Patent Description:
Two main types of wheelchairs are known, those with manual push and those self-propelled, the self-propelled ones generally rest on the ground by means of two small motorized wheels and two idle wheels, generally between <NUM> and <NUM> in diameter, whereas in the case of wheelchairs with manual push there are either four small idle wheels, always with a diameter generally comprised between <NUM> and <NUM>, or two large wheels, with a diameter greater than <NUM>, and two smaller wheels.

These wheels, which are substantially shaped like the bicycle wheels, have the problem of making it difficult to steer the wheelchair on uneven terrains. Furthermore, steering is particularly difficult on soft terrains, such as for example sandy terrains, which also have many irregularities in the form of small dunes.

The object of the present invention is that of overcoming this limit of the known art within a practical, efficient and low cost solution.

Such object is achieved by the features of the invention indicated in the independent claim. The dependent claims outline preferred and/or particularly advantageous aspects of the invention.

The invention, particularly, makes available a wheelchair comprising:.

wherein the roller develops longitudinally along a longitudinal axis and is provided with a pair of opposite longitudinal ends, which are chamfered.

In this way, the wheelchair allows steering operations without uncertainties even on uneven and/or soft terrains since the roller thus shaped allows it to crawl on the terrain during steering even on the roughness of the terrain allowing to overcome them. This feature is particularly important because, for example, it allows to overcome the small sand dunes on the beaches.

According to another aspect of the invention, the longitudinal ends can be truncated conical in shape.

In this way the roller is quick to manufacture.

For example, a portion of the lateral surface of the roller at each longitudinal end can be inclined between <NUM>° and <NUM>° with respect to a longitudinal axis of the roller.

According to yet another aspect of the invention, the roller can be rotatably associated idle with the frame.

In this way, the force required to the forward movement is reduced because the roller can roll on the surfaces.

According to a further aspect of the invention, the roller can have a maximum diameter, measured along a transverse direction with respect to a longitudinal axis of the roller, of less than half of the diameter of the wheels of the pair of wheels.

In this way the roller does not hinder the access to the seat of the wheelchair by the user. According to an aspect of the invention, the wheelchair can be of the self-propelled type and comprise a drive arrangement configured to set the pair of wheels in rotation with respect to the frame and provided with at least one electric motor adapted to supply the motion to the pair of wheels.

When the wheelchair is self-propelled, an aspect of the invention provides that the electric motor can be placed entirely at a vertical height greater than a vertical height of a wheel hub.

Thanks to this solution, a self-propelled wheelchair is made available which allows the person sitting in the chair to cross streams and bodies of water much deeper than those that can be crossed with known wheelchairs. Furthermore, in this way the wheelchair user can immerse his legs completely or almost completely in the water even in total autonomy, thus allowing people with motor handicaps in the lower limbs greater freedom of movement and action.

According to another aspect of the invention, in order to further improve the manoeuvring freedom of the wheelchair, the electric motor of which can be placed entirely at a vertical height from the ground greater than the maximum vertical height from the ground of the pair of wheels.

In a first embodiment of the drive arrangement, the motion generated by the electric motor is supplied to the wheels by means of a pair of rollers, each pressed in contact with a respective wheel.

In this way the transmission of the motion is particularly simple, light and resistant to salt and sand.

In a second embodiment of the drive arrangement, the drive arrangement can comprise a first pulley fixed to the output shaft of the motor, a second pulley integral in rotation to a wheel of the pair of wheels, and a flexible connecting member adapted to transmit a rotary motion between the first pulley and the second pulley.

In this way the transmission of the motion can take place without uncertainty thanks to the strong connection guaranteed pulleys and flexible connecting member. Furthermore, this solution allows to position the motor at a vertical height greater than in the first embodiment of the drive arrangement, since in said first embodiment the distance of the motor from the wheel affects the diameter of the roller which is pressed on the wheel to set it in rotation, therefore this diameter could become excessively bulky beyond a certain vertical height of the motor. Whereas in the case of the second embodiment of the drive arrangement, the distance has no influence on the size of the first pulley or of the second pulley, thus guaranteeing, always with the same distance, greater compactness and usability of the wheelchair.

Therefore, in this second embodiment, the electric motor can be placed entirely at a vertical height greater than the maximum vertical height of the wheels. For example, it can be placed <NUM> or <NUM> above the maximum vertical height of the wheels.

Further features and advantages of the invention will be more apparent after reading the following description provided by way of non-limiting example, with the aid of the figures illustrated in the accompanying drawings.

With particular reference to these figures, 1a, 1b, 1c, 1d, 1e, 1f generally indicate a wheelchair, in particular of the self-propelled type, i.e. capable of moving independently without the aid of motor power imparted by user of the chair or a companion.

Although a self-propelled chair is illustrated, the invention, i.e. the presence of a roller <NUM> as will be described below, does not necessarily need to be implemented in a self-propelled wheelchair, as it could also be implemented in a wheelchair of the manual push type.

The wheelchair is preferably of the self-propelled type, since this type guarantees greater manoeuvring freedom to the user.

Furthermore, a wheelchair able to accommodate a person is illustrated, but the wheelchair can be sized and equipped (with suitable seats) to carry even more than one person at the same time.

The wheelchair <NUM> comprises a frame <NUM>, for example tubular, although any other type of frame suitable for the purpose is equivalent.

A seat (not illustrated in the drawings) can be fixed to the frame <NUM> which has the purpose of supporting the wheelchair user at the bottom, for example this seat can comprise a substantially horizontal cushion which is fixed to the frame <NUM>.

The wheelchair can also comprise a backrest (not illustrated) placed at least partially at a higher level than the seat and shaped so that the wheelchair user can rest his back against it.

The wheelchair <NUM> comprises at least one pair of wheels <NUM> for resting on the ground (i.e. which contact the ground while keeping the frame raised therefrom), each of which is provided with a hub <NUM> by means of which the respective wheel <NUM> is rotatably associated with the frame <NUM> with respect to an axis of rotation R.

In particular, the wheels <NUM> of the pair of wheels <NUM> are rotatably associated with the frame <NUM> on opposite sides of the frame thereof. For example, they are rotatably associated with the frame on opposite sides of the frame thereof with respect to a centre plane of the wheelchair which extends from a front area to a rear area of the chair itself.

Furthermore, the axes of rotation R of the wheels <NUM> are coaxial, i.e. the pair of wheels is rotatably associated with the frame <NUM> with respect to a single axis of rotation R.

The axis of rotation R preferably lies on a horizontal plane.

However, it is not excluded that the axes of rotation of the wheels <NUM> may be incident and inclined to each other, as is the case for example in wheelchairs for sports use.

Each wheel <NUM> comprises a tyre or tire provided with a tread <NUM> and which is mounted on a rim integral in rotation with the hub <NUM>, for example by means of spokes, although it cannot be excluded that the rim may be made as a solid discoidal body comprising the hub.

At least the portion of tyre or tire in which the tread is present is made of a material with a high coefficient of friction, for example of rubber.

Each wheel <NUM> has a diameter, measured in a direction perpendicular to the axis of rotation R, at least greater than <NUM>, preferably comprised between <NUM> and <NUM>. The use of large diameter wheels helps in overcoming uneven terrains.

The wheelchair <NUM> can comprise a drive arrangement, which makes it self-propelled, configured to set said pair of wheels <NUM> in rotation with respect to the frame <NUM> in order to selectively move the wheelchair itself forward or backward.

The drive arrangement comprises at least one electric motor <NUM> fixed to the frame and which supplies the rotary motion, i.e. the driving torque, necessary to set the wheels in rotation in order to selectively move the wheelchair forward or backward. In particular, the electric motor <NUM> comprises an output shaft by means of which the rotary motion generated by the electric motor thereof is transmitted, i.e. from which output shaft it is possible to withdraw the rotary motion.

The motor comprises a protective casing or housing in which a plurality of windings (or solenoids) are housed and from which the output shaft which is connected to the wheels <NUM> to transmit the rotary motion comes out.

Preferably, the electric motor <NUM> is an electric gearmotor, i.e. inside the casing there is also a gear unit, generally with gears, which is placed upstream of the output shaft with respect to the direction of transmission of the rotary motion.

The electric motor <NUM> can be supplied by an electric supply battery fixed to the frame <NUM>.

The figures show six embodiments of the wheelchair, of which those illustrated in <FIG> are provided with a first embodiment of the drive arrangement and those illustrated in <FIG> are provided with a second embodiment of the drive arrangement.

In all the embodiments illustrated, the electric motor <NUM>, i.e. the electric gearmotor, is placed entirely at a vertical height from the ground on which the wheels <NUM> rest greater than the vertical height from the ground of the wheel hub, i.e. greater than the vertical height of both hubs of the two wheels <NUM> (in the embodiment illustrated, since there is a single axis of rotation R, the hubs are at the same vertical height). These heights are to be understood when the wheelchair is located on a horizontal plane.

In greater detail, the electric motor <NUM> is located entirely at a vertical height from the ground greater than the height of the intersection point between the axis of rotation R and a vertical plane that intersects the ground at a contact area of the wheel with the ground. For example, the electric motor <NUM> is placed entirely at a vertical height from the ground greater than <NUM>/<NUM> of the diameter of the wheel <NUM>.

More preferably, as is the case in the second embodiment of the drive arrangement, the electric motor <NUM> is placed entirely at a vertical height from the ground greater than the diameter of the wheel <NUM>. In detail, the electric motor <NUM> is placed at least <NUM> above the maximum height of the wheel <NUM>. Overall, the motor can therefore be positioned at a vertical distance of about one meter from the ground on which the wheels <NUM> rest.

In the various embodiments, the output shaft of the electric motor <NUM> rotates with respect to an eccentric axis of rotation, and for example parallel to the axis of rotation R.

In all the embodiments illustrated there are two electric motors <NUM> mechanically independent of each other, each configured to set in rotation, i.e. to transmit the driving torque to, a respective wheel <NUM> of the pair of wheels <NUM>.

In this way, it is particularly simple to impart a steering command to the wheelchair.

However, it is not excluded that in embodiments not illustrated, there may be a single motor connected to the wheels, a mechanism capable of transmitting the rotary motion to the wheels, i.e., the driving torque, and provided with at least one pair of brakes or clutches that can be selectively driven to reduce the rotary motion, i.e. the driving torque, to one of the two wheels <NUM> to make the wheel <NUM> that is closer to the centre of the turning radius rotate at a lower speed than the outer wheel and provided with at least one electric motor adapted to supply the motion to the pair of wheels. This mechanism is not further described as it is known to those skilled in the art.

The motors are both positioned above the vertical heights described above.

In the embodiment of the drive arrangement illustrated in <FIG>, the drive arrangement of the wheelchair 1a,1b,1c comprises a pair of rollers <NUM> which receive the motion from the electric motor <NUM>, and in which each of said rollers is pressed in contact with a respective wheel <NUM>, possibly with the aid of an elastic element.

In particular, each roller is pressed in contact with the tread <NUM> of the respective wheel <NUM>.

At least in the portion that contacts the wheel, the roller has a layer of material with a high coefficient of friction, for example of rubber.

In the preferred embodiment, these rollers <NUM> receive the rotary motion, i.e. the driving torque, from a respective electric motor, or electric gearmotor, <NUM>. For example, each roller can be keyed to the output shaft of the respective electric motor, or electric gearmotor <NUM>.

In this embodiment of the drive arrangement, the electric motor <NUM> is placed in a position in which it is located at least partially at a vertical height from the ground comprised between three quarters of the wheel diameter and the entire wheel diameter. However, it is not excluded that the electric motor could be located entirely at a height greater than the maximum height of the wheel.

In the embodiment of the drive arrangement illustrated in <FIG>, the electric motor of the wheelchair 1d, 1e, 1f is placed entirely at a vertical height greater than the maximum vertical height of the wheels, for example at least <NUM> or <NUM> above said maximum height, and the drive arrangement comprises a first pulley <NUM> connected, for example keyed, to the output shaft of the electric motor <NUM>, a second pulley <NUM> integral in rotation with a wheel <NUM> of the pair of wheels with respect to the axis of rotation R, and a flexible connecting member <NUM> at least partially wound on said pulleys to transmit the motion from the first pulley <NUM> to the second pulley <NUM>.

In particular, the drive arrangement comprises a pair of first pulleys <NUM> connected to a respective electric motor <NUM>, i.e. to the output shaft thereof, a pair of respective second pulleys <NUM>, each integral in rotation with respect to the axis of rotation R to a respective wheel <NUM>, and a pair of flexible connecting members <NUM> which connect a first pulley to the respective second pulley.

Preferably, for a slip-free transmission of motion, the flexible connecting member <NUM> is a chain and the pulleys <NUM>,<NUM> are provided with an external toothing, i.e. they are shaped like toothed wheels with external toothing, which mesh with the links of chain.

It is not excluded that even in this second embodiment, although it has not been illustrated, the motor, i.e. the motors, could also be located only at a vertical height from the ground greater than the vertical height of the hub.

Regardless of whether or not the drive arrangement is present, the wheelchair 1a,1b,1c,1d,1e,1f comprises, in addition to the pair of wheels <NUM>, also another element for resting on the ground, which comprises, i.e. is constituted by, a roller <NUM> resting on the ground.

The roller <NUM> is associated with the frame, for example rotatably associated idle with the frame with respect to an axis of rotation K, preferably lying on a horizontal plane, for example parallel to the axis of rotation R. In the illustrated embodiment, this rotation with respect to the axis K is the only degree of freedom of the roller <NUM> with respect to the frame. However, it is not excluded that the roller could also be tilting with respect to a horizontal axis perpendicular to the K axis.

The roller has an elongated shape along a longitudinal axis and is arranged with a longitudinal axis parallel to the axis of rotation K.

Under normal conditions of use, the roller <NUM> contacts the ground.

In the preferred embodiment the roller is idle, however it is not excluded that it can be motorized and rotated by a suitable mechanism.

This roller has (only) two opposite longitudinal ends of chamfered shape, i.e. at least at the opposite longitudinal ends the area of a cross section of the roller (identified by the intersection of the roller with an imaginary section plane perpendicular to the longitudinal axis) gradually decreases with respect to the area of a cross section of a central portion of the roller.

This chamfer, i.e. the portion in which the cross-sectional area gradually decreases, has a length equal to or greater than <NUM> measured along a direction parallel to the longitudinal axis of the roller <NUM>, i.e. parallel to the axis of rotation K. It is not excluded that from a plane of central symmetry perpendicular to the longitudinal axis of the roller, the roller always has a decreasing section area running from this plane to the respective longitudinal ends.

At the point where the cross section of a longitudinal end is smaller, it has an area of less than at least <NUM>/<NUM> of the cross section of a central portion of the roller.

Said longitudinal ends, i.e. the chamfers, truncated conical in shape, i.e. at least at the longitudinal ends the roller <NUM> comprises respective outer surfaces that are truncated conical in shape.

For the avoidance of doubt, it should be noted that these surfaces have a greater circumference in their portion that is closer to the central portion of the roller.

For example, these conical surfaces are inclined at an angle comprised between <NUM>° and <NUM>° with respect to the longitudinal axis of the roller.

In the illustrated embodiment, the roller comprises a cylindrical central portion from which the two truncated conical surfaces present at the longitudinal ends extend in the distancing direction.

The roller, at least in the central portion thereof, i.e. the cylindrical one, has a diameter of less than half of the diameter of the wheel <NUM>.

The roller <NUM> can be rigid, i.e. not deformable in bending or twisting or crushing under the normal work loads to which it is subjected when the wheelchair is used. For example, the roller can be made of plastic.

In all the embodiments illustrated, the wheelchair rests on the ground solely by means of the wheels <NUM> and the roller <NUM>.

The roller <NUM> for resting on the ground can be positioned both in front and behind the pair of wheels <NUM> with respect to the normal forward direction of the wheelchair.

It is not excluded that, in a less preferred and not illustrated embodiment, the other element for resting on the ground may comprise a pair of wheels, for example of smaller diameter than the pair of wheels <NUM>. That is, in an embodiment not illustrated, the wheelchair does not comprise the roller <NUM>, but is in any case provided with the drive arrangement of the wheels as described above.

With particular reference to <FIG> and <FIG>, in addition to the roller <NUM>, when the roller <NUM> is placed in front of the pair of wheels <NUM>, the wheelchair can comprise a further roller <NUM> associated with the frame, for example rotatably associated with it in an idle manner, and positioned behind the pair of wheels <NUM>.

In particular, it is rotatably associated with the frame according to an axis of rotation parallel to the axis of rotation R.

The further roller <NUM> is positioned so as not to touch the ground when the wheelchair is located on a flat, horizontal surface. In practice, when the chair touches the ground by means of the pair of wheels <NUM> and the roller <NUM>, the roller <NUM> is raised from the ground. In this way, the further roller <NUM> offers a backward anti-tipping function for the wheelchair, without hindering the forward movement under normal conditions.

The wheelchair described herein is available in different embodiments which combine differently the described features.

<FIG> and <FIG> illustrates a first embodiment of the wheelchair indicated with 1a and which differs in particular from the other embodiments in that the drive arrangement comprises the rollers <NUM> and in that the roller <NUM> is positioned in front of the pair of wheels <NUM>.

<FIG> illustrates a second embodiment of the wheelchair indicated with 1b, which has the same characteristics as the embodiment indicated with 1a and which in addition is provided with the further roller <NUM>.

<FIG> illustrates a third embodiment of the wheelchair indicated with 1c, which has the same characteristics as the embodiment indicated with 1a except for the fact that in the form of action 1c the roller <NUM> is placed behind the pair of wheels <NUM> instead of at the front as in 1a.

<FIG> illustrates a fourth embodiment of the wheelchair indicated with 1d, which has the same characteristics as the embodiment indicated with 1a except for the fact that in the form of action 1d the drive arrangement is the one of the second embodiment of the drive arrangement, i.e. the drive arrangement in place of the roller that contacts the wheel comprises the pulleys connected by the flexible connecting member.

<FIG> illustrates a fifth embodiment of the wheelchair indicated with 1e, which has the same characteristics as the embodiment indicated with 1d and which in addition is provided with the further roller <NUM>.

<FIG> illustrates a sixth embodiment of the wheelchair indicated with 1f, which has the same characteristics as the embodiment indicated with 1d except for the fact that in the form of action 1f the roller <NUM> is placed behind the pair of wheels <NUM> instead of front as in 1d.

The operation of the wheelchair according to the invention is as follows.

To drive forward or backward or forward/backward simultaneously with the steering, the wheels <NUM> are selectively or simultaneously set in rotation by means of the driving torque generated by the electric motor <NUM>, i.e. by the two electric motors <NUM>, which being located at a high height compared to known wheelchairs, are protected from water, thus allowing them to tackle streams or bodies of water of considerable depth.

Claim 1:
A wheelchair (1a,1b,1c,1d,1e,1f) comprising:
- a frame (<NUM>),
- a pair of wheels (<NUM>) for resting on the ground each rotatably associated with the frame (<NUM>), and
- a roller (<NUM>) for resting on the ground associated with the frame (<NUM>),
wherein the roller develops longitudinally along a longitudinal axis and is provided with a pair of opposite longitudinal ends, which are chamfered.