein est logé ;
  • ∘ un ressort de rappel qui sollicite le frein vers sa position de roulage ;
• un repose-pied monté sur le châssis, ce repose-pied étant indépendant de l'assise et mobile par rapport au châssis entre une position basse dans laquelle le repose-pied s'étend au voisinage du plan de roulage, et une position haute écartée de la position basse,
• un mécanisme d'actionnement du repose-pied, qui comprend un bras de levage relié au repose-pied et monté articulé par rapport au châssis, et une tringle portant, à une extrémité avant, un suiveur de came en appui contre le bras de levage ;
• un levier de commande monté en rotation par rapport au châssis, ce levier étant solidaire en rotation de la came et couplé à la tringle par une extrémité arrière de celle-ci, ce levier étant mobile entre :
  • ∘ une position de freinage dans laquelle le levier place la came en position de freinage et dans laquelle le levier permet au repose-pied d'occuper sa position basse,
  • ∘ une position de roulage dans laquelle le levier place la came en position de roulage et dans laquelle, via la tringle, le levier place le repose-pied dans sa position haute.

For this purpose, it is proposed a wheelchair comprising:

• a chassis, a seat mounted on the chassis and wheels mounted on the chassis, these wheels each having a tread and together defining a rolling plane,
• at least one brake provided with a shoe and a follower pin, this brake being displaceable in translation relative to the chassis between a braking position in which the shoe is applied against the tread of a wheel, and a rolling position in which the pad is moved away from the tread,
• a brake actuation mechanism, which comprises:
  • A cam cooperating with the finger, this cam being rotatably mounted relative to the chassis between a rolling position in which, via the finger, the cam allows the brake to occupy its rolling position, and a braking position in which, via the finger, the cam places the brake in its braking position, this cam being provided with a detent in which, in the rolling position, the brake finger is housed;
  • A return spring which urges the brake towards its rolling position;
• a footrest mounted on the frame, this footrest being independent of the seat and movable relative to the frame between a low position in which the footrest extends in the vicinity of the rolling plane, and a high position spaced apart from the low position,
• a footrest actuating mechanism, which includes a lift arm connected to the footrest and hinged to the frame, and a rod carrying at a front end a cam follower bearing against the lift arm ;
• a control lever rotatably mounted relative to the frame, this lever being integral in rotation with the cam and coupled to the rod by a rear end thereof, this lever being movable between:
  • A braking position in which the lever places the cam in the braking position and in which the lever allows the footrest to occupy its low position,
  • ∘ a rolling position in which the lever places the cam in rolling position and in which, via the rod, the lever places the footrest in its high position.

In this way, in the braking position, the footrest finds, by simple gravity, its low position which allows the patient to get up without necessarily having to use the arms. In addition, in rolling position, the footrest remains in its upper position because the weight of the patient's legs exerted on the footrest is too low to produce on the axis of the cam a couple to dislodge from the stop to the brake finger.

• en position de roulage, le bras de levage forme avec le plan de roulage un angle compris entre 10 et 20°, et de préférence de 15° environ ;
• en position de roulage, la tringle forme avec le bras de levage un angle compris entre 5 et 15°, et de préférence de 10° environ ;
• le bras de levage comprend une plaque d'appui, et le suiveur de came porté par la tringle se présente sous forme d'un galet en contact roulant avec la plaque d'appui ;
• le mécanisme d'actionnement du repose-pied comprend une paire de bras de levage superposés, à savoir un bras supérieur et un bras inférieur, montés articulés, d'une part, par rapport au châssis par une extrémité arrière et, d'autre part, par rapport au repose-pied par une extrémité avant pour former un parallélogramme déformable ;
• la tringle est pourvue d'une fenêtre oblongue qui coopère avec un pion de guidage solidaire du châssis ;
• le pion de guidage est coaxial avec l'articulation du bras inférieur de levage ;
• le levier comprend une paire de pédales qui s'étendent à l'opposé l'une de l'autre à partir d'un axe d'articulation du levier, à savoir une pédale supérieure de commande de la position de freinage, et une pédale inférieure de commande de la position de roulage, la tringle du mécanisme d'actionnement du repose-pied étant couplée au levier en étant articulée sur la pédale inférieure.

Various additional features may be provided, alone or in combination:

• in rolling position, the lifting arm forms with the rolling plane an angle of between 10 and 20 °, and preferably about 15 °;
• in the rolling position, the rod forms with the lifting arm an angle of between 5 and 15 °, and preferably about 10 °;
• the lift arm comprises a support plate, and the cam follower carried by the rod is in the form of a roller in rolling contact with the support plate;
• the actuating mechanism of the footrest comprises a pair of superposed lifting arms, namely an upper arm and a lower arm, mounted articulated on the one hand, with respect to the chassis by a rear end and on the other hand , relative to the footrest by a front end to form a deformable parallelogram;
• the rod is provided with an oblong window which cooperates with a guiding pin integral with the frame;
• the guide pin is coaxial with the articulation of the lower lifting arm;
• the lever comprises a pair of pedals which extend away from each other from an articulation axis of the lever, namely a top pedal for controlling the braking position, and a pedal lower control of the rolling position, the rod of the actuating mechanism of the footrest being coupled to the lever being hinged to the lower pedal.

• la figure 1 est une vue en perspective, de dessus et par l'avant, d'un fauteuil muni d'un repose-pied articulé ;
• la figure 2 est une vue partielle en perspective de dessous du fauteuil de la figure 1 avec, en médaillon, un détail à échelle agrandie du mécanisme d'actionnement du repose-pied ;
• la figure 3 est une vue en partielle en perspective, de dessus et par l'arrière, du fauteuil des figures précédentes ;
• la figure 4 est une vue partielle en coupe du fauteuil des figures précédentes, illustrant la position de roulage ;
• la figure 5 est une vue de détail en coupe illustrant le frein et son mécanisme d'actionnement en position de roulage, avec, en médaillon, un détail à échelle agrandie centré sur la came ;
• la figure 6 est une vue similaire à la figure 4, illustrant la position de freinage ;
• la figure 7 est une vue similaire à la figure 5, en position de freinage.

Other objects and advantages of the invention will become apparent in the light of the description of an embodiment, given hereinafter with reference to the accompanying drawings, in which:

• the figure 1 is a perspective view, from above and from the front, of a chair with an articulated footrest;
• the figure 2 is a partial perspective view from below of the armchair of the figure 1 with, in medallion, an enlarged detail of the mechanism of actuation of the footrest;
• the figure 3 is a partial perspective view, from above and from the rear, of the chair of the preceding figures;
• the figure 4 is a partial sectional view of the chair of the preceding figures, illustrating the rolling position;
• the figure 5 is a sectional detail view illustrating the brake and its actuating mechanism in the rolling position, with, inset, an enlarged detail centered on the cam;
• the figure 6 is a view similar to the figure 4 , illustrating the braking position;
• the figure 7 is a view similar to the figure 5 , in the braking position.

On the figure 1 is represented a wheelchair 1 designed to facilitate, in a medical environment (including hospital, retirement home or even home), the transfer of patients with reduced mobility, typically elderly people whose legs are no longer strong enough to allow them to walk over distances greater than a few meters.

This chair 1 comprises, in the first place, a frame 2 provided with a pair of longitudinal members 3 and a central cross member 4 connecting the longitudinal members 3.

The chair 1 comprises, in the second place, a seat 5 intended to accommodate a patient and provided for this purpose with a seat 6 and a backrest 7, as well as, where appropriate (as in the illustrated example), armrests 8 and a headrest 9. The seat 5 is mounted on the frame 2, for example by means of a jack 10 secured to the cross member 4, in which is housed a rod 11 of the jack secured to the seat 6.

Various adjustments can be provided: the seat 6 can be adjustable in height and / or depth (that is to say longitudinally); the armrests 8 can be adjustable in height and / or width; the headrest 9 can be adjustable in height and / or inclination.

The chair 1 comprises, thirdly, wheels 12, 13 mounted on the frame 2. As can be seen in particular on the Figures 1 to 4 , the chair 1 comprises, in the example shown, four wheels 12, 13, namely two front wheels 12 and two rear wheels 13 . Each wheel 12, 13 is mounted at the end of a spar 3.

Each wheel 12, 13 comprises a rim 14 rotatably mounted on an axis 15 integral with a yoke 16 itself rotatably mounted about a vertical axis relative to a liner 17 formed at the end of the spar 3.

Each wheel 12, 13 furthermore has a rolling band 18 , preferably rubberized, which surrounds the rim 14.

The wheels 12, 13 together define a rolling plane 19 which, when the chair is placed on a floor devoid of asperities, is coincident with it.

The chair 1 preferably comprises a handlebar 20 mounted behind the backrest 7 to allow the seizure and movement of the chair 1 by a caregiver, in the manner of a carriage.

The chair 1 comprises, fourthly, at least one brake 21 designed to lock at least one of the wheels 12, 13. In the example shown, the chair is equipped with two brakes 21, associated with the rear wheels 13 .

Each brake 21 comprises a slider 22 at a lower end of which is fixed a shoe 23 having a complementary surface of the tread 18 . The brake 21 further comprises a finger 24 secured to the slide 22, at an upper end thereof. As illustrated on figures 5 and 7 this finger 24 preferably has a conical shape, rounded at its end. The brake 21 is displaceable in translation relative to the chassis 2 (and more precisely with respect to the sleeve 17 ) between a rolling position ( figure 5 ) in which the shoe 23 is spaced apart from the tread band 18 , and a braking position in which the shoe 23 is applied against the tread 18 ( figure 7 ), which, under normal conditions of use (non-slippery floor, patient of reasonable weight), frictionally blocks the chair 1 in position. An additional mechanism (not shown) may be optionally provided for, in the braking position, further block the rotation of the wheel about its vertical axis.

The chair 1 comprises, fifthly, a mechanism 25 for actuating the brake 21. This mechanism 25 comprises a return spring 26 , preferably a compression spring, which urges the brake 21 towards its rolling position. In the illustrated example, the spring 26 is interposed between a shoulder 27 formed inside the liner 17, and an enlarged upper portion 28 of the slider 22.

The mechanism 25 for actuating the brake 21 also comprises a cam 29 cooperating with the finger 24 to move the brake 21. This cam 29 is rotatably mounted relative to the frame 2 (and more precisely with respect to the sleeve 17 ) around of a horizontal axis, between a rolling position in which the cam 29 leaves (via the finger 24 ) the brake 21 occupy its braking position, and a braking position in which the cam 29 places (via the finger 24 ) the brake 21 in its rolling position.

As can be seen in the medallions of figures 5 and 7 , the cam 29 is provided with a detent 30 which is adapted to receive the finger 24. This stop 30 is, in the illustrated example, formed by a notch hollowed radially in a periphery 31 (also essentially circular) of the cam 29.

As we also see in the medallions of detail of figures 5 and 7 , the cam 29 comprises a second notch 32, adjacent the first notch 30 and separated therefrom by a tooth 33 projecting, and a ramp 34 which connects the second notch 32 to the circular periphery 31 of the cam 29. The cam 29 comprises, at its center, a hole 35 with a hexagonal contour.

The chair 1 comprises, sixth, a control lever 36 , rotatably mounted relative to the frame 2, designed to drive the cam 29 in rotation and thus actuate or release the brake (s).

More specifically, this lever 36 is rotatably mounted on the sleeves 17 around a horizontal articulation axis 37 . The lever 36 is made integral in rotation with the (or each) cam 29 by means of a pin 38 of hexagonal section threaded into the central hole 35, complementary to the cam 29. As seen in the example shown in the figure 3 the hinge axis 37 is not necessarily unitary: it is here formed by two coaxial hinges 37 carried by each of the folders 17.

• ∘ une position de freinage dans laquelle le levier 36 place la came 29 en position de freinage,
• ∘ une position de roulage dans laquelle le levier 36 place la came 29 en position de roulage.

The lever 36 is movable between:

• A braking position in which the lever 36 places the cam 29 in the braking position,
• ∘ a rolling position in which the lever 36 places the cam 29 in rolling position.

According to an embodiment illustrated on the figure 3 , the lever 29 comprises a pair of pedals 39, 40 which extend away from each other from the articulation axis 37 of the lever 36, namely a pedal 39 of the upper control. the braking position, and a lower pedal 40 for controlling the rolling position. The upper pedal 39 is here formed of two non-contiguous L-shaped sections 41 . As for the lower pedal 40 , it is advantageously monobloc, and comprises a transverse bar 42 which connects to the joints by two bent end sections 43 .

In the rolling position, the cam 29 is oriented angularly so that the first notch 30 opens downwards, the finger 24 being housed ( figure 5 ) under the action of the return spring 26 which urges the finger 24 towards the axis of the cam 29.

The tooth 33 opposes the rotation of the cam 29 by exerting on the flank of the finger 24 an essentially tangential force. To dislodge the finger 24 from the notch 30, it is necessary to print the cam 29 (by pushing on the pedal 39 upper, as suggested by the arrow F1 on the figure 6 ) a rotational movement (in the direction of arrow F2 in the detail medallion of the figure 7 ) by applying a motor torque greater than a threshold value for pushing the finger 24, against the spring 26 of return (arrow F3 in the detail of the medallion of the figure 7 ), by sliding the tooth 33 on the end of the finger 24.

The spring 26 is calibrated, and the cam 29 dimensioned, so that the threshold value of the engine torque is greater than or equal to 5 Nm. According to a preferred embodiment, this threshold value is between 5 Nm and 30 Nm. It is possible , but disadvised, to exceed this last value, because the lever arm (in other words, the length of the upper pedal 39 , measured from the axis 37 of articulation of the lever 36 ) necessary to manipulate the cam 29 is then relatively important, and further exposes the cam 29 to a risk of rupture. This question is addressed again below.

The chair 1 comprises, seventh, a footrest 44 mounted on the frame 2, intended to accommodate the feet of the patient and to raise them in relation to the ground during taxiing, while allowing the patient to rest on the ground when he has to get up (with or without help).

This footrest 44 is independent of the seat 6, to which it is connected by any mechanism. The footrest 44 is mobile against the chassis 2, however, between a low position ( figure 4 ) in which the footrest 44 extends in the vicinity of the rolling plane 19 , and a high position spaced from the low position.

The chair 1 comprises, in the eighth place, a mechanism 45 for actuating the footrest 44 to allow the movement thereof from its lower position to its upper position, and vice versa.

This actuating mechanism 45 comprises at least one lifting arm 46 connected to the footrest 44 and articulated relative to the chassis 2.

According to a preferred embodiment illustrated in the figures, the mechanism 45 for actuating the footrest comprises a pair of superimposed lifting arms 46, 47 , namely an upper arm 46 and a lower arm 47 , articulated mounted, of on the one hand, with respect to the chassis 2 (for example by means of bolts 48 forming a rear articulation) by a rear end and, on the other hand, with respect to the footrest 44 by a front end.

As illustrated on the figure 1 each arm 46, 47 is hinged at its rear end to the cross member 4, and extends between the longitudinal members 3 on the side of the front wheels 12 . The articulation on the footrest 44 is effected by means of a yoke 49 in which are received and fixed (for example by means of bolts 50 forming a front articulation) the front ends of the arms 46, 47 of lifting . The arms 46, 47 are of equal length and thus form a deformable parallelogram that moves the footrest 44 while maintaining its attitude constant.

The mechanism 45 for actuating the footrest 44 further comprises a rod 51 coupled to the lever 36 by a rear end and carrying, at a front end, a follower 52 of cam resting against one of the arms 46, 47 of lifting.

According to a preferred embodiment illustrated in the figures, the mechanism 45 for actuating the footrest 44 comprises, for balancing the forces, a pair of identical rods 51 which extend parallel between the longitudinal members 3.

More precisely, and as is visible on the figure 2 , at its rear end, each rod 51 is coupled to the lever 36 by being articulated on the lower pedal 40 , for example on a lug 53 projecting therefrom. The joint is for example made by means of bolts 54.

At their front end, the rods 51 are connected by a shaft 55 carrying a roller (for example a bearing) which forms the cam follower 52 . This roller 52 is in rolling contact with a support plate 56 provided on the upper lifting arm 46 .

As seen in the detail medallion of the figure 2 each rod 51 is provided with an oblong window 57 which cooperates with a guiding pin 58 integral with the frame 2. According to a particular embodiment, this guide peg 58 is coaxial with the articulation of the arm Lower guide 47 on the frame 2. This pin 58 is for example formed by the body of a bolt 48 for fixing the lower arm 47 on the chassis 2.

Maneuvering the footrest 44 is controlled by the lever 36. In the rolling position, the lever 36 places, via the (the) rod (s) 51, the footrest 44 in its upper position. More precisely, the exercise of a thrust (arrow F4, figure 4 ) on the lower pedal 40 causes the rotation of the lever 36 and the movement of the rod 51 towards the front (arrow F5, figure 4 ), the latter being guided by the sliding of the pin 58 in the window 57. The (the) rod (s) 51 then exerts a thrust, via the roller 52, on the support plate 56 and constrained by therefore, the upper arm 46 of lifting to pivot about its hinge 48 back, which jointly drives the rotation of the lower arm 47 and the raising of the leg support 44 towards its raised position (arrow F6, figure 4 ). The angular limit stop of the lever 36 (determining the high position of the footrest 44 ) is formed by the oblong window 57 , at a rear end of which is applied the guide pin 58 . We have seen that in this rolling position, the brake 21 releases the rear wheels 13 . In this way, it is possible for the caregiver to freely move the chair 1, the feet of the patient being raised by the footrest 44 and thus forming no obstacle to driving.

In contrast, in the braking position, the lever 36 allows the footrest 44 to occupy its low position. Indeed, the thrust (arrow F1, figure 6 ) exerted on the upper pedal 39 causes the reverse rotation of the lever 36 and the movement of the rod (s) 51 towards the rear (arrow -F5, figure 6 ). Under the effect of the own weight of the footrest 44 and the arms 46, 47 lifting, to which is added, when the feet of a patient are resting on the footrest 44, the weight thereof, the arms 46, 47 rotate in the opposite direction and the footrest 44 lowers (arrow -F6, figure 6 ) as the roller 52 retracts backward until the footrest 44 reaches its low position. The angular limit stop of the lever 36 (determining the low position of the footrest 44 ) is formed by the oblong window 57 , at a front end of which is applied the guide pin 58 . We have seen that in this braking position, the brake 21 blocks the rear wheels 13 . In this way, the armchair 1 is stationary and the feet of the patient are supported on the ground via the footrest 44, allowing the patient to get up (with or without help).

The architecture of the actuating mechanism of the footrest is such that in rolling position the combined weight of the footrest 44, arms 46, 47 and feet of the patient is insufficient to tilt the lever 36 to its position braking, the torque generated on the articulation axis 37 of the lever 36 being insufficient to dislodge the finger 24 of the notch 30 of the cam 29.

• L1 la longueur des bras 46, 47 de levage, mesurée entre les axes 48, 50 d'articulation ;
• L2 l'entraxe entre le galet 52 et l'articulation 48 arrière du bras 46 supérieur, en position de roulage ;
• L3 la distance de l'articulation 54 arrière de la tringle 51 à l'axe 37 d'articulation du levier 36 ;
• A1 l'angle des bras 46, 47 de levage avec le plan 19 de roulage, en position de roulage ;
• A2 l'angle du bras 46 supérieur de levage avec la tringle 51, en position de roulage ;
• A3 l'angle entre la tringle 51 et le segment (en trait mixte sur la figure 4) joignant l'articulation 54 de la tringle 51 à l'axe 37 d'articulation du levier 36 ;
• F l'effort qui s'exerce sur l'articulation 50 avant du bras 46 supérieur, par les poids combinés des bras 46, 47, du repose-pied 44 et des pieds du patient ;
• C le couple qui s'exerce sur l'axe 37 d'articulation du levier 36, résultant de l'effort F.

We note, with reference to the figure 4 :

• L1 the length of the arms 46, 47 lifting, measured between the axes 48, 50 of articulation;
• L2 the distance between the roller 52 and the rear articulation 48 of the upper arm 46 , in rolling position;
• L3 the distance from the hinge 54 rear of the rod 51 to the axis 37 of articulation of the lever 36;
• A1 the angle of the arms 46, 47 lifting with the plane 19 of rolling, rolling position;
• A2 the angle of the upper lifting arm 46 with the rod 51, in rolling position;
• A3 the angle between the rod 51 and the segment (in dashed line on the figure 4 ) joining the articulation 54 of the rod 51 to the axis 37 of articulation of the lever 36;
• The force exerted on the front articulation 50 of the upper arm 46 by the combined weights of the arms 46, 47, the footrest 44 and the feet of the patient;
• C the torque exerted on the articulation axis 37 of the lever 36, resulting from the effort F.

It is easy to demonstrate that the couple C is calculated using the following formula: $$\mathrm{VS}=F\cdot \mathrm{The}\mathbf{3}\cdot \frac{\mathrm{The}\mathbf{1}}{\mathrm{The}\mathbf{2}}\cdot \mathit{cos}\mathrm{AT}\mathbf{1}\cdot \mathit{sin}\mathrm{AT}\mathbf{2}\cdot \mathit{sin}\mathrm{AT}\mathbf{3}$$

• L1 250 mm
• L2 100 mm
• L3 80 mm
• A1 15°
• A2 10°
• A3 60°
• F 100 N(≈10kg)

An example of values for the above parameters is given below:

• L1 250 mm
• L2 100 mm
• L3 80 mm
• A1 15 °
• A2 10 °
• A3 60 °
• F 100 N (≈10kg)

The formula above allows to deduce the value of the torque C, about 3 Nm. This calculation however does not take account of the friction, in particular between the pin 58 and the edge of the window 47. Indeed, the pin opposes the movement of the rod 51 towards the rear a friction resisting force substantially proportional to the the force F (the coefficient of proportionality depending on the materials chosen for the pin 58 and the bead 51 ) and directed forward, in the axis of the bead wire 51. This effort considerably reduces, in practice, the torque C applied to the axis 37 of articulation of the lever. Anyway, the value of the torque C is much lower than the threshold value (greater than 5 Nm) of the engine torque to maneuver the cam 29 which, consequently, remains in rolling position as long as no sufficient thrust is exerted on the upper pedal 39 .

Since such a push is exerted (at the foot by the caregiver), as suggested by the arrow F1 on the figure 6 , and that this thrust generates on the articulation axis 37 of the lever 36 a torque whose value is greater than the threshold value, the cam 29 can pivot, disengaging the finger 24 from the notch 30, and the brake 21 can be moved towards its braking position while the footrest 44 is simultaneously released by the roller 52 to resume its low position.

L4 denotes the length of the upper pedal 39 , measured from the articulation axis 37 of the lever, and C 'the torque generated on the axis 37 of articulation of the lever by a force, noted F', exerted along the arrow F1 on the upper pedal 39 , for placing the brake 21 in the braking position. The torque C 'is calculated using the following formula: $$\mathit{VS}=\mathit{F\; \text{'}}\cdot \mathrm{The}\mathbf{4}$$

Thus, for a force F 'of 150 N (about 15 kg) and a length L4 of 125 mm, the torque C' generated is 18.75 Nm.

This torque is largely sufficient to maneuver the cam 29, when the threshold value of the engine torque is less than 15 Nm.

By maintaining the length L4, and by exerting a force F 'of 240 Nm (or about 25 kg), the generated torque C' is 30 Nm, allowing to manipulate the cam 29 in all cases (we have seen that 30 Nm is the maximum recommended threshold value).

It should be noted that the numerical values provided above are only exemplary but are however neither imperative nor limiting.

In general, it will be understood that the parameters A1, A2 L1 and L2 in particular make it possible to vary the torque C. To prevent this torque from reaching the threshold value allowing the cam 29 to be manipulated and thus to move the brake 21 in the braking position without action on the lever 36, it will be ensured, preferably, that in driving position the angle A1 does not exceed 20 °, while being advantageously greater than or equal to 10 °. A value of about 15 ° (as in the example proposed above) represents a good compromise.

Likewise, the angle A2 is preferably less than 15 °. A value of about 10 ° (as in the example proposed above) also represents a good compromise.

The chair 1 which has just been described offers a number of advantages.

First, the footrest 44 being independent of the seat 6, it does not force the patient to use the arms to get up. In other words, since the caregiver has actuated the brake 21, the footrest 44 passing in the low position allows the patient to rise while leaning on the ground. This results in a contribution to the autonomy of patients. By "independent" is meant here that the structure and operation of the footrest are not related to the seat, the actuation of the footrest does not depend on the seat. There is thus no functional and structural link between what is above the frame (and in particular the entire structure of the seat, backrest, armrests, headrest that can be made according to different design ), and the chassis structure itself.

Secondly, in the alternative, this increased patient autonomy makes the use of the chair 1 safer and more ergonomic for caregivers, who are not systematically forced to help patients recover.

Thirdly, when the caregiver helps the patient to get up or settle down, he can count on firm support from the patient's feet. on the ground, the footrest 44 being in the low position. The work of the caregiver is thus facilitated.

Fourthly, the mechanisms 25, 45 for operating the brakes 21 and the footrest 44 are relatively simple to manufacture and require few maintenance operations.

Fifth, in a subsidiary manner, these mechanisms 25, 45 are robust and ensure a good life of the chair 1.

Sixth, these mechanisms 25, 45 are compact and lightweight, which lighten the chair 1 and facilitates its use, particularly its movement and handling during (rare) maintenance operations.

The up and down motion of the footrest does not result from the patient sitting or standing up, but is caused by the caregiver. As soon as the caregiver activated the brake, the footrest moved to the lower position, without the patient having to lift the seat by the force of the arms.

Claims (10)

Wheelchair (1) comprising: - a frame (2), a seat (6) mounted on the frame (2) and wheels (12, 13) mounted on the frame (2), these wheels (12, 13) each having a strip (18) of rolling and defining together a rolling plane (19) , - At least one brake (21) provided with a shoe (23) and a finger (24) forming cam follower, the brake (24) being movable in translation relative to the frame (2) between a rolling position wherein the shoe (23) is spaced apart from the tread (18) of a wheel (13), and a braking position in which the shoe (23) is applied against the tread (18) , a mechanism (25) for actuating the brake (21), which comprises: A cam (29) cooperating with the finger (24), this cam (29) being rotatably mounted relative to the frame (2) between a rolling position in which, via the finger (24), the cam (29) allows the brake (21) to occupy its driving position, and a braking position in which, via the finger (24), the cam (29) places the brake (21) in its braking position, A return spring (26) which urges the brake (21) towards its rolling position; - a footrest (44) mounted on the frame (2), movable relative to the latter between a low position in which the footrest (44) extends in the vicinity of the plane (19) of rolling, and a high position separated from the low position, - a mechanism (45) for actuating the footrest (44), which comprises a lifting arm (46) connected to the footrest (44) and articulated relative to the frame (2), and a rod (51). ) carrying, at a front end, a cam follower (52) bearing against the lifting arm (46) ; - A control lever (36) rotatably mounted relative to the frame (2), the lever (36) being integral in rotation with the cam (29) and coupled to the rod (51) by a rear end thereof. this lever (36) being movable between: A braking position in which the lever (36) places the cam (29) in the braking position and in which the lever (36) allows the footrest (44) to occupy its low position, ∘ a rolling position in which the lever (36) places the cam (29) in the rolling position and in which, via the rod (51), the lever (36) places the footrest (44) in its up position , this chair (1) being characterized in that the footrest (44) is independent of the seat (6), and in that the cam (29) is provided with a detent (30) in which in rolling position, the finger (24) of the brake (21) is housed. Armchair (1) according to claim 1, characterized in that , in rolling position, the lifting arm (46) forms with the rolling plane (19) an angle (A 1 ) of between 10 and 20 °. Armchair (1) according to claim 2, characterized in that , in rolling position, the lifting arm (46) forms with the rolling plane (19) an angle (A1) of approximately 15 °. Armchair (1) according to one of the preceding claims, characterized in that , in the rolling position, the rod (51) forms with the lifting arm (46) an angle (A2) of less than 15 °. Armchair (1) according to claim 4, characterized in that the rod (51) forms with the lifting arm (46) an angle (A2) of approximately 10 °. Armchair (1) according to one of the preceding claims, characterized in that the lifting arm (46) comprises a support plate (56) , and in that the cam follower (52) carried by the rod (51) ) is in the form of a roller in rolling contact with the plate (56) support. Armchair (1) according to one of the preceding claims, characterized in that the mechanism (45) for actuating the footrest (44) comprises a pair of superposed lifting arms (46, 47) , namely an arm ( 46) and a lower arm (47) , articulated, on the one hand, with respect to the frame (2) by a rear end and, on the other hand, with respect to the footrest (44) by a front end. to form a deformable parallelogram. Armchair (1) according to one of the preceding claims, characterized in that the rod (51) is provided with a window (57) oblong which cooperates with a guide pin (58) secured to the frame (2). Armchair (1) according to claims 7 and 8, taken in combination, characterized in that the guide pin (58) is coaxial with the hinge (48) of the lower arm (46) lifting on the frame (2). Armchair (1) according to one of the preceding claims, characterized in that the lever (36) comprises a pair of pedals which extend opposite one another from an axis (37) articulation of the lever (36), namely an upper pedal (39) for controlling the braking position, and a lower pedal (40) for controlling the rolling position, the rod (51) of the operating mechanism footrest (44) being coupled to the lever (36) being hinged to the lower pedal (40) .

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