WO2008090508A1

WO2008090508A1 - Equipment for enabling a motorized wheelchair to move safely even on steps or flights of stairs

Info

Publication number: WO2008090508A1
Application number: PCT/IB2008/050207
Authority: WO
Inventors: Andrea Dogliotti
Original assignee: Andrea Dogliotti
Priority date: 2007-01-23
Filing date: 2008-01-21
Publication date: 2008-07-31
Also published as: ITGE20070007A1

Abstract

The wheelchair is provided with motorized rear wheels (A) and with swivelling or steering front wheels (B), and comprises: Telescopic legs (202) located in the rear part of the wheelchair and provided at their lower ends with ground bearing means (C), these bearing means being positioned at a centre-to-centre distance (IA) from the rear wheels (A) of the wheelchair which is suitably greater than the radius of these wheels (A); Telescopic legs (5) located suitably with respect to the front wheels (B) of the wheelchair and provided at their lower ends with ground bearing means (D); Telescopic legs (3) which support the front wheels (B) of the wheelchair; Safety means and control means for ensuring that, during travel along the stairs, the bearing means of the said rear and intermediate legs (202, 5) are all extended and bear on the ground, together with the front and rear wheels of the wheelchair.

Description

TITLE:

"EQUIPMENT FOR ENABLING A MOTORIZED WHEELCHAIR TO MOVE SAFELY

EVEN ON STEPS OR FLIGHTS OF STAIRS"

DESCRIPTION

The invention relates to wheelchairs, particularly those wheelchairs that enable an invalid to climb and descend the stairs of a building and to pass over the steps of pavements and other architectural barriers in a fully independent way. In this technical field, the prior art can provide wheelchairs which, although they are very suitable, safe and fast for travel on stairs, are also bulky and less suitable for use in a domestic or work environment, so that an invalid at present requires a first vehicle for climbing and descending stairs and possibly also for outdoor use, this vehicle generally using tracks for travelling on stairs and wheels for fast movement on level ground, and a second vehicle specifically for use in the domestic and/or work environment, this vehicle normally making use of wheels only. Clearly, this solution is expensive and cannot always be used in cases in which the invalid is unable to move independently from one vehicle to the other.

The invention discloses improvements to be made to the general design of a conventional electrically powered wheelchair, or to another vehicle such as a pushchair or other (including automatic driverless vehicles such as those for surveillance or for space exploration), in order to make the vehicle suitable for travel both on level ground and on stairs, thus enabling the user to have a single vehicle to meet his different locomotion requirements, both inside and outside buildings, in the presence of flat or inclined surfaces, stairs, or other architectural barriers, in such a way that the overall dimensions of the wheelchair are not modified excessively, in order not to limit the manoeuvrability of the wheelchair in restricted environments and spaces.

The features of the improved wheelchair according to the invention, and the advantages derived therefrom, are described in the attached Claim 1 and in the subsequent dependent claims, and will become clear from the following description of some preferred embodiments of the improved wheelchair, which refers to the figures of the five attached sheets of drawings, in which:

Fig. 1 is a schematic view in side elevation of an improved wheelchair according to the invention, shown in solid lines in the position of travel on level ground and shown in broken and chained lines in some stages of a cycle of descending or climbing a staircase;

Fig. 2 is a plan view from above of the wheelchair of Figure 1 ;

Figs 3 and 3a are schematic front views of the rear subframe of the wheelchair, shown, respectively, in the raised position for the travel of the wheelchair on level ground and in the lowered position for the travel of the wheelchair on stairs;

Figs 4 and 4a are schematic side views of the rear subframe of the wheelchair in the conditions shown in Figures 3 and 3a;

Figs 5 and 5a are lateral views in partial section of one of the telescopic legs which carry the front wheels of the wheelchair, the leg being shown, respectively, in the retracted position for the travel of the wheelchair on level ground and in the extended position for the travel of the wheelchair along stairs;

Figs 6 and 6a are side views in partial section of a variant construction of the telescopic legs of Figures 5 and 5a;

Figs 7 and 7a are side views in partial section of one of the telescopic legs with intermediate castors for enabling the wheelchair to travel along stairs, the said leg being shown, respectively, in the retracted idle position and in an extended operating position;

Figs 8, 9, 10, 11 , 12, 13, 14, 15, 16, 17, 18 and 19 are schematic side views of the wheelchair in corresponding successive stages of a cycle of descending a staircase.

In Figures 1 and 2, the number 1 indicates a typical electric wheelchair, which is considered to be the "basic wheelchair" in this case, and which comprises a seat 101 , armrests 201 , a back 301 , and usually motorized rear wheels A with rubber- tyres, and front wheels B which also have rubber-tyres, which have a smaller diameter than that of the said wheels A and which are of the swivelling type, with or without controlled steering. According to the invention, the wheelchair 1 is provided with the following means:

• a rear subframe 2 which is horizontally movable and is provided with a pair of telescopic legs 202 which carry corresponding motorized castors C at their lower ends, these castors bearing on the ground jointly with, or alternately with, the motorized rear wheels A;

• a pair of telescopic front legs 3 which carry the swivelling front wheels B, which were previously positioned at a fixed height;

• a system 4 for locking the swivelling of the front wheels B;

• a pair of intermediate telescopic legs 5, provided at their lower ends with castors D which bear on the ground in combination with, or alternately with, the front wheels B;

• a system of sensors and automation means.

The rear subframe 2, which can be removable in order to limit the overall dimensions of the wheelchair during stowage or carriage in a motor vehicle, can be: a) fixed, for supporting only the two extendable legs which carry the castors C; b) movable vertically, where required, for passing over single steps of considerable height; c) movable horizontally for operation on small stairs with narrow treads or for the safe use of the wheelchair when travelling along stairs even if it has large- diameter motorized rear wheels A; d) movable both horizontally and vertically.

The following description relates to points b), c) and d) above and makes reference to Figures 1 , 2, 3, 3a, 4, 4a, 5 and 5a. The subframe 2 is, for example, of rectangular shape, and its horizontal sides 102 are, for example, flat, while its vertical sides 202 are tubular and slidably house the corresponding bars 8 which carry at their lower ends the axle of the castors C, parallel to the axle of the motorized wheels A. A vertical internally threaded tube 9 is rotatably mounted in the centre of the vertical subframe 2, this tube interacting with a screw 11 whose lower end is fixed to a cross-piece 10 fixed to the lower part of the said bars 8.

A reversible electric motor 12 is mounted on the lower cross-piece of the subframe 2, and is connected by means of a reduction transmission 13 to the female thread 9 in order to provide the necessary movement for raising and lowering the castors C.

The bars 8 are connected, by means of interposed forks 14, to the castors C, whose axle 15 is driven by an electric motor 16 which may have an external brake 17, the stator of these components 16 and 17 being fixed, for example, to the adjacent cross-piece 10.

Four tubes 18 are fixed to the rear of a frame behind the back 301 of the wheelchair, in a projecting horizontal configuration, and corresponding tubes 19 fixed to the corner areas of the subframe 2 slide on these four tubes. At least one or more of the said tubes can be threaded and some of them are rotatable and can be rotated in the desired direction by a motor 20 and by a corresponding transmission 21 , in order to provide the desired horizontal movement of the subframe 2 towards or away from the wheelchair, for the purposes described below.

In Figure 1 , the rear castors C are shown in broken lines in the low position K1 in which they are coplanar with the rear wheels A of the wheelchair and in the two positions of their minimum and maximum horizontal spacing from these wheels A, resulting from the operation of the motor 20 and of other means described below. When the subframe 2 is in the position of maximum spacing from the back 301 of the wheelchair, the centre-to-centre distance IA between the castors C and the driving wheels A is suitably greater than the radius of the latter wheels.

Also in Figure 1, the rear castors C are shown in solid lines in the raised position, to which they are moved by the motor 12. In order to pass over steps which are higher than normal steps of a staircase, arrangements can be made to raise the rear castors C beyond the normal raised position K (for example, to the position K2 shown in chained lines), by an additional travel MVT. This object can be achieved by suitably designing the path of the legs 202 for raising and lowering the said castors C, or can be achieved with means which are not shown, for example electrically or hydraulically operated means, which on command move a supplementary frame 22 carrying the aforesaid tubes 18 vertically along the back 301 of the wheelchair, the whole arrangement being provided in a way which is evident to persons skilled in the art and which is easily implemented by them.

All the motors can be of the stepping type, if this is convenient for the safe control of the operation of the wheelchair. The brake is not considered necessary for the two drives of the male and female thread mechanisms described above, since these are of the non-reversing type.

The motorized drive of the rear driving wheels A can theoretically remain unchanged, with the corresponding motors, brake and batteries located in the space indicated schematically by 7. If the ordinary drive motors cannot provide fine control of the forward movement to the edge of the step, then either they are replaced or an additional stepping motor is installed for use solely for the movements on stairs. If the stepping motor cannot be fixed on the wheel axle, it is fixed to the frame of the wheelchair and transmits the movement to the wheels A by means of a belt or chain.

Figure 1 also shows that the front wheels B of the basic wheelchair are, as mentioned, of the swivelling or steering type, to allow better mobility of the vehicle in restricted spaces. When the wheelchair has to climb or descend stairs, the front wheels B must be locked in a predetermined position, and therefore, if they are of the swivelling type, they are preferably locked in the forward travel position, by means of a locking device 4 which comprises, for example, a locking pin 104 which is operated, for example, by an electromagnet 204, mounted with the said locking pin, for example at the base of the legs 3. When the wheels B are to be locked, the locking pin 104 is lowered to interact with a housing 23 provided on a support fork of the wheels B, as shown in Figures 1 , 5 and 5a. Before commencing the ascent or descent of a staircase, which are carried out with the wheelchair in reverse or forward gear respectively, the wheelchair is moved forward slightly, in order to place the wheels B in the correct locked position, and the locking pins 104 are lowered by means of the corresponding electromagnets.

Figure 1 also shows that the telescopic legs 3 which carry the front wheels B must be able to transfer these wheels from the idle position indicated in solid lines to the position indicated in broken lines, and vice versa, by means of movements usually equal to the height of the step S between the wheels A and B. In order to limit the overall height of the legs 3 when they are in the retracted and raised idle position, and in order to prevent the legs from projecting above the height of the armrests 201 of the chair, the said legs 3 can be formed, for example, from cylinder and piston units of the type with a plurality of telescopic stems, as shown in detail in Figures 5 and 5a. Since these cylinders are unable to withstand high bending forces, it is possible to design a solution which reduces the resultants of these forces to a minimum. During the normal travel of the wheelchair, with the legs 3 retracted, the wheel attachments may, for example, transmit the bending forces to the outer body 103 of the cylinder only, for example by means of a cup 24 which interacts with this body 103 as shown in Figure 5.

If the locomotion equipment in question is to be combined with a vehicle other than a wheelchair, in which considerable bending forces will be encountered, even when the cylinders are in the extended position, the variant shown in Figures 6 and 6a can be adopted, in which case the bending force is primarily absorbed by a telescopic structure 25 of tubes, which externally enclose the hydraulic cylinder. In this case, the said cup 24 interacts with the outer body of the said structure 25 (Fig.

6).

The support forks of the wheels B are mounted rotatably on the lower ends of the said casings 25 and of the legs 3, together with the aforesaid locking means 4.

The hydraulic cylinders which are used can be of the double-acting type, or of the single-acting plunger type, with a return movement provided by gravity or by the action of resilient means shown schematically at 26 in Figures 6 and 6a.

The legs 5 with the intermediate castors D must be capable of bringing the said castors, on command, from the raised idle position shown in solid lines in Figure 1 to the position of maximum extension shown in broken lines in Figure 1 , and vice versa, and the said legs must have small overall dimensions when in the retracted idle position, without projecting beyond the armrests 301. For this purpose, the legs 5 are also made from multiple-extension hydraulic cylinders, as shown in detail in Figures 7 and 7a. In this case also, the cylinders 5 can be double-acting or single- acting, with the return movement provided by the action of gravity due to the load applied to them and with the discharge controlled by a modulated valve, or with the return movement provided by a resilient means shown schematically at 27 in Figures 7, 7a. In the second of the said cases, the legs 5 can be raised and lowered by other means which are not shown, which may be electrically or hydraulically operated and which can bring the castors D from the ground contact position to the raised idle position. These vertical movement means can be associated with the subframe described below, if present, which enables the legs 5 to be moved horizontally to vary the centre-to-centre distance IB between the castors D and the front wheels B.

Since the diameter of the front wheels B is smaller than that of the rear wheels A, the intermediate castors D can be positioned at a fixed centre-to-centre distance from the said front wheels B, in order to avoid interference with these wheels when the said castors are in the raised idle position. This centre-to-centre distance, indicated by IB in Figure 1 , is suitably greater than the radius of the front wheels B.

The hydraulic cylinders which form the legs 3 and 5 can be controlled by a hydraulic control unit located in the space indicated by 6 in Figures 1 and 2, and the motors and valves of this control unit, such as the motors 12 and 20 and all the automatic systems of the parts described will be supplied from the electrical accumulators which are located in the space indicated by 7 and which also supply the electric motors and the normal components of the wheelchair.

The equipment according to the invention is completed by means, which are not shown in the drawings, since they can be readily understood and easily provided by persons skilled in the art, for ensuring the safe and fully automatic operation of the wheelchair, as described below. The control system uses, for example, a computer unit which collects and processes the data received from a set of sensors and which operates the actuators.

The sensors comprise, for example: optoelectronic obstacle-detecting transducers, for example laser telemeters, mounted for example on the fixed part of the cylinder stems and/or on the frame of the wheelchair, above the wheels A, B, C and D; at least one biaxial inclinometer, mounted for example under the seat, on the electronic control unit; - limit switches for the various movements of the subframe 2 with the motorized rear castors C and for the upward and downward movements of the said castors C and of the intermediate castors D; a device for encoding or measuring the rotation of the axle of the castors C (and of the wheels A if necessary), if motors requiring this component are not used.

Figure 8 and the subsequent figures show schematically the cycle of descending a staircase S with four steps having a rise of approximately 20 cm and a tread of approximately 20 cm.

Each of the wheels or axles carries out a cycle of its own which intersects with those of the other wheels and which, essentially, interrupts them and is interrupted by them for the time required for the corresponding operations. It should be noted that, in the descent, any projection of the steps, which frequently project beyond the risers, has no effect on the cycle or on any sensors and controls for the automatic control system. The "stop" indications included in the description of the cycle are purely indicative of situations which require care. Stops can be avoided or reduced by using, for example, an advanced automation system.

Figure 8 shows how the wheelchair approaches the stairs with all the auxiliary castors C and D lowered and with the rear subframe 2 in the extended position, in other words with the maximum centre-to-centre distance IA between the rear wheels A and the corresponding castors C.

When the front wheels B have passed completely beyond the edge of the level ground, the vehicle stops, and, as shown in the following Figure 9, the legs 3 are extended and the wheels B bear on the lower step, after which the movement of the vehicle is resumed and, when the intermediate castors D have passed beyond the upper level, as shown in Figure 10, the vehicle stops and the legs 5 then extend so that the castors D bear on the lower step, as shown in Figure 11. At this point, the vehicle starts to move again as shown in Figure 12, and, when the front wheels B have passed beyond the step, the vehicle stops and the legs 3 extend to make the wheels B bear on the step below them, as shown in Figure 13. The cycle continues as described above, for all the other steps, until the wheelchair reaches the lower level, as described below.

When the rear castors C are about to reach the edge of the upper level of the staircase, as shown in Figure 14, the front wheels B and the intermediate castors D both bear on a step, in such a way that, when the rear wheels A have passed completely beyond the said upper level of the staircase S, the vehicle stops and these wheels A are made to bear on the step below, as shown in Figure 15, by a simultaneous retraction of all the legs 202, 3 and 5 of the equipment, while the wheelchair descends by one step. In the next stage, as shown in Figure 16, the legs 202 are raised slightly to detach the castors C from the ground, and the subframe 2 is moved horizontally to bring the said castors C above the step below, on which these castors are subsequently made to bear by the extension of the legs 202, as shown in Figure 17. In the next stage, as shown in Figure 18, while the horizontal movement of the wheelchair is resumed by means of the driving wheels A, the subframe 2 is returned to the position of maximum horizontal extension, thus enabling the whole of the cycle described to be repeated, for both the front and the rear wheels, until the wheelchair reaches the lowest level of the staircase as shown in Figure 19. In this final stage, the wheelchair bears on the ground with only the front wheels B and the rear wheels A, while the rear castors C and the intermediate castors D are raised to enable the wheelchair to proceed in the usual way.

The cycle for climbing a staircase is the reverse of that described for descending, and will be easily understood by persons skilled in the art; consequently it will not be described in detail here.

As regards the possibility of passing over particularly high steps, the said means for providing the castors C with an additional travel, indicated by MVT in Figure 1 , can also be used in the movement of raising and lowering the rear castors C. The cycle described with reference to Figures 8 to 19 suggests variant constructions which can easily be produced by persons skilled in the art, solely on the basis of the following considerations: a) the horizontal movement of the wheelchair during the climbing or descent of the stairs can be provided by the rotation of the rear castors C and/or by the horizontal movement of extension or retraction of the subframe 2, instead of by the driving wheels A; b) if the horizontal movement of the wheelchair according to the preceding sentence is provided by the horizontal movement of the extension or retraction of the subframe 2, then the auxiliary castors C can be replaced by feet; c) the legs 5 for the intermediate castors D can also be mounted on corresponding motorized subframes for horizontal movement, positioned on the sides of the wheelchair, and in this case the castors D can also be replaced by feet.

It should be understood that the description relates to some preferred embodiments of the invention, which can be varied and modified in numerous ways as regards construction, for example by making the front legs 3 carry their own ground bearing means which are different from the front wheels B, which in this case would continue to be associated with the wheelchair in the usual way. This variant, and all others which are evident to persons skilled in the art, fall within the guiding principle of the invention, as described above, as illustrated and as claimed below.

Claims

1. Equipment for enabling a wheelchair, or other means, to both climb and descend steps and flights of stairs in safety, the wheelchair being provided for example with motorized rear wheels (A) and with swivelling or steering front wheels (B), characterized in that it comprises at least the following means:

Telescopic legs (202) located in the rear part of the wheelchair and provided at their lower ends with ground bearing means (C) which can be raised and lowered by the legs on command, these bearing means being positioned at a centre- to-centre distance (IA) from the rear wheels (A) of the wheelchair which is suitably greater than the radius of these wheels (A);

Telescopic legs (5) located suitably with respect to the front wheels (B) of the wheelchair and provided at their lower ends with ground bearing means (D) which can be raised and lowered by the legs on command, these bearing means being positioned at a suitable centre-to-centre distance (IB) from the front wheels;

Telescopic legs (3) which support the front wheels (B) of the wheelchair in such a way that the front wheels (B) can be raised or lowered by these legs on command;

Safety means and control means for ensuring that, during travel along the stairs, the bearing means of the said rear and intermediate legs (202, 5) are all extended and bear on the ground, together with the front and rear wheels of the wheelchair, in such a way as to alternate with these wheels in bearing on the steps, while the horizontal movement for climbing or descending the stairs is imparted to the wheelchair by its rear driving wheels (A) and/or by the rear legs (202) or by the bearing means (C) associated with the lower ends of these legs.

2. Equipment according to Claim 1, in which the said centre-to-centre distance (IB) between the intermediate legs (5) and the front wheels (B) of the wheelchair is suitably greater than the radius of the front wheels (B), and means (4) are provided to lock these wheels (B) in a predetermined position, preferably corresponding to the position for the forward travel of the wheelchair.

3. Equipment according to Claim 1 , in which the said ground bearing means associated with the rear telescopic legs (202) are supplementary wheels (C) with an axle parallel to that of the rear driving wheels (A) of the wheelchair and means (16, 17) are provided for forward or reverse drive and for braking these supplementary wheels (C).

4. Equipment according to any one or both of the preceding claims, in which the rear telescopic legs (202) are provided with a movable lower part (8, 10) which slides on a vertical subframe (2), this subframe being located above it, mounted on a support structure behind the back (301) of the wheelchair, and provided with male and female thread means (9, 11) or means of an equivalent type and with a drive unit (12, 13) having two directions of rotation, which can, on command, bring the said movable part (8, 10) with the ground bearing means (C) into the raised idle position or into the lowered operating position.

5. Equipment according to Claim 4, in which the said subframe (2) is mounted on the corresponding support frame behind the back of the wheelchair, with the interposition of slide and guide means (18, 19) and of male and female thread means or equivalent means and of a drive unit (20, 21) for horizontal movement, the whole being designed in such a way as to vary the centre-to-centre distance (IA) between the lower bearing means (C) associated with the telescopic legs (202) of the subframe (2) and the rear driving wheels (A) of the wheelchair, in order to enable the wheelchair to travel safely even on irregular steps and/or small treads and/or in order to make use of the horizontal movement in question to provide the necessary horizontal travel of the wheelchair.

6. Equipment according to any one or more of the preceding claims, in which the said subframe (2) is mounted on the corresponding support structure, with the interposition of a vertical slide (22) and with drive means for providing the underlying bearing means (C) with a vertical additional travel (MVT) for the purpose of enabling the wheelchair to move even over steps whose rise is higher than that of the ordinary steps of a staircase.

7. Equipment according to any one or more of the preceding claims, in which the intermediate legs (5) can also be mounted on subframes with means for movement at least in the horizontal direction, for varying the centre-to-centre distance (IB) from the front wheels (B) in order to enable the wheelchair to move safely over the steps of irregular stairs and/or those having narrow treads, and/or in order to move the wheelchair along the stairs, even without the use of the rear driving wheels (A) or in the case of vehicles not having these driving wheels, in which case the lower bearing means (C, D) of the rear legs (202) and of the intermediate legs (5) are formed by wheels of which at least the rear ones (C) are motorized or are formed by feet if the horizontal movement of the wheelchair is provided by the horizontal movement of the said subframes.

8. Equipment according to Claim 1 , in which the intermediate telescopic legs (5) and front telescopic legs (3) are made from multiple-extension hydraulic cylinders of the double-acting type, or of the single-acting type, in which case the return movement is provided by gravity and/or by the action of resilient means (26, 27).

9. Equipment according to Claim 1 , in which the intermediate telescopic legs (5) and the front telescopic legs (3) are made from tubular elements having any desired cross section, moved by chains or moved by drive systems constructed using shape memory alloys.

10. Equipment according to Claim 8, characterized in that the hydraulic cylinders of the legs subject to considerable bending forces, for example those of the front legs (3), can be reinforced with an outer telescopic casing (25) which resists the said bending forces.

11. Equipment according to Claim 1, characterized in that, in a variant construction, the front legs (3) carry at their lower ends bearing means which are different from and independent of the front wheels (B) of the wheelchair, which can thus continue to be associated in the normal way with the wheelchair.