Self-balancing wheelchair parking device

Abstract

To provide an electric wheelchair capable of traveling in a nearly horizontal position even when placed on a traveling surface that is not completely flat, or is inclined, uneven, or curved. [Solution] A parking device (10, 10') for an electric self-balancing wheelchair (100), which is connected to a base (20) of the electric self-balancing wheelchair (100) by a pair of levers (30, 40), each of which is connected by a proximal lever (32, 42) to a shared gear (50, 50') drivable by a gear motor assembly (60, 60') constrained and preferably keyed to one of the levers (30, 40), each of the proximal levers (32, 42) being articulated to a respective distal lever (34, 44). In the parking device (10, 10'), each of the distal levers (34, 44) is connected to the base (20) of the wheelchair (100) by a respective guide (36, 46) and has a respective support leg (39, 49) for supporting it on the ground. The parking device (10, 10') is characterized in that the shared gear (50, 50') has a pair of gears (31, 41) that mesh with each other, each of the gears (31, 41) being integrated with the respective proximal levers (32, 42) of the pair of levers (30, 40) and having its own rotation axis (X, X'), and the pair of gears (31, 41) rotate simultaneously by operation of the gear motor assembly (60, 60') to drive the levers (30, 40) up and down.

Description

[Technical field]

[0001] The object of the invention is, for example but not exclusively, a self-balancing wheelchair parking device, or rather an electric self-balancing wheelchair parking device, for the transport of at least one person or for robotic applications, i.e. applications without a occupant. [Background technology]

[0002] It is well known that there are electric self-balancing wheelchairs for people with partial motor impairment of the lower limbs. Specifically, there are electric wheelchairs for transporting people in a seated position, which include a user-operable base for operating the electric wheelchair, two wheels arranged on both sides of the base and supported on a running surface, and a support frame integrally bound to the base and equipped with a seat. In particular, this type of electric wheelchair also includes a means for self-balancing its weight under all operating conditions, which is also used in a human transport device known as SEGWAY (registered trademark).

[0003] Such self-balancing, or balancing, means for balancing the weight of the wheelchair is housed within this base, along with additional means for changing the forward direction of the wheelchair. In this type of wheelchair, forward and / or rearward movement is achieved by a forward / rearward imbalance of the user's body.

[0004] The wheelchair is activated when a person sits in the wheelchair seat, using the user's weight to detect the user's presence and activate the wheelchair's power operation.

[0005] However, this type of wheelchair has the disadvantage that it is only equipped with two wheels arranged parallel and opposite each other, making it unstable when not in operation, i.e. when the internal motor is not running.

[0006] Even when the motor is running, possible unexpected external forces can cause the wheelchair to lose stability when in a stable resting position, with very dangerous consequences.

[0007] In this regard, however, the wheelchair is equipped with support means (so-called "parking assemblies or devices") for supporting the wheelchair on the running surface when it is maintained in an inoperative or parked position.

[0008] Patent document 1 illustrates a stabilization assembly applicable to a powered self-balancing wheelchair for transporting at least one person, comprising a platform arranged between a pair of powered coaxial wheels, carrying load detection means arranged to detect the presence of a driver on the platform and to activate an electronic steering unit adapted to control the powered wheels in response to changes in balance. The stabilization assembly includes a lever controlling a pair of supports respectively locatable at the front and rear of the platform, selectively movable by the driver on the seat between a ground-supported lowered position and an inoperable raised position.

[0009] The leverage of known stabilization assemblies can be controlled by the user himself through manually operated levers or bars located to the side and under the seat of the wheelchair.

[0010] Patent Document 2 illustrates an electric self-balancing wheelchair for transporting at least one person, which includes a base operable to operate the electric self-balancing wheelchair, and two wheels arranged on both sides of the base and supported on a running surface. The electric self-balancing wheelchair includes a support frame integrally bound to the base and equipped with a seat, and a support means for supporting the wheelchair on a running surface at least when in an inoperative state. The support means includes at least one leg that can be supported on the ground. It also includes a means for moving and locking the leg between a raised position and a lowered position. The leg is locked in a lowered position at least when in contact with the running surface so that the wheelchair is supported in a substantially horizontal position.

[0011] Patent document 3 describes a wheelchair with a seat attached to a gyropod, where, as is known, the term gyropod refers to an individual motorized vehicle consisting of a platform with two parallel wheels (in this case the platform supporting the "chair") and equipped with a gyro stabilization system. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] International Publication No. 2012 / 017335 [Patent Document 2] European Patent Application Publication No. 2606867 [Patent Document 3] French Patent Application Publication No. 3106492

[0013] Thanks to the Gyropod's gyro stabilization system, when the user leans forward, the center of gravity of the wheelchair-user assembly moves forward, which in turn sends a signal to the powered wheels to move the wheelchair forward along its longitudinal axis. Similarly, when the user leans back, the center of gravity of the wheelchair-user assembly moves backward, which generates a signal for the powered wheels to move the wheelchair backward along its longitudinal axis.

[0014] In particular, the gyro stabilization system comprises an electronic board adapted to calculate in real time the center of gravity of the wheelchair in which the user is riding from data received from a series of sensors. The electronic board then controls the motorized wheels based on the calculated center of gravity position. The sensors are, for example, accelerometers or gyroscopes. The sensors and the electronic board are housed in an electronic box, for example, placed transversely between the wheels.

[0015] The device allows the actuation system to be deactivated when the support is in the rest position and the user is seated to prevent unwanted movement of the wheelchair, and also provides a mechanical connection means adapted to hook the actuation system 35 when the legs are in the retracted position and to unhook the actuation system when the legs are in the deployed position while the user is seated.

[0016] Finally, the chair includes a pair of shanks, the first of which has intermeshing toothed ends. Summary of the Invention [Problem to be solved by the invention]

[0017] However, the problem of keeping the wheelchair stationary on both flat and steep terrain is not addressed in this document.

[0018] Therefore, an object of the present invention is to provide an electric wheelchair that can run in a substantially horizontal position even when placed on a running surface that is not completely flat, or that is inclined, uneven, or curved.

[0019] A further object of the present invention is to provide an electric wheelchair that can solve the problems of the known art by mechanical elements only, without introducing an additional complex electronic control system. [Means for solving the problem]

[0020] These objects are achieved by a parking device for an electric self-balancing wheelchair, which is connected to a base of the electric self-balancing wheelchair by a pair of levers, each of said levers being connected by a proximal lever to a shared gear drivable by a gear motor assembly constrained to one of said levers and preferably keyed, each of said proximal levers being articulated to a respective distal lever, each of said distal levers being guided along a respective guide, said guide being constrained to the base of the wheelchair and having a respective support leg for support on the ground, said shared gear having a pair of gears meshing with each other, each of said gears being integrated into the respective proximal lever of said pair of levers and having its own axis of rotation, and wherein operation of said gear motor assembly causes said pair of gears to rotate simultaneously, driving said levers up and down.

[0021] Advantages of this embodiment include the fact that the device of the present invention can be used to stationary a wheelchair on both flat and steep terrain.

[0022] According to one embodiment of the present invention, the shared gear is accommodated in a holder that fulcrums on a rotation axis different from the rotation axis of the gear.

[0023] The advantage of this embodiment is that the swing system of the motor-hinged holder allows the wheelchair to remain stationary even on steep slopes.

[0024] Specifically, the first part of the movement involves lowering the legs: as either leg hits the ground, the holder swings the second leg over until it also hits the ground.

[0025] This minimizes the force applied to one leg and creates a support reaction when both legs are on the ground.

[0026] According to one embodiment of the present invention, a gear motor assembly includes a pair of motors acting on a shared gear.

[0027] The advantage of this solution is that if one of the two motors fails, the other motor remains to ensure the movement, especially the simultaneous movement of the two proximal levers.

[0028] According to a further embodiment of the invention, the parking device further comprises a locking system which restricts the degree of freedom of the lever and gear motor system when both legs are on the ground in order to ensure the stability of the parking device.

[0029] The advantage of this solution is that the locking system ensures the stability of the parking device, as otherwise applying a torque to the base would cause it to rotate and the wheelchair to move forward, making the parking device unstable.

[0030] Further features of the invention can be inferred from the dependent claims.

[0031] Further characteristics and advantages of the invention will become apparent from the following description, given by way of non-limiting example with the aid of the figures depicted in the attached drawings, in which: [Brief description of the drawings]

[0032] [Figure 1] FIG. 1 is a side view of an electric self-balancing wheelchair equipped with a parking device according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a side view of the parking device of FIG. 1 in a stowed position when the wheelchair is on a flat surface. [Diagram 3] 2 is a side view of the parking device of FIG. 1 in an extended position in contact with the ground when the wheelchair is on a flat surface. [Figure 4]FIG. 2 is a side view of the parking device of FIG. 1 in a stowed position when the wheelchair is on a slope with a gradient of 10°. [Diagram 5] 2 is a side view of the parking device of FIG. 1 in an extended position in contact with the ground when the wheelchair is on a slope with a gradient of 10°. [Figure 6] FIG. 2 is a side view of the parking device of FIG. 1 in a stowed position when the wheelchair is on a slope with a gradient of 15°. [Figure 7] 2 is a side view of the parking device of FIG. 1 in an extended position in contact with the ground when the wheelchair is on a slope with a gradient of 15°. [Figure 8] 2 is a side view of the parking device of FIG. 1 in a stowed position when the wheelchair is on a slope with a gradient of 20°. [Figure 9] 2 is a side view of the parking device of FIG. 1 in an extended position in contact with the ground when the wheelchair is on a slope with a gradient of 20°. [Figure 10] FIG. 13 is a side view of a portion of a powered self-balancing wheelchair equipped with a parking device according to an alternative embodiment of the present invention. [Figure 11] FIG. 11 is a side view of the parking device of FIG. 10 in a stored position. [Figure 12] FIG. 11 is a side view of the parking device of FIG. 10 in an extended position. [Figure 13] FIG. 11 is a side view of the parking device of FIG. 10 in a laterally extended position. [Figure 14] FIG. 11 is a side view of the locking system of the parking arrangement of FIG. 10 in the locked position. [Figure 15] FIG. 11 is a side view of the locking system of the parking arrangement of FIG. 10 in an unlocked position. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0033] The invention will now be described with particular reference to the accompanying drawings.

[0034] In particular, FIG. 1 illustrates a side view of a powered self-balancing wheelchair equipped with a parking device, generally designated 100, according to one embodiment of the present invention.

[0035] In order to explain the invention in more detail, it should be clarified that the electric self-balancing wheelchair 100 can be used, for example but not limited to, for people with partial loss of motor skills in the lower limbs or for robotic applications.

[0036] Such a wheelchair comprises a base 20 which can be operated by the user to operate the wheelchair, two wheels 110 located on either side of the base 20 and supported on the running surface, and a support frame 120 which is integrally attached to the base and is equipped with a seat 130.

[0037] In particular, this type of electric wheelchair also has means for self-balancing its weight under all working conditions, for example of the type used in devices for transporting people known under the name SEGWAY®.

[0038] Such self-balancing, or balancing, means for balancing the weight of the wheelchair are housed within said base, together with additional means for changing the forward direction of the wheelchair. In this type of wheelchair, forward and / or backward movement, and possibly (steering) direction, is achieved by unbalancing the user's body forward and / or backward, or even to the side.

[0039] Alternatively, or in addition, the drive handlebars may contribute to determining, or solely determining, the forward and / or rearward movement of the vehicle in addition to the direction of travel (steering) of the same vehicle.

[0040] Further, in some preferred embodiments, activation of the wheelchair is accomplished when a person sits in the wheelchair seat and their weight is used to detect the user's presence and activate the power operation of the wheelchair.

[0041] Alternatively, simultaneous detection of the user's weight and the user's manipulation of the manual controls is necessary to operate the wheelchair.

[0042] The self-balancing wheelchair described herein, according to one aspect of the invention, is provided with a parking device of the type having support legs that can be lowered and raised, which is preferably manually activated by an operator and which only begins to operate when the wheelchair is stationary.

[0043] FIG. 2 shows a side view of the parking device of the present invention, generally designated 10, in a stowed position when the wheelchair is on a flat surface.

[0044] In particular, the parking device 10 of the present invention is connected to the base 20 of the self-balancing wheelchair 100 by a pair of front and rear levers 30, 40.

[0045] Each of the aforementioned levers 30,40 is connected by a proximal lever 32,42 to a shared gear 50 drivable by a gear motor assembly 60 keyed or in any other way constrained to one of the aforementioned levers 30,40.

[0046] Specifically, the gear motor assembly 60 includes a pair of motors M, M′ that act on the worm screw 51 .

[0047] More specifically, the front lever 30 is connected to the shared gear 50 via a proximal lever 32 and the rear lever 40 is connected to the shared gear 50 via a proximal lever 42 .

[0048] The gear motor assembly 60 is preferably keyed to one of the levers 30,40, for example the front lever 30 or the rear lever 40.

[0049] The proximal lever 32 of the front lever 30 is articulated to the distal lever 34 of the front lever 30 and the proximal lever 42 of the rear lever 40 is articulated to the distal lever 44 of the rear lever 40 .

[0050] Specifically, in the embodiment of the invention shown herein, the proximal lever 32 of the front lever 30 is articulated at one end to an end of a respective distal lever 34, and similarly, the proximal lever 42 of the rear lever 40 is articulated at one end to an end of a respective distal lever 44.

[0051] Because the distal lever 34 of the front lever 30 has a support leg 39 that rests on the ground, and the distal lever 44 of the rear lever 40 has a support leg 49 that rests on the ground, the assembly of the front lever 30 and the rear lever 40 forms the mechanical equivalent of a "shank" of the power wheelchair 100, i.e., the power wheelchair 100 itself is provided with front and rear support when the power wheelchair 100 is parked on a flat surface or along a slope.

[0052] The support legs 39, 49 of the distal levers 34, 44 of the front lever 30 and rear lever 40 are formed at the ends of the distal levers 34, 44 that are not engaged with the respective proximal levers 32, 42.

[0053] Each of the distal levers 34 , 44 is connected by a respective guide 36 , 46 (eg in the form of a sliding block) to a respective connecting lever 38 , 48 fixed to the base 20 of the electric wheelchair 100 .

[0054] Specifically, the distal lever 34 of the front lever 30 is connected to a front connecting lever 38 via a front guide 36, and this front connecting lever 38 is fixed to the base 20 of the electric wheelchair 100, while the distal lever 44 of the rear lever 40 is connected to a rear connecting lever 48 via a rear guide 46, and this rear connecting lever 48 is also fixed to the base 20 of the electric wheelchair 100.

[0055] The front guide 36 and the rear guide 46 allow the respective distal lever 34 , 44 to slide and rotate relative to the respective connecting lever 38 , 48 , and more specifically relative to the ends of the connecting levers 38 , 48 that are fixed to the base 20 .

[0056] Alternatively, other ways of connecting the distal levers 34, 44 to the base 20 of the electric wheelchair 100 are possible by general guides 36, 46 (understood herein in the general sense of mechanical constraints) that connect these distal levers 34, 44 to the base 20 and allow preferential rotational movement of the distal levers 34, 44 relative to the base 20. For example, guides 36, 46 consisting of sliding blocks hinged directly to the base 20 and on which the respective distal levers 34, 44 slide can be used, or other known mechanical constraints that allow for expected relative movement between the distal levers 34, 44 and the base 20 can be used.

[0057] The shared gear 50 has a pair of gears 31,41, each of which is integral with a respective proximal lever 32,42 of a respective lever 30,40.

[0058] More specifically, the shared gear 50 is integrated with the proximal front lever 32 of the front lever 30 and has a front toothed wheel 31 having an axis of rotation X.

[0059] Furthermore, the shared gear 50 is integrated with the proximal rear lever 42 of the rear lever 40 and has a rear toothed wheel 41 having a rotation axis X'.

[0060] In addition, in the shared gear 50, the front gear 31 meshes with the rear gear 41.

[0061] Furthermore, the shared gear 50 is accommodated in a holder 59 that fulcrums a rotation axis C that is different from the rotation axes X, X' of the gears 31, 41.

[0062] The parking device 10 for the electric self-balancing wheelchair 100 is operated as follows.

[0063] By operating the gear motor assembly 60, the pair of gears 31, 41 rotate simultaneously, thereby driving the front lever 30 and the rear lever 40 described above up and down.

[0064] Specifically, in the case of Figures 2 and 3, the parking device 10 switches from the stored position to the extended position when the wheelchair 100 is on a flat surface.

[0065] Actuation of the gear motor assembly 60 and the resulting simultaneous rotation of the pair of gears 31, 41 causes the proximal lever 32 of the front lever 30 to rotate about its axis of rotation X and the proximal lever 42 of the rear lever 40 to rotate about its axis of rotation X'.

[0066] The proximal lever 32 acts on the distal lever 34 which is guided downwardly by the guide 36 until it contacts the ground, and similarly, the proximal lever 42 acts on the distal lever 44 which is guided downwardly by the guide 46 until it contacts the ground, thereby bringing the configuration of the parking device 10 into the position shown in FIG. 3.

[0067] By operating the gear motor assembly 60 in the opposite direction, the parking device 10 can repeat the same motion described above in reverse, bringing the parking device 10 from the extended position to the stowed position.

[0068] FIG. 4 is a side view of the parking device of FIG. 1 in a stowed position when the wheelchair is on a slope with a gradient of 10°.

[0069] Actuation of the gear motor assembly 60 and the resulting simultaneous rotation of the pair of gears 31, 41 causes the proximal lever 32 of the front lever 30 to rotate about its axis of rotation X and the proximal lever 42 of the rear lever 40 to rotate about its axis of rotation X'.

[0070] The proximal lever 32 acts on a distal lever 34 which is guided downwards by a guide 36 until it contacts the ground, and similarly, the proximal lever 42 acts on a distal lever 44 which is guided downwards by a guide 46.

[0071] However, unlike the previous case, the wheelchair 100 is placed on a slope having a gradient of 10°, so in this case the distal lever 34 and each leg 39 contact the ground T earlier than the distal lever 44 and its leg 49 contact each other.

[0072] At the moment when the distal lever 34 and each leg 39 contact the ground T, the shared gear 50 rotates about its center of rotation C, allowing the distal lever 44 and each leg 49 to also contact the ground T, so that the parking device is guided to the position shown in FIG. 5, with the base 20 still remaining in a horizontal position.

[0073] Again, by operating the gear motor assembly 60 in the opposite direction, the parking device can be caused to repeat the same operations in reverse to bring the parking device from the extended position to the stowed position, i.e., the position shown in FIG.

[0074] Figures 6 and 7 show a similar movement to that shown in Figures 4 and 5 above, the only difference being that in this case the wheelchair 100 is on a slope with a gradient of 15°.

[0075] In this case, in the final position shown in FIG. 7, the shared gear 50 is more inclined than in the position shown in FIG. 5, but the base 20 still remains in a horizontal position.

[0076] Figures 8 and 9 show a similar movement to that shown in Figures 4 and 5 above, the only difference being that in this case the wheelchair 100 is on a slope with a gradient of 20 degrees.

[0077] In this case, in the final position shown in FIG. 9, the shared gear 50 is more inclined than in the position shown in FIG. 7, but the base 20 remains in a horizontal position.

[0078] The parking device 10 further includes a locking system that restricts the degree of freedom of the system formed by the levers 30, 40 and the gear motor 50 when both legs 39, 49 are in contact with the ground.

[0079] The locking system is shown in the locked position in FIG. 14 and in the unlocked position in FIG.

[0080] In particular, the locking system comprises a pair of electromagnets E, E' adapted to drive the toothed element 200 from a first position, in which the toothed element 200 is hooked by a crown wheel 210 integrated in the support frame 120 of the self-balancing wheelchair 100, to a second position, in which the toothed element 200 is unhooked from said crown wheel 210.

[0081] In this first position, the locking system ensures the stability of the parking device 10. Otherwise, applying a torque to the base 20 would cause the base 20 to rotate and drive the wheelchair 100 forward, making the parking device 10 unstable.

[0082] Furthermore, when a pair of electromagnets E, E' is activated, the hook of the crown wheel 210 is disengaged, and the locking system is unlocked.

[0083] FIG. 10 is a side view of a portion of a powered self-balancing wheelchair equipped with a parking device 10' according to an alternative embodiment of the present invention.

[0084] This embodiment differs from the embodiment of Figures 1 to 9 in that it provides a gear motor assembly 60' which drives a shared gear 50' including a worm screw 51 acting on a gear 52 which in turn drives an additional gear 54 which meshes with the rear gear 41 of the shared gear 50'.

[0085] Again, the gear motor assembly 60' comprises a pair of motors M, M' acting on the worm screw 51 as previously described.

[0086] The rotation of the rear gear 41 of the shared gear 50' is transmitted to the front gear 31 of the shared gear 50' in the same manner as described above.

[0087] Alternatively, the kinematics described above can be reconfigured so that the additional gear 54 meshes with the front gear 31 of the shared gear 50'.

[0088] In particular, operation of the gear motor assembly 60' actuates the worm screw 51, which in turn rotates the pair of gears 31, 41 simultaneously in accordance with the motion mechanism described above, causing the proximal lever 32 of the front lever 30 to rotate about its rotation axis X and the proximal lever 42 of the rear lever 40 to rotate about its rotation axis X'.

[0089] The proximal lever 32 acts on a distal lever 34 which is guided downwards by a guide 36 until it contacts the ground, and similarly, the proximal lever 42 acts on a distal lever 44 which is guided downwards by a guide 46.

[0090] Specifically, the distal lever 34 is guided by the guide 36 by virtue of the cam 37 present on the distal lever 34 itself, while the distal lever 44 is guided by the guide 46 by virtue of the cam 47 present on the distal lever 44 itself, so that the parking device 10' switches from the stowed position of FIG. 11 to the extended position of FIG. 12.

[0091] By operating the gear motor assembly 60' in the opposite direction, the parking device 10' can repeat the same movements described above in reverse, bringing the parking device 10' from the extended position (FIG. 12) to the stowed position (FIG. 11).

[0092] When the wheelchair 100 is on a slope, the moment the distal lever 34 and each leg 39 contact the ground T, the shared gear 50' rotates about its rotation center C', allowing the distal lever 44 and each leg 49 to contact the ground T, thereby leading the parking device 10' to the position shown in Figure 13.

[0093] Leg 39 can be articulated to distal lever 34 in the same way that leg 49 can be articulated to distal lever 44 to provide better ground support for the parking apparatus 10'.

[0094] In any of the embodiments described, the gear motor assemblies 60, 60' may be electrically driven, for example with suitable controls available to the user of the wheelchair 100.

[0095] Changes or modifications suggested for incidental or specific reasons can be made to the invention described above without thereby departing from the scope of the invention.

[0096] For example, in order to rotate the proximal levers 32, 42 simultaneously about the X and X' axes and achieve the same result in terms of the kinematics, two electronically synchronized motors can be installed instead of a pair of motors acting on a worm screw. [Explanation of symbols]

[0097] 10, 10' Parking Equipment 20 Base 30 Front Lever 31 Front Gear 32 Proximal Lever 34 Distal Lever 36 Front guide 37 Cam 38 Front connection lever 39 Support legs 40 Rear Lever 41 Rear Gear 42 Proximal Lever 44 Distal Lever 46 Rear guide 47 Cam 48 Rear connection lever 49 Support legs 50, 50' Shared Gear, Gearmotor 51 Worm screw 52 Gears 54 Additional Gears 59 Holder 60, 60' Gearmotor Assembly 100 Electric self-balancing wheelchair 110 wheels 120 Support Frame 130 seats 200 Toothed elements 210 Crown Wheel C, C' Rotation axis, center of rotation E, E' electromagnet M, M' motor T ground X, X' rotation axis

Claims

1. A parking device (10, 10') for an electric self-balancing wheelchair (100), said parking device (10, 10') being connected to a base (20) of said electric self-balancing wheelchair (100) by a pair of levers (30, 40), each of said levers (30, 40) being connected by a proximal lever (32, 42) to a shared gear (50, 50') drivable by a gear motor assembly (60, 60') constrained and preferably keyed to one of said levers (30, 40), each of said proximal levers (32, 42) being articulated to a respective distal lever (34, 44), each of said distal levers (34, 44) being articulated to a respective guide a parking device (10, 10') including a pair of gears (31, 41) that mesh with each other, each of the gears (31, 41) being integrated into the proximal lever (32, 42) of each of the pair of levers (30, 40) and having its own rotation axis (X, X'), and the pair of gears (31, 41) rotate simultaneously by operation of the gear motor assembly (60, 60') to drive the levers (30, 40) up and down.

2. 2. The parking device (10') according to claim 1, characterized in that the shared gear (50') comprises a worm screw (51) acting on a gear (52) which drives an additional gear (54) which meshes with one of the gears (31, 41) of the shared gear (50').

3. The parking device (10, 10') according to claim 1 or 2, characterized in that the shared gear (50, 50') is housed in a holder (59) whose fulcrum is a rotation axis (C) different from the rotation axis (X, X') of the gears (31, 41).

4. 3. The parking device (10, 10') according to claim 2, characterized in that the gear motor assembly (60, 60') comprises a pair of motors (M, M') acting on the worm screw (51).

5. 2. The parking device (10) of claim 1, wherein each of the distal levers (34, 44) is connected by a respective guide (36, 46) to a respective connecting lever (38, 48) fixed to the base (20).

6. The parking device (10, 10') according to claim 1, further comprising a locking system which restricts the degree of freedom of the system consisting of the levers (30, 40) and the shared gear (50, 50') when both of the support legs (39, 49) are in contact with the ground in order to ensure the stability of the parking device (10, 10').

7. 7. The parking device (10, 10') according to claim 6, characterized in that the locking system comprises a pair of electromagnets (E, E') adapted to drive the toothed element (200) from a first position in which the toothed element (200) is hooked by a crown wheel (210) integrated in the support frame of the electric self-balancing wheelchair (100) to a second position in which the toothed element (200) is unhooked from the crown wheel (210).

8. The parking device (10, 10') according to claim 1, characterized in that the support legs (39, 49) supported on the ground are adapted to be articulated to the corresponding distal levers (34, 44) to provide the parking device (10, 10') with better support on the ground.

9. The parking device (10, 10') according to claim 1, characterized in that the distal levers (34, 44) are guided by their respective guides (36, 46) via cams (37, 47) present on the distal levers (34, 44) themselves, to switch the parking device (10, 10') from a stowed position to an extended position or vice versa.

10. 2. The parking device (10, 10') according to claim 1, characterized in that the gear motor assembly (60, 60') can be driven electrically.

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