EP1631230B1 - English cane for a person with mobility impairment - Google Patents

Abstract

English cane for a person with mobility impairment, comprising in its internal part a linear actuator ( 7 ) likely to transfer pulling and pushing loads and having on one hand a pair of toothed belts ( 18, 18 ') equipped respectively with regularly spaced pads( 19, 19 ') on their face opposed to the toothed face, and having on the other hand driving members ( 11, 11 ') positioned on the opposed sides of said pair of toothed belts ( 18, 18 ') and cooperating with actuating means to allow the pads ( 19, 19 ') of said belts ( 18, 18 ') to engage with one another, with the result that said belts are flexible and mutually independent at a first length on one side or upstream of the driving members ( 11, 11 '), while at a second length on the opposite side or downstream of said driving members ( 11, 11 ') said belts are securely attached and extend in a straight line as an integral rigid bar suitable to transfer pushing loads as well as pulling loads.

Description

The present invention relates to an English cane for a person with a motor disability.

Such a rod conventionally comprises a telescopic tube consisting of at least two segments of tubes that can slide into one another, namely an upper tube segment and a lower tube segment and equipped at its upper end with a handle ergonomic device comprising a large cylinder portion extending transversely to the longitudinal axis of the telescopic tube and serving as a palmar support and a portion extending upwardly from the palmar support portion, obliquely to the longitudinal axis of the telescopic tube and which serves as antebrachial support.

There is a large number of people with temporary or permanent motor impairments who are struggling to get up, to sit or to tackle or to cross obstacles such as steps or gradients.

Canes, especially known English canes certainly provide significant assistance in terms of safety to the people who use them, but this help is not always sufficient to make these people completely autonomous, when they have a relatively heavy disability, so that they have to be helped by another person.

The present invention therefore aims to provide an English cane for giving a person with a motor disability greater autonomy to overcome a difficulty such as getting up from a seat, sit on it, or tackle obstacles like steps or gradients.

For this purpose, the present invention relates to an English cane of the type defined in the preamble, characterized in that it is equipped at its inner part with a linear actuator capable of transmitting tensile and thrust forces and comprising one part two identical toothed belts respectively provided with regularly spaced studs on their face opposite to the notched face, and secondly drive members located on either side of the two toothed belts and cooperating with actuating means to allow the pads of these belts to engage one into the other, so that they are flexible and independent of each other at a first section located on one side or upstream side of driving organs, then that at a second section located on the opposite side or downstream side of these bodies, they are joined together and extend in a straight line by behaving as a rigid bar in one piece capable of transmitting thrust forces like pulling efforts.

According to the invention, the drive members and the actuating means are housed in a housing fixed to the upper end of the upper tube segment and shaped to serve as an ergonomic handle so that the first section of the two toothed belts extends into the antebrachial support portion of the ergonomic handle while the second section of these belts extends into the upper tube segment and is attached to the inner portion of the lower tube segment through its downstream end.

The actuation of the drive members causes the sliding of the second section of the toothed belts to the inner part of the telescopic tube and the modification of the length of this tube.

It should be noted that it had already been proposed in accordance with EP 0 541 935 a motorized English cane to give greater autonomy to a person with a motor disability.

Such an English cane is in particular equipped with a telescopic rod whose sliding is controlled by an electric motor cooperating with actuating means with threaded rod and ball nut.

It should also be noted that according to the document FR at 2,826,422 it has already been proposed a linear actuator belt capable of transmitting tensile forces and thrust in the field of mechanics and more particularly small automation.

According to the invention, the actuating means preferably comprise a two-way electric motor powered by a rechargeable storage battery and a gear reduction mechanism which is coupled to the motor and comprises two pinions. output respectively engaging with the two toothed belts and constituting the drive members.

To allow the English cane to perform its function, the linear actuator must of course have a chosen power sufficient to provide a thrust corresponding to a substantial part of the weight of a person resting on the ergonomic handle.

According to another characteristic of the invention, the linear actuator comprises control means carried by the ergonomic handle for controlling the start / stop as well as the direction of rotation of the electric motor.

These control means may comprise a reversing switch with two unstable closing positions and a stable intermediate position of cutoff.

Such an inverting switch may advantageously comprise an actuating member which projects radially on the large cylinder portion serving as a palmar support, in the region of the free end of this large cylinder portion so that it can be actuated by an inch. from the hand of a cane user holding this part in big cylinder.

The storage battery is preferably electrically connected to an electrical connector accessible from outside the housing to allow charging of this storage battery by means of a battery charger.

According to a particularly advantageous characteristic of the invention, the housing consists of two half shells, in particular made of a molded plastic, for example polyethylene, which have a joint plane corresponding to the vertical median plane of symmetry of the ergonomic handle and are assembled by means of screws.

These two half-shells preferably each comprise a rib at the inner part of their part corresponding to the part forming antebrachial support of the ergonomic handle after assembly of the two half-shells.

These two ribs together define a separating partition isolating the first flexible and independent sections of the two toothed belts.

According to another particularly advantageous feature of the invention, the housing has, in the connection zone between the palmar bearing portion and the antebrachial support portion of the ergonomic handle, a hollow bulging portion within which the motor is arranged. electric, the speed reduction mechanism and the storage battery.

• la figure 1 est une vue latérale, en coupe verticale, d'une canne selon l'invention ;
• la figure 2 est une vue de derrière en partie en coupe verticale, de la canne de la figure 1 ;
• les figures 3 et 4 sont des vues correspondant respectivement à celles des figures 1 et 2, montrant la partie supérieure de la canne à une plus grande échelle ;
• les figures 5, 6 et 7 sont des vues en coupe respectivement suivant les lignes V-V, VI-VI et VII-VII de la figure 3 ;
• la figure 8 est un schéma montrant le circuit électrique utilisé dans la canne selon l'invention.

Other features and advantages of the present invention will become more apparent in the following description of a method of embodiment given by way of example with reference to the accompanying drawings in which:

• the figure 1 is a side view, in vertical section, of a cane according to the invention;
• the figure 2 is a back view partly in vertical section, of the cane of the figure 1 ;
• the Figures 3 and 4 are views corresponding respectively to those of the Figures 1 and 2 , showing the upper part of the cane on a larger scale;
• the Figures 5, 6 and 7 are sectional views respectively along the lines VV, VI-VI and VII-VII of the figure 3 ;
• the figure 8 is a diagram showing the electric circuit used in the rod according to the invention.

Referring to Figures 1 and 2 it can be seen that the rod according to the invention comprises, in a conventional manner, a telescopic tube 1 provided with an ergonomic handle 2 at its upper end and a non-slip rubber tip 3 at its lower end.

The ergonomic handle 2 comprises a part 2a, in large cylinder, which extends transversely to the longitudinal axis of the telescopic tube 1 and which serves as a palmar support, and a portion 2b which extends upwards from part 2a obliquely to the longitudinal axis of the telescopic tube and which serves as antebrachial support.

The telescopic tube 1 comprises at least two tube segments, preferably three tube segments, namely an upper segment la, an intermediate segment 1b and a lower segment 1c, which can slide into each other. The tube segments 1a, 1b and 1c may be of light metal or light metal alloy such as duralumin, or they may be of a composite material based on glass fibers or carbon.

Preferably, the rod comprises, in known manner, means for adjusting the length of the telescopic tube 1 to the size of the person or persons who are likely to use said rod. For this purpose the lower tube segment 1c comprises a pair of diametrically aligned holes 4, the intermediate tube segment 1b comprises two series of regularly spaced holes 5, each hole 5 of a series being diametrically aligned with the hole 5 of the another series, and an anchor 6. To adjust the length of the telescopic tube 1, simply align the two holes 4 of the segment 1c with a chosen pair of holes 5 of the segment 1b and engage the pin 6 in the holes 4 and 5 thus aligned.

The rod according to the invention comprises an actuator 7 reversible linear movement, which is functionally associated with the tube segments 1a and 1b to move longitudinally relative to each other in both directions.

As is best seen in the Figures 3 and 4 the linear actuator 7 comprises an electric motor 8 with two directions of rotation, a speed reduction gear mechanism 9 which is coupled to the motor, and a thrust chain 10 which is engaged with output gears 11 and 11 ' of the speed reduction mechanism 9. More specifically, the speed reduction mechanism 9 comprises a first pinion 12 which is fixed to the output shaft 13 of the motor 8 and which meshes with a toothed wheel 14 integral with an endless screw 15 which itself is engaged with two toothed wheels 16 and 16 'carried respectively by two shafts 17 and 17' to which the two aforementioned output gears 11 and 11 'are respectively fixed, so that each pinion 11 or 11' is integral with each other. in rotation of the toothed wheel 17 or 17 'corresponding.

The thrust chain 10 essentially comprises two toothed belts 18 and 18 'which are respectively engaged with the output gears 11 and 11' of the speed-reducing mechanism 9 and which are provided, on their face opposite to the notched face, with studs. 19 and 19 'regularly spaced and adapted to engage with each other in the manner of the teeth of a zipper. Upstream of the two output gears 11 and 11 ', i.e. above these two gears in the Figures 3 and 4 the two belts 18 and 18 are flexible and independent of one another, whereas downstream of the two output gears 11 and 11 ', the two belts 18 and 18' and their studs 19 and 19 'are united so as to define a chain extending in a straight line and behaving as a rigid bar capable of transmitting thrust forces such as tensile forces. Thrust chains such as the chain 10 are well known and are described in particular in the document FR-A-2,826,422 to which we can advantageously refer for more details.

In the application of the push chain 10 to the rod according to the invention, the lower end of the two toothed belts 18 and 18 'is connected to a connecting member 21 which is fixed rigidly to the upper end of the segment of tube 1b of the telescopic tube 1. For example, the connecting member 21 may be constituted by a plastic block, of cylindrical general shape, which is formed by overmolding on the lower end of the two toothed belts 18 and 18 ', so that the lower end of the two belts 18 and 18' is embedded and, therefore, anchored in the block 21. In addition, the block 21 may comprise a circular groove in its peripheral surface to allow its attachment to the upper end of the tube segment 1b, for example by crimping, as shown in 22 in the Figures 3 and 4 .

The thrust chain 10 is dimensioned such that, in the assembled state of the two toothed belts 18 and 18 'and their studs 19 and 19', the chain 10 can slide inside the tube segment 1a of the tube telescopic 1. Preferably, in order to ensure good guidance of the chain 10 in the tube segment la, each of the two lateral faces 23 and 24 of each of the studs 19 and 19 'of the toothed belts 18 and 18' has a profile curve that follows the contour of the inner cylindrical surface of the tube segment la as shown in FIG. figure 7 .

The electric motor, the speed reduction mechanism 9, at least part of the thrust chain 10 and a rechargeable accumulator battery 25 for the electric power supply of the electric motor 8 are housed in a housing 26 which is fixed at the upper end of the tube segment 1a of the telescopic tube 1. The housing 26 may advantageously be shaped as an ergonomic handle 2. For example, the housing 26 may consist of two half-shells 26a and 26b made of a plastics material molded, for example polyethylene, which have a joint plane 27 corresponding to the vertical median plane of symmetry 28 ( figure 4 ) of the ergonomic handle 2. Thus, after assembly and fixing of the two half-shells 26a and 26b to one another by several screws 29, the two half-shells 26a and 26b together form the ergonomic handle 2 with its part 2a serving palmar support and its part 2b serving as antebrachial support.

As is clearly visible in the Figures 3 and 4 , the housing 26 has, in the connection zone between the parts 2a and 2b of the ergonomic handle 2, a hollow bulge portion 31 inside which are disposed the electric motor 8, the speed reduction mechanism 9 and the battery The manner in which the electric motor 8, the worm 15, the shafts 17 and 17 'and the storage battery are supported in the housing 26 has not been shown in FIGS. Figures 3 and 4 for the sake of simplicity and clarity in these figures, but it is obvious that these elements can be supported or held in the housing 26 by partitions or by support members which are molded integrally with one or other of the two half-shells 26a and 26b.

It will also be noted that the two half-shells 26a and 26b each comprise a rib 32 ( figure 3 ) inside their portion forming the part 2b of the ergonomic handle 2. After assembly of the two half-shells 26a and 26b, the two ribs 32 together form a partition wall insulating the independent flexible parts from each other the two toothed belts 18 and 18 'of the push chain 10, upstream of the two output gears 11 and 11'. This avoids any interference between said flexible independent parts of the toothed belts 18 and 18 'which could cause a blockage or damage to the linear actuator 7. At their lower part, the two ribs 32 comprise a bulge portion 32a intended to facilitate the separation of the pads 19 and 19 'of the two toothed belts 18 and 18' when the drive chain 10 is moved vertically from low to high by the output gears 11 and 11 '.

A stop member at the end of the stroke, not shown in the figures, ensures the maintenance of a minimum portion of the two toothed belts 18, 18 'upstream of the two output gears 11, 11' so as to exclude any disassembly inadvertent thrust chain 10.

Below the bulged portion 31 of the housing 26, the two half-shells 26a and 26b form, after assembly, a cylindrical portion 33 which closely surrounds the upper end portion of the tube segment 1a of the telescopic tube. Although not shown in the drawings, other fastening screws such as screws 29, or a clamp may be necessary to securely tighten the two half-shells 26a and 26b in their cylindrical portion 33 against the upper end portion of the tube segment la. In addition, the upper end of the tube segment is preferably shaped to have a lip or collar 34 engageable with relief elements 35 formed on the inner wall of the cylindrical portion 33 of the housing 26. to prevent axial relative displacement in one direction or the other between the tube segment 1a and the housing 26.

Control means 36 carried by the ergonomic handle 2 are provided to control the on / off and the direction of operation of the linear actuator 7. More specifically, the control means 36 may comprise an inverting switch 37 ( figures 3 , 5 and 8 ) at two unstable closing positions and a stable intermediate position of cut. Preferably, the inverting switch 37 is housed inside the portion 2a of the ergonomic handle 2, and it comprises an operating member 38 which projects radially on said portion 2a, in the region of the free end of that so that it can be operated by an inch of the hand of a user of the cane holding said portion 2a of the ergonomic handle 2 in his hand, and this without the user being forced to relax his grip on said part 2a.

For example, for a rod intended to be held by the right hand of the user, the operating member 38 projects radially on the cylindrical surface of the portion 2a of the ergonomic handle 2, in a direction which is directed obliquely towards down and towards the right side of the user. For example, this direction may be at an angle of about 45 degrees from the vertical when the inverting switch 37 is in its stable intermediate position of cutoff.

The operating member 38 is guided and can slide in a slot or notch 39 ( figure 5 ) which extends in the circumferential direction in the cylindrical wall of the portion 2a of the ergonomic handle 2. When the operating member 38 is moved downwards, in the direction of the arrow F1, the inverter switch 37 switches in one of its two unstable closing positions and controls the start of the electric motor 8 in a first direction corresponding to a displacement of the push chain 10 for example downward, that is to say in one direction corresponding to the elongation of the telescopic tube 1. Conversely, when the actuating member 38 is moved upwards in the direction of the arrow F2, it switches the inverter switch 37 into its other unstable position of closure and controls the starting the electric motor 8 in the opposite direction of rotation, corresponding to a movement of the push chain 10 upwards, that is to say in a direction corresponding to a shortening of the telescopic tube 1 of the cann e.

For this purpose, in the case where the electric motor 8 is a DC motor, the inverting switch 37 may comprise two movable contacts 41 and 42 which are connected to the positive and negative poles of the accumulator battery 25 respectively by conductors. 43 and 44 as shown in the figure 8 . The inverter switch 37 further comprises a first pair of fixed contacts 45 and 46 which are connected to the two terminals of the motor 8 respectively by conductors 47 and 48, so that when the movable contacts 41 and 42 are in contact with the fixed contacts 45 and 46, the current supplied by the accumulator battery 25 passes through the motor 8 in a first direction to rotate said motor in the first direction of rotation causing for example the extension of the telescopic tube 1 of the rod . Finally, the inverting switch 37 comprises a second pair of fixed contacts 49 and 51 which are connected to the terminals of the motor 8 respectively by conductors 52 and 53 so that when the movable contacts 41 and 42 come into contact with the fixed contacts 49 and 51, the current supplied by the accumulator battery 25 passes through the motor 8 in the opposite direction to rotate said motor in a second direction of rotation causing for example a shortening of the telescopic tube 1 of the rod.

As can be seen on the figure 8 the two poles of the storage battery 25 are also connected respectively by conductors 54 and 55 to the contacts 56 and 57 of a connector 58. As shown in FIG. figure 4 , the connector 58 is attached to the housing 26 and is accessible from outside of said housing to allow recharging of the storage battery 25 by means of a battery charger (not shown) with a completed power cord by a plug compatible with connector 58.

As is clear from the foregoing description, it is clear that by acting on the operating member 38 of the reversing switch 37 in the direction of the arrow F1 or in the direction of the arrow F2 the user of the cane can cause as the case may be, an elongation or shortening of said cane. Thus, in the case of an extension of the cane, it is clear that a user relying on the ergonomic handle 2 can get assistance in crossing an obstacle, for example to climb on a step, or to lift a seat.

Preferably, the actuator 7, in particular the motor 8 and the speed reduction mechanism 9 are dimensioned so as to be capable of providing a predetermined power sufficient to give a thrust corresponding to a substantial part of the weight of a person s'. pressing on the ergonomic handle 2.

• moteur électrique 8 : à courant continu 17W, 12V, apte à fournir un couple de 0,058 N.m à 2800 tr/min avec un courant de 2,5 A ;
• pignon 12 : sept dents, module 0,5 ;
• roue dentée 14 : quatorze dents, module 0,5 ;
• vis sans fin 15 : un filet ayant un angle d'inclinaison de 85 degrés et un angle de frottement de 5 degrés ;
• deux roues dentées 16 et 16' ayant chacune cinquante dents, module 0.5 ;
• deux pignons de sortie 11 et 11' ayant chacun un rayon de 7,5 mm et dix dents ;
• batterie d'accumulateurs 25 : accumulateurs 12V au lithium ;

le mécanisme réducteur de vitesse 9 a un rapport de réduction 1/100 et un rendement mécanique global d'environ 0,5. Dans ces conditions, quand le moteur électrique 8 tourne à 2 800 tours/ minute, la chaîne de poussée 10 se déplace à une vitesse de 22 mm/ s et fournit un effort de poussée de 350N. Autrement dit, la canne est capable de soulever un poids de 35 kilos à une vitesse de 22 mm/ s.For example, using components with the following characteristics:

• electric motor 8: direct current 17W, 12V, able to provide a torque of 0.058 Nm at 2800 rpm with a current of 2.5 A;
• pinion 12: seven teeth, module 0.5;
• toothed wheel 14: fourteen teeth, module 0.5;
• worm 15: a net having an inclination angle of 85 degrees and a friction angle of 5 degrees;
• two toothed wheels 16 and 16 'each having fifty teeth, module 0.5;
• two output gears 11 and 11 'each having a radius of 7.5 mm and ten teeth;
• accumulator battery 25: 12V lithium batteries;

the speed reduction mechanism 9 has a 1/100 reduction ratio and an overall mechanical efficiency of about 0.5. Under these conditions, when the electric motor 8 rotates at 2800 rpm, the thrust chain 10 moves at a speed of 22 mm / s and provides a thrust force of 350N. In other words, the cane is able to lift a weight of 35 kilos at a speed of 22 mm / s.

As an electric motor 8, it is possible to use, for example, an engine marketed under the reference RE025 CLL by the company MDP MOTOR ( http://www.mdpmotor.com ).

It should be noted that, with the components indicated above, the efficiency of the worm 15 is zero when the output gears 11 and 11 'and the gears 16 and 16' are driving. This is for example the case when the motor 8 is not powered and the user of the rod is supported on the ergonomic handle 2. In this case, the reaction exerted by the ground on the lower end of the tube telescopic 1 causes the thrust chain 10 is subjected to a force directed upwards, so that the toothed belts 18 and 18 'tend to drive the pinions 11 and 11' in rotation and consequently also the toothed wheels 16 and 16 '. However, as the worm 15 has under these conditions a zero yield, it can not rotate, so that it locks the gears 16 and 16 'and thus prevents vertical movement of the thrust chain 10, as well upward than downward. The linear actuator 7 is therefore irreversible in the sense that the electric motor 8, when it is supplied with current, and the speed reduction mechanism 9 are able to move the push chain 10 in both directions, upwards and downwards. downwards, but, conversely, the thrust chain 10 is incapable of transmitting any movement to the speed-reducing mechanism 9 and to the electric motor 8.

The length of the thrust chain 10 is preferably chosen so that the linear actuator 7 has a total stroke of about 30 to 35 cm.

It goes without saying that the embodiment of the invention which has been described above has been given by way of purely indicative and non-limiting example, and that many modifications can be easily made by the man of the Art without departing from the scope of the invention.

It is in particular possible to provide an electronic circuit for controlling the electric motor 8, for example to adjust the speed of rotation. Such a control circuit can be easily carried by a printed circuit board installed in the part 2a of the ergonomic handle 2.

Claims (10)

1. Crutch for a person having a mobility impairment, comprising a telescopic tube (1) which is composed of at least two tube segments which can slide one in the other, that is to say, an upper tube segment (1a) and a lower tube segment (1b) and which is provided at the upper end thereof with an ergonomic handle (2) which comprises a substantially cylindrical portion (2a) which extends transversely relative to the longitudinal axis of the telescopic tube (1) and which acts as a palm support, and a portion (2b) which extends upwards from the portion (2a) in an oblique manner relative to the longitudinal axis of the telescopic tube (1) and which acts as an antebrachial support,
   characterised in that

   - the crutch is provided at the inner portion thereof with a linear actuator (7) which is capable of transmitting traction and thrust forces and which comprises, on the one hand, two identical notched belts (18, 18') which are each provided on their face opposite the notched face with studs (19, 19') which are spaced-apart in a uniform manner and, on the other hand, driving members (11, 11') which are located at one side and the other of the two notched belts (18, 18') and which co-operate with actuation means in order to allow the studs (19, 19') of these belts (18, 18') to move into mutual engagement, so that they are flexible and independent of each other in the region of a first portion which is located at one side or the upstream side of the driving members (11, 11') whilst, in the region of a second portion located at the opposite side or downstream side of these members (11, 11'), they are assembled in a fixedly joined manner and extend in a straight line, acting as a rigid bar in one piece which is capable of transmitting thrust forces as traction forces and

   - the driving members (11, 11') and the actuation means are accommodated in a casing (26) which is fixed to the upper end of the upper tube segment (1a) and which is shaped so as to act as an ergonomic handle (2) so that the first portion of the two notched belts (18, 18') extends in the portion (2b) which forms an antebrachial support for the ergonomic handle (2) whilst the second portion of these belts extends in the upper tube segment (1a) and is fixed to the inner portion of the lower tube segment (1b) with the downstream end thereof, the actuation of the driving members (11, 11') bringing about the sliding action of the second portion of the notched belts (18, 18') at the inner portion of the telescopic tube (1) and the modification of the length of this tube.
2. Crutch according to claim 1,
   characterised in that
   the actuation means comprise an electric motor (8) which has two rotation directions and which is supplied with electrical current by a battery of rechargeable accumulators (25) and a geared speed reduction mechanism (9) which is coupled to the motor (8) and which comprises two output pinions (11, 11') which move into engagement with the two notched belts (18, 18'), respectively, and which constitute the driving members.
3. Crutch according to either claim 1 or claim 2,
   characterised in that
   the linear actuator (7) has a level of power which is selected to be sufficient to provide a thrust which corresponds to a substantial portion of the weight of a person pressing on the ergonomic handle (2).
4. Crutch according to either claim 2 or claim 3,
   characterised in that
   the linear actuator (7) comprises control means (36) which are carried by the ergonomic handle (2) in order to control the starting/stopping action and the rotation direction of the electric motor (8).
5. Crutch according to claim 4,
   characterised in that
   the control means (36) comprise a reversing switch (37) having two unstable closing positions and a stable intermediate disconnection position.
6. Crutch according to claim 5,
   characterised in that
   the reversing switch (37) comprises a manoeuvring element (38) which protrudes radially over the substantially cylindrical portion (2a) which acts as a palm support, in the region of the free end of this substantially cylindrical portion so as to be able to be actuated by a thumb of the hand of a user of the crutch holding this substantially cylindrical portion.
7. Crutch according to any one of claims 2 to 6,
   characterised in that
   the battery of accumulators (25) is electrically connected to an electrical connector (58) which is accessible from the outer side of the casing (26) in order to allow this battery of accumulators to be recharged using a battery charger.
8. Crutch according to any one of claims 1 to 7,
   characterised in that
   the casing (26) is constituted by two half-shells (26a, 26b) which are in particular produced from a moulded plastics material, for example, polyethylene and which have a joint plane (27) which corresponds to the vertical centre plane of symmetry (28) of the ergonomic handle (2) and which are assembled using screws (29).
9. Crutch according to claim 8,
   characterised in that
   the two half-shells (26a, 26b) each comprise a rib (32) at the inner portion of the portion thereof corresponding to the portion (2b) which forms an antebrachial support for the ergonomic handle (2), after assembling the two half-shells (26a, 26b), these two ribs (32) together defining a separating partition which isolates the first flexible portions which are independent of the two notched belts (18, 18').
10. Crutch according to any one of claims 1 to 9,
    characterised in that
    the casing (26) has, in the connection zone between the portion (2a) which forms a palm support and the portion (2b) which forms an antebrachial support of the ergonomic handle (2), a hollow enlarged portion (31) inside which the electric motor (8), the speed reduction mechanism (9) and the battery of accumulators (25) are arranged.

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